Immunological Mechanism of Faecal Bacterial Transplantation in the Intervention of Ulcerative Colitis

Abstract

BackgroundUlcerative colitis is listed as one of the modern refractory diseases by the World Health Organization. At present, Western medicine still has many shortcomings in its treatment, and studies have shown that fecal bacterial transplantation (FMT) has a certain effect on it, but the mechanism is not clear.ObjectiveFMT was used to treat mouse ulcerative colitis model to verify the efficacy and possible mechanism of FMT.MethodsFrom December 2019 to April 2020, 60 mice were divided into normal control group (Control group) , ulcerative colitis model group (Model group) , ulcerative colitis model + fecal bacteria transplantation treatment group (Model+FMT group) and ulcerative colitis model + 5-aminosalicylic acid (5-ASA) treatment group (Model+5-ASA group) by random number table method, each of 15 mice. Control group did not make any intervention; Model group prepared mouse ulcerative colitis model; after successful modeling, the Model+FMT group was given 0.2 ml of fecal bacteria solution per enema; after successful modeling, the Model+5-ASA group was given 0.019 5 g/ml 5-ASA enema. The ultrastructural changes of intestinal tissue through transmission electron microscope, flow cytometric detection of blood helper T cell (Th) -17, Th-1, Th-2, Treg cell content changes, and enzyme-linked immunosorbent assay (ELISA) were observed to detect serum interferon γ (IFN-γ) , interleukin (IL) -2, IL-17, IL-4, IL-10, transforming growth factor β (TGF-β) level changes.ResultsIntestinal tissue transmission electron microscopy ultrastructure showed that the Model group was successfully modeled; the microvilli in the Model+FMT group and Model+5-ASA group were denser, with normal morphology, more goblet cells, slight swelling of mitochondria, and insignificant rough endoplasmic reticulum lesions. The Th17 cell content of the Model+FMT group was higher than that of the Control group and lower than that of the Model group; the Th17 cell content of the Model+5-ASA group was lower than that of Control group, Model group and Model+FMT group. The Th1 cell content of Model+FMT group and Model+5-ASA group were lower than those of Control group and Model group, respectively; Th2 cell content of Model+FMT group was lower than that of Control group and higher than that of Model group, and Th2 cell content of Model+5-ASA group was lower than that of Control group and higher than that of Model group and Model +FMT group. Treg cell content in Model+FMT group and Model+5-ASA group were lower than that of Control group and higher than that of Model group (P<0.05) . IFN-γ cell content in Model+5-ASA group was lower than that of Model group. IL-2 cell content in Model+FMT group and Model+5-ASA group was lower than that of Model group; the IL-17 cell content of Model+FMT group and Model+5-ASA group were lower than those of Control group and Model group, respectively. The IL-17 cell content of Model+5-ASA group was lower than that of Model+FMT group; the IL-4 cell content of Model+FMT group was lower than that of Control group and higher than that of Model group. The IL-4 cell content in the Model+5-ASA group was higher than that in the Model group; the IL-10 cell content in the Model+FMT group was higher than that in the Control group and the Model group, and the IL-10 cell content in the Model+5-ASA group was higher than that in the Model group; the content of TGF-β cells in the Model+FMT group and Model+5-ASA group were lower than those in the Control group and higher than those in the Model group (P<0.05) .ConclusionFMT can improve the symptoms of ulcerative colitis in mice. It is speculated that it may be achieved by adjusting the balance of Th1/Th2 cells and the ratio of Th17/Treg cells to achieve the purpose of treatment.

Keywords

• |colitis, ulcerative|fecal microbiota transplantation|mesalamine|th1 cells|th2 cells|th17 cells|t-lymphocytes, regulatory