Modulating intestinal immune responses by lipoteichoic acid-deficient Lactobacillus acidophilus

Aim: To investigate the mechanism(s) by which the intestinal commensal microbe Lactobacillus acidophilus can affect host immunity, we studied the role of a component of the cell wall, lipoteichoic acid, in colitis. Materials & methods: Colitis was induced by the intraperitoneal injection of pathogenic CD4 ⁺CD25 ^-CD45RB ^hi T cells into Rag1 ^-/- mice. The parental strain, NCK56, or the lipoteichoic acid-deficient strain, NCK2025, was then administered orally. Fluorescent microscopy was employed to examine resulting cell populations and their cytokine production in the colon. Results: NCK2025 enhanced IL-10 production by dendritic cells and macrophages. Increased numbers of regulatory dendritic cells coincided with the induction of activated FoxP3 ⁺ Tregs. Conclusion: These results suggest that the oral administration of the genetically modified strain NCK2025 may be an effective immunotherapeutic approach that reprograms the immune response in colonic inflammatory conditions.