Control WT (n = 12, black) and Nrg4-KO (n = 12, gray) male mice were fed NASH diet for 20 weeks, starting at 3 months of age. (A) Plasma ALT, AST, and HMGB1 levels and liver TAG content. Data represent mean ± SEM. *P < 0.05; **P < 0.01, 2-tailed unpaired Student’s t test. (B) H&E, sirius red, F4/80 immunofluorescence, and TUNEL staining of liver sections. Scale bars: 100 μm. (C) Quantification of sirius red, F4/80, and TUNEL staining images and liver hydroxyproline content. Data represent mean ± SEM. **P < 0.01; ***P < 0.001, 2-tailed unpaired Student’s t test. (D) Immunoblots of total liver lysates from NASH diet–fed mice. (E) Heatmap representation of hepatic genes up- or downregulated by Nrg4 deficiency following NASH diet feeding (top). Enrichment of biological processes in these 2 clusters (bottom). (F) qPCR analysis of hepatic gene expression. Data represent mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001, 2-tailed unpaired Student’s t test. (G) Flow cytometry analysis of liver CD4+ T cells. Results are expressed as percentage (%) of IL-17+, TNF-α+, RORγt+, and FOXP3+ cells in total liver CD4+ T cells. Data represent mean ± SEM. *P < 0.05; **P < 0.01, 2-tailed unpaired Student’s t test.