Systemic Lupus Erythematosus Flashcards
What is Systemic lupus erythematosus (“lupus”)?
an inflammatory autoimmune connective tissue disease. It is “systemic” because it affects multiple organs and systems and “erythematosus” refers to the typical red malar rash that occurs across the face.
It presents with varying and non-specific symptoms. It is more common in women and Asians and usually presents in young to middle aged adults but can present later in life.
What disease course does SLE often take?
a relapsing-remitting course, with flares and periods where symptoms are improved. The result of chronic inflammation means patients with lupus often have shortened life expectancy. Cardiovascular disease and infection are leading causes of death.
Pathophysiology of SLE
SLE is characterised by anti-nuclear antibodies. These are antibodies to proteins within the persons own cell nucleus.
This causes the immune system to target theses proteins.
When the immune system is activated by these antibodies targeting proteins in the cell nucleus it generates an inflammatory response.
Inflammation in the body leads to the symptoms of the condition.
Usually, inflammation is a helpful response when fighting off an infection however it creates numerous problems when it occurs chronically and against the tissues of the body.
SLE presents with non-specific symptoms:
Fatigue
Weight loss
Arthralgia (joint pain) and non-erosive arthritis
Myalgia (muscle pain)
Fever
Photosensitive malar rash. This is a “butterfly” shaped rash across the nose and cheek bones that gets worse with sunlight.
Lymphadenopathy and splenomegaly
Shortness of breath
Pleuritic chest pain
Mouth ulcers
Hair loss
Raynaud’s phenomenon
Investigations for SLE
Autoantibodies
Full blood count (normocytic anaemia of chronic disease)
C3 and C4 levels (decreased in active disease)
CRP and ESR (raised with active inflammation)
Immunoglobulins (raised due to activation of B cells with inflammation)
Urinalysis and urine protein:creatinine ratio for proteinuria in lupus nephritis
Renal biopsy can be used to investigate for lupus nephritis
Autoantibodies associated with SLE?
SLE is associated with anti-nuclear antibodies (ANA). These are antibodies against normal proteins in the cell nucleus. Around 85% of patients with SLE will be positive for ANA. Performing an ANA blood test is the initial step in testing for SLE in someone with symptoms of the condition. Antinuclear antibodies can be positive in healthy patients and patients with other autoimmune conditions (e.g. autoimmune hepatitis). Therefore, a positive result needs to be interpreted in the context of their symptoms.
Anti-double stranded DNA (anti-dsDNA) is specific to SLE, meaning patients without the condition are very unlikely to have these antibodies. Around 70% of patients with SLE will have anti-dsDNA antibodies. The levels vary with disease activity, so they are useful in monitoring disease activity and response to treatment.
Diagnosis of SLE?
You can use the SLICC Criteria or the ACR Criteria for establishing a diagnosis. This involves confirming the presence of antinuclear antibodies and establishing a certain number of clinical features suggestive of SLE.
List all the complications of SLE
Systemic lupus erythematosus affects many of the organs in the body. These effects are related to chronic inflammation.
Cardiovascular disease is a leading cause of death. Chronic inflammation in the blood vessels leads to hypertension and coronary artery disease.
Infection is more common in patients with SLE as part of the disease process and secondary to immunosuppressants.
Anaemia of chronic disease is common in SLE. It affects the bone marrow causing a chronic normocytic anaemia. Patients can also get leucopenia (low white cells), neutropenia (low neutrophils) and thrombocytopenia (low platelets).
Pericarditis is inflammation in the fluid filled sac around the heart. It causes sharp chest pain worse on lying flat.
Pleuritis is inflammation of the pleural lining of the lungs. This is also called pleurisy. It causes typical symptoms of sharp chest pain on inspiration.
Interstitial lung disease can be caused by inflammation in the lung tissue. This leads to pulmonary fibrosis.
Lupus nephritis occurs due to inflammation in the kidney. It can progress to end-stage renal failure. It is assessed urine protein:creatinine ratio and renal biopsy. The renal biopsy is often repeated to assess response to treatment.
Neuropsychiatric SLE is caused by inflammation in the central nervous system. It can present with optic neuritis (inflammation of the optic nerve), transverse myelitis (inflammation of the spinal cord) or psychosis.
Recurrent miscarriage is common in systemic lupus erythematosus. It is associated with other pregnancy complications such as intrauterine growth restriction, pre-eclampsia and pre-term labour.
Venous thromboembolism is particularly associated with antiphospholipid syndrome occurring secondary to SLE.
First line treatment of SLE
NSAIDs
Steroids (prednisolone)
Hydroxychloroquine (first line for mild SLE)
Suncream and sun avoidance for the photosensitive malar rash
Other commonly used immunosuppressants in resistant or more severe lupus:
Methotrexate
Mycophenolate mofetil
Azathioprine
Tacrolimus
Leflunomide
Ciclosporin
Biological therapies are considered for patients with severe disease or where patients have not responded to other treatments. The main options in SLE are:
Rituximab is a monoclonal antibody that targets the CD20 protein on the surface of B cells
Belimumab is a monoclonal antibody that targets B-cell activating factor
