HMGB1-Induced Hepatocyte Pyroptosis Expanding Inflammatory Responses Contributes to the Pathogenesis of Acute-on-Chronic Liver Failure (ACLF)

Weixin Hou; Xiaoyi Wei; Jiajun Liang; Peng Fang; Chongyang Ma; Qiuyun Zhang; Yanbin Gao

doi:10.2147/JIR.S336626

HMGB1-Induced Hepatocyte Pyroptosis Expanding Inflammatory Responses Contributes to the Pathogenesis of Acute-on-Chronic Liver Failure (ACLF)

J Inflamm Res. 2021 Dec 23:14:7295-7313. doi: 10.2147/JIR.S336626. eCollection 2021.

Authors

Weixin Hou^{1

2

3

4}, Xiaoyi Wei^{1

2}, Jiajun Liang^{1

2

3

4}, Peng Fang⁵, Chongyang Ma^{1

2}, Qiuyun Zhang^#^{1

2}, Yanbin Gao^#^{3

4}

Affiliations

¹ Department of Hepatology, School of Traditional Chinese Medicine, Capital Medical University, Beijing, People's Republic of China.
² Department of Hepatology, Beijing Key Laboratory of Traditional Chinese Medicine Collateral Disease Theory Research, Capital Medical University, Beijing, People's Republic of China.
³ Department of Endocrinology, School of Traditional Chinese Medicine, Capital Medical University, Beijing, People's Republic of China.
⁴ Department of Endocrinology, Beijing Key Laboratory of Traditional Chinese Medicine Collateral Disease Theory Research, Capital Medical University, Beijing, People's Republic of China.
⁵ Department of Infectious Diseases, First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, People's Republic of China.

^# Contributed equally.

Abstract

Background: Acute-on-chronic liver failure (ACLF) is a critical disease with a high fatality rate. Immune dysfunction and inflammatory responses are key risk factors in ACLF. Pyroptosis is a form of programmed cell death characterized by the release of inflammatory cytokines, which causes the strong inflammatory responses. High mobility group box-1 (HMGB1) could induce pyroptosis and is closely related to ACLF. However, the role of HMGB1-induced hepatocyte pyroptosis in ACLF has never been proposed; whether HMGB1-induced hepatocyte pyroptosis participates in the development of ACLF and the mechanisms involved are barely understood.

Purpose: This study aimed to clarify the roles of HMGB1-induced hepatocyte pyroptosis in ACLF and the molecular mechanisms involved.

Methods: Wistar rats were randomly divided into five groups, viz.: Normal, ACLF model, HMGB1 inhibitor, Caspase-1 inhibitor, and HMGB1 inhibitor+Caspase-1 inhibitor groups. The ACLF rat model was established using 40% carbon tetrachloride-induced liver fibrosis, followed by D-galactosamine and lipopolysaccharide joint acute attacks. The liver function, coagulation function and pathological damage of rats in each group were evaluated. The biological mechanisms of HMGB1-induced pyroptosis and the release of inflammatory cytokines were investigated using Western blot, quantitative real-time PCR (RT-qPCR), immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay.

Results: The liver function and coagulation function of ACLF rats were seriously impaired; liver tissue showed massive or submassive necrosis, accompanied by inflammatory cell infiltration; the percentage of pyroptotic hepatocytes significantly increased, and a large number of inflammatory cytokines were released. The expression levels of pyroptosis-related genes and proteins in liver tissues and serum significantly increased. But these phenomenons were improved by the inhibition of HMGB1, and the dual inhibition of HMGB1 and Caspase-1 showed a stronger effect.

Conclusion: The findings indicate, for the first time, that pyroptosis is a crucial pathophysiological event of ACLF involved in its pathogenesis, and HMGB1-induced hepatocyte pyroptosis expands inflammatory responses to aggravate ACLF, suggesting that it may be a potential therapeutic target for ACLF treatment.

Keywords: ACLF treatment; HMGB1; inflammatory response; molecular mechanism of ACLF; pyroptosis.