A recently formed clinical research group will soon begin studying how the complex interplay between genetics and the environment may influence the development of autoimmune disorders. Working out of the NIH's Warren Grant Magnuson Clinical Center in Bethesda, Maryland, the Environmental Autoimmunity Group first will investigate myositis, a little-known disorder that causes muscle inflammation and weakness throughout the human body and can affect breathing, digestion, and function of the heart muscle. Down the road, the team will broaden its focus to include other autoimmune disorders with suspected environmental triggers, including rheumatoid arthritis, lupus, type 1 diabetes mellitus, multiple sclerosis, scleroderma (a thickening of the skin), and autoimmune thyroid disease.
"Members of the group will work in collaboration with their colleagues at the NIEHS campus in North Carolina and those in other institutes at the Clinical Center at NIH," says Perry Blackshear, NIEHS director of clinical research, who will work with the group. Frederick W. Miller, a specialist in immunology, internal medicine, and rheumatology, will lead the group in close association with senior clinical investigator Lisa G. Rider, who specializes in immunology, pediatrics, and pediatric rheumatology. Biologist Terrance P. O'Hanlon and postdoctoral researcher Ejaz A. Shamim will join them.
According to Miller, scientists have long suspected that certain genetic and environmental risk factors can work together to lead to disease. Myositis--a chronic, incurable, potentially fatal disease that afflicts at least 30,000 children and adults in the United States--may be triggered by infections or exposure to certain drugs or sunlight in people who are genetically predisposed. The group's initial goal will be to understand the disorder's possible genetic and environmental risk factors, which they plan to accomplish through several stages of studies.
"Some studies will have to be hypothesis-generating investigations," explains Miller. After that will come cohort-control studies to compare significant differences between normal individuals and patients, followed by further studies to confirm those results. "To better understand genetic risk factors, we're also considering a number of case-control studies using a targeted gene approach," Miller says. He adds, "In order for us to know how to treat the disease, we have to know how to measure the disease." This will require validation studies of disease assessment tools. "This is necessary before we can do a treatment study," says Miller.
Myositis, like many autoimmune disorders, is often underdiagnosed for two chief reasons. First, patients exhibit nonspecific symptoms common to many diseases and disorders (such as muscle or joint pain and fatigue), or there is no clinical manifestation of the illness until long into the disease phase. Second, the disorders themselves are rare, and physicians don't diagnose disorders they know little or nothing about. Armed with more knowledge of the disease, physicians will eventually stand better equipped to diagnose and treat it. But because myositis is one of the rarest autoimmune disorders, Miller says, one initial challenge will be finding enough patients--100 or so for each study. For that reason, the research group will collaborate with doctors in other locations.
The research team will also explore the possibility that certain autoimmune disorders may actually be collections of a number of so-called elemental disorders, each with its own pathogenesis and trigger. "This may be a major confounder of current studies," Miller explains. There is increasing evidence, he says, that myositis, rheumatoid arthritis, lupus, and scleroderma as they are defined today are actually aggregate conditions composed of different elemental disorders.
The new team is unique in that it will study both adults and children. Rider says the team's focus on the environment marks a significant departure from much of past research on childhood rheumatic diseases, which has focused more on genetics. Among other things, the team will study the roles that infectious agents and sunlight play in the development of a form of myositis called dermatomyositis. "We'll also be looking at a phenomenon known as microchimerism, which is the result of migration of cells between mothers and fetuses," Rider says. In microchimerism, a small number of cells circulating inside an individual's body actually come from another individual's body. The most common form of microchimerism occurs during pregnancy, when cells from the fetus's and mother's bodies can interchange. Microchimerism is suspected to play a role in both myositis and scleroderma. "We suspect that [microchimerism] has a role in juvenile dermatomyositis and now need to understand whether it has a role in pathogenesis," Rider says.
Rider suspects a number of environmental agents, including silica, mercury, estrogenic compounds, pesticides, and others still unidentified may influence disease. More than likely, multiple environmental triggers combine to influence a single autoimmune disorder. "As these diseases are polygenetic, they are also going to be polyenvironmental," she predicts.
COPYRIGHT 2001 National Institute of Environmental Health Sciences
COPYRIGHT 2004 Gale Group
Contact
Home
A
Jackson-Weiss syndrome