Transcriptional regulation of IL-8 by C/EBP and NF-κB in human primary myocytes

Abstract

Interleukin-8 (IL-8) is a chemotactic cytokine present in uterine tissues that plays a key role in neutrophil recruitment in the cervix and myometrium. The promoter region of the IL-8 gene contains functional binding sites for NF-κB transcription factor and CCAAT/enhancer-binding protein (C/EBP). We aimed to determine whether an interaction between NF-κB and C/EBP determines IL-8 promoter activity, as applies for the oxytocin receptor. Primary human myocyte cell cultures were established from myometrial biopsies taken at elective caesarean section at term. Transfection studies were performed with two different IL-8 promoter constructs (short 135 ± 46 bp and long 1.6 kb±46 bp). Promoter activity of the short promoter is sixfold higher than the long (P < 0.02). Overexpression of C/EBPβ or NF-κBp65 increased the activity of both IL-8 promoter constructs 2–3-fold (P < 0.05; n = 3). Co-transfection of both C/EBPβ and NF-κB expression factors together resulted in a synergistic transactivation of the short IL-8 promoter activity (sixfold induction; P < 0.001; n = 3) but had no further effect upon the long promoter.