"We have to be cautious because although the mice are kept in a germ-free environment, it doesn't mean that they are not exposed to microbial products," Chervonsky says. He adds there is always concern that microbes may contaminate the feed, a possibility that could be overcome using a completely synthetic diet.
Mathis emphasized that one should not take away from these mouse studies "that mice or humans can 'catch' an autoimmune disease or arthritis," she says. She added that the better way to think about it is that individuals have varying degrees of genetic susceptibility, and when exposed to certain environmental factors may then go on to develop disease. "It's really an interaction between genetics and environment," Mathis says.