Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Department of Histopathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
Front Cell Infect Microbiol. 2018 Oct 2;8:330. doi: 10.3389/fcimb.2018.00330. eCollection 2018.
Intraocular tuberculosis (IOTB), an extrapulmonary manifestation of tuberculosis of the eye, has unique and varied clinical presentations with poorly understood pathogenesis. As it is a significant cause of inflammation and visual morbidity, particularly in TB endemic countries, it is essential to study the pathogenesis of IOTB. Clinical and histopathologic studies suggest the presence of in retinal pigment epithelium (RPE) cells. A human retinal pigment epithelium (ARPE-19) cell line was infected with a virulent strain of (H37Rv). Electron microscopy and colony forming units (CFU) assay were performed to monitor the adherence, invasion, and intracellular replication, whereas confocal microscopy was done to study its intracellular fate in the RPE cells. To understand the pathogenesis, the transcriptional profile of in ARPE-19 cells was studied by whole genome microarray. Three upregulated transcripts were also examined in human IOTB vitreous samples. Scanning electron micrographs of the infected ARPE-19 cells indicated adherence of bacilli, which were further observed to be internalized as monitored by transmission electron microscopy. The CFU assay showed that 22.7 and 8.4% of the initial inoculum of bacilli adhered and invaded the ARPE-19 cells, respectively, with an increase in fold CFU from 1 dpi (0.84) to 5dpi (6.58). The intracellular bacilli were co-localized with lysosomal-associated membrane protein-1 (LAMP-1) and LAMP-2 in ARPE-19 cells. The transcriptome study of intracellular bacilli showed that most of the upregulated transcripts correspond to the genes encoding the proteins involved in the processes such as adherence (e.g., and ), invasion (e.g., and ), virulence (e.g., and ), and intracellular survival (e.g., and as well as regulators of various metabolic pathways. Two of the upregulated transcripts () were also present in the vitreous samples of the IOTB patients. is phagocytosed by RPE cells and utilizes these cells for intracellular multiplication with the involvement of late endosomal/lysosomal compartments and alters its transcriptional profile plausibly for its intracellular adaptation and survival. The findings of the present study could be important to understanding the molecular pathogenesis of IOTB with a potential role in the development of diagnostics and therapeutics for IOTB.
眼内结核(IOTB)是眼部结核的一种肺外表现,具有独特且多样的临床表现,其发病机制尚不清楚。由于它是炎症和视力损害的一个重要原因,特别是在结核病流行的国家,因此研究 IOTB 的发病机制至关重要。临床和组织病理学研究表明,在视网膜色素上皮(RPE)细胞中存在 。使用一种强毒株(H37Rv)感染人视网膜色素上皮(ARPE-19)细胞系。进行电子显微镜和集落形成单位(CFU)测定以监测 的附着、入侵和细胞内复制,而共聚焦显微镜用于研究其在 RPE 细胞中的细胞内命运。为了了解发病机制,通过全基因组微阵列研究了 ARPE-19 细胞中 的转录谱。还在人眼内结核玻璃体样本中检查了 3 个上调的 转录本。感染的 ARPE-19 细胞的扫描电子显微镜图像表明了杆菌的附着,通过透射电子显微镜进一步观察到这些杆菌被内化。CFU 测定显示,初始接种菌的 22.7%和 8.4%附着并侵入 ARPE-19 细胞,从 1dpi(0.84)到 5dpi(6.58)的 CFU 倍数增加。细胞内杆菌与溶酶体相关膜蛋白-1(LAMP-1)和 LAMP-2 在 ARPE-19 细胞中共定位。细胞内杆菌的转录组研究表明,大多数上调的转录本对应于编码参与以下过程的蛋白质的基因:附着(例如, 和 )、入侵(例如, 和 )、毒力(例如, 和 )以及细胞内存活(例如, 和 )以及各种代谢途径的调节剂。上调的两个转录本( 和 )也存在于 IOTB 患者的玻璃体样本中。被 RPE 细胞吞噬,并利用这些细胞进行细胞内繁殖,涉及晚期内体/溶酶体区室,并可能改变其转录谱,以适应其细胞内适应和存活。本研究的结果对于理解 IOTB 的分子发病机制可能很重要,并可能对开发 IOTB 的诊断和治疗方法有潜在作用。