MMP2 and fibrosis: Significantly elevated protein levels of α-SMA (Fig. 2A, B), a gold standard fibrosis marker, and mRNA levels of fibrotic genes, such as Acta2, Col1α1, Col1α2, Col2α, Mmp2, and Mmp9, as well as proinflammatory genes, i.e. TNFα, IL-8, IL-10 and IL-1β, further illustrated the occurrence of liver fibrosis in fish fed HCHFD diet (Supplementary Fig. S1A, B) or challenged with CCL4 (Supplementary Fig. S1C, D).