| Research Abstract |
Urinary stones contain 1-5% protein, and many reports have suggested the importance of proteins in stone formation. We cloned and sequenced the cDNA encoding osteopontin (OPN) and calprotectin (CPT), important soluble stone protein components of calcium oxalate stone proteins extracted with 0.1M EDTA.Thus we found strong expression of OPN mRNA by distal tubular cells in the kidneys of stone-forming rats. Osteopontin can facilitate adhesion of many cell types, including smooth muscle cells, aortic endothelial cells, and macrophage-like cells. In atherosclerosis, macrophages are detected around mineralization and express osteopontin. We detected the emphasized expression of OPN and CPT at renal epithelial cells of urolithiasis patients and calcium oxalate stone-formation model rats and detected the existence of OPN and CPT in the stones including calcium. In stone-formation rats, macrophages migrate to the stroma around epithelial cells, going ahead of both OPN emphasis and stone-formation. The expression of immunological cytokines, IL-1, IL-6, TNFalpha and TGFbeta, go ahead of OPN emphasis. These suggest that OPN,macrophages and cytokines play a important role in the initiation of stone foromation. We showed bisphosphonate which use as the medicine to osteoporosis, Kampo medicine, Takusya, and citrate suppress the expression of OPN.Furthermore we transfected the expression vector of the anitisense to OPN mRNA into rat kidney cells to suppress the expression of OPN.We showed the cells transfected with antisense expression vector inhibited calcium oxalate monohydrate adhesion to cells. These suggest the important role of OPN in stone-formation.
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