State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China; Hepatology Unit, Shenzhen Hospital, Southern Medical University, Shenzhen 518000, China.
Life Sci. 2022 Jan 15;289:120235. doi: 10.1016/j.lfs.2021.120235. Epub 2021 Dec 14.
Liver fibrosis is a growing public health concern without effective medical treatment. Recent reports have indicated that inhibitors of apoptosis proteins (IAPs) were potential targets for idiopathic pulmonary fibrosis therapy. However, their roles have not been well identified in liver fibrosis.
The expression of IAPs were examined in human liver tissue and experimental mouse models. Liver fibrosis in CCl-induced mouse models were investigated by Sirius red staining, RT-PCR, Western blotting after hepatocytes-specific cIAP2 knockout or IAPs inhibitor APG-1387 treatment. The underlying molecular mechanism of APG-1387 action was explored by apoptosis analysis, matrix metalloprotein 9 (MMP9) inhibition, neutrophils depletion, and CC Motif Chemokine Ligand 5 (CCL5) gene knockout in vitro and in vivo.
Our study showed that increased expression of cIAP2 was associated with liver fibrosis severity in liver tissues. Deletion of cIAP2 from hepatocytes or degrading cIAPs by APG-1387 ameliorated liver fibrosis induced by CCl. APG-1387 treatment exhibited increased expression of MMP9 and resulted in higher ratio of MMP9 to tissue inhibitor of metalloproteinase-1. MMP9 was mainly derived from CCL5 chemotactic neutrophils. Further, MMP9 inhibition by CTT peptide, neutrophil depletion by Ly6G antibody or CCL5 deficiency blocked the anti-fibrotic effects of APG-1387 in vivo.
These results suggested that cIAPs, especially cIAP2, might play a novel role in the pathogenesis of liver fibrosis, and targeting cIAPs represented a promising therapeutic strategy for liver fibrosis by increasing MMP9 expression induced by CCL5 chemotactic neutrophils.
肝纤维化是一种日益严重的公共健康问题，目前尚无有效的医学治疗方法。最近的报告表明，凋亡抑制蛋白（IAPs）抑制剂可能是特发性肺纤维化治疗的潜在靶点。然而，它们在肝纤维化中的作用尚未得到充分证实。
检测了 IAPs 在人肝组织和实验性小鼠模型中的表达。通过天狼星红染色、RT-PCR 和 Western blot 分析，研究了 CCl4 诱导的小鼠模型中的肝纤维化，在特异性敲除肝细胞 cIAP2 或用 IAPs 抑制剂 APG-1387 处理后观察这些变化。通过凋亡分析、基质金属蛋白酶 9（MMP9）抑制、中性粒细胞耗竭和 CC 基序趋化因子配体 5（CCL5）基因敲除，在体外和体内探讨了 APG-1387 作用的潜在分子机制。
本研究表明，cIAP2 的表达增加与肝组织中肝纤维化的严重程度相关。在肝细胞中敲除 cIAP2 或用 APG-1387 降解 IAPs 可改善 CCl4 诱导的肝纤维化。APG-1387 处理可增加 MMP9 的表达，并导致 MMP9 与组织金属蛋白酶抑制剂-1 的比例升高。MMP9 主要来源于 CCL5 趋化的中性粒细胞。进一步的，CCL5 趋化的中性粒细胞耗竭或 MMP9 抑制肽 CTT 或 CCL5 缺失可阻断 APG-1387 在体内的抗纤维化作用。
这些结果表明，IAPs，特别是 cIAP2，可能在肝纤维化的发病机制中发挥新的作用，通过增加 CCL5 趋化的中性粒细胞诱导的 MMP9 表达，靶向 IAPs 可能成为治疗肝纤维化的一种有前途的治疗策略。
