Clinical-pathological and immunohistochemical evaluations of cardiac lesions in cats with chronic kidney disease

Abstract

Chronic kidney disease (CKD) is characterized by irreversible morphostructural lesions that can progressively evolve to chronic renal insufficiency and kidney failure. It is known that the heart and kidneys are closely related, and that communication between these organs occurs through a variety of pathways; subtle physiological changes in one of them are compensated by the other. Histopathological cardiac evaluation through routine staining presents a limitation to identify specific or discreet lesions in the cardiomyocytes. This study aimed to evaluate serum troponin levels in cats with CKD, associated with clinical and pathological findings, as well as to correlate the morphostructural cardiac lesions to determine their distribution through macroscopic and histological assessments and anti-cardiac troponin C (cTnC) immunohistochemistry (IHC). To this end, 20 cats (18 diagnosed with CKD and two controls) were selected. Anti-human cTnC IHC was conducted after necropsy and separation in eight regions of each collected heart. Heart fragments from two cats without CKD were used as controls. The anti-human cTnC antibody is useful in detecting cardiac lesions and has shown decreased expression in cardiomyocytes of cats with CKD. Serum troponin was above the reference values in 11/18 (61.11%) animals and decreased expression for the cTnC antibody was observed in individual cardiomyocytes in 9/18 (50%) animals. It was verified that the number of regions with decreased expression for the cTnC antibody in cardiomyocytes is significantly correlated with serum troponin. The anti-human cTnC antibody has been found effective in detecting cardiac lesions and has shown decreased expression in the cardiomyocytes of cats with CKD. Correlation was observed between increased serum cTnI and loss of immunoreactivity at anti-cTnC antibody IHC in cats with CKD, which proves damage to cardiomyocytes secondary to kidney disease.