Mitochondrial antioxidants alleviate oxidative and nitrosative stress in a cellular model of sepsis

Abstract

Purpose: Mitochondrial dysfunction plays a key role in sepsis.

Methods: We used a sepsis model of human endothelial cells (HUVEC) to study mitochondrial function during normoxic (21% O(2)) and hypoxic (1% O(2)) conditions.

Results: When stimulated with a LPS cocktail, HUVEC displayed an increase of nitric oxide (NO) in normoxic and hipoxic conditions, being higher at 21% O(2). LPS-activation for 24 h at 1% O(2) increased ROS production, which was reversed with the mitochondrial antioxidant Mitoquinone (MQ) and Glutathione Ethyl Ester (GEE). Activated cells displayed diminished mitochondrial O(2) consumption with specific inhibition of Complex I, accompanied by increase in tyrosine nitration and Type II NOS protein expression, effects which were recovered by antioxidants and/or with L-NAME. These parameters varied with O(2) environment, namely inhibition of respiration observed in both O(2) environments at 24 h was very similar, whereas O(2) consumption rate fell earlier in 1% O(2)-exposed cells. While no significant differences were detected at earlier time points, at 24 h tyrosine nitration was higher in normoxic vs. hypoxic cells.

Conclusions: Mitochondria are heavily implicated in sepsis. Mitochondrial antioxidants provide a mechanistic model for the development of potential therapies.