Cytokine regulation of cellular adhesion molecule expression in inflammation.

Cellular adhesion molecules (CAMs) play an essential role in tethering circulating leukocytes to the vascular endothelium at sites of inflammation. They are also instrumental in enabling leukocytes to transmigrate from blood vessels into adjacent inflamed tissues. In the absence of signals to stimulate expression of CAMs, the adhesive forces between leukocytes and the vascular endothelium are below the threshold level required to tether leukocytes. Research in the last decade has shown that several cytokines, including tumour necrosis factor alpha (TNF alpha) and interleukin-1 beta (IL-1beta), potently increase the expression of many CAMs and thus increase the adhesiveness between leukocytes and the endothelium. The CAM-inducing activity of these cytokines is therefore crucial to the regulation of inflammatory processes. Overactivation of CAM expression is linked to a number of acute and chronic inflammatory conditions, and has led to the rationale of antagonising cytokine activity and or CAM expression in order to treat these conditions. The potential application of 'adhesion' antagonists for the therapy of acute chronic inflammatory conditions is briefly discussed.