Role of tumour necrosis factor alpha in experimental arthritis: separate activity of interleukin 1 beta in chronicity and cartilage destruction

Chronic arthritis is characterised by persistent joint inflammation and con comitant joint destruction. Using murine arthritis models and neutralising antibodies as well as cytokine specific knockout conditions, it was found t hat tumour necrosis factor a (TNF alpha) is important in early joint swelli ng. Membrane bound TNFa is sufficient to drive this aspect of inflammation as well as the acute cellular infiltrate in the synovial tissue. Interleuki n 1 (IL1) is not necessarily a dominant cytokine in early joint swelling, b ut has a pivotal role in sustained cellular infiltration and erosive cartil age damage. TNFa independent IL1 production is a prominent feature in murin e arthritis models. These observations provide evidence for potential uncou pling of joint inflammation and erosive changes, implying that both cytokin es need to be targeted to achieve optimal treatment.