Aulicino Anna, Dinan Adam M, Miranda-CasoLuengo Aleksandra A, Browne John A, Rue-Albrecht Kévin, MacHugh David E, Loftus Brendan J
School of Medicine & Medical Science, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
Animal Genomics Laboratory, UCD School of Agriculture and Food Science, College of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.
BMC Genomics. 2015 Dec 9;16:1046. doi: 10.1186/s12864-015-2246-1.
Mycobacterium abscessus (MAB) is an emerging pathogen causing pulmonary infections in those with inflammatory lung disorders, such as Cystic Fibrosis (CF), and is associated with the highest fatality rate among rapidly growing mycobacteria (RGM). Phenotypically, MAB manifests as either a Smooth (MAB-S) or a Rough (MAB-R) morphotype, which differ in their levels of cell wall glycopeptidolipids (GPLs) and in their pathogenicity in vivo. As one of the primary immune cells encountered by MAB, we sought to examine the early transcriptional events within macrophages, following infection with both MAB-S or MAB-R.
We sampled the transcriptomes (mRNA and miRNA) of THP-1-derived macrophages infected with both MAB-R and MAB-S at 1, 4 and 24 h post-infection (hpi) using RNA-seq. A core set of 606 genes showed consistent expression profiles in response to both morphotypes, corresponding to the early transcriptional response to MAB. The core response is type I Interferon (IFN)-driven, involving the NF-κB and MAPK signaling pathways with concomitant pro-inflammatory cytokine production, and network analysis identified STAT1, EGR1, and SRC as key hub and bottleneck genes. MAB-S elicited a more robust transcriptional response at both the mRNA and miRNA levels, which was reflected in higher cytokine levels in culture supernatants. The transcriptional profiles of macrophages infected with both morphotypes were highly correlated, however, and a direct comparison identified few genes to distinguish them. Most of the induced miRNAs have previously been associated with mycobacterial infection and overall miRNA expression patterns were similarly highly correlated between the morphotypes.
The report here details the first whole transcriptome analysis of the early macrophage response to MAB infection. The overall picture at the early stages of macrophage infection is similar to that of other mycobacteria, reflected in a core type I IFN and pro-inflammatory cytokine response. Large-scale transcriptional differences in the host response to the different MAB morphotypes are not evident in the early stages of infection, however the subset of genes with distinct expression profiles suggest potentially interesting differences in internal trafficking of MAB within macrophages.
脓肿分枝杆菌（MAB）是一种新兴病原体，可在患有炎症性肺部疾病（如囊性纤维化（CF））的患者中引起肺部感染，并且在快速生长分枝杆菌（RGM）中死亡率最高。在表型上，MAB表现为光滑型（MAB-S）或粗糙型（MAB-R）两种形态，它们在细胞壁糖肽脂（GPL）水平及体内致病性方面存在差异。作为MAB遇到的主要免疫细胞之一，我们试图研究巨噬细胞在感染MAB-S或MAB-R后的早期转录事件。
我们使用RNA测序技术，在感染后1小时、4小时和24小时（hpi）对感染了MAB-R和MAB-S的THP-1来源的巨噬细胞的转录组（mRNA和miRNA）进行了采样。一组606个核心基因在对两种形态的反应中表现出一致的表达谱，对应于对MAB的早期转录反应。核心反应由I型干扰素（IFN）驱动，涉及NF-κB和MAPK信号通路，并伴随促炎细胞因子的产生，网络分析确定STAT1、EGR1和SRC为关键枢纽基因和瓶颈基因。MAB-S在mRNA和miRNA水平上引发了更强有力的转录反应，这反映在培养上清液中更高的细胞因子水平上。然而，感染两种形态的巨噬细胞的转录谱高度相关，直接比较发现很少有基因能区分它们。大多数诱导的miRNA此前已与分枝杆菌感染相关，并且两种形态之间的总体miRNA表达模式同样高度相关。
本报告详细介绍了巨噬细胞对MAB感染早期反应的首次全转录组分析。巨噬细胞感染早期的总体情况与其他分枝杆菌相似，表现为核心I型干扰素和促炎细胞因子反应。在感染早期，宿主对不同MAB形态的反应中大规模转录差异并不明显，然而具有不同表达谱的基因子集表明，MAB在巨噬细胞内的内部运输可能存在潜在有趣的差异。
