Inflammatory tendencies and overproduction of IL-17 in the colon of young NOD mice are counteracted with diet change.
OBJECTIVE
Dietary factors influence diabetes development in the NOD mouse. Diet affects the composition of microbiota in the distal intestine, which may subsequently influence intestinal immune homeostasis. However, the specific effects of antidiabetogenic diets on gut immunity and the explicit associations between intestinal immune disruption and type 1 diabetes onset remain unclear.


METHODS
Gut microbiota of NOD mice fed a conventional diet or ProSobee formula were compared using gas chromatography. Colonic lamina propria immune cells were characterized in terms of activation markers, cytokine mRNA and Th17 and Foxp3(+) T-cell numbers, using real-time PCR and flow cytometry. Activation of diabetogenic CD4 T-cells by purified B-cells was assessed in both groups. Immune tolerance to autologous commensal bacteria was evaluated in vitro using thymidine-incorporation tests.


RESULTS
Young NOD mice showed a disturbed tolerance to autologous commensal bacteria. Increased numbers of activated CD4 T-cells and (CD11b(+)CD11c(+)) dendritic cells and elevated levels of Th17 cells and IL23 mRNA were moreover observed in colon lamina propria. These phenomena were abolished when mice were fed an antidiabetogenic diet. The antidiabetogenic diet also altered the expression levels of costimulatory molecules and the capacity of peritoneal B-cells to induce insulin-specific CD4 T-cell proliferation.


CONCLUSIONS
Young NOD mice show signs of subclinical colitis, but the symptoms are alleviated by a diet change to an antidiabetogenic diet. Disrupted immune tolerance in the distal intestine may influence peritoneal cell pools and B-cell-mediated activation of diabetogenic T-cells.
Alam
Catharina
C
Department of Medical Microbiology and Immunology, University of Turku, Turku, Finland.
Valkonen
Suvi
S
Palagani
Vindhya
V
Jalava
Jari
J
Eerola
Erkki
E
Hänninen
Arno
A
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002455:Cell Division; D003106:Colon / Q000473:pathology; D003108:Colonic Diseases / Q000209:etiology*; D016207:Cytokines / Q000235:genetics; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology*; D004032:Diet; D004847:Epithelial Cells / Q000473:pathology; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000235:genetics; D006965:Hyperplasia; D007249:Inflammation / Q000209:etiology* / Q000382:microbiology / Q000473:pathology; D020381:Interleukin-17 / Q000235:genetics*; D053759:Interleukin-23 / Q000235:genetics; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D016688:Mice, Inbred NOD; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology
D016207:Cytokines; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D020381:Interleukin-17; D053759:Interleukin-23; D012333:RNA, Messenger