MSK L11 Rheumatoid Arthritis Flashcards
Definition
Autoimmune, chronic inflammatory disease, primarily affects the synovial joints
Clinical signs
➢ Soft tissue swelling • Effusion • Warmth • Erythema ➢ Joint deformity ➢ Reduced range of movement ➢ Muscle wasting
Radiological signs
Erosion of bone
Deformity
Symptoms
- Pain
- Stiffness
- Unpredictable ‘flare’ of inflammation
- Fatigue
- Disability
- Psychological effects
• Anxiety
• Depression
• Helplessness
Epi
Half a million in UK have RA
Prevalence worldwide → 0.5-1% WW
40% of patients are registered disabled within 3 years
Cost of treating RA in the UK is £0.8-£1.3 million
Population
Indians highest prevalence
Causes →
Possible antigenic targets in RA:
Microbial antigens:
Self antigens
Microbial antigens causing RA examples
- Super antigens (doesn’t require processing recognised by T-cell immediately) e.g. staphylococcal toxins
- Epstein-Barr virus antigens
- Heat shock proteins (HSPs)
- Parvovirus antigens
Self antigen associated with RA
- Collagen e.g. type II
- Cartilage link protein
- HSPS
- Aggrecan (cartilage matrix)
- Class II MHC shared epitope
- IgG Fc portion
Pannus: Formed from
Synovial hyperplasia containing many inflammatory cells (pannus) that erodes cartilage and bone.
Pannus function
Main form of joint destruction in RA
Panus contains
Abundant cell population: 1. Lymphocytes 2. Macrophages 3. Fibroblasts* Other cell population: 1. B lymphocytes – antigen processing 2. Dendritic cells 3. Plasma cells 4. Mast cells – pro-inflammatory
*Fibroblast cells →
apoptosis is delayed in RA therefore the fibroblasts continue to produce cytokines and enzymes continuing to erode the joint.
Role of B cells →
Auto antibodies:
- Antibodies to the Fc (Rhuematoid factor), Fac and F(ab)2 of the self IgG molecule
- Antibodies to Cellular antigens histone, ssDNA, RA nucleus antigen etc.
- Anti-collagen antibodies
- Antibodies to HSPs
Role of B cells in pathology→ Rheumatoid factors
- Ig classes of IgM, IgG, IgA and IgE
- RF found in 7-% of RA patients
- Not useful in diagnosis but is a good prognostic marker