HSD17B13 and fatty liver disease: HFD-induced liver hepatic steatosis and fibrosis were also significantly aggravated by higher HSD17B13 expression inducted by the AAV8-Hsd17b13 injection, something that was visible with histopathology (Figure 5E), paralleled with the increased liver hydroxyproline (HYP) expression (Figure 5F) as well as the expression of related fibrosis proteins (Figure 5G).