by Dr Yeap Swan Sim
Systemic lupus erythematosus (SLE, or 'lupus') is a chronic inflammatory disease that can affect any organ system in the body. The term 'lupus' is Latin for 'wolf' and was used in the Middle Ages to describe the erosive skin rashes that were suggestive of a wolf's bite.
In the United States, a 1998 study estimated the prevalence of SLE to be 51/100,000. Over the last 40 years, between 1950 and 1992, in developed countries, the incidence of SLE has nearly tripled.
African-Americans, Hispanics and Orientals are affected more frequently than Caucasians, and have higher disease morbidity.
In a study from America, 65% patients had disease onset between the ages of 16 and 55, 20% present before the age of 16, and 15% present after the age of 55. 90% of SLE patients are female.
Locally, in Malaysia, the female:male ratio is 12:1 and, in 1990, was estimated to affect 43/100,000 population.
What Causes SLE?
SLE is an autoimmune disease. There is usually a genetic susceptibility to SLE, with many genes having been implicated. This, combined with other susceptibility factors such as (female) gender and the environment, leads to the development of the abnormal immune response.
Normally, our bodies produce antibodies when there are foreign materials present e.g. bacteria. These foreign materials (called antigens) cause the immune system to produce antibodies against them. The antibody binds to the antigen, forming an immune complex, which is eventually cleared from the blood stream.
In autoimmune diseases, there is an abnormal immune response directed against self-antigens, with failure to regulate the production of pathogenic autoantibodies.
In addition, there is also a defective ability of the immune system to clear the resulting abnormal immune complexes and abnormal cells, which leads to more antigen formation.
Hence, the cycle perpetuates. These autoantibodies and immune complexes can deposit in the various organ tissues causing inflammation which leads to tissue damage.
Apart from the genetic susceptibility, environmental factors are probably important in triggering or exacerbating the disease.
Up to 70% of SLE patients can experience disease flares after prolonged exposure to UV light. Exposure of the skin DNA to UV light can lead to changes that render the DNA more immunogenic (more likely to cause antibody production).
UV light can also cause more of the skin cells (keratinocytes) to undergo cell death (apoptosis) which can expose self-molecules to the immune system and make them immunogenic.
Another predisposing factor is infection with the Epstein-Barr virus (EBV). Patients with SLE have abnormally high frequencies of EBV-infected cells in their blood. This leads to increased activity of the B cells, the cells that produce antibodies, which then start producing autoantibodies.
It is likely that EBV can push a pre-disposed individual from non-autoimmunity to autoantibody production, starting the cycle that could lead to disease.
The fact that more women than men, especially those in their reproductive years, have SLE suggests a possible role of oestrogen in the pathogenesis of the disease. Women who take oestrogen-containing contraceptive pills are at slightly greater risk for SLE (relative risk 1.4 to 1.9).
Another study showed that SLE women on combined oestrogen and progesterone hormone replacement therapy had a greater rate of mild to moderate, but not severe, flare-ups of their disease.
One reason for this may be that the presence of oestradiol prolongs the life of autoreactive B and T cells, the cells that produce the autoantibodies, which would otherwise be deleted by the body.
These cells then persist in the peripheral tissues where they can increase autoantibody production if the correct activating signals are produced.
How Does SLE Present?
Symptoms of SLE are related to either the general effects of inflammation in the whole body or the organ specific effects. The whole body effects lead to non-specific symptoms such as fever, fatigue and weight loss.
However, there are numerous other causes for these symptoms, which need to be excluded by your physician.
The second type of symptoms is related to the specific organ involved. For example, inflammation in the joints will lead to arthritis (joint pain and swelling) or inflammation in the skin will lead to rashes.
The questions listed under 'Diagnosing SLE' will give you an idea of the numerous body organ systems that can be affected by SLE.
The diagnosis of SLE is based on a combination of symptoms, clinical signs on examination and blood tests. Thus, SLE cannot be diagnosed on symptoms alone or excluded on the basis of a blood test.
'Yes' answers to the questions below may suggest that someone has SLE, and may need further evaluation by a specialist:
● Have you ever had arthritis or rheumatism for more than 3 months?
● Do your fingers become pale, numb, or uncomfortable in the cold?
● Have you had any sores in your mouth for more than 2 weeks? (mouth ulcers)
● Have you been told that you have low blood counts (anemia, low WBC count, or low platelet count)?
● Have you ever had a prominent rash on your cheeks for more than 1 month?
● Does your skin break out after you have been in the sun (not sunburn)?
● Has it ever been painful to take a deep breath for more than a few days (pleurisy)?
● Have you ever been told that you have protein in your urine?
● Have you ever had rapid loss of lots of hair?
● Have you ever had a seizure, convulsion, or fit?
The Treatment and Prognosis of SLE
As with all the autoimmune diseases, there is no cure for SLE but we now have drugs that can control the disease by reducing symptoms, reversing inflammation and minimize organ impairment.
Treatment is divided into 2 types. Firstly, there are the drugs for relief of symptoms such as pain-killers. These drugs do not treat the underlying abnormal immune response.
Secondly, there are drugs that can suppress the immune system and these are used for the more serious/major organ involvement. These immunosuppressive drugs will limit damage to the vital organs as well as reduce the risk of future recurrence.
Treatment should be undertaken under the charge of a medical specialist experienced in the treatment of SLE patients, as there needs to be careful tailoring of the treatment according to the organ involved and its severity.
The prognosis depends on the degree of organ involvement in SLE - patients with only joint and skin disease generally have milder disease with good prognosis, compared to those with kidney or brain involvement, where the prognosis is much poorer.
Overall, the long term survival of SLE patients has improved over the past few decades from approximately 40% in 5 years in the 1950s to survival rates of over 90% in 10 years in studies beginning after 1980.
After appropriate therapy, up to 25% of patients can have a period of drug-free remission lasting for at least one year. However, many will relapse.
Thus, it is important that SLE patients continue to see their doctor regularly for follow-ups, even when they feel well.
SLE is a not uncommon autoimmune disease affecting many women. Early detection and treatment will minimise the long-term sequelae of the disease and its treatment and the complications of both.
More info on SYSTEMIC LUPUS ERYTHEMATOSUS here.