How and why lupus develops is not understood. Experts say the illness probably results from a complex mix of hormonal, genetic, and environmental factors.
The hormone estrogen likely plays some role, which may explain why more women than men have the disease. Lupus involvement may worsen before menstruation and during pregnancy.
Genetics may partly explain racial and ethnic differences in the incidence and severity of lupus. Blacks not only have a higher incidence of lupus, but they tend to develop it earlier and experience more severe disease.
To look for patterns, researchers are studying families in which one or more members have lupus. Lupus sometimes runs in families. About 5% of children develop lupus if a parent had the disease, according to the LFA. Research shows that if an identical twin has lupus, the other twin is more likely to have or develop the disease than a non-identical twin would be.
Petri says the environmental factors that may trigger lupus in genetically susceptible people include:
- ultraviolet light
- infections (such as Epstein-Barr virus)
- some drugs (such as antibiotics in the sulfa group (Bactrim, Gantrisin, Septra)
Some people experience drug-induced lupus caused by extensive use of medications. The symptoms are similar to SLE but usually go away when the medications are stopped. Drugs most commonly connected with drug-induced lupus are:
- hydralazine (for hypertension)
- procainamide (for irregular heart rhythms)
"It's believed that somehow the wrong immune system meets the wrong insult," says Joan Merrill, M.D, "Healthy people may inherit protective genes. It's as if you shuffle a deck of cards and lupus patients get the bum deal."
In 2003, NIAMS announced that scientists had discovered a genetic "signature" in some people with SLE who develop life-threatening complications, such as blood disorders, central nervous system damage, and kidney failure. 14 of the thousands of genes studied were linked to a subset of SLE patients with severe disease. The 14 genes are known as the interferon (IFN) expression signature. The genes are turned on by IFN, a family of proteins that have a role in regulating immune responses.
The Alliance for Lupus Research created the International SLE Genetics Consortium, a group of researchers who are working to find the genes that put people at risk of lupus. Consortium members will contribute genetic material from all over the world in the hope of finding more targeted treatment.
Scientists have also recently discovered that people with lupus may have a genetic defect in a cellular process called apoptosis. Normally, special white blood cells work to clear dying cells from the body. But if there is an abnormality in this process, the lingering cell debris may trigger the production of autoantibodies that attack healthy tissue.
Researchers continue to investigate abnormalities in T cells and B cells of mice and humans with lupus. These white blood cells control immune response.
Typical Lupus Treatment
Doctors take an individualized approach to treatment, depending on the nature and severity of the disease. Sometimes, a combination of drugs is needed. Through early treatment, doctors want to prevent flares, to treat them when they occur, and to lower the risk of organ damage. At the same time, a key goal is minimizing the side effects of medication.
Many people with lupus need only Tylenol (acetaminophen) or non-steroidal anti-inflammatory medications (NSAIDs), such as:
These medications control pain, fever, and inflammation. Risks of NSAIDs include stomach or bowel irritation. And when prescription NSAIDs are used chronically, there appears to be a possibility of an increased risk of heart attacks and strokes.
For serious problems such as kidney inflammation, corticosteroids may be needed. Examples are:
Corticosteroids are either applied to the skin or taken by pill or injection. Side effects include:
- weight gain
- puffy cheeks
- thinning hair
- mood swings
- trouble with concentration
Taken over long periods, corticosteroids also can raise blood pressure and cholesterol levels, as well as increase the risk of infections, diabetes, cataracts, and osteoporosis. "As many as 90% of SLE patients require prednisone, which has side effects even at low doses," says Petri. These drugs should not be stopped suddenly.
Another category of drugs that has worked in some lupus patients is called anti-malarials. They work to prevent flares, new kidney disease, and blood clots, Petri says. Experts say that Plaquenil (hydroxychloroquine) is the one most commonly used. The risk of side effects is low, but, in very rare cases, anti-malarials can cause changes in the retina. People who take anti-malarials are advised to get regular eye exams. More common side effects include:
- blurry vision