Production and degradation of extracellular matrix in reversible glomerular lesions in rat model of habu snake venom-induced glomerulonephritis

We investigated the mechanism of development and repair process of glomerular injury in a rat model of habu snake (Trimeresurus flavoviridis) venom (HSV)-induced glomerulonephritis. Glomerulonephritis was induced in rats by intravenously injecting HSV at 3 mg/kg. Renal tissue was isolated and subjected to immunohistochemical analysis for expression levels of type IV collagen, heat shock protein 47 (HSP47), transforming growth factor-beta (TGF-beta), and matrix metalloproteinase-3 (MMP-3), as well as its transcription factor Ets-1. Expression levels of HSP47, TGF-beta, and type IV collagen began to increase in the mesangial area starting from day 14 and peaked on day 21, followed by a gradual decrease. Expression levels of MMP-3 and Ets-1 started to increase coinciding with peak production of mesangial matrix on day 21, peaking on day 35, followed by gradual decrease. Expression of MMP-3 and Ets-1 persisted until day 63, whereas that of HSP47 and type IV collagen returned to baseline level at this time point. Time-course changes of extracellular matrix (ECM) accumulation in glomeruli in the HSV-induced glomerulonephritis model were correlated with those of factors involved in both ECM production and degradation systems. Continued expression of factors in the degradation system seems particularly important for the repair process. These findings might lead to new therapies that prevent and repair glomerular injury.