Targeting SPHK1 by 8-HETrE Attenuates MASH-Driven Fibrosis via Restoration of Hepatic Stellate Cell Mitochondrial Dynamics

Metabolic dysfunction-associated steatohepatitis (MASH) drives hepatic stellate cell (HSC) activation and extracellular matrix deposition, leading to liver fibrosis, for which effective treatments remain lacking. Here, we report that 8-hydroxyoctacosatrienoic acid (8-HETrE), an arachidonic acid metabolite generated through cytochrome P450 or lipoxygenase pathways, significantly ameliorates MASH-related fibrosis by targeting sphingosine kinase 1 (SPHK1) and restoring mitochondrial function. Clinical observations revealed markedly reduced circulating 8-HETrE levels in patients with MASH fibrosis. In vivo studies demonstrated that 8-HETrE administration improved liver function, enhanced expression of mitochondrial fusion proteins (MFN1, MFN2, OPA1), and attenuated fibrosis in Gubra-Amylin-NASH (GAN)-diet-induced MASH models. In TGF-β1-activated human HSCs cell line (LX-2 cells), 8-HETrE treatment suppressed fibrotic markers (α-SMA, COL1A1) and improved mitochondrial dynamics. Mechanistic investigations revealed that 8-HETrE exerted its anti-fibrotic effects primarily through SPHK1 inhibition: SPHK1 knockdown moderately reduced HSC activation, decreased sphingosine-1-phosphate (S1P), lactate, and nitrite levels, enhanced glucose uptake, and promoted mitochondrial fusion, while completely abolishing 8-HETrE's therapeutic effects. Conversely, SPHK1 overexpression exacerbated fibrotic and metabolic abnormalities, which were effectively reversed by 8-HETrE treatment. Critically, HSC-specific Sphk1 knockout independently improved MASH fibrosis, mitochondrial function, and metabolic parameters, while completely blocking 8-HETrE's benefits. Our findings identify 8-HETrE as a novel mediator that targets the SPHK1-mitochondrial dynamics axis in HSCs, providing both mechanistic insights and therapeutic potential for MASH-related fibrosis treatment.代谢功能障碍相关脂肪性肝炎（Metabolic dysfunction-associated steatohepatitis, MASH）可驱动肝星状细胞（hepatic stellate cell, HSC）活化与细胞外基质沉积，进而引发肝纤维化，目前该类病症仍缺乏有效治疗手段。本研究报道，8-羟基二十八碳三烯酸（8-hydroxyoctacosatrienoic acid, 8-HETrE）——一种经由细胞色素P450或脂氧合酶途径生成的花生四烯酸代谢物——可通过靶向鞘氨醇激酶1（sphingosine kinase 1, SPHK1）并恢复线粒体功能，显著改善MASH相关纤维化。临床观测显示，合并纤维化的MASH患者循环中8-HETrE水平显著降低。体内实验表明，给予8-HETrE可改善Gubra-Amylin-NASH（GAN）饮食诱导的MASH模型小鼠的肝功能，上调线粒体融合蛋白（MFN1、MFN2、OPA1）的表达，并减轻肝纤维化程度。在经转化生长因子-β1（TGF-β1）活化的人肝星状细胞系LX-2中，8-HETrE处理可抑制纤维化标志物（α-SMA、COL1A1）的表达，并改善线粒体动态平衡。机制研究揭示，8-HETrE的抗纤维化作用主要通过抑制SPHK1实现：敲低SPHK1可适度抑制HSC活化，降低鞘氨醇-1-磷酸（sphingosine-1-phosphate, S1P）、乳酸及亚硝酸盐水平，增强葡萄糖摄取并促进线粒体融合，同时可完全抵消8-HETrE的治疗效果。与之相反，过表达SPHK1会加剧纤维化与代谢异常，而8-HETrE处理可有效逆转此类表型。尤为关键的是，HSC特异性敲除Sphk1可独立改善MASH相关纤维化、线粒体功能及代谢参数，同时完全阻断8-HETrE的治疗获益。本研究明确8-HETrE是一种新型介质，可靶向肝星状细胞内的SPHK1-线粒体动态轴，为MASH相关纤维化的治疗提供了机制见解与治疗潜力。