IL17A and type 1 diabetes mellitus: In addition, Xu et al. [40] have demonstrated that the ratio of IL-17A+CD4+ T cells in peripheral blood mononuclear cells increased in rats with streptozotocin (STZ)-induced type 1 diabetes, and intravitreal injection of anti-IL 23Rp19 antibody, which blocks the IL-23-Th17-IL-17A pathway, improved the blood-retinal barrier function in STZ-treated rats.