CCR1 is a novel target in the treatment of NASH by regulating macrophage activation through mTORC1 signaling

The number of patients with non-alcoholic steatohepatitis (NASH) is dramatically increasing globally. Recently, specific chemokine receptors have garnered interest as therapeutic targets in NASH. In different murine models with NASH, the level of CCR1 in plasma and the expression of CCR1 in liver increased, suggesting that CCR1 may be involved in the progression of NASH. Recent studies have shown that a variety of chemokines and their receptors play a certain role in the development of NASH. However, the role of CCR1 in pathogenesis of NASH remains obscure. Therefore, this study aims to explore the effect of CCR1 on the development of NASH. The results suggest that the absence of CCR1 prevents hepatic steatosis and abnormal glucose metabolism in the progression of NASH, and these results emphasize the impacts of CCR1 on macrophage recruitment and fibrosis in mice with NASH. Thus, the findings of the current study provide a new strategy for the clinical treatment of NASH. 1. Both 8-week-old male C57BL/6 (wild-type, WT) mice and CCR1 knockout (CCR1- KO) mice were fed with normal chow (NC) and high-fat, high cholesterol and cholate diet (CL) for 12 weeks, respectively. The weight of mice was measured every week. Glucose tolerance test (GTT) and pyruvate tolerance test (PTT) were performed after overnight fasting. After 12 weeks of feeding, the mice were sacrificed and the liver tissues were harvested. The hepatic macrophages were determined by flow cytometry. 2. Plasma triglyceride (TG), total cholesterol (TC), non-esterified free fatty acid (NEFA), insulin (INS), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and hepatic TG, TC, NEFA and hydroxyproline (HYP) were examined using ELISA or spectrophotometer according to the instructions. 3. The mRNA levels of liver lipid metabolism, inflammatory response and fibrosis related genes were detected by real-time fluorescence quantitative PCR (RT-qPCR). 4. Western blotting (WB) was used to detect the expression of proteins related to lipid metabolism, inflammatory signaling pathway and fibrosis in liver. 5. Hematoxylin and eosin (H&E) staining, Sirius Red staining and immunohistochemical staining (IHC) were used to evaluate the histology of liver sections 6. Protein chip and bioinformatic analysis were used to analyze the cluster of inflammatory proteins.