Pyroptosis Plays a Key Role Through Macrophages in Primary Biliary Cholangitis of Mice

TL;DR

This study shows that pyroptosis, a form of cell death, is active in a mouse model of primary biliary cholangitis and may be driven by macrophages.

Contribution

The study identifies pyroptosis and macrophage involvement in PBC for the first time using both human data and a mouse model.

Findings

Pyroptosis pathway is upregulated in PBC mice, confirmed by qRT-PCR and Western blotting.

Macrophages are the main cell type expressing gasdermin D in PBC mice.

M2 macrophage percentage is significantly reduced in PBC mice compared to controls.

Abstract

Primary biliary cholangitis (PBC) is an autoimmune intrahepatic cholestatic disease with both environmental and genetic participation. In this study, we aim to investigate the involvement of pyroptosis in PBC mice based on prior bioinformatic analysis of PBC patients and explore the immune cell populations potentially involved.

KEGG pathway enrichment analysis was performed using the GSE119600 dataset from the Gene Expression Omnibus (GEO) database, which includes whole‐blood samples from PBC patients (n = 90) and non–liver disease CTRs (n = 47). The bioinformatic analysis was conducted prior to and in guidance of the subsequent animal experiments. A total of 20 female C57BL/6 mice aged 4–6 months were randomly divided into the PBC group and the control (CTR) group. The PBC model was induced by two doses of 2‐nonynoic acid (2OA‐BSA) and polyinosinic–polycytidylic acid (poly I: C) for a total of 12 weeks. The pyroptosis pathway was examined by quantitative real‐time PCR (qRT‐PCR), Western blotting, and immunohistochemistry. Immunofluorescent (IF) staining and flow cytometry were performed on liver samples from PBC mice to assess the pyroptosis pathway and distinct immune cell populations.

Toll‐like receptor and NOD‐like receptor signaling pathways were identified in blood samples of PBC patients in KEGG pathway enrichment analysis. In the PBC mouse model, the pyroptosis pathway was found to be upregulated by qRT‐PCR (p < 0.05) and Western blotting (0.7786 ± 0.1371, p < 0.001). IHC staining revealed increased GSDMD and Casp1 expression in PBC mice, and macrophages were identified as the main cell type expressing gasdermin D (GSDMD) by IF staining. Flow cytometry showed a decrease in the percentage of M2 macrophages (6.10 ± 2.12 vs. 3.24 ± 0.93, p < 0.05).

Pyroptosis plays a key role in PBC patients and 2OA‐BSA induced PBC mice, with macrophages possibly serving as important executors. Inhibition of the pyroptosis pathway might be a potential target for the future treatment of PBC.

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