Department of Physiology and the Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, PR China.
Cardiovasc Res. 2013 Jun 1;98(3):391-401. doi: 10.1093/cvr/cvt047. Epub 2013 Feb 27.
The molecular events leading from cardiomyocyte ischaemia to inflammatory cytokine production are not well understood. We previously found that heat shock protein 60 (HSP60) appeared in extracellular space after cardiomyocyte ischaemia. This study examined the activation and regulation of toll-like receptors (TLRs) by HSP60 in cardiomyocytes.
Cytokine production and TLRs regulation mediated by TLRs signalling were examined in response to exogenous HSP60 (exHSP60) and endogenous HSP60 (enHSP60) released extracellularly under ischaemia. The results showed that exHSP60 induced inflammatory cytokine production in adult rat cardiomyocytes and H9c2 cells (a standard cardiac cell line derived from embryonic cells), through a pathway dependent on TLR4, myeloid differentiation factor 88 (MyD88), p38, and nuclear factor-κB (NF-κB). Further study revealed up-regulated expression of both TLR2 and TLR4 by exHSP60, which was dependent on the activation of TLR4, MyD88, c-Jun NH2-terminal kinase (JNK), and NF-κB, but not on p38. In myocytes exposed to ischaemia, enHSP60 was released into the media, and triggered cytokine production and TLR2/4 overexpression, through the same pathways as exHSP60. In rats subjected to LAD ligation, the released enHSP60 contributed to cytokine production and TLR2/4 overexpression in the ischaemic myocardium.
Extracellular HSP60 induces cytokine production via TLR4-MyD88-p38/NF-κB pathway, and up-regulates TLR2/4 expression via TLR4-MyD88-JNK/NF-κB pathway. Both pathways contribute to myocardial inflammation induced by ischaemia.
导致心肌细胞缺血到炎症细胞因子产生的分子事件尚不清楚。我们之前发现，热休克蛋白 60（HSP60）在心肌细胞缺血后出现在细胞外空间。本研究检测了 HSP60 在心肌细胞中对 toll 样受体（TLR）的激活和调节。
检测了外源性 HSP60（exHSP60）和缺血时细胞外释放的内源性 HSP60（enHSP60）通过 TLR 信号转导介导的细胞因子产生和 TLR 调节。结果表明，exHSP60 通过依赖 TLR4、髓样分化因子 88（MyD88）、p38 和核因子-κB（NF-κB）的途径，诱导成年大鼠心肌细胞和 H9c2 细胞（一种源自胚胎细胞的标准心脏细胞系）产生炎症细胞因子。进一步的研究表明，exHSP60 上调了 TLR2 和 TLR4 的表达，这依赖于 TLR4、MyD88、c-Jun NH2-末端激酶（JNK）和 NF-κB 的激活，但不依赖于 p38。在暴露于缺血的肌细胞中，enHSP60 释放到培养基中，并通过与 exHSP60 相同的途径触发细胞因子产生和 TLR2/4 过表达。在接受 LAD 结扎的大鼠中，释放的 enHSP60 导致缺血心肌中细胞因子的产生和 TLR2/4 过表达。
细胞外 HSP60 通过 TLR4-MyD88-p38/NF-κB 途径诱导细胞因子产生，并通过 TLR4-MyD88-JNK/NF-κB 途径上调 TLR2/4 表达。这两种途径都有助于缺血引起的心肌炎症。
