Chemokine Decoy Receptor: a novel therapy of IBD

描述（由申请方提供）：克罗恩病的当前治疗方法（皮质类固醇、TNF-？中和）依赖于广谱免疫抑制，这种方法不是一致有效的，并且经常与主要副作用相关。为了解决这一市场缺口，Radikal Therapeutics正在开发一种新型可溶性受体诱饵受体融合蛋白（hR-421），该蛋白可诱导抗原（Ag）特异性活化T细胞的免疫耐受。hR-421由Ig-Fc和CCR 5受体的第二胞外结构域构建，结合并中和所有3种CCR 5结合配体（趋化因子MIP-β，MIP-？，RANTES）并阻止它们与CCR 1、CCR 3和CCR 5的结合和激活。与CCR 5抑制剂相反，mR-421（hR-421的鼠同源物）阻断CCR 5非依赖性促炎通路，并且在CCR 5敲除小鼠中有效。使用mR-421的治疗深刻地抑制了实验性过敏性脑脊髓炎（EAE），一种经典的自身免疫模型系统，即使在疾病发作后开始治疗。此外，从用mR-421在体内处理的EAE供体中分离的Ag特异性效应Th 1细胞产生显著更少的促炎细胞因子，并在过继转移实验中抑制EAE。本申请的目的是将R-421技术的保护作用扩展到神经炎症的初步发现之外，并在克罗恩病的临床相关模型中确定其潜在益处。拟定研究专门设计用于检验mR-421通过抑制肠粘膜中的促炎细胞因子来减轻既存结肠炎的假设。具体目标：利用1）葡聚糖硫酸钠（DSS）模型和2）肠道炎症的二硝基苯磺酸（DNBS）模型，在小鼠中建立mR-421的药效学特征。(10 mg/kg QD IP）将在口服DSS或直肠内DNBS暴露开始后开始7天开始，这是显著进行性结肠炎的时间点。未暴露于DSS或mR-421的假手术组将用作对照。将监测动物的体重和疾病的临床体征：驼背外观、体重减轻、稀便/腹泻和血便。治疗10天后，将分析肠的生化、免疫组织化学和指示炎性损伤的形态学参数。进展至2期SBIR将需要使用mR-421：1）剂量依赖性地改善组织损伤，如所有以下损伤参数减少> 50%所证明：脂质过氧化，中性粒细胞（PMN）浸润，过氧亚硝酸盐（ONOO-）产生，多聚（ADP-核糖）聚合酶形成、大体和组织学损伤评分，以及2）证明了明确的作用机制，如DNBS和DSS模型中粘膜促炎细胞因子和趋化因子的抑制所示。mR-421的所有上述作用必须上级无关IgG对照组，并且至少不劣于治疗 抗鼠TNF-？mAb和地塞米松（p<0.05）。 公共卫生相关性：克罗恩病仍然是现有疗法的障碍，高比例的患者持续反复发作的炎症和肠道损伤。我们正在开发一种新药，专门阻断这种情况下的炎症过程。我们将在一系列临床相关的自身免疫性结肠炎动物模型中测试这种药物。

DESCRIPTION (provided by applicant): Current therapeutic approaches to Crohn's Disease (corticosteroids, neutralization of TNF-?) rely upon broad-spectrum immunosuppression, an approach that is not uniformly effective and is frequently associated with major side-effects. To address this market gap, Radikal Therapeutics is developing a novel soluble receptor decoy receptor fusion protein (hR-421) that induces immune tolerance in antigen (Ag)-specific activated T- cells. Constructed from Ig-Fc and the second ecto domain of the CCR5 receptor, hR-421 binds and neutralizes all 3 CCR5-binding ligands (chemokines MIP-?, MIP-?, RANTES) and prevents their binding and activation of CCR1, CCR3, and CCR5. In contrast to CCR5 inhibitors, mR-421 (the murine homologue of hR-421) blocks CCR5-independent pro-inflammatory pathways and is effective in CCR5 knock-out mice. Therapy with mR-421 profoundly suppresses experimental allergic encephalomyelitis (EAE), a classic autoimmune model system, even when treatment is initiated after disease onset. Moreover, Ag-specific effector Th1 cells isolated from EAE donors treated in vivo with mR-421 produce substantially less pro-inflammatory cytokines and suppress EAE in adoptive transfer experiments. The purpose of the current application is to extend the protective effects of the R-421 technology beyond the preliminary findings in neuroinflammation and establish its potential benefit in a clinically-relevant model of Crohn's Disease. The proposed studies are specifically designed to test the hypothesis that mR-421 attenuates preexisting colitis via its suppression of pro-inflammatory cytokines in the intestinal mucosa. Specific Aims: Establish the pharmacodynamic profile of mR-421 in mice utilizing 1) a dextran sulfate sodium (DSS) model and 2) a dintrobenzenesulfonic (DNBS) model of intestinal inflammation Treatment with mR-421 (3, 10, and 30 mg/kg/day QD IP), an irrelevant IgG control (10 mg/kg QD IP), dexamethasone (1 mg/kg QD IP), or anti-murine TNF-? (10 mg/kg QD IP) will begin 7 days after the start of oral DSS or intrarectal DNBS exposure, a timepoint of significant ongoing colitis. A sham group without exposure to DSS or mR-421 will be utilized as a control. Animals will be monitored for body weight and clinical signs of illness: hunched-over appearance, weight loss, loose stools/diarrhea, and bloody stools. After 10 days of therapy, the intestine will be analyzed for biochemical, immunohistochemical, and morphologic parameters indicative of inflammatory injury. Progression to the Phase 2 SBIR will require that with mR-421: 1) dose-dependently ameliorates tissue injury, as demonstrated by > 50% reductions in all of the following injury parameters: lipid peroxidation, neutrophil (PMN) infiltration, peroxynitrite (ONOO-) production, poly(ADP-ribose)polymerase formation, gross and histologic injury scores, and 2) demonstrate a clear mechanism of action, as shown by suppression of mucosal pro-inflammatory cytokines and chemokines in the DNBS and DSS models. All of the above effects of mR-421 must be superior relative to the irrelevant IgG control group and at least non-inferior relative to therapy with an anti-murine TNF-? mAb and dexamethasone (at p<0.05). PUBLIC HEALTH RELEVANCE: Crohn's Disease remains recalcitrant to existing therapies, with a high percentage of patients enduring recurrent bouts of inflammation and intestinal damage. We are developing a novel drug that specifically blocks the inflammatory process in this condition. We will test this agent in a series of clinically-relevant animal models of autoimmune colitis.