title: Burkholderia pseudomallei Biofilm Promotes Adhesion, Internalization and Stimulates Proinflammatory Cytokines in Human Epithelial A549 Cells.
abstract: Burkholderia pseudomallei is a Gram-negative bacterium that causes melioidosis. Inhalational exposure leading to pulmonary melioidosis is the most common clinical manifestation with significant mortality. However, the role of B. pseudomallei biofilm phenotype during bacterial-host interaction remains unclear. We hypothesize that biofilm phenotype may play a role in such interactions. In this study, B. pseudomallei H777 (biofilm wild type), B. pseudomallei M10 (biofilm mutant) and B. pseudomallei C17 (biofilm-complemented) strains were used to assess the contribution of biofilm to adhesion to human lung epithelial cells (A549), intracellular interactions, apoptosis/necrosis and impact on proinflammatory responses. Confocal laser scanning microscopy demonstrated that B. pseudomallei H777 and C17 produced biofilm, whereas M10 did not. To determine the role of biofilm in host interaction, we assessed the ability of each of the three strains to interact with the A549 cells at MOI 10. Strain H777 exhibited higher levels of attachment and invasion compared to strain M10 (p < 0.05). In addition, the biofilm-complemented strain, C17 exhibited restored bacterial invasion ability. Flow cytometry combined with a double-staining assay using annexin V and propidium iodide revealed significantly higher numbers of early apoptotic and late apoptotic A549 cells when these were infected with strain H777 (1.52%) and C17 (1.43%) compared to strain M10 (0.85%) (p < 0.05). Strains H777 and C17 were able to stimulate significant secretion of IL-6 and IL-8 compared with the biofilm mutant (p < 0.05). Together, these findings demonstrated the role of biofilm-associated phenotypes of B. pseudomallei in cellular pathogenesis of human lung epithelial cells with respect to initial attachment and invasion, apoptosis and proinflammatory responses.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.|Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Chanikarn
authors.initials: C
authors.lastname: Kunyanee
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.|Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Watcharaporn
authors.initials: W
authors.lastname: Kamjumphol
authors.affiliation: Department of Oral Diagnosis, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand.|Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand.|Biofilm Research Group, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Suwimol
authors.initials: S
authors.lastname: Taweechaisupapong
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.|Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand.|Biofilm Research Group, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Sakawrat
authors.initials: S
authors.lastname: Kanthawong
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Suwin
authors.initials: S
authors.lastname: Wongwajana
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.|Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Surasak
authors.initials: S
authors.lastname: Wongratanacheewin
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Chariya
authors.initials: C
authors.lastname: Hahnvajanawong
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.|Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand.|Biofilm Research Group, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Sorujsiri
authors.identifier: http://orcid.org/0000-0001-7176-2924
authors.initials: S
authors.lastname: Chareonsudjai
mesh_terms: D000072283:A549 Cells; D001422:Bacterial Adhesion; D018441:Biofilms; D016957:Burkholderia pseudomallei / Q000502:physiology*; D016207:Cytokines / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D007113:Immunity, Innate; D007249:Inflammation / Q000378:metabolism; D042541:Intracellular Space / Q000382:microbiology; D050296:Microbial Viability; D010641:Phenotype
chemical_list: D016207:Cytokines