Protective Role of Bifidobacterium longum ssp. infantis in Allergic Response
Background: Food Allergy (FA) is a critical and potentially life-threatening1 condition that affects ∼8% of US children.2 Despite growing financial3 and social burdens4 attributed to pediatric FA, mechanisms underlying the increased prevalence of FA remain poorly understood. Here, we expand on current knowledge regarding FA by examining the role of Bifidobacterium longum ssp. infantis (B. infantis) in immune response.
Objectives: Caco-2 cell monolayers were treated with B. infantis supernatant and Lipopolysaccharide (LPS) purified from E. coli 0111:B4 to 1) quantify the resulting intestinal permeability, 2) visualize the subsequent formation of tight junctions, and 3) analyze the innate immunologic activity of B. infantis.
Methods: Standard cell-line maintenance and subculturing protocols were used to grow Caco-2 cell monolayers. Transwell protocols were applied to treat cells with B. infantis supernatant and LPS. Trans Epithelial Electric Resistance (TEER) was used to measure the confluency of epithelial cells and determine intestinal permeability. Tight junctions were visualized using a Keyence microscope after immunofluorescence (IF) staining. RT-qPCR was run to analyze the expression of IL-8 cytokine.
Results: There was no significant difference between TEER values before and after Caco-2 cell monolayers were incubated for 4 hours with treatment conditions. Fluorescence microscopy showed that cells treated without LPS were generally larger than those treated with LPS. Monolayers treated with LPS demonstrated regions of disrupted cell proliferation. All treatment conditions significantly lowered LPS-induced IL-8 expression. B. infantis strains 3 and 5 had a comparable effect on decreasing IL-8 expression.
