Protease administration decreases enhanced transforming growth factor-beta 1 content in isolated glomeruli of...

Overproduction of transforming growth factor (TGF)-beta 1 messenger RNA is of fundamental importance in the pathogenesis of diabetic nephropathy. In vitro studies have recently shown that the serine protease trypsin diminishes the enhanced TGF-beta 1-expression induced by advanced glycation end products. Moreover, proteolytic enzymes may accelerate the removal of TGF-beta 1 from renal tissue via a protease-induced activation of alpha 2-macroglobulin (alpha 2M). This activation results in the binding of numerous cytokines, including TGF-beta 1 and is followed by enhanced plasma clearance of the protease alpha 2M-cytokine complex. In the present study in streptozotocin-diabetic rats we investigated whether the administration of Phlogenzym, a fixed combination of the proteases trypsin and bromelain combined with the antioxidant rutosid, modulates renal hypertrophy and the formation of TGF-beta 1 in isolated glomeruli. Three weeks after induction of diabetes, renal hypertrophy developed with an enhanced kidney/body weight ratio. When compared with normal rats, an elevated content of intraglomerular TGF-beta 1 (44.25 +/- 21.9 vs. 71.1 +/- 23.4 ng/microgram DNA, p < 0.05) as well as fibronectin (2.62 +/- 0.49 vs. 3.42 +/- 0.62 ng/microgram DNA, p < 0.05) was observed. In the diabetic rats, treatment with intraperitoneal proteases prevented the rise of intraglomerular TGF-beta 1 content (34.9 +/- 22.2 ng/microgram DNA, p < 0.01) and attenuated the rise of fibronectin (3.03 +/- 1.12 ng/microgram DNA NS). Furthermore, a decrease in the kidney/body weight ratio (p < 0.01) was achieved. Protease administration did not affect blood glucose concentration and was without visible adverse effects.