Bile acid–activated macrophages promote biliary epithelial cell proliferation through integrin αvβ6 upregulation following liver injury
Adrien Guillot, Lucia Guerri, Dechun Feng, Seung-Jin Kim, Yeni Ait Ahmed, Janos Paloczi, Yong He, Kornel Schuebel, Shen Dai, Fengming Liu, Pal Pacher, Tatiana Kisseleva, Xuebin Qin, David Goldman, Frank Tacke, Bin Gao
Adrien Guillot, Lucia Guerri, Dechun Feng, Seung-Jin Kim, Yeni Ait Ahmed, Janos Paloczi, Yong He, Kornel Schuebel, Shen Dai, Fengming Liu, Pal Pacher, Tatiana Kisseleva, Xuebin Qin, David Goldman, Frank Tacke, Bin Gao
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Research Article Hepatology

Bile acid–activated macrophages promote biliary epithelial cell proliferation through integrin αvβ6 upregulation following liver injury

Abstract

Cholangiopathies caused by biliary epithelial cell (BEC) injury represent a leading cause of liver failure. No effective pharmacologic therapies exist, and the underlying mechanisms remain obscure. We aimed to explore the mechanisms of bile duct repair after targeted BEC injury. Injection of intermedilysin into BEC-specific human CD59 (hCD59) transgenic mice induced acute and specific BEC death, representing a model to study the early signals that drive bile duct repair. Acute BEC injury induced cholestasis followed by CCR2+ monocyte recruitment and BEC proliferation. Using microdissection and next-generation RNA-Seq, we identified 5 genes, including Mapk8ip2, Cdkn1a, Itgb6, Rgs4, and Ccl2, that were most upregulated in proliferating BECs after acute injury. Immunohistochemical analyses confirmed robust upregulation of integrin αvβ6 (ITGβ6) expression in this BEC injury model, after bile duct ligation, and in patients with chronic cholangiopathies. Deletion of the Itgb6 gene attenuated BEC proliferation after acute bile duct injury. Macrophage depletion or Ccr2 deficiency impaired ITGβ6 expression and BEC proliferation. In vitro experiments revealed that bile acid–activated monocytes promoted BEC proliferation through ITGβ6. Our data suggest that BEC injury induces cholestasis, monocyte recruitment, and induction of ITGβ6, which work together to promote BEC proliferation and therefore represent potential therapeutic targets for cholangiopathies.

Authors

Adrien Guillot, Lucia Guerri, Dechun Feng, Seung-Jin Kim, Yeni Ait Ahmed, Janos Paloczi, Yong He, Kornel Schuebel, Shen Dai, Fengming Liu, Pal Pacher, Tatiana Kisseleva, Xuebin Qin, David Goldman, Frank Tacke, Bin Gao

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Figure 6

Myofibroblast activation is closely related to macrophage accumulation and BEC proliferation and increases Itgb6 expression after acute BEC injury.

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Myofibroblast activation is closely related to macrophage accumulation a...
(A) ihCD59 and ihCD59BEC-TG mice were injected with ILY, and desmin (green) and IBA1 (red) staining was performed on liver sections. White arrows show close localization of IBA1+ and desmin+ cells. Scale bar: 50 μm. BD, bile duct. (B) ihCD59Coll1GFP and ihCD59BEC-TG Coll1GFP mice were injected with ILY, and GFP (green) and IBA1 (red) staining was performed. White arrows indicate stained cell clusters. Scale bar: 50 μm. (C) α-SMA (red) and IBA1 (green) or collagen GFP (brown) immunostaining on serial liver sections. Arrows indicate cell clusters. Scale bars: 50 μm. (D) α-SMA and IBA1 staining was performed, and stained cell clusters were quantitated in the indicated models of liver injury or in liver sections from patients with chronic liver disease (n = 3–10 per group). ILY-treated ihCD59Hep-TG and ILY-treated ihCD59BEC-TG mice represent hepatocyte and BEC injury models, respectively. Data represent the mean ± SEM. AH, alcoholic hepatitis; HCV/HCC, HCV infection and hepatocellular carcinoma; HAT, hepatic artery thrombosis. (E) Collagen I–producing (GFP+) CD45– MFBs were sorted from CCl4-injected Coll1GFP mouse livers, placed in Transwells, and cocultured with SV40-transformed murine BECs. Ki67 staining was performed in BECs after 24 hours (representative images are shown). Scale bar: 40 μm. (F) Ki67 staining was quantified (n = 4–8 per group). (G) Itgb6 mRNA expression analysis was performed on BECs cultured with primary myofibroblasts (n = 4–8 per group). Data represent the mean ± SEM. *P < 0.05 and ***P < 0.005, by unpaired Student’s t test (F and G) and 1-way ANOVA (D).