Overcoming Membrane Transporters to Improve CNS Drug Therapy

描述(由申请人提供)：有一种紧迫感，需要推进药物治疗，以改善脑损伤后的结果。值得注意的是，创伤性脑损伤(TBI)仍然是儿童和年轻人死亡和残疾的主要原因。到目前为止，所有探索单一药物或疗法治疗脑损伤的临床试验都失败了。有效治疗脑外伤的唯一障碍是血-脑(BBB)上的三磷酸腺苷结合盒转运体和溶质载体，以及血-脑脊液(CSF)屏障，这些屏障通过主动和快速地重新摄取药物并将药物输出回血液，限制了药物在正常和受伤大脑中的生物利用度。这些障碍经常被认为是中枢神经系统损伤临床药物试验失败的主要原因，并明显限制了许多药物的治疗适应症，否则对非中枢神经系统疾病有效。膜转运蛋白包括多药耐药蛋白、多药耐药相关蛋白和有机阴离子转运蛋白。重要的是，这些转运蛋白的药理抑制剂已经存在了几十年，用于提高作为膜转运蛋白底物的药物的生物利用度。丙磺舒是一种膜转运蛋白抑制剂的原型。丙磺舒目前在临床上用于治疗尿酸血症，并在第二次世界大战期间被开发出来，以提高青霉素对受伤士兵的生物利用度。丙磺舒或任何膜转运蛋白抑制剂与潜在的神经保护性底物的组合从未被评估过用于治疗脑损伤，尽管丙磺舒单独用于(安全地)评估脑损伤后脑脊液中有机酸的浓度。由于这些抑制剂利用还原型谷胱甘肽(GSH)将物质共同输出到细胞外，丙磺舒也维持细胞内GSH的储存，GSH是一种重要的内源性抗氧化剂。因此，丙磺舒本身可能通过维持内源性抗氧化剂储备(AOR)来保护神经，通过减少跨膜屏障的外排来提高外源性治疗的脑生物利用度。PI具有挑衅性的初步数据表明，丙磺舒和FDA批准的抗氧化剂N-乙酰半胱氨酸(NAC)的组合，协同恢复小鼠脑损伤后受损脑中的总AOR。这一点，再加上PI之前的报告显示，脑外伤后患者脑脊液中的总AOR减少了50%，提供了令人信服的翻译数据来支持这一组合策略。PIS的假设是，包括克服膜转运障碍的治疗的组合策略将协同提高临床使用的和新疗法在脑外伤后的生物利用度和疗效。具体目的是确定丙磺舒和NAC联合使用在体外和体内拉伤后神经元中协同减少氧化应激和改善神经学结局的能力；以及丙磺舒和NAC联合使用在严重脑外伤儿童中安全和协同降低氧化应激的能力。

DESCRIPTION (provided by applicant): There is a sense of urgency to move forward with pharmacological therapies that improve outcome after brain injury. Notably, traumatic brain injury (TBI) remains the leading cause of death and disability amongst children and young adults. To date, all clinical trials exploring single agents or therapies for TBI have failed. Unique impediments to effective treatment for TBI are ATP-binding cassette transporters and solute carriers on the blood-brain (BBB) and blood-cerebrospinal fluid (CSF) barriers which limit bioavailability of drugs to normal and injured brain by active and rapid re-uptake and export of drug back into blood. These barriers are often cited as a major explanation for the failure of clinical drug trials for CNS injury, and clearly limit the therapeutic indications for many drugs otherwise effective in non-CNS diseases. Membrane transporters include the multidrug resistance proteins, multidrug resistance-associated proteins, and organic anion transporters. Importantly, pharmacological inhibitors of these transporters have existed for decades, used to enhance bioavailability of drugs that are membrane transporter substrates. A prototype membrane transporter inhibitor is probenecid. Probenecid is currently in clinical use to treat uric acidemia, and was developed during World War II to increase the bioavailability of penicillin to wounded soldiers. The combination of probenecid or any membrane transporter inhibitor with a potentially neuroprotective substrate has never been evaluated for the treatment of TBI, although probenecid alone has been used (safely) to evaluate brain-CSF concentrations of organic acids after TBI. Since these inhibitors utilize reduced glutathione (GSH) to co-export substances out of cells, probenecid also maintains intracellular stores of GSH, a prominent endogenous antioxidant. As such, probenecid itself may be neuroprotective by maintaining endogenous antioxidant reserves (AOR), complimenting its capacity to improve brain bioavailability of exogenous treatments by reducing efflux across membrane barriers. The PIs have provocative preliminary data showing that the combination of probenecid and the FDA-approved antioxidant N-acetylcysteine (NAC), whose CNS use is limited by poor brain bioavailability, synergistically restore total AOR in injured brain after TBI in mice. This coupled with the PIs' previous report showing that total AOR in CSF from patients are reduced by > 50% after TBI, provides compelling translational data in support of this combinational strategy. The PIs' hypothesis is that combinational strategies that include therapies that overcome membrane transport barriers will synergistically improve bioavailability and efficacy of both clinically used and novel therapies after TBI. Specific aims are to define the capacity of the combination of probenecid and NAC to synergistically reduce oxidative stress and improve neurological outcome in neurons after stretch-induced trauma in vitro and in mice after TBI in vivo; and to define the capacity of the combination of probenecid and NAC to safely and synergistically reduce oxidative stress in children with severe TBI.