Burkholderia: Characterizing Lung Innate Immunity

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DESCRIPTION (provided by applicant): Burkholderia (B.) mallei is a highly evolved Gram-negative bacterium that primarily infects solipeds but it is transmissible to humans by ingestion, cutaneous or aerosol exposures. Concern over this bacterium and the very closely related species B. pseudomallei has heightened because of the pathogens' seemingly perfect characteristics for malevolent uses as bioterror or biowarfare weapons against both animals and humans. In modern times their potential destructive impact on public health has escalated due to the pathogens' opportunistic infection of diabetic and immuno-compromised people, two growing populations worldwide. Virtually nothing is known about the interaction between Burkholderia and resident human lung cells, specifically bronchial respiratory epithelial cells (bREC) and alveolar epithelial cells (AEC) in combination with the underlying human pulmonary microvascular endothelial cells (HPMEC). The respiratory epithelium is a dynamic interface between the outside environment and the host. bREC and AEC are vital for maintaining lung homeostasis and providing a physical barrier against inhaled pathogens. Two inducible defense mechanisms provided by bREC and AEC include the production of antimicrobial factors and secreting cytokines for the recruitment and activation of immune cells. Therefore, we will use our novel biological relevant transwell filter model consisting of physiologically positioned human primary bREC or AEC and HPMEC in co-culture to determine invasion of and replication in these host cells by B. mallei and B. pseudomallei. Further, we will use B. mallei or B. pseudomallei to stimulate co-cultures and collect the co-culture conditioned medium to quantify cytokines. The second goal of this proposal we will assess if the co-cultures and/or their secreted soluble factors have the ability to influence how immune cells response to Burkholderia. This would be the first study to examine the interaction and response of human primary lung cells to Burkholderia. These studies are essential for gaining insight into the lung pathogenesis of Burkholderia, and will identify novel avenues for targeted vaccine development. PUBLIC HEALTH RELEVANCE: Burkholderia mallei and Burholderia pseudomallei can be used as a bioweapon against the public. Therefore, this application proposes to better understand how this organism interacts with lung cells and response of the lung cells to Burkholderia. This funding of this proposal will provide crucial insight into the effective and ineffective innate immune responses to help find future vaccines and therapeutic development.