Nitric oxide and cyclooxygenase in arthritis

说明(申请人提供)：一氧化氮(NO)参与许多细胞功能，其中一些似乎是自相矛盾的。例如，在一些环境中，升高的NO水平与促进细胞生长有关，而在另一些环境中，高浓度的NO会抑制细胞的增殖。NO是通过三种形式的一氧化氮合酶(NOS)中的一种合成的：神经型NOS(nNOS或NOS1)、诱导型NOS(iNOS或NOS2)和内皮型NOS(eNOS或NOS3)。顾名思义，iNOS是由多种外界刺激诱导的，包括细胞因子、免疫复合体、脂多糖和其他促炎分子。NO的变化已被描述为自身免疫性疾病，包括动物和人类的炎症性关节炎。许多上调iNOS的分子也刺激环氧合酶(COX)家族的活性。这些酶负责从花生四烯酸合成前列腺素(PGs)。这种酶的诱导型亚型COX-2也与炎症性关节炎有关。在这种情况下，NO可以调节COX活性，而PGs则可以调节NOS活性。作为COX抑制剂的药物已经开发出来，包括最初的非类固醇抗炎药(NSAID)，它非特异性地阻断这两种形式的COX酶，以及更新的、更特异的COX-2抑制剂。虽然环氧合酶-2抑制剂已被证明在某些情况下会改变iNOS的活性，但对其在炎症性关节炎中对iNOS的影响知之甚少。由于诱导COX-2和iNOS的刺激物的相似性，以及这些分子之间的其他相互作用，COX-2抑制剂似乎也可能改变iNOS的活性。这项建议将通过研究非特异性和选择性的COX抑制剂在具有不同NOS遗传背景的小鼠中的作用，来研究炎性关节炎中NOS和COX之间的一些相互关系，从而允许剖析iNOS、eNOS和COX在炎症严重程度中的作用。此外，将使用蛋白质组学分析工具探索血清蛋白质的变化，以识别关节炎进展和治疗反应的潜在生物标记物，并作为了解潜在机制的一部分-参与COX和NOS的相互作用，这可能解释NO对炎症过程的一些看似自相矛盾的影响。

DESCRIPTION (provided by applicant): Nitric oxide (NO) is involved in many cellular functions, some of which may appear to be paradoxical. For example, in some settings elevated NO levels are associated with enhanced cell growth, while in others high concentrations of NO reduce cellular proliferation. NO is synthesized via the activity of one of three forms of nitric oxide synthase (NOS): neuronal NOS (nNOS or NOS 1); inducible NOS (iNOS or NOS 2); and endothelial NOS (eNOS or NOS 3). As implied by its name, iNOS is induced by a variety of external stimuli, including cytokines, immune complexes, lipopolysaccharides, and other pro-inflammatory molecules. Changes in NO have been described in autoimmune disorders, including inflammatory arthritis in animals and in humans. Many of the molecules that upregulate iNOS also stimulate the activity of the cyclooxygenase (COX) family of enzymes. These enzymes are responsible for the synthesis of prostaglandins (PGs) from arachidonic acid. The inducible isoform of the enzyme, COX-2, also has been implicated in inflammatory arthritis. NO can modulate COX activity, and PGs can modulate NOS activity in this and other conditions. Drugs that act as COX inhibitors have been developed, including the original nonsteroidal anti-inflammatory drugs (NSAIDs) that nonspecifically block both forms of the COX enzymes, and the newer, more specific COX-2 inhibitors. While COX-2 inhibitors have been shown to alter iNOS activity in some settings, little is known about their effects on iNOS in inflammatory arthritis. Because of the similarities in the stimuli that induce COX-2 and iNOS and because of the other interactions between these molecules, it seems likely that COX-2 inhibitors might alter iNOS activity as well. This proposal will examine some of the interrelationships between NOS and COX in inflammatory arthritis by studying the effects of nonspecific and selective COX inhibitors in mice with different NOS genetic backgrounds, thus permitting the dissection of the roles of iNOS, eNOS, and COX in the severity of inflammation. Additionally, changes in serum proteins will be explored using the tools of proteomic analysis to permit the identification of potential biomarkers for arthritis progression and therapeutic response and as part of an effort to understand the underlying mechanisms-involved in COX and NOS interactions that may account for some of the seemingly paradoxical effects of NO on the inflammatory process.