Potential role of hydrogen sulfide in the pathogenesis of vascular dysfunction in septic shock

Various forms of circulatory shock (including septic shock) lead to an impairment of vascular function, which importantly contributes to the development of multiple organ failure and mortality. Such dysfunction of blood vessels consists of two principal components: vascular smooth muscle (VSM) dysfunction, and endothelial dysfunction. The VSM dysfunction (progressive, therapy-resistant loss of VSM responsiveness to vasoconstrictor catecholamines, such as noradrenaline) leads to a progressive deterioration of blood pressure in patients with circulatory shock. The endothelial dysfunction (loss of the ability of the endothelium to produce nitric oxide and other endothelium-derived factors) contributes to the impairment of microvascular blood flow, to the enhanced adhesion and activation of neutrophils and platelets, to coagulation problems, and perfusion/metabolism mismatch in the affected organs. Here we overview the vascular regulatory functions of the novel gasotransmitter hydrogen sulfide (H2S), with an emphasis on its potential role in the pathogenesis of vascular dysfunction in circulatory shock. We first review the roles of endogenously produced or exogenously administered H2S on vascular function. Next, we review the results of published studies using shock models induced by bacterial lipopolysaccharide, and by cecal ligation and puncture, a polymicrobial model of sepsis showing overproduction of H2S. Finally, we summarize the potential mechanisms by which H2S may contribute to vascular dysfunction in shock and show an example of how the vascular response to H2S is altered in a rat model of endotoxemia. In addition, we outline the potential means by which modulation of H2S (pharmacological inhibition of its biosynthesis or therapeutic donation) may affect the outcome in circulatory shock.