The Effects Of Endothelin On The Expressions Of Matrix Metalloproteinase-3 And Tissue Inhibitor Of Metalloproteinase-1 In Glomerulus

Objective:To investigate the effects of endothelin(ET) on the expressions of matrix metalloproteinase-3(MMP-3) and tissue inhibitor of metalloproteinase-1(TIMP-1) in glomerulus and its relationship with the progression of chronic glomerulonephritis. Methods: 1. ET, MMP-3, TIMP-1 and LN protein levels were examined by immunohistochemistry methods in human renal biopsy tissue.The biopsy specimens were divided into five groups:control(n=5), mild mesangioproliferative glomerulonephritis(MsGPN)(n=8), moderate MsGPN (n=6), severe MsGPN (n=6)and sclerosing glomerulonephritis(SGN)(n=6). 2. Cultured human embryonic mesangial cells(MC) were exposed to ET-1 , the expressions of MMP-3 and TIMP-1 proteins in MCs were examined by cell ELISA.3. The expression changes of MMP-3 and TIMP-1 in MCs stimulated by ET-1 were detected with immunocytochemistry methods.4. The level of LN in culture supernatant of MCs was measured by radio-immunity analysis(RIA).Results:1. ET, MMP-3, TIMP-1 and LN were expressed mildly in normal glomerulus and were enhanced in moderate,severe MsGPN and SGN,especially in severe MsGPN(P<0.05 or P<0.01). Glomerular expressions of ET,MMP-3 and LN were noted to diminish in SGN, while the expression of TIMP-1 was observed significantly stronger than normal glomerulus (P<0.01). The ratio of MMP-3/TIMP-1 was decreased in severe MsGPN, especially in SGN. The expression of ET was correlated with the expressions of MMP-3, TIMP-1 and LN, but inversely correlated with the ratio of MMP-3/ TIMP-1(P<0.01). The ratio of MMP-3/TIMP-1 was inversely correlated with the expression of LN and the serum level of creatinine(P<0.05 or P<0.01).The expression of MMP-3 was correlated with urinary protein content(P<0.01).2. The up-regulation of MMP-3 expression in MCs could be observed after stimulated by 10-7mol/L ET-1(P<0.01), and could not be noted if ET-1 concentration≤10-8mol/L. After 24-72 hours exposed to ET-1(10-7mol/L), the expression of MMP-3 in MCs was increased, but the stimulating effect was gradually decreased with the time.3. The expression of TIMP-1 in MCs could be stimulated by ET-1(10-9mol/L~10-7mol/L) in a dose-dependent manner(P<0.01 or P<0.05). After 24-72 hours exposed to ET-1(10-7mol/L), the TIMP-1 expression was increased, especially after 48 hours.4. The ratio of MMP-3/TIMP-1 in MCs exposed to ET-1(10-9mol/L~10-7mol/L) was decreased in a dose-dependent manner(P<0.01 or P<0.05). After 24-72 hours exposed to ET-1(10-7mol/L),the ratio was decreased, especially after 48 hours.5. After 24 hours of ET-1(10-7mol/L) incubation, the level of LN in culture supernatant of MCs was significantly higher than that of control (P<0.01).6. All the results above could be partially blocked by bosentan , an non-selected ETA- and ETB-receptor antagonist .Conclusion:1. ET may be involved in the process of ECM production and degradationin glomerulus. 2. ET-1 decreases the ratio of MMP-3/TIMP-1 and may contribute to the inhibition of ECM degradation.3.Bosentan could partially block the effects of ET-1. It might be used in the treatment of glomerular diseases in the future.