炎症因子介导的胶原蛋白自噬在胎膜早破中的作用研究

Premature rupture of the fetal membranes (PROM) is one of the major causes of preterm labor, nearly 30% of of these pregnancies present with evidence of chorioamnionitis, but the mechanism of inflammation leading to PROM is unclear. Our previous studies have found that the autophagic lysosome mechanism of amniotic tissue is an important pathway for the degradation of collagen type I which are major resouce of amnion tissue, and the lysosome in amniotic membrane is activated significantly at parturition. So we are really curious whether the pro-inflammatory cytokines produced by chorioamnionitis are involved in the degradation of collagen type I through autophagic lysosome pathway. Therefore, in this study, we will study whether the autophagic lysosome in amniotic membrane of chorioamnionitis is activated and whether pro-inflammatory cytokines participate in the degradation of type I collagen through autophagic lysosome pathway, and finally explore the molecular mechanism of pro-inflammatory cytokines activating autophagic lysosome. Through the above studies, we wil figure out whether pro-inflammatory cytokines participate in the PROM caused by chorioamnionitis through promoting autophagic degradation of collagen type I.

胎膜早破是早产的主要原因，近30%的胎膜早破病例存在绒毛膜羊膜炎，但炎症导致胎膜早破的机制尚不清楚。胶原蛋白与胎膜韧性密切相关，胎膜韧性的主要来源羊膜组织中I型胶原蛋白含量最多。我们研究发现，羊膜成纤维细胞的自噬溶酶体机制是I型胶原蛋白细胞内降解的重要途径，且分娩启动时羊膜中自噬溶酶体明显激活。但绒毛膜羊膜炎产生的促炎性细胞因子是否通过自噬溶酶体途径参与I型胶原蛋白的降解目前还不清楚。因此，本研究我们将研究绒毛膜羊膜炎的羊膜组织中自噬溶酶体途径是否激活增加；明确促炎性细胞因子是否通过自噬溶酶体途径参与羊膜成纤维细胞I型胶原蛋白的降解，并在此基础上探讨促炎性细胞因子激活自噬溶酶体途径的分子机制。通过上述研究明确促炎性细胞因子是否通过促进I性胶原蛋白的自噬降解参与绒毛膜羊膜炎导致的胎膜破裂。

分娩启动与母体炎症反应密切相关，无论是否存在宫内感染，IL-1β都是导致分娩发生的关键的促炎细胞因子。众所周知，IL-1β可以通过细胞外蛋白降解机制重塑羊膜结构，从而导致分娩时胎膜破裂。自噬也是降解蛋白的重要途径。然而，目前尚不清楚IL-1β是否通过自噬途径降解胶原蛋白，从而参与分娩时的胎膜破裂。在该课题中我们对此问题进行了探究。结果表明，在自然分娩的人羊膜中，IL-1β水平显著升高，伴随着COL1A1和COL1A2蛋白的含量的明显降低，而不是它们的mRNA水平则没有明显变化。培养的人原代羊膜成纤维细胞，IL-1β可以降低COL1A1和COL1A2蛋白水平，同样不降低其mRNA水平，同时可以促进羊膜细胞内自噬Marker LC3BII/I比率和自噬相关蛋白7（ATG7）。IL-1β诱导的COL1A1和COL1A2蛋白丰度的降低可被溶酶体抑制剂氯喹，ATG7-siRNA及内质网自噬受体FAM134C的siRNA所阻断，这表明FAM134C介导的内质网自噬参与了IL-1β在羊膜成纤维细胞中诱导的COL1A 1和COL1A 2蛋白的降低。在自然分娩的羊膜中，LC3B II/I、ATG7和FAM134C的水平也显著升高。总之，人羊膜中IL-1β丰度的增加可能会刺激羊膜成纤维细胞中内质网自噬介导的COL1A1和COL1A2蛋白降解，从而参与分娩时的膜破裂。