Lkb1 in dendritic cells restricts CD8Foxp3regulatory T cells expansion in vivo.

Liver kinase B1 (Lkb1) in dendritic cells (DCs) plays a key role in maintaining immunity homeostasis and adaptive immunity by controlling the CD4Foxp3T regulatory cell (CD4Tregs) pool and T cells activation. However, the function of Lkb1 in DCs for the regulation of CD8Foxp3T regulatory cells (CD8Tregs) has not been addressed. Herein, we found that Lkb1-deficient DCs could lead to excessive CD8Tregs expansion in multiple organs. We found that OX40 expression was significantly higher in Lkb1-deficient DCs compared with that in wild-type (WT) mice, suggesting a potential pathway of CD8Treg expansion. Moreover, we found that CD8Tregs from mice with conditional deletion Lkb1 in DCs (KO) displayed an activated phenotype and expressed higher levels of specific markers, including ICOS and CD103. Interestingly, compared with the WT mice without lipopolysaccharide(LPS) treatment, we found that CD8Tregs population increased in the WT mice with LPS treatment which can selectively delete Lkb1 protein in DCs. However, there was no significant difference in CD8Tregs population in the KO mice between LPS treatment group and non-LPS treatment. Collectively, our findings identified Lkb1 in DCs as a crucial regulator of CD8Treg expansion.