CONICET | Buscador de Institutos y Recursos Humanos

The resurgence of pertussis in different countries has urged the development of new vaccines that could overcome the weakness of current vaccines. Under this context we have already identified and characterized with very good results, a vaccine candidate based on outer membrane vesicles (OMVs). This new vaccine has shown to be safe and able to induce protection in mice, with a mixed Th1/Th17/Th2 profile and a robust antibody response. In this study, we investigated the ability of OMVs derived from Bordetella pertussis (Bp-OMVs), to trigger the activation of inflammasome-dependent pathways. To this end, we evaluated the secretion of hIL-1beta, hIL-18 and ASC-speck formation after the treatment of THP-1 cells with different quantities of Bp-OMVs (5ng-5ug/well). We detected significantly higher levels of hIL-1b and hIL-18 in culture supernatants stimulated with 200ng Bp-OMV (or more) vs. non-treated THP-1 cells (hIL-1b: 452,4±4,6pg/mL vs 4,4±0,5 pg/mL; p≤0,0001), (hIL-18: 2398,0±219,2pg/mL vs 203,0±113,1pg/mL; p≤0,0012). For this concentration of Bp-OMVs, the ASC-speck formation quantified by microscopy as ASC+/total cells, was 6,8±0,6 vs non-detected value for non-treated THP-1 cells. For the treatment LPSE.coli (1ug/mL) +DNA (500ng/mL) used as positive control, the ASC-speck formation in the THP-1 cells was 7,3±0,5 ASC+/total cells. We also evaluated the ability of Bp-OMVs to induce pyroptosis in treated THP-1 cells. To this end, LDH activity was measured in cell culture supernatants. The LDH activity measured in Bp-OMV stimulated cells shown 56,3% LDH release vs CTR; p≤0,05 (percentage of the mean value of LDH release compared to non-treated cells which was used as a reference value set to 100%). Our findings indicate that Bp-OMVs can activate the ASC-dependent inflammasomes, which could be key to trigger the protective immune response exerted by our vaccine candidate.