L. plantarum, L. salivarius, and L. lactis Attenuate Th2 Responses and Increase Treg Frequencies in Healthy Mice in a Strain Dependent Manner

Abstract

Many studies on probiotics are aimed at restoring immune homeostasis in patients to prevent disease recurrence or reduce immune-mediated pathology. Of equal interest is the use of probiotics in sub-clinical situations, which are characterized by reduced immune function or low-grade inflammation, with an increased risk of infection or disease as a consequence. Most mechanistic studies focus on the use of probiotics in experimental disease models, which may not be informative for these sub-clinical conditions. To gain better understanding of the effects in the healthy situation, we investigated the immunomodulatory effects of two Lactobacillus probiotic strains, i.e. L. plantarum WCFS1 and L. salivarius UCC118, and a non-probiotic lactococcus strain, i.e. L. lactis MG1363, in healthy mice. We studied the effect of these bacteria on the systemic adaptive immune system after 5 days of administration. Only L. plantarum induced an increase in regulatory CD103+ DC and regulatory T cell frequencies in the spleen. However, all three bacterial strains, including L. lactis, reduced specific splenic T helper cell cytokine responses after ex vivo restimulation. The effect on IFN-γ, IL5, IL10, and IL17 production by CD4+ and CD8+ T cells was dependent on the strain administered. A shared observation was that all three bacterial strains reduced T helper 2 cell frequencies. We demonstrate that systemic immunomodulation is not only observed after treatment with probiotic organisms, but also after treatment with non-probiotic bacteria. Our data demonstrate that in healthy mice, lactobacilli can balance T cell immunity in favor of a more regulatory status, via both regulatory T cell dependent and independent mechanisms in a strain dependent manner.

Early-Life Sugar Consumption Affects the Rat Microbiome Independently of Obesity

“…Clostridium sensu stricto was also elevated by sugar and has been correlated with the development of food allergy or food sensitization during early life (53,54) and atopic dermatitis during childhood (55). Lactobacillus, a strain of bacteria associated with promoting regulatory T helper cells (56) and preserving tight junctions in the epithelial cells of the intestinal tract (57), was increased by sugar consumption, whereas previous studies showed that this strain is reduced in mice fed an HFD (58)(59)(60)(61). Alistipes (genus in the family Rikenellaceae) and Bacteroides (genus in the family Bacteroidaceae) were also significantly elevated in all sugar groups compared with controls.…”

The Probiotic Mixture VSL#3 Has Differential Effects on Intestinal Immune Parameters in Healthy Female BALB/c and C57BL/6 Mice

“…However, immunomodulation by probiotic bacteria in a simplified in vitro system or in an established inflammation model in vivo does not reflect effects in conditions of homeostasis. Only few studies have addressed the effects of probiotic bacteria in healthy subjects (24)(25)(26)(27), and substantial variability in the response of human subjects to probiotic intervention was found (28,29).…”

Probiotics Can Generate FoxP3 T-Cell Responses in the Small Intestine and Simultaneously Inducing CD4 and CD8 T Cell Activation in the Large Intestine

“…Besides the beneficial effects of probiotics in inflammatory disease, the disease-preventing potential of probiotic bacteria is gaining attention [18]–[21]. Probiotic treatment may benefit individuals who are not yet receiving medical treatment, but are at risk of developing disease due to age- [22], obesity- [23], malnutrition- [24], or stress-related [25] deterioration of immune homeostasis.…”