Expression of decorin, biglycan, and collagen type I in human renal fibrosing disease

Background. The extracellular matrix proteoglycans decorin and biglycan may have a pathogenic role in renal fibrosing disease via regulation of the ac tivity of growth factors, such as transforming growth factor-beta, and effe cts on collagen type I fibrillogenesis. The expression of decorin and bigly can in human glomerular diseases characterized by mesangial sclerosis is un known. Methods. Decorin, biglycan, and collagen type I were localized immunohistoc hemically in human renal biopsy cases of amyloidosis (N = 18), diabetic nep hropathy (N = 11), fibrillary glomerulonephritis (N = 5), immunotactoid glo merulopathy (N = 5), light-chain deposition disease (N = 4), idiopathic mes angial sclerosis (N = 4), and nephrosclerosis (N = 6), and in morphological ly normal tissues obtained from tumor nephrectomies (N = 8). Decorin and bi glycan mRNA synthesis was evaluated by in situ hybridization. Results. Decorin and biglycan protein were not identified in normal glomeru li. Decorin accumulated in amyloid deposits, but not in deposits of fibrill ary glomerulonephritis or immunotactoid glomerulopathy. Biglycan weakly acc umulated in amyloid deposits, and both decorin and biglycan weakly stained mesangial nodules in cases of morphologically advanced light-chain depositi on disease and diabetic nephropathy. In all analyzed cases, irrespective of the underlying disease, decorin and biglycan accumulated in glomeruli in a reas of fibrous organization of the urinary space and in areas of tubuloint erstitial fibrosis. Biglycan, but not decorin, accumulated in the neointima of arteriosclerotic blood vessels. Decorin and biglycan mRNA synthesis was detected at sites of proteoglycan accumulation in glomeruli, interstitium, and neointima. Collagen type I colocalized with decorin and biglycan depos its. Conclusions, Differences in extracellular matrix proteoglycan composition m ay be diagnostically useful in distinguishing morphologically similar disea ses. Distinct patterns of proteoglycan expression may be related to modulat ion of specific growth factor activity in different glomerular diseases.