Mounting evidence indicates that an increase in histone deacetylation contributes to renal fibrosis. Although inhibition of histone deacetylase (HDAC) can reduce the extent of fibrosis, whether HDAC inhibitors exert the antifibrotic effect through modulating the phenotypes of macrophages, the key regulator of renal fibrosis, remains unknown. Moreover, the functional roles of the M2 macrophage subpopulation in fibrotic kidney diseases remain incompletely understood. Herein, we investigated the role of HDAC inhibitors on renal fibrogenesis and macrophage plasticity. We found that HDAC inhibition by trichostatin A (TSA) reduced the accumulation of interstitial macrophages, suppressed the activation of myofibroblasts and attenuated the extent of fibrosis in obstructive nephropathy. Moreover, TSA inhibited M1 macrophages and augmented M2 macrophage infiltration in fibrotic kidney tissue. Interestingly, TSA preferentially upregulated M2c macrophages and suppressed M2a macrophages in the obstructed kidneys, which was correlated with a reduction of interstitial fibrosis. TSA also repressed the expression of proinflammatory and profibrotic molecules in cultured M2a macrophages and inhibited the activation of renal myofibroblasts. In conclusion, our study was the first to show that HDAC inhibition by TSA alleviates renal fibrosis in obstructed kidneys through facilitating an M1 to M2c macrophage transition.
Keywords: macrophage subpopulation; renal fibrosis; trichostatin A.