[The study on the interleukin-8 (IL-8)]

Abstract

Interleukin-8 (IL-8), which is a member of C-X-C chemokine subfamily, is an important activator and chemoattractant for neutrophils and has been implicated in a variety of inflammatory diseases. Numerous reports show that various cells express IL-8 mRNA and produce IL-8 protein rapidly, including monocytes, T lymphocytes, neutrophils, fibroblasts, endothelial cells and epithelial cells. The human IL-8 gene has a length of 5191 bp and contains four exons separated by three introns. It maps to human chromosome 4q12-q21. The mRNA consists of a 101 bases 5' untranslated region, an open reading frame of 297 bases, and a long 3' untranslated region of 1.2 kb. The 5' flanking region of the IL-8 gene contains potential binding sites for several nuclear factors including activated protein-1 (AP-1), activated protein-2 (AP-2), nuclear factor-gene binding (NF-kappa B), nuclear factor-interleukin-6 (NF-IL-6, also calls CAAT/enhancer-binding proteins, C/EBP), IFN regulatory factor-1 (IRF-1), hepatocyte nuclear factor-1 (HNF-1), and so on. IL-8 gene expression is regulated initially at the level of gene transcription. The rapid induction of IL-8 gene expression is likely mediated by latent transcription factors that bind the IL-8 promoter. AP-1 and NF-IL-6 physically interact with NF-kappa B, and functional cooperativity among these factors appears to be critical for optimal IL-8 promoter activity in different cell types. The IL-8 receptor (IL-8R) is a dimeric glycoprotein consisting of a 59 KDa and a 67 KDa subunit. It has been given the name CDw128. It is expressed in many different cell types including those not responding to IL-8. The receptor density is approximately 20,000/cell in neutrophils, 1,040/cell in monocytes, and 300/cell in T-lymphocytes. The IL-8R is a member of the family of G-protein-coupled receptors. There are at least two different IL-8 receptor types (CXCR1 and CXCR2). The activities of IL-8 are not species-specific. IL-8 affects the adhesion of neutrophils to the endothelium and induces the transendothelial migration of neutrophils. IL-8 also exhibits in vitro chemotactic activities against of T-lymphocytes and basophils. IL-8 gene expression can be regulated by fluid shear stress, which may play an important role in the genesis and development of both inflammation and arterosclerosis.