TB Meningitis: Evaluating CSF Immunology to Discover Hidden Disease and Potential Immunomodulatory Therapies

摘要 在撒哈拉以南非洲，结核性脑膜炎（TBM）是成人脑膜炎的第二大常见原因。 脑膜炎是艾滋病毒感染者发病和死亡的主要原因。当宿主免疫- 尽管免疫缺陷明显驱动了TBM的发病机制，但病理性免疫应答也可使疾病恶化。关键 HIV相关的TBM发病机制的驱动因素尚未确定，但可能与HIV阴性的TBM不同，因此， HIV感染者中TBM发病机制的研究是有必要的和创新的。 在这一脆弱人群中进行宿主定向治疗的机会尚未探索。优化 治疗HIV/TBM和提高生存率，关键是要充分表征宿主反应的网站 感染和识别与良好或不良结果相关的免疫特征。为了迎接挑战，我们带来了 我们在结核病实验免疫学方面的技能，与经验丰富的研究团队相匹配， 乌干达艾滋病相关脑膜炎临床和转化研究的良好记录。 众所周知，诊断TBM非常困难。标准方法的灵敏度很低（约50%），只能检测到 TBM患者的一个子集，可能具有最高的CSF细菌负荷。在这些患者中，功能减退或 病理性免疫反应，代表免疫功能的相反极端，可能导致不良的免疫反应。 宿主控制感染。Xpert Ultra的灵敏度更高，能够半定量诊断 CSF细菌的负担较低，并确定了一组具有更好的感染免疫控制。我们 初步数据表明，微量或极低Xpert Ultra诊断与更好的生存率相关。 在这个项目中，我们提出了一个新的微生物/免疫学框架来理解TBM， 根据不同的Xpert Ultra PCR循环阈值对患者进行分类，作为以下指标的替代 CSF细菌负荷。我们试图通过定义包括生存期在内的疾病结局来质疑这一框架 和神经认知测试，同时将这些发现与 CSF中细胞免疫应答的免疫学分析。 我们的中心假设是CSF免疫特征与TBM疾病的关键方面相关 发病机制，包括诊断敏感性、疾病结果和治疗反应。为了验证这个，我们 将对CSF样本进行高参数光谱流式细胞术和多重细胞因子分析 和HIV/TBM患者的尸检标本。通过比较这些全面的免疫学数据， CSF细菌负荷高或低的患者组，结局良好或不良的患者组，以及 标准与高剂量利福平治疗的临床试验背景下，我们的目的是确定关键的贡献 宿主免疫对TBM发病机制的影响如果我们的假设是正确的，这项研究的意义是， 免疫调节治疗需要定制以解决免疫应答的缺乏或过度。

Abstract In Sub-Saharan Africa, tuberculous meningitis (TBM) is the second most common cause of adult meningitis, and a major cause of morbidity and mortality among people living with HIV. While host immuno- deficiency clearly drives TBM pathogenesis, pathologic immune responses can also worsen disease. The key drivers of HIV-associated TBM pathogenesis remain undefined but likely differ from HIV-negative TBM, thus a study of the pathogenesis of TBM in HIV-infected humans is warranted and innovative. Opportunities for host-directed therapy in this vulnerable population remain unexplored. To optimize treatment of HIV/TBM and improve survival, it is critical to fully characterize host responses at the site of infection and identify immune signatures associated with good or poor outcomes. To this challenge, we bring our skills in experimental immunology of tuberculosis, matched with an experienced research team with a proven track record of clinical and translational research regarding AIDS-related meningitis in Uganda. Diagnosing TBM is notoriously difficult. The poor sensitivity (~50%) of standard methodologies detects only a subset of those with TBM, likely with the highest CSF bacillary burden. In these patients hypo-functional or pathologic immune responses, representing opposite extremes of immune function, may contribute to poor host control of infection. The higher sensitivity of Xpert Ultra enables semi-quantitative diagnosis of those with a lower burden of CSF bacteria and identifies a group with better immune control of the infection. Our preliminary data suggest that diagnosis with trace or very low Xpert Ultra is associated with better survival. In this project, we propose a new microbiologic/immunologic framework for understanding TBM, categorizing patients based on the differing Xpert Ultra PCR cycle-threshold, which serve as a surrogate for CSF bacterial burden. We seek to interrogate this framework by defining disease outcomes including survival and neurocognitive testing in these different framework groups, while correlating these findings with immunologic analyses of cellular immune responses in the CSF. Our central hypothesis is that CSF immune signatures correlate with key aspects of TBM disease pathogenesis including sensitivity of diagnostics, disease outcomes, and treatment responses. To test this, we will perform high parameter spectral flow cytometry and multiplex cytokine profiling of samples from the CSF and autopsy specimens of patients with HIV/TBM. By comparing these comprehensive immunologic data in groups of patients with either high or low CSF bacterial burden, in those with good or poor outcomes, and in the context of a clinical trial of standard vs high dose rifampin treatment, we aim to define the key contributions of host immunity to TBM pathogenesis. If our hypothesis is correct, the implications of this research are that immunomodulatory therapy will need to be customized to address the paucity or excess of immune responses.