Seronegative Spondyloarthropathies Flashcards
(48 cards)
What is Spondyloarthritis?
An umbrella term for a group of inflammatory disorders that involve the joints and the entheses
What does seronegative mean?
Negative for rheumatoid factor
Name some seronegative spondyloarthropathies.
Ankylosing Spondylitis Psoriatic arthritis Reactive arthritis Juvenile Idiopathic arthritis Enteropathic arthritis
What are entheses?
The sites where ligaments and tendons attach to the bones
The seronegative spondyloarthropathies are associated with a particular tissue type. Which one?
HLA B27
What is HLA B27?
Human Leukocyte Antigen type B27
HLA class I antigens are found on all cells of the human body? True or false?
False, not on red blood cells
Do all people with HLA B27 get seronegative spondyloarthropathies?
No
Name the theories that explain why HLA B27 is linked with seronegative spondyloarthropathies?
- Molecular mimicry
- Misfolding
- Heavy Chain theory
What is the ‘molecular mimicry’ theory?
Infection with an agent with similar shaped antigens to B27 molecules
The body makes antigens against the pathogen’s antigens
But they attack the (very similar) B27 antigen
Immune system is attacking its own cells
What is the ‘misfolding’ theory?
Unfolded proteins get trapped in the endoplasmic reticulum of macrophages
This causes a response involving IL-23 and IL-17
These cause inflammation and damage to joints
What is the ‘heavy chain’ theory?
B27 chains tend to dimerise and accumulate in the ER
This initiates a response involving IL-23 and IL-17
These cause inflammation and damage to joints
What are the general features of the seronegative spondyloarthropathies?
HLA B27 association
Axial arthritis: axial skeleton
Asymmetrical large joint affecting a few or 1 joint
Enthesitis
Dactylitis
Extra-articular manifestations
What is meant by ‘axial arthritis’?
Affecting the axial skeleton:
- spine
- ribs
- pelvis
- sacroiliac joints
What is enthesitis?
Inflammation of the entheses (attachments of tendons + ligaments to bone)
What is dactylitis?
Inflammation of the entire digit
Featuring soft tissue oedema, tenosynovial + joint inflammation
Sausage digit
What is sausage digit?
A digit affected by dactylitis: oedema and swelling make the digit resemble a sausage shape
Painful
What are some extra-articular manifestations of the seronegative spondyloarthropathies?
Anterior uveitis Psoriaform rash Oral ulcers Aortic valve incompetencies IBD
What is a good mnemonic to remember the general features of the seronegative spondyloarthropathies?
SPINEACHE
S - sausage digit P - psoriasis I - inflammatory back pain N- NSAIDs good response E - enthesitis A - arthritis C - crohn’s / colitis (or family history of it) / raised CRP H - HLA B27 E - eye (uveitis)
What is anterior uveitis?
Inflammation of the uvea
Uvea = middle part of the eye that consists of the iris, ciliary body and choroid
What is ankylosing spondylitis?
Chronic inflammation of the spine + sacro-iliac joints
Who is affected with ankylosing spondylitis?
Young adults, peak onset 20-30 years
Men more than women
90% of patients are HLA B27
Clinical features of ankylosing spondylitis?
Gradual onset of low back pain
Pain worse at night
Spinal morning stiffness relived by exercise
Pain in sacroiliac joints radiates to hips + buttocks
In time, rigid spine - bone has fused together after years of inflammation
If severe: stooped posture, neck hyperextension
Anterior uveitis
Asymmetric peripheral arthritis
Osteoporosis
What are the symptoms + signs of anterior uveitis?
Painful red eye Irregular pupil White cells floating in vitreous fluid Photophobia Cloudy vision
