Cathelicidin aggravates myocardial ischemia/reperfusion injury via activating TLR4 signaling and P2X7R/NLRP3 inflammasome

Yan Wu, Yacheng Zhang, Jie Zhang, Tingting Zhai, Jingping Hu, Hairong Luo, Haiyan Zhou, Qinghai Zhang, Zhiguang Zhou, Feng Liu

Research output: Contribution to journalArticle

Abstract

Aims: The antimicrobial peptide cathelicidin (Camp) has multifunctional immunomodulatory activities. However, its roles in inflammation-related myocardial ischemia/reperfusion (MI/R) injury remain unclear. Methods and results: In this study, adult male C57BL/6 wild-type (WT) mice were subjected to MI/R injury by left anterior descending coronary artery ligation for 45 min followed by 3 or 24 h of reperfusion. An abundant cardiac expression of cathelicidin was observed during ischemia and reperfusion, which was mainly derived from heart-infiltrating neutrophils. Knockout of Camp in mice reduced MI/R-induced myocardial inflammation, infarct size, and circulating cTnI levels (an indicator of heart damage). CRAMP (the mature form of murine cathelicidin) administration of WT mice immediately before MI/R exerted detrimental effects on the reperfused heart. CRAMP exacerbates MI/R injury via a TLR4 and P2X7R/NLRP3 inflammasome-dependent mechanism, since I/R-induced myocardial infarction was reserved by inhibition of TLR4, P2X7R, or NLRP3 inflammasome in CRAMP-treated WT mice. Depletion of neutrophils before MI/R abrogated the amplification of infarct size in CRAMP-treated WT mice. Heart-infiltrating neutrophils were found to be one of major cellular sources of myocardial IL-1β (a “first line” pro-inflammatory cytokine) at the early stage of MI/R. At this stage, CRAMP administration just before MI/R induced pro-IL-1β protein expression in heart-infiltrating neutrophils, but not in non-neutrophils. In vitro experiments showed that LL-37 (the mature form of human cathelicidin) treatment promotes the processing and secretion of IL-1β from human neutrophils via stimulating TLR4 signaling and P2X7R/NLRP3 inflammasome. Conclusions: Our findings reveal that, at the early stage of MI/R, neutrophil-derived cathelicidin plays an injurious role in the heart. Cathelicidin aggravates MI/R injury by over-activating TLR4 signaling and P2X7R/NLRP3 inflammasome in heart-infiltrating neutrophils, which leads to the excessive secretion of IL-1β and subsequent inflammatory injury.

Original languageEnglish (US)
Pages (from-to)75-86
Number of pages12
JournalJournal of Molecular and Cellular Cardiology
Volume139
DOIs
Publication statusPublished - Feb 2020

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Keywords

  • Cathelicidin
  • Ischemia/reperfusion
  • Neutrophils
  • NLRP3 inflammasome
  • P2XR
  • TLR4

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

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