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Abstract

Viral myocarditis is an inflammation of the myocardium, and coxsackievirus B3 (CVB3) is one of the most important etiologic agents. Curcumin is an active ingredient of Curcumin longa, which has been used as a traditional Chinese herb for the treatment of various inflammatory diseases. The aim of this study was to explore the therapeutic effect of curcumin on CVB3-induced myocarditis and the underlying mechanism. Our results showed that treatment with curcumin could significantly attenuate CVB3-induced myocarditis, as demonstrated by improved weight loss, increased survival rate, reduced serological level cardiac enzymes, and improved heart histopathology. Of importance, curcumin administration was revealed to significantly reduce the systemic and local myocardial expression of proinflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL) 6, and IL-1β, in the CVB3-infected mice. Further study showed that curcumin treatment significantly inhibited the CVB3-induced activation of nuclear factor-κB (NF-κB), a key transcription factor in the pathogenesis of inflammation, in a phosphatidylinositol 3 kinase (PI3K)/Akt pathway-dependent manner. These data indicate that curcumin has protective effect against CVB3-induced myocarditis by inhibiting PI3K/Akt/NF-κB signaling pathway and thus reducing the inflammatory response.

Keywords

coxsackievirus myocarditis curcumin proinflammatory cytokines NF-κB PI3K/Akt

Introduction

Acute viral myocarditis characterized by myocardial inflammatory infiltrate is an important cause of dilated cardiomyopathy and can even progress to advanced congestive heart failure.^1–3 Coxsackievirus B3 (CVB3), a nonenveloped single positive polarity RNA enterovirus of the Picornaviridae family, is the most frequent cause of viral myocarditis in humans.^4–8 Virus-induced myocarditis is a triphasic disease involving an initial viral infection, followed by autoimmune response and finally remodeling of cardiac structure and function. It is reported that CVB3 itself can directly hurt myocytes; however, growing evidence suggests that the excessive immune response may play a more critical role in the pathogenesis of CVB3-induced myocarditis.^2,3,8,9

The eukarytoic transcription factor nuclear factor-κB (NF-κB) is known to play a critical role in host inflammatory response to CVB3 infection by controlling the expression of a variety of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL) 6, and IL-1β.^10–13 Of note, there is direct evidence that inhibiting NF-κB activity by NF-κB inhibitor SUN C8079 or pyrrolidine dithiocarbamate can block the production of proinflammatory cytokines in cardiac tissues or myocytes, thus preventing the development of myocarditis.^14,15 The intracellular signaling cascades controlling NF-κB activation are highly complex and involve a distinct set of kinases. Of the potential protein kinases involved in the activation of NF-κB, phosphatidylinositol 3 kinase (PI3K)/Akt receives particular attention, and reports also indicate that PI3K/Akt pathway may be an important therapeutic target for many inflammatory diseases, including cardiovascular diseases.^16–19 Despite improvements in studying viral pathology and molecular biology, as well as improved disease diagnosis, the therapy for CVB3-induced myocarditis is still not satisfactory,^3,8 which underscores the importance of searching for new therapeutic compounds.

Curcumin (diferuloylmethane) is a natural polyphenol derived from the root of the plant Curcuma longa, which has been used as a traditional Chinese medicine for the treatment of many inflammatory diseases. Recent evidence indicates that curcumin has many biological activities, including anti-inflammatory, antioxidant, and antiproliferative properties. It is reported that the anti-inflammatory actions of curcumin mainly involve the regulation of some signal transduction pathways, including NF-κB and PI3K/Akt.^20–26 Safety evaluation studies indicate that curcumin is well tolerated at a very high dose without any toxic effects. Recent studies also show that curcumin has a promising potential for the treatment of various diseases, including cancer, arthritis, inflammatory bowel disease, cardiovascular diseases, and others.^27–30 However, whether curcumin possesses therapeutic effect on CVB3-induced myocarditis remains unclear.

In the present investigation, curcumin was administered daily to CVB3-infected mice, and its therapeutic effect on CVB3-induced myocarditis was assessed following virus infection. The underlying mechanisms by which curcumin attenuated CVB3-induced myocarditis, especially its effect on inflammatory response and PI3K/Akt/NF-κB activation, were also carefully investigated.

Materials and Methods

Mice and Virus

Six-week-old male BALB/c mice were purchased from the experimental animal center of the Chinese Academy of Science (Shanghai, China). All mice were maintained in the Shanghai Jiaotong University School of Medicine animal facilities under specific pathogen-free conditions, and all animal experiments were performed according to the guidelines for the care and use of laboratory animals (Ministry of Health, PR China, 1998) and guidelines of the Laboratory Animal Ethical Commission of Shanghai Jiaotong University. The CVB3 (Nancy strain) was prepared by passage through HeLa cells. Viral titers were routinely determined prior to infection by a 50% tissue culture infectious dose (TCID₅₀) assay of HeLa cell monolayers. BALB/c mice were infected by an intraperitoneal injection of 0.2 mL of RPMI-1640 (Gibco) containing approximately 10³ TCID₅₀ of the virus at day 0. Curcumin was purchased from Sigma (catalog number is C7727; ≥94% curcuminoid content with ≥80% curcumin) and dissolved in 0.1% dimethyl sulfoxide (DMSO). The CVB3-infected mice were treated daily with vehicle (0.1% DMSO) or curcumin (100 mg/kg) by intragastric tube from days 0 to 14.

Pathologic Examination

Seven days following CVB3 infection, hearts of surviving mice were collected and fixed in 10% buffered formalin for the hematoxylin and eosin stains. Transverse sections of the myocardium were graded for the severity of necrosis and mononuclear cell infiltration as follows: grade 0, no; grade 1, 25% of the heart section is involved; grade 2, 25% to 50%; grade 3, 50% to 75%; and grade 4, more than 75%. Sections were examined by 2 independent investigators in a blinded manner.

Analysis of Serological Index of Myocarditis

Serum lactate dehydrogenase (LDH), aspartate aminotransferase (AST), creatine kinase (CK), and MB isoenzyme of CK-MB activities were determined on a chemistry analyzer (Dimension RxL Max; Siemens Healthcare Diagnostics) using commercial kits.

Viral Titers in the Heart Tissue

Seven days after 10³ TCID₅₀ CVB3 infections, one part of each heart was removed, weighed, and homogenized. After centrifugation, the supernatants were subjected to 10-fold dilutions in DMEM. Viral titers were determined by TCID₅₀ assays.

Cytokine Enzyme-Linked Immunosorbent Assay

The levels of TNF-α, IL-6, and IL-1β in mice sera and heart tissues were measured by enzyme-linked immunosorbent assay (ELISA; R&D system) according to the manufacturer’s instructions. Briefly, the plates were coated with diluted capture antibody (100 μL/well) and incubated overnight at 4°C. Plates were washed (300 μL of phosphate-buffered saline [PBS]-Tween, 3 times), blocked, and emptied. Samples and standards were added to triplicate wells (100 μL/well), and plates were incubated at room temperature for 2 hours. After washing, biotinylated detection antibody was added for 1 hour, followed by 100 μL of strepavidin-conjugated horseradish peroxidase for 1 hour at 37°C. After washing, 3,3′,5,5′-tetramethylbenzidine substrate was added to each well. After 10 minutes, 50 μL of stop solution (2 N H₂SO4) was added and absorbance was measured at 450 nm. For each plate standard curve was used to calculate the absolute concentrations of the indicated cytokines.

Western Blot Analysis

Equal amounts of the total protein (50 μg/lane) were separated by 10% sodium dodecyl–polyacrylamide gel electrophoresis and sequentially transferred onto polyvinylidene difluoride microporous membrane. The membrane was incubated with antibodies to phosphor-/total IkBα, PI3K, Akt (Cell Signalling Technology, CST, Beverly, Massachusetts), or actin (Santa Cruz Biotechnology, Santa Cruz, California) overnight at 4°C and then again incubated with the corresponding peroxidase-linked secondary antibody. Immunoreactive proteins were detected by an enhanced chemiluminescence kit (Pierce, Rockford, Illinois).

Electrophoretic Mobility Shift Assay

Nuclear extracts from heart tissues or primary myocytes were isolated by NE-PER reagents (Pierce) following manufacturer recommendations. Nuclear extract of 5 μg was preincubated on ice with 2 μg of poly(deoxyinosine-deoxycytosine) as an unspecific competitor in band shift buffer (50 mmol/L Tris, 150 mmol/L KCl, 5% glycerol, 10 mmol/L MgCl₂, 0.1% NP-40, 5 mmol/L EDTA, and 2.5 mmol/L DTT) for 15 minutes. Biotin-labeled oligonucleotides containing the NF-κB consensus-binding sequence (5′-GGGGACTTTCCC-3′) were then added to a total volume of 20 μL, incubated on ice for 30 minutes, and loaded onto 6% native polyacrylamide gels in 0.5× TBE buffer. The gels were blotted on nylon membrane, and the blot was cross-linked by ultraviolet irradiation. Biotin-labeled probe was detected by a light shift chemiluminescent electrophoretic mobility shift assay (EMSA) kit (Pierce) according to the manufacturer’s instructions.

An ELISA-Based NF-κB Assay

An ELISA-based kit was used for quantitative detection of NF-κB activity (TransAM NF-κB kit; Active Motif Europe, Rixensart, Belgium). In brief, 5 μg of nuclear extract, diluted to 20 μL, was added to the wells coated with oligonucleotides containing the NF-κB consensus-binding site. For the detection of activated NF-κB, antibodies against the p65 were used, followed by a secondary antibody conjugated to horseradish peroxidase. The colorimetric readout (450 nm) was done with an ELISA plate reader.

Isolation of Neonatal Myocytes

The neonatal mouse myocytes were isolated as described previously.^15,31 Briefly, hearts were obtained from mice within 72 hours of birth, minced finely, and subjected to stepwise digestion with 0.25% trypsin. The single-cell suspension was washed and depleted of endothelial cells and fibroblasts by 2 sequential 1-hour adsorptions to plastic flasks at 37°C. The nonadherent myocytes were retrieved and resuspended in complete basal medium and dispensed into tissue culture wells. After a period of 48 hours, the myocytes were attached firmly to the plastic.

Plasmid Construction and Transfection

Mouse Akt (protein kinase B) complementary DNA was obtained by polymerase chain reaction with reverse transcription (RT-PCR) on total RNA from splenocytes and then cloned into the mammalian expression vector pCDNA3 (Invitrogen). The recombinant construct was verified by automated DNA sequencing. The primary myocytes were transfected with empty vector or pCDNA-Akt using the Neonatal Nucleofector kit (no. VPE-1002; Amaxa).

Statistics

Data are presented as mean ± standard deviation. Statistical analyses were performed using the unpaired Student t test. The survival rates of CVB3-infected mice were compared and analyzed with Kaplan-Meier plot. Differences were considered to be statistically significant when P < .05.

Results

Curcumin Administration Leads to Less Weight Loss and Reduced Mortality in CVB3-Infected Mice

To explore the therapeutic effect of curcumin on CVB3-induced myocarditis, mice were infected with 10³ TCID₅₀ CVB3 and then treated with curcumin (100 mg/kg) or vehicle (0.1% DMSO) daily by intragastric tube. The body weight and survival rate were monitored during the following 2 weeks. Results showed that vehicle-treated mice underwent a significant and persistent loss of body weight, while mice treated with curcumin presented almost no weight loss (Figure 1A). Furthermore, mice receiving curcumin had a significantly improved survival rate compared with vehicle-treated mice (Figure 1B).

Figure 1.

Weight profile and survival rate of CVB3-infected mice treated with or without curcumin. BALB/c mice were infected with CVB3 on day 0 and then treated with curcumin (n = 12) or vehicle (0.1% dimethyl sulfoxide [DMSO]; n = 12) by intragastric tube daily from days 0 to 14. The body weight change (A) and survival rate (B) were, respectively, monitored daily until days 7 and 14 postinfection. Data are shown as the mean ± standard deviation. * P < .05. CVB3 indicates coxsackievirus B3.

Heart Tissue Injuries Are Reduced in Curcumin-Treated Mice

To examine the situation of heart tissue, the serological indices and pathological observation were carefully evaluated. It is known that LDH, AST, CK, and CKMB are cardiac enzymes, and the blood level of these enzymes will be upregulated significantly once the heart gets damaged. We thus carefully tested the concentration of these cardiac enzymes in mice sera. As shown in Figure 2A to D, the serum levels of LDH, AST, CK, and CKMB were significantly decreased in curcumin-treated mice compared to vehicle-treated mice. Furthermore, histological analysis of cardiac tissue sections revealed that CVB3-infected mice developed severe myocarditis reflected by tissue damage and massive inflammatory cell infiltration, while curcumin treatment led to a markedly reduced inflammation (Figure 2E and F). Taken together, these data indicated that curcumin administration could efficiently attenuate heart tissue injuries induced by CVB3. To test the viral loads in CVB3-infected mice, at day 7 postinfection, mice were killed and the viral titers in the heart were examined. As shown in Figure 2G, curcumin treatment did not have significant effect on the viral titres, indicating that the cucurmin-mediated inhibitory effect on CVB3-induced myocarditis might not be due to the viral clearance.

Figure 2.

The effect of curcumin treatment on tissue damage of CVB3-infected mice. BALB/c mice were challenged with CVB3 and treated with curcumin or vehicle (0.1% dimethyl sulfoxide [DMSO]). A-D, Cardiac enzyme profiles of CVB3-infected mouse sera. Blood samples were collected at 7 days postinfection. Lactate dehydrogenase (LDH), aspartate aminotransferase (AST), creatine kinase (CK), and CKMB levels were analyzed. Data were shown as the mean ± SD (n = 8 per group). *P < .05. E, Paraffin sections of heart tissues were prepared, and cardiac inflammation was revealed by hematoxylin and eosin staining. The severity of myocarditis was scored by a standard 0 to 4 scale according to the foci of mononuclear infiltration and myocardial necrosis. *P < .05. F, One representative heart section was shown for each group, magnification ×200. G, The effect of curcumin treatment on viral loads of CVB3-infected mice. Viral loads in the heart tissue were determined as described in Materials and Methods. Data are shown as the mean ± SD (n = 8 per group). *P < .05. ND indicates not detected; SD, standard deviation.

Curcumin Treatment Reduces the Production of Proinfammatory Cytokines

We further investigated whether curcumin could inhibit the production of proinflammatory cytokine, thus relieving CVB3-induced myocardial inflammation. Results obtained from ELISA analysis showed that curcumin administration efficiently suppressed the production of TNF-α, IL-6, and IL-1β in mice sera (Figure 3A-C). To determine the effect of curcumin on the local myocardial expression of these proinflammatory cytokines, we obtained the heart tissue homogenesized and measured the cytokine concentration in the supernates by ELISA technique. As shown in Figure 3D and E, curcumin treatment also efficiently inhibited the local myocardial expression of these proinflammatory cytokines (TNF-α, IL-6, and IL-1β).

Figure 3.

Inflammatory cytokine expression profiles of CVB3-infected mice following curcumin treatment. BALB/c mice were challenged with CVB3 and treated with curcumin or vehicle (0.1% dimethyl sulfoxide [DMSO]). Protein levels of TNF-α (A), IL-6 (B), and IL-1β (C) in the sera and TNF-α (D), IL-6 (E), and IL-1β (F) in the homogenized heart tissue were determined by enzyme-linked immunosorbent assay (ELISA) on day 7 postinfection. Data are shown as the mean ± standard deviation (n = 8 per group). *P < .05. CVB3 indicates coxsackievirus B3; IL, interleukin; TNF-α, tumor necrosis factor-α.

Curcumin Treatment Inhibits CVB3-Induced NF-κB Activation

The NF-κB is reported to play a central role in regulating the induction of a variety of proinflammatory cytokines in cardiac inflammation,^10–15 and our earlier data demonstrated that the curcumin treatment could efficiently inhibit the production of proinflammatory cytokines (TNF-α, IL-6, and IL-1β) induced by CVB3. We therefore investigate the effect of curcumin on CVB3-induced NF-κB activity by isolating nuclear extract from heart tissue of live mice and performing electrophoretic mobility shift assay (EMSA). It was found that CVB3 infection significantly increased the NF-κB-binding activity, but this event was repressed efficiently by curcumin treatment (Figure 4A). The inhibitory effect of curcumin on CVB3-induced NF-κB-binding activity was further confirmed by an ELISA-based NF-κB assay (Figure 4B).

Figure 4.

The effect of curcumin treatment on NF-κB activation in CVB3-infected mice. BALB/c mice were challenged with CVB3 and treated with or without curcumin. On day 7 postinfection, nuclear extracts were isolated from myocardial tissue and subjected to electrophoretic mobility shift assay (EMSA; A) and an enzyme-linked immunosorbent assay (ELISA)-based NF-κB assay (B) as described in Materials and methods. Data are shown as the mean ± standard deviation (n = 8 per group). *P < .05. C, Protein levels of phosphorylated and total IκBα in myocardial tissue were determined by Western blot. Actin was used as a loading control. Similar results were obtained in 3 separate experiments. NF-κB indicates nuclear factor-κB.

One of the most important steps in NF-κB activation is the dissociation of IkBα, which is mediated via phosphorylation and subsequent ubiquitin-proteasomal degradation of this inhibitory subunit.³² To determine whether curcumin-mediated inhibition of NF-κB DNA binding was due to its suppressive effect on IkBα degradation via phosphorylation, the expression levels of phosphorylated and total IκBα in the myocardial tissue were determined by Western blot analysis. As shown in Figure 4C, CVB3 infection indeed enhanced the phosphorylation of IκBα and led to the degradation of total IκBα; however, these events could be reversed by curcumin treatment.

Curcumin Treatment Inhibits CVB3-Induced PI3K/Akt Activation

The PI3K/Akt signaling pathway is reported to be important for NF-κB activation via the regulation of IκBα phosphorylation and degradation.^16–19 We thus wondered whether curcumin-mediated inhibition of CVB3-induced NF-κB activation involved the PI3K/Akt pathway. To test this possibility, we examined the effect of curcumin on PI3K/Akt activation induced by CVB3. Western blot analysis showed that the phosphorylation of PI3K or Akt in the myocardial tissue increased significantly upon CVB3 infection; however, curcumin treatment dramatically repressed these events (Figure 5).

Figure 5.

The effect of curcumin treatment on PI3K/Akt activation in CVB3-infected mice. BALB/c mice were challenged with CVB3 and treated with or without curcumin. On day 7 postinfection, phosphorylated and total PI3K and Akt in myocardial tissue were determined by Western blot. PI3K indicates phosphatidylinositol 3 kinase.

Coxsackievirus B3 Activates NF-κB Through a PI3K/Akt-Dependent Pathway

To further verify whether the activation of NF-κB induced by CVB3 was dependent on the activation of PI3K/Akt pathway, we isolated the primary cardiomyocytes and infected these cells with CVB3 in the presence or absence of PI3K/Akt signaling inhibitor LY294002. It was found that, consistent with the in vivo analysis, CVB3 infection led to the phosphorylation and degradation of IκBα (Figure 6A) and enhanced NF-κB DNA-binding activity significantly (Figure 6B). However, inhibition of PI3K/Akt signaling by LY294002 substantially attenuated these activities (Figure 6A and B). Furthermore, we have investigated the role of PI3K/Akt pathway in curcumin-mediated inhibition of CVB3-induced NF-κB activation by overexpressing Akt in primary cardiomyocytes. It was found that overexpression of Akt significantly attenuated curcumin-mediated inhibitory effect on CVB3-induced phosphorylation and degradation of IκBα (Figure 6C), as well as on CVB3-induced NF-κB DNA-binding activity (Figure 6D). Together, these data suggested that CVB3 induced the NF-κB activation via the PI3K/Akt pathway

Figure 6.

The CVB3 activates NF-κB through a PI3K/Akt-dependent pathway. A, The effect of inhibiting PI3K/Akt pathway on IκBα phosphorylation and degradation induced by CVB3. Cardiac myocytes were pretreated with vehicle or PI3K inhibitor LY-240029 (10 μmol/L) for 1 hour followed by CVB3 infection (MOI = 10) for 6 hours. Cells were then subjected to Western blotting using indicated antibodies. B, The effect of inhibiting PI3K/Akt pathway on CVB3-induced NF-κB-binding activity. Cardiac myocytes were treated as in (A), and nuclear extracts were isolated and subjected to the ELISA-based NF-κB assay. Data were shown as the mean ± SD. *P < .05. C, The effect of Akt overexpression on curcumin-mediated inhibition of CVB3-induced IκBα phosphorylation and degradation. Cardiac myocytes were transfected with empty vector or Akt expression plasmid (pCDNA-Akt). Twenty-four hours posttransfection, cells were infected with CVB3 (MOI = 10) for 6 hours in the presence or absence of curcumin (20 μmol/L), followed by Western blot using indicated antibodies. D, The effect of Akt overexpression on curcumin-mediated inhibition of CVB3-induced NF-κB-binding activity. Cells were treated as in (C), and nuclear extracts were isolated and subjected to the ELISA-based NF-κB assay. Data were shown as the mean ± SD. *P < .05. CVB3 indicates coxsackievirus B3; ELISA, enzyme-linked immunosorbent assay; MOI, multiplicity of infection; NF-κB, nuclear factor-κB; PI3K, phosphatidylinositol 3-kinase; SD, standard deviation.

Discussion

Viral myocarditis, which is mainly caused by CVB3 infection, affects about 5% to 20% of the world population.³³ Although Rezkalla et al³⁴ reported that captopril is beneficial in acute CVB3-induced myocarditis, there is still much to be done to improve the therapy for this disease. In the current investigation, we explored the therapeutic effect of curcumin on CVB3-induced myocarditis.

It was found that curcumin, a naturally occurring anti-inflammatory and antioxidant compound, could significantly attenuate CVB3-induced myocarditis, as evidenced by significantly reduced serological levels of cardiac enzymes, less myocardial inflammation, increased survival rate, and so on. Although some studies found that the virus itself can hurt myocytes directly, there is more evidence to support the idea that the excessively activated immune response, rather than any direct viral mechanism, is primarily responsible for myocyte damage.^35,36 Recent studies also showed that levels of circulating proinflammatory cytokines, such as TNF-α, IL-6, and IL-1β, were elevated significantly in patients with myocarditis.³⁷ To explore the mechanism by which curcumin ameliorated CVB3-induced myocarditis, the expression profiles of these inflammatory cytokines were examined. It was found that curcumin treatment efficiently reduced both the systemic and the local myocardial expression of TNF-α, IL-6, and IL-1β.

It is well established that NF-κB is an important intracellular transcription factor and usually exists as latent cytoplasmic complex bound to its inhibitory protein IκB. Once IκB degraded, NF-κB is free to translocate into the nucleus and regulates NF-κB-dependent gene expression.³² As NF-κB activity has been proved to be essential for the production of proinflammatory cytokines in cardiac myocytes, and curcumin is also reported to display anti-inflammatory properties through the inhibition of NF-κB activity,^21–25 we therefore evaluated the effect of curcumin on NF-κB activity in CVB3-infected mice. Our results showed that curcumin efficiently inhibited CVB3-induced NF-κB-binding activity in murine heart tissue. It was also found that CVB3 infection resulted in the phosphorylation and degradation of NF-κB inhibitor IκBα, but this process could be repressed by the treatment of curcumin, further demonstrating the inhibitory effect of curcumin on CVB3-induced NF-κB activation.

The molecular mechanisms involved in NF-κB activation in response to various external stimuli have not been fully clarified. One of the most extensively investigated intracellular signaling cascades involved in proinflammatory responses is the PI3K/Akt kinase pathway. This pathway has been reported to influence NF-κB activity by promoting IKK activation and subsequent phosphorylation and degradation of IκBα, which activates the RelA/p65 subunit of NF-κB in a number of systems. Accumulating in vivo and in vitro evidences also indicated that treatment with curcumin inhibited the phosphorylation of PI3K and Akt in a number of experimental systems.^{16–19,38,39} We are thus interested to know whether the curcumin-mediated inhibitory effect on CVB3-induced myocarditis was linked to the inhibition of PI3K/Akt pathway. Our results showed that CVB3 infection led to the phosphorylation of PI3K and Akt, which is suppressed by curcumin; and treatment of myocardial cells with LY294002 indeed not only inhibited the CVB3-induced phosphorylation of PI3K and Akt but also markedly repressed the activation of NF-κB induced by CVB3 infection. Furthermore, our data revealed that overexpression of Akt significantly attentuated curcumin-mediated inhibition of CVB3-induced NF-κB activation.

In conclusion, the present study indicates curcumin, as an inhibitor of PI3K/Akt/NF-κB signaling pathway, has the potential to protect mice against cardiac inflammation through the suppression of proinflammatory responses and may provide a novel therapeutic strategy for acute myocarditis induced by CVB3.

Footnotes

Declaration of Conflicting Interests

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

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by grants from the Foundation of Shanghai Shenkang Hospital Development Centre (No. SHDC12010215).

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Yajima

Knowlton

. Viral myocarditis: from the perspective of the virus. Circulation. 2009;119(19):2615–2624.

Curcumin Protects Mice From Coxsackievirus B3-Induced Myocarditis by Inhibiting the Phosphatidylinositol 3 kinase/Akt/Nuclear Factor-κB Pathway

Abstract

Keywords

Introduction

Materials and Methods

Mice and Virus

Pathologic Examination

Analysis of Serological Index of Myocarditis

Viral Titers in the Heart Tissue

Cytokine Enzyme-Linked Immunosorbent Assay

Western Blot Analysis

Electrophoretic Mobility Shift Assay

An ELISA-Based NF-κB Assay

Isolation of Neonatal Myocytes

Plasmid Construction and Transfection

Statistics

Results

Curcumin Administration Leads to Less Weight Loss and Reduced Mortality in CVB3-Infected Mice

Heart Tissue Injuries Are Reduced in Curcumin-Treated Mice

Curcumin Treatment Reduces the Production of Proinfammatory Cytokines

Curcumin Treatment Inhibits CVB3-Induced NF-κB Activation

Curcumin Treatment Inhibits CVB3-Induced PI3K/Akt Activation

Coxsackievirus B3 Activates NF-κB Through a PI3K/Akt-Dependent Pathway

Discussion

Footnotes

Declaration of Conflicting Interests

Funding

References