These endopeptidase inhibitor activity related genes (SERPIND1, AMBP, AHSG, SERPINA3-2) were markedly upregulated by cold exposure (Figure 4C), suggesting that cold treatment induced alteration on lipid metabolism might be entangled with endopeptidase inhibitor activity, which reportedly could improve hepatic steatosis and inflammation (Jiang et al., 2020). Here, SERPIND1 is linked to fatty liver disease.