Habibi Mohammad, Ferguson Daniel, Eichler Sophie J, Chan Mandy M, Fu Christina, Pietka Terri A, Bredemeyer Andrea L, LaPoint Andrew, Shew Trevor M, He Mai, Liss Kim H H, Lutkewitte Andrew J, Cho Kevin, Schilling Joel D, Patti Gary J, Finck Brian N
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri.
Department of Medicine, Washington University School of Medicine, St. Louis, Missouri; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri.
Cell Mol Gastroenterol Hepatol. 2025 Apr 14;19(8):101517. doi: 10.1016/j.jcmgh.2025.101517.
BACKGROUND & AIMS: Hepatic stellate cells (HSCs) are non-parenchymal cells of the liver that produce the extracellular matrix that forms fibrotic lesions in chronic liver disease, including metabolic dysfunction-associated steatohepatitis (MASH). The mitochondrial pyruvate carrier (MPC) catalyzes the transport of pyruvate from the cytosol into the mitochondrial matrix, which is a critical step in pyruvate metabolism. An MPC inhibitor has shown promise as a novel therapeutic for MASH and HSC activation, but a mechanistic understanding of the direct effects of MPC inhibition on HSC activation is lacking.
Stable lines of LX2 cells expressing short hairpin RNA against MPC2 were established and examined in a series of studies to assess HSC metabolism and activation. Mice with conditional, HSC-specific MPC2 deletion were generated and their phenotypes assessed in the context of diets that cause hepatic steatosis, injury, and early-stage fibrosis.
Genetic suppression of MPC activity markedly decreased expression of markers of HSC activation in vitro. MPC knockdown reduced the abundance of several intermediates of the tricarboxylic acid cycle and attenuated HSC activation by suppressing hypoxia inducible factor-1α signaling. Supplementing alpha-ketoglutarate to replenish the tricarboxylic acid cycle intermediates was sufficient to overcome the effects of MPC inhibition on hypoxia inducible factor-1α and HSC activation. On high-fat diets, mice with HSC-specific MPC deletion exhibited reduced circulating transaminases, numbers of HSCs, and hepatic expression of markers of HSC activation and inflammation compared with wild-type mice.
These data suggest that MPC inhibition modulates HSC metabolism to attenuate activation and illuminate mechanisms by which MPC inhibitors could prove therapeutically beneficial for treating MASH.
肝星状细胞（HSCs）是肝脏的非实质细胞，可产生细胞外基质，在慢性肝病（包括代谢功能障碍相关脂肪性肝炎，即MASH）中形成纤维化病变。线粒体丙酮酸载体（MPC）催化丙酮酸从细胞质转运至线粒体基质，这是丙酮酸代谢的关键步骤。一种MPC抑制剂已显示出有望成为治疗MASH和肝星状细胞激活的新型疗法，但目前缺乏对MPC抑制对肝星状细胞激活的直接作用的机制理解。
建立了表达针对MPC2的短发夹RNA的LX2细胞稳定系，并在一系列研究中进行检测，以评估肝星状细胞的代谢和激活情况。构建了条件性、肝星状细胞特异性MPC2缺失的小鼠，并在导致肝脂肪变性、损伤和早期纤维化的饮食背景下评估其表型。
在体外，对MPC活性的基因抑制显著降低了肝星状细胞激活标志物的表达。MPC基因敲低减少了三羧酸循环几种中间产物的丰度，并通过抑制缺氧诱导因子-1α信号传导减弱了肝星状细胞的激活。补充α-酮戊二酸以补充三羧酸循环中间产物足以克服MPC抑制对缺氧诱导因子-1α和肝星状细胞激活的影响。在高脂饮食条件下，与野生型小鼠相比，肝星状细胞特异性MPC缺失的小鼠循环转氨酶水平降低，肝星状细胞数量减少，肝星状细胞激活和炎症标志物的肝表达降低。
这些数据表明，MPC抑制可调节肝星状细胞代谢以减弱激活，并阐明了MPC抑制剂在治疗MASH中可能具有治疗益处的机制。
