Saini Chaman, Ramesh Venkatesh, Nath Indira
National Institute of Pathology, Safdarjung Hospital Campus, New Delhi, India.
Department of Dermatology, Safdarjung Hospital, New Delhi, India.
PLoS Negl Trop Dis. 2014 Jan 16;8(1):e2639. doi: 10.1371/journal.pntd.0002639. eCollection 2014.
Lepromatous leprosy caused by Mycobacterium leprae is associated with antigen specific T cell unresponsiveness/anergy whose underlying mechanisms are not fully defined. We investigated the role of CD25(+)FOXP3(+) regulatory T cells in both skin lesions and M.leprae stimulated PBMC cultures of 28 each of freshly diagnosed patients with borderline tuberculoid (BT) and lepromatous leprosy (LL) as well as 7 healthy household contacts of leprosy patients and 4 normal skin samples.
METHODOLOGY/PRINCIPLE FINDINGS: Quantitative reverse transcribed PCR (qPCR), immuno-histochemistry/flowcytometry and ELISA were used respectively for gene expression, phenotype characterization and cytokine levels in PBMC culture supernatants. Both skin lesions as well as in vitro antigen stimulated PBMC showed increased percentage/mean fluorescence intensity of cells and higher gene expression for FOXP3(+), TGF-β in lepromatous (p<0.01) as compared to tuberculoid leprosy patients. CD4(+)CD25(+)FOXP3(+) T cells (Tregs) were increased in unstimulated basal cultures (p<0.0003) and showed further increase in in vitro antigen but not mitogen (phytohemaglutinin) stimulated PBMC (iTreg) in lepromatous as compared to tuberculoid leprosy patients (p<0.002). iTregs of lepromatous patients showed intracellular TGF-β which was further confirmed by increase in TGF-β in culture supernatants (p<0.003). Furthermore, TGF-β in iTreg cells was associated with phosphorylation of STAT5A. TGF-β was seen in CD25(+) cells of the CD4(+) but not that of CD8(+) T cell lineage in leprosy patients. iTregs did not show intracellular IFN-γ or IL-17 in lepromatous leprosy patients.
CONCLUSIONS/SIGNIFICANCE: Our results indicate that FOXP3(+) iTregs with TGF-β may down regulate T cell responses leading to the antigen specific anergy associated with lepromatous leprosy.
由麻风分枝杆菌引起的瘤型麻风与抗原特异性T细胞无反应性/无能相关，其潜在机制尚未完全明确。我们调查了28例新诊断的界线类偏结核型（BT）和瘤型麻风（LL）患者、7例麻风患者的健康家庭接触者以及4例正常皮肤样本的皮肤病变和麻风分枝杆菌刺激的外周血单个核细胞（PBMC）培养物中CD25(+)FOXP3(+)调节性T细胞的作用。
方法/主要发现：分别采用定量逆转录聚合酶链反应（qPCR）、免疫组织化学/流式细胞术和酶联免疫吸附测定（ELISA）检测PBMC培养上清液中的基因表达、表型特征和细胞因子水平。与结核样型麻风患者相比，瘤型麻风患者的皮肤病变以及体外抗原刺激的PBMC中，FOXP3(+)、转化生长因子-β（TGF-β）的细胞百分比/平均荧光强度增加，基因表达更高（p<0.01）。与结核样型麻风患者相比，瘤型麻风患者未刺激的基础培养物中CD4(+)CD25(+)FOXP3(+) T细胞（调节性T细胞）增加（p<0.0003），体外抗原刺激而非丝裂原（植物血凝素）刺激的PBMC中进一步增加（诱导性调节性T细胞，iTreg）（p<0.002）。瘤型麻风患者的iTreg细胞显示细胞内TGF-β，培养上清液中TGF-β增加进一步证实了这一点（p<0.003）。此外，iTreg细胞中的TGF-β与信号转导和转录激活因子5A（STAT5A）的磷酸化相关。麻风患者CD4(+)但非CD8(+) T细胞谱系的CD25(+)细胞中可见TGF-β。瘤型麻风患者的iTreg细胞未显示细胞内干扰素-γ（IFN-γ）或白细胞介素-17（IL-17）。
结论/意义：我们的结果表明，携带TGF-β的FOXP3(+) iTreg可能下调T细胞反应，导致与瘤型麻风相关的抗原特异性无反应性。
