Targeting M. Leprae survival strategies in the PNS

描述（由申请人提供）：麻风病仍然是一个重要的全球健康问题，是周围神经系统（PNS）感染性神经退行性疾病的典型例子。麻风分枝杆菌感染的雪旺细胞，PNS的神经胶质细胞，是麻风神经损伤的主要原因。我们最近的研究表明，非髓鞘化雪旺细胞，而非髓鞘化雪旺细胞，优先窝藏麻风分枝杆菌，因此作为持续感染的细胞内生态位。由于麻风分枝杆菌是一种专性细胞内病原体，具有最长的加倍时间和基因组中有限的基因数量，因此在无髓鞘雪旺细胞内建立生产感染是细菌存活的关键。然而，麻风分枝杆菌在雪旺细胞内存活的机制尚不清楚。针对麻风分枝杆菌的生存策略将为开发新的治疗方法来对抗神经损伤和疾病进展提供合理的依据。为了研究这些方面，我们使用原代人雪旺细胞（从人周围神经中分离纯化）作为模型，因为它们在体内的表型与无髓鞘雪旺细胞相似。体外培养的细胞内麻风分枝杆菌可维持数周的活力，而不会引起雪旺细胞凋亡或细胞病变。我们使用Affymetrix human GeneChips对感染活麻风分枝杆菌30天的原代人雪旺细胞制备的cRNA进行微阵列分析，发现大多数差异表达的雪旺细胞基因是(i)调节代谢和呼吸功能的酶，（ii）细胞周期调节剂/抑制剂，（iii）生长/神经营养因子，（iv）生长因子受体和(v)相关的转录和信号分子。因此，我们认为一旦感染，麻风分枝杆菌一方面有效地利用雪旺细胞机制来维持细菌的活力，另一方面通过调节雪旺细胞的生长来确保细胞内生态位的长期生存。为此，我们将研究以下内容：(1)麻风分枝杆菌对雪旺细胞代谢/分解功能的调节；(2)麻风分枝杆菌对人雪旺细胞周期的调节；(3)麻风分枝杆菌诱导的生长/神经营养因子及其对雪旺细胞信号传导、生长和功能的影响。这些研究将为PNS持续的麻风分枝杆菌感染、麻风患者的神经损伤和神经胶质细胞的基本生物学提供新的见解。

DESCRIPTION (provided by applicant): Leprosy remains an important global health problem, and represents a classical example of infectious neuro-degenerative diseases of the peripheral nervous system (PNS). Mycobacterium leprae infection of the Schwann cell, the glial cell of the PNS, is the primary cause for the nerve damage in leprosy. We have recently shown that the non-myelinating Schwann cell, but not the myelinated Schwann cell, preferentially harbors M. leprae, and thus serves as the intracellular niche for persistent infection. Because M. leprae is an obligate intra-cellular pathogen with the longest doubling time and a limited number of genes in its genome, the establishment of productive infection within non-myelinated Schwann cells is the key for bacterial survival. However, the mechanisms of M. leprae survival within Schwann cells are unknown. Targeting of M. leprae survival strategies will provide the rational to develop new therapeutics to combat the neurological injury and disease progression. To study these aspects, we used primary human Schwann cells (isolated and purified from human peripheral nerves) as a model, since they phenotypically resemble non-myelinated Schwann cells in vivo. Intracellular M. leprae in vitro maintain viability for several weeks without causing any apoptosis or cytopathic effect to Schwann cells. Microarray analysis using Affymetrix human GeneChips with cRNA prepared from primary human Schwann cells infected with viable M. leprae for 30 days, we showed that the majority of differentially expressed Schwann cells genes are (i) enzymes that regulate metabolic and respiratory functions, (ii) cell cycle regulators/inhibitors, (iii) growth/neurotropic factors, (iv) growth factor receptors and (v) associated transcriptional and signaling molecules. Therefore, we propose that once infected, M. leprae effectively use Schwann cell machinery on one hand to maintain the bacterial viability and the other hand to secure the intracellular niche for long-term bacterial survival by regulating Schwann cell growth. To study these, we will study the following: (1) M. leprae regulation of Schwann cell metabolic/catabolic functions, (2) Regulation of human Schwann cell cycle by M. leprae, and (3) M. leprae-induced growth/neurotropic factors and their effects on Schwann cell signaling, growth and functions. These studies should provide novel insight into the persistent M. leprae infection in the PNS, nerve damage in leprosy patients, and the basic biology of glial cells.