Chemokine Decoy Receptor: a novel therapy of IBD

描述（由申请人提供）：目前克罗恩病的治疗方法（皮质类固醇，TNF-的中和）依赖于广谱免疫抑制，这种方法不是统一有效，并且经常与主要副作用相关。为了填补这一市场空白，Radikal Therapeutics正在开发一种新的可溶性受体诱骗受体融合蛋白（hR-421），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CCR5受体的第二外显子结构域构建，结合并中和所有3种CCR5结合配体(趋化因子MIP-？, MIP - ?阻断它们与CCR1、CCR3和CCR5的结合和激活。与CCR5抑制剂相比，mR-421 （hR-421的小鼠同源物）阻断CCR5不依赖的促炎途径，对CCR5敲除小鼠有效。即使在疾病发作后开始治疗，mR-421治疗也能显著抑制实验性过敏性脑脊髓炎（EAE），这是一种经典的自身免疫模型系统。此外，从EAE供体中分离的ag特异性效应Th1细胞在体内经mR-421处理后产生的促炎细胞因子显著减少，并在过代转移实验中抑制EAE。目前申请的目的是将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。拟议的研究是专门设计来验证mR-421通过抑制肠粘膜中的促炎细胞因子来减轻先前存在的结肠炎的假设。具体目的：利用1)葡聚糖硫酸钠（DSS）模型和2)二苯磺酸（DNBS）肠道炎症模型建立mR-421在小鼠体内的药效学特征，mR-421（3、10和30 mg/kg/d QD IP）、无关IgG对照（10 mg/kg QD IP）、地塞米松（1 mg/kg QD IP）或抗小鼠TNF-？（10 mg/kg QD IP）将在口服DSS或直肠内DNBS暴露后7天开始，这是严重持续结肠炎的时间点。不暴露于DSS或mR-421的假组作为对照。将监测动物的体重和疾病的临床症状：驼背、体重减轻、稀便/腹泻和血便。治疗10天后，将分析肠道的生化、免疫组织化学和指示炎症损伤的形态学参数。进展到2期SBIR将需要mR-421: 1)剂量依赖性地改善组织损伤，以下所有损伤参数减少了50%：脂质过氧化，中性粒细胞（PMN）浸润，过氧亚硝酸盐（ONOO-）产生，聚（adp -核糖）聚合酶形成，总体和组织学损伤评分，以及2)显示了明确的作用机制，在DNBS和DSS模型中抑制粘膜促炎细胞因子和趋化因子。mR-421的上述所有效果必须优于无关IgG对照组，至少不逊于治疗组

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.