Arthritis

• Arthritis can affect:

  •1 joint: monoarthritis e.g. Septic arthritis, trauma induced arthritis, crystal induced arthritis (gout, pseudogout)

  •2-3 joints: oligoarthritis e.g. Reactive arthritis, ankylosing spondylitis, rheumatic fever, osteoarthritis

  >3joints: polyarthritis e.g. Rheumatoid arthritis, systemic lupus erythematosus, osteoarthritis
• Our body presents material to the immune system via the HLA system:

  • HLA class 1 (A,B and C): sit on the surface of nearly all cells and presents material from within the cells to the immune system
  • HLA class 2 (DR,DP and DQ): sit on antigen presenting cells and present material it finds floating around outside of cells to immune system
  • Lots of different variations of HLA proteins depending on our genetics e.g. HLA-B27
• Autoimmune disorder = issue with adaptive immune system e.g. anti-CCP antibodies in RA
• Autoinflammatory disorder = problem with innate immune system - producing inflammatory cytokines that cause inflammation and damage to own tissues

  e.g. release of cytokines in response to crystals in gout and pseudogout
• If your genes encode the HLA subtype HLA-B27 you are more prone to developing spondyloarthropathies
• Inflammatory arthritis can be split into 2 subtypes:

  • Autoinflammatory arthritis - crystalline arthritis and seronegative spondyloarthritis
  • Autoimmune arthritis - seronegative spondyloarthritis, RA and inflammatory arthritis as a result of autoimmune condition e.g. SLE
• Seronegative spondyloarthritis:

  • Classified as autoinflammatory and autoimmune arthritis (despite no antibodies being identified for these diseases)
  • Seronegative = no identifiable autoantibodies
  • Are a group of inflammatory conditions with shared features associated with HLA-B27
  • Ankylosing spondylitis
  • Psoriatic arthritis
  • Reactive arthritis
  • Enteropathic arthropathy