SLE Flashcards
What is systemic lupus erythematosus (SLE)?
Systemic, inflammatory autoimmune connective tissue disease. Often takes a relapsing and remitting course.
Describe the pathophysiology of SLE
- Cell damage occurs resulting in apoptosis of cells
- Apoptotic bodies form and these display internal components of cells e.g. from nuclear, cytoplasm and cell membrane
- Usually, phagocytes clear these apoptotic bodies
- If pt has susceptibility genes, their immune system is more likely to mount an immune response against these intracellular components exposed on apoptotic body. Furthermore, in pts with SLE there is decreased clearance of these apoptotic bodies
- Immature APCs can bind to these apoptotic bodies and present the intracellular components -which were displayed on the apoptotic body - to immature T cells in lymph node
- T cells differntiate into different mature T cells
- TH2 cells activate plasma B cells causing them to produce autoantibodies to intracellular components-particularly the nuclear components of cells
- Antibodies can then:
- Circulate in body and bind to cells activating complement cascade
- Bind to nuclear antigens and the antigen-antibody complex can deposit in other tissues in body
- .. .both of the above cause inflammation and damage to organ
- Type III hypersensitivity reaction
State some risk factors for SLE
- Female sex
- 15-45 years of age
- Genetic factors/family history
- African/Asian dec
- Drugs
- Drugs that trigger SLE like syndrome include: isoniazid, TNF inhibitors etc..
Who does SLE typically present in?
- Young to middle aged females
- Asian/african ethnicity (if in US or Europe)
State some symptoms of SLE
- Fatigue
- Weight loss
- Arthralgia
- Myalgia
- Fever
- Rash on face which is photosensitive
- SOB
- Mouth ulcers
- Hair loss
- Raynaud’s phenomenom
- Abdo pain
- Nausea, vomitting
State what you might find on clinical examination of somoeone with SLE
- Lymphadenopathy
- Splenomegaly
- Hypertension
- Signs of nephrosis e.g. oedema
- Photosensitive malar rash
- Discoid rash
- Livedo reticularis
- Mouth ulcers
- Hair loss
What mneumonic can you use to remember signs & symptoms of SLE?
SOAP BRAIN
- Serositis: pleurisy, pericarditis
- Oral ulcers (usually painless)
- Arthritis (of small joints, non-erosive)
- Photosensitivity and/or malar/discoid rash
- Blood disorders (low WCC, lyphopenia, thrombocytopenia, haemolytic anaemia)
- Renal involvement (glomerulonephritis, proteinuria)
- Autoantibodies
- Immunological tests e.g. low complements
- Neurological disorder e.g. seizures, psychosis, anxiety and depression
What is the most common cardiac manifestation of SLE?
Pericarditis
If you send a test for “antibodies to extractable nuclear antigens (anti-ENA antibodies)” to the lab it will check for antibodies to specific components in the cell nuclear. State the different types of anti-nuclear antibody and state what diseases they are present in
- Anti-Smith: highly specific to SLE but not very sensitive
- Anti-centromere: most associated with limited cutaneous systemic sclerosis
- Anti-Ro and Anti-La: most associated with Sjogren’s
- Anti-Scl-70: most associaed with systemic sclerosis
- Anti-Jo-1: most associated with dermatomyositis
What investigations would you do if you suspect someone has SLE, include:
- Bedside
- Bloods
- Imaging
*Where appropriate justify why you are doing each
Bedside
- Urinalysis: detect renal disease
Bloods
- FBC: anaemia & leukopenia are common
- U&Es: check renal func
- LFTs: check liver func
- ANA autoantibodies: 85-95% of SLE pts are ANA positive. Highly sensitive
- Anti-dsDNA autoantibodies: 70% of SLE pts are positive. Titre rises with disease severity. Highly specific.
- Anti-ENA antibody test: anti-Ro and anti-La are common
- Antiphospholipid antibodies: antiphospholipid syndrome can occur secondary to SLE in up to 40% SLE pts
- Rheumatoid factor antibodies: 20% positive
- ESR: often raised
Imaging
- Any imaging appropriate for systemic symptoms e.g. CXR
Others:
- Renal biopsy
- Skin biopsy
ECG: if has cardiac symptoms
What happens to C3 & C4 as disease activity increases?
C3 and C4 fall with disease activity (due to consumption of complement proteins)
CRP is usually raised in SLE; true or false?
FALSE; CRP is usually normal in SLE.
ESR & plasma viscosity are often raised. ESR generally used. If CRP is raised may indicate underlying infection.
Up to 40% of pts with SLE can develop antiphospholipid syndrome secondary to SLE; state two potential complications of anti-phospholipid syndrome
What 2 criteria can you use to establish a diagnosis of SLE?
Use SLICC criteria or the ACR criteria
They both look at both symptoms & signs and immunological results
Discuss the management of SLE
Anti-inflammatory medication & immunsupression is mainstay of treatment. Treatment is usually titrated upwards to find minimal medication with least side effects to control symptoms:
Non-pharmacological
- Sun protection
- Health lifestyle (in view of CVD risk)
First line treatment Pharmacological
- Hydroxychloroquine is treatment of choice!!
- NSAIDs: may be used for arthritis pain in some patients
- Steroids e.g. prednisolone: may be used for some patients where hydroxychloroquine and NSAIDS inadequete
Other pharmacological treatments
- Immunosuppressants: methotrexate, mycophenolate mofetil, azathioprine, tacrolismus, leflunomide, ciclosporin
- Biological therapies: rituximab, belimumab (monoclonal antibody against B-cell activating factor)
- Cyclophosphamide
Explain the difference between a malar rash and a discoid rash that can be seen in SLE
- Malar rash: erythema over malar eminences (typical butterfly rash)
- Discoid rash: erythematous raised patches with keratotic scaling and follicular plugging
