INHIBITORY EFFECT OF TRIPTERYGIUM-WILFORDII MULTIGLYCOSIDE ON INCREASED GLOMERULAR ALBUMIN PERMEABILITY IN-VITRO

Background. Tripterygium wilfordii Hook F is a medicinal plant used fo r the treatment of glomerulonephritis in China. We studied the effect of Tripterygium wilfordii multiglycoside (TWG) on glomerular albumin p ermeability (P-albumin) in vitro. Methods. Isolated rat glomeruli were incubated with protamine (600 mu g/ml) for 30 min, or with human reco mbinant tumour necrosis factor (TNF-alpha, 0.4 ng/ml), superoxide (10 units/ml), or serum from a focal segmental glomerular sclerosis (FSGS) patient for 10 min at 37 degrees C. TWG, 1 mg/ml, was added in parall el tubes to study the effect on P-albumin. Control glomeruli were incu bated under identical conditions. The albumin reflection coefficient ( sigma(albumin)) was calculated from the change in glomerular volume in response to an applied oncotic gradient. Convectional permeability (P -albumin) was calculated as (1-sigma(albumin)). Results. Compared with controls, protamine increased the P-albumin of glomeruli (0.83 +/- 0. 05, n = 25 vs 0.18 +/- 0.03, n = 20); pretreatment with TWG blocked th is effect (0.13 +/- 0.04, n = 25). TNF-alpha also increased the P-albu min (0.79 +/- 0.04, n = 24 vs 0.04 +/- 0.07, n = 19); preincubation wi th TWG blocked this effect (0.03 +/- 0.09, n = 24). P-albumin of glome ruli incubated with xanthine and xanthine oxidase, resulting in the pr oduction of superoxide, also increased as compared to controls (0.85 /- 0.04, n = 15 vs 0.08 +/- 0.05, n = 14); TWG blocked this effect as well (0.21 +/- 0.08, n = 14). FSGS serum also increased P-albumin Of g lomeruli significantly (0.88 +/- 0.02, n = 49 vs 0.00 +/- 0.02, n = 49 ); preincubation with TWG blocked this effect (0.05 +/- 0.07, n = 30). TWG by itself had no effect on P-albumin (0.19 +/- 0.10, n = 15).Conc lusions. Our results show that TWG blocks protamine, TNF-alpha, supero xide, and FSGS serum-mediated increase in glomerular albumin permeabil ity in vitro. We conclude that reduction of proteinuria by Tripterygiu m wilfordii multiglycoside in various kinds of glomerular diseases in vivo might be due to protection of the glomerular filtration barrier.