Fig. 7

The gut microbiota from patients with IDD increased the bacterial load in the pancreas, disrupted local immune tolerance and induced IDD in recipient mice. A The overall structure of the gut microbiota of the IDD patients, healthy human donors, and mouse recipients. Principal coordinate analysis (PCoA) was performed on the basis of Bray-Curtis distance at the amplicon sequence variant (ASV) level. The bacterial load in the pancreas of HFM_H and HFM_D mice as measured by B real-time qPCR and C FISH of 16S rRNA genes. HFM_H, n=16; HFM_D, n=13. D Flow cytometry evaluation of leukocyte subtypes in the pancreas of mice in the HFM_H and HFM_D groups. Data are presented as the frequency of gated cells (left to right: F4/80⁺ macrophages, CD3⁺ cells, CD8⁺ T cells, CD4⁺ T cells, and Foxp3⁺ CD4⁺ cells) among the CD45⁺ population of cells per mouse. HFM_H, n=4; HFM_D, n=4. E Histological sections of pancreatic tissue (scale bar = 0.1 mm) from HFM_H and HFM_D mice stained for insulin (green) and DNA (blue). The insulin-positive area in pancreatic tissue was calculated. HFM_H, n=10; HFM_D, n=10. F H&E-stained histological sections of pancreatic tissue (400x, scale bar = 0.05 mm) from HFM_D mice and HFM_H mice. The number of islets per mm2 of pancreatic tissue was counted. HFM_H, n=18; HFM_D, n=16. G H&E-stained histological sections of pancreatic tissue (200x, scale bar = 0.1 mm) from HFM_H and HFM_D mice. The histologic pancreatitis score was evaluated by edema, inflammation, and vacuolization. HFM_H, n=10; HFM_D, n=10. H The blood glucose level of HFM_H and HFM_D mice according to OGTT (the AUC is shown in the inset graph). HFM_H, n=4; HFM_D, n=4. HFM_H, antibiotic cocktail-treated mice inoculated with the fecal microbiota of healthy human donors; HFM_D, antibiotic cocktail-treated mice inoculated with the fecal microbiota of IDD patients. The data are shown as the mean ± SEM, and Student’s t-test (two-tailed) was used to analyze differences between groups. *P <0.05 and **P <0.01