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Abstract

Cardiovascular diseases are chronic inflammatory diseases that affect a large segment of society. Coronary heart disease (CHD), the most common cardiovascular disease, progresses over several years and affects millions of people worldwide. Chronic infections may contribute to the systemic inflammation and enhance the risk for CHD. Periodontitis is one of the most common chronic infections that affects up to 50% of the adult population. Under inflammatory conditions the activation of endogenous degradation pathways mediated by immune responses leads to the release of destructive cellular molecules from both resident and immigrant cells. Matrix metalloproteinases (MMPs) and their regulators can activate each other and play an important role in immune response via degrading extracellular matrix components and modulating cytokines and chemokines. The action of MMPs is required for immigrant cell recruitment at the site of inflammation. Stimulated neutrophils represent the major pathogen-fighting immune cells that upregulate expression of several proteinases and oxidative enzymes, which can degrade extracellular matrix components (e.g. MMP-8, MMP-9 and neutrophil elastase). The activity of MMPs is regulated by endogenous inhibitors and/or candidate MMPs (e.g. MMP-7). The balance between MMPs and their inhibitors is thought to mirror the proteolytic burden. Thus, neutrophil-derived biomarkers, including myeloperoxidase, may activate proteolytic destructive cascades that are involved in subsequent immune-pathological events associated with both periodontitis and CHD. Here, we review the existing studies on the contribution of MMPs and their regulators to the infection-related pathology. Also, we discuss the possible proteolytic involvement and role of neutrophil-derived enzymes as an etiological link between chronic periodontitis and CHD.

Keywords

cardiovascular disease coronary artery disease gingival crevicular fluids hypochlorous acid lipopolysaccharide matrix metalloproteinases myeloperoxidase neutrophils oral infections periodontal diseases tissue inhibitor of matrix metalloproteinases

Introduction

Chronic periodontitis

Chronic periodontitis (CP), the most prevalent form of periodontitis, is defined as an inflammatory disease of the tooth-supporting structures. CP is caused by a complex interplay between host defense and biofilm dysbiosis indicated by growth of specific pathogens or complexes of pathogens colonizing the subgingival area. To challenge the microbial biofilm and its virulence factors (LPS, enzymes and toxins), an immune-inflammatory response develops. Resident tissue cells induce and produce pro-inflammatory mediators, which enhance the recruitment of inflammatory cells (primarily neutrophils) at the site of inflammation. Once neutrophils reach the inflamed sites, they aggregate, form a wall separating the epithelium from the bacterial biofilm, degranulate large quantities of tissue destructive enzymes [e.g. matrix metalloproteinase (MMP)-8, MMP-9 and neutrophil elastase (NE)] and generate ROS.^1–3 These cascades result in collagen loss and further progressive breakdown of soft and hard tissues of the periodontium, leading to pocket formation and/or recession. If not treated, CP eventually leads to tooth loss.^4–6

When periodontitis progresses the predominance of Gram-positive bacterial species in the biofilm changes majorly into Gram-negative species.^7,8 According to culture and DNA hybridization techniques, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, Tannerella forsythia and Aggregatibacter actinomycetemcomitans are considered to be etiologically linked with periodontal diseases (PDs) or frequently found in pathological periodontal conditions.^7,8 Culture-independent studies have expanded the range of disease-associated organisms,⁹ and around 1000 bacterial species have been found in the oral cavity.¹⁰ Periodontal bacteria or their products, for example LPS, may enter the bloodstream through inflamed periodontal tissues, especially after dental treatment,^11–13 gentle mastification or tooth brushing.^12,14 Similarly as during the acute-phase response, in periodontitis patients and... during the acute-phase response in periodontitis patients and in a mouse model infected with A. actinomycetemcomitans,^15–17 most of the endotoxin activity is found in the pro-atherogenic lipoprotein fraction. This alteration is considered to promote pro-atherogenic properties of the lipoproteins, including activation of macrophages and accumulation of cellular cholesterol.¹⁸ Long-term or repeated episodes of bacteremia and endotoxemia are undoubtedly threats to general health in both healthy people and those with metabolic disorders.^19–24

Coronary heart disease

Coronary heart disease (CHD) progresses over several years and affects millions of people worldwide. The disease may lead to acute coronary syndrome (ACS) [unstable angina pectoris and myocardial infarction (MI)] which is considered as the major cause for mortality in patients with cardiovascular diseases (CVD).²⁵ Atherosclerosis is the underlying cause for CHD and represents a multifactorial degenerative disease of large- and medium-sized arteries. It leads to lipid-rich plaque formation, artery wall thickening and atheroma development. The incidence of atherosclerosis cannot be fully explained by classical risk factors. The hypothesis of infection as a potential cause of atherosclerosis has gained favour and is supported by a large body of epidemiological evidence.^25–28 Inflammation is thought to contribute to the progression of atherosclerotic lesions and may also have a fundamental role in thrombosis and adverse acute outcomes causing death.²⁹

Association of CP and CHD

Since Mattila et al. addressed an association between oral infections and CHD in 1989,³⁰ numerous epidemiologic studies have revealed a link between CP and CVD.^31–39 Although the findings were modest and no causal association could be found, these studies suggested an independent consistent association that cannot be attributed to common risk factors.³⁷

CP, like other life-long infectious diseases, may affect initiation, development and progression of CHD either directly by bacterial vascular invasion or indirectly through systemic inflammation or antigen cross-reactivity (Figure 1).^40–44 Most importantly, successful treatment of periodontitis has positive effects on CVD-associated risk factors.^45–47

Figure 1.

Schematic representation of principal interactions of neutrophil-derived proteases and the anti-protease shield, addressing a possible mechanistic link between CP and acute manifestations of CVD.

Bacteria may access the circulation during daily routine, oral hygiene procedures and during periodontal therapy.^22,48,49 The epithelial ulceration at the periodontal pocket confers direct access of virulent Gram-negative organisms (e.g. P. gingivalis and A. actinomycetemcomitans) to the blood stream that causes recurrent and transient bacteremia, as well as low-grade systemic inflammation.^12,13,50 Trafficking of phagocytes represents another direct route that periodontal pathogens may circulate in the blood stream, invade endothelial cells and possibly promote atherosclerosis-related vascular inflammation.⁵¹ Systemic challenge to periodontal pathogens and their soluble components induces a major vascular response, which may alter the endothelial integrity; this represents the earliest change in the vascular wall, followed by leukocyte aggregation, cholesterol deposition, atheroma formation and progression, and plaque rupture in further consequence. These hypotheses are confirmed by the detection of multiple periodontal pathogens, as well as their identification at the DNA level, in human atherosclerotic plaques.^29,52–54

Host inflammatory response and molecular mimicry represent another indirect mechanism linking CP and CHD. Periodontal pathogens and virulence factors are capable of inducing systemic inflammation, which, in turn, affects all stages of the atherosclerotic process. Locally secreted pro-inflammatory cytokines such as TNF-α, IL-1 and IL-6 enter circulation, trigger the release of acute-phase reactants (e.g. C-reactive protein) and promote cell activation. This leads to production of adhesion molecules, activation of TLRs and the release of MMPs (e.g. MMP-9) and their regulators [e.g. tissue inhibitors of metalloproteinase-1 (TIMP-1)] and NE, respectively—processes accelerating the development of the atherosclerotic process in the vessel wall.^{41,43,55–57} Cross-reactive auto-antibodies against common antigens of periodontopathogens and the host (e.g. heat shock proteins) generated by molecular mimicry may disturb the immune reaction and contribute to the pathogenesis of PD and CHD, probably via similar activation processes and cascades.^58,59

Appropriate periodontal treatment has been reported to be effective in reducing and improving markers associated with CVD, for example CRP, IL-6, TNF-α, cholesterol levels and endothelial dysfunction.^45–47 Importantly, periodontal treatment may have a beneficial effect also on the function and properties of all lipoprotein classes.^13,18,60 Thus, these reports point towards a causal association between CP and CHD.

A large body of evidence reporting possible pathogenic pathways that may link PD with CHD has been published. The present review will primarily cover the proteolytic role of MMPs and their regulators, as well as the role of myeloperoxidase (MPO), a neutrophil-derived enzyme that gets upregulated during inflammatory diseases,⁶¹ including atherosclerosis, glomerulosclerosis, glomerulonephritis and PD (see below).^62–67

MMPs and their regulators in periodontitis and CHD

The MMP family consists of at least 23 genetically distinct but structurally related zinc- and calcium-dependent endopeptidases, which cooperatively participate in a protease cascade to remodel almost all extracellular matrix (ECM) and basement membrane (BM) constituents. MMPs can process a number of soluble proteins such as cytokines, chemokines and growth factors, and activate individual MMPs, thus generating cascade-type MMP-dependent immune responses (Figures 1 and 2).^68–71 Alternatively, pro-MMPs in cascade can also be activated by microbial proteases, serine proteinases and ROS (Figures 1 and 2). The ability of MMPs to cleave ECM components and to regulate the activity of non-ECM bioactive molecules confers their crucial roles in various physiological and pathological processes such as tissue development, immune responses, remodeling, and in inflammatory and vascular diseases. MMPs are often categorized according to their modular domain structure: (i) collagenases (MMP-1, MMP-8 and MMP-13); (ii) gelatinases (MMP-2 and MMP-9); (iii) stromelysins (MMP-3, MMP-10 and MMP-11); (iv) matrilysins (MMP-7 and MMP-26); (v) membrane-type MMPs (MMP-14, MMP-15-17, MMP-24 and MMP-25); and (vi) others (MMP-12, MMP-19 to MMP-21, MMP-23, MMP-27 and MMP-28).^68,72

Figure 2.

Proteolytic and oxidative activation cascades of MMP-8 and MMP-9 associated with periodontitis and CVD. This activation cascade can be potentiated by microbial proteases, serine proteases, other MMPs and MPO but will be inhibited by TIMP-1.

MMP-8 (collagenase-2)

Upon maturation in the bone marrow, neutrophils (also called polymorphonuclear leukocytes) synthesize and store MMP-8 (also called neutrophil collagenase) in secondary granules as a latent enzyme. In response to various extracellular stimuli neutrophils degranulate and release mature MMP-8. Owing to its collagenolytic properties, MMP-8 is contributing to leukocyte recruitment at the site of inflammation. In addition to neutrophils (the main source of MMP-8), a variety of cells of the non-polymorphonuclear leukocyte lineage, such as monocytes/macrophages, plasma cells, endothelial cells, fibroblasts and epithelial cells, can express MMP-8 during inflammatory processes.^{2,68–70,72–76} MMP-8 can initiate the cleavage of collagen type I–III; most importantly, MMP-8 has a high affinity for type I collagen. Other MMPs, like gelatinases can further cleave the proteolytic products of collagens after the initial cleavage by collagenases.^{69,70,77–80}

Collagen type I is the preferred substrate for MMP-8 that is secreted by different inflamed cells in the atherosclerotic plaque. Type I is the most abundant collagen and the major load-bearing molecule in the atherosclerotic fibrous cap; it is obvious that MMP-8 plays a crucial role in atherosclerosis.⁸¹ Furthermore, MMP-8 degrades apolipoproteins A–I (apoA–I; the major apolipoprotein of high-density lipoproteins) thereby decreasing the anti-atherogenic function of lipoproteins of the high-density range during reverse cholesterol transport.⁸² MMP-8 has been proposed to act as a suitable marker for cardiovascular outcomes.^83–86 An increased expression of MMP-8 was found in activated inflammatory cells covering the shoulder region of the atherosclerotic plaque.^81,87,88 MMP-8 has been found to be released excessively in patients with CVD characterized by plaque progression,⁸⁹ to be significantly elevated in ruptured infarct tissue in patients with MI,⁸⁶ to potentially reflect coronary plaque instability in patients with unstable angina pectoris,⁹⁰ and to be linked with the severity of coronary artery disease and ACS.^91,92 In addition, high serum MMP-8 levels are associated with ACS,⁹³ particularly in patients with acute MI, CVD and cardiac arrest.^86,94–96

MMP-8 is the predominant MMP associated with periodontitis.^69,70 Periodontal pathogens and their virulence factors can activate resident cells to generate inflammatory mediators,^97–99 by which the latent MMP-8 can be proteolytically and oxidatively activated.⁸⁴ Active MMP-8 can degrade type I collagen, the major component of the ECM in the periodontal tissues, leading to undesired destructive lesions. Saliva and gingival crevicular fluids (GCF) are easily and noninvasively collectable diagnostic biological specimens that are useful for the detection of early periodontitis. Monitoring of candidate fluid biomarkers for both oral and systemic conditions is a necessary tool to complement clinical examinations in epidemiological studies. Nonetheless, it should be noted that smoking, variations in the salivary flow rates and other factors may affect the usefulness of oral fluid marker analyses, and thus the levels should be considered with caution when interpreting results.¹⁰⁰ Several studies have shown that MMP-8 levels in oral fluids correlate with the severity of periodontal inflammation, being elevated especially in severe periodontitis.^85,101–109 MMP-8 levels decrease in response to different periodontal treatments such as scaling, root planning or application of the collagenase inhibitor doxycycline.^103,110 Kivelä-Rajamäki et al. even reported that high MMP-8 levels have been identified in an active form in diseased peri-implant sulcular fluids.¹¹¹ To conclude, MMP-8 plays an important role not only in periodontal tissue destruction, but also in periodontal homeostasis and defense.^112,113 However, future studies are required to address whether salivary or mouth rinse analysis of MMP-8, MMP-9, MPO and their regulators can be utilized as potential diagnostic tools in systemic diseases such as CVD.^56,57

MMP-9 (gelatinase B)

Similarly as reported for MMP-8, MMP-9 is mainly synthesized by neutrophils and stored in their intracellular secondary granules as a latent enzyme.¹¹⁴ Upon bacterial challenge activated leukocytes migrate to the site of inflammation and secrete MMP-9 as a latent form, which is activated locally by trypsin, α-chymotrypsin, cathepsin G, plasmin and other MMPs (e.g. MMP-3, MMP-7 and MMP-10) by removal of the pro-peptide (Figure 2).^115–117 In addition to neutrophils, MMP-9 is also secreted by macrophages, smooth muscle cells (SMCs), epithelial and endothelial cells.^{115,118–122} In order to facilitate leukocyte migration, expression and activation of MMP-9 is increased during inflammatory processes, including periodontitis.^{69,70,123–125} In addition to gelatins, MMP-9 cleaves also ECM and BM components such as collagen type IV/V, aggrecan, elastin and other substances, for example IL-1β.^{122,126–130} Expression of MMP-9 can be induced by MMP-7, as well as different cytokines, including IFN-γ, IL-1, IL-2 and TNF-α, respectively.

MMP-9 plays a subtle role in the progression of CVD. Expression of MMP-9 has been described in macrophages, SMCs and endothelial cells derived from atherosclerotic plaque material, particularly at the shoulder region. Furthermore, MMP-9 cleaves type IV collagen and denatured collagen, and may contribute to plaque formation and destabilization via facilitation of medial SMC migration to the intima. Thus, it contributes to degradation of the thin collagen cap that covers cholesterol-rich plaques lining the coronary arteries, which leads to plaque rupture, thrombosis and acute MI.^{88,96,131–134} The active form of MMP-9 is elevated in clinically defined unstable carotid plaque, and MMP-9 levels are significantly higher in ruptured infarct tissue in patients with fatal MI.^84,86,135 Furthermore, elevated serum or plasma levels of MMP-9 have been reported in patients with cardiac arrest, unstable angina and acute MI, or patients with a history of MI.^96,136–138

MMP-9 is considered as one of the major MMPs expressed in periodontitis-affected gingiva. This protease has been found to be associated with severe periodontitis but its levels decrease after successful periodontal intervention.^{69,70,125,139} Elevated serum levels of MMP-9 have also been reported in patients with periodontitis, but decreased significantly after 3 months of non-surgical periodontal intervention.^57,106 One cross-sectional study showed that GCF levels of MMP-8 and MMP-9 correlate with disease activity in patients with PD.¹⁰⁵

MMP-7 (matrilysin-1)

Owing to the absence of the hemopexin-like domain that is common to all other MMPs, MMP-7, the smallest (28 kDa) of the known MMP family members, is less susceptible to inhibition by TIMPs.^140–143 Epithelial MMP-7 is secreted in its latent form and can be effectively activated by plasmin and MMP-3 through proteolytic removal of the pro-domain.^115,144 MMP-7 is secreted by various cells, including epithelial cells and macrophages, but not by neutrophils, and can degrade elastin, laminin, collagen type IV and IX and fibronectin. MMP-7 cannot cleave interstitial collagen, but it can activate latent forms of other MMPs (pro-MMP-1, pro-MMP-2, pro-MMP-8 and pro-MMP-9) (Figure 2), and thus potentiates proteolytic-cascades. MMP-7 plays a key role in both epithelial repair and defense,¹⁴⁰ and it may have a specific role in the intraepithelial cell migration process during renewal of the epithelium when expressed by junctional epithelium.^{111,140,145–147} In addition, MMP-7 may express antimicrobial defense properties in response to bacterial insult by converting antimicrobial pro-defensin peptides into their active forms.¹⁴⁰

MMP-7 is also expressed by lipid-laden macrophages in atherosclerotic lesions, and serum MMP-7 levels are elevated in cardiac arrest patients compared with healthy controls.⁹⁶ Increased MMP-7 expression was found in macrophages and SMCs covering the shoulder regions of the atherosclerotic plaque.¹⁴⁸ Plasma MMP-7 concentrations are elevated in patients with (un)stable coronary artery disease and CVD.^94,149 Furthermore, MMP-7 may contribute to collagenolysis preceding the atherosclerotic plaque rupture by cleaving pro-MMP-8 into active MMP-8.¹⁵⁰

MMP-7 is induced by microbial products such as LPS.¹⁴⁰ Furthermore, MMP-7 was found to be expressed by periodontitis-affected human gingival sulcular epithelium in vivo and in peri-implant sulcular fluid.^111,151 MMP-7 is released in gingival tissues of patients with periodontitis and is elevated in CP.^145,151

TIMPs

TIMPs (TIMP-1–4) are natural MMP inhibitors. Similar to MMPs, TIMPs are expressed at low levels in normal tissues. However, TIMP expression rises during tissue remodeling under both physiological and pathological conditions.^152,153 Although TIMPs can inhibit all individual MMP proteins, the inhibitory effect varies among the different MMP species. Owing to the lack of the hemopexin domain various MMPs are less tightly bound to TIMPs, and therefore are poorly inhibited.¹⁵⁴ The activity of MMP is inhibited via non-covalent binding of the N-terminal portion of TIMP to the C-terminal portion of MMP (Figures 1 and 2).^{68,71,146,153,154} The imbalance between MMPs and their TIMP inhibitors leads to an excessive and undesirable tissue destruction at the site of inflammation.^69,70

Various vascular tissue cells (e.g. endothelial cells, monocytes/macrophages and SMCs) can express TIMP-1. TIMP-1 expression and its release by neutrophils are very low or hardly detectable.^155,156 Through inhibiting MMPs, TIMP-1 blocks SMC migration and thus plays a beneficial role against progression of atherogenesis.¹¹⁵ High serum TIMP-1 levels have been correlated with plaque instability and tissue damage and various forms of CVD (e.g. MI and cardiac mortality),^157,158 and may predict fatal future outcomes.^93,94 The MMP/TIMP ratio may be considered an important parameter affecting atherogenesis.¹³⁷ Furthermore, an increased MMP-8/TIMP-1 ratio was found to be strongly associated with ACS and CVD,^93,137 and thus may be considered as a predictor for coronary risk.⁹⁴

TIMP-1 expression is found in several periodontitis-affected gingival tissue cells such as endothelial cells, monocytes/macrophages, keratinocytes and fibroblasts.¹⁵⁹ In oral samples, the balance between MMPs and TIMPs is regarded to mirror the proteolytic burden.^69,70 Low TIMP-1 levels have been demonstrated in patients with periodontitis compared with controls, and after periodontal treatment these levels appear to rise. Furthermore, the MMP-8/TIMP-1 ratio in salivary and GCFs can be used to discriminate patients with periodontitis from controls.^160–162

NE

NE (also termed polymorphonuclear leukocyte elastase) is a serine protease. Activated neutrophils express and store NE in their primary granules in order to combat bacterial insult, but the enzyme may also contribute to undesired tissue degradation.^163,164 NE can degrade elastin, collagen type I–IV, laminins, fibronectin and proteoglycans.^79,163,164 Moreover, NE is able to degrade ECM by accelerating MMP cascades. NE is also able to activate pro-MMPs, such as pro-MMP-9 and pro-MMP-3, and to inactivate TIMPs, a process that essentially modulates the MMP/TIMP ratio.^165,166 NE can modulate the activity of various cytokines and favor thrombus formation.^116,167 As macrophages present in human lesion material express NE,¹⁶⁸ an enzyme that has been suggested to be associated with an increased risk of CVD and plaque instability.^94,169,170

Furthermore, NE can degrade non-collagenous protein-covered collagen fibrils in the early destructive stages of PDs.¹⁷¹ High serum levels of NE were reported in untreated periodontitis than in periodontally healthy controls.¹⁷² Most importantly, serum NE levels were significantly decreased in response to non-surgical periodontal intervention.¹⁷³

MPO

Another circulating biomarker for CVD/CHD used to predict clinical risk and prognosis of affected patients is MPO.^174–179 The predominant in vivo sources for MPO released during the oxidative burst are neutrophils and monocytes, in which MPO makes up to 5% and 1% in the total cell protein content, respectively. Furthermore, a subpopulation of macrophages expressing MPO is considered to play a particular role in atheroma complication and ACS.^180,181 MPO generates the potent oxidant hypochlorous acid (HOCl) from H₂O₂ and chloride ions. Besides its antimicrobial activity, MPO contributes to degradation of connective tissues by impairing the crucial balance between proteases and anti-proteases. MPO is also present in the ECM in human lesion material;⁶⁴ the enzyme co-localizes with HOCl-modified epitopes/proteins at the endothelial layer and macrophages,^182,183 and most importantly also with MMP-7.¹⁸⁴ As shown by Weiss and coworkers, with pro-MMP-8 and pro-MMP-9,^185,186 and later by Fu et al.,¹⁸⁴ with pro-MMP-7, HOCl may rapidly activate these zymogens, a process apparently depending on the oxidant:enzyme molar ratio.¹⁸⁷ This suggests that HOCl formed by the MPO-H2O2-halide system of activated phagocytes provides an oxidative mechanism for activating latent MMPs in vascular diseases; a pathway that may play a critical role in the rupture of atherosclerotic lesions,^184,188 regulation of neutrophil recruitment and inactivation of TIMPs (Figures 1 and 2). Indeed, in vitro studies have shown that HOCl added as reagent or generated by the MPO-H₂O₂-chloride system inactivates TIMP-1 by oxidizing the N-terminal cysteine residue of the enzyme,^189,190 a mechanism reported to occur in vivo under inflammatory conditions.¹⁹⁰ These data support the notion that an imbalance between the proteolytic activity of MMPs and the inhibitory activity of TIMPs is implicated in many pathological conditions.¹⁹⁰

A large body of data reported increased neutrophil infiltration during CP, reflecting a heightened inflammatory state. As a consequence, MPO mass and/or activity is upregulated in rapidly progressing CP, GCFs, saliva and human dental pulp tissues in order to combat pathogenic microbes.^{105,191–204} Miyasaki and Nemirovsky reported that among dental and periodontal bacteria tested,²⁰⁴ A. actinomycetemcomitans has the highest capacity to promote the release of neutrophil-derived MPO. Owing to its ability to form HOCl, MPO is involved in the destruction of periodontal components and can destroy the ECM by directly activating latent MMP-8 and MMP-9, and by enhancing MMP activity via inactivation of TIMP-1.¹⁰¹ Leppilahti et al. reported that levels of MPO and MMPs (MMP-8, MMP-13 and MMP-14) show highest diagnostic accuracy,¹⁹⁶ while only MPO and MMP-8 were significantly higher in periodontitis compared with gingivitis. Furthermore, salivary concentrations of MPO and NE, and the ratio of MMP-8/TIMP-1, were higher in generalized CP and aggressive periodontitis than in healthy controls.²⁰² The high prognostic value of MPO and MMPs, as well as TIMPs, in periodontitis is supported by a marked decrease even after non-surgical therapy.^{69,101,105,201} Basically, MPO levels in saliva are increased in patients with peri-implant disease with and without implants.^205,206 In peri-implant sulcus fluids, levels of MPO rose with the increase of pocket probing depth and increasing gingival inflammation but decreased significantly after non-surgical therapy.^207,208

Neutrophils, the first cellular responders to invading microbes, exert most of their antimicrobial activity in phagosomes, specialized membrane-bound intracellular compartments formed by ingestion of microorganisms.²⁰⁹ Alternatively, stimulated neutrophils may combat microbes through the release of web-like filamentous structures of decondensed chromatin, so-called neutrophil extracellular traps. These traps are composed of DNA and histones, and harbor antimicrobial peptides and enzymes such as cathepsin G, NE and MPO.²¹⁰ Neutrophil extracellular traps are present in dental plaque samples, saliva, supragingival biofilms and gingival connective tissue,^211,212 and thus play a significant role in the pathogenesis of periodontitis (for a review see Cooper et al.²¹¹) probably by subsequent modulation of the immune response.²¹³

High levels of MPO–DNA complexes, as observed in severe coronary atherosclerosis,²¹⁴ are most likely due to periodontal bacteria (P. gingivalis, T. forsythia and P. intermedia) that may trigger neutrophil activation. This suggests activation of similar pathways as in atherosclerosis and periodontitis.²¹⁵ Treatment of periodontitis has further been reported to modulate the atherosclerotic profile by exerting a beneficial effect on endothelial cell function.⁴⁷ This must be seen in context: MPO-mediated endothelial dysfunction, apparently due to consumption of NO,²¹⁶ may be considered an important mechanistic link between inflammation and CVD.²¹⁷ Different MPO polymorphisms have been found to be associated with plasma MPO concentrations in patients with coronary artery disease.¹⁷⁸ Whether such a link may also exist with periodontitis needs further investigation.^218–220

Neutrophil proteolytic activation cascades

Naruko et al. were the first to show neutrophil infiltration into culprit lesions in ACS.²²¹ Later, Ionita et al. reported that high neutrophil numbers in human carotid atherosclerotic plaques are associated with characteristics of rupture-prone lesions.²²² Furthermore, a positive association between the number of neutrophils and plaque levels of MMP-8 and MMP-9 was found.²²² From these data it is obvious that neutrophils play a major role in mediating destabilization of the atherosclerotic plaque.^221,222 Neutrophils are present in greater numbers in periodontal patients, and acute MI size is related to the extent of periodontitis.²²³ Furthermore, neutrophils play a crucial role in the initiation and/or progression of both periodontitis and CHD, probably via proteolytic alteration in the local balance of ECM.^1,2,76,224 Collagen structures of both periodontal ligament and atherosclerotic fibrous cap are almost the same. In the periodontium, mainly type I collagen and to a lesser extent type III collagen represent the main component of the ECM in the soft (gingiva and periodontal ligament) and hard (alveolar bone) periodontal tissues.^225,226 Similarly, the atherosclerotic fibrous cap is rich in collagen type I and III.^25,26,28,227 In order to approach the infected sites and eradicate the infectious bacterial burden, neutrophils release several proteases from their granules to degrade the collagen and gelatine moieties of the ECM and BM components, and to fulfill their antimicrobial function.² CP can result in enhanced production of neutrophil-derived proteases, both at local sites and also in the circulation.² The existence of periodontal bacteria in atheromatous plaque lesion may trigger neutrophil activation and recruitment at inflammatory sites.²¹⁵ Thus, proteolytic biomarkers released directly from neutrophils at the atheromatous plaque site or secreted in the circulation by neutrophils at sites of periodontal lesions may be considered a link between these inflammatory diseases (CP and CHD). Robust or prolonged neutrophilic antimicrobial activities may cause collateral uncontrolled destructive lesions.^2,69,224 MMPs are the key players in this process by cleaving almost all ECM constituents and regulating the action of cytokines and chemokines.^{69–72,124,228}

Doxycycline and other medications used for reducing MMPs or MPO and low-grade inflammation

Doxycycline, an approved adjunctive medication for the treatment of CP, is a synthetic MMP inhibitor and may be administered at three different pharmacological doses. It can be applied as either low- or submicrobial-dose doxycycline, 20–40 mg, or at a normal/regular dose (>100 mg). Owing to its anti-MMP properties, doxycycline may decrease the risk of coronary artery disease events. Doxycycline, at both low and regular doses, can downregulate several MMPs and other pro-inflammatory mediators, probably owing to its immunomodulatory and anti-proteolytic effects.^{42,162,229–231} In contrast, low or sub-antimicrobial adjunctive doxycycline medication does not exert antimicrobial properties, thus differing clearly from regular antimicrobial dosages.²³² Doxycycline can decrease MMP-7 and the MMP-8/TIMP-1 ratio, modulate NE, MPO, cytokines (IL-6, IL-8, TNF-α) and CRP, and most importantly increase TIMP-1 levels.^{42,133,139,162} Therefore, doxycycline seems to exert its potential as an adjunctive medication for multiple pathological conditions and chronic inflammatory diseases, including CP, CVD and ACS.^85,133,139 In line with previous studies, our data have shown that MMP-7 and MMP-8, as well as the MMP-8/TIMP-1 ratio, were diminished with doxycycline treatment.^{42,161,229,233–235} Recently, at low doses, doxycycline has been suggested to decrease MMP-8 and MMP-9 levels in serum and oral fluids (such as GCF) and, consequently, beneficially modulate the MMP-8/TIMP-1 ratio.^110,162,236 Frankwich et al. have demonstrated that regular-dose doxycycline medication decreased serum pro-inflammatory biomarkers and MMPs, resulting in improved insulin sensitivity eventually by protecting insulin receptor cleavage(s) by MMPs.^237,238 Nevertheless, some adverse side effects (e.g. diarrhea, fungal infections and super infections) have been reported to occur when patients are treated with doxycycline at regular doses.²³⁹

In rat models of experimental periodontitis, increased levels of MPO may be considered an inflammatory disease marker.^240–242 Therapeutic effects on MPO levels by antioxidants such as alpha lipoic acid and vitamin C have been reported.²⁴⁰ Both, carvedilol (an alpha/beta blocker) or azilsartan/olmersartan (angiotensin II receptor-AT₁ blockers) reduced levels of MPO, MMP-2 and MMP-9.^243–246 Treatment with synthetic parstatin (a 41-aa peptide, formed in vivo by proteolytic cleavage on activation of the protease activated receptor-1) significantly reduced MPO activity in gingivamucosal tissue.²⁴² Also, treatment of periodontitis with the tryptase inhibitor Nafamostat mesilate for 14 days decreased MPO activity in gingivomucosal tissue.²⁴⁷

The combination of alendronate (a bisphosphonate) and atorvastatin (a cholesterol-lowering drug) decreased MPO activity in the gingiva of rats following ligature-induced periodontitis.²⁴⁸ Also simvastatin (another inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase, the key enzyme in endogenous cholesterol biosynthesis pathway), which was previously reported to downregulate MPO gene expression in human and murine monocyte macrophages,²⁴⁹ was found to decrease MPO activity dose dependently in experimental periodontitis.²⁵⁰ Additionally, a recent study in patients with type-2 diabetes with hypercholesterolemia demonstrated the mechanisms of lipid-lowering drugs to reduce systemic pro-inflammatory factors and MMPs.²⁵¹

Inhibition of MPO or scavenging of HOCl might represent an alternative strategy for the treatment of PDs.²⁵² In particular, taurine chloramine, which is generated from HOCl and its physiological scavenger (the sulfur-containing aa taurine), is only about a third as active as HOCl in activating MMP-8 but completely fails to inhibit TIMP-1 at concentrations achieved at sites of inflammation.²⁵³

Conclusion

A recent study correlating salivary biomarkers with MI and periodontal status revealed that MMP-9 correlated positively with MMP-8 and MPO but negatively with TIMP levels.²⁵⁴ Indeed, MMP-8 and MMP-9 primarily secreted from neutrophils in a latent form and during inflammation can be activated by several pro-inflammatory mediators, such as cytokines, MMP-7, NE and MPO-derived/generated reactive intermediates (including HOCl), as well as microbial proteases.⁹⁹ MMP-8 is able to degrade collagen type I, the major contributor to the tensile strength of the fibrous cap, threefold more potently than other interstitial collagenases.^78,81 In addition to BM proteolysis, the proteolytic products of collagens can further be degraded by MMP-9.⁷¹ Through its ability to release chemokines, epithelial MMP-7 is important for neutrophil influx to the site of inflammation.^124,255 Other enzymes of the neutrophil granules, for example NE and MPO, and MPO-generated reactants, secreted into the extracellular space can cleave the ECM. MMPs and their regulators can promote auto-activation and form proteolytic activation cascades.¹⁰⁸ Alternatively, MPO potentiates MMP proteolytic cascades by impairing the crucial balance between proteases and anti-proteases that may lead to potentially deleterious situations.²⁵⁶ MPO can also oxidatively convert latent MMP-8 and MMP-9 into proteolytically active forms, inactivate TIMPs and regulate neutrophil recruitment (Figures 1 and 2).^{69,76,101,190,257} All of these neutrophil-derived markers, reported to be upregulated in atherosclerotic lesions, are thought to play a fundamental role in plaque rupture and are associated with subsequent pathological CVD events.^{93,94,148,168,258,259} Thus, neutrophil-derived proteases implicated in the atherosclerotic plaque rupture may lead to acute manifestations of the disease such as unstable angina pectoris or acute MI. On the one hand, future CVD events could be predicted by determining serum MMP-7 and MMP-8, TIMP-1 and the MMP-8/TIMP-1 ratio, as high MMP-7 and MMP-8 levels have been associated with several forms of CVD and increased incidence of fatal heart attacks.^92–96 Serum levels of these molecules might reflect the progression and severity of CVD and may thus be considered as candidate markers in predicting future CVD events. On the other hand, the usefulness of these molecules in oral samples, saliva, mouth rinse or GCF as biomarkers of CVD requires further investigations.

MMP inhibition via doxycycline represents a promising route for periodontitis treatment. Nevertheless, further research is needed that includes large-scale/multinational intervention trials with a sufficiently long follow-up period, standardized periodontal measurements and proper adjustments for known confounders. It is important to elaborate the understanding of molecular mechanisms related to neutrophil proteolytic pathways by investigating the impact of periodontal therapy on traditional CVD risk factors. Furthermore, it is necessary to provide therapeutic strategies preventing and treating severe clinical outcomes, such as secondary CVD events or even mortality. The strategy to balance MMPs and their regulators by doxycycline treatment might offer a suitable approach for CHD treatment by providing an anti-proteolytic and anti-inflammatory barrier against systemic inflammation and recurrent CVD events.

Footnotes

Funding

Research in our laboratories has been funded by the Ella and Georg Ehrnrooth Foundation (to HA), the Sigrid Juselius Foundation (to PJP), the Yrjö Janhsson Foundation (to PJP), the Finnish Dental Society Apollonia (to PJP), the Academy of Finland (#1266053 to PJP, #1130408 to TS) and the Helsinki University Central Hospital Foundation (EVO for TS).

Conflict of interest

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

References

Kantarci

Oyaizu

Van Dyke

. Neutrophil-mediated tissue injury in periodontal disease pathogenesis: findings from localized aggressive periodontitis. J Periodontol 2003; 74: 66–75.

Scott

Krauss

. Neutrophils in periodontal inflammation. Front Oral Biol 2012; 15: 56–83.

Tonetti

Imboden

Lang

. Neutrophil migration into the gingival sulcus is associated with transepithelial gradients of interleukin-8 and ICAM-1. J Periodontol 1998; 69: 1139–1147.

Mealey

Rethman

. Periodontal disease and diabetes mellitus. Bidirectional relationship. Dent Today 2003; 22: 107–113.

Pihlstrom

Michalowicz

Johnson

. Periodontal diseases. Lancet 2005; 366: 1809–1820.

Tamaki

Tomofuji

Ekuni

. Short-term effects of non-surgical periodontal treatment on plasma level of reactive oxygen metabolites in patients with chronic periodontitis. J Periodontol 2009; 80: 901–906.

Desvarieux

Demmer

Rundek

. Periodontal microbiota and carotid intima-media thickness: the Oral Infections and Vascular Disease Epidemiology Study (INVEST). Circulation 2005; 111: 576–582.

Socransky

Haffajee

Cugini

. Microbial complexes in subgingival plaque. J Clin Periodontol 1998; 25: 134–144.

Kumar

Griffen

Barton

. New bacterial species associated with chronic periodontitis. J Dent Res 2003; 82: 338–344.

10.

Wade

. The oral microbiome in health and disease. Pharmacol Res 2013; 69: 137–143.

11.

Erridge

. Diet, commensals and the intestine as sources of pathogen-associated molecular patterns in atherosclerosis, type 2 diabetes and non-alcoholic fatty liver disease. Atherosclerosis 2011; 216: 1–6.

12.

Forner

Larsen

Kilian

. Incidence of bacteremia after chewing, tooth brushing and scaling in individuals with periodontal inflammation. J Clin Periodontol 2006; 33: 401–407.

13.

Pussinen

Vilkuna-Rautiainen

Alfthan

. Severe periodontitis enhances macrophage activation via increased serum lipopolysaccharide. Arterioscler Thromb Vasc Biol 2004; 24: 2174–2180.

14.

Geerts

Nys

. Systemic release of endotoxins induced by gentle mastication: association with periodontitis severity. J Periodontol 2002; 73: 73–78.

15.

Levels

Abraham

van den Ende

. Distribution and kinetics of lipoprotein-bound endotoxin. Infect Immun 2001; 69: 2821–2828.

16.

Kallio

Buhlin

Jauhiainen

. Lipopolysaccharide associates with pro-atherogenic lipoproteins in periodontitis patients. Innate Immun 2008; 14: 247–253.

17.

Tuomainen

Jauhiainen

Kovanen

. Aggregatibacter actinomycetemcomitans induces MMP-9 expression and proatherogenic lipoprotein profile in apoE-deficient mice. Microb Pathog 2008; 44: 111–117.

18.

Kallio

KAE

Hyvärinen

Kovanen

. Very low density lipoproteins derived from periodontitis patients facilitate macrophage activation via lipopolysaccharide function. Metabolism 2013; 62: 661–668.

19.

Kallio

Hätonen

Lehto

. Endotoxemia, nutrition, and cardiometabolic disorders. Acta Diabetol 2015; 52: 395–404.

20.

Lassenius

Pietiläinen

Kaartinen

. Bacterial endotoxin activity in human serum is associated with dyslipidemia, insulin resistance, obesity, and chronic inflammation. Diabetes Care 2011; 34: 1809–1815.

21.

Neves

Coelho

Couto

. Metabolic endotoxemia: a molecular link between obesity and cardiovascular risk. J Mol Endocrinol 2013; 51: R51–R64.

22.

Nymark

Pussinen

Tuomainen

. Serum lipopolysaccharide activity is associated with the progression of kidney disease in finnish patients with type 1 diabetes. Diabetes Care 2009; 32: 1689–1693.

23.

Pussinen

Havulinna

Lehto

. Endotoxemia is associated with an increased risk of incident diabetes. Diabetes Care 2011; 34: 392–397.

24.

Pussinen

Tuomisto

Jousilahti

. Endotoxemia, immune response to periodontal pathogens, and systemic inflammation associate with incident cardiovascular disease events. Arterioscler Thromb Vasc Biol 2007; 27: 1433–1439.

25.

Libby

Ridker

Maseri

. Inflammation and atherosclerosis. Circulation 2002; 105: 1135–1143.

26.

Ross

. Atherosclerosis is an inflammatory disease. Am Heart J 1999; 138: S419–S420.

27.

Epstein

. The multiple mechanisms by which infection may contribute to atherosclerosis development and course. Circ Res 2002; 90: 2–4.

28.

Libby

Ridker

Hansson

. Inflammation in atherosclerosis: from pathophysiology to practice. J Am Coll Cardiol 2009; 54: 2129–2138.

29.

Kozarov

Dorn

Shelburne

. Human atherosclerotic plaque contains viable invasive Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. Arterioscler Thromb Vasc Biol 2005; 25: e17–e18.

30.

Mattila

Nieminen

Valtonen

. Association between dental health and acute myocardial infarction. BMJ 1989; 298: 779–781.

31.

Aas

Paster

Stokes

. Defining the normal bacterial flora of the oral cavity. J Clin Microbiol 2005; 43: 5721–5732.

32.

Bahekar

Singh

Saha

. The prevalence and incidence of coronary heart disease is significantly increased in periodontitis: a meta-analysis. Am Heart J 2007; 154: 830–837.

33.

Humphrey

Buckley

. Periodontal disease and coronary heart disease incidence: a systematic review and meta-analysis. J Gen Intern Med 2008; 23: 2079–2086.

34.

Janket

Baird

Chuang

. Meta-analysis of periodontal disease and risk of coronary heart disease and stroke. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003; 95: 559–569.

35.

Khader

Albashaireh

Alomari

. Periodontal diseases and the risk of coronary heart and cerebrovascular diseases: a meta-analysis. J Periodontol 2004; 75: 1046–1053.

36.

Linden

Herzberg

Working group 4 of joint EFP/AAP workshop . Periodontitis and systemic diseases: a record of discussions of working group 4 of the Joint EFP/AAP Workshop on Periodontitis and Systemic Diseases. J Clin Periodontol 2013; 40(Suppl. 14): S20–S23.

37.

Lockhart

Bolger

Papapanou

. Periodontal disease and atherosclerotic vascular disease: does the evidence support an independent association?: a scientific statement from the American Heart Association. Circulation 2012; 125: 2520–2544.

38.

Mustapha

Debrey

Oladubu

. Markers of systemic bacterial exposure in periodontal disease and cardiovascular disease risk: a systematic review and meta-analysis. J Periodontol 2007; 78: 2289–2302.

39.

Scannapieco

Bush

Paju

. Associations between periodontal disease and risk for atherosclerosis, cardiovascular disease, and stroke. A systematic review. Ann Periodontol 2003; 8: 38–53.

40.

Alfakry

Paju

Sinisalo

. Periodontopathogen- and host-derived immune response in acute coronary syndrome. Scand J Immunol 2011; 74: 383–389.

41.

Fredriksson

Figueredo

Gustafsson

. Effect of periodontitis and smoking on blood leukocytes and acute-phase proteins. J Periodontol 1999; 70: 1355–1360.

42.

Garcia

Pantazatos

Gessner

. Molecular interactions between matrilysin and the matrix metalloproteinase inhibitor doxycycline investigated by deuterium exchange mass spectrometry. Mol Pharmacol 2005; 67: 1128–1136.

43.

Teles

Wang

. Mechanisms involved in the association between periodontal diseases and cardiovascular disease. Oral Dis 2011; 17: 450–461.

44.

Turunen

Kummu

Harila

. Recognition of Porphyromonas gingivalis gingipain epitopes by natural IgM binding to malondialdehyde modified low-density lipoprotein. PLoS One 2012; 7: e34910–e34910.

45.

Buhlin

Hultin

Norderyd

. Periodontal treatment influences risk markers for atherosclerosis in patients with severe periodontitis. Atherosclerosis 2009; 206: 518–522.

46.

D'Aiuto

Orlandi

Gunsolley

. Evidence that periodontal treatment improves biomarkers and CVD outcomes. J Periodontol 2013; 84: S85–S105.

47.

Teeuw

Slot

Susanto

. Treatment of periodontitis improves the atherosclerotic profile: a systematic review and meta-analysis. J Clin Periodontol 2014; 41: 70–79.

48.

Olsen

. Update on bacteraemia related to dental procedures. Transfus Apher Sci 2008; 39: 173–178.

49.

Kinane

Riggio

Walker

. Bacteraemia following periodontal procedures. J Clin Periodontol 2005; 32: 708–713.

50.

Horliana

Chambrone

Foz

. Dissemination of periodontal pathogens in the bloodstream after periodontal procedures: a systematic review. PLoS One 2014; 9: e98271–e98271.

51.

Rafferty

Jonsson

Kalachikov

. Impact of monocytic cells on recovery of uncultivable bacteria from atherosclerotic lesions. J Intern Med 2011; 270: 273–280.

52.

Haraszthy

Zambon

Trevisan

. Identification of periodontal pathogens in atheromatous plaques. J Periodontol 2000; 71: 1554–1560.

53.

Kozarov

. Bacterial invasion of vascular cell types: vascular infectology and atherogenesis. Future Cardiol 2012; 8: 123–138.

54.

Reyes

Herrera

Kozarov

. Periodontal bacterial invasion and infection: contribution to atherosclerotic pathology. J Clin Periodontol 2013; 40(Suppl. 14): S30–S50.

55.

Loos

Craandijk

Hoek

. Elevation of systemic markers related to cardiovascular diseases in the peripheral blood of periodontitis patients. J Periodontol 2000; 71: 1528–1534.

56.

Noack

Genco

Trevisan

. Periodontal infections contribute to elevated systemic C-reactive protein level. J Periodontol 2001; 72: 1221–1227.

57.

Pussinen

Paju

Mäntyla

. Serum microbial- and host-derived markers of periodontal diseases: a review. Curr Med Chem 2007; 14: 2402–2412.

58.

Schenkein

Loos

. Inflammatory mechanisms linking periodontal diseases to cardiovascular diseases. J Clin Periodontol 2013; 40(Suppl. 14): S51–S69.

59.

Leishman

Ford

. Cardiovascular disease and the role of oral bacteria. J Oral Microbiol 2010; 2: 1–13.

60.

Pussinen

Jauhiainen

Vilkuna-Rautiainen

. Periodontitis decreases the antiatherogenic potency of high density lipoprotein. J Lipid Res 2004; 45: 139–147.

61.

Pattison

Davies

. Reactions of myeloperoxidase-derived oxidants with biological substrates: gaining chemical insight into human inflammatory diseases. Curr Med Chem 2006; 13: 3271–3290.

62.

Daugherty

Dunn

Rateri

. Myeloperoxidase, a catalyst for lipoprotein oxidation, is expressed in human atherosclerotic lesions. J Clin Invest 1994; 94: 437–444.

63.

Malle

Wag

Thiery

. Hypochlorite-modified (lipo)proteins are present in rabbit lesions in response to dietary cholesterol. Biochem Biophys Res Commun 2001; 289: 894–900.

64.

Malle

Waeg

Schreiber

. Immunohistochemical evidence for the myeloperoxidase/H₂O₂/halide system in human atherosclerotic lesions: colocalization of myeloperoxidase and hypochlorite-modified proteins. Eur J Biochem 2000; 267: 4495–4503.

65.

Malle

Woenckhaus

Waeg

. Immunological evidence for hypochlorite-modified proteins in human kidney. Am J Pathol 1997; 150: 603–615.

66.

Grone

Malle

. Immunohistochemical detection of hypochlorite-modified proteins in glomeruli of human membranous glomerulonephritis. Lab Invest 2002; 82: 5–14.

67.

Malle

Buch

Grone

. Myeloperoxidase in kidney disease. Kidney Int 2003; 64: 1956–1967.

68.

Nagase

Visse

Murphy

. Structure and function of matrix metalloproteinases and TIMPs. Cardiovasc Res 2006; 69: 562–573.

69.

Sorsa

Tjäderhane

Konttinen

. Matrix metalloproteinases: contribution to pathogenesis, diagnosis and treatment of periodontal inflammation. Ann Med 2006; 38: 306–321.

70.

Sorsa

Tjäderhane

Salo

. Matrix metalloproteinases (MMPs) in oral diseases. Oral Dis 2004; 10: 311–318.

71.

Visse

Nagase

. Matrix metalloproteinases and tissue inhibitors of metalloproteinases: structure, function, and biochemistry. Circ Res 2003; 92: 827–839.

72.

Nissinen

Kahari

. Matrix metalloproteinases in inflammation. Biochim Biophys Acta 2014; 1840: 2571–2580.

73.

Hanemaaijer

Sorsa

Konttinen

. Matrix metalloproteinase-8 is expressed in rheumatoid synovial fibroblasts and endothelial cells. Regulation by tumor necrosis factor-alpha and doxycycline. J Biol Chem 1997; 272: 31504–31509.

74.

Prikk

Maisi

Pirilä

. In vivo collagenase-2 (MMP-8) expression by human bronchial epithelial cells and monocytes/macrophages in bronchiectasis. J Pathol 2001; 194: 232–238.

75.

Wahlgren

Maisi

Sorsa

. Expression and induction of collagenases (MMP-8 and -13) in plasma cells associated with bone-destructive lesions. J Pathol 2001; 194: 217–224.

76.

Weiss

. Tissue destruction by neutrophils. N Engl J Med 1989; 320: 365–376.

77.

Ala-aho

Kahari

. Collagenases in cancer. Biochimie 2005; 87: 273–286.

78.

Hasty

Jeffrey

Hibbs

. The collagen substrate specificity of human neutrophil collagenase. J Biol Chem 1987; 262: 10048–10052.

79.

Owen

Campbell

. The cell biology of leukocyte-mediated proteolysis. J Leukoc Biol 1999; 65: 137–150.

80.

Safkan-Seppalä

Sorsa

Tervahartiala

. Collagenases in gingival crevicular fluid in type 1 diabetes mellitus. J Periodontol 2006; 77: 189–194.

81.

Herman

Sukhova

Libby

. Expression of neutrophil collagenase (matrix metalloproteinase-8) in human atheroma: a novel collagenolytic pathway suggested by transcriptional profiling. Circulation 2001; 104: 1899–1904.

82.

Salminen

Åstrom

Metso

. Matrix metalloproteinase 8 degrades apolipoprotein A-I and reduces its cholesterol efflux capacity. FASEB J 2015; 29: 1435–1445.

83.

Molloy

Thompson

Jones

. Unstable carotid plaques exhibit raised matrix metalloproteinase-8 activity. Circulation 2004; 110: 337–343.

84.

Sluijter

Pulskens

Schoneveld

. Matrix metalloproteinase 2 is associated with stable and matrix metalloproteinases 8 and 9 with vulnerable carotid atherosclerotic lesions: a study in human endarterectomy specimen pointing to a role for different extracellular matrix metalloproteinase inducer glycosylation forms. Stroke 2006; 37: 235–239.

85.

Sorsa

Tervahartiala

Leppilahti

. Collagenase-2 (MMP-8) as a point-of-care biomarker in periodontitis and cardiovascular diseases. Therapeutic response to non-antimicrobial properties of tetracyclines. Pharmacol Res 2011; 63: 108–113.

86.

van den Borne

Cleutjens

Hanemaaijer

. Increased matrix metalloproteinase-8 and -9 activity in patients with infarct rupture after myocardial infarction. Cardiovasc Pathol 2009; 18: 37–43.

87.

Galis

Muszynski

Sukhova

. Enhanced expression of vascular matrix metalloproteinases induced in vitro by cytokines and in regions of human atherosclerotic lesions. Ann N Y Acad Sci 1995; 748: 501–507.

88.

Galis

Sukhova

Lark

. Increased expression of matrix metalloproteinases and matrix degrading activity in vulnerable regions of human atherosclerotic plaques. J Clin Invest 1994; 94: 2493–2503.

89.

Turu

Krupinski

Catena

. Intraplaque MMP-8 levels are increased in asymptomatic patients with carotid plaque progression on ultrasound. Atherosclerosis 2006; 187: 161–169.

90.

Momiyama

Ohmori

Tanaka

. High plasma levels of matrix metalloproteinase-8 in patients with unstable angina. Atherosclerosis 2010; 209: 206–210.

91.

Kato

Momiyama

Ohmori

. Plasma matrix metalloproteinase-8 concentrations are associated with the presence and severity of coronary artery disease. Circ J 2005; 69: 1035–1040.

92.

Qiang

Zhou

. [Implications of serum matrix metalloproteinase-8 elevation in patients with acute coronary syndrome]. Nan Fang Yi Ke Da Xue Xue Bao 2007; 27: 831–833.

93.

Pussinen

Sarna

Puolakkainen

. The balance of serum matrix metalloproteinase-8 and its tissue inhibitor in acute coronary syndrome and its recurrence. Int J Cardiol 2013; 167: 362–368.

94.

Tuomainen

Kormi

Havulinna

. Serum tissue-degrading proteinases and incident cardiovascular disease events. Eur J Prev Cardiol 2014; 21: 806–812.

95.

Tuomainen

Nyyssonen

Laukkanen

. Serum matrix metalloproteinase-8 concentrations are associated with cardiovascular outcome in men. Arterioscler Thromb Vasc Biol 2007; 27: 2722–2728.

96.

Hastbacka

Tiainen

Hynninen

. Serum matrix metalloproteinases in patients resuscitated from cardiac arrest. The association with therapeutic hypothermia. Resuscitation 2012; 83: 197–201.

97.

Holopainen

Moilanen

Sorsa

. Activation of matrix metalloproteinase-8 by membrane type 1-MMP and their expression in human tears after photorefractive keratectomy. Invest Ophthalmol Vis Sci 2003; 44: 2550–2556.

98.

Saari

Suomalainen

Lindy

. Activation of latent human neutrophil collagenase by reactive oxygen species and serine proteases. Biochem Biophys Res Commun 1990; 171: 979–987.

99.

Sorsa

Ingman

Suomalainen

. Identification of proteases from periodontopathogenic bacteria as activators of latent human neutrophil and fibroblast-type interstitial collagenases. Infect Immun 1992; 60: 4491–4495.

100.

Palm

Lahdentausta

Sorsa

. Biomarkers of periodontitis and inflammation in ischemic stroke: A case–control study. Innate Immun 2014; 20: 511–518.

101.

Hernandez

Gamonal

Tervahartiala

. Associations between matrix metalloproteinase-8 and -14 and myeloperoxidase in gingival crevicular fluid from subjects with progressive chronic periodontitis: a longitudinal study. J Periodontol 2010; 81: 1644–1652.

102.

Leppilahti

Kallio

Tervahartiala

. Gingival crevicular fluid matrix metalloproteinase-8 levels predict treatment outcome among smokers with chronic periodontitis. J Periodontol 2014; 85: 250–260.

103.

Mäntyla

Stenman

Kinane

. Monitoring periodontal disease status in smokers and nonsmokers using a gingival crevicular fluid matrix metalloproteinase-8-specific chair-side test. J Periodontal Res 2006; 41: 503–512.

104.

Mäntyla

Stenman

Kinane

. Gingival crevicular fluid collagenase-2 (MMP-8) test stick for chair-side monitoring of periodontitis. J Periodontal Res 2003; 38: 436–439.

105.

Marcaccini

Meschiari

Zuardi

. Gingival crevicular fluid levels of MMP-8, MMP-9, TIMP-2, and MPO decrease after periodontal therapy. J Clin Periodontol 2010; 37: 180–190.

106.

Marcaccini

Novaes

AB Jr

Meschiari

. Circulating matrix metalloproteinase-8 (MMP-8) and MMP-9 are increased in chronic periodontal disease and decrease after non-surgical periodontal therapy. Clin Chim Acta 2009; 409: 117–122.

107.

Merchant

Pitiphat

Parker

. Can nonstandardized bitewing radiographs be used to assess the presence of alveolar bone loss in epidemiologic studies? Community Dent Oral Epidemiol 2004; 32: 271–276.

108.

Sorsa

Hameila

Järviluoma

. Handling anticancer drugs: from hazard identification to risk management? Ann N Y Acad Sci 2006; 1076: 628–634.

109.

Sorsa

Hernandez

Leppilahti

. Detection of gingival crevicular fluid MMP-8 levels with different laboratory and chair-side methods. Oral Dis 2010; 16: 39–45.

110.

Golub

Lee

Stoner

. Subantimicrobial-dose doxycycline modulates gingival crevicular fluid biomarkers of periodontitis in postmenopausal osteopenic women. J Periodontol 2008; 79: 1409–1418.

111.

Kivelä-Rajamaki

Maisi

Srinivas

. Levels and molecular forms of MMP-7 (matrilysin-1) and MMP-8 (collagenase-2) in diseased human peri-implant sulcular fluid. J Periodontal Res 2003; 38: 583–590.

112.

Hernandez

Gamonal

Salo

. Reduced expression of lipopolysaccharide-induced CXC chemokine in Porphyromonas gingivalis-induced experimental periodontitis in matrix metalloproteinase-8 null mice. J Periodontal Res 2011; 46: 58–66.

113.

Kuula

Salo

Pirilä

. Local and systemic responses in matrix metalloproteinase 8-deficient mice during Porphyromonas gingivalis-induced periodontitis. Infect Immun 2009; 77: 850–859.

114.

Sternlicht

Werb

. How matrix metalloproteinases regulate cell behavior. Annu Rev Cell Dev Biol 2001; 17: 463–516.

115.

Lijnen

Collen

. Matrix metalloproteinase system deficiencies and matrix degradation. Thromb Haemost 1999; 82: 837–845.

116.

Nakamura

Yoshimura

McElvaney

. Neutrophil elastase in respiratory epithelial lining fluid of individuals with cystic fibrosis induces interleukin-8 gene expression in a human bronchial epithelial cell line. J Clin Invest 1992; 89: 1478–1484.

117.

Okada

Gonoji

Naka

. Matrix metalloproteinase 9 (92-kDa gelatinase/type IV collagenase) from HT 1080 human fibrosarcoma cells. Purification and activation of the precursor and enzymic properties. J Biol Chem 1992; 267: 21712–21719.

118.

Nguyen

Arkell

Jackson

. Human endothelial gelatinases and angiogenesis. Int J Biochem Cell Biol 2001; 33: 960–970.

119.

Opdenakker

Van den Steen

Van Damme

. Gelatinase B: a tuner and amplifier of immune functions. Trends Immunol 2001; 22: 571–579.

120.

Stahle-Backdahl

Parks

. 92-kd gelatinase is actively expressed by eosinophils and stored by neutrophils in squamous cell carcinoma. Am J Pathol 1993; 142: 995–1000.

121.

Tetlow

Adlam

Woolley

. Matrix metalloproteinase and proinflammatory cytokine production by chondrocytes of human osteoarthritic cartilage: associations with degenerative changes. Arthritis Rheum 2001; 44: 585–594.

122.

Van den Steen

Dubois

Nelissen

. Biochemistry and molecular biology of gelatinase B or matrix metalloproteinase-9 (MMP-9). Crit Rev Biochem Mol Biol 2002; 37: 375–536.

123.

Birkedal-Hansen

. Role of matrix metalloproteinases in human periodontal diseases. J Periodontol 1993; 64: 474–484.

124.

Elkington

O'Kane

Friedland

. The paradox of matrix metalloproteinases in infectious disease. Clin Exp Immunol 2005; 142: 12–20.

125.

Westerlund

Ingman

Lukinmaa

. Human neutrophil gelatinase and associated lipocalin in adult and localized juvenile periodontitis. J Dent Res 1996; 75: 1553–1563.

126.

Wilhelm

Collier

Marmer

. SV40-transformed human lung fibroblasts secrete a 92-kDa type IV collagenase which is identical to that secreted by normal human macrophages. J Biol Chem 1989; 264: 17213–17221.

127.

Fosang

Neame

Last

. The interglobular domain of cartilage aggrecan is cleaved by PUMP, gelatinases, and cathepsin B. J Biol Chem 1992; 267: 19470–19474.

128.

Senior

Griffin

Fliszar

. Human 92- and 72-kilodalton type IV collagenases are elastases. J Biol Chem 1991; 266: 7870–7875.

129.

Backstrom

Tokes

. The 84-kDa form of human matrix metalloproteinase-9 degrades substance P and gelatin. J Neurochem 1995; 64: 1312–1318.

130.

Ito

Mukaiyama

Itoh

. Degradation of interleukin 1beta by matrix metalloproteinases. J Biol Chem 1996; 271: 14657–14660.

131.

Brown

Hibbs

Kearney

. Identification of 92-kD gelatinase in human coronary atherosclerotic lesions. Association of active enzyme synthesis with unstable angina. Circulation 1995; 91: 2125–2131.

132.

Cho

Reidy

. Matrix metalloproteinase-9 is necessary for the regulation of smooth muscle cell replication and migration after arterial injury. Circ Res 2002; 91: 845–851.

133.

Lee

Sorsa

. Non-antibacterial tetracyclines modulate mediators of periodontitis and atherosclerotic cardiovascular disease: a mechanistic link between local and systemic inflammation. Pharmacol Res 2011; 64: 573–579.

134.

Lalla

Lamster

Hofmann

. Oral infection with a periodontal pathogen accelerates early atherosclerosis in apolipoprotein E-null mice. Arterioscler Thromb Vasc Biol 2003; 23: 1405–1411.

135.

Loftus

Naylor

Goodall

. Increased matrix metalloproteinase-9 activity in unstable carotid plaques. A potential role in acute plaque disruption. Stroke 2000; 31: 40–47.

136.

Ferroni

Basili

Martini

. Serum metalloproteinase 9 levels in patients with coronary artery disease: a novel marker of inflammation. J Investig Med 2003; 51: 295–300.

137.

Inokubo

Hanada

Ishizaka

. Plasma levels of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 are increased in the coronary circulation in patients with acute coronary syndrome. Am Heart J 2001; 141: 211–217.

138.

Renko

Kalela

Jaakkola

. Serum matrix metalloproteinase-9 is elevated in men with a history of myocardial infarction. Scand J Clin Lab Invest 2004; 64: 255–261.

139.

Brown

Desai

Vakili

. Clinical and biochemical results of the metalloproteinase inhibition with subantimicrobial doses of doxycycline to prevent acute coronary syndromes (MIDAS) pilot trial. Arterioscler Thromb Vasc Biol 2004; 24: 733–738.

140.

Burke

. The role of matrix metalloproteinase 7 in innate immunity. Immunobiology 2004; 209: 51–56.

141.

de Coignac

Elson

Delneste

. Cloning of MMP-26. A novel matrilysin-like proteinase. Eur J Biochem 2000; 267: 3323–3329.

142.

Wielockx

Libert

Wilson

. Matrilysin (matrix metalloproteinase-7): a new promising drug target in cancer and inflammation? Cytokine Growth Factor Rev 2004; 15: 111–115.

143.

Wilson

Matrisian

. Matrilysin: an epithelial matrix metalloproteinase with potentially novel functions. Int J Biochem Cell Biol 1996; 28: 123–136.

144.

Nagase

Woessner

JF Jr

. Matrix metalloproteinases. J Biol Chem 1999; 274: 21491–21494.

145.

Emingil

Tervahartiala

Mantyla

. Gingival crevicular fluid matrix metalloproteinase (MMP)-7, extracellular MMP inducer, and tissue inhibitor of MMP-1 levels in periodontal disease. J Periodontol 2006; 77: 2040–2050.

146.

Uitto

Overall

McCulloch

. Proteolytic host cell enzymes in gingival crevice fluid. Periodontol 2000 2003; 31: 77–104.

147.

Uitto

Salonen

Firth

. Matrilysin (matrix metalloproteinase-7) expression in human junctional epithelium. J Dent Res 2002; 81: 241–246.

148.

Halpert

Sires

Roby

. Matrilysin is expressed by lipid-laden macrophages at sites of potential rupture in atherosclerotic lesions and localizes to areas of versican deposition, a proteoglycan substrate for the enzyme. Proc Natl Acad Sci U S A 1996; 93: 9748–9753.

149.

Nilsson

Jonasson

Nijm

. Increased plasma concentration of matrix metalloproteinase-7 in patients with coronary artery disease. Clin Chem 2006; 52: 1522–1527.

150.

Dozier

Escobar

Lindsey

. Matrix metalloproteinase (MMP)-7 activates MMP-8 but not MMP-13. Med Chem 2006; 2: 523–526.

151.

Tervahartiala

Pirilä

Ceponis

. The in vivo expression of the collagenolytic matrix metalloproteinases (MMP-2, -8, -13, and -14) and matrilysin (MMP-7) in adult and localized juvenile periodontitis. J Dent Res 2000; 79: 1969–1977.

152.

Beaudeux

Giral

Bruckert

. Matrix metalloproteinases, inflammation and atherosclerosis: therapeutic perspectives. Clin Chem Lab Med 2004; 42: 121–131.

153.

Brew

Dinakarpandian

Nagase

. Tissue inhibitors of metalloproteinases: evolution, structure and function. Biochim Biophys Acta 2000; 1477: 267–283.

154.

Stetler-Stevenson

. Tissue inhibitors of metalloproteinases in cell signaling: metalloproteinase-independent biological activities. Sci Signal 2008; 1: re6–re6.

155.

Dollery

McEwan

Henney

. Matrix metalloproteinases and cardiovascular disease. Circ Res 1995; 77: 863–868.

156.

Welgus

Campbell

Bar-Shavit

. Human alveolar macrophages produce a fibroblast-like collagenase and collagenase inhibitor. J Clin Invest 1985; 76: 219–224.

157.

Cavusoglu

Ruwende

Chopra

. Tissue inhibitor of metalloproteinase-1 (TIMP-1) is an independent predictor of all-cause mortality, cardiac mortality, and myocardial infarction. Am Heart J 2006; 151: 1101 e1101–e1108.

158.

Lubos

Schnabel

Rupprecht

. Prognostic value of tissue inhibitor of metalloproteinase-1 for cardiovascular death among patients with cardiovascular disease: results from the AtheroGene study. Eur Heart J 2006; 27: 150–156.

159.

Naesse

Schreurs

Helgeland

. Matrix metalloproteinases and their inhibitors in gingival mast cells in persons with and without human immunodeficiency virus infection. J Periodontal Res 2003; 38: 575–582.

160.

Gursoy

Könönen

Pradhan-Palikhe

. Salivary MMP-8, TIMP-1, and ICTP as markers of advanced periodontitis. J Clin Periodontol 2010; 37: 487–493.

161.

Ingman

Tervahartiala

Ding

. Matrix metalloproteinases and their inhibitors in gingival crevicular fluid and saliva of periodontitis patients. J Clin Periodontol 1996; 23: 1127–1132.

162.

Payne

Golub

Stoner

. The effect of subantimicrobial-dose-doxycycline periodontal therapy on serum biomarkers of systemic inflammation: a randomized, double-masked, placebo-controlled clinical trial. J Am Dent Assoc 2011; 142: 262–273.

163.

Belaaouaj

Kim

Shapiro

. Degradation of outer membrane protein A in Escherichia coli killing by neutrophil elastase. Science 2000; 289: 1185–1188.

164.

Hiemstra

van Wetering

Stolk

. Neutrophil serine proteinases and defensins in chronic obstructive pulmonary disease: effects on pulmonary epithelium. Eur Respir J 1998; 12: 1200–1208.

165.

Ferry

Lonchampt

Pennel

. Activation of MMP-9 by neutrophil elastase in an in vivo model of acute lung injury. FEBS Lett 1997; 402: 111–115.

166.

Okada

Nakanishi

. Activation of matrix metalloproteinase 3 (stromelysin) and matrix metalloproteinase 2 (‘gelatinase') by human neutrophil elastase and cathepsin G. FEBS Lett 1989; 249: 353–356.

167.

Henriksen

Sallenave

. Human neutrophil elastase: mediator and therapeutic target in atherosclerosis. Int J Biochem Cell Biol 2008; 40: 1095–1100.

168.

Dollery

Owen

Sukhova

. Neutrophil elastase in human atherosclerotic plaques: production by macrophages. Circulation 2003; 107: 2829–2836.

169.

Smith

Fowkes

Rumley

. Tissue plasminogen activator and leucocyte elastase as predictors of cardiovascular events in subjects with angina pectoris: Edinburgh Artery Study. Eur Heart J 2000; 21: 1607–1613.

170.

Leclercq

Houard

Philippe

. Involvement of intraplaque hemorrhage in atherothrombosis evolution via neutrophil protease enrichment. J Leukoc Biol 2007; 82: 1420–1429.

171.

Ujiie

Oida

Gomi

. Neutrophil elastase is involved in the initial destruction of human periodontal ligament. J Periodontal Res 2007; 42: 325–330.

172.

Wohlfeil

Scharf

Siegelin

. Increased systemic elastase and C-reactive protein in aggressive periodontitis (CLOI-D-00160R2). Clin Oral Investig 2012; 16: 1199–1207.

173.

Eickholz

Siegelin

Scharf

. Non-surgical periodontal therapy decreases serum elastase levels in aggressive but not in chronic periodontitis. J Clin Periodontol 2013; 40: 327–333.

174.

Anatoliotakis

Deftereos

Bouras

. Myeloperoxidase: expressing inflammation and oxidative stress in cardiovascular disease. Curr Top Med Chem 2013; 13: 115–138.

175.

Nicholls

Hazen

. Myeloperoxidase and cardiovascular disease. Arterioscler Thromb Vasc Biol 2005; 25: 1102–1111.

176.

Baldus

Heeschen

Meinertz

. Myeloperoxidase serum levels predict risk in patients with acute coronary syndromes. Circulation 2003; 108: 1440–1445.

177.

Heslop

Frohlich

Hill

. Myeloperoxidase and C-reactive protein have combined utility for long-term prediction of cardiovascular mortality after coronary angiography. J Am Coll Cardiol 2010; 55: 1102–1109.

178.

Scharnagl

Kleber

Genser

. Association of myeloperoxidase with total and cardiovascular mortality in individuals undergoing coronary angiography—the LURIC study. Int J Cardiol 2014; 174: 96–105.

179.

Zhang

Brennan

. Association between myeloperoxidase levels and risk of coronary artery disease. JAMA 2001; 286: 2136–2142.

180.

Sugiyama

Okada

Sukhova

. Macrophage myeloperoxidase regulation by granulocyte macrophage colony-stimulating factor in human atherosclerosis and implications in acute coronary syndromes. Am J Pathol 2001; 158: 879–891.

181.

Nauseef

. Myeloperoxidase in human neutrophil host defence. Cell Microbiol 2014; 16: 1146–1155.

182.

Malle

Marsche

Panzenboeck

. Myeloperoxidase-mediated oxidation of high-density lipoproteins: fingerprints of newly recognized potential proatherogenic lipoproteins. Arch Biochem Biophys 2006; 445: 245–255.

183.

Hazell

Arnold

Flowers

. Presence of hypochlorite-modified proteins in human atherosclerotic lesions. J Clin Invest 1996; 97: 1535–1544.

184.

Kassim

Parks

. Hypochlorous acid oxygenates the cysteine switch domain of pro-matrilysin (MMP-7). A mechanism for matrix metalloproteinase activation and atherosclerotic plaque rupture by myeloperoxidase. J Biol Chem 2001; 276: 41279–41287.

185.

Peppin

Weiss

. Activation of the endogenous metalloproteinase, gelatinase, by triggered human neutrophils. Proc Natl Acad Sci U S A 1986; 83: 4322–4326.

186.

Weiss

Peppin

Ortiz

. Oxidative autoactivation of latent collagenase by human neutrophils. Science 1985; 227: 747–749.

187.

Michaelis

Vissers

Winterbourn

. Different effects of hypochlorous acid on human neutrophil metalloproteinases: activation of collagenase and inactivation of collagenase and gelatinase. Arch Biochem Biophys 1992; 292: 555–562.

188.

Kassim

Parks

. Hypochlorous acid generated by myeloperoxidase modifies adjacent tryptophan and glycine residues in the catalytic domain of matrix metalloproteinase-7 (matrilysin): an oxidative mechanism for restraining proteolytic activity during inflammation. J Biol Chem 2003; 278: 28403–28409.

189.

Shabani

McNeil

Tippett

. The oxidative inactivation of tissue inhibitor of metalloproteinase-1 (TIMP-1) by hypochlorous acid (HOCI) is suppressed by anti-rheumatic drugs. Free Radic Res 1998; 28: 115–123.

190.

Wang

Rosen

Madtes

. Myeloperoxidase inactivates TIMP-1 by oxidizing its N-terminal cysteine residue: an oxidative mechanism for regulating proteolysis during inflammation. J Biol Chem 2007; 282: 31826–31834.

191.

Buchmann

Hasilik

Van Dyke

. Amplified crevicular leukocyte activity in aggressive periodontal disease. J Dent Res 2002; 81: 716–721.

192.

Cifcibasi

Koyuncuoglu

Ciblak

. Evaluation of local and systemic levels of interleukin-17, interleukin-23, and myeloperoxidase in response to periodontal therapy in patients with generalized aggressive periodontitis. Inflammation 2015; 38: 1959–1968.

193.

Durrani

Singh

. Myeloperoxidase level around dental implants as an indicator of an inflammatory process. Indian J Dent 2015; 6: 2–6.

194.

Over

Yamalik

Yavuzyilmaz

. Myeloperoxidase activity in peripheral blood, neutrophil crevicular fluid and whole saliva of patients with periodontal disease. J Nihon Univ Sch Dent 1993; 35: 235–240.

195.

Kaner

Bernimoulin

Kleber

. Gingival crevicular fluid levels of calprotectin and myeloperoxidase during therapy for generalized aggressive periodontitis. J Periodontal Res 2006; 41: 132–139.

196.

Leppilahti

Hernandez-Rios

Gamonal

. Matrix metalloproteinases and myeloperoxidase in gingival crevicular fluid provide site-specific diagnostic value for chronic periodontitis. J Clin Periodontol 2014; 41: 348–356.

197.

Smith

Hinrichs

Melnyk

. Gingival crevicular fluid myeloperoxidase at periodontitis sites. J Periodontal Res 1986; 21: 45–55.

198.

Wei

. The investigation of glutathione peroxidase, lactoferrin, myeloperoxidase and interleukin-1beta in gingival crevicular fluid: implications for oxidative stress in human periodontal diseases. J Periodontal Res 2004; 39: 287–293.

199.

Yamalik

Caglayan

Kilinc

. The importance of data presentation regarding gingival crevicular fluid myeloperoxidase and elastase-like activity in periodontal disease and health status. J Periodontol 2000; 71: 460–467.

200.

Marcaccini

Amato

Leao

. Myeloperoxidase activity is increased in gingival crevicular fluid and whole saliva after fixed orthodontic appliance activation. Am J Orthod Dentofacial Orthop 2010; 138: 613–616.

201.

Meschiari

Marcaccini

Santos Moura

. Salivary MMPs, TIMPs, and MPO levels in periodontal disease patients and controls. Clin Chim Acta 2013; 421: 140–146.

202.

Nizam

Gumus

Pitkanen

. Serum and salivary matrix metalloproteinases, neutrophil elastase, myeloperoxidase in patients with chronic or aggressive periodontitis. Inflammation 2014; 37: 1771–1778.

203.

Accorsi-Mendonca

Silva

Marcaccini

. Evaluation of gelatinases, tissue inhibitor of matrix metalloproteinase-2, and myeloperoxidase protein in healthy and inflamed human dental pulp tissue. J Endod 2013; 39: 879–882.

204.

Miyasaki

Nemirovskiy

. Myeloperoxidase isoform activities released by human neutrophils in response to dental and periodontal bacteria. Oral Microbiol Immunol 1997; 12: 27–32.

205.

Liskmann

Vihalemm

Salum

. Characterization of the antioxidant profile of human saliva in peri-implant health and disease. Clin Oral Implants Res 2007; 18: 27–33.

206.

Sanchez-Siles

Lucas-Azorin

Salazar-Sanchez

. Salivary concentration of oxidative stress biomarkers in a group of patients with peri-implantitis: a transversal study. Clin Implant Dent Relat Res. Epub ahead of print 31 Jul 2015. DOI: 10.1111/cid.12367.

207.

Liskmann

Zilmer

Vihalemm

. Correlation of peri-implant health and myeloperoxidase levels: a cross-sectional clinical study. Clin Oral Implants Res 2004; 15: 546–552.

208.

Malik

Naik

Uppoor

. Levels of myeloperoxidase and alkaline phosphatase in periimplant sulcus fluid in health and disease and after nonsurgical therapy. Implant Dent 2015; 24: 434–440.

209.

Klebanoff

Kettle

Rosen

. Myeloperoxidase: a front-line defender against phagocytosed microorganisms. J Leukoc Biol 2013; 93: 185–198.

210.

Kaplan

Radic

. Neutrophil extracellular traps: double-edged swords of innate immunity. J Immunol 2012; 189: 2689–2695.

211.

Cooper

Palmer

Chapple

. Neutrophil extracellular traps as a new paradigm in innate immunity: friend or foe? Periodontol 2000 2013; 63: 165–197.

212.

Hirschfeld

Dommisch

Skora

. Neutrophil extracellular trap formation in supragingival biofilms. Int J Med Microbiol 2015; 305: 453–463.

213.

Mohanty

Sjögren

Kahn

. A novel mechanism for NETosis provides antimicrobial defense at the oral mucosa. Blood 2015; 126: 2128–2137.

214.

Borissoff

Joosen

Versteylen

. Elevated levels of circulating DNA and chromatin are independently associated with severe coronary atherosclerosis and a prothrombotic state. Arterioscler Thromb Vasc Biol 2013; 33: 2032–2040.

215.

Range

Labreuche

Louedec

. Periodontal bacteria in human carotid atherothrombosis as a potential trigger for neutrophil activation. Atherosclerosis 2014; 236: 448–455.

216.

Eiserich

Baldus

Brennan

. Myeloperoxidase, a leukocyte-derived vascular NO oxidase. Science 2002; 296: 2391–2394.

217.

Vita

Brennan

Gokce

. Serum myeloperoxidase levels independently predict endothelial dysfunction in humans. Circulation 2004; 110: 1134–1139.

218.

Debabrata

Prasanta

Vineet

. Aggressive periodontitis: an appraisal of systemic effects on its etiology-genetic aspect. J Indian Soc Periodontol 2015; 19: 169–173.

219.

Erciyas

Pehlivan

Sever

. Genetic variation of myeloperoxidase gene contributes to aggressive periodontitis: a preliminary association study in Turkish population. Dis Markers 2010; 28: 95–99.

220.

Meisel

Krause

Cascorbi

. Gender and smoking-related risk reduction of periodontal disease with variant myeloperoxidase alleles. Genes Immun 2002; 3: 102–106.

221.

Naruko

Ueda

Haze

. Neutrophil infiltration of culprit lesions in acute coronary syndromes. Circulation 2002; 106: 2894–2900.

222.

Ionita

van den Borne

Catanzariti

. High neutrophil numbers in human carotid atherosclerotic plaques are associated with characteristics of rupture-prone lesions. Arterioscler Thromb Vasc Biol 2010; 30: 1842–1848.

223.

Marfil-Alvarez

Mesa

Arrebola-Moreno

. Acute myocardial infarct size is related to periodontitis extent and severity. J Dent Res 2014; 93: 993–998.

224.

Mayadas

Cullere

Lowell

. The multifaceted functions of neutrophils. Annu Rev Pathol 2014; 9: 181–218.

225.

Bartold

. Periodontal tissues in health and disease: introduction. Periodontol 2000 2006; 40: 7–10.

226.

Nanci

Bosshardt

. Structure of periodontal tissues in health and disease. Periodontol 2000 2006; 40: 11–28.

227.

Lusis

. Atherosclerosis. Nature 2000; 407: 233–241.

228.

Jones

Sane

Herrington

. Matrix metalloproteinases: a review of their structure and role in acute coronary syndrome. Cardiovasc Res 2003; 59: 812–823.

229.

Lauhio

Konttinen

Tschesche

. Reduction of matrix metalloproteinase 8-neutrophil collagenase levels during long-term doxycycline treatment of reactive arthritis. Antimicrob Agents Chemother 1994; 38: 400–402.

230.

Lauhio

Salo

Ding

. In vivo inhibition of human neutrophil collagenase (MMP-8) activity during long-term combination therapy of doxycycline and non-steroidal anti-inflammatory drugs (NSAID) in acute reactive arthritis. Clin Exp Immunol 1994; 98: 21–28.

231.

Salminen

Pussinen

Payne

. Subantimicrobial-dose doxycycline treatment increases serum cholesterol efflux capacity from macrophages. Inflamm Res 2013; 62: 711–720.

232.

Golub

Lee

Ryan

. Tetracyclines inhibit connective tissue breakdown by multiple non-antimicrobial mechanisms. Adv Dent Res 1998; 12: 12–26.

233.

Akahane

Shah

. TIMP-1 stimulates proliferation of human aortic smooth muscle cells and Ras effector pathways. Biochem Biophys Res Commun 2004; 324: 440–445.

234.

Kormi

Alfakry

Tervahartiala

. The effect of prolonged systemic doxycycline therapy on serum tissue degrading proteinases in coronary bypass patients: a randomized, double-masked, placebo-controlled clinical trial. Inflamm Res 2014; 63: 329–334.

235.

Lauhio

Hästbacka

Pettila

. Serum MMP-8, -9 and TIMP-1 in sepsis: high serum levels of MMP-8 and TIMP-1 are associated with fatal outcome in a multicentre, prospective cohort study. Hypothetical impact of tetracyclines. Pharmacol Res 2011; 64: 590–594.

236.

Reinhardt

Stoner

Golub

. Association of gingival crevicular fluid biomarkers during periodontal maintenance with subsequent progressive periodontitis. J Periodontol 2010; 81: 251–259.

237.

Frankwich

Tibble

Torres-Gonzalez

. Proof of concept: matrix metalloproteinase inhibitor decreases inflammation and improves muscle insulin sensitivity in people with type 2 diabetes. J Inflamm (Lond) 2012; 9: 35–35.

238.

DeLano

Schmid-Schonbein

. Proteinase activity and receptor cleavage: mechanism for insulin resistance in the spontaneously hypertensive rat. Hypertension 2008; 52: 415–423.

239.

Smith

Leyden

. Safety of doxycycline and minocycline: a systematic review. Clin Ther 2005; 27: 1329–1342.

240.

Akman

Canakci

Kara

. Therapeutic effects of alpha lipoic acid and vitamin C on alveolar bone resorption after experimental periodontitis in rats: a biochemical, histochemical, and stereologic study. J Periodontol 2013; 84: 666–674.

241.

Gomes

Pires

Zuza

. Myeloperoxidase as inflammatory marker of periodontal disease: experimental study in rats. Immunol Invest 2009; 38: 117–122.

242.

Spolidorio

Lucas

Steffens

. Influence of parstatin on experimental periodontal disease and repair in rats. J Periodontol 2014; 85: 1266–1274.

243.

Araujo

Lopes de Souza

Souza

. Olmesartan decreases IL-1beta and TNF-alpha levels; downregulates MMP-2, MMP-9, COX-2, and RANKL; and upregulates OPG in experimental periodontitis. Naunyn Schmiedebergs Arch Pharmacol 2013; 386: 875–884.

244.

Araujo

Varela

Brito

. Azilsartan increases levels of IL-10, down-regulates MMP-2, MMP-9, RANKL/RANK, Cathepsin K and up-regulates OPG in an experimental periodontitis model. PLoS One 2014; 9: e96750–e96750.

245.

de Araujo Junior

Souza

de Medeiros

. Carvedilol decrease IL-1beta and TNF-alpha, inhibits MMP-2, MMP-9, COX-2, and RANKL expression, and up-regulates OPG in a rat model of periodontitis. PLoS One 2013; 8: e66391–e66391.

246.

de Araujo Junior

Souza

de Moura

. Atorvastatin decreases bone loss, inflammation and oxidative stress in experimental periodontitis. PLoS One 2013; 8: e75322–e75322.

247.

Holzhausen

Balejo

Lara

. Nafamostat mesilate, a potent tryptase inhibitor, modulates periodontitis in rats. Clin Oral Investig 2011; 15: 967–973.

248.

Goes

Melo

Silva

. Low-dose combination of alendronate and atorvastatin reduces ligature-induced alveolar bone loss in rats. J Periodontal Res 2014; 49: 45–54.

249.

Kumar

Reynolds

. Statins downregulate myeloperoxidase gene expression in macrophages. Biochem Biophys Res Commun 2005; 331: 442–451.

250.

Dalcico

de Menezes

Deocleciano

. Protective mechanisms of simvastatin in experimental periodontal disease. J Periodontol 2013; 84: 1145–1157.

251.

Kadoglou

Sailer

Fotiadis

. The impact of type 2 diabetes and atorvastatin treatment on serum levels of MMP-7 and MMP-8. Exp Clin Endocrinol Diabetes 2014; 122: 44–49.

252.

Malle

Furtmuller

Sattler

. Myeloperoxidase: a target for new drug development? Br J Pharmacol 2007; 152: 838–854.

253.

McCarty

. Supplementary taurine may stabilize atheromatous plaque by antagonizing the activation of metalloproteinases by hypochlorous acid. Med Hypotheses 2004; 63: 414–418.

254.

Rathnayake

Gustafsson

Norhammar

. Salivary matrix metalloproteinase-8 and -9 and myeloperoxidase in relation to coronary heart and periodontal diseases: a subgroup report from the PAROKRANK study (periodontitis and its relation to coronary artery disease). PLoS One 2015; 10: e0126370–e0126370.

255.

Messas

Batista

EL Jr

. Porphyromonas gingivalis infection accelerates the progression of atherosclerosis in a heterozygous apolipoprotein E-deficient murine model. Circulation 2002; 105: 861–867.

256.

Liu

Xie

Huang

. Elevated serum myeloperoxidase activities are significantly associated with the prevalence of ACS and High LDL-C levels in CHD patients. J Atheroscler Thromb 2012; 19: 435–443.

257.

Spallarossa

Garibaldi

Barisione

. Postprandial serum induces apoptosis in endothelial cells: Role of polymorphonuclear-derived myeloperoxidase and metalloproteinase-9 activity. Atherosclerosis 2008; 198: 458–467.

258.

Alfakry

Sinisalo

Paju

. The association of serum neutrophil markers and acute coronary syndrome. Scand J Immunol 2012; 76: 181–187.

259.

D'Aiuto

Nibali

Parkar

. Oxidative stress, systemic inflammation, and severe periodontitis. J Dent Res 2010; 89: 1241–1246.

Neutrophil proteolytic activation cascades: a possible mechanistic link between chronic periodontitis and coronary heart disease

Abstract

Keywords

Introduction

Chronic periodontitis

Coronary heart disease

Association of CP and CHD

MMPs and their regulators in periodontitis and CHD

MMP-8 (collagenase-2)

MMP-9 (gelatinase B)

MMP-7 (matrilysin-1)

TIMPs

NE

MPO

Neutrophil proteolytic activation cascades

Doxycycline and other medications used for reducing MMPs or MPO and low-grade inflammation

Conclusion

Footnotes

Funding

Conflict of interest

References