Previous studies in a rat model of Sephadex induced lung inflammation showed that 4-Thiouridine (4SU), a thiol substituted nucleoside, was very effective in reducing edema, leukocyte influx and TNF levels in bronchoalvelolar lavage fluid. However, little is known about the factors and mechanisms underlying these effects. In the present study, we have used two separate mouse models of chronic inflammation, a model of dextran sulphate sodium (DSS) induced colitis and a model of antigen induced arthritis, to evaluate the anti-inflammatory effect of 4-thiouridine. We have analyzed a broad spectrum of inflammatory mediators in order to delineate the mechanisms behind a potential anti-inflammatory effect of 4SU. Colitis was induced in C57BL/6 mice by administration of 3.5% DSS in drinking water for 5 days and the potential anti-colitic effect of 4SU was assessed by monitoring the disease activity index (DAI), measurement of colon length and histopathological analysis of colon tissue. We analyzed tissue myeloperoxidase (MPO) activity, serum pro-inflammatory cytokines (IL-1β, IL-6 and TNF), mRNA and protein expression of pro-inflammatory cytokines, COX-2, and NF-κB activity in colitis tissue. Intracolonic administration of 4SU (5 mg/kg & 10 mg/kg.) significantly inhibited MPO activity and reduced the levels of pro-inflammatory cytokines (IL-1β, IL-6 and TNF) as well as COX-2. Further, NF-κB activation was also blocked by attenuating the phosphorylation of IkB kinase (IKK α/β) in DSS-induced colitis tissues. Arthritis was induced by intra-articular injection of mBSA in the knee of NMRI mice pre-immunized with mBSA and 4SU was administered locally by direct injection into the knee joint. The antiarthritic potential of 4SU was calculated by histopathological scores and histochemical analysis of joint tissue. Further, immunohistochemistry was used to study inflammatory cell infiltration and expression of cytokines and adhesion molecules in the synovium. Local administration of 50–100 mg/kg 4SU at the time of arthritis onset clearly prevented development of joint inflammation and efficiently inhibited synovial expression of CD18, local cytokine production and recruitment of leukocytes to the synovium. Taken together, our data clearly demonstrates a potent anti-inflammatory effect of 4SU in two experimental models. In conclusion 4SU could be a new promising candidate for therapeutic modulation of chronic inflammatory diseases like ulcerative colitis and arthritis.

先前在Sephadex诱导的肺部炎症的大鼠模型中的研究表明，巯基取代的核苷4-硫尿苷（4SU）在减少支气管肺泡灌洗液中的水肿，白细胞涌入和TNF水平方面非常有效。但是，对于这些作用的潜在因素和机制知之甚少。在本研究中，我们使用了两种单独的慢性炎症小鼠模型，一种葡聚糖硫酸钠（DSS）诱导的结肠炎模型和一种抗原诱导的关节炎模型来评估4-硫尿苷的抗炎作用。为了描述4SU潜在抗炎作用的机制，我们分析了多种炎性介质。通过施用3在C57BL / 6小鼠中诱发结肠炎。通过监测疾病活动指数（DAI），结肠长度的测量和结肠组织的组织病理学分析，评估了饮用水中5％的DSS（5天）和4SU的潜在抗结肠炎作用。我们分析了结肠炎组织中的组织髓过氧化物酶（MPO）活性，血清促炎细胞因子（IL-1β，IL-6和TNF），促炎细胞因子的mRNA和蛋白表达，COX-2和NF-κB活性。结肠内施用4SU（5 mg / kg和10 mg / kg。）可显着抑制MPO活性并降低促炎细胞因子（IL-1β，IL-6和TNF）以及COX-2的水平。此外，通过减弱DSS诱导的结肠炎组织中IkB激酶（IKKα/β）的磷酸化，也可以阻断NF-κB的活化。通过关节腔内注射mBSA预先免疫接种了mBSA的NMRI小鼠，可诱发关节炎，并通过直接注射至膝关节局部施用4SU。通过组织病理学评分和关节组织的组织化学分析计算出4SU的抗关节炎潜力。此外，免疫组织化学被用于研究滑膜中炎性细胞浸润以及细胞因子和粘附分子的表达。在关节炎发作时局部给予50-100 mg / kg 4SU可以明显预防关节炎症的发展，并有效抑制CD18的滑膜表达，局部细胞因子的产生以及白细胞向滑膜的募集。综上所述，我们的数据清楚地证明了两个实验模型中4SU的有效抗炎作用。