TNFSF15 and diabetes mellitus: In this study, we demonstrated a decreased TNFSF15/VEGF ratio in the vitreous of PDR patients, even though the expression level of TNFSF15 was increased; in diabetic animals, TNFSF15 expression was obviously decreased one month after DM induction, then increased gradually with disease progression; moreover, TNFSF15 inhibited changes in TJPs and BRB permeability induced by DR, which might be correlated with downregulation of VEGF.