Outer Membrane Vesicles from Bordetella pertussis require NLRP3 and potassium efflux to trigger canonical inflammasome activation.

ELIZAGARAY MAIA; GOMES MARCO TULIO; GUIMARAES ERIKA; RUMBO MARTÍN; HOZBOR DANIELA; OLIVEIRA SERGIO C; MORENO GRISELDA

San Miguel de Tucumán

Congreso; LXVII Reunión Científica Anual de la Sociedad Argentina de Inmunología; 2019

Sociedad Argentina de Inmunología

The resurgence of pertussis has urged the development of new vaccines that could overcome the weakness of current vaccines. We have characterized a vaccine candidate based on outer membrane vesicles derived from Bordetella pertussis (OMVsBp). The OMVsBp has shown to be safe and protective with mixed Th1/Th17/Th2 profile. We have demonstrated that our vaccine candidate is able to activate the inflammasome in a human macrophage cell line (THP1). Now we evaluated inflammasome activation triggered by OMVsBp using Bone Marrow Derived Macrophages (BMDM) from C57BL/6 and NLRP3 deficient mice. The BMDM stimulated with 400ng of OMVsBp. The IL-1β secretion level was measured in culture supernatant by ELISA. We observed an increase (p≤0.001) in IL-1β secretion in cells stimulated with OMVsBp. We observed a decrease (p≤0.001) in IL-1β secretion from NLRP3 KOs mice under OMVsBp stimulation. The K+ efflux is a necessary event in NLRP3 activation so we exposed cells to high extracellular concentrations of K+ (80mM) plus OMVsBp. There was a decrease (p≤0.001) in IL-1β secretion. Pyroptosis is a lytic form of cell death induced by caspases that cleave gasdermin D (GSDMD). GSDMD was identified as a factor downstream of caspase-1 or 11 to mediate the release of interleukin IL-1β and IL-1α. We tested IL-1α secretion in culture media as a measure of GSDMD pore formation and found that NLRP3 is dispensable for this process. We show that our vaccine candidate activates the inflammasome canonical pathway in mice BMDM. This might be one of the innate mechanisms that orchestrates the adaptive immune response responsible of the protective capacity of our vaccine.