Identifying therapeutic targets for vulvodynia

描述(由申请者提供)：据估计，美国有600万女性患有外阴疼痛。激惹的前庭痛，通常与外阴前庭炎有关。 最常见于绝经前妇女。这种慢性疼痛综合征的特征是疼痛感受器轴突数量增加，通常位于前庭后部。临床证据表明，生殖激素影响外阴前庭炎综合征(VVS)的发生和严重程度。除了手术切除过度神经支配的组织外，没有有效的治疗方法。这项申请提出了临床前研究，旨在描述VVS的动物模型，并使用它来评估可能适用于治疗靶向的生物学机制。我们开发了一种VVS的大鼠模型，它在人类身上复制了许多临床结果。向大鼠后前庭小剂量注射完全弗氏佐剂可引起持续性超敏反应和超神经支配。在Aim1中，我们使用这个模型来研究前庭炎症的神经后果，包括发芽和表型改变。我们将研究超神经支配的持续性及其与机械前庭敏感性的相关性，并确定我们的模型是否表现出与性功能障碍一致的行为。我们将评估改变伤害性感受器神经正常模式的雌激素是否也影响过度神经支配的发展。我们将建立在给予幼年大鼠黄体酮导致感觉神经密度持续增加的初步发现的基础上，并确定这是否促进前庭过度神经的发育。我们将评估我们的模型模拟人类细胞学变化的程度，方法是将大鼠的发现与从VVS患者身上切除的组织进行比较。在目标2中，我们验证了血管紧张素II受体2型(AT2)激活介导VVS神经兴奋和超敏反应的假说。在初步研究中，我们发现，在我们的模型中，AT2受体阻滞剂可以消除过度神经支配和超敏反应。我们假设炎症细胞创造了一个局部肾素-血管紧张素系统，该系统合成血管紧张素II，从而启动感觉神经轴突的萌芽。我们将确定血管紧张素II是否由大鼠和人的前庭组织合成，并使用外植体培养，以诱导萌发。我们将确定在我们的大鼠模型中，在没有炎症的情况下，IAT2的激活会引起发芽和过敏。我们将确定AT2拮抗剂是否不仅可以预防或逆转神经过敏和超敏反应。我们将确定AT2阻滞剂是否克服了生殖激素作用所增强的超神经支配和机械敏感性。这一应用将为调节正常和炎症前庭组织的神经支配机制提供基本信息。它利用一种新的大鼠模型来确定前庭炎症超敏反应的生物学基础，目的是操纵一个关键的信号通路，以确定VVS的新治疗靶点。从这些研究中获得的信息具有极大的潜力，可以实质性地改变我们对某些形式的外阴疼痛的治疗思路和临床方法。

DESCRIPTION (provided by applicant): An estimated 6 million women in the US suffer from vulvodynia. Provoked vestibulodynia, which typically is associated with vulvar vestibulitis, occurs most often in premenopausal women. This chronic pain syndrome is characterized by increased numbers of nociceptor axons usually localized to the posterior vestibule. Clinical evidence suggests that reproductive hormones influence the development and severity of vulvar vestibulitis syndrome (VVS). Aside from surgical excision of the hyperinnervated tissue, there are no effective therapies. This application proposes preclinical studies designed to characterize an animal model of VVS, and to use it to assess biological mechanisms that may be amenable to therapeutic targeting. We developed a rat model of VVS that replicates many clinical findings in humans. Small-volume injections of complete Freund's adjuvant into the rat posterior vestibule evoke persistent hypersensitivity and hyperinnervation. In Aim1, we use this model to investigate neural consequences of vestibular inflammation, including sprouting and phenotype alterations. We will investigate the persistence of hyperinnervation and its correlation to mechanical vestibular sensitivity, and determine if our model shows behavior consistent with dyspareunia. We will assess whether estrogen, which alters normal patterns of nociceptor innervation, also affects development of hyperinnervation. We will build on preliminary findings that progesterone administered to juvenile rats causes persistent increases in sensory innervation density, and determine whether this augments development of vestibular hyperinnervation. We will assess the extent to which our model simulates human cytological changes by comparing findings in rats with tissue excised from patients with VVS. In Aim 2, we test the hypothesis that activation of the angiotensin II receptor type 2 (AT2) mediates hyperinnervation and hypersensitivity in VVS. In preliminary studies, we show that AT2 blockade abrogates hyperinnervation and hypersensitivity in our model. We hypothesize that inflammatory cells create a local renin-angiotensin system that synthesizes angiotensin II, which initiates sensory axon sprouting. We will determine if angiotensin II is synthesized by rat and human vestibular tissue, and using explant cultures, that it elicits sprouting. We will determine i AT2 activation in the absence of inflammation elicits sprouting and hypersensitivity in our rat model. We will determine if AT2 antagonism not only prevents, but also reverses hyperinnervation and hypersensitivity. We will determine if AT2 blockade is overcomes hyperinnervation and mechanical sensitivity augmented by the actions of reproductive hormones. This application will provide fundamental information on mechanisms that regulate innervation in normal and inflamed vestibular tissue. It employs a novel rat model to identify the biological underpinnings of vestibular inflammatory hypersensitivity with the intention of manipulating a key signaling pathway in order to identify new therapeutic targets in VVS. Information obtained in these studies has strong potential to substantively change our thinking and clinical approach to the management of some forms of vulvodynia.