Lymphocyte activation gene 3 (Lag3) supports Foxp3 + Treg cell function by restraining c-Myc-dependent aerobic glycolysis.

Lymphocyte activation gene 3 (Lag3) has emerged as the next-generation immune checkpoint molecule due to its ability to inhibit effector T cell activity. Foxp3 + regulatory T (Treg) cells, a master regulator of immunity and tolerance, also highly express Lag3. While Lag3 is thought to be necessary for Treg cell-mediated regulation of immunity, the precise roles and underlying mechanisms remain largely elusive. In this study, we report that Lag3 is indispensable for Treg cells to control autoimmune inflammation. Utilizing a newly generated Treg cell specific Lag3 mutant mouse model, we found that these animals are highly susceptible to autoimmune diseases, suggesting defective Treg cell function. Genome wide transcriptome analysis further uncovered that Lag3 mutant Treg cells upregulated genes involved in metabolic processes. Mechanistically, we found that Lag3 limits Treg cell expression of Myc, a key regulator of aerobic glycolysis. We further found that Lag3-dependent Myc expression determines Treg cells’ metabolic programming as well as the in vivo function to suppress autoimmune inflammation. Taken together, our results uncovered a novel function of Lag3 in supporting Treg cell suppressive function by regulating Myc-dependent metabolic programming.

Transcriptional Interactomic Inhibition of RORα Suppresses Th17-Related Inflammation.

PURPOSE: Th17 cells and their cytokines are implicated in the pathogenesis of various autoimmune diseases. Retinoic acid-related orphan receptor alpha (RORα) is a transcription factor for the differentiation and the inflammatory functions of Th17 cells. In this study, we generated the nucleus-transducible form of transcription modulation domain of RORα (nt-RORα-TMD) to investigate the functional roles of RORα in vitro and in vivo under normal physiological condition without genetic alteration. METHODS: The functions of nt-RORα-TMD were analyzed in vitro through flow cytometry, luciferase assay, ELISA, and transcriptome sequencing. Finally, the in vivo therapeutic effects of nt-RORα-TMD were verified in dextran sulfate sodium (DSS)-induced colitis mice. RESULTS: nt-RORα-TMD was effectively delivered into the cell nucleus in a dose- and time-dependent manner without any cellular toxicity. nt-RORα-TMD competitively inhibited the RORα-mediated transcription but not RORγt-mediated transcription. Secretion of IL-17A from the splenocytes was suppressed by nt-RORα-TMD without affecting the secretion of Th1- or Th2-type cytokine and T cell activation events such as induction of CD69 and CD25. The differentiation potential of naïve T cells into Th17 cells, not into Th1, Th2, or Treg cells, was significantly blocked by nt-RORα-TMD. Consistently, mRNA sequencing analysis showed that nt-RORα-TMD treatment down-regulated the expression of the genes related to the differentiation and functions of Th17 cells. Treatment of DSS-induced colitis mice with nt-RORα-TMD improved the overall symptoms of colitis, such as body weight change, colon length, infiltration of inflammatory cells, and the level of inflammatory cytokines in the serum. In the mesenteric lymph node (MLN) of the nt-RORα-TMD-treated mice, the population of CD4+IL-17A+ Th17 cells was reduced, and the population of CD4+Foxp3+ Treg cells increased. CONCLUSION: nt-RORα-TMD has a potential to be developed as a novel therapeutic reagent for treating various inflammatory diseases in which Th17 cells are the leading pathological player.