Expression of alpha-smooth muscle actin and fibronectin in tubulointerstitial lesions of cats with chronic renal failure.
OBJECTIVE
To examine renal expression of alpha-smooth muscle actin (alpha-SMA) and fibronectin in cats with tubulointerstitial nephritis (TIN) for use in predicting progression to renal fibrosis.


METHODS
19 cats with TIN and 9 cats without nephritis.


METHODS
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 alpha-SMA in renal tissue was immunohistochemically detected, and correlations were evaluated between the alpha-SMA index and other histologic and clinical variables.


RESULTS
The alpha-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 alpha-SMA index was significantly associated with the TI index (r2 = 0.70), fibronectin index (r2 = 0.95), BUN concentration (r = 0.64), and serum creatinine concentration () = 0.66). Of special interest was that interstitial alpha-SMA expression appeared evident in the kidneys at an early stage of TIN, prior to the onset of ECM deposition.


CONCLUSIONS
Analysis of results of histologic and clinical examinations revealed that interstitial alpha-SMA expression may have clinical importance and may be a useful early histologic marker for development of chronic renal failure in cats. An immunohistochemical examination for fibrogenic molecules (such as alpha-SMA expression) may provide fundamental information on the pathogenesis of early-stage renal disease and aid clinical management of cats with chronic renal failure, including TIN.
Sawashima
K
K
Institute of Experimental Animal Sciences, Osaka University Medical School, Suita-shi, Japan.
Mizuno
S
S
Mizuno-Horikawa
Y
Y
Shimada
A
A
Kudo
T
T
Kurosawa
T
T
D000199:Actins / Q000096:biosynthesis*; D000818:Animals; D002371:Cat Diseases / Q000378:metabolism*; D002415:Cats; D018450:Disease Progression; D005260:Female; D005353:Fibronectins / Q000096:biosynthesis*; D007668:Kidney / Q000473:pathology; D007676:Kidney Failure, Chronic / Q000473:pathology / Q000662:veterinary*; D007678:Kidney Glomerulus / Q000473:pathology; D008297:Male; D009395:Nephritis, Interstitial / Q000473:pathology / Q000662:veterinary*
D000199:Actins; D005353:Fibronectins