Heterogeneity of hepatic stellate cells in a mouse model of non‐alcoholic steatohepatitis (NASH)
In clinical and experimental non-alcoholic steatohepatitis (NASH), the origin of the scar-forming myofibroblast is the hepatic stellate cell (HSC). We used foz/foz mice on a Western diet to characterize in detail the phenotypic changes of HSCs in a NASH model. We examined the single cell expression profiles (scRNA-Seq) of HSCs purified from the normal livers of foz/foz mice on a chow diet, in NASH with fibrosis of foz/foz mice on a Western diet, and in livers during regression of NASH after switching back to a chow diet. Selected genes were analyzed using immunohistochemistry, qRT-PCR, and shRNA-knockdown in primary mouse HSCs. Our analysis of the normal liver identified two distinct clusters of quiescent HSCs that correspond to their acinar position of either pericentral vein or periportal vein. The NASH livers had four distinct HSC clusters, including one representing the classic fibrogenic myofibroblast. The three other HSC clusters consisted of a proliferating cluster, an intermediate activated cluster, and an immune and inflammatory cluster. The livers with NASH regression had one cluster of inactivated HSCs, which was similar to, but distinct from, the quiescent HSCs. Conclusion: Analysis of scRNA-Seq in combination with an interrogation of previous studies has revealed an unanticipated heterogeneity of HSC phenotypes under normal and injured states.