Vahrenbrink Madita, Coleman C D, Kuipers S, Lurje I, Hammerich L, Kunkel D, Keye J, Dittrich S, Schjeide B M, Hiß R, Müller J, Püschel G P, Henkel J
Department of Nutritional Biochemistry, Institute of Nutritional Science, University of Potsdam, Nuthetal, Germany.
Max Rubner Center (MRC) for Cardiovascular Metabolic Renal Research, Institute of Pharmacology, Charité-Universitätsmedizin Berlin, Hessische Straße 3-4, 10115, Berlin, Germany.
Cell Commun Signal. 2025 May 16;23(1):227. doi: 10.1186/s12964-025-02222-y.
The transition from metabolic dysfunction-associated steatotic liver disease (MASLD) to steatohepatitis (MASH) is characterized by a chronic low-grade inflammation, involving activation of resident macrophages (Kupffer cells; KC) and recruitment of infiltrating macrophages. Macrophages produce cytokines and, after induction of Cyclooxygenase 2 (COX-2), the key enzyme of prostanoid synthesis, prostaglandin E (PGE). PGE modulates cytokine production in an autocrine and paracrine manner, therefore playing a pivotal role in regulating inflammatory processes. Changes in the hepatic macrophage pool during MASLD progression to MASH could influence PGE- and cytokine-mediated signaling processes. The aim of this study was to characterize these changes in mice with diet-induced MASH and further elucidate the role of COX-2-dependently formed PGE on the inflammatory response in different macrophage populations of mice with a macrophage-specific COX-2-deletion.
Male, 6-7-week-old wildtype mice were fed either a Standard or high-fat, high-cholesterol MASH-inducing diet for 4, 12 and 20 weeks. Liver macrophages were isolated and analyzed by flow cytometry. For in vitro experiments primary KC, peritoneal macrophages (PM) and Bone-marrow-derived macrophages (BMDM) were isolated from macrophage-specific COX-2-deficient and wildtype mice and treated with lipopolysaccharide (LPS) and/or PGE.
During MASH-development, the proportion of KC (Clec4FTim4) decreased, while the proportion of monocyte-derived macrophages (Clec4FTim4) and monocyte-derived cells exhibiting a phenotype similar to KC (Clec4FTim4) significantly increased over time. In vitro experiments showed that exogenous PGE completely abrogated the LPS-induced mRNA expression and secretion of tumor necrosis factor-alpha (TNF-α) in primary KC, PM and BMDM from wildtype mice. PM and BMDM, as in vitro models for infiltrating macrophages, were more sensitive to PGE compared to KC. Deletion of COX-2 in all macrophage populations led to an impaired PGE-dependent feedback inhibition of TNF-α production. LPSinduced TNF-α mRNA expression was higher compared to the respective wildtype macrophage population.
The current study, using a murine MASH model, indicates that PGE may have a protective, anti-inflammatory effect, especially by inhibiting the expression of pro-inflammatory cytokines such as TNFα in infiltrating monocyte-derived macrophages. An inhibition of endogenous PGE synthesis in macrophages by pharmacological inhibition of COX-2 could potentially increase inflammation and promote the progression of MASH.
从代谢功能障碍相关脂肪性肝病（MASLD）转变为脂肪性肝炎（MASH）的特征是慢性低度炎症，涉及驻留巨噬细胞（库普弗细胞；KC）的激活和浸润巨噬细胞的募集。巨噬细胞产生细胞因子，在诱导环氧化酶2（COX-2）后，前列腺素合成的关键酶，产生前列腺素E（PGE）。PGE以自分泌和旁分泌方式调节细胞因子的产生，因此在调节炎症过程中起关键作用。MASLD进展为MASH过程中肝巨噬细胞池的变化可能影响PGE和细胞因子介导的信号传导过程。本研究的目的是在饮食诱导的MASH小鼠中表征这些变化，并进一步阐明COX-2依赖性形成的PGE对巨噬细胞特异性COX-2缺失小鼠不同巨噬细胞群体炎症反应的作用。
将6-7周龄的雄性野生型小鼠分别喂食标准饮食或高脂肪、高胆固醇的MASH诱导饮食4、12和20周。分离肝巨噬细胞并通过流式细胞术进行分析。对于体外实验，从巨噬细胞特异性COX-2缺陷型和野生型小鼠中分离原代KC、腹腔巨噬细胞（PM）和骨髓来源的巨噬细胞（BMDM），并用脂多糖（LPS）和/或PGE处理。
在MASH发展过程中，KC（Clec4FTim4）的比例下降，而单核细胞衍生巨噬细胞（Clec4FTim4）和表现出与KC相似表型的单核细胞衍生细胞（Clec4FTim4）的比例随时间显著增加。体外实验表明，外源性PGE完全消除了野生型小鼠原代KC、PM和BMDM中LPS诱导的肿瘤坏死因子-α（TNF-α）的mRNA表达和分泌。与KC相比，作为浸润巨噬细胞体外模型的PM和BMDM对PGE更敏感。所有巨噬细胞群体中COX-2的缺失导致TNF-α产生的PGE依赖性反馈抑制受损。与各自的野生型巨噬细胞群体相比，LPS诱导的TNF-α mRNA表达更高。
本研究使用小鼠MASH模型表明，PGE可能具有保护、抗炎作用，特别是通过抑制浸润的单核细胞衍生巨噬细胞中促炎细胞因子如TNFα的表达。通过药理学抑制COX-2来抑制巨噬细胞内源性PGE合成可能会增加炎症并促进MASH的进展。
