High CYP2E1 activity aggravates hepatofibrosis by limiting macrophage polarization towards the M2 phenotype

Cytochrome P450 2E1 (CYP2E1) is an important drug-metabolizing enzyme that has been recognized as one of the risk factors for hepatofibrosis. Macrophages play key roles in regulating hepatofibrosis progression and resolution. However, whether CYP2E1 is involved in the regulation of macrophage polarization during hepatofibrosis is still unclear. Herein, we measured CYP2E1 activity and the expression of CD163 (an M2 marker) and CD68 (a pan-macrophage marker) in hepatofibrotic tissue from HCC patients (n = 26) with comparison to normal liver tissue (n = 26). The relationship of CYP2E1 activity in vivo and the CD163/CD68 ratio (an indicator of M2 polarization), as well as the extent of hepatofibrosis, were evaluated in diethylnitrosamine (DEN)-treated Sprague-Dawley rats. Strikingly, CYP2E1 activity and expression of CD68 increased and the CD163/CD68 ratio decreased, especially in hepatofibrotic tissue with higher CYP2E1 activity. Expression of α-SMA, Ki67, and PCNA were positively correlated with CYP2E1 activity and inversely correlated with the CD163/CD68 ratio. Furthermore, CYP2E1 activity showed an inverse correlation with the CD163/CD68 ratio. Overall, high CYP2E1 activity aggravates hepatofibrosis by restraining M2 macrophage polarization, providing a novel insight for understanding the profibrotic activity of CYP2E1 and a promising avenue for hepatofibrosis therapy.