Vestibulodynia At High Resolution: Omics Approach to Improve Diagnosis

Overview

According to recent nomenclature, vulvodynia is vulvar pain without a clear identifiable cause persisting for at least 3-months and distinguished from vulvar pain caused by a specific disorder (inflammatory, neoplastic, traumatic). Vulvodynia can be provoked (when the pain is felt after touching the area), or unprovoked (pain is constant). Localized provoked vulvodynia of the vestibule, known as vestibulodynia (VBD), is the most common manifestation of the disease (about 80%). Data collected suggests that up to 16% of women, particularly sexually active reproductive-aged women, suffers from this condition. Despite affecting almost 1 out of 8 women of all ages, vulvodynia remains completely unacknowledged to the most. These data highlight that VBD cannot be considered a rare disease, but it rather is a high frequency women's health condition, albeit neglected and hard to diagnose because of a lack of obvious markers. Despite the paucity of molecular data, studies about pathogenesis of VBD have highlighted several risk factors including inflammation, recurrent vulvovaginal infections and microbiota dysfunction, mucosal nerve fiber proliferation, hormonal alterations, pelvic floor muscle dysfunction, central pain mechanisms, and genetic factors. A recent study has highlighted that, compared to healthy controls, women with VBD demonstrated differences primarily in vaginal (but not plasma) concentrations of metabolites of the sphingolipid signaling pathways, suggesting localized effects in vagina and vulvar vestibule rather than systemic effects. The current prevalent theory on the etiology of VBD is that during or after an initial and persistent vulvovaginal insult (infection, microtrauma, allergic reaction), a "susceptible" individual is then unable to successfully clear the inflammation process that alters and sensitizes the neural tissue in the vestibular area, resulting in localized allodynia and hyperalgesia. The under-diagnosis of VBD is the result of different factors including practical, cultural, sociological and psychological ones. The women with VBD confirmed that healthcare provider knowledge and attitudes as well as system challenges (specialist and allied healthcare provider availability) are major barriers to timely diagnosis, mainly due to lack of diagnostic tests. For instance, many patients do not seek treatment due to feelings of inadequacy, invalidation, isolation or guilt. This attitude also has a cultural background that is rooted in shame, in the endurance of pain, in embarrassment and resulting silence of patients, dismissal of vulvar pain as a "psychological disorder" by clinicians have resulted in widespread ignorance about this disabling condition. Finally, one of the most important, and doubtlessly the easiest one to solve, is the lack of either molecular or cellular markers of the disease itself. Unfortunately the VBD diagnosis always comes too late, when the mechanism of aberrant immune response already has caused the irreversible nervous sprouting in the vulvar vestibule and the chronicization of the symptoms has already happened. This delayed diagnosis increases the women's risk for sexual dysfunction and diminishes their quality of life. The VBD diagnosis is generally a diagnosis of exclusion, where basically all other possible differential diagnoses have been excluded and this is what is "left over". Many markers of inflammation were investigated without significant results, likely because the method employed in the study was focused on few pre-selected targets and an unbiased analysis has not been performed, yet. For all these reasons, the search for suitable diagnostic markers of VBD remains a high but unmet research priority. In the NGS era the absence of genomic study of VBD is despicable. RNA-sequencing of vestibule vaginae (vestibular) cell swab is a pain-free method that we already tested and could allow the identification of diagnostic markers of VBD for the development and the optimization of a reliable and quantifiable diagnostic test. In this context we plan to perform transcriptomic analysis integrated with the state-of-the-art single cell omic analysis on VBD patients and healthy controls to unbiasedly identify specific VBD markers. Moreover, considering the different pathogenesis and the range of symptoms and severity of the disease, with these markers we also aim at stratifying different groups of VBD. This stratification will lay the foundation for further studies to move patients towards a real personalized medicine. This analysis has never been performed on VBD patients with this global approach and at such high resolution. The results of our project will help the clinicians in VBD diagnosis, in therapy direction and in the earlier identification of patients with higher risk to develop chronic VBD, thus helping to build a preventive strategy to avoid the progression and chronicization of the symptoms