Nonalcoholic steatohepatitis (NASH) may soon become the leading cause of end-stage liver disease worldwide with limited treatment options. Liver fibrosis, which is driven by chronic inflammation and hepatic stellate cell (HSC) activation, critically determines morbidity and mortality in patients with NASH. Pyruvate kinase M2 (PKM2) is involved in immune activation and inflammatory liver diseases; however, its role and therapeutic potential in NASH-related fibrosis remain largely unexplored. Bioinformatics screening and analysis of human and murine NASH livers indicated that PKM2 was upregulated in nonparenchymal cells (NPCs), especially macrophages, in the livers of patients with fibrotic NASH. Macrophage-specific PKM2 knockout (PKM2FL/FLLysM-Cre) significantly ameliorated hepatic inflammation and fibrosis severity in three distinct NASH models induced by a methionine- and choline-deficient (MCD) diet, a high-fat high-cholesterol (HFHC) diet, and a western diet plus weekly carbon tetrachloride injection (WD/CCl4). Single-cell transcriptomic analysis indicated that deletion of PKM2 in macrophages reduced profibrotic Ly6Chigh macrophage infiltration. Mechanistically, PKM2-dependent glycolysis promoted NLR family pyrin domain containing 3 (NLRP3) activation in proinflammatory macrophages, which induced HSC activation and fibrogenesis. A pharmacological PKM2 agonist efficiently attenuated the profibrotic crosstalk between macrophages and HSCs in vitro and in vivo. Translationally, ablation of PKM2 in NPCs by cholesterol-conjugated heteroduplex oligonucleotides, a novel oligonucleotide drug that preferentially accumulates in the liver, dose-dependently reversed NASH-related fibrosis without causing observable hepatotoxicity. The present study highlights the pivotal role of macrophage PKM2 in advancing NASH fibrogenesis. Thus, therapeutic modulation of PKM2 in a macrophage-specific or liver-specific manner may serve as a novel strategy to combat NASH-related fibrosis.

中文翻译：

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PKM2 的治疗靶向以巨噬细胞特异性和肝脏特异性方式改善 NASH 纤维化进展


非酒精性脂肪性肝炎 （NASH） 可能很快成为全球终末期肝病的主要原因，治疗选择有限。肝纤维化是由慢性炎症和肝星状细胞 （HSC） 激活驱动的，关键决定了 NASH 患者的发病率和死亡率。丙酮酸激酶 M2 （PKM2） 参与免疫激活和炎症性肝病;然而，它在 NASH 相关纤维化中的作用和治疗潜力在很大程度上仍未得到探索。人和小鼠 NASH 肝脏的生物信息学筛选和分析表明，PKM2 在纤维化 NASH 患者肝脏的非实质细胞 （NPC） 中上调，尤其是巨噬细胞。巨噬细胞特异性 PKM2 敲除 （PKM2FL/FLLysM-Cre） 在蛋氨酸和胆碱缺乏 （MCD） 饮食、高脂肪高胆固醇 （HFHC） 饮食和西方饮食加每周四氯化碳注射 （WD/CCl4） 诱导的三种不同 NASH 模型中显著改善肝脏炎症和纤维化严重程度。单细胞转录组学分析表明，巨噬细胞中 PKM2 的缺失减少了促纤维化 Ly6Chigh 巨噬细胞浸润。从机制上讲，PKM2 依赖性糖酵解促进了促炎巨噬细胞中 NLR 家族包含 pyrin 结构域 3 （NLRP3） 的激活，从而诱导 HSC 激活和纤维化。药理学 PKM2 激动剂在体外和体内有效减弱了巨噬细胞和 HSC 之间的促纤维化串扰。翻译上，胆固醇偶联的异源双链寡核苷酸（一种优先在肝脏中积累的新型寡核苷酸药物）消融 NPC 中的 PKM2，剂量依赖性逆转 NASH 相关纤维化，而不会引起可观察到的肝毒性。 本研究强调了巨噬细胞 PKM2 在促进 NASH 纤维化中的关键作用。因此，以巨噬细胞特异性或肝脏特异性方式对 PKM2 进行治疗性调节可能是对抗 NASH 相关纤维化的新策略。