Aluminum adjuvant promotes liver inflammation and fibrosis in mice: A novel approach to establish a liver fibrosis animal model

Abstract

Background and aims: Liver fibrosis is a prevalent pathological stage of various chronic liver diseases and has the potential to progress to liver cirrhosis and hepatocellular carcinoma. However, experimental models for in vivo research are limited. Unexpectedly, increased liver inflammation and fibrosis were previously observed in mice treated with aluminum adjuvant (commercial Imject Alum, a mixture of Al(OH)₃ and Mg(OH)₂). Our study aimed to reveal the pathogenesis and pathological features of Imject Alum-induced liver injury and evaluate its potential as an experimental model of fibrotic liver disease.

Methods and materials: C57BL/6J mice were randomly divided into the following four groups: (i) control group, which received phosphate-buffered saline injections on days 1, 12, 26, 40, and 54; (ii) Imject Alum (Al(OH)₃ 160 mg/kg) D26 group, which was administered with Imject Alum (Al(OH)₃ 160 mg/kg) on days 1, 12, and 26; (iii) Imject Alum (Al(OH)₃ 80 mg/kg) D54; and (iv) Imject Alum (Al(OH)₃ 160 mg/kg) D54 groups, which were treated with 80 mg/kg and 160 mg/kg of Imject Alum (Al(OH)₃), respectively, on days 1, 12, 26, 40, and 54. All reagents were delivered by intraperitoneal injection. Serum biochemical parameters, liver pathology, and expression of genes related to inflammation and fibrogenesis were evaluated. Transcriptome sequencing was performed. The genetic characteristics of the Imject Alum-induced liver lesions in the existing fibrosis model and patients with cirrhosis were determined.

Results: Administration of Imject Alum (Al(OH)₃ 160 mg/kg) at certain points for 54 days led to extensive hepatic inflammation and fibrosis, accompanied by disturbed bile acid metabolism in mice. Moreover, Imject Alum aggravated liver inflammation and injury by activating the pyroptosis-related inflammasome pathway. Transcriptome analysis revealed that Imject Alum-induced liver lesions had differentially expressed genes that were significantly enriched in pathways related to inflammation, fibrogenesis, and multiple metabolic processes. Moreover, Imject Alum-induced liver lesions exhibited gene signatures similar to those of existing fibrosis models and patients with cirrhosis.

Conclusions: Aluminum adjuvant (Imject Alum; Al(OH)₃ 160 mg/kg) administration at certain points for 54 days resulted in notable liver injury, inflammation, and fibrosis. This model had similar gene expression characteristics with existing fibrosis models and liver samples from patients with cirrhosis. Overall, aluminum adjuvant (Imject Alum)-induced mouse model may be a novel approach for establishing a liver fibrosis animal model.

Keywords

Liver fibrosis / Cirrhosis / Aluminum adjuvant / Inflammation / Animal model

Authors’ contributions

Zhixian Zhu: Writing e original draft, Visualization, Method-ology, Formal analysis, Data curation. Sen Liang: Writing e original draft, Validation, Investigation, Formal analysis, Data curation. Nan Zhao: Methodology, Investigation, Data curation. Huiling Zou: Supervision, Methodology, Funding acquisition. Liangjun Zhang: Investigation, Data curation, Conceptualization, Funding acquisi-tion. Xiaoxun Zhang: Writing e review & editing, Writing e original draft, Supervision, Conceptualization. Jin Chai: Supervi-sion, Project administration, Methodology, Funding acquisition, Conceptualization.

Data availability statement

All the datasets are available from the corresponding authors on reasonable request. The raw sequencing data of this study have been deposited in the Genome Sequence Archive in Beijing Institute of Genomics (BIG) Data Center (https://bigd.big.ac.cn/), with the accession number: CRA010020.

Declaration of competing interest

The authors declare that they have no conflict of interest.

Acknowledgements

This work was granted by grants from the National Natural Science Foundation of China (No. 82325008 and No. 92268110 to Jin Chai), Chongqing Postdoctoral Science Foundation (No. 2023CQBSHTB309 to Liangjun Zhang) and Changsha Hospital for Maternal & Child Health Care (No. 2022YJ04 to Huiling Zou).

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.livres.2025.05.001.

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