To this end, we have investigated the subsets of macrophages during obstruction-induced CKD progression and have discovered that tPA promotes M1 macrophage accumulation in the fibrotic kidneys with concurrent induction of proinflammatory chemokines, such as inducible nitric oxide synthase (iNOS), TNF-α, and interleukin (IL)-1β [82]. Here, NOS2 is linked to chronic kidney disease.