Ambient O2 pressure induces NF-kB1/RelA related inflammatory response in human lung epithelial cells in vitro

Purpose: Oxygen (O2) levels in cell culture conditions is typically 2-5 fold higher than the physiological O2 levels that most tissues experience in vivo. The ambient atmospheric O2 (21%) is known to induce cell proliferation defects and cellular senescence in stem cell and primary cell cultures. Therefore, culturing these cells under lower O2 levels (2-9%) is currently a standard practice. However, the non-cancerous immortalized cells and cancer cells, which evade cellular senescence are normally cultured under 21% O2 levels and the effects of higher O2 levels on these cells are not fully understood.Methods: Gene expression (RNA seq transcriptomics) analysis of immortalized human bronchial epithelial (BEAS-2B) cells cultured at ambient 21% O2 and lower 10% O2 levels for 3 days and 3 weeks. Further the beneficial effects of cuturing cells under lower oxygen tension is evalulatedResults: Our results show NF-κB/RelA mediated activation of pro-inflammatory cytokines as a major outcome of cells being cultured 21% O2. Moreover, we demonstrate increased RelA binding at the NF-κB1/RelA target gene promoters at 21% O2. Interestingly, contrary to cells cultutred at 21% O2, external stress induced by H2O2 exposure did not induce inflammatory response in cells grown at 10% O2, suggesting increased ability to handle external stress in cells cultured at lower O2 levels.