Free or nanoencapsulated Minthostachys verticillata essential oil as candidates for adjuvant in oral vaccine

MONTIRONI ID; ROMA D; PINOTTI A; ARSAUTE S; CECCHINI ME; MURA N; DI GIACOMO AL; MAÑAS F; ALUSTIZA F; BELLINGERI R; CARIDDI LN

Congreso; LXXI Reunión Científica Anual de la Sociedad Argentina de Inmunología; 2023

In previous studies, we have demonstrated that free and micro or nanoencapsulated essential oil (EO) from Minthostachys verticillata, an Argentinian plant, have adjuvant ability enhancing the immune response of different antigens by subcutaneous immunization in mice. In a recent study we reported that oral administration of EO result safe and maintained a tolerogenic environment in the intestinal mucosa of mice. The aim of this study was to evaluate the effect of oral administration of free (EO) and nanoencapsulated (NEO) essential oil on weaned piglets as possible candidates for adjuvants in oral vaccines to prevent post-weaning diarrhea. EO was extracted by hydrodistillation and nanoencapsulation was performed by the high-energy method using Tween 80 and Span 60 as surfactants. EO and NEO were chemically analyzed by gas chromatography-mass spectrometry (GC-MS). The cytotoxic effect of both was evaluated on human colorectal adenocarcinoma (Caco-2) cell line. For in vivo assay, thirty-six weaned piglets were randomly distributed in six groups of six animals each group (n=6). Each group received orally EO or NEO for 30 consecutive days. Group 1: Control group (not treated), Group 2: Vehicle control (Tween 80 0.75% v/v, Span 60 0.25% w/v and deionized water 99% v/v). Group 3: EO (10 mg/kg/day). Groups 4-6: NEO (2.5, 5 and 10 mg/kg/day, respectively). Subsequently, histological and hematological parameters, cytokines production, oxidative markers, and CD4+/CD8+ T cells were evaluated. The GC-MS analysis was similar in both. NEO was more toxic on Caco-2 cells than EO, but the toxicity was acceptable. NEO did not alter the morpho-physiology of digestive organs and decreased malondialdehyde concentrations in liver and kidney (p