Rheumatoid arthritis Flashcards
(114 cards)
What are some of the symptoms a patient may initially experience before joint inflammation occurs?
Fever
Malaise
Weakness
Arthralgia
Which joints are most commonly affected by RA?
Joints of the hand, feet, knee and hip
How many people in the UK are affected by RA?
600,000 people and prevalence is said to be roughly 0.5-1%
At what age do people tend to develop RA?
Between 25-50 years
Define Rheumatoid arthritis.
Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease.
What is the key characterisation of RA?
Proliferative synovitis and inflammatory arthritis with erosions
What is the ratio of women to men that have RA?
2-3:1
Due to possible effect of the female hormones (oestrogen) as in addition use of the contraceptive pill shows higher proportion of RA sufferers.
Explain the role of genetics in RA predisposition?
It is believed that RA is multifactorial meaning that there is not one singular cause but is a combination of genetics, environmental and immunological factors but having said that there is a genetic predisposition.
What are some of the genes involved in RA?
70% of RA sufferers have HLA-DR4 present
STAT-4
TRAF1/C5
PTPN22
Describe some of the environmental factors that perhaps link to RA?
Tobacco smoke
Air pollution
Mineral oil
Silica
Infectious agents
Describe some of the immunological factors involved in the pathogenesis of RA?
RF
Anti-citrullinated cyclic peptide
Immune dysregulation
Antibody responses to modified peptides
Increased production of cytokines and chemokines
What is the concordance rate of twins with RA?
15-20% (15% in monozygotic twins)
Which allele is associated with an increased risk of RA?
MHC allele HLA-DRB1 increased risk of 4-12 times
What are some of the potential infections said to be associated with the onset of RA?
Mycobacterium
Mycoplasma
Streptococcus
Epstein Barr virus
Parvovirus
All suggested, nothing confirmed
What are the role of B cells in RA pathophysiology?
Produce auto-antibodies which cause complement activation
Bind to activated macrophages which they perpetuate inflammation
What are the roles of auto-antibodies in RA pathophysiology ?
Rheumatoid factor is directed against Fc factor fragment of IgG
Anti-citrullinated peptides are directed against antigens in the joint
What are the roles of T cells in RA pathophysiology?
They activate monocytes or macrophages and synovial fibroblasts by producing TNF-alpha, IL-1B or IL-6 which results in the production of MMPs which lead to the degradation of cartilage
Joint destruction might be caused by CD4 (+) T cell cytokines.
What is the function of the RANK ligand?
Promotes osteoclasts
Briefly outline the pathogenesis of RA.
There is normally an initiator event such as injury, infection and illness however then there is persistent inflammation where APCs are recruited and there is citrullination of proteins and it is perceived as a non-self immune response. Tis leads to a clonal expansion of B and T cells uncontrolled by T regulatory.
There is now inflammatory damage in the synovium, self antigens that were previously unseen now become exposed and the immune system attacks the cartilage, there is an infiltration of immune cells.
Fibroblasts and osteoclasts become activated by pro-inflammatory cytokines TNF and IL-6 resulting in the destruction of the bone.
State the co-morbidities of RA associated with systemic pro-inflammatory cytokines.
Iron redistribution in the liver
Free fatty acid deposition
Insulin resistance in the muscle
Lone bone mineral density - osteoporosis
Low stress tolerance, depression
Atherogenesis, MI, stroke
Which cytokines are associated with iron redistribution in the liver?
IL-6
Which cytokines are associated with free fatty acid deposition?
TNF-a and IL-6
Which cytokines are associated with insulin resistance in the muscle?
TNF-a and IL-1
Which cytokines are associated with low mineral bone density?
TNF-a, IL-6, IL-1