N-glycosylated LTβR increases the Th17/Treg cell ratio in liver cancer by blocking RORC ubiquitination and FOXP3 transcription.

LTβR-overexpressing CAR-T cells have demonstrated surprising effectiveness against solid tumors, exhibiting strong anti-exhaustion and proliferation capabilities. However, the role of LTβR in CD4 T cell differentiation and anti-tumor activity remains unclear. In this study, we employed primary or subcutaneous mouse hepatocellular carcinoma (HCC) models and flow cytometry to study the impact of conditional knock-in of Ltbr on CD4 T cell differentiation and response, particularly the Th17/Treg cell ratio, and its influence on HCC progression. Immunoprecipitation, immunoblotting, RT-qPCR, molecular docking, and Chromatin Immunoprecipitation-qPCR were performed to investigate the molecular mechanism of CD4 T cell differentiation. Adeno-associated virus-modified T cells were introduced into patient-derived orthotopic xenograft (PDOX) model to assess the combined impact of LTβR and glycolysis inhibitors on the Th17/Treg cell differentiation. We found that LTβR reduced PELI1 expression, preventing TRAF3 protein degradation in Th17 cells. TRAF3 then competed with RORC for SMURF1 binding, enhancing RORC stability and Th17 cell differentiation. LTβR also blocked PRDM1 expression, delaying Foxp3 transcription and Treg cell infiltration. Additionally, N-glycosylation supported the stability of LTβR by protecting it from ubiquitination. From a therapeutic perspective, glycolysis inhibitors helped LTβR balance the proportion of Th17/Treg cells in PDOX model to inhibit tumor growth. In conclusion, our findings indicated that LTβR N-glycosylation prevented RORC ubiquitination and Foxp3 transcription, raising the Th17/Treg cell ratio and hindering HCC progression.