WEEK 5 Rheumatoid arthritis Flashcards
(11 cards)
What is Rheumatoid arthritis?
(RA) is an autoimmune disorder that primarily affects the joints but can also involve other tissues and organs in the body. The pathophysiology of RA is complex and involves a dysregulated immune response that leads to chronic inflammation, joint damage, and systemic manifestations.
Autoimmune Response: in RA
RA is characterized by an autoimmune response, where the body’s immune system mistakenly attacks its tissues, primarily the synovium (lining of the joint capsule).
Antigen-presenting cells, such as dendritic cells and macrophages, play a role in presenting self-antigens (like citrullinated proteins) to T cells, leading to the activation of autoreactive T cells
Inflammatory Cytokines in RA
Activated T cells release pro-inflammatory cytokines, particularly tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6).
These cytokines contribute to the recruitment of immune cells, such as neutrophils and monocytes, into the synovial tissue.
Synovial Inflammation
in RA
Chronic synovial inflammation is a hallmark of RA. The synovium becomes thickened and infiltrated with immune cells.
Pannus formation occurs, which is an invasive, hyperplastic synovial tissue that invades and damages the adjacent joint cartilage and bone.
Cartilage and Bone Destruction
in RA
Inflammatory cytokines and enzymes, such as matrix metalloproteinases (MMPs) and cathepsins, are released and contribute to the destruction of articular cartilage and subchondral bone.
Osteoclasts, cells responsible for bone resorption, are activated and contribute to bone erosion.
Autoantibodies in RA
Rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPAs) are autoantibodies commonly found in the blood of individuals with RA.
These autoantibodies contribute to immune complex formation and inflammation within the joints.
Synovial Angiogenesis in RA
Chronic inflammation in the synovium leads to angiogenesis, the formation of new blood vessels.
These newly formed blood vessels supply nutrients and oxygen to the proliferating synovial tissue, sustaining the inflammation.
Systemic Involvement in RA
RA is not limited to joint inflammation; it can also affect other organs and systems, such as the skin, heart, lungs, and blood vessels.
Systemic inflammation can lead to complications like cardiovascular disease, pulmonary involvement, and rheumatoid nodules.
Genetic and Environmental Factors
in RA
Genetic factors, particularly certain human leukocyte antigen (HLA) alleles, are associated with an increased risk of RA.
Environmental factors, such as smoking, infections, and hormonal changes, may trigger or exacerbate the disease in genetically susceptible individuals.
Immunological Memory in RA
Once the autoimmune response is initiated, the immune system forms memory T cells and B cells, leading to a persistent and chronic inflammatory state.
Synovial Fibroblasts in RA
Activated synovial fibroblasts play a role in the perpetuation of inflammation and joint damage by releasing cytokines and enzymes that contribute to tissue destruction.
