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 utilized real-time RT-PCR to quantify mRNA levels of iNOS and NF-κB. Western blots were used to determine iNOS, NF-κB, IκB-α and phospho-IκB expression levels in normal peritoneal and adhesion fibroblasts in response to hypoxia.Result(s)-Hypoxia resulted in a significant increase in iNOS and NF-κB expression in normal and adhesion fibroblasts. Furthermore, both cell types manifested lower levels of NF-κB, cytoplasmic phospho-IκB-α, and iNOS proteins. In contrast, they manifested higher levels of cytoplasmic IκB-α and IκB-α/NF-κB ratios as well as phosphorylated-IκB-α/NF-κB ratio. Under hypoxic conditions, both cell types exhibited significantly decreased cytoplasmic NF-κB, IκB-α levels, and significantly increased cytoplasmic phospho-IκB-α, iNOS, and NF-κB protein levels.Conclusions-Hypoxia increases iNOS expression by a mechanism involving activation of NF-κB. The ratio of IκB-α/NF-κB or IκB-α/p-IκB-α can be used to monitor activation.