Toll-like receptor 2 activation by bacterial peptidoglycan-associated lipoprotein activates cardiomyocyte inflammation and contractile dysfunction

Xinsheng Zhu, Aranya Bagchi, Huailong Zhao, Carsten J. Kirschning, Roger J. Hajjar, Wei Chao, Judith Hellman, Ulrich Schmidt

Research output: Contribution to journalArticlepeer-review

57 Scopus citations

Abstract

OBJECTIVE: Although cardiac dysfunction plays an important role in the pathogenesis of sepsis, the mechanisms that underlie cardiac dysfunction in sepsis remain poorly understood. Bacterial peptidoglycan-associated lipoprotein (PAL), an outer-membrane protein of Gram-negative bacteria, was recently found to be released into the bloodstream in sepsis and to cause inflammation and death in mice. The present studies assessed the effects of PAL on cardiomyocyte function and its signal transduction in cardiomyocytes. DESIGN: Randomized prospective animal study. SETTING: Research laboratory. SUBJECTS: Male C57BL/6 mice, B6;129S-Tnfrsf1aTnfrsf1b/ J knockout mice, Toll-like receptor 2 (TLR2) knockout mice, and myeloid differentiation factor 88 (MyD88) knockout mice. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Immunohistochemical staining and immunoblot analysis indicated that intravenously injected PAL bound to myocardium. Injection of PAL decreased cardiac function in vivo. Challenge with PAL altered cell shortening and Ca transients in isolated mouse cardiomyocytes but not in cardiomyocytes isolated from TLR2 and MyD88 mice. Cytokine profiling arrays demonstrated that tumor necrosis factor-α (TNFα), granulocyte colony-stimulating factor, and interferon-γ production were elevated in PAL-treated cardiomyocytes. Increased TNFα production was abolished in MyD88 cardiomyocytes but restored by adenovirally mediated expression of MyD88. PAL did not affect cell shortening and Ca cycling in cardiomyocytes obtained from mice deficient for TNFα receptor (TNFR) 1 and TNFR2 (TNFR1/2). CONCLUSION: Our data reveal that PAL uses the TLR2/MyD88 signaling cascade to induce cardiomyocyte dysfunction and inflammatory responses and that TNFα is a major mediator of PAL-induced dysfunction in cardiomyocytes. These studies suggest that circulating PAL and other TLR2 agonists may contribute to cardiac dysfunction in sepsis.

Original languageEnglish
Pages (from-to)886-892
Number of pages7
JournalCritical Care Medicine
Volume35
Issue number3
DOIs
StatePublished - Mar 2007
Externally publishedYes

Keywords

  • Peptidoglycan-associated lipoprotein
  • Toll-like receptor 2
  • Tumor necrosis factor-α

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