Regulation of IL-17A-mediated hypersensitivity by extracellular vesicles and lipid nanoparticles carrying miR-451a.

Extracellular vesicles (EVs), including exosomes, mediate intercellular communication by transporting functional molecules between donor cells and recipient cells, thereby regulating biological processes, such as immune responses. miR-451a, an immune regulatory microRNA, is highly abundant in circulating EVs; however, its precise physiological significance remains to be fully elucidated. Here, we demonstrate that miR-451a deficiency exacerbates delayed-type hypersensitivity (DTH) in mice. Notably, miR-451a knockout resulted in a significant increase in the number of interleukin (IL)-17A-expressing T helper 17 and γδ T cells infiltrating DTH-induced ear lesions. miR-451a deficiency also increased the number of γδ T cells in the secondary lymphoid tissues. Comprehensive analyses revealed that miR-451 deficiency promoted the expression of Rorc and γδ T cell-related genes following sensitization with allergens. Moreover, intravenous administration of wild-type EVs to miR-451a knockout mice increased cellular miR-451a levels in tissues and significantly attenuated the severity of DTH. Furthermore, synthetic lipid nanoparticles encapsulating miR-451a effectively mitigated DTH. Our findings indicate the importance of circulating miR-451a in the proliferation of γδ T cells and highlight the therapeutic potential of lipid nanoparticle-based microRNA delivery platforms for interventions in immune-related diseases.