Expression of α-smooth muscle actin and fibronectin in tubulointerstitial lesions of cats with chronic renal failure

Objective—To examine renal expression of α-smooth muscle actin (α-SMA) and fibronectin in cats with tubulointerstitial nephritis (TIN) for use in predicting progression to renal fibrosis. Animals—19 cats with TIN and 9 cats without nephritis. Procedure—Serum creatinine and BUN concentrations were measured. Indices for glomerular extra-cellular matrix (ECM), tubular injury (TI), and fibronectin were determined in renal specimens to quantify the extent of injury and fibrotic lesions. Expression of α-SMA in renal tissue was immunohistochemically detected, and correlations were evaluated between the α-SMA index and other histologic and clinical variables. Results—The α-SMA index in tubulointerstitial areas (1.63 ± 0.78) was significantly higher in cats with TIN, especially in the periglomerular and peritubular areas, than in cats without nephritis (0.20 ± 0.14). The α-SMA index was significantly associated with the TI index (r 2 = 0.70), fibronectin index (r 2 = 0.95), BUN concentration (r 2 = 0.64), and seru...