Summary of "Systemic Lupus Erythematosus (SLE) - signs and symptoms, pathophysiology, investigations, treatment"

Summary of Video: Systemic Lupus Erythematosus (SLE)

Signs and Symptoms, Pathophysiology, Investigations, Treatment

Main Ideas and Concepts

Definition and Overview

Systemic Lupus Erythematosus (SLE) is a chronic, systemic autoimmune disease characterized by autoantibodies and immune complexes targeting nearly every organ. It predominantly affects women in their reproductive years (15-40 years), with a female-to-male ratio of up to 20:1.

Pathophysiology

SLE arises from an interplay of genetic susceptibility, epigenetic changes, hormonal influences (notably estrogen), and environmental triggers.
Environmental triggers include UV light, infections (e.g., Epstein-Barr virus), smoking, and certain drugs, which cause oxidative stress and cellular damage.
Damaged cells that cannot repair undergo apoptosis, exposing internal nuclear and cytoplasmic proteins.
Inefficient clearance of apoptotic cells (often due to complement protein deficiencies like C1, C2, C3, C4) leads to exposure of nuclear antigens to the immune system.
Antigen-presenting cells (APCs) such as immature macrophages and dendritic cells pick up these self-antigens (nuclear proteins like dsDNA, histones, SM, RNP, Ro; cytoplasmic and membrane antigens like cardiolipin).
APCs present these antigens to naive T-helper cells in lymph nodes, promoting differentiation mainly into T-helper 2 (Th2) cells.
Th2 cells stimulate B cell activation and proliferation, resulting in plasma cells that produce autoantibodies (AO antibodies) against self-antigens.
Autoantibodies form immune complexes that deposit in tissues, activate complement, and induce inflammation via cytokine release and immune cell activation.
This leads to organ inflammation, damage, and a vicious cycle of further cell injury.
Immunologic memory causes disease flare-ups upon re-exposure to antigens, triggered by factors such as sun exposure, infections, stress, surgery, and pregnancy.

Immune Response Details

Th1 cells (cell-mediated immunity) play a minor role in SLE.
Cytokines like IL-4 promote Th2 and humoral responses; IL-6 and IL-10 stimulate B cell activation.
Long-lived plasma cells in bone marrow maintain autoantibody production during flares.

Signs and Symptoms

Constitutional: fatigue, myalgia, weight loss, fever.
Skin: UV-sensitive butterfly rash on face (nasal bridge and malar bones), discoid rash, photosensitivity.
Neurological: cognitive impairment, headaches, seizures, delirium, psychosis, peripheral neuropathy.
Pulmonary: interstitial fibrosis, vasculitis, pleuritis, effusions.
Cardiovascular: pericardial disease (often asymptomatic), myocarditis, valvular heart disease, hypertension (often secondary to renal involvement).
Renal: lupus nephritis (immune complex deposition in glomeruli), leading to possible renal failure.
Gastrointestinal: nonspecific symptoms, hepatomegaly, ulcers (often medication-related).
Hematological: anemia, leukopenia, possibly drug-induced cytopenias.
Musculoskeletal: arthralgia, symmetrical polyarthritis, morning stiffness, Raynaud’s phenomenon.
Bone: osteopenia and osteoporosis due to multiple factors (low vitamin D, steroid use, renal disease, hormonal changes).
Other complications: antiphospholipid syndrome (in ~1/3 of patients), increased risk of non-Hodgkin lymphoma.

Investigations

Blood tests: full blood count, electrolytes, urea, creatinine, liver function tests (LFTs), inflammatory markers (CRP, ESR).
Urine tests: urinalysis, microscopy, albumin/creatinine ratio to assess kidney involvement.
Serological markers:
- Antinuclear antibody (ANA) – screening test for SLE and connective tissue diseases.
- Specific autoantibodies: anti-dsDNA, anti-histone, anti-Sm, anti-Ro, anti-RNP, anti-cardiolipin, anti-phospholipid antibodies.
- Complement levels (C3, C4) often decreased during flares.
- Rheumatoid factor (RF) may be tested to rule out other diseases.
Important to consider drug-induced lupus in patients with new drug exposure and positive ANA.

Management

General measures:
- Avoid UV light exposure.
- Vitamin D and calcium supplementation.
- Lifestyle modifications: smoking cessation, alcohol avoidance, weight management, cholesterol control.
Pharmacological treatment:
- Calcineurin inhibitors (e.g., tacrolimus) inhibit IL-2 production and T cell activation.
- Mycophenolate mofetil and azathioprine suppress lymphocyte proliferation (both B and T cells).
- Belimumab (monoclonal antibody) targets B cell activating factor (BAFF), reducing B cell survival and antibody production.
- Glucocorticoids are mainstay for controlling inflammation and flares.
- NSAIDs for musculoskeletal pain.
- Antihypertensives to control blood pressure and reduce renal damage.
Monitoring and managing complications such as osteoporosis and antiphospholipid syndrome are critical.

Pathophysiology Process

Genetic susceptibility combined with environmental triggers leads to oxidative stress and cell damage.
Damaged cells undergo apoptosis, exposing nuclear and cytoplasmic antigens.
Inefficient clearance of apoptotic cells (due to complement deficiency) results in antigen exposure.
APCs pick up antigens and present them to naive T-helper cells, promoting Th2 differentiation.
Th2 cells activate B cells, which differentiate into plasma cells producing autoantibodies.
Autoantibodies form immune complexes that deposit in tissues and activate complement.
Cytokine release causes inflammation and organ damage.
Immunologic memory leads to flare-ups upon re-exposure to antigens.

Diagnostic Workup

Blood tests: CBC, renal and liver function, inflammatory markers.
Urinalysis and urine protein quantification.
Serological tests: ANA, anti-dsDNA, anti-Sm, anti-Ro, anti-RNP, complement levels.
Review drug history to assess for drug-induced lupus.

Management Approach

Educate patients on UV protection and lifestyle changes.
Supplement vitamin D and calcium.
Use immunosuppressive drugs based on disease severity and organ involvement:
- Tacrolimus (calcineurin inhibitor)
- Mycophenolate mofetil or azathioprine
- Belimumab (B cell targeted therapy)
- Glucocorticoids for inflammation control
- NSAIDs for symptomatic relief
Control hypertension and other cardiovascular risk factors.
Monitor and treat complications such as osteoporosis and antiphospholipid syndrome.

Speakers / Sources Featured

The subtitles do not specify individual speakers or named sources.
The content appears to be delivered by a single medical educator or clinician providing a comprehensive overview of SLE.

End of Summary