| Research Abstract |
This study provided us a new experimental model of acute tubulointerstitial nephritis (TIN) using cationic antigen in mice. Cationic ovalbumin (c-OA, isoelectric point>10), when injected intravenously (I.v.) via tha tail vein, localized exclusively on the tubular basement membrane (TBM) and on the basement membrane of the Bowman's capsule of mice. In situ immune complex formation was induced on the TBM, but not on the glomerular basement membrane, by intravenous injection of rabbit anti-OA antibody 5 hours after antigen injection. An active model of TIN was established. One week after the last immunization with normal rabbit serum, 1mg of c-OA was injected I.v., followed 5 hours later by I.v. injection with 3.5 mg of rabbit anti-Oa 1gG. The lesion was characterized by enhanced expression of intercellular adhesion molecule (ICAM)-1 and major histocompatibility complex (MHC) class II molecules on the tubular epithelium, as well as on the peritubular capillaries and was associated with T
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lymphocytes-dominant inflammatory cell infiltration in the interstitium. In the next step, in vitro study was done in order to identify the cytokine, which influenced the phenotypic change (ICAM and MHC class II expression) of tubular epithelial cell (TEC). TEC was isolated from the mouse kidney and was stimulated by macrophage-derived cytoknes such as IL-1 β and TNF α or T lymphocyte-derived cytokine such as INF-r. Using flow cytometry, the phenotypic change of TEC was documented by INF-r, but not by as IL-1βor TNF α. A further in vitro study succeeded to show that the expression of MHC class II on the tubular epithelial cells (CONTINUE TO NEXT PAGE) together with super-antigen activated the rsting T lymphocytes. In the next step, the TIN mouse was analyzed by immunohistochemistry and in situ hybridization in order to know the cytokines, which play a role in the progression of TIN. A positive stain for MHC class II on the TEC, which was surrounded by a diffuse T cell and macrophage infiltation was seen in early phase of TIN. In contrast, a positive stain for vimentin on TEC, which were surrounded by TGF β1-and HSP 47-positive cell in αSMA-positive area in the later phase. TGF β1- and HSP 47-positive cells in the early phase included tubules, macrophages, interstitial cells, and endothelial cells, which may potentially impact on development of interstitial fibrosis. As shown above, we could have a global view on the interaction among tubules, interstitial cells and inflammatory cells in the progression of TIN. Less
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