Urinary Transforming Growth Factor-beta 1 as a marker of response to immunosuppressive treatment, in patients with crescentic nephritis

Abstract

Abstract Background Crescentic nephritis is characterized by formation of cellular crescents that soon become fibrotic and result in irreversible damage, unless an effective immunosuppressive therapy is rapidly commenced. TGF-β1 is involved in the development of crescents through various pathways. The aim of this study was to identify whether the determination of urinary TGF-β1 levels in patients with crescentic nephritis could be used as a marker of response to treatment. Methods Fifteen patients with crescentic nephritis were included in the study. The renal expression of TGF-β1 was estimated in biopsy sections by immunohistochemistry and urinary TGF-β1 levels were determined by quantitative sandwich enzyme immunoassay (EIA). TGF-β1 levels were determined at the time of renal biopsy, before the initiation of immunosuppressive treatment (corticosteroids, cyclophosphamide and plasma exchange). Twelve patients with other types of proliferative glomerulonephritis and ten healthy subjects were used as controls. Results Improvement of renal function with immunosuppressive therapy was observed in 6 and stabilization in 4 patients (serum creatinine from 3.2 ± 1.5 to 1.4 ± 0.1 mg/dl and from 4.4 ± 1.2 to 4.1 ± 0.6 mg/dl, respectively). In 5 patients, with severe impairment of renal function who started on dialysis, no improvement was noted. The main histological feature differentiating these 5 patients from others with improved or stabilized renal function was the percentage patients with poor response to treatment were the percentage of glomeruli with crescents and the presence of ruptured Bowman's capsule and glomerular necrosis. Urinary TGF-β1 levels were significantly higher in patients who showed no improvement of renal function with immunosuppressive therapy (930 ± 126 ng/24 h vs. 376 ± 84 ng/24 h, p < 0.01). TGF-β1 was identified in crescents and tubular epithelial cells, whereas a significant correlation of TGF-β1 immunostaining with the presence of fibrocellular cresents was observed (r = 0.531, p < 0,05). Conclusion Increased TGF-β1 renal expression and urinary excretion that is related to the response to immunosuppressive therapy was observed in patients with crescentic nephritis. Evaluation of urinary TGF-β1 levels may be proved a useful marker of clinical outcome in patients with crescentic nephritis.