Role of ASIC3 in the Etiology of Fibromyalgia

描述(申请人提供)：类风湿性关节炎(RA)仍然是一个主要的未得到满足的医疗需求，尽管最近在治疗方面取得了进展。慢性滑膜炎引起的疼痛和功能丧失是由多种影响引起的，包括激活的适应性和先天免疫反应。在这个方案中，我们假设关节的低pH环境可以通过激活滑膜细胞上的酸感受通道(ASIC)来增加炎症介质的产生，从而加重滑膜炎症。我们先前在最初应用中的实验表明，删除ASIC3或局部阻断ASICs，可以防止与肌肉或关节侮辱相关的疼痛行为。我们进一步展示了支配炎症组织的感觉神经元中ASIC的上调，以及炎症后ASIC电流的变化。我们最近发现，滑膜细胞表达ASIC3，初步数据显示，pH降低会增加ASIC3+/+小鼠滑膜细胞内钙离子，但不会 ASIC3-/-小鼠。此外，pH的降低增加了ASIC3+/+小鼠成纤维样滑膜细胞(FLS)中前列腺素E2的产生。通过降低pH激活ASICs也可以激活细胞内的信号级联，调节与RA有关的细胞因子的产生，如IL-1、IL-6和肿瘤坏死因子。这些炎症介质增强炎症过程，调节关节破坏，并使伤害性关节传入敏化。具体目标1将确定pH降低是否通过增加细胞内钙、激活细胞内信号级联和促进炎症介质的释放来激活小鼠和人类成纤维细胞样滑膜细胞(FLS)。特定目标2将通过比较ASIC3-/-小鼠对ASIC3+/+小鼠在FLS中的反应(在特定目标1中)，以及通过比较人FLS中ASIC3的miRNA敲除效果与对照miRNA处理的人FLS中的效果，来确定pH诱导的细胞内钙变化、信号级联和炎症介质的释放是否依赖于ASIC3的激活。具体目标3将通过比较ASIC3-/-和ASIC3+/+小鼠的反应，确定ASIC3是否有助于类风湿关节炎被动K/BxN血清转移模型中炎症和疼痛的发展。了解pH和ASIC3如何促进炎症过程的新机制，将有可能通过开发针对这些途径的新药物来改善医疗保健。 公共卫生相关性：类风湿性关节炎(RA)仍然是一个主要的未得到满足的医疗需求，由于慢性炎症导致疼痛和功能丧失。类风湿性关节炎患者关节中的pH降低会激活滑膜细胞上的酸感离子通道，从而增加炎症过程，因此是炎症关节酸性环境的理想靶点。因此，旨在抑制ASICs的药物是很有前途的，因为它们不仅有可能减轻炎症过程，而且在抑制肌肉骨骼疼痛方面也有直接作用。

DESCRIPTION (provided by applicant): Rheumatoid arthritis (RA) remains a major unmet medical need despite recent advances in therapy. The pain and loss of function resulting from chronic synovitis are due to a variety of influences, including activated adaptive and innate immune responses. In this proposal, we hypothesize that the low pH environment of the joint can exacerbate synovitis by activating acid sensing channels (ASIC) on synoviocytes to increase production of inflammatory mediators. Our prior experiments in the initial application show that deletion of ASIC3, or local blockade of ASICs, prevents the pain behaviors associated with muscle or joint insult. We further show upregulation of ASICs in sensory neurons innervating inflamed tissue, and alterations in ASIC currents after inflammation. We recently discovered that synoviocytes express ASIC3 and preliminary data show that decreases in pH increase intracellular calcium in synoviocytes from ASIC3+/+ mice but not ASIC3-/- mice. Further, decreases in pH enhance prostaglandin E2 production in fibroblast-like synoviocytes (FLS) from ASIC3+/+ mice. The activation of ASICs by decreases in pH could also activate intracellular signaling cascades that regulate production of cytokines implicated in RA, such as IL-1, IL-6, and TNF. These inflammatory mediators enhance the inflammatory process, regulate joint destruction, and sensitize nociceptive joint afferents. Specific Aim 1 will determine if decreases in pH activate murine and human fibroblast-like synoviocytes (FLS) by increasing intracellular calcium, activating intracellular signaling cascades, and enhancing release inflammatory mediators. Specific Aim 2 will determine if the pH-induced changes in intracellular calcium, signaling cascades, and release of inflammatory mediators, depend on activation of ASIC3 by comparing responses in FLS from ASIC3-/- mice to ASIC3+/+ mice (in Specific Aim 1), and by comparing effects of miRNA knockdown of ASIC3 in human FLS to those in human FLS treated with control miRNA. Specific Aim 3 will determine if ASIC3 contributes to development of inflammation and pain in the passive K/BxN serum transfer model of rheumatoid arthritis by comparing responses in ASIC3-/- and ASIC3+/+ mice. Understanding the novel mechanisms of how pH and ASIC3 enhance the inflammatory process will potentially lead to improved healthcare through development of new pharmaceuticals that target these pathways. PUBLIC HEALTH RELEVANCE: Rheumatoid arthritis (RA) remains a major unmet medical need resulting in pain and loss of function due to chronic inflammation. Decreases in pH, that occur in joints of people with rheumatoid arthritis, can activate acid sensing ion channels, located on synoviocytes, to increase the inflammatory process and thus would be ideal targets for the acidic environment of an inflamed joint. Thus, pharmaceutical agents aimed at inhibition of ASICs are promising in that they not only have the potential to reduce the inflammatory process but also have a direct role in inhibiting musculoskeletal pain.