Babrak Lmar, Danelishvili Lia, Rose Sasha J, Kornberg Tiffany, Bermudez Luiz E
Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, USA Department of Microbiology, College of Science, Oregon State University, Corvallis, Oregon, USA.
Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, USA.
Infect Immun. 2015 Feb;83(2):625-36. doi: 10.1128/IAI.02699-14. Epub 2014 Nov 24.
"Mycobacterium avium subsp. hominissuis" is an opportunistic environmental pathogen that causes respiratory illness in immunocompromised patients, such as those with cystic fibrosis as well as other chronic respiratory diseases. Currently, there is no efficient approach to prevent or treat M. avium subsp. hominissuis infection in the lungs. During initial colonization of the airways, M. avium subsp. hominissuis forms microaggregates composed of 3 to 20 bacteria on human respiratory epithelial cells, which provides an environment for phenotypic changes leading to efficient mucosal invasion in vitro and in vivo. DNA microarray analysis was employed to identify genes associated with the microaggregate phenotype. The gene encoding microaggregate-binding protein 1 (MBP-1) (MAV_3013) is highly expressed during microaggregate formation. When expressed in noninvasive Mycobacterium smegmatis, MBP-1 increased the ability of the bacteria to bind to HEp-2 epithelial cells. Using anti-MBP-1 immune serum, microaggregate binding to HEp-2 cells was significantly reduced. By far-Western blotting, and verified by coimmunoprecipitation, we observed that MBP-1 interacts with the host cytoskeletal protein vimentin. As visualized by confocal microscopy, microaggregates, as well as MBP-1, induced vimentin polymerization at the site of bacterium-host cell contact. Binding of microaggregates to HEp-2 cells was inhibited by treatment with an antivimentin antibody, suggesting that MBP-1 expression is important for M. avium subsp. hominissuis adherence to the host cell. MBP-1 immune serum significantly inhibited M. avium subsp. hominissuis infection throughout the respiratory tracts of mice. This study characterizes a pathogenic mechanism utilized by M. avium subsp. hominissuis to bind and invade the host respiratory epithelium, suggesting new potential targets for the development of antivirulence therapy.
“鸟分枝杆菌人型亚种”是一种机会性环境病原体，可导致免疫功能低下患者出现呼吸道疾病，如囊性纤维化患者以及患有其他慢性呼吸道疾病的患者。目前，尚无有效的方法来预防或治疗肺部鸟分枝杆菌人型亚种感染。在气道初始定植期间，鸟分枝杆菌人型亚种在人呼吸道上皮细胞上形成由3至20个细菌组成的微聚集体，这为表型变化提供了环境，从而导致在体外和体内实现有效的黏膜侵袭。采用DNA微阵列分析来鉴定与微聚集体表型相关的基因。编码微聚集体结合蛋白1（MBP-1）（MAV_3013）的基因在微聚集体形成过程中高度表达。当在非侵袭性耻垢分枝杆菌中表达时，MBP-1增强了细菌与HEp-2上皮细胞结合的能力。使用抗MBP-1免疫血清，微聚集体与HEp-2细胞的结合显著减少。通过远缘Western印迹法，并经免疫共沉淀验证，我们观察到MBP-1与宿主细胞骨架蛋白波形蛋白相互作用。通过共聚焦显微镜观察，微聚集体以及MBP-1在细菌与宿主细胞接触部位诱导波形蛋白聚合。用抗波形蛋白抗体处理可抑制微聚集体与HEp-2细胞的结合，这表明MBP-1的表达对于鸟分枝杆菌人型亚种黏附宿主细胞很重要。MBP-1免疫血清显著抑制了鸟分枝杆菌人型亚种在小鼠整个呼吸道中的感染。本研究描述了鸟分枝杆菌人型亚种用于结合并侵入宿主呼吸道上皮的致病机制，为抗毒力疗法的开发提出了新的潜在靶点。
