Tamaki K, Okuda S, Miyazono K, Nakayama M, Fujishima M
Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Lab Invest. 1995 Jul;73(1):81-9.
A progressive increase in latent transforming growth factor-beta (TGF-beta) secretion from diseased tissue was revealed in our previous work using adriamycin (ADR)-nephropathy (Kidney Int 45:525-36, 1994). Latent TGF-beta is composed of mature TGF-beta and latency-associated peptide (LAP) with or without latent TGF-beta-binding protein (LTBP). LTBP has been reported to contribute to either matrix-association or activation of latent TGF-beta. LTBP also seems to play a key role in the renal lesions of this model. The present study was designed to show the secretion of latent TGF-beta with LTBP and the location of LTBP in renal tissue in ADR-nephropathy.
The renal cortical tissue specimens were sampled at Weeks 4, 8, and 16 after the injection of ADR or saline (control) for cortical tissue culture and immunohistology. TGF-beta in the conditioned medium was assayed by immunoprecipitation and bioassay using mink lung epithelial cells. An immunohistochemical study was performed to examine the localization of LTBP, ED-1-positive macrophages, and extracellular matrix proteins including laminin, fibronectin, and collagen type I and type III.
A TGF-beta bioassay revealed a progressive increase in latent TGF-beta secretion from the cortex of diseased kidney. Free LTBP and LTBP-LAP complex with mature TGF-beta were immunoprecipitated by anti-LTBP Ab from the cortical culture medium. An immunohistochemical study using anti-LTBP Ab demonstrated that LTBP localization was restricted to the glomeruli and the arterioles in the control cortex. In the ADR rats at Week 4, a faint deposition of LTBP was observed in the interstitium around the glomeruli. At Week 8 or 16, LTBP was accumulated in the sclerosing glomeruli or fibrous interstitium, where ECM proteins and infiltrating ED-1-positive macrophages were intensely located.
Our results indicated that latent TGF-beta with LTBP was localized in association with the extracellular matrix in the sclerotic and fibrotic tissue in this model. Matrix-associated latent TGF-beta with LTBP may thus play an important role in the progressive process of glomerulosclerosis and interstitial fibrosis in ADR-nephropathy.
在我们之前使用阿霉素（ADR）诱导的肾病模型的研究中（《肾脏国际》45:525 - 36, 1994），发现患病组织中潜伏转化生长因子 -β（TGF -β）的分泌呈渐进性增加。潜伏TGF -β由成熟TGF -β和潜伏相关肽（LAP）组成，可能还结合有潜伏TGF -β结合蛋白（LTBP）。据报道，LTBP有助于潜伏TGF -β与基质结合或激活。LTBP似乎在该模型的肾脏病变中也起关键作用。本研究旨在揭示ADR肾病中与LTBP结合的潜伏TGF -β的分泌情况以及LTBP在肾组织中的定位。
在注射ADR或生理盐水（对照）后的第4、8和16周采集肾皮质组织标本，用于皮质组织培养和免疫组织学研究。通过免疫沉淀和使用貂肺上皮细胞的生物测定法检测条件培养基中的TGF -β。进行免疫组织化学研究以检查LTBP、ED -1阳性巨噬细胞以及包括层粘连蛋白、纤连蛋白、I型和III型胶原蛋白在内的细胞外基质蛋白的定位。
TGF -β生物测定显示患病肾脏皮质中潜伏TGF -β的分泌呈渐进性增加。游离LTBP以及与成熟TGF -β结合的LTBP - LAP复合物可被抗LTBP抗体从皮质培养基中免疫沉淀出来。使用抗LTBP抗体进行的免疫组织化学研究表明，在对照皮质中，LTBP的定位仅限于肾小球和小动脉。在第4周的ADR大鼠中，在肾小球周围的间质中观察到LTBP有微弱沉积。在第8周或16周时，LTBP积聚在硬化的肾小球或纤维间质中，而这些部位细胞外基质蛋白和浸润的ED -1阳性巨噬细胞也大量存在。
我们的结果表明，在该模型中，与LTBP结合的潜伏TGF -β定位于硬化和纤维化组织中的细胞外基质。因此，与LTBP结合的与基质相关的潜伏TGF -β可能在ADR肾病肾小球硬化和间质纤维化的进展过程中起重要作用。
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