■Aramchol是一种脂肪酸-胆汁酸缀合物,可降低肝脏脂肪含量,并且正在非酒精性脂肪性肝炎(NASH)的III期临床试验中进行评估。Aramchol在小鼠模型中减弱NASH并通过下调肝细胞中的脂肪酸合成酶硬脂酰辅酶A去饱和酶1(SCD1)来减少脂肪变性。尽管肝星状细胞(HSC)也将脂质储存为视黄酯,Aramchol在这种细胞类型中的影响是未知的。
■我们研究了Aramchol对人HSC系(LX-2)的影响,原代人类HSC(phHSC),和原代人肝细胞(phHeps)。
■在LX-2和phHSC中,10μMAramchol显着降低SCD1mRNA,同时诱导PPARG(PPARγ)mRNA,2种蛋白质的平行变化;LX-2中ACTA2,COL1A1,β-PDGFR(bPDGFR)mRNA也显着减少。10μMAramchol抑制了胶原蛋白1(Col1α1)的分泌。LX-2细胞中SCD1敲低通过减少纤维发生来证实Aramchol的作用,向这些细胞中添加Aramchol并不能挽救纤维化基因的表达。相反,在过表达LX-2的SCD1中,Aramchol不再抑制纤维化基因表达。该药物还诱导LX-2中的基因,这些基因促进胆固醇流出并抑制催化胆固醇合成的ACAT2。在PhHeps,Aramchol还降低SCD1并增加PPARGmRNA表达。
■Aramchol下调HSC的SCD1并升高PPARG,减少COL1A1和ACTA2mRNA和COL1A1分泌。这些数据表明Aramchol通过SCD1抑制对HSC的直接抑制作用,作为对纤维基因和胆固醇稳态介质的更广泛影响的一部分。这些发现说明了Aramchol活性的新机制,包括NASH和纤维化患者的潜在抗纤维化活性。
■在这项研究中,我们探索了Aramchol的潜在活性,目前正在进行脂肪肝临床试验的药物,在阻断纤维化方面,或疤痕,通过肝星状细胞,肝损伤中主要的胶原蛋白产生(即纤维化)细胞类型。在分离的人肝星状细胞和人肝星状细胞系中,这种药物抑制了关键的脂肪生成酶,硬脂酰辅酶A去饱和酶1(SCD1),导致与肝纤维化相关的基因和蛋白质表达减少,在诱导保护性基因的同时,PPARγ。当SCD1已经被基因敲除减少时,药物失去活性,强化了抑制SCD1是Aramchol主要活性模式的观点。这些发现加强了在NASH患者中测试Aramchol的理由。
UNASSIGNED: Aramchol is a fatty acid-bile acid conjugate that reduces liver fat content and is being evaluated in a phase III clinical trial for non-alcoholic steatohepatitis (NASH). Aramchol attenuates NASH in mouse models and decreases steatosis by downregulating the fatty acid synthetic enzyme stearoyl CoA desaturase 1 (SCD1) in hepatocytes. Although hepatic stellate cells (HSCs) also store lipids as retinyl esters, the impact of Aramchol in this cell type is unknown.
UNASSIGNED: We investigated the effects of Aramchol on a human HSC line (LX-2), primary human HSCs (phHSCs), and primary human hepatocytes (phHeps).
UNASSIGNED: In LX-2 and phHSCs, 10 μM Aramchol significantly reduced SCD1 mRNA while inducing PPARG (PPARγ) mRNA, with parallel changes in the 2 proteins; ACTA2, COL1A1, β-PDGFR (bPDGFR) mRNAs were also significantly reduced in LX-2. Secretion of collagen 1 (Col1α1) was inhibited by 10 μM Aramchol. SCD1 knockdown in LX-2 cells phenocopied the effect of Aramchol by reducing fibrogenesis, and addition of Aramchol to these cells did not rescue fibrogenic gene expression. Conversely, in LX-2 overexpressing SCD1, Aramchol no longer suppressed fibrogenic gene expression. The drug also induced genes in LX-2 that promote cholesterol efflux and inhibited ACAT2, which catalyses cholesterol synthesis. In phHeps, Aramchol also reduced SCD1 and increased PPARG mRNA expression.
UNASSIGNED: Aramchol downregulates SCD1 and elevates PPARG in HSCs, reducing COL1A1 and ACTA2 mRNAs and COL1A1 secretion. These data suggest a direct inhibitory effect of Aramchol in HSCs through SCD1 inhibition, as part of a broader impact on both fibrogenic genes as well as mediators of cholesterol homeostasis. These findings illustrate novel mechanisms of Aramchol activity, including potential antifibrotic activity in patients with NASH and fibrosis.
UNASSIGNED: In this study, we have explored the potential activity of Aramchol, a drug currently in clinical trials for fatty liver disease, in blocking fibrosis, or scarring, by hepatic stellate cells, the principal collagen-producing (i.e. fibrogenic) cell type in liver injury. In both isolated human hepatic stellate cells and in a human hepatic stellate cell line, the drug suppresses the key fat-producing enzyme, stearoyl CoA desaturase 1 (SCD1), which leads to reduced expression of genes and proteins associated with hepatic fibrosis, while inducing the protective gene, PPARγ. The drug loses activity when SCD1 is already reduced by gene knockdown, reinforcing the idea that inhibition of SCD1 is a main mode of activity for Aramchol. These findings strengthen the rationale for testing Aramchol in patients with NASH.