ESPE Abstracts

Research Objectives: Studies have shown that Akkermansiella mucinophila has a positive effect in various metabolic diseases, and can also prevent the onset of spontaneous type 1 diabetic NOD mice. However, its effect on type 1 diabetic mice is not clear. The purpose of this study is to analyze the effect of Akkermansiella mucinophila intervention on type 1 diabetic mice.

Research Methods: Thirty male C57BL / 6 mice aged 3-5 weeks were randomly divided into control group (NC group, n = 10), streptozotocin group (STZ group, n = 10) and Akkermansia mucini intervention group (AKK group, n = 10). The STZ group and the AKK group were intraperitoneally injected with STZ 50 mg / kg / d for 5 consecutive days to construct a type 1 diabetes model, and the NC group was injected with an equal volume of solvent. Body weight, random blood glucose and daily water intake were measured weekly. When random blood glucose > 16.7mmol / L, the model was successfully established. The mice in the AKK group were orally supplemented with 0.5 OD / 0.2ml / day of Akkermansia muciniphila for 3 consecutive days, and the other groups were supplemented with an equal volume of deoxygenated PBS. All mice were sacrificed after two days of observation. Body weight, random blood glucose and daily water intake were measured weekly during the experiment. Pathological HE staining of islets; the cytokine profiles (IFN-γ, TNF-α, IL-4 and TGF-β) in spleen and the expression of ZO-1 and Zonulin in colon were determined by ELISA. The expression of CD4, CD8 and FoxP3 in spleen was determined by flow cytometry. The expression of STAT1 and NF-κB p65 in colon was determined by immunohistochemistry. The feces were subjected to 16 SrRNA flora sequencing analysis.

Research Results: Compared with the NC group, the body weight of mice in the STZ group and the AKK group decreased, and the blood glucose and water intake increased (all P < 0.05). Compared with STZ group, there was no significant difference in body weight, blood glucose and water intake between AKK group and STZ group. The results of HE staining showed that compared with the NC group, the islet cells of STZ group and AKK group had different degrees of vacuolar degeneration and necrosis, and the number was reduced. Compared with the STZ group, there was no significant improvement in the islet of AKK group. The results of flow cytometry and ELISA showed that there was no significant difference in the proportion of spleen CD4 + / CD8 + cells, the expression of CD4 + FoxP3 + Treg cells, the levels of IFN-γ and IL-4 between the STZ group and the NC group. The expression of TNF-α, TGF-β and Zonulin increased, and the expression of ZO-1 decreased (all P < 0.05). Compared with STZ group, the expression of IFN-γ, TNF-α in spleen and Zonulin in colon of mice in AKK group decreased, the proportion of CD4 + / CD8 + cells in spleen, the expression of CD4 + FoxP3 + Treg cells, the expression of IL-4, TGF-β and ZO-1 in colon increased (all P < 0.05). Immunohistochemistry showed that compared with the NC group, the expression of NF-κB p65 in the colon of STZ group was significantly up-regulated (P < 0.05), and the expression of STAT1 was also up-regulated, but the difference was not statistically significant. Compared with the STZ group, the expression of NF-κB p65 in the colon of the AKK group was down-regulated, but the difference was not statistically significant, and the expression of STAT1 was significantly down-regulated (P < 0.05). The results of 16SrRNA sequencing showed that there was no significant difference in the abundance of actinobacteria in the feces of STZ group compared with NC group. Compared with STZ group, the abundance of actinobacteria in AKK group decreased significantly (P < 0.05).

Research Conclusion: The intervention of Akkermansiella mucilaginosa can induce multiple low-dose STZ-induced intestinal function enhancement and CD4 + Foxp3 + Treg cell-mediated immune tolerance in T1DM mice by down-regulating STAT and NF-κB signal transduction, which may be related to the decrease of the abundance of Actinobacteria.

Keywords: Type 1 diabetes; Streptozotocin; Akkermansiella mucinophila; Autoimmune; Intestinal barrier.