Evaluation of Bcl-2 as a marker for prediction of Chronic Kidney disease in cats

Abstract

Chronic kidney disease (CKD) is a common disease in geriatric cats. Bcl-2 implicates kidney disease through apoptosis and fibrosis. This study aims to compare the Bcl-2 levels between CKD and clinically healthy age-matched cats, to determine the correlation among the Bcl-2 levels, signalment, and blood parameters of cats with CKD, and to determine Bcl-2 in kidney tissues of CKD cats in both quantitative and qualitative aspect by immunohistochemistry technique. Twenty-four CKD and eleven clinically healthy age-matched cats visiting the Small Animal Hospital, Faculty of Veterinary Medicine, Chiang Mai University during 2019 to 2020 were measured circulating levels of Bcl-2 by immunoassay. Immunohistochemistry was performed to determine Bcl-2 expression in 17 renal tissues of cats that died from CKD. The Bcl-2 immunohistochemical intensity was graded in each glomerulus and tubulointerstitium. The Bcl-2 levels between groups were compared using a general linear model (GLM). The correlations among the circulating Bcl-2, signalment, and blood parameters were determined using Pearson correlation. The association between the survival time of CKD cats and potential variables was investigated using the Cox hazard model and KaplanMeier survival analysis. The circulating Bcl-2 of CKD cats was significantly lower than that in clinically healthy age-matched cats (P = 0.034). From principal component analysis (PCA), circulating Bcl-2 can distinguish CKD and healthy cats. The CKD severity was significantly positively correlated with leukocytosis but negatively correlated with anemia and body weight. The circulating Bcl-2 (P < 0.01) and severity of CKD (P = 0.02) were significantly associated with the survival time of cats with CKD. The area under the curve (AUC) of Bcl-2 for detection of CKD was 0.723, indicating acceptable discrimination. Bcl-2 protein weakly expressed on renal tissues of cats with CKD. Bcl-2 concentration decrease with decreasing survival time of cats with CKD. Bcl2 may be useful for the diagnosis of feline CKD.