Early supplementation of non-obese diabetic mice with oligosaccharides isolated from human milk reduces spontaneous autoimmune diabetes development later in life

It is well established that breast feeding beneficially affects immune development in the offspring. Human milk oligosaccharides (HMOS) are components of human milk that have been implicated to affect immune function development, either directly or through effects on the intestinal microbiota. To investigate whether HMOS have the potential to affect the development of autoimmune conditions later in life, HMOS supplementation in early life was tested in non-obese diabetic mice that spontaneously develop autoimmune (type I) diabetes. The total fraction of lactose reduced HMOS (consisting of fucosylated and/or sialylated neutral and acidic structures) were isolated from pooled human milk samples donated by healthy donors, and supplemented in AIN-93M rodent diets at a dose of 10g/kg. Non-obese diabetic NOD/ShiLtJ mice (Jackson) were fed from week 4-10 on supplemented or control AIN-93M diet. Diabetes incidence was measured by urine glucose test. Animals were followed up to a maximum of 30 weeks of age. Upon two consecutive positive urine tests, or at 30 weeks of age, animals were sacrificed. Insulitis was analyzed histologically, spleen lymphocyte populations were analyzed by flow cytometry Supplementation of the diet with HMOS between weeks 4-10 significantly reduced the incidence of spontaneous autoimmune diabetes later in life, up to the age of 30 weeks, as measured by urine glucose test (p=0.03). These findings were corroborated by pancreas histology and decreased T-cell activation marker expression in the spleen, although the ratio of Th1/Th2 cells remained unchanged. Surprisingly, there was a significant reduction in regulatory T-cells (CD4+CD25+FOXP3+) in the HMOS group as well. In a mouse model of spontaneous autoimmune diabetes, temporary dietary exposure to HMOS in early life reduced the incidence of disease later in life. The reduction in T-cell activation and pancreas inflammation markers corresponded with a reduced percentage of regulatory T-cells in the spleen, suggesting that these cells are induced in response to the severity of the disease process, rather than being the causal factor of the protective effect of HMOS. Overall, the results suggest that the immunological benefits of breast feeding may include changes in immune development by HMOS, leading to suppression of spontaneous autoimmune reactions later in life.