Innervation of ectopic endometrium in a rat model of endometriosis

Different types of small nerve fibers in eutopic endometrium and myometrium in women with endometriosis

OBJECTIVE

To investigate types of nerve fibers in endometrium and myometrium in women with endometriosis.

DESIGN

Laboratory study using human tissue.

SETTING

University-based laboratory.

PATIENT(S)

Women with and without endometriosis undergoing hysterectomy.

INTERVENTION(S)

Histologic sections of contiguous endometrial and myometrial tissues were prepared from hysterectomies performed on women with and without endometriosis.

MAIN OUTCOME MEASURE(S)

Types and density of nerve fibers in endometrium and myometrium in women with and without endometriosis were determined using a series of specific markers for neuronal structure and function: PGP9.5, NF, SP, CGRP, TH, VAChT, VIP, and NPY.

RESULT(S)

Nerve fibers stained with PGP9.5 and NF in endometrium and myometrium were significantly increased in women with endometriosis compared with women without endometriosis. Nerve fibers in the functional layer of endometrium in women with endometriosis were likely to be sensory C, a mixture of sensory A delta, sensory C, and adrenergic fibers in the basal layer of the endometrium, a mixture of sensory A delta, sensory C, adrenergic and cholinergic fibers in the myometrium.

CONCLUSION(S)

Increased nerve fiber density in endometrium and myometrium, and sensory C fibers and adrenergic nerve fibers in the endometrium in women with endometriosis may play an important role in the mechanisms of pain generation in this condition.

Targeting mast cells in endometriosis with janus kinase 3 inhibitor, JANEX-1

Endometriosis (EMS) is a chronic inflammatory disease of multifactorial etiology characterized by implantation and growth of endometrial glands and stroma outside the uterine cavity. EMS is a significant public health issue as it affects 15-20% of women in their reproductive age. Clinical symptoms may include pelvic pain, dysmenorrhea, dyspareunia, pelvic/abdominal masses, and infertility. Symptomatic treatments such as surgical resection and/or hormonal suppression of ovarian function and analgesics are not as effective as desired. Consequently, there is an enormous unmet need to develop effective medical therapy capable of preventing the occurrence and recurrence of EMS without undesirable side-effects. EMS-associated intra-abdominal bleeding episodes, local inflammation, adhesions, and i.p. immunologic dysfunction leads to pelvic nociception and pelvic pain. Increasing evidence supports the involvement of allergic-type inflammation in EMS. Invasion of mast cells, degranulation, and proliferation of interstitial component are observed in endometriotic lesions. Presence of activated and degranulating mast cells within the nerve structures can contribute to the development of pain and hyperalgesia by direct effects on primary nociceptive neurons. Therefore, treatments targeting endometrial mast cells may prove effective in preventing or alleviating EMS-associated symptoms. The Janus kinase 3 (JAK3) is abundantly expressed in mast cells and is required for the full expression of high-affinity IgE receptor-mediated mast cell inflammatory sequelae. JANEX-1/WHI-P131 is a rationally designed novel JAK3 inhibitor with potent anti-inflammatory activity in several cellular and in vivo animal models of inflammation, including mouse models of peritonitis, colitis, cellulitis, sunburn, and airway inflammation with favorable toxicity and pharmacokinetic profile. We hypothesize that JAK3 inhibitors, especially JANEX-1, may prove useful to prevent or alleviate the symptoms of EMS.

Growth-associated protein 43–positive sensory nerve fibers accompanied by immature vessels are located in or near peritoneal endometriotic lesions

OBJECTIVE

To investigate the topographical relationship between nerve fibers and peritoneal endometriotic lesions and to determine the origin of endometriosis-associated nerve fibers.

DESIGN

Retrospective nonrandomized study.

SETTING

University hospital endometriosis research center.

PATIENT(S)

Premenopausal women with histologically confirmed endometriosis were selected (n = 73). Peritoneal endometriotic lesions (n = 106) and unaffected peritoneal biopsies from patients without endometriosis (n = 9) were obtained.

INTERVENTION(S)

Immunohistochemistry was used to study the expression of neurofilament, substance P, smooth muscle actin, von Willebrand factor, growth-associated protein 43, nerve growth factor, and neutrophin-3 in peritoneal endometriotic lesion samples from women with symptomatic endometriosis and in peritoneal samples from women without endometriosis.

RESULT(S)

Pain-conducting substance-P-positive nerve fibers were found to be directly colocalized with human peritoneal endometriotic lesions in 74.5% of all cases. The endometriosis-associated nerve fibers are accompanied by immature blood vessels within the stroma. Nerve growth factor and neutrophin-3 are expressed by endometriotic cells. Growth-associated protein 43, a marker of neural outgrowth and regeneration, is expressed in endometriosis-associated nerve fibers but not in existing peritoneal nerves.

CONCLUSION(S)

The data provide the first evidence of direct contact between sensory nerve fibers and peritoneal endometriotic lesions. This implies that the fibers play an important role in the etiology of endometriosis-associated pelvic pain. Moreover, emerging evidence suggests that peritoneal endometriotic cells exhibit neurotrophic properties.

Neuroendocrine-immune disequilibrium and endometriosis: an interdisciplinary approach

Endometriosis, a chronic disease characterized by endometrial tissue located outside the uterine cavity, affects one fourth of young women and is associated with chronic pelvic pain and infertility. However, an in-depth understanding of the pathophysiology and effective treatment strategies of endometriosis is still largely elusive. Inadequate immune and neuroendocrine responses are significantly involved in the pathophysiology of endometriosis, and key findings are summarized in the present review. We discuss here the role of different immune mechanisms particularly adhesion molecules, proteinglycan interactions, and pro-angiogenic mediators in the development and progression of the disease. Finally, we introduce the concept of endometrial dissemination as result of a neuroendocrine-immune disequilibrium in response to high levels of perceived stress caused by cardinal clinical symptoms of endometriosis.

Influence of endometriosis on visceromotor and cardiovascular responses induced by vaginal distention in the rat

This study examined pseudoaffective responses elicited by vaginal distention in urethane-anesthetized rats, and tested hypotheses that responses would be increased by endometriosis (ENDO) and vary with the estrous cycle. Three groups were studied: ENDO, shamENDO, and Naive. ENDO was induced by autotransplanting small pieces of uterine horn (or, for shamENDO, fat) on mesenteric arteries. Ten weeks later, rats in proestrus or metestrus were anesthetized with urethane. Distendable latex balloons were inserted into the vaginal canal. While an increasing series of vaginal distentions was delivered, changes in electromyographic activity of the external oblique musculature (visceromotor response, VMR) and mean arterial pressure (pressor) responses were simultaneously measured. Vaginal distention produced VMR and pressor responses in all groups. These responses were significantly greater in ENDO than in the other groups, and greater in proestrus than metestrus. Although the overall amount of cystic tissue was greater in proestrous than metestrous rats, there was no correlation between these amounts and VMR or pressor responses. Acute spinalization (T8-T9) and bilateral pelvic, but not hypogastric, neurectomy attenuated both VMR and pressor responses, supporting the hypothesis that vaginal nociception involves suprathoracic spinal processing of information conveyed by the pelvic nerve. These effects on VMR and pressor responses to vaginal distention parallel behavioral escape responses to the same stimuli reported previously. The findings encourage continued use of VMR and pressor responses for further investigation of mechanisms underlying pain associated with ENDO and its potential treatment.

Differences in characteristics among 1,000 women with endometriosis based on extent of disease

OBJECTIVE

To determine the relationship between disease severity and patient characteristics in endometriosis.

DESIGN

Cross-sectional study of self-reported survey data.

SETTING

Academic research setting.

PATIENT(S)

One thousand women in the Oxford Endometriosis Gene (OXEGENE) study.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Participants were assigned to one of two groups with predominantly revised AFS stage I-II (group I, n = 423) or III-IV disease (group II, n = 517). Their characteristics were compared by disease extent.

RESULT(S)

Most participants were white (96%) and of reproductive age (81%). Women in group I were significantly younger on entering the study (39.9 +/- 0.5 vs. 44.5 +/- 0.4 years). Overall time to diagnosis did not differ between groups. The most common symptoms leading to a diagnosis were dysmenorrhea (79%) and pelvic pain (69%). In group II, subfertility (21.5% vs. 30.0%) and an ovarian mass (7.3% vs. 29.4%) more commonly led to a diagnosis, whereas dyspareunia (51.1% vs. 39.5%) was significantly more common in group I. Subfertility (41.5% vs. 53.4%) remained more common in group II throughout reproductive life, although birth and miscarriage rates were similar.

CONCLUSION(S)

Pelvic pain is common to all with endometriosis and those with more extensive disease report higher rates of subfertility. Remarkably, the time to diagnosis was similar among women.

Too soon, too late, too often, too seldom?

Many variables determine the appropriate timing of diagnostic laparoscopy for suspected endometriosis. When initial treatments fail to relieve pain attributed to endometriosis, more detailed assessment is often indicated rather than escalation of treatment.

Opposing viscerovisceral effects of surgically induced endometriosis and a control abdominal surgery on the rat bladder

OBJECTIVE

To determine, in rats, how surgically induced endometriosis and a control surgery (partial hysterectomy; sutures in abdomen) affects micturition thresholds and bladder vascular permeability.

DESIGN

Two animal studies, each performed in three groups of urethane-anesthetized rats in proestrus.

SETTING

Academic facility.

ANIMAL(S)

Seventy-three female, regularly cycling Sprague-Dawley rats studied in proestrus.

INTERVENTION(S)

Surgical induction of endometriosis (ENDO), surgical control (shamENDO), intact control (NoSURG), and bladder inflammation via intravesicular turpentine in all three groups.

MAIN OUTCOME MEASURE(S)

[1] Micturition thresholds (MTs; volume voiding thresholds), as measured by repetitive transurethral cystometry before and after bladder inflammation and [2] bladder inflammation, as assessed by extravasation of Evans Blue dye.

RESULT(S)

In the uninflamed bladder, MTs were significantly lower and dye extravasation significantly higher in ENDO rats than in shamENDO and NoSURG rats. Bladder inflammation increased dye extravasation in all groups and reduced MTs in the NoSURG and ENDO rats, but not in the shamENDO rats.

CONCLUSION(S)

Endometriosis reduces MTs and produces signs of inflammation in the healthy bladder. Surprisingly, the control surgical procedure (partial hysterectomy; sutures on mesenteric blood vessels) protects bladder reflexes from the influence of bladder inflammation, a condition that is named silent bladder inflammation. Such cross-system inducing and masking effects have important clinical relevance.

The reinnervation pattern of wounds and scars may explain their sensory symptoms

Anaesthesia, pruritus and pain are common in cutaneous scars. The reinnervation pattern of healing wounds and scars might help to explain these symptoms, as sensory neurotransmitters are known to be mediators of inflammation and healing. We quantified the regeneration patterns of blood vessels and nerves in excisional skin wounds as they matured into scars. Mice underwent 1cm(2) full thickness skin excisions. Wounds were harvested between five and 84 days. Sections underwent immunohistochemical staining for protein gene product 9.5 (PGP9.5) a pan-neuronal marker, and the sensory neuropeptides calcitonin gene related peptide (CGRP) and substance P (SP). The endothelial marker von Willebrand factor (VWF) was used to allow co-localisation and quantification of blood vessels. Nerve fibre density was quantified at multiple sites within wounds. There was no difference in the reinnervation/revascularisation pattern between peripheral and central sites. The density of PGP9.5, CGRP, SP and VWF peaked between 14 and 42 days, and levels of PGP9.5, CGRP and VWF all decreased to approximately those found in unwounded skin by 84 days (mature scar). SP levels, however, remained elevated at approximately twice the density found in unwounded skin. Increased densities of SP and CGRP in healing wounds could explain the unpleasant sensory symptoms of healing wounds.

Nerve fibres in peritoneal endometriosis

BACKGROUND

Endometriosis is a gynaecological disease that can be associated with severe pelvic pain; however, the mechanisms by which pain is generated remain unknown.

METHODS

Peritoneal endometriotic lesions and normal peritoneum were prepared from women with and without endometriosis (n = 40 and 36, respectively). Specimens were also prepared from endosalpingiosis lesions (n = 9). These sections were stained immunohistochemically with antibodies against protein gene product 9.5, neurofilament (NF), nerve growth factor (NGF), NGF receptor p75 (NGFRp75), substance P (SP), calcitonin gene-related peptide (CGRP), acetylcholine (ACh) and tyrosine hydroxylase (TH) to demonstrate myelinated, unmyelinated, sensory, cholinergic and adrenergic nerve fibres.

RESULTS

There were significantly more nerve fibres identified in peritoneal endometriotic lesions than in normal peritoneum (P < 0.001) or endosalpingiosis lesions (P < 0.001). These nerve fibres were SP, CGRP, ACh or TH immunoreactive. Many of these markers were co-localized. There was an intense NGF immunoreactivity near endometriotic glands, and NGFRp75 immunoreactive nerve fibres were present near endometriotic glands and blood vessels in the peritoneal endometriotic lesions.

CONCLUSIONS

Peritoneal endometriotic lesions were innervated by sensory Adelta, sensory C, cholinergic and adrenergic nerve fibres. These nerve fibres may play an important role in the mechanisms of pain generation in this condition.

Animal models in endometriosis research

Endometriosis is a common gynaecological disease, defined as the presence of endometrial tissue outside the uterus, causing pelvic pain and subfertility in approximately 10% of women of reproductive age. Current therapies lead to pain relief, however, do not address the causes and entail severe side effects. Still little is known about the pathogenic processes leading to the development and maintenance of endometriosis. Because endometriosis occurs spontaneously only in humans and some non-human primates, animal models of induced endometriosis have been developed and are of high value for the evaluation of pathophysiological mechanisms underlying the development of this disease. These experimental models include the autotransplantation of uterine fragments into the peritoneal cavity of rodents and non-human primates or the heterotransplantation of human endometrial or endometriotic tissue to immunodeficient mice or onto the chicken chorioallantoic membrane (CAM). This review describes the animal models for endometriosis and assesses their different potentials and limitations in regard to endometriosis research, with the aim of developing novel non-invasive diagnostic tools and improved strategies for the treatment of endometriosis in women.

Abdominal wall endometriosis: a diagnostic dilemma for surgeons

OBJECTIVE

To report 3 cases of endometriosis of the abdominal wall, a disease which is unfamiliar to general surgeons because of the potential pitfalls in its diagnosis.

CLINICAL PRESENTATION AND INTERVENTION

Three patients were referred to our general surgery clinic for abdominal masses. Incisional hernia and an abdominal mass were initially suspected in 2 patients, while a preoperative diagnosis of a rectus abdominis hematoma was made in the third because she had no history of previous surgery. Pain was a remarkable complaint in only one of the present cases. Abdominal wall endometriosis was diagnosed only upon histological examination postoperatively. In all cases, ultrasonography revealed hypoechogenic masses, and computed tomography showed that these masses had spiculations, and macroscopic views of the resected masses revealed well-demarcated margins without peritoneal involvement. All patients were treated with wide radical resections followed by polytetrafluoroethylene patch grafting. They were discharged from hospital on either the 2nd or the 3rd postoperative day uneventfully, and during follow-up there were no signs of pelvic endometriosis, as confirmed by ultrasonography, CA 125 measurement, gynecological consultation and examination.

CONCLUSION

Since the diagnosis of scar endometrioma is rarely established prior to surgery, endometriosis should be included in the differential diagnosis of masses on the abdominal wall.

High density of small nerve fibres in the functional layer of the endometrium in women with endometriosis

BACKGROUND

Endometriosis is a common gynaecological disease and is frequently associated with recurrent and serious pelvic pain such as dysmenorrhoea and dyspareunia, but the mechanisms by which these symptoms are generated are not well understood.

METHODS

Histological sections of endometrial tissue were prepared from endometrial curettings and hysterectomies performed on women with endometriosis (n=25 and n=10, respectively) and without endometriosis (n=47 and n=35, respectively). These were stained immunohistochemically for the highly specific polyclonal rabbit anti-protein gene product 9.5 (PGP9.5) and monoclonal mouse anti-neurofilament protein (NF) to demonstrate both myelinated and unmyelinated nerve fibres.

RESULTS

Small nerve fibres were identified throughout the basal and functional layers of the endometrium in all endometriosis patients, but were not seen in the functional layer of the endometrium in any of the women without endometriosis (P<0.001). NF-immunoreactive nerve fibres were present in the basal layer in all endometriosis patients but not in non-endometriosis patients, with one exception (P<0.001).

CONCLUSIONS

Small nerve fibres detected in the functional layer in all women with endometriosis may have important implications for understanding the generation of pain in these patients. The presence of nerve fibres in an endometrial biopsy may be a novel surrogate marker of clinical endometriosis.

Vesicular monoamine transporter 2 (VMAT2) expression in hematopoietic cells and in patients with systemic mastocytosis

Uptake of monoamines into secretory granules is mediated by the vesicular monoamine transporters VMAT1 and VMAT2. In this study, we analyzed their expression in inflammatory and hematopoietic cells and in patients suffering from systemic mastocytosis (SM) and chronic myelogenous leukemia (CML). Normal human and monkey tissue specimens and tissues from patients suffering from SM and CML were analyzed by means of immunohistochemistry, radioactive in situ hybridization, real time RT-PCR, double fluorescence confocal laser scanning microscopy, and immunoelectron microscopy. In normal tissue specimens, VMAT2, but not VMAT1, was expressed in mast cells, megakaryocytes, thrombocytes, basophil granulocytes, and cutaneous Langerhans cells. Further hematopoietic and lymphoid cells showed no expression of VMATs. VMAT2 was expressed in all types of SM, as indicated by coexpression with the mast cell marker tryptase. In CML, VMAT2 expression was retained in neoplastic megakaryocytes and basophil granulocytes. In conclusion, the identification of VMAT2 in mast cells, megakaryocytes, thrombocytes, basophil granulocytes, and cutaneous Langerhans cells provides evidence that these cells possess molecular mechanisms for monoamine storage and handling. VMAT2 identifies normal and neoplastic mast cells, megakaryocytes, and basophil granulocytes and may therefore become a valuable tool for the diagnosis of mastocytosis and malignant systemic diseases involving megakaryocytes and basophil granulocytes.

The pains of endometriosis

Endometriosis is a disease defined by the presence of endometrial tissue outside of the uterus. Severe pelvic pain is often associated with endometriosis, and this pain can be diminished with therapies that suppress estrogen production. Many women with endometriosis also suffer from other chronic pain conditions. Recent studies suggest that mechanisms underlying these pains and sensitivity to estrogen involve the growth into the ectopic endometrial tissue of a nerve supply, which could have a varied and widespread influence on the activity of neurons throughout the central nervous system.