Targeting innate immunity to prevent CNS injury in neonatal meningitis

描述（由申请人提供）：B群链球菌（GBS）是新生儿第一年细菌性脑膜炎的最常见原因，占所有新生儿脑膜炎病例的近50%。新生儿的细菌性脑膜炎会导致严重的不可逆的认知和身体残疾，导致终身损害，尽管高效的抗菌治疗。我们已经成功地开发了体外模型，提供了证据表明，皮质神经元进行细胞死亡时，热灭活GBS或GBS（GBS-F）产生的可溶性因子，只有当小胶质细胞存在。此外，我们通过显示GBS和GBS-F介导的小胶质细胞活化都需要细胞表面受体Toll样受体2（TLR 2）和信号衔接蛋白MyD 88的功能表达来定义信号转导途径的相关组分。最后，我们确定了当小胶质细胞缺乏功能性TLR 2或MyDSS时，响应GBS或GBS-F的神经毒性未能发生。我们的初步数据表明革兰氏阳性菌感染、CMS先天免疫激活和随后的神经变性之间存在因果关系。这些结果支持开发针对调节小胶质细胞活性的特异性疗法作为预防细菌性脑膜炎的神经系统后果的手段的潜力。这种转化研究，如果是积极的，将导致治疗剂和临床试验的发展。我们的总体假设是，通过TLR 2-MyD 88依赖性机制激活CMS中的先天免疫是GBS脑膜炎背景下神经元发生旁观者损伤的原因。我们提出了两个具体的目标，这将使我们能够在体内测试这一途径的作用：具体目标1：以确定是否GBS（热灭活）介导的先天免疫激活引起神经元损伤，并依赖于功能性TLR 2和MyD 88在体内。假设：将热灭活的GBS引入新生小鼠的CMS中将引起神经元损伤，并且这种作用将依赖于功能性TLR 2和/或MyD 88的表达。具体目标2：确定GBS（活生物体）脑膜炎中的神经元损伤是否依赖于功能性TLR 2和MyD 88。假设：在用标准抗微生物疗法治疗的GBS（活的）脑膜炎中，神经元损伤将在缺乏功能性TLR 2或MyD 88的动物中受到限制。

DESCRIPTION (provided by applicant): Group B streptococcus (GBS) is the most common cause of bacterial, meningitis in the first year of life and accounts for nearly 50% of all cases of neonatal meningitis. Bacterial meningitis in newborn infants causes severe irreversible cognitive and physical disability resulting in life long impairment despite highly effective antimicrobial therapy. We have successfully developed in vitro modeling which provides evidence that cortical neurons undergo cell death when treated with heat-inactivated GBS or a soluble factor produced by GBS (GBS-F) only when microglia are present. Furthermore, we defined relevant components of the signal transduction pathway by showing that both GBS and GBS-F mediated activation of microglia require functional expression the cell surface receptor toll-like receptor 2 (TLR2) and the signaling adaptor protein MyD88. Finally, we established that the neurotoxicity in response to GBS or GBS-F failed to occur when microglia lacked functional TLR2 or MyDSS. Our preliminary data suggest a causal relationship between infection with gram-positive bacteria, activation of CMS innate immunity, and subsequent neurodegeneration. These results support the potential for development of specific therapies directed towards modulating microglial activity as a means of preventing the neurological consequences of bacterial meningitis. This translational research, if positive, will then lead to development of a therapeutic agent and clinical trial. Our overall hypothesis is that activation of innate immunity in the CMS through a TLR2-MyD88 dependent mechanism is responsible for the bystander injury that occurs to neurons in the setting of GBS meningitis. We propose two specific aims that will allow us to test the role of this pathway in vivo: Specific Aim 1: To determine if GBS (heat inactivated) mediated activation of innate immunity causes neuronal injury and is dependent on functional TLR2 and MyD88 in vivo. Hypothesis: Heat inactivated GBS introduced into the CMS of neonatal mice will cause neuronal injury and this effect will be dependent on expression of functional TLR2 and or MyD88. Specific Aim 2: To determine if neuronal injury in GBS (live organism) meningitis is dependent upon functional TLR2 and MyD88. Hypothesis: In GBS (live) meningitis treated with standard antimicrobial therapy, neuronal injury will be limited in animals lacking functional TLR2 or MyD88.