Fig. 2

Pathophysiology of Rheumatoid Arthritis. A Genetic variants and environmental factors illustrated in the image cause several reactions eventually that promote loss of self-tolerance and subsequently, the inflammatory response of innate, adaptive, and stromal cells causes swelling, cartilage, and bone erosion in certain parts of the human body. B Antigen presentation stimulates naive T-cells, especially Th1 cells, and starts an immune response. Subsequently, macrophage activity increases in the synovial joint, which raises the production of pro-inflammatory cytokines such as TNF-α and IL1. These cytokines affect fibroblasts, osteoclasts, and chondrocytes. Matrix-metalloproteinase (MMP) and other collagen-degrading enzymes are released by chondrocytes. Furthermore, T-cells activate plasma cells and B-cells, which lead to secrete a variety of auto-antibodies. These auto-antibodies can attach to APCs and result in pannus formation and subsequent cartilage degradation. (The figure Created by biorender.com)