TNF and rheumatoid arthritis: FLS produces matrix metalloproteinases (MMPs), IL-6,leukotrienes, and prostaglandins, while MLS produces TNF, IL-1, andIL-6, all contributing to RA symptoms.20,21 InfiltratingCD4+ memory T cells and Th1 cells create a pro-inflammatoryenvironment, with TNF-α, IFN-γ, and IL-1β causingcartilage and bone damage.22,23 Ectopic germinal cantersmay form in some patients, producing antibodies like ACPAs and RF,leading to RA development.24 Synovial invasioninto adjacent tissue causes cartilage and bone damage (Figure 2).