Pathology & Pathogenesis Of Rheumatoid Arthritis Flashcards
What are the different sources of musculoskeletal pain?
Soft tissue
Bone
Joint
Referred/central
What are the 2 different types of joint disorder?
- Degenerative: OA
2. Inflammatory: infection (e.g. septic arthritis), crystal arthropathy (e.g. gout/pseudogout) or autoimmune disorder
What are the 3 different types of autoimmune inflammatory joint disorder?
- RA
- Connective tissue disorder e.g. SLE or Sjogren’s syndrome
- Spondylo-arthritis inv. spine as well as joints
What are the causes of inflammatory polyarthritis?
- Infection e.g. streptococcal septic arthritis
- Post infectious
- Reactive arthritis
- Crystal arthritis e.g. gout
- RA
- SLE
- Sarcoidosis
What are the causes of virus arthralgia?
- Hep B and C
- Rubella
- Parvovirus infection (erythrovirus)
What are the key features of a joint?
- Hyaline cartilage smooth joint is in synovial cavity surrounded by synovial fluid which lubricates joint
- Synovium (serous membrane) is a sheet of fibrous connective tissue that secretes synovial fluid surrounding this
- Joint capsule spans the 2 bones and surrounds all of this protecting and supporting the joint
What are synovocytes?
Specialised cell present in layers no more than 4 cells thick but commonly just 1, that produce synovial fluid
What is the function of synovial fluid?
Metabolite exchange medium
Lubricant for synovial joints
Serum autoantibody detection DOES NOT equal ____ ___. Why?
Autoimmune disease
Because we are all constantly developing autoimmunity that our body detects and controls and also, the presence of autoAbs increases in frequency the older we get
Why does the prevalence of autoantibodies (autoAbs) increase with advancing age?
Repeated exposure to infection
How are T cells regulated?
In the thymic cortex, millions of T cells are made every day with different fates:
- Many recognise self-peptides strongly so undergo clonal deletion
- Many do not recognise anything and die through neglect
- A few recognise self-peptides weakly so are allowed to mature and leave the thymus
How are B cells regulated?
B cells which meet and therefore recognise self-Ag in the bone marrow are anergised (clonal anergy) which means they are alive but unresponsive and suppressed
Give some examples of autoimmunity theories.
- Defects in T reg cells
- Molecular mimicry between pathogens and self-peptides when a foreign Ag looks similar to a self Ag
- Polyclonal activation of anergised B cells during immune responses or infection e.g. EBV causing recognition of self Ags
- Sequestered Ag not seen by developing T and B cells so when exposed for e.g. in trauma, it is seen as foreign (e.g. sperm or eyes)
Why do some people get autoimmune disease and others don’t?
Genetic susceptibility -> autoimmune diseases are clustered in families AND in individuals
What are some theories of autoimmunity triggers causing genetically susceptible people to get autoimmune diseases?
- Female hormones (and also pregnancy)
2. Trigger such as infection
What genes are many autoimmune diseases associated with? What does this suggest?
HLA/MHC gene involved with antigen presentation by T cells which suggests that presentation of self-peptides to autoreactive T cells is significant
What gene is rheumatoid arthritis (RA) associated with?
HLA-DR4 (and HLA-DR1)
What is rheumatoid factor (RhF)?
A IgM autoAb against the Fc fragment of IgG - present in RA (~70%), other rheumatic disorders, sarcoidosis, infections and advancing age so DO NOT CHECK IT IN A PATIENT WITH JOINT PAIN
How does rheumatoid arthritis (RA) cases often present clinically when taking a patient history?
- Often young-middle age females (20-50yrs)
- Pain/stiffness in joints
- Gradual/sudden onset
- Symmetrical usually in hands, feet and other joints
- Extra-articular features in 20% of patients such as fatigue, anorexia, weight loss, low grade fever and anaemia
- Usually RA is present in a family member
- Smoking increases risk of RA development
What are the 3 key signs to look out for to catch it early so it can be treated early with a better outcome?
S: early morning joint STIFFNESS lasting > 30 mins
S: persistent SWELLING of 1 joint or > esp. hand joints
S: SQUEEZING the joints is painful
What joints can rheumatoid arthritis (RA) affect?
Hands/feet most commonly Elbows/knees Hip Shoulder Neck TMJ
How does the rheumatoid arthritis (RA) hand deformity advance if not treated early?
- Early fusiform swelling
- Ulnar deviation/MCP subluxation
- Swan neck deformities
- Boutonniere deformities: PIP joint bent towards palm whilst DIP joint is bent back away
What are rheumatoid nodules?
Firm lumps that appear subcutaneously on hands, heels and elbows and also at pressure points that are not usually painful e.g. present commonly on knuckles (MCP joint) of hand
What extra-articular features can be caused by rheumatoid arthritis (RA)?
Cardiac: pericarditis, valve problems + atherosclerosis -> IHD + CVA
Pulmonary: pleural effusions, rheumatoid nodules + pulmonary fibrosis
Blood: anaemia (chronic/haemolytic) + splenomegaly (Felty’s syndrome)
Bones: localised osteoporosis
Skin: rheumatoid nodules, vasculitis + leg ulcers
Neurological: C1/C2 atlanto-axial subluxation + nerve compression
Eyes: scleritis + xerophthalmia (2ndary Sjogrens syndrome)