Expression of Toll-like receptors 2, 4 and 6 in different cell populations of the equine endometrium

• Published in: Veterinary immunology and immunopathology 2017-03, Vol.185, p.7-13
• Main Authors: Schöniger, Sandra, Gräfe, Hilke, Schoon, Heinz-Adolf
• Format: Article
• Language: English
• Subjects: Animals; Endometrium; Endometrium - metabolism; Endometrium - pathology; Equine; Female; Horses - metabolism; Immunohistochemistry; PCR; Toll-Like Receptor 2 - biosynthesis; Toll-Like Receptor 4 - biosynthesis; Toll-Like Receptor 6 - biosynthesis; Toll-like receptors; Uterine Diseases - metabolism; Uterine Diseases - pathology; Uterine Diseases - veterinary
• ISSN: 0165-2427; 1873-2534
• DOI: 10.1016/j.vetimm.2017.01.002

•Expression of TLRs 2, 4 and 6 within the healthy and diseased equine endometrium.•Immunostaining for these TLRs in epithelia, stromal cells, mast cells and vessels.•Immunosignal within the cytoplasm of these cells and in epithelia also intranuclear.•Marked differences in regard to their cellular expression between individual mares.•Results as prerequisite for studies into their impact on disease pathogenesis. Subfertility in mares is mainly caused by endometrial diseases. Alterations of Toll-like receptors (TLRs) are associated with endometrial disorders in women. This study investigated TLRs 2, 4 and 6 in the equine endometrium. Endometria of 21 mares were examined by histology, PCR and immunohistochemistry. Tissues from 2 mares were considered normal. The remaining showed endometritis, endometrosis and/or angiosclerosis. TLRs 2, 4 and 6 were expressed as transcripts and proteins in all endometria. Immunohistochemistry detected TLRs 2, 4 and 6 in mast cells, luminal and glandular epithelial cells, stromal cells, endothelia, vascular smooth muscle and/or inflammatory cells. Between examined endometria numbers of immunopositive epithelial cells varied considerably; TLRs were located in their cytoplasm and/or the nucleus. All other cell types displayed a cytoplasmic staining. Results indicate a complex and cell-type-specific modulation of TLRs 2, 4 and 6 in the equine endometrium. The lack of a detectable association between a particular disease and a distinct cellular expression may be explained by the often combined presence of several factors with a possible influence on TLRs. This study expands the basic knowledge on equine endometrial immunity and will assist to uncover if immunological alterations contribute to uterine diseases of mares.