Bacteria get a bad name. Although most people exercise their Lysol as a sword against these organisms, in fact, many types of bacteria help us survive. Now, research has revealed that some microbes could also play a key role in the prevention of diabetes.
The human body runs on glucose and the hormone insulin prevents excessive outbreak. Every year about 15,000 people in the US are diagnosed with type 1 diabetes, which strikes when the immune system attacks cells in the pancreas that make insulin. Researchers have spent years trying to understand what triggers that attack the body's own cells.
Some studies have shown that mice exposed to different microbes develop type 1 diabetes at variable rates, suggesting that some bacteria can help modulate early stages of the disease. But specific information on how it works, and that bacteria were important, remained elusive.
Chervonsky immunologist Alexander of the University of Chicago in Illinois and colleagues evaluated how the microbial environment impacts of diabetes in mice. In some animals genetically predisposed to type 1 diabetes, the researchers hit a gene that protects against bacterial infections. The researchers then exposed five mouse prone to diabetes and five standard mouse germ vulnerable to a typical environment with lots of microbes. All normal mice and four of five mice prone germ developed diabetes, it seemed that the susceptibility to infection made no difference. But when the researchers studied the T cells, a marker of immune system activity in different tissues, they saw much less activity of T cells - something that is also a sign of incipient diabetes - in the ganglia pancreatic lymph from the general free mice, they reported in September 21 Nature .
Which microbes were behind the decreased T cell activity? The researchers keyed to a cocktail of bacteria known to live in the pancreatic lymph nodes normally. They placed mice susceptible to diabetes in an environment free of microorganisms and exposed to other bacteria. All mice in the germ-free environment developed diabetes; none of the mice exposed to the bacteria showed signs of the disease.
The Chervonsky group is examining whether the mice with type 1 diabetes living in otherwise normal lack these key microbes. "If we find the bacterial strain that is protective in mice, that should be enough to try convincing in humans," he said. But he noted that researchers need to understand exactly how these bacteria called off the attack of the immune system to produce treatments for patients with type 1 diabetes
developmental biologist Margaret McFall-Ngai of the University of Wisconsin, Madison, said the work reinforces the idea that microbes within our body can profoundly affect the way our bodies. And although David Relman immunologist at Stanford University in Palo Alto, California, warns against attributing too much importance to the role of microbes in human diabetes, it think the results are worth noting. "If nothing else, forcing us to another variable on the table that is not part of the mixture"
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