TLR3 and TLR4 protein is localised to endometrial cells during the menstrual cycle. TLR3 protein staining in healthy late proliferative (LP) tissue was high in luminal and glandular tissue (A, brown precipitate) and lower in LP endometriotic tissue (B). Late secretory (LS) endometrium showed highly expressed TLR3 in the epithelium (C), but weakly in endometriosis (D). Intense staining of TLR4 proteins was shown in mid proliferative (MP) tissue (E). In late proliferative phase of endometriosis, TLR4 proteins were comparably lower (F). TLR4 protein was high in mid secretory (MS) normal endometrium (G), whereas it was decreased in endometriotic MS tissue (H). During the menstrual phase, both TLR3 (I) and TLR4 (J) were highly expressed. Co-immunostaining for TLR4 (green), CD14 (K, red) and CD163 (L, red) demonstrated that TLR4 proteins were expressed by CD14 positive dendritic cells and monocytes (K, yellow) and by CD163 positive macrophages (L, yellow). Localisation of TLR4 to immune cells is marked by a black arrow (J) and by white arrows (K, L).
Allhorn et al. Reproductive Biology and Endocrinology 2008 6:40