DNA damage and repair in inflammation-induced peripheral sensitization

 描述（由申请人提供）：虽然炎症诱导的外周致敏（即感觉神经元的敏感性增加）可以随着损伤愈合而消退，但在 病理条件下，这种致敏作用得以维持并导致慢性炎性疼痛。对介导维持外周致敏的细胞机制的研究集中在改变蛋白质表达或各种蛋白质（尤其是离子通道）的翻译后调节的转录变化上。然而，到目前为止，这些研究还没有产生用于治疗慢性炎性疼痛的新的治疗方法。对于这种R21的应用，我们提出了一种新的机制来维持感觉神经元的敏化，即炎症诱导的DNA损伤。这种损伤可能导致神经元的表型从“正常”到致敏状态的改变。最近在我们实验室进行的研究为检查这种机制提供了支持，因为我们已经表明，增强DNA修复机制可以逆转癌症治疗诱导的感觉神经元毒性。此外，我们的初步数据表明，炎症和炎症介质LPS，MCP-1，和，PGE 2，可以在感觉神经元中产生DNA损伤。因此，我们假设炎症和炎症介质在感觉神经元中产生氧化性DNA损伤，导致超敏反应，并且增强碱基切除修复途径保护神经元免受这种损伤，从而减弱增强的兴奋性。为了验证这一假设，我们提出了两个具体目标。在第一个目标的研究中，我们将确定CFA诱导的炎症或长期暴露于分离的感觉神经元中的炎症介质（LPS，MCP-1或PGE 2）是否会在感觉神经元中产生活性氧（ROS）和DNA损伤。我们还将确定抗氧化剂或增加APE 1修复活性（通过在感觉神经元中过度表达）是否可以预防或逆转DNA损伤。在目标2中，我们将确定在感觉神经元中通过过表达来增强APE 1活性是否预防或逆转由CFA注射到大鼠后爪中或通过长期暴露于分离的感觉神经元中的炎症介质（LPS、MCP-1或PGE 2）诱导的外周敏化。如果我们证明DNA修复可以逆转炎症过程中发生的外周敏化，我们的发现对于阐明治疗慢性疼痛的新治疗靶点具有重要意义。

 DESCRIPTION (provided by applicant): Although inflammation-induced peripheral sensitization (i.e. increased sensitivity of sensory neurons) can resolve as an injury heals, under pathological conditions this sensitization is maintained and contributes to chronic inflammatory pain. Studies of the cellular mechanisms mediating this maintenance of peripheral sensitization have focused on transcriptional changes that alter protein expression or post-translational modulation of various proteins, especially ion channels. To date, however, these studies have not resulted in new therapeutic approaches for treating chronic inflammatory pain. For this R21 application, we propose a novel mechanism for maintaining sensitization of sensory neurons, i.e. inflammation-induced DNA damage. This damage could result in an alteration in the phenotype of neurons from "normal" to the sensitized state. Recent studies performed in our laboratory provide support for examining this mechanism, since we have shown that augmenting DNA repair mechanism reverses toxicity in sensory neurons induced by cancer therapies. Furthermore, our preliminary data suggest that inflammation and the inflammatory mediators LPS, MCP-1, and, PGE2, can produce DNA damage in sensory neurons. Thus, we hypothesize that inflammation and inflammatory mediators produce oxidative DNA damage in sensory neurons that contributes to hypersensitivity and that augmenting the base excision repair pathway protects neurons from this damage and thus attenuates the enhanced excitability. To test this hypothesis we propose two specific aims. In studies for the first aim, w will determine whether CFA-induced inflammation or long-term exposure to inflammatory mediators (LPS, MCP-1 or PGE2) in isolated sensory neurons produces reactive oxygen species (ROS) and DNA damage in sensory neurons. We also will determine whether antioxidants or increasing APE1 repair activity (by overexpressing it in sensory neurons) prevents or reverses the DNA damage. In aim 2, we will determine whether augmenting APE1 activity with overexpression in sensory neurons prevents or reverses peripheral sensitization induced by CFA injection into the rat hindpaw or by long-term exposure to inflammatory mediators (LPS, MCP-1 or PGE2) in isolated sensory neurons. If we demonstrate that DNA repair reverses peripheral sensitization that occurs during inflammation, our findings have important implications for elucidating a novel therapeutic target for treating chronic pain.