Facultad de Ciencias de la Salud

Intestinal mononuclear phagocytes (MPs) comprise dendritic cells (DCs) and macrophages (M0s) that play different roles in response to Salmonella infection. After phagocytosis, DCs expressing CD103 transport Salmonella from the intestinal tract to the mesenteric lymph nodes (MLN) and induce adaptive immune responses whereas resident M0s expressing CX3CR1 capture bacteria in the lumen and reside in the lamina propria (LP) where they induce a local immune response. CX3CR1+ M0s are generated from Ly6Chi monocytes that enter the colonic mucosa and differentiate locally. We previously demonstrated that the probiotic yeast Saccharomyces boulardii CNCM I-745 (S.b) prevents infection by Salmonella enterica serovar Typhimurium (ST), decreases ST translocation to the peripheral organs and modifies the pro-and anti-inflammatory cytokine profiles in the gut. In the present study, we investigated the effect of S.b on the migratory CD103+ DCs and the resident CX3CR1+ M0s. MPs were isolated from the LP of streptomycin-treated mice infected by ST with or without S.b treatment before or during the infection. In S.b-pretreated mice, we observed a decrease of the CD103+ DCs in the LP that was associated with the drop of ST recovery from MLN. Interestingly, S.b induced an infiltration of LP by classical Ly6Chi monocytes, and S.b modified the monocyte-M0 maturation process in ST-infected mice. Our results showed that S.b treatment induced the expansion of Ly6Chi monocytes in the blood as well as in the bone marrow (BM) of mice, thus contributing to the M0 replenishment in LP from blood monocytes. In vitro experiments conducted on BM cells confirmed that S.b induced the expansion of CX3CR1+ M0s and concomitantly ST phagocytosis. Altogether, these data demonstrate that Saccharomyces boulardii CNCM I-745 modulates the innate immune response. Although here, we cannot explicitly delineate direct effects on ST from innate immunity, S. b-amplified innate immunity correlated with partial protection from ST infection. This study shows that S.b can induce the expansion of classical monocytes that are precursors of resident M0s in the LP.

To assess the effects of a probiotic upon oral health indices in adolescents and to establish relationships between these indices and dietary habits and oral hygiene. Twenty-seven adolescents between 12 and 18 years of age were randomized into two groups. The study group received tablets containing Lactobacillus reuteri DSM 17938/ATCC 5289 for 28 days, while the control group received tablets without any bacteria. Streptococcus mutans, Lactobacillus sp., and salivary pH were assessed at baseline and at 7, 14, 21, 28, and 45 days. The plaque, gingivitis, and bleeding indices were recorded at baseline and at 14, 28, and 45 days. Dietary and oral hygiene habits were also evaluated by means of a questionnaire. A less marked rise in S. mutans was recorded in the study group. Improvements were observed in terms of plaque, gingivitis, and bleeding, though statistical significance was not reached. Oral pH increased in the study group, though not to a significant degree. Poorer eating habits were significantly correlated to increased plaque. The study parameters decreased with the two strains of L. reuteri DSM 17938 and ATCC PTA 5289, though the results failed to reach statistical.