Bifidobacterium infantis regulates the programmed cell death 1 pathway and immune response in mice with inflammatory bowel disease

Figure 1 The effects of blocking programmed cell death ligand. A: Expression of programmed cell death 1 (PD-1) protein; B: Statistical chart showing the differences in PD-1 protein expression; C: Statistical map showing the differences in PD-1 mRNA expression; D: Western blot showing forkhead box protein 3 protein (Foxp3) expression; E: Statistical chart showing the differences in Foxp3 expression; F: Statistical map showing the differences in Foxp3 mRNA levels. Data are presented as mean ± SD, and comparisons between groups were analyzed by one-way analysis of variance. Statistical significance was set as P < 0.05. PD-1: Programmed cell death 1; PD-L1: Programmed cell death ligand; GAPDH: Glyceraldehyde-3-phosphate dehydrogenase; DSS: Dextran sulfate sodium; B. infantis: Bifidobacterium infantis; Foxp3: Forkhead box protein 3.

Figure 2 Effects of Bifidobacterium infantis and programmed cell death ligand inhibition on the proportion of CD4⁺, CD25⁺, and forkhead box protein 3⁺ cells in the blood. A: The strategy of CD4⁺, CD25⁺, and forkhead box protein (Foxp) 3⁺ cells; B-F: Flow cytometry results for the control group (B), the DSS model group (C), the DSS + B. infantis group (D), the DSS + B. infantis + anti-PD-L1 group (E), the DSS + anti-PD-L1 group (F); G: Statistical chart of the numbers of CD4⁺, CD25⁺, and Foxp3⁺ cells. Data are presented as mean ± SD, and the comparisons among each group were analyzed by one-way analysis of variance. Statistical significance was set as P < 0.05. PD-1: Programmed cell death 1; PD-L1: Programmed cell death ligand; DSS: Dextran sulfate sodium; B. infantis: Bifidobacterium infantis; Foxp3⁺: Forkhead box protein 3⁺; CD: Cluster of differentiation; SSC: Side scatter; FSC: Forward scatter; FL: Fluorescence; APC: Allophycocyanin; FITC: Fluorescein isothiocyanate; H: Height.

Figure 3 Effects of Bifidobacterium infantis and programmed cell death ligand inhibition on the proportion of splenic CD4⁺, CD25⁺, and forkhead box protein 3⁺ cells. A: The strategy of CD4⁺, CD25⁺, and forkhead box protein (Foxp) 3⁺ cells; B-F: Flow cytometry results for the the control group (B), the DSS model group (C), the DSS + B. infantis group (D), the DSS + B. infantis + anti-PD-L1 group (E); and the DSS + anti-PD-L1 group (F); G: Statistical chart of the numbers of CD4⁺, CD25⁺, and Foxp3⁺ cells. Data are presented as mean ± SD, and the comparisons among each group were analyzed by one-way analysis of variance. Statistical significance was set as P < 0.05. PD-1: Programmed cell death 1; PD-L1: Programmed cell death ligand; DSS: Dextran sulfate sodium; B. infantis: Bifidobacterium infantis; Foxp3⁺: Forkhead box protein 3⁺; CD: Cluster of differentiation; SSC: Side scatter; FSC: Forward scatter; FL: Fluorescence; APC: Allophycocyanin; FITC: Fluorescein isothiocyanate; H: Height.

Figure 4 Effects of programmed cell death ligand inhibition on the expression of interleukin-10 and transforming growth factor β 1. A: Western blot showing interleukin (IL)-10 and transforming growth factor β (TGF-β) 1 protein expression; B-E: Statistical maps of the differences in IL-10 protein expression (B), TGF-β1 protein expression (C), IL-10 mRNA expression (D), and TGF-β1 expression (E). Data are presented as mean ± SD, and the comparisons among each group were analyzed by one-way analysis of variance. Statistical significance was set as P < 0.05. PD-1: Programmed cell death 1; PD-L1: Programmed cell death ligand; DSS: Dextran sulfate sodium; B. infantis: Bifidobacterium infantis; IL: Interleukin; TGF-β: Transforming growth factor β; GAPDH: Glyceraldehyde-3-phosphate dehydrogenase; mRNA: Messenger ribonucleic acid.