MINTHOSTACHYS VERTICILLATA ESSENTIAL OIL ALONE OR MICROENCAPSULATED ACTIVATES TH1 CELLS AND INDUCES THE PRODUCTION OF OPSONIZING ANTIBODIES

NOELIA CAMPRA; MELINA VANESA MOLIVA ; SOFÍA ARSAUTE ; NAHUEL MATÍAS CAMACHO ; ALEJANDRO JAVIER PAREDES ; MARÍA CELESTE MORÁN ; BELKYS A. MALETTO ; SANTIAGO DANIEL PALMA ; SILVIA MARCELA ESTEIN ; ELINA BEATRIZ REINOSO ; LAURA NOELIA CARIDDI

Congreso; LXVIII REUNIÓN SAI; 2020

In a previous study, we demonstrated the adjuvant capacity of the Minthostachys verticillata essential oil (EO) (2.5 mg/ml) or microencapsulated essential oil (EOMC) (5 mg/ml) on the humoral and cellular immune response against Enterococcus faecium in Balb/c mice. The aim of this study was to evaluate the functionality of the specific antibodies produced and to quantify the IFN-γ and IL-4 cytokines. Balb/c mice (n=4 per group) were inoculated by subcutaneous injection (days 0, 14 and 28) as follows: Group 1: 100 µl saline solution; Group 2: 100 µl bacterin+EO (2.5 mg/ml); Group 3: 100 µl bacterin+ microcapsule wall material (2.5 mg/ml); Group 4: 100 μl bacterin+EOMC (5 mg/ml). In all groups, bacterin was of E. faecium. Seven days after the last booster, blood was obtained and serum was separated. Mice were sacrificed by cervical dislocation and spleens were removed to obtain splenic lymphocytes for cell proliferation assay. To evaluate the functionality of the antibodies, the Opsonophagocytic Killing Assay was carried out using different dilutions of the sera (1/100, 1/200, 1/500, 1/1000, 1/2000), E. faecium (1x107 CFU/ml), bovine PMNs (1x107cells/ml) suspensions and a source of bovine complement. Sera antibodies of mice from Group 4 mediated the opsonization of E. faecium and enhance the phagocytosis by PMNs up to the 1/500 dilution compared to Group 2, which was up to the 1/200 dilution (p<0.001). IFN-γ and IL-4 were quantified in the culture supernatants by sandwich ELISA. Higher levels of IFN-γ and IL-4 were detected in lymphocyte culture supernatants of Group 2 compared to other groups (p<0.001). In Group 2, IFN-γ levels were higher than IL-4 (p<0.001), indicating that the activation of CD4+ T cells by the vaccine formulation containing alone EO may result in a Th1 profile. The results obtained confirm that EO and EOMC activate humoral and cellular immunity and could be candidates for vaccine adjuvants.