# Mechanisms of synergistic regulation of biliary inflammation and fibrosis

> **NIH VA I01** · RLR VA MEDICAL CENTER · 2022 · —

## Abstract

The risk of liver diseases due to alcohol and toxin abuse and hepatitis viruses in US Veterans is increasingly
high and is one of the most common reasons for hospitalization and mortality. Hepatic fibrotic disease represents
one of the largest groups of disorders for which there is no effective therapy and thus denotes a major unmet
medical need. Often the only option for patients with liver fibrosis is organ transplantation. Chronic liver diseases
include cholangiopathies that target cholangiocytes such as Primary Sclerosing Cholangitis (PSC) which is
characterized by biliary proliferation, inflammation and progressive fibrosis. Unrestrained cholangiocyte
proliferation can develop into cancer of the bile ducts (i.e., cholangiocarcinoma, CCA) and patients with PSC are
more susceptible to development of CCA. Further, cholangiocytes display a senescent phenotype during PSC
which may contribute to inflammation and further influence hepatic fibrosis by activating hepatic stellate cells
(HSCs). It has been shown that damaged cholangiocytes secrete senescence-associated secretory phenotypes
(SASP). Mast cells (MCs) are important in mediating numerous pathologies including liver diseases, but are
found at very low numbers in normal, homeostatic livers. Infiltrating hepatic MCs are found near damaged
intrahepatic bile ducts and activated HSCs. In unpublished data, we have found that damaged, senescent
cholangiocytes induce MC migration during non-alcoholic fatty liver disease. Further, senescent cholangiocytes
secrete factors like stem cell factor (SCF) and interleukins that are known to be chemoattractants for MCs,
inducing migration. Following migration and activation, MCs release mediators including large amounts of
histamine that stimulates cholangiocyte proliferation and fibrosis. The rationale for our proposal is built upon
previously published data from our lab and others showing that MC infiltration increases in PSC and CCA patients
along with rodent models of liver damage, and MC infiltration positively correlates with increased fibrosis.
Additionally, normal wild-type mice (typically very few hepatic MCs) injected with cultured MCs display increased
biliary damage, inflammation and hepatic fibrosis, all of which are key features of PSC. Using a model of PSC
(Mdr2-/- mice) we generated a double knockout mouse (DKO) by breeding Mdr2-/- with mice lacking histidine
decarboxylase (HDC-/-). DKO mice (few to no MCs) have decreased biliary damage, inflammation and hepatic
fibrosis. Further, upon reintroduction of MCs into DKO mice, we find a striking increase in damage and fibrosis
that mimics Mdr2-/- mice, which was reversed when MCs lacking TGF-β1 signaling were used demonstrating a
key role for MCs in PSC. Finally, inhibition of MC-derived histamine decreases biliary damage and hepatic
fibrosis in models of cholestatic liver injury, PSC and CCA suggesting that modulation of MCs mediators may
prove therapeutic. We propose the working hypothesis that ...

## Key facts

- **NIH application ID:** 10427140
- **Project number:** 5I01BX003031-08
- **Recipient organization:** RLR VA MEDICAL CENTER
- **Principal Investigator:** Heather L Francis
- **Activity code:** I01 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2022
- **Award amount:** —
- **Award type:** 5
- **Project period:** 2016-01-01 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10427140

## Citation

> US National Institutes of Health, RePORTER application 10427140, Mechanisms of synergistic regulation of biliary inflammation and fibrosis (5I01BX003031-08). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10427140. Licensed CC0.

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