Background: Understanding macrophage behavior is key to decipher Mycobacterium tuberculosis (Mtb) pathogenesis. We studied the phenotype and ability of human monocyte-derived cells polarized with active vitamin D [1,25(OH)2D3] to control intracellular Mtb infection compared with polarization of conventional subsets, classical M1 or alternative M2. Methods: Human blood-derived monocytes were treated with active vitamin D or different cytokines to obtain 1,25(OH)2D3-polarized as well as M1- and M2-like cells or fully polarized M1 and M2 subsets. We used an in vitro macrophage Mtb infection model to assess both phenotype and functional markers i.e., inhibitory and scavenger receptors, costimulatory molecules, cytokines, chemokines, and effector molecules using flow cytometry and quantitative mRNA analysis. Intracellular uptake of bacilli and Mtb growth was monitored using flow cytometry and colony forming units. Results: Uninfected M1 subsets typically expressed higher levels of CCR7, TLR2, and CD86, while M2 subsets expressed higher CD163, CD200R, and CD206. Most of the investigated markers were up-regulated in all subsets after Mtb infection, generating a mixed M1/M2 phenotype, while the expression of CD206, HLADR, and CD80 was specifically up-regulated (P < 0.05) on 1,25(OH)2D3-polarized macrophages. Consistent with the pro-inflammatory features of M1 cells, Mtb uptake and intracellular Mtb growth was significantly (P < 0.01-0.001 and P < 0.05-0.01) lower in the M1 (19.3%) compared with the M2 (82.7%) subsets 4 h post-infection. However, infectivity rapidly and gradually increased in M1 cells at 24-72 h. 1,25(OH)2D3-polarized monocyte-derived cells was the most potent subset to inhibit Mtb growth at both 4 and 72 h (P < 0.05-0.01) post-Mtb infection. This ability was associated with high mRNA levels of pro-inflammatory cytokines and the antimicrobial peptide LL-37 but also anti-inflammatory IL-10, while expression of the immunosuppressive enzyme IDO (indoleamine 2,3-dioxygenase) remained low in Mtb-infected 1,25(OH)2D3-polarized cells compared with the other subsets. Conclusions: Mtb infection promoted a mixed M1/M2 macrophage activation, and 1,25(OH)2D3-polarized monocyte-derived cells expressing LL-37 but not IDO, were most effective to control intracellular Mtb growth. Macrophage polarization in the presence of vitamin D may provide the capacity to mount an antimicrobial response against Mtb and simultaneously prevent expression of inhibitory molecules that could accelerate local immunosuppression in the microenvironment of infected tissue.

中文翻译：

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人单核细胞衍生的细胞与维生素D极化可促进结核分枝杆菌感染的控制。

背景：了解巨噬细胞的行为是破译结核分枝杆菌（Mtb）发病机理的关键。与传统亚群，经典M1或替代M2的极化相比，我们研究了用活性维生素D [1,25（OH）2D3]极化的人单核细胞衍生细胞的表型和控制细胞内Mtb感染的能力。方法：用活性维生素D或不同的细胞因子处理人血源性单核细胞，以获得极化的1,25（OH）2D3以及M1和M2样细胞或完全极化的M1和M2亚群。我们使用体外巨噬细胞Mtb感染模型，使用流式细胞仪和定量mRNA分析评估表型和功能标记，即抑制和清除受体，共刺激分子，细胞因子，趋化因子和效应分子。使用流式细胞仪和菌落形成单位监测细菌的细胞内摄取和Mtb生长。结果：未感染的M1子集通常表达更高水平的CCR7，TLR2和CD86，而M2子集则表达更高的CD163，CD200R和CD206。在Mtb感染后，大多数研究的标记物在所有亚组中均上调，产生混合的M1 / M2表型，而1,206（OH）上的CD206，HLADR和CD80的表达被特异上调（P <0.05）。 2D3极化的巨噬细胞。与M1细胞的促炎特征一致，M1（19.3％）的Mtb摄取和细胞内Mtb生长显着降低（P <0.01-0.001和P <0.05-0.01），而M2（子集为82.7％）4 h感染后。但是，感染性在M1细胞中在24-72 h迅速并逐渐增加。1，25（OH）2D3极化的单核细胞衍生的细胞是在Mtb感染后4和72 h抑制Mtb生长的最有效子集（P <0.05-0.01）。这种能力与促炎细胞因子和抗菌肽LL-37以及抗炎IL-10的高mRNA水平有关，而免疫抑制酶IDO（吲哚胺2,3-二加氧酶）的表达在受Mtb感染的患者中仍然很低。 1,25（OH）2D3极化的细胞与其他子集相比。结论：Mtb感染促进了M1 / M2巨噬细胞的混合活化，表达LL-37但不表达IDO的1,25（OH）2D3极化单核细胞衍生的细胞最有效地控制了细胞内Mtb的生长。