Matrix-associated latent TGF-beta with latent TGF-beta binding protein in the progressive process in adriamycin-induced nephropathy.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Tamaki
K
K
Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Okuda
S
S
Miyazono
K
K
Nakayama
M
M
Fujishima
M
M
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis*; D004317:Doxorubicin / Q000633:toxicity*; D016326:Extracellular Matrix Proteins / Q000032:analysis*; D005455:Fluorescent Antibody Technique; D005923:Glomerulosclerosis, Focal Segmental / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D007668:Kidney / Q000737:chemistry; D007674:Kidney Diseases / Q000139:chemically induced / Q000473:pathology*; D053779:Latent TGF-beta Binding Proteins; D008264:Macrophages / Q000737:chemistry; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D016212:Transforming Growth Factor beta / Q000032:analysis* / Q000235:genetics
D002352:Carrier Proteins; D016326:Extracellular Matrix Proteins; D047908:Intracellular Signaling Peptides and Proteins; D053779:Latent TGF-beta Binding Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D004317:Doxorubicin