Table of Contents
Definition of Lupus
Systemic lupus erythematosus as an autoimmune disease
Systemic lupus erythematosus is an autoimmune disease that is classified as a collagenosis, a disease that affects the connective tissue. Within the group of collagenoses, it is associated with the spectrum of rheumatic diseases.
Epidemiology of Lupus
Women of childbearing age constitute about 90% of the affected patients. The highest prevalence is observed in African-American and Afro-Caribbean women. The prevalence of SLE in the US ranges from 20 to 150 per 100,000 women.
Etiology of Lupus
Causes of the systemic lupus erythematosus
The exact etiology of lupus is unknown, but there are certain predisposing genetic factors (e.g., the surface molecules HLA-DR2 and HLA-DR3). Also, external factors like hormonal changes, stress, infections, increased light exposure, or drugs can “trigger” lupus.
Pathophysiology of Lupus
The development of systemic lupus erythematosus
The pathological mechanism of lupus is a precipitation of immune complexes at the basal membrane of the cell walls. This occurs in the connective tissue of the skin and also in blood vessels. The precipitates can lead to a vasculitis, which can be seen as a “lupus band” under the microscope with immunofluorescence staining.
These precipitating immune complexes consist of DNA, antibodies against this DNA, complement, and fibrin. They are caused by a misdirected immune response against components of the cell nucleus. These complexes are falsely identified as foreign by the immune system, and more antibodies are produced.
In summary, genetic and environmental factors contribute to increased production of nucleic acids; this, in turn, elicits an abnormal immune response from the body. The result is the formation of circulating immune complexes. These immune complexes precipitate in the tissues and cause inflammation and damage.
Clinical Picture of Lupus
Signs and symptoms of systemic lupus erythematosus
In most cases, systemic lupus erythematosus presents with nonspecific general symptoms, which can complicate the diagnosis. Fever, weakness, weight loss, and swelling of the lymph nodes are several examples.
Skin changes that give the disease its name manifest nearly as often. Lupus comes from the Latin name for wolf, and the rash often seen in these patients is thought to resemble the facial scars that remain after the healing of a wolf’s bite. The characteristic skin changes are a butterfly-like erythema on the cheeks and the bridge of the nose. Vibrant, scaling papules are found in discoid lupus, a form of cutaneous lupus erythematosus.
Polyarthritis and myositis are some of the more common manifestations of SLE.
Eventually, SLE can lead to neurological complications. In these cases, the peripheral nervous system is affected more often. Neurological involvement may become apparent due to decreased vigilance, depression, epilepsy, or stroke.
Renal changes in systemic lupus erythematosus: lupus nephritis
Lupus nephritis, which occurs in over half of the patients, is crucial to the prognosis of SLE. The complexes of DNA and anti-DNA antibodies lead to the clinical picture of a classic immune complex glomerulonephritis. This condition can express itself to varying degrees ranging from asymptomatic proteinuria to chronic renal failure.
It is divided into six different types by the World Health Organization (WHO) as well as the International Society of Nephrology and the Renal Pathology Society; each type is treated differently. The therapy consists of immunosuppression and adjustment for optimal blood pressure in most cases; treatment may differ for those with either minimal or extensive involvement of the kidneys.
Summary of the signs and symptoms of systemic lupus erythematosus
Systemic lupus erythematosus is characterized by the following signs and symptoms:
- Fever, weakness, weight loss
- Butterfly rash
- Polyarthritis, myositis
- Cardiopulmonary changes
- Lupus nephritis
- Neurological changes
Diagnosis of Lupus
Laboratory diagnostics for systemic lupus erythematosus
- The anti-dsDNA antibodies that are increased in 70% of the cases of lupus, and the anti-nuclear antibodies (ANA) that are nearly always increased, are characteristic. Yet, these antibodies can also be found in healthy individuals in low concentrations.
- Test results for other antibodies can also be positive: anti-Sm, anti-Ro, antiphospholipid antibodies (APA), anti-histone, antineuronal, antiribosomal, and others. The circulating antibodies often lead to a decrease in certain cell counts, such as thrombocytopenia and lymphocytopenia.
- An increase of ANAs is seen in 95% of the cases.
- An increase of anti-dsDNA antibodies is seen in 70% of the cases.
Diagnostic criteria for SLE from the American College of Rheumatology
At least 4 of the 11 criteria must be met to diagnose SLE:
Criteria of SLE
Therapy for Lupus
- No cure is available, and complete, sustained remissions are not common. Therefore, the aim is control of acute flares, suppression of symptoms to an acceptable level, and prevention of organ damage.
- Patients without major organ involvement can be managed conservatively with analgesics and antimalarials. Systemic glucocorticoids are the recommended treatment for any life-threatening or organ-threatening inflammatory manifestations of SLE.
- Cytotoxic or immunosuppressive agents, especially cyclophosphamide or mycophenolate, are added to glucocorticoids to treat serious SLE. For refractory serious SLE, various biologics are currently being studied. Also, studies of highly targeted interventions at various steps of immune regulation are in progress.
- The blood pressure must be optimally adjusted to prevent renal damage. Sufficient prophylaxis of osteoporosis should follow.
- Other preventive strategies include providing influenza and pneumococcal vaccines and suppressing recurrent urinary tract infections.
- Controlling other comorbidities, such as dyslipidemia, hyperglycemia, and obesity, is also recommended to improve SLE outcomes.
Prognosis of Lupus
Survival probability in systemic lupus erythematosus
The rate of survival is very good with optimal therapy. Lupus patients mostly die from cardiovascular complications.
Poor prognosis has been associated with high serum creatinine levels, hypertension, nephrotic syndrome, anemia, hypoalbuminemia, hypocomplementemia, antiphospholipid antibodies, male sex, ethnicity (African American, Hispanic with mestizo heritage), and low socioeconomic status.