Previous Ingestion of Lactococcus lactis by Ethanol-Treated Mice Preserves Antigen Presentation Hierarchy in the Gut and Oral Tolerance Susceptibility.

BACKGROUND: Ethanol (EtOH) consumption is able to disturb the ovalbumin (OVA)-oral tolerance induction by interfering on the function of antigen presenting cells (APC), down-regulating dendritic cells (DCs) and macrophages and up-regulating B-lymphocytes and their function, which results in an overall allergic-type immune status. In this study, the potential of a priori administration of Lactococcus lactis (LL) in avoiding loss of oral tolerance in EtOH-treated mice was investigated. METHODS: Female C57BL/6 mice received, by oral route, ad libitum wild-type (WT) LL or heat-shock protein producer (Hsp65) LL for 4 consecutive days. Seven days later, mice were submitted to short-term high-dose EtOH treatment. After 24 hours, stomach, intestine, spleen, mesenteric lymph nodes (mLN) specimens were collected for biomarkers analysis. Following EtOH-treatment protocol, a group of animals underwent single-gavage OVA-tolerance protocol and sera samples collected for antibody analysis. RESULTS: The ingestion of WT LL or Hsp65 LL is able to restore oral tolerance to OVA in EtOH-treated mice, by reducing local and systemic allergic outcomes such as gastric mast cells and gut-interleukin-4, as well as serum IgE. WT LL treatment prevents the decrease of mLN regulatory T cells induced by the EtOH treatment. Moreover, LL treatment preserves APC hierarchy and antigen presentation commitment in EtOH-treated mice, with conserved DC and macrophage activity over B lymphocytes in mLN and preserved macrophage activity over DC and B-cell subsets in the spleen. CONCLUSIONS: The present findings suggest that a priori ingestion of LL preserves essential mechanisms associated with oral tolerance induction that are disturbed by EtOH ingestion. Maintenance of mucosal homeostasis by preserving APC hierarchy and antigen presentation commitment could be associated with T-regulatory subset activities in the gastrointestinal tract.

Immunological activities are modulated by enteral administration of an elemental diet in mice.

BACKGROUND & AIMS: Elemental diets (EDs) have been used successfully in treatment of some intestinal inflammatory diseases; however, the mechanism that mediates their effects is still unclear. In this study we evaluated the immunological effect of enteral administration of an ED in mice. METHODS: C57BL/6 mice were fed an ED (El-Diet) from weaning up to adulthood and immunological parameters were analyzed. RESULTS: El-Diet-fed mice presented an underdeveloped gut-associated-lymphoid tissue with lower numbers of TCRalphabeta+IELs and lamina propria cells and low levels of secretory IgA when compared to chow-fed mice. They showed a systemic decrease in the production of IgG and IgA as well as a skewing towards a Th2 profile of cytokine production upon in vitro stimulation with an increase in IL-4 and a reduction in IFN-gamma and IL-6 secretion. CONCLUSION: Our study demonstrated the role of EDs in modulating immunological activities in mice and proposes a rational for their successful use in treatment of some intestinal inflammatory diseases.