Pain, mast cells, and nerves in peritoneal, ovarian, and deep infiltrating endometriosis

The importance of pelvic nerve fibers in endometriosis

Several lines of recent evidence suggest that pelvic innervation is altered in endometriosis-affected women, and there is a strong presumption that nerve fibers demonstrated in eutopic endometrium (of women with endometriosis) and in endometriotic lesions play roles in the generation of chronic pelvic pain. The recent observation of sensory C, sensory A-delta, sympathetic and parasympathetic nerve fibers in the functional layer of endometrium of most women affected by endometriosis, but not demonstrated in most women who do not have endometriosis, was a surprise. Nerve fiber densities were also greatly increased in myometrium of women with endometriosis and in endometriotic lesions compared with normal peritoneum. Chronic pelvic pain is complex, and endometriosis is only one condition which contributes to this pain. The relationship between the presence of certain nerve fibers and the potential for local pain generation requires much future research. This paper reviews current knowledge concerning nerve fibers in endometrium, myometrium and endometriotic lesions, and discusses avenues of research that may improve our knowledge and lead to enriched understanding and management of endometriotic pain symptoms.

Gastrointestinal symptoms among endometriosis patients--A case-cohort study

Background

Women with endometriosis often experience gastrointestinal symptoms. Gonadotropin-releasing hormone (GnRH) analogs are used to treat endometriosis; however, some patients develop gastrointestinal dysmotility following this treatment. The aims of the present study were to investigate gastrointestinal symptoms among patients with endometriosis and to examine whether symptoms were associated with menstruation, localization of endometriosis lesions, or treatment with either opioids or GnRH analogs, and if hormonal treatment affected the symptoms.

Methods

All patients with diagnosed endometriosis at the Department of Gynecology were invited to participate in the study. Gastrointestinal symptoms were registered using the Visual Analogue Scale for Irritable Bowel Syndrome (VAS-IBS); socioeconomic and medical histories were compiled using a clinical data survey. Data were compared to a control group from the general population.

Results

A total of 109 patients and 65 controls were investigated. Compared to controls, patients with endometriosis experienced significantly aggravated abdominal pain (P = 0.001), constipation (P = 0.009), bloating and flatulence (P = 0.000), defecation urgency (P = 0.010), and sensation of incomplete evacuation (P = 0.050), with impaired psychological well-being (P = 0.005) and greater intestinal symptom influence on their daily lives (P = 0.001). The symptoms were not associated with menstruation or localization of endometriosis lesions, except increased nausea and vomiting (P = 0.010) in patients with bowel-associated lesions. Half of the patients were able to differentiate between abdominal pain from endometriosis and from the gastrointestinal tract. Patients using opioids experienced more severe symptoms than patients not using opioids, and patients with current or previous use of GnRH analogs had more severe abdominal pain than the other patients (P = 0.024). Initiation of either combined oral contraceptives or progesterone for endometriosis had no effect on gastrointestinal symptoms when the patients were followed prospectively.

Conclusions

The majority of endometriosis patients experience more severe gastrointestinal symptoms than controls. A poor association between symptoms and lesion localization was found, indicating existing comorbidity between endometriosis and irritable bowel syndrome (IBS). Treatment with opioids or GnRH analogs is associated with aggravated gastrointestinal symptoms.

Pathogenetic Mechanisms of Deep Infiltrating Endometriosis

Endometriosis is a benign gynecologic disease, affecting women of reproductive age associated with chronic pelvic pain, dysmenorrhea, dyspareunia and infertility. Ovarian endometrioma (OMA), superficial peritoneal endometriosis (SPE), and deep infiltrating endometriosis (DIE) are, till now, recognized as major phenotypes. The discussion is to know whether they share the same pathogenetic mechanisms. Till today, DIE is recognized as the most severe clinical form of endometriosis and has a complex clinical management. The DIE lesions have been considered in the present article, without distinguishing between the anterior (bladder) or the posterior (vagina, uterosacral ligaments, rectum, and ureter) compartment. The present knowledge indicates that hormonal function (estrogen and progesterone receptors) and immunological factors, such as peritoneal macrophages, natural killer cells, and lymphocytes, are critically altered in DIE. The aggressive behavior of DIE may be explained by the highly decreased apoptosis (nuclear factor kappa-light-chain-enhancer of activated B cells [NF-kB], B-cell lymphoma 2 [Blc-2], and anti-Mullerian hormone) and by the increased proliferation activity related to oxidative stress (NF-kB, reactive oxygen species, extracellular regulated kinase (ERK), advanced oxidation protein product). Invasive mechanisms are more expressed (matrix metalloproteinases and activins) in DIE in comparison to the OMA and SPE. Correlated with the increased invasiveness are the data on very high expression of neuroangiogenesis (nerve growth factor, vascular endothelial growth factor, and intercellular adhesion molecule) genes in DIE. Therefore, at the present time, several of the DIE pathogenetic features result specific in comparison to other endometriosis phenotypes, pleading for the existence of a specific entity. These evidence of specific pathogenetic features of DIE may explain the more severe symptomatology related to this form of endometriosis and suggest possible future target medical treatments.

The risk of irritable bowel syndrome in patients with endometriosis during a 5-year follow-up: a nationwide population-based cohort study

PURPOSE

Studies have suggested that endometriosis may coexist with irritable bowel syndrome (IBS). Using a population-based cohort study, we followed subjects for a 5-year period to identify the risk of IBS after a diagnosis of endometriosis.

METHODS

This cohort study used the Taiwan National Health Insurance Database as a source of subjects. A total of 6076 patients with endometriosis from 2000 to 2005 were identified. Their data were compared with those of 30,380 age-matched controls without endometriosis who were randomly selected from the same database. All subjects were tracked for 5 years from the date of cohort entry to identify the risk of IBS. The Cox model was used to evaluate the 5-year event occurrence of IBS.

RESULTS

Nine hundred twenty-six patients were diagnosed with IBS, including 256 in the case cohort (4.2%) and 670 in the control cohort (2.2%). The Kaplan-Meier survival curves demonstrated significantly lower event-free rates in the case cohort than in the control cohort (P = 0.001). After adjusting for urbanization level, monthly income, residential region and comorbidities, the hazard ratio (HR) within 5 years revealed a 1.79-fold (95% confidence interval [CI] 1.55-2.07) greater risk among the cases than the controls. The HR was higher within the first year of follow-up (HR 1.90, 95% CI 1.42-2.55) and in those women aged 25-34 years (HR 2.17, 95% CI 1.61-2.92).

CONCLUSIONS

The risk of IBS among endometriosis patients persisted over 5 years of follow-up. The association detected in this study might have proceeded through shared risk and pathogenic factors.

Effect of human umbilical cord mesenchymal stem cells transplantation on nerve fibers of a rat model of endometriosis

Background

Endometriosis is a common, benign, oestrogen-dependent, chronic gynaecological disorder associated with pelvic pain and infertility. Some researchers have identified nerve fibers in endometriotic lesions in women with endometriosis. Mesenchymal stem cells (MSCs) have attracted interest for their possible use for both cell and gene therapies because of their capacity for self-renewal and multipotentiality of differentiation. We investigated how human umbilical cord-MSCs (hUC-MSCs) could affect nerve fibers density in endometriosis.

Materials and Methods

In this experimental study, hUC-MSCs were isolated from fresh human umbilical cord, characterized by flow cytometry, and then transplanted into surgically induced endometriosis in a rat model. Ectopic endometrial implants were collected four weeks later. The specimens were sectioned and stained immunohistochemically with antibodies against neurofilament (NF), nerve growth factor (NGF), NGF receptor p75 (NGFRp75), tyrosine kinase receptor-A (Trk-A), calcitonin gene-related peptide (CGRP) and substance P (SP) to compare the presence of different types of nerve fibers between the treatment group with the transplantation of hUC-MSCs and the control group without the transplantation of hUC-MSCs.

Results

There were significantly less nerve fibers stained with specific markers we used in the treatment group than in the control group (p<0.05).

Conclusion

MSC from human umbilical cord reduced nerve fiber density in the treatment group with the transplantation of hUC-MSCs.

Innervation in women with uterine myoma and adenomyosis

Objective

To determine if neurofilament (NF) is expressed in the endometrium and the lesions of myomas and adenomyosis, and to determine their correlation.

Methods

Histologic sections were prepared from hysterectomies performed on women with adenomyosis (n=21), uterine myoma (n=31), and carcinoma in situ of the uterine cervix. Full-thickness uterine paraffin blocks, which included the endometrium and myometrium histologic sections, were stained immunohistochemically using the antibodies for monoclonal mouse antihuman NF protein.

Results

NF-positive cells were found in the endometrium and myometrium in 11 women with myoma and in 7 with adenomyosis, but not in patients with carcinoma in situ of uterine cervix, although the difference was statistically not significant. There was no significant difference between the existence of NF-positive cells and menstrual pain or phases. The NF-positive nerve fibers were in direct contact with the lesions in nine cases (29.0%) of myoma and in five cases (23.8%) of adenomyosis. It was analyzed if there was a statistical significance between the existence of NF positive cells in the endometrium and the expression of NF-positive cells in the uterine myoma/adenomyosis lesions. When NF-positive cell were detected in the myoma lesions, the incidence of NF-positive nerve cells in the eutopic endometrium was significantly high. When NF-positive cell were detected in the basal layer, the incidence of NF-positive nerve cells in the myoma lesions and adenomyosis lesions was significantly high.

Conclusion

We assume that NF-positive cells in the endometrium and the myoma and adenomyosis lesions might play a role in pathogenesis. Therefore, more studies may be needed on the mechanisms of nerve fiber growth in estrogen-dependent diseases.

Human Adenomyosis Endometrium Stromal Cells Secreting More Nerve Growth Factor: Impact and Effect

Abnormal expression of nerve growth factor (NGF) was found in adenomyosis (AM). We collected AM foci from patients and eutopic endometrium from non-AM controls. Endometrium stromal cells (ESCs) were cultured. Different levels of 17β-estradiol, tumor necrosis factor (TNF), CoCl2, and H2O2 were added to the culture system separately, then the expression level of NGF in ESCs was detected. After adding different levels of NGF, the proliferation and apoptosis of ESCs and aromatase expression were detected. We found that 17β-estradiol promoted NGF production in AM ESCs but not in control ESCs; TNF promoted NGF production in both AM and control ESCs; and CoCl2 inhibited NGF production in control ESCs, but had no effect in AM ESCs. Nerve growth factor promoted the proliferation and synthesis of aromatase in AM ESCs. In conclusion, locally increased estrogen levels and inflammation may cause increased NGF production in the uterus of patients with AM. Nerve growth factor stimulated the proliferation and increased aromatase expression of ESCs from AM foci, suggesting NGF might contribute to the pathology and etiology of AM.

Telocytes damage in endometriosis-affected rat oviduct and potential impact on fertility

Women with endometriosis (EMs) have unexplained infertility. The recently identified telocytes (TCs) might participate in the maintenance of structural and functional integrity of oviduct tissue, but so far the involvement of TCs in EMs-affected oviduct tissue and potential impact on fertility capacity remain unknown. By an integrated technique of haematoxylin and eosin staining, in situ immunohistochemistry and double-labelled immunofluorescence staining and electron microscopy approach, TCs were studied in the autotransplantation Sprague-Dawley rat model of EMs-affected oviduct tissue and in sham control, respectively, together with determination of iNOS, COX-2, LPO and estradiol. TCs were found in perivascular connective tissue and smooth muscle bundles in sham oviduct, with typical ultrastructural features (a slender piriform/spindle/triangular cell body, and one or more extremely long prolongations, emerged from cell bodies and extend to various directions), and specific immunophenotype of CD34-positive/vimentin-positive/c-kit-negative. However, in EMs-affected oviduct tissue (grade III), extensive ultrastructural damage (degeneration, discontinue, dissolution and destruction), significant decrease or loss of TCs and interstitial fibrosis were observed, together with elevated level of iNOS, COX-2, LPO and estradiol, thus suggestive of inflammation and ischaemia-induced TCs damage. Based on TCs distribution and intercellular connections, we proposed that such damage might be involved in structural and functional abnormalities of oviduct, such as attenuated intercellular signalling and oviduct contractility, impaired immunoregulation and stem cell-mediated tissue repair, 3-D interstitial architectural derangement and tissue fibrosis. Therefore, TCs damage might provide a new explanation and potential target for EMs-induced tubal damage and fertility disorders.

Mast cells in chronic inflammation, pelvic pain and depression in women

Inflammatory and neuroinflammatory processes are increasingly recognized as critical pathophysiologic steps in the development of multiple chronic diseases and in the etiology of persistent pain and depression. Mast cells are immune cells now viewed as cellular sensors in inflammation and immunity. When stimulated, mast cells release an array of mediators to orchestrate an inflammatory response. These mediators can directly initiate tissue responses on resident cells, and may also regulate the activity of other immune cells, including central microglia. New evidence supports the involvement of peripheral and central mast cells in the development of pain processes as well as in the transition from acute, to chronic and neuropathic pain. That behavioral and endocrine states can increase the number and activation of peripheral and brain mast cells suggests that mast cells represent the immune cells that peripherally and centrally coordinate inflammatory processes in neuropsychiatric diseases such as depression and anxiety which are associated with chronic pelvic pain. Given that increasing evidence supports the activated mast cell as a director of common inflammatory pathways/mechanisms contributing to chronic and neuropathic pelvic pain and comorbid neuropsychiatric diseases, mast cells may be considered a viable target for the multifactorial management of both pain and depression.

Peripheral changes in endometriosis-associated pain

BACKGROUND

Pain remains the cardinal symptom of endometriosis. However, to date, the underlying mechanisms are still only poorly understood. Increasing evidence points towards a close interaction between peripheral nerves, the peritoneal environment and the central nervous system in pain generation and processing. Recently, studies demonstrating nerve fibres and neurotrophic and angiogenic factors in endometriotic lesions and their vicinity have led to increased interest in peripheral changes in endometriosis-associated pain. This review focuses on the origin and function of these nerves and factors as well as possible peripheral mechanisms that may contribute to the generation and modulation of pain in women with endometriosis.

METHODS

We conducted a systematic search using several databases (PubMed, MEDLINE, EMBASE and CINAHL) of publications from January 1977 to October 2013 to evaluate the possible roles of the peripheral nervous system in endometriosis pathophysiology and how it can contribute to endometriosis-associated pain.

RESULTS

Endometriotic lesions and peritoneal fluid from women with endometriosis had pronounced neuroangiogenic properties with increased expression of new nerve fibres, a shift in the distribution of sensory and autonomic fibres in some locations, and up-regulation of several neurotrophins. In women suffering from deep infiltrating endometriosis and bowel endometriosis, in which the anatomical distribution of lesions is generally more closely related to pelvic pain symptoms, endometriotic lesions and surrounding tissues present higher nerve fibre densities compared with peritoneal lesions and endometriomas. More data are needed to fully confirm a direct correlation between fibre density in these locations and the amount of perceived pain. A better correlation between the presence of nerve fibres and pain symptoms seems to exist for eutopic endometrium. However, this appears not to be exclusive to endometriosis. No correlation between elevated neurotrophin levels and pain severity appears to exist, suggesting the involvement of other mediators in the modulation of pain.

CONCLUSIONS

The increased expression of neurotrophic factors and nerve fibres in endometriotic lesions, eutopic endometrium and the peritoneum imply a role of such peripheral changes in the pathogenesis of endometriosis-associated pain. However, a clear link between these findings and pain in patients with endometriosis has so far not been demonstrated.

Endometriosis: pathogenesis and treatment

Endometriosis is defined as the presence of endometrial-type mucosa outside the uterine cavity. Of the proposed pathogenic theories (retrograde menstruation, coelomic metaplasia and Müllerian remnants), none explain all the different types of endometriosis. According to the most convincing model, the retrograde menstruation hypothesis, endometrial fragments reaching the pelvis via transtubal retrograde flow, implant onto the peritoneum and abdominal organs, proliferate and cause chronic inflammation with formation of adhesions. The number and amount of menstrual flows together with genetic and environmental factors determines the degree of phenotypic expression of the disease. Endometriosis is estrogen-dependent, manifests during reproductive years and is associated with pain and infertility. Dysmenorrhoea, deep dyspareunia, dyschezia and dysuria are the most frequently reported symptoms. Standard diagnosis is carried out by direct visualization and histologic examination of lesions. Pain can be treated by excising peritoneal implants, deep nodules and ovarian cysts, or inducing lesion suppression by abolishing ovulation and menstruation through hormonal manipulation with progestins, oral contraceptives and gonadotropin-releasing hormone agonists. Medical therapy is symptomatic, not cytoreductive; surgery is associated with high recurrence rates. Although lesion eradication is considered a fertility-enhancing procedure, the benefit on reproductive performance is moderate. Assisted reproductive technologies constitute a valid alternative. Endometriosis is associated with a 50% increase in the risk of epithelial ovarian cancer, but preventive interventions are feasible.

Mast cells: versatile gatekeepers of pain

Mast cells are important first responders in protective pain responses that provoke withdrawal from intense, noxious environmental stimuli, in part because of their sentinel location in tissue-environment interfaces. In chronic pain disorders, the proximity of mast cells to nerves potentiates critical molecular cross-talk between these two cell types that results in their synergistic contribution to the initiation and propagation of long-term changes in pain responses via intricate signal networks of neurotransmitters, cytokines and adhesion molecules. Both in rodent models of inflammatory pain and chronic pain disorders, as well as in increasing evidence from the clinic, it is abundantly clear that understanding the mast cell-mediated mechanisms underlying protective and maladaptive pain cascades will lead to improved understanding of mast cell biology as well as the development of novel, targeted therapies for the treatment and management of debilitating pain conditions.

Dienogest inhibits nerve growth factor expression induced by tumor necrosis factor-α or interleukin-1β

OBJECTIVE

Dienogest (DNG), a selective P receptor (PR) agonist, is used to treat endometriosis. To investigate whether DNG affects nerve growth factor (NGF) expression, we stimulated human endometrial epithelial cells (hEECs) with inflammatory cytokines.

DESIGN

Prospective basic research study using immortalized hEEC lines.

SETTING

Development Research, Mochida Pharmaceutical Co., Ltd., Japan.

PATIENT(S)

None.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

In immortalized hEECs, NGF production induced by tumor necrosis factor-α (TNF-α) or interleukin-1β (IL-1β) was evaluated in the presence or absence of the synthetic progestin DNG or endogenous P. The NGF messenger RNA (mRNA) and protein were measured using real-time reverse transcriptase-polymerase chain reaction (PCR) and ELISA, respectively. The NGF bioactivity in the culture medium was measured by assaying neurite outgrowth of PC-12 cells.

RESULT(S)

Tumor necrosis factor-α and IL-1β induced NGF mRNA and protein and increased NGF bioactivity in the culture medium. These activities were inhibited by DNG in a hEEC line that stably expresses PR. In contrast, in an hEEC line that constitutively expresses faint levels of PR, no inhibitory effect of DNG on NGF mRNA was detected. The NGF mRNA was also inhibited in hEEC lines that express only PR-A or only PR-B.

CONCLUSION(S)

Nerve growth factor is one of the key mediators that generates the pain associated with endometriosis. Dienogest inhibits NGF expression through PR-A and PR-B in hEEC, which may contribute to the pharmacological mechanisms of how DNG relieves pain in endometriosis.

Mechanisms involved in abdominal nociception induced by either TRPV1 or TRPA1 stimulation of rat peritoneum

Abdominal pain is a frequent symptom of peritoneal cavity irritation, but little is known about the role of the receptors for irritant substances, transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1), in this painful condition. Thus, we investigated the abdominal nociception caused by peritoneal stimulation with TRPV1 (capsaicin) and TRPA1 (allyl isothiocyanate, AITC) agonists and their mechanisms in rats. The intraperitoneal (i.p.) injection of either capsaicin or AITC (0.03-10 mg/kg) induced short-term (up to 20 min) and dose-dependent abdominal nociception, and also produced c-fos expression in spinal afferents of the dorsal horn. TRPV1 antagonism prevented (94 ± 4% inhibition) nociception induced by capsaicin but not by AITC. In contrast, the TRPA1 antagonism almost abolished AITC-induced nociception (95 ± 2% inhibition) without altering the capsaicin response. Moreover, nociception induced by either capsaicin or AITC was reduced by the desensitisation of TRPV1-positive sensory fibres with resiniferatoxin (73 ± 18 and 76 ± 15% inhibitions, respectively) and by the NK1 receptor antagonist aprepitant (56 ± 5 and 53 ± 8% inhibitions, respectively). Likewise, the i.p. injections of capsaicin or AITC increased the content of substance P in the peritoneal fluid. Nevertheless, neither the mast cell membrane stabiliser cromoglycate, nor the H1 antagonist promethazine, nor depletion of peritoneal macrophages affected abdominal nociception induced either by capsaicin or AITC. Accordingly, neither capsaicin nor AITC increased the histamine content in the peritoneal fluid or provoked peritoneal mast cell degranulation in vitro. Collectively, our findings suggest that TRPV1 and TRPA1 stimulation in the peritoneum produces abdominal nociception that is mediated by sensory fibres activation.

Anti-TNF-α treatment for pelvic pain associated with endometriosis

BACKGROUND

Endometriosis is a chronic, recurring condition that can develop during the reproductive years. It is characterised by the development of endometrial tissue outside the uterine cavity. It is the most common cause of pelvic pain in women. This endometrial tissue development is dependent on oestrogen produced primarily by the ovaries and, therefore, traditional management has focused on suppression of ovarian function. Mounting evidence shows that altered immune function plays a crucial role in the genesis and development of endometriosis. In this review we considered modulation of the inflammation as an alternative approach.

OBJECTIVES

To determine the effectiveness and safety of anti-tumour necrosis factor-α (anti-TNF-α) treatment in the management of endometriosis in premenopausal women.

SEARCH METHODS

For the first publication of this review, we searched for trials in the following databases (from their inception to August 2009): Cochrane Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, CINAHL, and PsycINFO. In addition, we searched all reference lists of included trials and contacted experts in the field in an attempt to locate trials. We reran this search to 3 September 2012 for this update.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing anti-TNF-α drugs with placebo, no treatment, medical treatment, or surgery for pelvic pain associated with endometriosis were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality, and extracted data using data extraction forms. The domains assessed for risk of bias were sequence generation, allocation concealment, blinding, incomplete outcome data, and selective outcome reporting. We used risk ratios (RR) for reporting dichotomous data with 95% confidence intervals (CI), whilst we expressed continuous data as mean differences (MD). We assessed statistical heterogeneity using the I(2) statistic.

MAIN RESULTS

Only one trial involving 21 participants was included. The results showed no evidence of an effect of infliximab, one of the known anti-TNF-α drugs, on pelvic pain reduction using the Biberoglu-Behrman (BB) score (0 to 3 scale) for participants (MD -0.14, 95% CI -0.43 to 0.15), the BB score for clinicians (MD -0.14, 95% CI -0.39 to 0.11), or a visual analogue pain score (VAS, 100 mm scale) (MD -5.60, 95% CI -16.10 to 4.90), or on the use of pain killers (ibuprofen, g/day) (MD -0.10, 95% CI -0.30 to 0.10). There was no evidence of an increase in adverse events in the infliximab group compared with placebo (RR 3.73, 95% CI 0.22 to 63.66). We found no evidence of clinical benefits of infliximab for endometriotic lesions, dysmenorrhoea, dyspareunia, or pelvic tenderness. To date, there is no trial that has reported a cost-effectiveness analysis of anti-TNF-α drugs, or the odds of recurrence.

AUTHORS' CONCLUSIONS

This review was updated in 2012. The results of the original review published in 2010 remain unchanged. There is still not enough evidence to support the use of anti-TNF-α drugs in the management of women with endometriosis for the relief of pelvic pain.

The adjuvant use of N-palmitoylethanolamine and transpolydatin in the treatment of endometriotic pain

OBJECTIVE

To test the adjuvant use of the combination of N-palmitoylethanolamine and transpolydatin in the medical treatment of endometriotic pain.

STUDY DESIGN

We enrolled 47 patients admitted to the Outpatient Endometriosis Care Unit of Ferrara University from January 2011 to December 2011. They were divided into two groups according to the endometriosis site (group A: recto-vaginal septum; group B: ovary). One tablet, containing 400 mg of micronized N-palmitoylethanolamine plus 40 mg transpolydatin, was administered twice daily on a full stomach for 90 days. Each patient was requested to grade the severity of dysmenorrhea, chronic pelvic pain, dyspareunia and dyschezia using a 0-10 cm visual analogic scale prior to beginning treatment (T0), after 30 days (T1), 60 days (T2) and 90 days (T3). The continuous and categorical variables were compared, respectively, using Student's t-test and the chi-square test. Analysis of variance for repeated measures was used to verify the reduction of endometriotic pain.

RESULTS

The intensity of endometriotic pain decreased significantly for both groups (p<0.0001). The efficacy of drug treatment was significant after 30 days. Pain intensity decreased equally in the two groups except for dysmenorrhea, which was reduced more rapidly in group B.

CONCLUSIONS

The combination of N-palmitoylethanolamine and transpolydatin reduced pain related to endometriosis irrespective of lesion site. It had a marked effect on chronic pelvic pain determined by deep endometriosis and on dysmenorrhea correlated to ovarian endometriosis.

Effect of antiangiogenic treatment on peritoneal endometriosis-associated nerve fibers

OBJECTIVE

To investigate the effect of antiangiogenic treatment on experimental endometriotic lesion nerve fibers.

DESIGN

Heterologous mouse model of endometriosis.

SETTING

University Institute IVI, University Hospital La Fe.

ANIMAL(S)

Ovariectomized nude mice (n = 16) receiving human endometrial fragments from oocyte donors (n = 4).

INTERVENTION(S)

Endometrium fragments stuck in the peritoneum of 5-week-old female nude mice treated with vehicle (n = 8) and antiangiogenic agent cabergoline (n = 8; Cb(2,) 0.05 mg/kg/day) for 14 days.

MAIN OUTCOME MEASURE(S)

Immunofluorescence analysis of von-Willebrand factor (vWF) and vascular smooth muscle cells (αSMA) for evaluating the number of immature blood vessels (IBV) and microvascular density (MVD); immunochemical analysis of protein-gene product 9.5 (PGP 9.5) to assess nerve fibers density (NFD), and blue toluidine staining to confirm presence of mast cells and macrophages in endometriotic lesions.

RESULT(S)

All the results were quantified by morphometric techniques. The IBV, NFD, and number of macrophages and mast cells were statistically significantly decreased in the Cb2-treated group when compared with controls.

CONCLUSION(S)

Antiangiogenic treatment statistically significantly diminishes new blood vessel formation after macrophage, mast cell, and nerve fiber reduction, providing a rationale to test antiangiogenic agents as a novel therapeutic approach to severe pelvic pain associated with human peritoneal endometriosis.

Mast cell degranulation mediates compound 48/80-induced hyperalgesia in mice

Mast cells mediate allergies, hypersensitivities, host defense, and venom neutralization. An area of recent interest is the contribution of mast cells to inflammatory pain. Here we found that specific, local activation of mast cells produced plantar hyperalgesia in mice. Basic secretagogue compound 48/80 induced plantar mast cell degranulation accompanied by thermal hyperalgesia, tissue edema, and neutrophil influx in the hindpaws of ND4 Swiss mice. Blocking mast cell degranulation, neutrophil extravasation, and histamine signaling abrogated these responses. Compound 48/80 also produced edema, pain, and neutrophil influx in WT C57BL/6 but not in genetically mast cell-deficient C57BL/6-Kit(W-sh)(/)(W-sh) mice. These responses were restored following plantar reconstitution with bone marrow-derived cultured mast cells.

Stress exacerbates endometriosis manifestations and inflammatory parameters in an animal model

Women with endometriosis have significant emotional distress; however, the contribution of stress to the pathophysiology of this disease is unclear. We used a rat model of endometriosis to examine the effects of stress on the development of this condition and its influence on inflammatory parameters. Female Sprague-Dawley rats were subjected to swim stress for 10 consecutive days prior to the surgical induction of endometriosis by suturing uterine horn implants next to the intestinal mesentery (endo-stress). Sham-stress animals had sutures only, and an endo-no stress group was not subjected to the stress protocol. At the time of sacrifice on day 60, endometriotic vesicles were measured and colons assessed for macroscopic and microscopic damage. Colonic tissue and peritoneal fluid were collected for inflammatory cell analysis. Endometriosis, regardless of stress, produced a decrease in central corticotropin-releasing factor immunoreactivity, specifically in the CA3 subregion of the hippocampus. Prior exposure to stress increased both the number and severity of vesicles found in animals with endometriosis. Stress also increased colonic inflammation, motility, myeloperoxidase levels, and numbers of mast cells. In summary, prior stress may contribute to the development and severity of endometriosis in this animal model through mechanisms involving cell recruitment (eg, mast cells), release of inflammatory mediators, and deregulation of hypothalamic-pituitary axis responses in the hippocampus.

Continuous low-dose oral contraceptive in the treatment of colorectal endometriosis evaluated by rectal endoscopic ultrasonography

OBJECTIVE

Limited attention has been focused on the medical treatment of bowel endometriosis. This study evaluates the efficacy of administration of a continuous low-dose oral contraceptive in treating pain and other symptoms associated with colorectal endometriotic nodules, as evaluated by rectal endoscopic ultrasonography.

DESIGN

Prospective observational study.

SETTING

Academic Department of San Raffaele Scientific Institute, Obstetrics and Gynecology Unit.

POPULATION

Symptomatic women of reproductive age (n=26) with colorectal nodules infiltrating at least the bowel muscularis propria and without a stenosis >50%. In 31% of the patients, endoscopic ultrasonography permitted diagnosis of nodules located more than 10 cm from the anal rim.

METHODS

Patients received a continuous low-dose oral contraceptive containing 15 μg ethinylestradiol and 60 μg gestodene for 12 months. Subjective symptoms were prospectively evaluated, and nodule volumes were monitored using endoscopic ultrasonography.

MAIN OUTCOME MEASURES

Nodule measurements were performed at baseline and after 12 months of treatment. Symptoms at the start and after 12 months were evaluated.

RESULTS

A significant improvement in the intensity of all the considered symptoms (dysmenorrhea, non-menstrual pelvic pain, deep dyspareunia and painful defecation) was seen when evaluated by a visual analog scale. A reduction in terms of both diameter (mean reduction 26%) and volume of the nodules (mean reduction 62%) was observed after a 12 month period.

CONCLUSIONS

A continuous low-dose oral contraceptive therapy may reduce bowel endometriosis-associated symptoms. In addition, this therapy induces a significant volumetric reduction of colorectal plaques when evaluated by endoscopic ultrasonography.

Ovarian endometrioma: severe pelvic pain is associated with deeply infiltrating endometriosis

BACKGROUND

The objective of this study was to evaluate the significance of severe preoperative pain for patients presenting with ovarian endometrioma (OMA).

METHODS

Three hundred consecutive patients with histologically proven OMA were enrolled at a single university tertiary referral centre between January 2004 and May 2010. Complete surgical excision of all recognizable endometriotic lesions was performed for each patient. Pain intensity was assessed with a 10-cm visual analogue scale (VAS). Pain was considered as severe when VAS was ≥ 7. Prospective preoperative assessment of type and severity of pain symptoms (VAS) was compared with the peroperative findings (surgical removal and histological analysis) of endometriomas and associated deeply infiltrating endometriosis. Correlations were sought with univariate analysis and a multiple regression logistic model.

RESULTS

After multiple logistic regression analysis, uterosacral ligaments involvement was related with a high severity of chronic pelvic pain [odds ratios (OR) = 2.1; 95% confidence interval (CI): 1.1-4.3] and deep dyspareunia (OR = 2.0; 95% CI: 1.1-3.5); vaginal involvement was related with a higher intensity of lower urinary symptoms (OR = 13.4; 95% CI: 3.2-55.8); intestinal involvement was related with an increased severity of dysmenorrhoea (OR = 5.2; 95% CI: 2.7-10.3) and gastro-intestinal symptoms (OR = 7.1; 95% CI: 3.3-15.3).

CONCLUSIONS

In case of OMA, severe pelvic pain is significantly associated with deeply infiltrating lesions. In this situation, the practitioner should perform an appropriate preoperative imaging work-up in order to evaluate the existence of associated deep nodules and inform the patient in order to plan the surgical intervention strategy.

Deep infiltrating endometriosis is associated with markedly lower body mass index: a 476 case-control study

BACKGROUND

An inverse association between BMI and endometriosis has been reported but remains controversial. We decided to evaluate the association between BMI and the different types of endometriosis, classified as superficial endometriosis (SUP), deep infiltrating endometriosis (DIE) and ovarian endometrioma (OMA).

METHODS

From a prospective database of patients who underwent gynecological surgery between February 2005 and October 2008, we compared 238 patients with a histological diagnosis of endometriosis to 238 age- and smoking-status-matched controls using a prospective preoperative questionnaire and surgical data. Numerical variables means were compared for matched pairs, and non-parametric variables using Wilcoxon test. The Odds ratios for all types of endometriosis adjusted for confounding variables were computed according to predefined BMI groups [1(<18.5), 2 (≥18.5 and <22), 3(≥22 and <25), 4(≥25)], taking Group 3 as the reference population.

RESULTS

BMI was significantly lower for all 238 patients (21.70 ± 3.7 versus 23.29 ± 4.1, P < 0.001), for 101 OMA patients (21.88 ± 3.8 versus 22.99 ± 4, P < 0.038), and for 97 DIE patients (21.35 ± 3.4 versus 23.35 ± 3.8, P < 0.001) compared with their own controls, but not for the 40 SUP patients. Patients in Group 1 had adjusted odds ratios as high as 3.3 [95% confidence interval (CI): 1.6-6.8] for DIE and 2.7 (95% CI: 1.1-6.8) for OMA; in Group 2, the adjusted oddd ratios were 2.6 (95% CI: 1.3-5.5) for DIE and 2.9 (95% CI: 1.5-5.4) for OMA.

CONCLUSIONS

Endometriotic patients have lower BMI than age- and smoking-status-matched controls, independent of confounding variables. Patients with the lowest BMI (<18.5) are at a high risk of DIE.

Human tryptase cleaves pro-nerve growth factor (pro-NGF): hints of local, mast cell-dependent regulation of NGF/pro-NGF action

Several factors regulate nerve growth factor (NGF), which is formed from pro-NGF by intracellular and extracellular enzymatic cleavage. The close proximity between mast cells expressing the protease tryptase and NGF-producing smooth muscle-like peritubular cells in the testes of infertile patients led us to examine whether tryptase is among those factors. Human peritubular cells express functional tryptase receptors (PAR-2). Recombinant enzymatically active β-tryptase increased NGF levels in the culture medium of primary human peritubular cells, but the peptide agonist for PAR-2 (SLIGKV) did not. Neither tryptase nor the peptide increased NGF mRNA levels. To test whether the increase in NGF is due to enzymatic activity of tryptase acting on pro-NGF, supernatants of peritubular cells and synthetic pro-NGF were treated with tryptase. Results of Western blot studies indicate enzymatic cleavage of pro-NGF by active tryptase. Heat-inactivated tryptase or SLIGKV was not effective. Mass spectrometry analysis of in vitro cleavage products from recombinant tryptase and synthetic pro-NGF revealed multiple cleavage sites within the pro-NGF sequence. The results also indicate the generation of mature NGF and smaller NGF fragments as a result of tryptase action. Thus, tryptase-secreting mast cells in the vicinity of pro-NGF/NGF-secreting cells in any human tissue are likely able to alter the ratios of pro-NGF/NGF. As NGF and pro-NGF have different affinities for their receptors, this indicates a novel way by which mast cells, via tryptase, can modify the microenvironment in human tissues with regard to neurotrophin actions.

Effectiveness of the association micronized N-Palmitoylethanolamine (PEA)-transpolydatin in the treatment of chronic pelvic pain related to endometriosis after laparoscopic assessment: a pilot study

OBJECTIVE

Aim of our study was to evaluate the effectiveness of the association between N-Palmitoylethanolamine and transpolydatin in the management of chronic pelvic pain related to EMS.

STUDY DESIGN

This was a randomized, double-blind, parallel-group, placebo-controlled clinical trial involving 61 subjects, submitted to a first line laparoscopic conservative surgery, who were randomized into 3 groups receiving: group A (n=21) the association N-Palmitoylethanolamine-transpolydatin 400 mg + 40 mg twice a day for 3 months; group B (n=20) the placebo for 3 months; group C (n=20) a single course of Celecoxib 200mg twice a day for 7 consecutive days. Assessments of the severity of pelvic endometriosis (pelvic pain, dysmenorrhoea and dyspareunia) were recorded before and after treatment on a questionnaire and a 10-point VAS. Differences between groups were verified with Kruskal-Wallis ANOVA for non-parametric multiple comparisons.

RESULTS

A marked decrease in dysmenorrhoea, dyspareunia and pelvic pain was observed in all groups, and the association between N-Palmitoylethanolamine and transpolydatin resulted to be more effective than placebo (P<.001). Additionally, the treatment with Celecoxib resulted in a decrease in pelvic pain more effective either than the association N-Palmitoylethanolamine and transpolydatin or placebo.

CONCLUSION

These preliminary results show that the association between micronized N-Palmitoylethanolamine and transpolydatin is effective in the management of pelvic pain related to endometriosis after laparoscopy. Additionally, this association seems to be safe, shows an optimal control of pain and can be used in patients who are unable to receive other therapies.

Cyclic sciatica from extrapelvic endometriosis affecting the sciatic nerve

Sciatic (catamenial) radiculopathy, waxing and waning with the menstrual cycle, is an uncommon condition typically caused by pelvic endometriosis affecting the lumbosacral plexus or proximal sciatic nerve. The authors describe a woman with catamenial sciatica caused by endometriosis affecting the sciatic nerve trunk in the upper thigh. Symptomatic with leg pain for 5 years, this patient developed gluteal atrophy and sensory loss and decreased strength in the L-5 dermatomyotome, a distribution confirmed by electromyography. Magnetic resonance imaging suggested thickening of the sciatic nerve at and distal to the sciatic notch. At operation the nerve showed extrinsic and intrinsic abnormality, proven to be endometriosis. Her symptoms improved, and she began gonadotropin-releasing hormone agonist therapy for further suppression. This very unusual case shows that endometriosis can affect the sciatic nerve over a range of territory inside and outside the pelvis, and that surgery must be appropriately directed to avoid negative exploration. Surgical decompression achieves good relief of symptoms, and medical therapy also allows sustained suppression of this disease.

Endometriosis, need for a multidisciplinary clinical setting: the internist's point of view

Endometriosis is a common condition characterized by proliferation of endometrial tissue outside the uterus, both in the pelvis and in other extra-pelvic sites. The clinical picture of endometriosis is widely heterogeneous. A correct diagnostic work-up of these patients can sometimes be very difficult, since there are a number of gynecological, intestinal and systemic diseases mimicking endometriosis, as well as other conditions that could be associated with or are a consequence of this disorder. Therefore, multidisciplinary care should be encouraged to ensure correct evaluation and improve the management of these patients.

Generalized hyperalgesia in women with endometriosis and its resolution following a successful surgery

Although pains of various kinds top the list of complaints from women with endometriosis and are the most debilitating of the disease, little is known about the mechanism/mechanisms of endometriosis-associated pains. To test the hypothesis that women with endometriosis have generalized hyperalgesia which may be alleviated by a successful surgery, we recruited 100 patients with surgically and histologically confirmed endometriosis and 70 women without, and tested their responses to pain stimulations. Before the surgery, all patients rated their dysmenorrhea severity by Visual Analog scale (VAS) and went through an ischemic pain test (IPT) and an electrical pain test (EPT). The controls were also administrated with IPT/EPT. Three and 6 months after surgery, all patients were administrated with IPT/EPT and rated their severity of dysmenorrhea. We found that patients with endometriosis had significantly higher IPT VAS scores and lower EPT pain threshold than controls, but after surgery their IPT scores and EPT pain threshold were significantly and progressively improved, along with their dysmenorrhea severity. Thus, we conclude that women with endometriosis have generalized hyperalgesia, which was alleviated by surgery. Consequently, central sensitization may be a possible mechanism underlying various forms of pain associated with endometriosis, and its recognition should have important implications for the development of novel therapeutics and better clinical management of endometriosis.

Role of mast cell activation in inducing microglial cells to release neurotrophin

The brain-derived neurotrophic factor (BDNF) plays a critical role in pain hypersensitivity. BDNF is the ligand of P2X4 receptors (P2X4R) in the microglia. The causative factors involving the P2X4R over expression in the microglia remains unclear. Mast cell activation has a close relation with pain hypersensitivity. However, the underlying mechanism between mast cell activation and pain hypersensitivity is unknown. The present study aimed to elucidate the mechanism by which mast cell activation promoted the expression of P2X4R in the microglia. The results of present study showed that mast cell activation markedly promoted the expression of P2X4R and BDNF in microglial cells, which significantly enhanced the release of BDNF from microglial cells upon exposure to adenosine triphosphate. Mast cell-derived tryptase activated PAR2 that resulted in promoting the expression of P2X4R in microglial cells. Pretreatment with antibodies against tryptase or PAR2, or using tryptase-deficient HMC-1 cells or PAR2-deficient microglial cells abolished the increase in P2X4R expression and BDNF release. Increase in mitogen activated protein kinase phosphorylation was observed in the processes of mast cell-induced BDNF release and P2X4R expression. We conclude that mast cell activation has the capacity to promote the expression of P2X4R and BDNF in microglial cells.

Dehydroepiandrosterone to induce murine models for the study of polycystic ovary syndrome

During the last decade a battery of animal models used for the study of polycystic ovary syndrome (PCOS) have allowed a focus on different aspects of the pathology. Since dehydroepiandrosterone (DHEA) was found to be one of the most abundant circulating androgens in women with PCOS, a rodent model showing the salient features found in women with PCOS was developed by the injection of DHEA. Although insulin-sensitizing agents, such as biguanides, are clinically used in the treatment of diabetes and PCOS, the complete understanding of their mechanisms of action remains unknown. The present review discusses the molecular mechanisms involved in the development of PCOS by using the DHEA-PCOS murine model and analyzes the role of the biguanide metformin as treatment.