Revision as of 15:21, 20 October 2020

Interleukin 8

Usage and Biology

Interleukin 8 is a chemokine produced by macrophages and other cell types such as epithelial cells, airway smooth muscle cells and endothelial cells. Endothelial cells store IL-8 in their storage vesicles, the Weibel-Palade bodies. In humans, the interleukin-8 protein is encoded by the CXCL8 gene. IL-8 is initially produced as a precursor peptide of 99 amino acids which then undergoes cleavage to create several active IL-8 isoforms. In culture, a 72 amino acid peptide is the major form secreted by macrophages.

There are many receptors on the surface membrane capable of binding IL-8; the most frequently studied types are the G protein-coupled serpentine receptors CXCR1 and CXCR2. Expression and affinity for IL-8 differs between the two receptors (CXCR1 > CXCR2). Through a chain of biochemical reactions, IL-8 is secreted and is an important mediator of the immune reaction in the innate immune system response.

IL-8 can be secreted by any cells with toll-like receptors that are involved in the innate immune response. Usually, it is the macrophages that see an antigen first, and thus are the first cells to release IL-8 to recruit other cells. Both monomer and homodimer forms of IL-8 have been reported to be potent inducers of the chemokine receptors CXCR1 and CXCR2. The homodimer is more potent, but methylation of Leu25 can block the activity of homodimers.

Sequence and Features

Sequence and Features

MIT MAHE 2020

Summary

Interleukin-8 (IL-8) is a cytokine unique in its property of target specificity towards neutrophils, with only weak effects on other blood cells. It is produced by various tissues and blood cells. In the inflammatory region, it attracts and activates neutrophils which responds by migration of the cells, the release of granule enzymes, and other intra- and extracellular changes. IL-8 is a member of the Interleukin-8 supergene family that includes other small chemotactic peptides with structural homology.

References

1. Bickel M. (1993). The role of interleukin-8 in inflammation and mechanisms of regulation. Journal of periodontology, 64(5 Suppl), 456–460.