Bone marrow-derived macrophage contributes to fibrosing steatohepatitis through activating hepatic stellate cells
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AbstractThe role of macrophages in fibrosing steatohepatitis is largely unclear. We characterized the origin and molecular mechanisms of macrophages and its targeted therapy of fibrosing steatohepatitis. Fibrosing steatohepatitis was established in Alms1 mutant (foz/foz) and C57BL/6J wildtype mice fed high-fat/high-cholesterol or methionine- and choline-deficient diet. Bone marrow transplantation was performed to track the macrophage origin in fibrosing steatohepatitis. Macrophages were depleted using liposomal clodronate. Primary macrophages were isolated from bone marrow for adoptive transfer into mice. We found that macrophage infiltration is induced in two mouse models of fibrosing steatohepatitis and human nonalcoholic steatohepatitis-fibrosis patients. Bone marrow-derived macrophages (BMMs) contribute to the hepatic macrophage accumulation in experimental fibrosing steatohepatitis. Depletion of hepatic BMMs by liposomal clodronate during liver injury attenuated fibrosing steatohepatitis, whilst BMMs depletion after liver injury delayed the regression of fibrosing steatohepatitis. The pro-fibrotic effect of macrophages was associated with reduced activation of hepatic stellate cells (HSCs), collagen deposition and hepatic expression of key pro-fibrotic factors (TIMP1, TIMP2, and TGFβ1) and endoplasmic reticulum stress markers (GRP78, IRE1α, and PDI). Conversely, adoptive transfer of BMMs significantly aggravated fibrosing steatohepatitis. Moreover, macrophage-conditioned medium directly promoted the phenotypic transition of primary quiescent HSCs to activated HSCs; it enhanced activation and proliferation but decreased apoptosis of HSC cell lines (LX-2 and HSC-T6). The effect of BMMs in promoting fibrosing steatohepatitis was mediated by inducing key pro-fibrosis factors and signaling pathways including cytokine/chemokine, TGFβ and complement cascade as assessed by cDNA expression array. Complement 3a receptor (C3ar1) was a predominant effector of macrophage mediated fibrosing steatohepatitis. Knockout of C3ar1 in mice blunted development of fibrosing steatohepatitis. In conclusion, BMMs promoted the progression of fibrosing steatohepatitis during injury, whereas macrophages reduced fibrosing steatohepatitis in the recovery phase of liver injury. Increasing anti-fibrotic macrophages and decreasing pro-fibrotic macrophages are promising approaches for fibrosing steatohepatitis.
Acceptance Date28/03/2019
All Author(s) ListHan J, Zhang X, Lau JK, Fu K, Lau HCH, Xu W, Chu ES, Lan H, Yu J
Journal nameJournal of Pathology
Year2019
ISSN0022-3417
eISSN1096-9896
LanguagesEnglish-United Kingdom
Keywordsbone marrow-derived monocytes, nutritional fibrosis, hepatic stellate cells, C3ar1, target therapy

Last updated on 2020-03-07 at 03:19