Morphological substrate and pathogenetic mechanisms of pelvic pain syndrome in endometriosis. Part II. Peripheral nerve tissue remodeling in the foci of endometriosis

Abstract

Endometriosis (EM) is morphologically characterized by the development of extrauterine endometrioid heterotopies, the major clinical symptoms of which is chronic pelvic pain, which is a serious problem not only in modern gynecology, but also in public health as a whole. to investigate neurogenic markers in the foci of EM of various sites and histological structure in women with and without pain syndrome. The investigation was performed using the operative material (resected segments of the intestine, bladder, rectovaginal septum, and small pelvic peritoneum) obtained from 52 women with an intraoperative and morphologically verified diagnosis of EM and (Group 1) and without (Group 2) pain syndrome. Immunohistochemical examination was made on paraffin-embedded tissue sections in accordance with the standard protocols, by using the antibodies: 1) anti-PGP 9.5 polyclonal rabbit antibodies; 2) mouse anti-human neurofilament (NF) protein monoclonal antibodies (Clone 2F1); 3) mouse anti-nerve growth factor (NGF) monoclonal antibodies; 4) monoclonal mouse anti-human NGF receptor p75 (NGFRp75) antibodies (Dako, Denmark). Our findings demonstrate differences in the expression of PGP 9.5, NFs, NGF, and NGFRp75 in the foci and adjacent tissue in painful and painless EM irrespective of the locations of heterotopies. The found molecular features are a manifestation of the remodeling of nerve fibers and nerve endings in the foci of EM and PGP9.5, NGF, and NGFRp75 give rise to nerve fiber neoformation and pain syndrome in EM. At the same time, the immunohistochemical phenotype of EM foci does not depend on their site and reflects the presence or absence of pain syndrome.