Significance of macrophage and cytokines in expression of stone matrix

Abstract

(BACKGROUND). Urinary calculus consists of inorganic substances as a major component and organic substances as a minor component. In this study, the organic substances playing an important role in the formation of calculus, such as osteopontin, calprotectin, macrophage and cytokines, are investigated for their significance in the calculus formation mechanism. (METHODS). Using renal tissues of rats having intraperitoneal glyoxylic acid-induced calculus, mode of the expression of osteopontin was examined by in situ hybridization method, immunohistological staining and northern blot method. Then human renal tissues obtained from the nephrectomy specimen conducted for a renal calculus were subjected to immunohistological staining by an enzyme antibody method using antibodies against osteopontin, calprotectin, macrophage and cytokines. (RESULTS). In rats, while the expression of osteopontin mRNA was observed in renal distal tubular cells, no expression was observed in glomerulus or renal interstitial tissues. The level of osteopontin mRNA expression in calculus forming rats was higher than in control rats by northern blot method. In human tissues, all of osteopontin, calprotectin, macrophage exhibited positive results in the renal distal tubular cells and in the calculus nucleus in the renal distal tubular cavity. Calprotectin and macrophage exhibited positive result also in the renal interstitial tissues. Cytokines exhibited positive results for interleukin-1,6, tumor necrosis factor alpha and transforming growth factor beta. Cytokines exhibited positive results in the distal tubular cells. Negative results were observed for interleukin-2,4 and 5. (CONCLUSION). Based on the findings described above, it is concluded that accumulation of macrophage in the renal interstitial tissues takes place and then one type of cytokines sensitive to macrophage is secreted. Subsequently, in the renal distal tubular cells stimulated with macrophage and cytokines, the expression of osteopontin and calprotectin takes place, and these organic substances bind to calcium, whereby forming the calculus nucleus.