Ciprofloxacin enhances DNA repair capacity after radiation combined injury

描述(由申请人提供)：本申请解决了辐射复合损伤(CI)的医疗治疗的一个主要空白。氟喹诺酮类药物，如环丙沙星(CIP)，一般耐受性良好，通常用于治疗普通人群的感染。美国食品和药物管理局(FDA)建议将CIP用于炭疽病治疗，并将其保存在国家储备中，以供发生国家紧急情况时特定的人类使用。我们假设CIP通过间接地通过遗传毒性应激反应，或直接通过修饰染色质和/或抑制真核细胞拓扑异构酶(Topo)II来发挥辐射防护/治疗作用。CIP通过抑制细菌DNA旋转酶(细菌Topo II或Topo IV)发挥作用，但对真核细胞Topo II有轻微的抑制作用。Topo II催化双链DNA断裂/宗教反应。我们的理论基于：1)小鼠研究表明，CIP可提高9.75Gy全身照射(TBI)和脑梗塞小鼠的存活率；2)与TBI相比，CIP可提高6.5GyTBI和CI小鼠的DNA修复能力。我们的长期目标是(1)阐明与复合损伤(CI-辐射+皮肤创伤)相关的病理机制，以及(2)评估选定的抗菌药治疗CI后脓毒症的疗效。我们的短期目标是1)阐明与TBI-CIP动物明显增强的基因组稳定性相关的分子机制，2)阐明B6D2F1雌性小鼠辐射损伤(RI)和CI后存活率增加的分子途径。我们将在三个特定的目标中实现这些目标：目的1.评估CIP在人淋巴母细胞TK6细胞中的生物学活性和血液的体外药效学；目的2.通过(A)定量CI后细胞周期、DNA修复和细胞凋亡的同源基因和蛋白，以及(B)通过FACS评估DNA损伤/修复和凋亡标志物，以及目的3.通过体外基因组挑战分析来区分RI和CI的造血样本中CIP和CIP后基因组稳定性的变化。R33部分将被分成3个明确的任务：(A)辐射防护/治疗效果(B)作用机制，以及(C)基因组/蛋白质组图谱。对免疫调节特性和检查点通路的激活的了解将有助于CIP的更大用途，以及喹诺酮类抗菌药如何增强基因组稳定性，促进伤口愈合和提高存活率。

DESCRIPTION (provided by applicant): This application addresses a major gap for medical treatment of radiation combined injuries (CI). Fluoroquinolones, like ciprofloxacin (CIP), are generally well-tolerated and commonly used for treating infections in the general population. The Food and Drug Administration (FDA) has recommended CIP for anthrax treatment, and it is maintained in the National Stockpile for specific human use in the event of a national emergency. We hypothesize that CIP exerts a radioprotective/therapeutic effect either indirectly through genotoxic stress response, or directly via ability to modify chromatin and/or inhibit eukaryotic topoisomerase (topo) II. CIP works by inhibiting bacterial DNA gyrase (bacterial topo II or topo IV), but has a slight inhibitory effects on eukaryotic topo II. Topo II catalyzes the double strand DNA break/religation reaction. Our rationale is based on: 1) mouse studies where CIP enhanced survival after 9.75 Gy total body irradiation (TBI) and CI mice and 2) increased DNA repair capacity in rhesus macaques that received 6.5 Gy TBI with CIP compared to TBI. Our long-term goals are to (1) clarify the pathologic mechanisms associated with combined injury (CI-radiation plus skin-wound trauma) and (2) assess the efficacy of selected antimicrobials for treating sepsis after CI. Our short-term goals are to 1) clarify the molecular mechanisms associated with apparent enhanced genomic stability conferred on TBI-CIP animals, and 2) to elucidate molecular pathways involved in increased survival after radiation injury (RI) and CI in B6D2F1 female mice. We will address these goals in three Specific Aims: Aim 1. Assess biological activities of CIP in human lymphoblastoid TK6 cells and a blood ex vivo pharmacodynamic assay, Aim 2. Measure CIP-molecular pharmacodynamics in mice in vivo by (a) quantify homologous genes and proteins for cell cycle, DNA repair, and apoptosis in hematopoietic, wound tissues following CI, and (b) assess DNA damage/ repair and apoptotic markers by FACS, and Aim 3. Discriminate changes in genomic stability post CI and CIP in hematopoietic samples for RI and CI by genomic challenge assay ex vivo. The R33 portion will be divided into 3 defined tasks: (a) radioprotective/therapeutic efficacy (b) mechanisms of action, and (c) genomic/proteonomic profiling. The increased understanding of immunomodulatory properties and activation of checkpoint pathways will facilitate greater utility of CIP, and of how quinolone antimicrobials might confer genomic stability, enhance wound healing, and improve survival.