FIGURE 4.

Preventive supplementation with B. longum 5^1A increases the production of short-chain fatty acids (SCFAs) and the number of lung Treg cells of re-challenged OVx allergic mice. (A) Sterile bacterial culture medium and B. longum in culture medium. Fecal SCFA concentrations from the mice depicted in (B). (C) An oral probiotic (B. longum 5^1A) was administered by gavage daily for 15 days before the first OVA sensitization of mice and continued until 24 h before the mouse ovaries were removed. After the last re-challenge, cells from the BALF were subjected to flow cytometry and stained for CD4-APC, CD25-PE, and FoxP3-FITC. The dot plot demonstrates the gate strategy of Treg (Isotype control, Fluorescence Minus One Control-FMO, OVA-OVx, and OVA-OVx-probiotic) and the percentage of positive Treg cells. The graph is representative of two independent experiments. All results are representative of data generated in two different experiments and are expressed as the mean ± SEM [n = 3 for all groups in (A), n = 4 in (B,C)]. Statistical significance was determined by a one-way ANOVA. ^∗P < 0.05, ^∗∗∗P < 0.001.