The effect of acute hyperoxia in vivo on NF kappa B expression in human PBMC.

The mechanisms of hyperbaric oxygen (HBO) therapy have not been fully elucidated. It is presumed that breathing 100% oxygen at pressure generates free radicals and the cellular response to these may confer protection. A crucial signalling molecule, nuclear transcription factor kappa B (NFκB), translocates from the cytoplasm to the nucleus and activates a raft of pathways in response to various stimuli, and plays a role in inflammatory processes. This study focussed upon the expression of NFκB in isolated human peripheral blood mononuclear cells (PBMC) following HBO. Ten healthy male volunteers underwent a single HBO treatment, breathing 100% oxygen at a pressure of 2.8 ATA for 1 h. EDTA blood samples were taken pre-, post- and 4-h post-HBO. PBMC were isolated, nuclear extracts prepared and assayed using a NFkBp50 transcription factor ELISA. Mean NFκB expression of 0.27 (0.20-0.34, 95%CI) absorbance units (mg protein)(-1) was observed pre-HBO and this increased to 0.29 (0.20-0.38, 95%CI) immediately post-HBO. A significant increase in NFκB expression within PBMC was observed 4-h post-HBO, in comparison to pre-HBO (mean 0.38, 0.30-0.47, 95%CI, p = 0.027). This study demonstrates that HBO induces NFκB activation in human PBMC, which could be a crucial step in the mechanism of HBO treatment.