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. Methods In a control matched study, primary human fibroblast strains were generated from biopsies collected from localized provoked vulvodynia (LPV) cases and 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 pro-inflammatory/pain-associated interleukin 6 (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 versus 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 NFκB (pro-inflammatory transcription factor) nearly abrogated IL-6 and PGE2 production induced by C. albicans, in keeping with observations that Dectin-1 signals through the NFκB pathway. Conclusion These findings implicate that a fibroblast-mediated pro-inflammatory 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.

Fibroblast strains were derived from two regions of the lower genital tract of localized provoked vulvodynia (LPV) cases and pain-free controls. Sixteen strains were derived from four cases and four controls, age and race matched, following pre-sampling mechanical pain threshold assessments. Strains were challenged with six separate stimuli: live yeast species (C. albicans, C. glabrata, C. tropicalis, and S. cerevisiae), yeast extract (zymosan), or inactive vehicle. Production of prostaglandin E2 (PGE2) and interleukin-6 (IL-6) were pro-inflammatory response measures. Highest IL-6 and PGE2 occurred with vestibular strains following C. albicans, C. glabrata, and zymosan challenges, resulting in the ability to significantly predict IL-6 and PGE2 production by genital tract location. Following C. albicans and C. glabrata challenge of all sixteen fibroblast strains, adjusting for dual sampling of subjects, PGE2 and IL-6 production significantly predicted the pre-sampling pain threshold from the genital tract site of sampling. At the same location of pain assessment and fibroblast sampling, in situ immunohistochemical (IHC)(+) fibroblasts for IL-6 and Cox-2 were quantified microscopically. The correlation between IL-6 production and IL-6 IHC(+) was statistically significant yet biological significance is unknown because of the small number of IHC(+) IL-6 fibroblasts identified. A low fibroblast IL-6 IHC(+) count may result from most IL-6 produced by fibroblasts existing in a secreted, extracellular state. Enhanced, site-specific, innate immune responsiveness to yeast pathogens by fibroblasts may be an early step in LPV pathogenesis. Fibroblast strain testing may offer an attractive/objective marker of LPV pathology in women with vulvodynia of inflammatory origin.

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Localized provoked vulvodynia (LPV) is a common, chronic, and disabling condition; patients experience profound pain and a diminished quality of life. The etiologic 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 pro-inflammatory stimuli and copiously produce pain-associated pro-inflammatory 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. NFkB (already targeted clinically) or other inflammatory components may be suitable therapeutic targets.

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 NFκB signaling (a major inflammatory pathway), while 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/pro-pain stimuli, we move closer to understanding the origins of chronic vulvar pain and identifying new therapeutic targets, knowledge which could significantly improve patient care.