VACCINE CANDIDATE BASED ON OUTER MEMBRANE VESICLES FROM Bordetella pertussis TRIGGERS INFLAMMASOME ACTIVATION

ELIZAGARAY MAIA; HOZBOR DANIELA; RUMBO MARTÍN; MORENO GRISELDA

Mar del Plata

Congreso; LXVI Congreso de la Sociedad Argentina de Inmunología; 2018

SAI / SAIC / SAFIS

Outer-membrane vesicles (OMVs) are naturallynon-replicating spherical nanoparticles derived from Gram-negative bacteria.OMVs are highly immunogenic and consist of phospholipids, LPS, outer membraneproteins and entrapped periplasmic components. Because of their immunogenicproperties, self-adjuvanticity and ability to be taken up by mammalian cells,OMVs are attractive candidates for vaccine delivery platforms. We developed anew vaccine against pertussis based on OMVs from Bp, which have been shown tobe safe and to induce protection in mice, with a mixed Th1/Th17/Th2 profile, arobust antibody response and adequate protection capacity against different B.pertussis genetic background. The set of these cellular profiles depend on thedifferent innate immune system pathways that are previously activated.Inflammasomes are multimeric protein complexes from innate immunity that arecrucial for host defence against infection and response to endogenous dangersignals. It is reported the relevance of inflammasome activation by OMVs from otherbacteria species, particularly in the assembly of a Th17 adaptative response.In this study we demonstrate the ability ofOMVs Bp to activate the inflammasome and try to elucidate the pathways by whichit is activated.Classic and reporter THP1 cell lines werestimulated with OMVs Bp. Cytokines IL-1b, IL-18, IL-8 and LDH (lactatedehydrogenase) activity were measured in culture supernatant by ELISA and witha LDH-L kit, respectively. ASC specks formation from THP1-ASC-GFP cells wereobserved and quantified. SEAP (alkaline phosphatase) activity from THP1-Myd88KOculture supernatant was measured. Release of IL-1b from THP1 cells stimulatedwith 100 ng OMV Bp was significantly higher than control (11,378±0,114 pg/mL vs. 4,212±0,016 pg/mL; p≤0,001). The ratio ASC+/totalTHP1-ASC-GFP cells was significantly higher for cells stimulated with 200 ngOMV Bp in comparison with non-stimulated cells (6,837±0,621 vs.0,0±0,0. Positive control LPS+DNA: 7,267±0,509; p≤0,001). In accordance, the release of IL-1b from these THP1-ASC-GFP cells stimulated with200 ng OMV Bp was significantly higher than the non-stimulated ones (72,331±2,104 pg/mL vs. 4,091±0,0228 pg/mL p≤0,001). In this work we further characterize the immuneresponse triggered by our novel vaccine candidate. These results show for thefirst time the OMVs Bp capacity of inflammasome activation in a humanmacrophage cell line THP1. This activation was determined by IL-1b secretion inTHP1 and THP1-ASC-GFP culture supernatant and by quantification of ASC+ cellsin THP1-ASC-GFP culture.  Furthermore,this data would strengthen the concept of inflammasome activation as one of theinnate immune pathways with the ability to profile the protective adaptiveresponse of our vaccine.