Division of Pulmonary, Critical Care, and Sleep Medicine, The Dorothy M. Davis Heart and Lung Research Institute, Columbus, OH, USA.
Dept of Microbial Infection and Immunity, Center for Microbial Interface Biology, Columbus, OH, USA.
Eur Respir J. 2021 Mar 18;57(3). doi: 10.1183/13993003.02695-2020. Print 2021 Mar.
Sarcoidosis and tuberculosis are granulomatous pulmonary diseases characterised by heightened immune reactivity to antigens. We hypothesised that an unsupervised analysis comparing the molecular characteristics of granulomas formed in response to antigens in patients with sarcoidosis or latent tuberculosis infection (LTBI) would provide novel insights into the pathogenesis of sarcoidosis.
A genomic analysis identified differentially expressed genes in granuloma-like cell aggregates formed by sarcoidosis (n=12) or LTBI patients (n=5) in an established human granuloma model wherein peripheral blood mononuclear cells were exposed to antigens (beads coated with purified protein derivative) and cultured for 7 days. Pathway analysis of differentially expressed genes identified canonical pathways, most notably antigen processing and presentation phagolysosomes, as a prominent pathway in sarcoidosis granuloma formation. The phagolysosomal pathway promoted mechanistic target of rapamycin complex 1 (mTORc1)/STAT3 signal transduction. Thus, granuloma formation and related immune mediators were evaluated in the absence or presence of various pre-treatments known to prevent phagolysosome formation (chloroquine) or phagosome acidification (bafilomycin A1) or directly inhibit mTORc1 activation (rapamycin).
In keeping with genomic analyses indicating enhanced phagolysosomal activation and predicted mTORc1 signalling, it was determined that sarcoidosis granuloma formation and related inflammatory mediator release was dependent upon phagolysosome assembly and acidification and mTORc1/S6/STAT3 signal transduction.
Sarcoidosis granulomas exhibit enhanced and sustained intracellular antigen processing and presentation capacities, and related phagolysosome assembly and acidification are required to support mTORc1 signalling to promote sarcoidosis granuloma formation.
结节病和结核病是两种肉芽肿性肺部疾病，其特征是针对抗原的免疫反应增强。我们假设，对结节病（n=12）或潜伏性结核感染（LTBI）患者（n=5）针对抗原形成的肉芽肿的分子特征进行无监督分析，将为结节病的发病机制提供新的见解。
在一个已建立的人类肉芽肿模型中，通过基因组分析鉴定了在抗原（珠粒包被有纯化蛋白衍生物）暴露并培养 7 天的外周血单核细胞中形成的肉芽肿样细胞聚集体中差异表达的基因，这些患者分别患有结节病或 LTBI。差异表达基因的途径分析确定了经典途径，尤其是抗原加工和呈递吞噬体，是结节病肉芽肿形成的主要途径。吞噬体途径促进了雷帕霉素复合物 1（mTORc1）/STAT3 信号转导的机械靶点。因此，在存在或不存在已知可防止吞噬体形成（氯喹）或吞噬体酸化（巴弗洛霉素 A1）或直接抑制 mTORc1 激活（雷帕霉素）的各种预处理的情况下，评估了肉芽肿形成和相关免疫介质。
与基因组分析表明增强的吞噬体激活和预测的 mTORc1 信号一致，确定结节病肉芽肿形成和相关炎症介质释放依赖于吞噬体组装和酸化以及 mTORc1/S6/STAT3 信号转导。
结节病肉芽肿表现出增强和持续的细胞内抗原加工和呈递能力，相关的吞噬体组装和酸化是支持 mTORc1 信号转导以促进结节病肉芽肿形成所必需的。
