Vitamin D Metabolism in Leprosy

多年来，人们一直认为维生素D在麻风分枝杆菌(MLEP)的发病和治疗中起着重要作用。患有进行性、富含细菌的麻风型(L-LEP)的患者更有可能缺乏维生素D，并在临床上受益于中波紫外线(阳光)照射或饮食补充维生素D。这些患者还面临着疾病激活的巨噬细胞通过循环中的25-羟基维生素D(25D)过度调节合成活性维生素D代谢物1，25-二羟基维生素D(1，25D)的风险。另一方面，细胞内1，25D的合成和在维生素D受体(VDR)水平上的作用是对mLEP产生抗菌反应的关键。因此，控制维生素D代谢和作用的机制(S)是麻风的关键组成部分。我们最近的体外研究清楚地证明了维生素D系统的功能元件，包括CYP27B1-羟基酶和VDR分别在干扰素驱动的I型和II型、T-LEP和L-LEP肉芽肿中的差异表达。综上所述，这些临床和实验室发现使我们推测，mLEP感染和各自的T-LEP或L-LEP下游干扰素途径，将不同地影响巨噬细胞和其他感染微环境中VDR表达的炎症细胞中活性维生素D代谢产物的合成、代谢和功能。为了验证这一假设，我们将承担三个概念上新颖的机械论目标。首先，将在单细胞水平上定量定位T-LEP和L-LEP肉芽肿中维生素D系统的组成成分(CYP2R1，维生素D羟基酶；CYP27B1；CYP24A1，24-羟基酶；和VDR)。第二，T-LEP或L-LEP免疫反应分泌体及其相关的下游干扰素反应，将利用在项目1和3中开发的创新分子工具来表征T-LEP或L-LEP免疫反应分泌体对维生素D在人类炎症细胞中的代谢和免疫作用的协调作用。第三，利用最近构思的核糖核酸测序技术，将探讨人类宿主维生素D缺乏状态的功能后果及其在体外和体内对mLEP的免疫反应和杀伤的拯救。与其他CORT项目的实验结果结合分析时，预计这项工作将为操纵人类维生素D平衡以促进特定麻风病和一般肉芽肿形成疾病的先天和获得性免疫反应的实践奠定基础。

A role for vitamin D in the pathogenesis and treatment of Mycobacterium leprae (mLEP) has been presumed for many years. Pafients suffering from the progressive, bacilli-abundant lepromatous form (L-lep) ofthe disease are more likely to be vitamin D-deficient and benefit clinically from ultraviolet B (sunlight) irradiation or dietary supplementation vitamin D. Such patients are also at risk for developing dysregulated over- production of the active vitamin D metabolite 1,25-dihydroxyvitamin D (1,25D) from circulating 25- hydroxyvitamin D (25D) by disease-activated macrophages. On the other hand, intracellular 1,25D synthesis and action at the level of the vitamin D receptor (VDR) is crucial for mounting an antimicrobial response to mLEP. Therefore, the mechanism(s) that govern vitamin D metabolism and action in leprosy is a key component to the disease. Our recent studies In vitro clearly demonstrate the differential expression of the functional elements ofthe vitamin D system, including CYP27B1-hydroxylase and the VDR in Type I and II interferon-driven, T-lep and L-lep granulomas, respectively. Taken together, these clinical and laboratory findings lead us to theorize that mLEP Infection and the respective T-lep or L-lep downstream interferon- directed pathways, will differentially Impact the synthesis, metabolism and function of active vitamin D metabolites in the macrophage and other elicited, VDR-expressing inflammatory cells in the infectious microenvironment ofthe host with leprosy. To test this hypothesis, we will undertake three conceptually novel, mechanistic aims. First, the vitamin D system components (CYP2R1, vitamin D hydroxylase; CYP27B1; CYP24A1, 24-hydroxylase; and VDR) will be quantitatively mapped in T-lep and L-lep granulomas at the single cell level. Second, the orchestrated effects of T-lep or L-lep immune response secretomes, and associated downstream interferon responses, on the metabolism and immunoaction of vitamin D in human inflammatory cells will be characterized using innovative molecular tools developed in Projects 1 and 3. Third, using recently-conceived RNA sequencing technologies, the functional consequences ofthe human host vitamin D deficient state, and its rescue In vitro and in vivo, on immune responses to and killing of mLEP will be probed. When analyzed in concert with the experimental results of the other CORT projects, it is anticipated that this work will set the stage for the practice of manipulating human vitamin D balance in promotion ofthe innate and adaptive immune response in leprosy specifically and in granuloma-forming diseases in general.