A diagnostic study of bovine endometritis integrating cytological, histopathological assessments, and immunohistochemical localizations of interleukins

Endometritis significantly impairs cows' reproductive productivity, yet existing diagnostic practices lack the comprehensive accuracy required for precise diagnosis and pathological staging. This study aimed to evaluate and validate a combined diagnostic model integrating cytology, histopathology, and immunohistochemistry to diagnose and categorize the severity of endometritis precisely. Post-mortem endometrial samples (n=76) were collected from slaughtered cows and were subjected to endometrial cytobrush and biopsy sampling. Cytobrush smears were quantified for polymorphonuclear leukocyte (PMNL) and classified according to recognized thresholds: mild (≤5%), moderate (>5-15%), and high (>15%). The severity of endometrial inflammation was categorized into mild, acute, and chronic. Immunohistochemistry was utilized to determine the localization and expression patterns of interleukins (IL-8, IL-1β, and IL-10). The moderate threshold of PMNL count revealed a significantly higher rate (51.3%) than the mild and high groups, demonstrating a correlation with the histopathological assessment. Histopathological evaluation identified chronic inflammation as the most prevalent pathological lesion (47.4%). Receiver operating characteristic curve analysis supported the diagnostic efficacy of PMNL cut-off values, exhibiting high sensitivity and specificity for differentiating inflammation severity. Immunohistochemistry revealed differential localization and expression patterns of utilized inflammatory interleukins correlating with endometritis severity. Specifically, elevated expression intensity of IL-8 and IL-1β was consistently associated with severe inflammation, whereas a stronger expression of IL-10 predominated in chronic endometritis. In conclusion, the integration of cytobrush, histopathology, and immunohistochemistry significantly enhances the diagnostic accuracy and staging. The differential interleukin expression serves as a promising molecular biomarker, presenting novel insights into the complicated inflammatory dynamics underlying endometritis progression.