Rheumatic Disorders (Pathophysiology) - Block 1 Flashcards
What is rheumatoid arthritis?
Chronic systemic inflammatory autoimmune disease characterized by:
1. Synovial inflammation and hyperplasia
2. Auoantibody production
3. Cartilage and bone destruction
4. Systemic involvement
What is the cause of RA?
Genetic susceptibility (HLA-DRB1, PTPN22, PADI4) + environmental trigger (smoking, silica, air pollution, estrogen) + Infectious agents (EBV, CMV, E coli, mycoplasmas, P. gingivalis) -> loss of tolerance -> RA
What are the sx of RA?
- Joint
- Chronic, erosive polyarthritis: Symmetrical, bilateral inflammation in joints
- Metabolic manifestations: fatigue, anorexia, weight loss, weakness, low grade fever
What are the joint sx of RA?
- Join swelling
- Stiffness (morning stiffness, inactivity)
- Warmth
- Tenderness
- Pain
What is polyarthritis?
arthritis affecting 4 or more joints
What is polyarthralgia?
Pain in more than 4 joints
What is joint swelling caused by?
Fluid accumulation in joint capsule
What are the small joints in the hands and feet?
Proximal interphalangeal (PIP)
Metacarpophalangeal (MCP)
Distal interphalangeal (DIP)
Metatarsalphalangeal joints (feet)
What are the types of RA joint deformities?
- Ulnar deviation deformity of the fingers
- Mallet finger deformity of the distal interphalangeal joint
- Swan-neck deformity of the proximal interphalangeal joint
- Boutonniere deformity due to extension of distal interphalangeal joint
What are rheumatoid nodules?
- Most common cutaneous manifestation of RA
- Found on pressure points such as forearm and joints of the hands and toes
- Asymptomatic but may ulcerate that must be surgically removed
What is the hallmark of RA?
Bone erosion
What are the systemic sx of RA?
Pulmonary and cardiac disease
Describe the progression of RA?
What are cryptic epitopes?
When molecule is denatured or altered, Hidden epitopes are exposed and recognized by the immune systme generating autoantibodies
What is RF?
IgM against IgG
When IgG antibodies bind, they undergo a conformational change than exposes cryptic epitopes that are recognized by RF
What is used to diagnose RA?
RF and anticitrullinated protein antibodies (ACPA)
What are Citrullinated peptides (CCPs)?
Foreign proteins that mount an immune response
How does autoantibodies contribute to RA?
- Forming immune complexes by binding to autoantigens or soluble antigens
- Activation of classical complement
What cells produce autoantibodies?
Plasma cells in joints
Where are autoantibodies found?
Serum and synovial fluid
What are the prominent autoantibodies associated with RA?
- RF (IgM Ab against IgG Fc portion (cryptic epitope))
- Anti-Citrullinated Protein Autoantibodies (ACPA)
Describe the structure of the synovial joint?
- Found between bones that move against each other
- Cartilagecovers the end of the articulating bones
- Surrounded by a joint capsule
- Dense connective tissue that attached to bones forming a sleeve around the joint (Outer=fibrous, Inner=synovium)
- Synovial membrane produces the lubricating fluid of the joint-synovial fluid
How is the synovial joint affected by RA?
Formation of a pannus leads to erotion of cartilae and bone destroying surrounding tissue
What is a pannus?
Synoviocytes undergo hyperplasia and swell, thickening the synovial tissue
Describe the immunological components of RA?
- APCs present self-antigen to helper T cells
- T cells secrete inflammatory cytokines and help B cells and Macrophages become activated
- B cells are activated and secrete inflammatory cytokines and differentiate into plasma cells.
- Plasma cells secrete autoantibodies that form immune complexes.
- Activates a Type III hypersensitivity response: Immune complex mediated hypersensitivity
Decribe the macrophage and neutrophil action in RA?
Secrete inflammatory cytokines that lead to:
1. Increased vascular permeability (swelling): TNF-a and IL-1
2. Warmth: IL-1, TNF-a and IL-6; IL-6 initiates the acute phase response
3. Macrophages secrete matrix metalloproteases that degrade collagen (pannus expansion and invasion of the joint)
4. Macrophages secrete IL-1 and RANKL, which activates chondrocytes and osteoclasts to degrade of the cartilage and bone of the joint
Chronic inflammation leads to ___ and ___?
Scar tissue and bony fusion (ankylosis)
Increase pannus formation, leads to ____ and ____ erosion leading to _____?
Joint and cartilage; reduced joint space
What is the difference between remission and relapse?
Remission: Period of time when symptoms and inflammation is low or non existent
Relapse: After remission when symptoms return