MiR-195 regulates CD40 to maintain Th17/Treg balance in rats with non-alcoholic fatty liver disease.

Purpose: This study aims to explore the relationship between miR-195 and CD40 and its effect on Th17/Treg balance in rats with non-alcoholic fatty liver disease (NAFLD).

Methods: We established rat models of NAFLD and made seven groups, Normal group (without modeling), Model group (model rats), NC group (model rats injected with negative control vector), miR-195 OE group (model rats injected with miR-195 mimic), anti-miR-195 group (model rats injected with miR-195 inhibitor), Si-CD40 group (model rats injected with CD40 silencing vector), and anti-miR-195+Si-CD40 group (model rats injected with miR-195 inhibitor and CD40 silencing vector). Dual-luciferase reporter gene assay verified the targeting relationship between miR-195 and CD40. The mRNA and protein expression levels of miR-195, CD40 as well as Th17/Treg associated cytokines in the liver tissues were detected. The pathological changes of liver tissues were detected, and the liver lesion scoring was carried out. The liver coefficient was calculated. The levels of liver function related indices, and Th17/Treg associated cytokines and inflammatory factors in serum were determined. The proportions of Th17/Treg cells in serum were determined by flow cytometry.

Results: Compared with Normal group, miR-195 expression level in liver tissues of rats in other six groups was significantly reduced (all P < 0.05); the serum levels of AST, ALT, GGT, IL-17, TNF-α, IL-23, IL-6, IL-8, TC, TG, HDL, and LDL, and the Th17/Treg ratio, as well as the mRNA and protein expression levels of CD40, RORyt, IL-17, TNF-α, IL-23, and IL-8 in liver tissues were significantly increased (all P < 0.05); while the mRNA and protein expression levels of Foxp3, and IL-10 level were significantly reduced (all P < 0.05). Compared with Model group, the above parameters showed an opposite trend in miR-195 OE group and Si-CD40 group were significantly reduced (all P < 0.05). Moreover, anti-miR-195 group could aggravate the imbalance of Th17/Treg cells in rats with NAFLD and promote inflammatory response. Compared with anti-miR-195 group, the combined treatment in anti-miR-195+Si-CD40 group can partially avoid the imbalance of Th17/Treg cells, and inhibit inflammatory response.

Conclusion: Overexpression of miR-195 can reduce the Th17/Treg ratio to maintain Th17/Treg balance by inhibiting CD40 expression in rats with NAFLD.