Metabolically and epigenetically reprogrammed splenic TRNP1^hiCD8⁺ T cells exacerbate liver fibrosis

Metabolic dysfunction-associated steatotic liver disease (MASLD), especially its severe form, metabolic dysfunction-associated steatohepatitis (MASH), progresses to liver fibrosis, leading to cirrhosis and liver cancer. The cross-talk between spleen and liver in MASLD/MASH progression remains poorly understood. Here we found enlarged spleens in patients with MASLD and identified induced TRNP1^hiCD8⁺ T cells in spleens of MASLD/MASH mouse models and patients. These cells exhibited pro-fibrotic properties through secretion of INSR-α. Mechanistically, demethylated DNA and H3K27me3, increased H3K27ac and bolstered enhancer-promoter contact synergistically reorganized chromatin topologically associating domains spatially to initiate the expression of transcription factor TRNP1 in splenic CD8⁺ T cells. TRNP1 then transcriptionally activated the expression of FURIN and CTSD, promoting the maturation and ectodomain shedding of INSR-α and facilitating its secretion to activate hepatic stellate cells. In vivo blockade of INSR-α using neutralizing antibodies alleviated MASLD/MASH-induced liver fibrosis. This study reveals splenic TRNP1^hiCD8⁺ T cells with pro-fibrotic properties and suggests a potential anti-fibrotic strategy.