TGFB1 and chronic kidney disease: In addition, high levels of TGF-b1 from the fibrotic CKD kidney may also stimulate NPY production because TGF-b1 can stimulate NPY production by fibroblasts as we recently reported in a mouse model of cardiac remodeling.35 During the high sympathetic-driven conditions in CKD patients 24-30, 41, 42, NPY can be released as a potent vasoconstrictor to cause vascular smooth muscle constriction, resulting in chronic and ischemic renal injury.