Fibrin formation within the glomeruli occurs in various forms of human and experimental glomerulonephritis and it may play an important role in progressive glomerular injury. Transforming growth factor-beta (TGF-beta) has been shown to participate in the glomerular accumulation of extracellular matrix in glomerulonephritis. We investigated whether thrombin, an important coagulation factor, could modulate the production of TGF-beta by cultured human mesangial cells (HMC). TGF-beta levels in the culture supernatants were measured by ELISA using a specific antibody. The TGF-beta concentration was significantly increased by incubation of HMC with thrombin in a time-dependent manner. The stimulating effect of thrombin on TGF-beta was inhibited by addition of hirudin (a natural thrombin inhibitor) and argatroban (a synthetic thrombin inhibitor). In addition DFP-inactivated thrombin, which has no enzymatic activity, did not stimulate TGF-beta production. A protein kinase C inhibitor (H7) and a tyrosine kinase inhibitor (herbimycin A) also inhibited thrombin induced TGF-beta production. These findings suggested that thrombin may modulate the synthesis of TGF-beta via protein kinase C- and tyrosine kinase-dependent mechanisms in cultured HMC. Thus thrombin may participate in the accumulation of extracellular matrix in glomeruli through the augmentation of TGF-beta production.

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Abstractdegradation or both may result in its accumulation in the glomerulus. Glomerular ECM has been shown to Background. Glomerulosclerosis is characterized by glomerular accumulation of extracellular matrix fol-consist of type IV collagen, laminin, heparan sulphate proteoglycan, fibronectin, and other proteins. lowing mesangial cell proliferation. The precise pathomechanism of glomerulosclerosis is still undetermined. Glomerular deposition of type IV collagen has been reported in human glomerular diseases [1] and experiPlatelet-derived growth factor (PDGF ) and basic fibroblast growth factor (b-FGF ) are known to be mental animal models [2]. Platelet-derived growth factor (PDGF ) has been shown to be a potent mitogen mitogenic for mesangial cells, and interferon c (IFN-c) is known to have an inhibitory effect on mesangial cell for mesangial cells in culture and is expressed in both experimental and human forms of glomerulonephritproliferation. We attempted to clarify the role of these cytokines on mesangial matrix production using cul-ides in which mesangial cell proliferation occurs [3][4][5][6].Basic fibroblast growth factor (b-FGF ) is also thought tured human fetal mesangial cells (HMC ). Methods. HMC were incubated with these cytokines to be mitogenic for mesangial cells in culture [7], while inteferon c (IFN-c) is known to inhibit mesangial cell for 24-72 h and the levels of type IV collagen and TGF-b in the cell supernatants were measured by proliferation [8]. Mesangial cell proliferation may precede or be associated with ECM accumulation in enzyme immunoassay. Results. PDGF, b-FGF, and IFN-c stimulated type mesangial proliferative glomerulonephritis. However, it is still undetermined how PDGF, b-FGF, and IFN-IV collagen production by HMC in a dose-and timedependent manner. The anti-TGF-b neutralizing anti-c influence the glomerular accumulation of ECM in glomerulonephritis. Transforming growth factor b body clearly inhibited their stimulatory effect on type IV collagen production. PDGF and b-FGF also stimu-( TGF-b) is a multifunctional regulatory protein and is known to participate in the glomerular accumulation lated TGF-b production by HMC in a dose-dependent manner, although IFN-c did not.of ECM in glomerulonephritis. Therefore we studied the production of type IV collagen and TGF-b by Conclusion. PDGF, b-FGF, and IFN-c stimulate type IV collagen production in cultured HMC via a TGF-cultured fetal mesangial cells (HMC ) incubated with PDGF, b-FGF, and IFN-c. We also examined the b-dependent mechanism.effect of anti-TGF-b antibody to clarify the role of TGF-b in type IV collagen production stimulated with

We found that thrombin stimulates FN production in PTEC without causing matrix degradation, an effect that may contribute to the formation of tubulointerstitial fibrosis associated with glomerular disease. The stimulatory effect of thrombin on FN production in PTEC is, at least in part, mediated by TGF-beta.

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