HYALURONAN-MEDIATED NITRIC OXIDE PRODUCTION BY MACROPHAG

类风湿性关节炎(RA)是一种常见疾病，会导致严重的痛苦、残疾和死亡率增加，是慢性炎症性免疫反应的一个例子。RA的特征是过度产生透明质酸(HA)和产生具有促炎特性的低分子HA寡糖。一氧化氮(NO)和肿瘤坏死因子α是类风湿关节炎(RA)中两种重要的炎症介质。诱导人滑膜巨噬细胞产生NO的机制以及NO的下游炎症效应尚不清楚，尤其是在RA等疾病的背景下。同样，使类风湿因子在类风湿关节炎中持续生产的机制尚未完全确定。这一提议将检验这样一种假设，即低分子HA寡糖通过细胞表面HA受体CD44维持RA滑膜巨噬细胞产生一氧化氮(NO)和肿瘤坏死因子α(TNFpha)的炎症循环，从而导致进一步产生碎片HA寡糖。具体目标是：1.比较不同相对分子质量的HA寡糖诱导人单核细胞和组织巨噬细胞产生NO的能力。2.)确定HA寡糖是否诱导RA患者单核细胞和滑膜巨噬细胞产生NO。3.)测定HA寡糖诱导人巨噬细胞产生细胞因子的能力。4.)确定单核细胞和滑膜巨噬细胞产生NO是否诱导HA断裂。这些研究将导致未来的工作，以确定涉及CD44信号和人巨噬细胞产生NO的分子事件，并将为针对RA患者进行旨在抑制NO产生和抑制CD44-HA相互作用的治疗试验提供理论基础。

Rheumatoid arthritis (RA) is a common disease that causes important suffering, disability and increased mortality, and represents an example of a chronic inflammatory immune response. RA is characterized by the overproduction of hyaluronan (HA) and production of low molecular weight HA oligosaccharides which have proinflammatory properties. Nitric oxide (NO) and TNFalpha are two important inflammatory mediators in RA. The mechanisms that induce NO production in human synovial macrophages and the downstream inflammatory effects of NO are poorly understood, especially in the context of diseases such as RA. Likewise, the mechanisms that perpetuate the continued production of TNFalpha in RA have not been completely characterized. This proposal will test the postulate that low molecular weight HA oligosaccharides perpetuate an inflammatory cycle of nitric oxide (NO) and TNFalpha production by synovial macrophages in RA, via the cell surface HA receptor CD44, that leads to further production of fragmented HA oligosaccharides. The specific aims are to: 1.) Compare the ability of HA oligosaccharides of different molecular weight to induce NO production by human monocytes and tissue macrophages. 2.) Determine whether HA oligosaccharides induce NO production by monocytes and synovial macrophages from patients with RA. 3.) Determine the ability of HA oligosaccharides to induce human macrophage cytokine production. 4.) Determine whether NO production by monocytes and synovial macrophages induces HA fragmentation. These studies will lead to future work that defines the molecular events involved in CD44 signaling and NO production by human macrophages and will also provide the rationale for therapeutic trials in RA patients that target inhibition of NO production and inhibition of CD44-HA interactions.