Effect of U-Omp19 from Brucella spp. on intestinal epithelial cells

CORIA, LORENA M.; GUAIMAS, FRANCISCO F; FERRERO, MARIANA; PASQUEVICH, KARINA A.; BRUNO, LAURA A.; RISSO, GABRIELA S.; CASSATARO, JULIANA

Buenos Aires

Congreso; LXV Reunión Anual de la Sociedad Argentina de Inmunología (SAI); 2017

SAI

Our group have been working in the usefulness of a protease inhibitor (U-Omp19) from Brucella spp. as vaccine adjuvant. We previously demonstrated that U-Omp19 inhibits main gastrointestinal proteases protecting co-delivered antigens (Ags) from digestion thus increasing immune responses. Our current hypothesis is that after bypassing stomach and pancreatic proteases, vaccine formulations comprising U-Omp19 could face proteolytic digestion by brush border and intracellular proteases from enterocytes. Thus, in this work, we evaluated the effect of U-Omp19 on intestinal epithelial cells. Results demonstrated that U-Omp19 can inhibit protease activities from murine intestinal brush-border membranes (p0.01) and cysteine proteases from human Caco-2 and HT29 epithelial cells (p0.01). We also demonstrated by confocal microscopy that U-Omp19 co-administration with Ag on Caco-2 cells promoted Ag (OVA) accumulation within Lamp-2+ endosomal compartments (p0.001). In addition, using transwell plates we have shown that U-Omp19 facilitated the transcellular passage of Ag (OVA) through Caco-2 epithelial cell monolayers (p0.01). Transepithelial electric resistance (TEER) values remained unaltered during transcytosis of Ag and/or U-Omp19 confirming that the epithelial barrier integrity was unaltered by the formulations. Finally, oral co-delivery of U-Omp19 with Ag in mice induced the production of Ag-specific IgA at feces and the recruitment of CD103+ CD11b- CD8α+ dendritic cell (DC) subset to Peyer Patches. This particular DC subset has a key role in the induction of IgA producing plasma cells at the lamina propria and it has been associated with Ag cross-presentation to CD8+ T cells. Our results demonstrate that U-Omp19 co-delivery protects Ag digestion by brush border and intracellular enterocyte proteases, facilitating Ag transport across the intestinal epithelial barrier and increasing the amount of Ag that could reach DCs for the induction of appropriate immune responses.