Rôle de la dysfonction endothéliale dans la mortalité liée au sepsis

Novel relationships between oxidative stress and angiogenesis-related factors in sepsis: New biomarkers and therapies

Sepsis is a systemic uncontrolled inflammatory response in the presence of an infection. It remains a major cause of morbidity and mortality in hospitalized patients. According to its severity, sepsis can progress to three different states: severe sepsis, septic shock, and multiple organ dysfunction syndrome, related to organ dysfunction and/or tissue hypoperfusion. Different processes underlie its pathophysiology; among them are oxidative stress, endothelial and mitochondrial dysfunction, and angiogenesis-related factors. However, no studies have integrated these elements in sepsis. The main difficulty in sepsis is its diagnosis. Currently, the potential of inflammatory biomarkers in septic patients remains weak. In this context, the research into new biomarkers is essential to aid with sepsis diagnosis and prognostication. Furthermore, even though the current management of severe forms of sepsis has been effective, morbimortality remains elevated. Therefore, it is essential to explore alternative approaches to therapy development. The aim of this review is to present an update of evidence supporting the role of oxidative stress and angiogenesis-related factors in the pathophysiology of the different forms of sepsis. It proposes a novel convergence between both elements in their role in the disease, and it will cover their utility as new diagnostic tools, predictors of outcome, and as novel therapeutic targets.

Oxidative stress as a novel target in pediatric sepsis management

Sepsis with secondary multisystem organ dysfunction syndrome is the leading cause of death in the pediatric intensive care unit. Increased reactive oxygen species may influence circulating and endothelial cells, contributing to inflammatory tissue injury and explaining the tissue hypoxia paradigm based on microvascular dysfunction. An impaired mitochondrial cellular oxygen utilization, rather than inadequate oxygen delivery, was claimed to play a more important role in the development of multisystem organ dysfunction syndrome. Anyway, it seems plausible that reactive oxygen species can mediate the pathophysiologic processes occurring in sepsis. However, the consensus guidelines for the management of patients with these conditions do not include the enhancement of antioxidant potential. Therefore, further investigation is needed to support interventions aimed to attenuate the severity of the systemic compromise by abrogating the mechanism of oxidative damage. Antioxidant supplementation currently in use lacks a mechanistic support. Specific pharmacologic targets, such as mitochondria or Nicotinamide Adenine Dinucleotide Phosphate-Oxidase (NADPH) oxidase system, need to be explored. Furthermore, the early recognition of oxidative damage in these seriously ill patients and the usefulness of oxidative stress biomarkers to define a cut point for more successful therapeutic antioxidant interventions to be instituted would offer a new strategy to improve the outcome of critically ill children.

[Microparticles during sepsis and trauma. A link between inflammation and thrombotic processes]

Sepsis and trauma lead to a sustained activation of monocytes and endothelium. In the vascular compartment, stimulated cells release microparticles. Circulating MP provide an additional procoagulant phospholipid surface enabling the assembly of the clotting enzymes complexes and thrombin generation. Their procoagulant properties rely on the exposition of phosphatidylserine, made accessible after cell stimulation and on the possible presence of tissue factor, the main cellular initiator of blood coagulation. Microparticles constitute the main reservoir of blood-borne tissue factor activity. At sites of endothelium injury, enhanced release or recruitment of procoagulant MP through P-selectin-PSGL-1 pathway could concentrate TF activity above a threshold allowing blood coagulation to be triggered. Converging evidences from experimental or clinical data highlight a role for MP harboring tissue factor in the initiation of disseminated intravascular coagulopathy. In these settings, the pharmacological modulation of MP levels or biological functions through activated protein C or factor VIIa allows challenging issues.