摘要Objective:Cytotoxic T lymphocytes(CTLs)play a crucial role in the therapeutic approach to hepatocellular carcinoma(HCC).Recent research has indicated that junctional adhesion molecule-like protein(JAML)enhances the antitumor activity of CD8+T cells.Our study investigates the role of JAML+CD8+T cells in HCC.Methods:We utilized time-of-flight mass cytometry and an orthotopic mouse model of HCC to examine histone modifications in tumor-infiltrating immune cells undergoing immunotherapy.Flow cytometry was used to assess CD4+T cells differentiation and JAML expression in CD8+T cells infiltrating HCC.Correlation analysis revealed a strong positive correlation between lactate dehydrogenase A+(LDHA+)CD4+T cells and JAML+CD8+T cells.Subsequently,we evaluated the therapeutic effects of an agonistic anti-JAML antibody,both alone and combined with immunotherapy.Finally,RNA sequencing was conducted to identify potential regulatory mechanisms.Results:Immunotherapy significantly increased the percentage of CD8+T cells infiltrating HCC and induced histone modifications,such as H3K18 lactylation(H3K181a)in CD4+T cells.Flow cytometry analysis revealed that lactate promotes the differentiation of CD4+T cells into Th1 cells.LDHA,an enzyme that converts pyruvate to lactate,plays a key role in this process.Correlation analysis revealed a strong positive relationship between LDHA+CD4+T cells and JAML+CD8+T cells in patients who responded to immunotherapy.Moreover,high JAML expression in CD8+T cells was associated with a more favorable prognosis.In vivo experiments demonstrated that agonistic anti-JAML antibody therapy reduced tumor volume and significantly prolonged the survival of tumor-bearing mice,independent of the effects of anti-programmed cell death protein ligand-1 antibody(αPD-L1)-mediated immunotherapy.Pathway enrichment analysis further revealed that JAML enhances CTL responses through the oxidative phosphorylation pathway.Conclusions:Activation of JAML enhances CTL responses in HCC treatment,independent of αPD-L1-mediated immunotherapy,providing a promising strategy for advanced HCC.