Harnessing ectonucleotidases to treat chronic pain

描述(申请人提供)：患慢性疼痛的美国人比心脏病、糖尿病和癌症加起来还要多。不幸的是，现有的止痛药并不是对所有疼痛状况都完全有效，而且有严重的副作用。这些事实突显了现代生物医学研究无疑面临的一个关键挑战--需要提供没有严重副作用的止痛药。我们将通过利用内源性存在于背根神经节(DRG)和脊髓的伤害性(痛觉)回路中的胞外核苷酸酶来直接应对这一挑战。胞外核苷酸酶将引起疼痛的嘌呤核苷酸(如ATP和ADP)降解为腺苷，腺苷是一种对啮齿动物和人类具有止痛特性的化合物。腺苷通过A1-腺苷受体抑制疼痛。为了充分利用胞外核苷酸酶治疗疼痛，我们将确定所有在伤害性环路中将核苷酸代谢为腺苷的胞外核苷酸酶，然后确定这些酶是否可以单独或联合使用来治疗急性和慢性疼痛。我们将利用缺乏这些酶的转基因小鼠、重组ECN蛋白、行为分析和膜片钳电生理学进行这些实验。此外，我们还将利用药物化学来合成腺苷前体药物，这些药物可以通过胞外核苷酸酶转化为有效的A1-腺苷受体激动剂。我们将测量这些前药在血清中的稳定性，并使用行为和生理测试来评估止痛效果和副作用。我们还将在慢性炎症性和神经病理性疼痛的动物模型中测试胞外核苷酸酶和前药的疗效。 公共卫生相关性：这些研究将使我们能够开发新的蛋白质和小分子，靶向胞外核苷酸酶治疗急性和慢性疼痛。此外，这些研究有可能以更少的副作用改变我们治疗数百万患者疼痛的方式。

DESCRIPTION (provided by applicant): More Americans suffer from chronic pain than heart disease, diabetes and cancer combined. Unfortunately, existing analgesics are not completely effective for all pain conditions and have serious side effects. These facts highlight what is undoubtedly a critical challenge for modern biomedical research-the need to provide pain relief without serious side effects. We will directly address this challenge by harnessing ectonucleotidases that are found endogenously in nociceptive (pain-sensing) circuits in dorsal root ganglia (DRG) and spinal cord. Ectonucleotidases degrade purine nucleotides (like ATP and ADP) that cause pain into adenosine-a compound that has analgesic properties in rodents and humans. Adenosine suppresses pain by acting through A1-adenosine receptors. To fully harness ectonucleotidases for the treatment of pain, we will identify all of the ectonucleotidases that metabolize nucleotides to adenosine in nociceptive circuits and then determine if these enzymes can be used alone or in combination to treat acute and chronic pain. We will utilize genetically modified mice that are missing these enzymes, recombinant ectonucleotidase proteins, behavioral assays and patch clamp electrophysiology for these experiments. In addition, we will use medicinal chemistry to synthesize adenosine prodrugs that can be converted into potent A1-adenosine receptor agonists by ectonucleotidases. We will measure the stability of these prodrugs in serum and use behavioral and physiological assays to assess analgesic efficacy and side effects. We will also test ectonucleotidases and prodrugs for efficacy in animal models of chronic inflammatory and neuropathic pain. PUBLIC HEALTH RELEVANCE: These studies will allow us to develop new proteins and small molecules that target ectonucleotidases for the treatment of acute and chronic pain. In addition, these studies have the potential to transform how we treat pain in millions of patients with fewer side effects.