Expression of interleukins 6 and 10 and population of inflammatory cells in the equine endometrium: diagnostic implications

Abstract

Endometritis consists of an acute or chronic inflammatory process involving the endometrium and together with endometrosis constitute the main causes of infertility in mares. The aim of this study was to associate the histopathological findings with the immunohistochemical markers interleukins 6 (IL-6) and 10 (IL-10) to evaluate the inflammatory changes and progression of uterine tissue lesions of mares in the diestrus phase and their diagnostic implications. Twelve crossbred cyclic mares were used for endometrial biopsy collection. Samples were collected in the diestrus period (6 ± 1 day after ovulation) without previous artificial insemination. In the histopathological analysis the samples were classified according to the type and intensity of inflammation, alterations regarding endometrial fibrosis and biopsy categories (I, IIA, IIB and III). In the immunohistochemical analysis, the markers of IL-6 and IL-10 were evaluated by scores (0, 2, 4, 6) according to the intensity of the immunostaining and inflammatory cells (CD-3, CD-20, CD-68 and MPO antibodies) and were counted according to the number of cells immunostained in brown, in ten random fields. An association (p ≤ 0.05) occurred between low score (2) for IL-6 in the endometrial glandular area and moderate fibrotic nets; and between high scores (4 and 6) for IL-10 in sub-epithelial connective tissue and moderate periglandular fibrosis. In conclusion, immunohistochemical analysis demonstrated an association between interleukins and inflammatory cells with endometrial lesions. In addition, this research may be useful in the future to evaluate the progress of the inflammatory process, contributing to the adequate optimization of the reproductive management of the mares.