KI-67 Immunohistochemical Expression in Lung Tissue of Rats under Chronic Renal Failure

Abstract Chronic kidney disease (CKD) is associated with systemic complications, including pulmonary alterations due to kidney–lung crosstalk. This study evaluates Ki-67 immunohistochemical expression in rat lung tissue to assess cellular proliferative activity under experimental chronic renal failure (CRF) conditions, considering age-related variations. Outbred male rats (n = 150, aged 6, 9, and 12 months) were divided into control and experimental groups. CRF was induced via repeated intramuscular injections of 50% glycerol (0.5 mL twice weekly for 1 month). Alveolar lung tissues were fixed, sectioned, and stained for Ki-67 using the 3,3′-Diaminobenzidine method. Quantitative analysis was performed with QuPath software (v0.4.0) to calculate proliferative indices. Data were analyzed using two-way ANOVA with post-hoc tests (p <0.05). In controls, Ki-67 proliferative indices declined with age: 55.86% at 6 months, 52.32% at 9 months, and 23.44% at 12 months. Under CRF, indices were significantly suppressed: 21.75, 11.06, and 2.32%, respectively (p <0.01 vs. controls), indicating impaired cellular renewal. Experimental CRF exacerbates age-dependent reductions in lung cell proliferation, highlighting mechanisms, such as inflammation and hypoxia in pulmonary pathology. These findings underscore the need for targeted interventions in CKD-related lung dysfunction.