Systemic lupus erythematosus
It is an autoimmune disease that causes from inflammation of the skin and joints to involvement of other organs, resulting in heterogeneous manifestations ranging from mild skin disease to multiorgan failure. The overall incidence ranges from 1.5-11 cases per 100,000 people per year due to differences in gender, ethnicity and environmental factors.
Currently, the presence of antibodies that recognize different cellular structures has been identified, but the specific cause that triggers the production of these autoantibodies is unknown. Apparently, affected individuals would have a hereditary predisposition and would develop the disease when they come into contact with environmental factors that may trigger it. Among these possible triggers would be:
- Viral infections by cytomegalovirus, Epstein-Barr, retrovirus or herpesvirus among others.
- Certain medications such as isoniazid, hydralazine, anticonvulsants, sulfasalazine, among others.
- Exposure to sunlight.
- Smoking and excessive alcohol consumption.
- Industrial pollutants or solvents, silica.
- Specific hormonal states such as puberty, pregnancy, or menopause.
In addition, different conditioning factors have been described that increase the risk of developing this condition:
- Gender: it is of the order of 4-12 times more frequent in females than males.
- Age: women of reproductive age from 15 to 44 years are at higher risk of presenting it, however, it can occur at any age, including childhood.
- Ethnicity: it is more common in individuals with specific ancestries, mainly African Americans, Latinos, Asians and Indo-Americans, and tends to worsen to a greater extent in these groups. </ul
Genetic factors play a key role in SLE, with heritability estimates ranging from 43% to 66% in all populations. Based on existing differences in prevalence, severity and disease onset based on ancestry, a trans-ethnic GWAS study in nearly 9000 cases and nearly 25000 controls has led to the identification of 28 risk loci involved in cytokine-mediated signaling and other immune system pathways, especially related to B and T lymphocytes.
The symptoms of lupus vary widely among affected individuals, as it will also depend on whether there is general and/or organ-specific involvement. They may be sudden or develop slowly, be mild or severe, temporary or permanent. In most cases it is a mild condition characterized by episodes or outbreaks after which the manifestations improve or even disappear completely for a period of time. The most frequent symptoms consist of:
- Fatigue and tiredness that does not disappear with rest.
- Fever and muscle pain.
- Joint pain accompanied by swelling and stiffness.
- Butterfly-shaped rash on the face covering the nose and cheeks known as malar erythema, or over the rest of the body.
- Sensitivity to sunlight leading to the appearance of skin lesions.
- Color change in the fingers and toes to violet blue, white or red caused by cold and stress (Raynaud's phenomenon).
- Oral sores and hair loss.
In addition, other organs may be affected in the most severe cases. The kidneys, triggering severe renal failure which is one of the main causes of death in these patients. The central nervous system, causing headaches, dizziness, behavioral changes, vision problems, memory loss, disorientation, difficulties in expressing thoughts and even strokes or seizures. Blood and vasculature, causing anemia, alterations in coagulation, or inflammation of the blood vessels. Lungs, favoring inflammation of the pleura making breathing difficult, even pneumonia or pulmonary bleeding. Heart, causing inflammation of the heart muscle, arteries, pericardium, and increasing the risk of cardiovascular disease and infarction.
There are no effective measures available to prevent the disease, although it is true that there are recommendations aimed at avoiding or reducing the appearance of new outbreaks, symptoms and possible complications: avoid prolonged exposure to the sun and therefore receive vitamin D supplements to avoid its deficiency, stop smoking and reduce alcohol consumption, do regular physical exercise, follow a balanced diet low in fat, salt, sugars and rich in fiber, avoid stress, and rest adequately by limiting work overload.
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Barber MRW et al. Global epidemiology of systemic lupus erythematosus. Nat Rev Rheumatol. 2021 Sep;17(9):515-532.
Choi MY et al.Preventing the development of SLE: identifying risk factors and proposing pathways for clinical care. Lupus. 2016 Jul;25(8):838-49.
Wang YF et al. Identification of 38 novel loci for systemic lupus erythematosus and genetic heterogeneity between ancestral groups. Nature Communications. 2021 Feb;12(1):772.