MicroRNA-31 Regulates Immunosuppression in Ang II (Angiotensin II)-induced Hypertension by Targeting Ppp6C (Protein Phosphatase 6c).

Regulatory T cells (T_reg cells) play important roles in hypertension and organ damages. MicroRNA-31 (miR-31) is a critical regulator for T_reg cell generation. However, the role of miR-31 in hypertension has not been elucidated. We aim to study the functionality of miR-31 and the detailed mechanism in Ang II (Angiotensin II)-induced hypertensive mouse model. We found: In vitro, miR-31 expression was higher in T helper 17 cells and lower in T_reg cells than that of naïve T cells. The genetic deficiency of miR-31 promoted T_reg cell differentiation, whereas no impact on T helper 17 cells differentiation. Ang II-induced hypertension resulted in increased expression of miR-31 in the aorta, splenic CD4⁺ T cells, and kidney leukocytes. MiR-31 deficiency strikingly decreased systolic blood pressure and diastolic blood pressure and attenuated renal and vascular damage. MiR-31 deletion altered the accumulation of T_reg cells and macrophages and expression of inflammatory cytokines in kidneys in Ang II-induced hypertensive mice. Ang II treatment reduced the levels of anti-inflammatory cytokines and increased proinflammatory cytokines in plasma that were blunted by the miR-31 deletion. Ppp6C (protein phosphatase 6c; a direct target of miR-31) specific deletion in T_reg cells led to marked impairment of T_reg cell induction, increased Ang II-induced blood pressure elevation, and organ damage in mice. In conclusion, we provided novel evidence of miR-31 as an emerging key posttranscriptional regulator of hypertension-associated immunosuppression through targeting ppp6C which is a critical regulator in the differentiation of T_reg cells. This study offers new perspectives on miRNA-based therapeutic approaches.

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