高迁移率族蛋白1调控心脏成纤维细胞自噬活性在心脏纤维化中的作用及机制

HMGB1, a kind of nuclear DNA binding protein, is an important inflammatory factor released by dead or damaged cells, which can promote cell proliferation and tissue regeneration via damage-associated molecular patterns (DAMP). Our previous experiments confirmed: Cardiac fibroblasts (CFs) can express TLR4. The activation of autophagy in myocardial tissue was inhibited and cardiac fibrosis was reduced in TLR4 knockout mice. In addition, the expression of HMGB1 was positively associated with the degree of cardiac fibrosis. Therefore, we propose hypotheses: HMGB1 released from dead cardiomyocytes(CMs) can stimulate TLRs in CFs membrane and then activates autophagic activity in CFs, determining CFs activation, proliferation and extracellular matrix collagen accumulation, leading to cardiac fibrosis. . In this study, we will first use HMGB1 on primary CFs of TLR2/TLR4 knockout mice to explored the role and signal pathway of HMGB1 in regulating autophagic activity, cell proliferation and collagen secretion via TLRs. Second, we will use the inhibitor of HMGB1 to view the effect on autophagy activity of myocytes and cardiac fibrosis in post-infarction and isoproterenol-induced mouse model. Third, we will use primary CMs to establish hypoxia/reoxygenation model to investgate the influence of dead CMs on the secretion of HMGB1.. Our study will provide a new target for prevention and treatment of cardiac fibrosis.

HMGB1是组织内部重要的炎症因子，由坏死或损伤细胞释放，通过损伤识别模式促进细胞增殖与组织再生。我们前期研究发现：敲除TLR4基因后自噬活性被抑制，心脏纤维化减轻；HMGB1在纤维化组织中高表达。我们提出假说：坏死的心肌细胞释放的HMGB1通过心脏成纤维细胞膜上Toll样受体活化心脏成纤维细胞自噬，进而促进心脏成纤维细胞的激活、增殖及细胞外间质胶原聚积，导致心脏纤维化。本项目： 1、在Toll样受体2、4基因敲除的心脏成纤维细胞上，明确HMGB1通过Toll样受体对自噬活性及细胞增殖、胶原分泌的作用及机制；2、在小鼠心梗后及异丙肾上腺素诱导的心脏纤维化模型上，观察HMGB1对心脏成纤维细胞自噬及心脏纤维化的影响；3、在原代培养心肌细胞上，观察心肌细胞坏死对HMGB1分泌的影响。此研究将为心脏纤维化的防治提供靶点。

HMGB1是组织内部重要的炎症因子，由坏死或损伤细胞释放，通过损伤识别模式促进细胞 增殖与组织再生。本项目探讨了坏死的心肌细胞释放的HMGB1通过心脏成纤维细胞膜上Toll样受体对心肌成纤维细胞自噬的做用及其机制。结果发现：（1）阐明了TLR2敲低可减轻ISO介导的的小鼠心脏功能障碍，减少心肌中炎性细胞浸润，增加心肌细胞存活，减轻心脏纤维化（胶原体积分数、胶原I和a-SMA）。（2）证明了在ISO介导的心肌损伤中，心肌成纤维细胞自噬受损，而敲低TLR2可恢复自噬。（3）阐明了TLR2介导的HMGB1导致心肌成纤维细胞自噬抑制和a-SMA增加，HMGB1 / TLR2导致的自噬抑制阻碍了心肌成纤维细胞中α-SMA的降解。（4）证明了GA通过抑制HMGB1，增加心肌成纤维细胞自噬，改善ISO诱导的心肌纤维化。本研究表明，TLR2与HMGB1相互作用，抑制心脏成纤维细胞自噬，从而加重了心脏纤维化的发病机理，而HMGB1抑制剂GA可通过抑制HMGB1恢复心肌成纤维细胞自噬，从而减轻心肌纤维化程度，为心肌纤维化治疗提供新的理论依据。