Role of ASIC3 in the Etiology of Fibromyalgia

描述（由申请人提供）：尽管最近在治疗方面取得了进展，但风湿性关节炎（RA）仍然是一个主要的未满足的医疗需求。慢性滑膜炎引起的疼痛和功能丧失是由于各种影响，包括激活的适应性和先天免疫反应。在这个提议中，我们假设关节的低pH环境可以通过激活滑膜细胞上的酸敏感通道（ASIC）来增加炎症介质的产生而加剧滑膜炎。我们在最初应用中的先前实验表明，ASIC 3的缺失或ASICs的局部阻断防止了与肌肉或关节损伤相关的疼痛行为。我们进一步显示了在支配发炎组织的感觉神经元中ASIC的上调，以及炎症后ASIC电流的改变。我们最近发现滑膜细胞表达ASIC 3，初步数据显示pH值的降低会增加ASIC 3 +/+小鼠滑膜细胞的细胞内钙，但不会增加ASIC 3 +/+小鼠滑膜细胞的细胞内钙。 ASIC 3-/-小鼠。此外，pH值的降低增强了ASIC 3 +/+小鼠成纤维细胞样滑膜细胞（FLS）中前列腺素E2的产生。通过pH降低激活ASIC也可以激活细胞内信号级联，其调节与RA有关的细胞因子如IL-1、IL-6和TNF的产生。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感。具体目标1将确定pH值降低是否通过增加细胞内钙、激活细胞内信号级联和增强炎症介质释放来激活鼠和人成纤维细胞样滑膜细胞（FLS）。具体目标2将通过比较来自ASIC 3-/-小鼠与ASIC 3 +/+小鼠的FLS中的应答（在具体目标1中），以及通过比较人FLS中ASIC 3的miRNA敲低与用对照miRNA处理的人FLS中的那些的效应，来确定pH诱导的细胞内钙、信号传导级联和炎性介质释放的变化是否依赖于ASIC 3的活化。具体目标3将通过比较ASIC 3-/-和ASIC 3 +/+小鼠中的反应来确定ASIC 3是否有助于类风湿性关节炎的被动K/BxN血清转移模型中炎症和疼痛的发展。了解pH和ASIC 3如何增强炎症过程的新机制，将可能通过开发针对这些途径的新药来改善医疗保健。 公共卫生相关性：风湿性关节炎（RA）仍然是一个主要的未满足的医疗需求，导致疼痛和功能丧失，由于慢性炎症。在类风湿性关节炎患者的关节中发生的pH值降低可以激活位于滑膜细胞上的酸敏感离子通道，以增加炎症过程，因此将是发炎关节的酸性环境的理想目标。因此，旨在抑制ASIC的药剂是有希望的，因为它们不仅具有减少炎症过程的潜力，而且在抑制肌肉骨骼疼痛中具有直接作用。

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.