NLRP6, a member of the nucleotide-binding domain, leucine-rich repeat-containing (NLR) innate immune receptor family, has been reported to participate in inflammasome formation. Activation of inflammasome triggers a caspase-1–dependent programming cell death called pyroptosis. However, whether NLRP6 induces pyroptosis has not been investigated. In this study, we showed that NLRP6 overexpression activated caspase-1 and gasdermin-D and then induced pyroptosis of human gingival fibroblasts, resulting in release of proinflammatory mediators interleukin (IL)–1β and IL-18. Moreover, NLRP6 was highly expressed in gingival tissue of periodontitis compared with healthy controls. Porphyromonas gingivalis, which is a commensal bacterium and has periodontopathic potential, induced pyroptosis of gingival fibroblasts by activation of NLRP6. Together, we, for the first time, identified that NLRP6 could induce pyroptosis of gingival fibroblasts by activation of caspase-1 and may play a role in periodontitis.
AhnHKangSGYoonSIKoHJKimPHHongEJAnBSLeeELeeGS. 2017. Methylene blue inhibits NLRP3, NLRC4, AIM2, and non-canonical inflammasome activation. Sci Rep. 7(1):12409.
2.
AnandPKMalireddiRKLukensJRVogelPBertinJLamkanfiMKannegantiTD. 2012. NLRP6 negatively regulates innate immunity and host defence against bacterial pathogens. Nature. 488(7411):389–393.
3.
BalvanJKrizovaAGumulecJRaudenskaMSladekZSedlackovaMBabulaPSztalmachovaMKizekRChmelikRet al. 2015. Multimodal holographic microscopy: distinction between apoptosis and oncosis. PLoS One. 10(3):e0121674.
4.
BirchenoughGMNystromEEJohanssonMEHanssonGC. 2016. A sentinel goblet cell guards the colonic crypt by triggering Nlrp6-dependent Muc2 secretion. Science. 352(6293):1535–1542.
5.
Chaves de SouzaJAFrasnelliSCCurylofo-ZottiFAAvila-CamposMJSpolidorioLCZamboniDSGravesDTRossaCJr.2016. NOD1 in the modulation of host-microbe interactions and inflammatory bone resorption in the periodontal disease model. Immunology. 149(4):374–385.
6.
DestaTGravesDT. 2007. Fibroblast apoptosis induced by Porphyromonas gingivalis is stimulated by a gingipain and caspase-independent pathway that involves apoptosis-inducing factor. Cell Microbiol. 9(11):2667–2675.
7.
DingJWangKLiuWSheYSunQShiJSunHWangDCShaoF. 2016. Pore-forming activity and structural autoinhibition of the gasdermin family. Nature. 535(7610):111–116.
8.
EdgeworthJDSpencerJPhaliponAGriffinGESansonettiPJ. 2002. Cytotoxicity and interleukin-1beta processing following Shigella flexneri infection of human monocyte-derived dendritic cells. Eur J Immunol. 32(5):1464–1471.
9.
ElinavEStrowigTHenao-MejiaJFlavellRA. 2011. Regulation of the antimicrobial response by NLR proteins. Immunity. 34(5):665–679.
10.
GravesDTCochranD. 2003. The contribution of interleukin-1 and tumor necrosis factor to periodontal tissue destruction. J Periodontol. 74(3):391–401.
11.
GrenierJMWangLManjiGAHuangWJAl-GarawiAKellyRCarlsonAMerriamSLoraJMBriskinMet al. 2002. Functional screening of five PYPAF family members identifies PYPAF5 as a novel regulator of NF-kappaB and caspase-1. FEBS Lett. 530(1–3):73–78.
12.
HsiaoPCLeeWJYangSFTanPChenHYLeeLMChangJLLaiGMChowJMChienMH. 2014. Nobiletin suppresses the proliferation and induces apoptosis involving MAPKs and caspase-8/-9/-3 signals in human acute myeloid leukemia cells. Tumour Biol. 35(12):11903–11911.
13.
HuangXYangXNiJXieBLiuYXuanDZhangJ. 2015. Hyperglucose contributes to periodontitis: involvement of the NLRP3 pathway by engaging the innate immunity of oral gingival epithelium. J Periodontol. 86(2):327–335.
14.
KempsterSLBeltekiGForheadAJFowdenALCatalanoRDLamBYMcFarlaneICharnock-JonesDSSmithGC. 2011. Developmental control of the Nlrp6 inflammasome and a substrate, IL-18, in mammalian intestine. Am J Physiol Gastrointest Liver Physiol. 300(2):G253–G263.
15.
Ketelut-CarneiroNSilvaGKRochaFAMilaneziCMCavalcanti-NetoFFZamboniDSSilvaJS. 2015. IL-18 triggered by the Nlrp3 inflammasome induces host innate resistance in a pulmonary model of fungal infection. J Immunol. 194(9):4507–4517.
16.
KimJYPatonJCBrilesDERheeDKPyoS. 2015. Streptococcus pneumoniae induces pyroptosis through the regulation of autophagy in murine microglia. Oncotarget. 6(42):44161–44178.
17.
LamkanfiMDixitVM. 2014. Mechanisms and functions of inflammasomes. Cell. 157(5):1013–1022.
18.
LawlorKEKhanNMildenhallAGerlicMCrokerBAD’CruzAAHallCKaur SpallSAndertonHMastersSLet al. 2015. RIPK3 promotes cell death and NLRP3 inflammasome activation in the absence of MLKL. Nat Commun. 6:6282.
19.
LechMAvila-FerrufinoASkuginnaVSusantiHEAndersHJ. 2010. Quantitative expression of RIG-like helicase, NOD-like receptor and inflammasome-related mRNAs in humans and mice. Int Immunol. 22(9):717–728.
20.
LeeYMFujikadoNManakaHYasudaHIwakuraY. 2010. IL-1 plays an important role in the bone metabolism under physiological conditions. Int Immunol. 22(10):805–816.
21.
LevyMThaissCAZeeviDDohnalovaLZilberman-SchapiraGMahdiJADavidESavidorAKoremTHerzigYet al. 2015. Microbiota-modulated metabolites shape the intestinal microenvironment by regulating NLRP6 inflammasome signaling. Cell. 163(6):1428–1443.
22.
LiuJDuanJWangYOuyangX. 2014. Intracellular adhesion molecule-1 is regulated by Porphyromonas gingivalis through nucleotide binding oligomerization domain-containing proteins 1 and 2 molecules in periodontal fibroblasts. J Periodontol. 85(2):358–368.
23.
LourencoTGHellerDSilva-BoghossianCMCottonSLPasterBJColomboAP. 2014. Microbial signature profiles of periodontally healthy and diseased patients. J Clin Periodontol. 41(11):1027–1036.
24.
MaZWangYZhuXZhangCLiSJinLShenYHaapasaloM. 2011. Role of polymorphonuclear neutrophils in the clearance of Enterococcus faecalis derived from saliva and infected root canals. J Endod. 37(3):346–352.
25.
MarchesanJJiaoYSchaffRAHaoJMorelliTKinneyJSGerowESheridanRRodriguesVPasterBJet al. 2016. TLR4, NOD1 and NOD2 mediate immune recognition of putative newly identified periodontal pathogens. Mol Oral Microbiol. 31(3):243–258.
26.
MartinonFBurnsKTschoppJ. 2002. The inflammasome: a molecular platform triggering activation of inflammatory caspases and processing of proIL-beta. Mol Cell. 10(2):417–426.
NormandSDelanoye-CrespinABressenotAHuotLGrandjeanTPeyrin-BirouletLLemoineYHotDChamaillardM. 2011. Nod-like receptor pyrin domain-containing protein 6 (NLRP6) controls epithelial self-renewal and colorectal carcinogenesis upon injury. Proc Natl Acad Sci USA. 108(23):9601–9606.
29.
OhHHiranoJTakaiHOgataY. 2015. Effects of initial periodontal therapy on interleukin-1β level in gingival crevicular fluid and clinical periodontal parameters. J Oral Sci. 57(2):67–71.
30.
ReddyVSPrabhuSDMummidiSValenteAJVenkatesanBShanmugamPDelafontainePChandrasekarB. 2010. Interleukin-18 induces EMMPRIN expression in primary cardiomyocytes via JNK/Sp1 signaling and MMP-9 in part via EMMPRIN and through AP-1 and NF-kappaB activation. Am J Physiol Heart Circ Physiol. 299(4):H1242–H1254.
31.
SauerJDWitteCEZemanskyJHansonBLauerPPortnoyDA. 2010. Listeria monocytogenes triggers AIM2-mediated pyroptosis upon infrequent bacteriolysis in the macrophage cytosol. Cell Host Microbe. 7(5):412–419.
32.
SborgiLRuhlSMulvihillEPipercevicJHeiligRStahlbergHFaradyCJMullerDJBrozPHillerS. 2016. GSDMD membrane pore formation constitutes the mechanism of pyroptotic cell death. EMBO J. 35(16):1766–1778.
33.
ShiJZhaoYWangKShiXWangYHuangHZhuangYCaiTWangFShaoF. 2015. Cleavage of GSDMD by inflammatory caspases determines pyroptotic cell death. Nature. 526(7575):660–665.
34.
ValenteAJYoshidaTMurthySNSakamuriSSKatsuyamaMClarkRADelafontainePChandrasekarB. 2012. Angiotensin II enhances AT1-Nox1 binding and stimulates arterial smooth muscle cell migration and proliferation through AT1, Nox1, and interleukin-18. Am J Physiol Heart Circ Physiol. 303(3):H282–H296.
35.
WanMLiuJRWuDChiXPOuyangXY. 2015. E-selectin expression induced by Porphyromonas gingivalis in human endothelial cells via nucleotide-binding oligomerization domain-like receptors and Toll-like receptors. Mol Oral Microbiol. 30(5):399–410.
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
