Advanced glycation end products activate a chymase-dependent angiotensin II-generating pathway in diabetic complications.
BACKGROUND
Angiotensin II is a key mediator of diabetes-related vascular disease. It is now recognized that in addition to angiotensin-converting enzyme, chymase is an important alternative angiotensin II-generating enzyme in hypertension and diabetes. However, the mechanism of induction of chymase in diabetes remains unknown.


RESULTS
Here, we report that chymase is upregulated in coronary and renal arteries in patients with diabetes by immunohistochemistry. Upregulation of vascular chymase is associated with deposition of advanced glycation end products (AGEs), an increase in expression of the receptor for AGEs (RAGE), and activation of ERK1/2 MAP kinase. In vitro, AGEs can induce chymase expression and chymase-dependent angiotensin II generation in human vascular smooth muscle cells via the RAGE-ERK1/2 MAP kinase-dependent mechanism. This is confirmed by blockade of AGE-induced vascular chymase expression with a neutralizing RAGE antibody and an inhibitor to ERK1/2 and by overexpression of the dominant negative ERK1/2. Compared with angiotensin-converting enzyme, chymase contributes to the majority of angiotensin II production (>70%, P<0.01) in response to AGEs. Furthermore, AGE-induced angiotensin II production is blocked by the anti-RAGE antibody and by inhibition of ERK1/2 MAP kinase activities.


CONCLUSIONS
AGEs, a hallmark of diabetes, induce chymase via the RAGE-ERK1/2 MAP kinase pathway. Chymase initiates an important alternative angiotensin II-generating pathway in diabetes and may play a critical role in diabetic vascular disease.
Koka
Vijay
V
Department of Medicine-Nephrology, Baylor College of Medicine, Houston, TX 77030, USA.
Wang
Wansheng
W
Huang
Xiao Ru
XR
Kim-Mitsuyama
Shokei
S
Truong
Luan D
LD
Lan
Hui Y
HY
D000328:Adult; D000368:Aged; D000804:Angiotensin II / Q000096:biosynthesis / Q000378:metabolism*; D053818:Chymases; D003925:Diabetic Angiopathies / Q000209:etiology*; D005260:Female; D017127:Glycation End Products, Advanced / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D006973:Hypertension; D008297:Male; D008875:Middle Aged; D048052:Mitogen-Activated Protein Kinase 3 / Q000032:analysis / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000737:chemistry / Q000166:cytology; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000378:metabolism; D012697:Serine Endopeptidases / Q000032:analysis / Q000502:physiology*; D015854:Up-Regulation
D017127:Glycation End Products, Advanced; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D000804:Angiotensin II; D048052:Mitogen-Activated Protein Kinase 3; D012697:Serine Endopeptidases; D053818:Chymases