Site-specific mesenchymal control of inflammatory pain to yeast challenge in vulvodynia-afflicted and pain-free women

Localized provoked vulvodynia as an immune-mediated inflammatory disease: rationale for a new line of research

Localized provoked vulvodynia (LPV), also called vulvar vestibulitis or provoked vestibulodynia, is a major cause of dyspareunia that severely impacts sexual health. At the tissue level, lymphocytic inflammation and hyperinnervation are characteristic pathological features, explaining the main symptoms and signs. A recent experimental animal study suggests that the histopathological findings of LPV may be due to mucosal CD4 Th17 immune responses to microbial antigens. We hypothesize that LPV is an immune-mediated inflammatory disease and challenge the concept of LPV as a chronic pain syndrome of unknown cause. Since most treatment modalities currently used in LPV are no better than placebo, we therefore warrant future research investigating the possible presence of CD4 Th17 cells and IL17 cytokine in affected tissues together with treatment trials that include inhibitors of the IL17 pathway.

Treponema pallidum-induced prostaglandin E2 secretion in skin fibroblasts leads to neuronal hyperpolarization: A cause of painless ulcers

BACKGROUND

Primary syphilis is characterized by painless ulcerative lesions in the genitalia, the aetiology of painless remains elusive.

OBJECTIVES

To investigate the role of Treponema pallidum in painless ulcer of primary syphilis, and the mechanisms underlying painless ulcers caused by T. pallidum.

METHODS

An experimental rabbit model of primary syphilis was established to investigate its effects on peripheral nerve tissues. Human skin fibroblasts were used to examine the role of T. pallidum in modulating neurotransmitters associated with pain and to explore the signalling pathways related to neurotransmitter secretion by T. pallidum in vitro.

RESULTS

Treponema pallidum infection did not directly lead to neuronal damage or interfere with the neuronal resting potential. Instead, it facilitated the secretion of prostaglandin E2 (PGE2) through endoplasmic reticulum stress in both rabbit and human skin fibroblasts, and upregulation of PGE2 induced the hyperpolarization of neurones. Moreover, the IRE1α/COX-2 signalling pathway was identified as the underlying mechanism by which T. pallidum induced the production of PGE2 in human skin fibroblasts.

CONCLUSION

Treponema pallidum promotes PGE2 secretion in skin fibroblasts, leading to the excitation of neuronal hyperpolarization and potentially contributing to the pathogenesis of painless ulcers in syphilis.

Exploring Localized Provoked Vulvodynia: Insights from Animal Model Research

Provoked vulvodynia represents a challenging chronic pain condition, characterized by its multifactorial origins. The inherent complexities of human-based studies have necessitated the use of animal models to enrich our understanding of vulvodynia's pathophysiology. This review aims to provide an exhaustive examination of the various animal models employed in this research domain. A comprehensive search was conducted on PubMed, utilizing keywords such as "vulvodynia", "chronic vulvar pain", "vulvodynia induction", and "animal models of vulvodynia" to identify pertinent studies. The search yielded three primary animal models for vulvodynia: inflammation-induced, allergy-induced, and hormone-induced. Additionally, six agents capable of triggering the condition through diverse pathways were identified, including factors contributing to hyperinnervation, mast cell proliferation, involvement of other immune cells, inflammatory cytokines, and neurotransmitters. This review systematically outlines the various animal models developed to study the pathogenesis of provoked vulvodynia. Understanding these models is crucial for the exploration of preventative measures, the development of novel treatments, and the overall advancement of research within the field.

Inflammation, lipid dysregulation, and transient receptor potential cation channel subfamily V member 4 signaling perpetuate chronic vulvar pain

ABSTRACT

Localized provoked vulvodynia is characterized by chronic vulvar pain that disrupts every aspect of the patient's life. Pain is localized to the vulvar vestibule, a specialized ring of tissue immediately surrounding the vaginal opening involved in immune defense. In this article, we show inflammation is the critical first step necessary for the generation of pain signals in the vulva. Inflammatory stimuli alone or combined with the transient receptor potential cation channel subfamily V member 4 (TRPV4) agonist 4α-phorbol 12,13-didecanoate stimulate calcium flux into vulvar fibroblast cells. Activity is blocked by the TRPV4 antagonist HC067047, denoting specificity to TRPV4. Using lipidomics, we found pro-resolving lipids in the vulvar vestibule were dysregulated, characterized by a reduction in pro-resolving mediators and heightened production of inflammatory mediators. We demonstrate specialized pro-resolving mediators represent a potential new therapy for vulvar pain, acting on 2 key parts of the disease mechanism by limiting inflammation and acutely inhibiting TRPV4 signaling.

Quality of life in women with chronic recurrent vulvovaginal candidosis: A sub-analysis of the prospective multicentre phase IIb/III Prof-001 study

BACKGROUND

Chronic recurrent vulvovaginal candidosis (RVVC), defined as three or more episodes of vulvovaginal candidosis per year, significantly impairs quality of life (QoL) and sexual health.

OBJECTIVES

The primary objective of this study was to assess health-related QoL in women with RVVC using validated questionnaires before and after treatment. The secondary objective was to analyse the effect of RVVC on women's sexual health.

PATIENTS/METHODS

This was a sub-analysis of a randomised, controlled, double-blinded study titled 'A phase IIb/III, parallel-arm, randomized, active-controlled, double-blind, double-dummy, multicenter, non-inferiority study in patients with recurrent vulvovaginal candidosis to compare the clinical efficacy, safety and tolerability of topically administered ProF-001 (Candiplus®) to oral fluconazole, which was conducted at 35 study sites in Austria, Poland and Slovakia. QoL was assessed using the European Quality of Life (EQ) five-dimension five-level scale (EQ-5D-5L) and visual analogue scale (EQ-VAS) questionnaires, followed by specific questions regarding sexuality.

RESULTS

From 2019 to 2021, 360 of 432 (83.3%) women with RVVC had accomplished a 6-months maintenance treatment and were enrolled in this sub-analysis. The EQ-5D-5L and EQ-VAS scores demonstrated improved QoL in 137 (65.2%) and 159 (75.4%) women after 6 months of maintenance treatment. Each individual aspect of sexual health significantly improved (all p < .05). A reduction in pain frequency during or after sexual intercourse in the 6-month period occurred in 124 (66.3%) women.

CONCLUSIONS

Women with RVVC had high QoL and sexual health impairment; however, a 6-months maintenance treatment resulted in effective improvement in QoL and sexual health.

The Association Between Immune-Related Conditions Across the Life-Course and Provoked Vulvodynia

Vulvodynia, impacts up to 8% of women by age 40, and is hypothesized to manifest through an altered immune-inflammatory response. To test this hypothesis, we identified all women born in Sweden between 1973 and 1996 diagnosed with localized provoked vulvodynia (N76.3) and/or vaginismus (N94.2 or F52.5) between 2001 and 2018. We matched each case to two women from the same birth year with no vulvar pain ICD codes. As a proxy for immune dysfunction, we used Swedish Registry data to capture 1) immunodeficiencies, 2) single organ and multiorgan autoimmune conditions, 3) allergy and atopies, and 4) malignancies involving immune cells across the life course. Women with vulvodynia, vaginismus or both were more likely to experience immune deficiencies (OR 1.8, 95% CI, 1.2-2.8), single organ (OR 1.4, 95% CI, 1.2-1.6) and/or multi-organ (OR 1.6, 95% CI, 1.3-1.9) immune disorders, and allergy/atopy conditions (OR 1.7, 95% CI, 1.6-1.8) compared to controls. We observed greater risk with increasing numbers of unique immune related conditions (1 code: OR = 1.6, 95% CI, 1.5-1.7; 2 codes: OR = 2.4, 95% CI, 2.1-2.9; 3 or more codes: OR = 2.9, 1.6-5.4). These findings suggest that women with vulvodynia may have a more compromised immune system either at birth or at points across the life course than women with no vulvar pain history. PERSPECTIVE: Women with vulvodynia are substantially more likely to experience a spectrum of immune related conditions across the life course. These findings lend support to the hypothesis that chronic inflammation initiates the hyperinnervation that causes the debilitating pain in women with vulvodynia.

Inflammation, lipids, and pain in vulvar disease

Localized provoked vulvodynia (LPV) affects ∼14 million people in the US (9% of women), destroying lives and relationships. LPV is characterized by chronic pain (>3 months) upon touch to the vulvar vestibule, which surrounds the vaginal opening. Many patients go months or years without a diagnosis. Once diagnosed, the treatments available only manage the symptoms of disease and do not correct the underlying problem. We have focused on elucidating the underlying mechanisms of chronic vulvar pain to speed diagnosis and improve intervention and management. We determined the inflammatory response to microorganisms, even members of the resident microflora, sets off a chain of events that culminates in chronic pain. This agrees with findings from several other groups, which show inflammation is altered in the painful vestibule. The vestibule of patients is acutely sensitive to inflammatory stimuli to the point of being deleterious. Rather than protect against vaginal infection, it causes heightened inflammation that does not resolve, which coincides with alterations in lipid metabolism that favor production of proinflammatory lipids and not pro-resolving lipids. Lipid dysbiosis in turn triggers pain signaling through the transient receptor potential vanilloid subtype 4 receptor (TRPV4). Treatment with specialized pro-resolving mediators (SPMs) that foster resolution reduces inflammation in fibroblasts and mice and vulvar sensitivity in mice. SPMs, specifically maresin 1, act on more than one part of the vulvodynia mechanism by limiting inflammation and acutely inhibiting TRPV4 signaling. Therefore, SPMs or other agents that target inflammation and/or TRPV4 signaling could prove effective as new vulvodynia therapies.

Immune mechanisms in vulvodynia: key roles for mast cells and fibroblasts

Vulvodynia is a debilitating condition characterized by painful sensitivity to touch and pressure in the vestibular tissue surrounding the vaginal opening. It is often a "diagnosis of exclusion" of idiopathic pain made in the absence of visible inflammation or injury. However, the association between increased vulvodynia risk and a history of yeast infections and skin allergies has led researchers to explore whether immune mechanisms of dysregulated inflammation might underlie the pathophysiology of this chronic pain condition. Here we synthesize epidemiological investigations, clinical biopsies and primary cell culture studies, and mechanistic insights from several pre-clinical models of vulvar pain. Taken together, these findings suggest that altered inflammatory responses of tissue fibroblasts, and other immune changes in the genital tissues, potentially driven by the accumulation of mast cells may be key to the development of chronic vulvar pain. The association of increased numbers and function of mast cells with a wide variety of chronic pain conditions lends credence to their involvement in vulvodynia pathology and underscores their potential as an immune biomarker for chronic pain. Alongside mast cells, neutrophils, macrophages, and numerous inflammatory cytokines and mediators are associated with chronic pain suggesting immune-targeted approaches including the therapeutic administration of endogenous anti-inflammatory compounds could provide much needed new ways to treat, manage, and control the growing global pandemic of chronic pain.

Vestibular hyaluronic acid injection in provoked vestibulodynia patients and its effect on pain and sexual function: A preliminary report

OBJECTIVE

Provoked vestibulodynia (PVD) is a challenging and distressing problem for women. The aim of this study was to examine the effect of hyaluronic acid (HA) in the management of this condition.

METHOD

This is a retrospective review of 12 women diagnosed with PVD and treated with HA (19 mg/mL) applied, point-by-point, to the vestibular region at 2 mm intervals and at a depth of 0.5 mm. Women completed a pain VAS and a Female Sexual Function Index (FSFI) before and 45 days after treatment.

RESULTS

An improvement was observed both in mean FSFI scores (17.8 to 23.3; p = 0.003) and mean VAS scores (7.2 to 4.1; p = 0.002) after HA application respectively. However, on a telephone interview 3 months post treatment, five women (41.7 %) complained of recurrence of their dyspareunia.

CONCLUSION

HA is a promising management option in provoked vestibulodynia. However, further larger studies with possible alternative regimens and longer follow-up are required.

Fibroblasts: the neglected cell type in peripheral sensitisation and chronic pain? A review based on a systematic search of the literature

Chronic pain and its underlying biological mechanisms have been studied for many decades, with a myriad of molecules, receptors and cell types known to contribute to abnormal pain sensations. Besides an obvious role for neurons, immune cells like microglia, macrophages and T cells are also important drivers of persistent pain. While neuroinflammation has therefore been widely studied in pain research, there is one cell type that appears to be rather neglected in this context: the humble fibroblast. Fibroblasts may seem unassuming but actually play a major part in regulating immune cell function and driving chronic inflammation. Here, our aim was to determine the breadth and quality of research that implicates fibroblasts in chronic pain conditions and models.

OBJECTIVES

We set out to analyse the current literature on this topic-using systematic screening and data extraction methods to obtain a balanced view on what has been published.

METHODS

We categorised the articles we included-stratifying them according to what was investigated, the estimated quality of results and any common conclusions.

RESULTS

We found that there has been surprisingly little research in this area: 134 articles met our inclusion criteria, only a tiny minority of which directly investigated interactions between fibroblasts and peripheral neurons.

CONCLUSIONS

Fibroblasts are a ubiquitous cell type and a prominent source of many proalgesic mediators in a wide variety of tissues. We think that they deserve a more central role in pain research and propose a new, testable model of how fibroblasts might drive peripheral neuron sensitisation.

Specialized Pro-resolving Mediators Reduce Pro-nociceptive Inflammatory Mediator Production in Models of Localized Provoked Vulvodynia

Localized provoked vulvodynia (LPV) is the most common cause of chronic dyspareunia in premenopausal women, characterized by pain with light touch to the vulvar vestibule surrounding the vaginal opening. The devastating impact of LPV includes sexual dysfunction, infertility, depression, and even suicide. Yet, its etiology is unclear. No effective medical therapy exists; surgical removal of the painful vestibule is the last resort. In LPV, the vestibule expresses a unique inflammatory profile with elevated levels of pro-nociceptive proinflammatory mediators prostaglandin E2 (PGE2) and interleukin-6 (IL-6), which are linked to lower mechanical sensitivity thresholds. Specialized pro-resolving mediators (SPMs), lipids produced endogenously within the body, hold promise as an LPV treatment by resolving inflammation without impairing host defense. Ten of 13 commercially available SPMs reduced IL-6 and PGE2 production by vulvar fibroblasts, administered either before or after inflammatory stimulation. Using a murine vulvar pain model, coupling proinflammatory mediator quantification with mechanical sensitivity threshold determination, topical treatment with the SPM, maresin 1, decreased sensitivity and suppressed PGE2 levels. Docosahexaenoic acid, a precursor of maresin 1, was also effective in reducing PGE2 in vulvar fibroblasts and rapidly restored mouse sensitivity thresholds. Overall, SPMs and their precursors may be a safe and efficacious for LPV. Perspective: Vulvodynia, like many pain conditions, is difficult to treat because disease origins are incompletely understood. Here, we applied our knowledge of more recently discovered vulvodynia disease mechanisms to screen novel therapeutics. We identified several specialized pro-resolving mediators as likely potent and safe for treating LPV with potential for broader application.

Localized Provoked Vulvodynia-An Ignored Vulvar Pain Syndrome

Localized provoked vulvodynia (LPV) causes dyspareunia among reproductive aged women. We review the pathogenesis of LPV and suggest that LPV is an inflammatory pain syndrome of the vestibular mucosa triggered by microbial antigens in a susceptible host. Tissue inflammation and hyperinnervation are characteristic findings which explain symptoms and clinical signs. Education of health care providers of LPV is important since this condition is common, often unrecognized, and patients often become frustrated users of health care. Research is needed on the antigen triggers of the syndrome. Randomized clinical trials are needed to evaluate treatment modalities.

Generating primary murine vaginal fibroblast cell lines

Primary human vulvovaginal fibroblast cell lines are useful for studying biological mechanisms underlying genital pain, pelvic organ prolapse, and the spread of sexually transmitted infections. However, the vaginal biopsies necessary for establishing these cell lines are invasive and relatively difficult to obtain. Primary mouse fibroblast cell lines derived from pre-clinical animal models of these conditions can be used for better controlled experiments that can help us dissect disease mechanisms. To our knowledge, there are no published protocols for establishing primary murine vaginal fibroblast cell lines to date. Here, we describe a protocol for the establishment of murine vaginal fibroblast cell lines via enzymatic digestion of vaginal canal tissue. Cell lines generated using this method can be used for in vitro studies of these important structural cells in a variety of pre-clinical mouse models; such studies are required to identify and characterize relevant regulatory and therapeutic targets in a wide array of diseases of interest. As shown in our representative data, this protocol yields viable cell lines from ND4 Swiss outbred mice. These cells bear surface markers characteristic of fibroblasts and are capable of producing inflammatory cytokines in response to treatment with bacterial and yeast antigens in vitro.

Vulvodynia

Vulvodynia is a condition that occurs in 8-10% of women of all ages and is characterized by pain at the vulva that is present during sexual and/or non-sexual situations. Diagnosis is established through careful medical history and pelvic examination, including the cotton-swab test. The onset and maintenance of vulvodynia involves a complex interplay of peripheral and central pain mechanisms, pelvic floor muscle and autonomic dysfunction, anxiety, depression and childhood maltreatment as well as cognitive-affective, behavioural and interpersonal factors. Given the absence of empirically supported treatment guidelines, a stepwise approach of pelvic floor physical therapy and cognitive behavioural therapy as well as medical management is suggested, with surgery as the last option. Vulvodynia has a negative effect on the quality of life of women and their partners, and imposes a profound personal and societal economic burden. In addition, women with vulvodynia are more likely to report other chronic pain conditions, which further alters their quality of life. Future efforts should aim to increase girls', women's and healthcare professionals' education and awareness of vulvodynia, phenotype different subgroups of women based on biopsychosocial characteristics among more diverse samples, conduct longitudinal studies and improve clinical trial designs.

Emerging Evidence of Macrophage Contribution to Hyperinnervation and Nociceptor Sensitization in Vulvodynia

Vulvodynia is an idiopathic chronic pain disorder and a leading cause of dyspareunia, or pain associated with sexual intercourse, for women. The key pathophysiological features of vulvodynia are vaginal hyperinnervation and nociceptor sensitization. These features have been described consistently by research groups over the past 30 years, but currently there is no first-line recommended treatment that targets this pathophysiology. Instead, psychological interventions, pelvic floor physiotherapy and surgery to remove painful tissue are recommended, as these are the few interventions that have shown some benefit in clinical trials. Recurrence of vulvodynia is frequent, even after vestibulectomy and questions regarding etiology remain. Vestibular biopsies from women with vulvodynia contain increased abundance of immune cells including macrophages as well as increased numbers of nerve fibers. Macrophages have multiple roles in the induction and resolution of inflammation and their function can be broadly described as pro-inflammatory or anti-inflammatory depending on their polarization state. This state is not fixed and can alter rapidly in response to the microenvironment. Essentially, M1, or classically activated macrophages, produce pro-inflammatory cytokines and promote nociceptor sensitization and mechanical allodynia, whereas M2, or alternatively activated macrophages produce anti-inflammatory cytokines and promote functions such as wound healing. Signaling between macrophages and neurons has been shown to promote axonal sprouting and nociceptor sensitization. This mini review considers emerging evidence that macrophages may play a role in nociceptor sensitization and hyperinnervation relevant to vulvodynia and considers the implications for development of new therapeutic strategies.

Altered gray matter volume in sensorimotor and thalamic regions associated with pain in localized provoked vulvodynia: a voxel-based morphometry study

Multimodal neuroimaging studies provide support for a role of alterations in sensory processing circuits and endogenous pain modulatory systems in provoked vestibulodynia (PVD). In this study, we tested the hypotheses that PVD compared with healthy controls (HCs) would demonstrate gray matter volume (GMV) alterations in regions associated with sensorimotor, corticothalamic, and basal ganglia circuits. We also tested the replicability of previously reported gray matter increases in basal ganglia and hippocampal volumes in PVD vs HCs. In addition, disease specificity of GMV alterations were examined by comparing PVD with another chronic pain disorder. Finally, we examine whether GMV alterations are correlated with symptom measures. Structural magnetic resonance imaging was obtained in 119 premenopausal women (45 PVD, 45 HCs, and 29 irritable bowel syndrome [IBS]). A voxel-based morphometry analysis was applied to determine group differences in the hypothesized regions of interest. Compared with HCs, PVD women exhibited greater GMV in the basal ganglia, hippocampus, and sensorimotor cortices. Compared to patients with IBS, women with PVD had greater GMV in the hippocampus, and sensorimotor network, but lower GMV in the thalamus and precentral gyrus. Regional GMV alterations were associated with patient reports of pain during intercourse and muscle tenderness. The current findings provide further evidence that GMV is increased in PVD compared with HCs in several regions of the sensorimotor network and the hippocampus in patients with PVD. In addition, GMV distinct alterations in the sensorimotor network were identified between 2 pelvic pain disorders, PVD compared with IBS.

Candida tropicalis induces pro-inflammatory cytokine production, NF-κB and MAPKs pathways regulation, and dectin-1 activation

The prevalence of Candida infection induced by non-albicans Candida (NAC) species is increasing. However, as a common NAC species, C. tropicalis has received much less study in terms of host immunity than C. albicans has. In this study, we evaluated the pro-inflammatory cytokine responses evoked by C. tropicalis and determined whether dectin-1 and downstream NF-κB and mitogen-activated protein kinases (MAPKs) signaling pathways played roles in inflammation in human peripheral blood mononuclear cells (PBMCs) and THP-1 macrophage-like cells. Exposure of PBMCs and THP-1 macrophage-like cells to C. tropicalis led to the enhanced gene expression and secretion of TNF-α and IL-6 in a time- and dose-dependent manner. THP-1 macrophage-like cells being challenged by C. tropicalis resulted in the activation of the NF-κB, p38, and ERK1/2 MAPK signaling pathways. We also found that the expression of dectin-1 was increased with C. tropicalis treatment. These data reveal that dectin-1 may play a role in sensing the inflammation response induced by C. tropicalis and that NF-κB and MAPK are involved in the downstream signaling pathways in macrophages.

Toll-Like Receptor Signaling Contributes to Proinflammatory Mediator Production in Localized Provoked Vulvodynia

OBJECTIVES

Localized provoked vulvodynia (LPV) afflicts approximately 8% of women in the United States and represents a huge financial, physical, and psychological burden. Women with LPV experience intense pain localized to the vulvar vestibule (area immediately surrounding vaginal opening). We have identified mechanisms involved in the development of LPV whereby vulvar fibroblasts respond to proinflammatory stimuli to perpetuate an inflammatory response that causes pain. However, these mechanisms are not fully elucidated. Therefore, we explored the role of toll-like receptors (TLRs), a class of innate immune receptors that rapidly respond to microbial assaults.

MATERIALS AND METHODS

To determine whether TLRs are expressed by vulvar fibroblasts and whether these contribute to proinflammatory mediator production and pain in LPV, we examined TLR expression and innate immune responses in fibroblasts derived from painful vestibular regions compared with nonpainful external vulvar regions.

RESULTS

Human vulvar fibroblasts express functional TLRs that trigger production of inflammatory mediators associated with chronic pain. We focused on the TLR-7-imiquimod proinflammatory interaction, because imiquimod, a ligand of TLR-7, may exacerbate pain in women during treatment of human papillomavirus-associated disease.

CONCLUSIONS

Human vulvar fibroblasts express a broad spectrum of TLRs (a new finding). A significantly higher TLR-mediated proinflammatory response was observed in LPV case vestibular fibroblasts, and with respect to the imiquimod-TLR 7 interaction, development of chronic vestibular pain and inflammation may be a possible sequelae of treatment of vulvar human papillomavirus-associated disease. Suppressing enhanced TLR-associated innate immune responses to a spectrum of pathogen-associated molecular patterns may represent a new/effective therapeutic approach for vulvodynia.

Vulvodynia: a consideration of clinical and methodological research challenges and recommended solutions

Vulvodynia, an idiopathic chronic vulvar pain, is a prevalent genital pain condition that results in significant impairment to sexual, relational, and psychological functioning of affected women and their romantic partners. Despite its high prevalence, there remain gaps in knowledge and health care access for women coping with vulvodynia, given its varied clinical presentation and no widely accepted treatment protocol. The past several decades have seen important advancements in understanding vulvodynia and developing effective treatments; however, progress has been impeded due to clinical and methodological challenges in conducting research with this vulnerable population. This review presents a brief overview of vulvodynia correlates, consequences, etiology, and treatment, and then turns its attention to considering the clinical and methodological challenges that hinder vulvodynia research. Identifying these barriers alongside potential mitigating solutions is essential to developing empirically supported treatments for all women affected by vulvodynia, across all age and minority groups. Potential solutions will require researchers to broaden eligibility criteria, examine subgroups of women, and expand definitions of treatment outcomes, and may be best facilitated by more active collaboration among research groups and across relevant disciplines. Engagement in these solutions may contribute to more representative findings and the development and dissemination of empirically based treatment options for this complex pain condition.

Recurrent Yeast Infections and Vulvodynia: Can We Believe Associations Based on Self-Reported Data?

OBJECTIVE

We determined whether self-reported new or recurrent yeast infections were a risk factor for and/or consequence of vulvodynia and then determined the extent to which various levels of misclassification of self-reported yeast infections influenced these results.

MATERIALS AND METHODS

In this case-control study we retrospectively assessed self-reported new and recurrent yeast infections prior and subsequent to first vulvar pain onset among 216 clinically confirmed cases and during a similar time period for 224 general population controls.

RESULTS

A history of >10 yeast infections before vulvodynia onset was strongly but imprecisely associated with currently diagnosed vulvodynia after adjustment for age, age at first intercourse, and history of urinary tract infections [adjusted odds ratio = 5.5, 95% confidence interval (CI) 1.7-17.8]. Likewise, a history of vulvodynia was associated with a twofold risk of subsequent new or recurrent onset of yeast infections after adjustment for age, age at first intercourse, and history of yeast infections before vulvodynia onset (comparable time period among controls, 95% CI 1.5-2.9). Bias analyses showed that our observed associations were an underestimation of the true association when nondifferential misclassification of self-reported yeast infections and certain differential misclassification scenarios were present. However, if women with vulvodynia more frequently misreported having them when they truly did not, our observed associations were an overestimate of the truth.

CONCLUSIONS

There appears to be a positive relationship between yeast infections preceding and following the diagnosis of vulvodynia, but this relationship varies from strong to nonexistent depending on the relative accuracy of the recalled diagnosis of yeast infections among cases and controls. To better understand the bidirectional associations between yeast infections and vulvodynia, future validation studies are needed to determine the extent to which misclassification of self-reported yeast infections differs between women with and without vulvodynia.

Elevated nitric oxide in recurrent vulvovaginal candidiasis - association with clinical findings

INTRODUCTION

Recurrent vulvovaginal candidiasis is defined as having three to four episodes per year and causes substantial suffering. Little is known about the mechanisms leading to relapses in otherwise healthy women. Nitric oxide is part of the nonspecific host defense and is increased during inflammation. Nitric oxide levels were measured and the expression of inducible nitric oxide synthase was analyzed in the vagina during an acute episode of recurrent vulvovaginal candidiasis and after treatment with fluconazole.

MATERIAL AND METHODS

Twenty-eight women with symptoms of recurrent vulvovaginal candidiasis were enrolled together with 31 healthy controls. Nitric oxide was measured with an air-filled 25-mL silicon catheter balloon incubated in the vagina for five minutes and then analyzed by chemiluminescence technique. Vaginal biopsies were analyzed for the expression of inducible nitric oxide synthase. Symptoms and clinical findings were surveyed using a scoring system. The measurements and biopsies were repeated in patients after six weeks of fluconazole treatment.

RESULTS

Nitric oxide levels were increased during acute infection (median 352 ppb) compared with controls (median 6 ppb), p < 0.0001. The levels decreased after treatment (median 18 ppb) but were still higher than in controls. Increased expression of inducible nitric oxide synthase was observed in the epithelial basal layer in patients before and after treatment compared with controls. Before treatment, there were positive correlations between nitric oxide and symptom (r_s  = 0.644) and examination scores (r_s  = 0.677), p < 0.001.

CONCLUSIONS

Nitric oxide is significantly elevated in patients with recurrent vulvovaginal candidiasis during acute episodes of infection and decreases after antifungal treatment. The results illustrate the pronounced inflammatory response in recurrent vulvovaginal candidiasis correlating to symptoms of pain and discomfort.

Immune activation enhances epithelial nerve growth in provoked vestibulodynia

BACKGROUND

Provoked vestibulodynia manifests as allodynia of the vulvar vestibular mucosa. The exact mechanisms that result in altered pain sensation are unknown. Recently, we demonstrated the presence of secondary lymphoid tissue, which is the vestibule-associated lymphoid tissue in the vestibular mucosa, and showed that this tissue becomes activated in provoked vestibulodynia.

OBJECTIVE

The purpose of this study was to examine whether expression of intraepithelial nerve fibers and nerve growth factor are related to immune activation in provoked vestibulodynia.

STUDY DESIGN

Vestibular mucosal specimens were obtained from 27 patients with severe provoked vestibulodynia that was treated by vestibulectomy and from 15 control subjects. We used antibodies against the protein gene product 9.5, the neuron specific neurofilament, and nerve growth factor for immunohistochemistry to detect intraepithelial nerve fibers and nerve growth factor expressing immune cells in the vestibular mucosa. For intraepithelial nerve fibers, we determined their linear density (fiber counts per millimeter of the outer epithelial surface, protein gene product 9.5) or presence (neuron specific neurofilament). Nerve growth factor was analyzed by counting the staining-positive immune cells. Antibodies against CD20 (B lymphocytes) and CD3 (T lymphocytes) were used to identify and locate mucosal areas with increased density of lymphocytes and the presence of germinal centers (ie, signs of immune activation). B-cell activation index was used to describe the overall intensity of B-cell infiltration.

RESULTS

We found more protein gene product 9.5-positive intraepithelial fibers in vestibulodynia than in the control samples (6.3/mm [range, 0.0-15.8] vs 2.0/mm [range, 0.0-12.0]; P=.006). Neuron specific neurofilament -positive intraepithelial fibers were found in 17 of 27 vestibulodynia cases (63.0%) and in none of the control cases. Protein gene product 9.5-positive intraepithelial fibers were more common in samples with more pronounced immune activation. The density of these fibers was higher in samples with than without germinal centers (6.1/mm [range, 4.3-15.8] vs 3.0/mm [range, 0.0-13.4]; P=.020). A positive correlation between the fiber density and B-cell activation index score of the sample was found (Spearman's Rho, 0.400; P=.004; R²=0.128). No significant difference, however, was found in the density or presence of nerve fibers between samples with high and low T-cell densities. We identified areas of minor and major vestibular glands in 16 of the patient samples and in 1 control sample. Protein gene product 9.5-positive nerve fibers were found more often in glandular epithelium surrounded by B-cell infiltration than in glands without B cells (P=.013). Also, the presence of neuron specific neurofilament-positive fibers in glandular epithelium was associated with B-cell infiltrates (P=.053). Nerve growth factor-positive immune cells were more common in mucosal areas with than without B-cell infiltration and intraepithelial nerve fibers.

CONCLUSION

Excessive epithelial nerve growth in provoked vestibulodynia is associated with increased B-cell infiltration and the presence of germinal centers. This supports the fundamental role of immune activation in provoked vestibulodynia.

Recent advances in understanding provoked vestibulodynia

Vulvodynia refers to pain in the vulva of at least 3 months’ duration in the absence of a recognized underlying cause. Provoked, localized vestibulodynia is the term used to describe superficial pain confined to the vulvar vestibule, provoked by touch. This review will focus on provoked vestibulodynia with regard to its suggested causative factors and will discuss the role of inflammation, vulvovaginal infections, mucosal nerve fiber proliferation, hormonal associations, central pain mechanisms, pelvic floor muscle dysfunction, and genetic factors.

Clinical observations, epidemiological studies, and data from basic research emphasize the heterogeneity of vulvar pain syndromes. There is a critical need to perform prospective, longitudinal studies that will allow better diagnostic criteria and subgrouping of patients that would lead to improvements in our understanding of provoked vestibulodynia and its treatment.

A Role for Bradykinin Signaling in Chronic Vulvar Pain

Chronic vulvar pain is alarmingly common in women of reproductive age and is often accompanied by psychological distress, sexual dysfunction, and a significant reduction in quality of life. Localized provoked vulvodynia (LPV) is associated with intense vulvar pain concentrated in the vulvar vestibule (area surrounding vaginal opening). To date, the origins of vulvodynia are poorly understood, and treatment for LPV manages pain symptoms, but does not resolve the root causes of disease. Until recently, no definitive disease mechanisms had been identified; our work indicates LPV has inflammatory origins, although additional studies are needed to understand LPV pain. Bradykinin signaling is one of the most potent inducers of inflammatory pain and is a candidate contributor to LPV. We report that bradykinin receptors are expressed at elevated levels in LPV patient versus healthy control vestibular fibroblasts, and patient vestibular fibroblasts produce elevated levels of proinflammatory mediators with bradykinin stimulation. Inhibiting expression of one or both bradykinin receptors significantly reduces proinflammatory mediator production. Finally, we determined that bradykinin activates nuclear factor (NF)κB signaling (a major inflammatory pathway), whereas inhibition of NFκB successfully ablates this response. These data suggest that therapeutic agents targeting bradykinin sensing and/or NFκB may represent new, more specific options for LPV therapy.

PERSPECTIVE

There is an unmet need for the development of more effective vulvodynia therapies. As we explore the mechanisms by which human vulvar fibroblasts respond to proinflammatory/propain stimuli, we move closer to understanding the origins of chronic vulvar pain and identifying new therapeutic targets, knowledge that could significantly improve patient care.

Vulvodynia and Irritable Bowel Syndrome Treated With an Elimination Diet: A Case Report

BACKGROUND

A 28-y-old athletic woman was diagnosed with vulvodynia and long-term irritable bowel syndrome (IBS) and was treated successfully with an elimination diet.

CASE/INTERVENTION

In the course of 6 mo of nutrition therapy utilizing an elimination diet, specific foods triggering abdominal bloating and pain, and vulvovaginal pain were identified. In the course of treatment, the nutrition and supplement program instituted for this patient allowed her to return to her prior functional level without pain (including sexual activity) and resolution of her IBS. She has remained symptom free for at least 6 mo posttreatment.

CONCLUSION

This case demonstrates the potential usefulness of incorporating a customized nutritional approach to determine proinflammatory foods in patients with chronic vulvodynia and overlapping IBS. Long-term pain resolution and healthy sexual functioning in this case was supported by food elimination and nutritional supplementation.

A review of the available clinical therapies for vulvodynia management and new data implicating proinflammatory mediators in pain elicitation

Localised provoked vulvodynia (LPV) is a common, chronic, and disabling condition: patients experience profound pain and a diminished quality of life. The aetiologic origins of vulvodynia are poorly understood, yet recent evidence suggests a link to site-specific inflammatory responses. Fibroblasts isolated from the vestibule of LPV patients are sensitive to proinflammatory stimuli and copiously produce pain-associated proinflammatory mediators (IL-6 and PGE₂ ). Although LPV is a multifactorial disorder, understanding vulvar inflammation and targeting the inflammatory response should lead to treatment advances, especially for patients exhibiting signs of inflammation. NFκB (already targeted clinically) or other inflammatory components may be suitable therapeutic targets.

TWEETABLE ABSTRACT

Vulvodynia is a poorly understood, prevalent, and serious women's health issue requiring better understanding to improve therapy.

Vulvar vestibulodynia: strategies to meet the challenge

Vulvodynia is a condition that affects approximately 8% to 12% of women during their lifetimes. Vulvar vestibulodynia (VVD), the most common form of this condition, is characterized by pain with touch at the vulvar vestibule and resulting entryway dyspareunia. Studies suggest a multifactorial etiology; hormonal effects, muscle dysfunction, personality, psychosocial factors, and inflammatory mediators may all play some role in the development of this condition. Both peripheral and central sensitization to pain have been implicated in the development of enhanced pain experienced by women with VVD. Recommendations for the treatment of this condition exist; however, treatments of this condition have not been well studied. Few prospective placebo-controlled trials exist, and many of those that do have failed to show clinically relevant efficacy associated with traditional therapies. New studies into the etiology of this condition, as well as potential new therapies, are emerging, but the optimal approach has yet to be defined. Proper vulvar hygiene is recommended, and traditional therapies such as topical medications and centrally acting oral medications may continue to play a role in treatment. Newer studies elucidating the effects of personality and cognitive factors as well as pelvic floor muscle dysfunction in the development of this condition lend support for the inclusion of cognitive behavioral therapy and physical therapy/surface electromyographic biofeedback in the treatment regimen. Surgery for this condition exists, with success rates of 60% to 90%; however, it is recommended only in cases that have failed to respond to traditional therapy.

Identification of novel mechanisms involved in generating localized vulvodynia pain

OBJECTIVE

Our goal was to gain a better understanding of the inflammatory pathways affected during localized vulvodynia, a poorly understood, common, and debilitating condition characterized by chronic pain of the vulvar vestibule.

STUDY DESIGN

In a control matched study, primary human fibroblast strains were generated from biopsies collected from localized provoked vulvodynia (LPV) cases and from age- and race-matched controls. We then examined intracellular mechanisms by which these fibroblasts recognize pathogenic Candida albicans; >70% of vulvodynia patients report the occurrence of prior chronic Candida infections, which is accompanied by localized inflammation and elevated production of proinflammatory/pain-associated interleukin (IL)-6 and prostaglandin E2 (PGE2). We focused on examining the signaling pathways involved in recognition of yeast components that are present and abundant during chronic infection.

RESULTS

Dectin-1, a surface receptor that binds C albicans cell wall glucan, was significantly elevated in vestibular vs external vulvar cells (from areas without pain) in both cases and controls, while its abundance was highest in LPV cases. Blocking Dectin-1 signaling significantly reduced pain-associated IL-6 and PGE2 production during the response to C albicans. Furthermore, LPV patient vestibular cells produced inflammatory mediators in response to low numbers of C albicans cells, while external vulvar fibroblasts were nonresponsive. Inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (proinflammatory transcription factor) nearly abrogated IL-6 and PGE2 production induced by C albicans, in keeping with observations that Dectin-1 signals through the nuclear factor kappa-light-chain-enhancer of activated B cells pathway.

CONCLUSION

These findings implicate that a fibroblast-mediated proinflammatory response to C albicans contributes to the induction of pain in LPV cases. Targeting this response may be an ideal strategy for the development of new vulvodynia therapies.