7. Rheumatoid Arthritis Flashcards
what key feature distinguishes RA from OA
RA is an autoimmune disease
how is inflammation in the joints presented in RA
symmetrical in presentation and develops simultaneously
name 3 similarities between RA and OA
- both located in joints
- no cure for either
- not fatal conditions but can decrease quality of life
what is the difference between RA and OA in terms of the area it affects
OA primarily affects cartilage
RA primarily affects the lining of the joint (synovial membrane)
which has a shorter timescale: RA or OA
RA
how long does RA take to develop
a few months, but can be within a week in 15% of cases
name 4 symptoms of RA
symmetrical joint swelling
morning stiffness
fatigue
Raynaud’s phenomenon
describe 3 methods of how RA is diagnosed
observation of symptoms
detection of rheumatoid factor
X-ray
at what stage would an Xray only provide a diagnosis
at late stages - where there is joint erosion
what is rheumatoid factor
a group of autoantibodies to the Fc portion of IgG
what joint is affected the most in RA
finger joints
name two joints on the fingers affected by RA
proximal interphalangeal joint
distal interphalangeal joint
what are synoviocytes
fibroblast like cells
what is the role of synoviocytes
cells responsible for the production of synovial fluid components, absorption from the joint cavity and for blood/synovial fluid exchange
describe the positioning of normal synoviocytes
line the fluid filled synovial membrane
what causes the abnormal proliferation of synoviocytes
inflammatory processes
what does the extensive growth of synoviocytes result in
uncontrolled growth = vascularisation and extensive angiogenesis
describe what happens to the synovial lining when cells start to grow
it eventually connects with the cartilage on the surface of the tibial plaque and causes damage to the cartilage
what facilitates bone erosion
imbalance of osteoclasts and osteoblasts prevents the normal turnover of bone = destruction
what aggrecan damaging protein is also elevated in RA, what does this do?
matrix metalloproteinase
- breaks down aggrecan, no water can be held in the cartilage = cartilage damage
which is more common: OA or RA
OA - less than 1% of the population suffer with RA
is RA sex biased?
yes - women are 2-3x more likely to suffer RA
name some ethnic groups with a lower prevalence of RA
Chinese and japanese
what is the typical age of onset for RA
40-60 years old
how long does RA take to develop
typically over several months
but in 15% of cases it can happen within 1 week
what gene is associated with 30% of the risk of RA
HLA-DRB1
what is the role of HLA-DRB1
encodes part of the HLA complex which is involved in distinguishing self from non-self
name a polymorphism that can act as a risk factor for several autoimmune diseases
PTPN22
name 2 environmental risk factors for RA
higher BMI - over 25 increases the risk by 15%
smoking
how much increased is the risk for RA in males who smoke compared to females
males who smoke 2X increased risk
females = 1.3X increased risk
what does the scientific community postulate to be a trigger of RA
both viral and bacterial infections
what is a medical mystery in RA
some people get spontaneously better!!
what does SADMD stand for
slow acting disease-modifying drugs
give an example of SADMD
gold injections
give an example of an immunosuppressant
methotrexate
what is the risk of methotrexate
it is not targeted immune suppression - can lead patients vulnerable to infection and can increase the risk of tumour growth
describe the use of corticosteroids in RA
effective short term relief from symptoms
potent anti-inflammatory drugs
effectiveness is short term!!
what is the problem with corticosteroids
they are addictive and effectiveness is short term
how does infliximab work?
- soluble TNF alpha is prevented from binding and creating a pro-inflammatory cascade
- transmembrane TNF alpha is marked for cell lysis via complement cascade
- increases IL-10 to create an anti-inflammatory microenvironment
