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Systemic Lupus Erythematosus

Discussion in 'Immunology and Rheumatology' started by Aboyamen, Mar 30, 2011.

  1. Aboyamen

    Aboyamen Moderator

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    What is lupus? What are the types of lupus?

    Lupus is an autoimmune disease characterized by acute and chronic inflammation of various tissues of the body. Autoimmune diseases are illnesses that occur when the body's tissues are attacked by its own immune system. The immune system is a complex system within the body that is designed to fight infectious agents, such as bacteria and other foreign microbes. One of the ways that the immune system fights infections is by producing antibodies that bind to the microbes. People with lupus produce abnormal antibodies in their blood that target tissues within their own body rather than foreign infectious agents. Because the antibodies and accompanying cells of inflammation can affect tissues anywhere in the body, lupus has the potential to affect a variety of areas. Sometimes lupus can cause disease of the skin, heart, lungs, kidneys, joints, and/or nervous system. When only the skin is involved, the condition is called lupus dermatitis or cutaneous lupus erythematosus. A form of lupus dermatitis that can be isolated to the skin, without internal disease, is called discoid lupus. When internal organs are involved, the condition is referred to as systemic lupus erythematosus (SLE).

    Both discoid and systemic lupus are more common in women than men (about eight times more common). The disease can affect all ages but most commonly begins from 20-45 years of age. Statistics demonstrate that lupus is somewhat more frequent in African Americans and people of Chinese and Japanese descent.


    What causes lupus? Is lupus hereditary?

    The precise reason for the abnormal autoimmunity that causes lupus is not known. Inherited genes, viruses, ultraviolet light, and certain medications may all play some role.

    Genetic factors increase the tendency of developing autoimmune diseases, and autoimmune diseases such as lupus, rheumatoid arthritis, and autoimmune thyroid disorders are more common among relatives of people with lupus than the general population. Some scientists believe that the immune system in lupus is more easily stimulated by external factors like viruses or ultraviolet light. Sometimes, symptoms of lupus can be precipitated or aggravated by only a brief period of sun exposure.

    It also is known that some women with SLE can experience worsening of their symptoms prior to their menstrual periods. This phenomenon, together with the female predominance of SLE, suggests that female hormones play an important role in the expression of SLE. This hormonal relationship is an active area of ongoing study by scientists.

    More recently, research has demonstrated evidence that a key enzyme's failure to dispose of dying cells may contribute the development of SLE. The enzyme, DNase1, normally eliminates what is called "garbage DNA" and other cellular debris by chopping them into tiny fragments for easier disposal. Researchers turned off the DNase1 gene in mice. The mice appeared healthy at birth, but after six to eight months, the majority of mice without DNase1 showed signs of SLE. Thus, a genetic mutation in a gene that could disrupt the body's cellular waste disposal may be involved in the initiation of SLE
    What is drug-induced lupus?

    Dozens of medications have been reported to trigger SLE. However, more than 90% of cases of "drug-induced lupus" occurs as a side effect of one of the following six drugs: hydralazine (Apresoline is used for high blood pressure); quinidine (Quinidine Gluconate, Quinidine Sulfate) and procainamide (Pronestyl; Procan-SR; Procanbid) are used for abnormal heart rhythms; phenytoin (Dilantin) is used for epilepsy; isoniazid ([Nydrazid, Laniazid] used for tuberculosis); and d-penicillamine (used for rheumatoid arthritis). These drugs are known to stimulate the immune system and cause SLE. Fortunately, drug-induced SLE is infrequent (accounting for less than 5% of all people with SLE) and usually resolves when the medications are discontinued.


    What are lupus symptoms and signs?

    People with SLE can develop different combinations of symptoms and organ involvement. Common complaints and symptoms include fatigue, low-grade fever, loss of appetite, muscle aches, arthritis, ulcers of the mouth and nose, facial rash ("butterfly rash"), unusual sensitivity to sunlight (photosensitivity), inflammation of the lining that surrounds the lungs (pleuritis) and the heart (pericarditis), and poor circulation to the fingers and toes with cold exposure (Raynaud's phenomenon). Complications of organ involvement can lead to further symptoms that depend on the organ affected and severity of the disease.

    Skin manifestations are frequent in lupus and can sometimes lead to scarring. In discoid lupus, only the skin is typically involved. The skin rash in discoid lupus often is found on the face and scalp. It usually is red and may have raised borders. Discoid lupus rashes are usually painless and do not itch, but scarring can cause permanent hair loss (alopecia). Over time, 5%-10% of those with discoid lupus may develop SLE.

    Over half of the people with SLE develop a characteristic red, flat facial rash over the bridge of their nose. Because of its shape, it is frequently referred to as the "butterfly rash" of SLE. The rash is painless and does not itch. The facial rash, along with inflammation in other organs, can be precipitated or worsened by exposure to sunlight, a condition called photosensitivity. This photosensitivity can be accompanied by worsening of inflammation throughout the body, called a "flare" of the disease.


    Picture of a butterfly rash on the face, a characteristic sign of systemic lupus erythematosus (SLE).Typically, with treatment, this rash can heal without permanent scarring.

    Most people with SLE will develop arthritis during the course of their illness. Arthritis in SLE commonly involves swelling, pain, stiffness, and even deformity of the small joints of the hands, wrists, and feet. Sometimes, the arthritis of SLE can mimic that of rheumatoid arthritis (another autoimmune disease).

    More serious organ involvement with inflammation occurs in the brain, liver, and kidneys. White blood cells and blood-clotting factors also can be characteristically decreased in SLE, known as leukopenia (leucopenia) and thrombocytopenia, respectively. Leukopenia can increase the risk of infection, and thrombocytopenia can increase the risk of bleeding.

    Inflammation of muscles (myositis) can cause muscle pain and weakness. This can lead to elevations of muscle enzyme levels in the blood.

    Inflammation of blood vessels (vasculitis) that supply oxygen to tissues can cause isolated injury to a nerve, the skin, or an internal organ. The blood vessels are composed of arteries that pass oxygen-rich blood to the tissues of the body and veins that return oxygen-depleted blood from the tissues to the lungs. Vasculitis is characterized by inflammation with damage to the walls of various blood vessels. The damage blocks the circulation of blood through the vessels and can cause injury to the tissues that are supplied with oxygen by these vessels.

    Inflammation of the lining of the lungs (pleuritis) and of the heart (pericarditis) can cause sharp chest pain. The chest pain is aggravated by coughing, deep breathing, and certain changes in body position. The heart muscle itself rarely can become inflamed (carditis). It has also been shown that young women with SLE have a significantly increased risk of heart attacks due to coronary artery disease.

    Kidney inflammation in SLE can cause leakage of protein into the urine, fluid retention, high blood pressure, and even kidney failure. This can lead to further fatigue and swelling of the legs and feet. With kidney failure, machines are needed to cleanse the blood of accumulated waste products in a process called dialysis.

    Involvement of the brain can cause personality changes, thought disorders (psychosis), seizures, and even coma. Damage to nerves can cause numbness, tingling, and weakness of the involved body parts or extremities. Brain involvement is referred to as lupus cerebritis.

    Many people with SLE experience hair loss (alopecia). Often, this occurs simultaneously with an increase in the activity of their disease. The hair loss can be patchy or diffuse and appear to be more like hair thinning.

    Some people with SLE have Raynaud's phenomenon. In this condition, the blood supply to the fingers and/or toes becomes compromised upon exposure to cold, causing blanching, whitish and/or bluish discoloration, and pain and numbness in the exposed fingers and toes.

    Other conditions that can accompany lupus include fibromyalgia, coronary heart disease, nonbacterial valvular heart disease, pancreatitis, esophagus disease with difficulty swallowing (dysphagia), liver disease (lupoid hepatitis), and infections.
    How is lupus diagnosed?

    Since individuals with SLE can have a wide variety of symptoms and different combinations of organ involvement, no single test establishes the diagnosis of systemic lupus. To help doctors improve the accuracy of the diagnosis of SLE, 11 criteria were established by the American Rheumatism Association. These 11 criteria are closely related to the symptoms discussed above. Some people suspected of having SLE may never develop enough criteria for a definite diagnosis. Other people accumulate enough criteria only after months or years of observation. When a person has four or more of these criteria, the diagnosis of SLE is strongly suggested. Nevertheless, the diagnosis of SLE may be made in some settings in people with only a few of these classical criteria, and treatment may sometimes be instituted at this stage. Of these people with minimal criteria, some may later develop other criteria, but many never do.

    The 11 criteria used for diagnosing systemic lupus erythematosus are
     

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