TY - JOUR
T1 - OP-1 - Inflammatory mediators and atmospheric O2 exacerbate antioxidant defenses in endothelial cells
AU - Keeley, Thomas
AU - Mann, Giovanni
PY - 2018/5/20
Y1 - 2018/5/20
N2 - The culture of mammalian cells is routinely conducted under atmospheric O2 levels, far removed from their physiological environment in vivo (PO2 ~3-10 kPa). We have previously demonstrated that culture of cells under normoxia (PO2 5 kPa) attenuates the induction of antioxidant proteins such as heme oxygenase 1 (HO -1). This is due to an upregulation of a repressor protein, Bach1, the expression of which is inversely proportional to cellular PO2. We hypothesise that atmospheric O2 levels constitute an artificial inflammatory environment that primes cells to respond to additional stressors. To address this, we modelled inflammatory conditions under normoxia using treatment with PMA (0.001-1µM) or TNF-α (10 ng/ml), which dose-dependently restored sulforaphane (SFN, 0.5µM)-mediated HO-1 expression. No additional effect of PMA nor TNF-α was observed on SFN-mediated HO-1 expression under atmospheric O2 levels. Treatment with PMA did not influence Bach1 expression. Rather, co-treatment with PMA reduced SFN-mediated induction of GCLC in cells under normoxic conditions which was reflected in intracellular reduced glutathione content. Exposure to atmospheric O2 or inflammation weakens GSH-based defenses and necessitates the induction of alternative antioxidants to combat additional stress.
AB - The culture of mammalian cells is routinely conducted under atmospheric O2 levels, far removed from their physiological environment in vivo (PO2 ~3-10 kPa). We have previously demonstrated that culture of cells under normoxia (PO2 5 kPa) attenuates the induction of antioxidant proteins such as heme oxygenase 1 (HO -1). This is due to an upregulation of a repressor protein, Bach1, the expression of which is inversely proportional to cellular PO2. We hypothesise that atmospheric O2 levels constitute an artificial inflammatory environment that primes cells to respond to additional stressors. To address this, we modelled inflammatory conditions under normoxia using treatment with PMA (0.001-1µM) or TNF-α (10 ng/ml), which dose-dependently restored sulforaphane (SFN, 0.5µM)-mediated HO-1 expression. No additional effect of PMA nor TNF-α was observed on SFN-mediated HO-1 expression under atmospheric O2 levels. Treatment with PMA did not influence Bach1 expression. Rather, co-treatment with PMA reduced SFN-mediated induction of GCLC in cells under normoxic conditions which was reflected in intracellular reduced glutathione content. Exposure to atmospheric O2 or inflammation weakens GSH-based defenses and necessitates the induction of alternative antioxidants to combat additional stress.
U2 - 10.1016/j.freeradbiomed.2018.04.102
DO - 10.1016/j.freeradbiomed.2018.04.102
M3 - Meeting abstract
SN - 0891-5849
VL - 120, Supplement 1
SP - S29
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
ER -