Aug. 5, 2002 -- Environmental factors have long been thought to help trigger lupus in people who are genetically predisposed to get the disease. Now researchers have identified just such an environmental trigger in mice, and it may help them understand the causes of lupus in humans.
The findings provide some of the best direct evidence yet that environmental influences play a role in the onset and advancement of lupus, an autoimmune disorder that causes the body's immune system to attack healthy tissue, resulting in a wide range of symptoms including kidney disease, arthritis, fatigue, joint pain, and anemia.
In this study, reported by University of Florida researchers in the August issue of the journal Arthritis and Rheumatism, mice predisposed to develop the disease got sick and died much quicker when they were injected with a component of mineral oil known as pristane.
Although there is no evidence that pristane causes lupus in humans, it has been shown to induce inflammatory disease when absorbed through the respiratory or gastrointestinal tract. Researcher Westley H. Reeves, MD, says the latest findings may help unravel the mystery of why some genetically predisposed people get lupus while others do not.
"We are not saying that mineral oil causes lupus in humans," Reeves tells WebMD. "That would be highly speculative. But if we are able to identify the environmental components in humans that act the way pristane does in mice, we may be able to reduce the probability that someone who is prone to lupus will actually get it." Reeves is chief of rheumatology at the University of Florida College of Medicine.
In the study, mice genetically engineered to develop lupus were injected with either pristane or salt water. As anticipated, all of the predisposed mice developed lupus-specific antibodies, but the mice injected with pristane developed more antibodies more quickly. Disease symptoms were also dramatically accelerated in the pristane-injected mice - 75% died within six months of injection, compared to just 9% of mice injected with the saline solution.
The findings suggest that environmental factors play a bigger role in the development of lupus than has generally been believed, says researcher Hideo Yoshida. Isolating those environmental factors and either avoiding them or treating for them may turn out to be a relatively simple way to prevent or manage the autoimmune disorder.