EWT H MG

Several studies have shown that gut bacteria play a role in diabetes in murine models, and specific bacteria have been correlated with the onset of diabetes in a rat model. However, it is unknown whether intestinal microbes play a role in the development of autoimmunity in humans that often leads to type 1 diabetes (T1D), an autoimmune disorder in which insulin-secreting pancreatic islet cells are destroyed. High throughput, culture-independent approaches identified bacteria that correlate with the development of autoimmunity and T1D in young children who are at high genetic risk for this disorder. The level of bacterial diversity diminishes over time in these autoimmune subjects relative to that of age-matched, genotype-matched, non-autoimmune individuals. A single bacterial species, Bacteroides ovatus, comprised nearly 24% of the total increase in the phylum Bacteroidetes in cases compared to controls. Conversely, a single species of the phylum Firmicutes, represented by the human firmicute strain CO19, represented nearly 20% of the increase in that phylum in controls compared to cases over time. These data present four lines of evidence that support the notion that, as healthy infants approach the toddler stage, their microbiomes become healthier and more stable; whereas, children who are destined for autoimmunity develop a microbiome with higher levels of putative pathogenic members in an unstable bacterial community. Hence, this unhealthy, unstable microbiome in children who develop T1D-associated autoimmunity suggests that the autoimmune microbiome may be distinctly different from that found in healthy children. These data also suggest that bacterial-based markers for the early diagnosis of T1D. In addition, bacteria negatively correlated with the autoimmune state may prove useful as probiotics to prevent the development of autoimmunity in high-risk children.