Abstract

Abstract Introduction Localized provoked vulvodynia (LPV) is a chronic condition in which patients experience disabling pain in the vulvar vestibule. This condition’s mechanisms are poorly understood, and the lack of adequate treatment reflects the misunderstanding of the disease’s origins. Many LPV patients attempt to treat their pain with NSAIDS, but their use has been clinically shown to be ineffective against LPV associated vulvar pain. Recent evidence, utilizing fibroblasts isolated from vestibular and vulvar tissue of LPV patients, supports a link between inflammation and symptomology of LPV. These fibroblasts have shown to be sensitive to pro-inflammatory stimuli and overproduce inflammatory mediators such as Interleukin-6 (IL-6) and Prostaglandin E2 (PGE2). Increased production of IL-6 and PGE2 correlates with decreased pain thresholds, endorsing these levels as a surrogate measure for pain. Lipidomic data collected via mass spectroscopy also demonstrates LPV fibroblast strains have dysregulated arachidonic acid metabolism, resulting in an imbalance in pro-resolving lipids. Utilizing this fibroblast model, different cyclooxygenase (COX) inhibitors were used to better illuminate the mechanism behind fibroblast inflammation in LPV. Objective Using a fibroblast cell model, we set out to better understand pathophysiology of LPV and use that information to guide development of effective and pragmatic medical treatments. Methods Fibroblast strains were generated from vulvar and vestibular tissue samples of LPV patients and non-LPV age and race-matched controls. These cells were then treated with Interleukin 1 beta (IL-1β), selective cyclooxygenase-1 inhibitor (SC560), celecoxib (selective COX-2 inhibitor), and ibuprofen (nonselective COX inhibitor) to investigate differences in cellular response when blocking different enzymes in the inflammatory pathway. IL-1β is known to induce IL-6 and PGE2 which acted as a positive control. Results were then quantified via ELISA assay. Results Vestibular and vulvar tissues showed an increase in IL-6 and PGE2 production following treatment with IL-1B. When concurrently treated with IL-1B (to stimulate inflammation) and SC560 (to inhibit COX-1 signaling) ELISA analysis showed a significant decrease in PGE2. A significant PGE2 decrease was shown with concurrent IL-1B/Ibuprofen treatment as well as with IL-1B/Celecoxib treatments. In all three cases, IL-6 signaling was generally not decreased, while PGE2 was decreased, but not to baseline levels. Ibuprofen treatment in fact showed a trend towards increased IL-6 production. Conclusions Fibroblast response to inflammation in the case of LPV is complex. COX inhibitors do not fully inhibit the pain signaling that contributes to the symptomology of LPV patients (IL-6 production remains elevated). NSAIDs leave patients with dysregulated inflammation cascades, which does not remediate pain. Future areas of study for pharmaceutical targets include investigating lipid regulation, other pain signaling mechanisms, such as transient receptor potential cation channel subfamily V member 4 (TRPV4), and combination topical NSAID use to create more appropriate and robust treatment for patients with LPV. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: SPM Therapeutics.