Nature Genetics | TRNP1hiCD8+ T Cells Promote Liver Fibrosis via INSR-α

This study reveals a critical role of a splenic CD8+ T cell subset in the progression of metabolic dysfunction-associated steatotic liver disease, providing novel experimental design ideas for immune mechanism research in MASLD and liver fibrosis, and suggesting INSR-α as a potential therapeutic target.

 

Literature Overview

The article titled 'Metabolically and epigenetically reprogrammed splenic TRNP1hiCD8+ T cells exacerbate liver fibrosis,' published in Nature Genetics, systematically investigates how splenic CD8+ T cells acquire profibrotic functions through epigenetic and metabolic reprogramming in the context of metabolic dysfunction-associated steatotic liver disease (MASLD). By integrating human cohort studies, animal models, and multi-omics analyses, the study uncovers a previously unknown spleen-liver axis signaling pathway. It further elucidates the molecular mechanism by which TRNP1, acting as a transcription factor, drives the secretion of INSR-α, providing crucial theoretical insights into the progression of chronic liver disease.

Background Knowledge

MASLD has become the most common chronic liver disease worldwide, with its severe form, MASH, progressing to liver fibrosis, cirrhosis, and even hepatocellular carcinoma. Although the role of the immune system in disease progression is increasingly recognized, the inter-organ communication between the spleen and liver remains poorly understood. Most existing studies focus on local liver immune cells, such as Kupffer cells or NKT cells, while the systemic roles of spleen-derived immune cells lack in-depth analysis. In particular, the heterogeneity of CD8+ T cells and their regulatory roles in fibrosis remain controversial. This study's starting point was the observation of spleen enlargement in MASLD patients, followed by single-cell sequencing that identified a distinct TRNP1hiCD8+ T cell subset. This subset is not only induced in the spleen but also closely linked to HSC activation, leading to the novel hypothesis of a 'spleen-derived T cell—hepatic stellate cell' axis. This discovery fills a mechanistic gap in the transition from MASLD/MASH to fibrosis and suggests that TRNP1 may serve as a biomarker or therapeutic target for disease progression.

 

 

Research Methods and Experiments

The authors first confirmed spleen enlargement in MASLD patients across two independent human cohorts, suggesting a potential role of the spleen-liver axis in disease progression. Using MASLD/MASH mouse models induced by MCDHFD and CDAHFD diets, combined with scRNA-seq and T cell receptor sequencing, they identified significant expansion of splenic CD8+ T cells that specifically and highly expressed the transcription factor TRNP1. RNAscope technology confirmed co-expression of Trnp1 mRNA and CD8 protein, ruling out interference from other cell types. To validate function, the researchers generated Cd8-Cre-mediated Trnp1 conditional knockout mice (Trnp1^cko). In the MCDHFD model, these mice exhibited significantly reduced liver fibrosis, while lipid accumulation and inflammation remained unaffected, indicating that TRNP1 specifically regulates the fibrotic pathway. Furthermore, adoptive transfer experiments and splenectomy confirmed that TRNP1hiCD8+ T cells originate from the spleen and are sufficient to drive fibrosis progression.

Key Conclusions and Perspectives

• In the context of MASLD/MASH, splenic CD8+ T cells undergo metabolic and epigenetic reprogramming, leading to upregulated TRNP1 expression — this finding suggests TRNP1 as a marker of spleen-derived T cell activation, guiding future exploration of similar subsets in autoimmune liver diseases or metabolic inflammation.
• TRNP1 promotes the maturation and membrane shedding of precursor INSR by regulating FURIN and CTSD, ultimately resulting in the secretion of soluble INSR-α — this reveals a novel mechanism by which T cells directly secrete functional receptor subunits, suggesting INSR-α is not only a metabolic factor but also a potential immune effector molecule, opening new avenues in immunometabolism research.
• The secreted INSR-α binds to INSR on hepatic stellate cells, activating the ERK/p90RSK pathway to induce their activation — this provides a non-TGF-β-dependent pathway for HSC activation, highlighting a non-canonical role of INSR in liver fibrosis and supporting the development of neutralizing antibody strategies targeting INSR-α.
• In vivo administration of ersodetug (an anti-INSR monoclonal antibody) significantly alleviates fibrosis without affecting glucose homeostasis — this indicates that targeting INSR-α offers a therapeutic window, avoiding metabolic side effects associated with traditional insulin pathway interventions, and advancing it into the preclinical development phase.

Research Significance and Prospects

This study fundamentally shifts the understanding of CD8+ T cells in chronic liver disease—from traditional cytotoxic effectors to profibrotic signal transducers. It not only defines a new immune cell subset (TRNP1hiCD8+ T cells) but also reveals the coupled mechanism between epigenetic regulation (H3K27me3/H3K27ac), chromatin spatial conformation, and protein secretion, providing a paradigm for understanding immune cell functional plasticity.

In terms of drug development, INSR-α, as a soluble target, is more amenable to targeting than intracellular signaling nodes. Neutralizing antibodies such as ersodetug have already shown antifibrotic potential without affecting systemic insulin sensitivity, suggesting they may become precision therapeutics for late-stage MASH patients. Meanwhile, although TRNP1 itself is a nuclear transcription factor, its upstream methyl donor deficiency (e.g., methionine, choline) could serve as a nutritional intervention target, implying that dietary adjustments or supplementation might slow disease progression.

Regarding disease modeling, this study supports the use of CDAHFD or MCDHFD models to recapitulate the immune-metabolic dysregulation features of human MASLD/MASH, especially for evaluating spleen-liver axis-related phenotypes. Combining Trnp1-floxed mice with Cd8-Cre mice enables the generation of conditional knockout models for mechanistic validation. Additionally, humanized HSC and CD8+ T cell co-culture systems can be used to test the in vitro efficacy of INSR-α blockers, accelerating drug evaluation pipelines.

 

 

Conclusion

This study redefines the spleen as a key immune regulatory organ in the progression of MASLD/MASH, revealing a novel mechanism by which TRNP1hiCD8+ T cells remotely activate hepatic stellate cells via INSR-α secretion. This discovery not only deepens our understanding of liver fibrosis development but also provides multiple intervention points for clinical translation: neutralizing antibodies targeting INSR-α, epigenetic drugs modulating TRNP1 expression, and nutritional strategies to improve methyl donor status. From bench to bedside, this work establishes a solid mechanistic foundation for developing antifibrotic therapies, potentially improving long-term outcomes for MASLD patients. More importantly, it suggests that systemic immune status should be evaluated comprehensively, rather than focusing solely on the liver microenvironment, thereby promoting a more holistic, multi-organ interaction framework in chronic liver disease research. This mechanism may also apply to other fibrotic diseases, such as pulmonary or renal fibrosis, offering broad scientific and clinical implications.

 

Liyuan Zhang, Yahui Wang, Kai Wei, Shanrong Liu, and Jin Hou. Metabolically and epigenetically reprogrammed splenic TRNP1hiCD8+ T cells exacerbate liver fibrosis. Nature Genetics.