Probiotic Bacteria and Their Cell Walls Induce Th1-Type Immunity Against Salmonella Typhimurium Challenge

LEMME DUMIT, JOSE MARÍA; CAZORLA, SILVIA I; GABRIELA PERDIGÓN; MALDONADO GALDEANO, CAROLINA

FRONTIERS IN IMMUNOLOGY

Frontiers

Año: 2021

Probiotics have been associated with a variety of health benefits. They can act asadjuvant to enhance specific immune response. Bacterial cell wall (CW) molecules arekey structures that interact with host receptors promoting probiotic effects. The adjuvantcapacity underlying this sub-cellular fraction purified from Lactobacillus casei CRL431and L. paracasei CNCMI-1518 remains to be characterized. We interrogated themolecular and cellular events after oral feeding with probiotic-derived CW in additionto heat-inactivated Salmonella Typhimurium and their subsequent protective capacityagainst S. Typhimurium challenge. Intact probiotic bacteria were orally administered forcomparison. We find that previous oral feeding with probiotics or their sub-cellularfraction reduce bacterial burden in spleen and liver after Salmonella challenge. Antibodyresponses after pathogen challenge were negligible, characterized by not major changesin the antibody-mediated phagocytic activity, and in the levels of total and Salmonellaspecificintestinal sIgA and serum IgG, respectively. Conversely, the beneficial effect ofprobiotic-derived CW after S. Typhimurium challenge were ascribed to a Th1-type cellmediatedimmunity which was characterized by augmentation of the delayed-typehypersensitivity response. The cell-mediated immunity associated with the oral feedingwith probiotic-derived CW was accompanied with a Th1-cell polarizing cytokines,distinguished by increase IFN-g/IL-4 ratio. Similar results were observed with the intactprobiotics. Our study identified molecular events associated with the oral administrationof sub-cellular structures derived from probiotics and their adjuvant capacity to exertimmune modulatory function.