Systemic lupus erythematosus
Systemic lupus erythematosus (SLE) is a rheumatic disease (Disease affecting the skin and connective tissue), considered the paradigm of autoimmune diseases.
Being an autoimmune disease The most characteristic feature is the presence of autoantibodies. That is, antibodies produced by the immune system of the individual's own "attack" the body's own cells.
In the case of lupus the final result of the action of these autoantibodies is the appearance of lesions in numerous organs and tissues. This is the why it is considered a "sistémcia disease" or "organ-specific".
It is a chronic disease with periods of remission and exacerbation of symptoms.
Systemic lupus erythematosus affects females (10: 1) and the black race (3: 1). Likewise, the risk is higher in relatives of sick people in the rest of the population.
Until 65% of cases the disease appears between 20 and 40 years.
The exact cause of the disease is unknown although it seems undeniable that the etiology is multifactorial.
A series of genetic, hormonal and environmental factors act on a genetically predisposed immune system, which ultimately would lead to the typical clinical manifestations of the disease.
What does it mean that the immune system is "genetically predisposed"?
The immune system of a person does not trigger an abnormal response because, if it is not necessary to have a predisposition to it.
This bias is due to the existence of susceptibility genes (Indirectly related genes with the disease who possesses make you more likely to develop the disease) and the absence of a series of protective genes.
The sum of these two factors has resulted in modifying the immune response against external and internal factors. When this response is too excessive or prolonged in time autoimmunity appears.
Systemic lupus erythematosus is a significant association with HLA - DR3 and HLA - DR2 and some genes encoding components of the complement system (Relative deficit C2 and C4).
HLA (human leukocyte antigens) are molecules present in all cells of the human organism, allowing the immune system to differentiate what is proper (to not attack) of the alien (to attack).
The complement system consists of a series of molecules which aims to remove any element not recognized as self.
The highest prevalence of systemic lupus erythematosus in women of childbearing age than men It has led to propose that there is a relationship between sex hormones and disease.
Therefore, own hormones (estrogen, progesterone, prolactin, testosterone ...) and exogenous (replacement therapy or birth control) seem to play an important role in the disease, although there is still no consensus about the importance of their influence.
Some environmental factors seem to trigger or intensify systemic lupus erythematosus.
- ultraviolet radiation, related photosensitivity own (exaggerated response to sunlight) box and the appearance of new shoots after exposure to the sun porlongada.
- Some virus infections, as the Epstein - Barr or some retroviruses.
- Drug-induced, where the clinical picture may be due to the action of certain drugs on the immune system, as with procainamide (antiarrhythmic) or hydralazine (antihypertensive).
The end result is the formation of immune complexes and deposition in different tissues. (It is called immunocomplex the result of antigen binding - antibody).
This deposit is one of the major mechanisms by which tissue injury occurs, with inflammation processes and apoptosis (cell death) result from abnormal immune response.
general symptoms (95%): fatigue, lack of appetite, weight loss, malaise. The joint pain is almost constant.
Demonstrations muscle - skeletal (95%): It is primarily muscle and joint pain. Are the most common symptoms.
skin lesions (80% of cases): more than half of lupus patients are photosensitive. The skin lesion may occur in three ways:
- Acute cutaneous lupus (50%): It appears one of the most characteristic lesions of the disease, facial erythema (Reddening of the skin of the face) shaped butterfly wings. It leaves no scars and their appearance is related to the sun and with new sprouts. It can sometimes be accompanied by a reddening rash that affects other areas (neck, shoulders, arms ...).
- Subacute cutaneous lupus (10%): bullous lesions appear symmetrical neck and shoulders with sun exposure. It leaves no scar, although they may be areas where skin pigmentation is altered.
- chronic cutaneous lupus (30%).
Almost half of patients have lesions in the oral mucosa and nasal passages as thrush.
The joint pain is almost constant.
hematologic abnormalities (80%): Most often, the onset of chronic anemia.
neurological manifestations: such as headache, depression, anxiety, seizures ...
pulmonary involvement and pleural: in half of patients. The most common is pleurisy and the most serious, massive alveolar hemorrhage (fortunately latter is very rare).
Cardiac manifestations: the most common is the pericarditis.
lupus nephritis. It affects half of patients and is a poor prognostic sign.
many other manifestations may occur depending on the affected organ, such as abortions, keratoconjunctivitis ...
Diagnosis of lupus
The alteration characteristic of lupus is the appearance of autoantibodies ANA (Antinuclear autoantibodies) present in 80 -90% of patients.
- The ANA are not specific to lupus, and they also appear in other autoimmune diseases.
- ANA may not be present if the patient has lupus. The ANA negative patients (10-20%) are more clinical and may have Raynaud's phenomenon.
- Within the ANA, the more specific for lupus are called Anti DNA DS.