Oxidative stress and mitochondrial dysfunction in sepsis: a potential therapy with mitochondria-targeted antioxidants

Abstract

Sepsis and septic shock are the major causes of death in intensive care units. The prevalent hypothesis regarding the mechanisms of sepsis and septic shock indicates that this syndrome is caused by an excessive defensive and inflammatory response characterised by massive increases in reactive oxygen species (ROS), nitric oxide (NO) and inflammatory cytokines. The consequences of these syndromes are systemic damage to the vascular endothelium, impaired tissue and a compromised whole body respiration, glutathione depletion and mitochondrial respiratory dysfunction with diminished levels of ATP and O(2) consumption. In general, ROS are essential to the functions of cells and particularly immune cells, but adequate levels of antioxidant defenses are required to protect against the harmful effects of excessive ROS production. Mitochondrial oxidative stress damage and dysfunction contribute to a number of cell pathologies that manifest themselves in a range of conditions, including sepsis. This review considers the process of sepsis from a mitochondrial perspective, discussing strategies for the targeted delivery of antioxidants to mitochondria currently under development. We will provide a summary of the following areas: the cellular metabolism of ROS and its role in pathophysiological processes such as sepsis; currently available antioxidants and possible reasons for their efficacy and inefficacy in ameliorating oxidative stress-mediated diseases; and recent developments in antioxidants that target the matrix-facing surface of the inner mitochondrial membrane in order to protect against mitochondrial oxidative damage, and their therapeutic potential as a treatment for sepsis.