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

BACKGROUND

Inflammatory bowel disease (IBD) is caused by an abnormal immune response. Programmed cell death 1 (PD-1) is an immunostimulatory molecule, which interacts with PD ligand (PD-L1) playing a prime important role among autoimmune diseases. () can promote the differentiation of CD (cluster of differentiation) 4 T cells into regulatory T cells (Tregs). Tregs participate in the development of IBD and may be related to disease activity. amplify the expression level of PD-1, PD-L1 and Tregs' nuclear transcription factor forkhead box protein 3 (Foxp3). But the mechanism of on PD-1/PD-L1 signaling remains unclear.

AIM

To explore the mechanism of regulating the immune response in IBD.

METHODS

Forty-eight-week-old BALB/c mice were randomly divided into five groups: The control group, dextran sulphate sodium (DSS) model group, DSS + group, DSS + + anti-PD-L1 group, and DSS + anti-PD-L1 group. The control group mice were given drinking water freely, the other four groups were given drinking water containing 5% DSS freely. The control group, DSS model group, and DSS + anti-PD-L1 group were given normal saline (NS) 400 μL daily by gastric lavage, and the DSS + group and DSS + + anti-PD-L1 group were given NS and 1 × 10 colony-forming unit of daily by gastric lavage. The DSS + + anti-PD-L1 group and DSS + anti-PD-L1 group were given 200 μg of PD-L1 blocker intraperitoneally at days 0, 3, 5, and 7; the control group, DSS + anti-PD-L1 group, and DSS + group were given an intraperitoneal injection of an equal volume of phosphate buffered saline (PBS). Changes in PD-L1, PD-1, Foxp3, interleukin (IL)-10, and transforming growth factor β (TGF-β) 1 protein and gene expression were observed. Flow cytometry was used to observe changes in CD4, CD25, Foxp3 cell numbers in the blood and spleen.

RESULTS

Compared to the control group, the expression of PD-1, Foxp3, IL-10, and TGF-β1 was significantly decreased in the intestinal tract of the DSS mice ( < 0.05). Compared to the control group, the proportion of CD4, CD25, Foxp3 cells in spleen and blood of DSS group was visibly katabatic ( < 0.05). upgraded the express of PD-L1, PD-1, Foxp3, IL-10, and TGF-β1 ( < 0.05) and increased the proportion of CD4, CD25, Foxp3 cells both in spleen and blood ( < 0.05). After blocking PD-L1, the increase in Foxp3, IL-10, and TGF-β1 protein and gene by was inhibited ( < 0.05), and the proliferation of CD4, CD25, Foxp3 cells in the spleen and blood was also inhibited ( < 0.05). After blocking PD-L1, the messenger ribonucleic acid and protein expression of PD-1 were invariant.

CONCLUSION

It is potential that boost the proliferation of CD4, CD25, Foxp3 T cells in both spleen and blood, as well as the expression of Foxp3 in the intestinal tract by activating the PD-1/PD-L1 pathway.