Detection of the pan neuronal marker PGP9.5 by immuno-histochemistry and quantitative PCR in eutopic endometrium from women with and without endometriosis

Distribution of Nerve Fibers in Abdominal Wall Endometriosis and Their Clinical Significance

Objective

This study aimed to explore the distribution of nerve fibers in abdominal wall endometriosis (AWE) and discern their association with pain.

Methods

A retrospective case-control study was conducted. The cases comprised 30 patients diagnosed with AWE, while the control group consisted of 17 patients who had undergone laparotomy without any history of endometriosis. We analyzed clinical characteristics and examined the innervation patterns in samples using stains for S-100, neuron-specific enolase (NSE), protein gene product 9.5 (PGP9.5), neurofilament (NF), and substance P (SP) antibodies.

Results

There was a notable increase in the density of S-100, NSE and PGP9.5 immunoreactive nerve fibers and a higher proportion of SP positivity in AWE lesions compared to standard abdominal wall scars (p < 0.05). However, there were no significant differences in the density or proportion of NF-immunoreactive nerve fibers between the cases and the controls. Moreover, no statistically significant correlation was observed between the density of S-100, NSE, PGP9.5, NF, or SP-positive nerve fibers and pain scores.

Conclusion

This study demonstrated an increased immunoreactive nerve fiber density located in AWE lesions compared to normal abdominal wall scars. Further high-quality studies are needed to investigate the mechanisms responsible for pain in women with endometriosis.

Dysmenorrhea in patients with adenomyosis: A clinical and demographic study

OBJECTIVE

To identify the risk factors associated with dysmenorrhea in adenomyosis and to discuss the potential hormone-based understanding of pain mechanisms.

STUDY DESIGN

Adenomyosis patients with mild or no dysmenorrhea (n = 40, Group 1) and moderate-to-severe dysmenorrhea (n = 80, Group 2) were recruited. Charts of all patients were recorded. An immunohistochemistry (IHC) analysis was performed to detect the cellular levels of estrogen receptor-α (ER-α), estrogen receptor-β (ER-β), gonadotropin-releasing hormone receptor (GnRH-R), and neurofilaments (NFs) in 60 cases.

RESULTS

A history of cesarean section (CS) was positively related to the degree of dysmenorrhea in adenomyosis (OR (95 % CI): 4.397 (1.371-14.104)). The ER-α levels in the eutopic endometrium (EUE) of Group 2 were higher than those in the ectopic endometrium (ECE) of Group 1. Group 2 had higher NF levels in the ECE than in the EUE.

CONCLUSION

A history of CS is a risk factor for adenomyosis with moderate-to-severe dysmenorrhea. For patients with adenomyosis, high ER-α levels in the EUE and high NF levels in the ECE may be related to moderate-to-severe dysmenorrhea. These hormone-based mechanisms may contribute to our understanding of the pathogenesis of dysmenorrhea in adenomyosis.

Pelvic organ cross-talk: A new paradigm for endometriosis-related pelvic pain?

Endometriosis patients often complain about pelvic and abdominal pain with varying bowel and bladder symptoms unrelated to the location and extent of the disease. The pathophysiology can be multifactorial, but one possibility is that pelvic organ cross-talk may play a role. The aim of this review was to evaluate the scientific support for this hypothesis. A search was performed in PubMed to identify relevant experimental and clinical studies. Data achieved in animal models and clinical evidence suggest that endometriosis-related pain may implicate interactions between pelvic structures like the urinary tract, the bowel and the vagina, mediated by the autonomous nervous system. Such pelvic organ cross-talk with involvement of nerve fibre outgrowth into endometriosis lesions, peripheral sensitisation and convergence of afferent nerve fibres could be an explanation for the varying pain problems in endometriosis, but the precise mechanisms are still poorly understood. Some patients with chronic pelvic pain, including those with endometriosis, also seem to have a more general somatic, musculoskeletal hyperalgesia, indicating a potential viscero-somatic convergence. This might be due to continuous nociceptive input to the brain, resulting in changes in brain structures and finally leading to central sensitisation. Thus, pelvic organ cross-talk seems to represent a new paradigm for endometriosis-related pain with novel possibilities for the development of therapeutic strategies.

Assessment of biomarkers in women with endometriosis-associated pain using the ENG contraceptive implant or the 52 mg LNG-IUS: a non-inferiority randomised clinical trial

OBJECTIVE

The aim of the study was to assess the serum levels of the following biomarkers in women with endometriosis-associated pelvic pain before and after six months of using the etonogestrel (ENG) contraceptive implant or the 52 mg levonorgestrel-releasing intrauterine system (LNG-IUS): cancer antigen (CA)-125, cluster of differentiation (CD) 23 and endometrial nerve fibre density.

METHODS

The study was conducted at the Department of Obstetrics and Gynaecology, University of Campinas Medical School, Brazil. A total of 103 women with endometriosis-associated pain diagnosed by surgery, transvaginal ultrasound and/or magnetic resonance imaging were included. Endometrial nerve fibre density and serum levels of CA-125 and soluble CD23 were assessed before and after six months of using the allocated method and were correlated to 10 cm visual analogue scale (VAS) scores for non-cyclical pelvic pain and dysmenorrhoea.

RESULTS

Both contraceptive methods significantly reduced concentrations of serum soluble CD23 and endometrial nerve fibre density (p < .001); however, CA-125 was significantly reduced only among users of the ENG implant (p < .05). No correlation was observed between reduction of biomarkers and improvement of VAS pain and dysmenorrhoea scores. No differences were observed between the ENG implant and the LNG-IUS.

CONCLUSION

Both progestin-only contraceptives significantly reduced two out of the three biomarkers evaluated. These two biomarkers could, therefore, be used as surrogate markers to follow up medical treatment of endometriosis-associated pain.

PKCβII-induced upregulation of PGP9.5 and VEGF in postoperative persistent pain in rats

Purpose

Postoperative pain is a common clinical problem. In this study, we aimed to investigate the role of protein kinase C βII (PKCβII) in the progression of postoperative pain following skin/muscle incision and retraction (SMIR) surgery.

Materials and methods

SMIR postoperative pain model was established in rats, akin to a clinical procedure. The expression level and location of p-PKCβII were observed in dorsal root ganglion (DRG) or spinal cord from SMIR-operated rats by Western blotting and immunofluorescence. In addition, the effects of PKCβII on the expression of protein gene product 9.5 (PGP9.5) or vascular endothelial growth factor (VEGF) were assessed by using pharmacological activator and inhibitor of PKCβII. Moreover, mechanical withdrawal threshold (MWT) was assessed before or after SMIR-operated rats were treated with inhibitor or activator of PKCβII.

Results

The expression of PKCβII in DRG and spinal cord was significantly increased after SMIR surgery (P < 0.001, P < 0.01) and expression of PKCβII was located in the neurons of the spinal cord, and magnocellular neurons, non-peptide neurons, and peptide neurons in DRG. Besides, compared with skin/muscle incision group, retraction caused a marked increase in the expression of PKCβII and a significant decrease of MWT (P < 0.001, P < 0.05). The activator of PKCβII greatly increased the expression of PGP9.5 and VEGF (P < 0.05, P < 0.01) and enhanced MWT (P < 0.001), while inhibitor of PKCβII decreased the expression of PGP9.5 and VEGF and attenuated MWT (P < 0.05, P < 0.01, P < 0.001).

Conclusion

Activation of PKCβII signaling pathways might be an important mechanism in the progression of postoperative pain.

Reduced alternative splicing of estrogen receptor alpha in the endometrium of women with endometriosis

Endometriosis is a condition which involves the presence of uterine stroma and glands outside of the uterine cavity and represents one of the most prevalent disorders of the female reproductive tract. The key symptom of endometriosis is pain, including dysmenorrhea, deep dyspareunia, and chronic pelvic pain. As such, endometriosis has significant economic consequences within the healthcare system and can influence the daily quality of life in affected patients. However, the pathophysiology of this disease and the mechanisms in which this condition generates pain are very unclear. This study, involving 30 women with endometriosis and 28 controls without endometriosis, aimed to investigate relative levels of estrogen receptor alpha (ERα) splice variants in the endometrium of women with and without endometriosis and investigate potential links to the severity of pain. Wild type (wt)-ERα was dominantly expressed in human endometrium while the expression of ERα-del.4, ERα-del.7, and ERα-del.3,4 was significantly reduced in endometriosis patients compared with healthy patients (p < 0.05). Furthermore, the relative ratios of wtERα:ERα-del.4, and wtERα:ERα-del.3,4 were associated with the severity of pain in endometriosis patients (p < 0.05). Consequently, analyzing differences in the relative levels of four types of ERα splice variant in the endometrium of patients with endometriosis may help in the development of endometriosis-targeted treatment and the development of appropriate therapies.

Prostaglandin levels, vaginal innervation, and cyst innervation as peripheral contributors to endometriosis-associated vaginal hyperalgesia in rodents

Endometriosis is a painful condition characterized by growth of endometrial cysts outside the uterus. Here, we tested the hypothesis that peripheral innervation and prostaglandin levels contribute to endometriosis-associated pain. Female Sprague-Dawley rats (n = 16) were surgically instrumented by transplanting uterine tissue onto mesenteric arteries within the peritoneal cavity to create a model of endometriosis which forms extra-uterine endometrial cysts and vaginal hyperalgesia. Our results describe a significant positive correlation between endometriosis-induced vaginal hyperalgesia and cyst innervation density (sensory, r = 0.70, p = 0.003; sympathetic, r = 0.55, p = 0.03), vaginal canal sympathetic innervation density (r = 0.80, p = 0.003), and peritoneal fluid levels of the prostaglandins PGE2 (r = 0.65, p = 0.01) and PGF2α (r = 0.63, p = 0.02). These results support the involvement of cyst innervation and prostaglandins in endometriosis-associated pain. We also describe how sympathetic innervation density of the vaginal canal is an important predictor of vaginal hyperalgesia.

Nerve fibers and endometriotic lesions: partners in crime in inflicting pains in women with endometriosis

One of major objectives in treating endometriosis is to alleviate pain since dysmenorrhea and other types of pain top the list of complaints from women with endometriosis who seek medical attention. Indeed, endometriosis-associated pain (EAP) is the most debilitating of the disease that negatively impacts on the quality of life in affected women, contributing significantly to the burden of disease and adding to the substantial personal and societal costs. Unfortunately, the mechanisms underlying the EAP are still poorly understood. In the last two decades, one active research field in endometriosis is the investigation on the distribution and genesis of nerve fibers in eutopic and ectopic endometrium, and the attempt to use endometrial nerve fiber density for diagnostic purpose. Since EAP presumably starts with the terminal sensory nerves, in or around endometriotic lesions, that transduce noxious mediators to the central nervous system (CNS) which ultimately perceives pain, this field of research holds the promise to elucidate the molecular mechanisms underlying the EAP, thus opening new avenues for novel diagnostics and therapeutics. In this review, we shall first briefly provide some basic facts on nerve fibers, and then provide an overview of some major findings in this filed while also note some conflicting results and expose areas in need of further research. We point out that since recently accumulated evidence suggests that endometriotic lesions are wounds undergoing repeated tissue injury and repair, the relationship between endometriotic lesions and nerve fibers is not simply unidirectional, i.e. lesions promote hyperinnervations. Rather, it is bidirectional, i.e. endometriotic lesions and nerve fibers engage active cross-talks, resulting in the development of endometriosis and pain. That is, nerve fibers and endometriotic lesions are actually partners in crime in inflicting pains in women with endometriosis, aided and abetted possibly by other culprits, some yet to be identified. We provide a list of possible perpetrators likely to be involved in this crime. Finally, we discuss possible implications when viewing the relationship from this vista.