Systemic Lupus Erythematosus Overview

Study Notes

SLE is an autoimmune disease where organs and cells are damaged by autoantibodies and immune complexes binding to tissues.
Ninety percent of SLE cases occur in women of childbearing age.
SLE is 5.5 to 6.5 times more common in women than men.

Genetics play a significant role in SLE, contributing to 44% of heritability. Genetic variants, DNA breaks, and mutations are involved.
Environmental factors include exposure to UV light, smoking, silica, Epstein-Barr Virus (EBV) infection, hormones, obesity, less than 7 hours of sleep, Post-Traumatic Stress Disorder (PTSD), and specific medications like procainamide, hydralazine, isoniazid (INH), minocycline, and TNF inhibitors.

Genetic and environmental factors trigger abnormal immune responses.
Autoantibodies form complexes that deposit in organs.
Inflammatory pathways are activated, leading to organ damage.
Examples of affected organ systems include atherosclerosis, nephritis, arthritis, serositis, central nervous system (CNS) cerebritis, carditis, and leukopenia.

The 2012 Systemic Lupus International Collaborating Clinics (SLICC) criteria and the 2019 EULAR/ACR criteria are used to diagnose SLE.

Skin: Acute/subacute cutaneous lupus erythematosus (e.g., photosensitivity, malar rash, maculopapular lesions, bullous lesions); Chronic cutaneous lupus erythematosus (e.g., discoid lupus, panniculitis, lichen planus-like lesions, hypertrophic verrucous lesions, chilblains); oral/nasal ulcers, nonscarring alopecia, synovitis (≥ 2 joints), and serositis (pleurisy or pericarditis).
Renal: Proteinuria (≥0.5 g/24 hours), red blood cell casts, and renal biopsy findings.
Neurological: Seizures, psychosis, mononeuritis multiplex, peripheral or cranial neuropathies, acute confusional states.
Hematologic: Hemolytic anemia, leukopenia (< 4000/μL) or lymphopenia (< 1000/μL), and thrombocytopenia (< 100,000/μL).
Immunologic: Positive antinuclear antibody (ANA) test (above a reference range), positive anti-double-stranded DNA (anti-dsDNA), anti-Smith (anti-Sm) antibodies, antiphospholipid antibodies (e.g., lupus anticoagulant, false-positive rapid plasma reagin, anticardiolipin, anti-β2-glycoprotein 1), and low serum complement levels.

There is no cure for SLE, but complete and sustained remissions are rare.
The Systemic Lupus Erythematosus Disease Activity Score (SLEDAI)-2K is used to monitor disease activity.
Treatment focuses on managing symptoms and preventing organ damage.
Adjunctive therapies such as sun protection, vaccinations, exercise, avoiding smoking, and maintaining a normal weight, blood pressure, and lipids are also critical. Medications like corticosteroids (GCs), hydroxychloroquine (HCQ), methotrexate (MTX), azathioprine (AZA), and biologics are used depending on disease severity and organ involvement. These medications may also need to be closely monitored for adverse effects, such as blood disorders, infection, liver and kidney problems.