Mesothelin/mucin 16 signaling in activated portal fibroblasts regulates cholestatic liver fibrosis
Yukinori Koyama, … , David A. Brenner, Tatiana Kisseleva
Yukinori Koyama, … , David A. Brenner, Tatiana Kisseleva
Published March 13, 2017
Citation Information: J Clin Invest. 2017;127(4):1254-1270. https://doi.org/10.1172/JCI88845.
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Research Article Gastroenterology

Mesothelin/mucin 16 signaling in activated portal fibroblasts regulates cholestatic liver fibrosis

Abstract

Cholestatic liver fibrosis is caused by obstruction of the biliary tract and is associated with early activation of portal fibroblasts (PFs) that express Thy-1, fibulin 2, and the recently identified marker mesothelin (MSLN). Here, we have demonstrated that activated PFs (aPFs) and myofibroblasts play a critical role in the pathogenesis of liver fibrosis induced by bile duct ligation (BDL). Conditional ablation of MSLN+ aPFs in BDL-injured mice attenuated liver fibrosis by approximately 50%. Similar results were observed in MSLN-deficient mice (Msln–/– mice) or mice deficient in the MSLN ligand mucin 16 (Muc16–/– mice). In vitro analysis revealed that MSLN regulates TGF-β1–inducible activation of WT PFs by disrupting the formation of an inhibitory Thy-1–TGFβRI complex. MSLN also facilitated the FGF-mediated proliferation of WT aPFs. Therapeutic administration of anti-MSLN–blocking Abs attenuated BDL-induced fibrosis in WT mice. Liver specimens from patients with cholestatic liver fibrosis had increased numbers of MSLN+ aPFs/myofibroblasts, suggesting that MSLN may be a potential target for antifibrotic therapy.

Authors

Yukinori Koyama, Ping Wang, Shuang Liang, Keiko Iwaisako, Xiao Liu, Jun Xu, Mingjun Zhang, Mengxi Sun, Min Cong, Daniel Karin, Kojiro Taura, Chris Benner, Sven Heinz, Tapan Bera, David A. Brenner, Tatiana Kisseleva

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Figure 6

Msln–/– aPFs exhibit defective TGF-β1 signaling.

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Msln–/– aPFs exhibit defective TGF-β1 signaling. (A) Responses to TGF-β...
(A) Responses to TGF-β1 were compared in immortalized WT and Msln–/– aPFs using qPCR. P values were determined by ANOVA, **P < 0.01 and *P < 0.05. (B) TGF-β1–induced phosphorylation of SMAD2/3 was compared in WT and Msln–/– aPFs using Western blotting (representative blots are shown). (C–E) IPs of cell lysates from WT or Msln–/– aPFs, with or without TGF-β1, and of lysates of RFL-6-CD90.2 (lung fibroblast cell line) and LMP (pancreatic cancer cell line), which were used as controls for the expression of Thy-1 and MSLN, respectively, with (C) anti-TGFβRI Ab, (D) anti-MSLN Ab, and (E) anti-MUC16 Ab. Immunoblots are representative of more than 3 independent IPs (see also Supplemental Figure 6). (F) Proposed model of MSLN regulation of TGF-β1 signaling. In WT aPFs, Thy-1, and MUC16 interact with TGFβRI under steady-state conditions, and MUC16 and Thy-1 bind to MSLN (but not to each other). In TGF-β1–stimulated WT aPFs, both Thy-1 and MUC16 dissociate from the TGFβRI complex, and MSLN–Thy-1 interaction is increased, while MSLN-MUC16 interaction is decreased, suggesting that binding of MSLN to Thy-1 enables TGF-β1 signaling. Deletion of Msln results in overexpression of Thy-1, MUC16, and SMAD7 in Msln–/– aPFs, increased formation of the inhibitory Thy-1–TGFβRI complex, and retention of SMAD7 at the C-terminus of MUC16 TGFβRI receptors.