Alpha-enolase staining patterns in the renal tissues of cats with and without chronic kidney disease

Renal α-enolase has variable expression in inflammatory and neoplastic diseases. Therefore, in order to define the distribution of α-enolase in renal tissues of cats, an immunohistochemistry assay was validated and described here. Tissues from 29 cats with IRIS Stage 2-4 CKD, 8 control cats < 2 years of age, and 4 control cats> 10 years of age were assessed. Interstitial nephritis was the predominant histopathological finding in the CKD group. The control cats < 2 years of age had moderate α-enolase immunoreactivity in tubular epithelium but staining was absent to mild in glomeruli. In contrast, α-enolase was moderate to high in tubular epithelium and glomeruli in control cats > 10 years of age. In cats with CKD, α-enolase was decreased in tubules that were degenerative or atrophic, similar to normal tubules in control groups, and moderate to high in glomeruli. When compared between the study groups, the results suggest that alpha-enolase decreases in damaged tubules and increases in the glomeruli of older cats prior to the development of detectable CKD. Further studies will be required to determine whether these findings relate to the pathogenesis or could be used in the diagnosis of feline CKD.