not-yet-known not-yet-known not-yet-known unknown Abnormal activation of T cells is one of the main pathogenesis of psoriasis, and mesenchymal stem cells (MSCs) play important roles in immune regulation. To investigate the mechanism of regulation of T cell activities by miR-183-5p in psoriatic MSCs exosomes. MSCs were isolated from the skin tissues of normal people and patients with psoriasis. The exosomes of psoriatic and normal skin MSCs were extracted by ultrafast centrifuge, and then co-cultured with human Jurkat T cells. miRNA sequencing was performed and 29 different miRNAs were screened. The results showed that psoriatic MSCs exosomes can stimulate Jurkat T cells to secrete IL-17A and IL-23, while TGF-β secretion is reduced. The expression of miR-183-5p in psoriatic MSCs exosomes was significantly decreased, and the expression of FOXO1 in Jurkat T cells was significantly increased after co-culture. The exosomes from MSCs transfected with miR-183-5p-inhibitor siginificantly increased the expression of IL-17A and IL23, while decreased the expression of TGF-β in Jurkat T cells. Psoriatic MSCs regulate T cells activities through exosome-mediated miR-183-5p/FOXO1 pathway. Overexpression of miR-183-5p can inhibit T cell activities and reverse immune activation in psoriasis, suggesting utility of miR-183-5p as a potential therapeutic intervention for psoriasis.