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Systemic lupus erythematosus (SLE) - causes, symptoms, diagnosis & pathology
Osmosis from Elsevier
Overview
Systemic lupus erythematosus (SLE), or lupus, is a chronic autoimmune disease where the immune system mistakenly attacks the body's own tissues. It can affect multiple organs, including the skin, joints, kidneys, heart, lungs, and brain. The exact cause is unknown but involves a combination of genetic predisposition and environmental triggers like UV radiation, infections, or certain medications. When cells are damaged, they release nuclear antigens, which trigger an immune response. In susceptible individuals, the body produces antinuclear antibodies (ANAs) that form immune complexes, leading to inflammation and tissue damage, often presenting as a Type II or Type III hypersensitivity reaction. Diagnosis is challenging due to the wide range of symptoms and requires meeting at least four out of eleven specific criteria. Treatment focuses on managing symptoms, preventing flares, and reducing inflammation using medications like corticosteroids and immunosuppressants.
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Chapters
- •Lupus is an autoimmune disease affecting multiple organs (systemic).
- •The name 'erythematosus' refers to skin redness, and 'lupus' means wolf, possibly referencing wolf-bite-like skin lesions.
- •In lupus, the immune system attacks the body's own healthy tissues.
- •It's a complex disease resulting from genetic and environmental factors.
- •Environmental triggers (e.g., UV radiation) cause cell damage and apoptosis, releasing nuclear antigens.
- •Genetic susceptibility affects immune cell function and clearance of apoptotic bodies.
- •Immune cells recognize nuclear antigens as foreign, leading to the production of antinuclear antibodies (ANAs).
- •ANAs bind to antigens, forming immune complexes that deposit in various tissues.
- •These deposits trigger inflammation and tissue damage, classified as a Type III hypersensitivity reaction.
- •Besides UV radiation, other triggers include cigarette smoking, viruses, bacteria, and certain medications.
- •Sex hormones, particularly estrogen, may play a role, contributing to higher prevalence in women.
- •Lupus is significantly more common in women of reproductive age compared to men, children, or older adults.
- •Some patients develop antibodies targeting blood cells (red blood cells, white blood cells, platelets), marking them for destruction.
- •This can lead to anemia, thrombocytopenia, and leukopenia, considered a Type II hypersensitivity reaction.
- •The exact reason for these specific autoantibodies is not fully understood.
- •Diagnosis is challenging due to varied symptoms and affected populations.
- •A diagnosis requires meeting at least 4 out of 11 specific criteria.
- •Criteria include skin manifestations (Malar rash, discoid rash, photosensitivity), mucosal ulcers, serositis (pleuritis, pericarditis), arthritis, renal disorders, neurologic disorders, hematologic disorders, and specific antibody levels.
- •Skin: Malar (butterfly) rash, discoid rash, photosensitivity.
- •Mucosal ulcers: Sores in the mouth or nose.
- •Serositis: Inflammation of the linings of the lungs (pleuritis) or heart (pericarditis).
- •Renal: Kidney inflammation (glomerulonephritis).
- •Neurologic: Seizures, psychosis.
- •Hematologic: Anemia, low platelets, low white blood cells.
- •Antibody markers: Antinuclear antibody (ANA), anti-Smith (anti-Sm), anti-double-stranded DNA (anti-dsDNA), antiphospholipid antibodies.
- •Antiphospholipid antibodies can lead to antiphospholipid syndrome, causing a hypercoagulable state and increased risk of blood clots.
- •Lupus is characterized by periods of flares and remissions.
- •Treatment aims to prevent flares and manage severity.
- •Management strategies include sun avoidance, corticosteroids to reduce inflammation, and immunosuppressive drugs for severe cases.
Key Takeaways
- 1Lupus is an autoimmune disease where the body attacks its own tissues, affecting multiple organs.
- 2It arises from a complex interplay of genetic susceptibility and environmental triggers.
- 3UV radiation is a significant trigger, leading to cell damage and the release of nuclear antigens.
- 4Antinuclear antibodies (ANAs) are a hallmark of lupus, forming immune complexes that cause inflammation.
- 5Diagnosis is based on meeting specific clinical and laboratory criteria, as symptoms are highly variable.
- 6Common symptoms include rashes, joint pain, fatigue, and potential organ damage (kidneys, heart, brain).
- 7Treatment focuses on managing inflammation and preventing disease flares using corticosteroids and immunosuppressants.
- 8Some patients develop antiphospholipid syndrome, increasing the risk of blood clots.