Correlation between in vitro and in vivo immunomodulatory properties of lactic acid bacteria

Figure 1 Strain-specific patterns of IL-10 (A) and IL-12p70 (B) release for various bacterial strains and IL-10/IL-12 ratios (C) for 6 to 12 independent healthy donors. Bars represent the mean ± SE values in pg/mL for 6 to 12 independent healthy donors. Ranked box and whisker plots show the median values and first to third quartiles in boxes. Different letters indicate significant differences according to Mann-Whitney U test (P < 0.05).

Figure 2 IL-10 (A) and IL-12p70 (B) release in 4 distinct individual human PBMC donors and the expression level of IL-10 (C) and IL-12p70 (D). Individual values are represented in pg/mL while IL-10 and IL-12p70 levels are expressed as % of the highest inducer strain. ^aP < 0.05.

Figure 3 Protective effect of LAB strains against TNBS-induced colitis in BALB/c mice. Results are expressed as a % reduction of the mean macroscopic inflammation of mice treated with LAB as compared to the mean score of non-treated mice. Colitis index was assessed 48 h after TNBS administration. Each bar represents an independent experiment and corresponds to the ratio of control and LAB-treated mice groups (n = 10). ^aP < 0.05, ^bP < 0.01 vs TNBS-control group. The horizontal dashed lines indicate the 30% threshold of the uncertain statistical significance.

Figure 4 Hematoxylin/eosin staining of representative cross-sections of murine (BALB/c) distal colon (HE, x 20). A: Normal appearance of the colon from a negative control mice; B: Thickening of the colon wall accompanied with massive inflammatory infiltrate and muscular necrosis 2 d after TNBS-induction of colitis; C: Reduction of histological damage in L. salivarius Ls33-treated mice after TNBS administration; D: Lack of histological improvement of colitis in L. acidophilus NCFM-treated mice after TNBS administration.

Figure 5 Correlation between the average protection against experimental colitis and the mean IL-10/IL-12 ratios obtained in vitro, for all investigated strains. Spearman coefficient (r_s = 0.825, P < 0.001). The horizontal dashed lines indicate the 30% threshold of unprotectiveness.