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Flashcards in RA Deck (27):
1

definition of RA

an illness causes by polyarticular inflammatory arthritis, associated with other systemic symptoms

2

who is most affected by RA?

women

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requirements for RA diagnosis

patient with at least one joint with DEFINITE clinical synovitis that is not better explained by another disease

(joint distribution, RF/ACPA serology, symptom duration, ESR)

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common features of joint distribution in RA

carpal, MCP, PIP joints affected. DIP joints spared. subluxation common

5

where does the synovium anchor within the joint?

at the margin of the cartilage and bone

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early stage RA

inflammation within the joint. synovium thickens by hypertrophy and hyperplasia. joint distention due to inflammatory cells within fluid that is less viscous than normal.

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middle stage RA

tremendous inflammation of synovium causes bony destruction and cartilage damage at the margin. synovium becomes thickened and looks like wet bread (called pannus).

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late stage RA

tremendous damage to bone and cartilage. Vascular supply is outstripped by growth of synovium

9

RA vs OA vs Spondylitis

inflammatory disease of synovium affecting small joints of hands/feet
degenerative disease of cartilage affecting hands and weight bearing joints
inflammatory disease of synovium and enthuses, axial and peripheral joints affected

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shared epitope hypothesis

HLA DR alleles that are associated with RA share an amino acid sequence that constitutes part of antigen binding groove

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risk factors that might trigger immune response in RA

infectious agent, pesticides, smoking, gingivitis

12

smoking and RA

can cause citrullination in the lungs leading to anti CCP antibodies which direct against residues of type 2 collagen

13

periodontal disease and RA

cause and effect relationship is unclear

14

histology of normal synovium

thin membrane of 1-2 cells deep, supported by fibrous tissue.

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histology of inflamed RA synovium

thickening of synovial cell layer (hypertrophy), proliferation of the synovium (hyperplasia), perivascular infiltrates of inflammatory cells, increased vascularity

16

how can RA be self perpetuating?

immune cells that infiltrate synovium may organize into germinal centers and perpetuate antigen presentation and autoimmune reaction

17

antibodies indicative of RA

RF and anti-CCP. (can form immune complexes that activate complement and attract other inflammatory cells to synovium)

18

RF (rheumatoid factor)

polyclonal antibody (IgM) that binds to Fc portion of IgG. enhances antigen presenting role of b cells. can self associate into immune complex that fixes complement and activates inflammation.

19

cytokines associated with RA

TNFa, IL6, Lymphotoxin, IFNy

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what is the boss cytokine in RA?

TNFa

21

mechanism of cartilage destruction in RA?

cytokines activate collagenase/MMPs. when released from fibroblast, works from the outside in. when released from chondrocyte, works from the inside out.

22

mechanism of bone destruction in RA?

cytokines activate RANKL, which is an osteoclast differentiation factor

23

RANK

receptor on pre-osteoclasts and osteoclasts that signals for their differentiation and activation

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RANKL

membrane bound or secreted protein from stromal cells, osteoblasts, T cells, and synovial fibroblasts that activates RANK

25

OPG (osteoprotegerin)

natural RANK antagonist that is secreted by many different cells, which functions by binding RANKL

26

non joint symptoms of RA patients?

accelerated atherosclerosis (likely due to systemic inflammation), increased risk of infection/malignancy, secondary sjogren's vasculitis, increased pulmonary autoimmune disease.

27

treatment for RA

inhibit TNFa, inhibit B cell function (rituximab), inhibit co-stimulatory molecules, inhibit cytokine receptors, inhibit RANK activation