Comparative Structural Study of Terminal Ends of Lipoarabinomannan from Mice Infected Lung Tissues and Urine of a Tuberculosis Positive Patient.,ACS Infectious Diseases

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Comparative Structural Study of Terminal Ends of Lipoarabinomannan from Mice Infected Lung Tissues and Urine of a Tuberculosis Positive Patient.
ACS Infectious Diseases ( IF 4.0 ) Pub Date : 2019-12-12 , DOI: 10.1021/acsinfecdis.9b00355
Prithwiraj De ₁ , Libin Shi ₁ , Claudia Boot ₂ , Diane Ordway ₁ , Michael McNeil ₁ , Delphi Chatterjee ₁

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Mycobacterium tuberculosis lipoarabinomannan (LAM) is a biomarker for active tuberculosis (TB) disease. The presence of LAM in the urine of TB patients, whether HIV positive or negative, has been validated by a gas chromatography/mass spectral method with good specificity (84%) and sensitivity (99%). However, point-of-care (POC) methods to detect TB LAM in urine using immunoassays have poor sensitivity and are limited to only HIV coinfected TB diagnosis. We hypothesized that these disappointing results with the POC methods may be due to the antibodies used in the immunoassays as there could be structural differences between LAM in vivo and LAM in vitro. To address this issue, we infected C3HeB/FeJ mice with M.tb W. Beijing SA161 and purified LAM from the lung. Analysis of these sources of LAM using a panel of existing mAbs revealed differences in epitope patterns. Conventionally, the non-reducing termini of LAM are identified by their release with endoarabinanase. These epitopes correspond to linear tetra-(Ara4), branched hexa-(Ara6) arabinofuranosides, and their mannose-capped versions. We discovered two distinct epitopes. In the first case, it was found that the non-reducing termini of LAM from M.tb strain SA161 are highly succinylated, especially when the LAM was isolated from the mouse lungs. In the second case, it was found that Cellulomonas endoarabinanase digestion of LAM from both SA161 and LAM from a TB+ HIV- patient's urine yielded epitopes based on 5 arabinoses as major components and a profound lack of Ara6. The epitopes based on 5 arabinoses from M.tb SA161 and from the LAM in human urine must result from underlying structural and thus epitope differences. These results suggest approaches to develop specific antibodies for POC tests for LAM in the urine of suspected TB patients.

中文翻译：

小鼠感染肺组织和结核阳性患者尿液中脂寡糖甘露聚糖末端的比较结构研究。

结核分枝杆菌脂阿拉伯甘露聚糖（LAM）是活动性结核（TB）疾病的生物标记。结核病患者尿液中LAM的存在，无论是HIV阳性还是阴性，都已经通过气相色谱/质谱法进行了验证，具有良好的特异性（84％）和敏感性（99％）。但是，使用免疫测定法检测尿液中TB LAM的现场护理（POC）方法灵敏度低，并且仅限于HIV合并感染的TB诊断。我们假设POC方法的这些令人失望的结果可能是由于免疫分析中使用的抗体所致，因为体内LAM和体外LAM之间可能存在结构差异。为了解决这个问题，我们用M.tb W. Beijing SA161感染了C3HeB / FeJ小鼠，并从肺中纯化了LAM。使用一组现有的mAb对LAM的这些来源进行分析，发现表位模式存在差异。常规上，LAM的非还原性末端是通过其与内阿拉伯聚糖酶的释放来鉴定的。这些表位对应于线性四-（Ara4），支链六-（Ara6）阿糖呋喃糖苷及其甘露糖封端的版本。我们发现了两个不同的表位。在第一种情况下，发现来自M.tb菌株SA161的LAM的非还原末端是高度琥珀酰化的，特别是当从小鼠肺中分离出LAM时。在第二种情况下，发现纤维单胞菌内切阿拉伯糖酶从SA161和L +感染TB + HIV患者的尿液中提取的LAM均产生了基于5种阿拉伯糖酶作为主要成分的表位，并且严重缺乏Ara6。基于来自M.的5种阿拉伯糖酶的表位 tb SA161和人尿液中的LAM必须归因于潜在的结构差异和表位差异。这些结果提示了开发可疑结核病患者尿液中用于LAM的POC检测的特异性抗体的方法。

更新日期：2019-12-13

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