Selective depletion of hepatic stellate cells-specific LOXL1 alleviates liver fibrosis
Selective depletion of hepatic stellate cells-specific LOXL1 alleviates liver fibrosis
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DOI：
10.1096/fj.202100374r
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发表时间：
2021-10-01
期刊：
影响因子：
4.8
通讯作者：
You, Hong
中科院分区：
文献类型：
--
作者：
Yang, Aiting;Yan, Xuzhen;You, Hong
LOXL1 通过介导 ECM 交联和稳定在纤维化中的作用已得到充分证实；然而，肝星状细胞 (HSC) 特异性 LOXL1 在纤维化发展中的作用仍不清楚。我们生成了 HSC 特异性 Loxl1 缺失小鼠（Loxl1（Gfap-cre）小鼠），以研究 LOXL1 在纤维化发病机制中的 HSC 特异性贡献。 Loxl1(fl/fl)小鼠用作对照。此外，我们使用 RNA 测序来探索转录组的潜在变化。天狼星红染色、I 型胶原免疫标记和羟脯氨酸含量分析的结果，加上促纤维化基因表达的减少，表明 CCl4 诱导的纤维化 Loxl1(Gfap-cre) 小鼠表现出肝纤维化减少。此外，与对照组相比，Loxl1(Gfap-cre)小鼠表现出CD68阳性细胞巨噬细胞浸润减少，炎症基因表达减少。 RNA 测序鉴定出整合素 α 8 (ITGA8) 是 LOXL1 介导的肝纤维化的关键调节剂。功能分析表明，培养的成纤维细胞中 Itga8 的 siRNA 沉默导致 LOXL1 表达下降并抑制成纤维细胞活化。机制分析表明，LOXL1 激活 FAK/PI3K/AKT/HIF1a 信号通路，添加 FAK 或 PI3K 抑制剂可通过下调 LOXL1 逆转这些结果。此外，HIF1a直接与LOXL1相互作用并上调其表达，表明LOXL1可以通过与FAK/PI3K/AKT/HIF1a通路形成正反馈环进行正向自我调节。我们证明 HSC 特异性 Loxl1 缺陷可以预防纤维化和炎症，并且 ITGA8/FAK/PI3K/AKT/HIF1a 对于 LOXL1 的功能和表达至关重要。了解这种方法可以为未来治疗纤维化提供新的机制和目标。
The role of LOXL1 in fibrosis via mediating ECM crosslinking and stabilization is well established; however, the role of hepatic stellate cells (HSCs)-specific LOXL1 in the development of fibrosis remains unknown. We generated HSCs-specific Loxl1-depleted mice (Loxl1(Gfap-cre) mice) to investigate the HSCs-specific contribution of LOXL1 in the pathogenesis of fibrosis. Loxl1(fl/fl) mice were used as the control. Furthermore, we used RNA sequencing to explore the underlying changes in the transcriptome. Results of the sirius red staining, type I collagen immunolabeling, and hydroxyproline content analysis, coupled with the reduced expression of profibrogenic genes revealed that Loxl1(Gfap-cre) mice with CCl4-induced fibrosis exhibited decreased hepatic fibrosis. In addition, Loxl1(Gfap-cre) mice exhibited reduced macrophage tissue infiltration by CD68-positive cells and decreased expression of inflammatory genes compared with the controls. RNA sequencing identified integrin alpha 8 (ITGA8) as a key modulator of LOXL1-mediated liver fibrosis. Functional analyses showed that siRNA silencing of Itga8 in cultured fibroblasts led to a decline in the LOXL1 expression and inhibition of fibroblast activation. Mechanistic analyses indicated that LOXL1 activated the FAK/PI3K/AKT/HIF1a signaling pathway, and the addition of inhibitors of FAK or PI3K reversed these results via downregulation of LOXL1. Furthermore, HIF1a directly interacted with LOXL1 and upregulated its expression, indicating that LOXL1 can positively self-regulate by forming a positive feedback loop with the FAK/PI3K/AKT/HIF1a pathway. We demonstrated that HSCs-specific Loxl1 deficiency prevented fibrosis, inflammation and that ITGA8/FAK/PI3K/AKT/HIF1a was essential for the function and expression of LOXL1. Knowledge of this approach can provide novel mechanisms and targets to treat fibrosis in the future.