CLDN5 and diabetic kidney disease: To determine whether CLDN5 has a role in diabetic kidney disease, we first studied the expression of CLDN5 in two mouse models of DN, the unilateral nephrectomy (UNX) combined with streptozotocin (STZ)-induced type I diabetic mice and DB/DB type 2 diabetic mice, by double immunostaining for CLDN5 and NPHS2.