Microaggregate-associated protein involved in invasion of epithelial cells byMycobacterium aviumsubsp.hominissuis

Abstract

Keywords: filamin A, host-pathogen interaction, invasion, lung mucosal epithelial cells, microaggregate, mycobacterium avium subsp hominissuisThe environmental opportunistic pathogen Mycobacterium avium subsp hominissuis (MAH), a member of the nontuberculous mycobacteria (NTM) cluster, causes respiratory as well as disseminated disease in patients such as those with chronic respiratory illnesses or AIDS. Currently, there is no effective method to prevent NTM respiratory infections. The formation of mycobacterial microaggregates comprises of phenotypic changes that lead to efficient adherence and invasion of the respiratory mucosa in vitro and in vivo. Microaggregate adhesion to the respiratory epithelium is mediated in part through the mycobacterial protein, MAV_3013 (MBP-1). Through DNA microarray analysis, the small hypothetical gene MAV_0831 (Microaggregate Invasion Protein-1, MIP-1) was identified as being upregulated during microaggregate formation. When MIP-1 was overexpressed in poorly-invasive Mycobacterium smegmatis, it provided the bacterium the ability to bind and enter epithelial cells. In addition, incubating microaggregates with recombinant MIP-1 protein enhanced the ability of microaggregates to invade HEp-2 cells, and exposure to anti-MIP-1 immune serum reduced the invasion of the host epithelium. Through protein-protein interaction assays, MIP-1 was found to bind to the host protein filamin A, a cytoskeletal actin-binding protein integral to the modulation of host cell shape and migration. As visualized by immunofluorescence, filamin A was able to colocalize with microaggregates and to a lesser extent planktonic bacteria. Invasion of HEp-2 cells by microaggregates and planktonic bacteria was also inhibited by the addition of anti-filamin A antibody suggesting that filamin A plays an important role during infection. In addition, at earlier time points binding and invasion assay results suggest that MBP-1 participates significantly during the first interactions with the host cell while MIP-1 becomes important once the bacteria adhere to the host epithelium. In summary, we have unveiled one more step associated with MAH crossing the respiratory mucosa.

Identification of Bicarbonate as a Trigger and Genes Involved with Extracellular DNA Export in Mycobacterial Biofilms

“…Furthermore, M. avium subsp. hominissuis forms mircoaggregates once in contact with respiratory epithelial cells and, once formed, the bacteria are more proficient at binding to and invading other cells (8–10). Surveilling macrophages that encounter M. avium subsp.…”

Investigating the Role of Mucin as Frontline Defense of Mucosal Surfaces against Mycobacterium avium Subsp. hominissuis

“…Monolayers were prepared by seeding 10 5 cells in each well of a 24-well tissue culture plate and incubated until achieving 90% confluency. Monolayers were then covered with 5% mucin MUC2 or MUC5b, and the ability of bacteria to enter the epithelial cells was investigated as previously reported [8,9]. In brief, monolayers were incubated with either M. avium 104 or P. aeruginosa, E. coli, S. aureus, and L. monocytogenes for 1 hour, the supernatant was removed, and the plate was washed with HBSS three times.…”

Genetic determinants of virulence and drug resistance of <i>Mycobacterium avium</i> subsp. <i>hominissuis</i> — a causative agent of mycobacteriosis in humans

“…Как и многие патогенные бактерии, МАН способны связываться с эпителиальными клетками, что приводит к образованию микроагрегатов и инвазии в слизистую оболочку дыхательных путей или желудочно-кишечного тракта, обеспечивая персистенцию в организме хозяина. Образование микроагрегатов предшес твует образованию биопленок, что частично объясняет устойчивость М. avium к антибиотикам и рецидивирующий характер респираторных инфекций [3,39].…”

“…Microaggregate Invasion Protein-1) в ходе формирования микроагрегатов. MIP-1 способствует эффективному проникновению сформировавшегося агрегата в эпителиальные клетки хозяина посредством взаимодействия с филамином А -актинсвязывающим структурным белком цитоскелета [3,39,47]. Продукты генов MAV_5138 и MAV_3679, регулируемые геном fadD2 (кодирует ацил-КоАсинтетазу), ответственны за инвазию МАН в эпителиальные клетки [15].…”