Blockade of endogenous tissue kallikrein aggravates renal injury by enhancing oxidative stress and inhibiting matrix degradation.
Levels of tissue kallikrein (TK) are significantly lower in the urine of patients with kidney failure, and TK expression is specifically diminished in rat kidney after recovery from ischemia-reperfusion injury. In this study, we investigated the functional consequence of blocking endogenous TK activity in a rat model of chronic kidney disease. Inhibition of endogenous TK levels for 10 days by neutralizing TK antibody injection in DOCA-salt rats caused a significant increase in blood urea nitrogen and urinary protein levels, and a decrease in creatinine clearance. Kidney sections from anti-TK antibody-treated rats displayed a marked rise in tubular dilation and protein cast accumulation as well as glomerular sclerosis and size. TK blockade also increased inflammatory cell infiltration, myofibroblast and collagen accumulation, and collagen fraction volume. Elevated renal inflammation and fibrosis by anti-TK antibody were associated with increased expression of tumor necrosis factor-alpha, intercellular adhesion molecule-1, tissue inhibitor of metalloproteinase-2 (TIMP-2), and plasminogen activator inhibitor-1 (PAI-1). Moreover, the detrimental effect of TK blockade resulted in reduced nitric oxide (NO) levels as well as increased serum lipid peroxidation, renal NADH oxidase activity, and superoxide formation. In cultured proximal tubular cells, TK inhibited angiotensin II-induced superoxide production and NADH oxidase activity via NO formation. In addition, TK markedly increased matrix metalloproteinase-2 activity with a parallel reduction of TIMP-2 and PAI-1 synthesis. These findings indicate that endogenous TK has the propensity to preserve kidney structure and function in rats with chronic renal disease by inhibiting oxidative stress and activating matrix degradation pathways.
Liu
Yuying
Y
Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Ave., Charleston, SC 29425-2211, USA.
Bledsoe
Grant
G
Hagiwara
Makato
M
Yang
Zhi-Rong
ZR
Shen
Bo
B
Chao
Lee
L
Chao
Julie
J
D000804:Angiotensin II; D000818:Animals; D000906:Antibodies; D002460:Cell Line; D006801:Humans; D007674:Kidney Diseases / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000166:cytology; D008297:Male; D045726:Metalloproteases / Q000378:metabolism; D018384:Oxidative Stress; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011920:Rats, Inbred WF; D017382:Reactive Oxygen Species; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics / Q000378:metabolism; D020840:Tissue Kallikreins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D000906:Antibodies; D017395:Plasminogen Activator Inhibitor 1; D017382:Reactive Oxygen Species; D016212:Transforming Growth Factor beta; D000804:Angiotensin II; D019716:Tissue Inhibitor of Metalloproteinase-2; D045726:Metalloproteases; D020840:Tissue Kallikreins