Immunopathogenesis of osteoarthritis

Abstract

Even though osteoarthritis (OA) is mainly considered as a degradative condition of the articular cartilage, there is increasing body of data demonstrating the involvement of all branches of the immune system. Genetic, metabolic or mechanical factors cause an initial injury to the cartilage resulting in release of several cartilage specific auto-antigens, which trigger the activation of immune response. Immune cells including T cells, B cells and macrophages infiltrate the joint tissues, cytokines and chemokines are released from different kind of cells present in the joint, complement system is activated, cartilage degrading factors such as matrix metalloproteins (MMPs) and prostaglanding E2 (PGE2) are released, resulting in further damage to the articular cartilage. There is considerable success in the treatment of rheumatoid arthritis using anti-cytokine therapies. In OA, however, these therapies did not show much effect, highlighting more complex nature of pathogenesis of OA. This needs the development of more novel approaches to treat OA, which may include therapies that act on multiple targets. Plant natural products have this kind of properties and may be considered for future drug development efforts. Here we reviewed the studies implicating different components of the immune system in the pathogenesis of OA.

Association between severity of knee osteoarthritis and serum and synovial fluid interleukin 17 concentrations

“…Although rheumatoid arthritis and osteoarthritis have different aetiologies, the diseases share several common characteristics including destruction of articular cartilage, joint space narrowing and synovitis. 24 The concentration of IL-17 in synovial fluid, but not serum, was found to correlate significantly with Lequesne index (an objective assessment of osteoarthritis severity) in the current study. The increased IL-17 concentrations in synovial fluid may be attributable to the increased local and systemic production of IL-17 by synovial cells and chondrocytes in local and extra-articular tissues.…”

Serum and synovial fluid chemokine ligand 2/monocyte chemoattractant protein 1 concentrations correlates with symptomatic severity in patients with knee osteoarthritis

“…22 A series of cell cytokines or proinflammatory mediators have been detected in knee OA patients. [21][22][23][24][25] Chemokines are a family of small and secreted proteins that play pleiotropic roles in inflammation-related pathological diseases. Chemokines perform in many physiological and pathological process, including those acting in the inflammation process of articular cartilage.…”

Genomic Analysis and Differential Expression of HMG and S100A Family in Human Arthritis: Upregulated Expression of Chemokines, IL-8 and Nitric Oxide by HMGB1

“…T he pathogenesis in osteoarthritis (OA) is observed in the joints, cartilage, and subchondral bone (Haseeb and Haqqi, 2013). Human OA-affected cartilage as compared with normal cartilage is an active site for chondrocyte hypertrophy, angiogenesis and chondrogenesis, inflammation, inflammation resolution, and extracellular matrix repair and remodeling Attur et al, 2002a;Haseeb and Haqqi, 2013).…”