AIM2 involvement in inflammasome activation triggered by Outer Membrane Vesicles (OMVs) from Bordetella Pertussis

ELIZAGARAY MAIA LINA; RUMBO, MARTÍN; MORENO, GRISELDA; GUIMARAES, ERIKA S.; OLIVEIRA, SERGIO C.; GOMES, MARCO TÚLIO R.; HOZBOR, DANIELA F.

MODALIDAD VIRTUAL

Congreso; LXVIII Reunión Anual de la Sociedad Argentina de Inmunología; 2020

SAI, SAIC, SAFIS

The resurgence of pertussis has urged the development of new vaccines. We have characterized a vaccine candidate based on outer membrane vesicles derived from Bordetella pertussis (BpOMVs). This candidate has shown to be safe and protective with a mixed Th1/Th17/Th2 immune profile. We have demonstrated that our vaccine candidate is able to activate the inflammasome in a human macrophage cell line (THP1) and in murine Bone Marrow Derived Macrophages with a dependence on NLRP3 and Caspase 11. It is known that OMVs from different Gram-negative bacteria can carry genetic material inside itself or membrane associated. One of the intracellular dsDNA sensors capable of activate the inflammasome pathway is AIM2 (Absent In Melanoma 2). We evaluated inflammasome activation in AIM2-/- BMDM that were stimulated with 400ng of OMVsBp and IL-1β secretion was measured in culture supernatant by ELISA. We observed a decrease (p≤0.001) in IL-1β secretion from AIM2-/- cells under OMVsBp stimulation in comparison to BMDM from C57BL/6 mice. We performed western blot analysis of caspase 1 induction in the same scenario and the levels of Casp1 was also diminished compared to control. We therefore stimulated wt and AIM2-/- BMDM with BpOMVs previously treated with DNAse and the levels of IL-1b secretion were significantly diminished (p≤0.001). Pyroptosis is a lytic form of cell death induced by caspases that cleave gasderminD (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 lack of AIM2 significantly affects its secretion in comparison to control (p≤0.05). We show that our vaccine candidate activates the inflammasome via the dsDNA intracellular sensor AIM2 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.