IL8CXCL8

IL8CXCL8, commonly referred to as interleukin-8 (IL-8) or CXCL8, is a chemokine belonging to the CXC chemokine family. In humans, IL-8 is a secreted cytokine that acts as a potent chemoattractant for neutrophils and plays a central role in the inflammatory response. The IL8 gene encodes the precursor protein, which is processed to a mature 72-amino-acid chemokine that contains an N-terminal ELR motif essential for neutrophil chemotaxis and activation. IL-8 signals through two G protein-coupled receptors, CXCR1 (IL-8RA) and CXCR2 (IL-8RB). Binding to these receptors triggers calcium mobilization and downstream signaling pathways that promote chemotaxis, degranulation, and respiratory burst of neutrophils.

IL-8 expression is rapidly upregulated in response to inflammatory stimuli such as bacterial lipopolysaccharide (LPS), interleukin-1β, and tumor necrosis factor-α, often via transcription factors NF-κB and AP-1. Producing cells include monocytes/macrophages, epithelial cells, endothelial cells, and fibroblasts, among others. IL-8 also participates in angiogenesis under certain conditions and can influence other leukocytes.

Clinically, elevated IL-8 levels are observed in various infections and inflammatory diseases, including sepsis, chronic obstructive pulmonary disease, cystic fibrosis, and inflammatory bowel disease. Genetic polymorphisms in the IL8 promoter or regulatory regions can affect expression and have been studied in relation to disease susceptibility and prognosis. In mice, a direct IL-8 homolog is absent; instead, functional analogs such as CXCL1 and CXCL2 fulfill similar roles, which has implications for translational research and model selection.