IL‐22 produced by Th22 cells aggravates atherosclerosis development in ApoE(−/−) mice by enhancing DC‐induced Th17 cell proliferation

Th22 cells are a novel subset of CD4(+) T cells that primarily mediate biological effects through IL‐22, with both Th22 cells and IL‐22 being closely associated with multiple autoimmune and chronic inflammatory diseases. In this study, we investigated whether and how Th22 cells affect atherosclerosis. ApoE(−/−) mice and age‐matched C57BL/6J mice were fed a Western diet for 0, 4, 8 or 12 weeks. The results of dynamic analyses showed that Th22 cells, which secrete the majority of IL‐22 among the known CD4(+) cells, play a major role in atherosclerosis. ApoE(−/−) mice fed a Western diet for 12 weeks and administered recombinant mouse IL‐22 (rIL‐22) developed substantially larger plaques in both the aorta and aortic root and higher levels of CD3(+) T cells, CD68(+) macrophages, collagen, IL‐6, Th17 cells, dendritic cells (DCs) and pSTAT3 but lower smooth muscle cell (SMC) α‐actin expression than the control mice. Treatment with a neutralizing anti–IL‐22 monoclonal antibody (IL‐22 mAb) reversed the above effects. Bone marrow‐derived DCs exhibited increased differentiation into mature DCs following rIL‐22 and ox‐LDL stimulation. IL‐17 and pSTAT3 were up‐regulated after stimulation with IL‐22 and ox‐LDL in cells cocultured with CD4(+) T cells and mature DC supernatant, but this up‐regulation was significantly inhibited by IL‐6mAb or the cell‐permeable STAT3 inhibitor S31‐201. Thus, Th22 cell‐derived IL‐22 aggravates atherosclerosis development through a mechanism that is associated with IL‐6/STAT3 activation, DC‐induced Th17 cell proliferation and IL‐22–stimulated SMC dedifferentiation into a synthetic phenotype.