Hypoxia regulates iNOS expression in human normal peritoneal and adhesion fibroblasts through nuclear factor kappa B activation mechanism

Objective: To determine the mechanism by which hypoxia increases expression of iNOS in human normal peritoneal and adhesion fibroblasts. Design: Prospective experimental study. Setting: University medical center. Patient(s): Primary cultures of fibroblasts from normal peritoneum and adhesion tissues. Intervention(S): Hypoxia-treated cells. Main Outcome Measure(s): We used real-time reverse transcription-polymerase chain reaction to quantify mRNA levels of iNOS and nuclear factor kappa B (NF-kappa B). Western blots were used to determine iNOS, NF-kappa B, I kappa KB-alpha, and phospho-I kappa B expression levels in normal peritoneal and adhesion fibroblasts in response to hypoxia. Result(S): Hypoxia resulted in a significant increase in iNOS and NF-kappa B expression in normal and adhesion fibroblasts. Furthermore, both cell types manifested lower levels of NF-kappa B, cytoplasmic phospho-I kappa B-alpha, and iNOS proteins. In contrast, they manifested higher levels of cytoplasmic I kappa B-alpha and I kappa B-alpha/NF-kappa B ratios as well as a phosphorylated-I kappa B-alpha/NF-kappa B ratio. Under hypoxic conditions, both cell types exhibited significantly decreased cytoplasmic NF-kappa B, I kappa B-alpha levels, and significantly increased cytoplasmic phospho-I kappa B-alpha, iNOS, and NF-kappa B protein levels. Conclusion(S): Hypoxia increases iNOS expression by a mechanism involving activation of NF-kappa B. The ratio of I kappa B-alpha/NF-kappa B or I kappa B-Cdp-I kappa B-alpha can be used to monitor activation. (Fertil Steril(R) 2009;91:616-21. (C)2009 by American Society for Reproductive Medicine.)