🩻MSK🩻 - Lupus Flashcards
What are the autoimmune connective tissue disorders?
SLE
Sjogren’s syndrome
Systemic sclerosis (scleroderma)
Autoimmune inflammatory muscle disease
What is SLE?
Autoimmune disease involving disturbance of both innate and adaptive immune systems
Autoantibodies to nuclear components
Antibody-antigen (immune complexes) & other mechanisms -> chronic tissue inflammation
Multi-site inflammation but particularly the joints, skin and kidney
What features are characteristic of autoimmune connective tissue disorders in general?
Arthralgia and non-erosive arthritis
Serum autoantibodies - useful diagnostically, corelates with disease activity, may be directly pathogenic
Raynaud’s phenomenon - intermittent vasospasm of digits - usually triggered by cold exposure
Outline Raynaud’s
Intermittent vasospasm of digits
Usually triggered by cold exposure
Typical triphasic colour changes - white, blue, red
Severe Raynaud’s -> tissue ischaemia, ulcers and necrosis
What is the epidemiology of SLE?
Typical onset between 15 – 45 years
F:M ~9:1
Prevalence and severity varies by ancestry
African > Asian > White European
Clinical manifestations highly variable
Disease can range from mild to life threatening
Why is there so much variety in SLE presentations?
Target of autoantibodies are nuclear components - present in just about every cell
Such a wide variety of potential targets = a huge variety of outcomes and presentations
How do finger deformities in SLE differ from those in types of arthritis?
SLE-induced deformities show no bony erosions - deformity is due purely to soft tissue damage
What are some of the clinical features of SLE?
Skin and mucosa - malar rash, photosensitive rash, mouth ulcers, hair loss
Vascular - Raynaud’s
MSK - Arthralgia and (non-erosive)
Internal organs - serositis (pericarditis, pleuritis etc…), renal disease, cerebral disease, myocarditis
Haematological - autoimmune thrombocytopenia, haemolytic anaemia
Other - lymphadenopathy, fever with no infection
Can be any combination of the above
What marker is a hallmark of SLE?
Presence of ANA
What is ANA?
Anti-nuclear antibodies
Found in all SLE patients (actually some don’t but for the purposes of the exams assume they all do)
Negative ANA rules out SLE, positive doesn’t diagnose however - may be seen in other autoimmune diseases, infections or even sometimes healthy people
What is done after ANA are identified?
What is APL?
Antiphospholipid (APL) antibodies
As well as ANA, some SLE patients have antibodies directed to phospholipids on cell membrane
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What is the presence of APL antibodies associated with?
Increased risk of thrombosis:
Arterial - stroke
Venous - DVT
Pregnancy loss - miscarriage
What is anti-phospholipid antibody syndrome?
Persistent presence of APL + a clinical event
Anti-phospholipid antibody syndrome can also occur in absence of SLE
(‘primary anti-phospholipid antibody syndrome’ )
What other autoantibodies are specific for SLE?
Anti-double stranded DNA antibodies (anti-dsDNA) - serum level correlates with disease activity
Anti-Sm antibodies
What autoantibodies are associated with RA?
Rheumatoid Factor
Anti-cyclic citrullinated peptide antibody
What autoantibodies are associated with SLE?
Antinuclear antibodies (ANA)
Anti-double stranded DNA antibodies (anti-dsDNA)
Anti-phospholipid antibodies
Anti-Smith
Anti-Ro
Anti-La
Anti-RNP
Which of SLE’s immunopathogeneses stem from innate immunity?
Overactivity of type 1 interferon pathway
Complement pathway abnormalities
Which of SLE’s immunopathogeneses stem from adaptive immunity?
Autoreactive T and B cells
How is the immune system generating a response to nuclear antigens?
(should be hidden inside the cell)
the ‘waste disposal hypothesis’
What types of investigations would you do for SLE?
Inflammation
Haematology
Renal
Immunological
What inflammatory markers would their be in SLE?
High ESR
Normal CRP (unless infection or serositis/arthritis)
What might you find in haematological investigations in a patient with SLE?
Haemolytic anaemia
Lymphopenia
Thrombocytopenia
What renal signs might you see in SLE?
Urine protein - VERY IMPORTANT
Creatinine
Look at albumin
Kidney biopsy if persistent proteinuria
What immunological signs might be apparent upon investigation in SLE?
ANA
Anti-dsDNA
Low complement (i.e. low C4 and C3) - complement used in immune complexes
APL antibodies
