New insight from the interplay between nitric oxide and glucocorticoids*

Concomitant administration of nitric oxide and glucocorticoids improves protection against bronchoconstriction in a murine model of asthma

Glucocorticoids (GC) remain the first choice of treatment in asthma, but GC therapy is not always effective and is associated with side effects. In a porcine study in our laboratory, simultaneous administration of GC and nitric oxide (NO) attenuated the endotoxin-induced inflammatory response and made GC treatment more effective than inhaled NO or steroids alone. In the present study, we aimed to further investigate the interactions between NO and GC treatment in two murine models of asthma. Inflammation was induced by endotoxin, ovalbumin, or a combination of both. With an animal ventilator and a forced oscillation method (FlexiVent), lung mechanics and airway reactivity to methacholine in response to various treatments were assessed. We also describe histology and glucocorticoid receptor (GR) protein expression in response to inhaled NO treatment [40 ppm NO gas or NO donors sodium nitroprusside (SNP) or diethylamine NONOate (DEA/NO)]. SNP and GC provided protection against bronchoconstriction to a similar degree in the model of severe asthma. When GC-treated mice were given SNP, maximum airway reactivity was further reduced. Similar effects were seen after DEA/NO delivery to GC-treated animals. Using 1-H-[1,2,4]-oxadiazolo-[4,3-a]-quinoxalin-1-one (ODQ), a soluble guanylate cyclase inhibitor, we found this effect of NO donors to be mediated through a cGMP-independent mechanism. In the severe model, prolonged NO treatment restored or even increased the nuclear levels of GR. In conclusion, in our murine model of severe asthma GC treatment provided protection to only a limited degree against bronchoconstriction, while concomitant treatment with a NO donor was markedly more potent than the use of either NO or GC alone.

Adrenal insufficiency in pediatric critical illness: controversies regarding its prevalence, pathogenesis, definition and management

Proper functioning of the hypothalamic–pituitary–adrenal axis is necessary for normal homeostasis in children and especially under conditions of stress, such as critical illness. Disturbances of this axis have been classified collectively under the heading of adrenal insufficiency. Although the majority of literature has focused on children with septic shock, more recent evidence suggests that adrenal insufficiency occurs in a much broader group of critically ill children. Its etiology in pediatric critical illness remains unclear but is most likely multifactorial. Several studies have suggested possible diagnostic criteria for adrenal insufficiency in pediatric critical illness; however, to date none of these biochemical definitions have been validated. Similarly, current management of this condition in children remains based primarily on an empiric, best-practice approach. Future large-scale studies are needed to elucidate the prevalence, pathogenesis, definition, diagnosis and management of this condition.