Gene expression profiling at birth characterizing the preterm infant with early onset infection.

Early onset infection (EOI) in preterm infants <32 weeks gestational age (GA) is associated with a high mortality rate and the development of severe acute and long-term complications. The pathophysiology of EOI is not fully understood and clinical and laboratory signs of early onset infections in this patient cohort are often not conclusive. Thus, the aim of this study was to identify signatures characterizing preterm infants with EOI by using genome-wide gene expression (GWGE) analyses from umbilical arterial blood of preterm infants. This prospective cohort study was conducted in preterm infants <32 weeks GA. GWGE analyses using CodeLink human microarrays were performed from umbilical arterial blood of preterm infants with and without EOI. GWGE analyses revealed differential expression of 292 genes in preterm infants with EOI as compared to infants without EOI. Infants with EOI could be further differentiated into two subclasses and were distinguished by the magnitude of the expression of genes involved in both neutrophil and T cell activation. A hallmark activity for both subclasses of EOI was a common suppression of genes involved in natural killer (NK) cell function, which was independent from NK cell numbers. Significant results were recapitulated in an independent validation cohort. Gene expression profiling may enable early and more precise diagnosis of EOI in preterm infants. KEY MESSAGE: Gene expression (GE) profiling at birth characterizes preterm infants with EOI. GE analysis indicates dysregulation of NK cell activity. NK cell activity at birth may be a useful marker to improve early diagnosis of EOI.

Insulin protects cardiomyocytes against reoxygenation-induced hypercontracture by a survival pathway targeting SR Ca2+ storage.

OBJECTIVE: Experimental and clinical studies have shown that administration of insulin during reperfusion is cardioprotective, but the underlying mechanisms are still unknown. In this study, we investigated in isolated rat cardiomyocytes subjected to hypoxia and reoxygenation whether administration of insulin during reoxygenation reduces reoxygenation-induced hypercontracture, a hallmark of acute reperfusion injury. The effects of insulin on potential pro-survival kinases, i.e., PI 3-kinase, NO synthase (eNOS), and cGMP-dependent protein kinase (PKG), and on cytosolic Ca2+ control in reoxygenated cardiomyocytes were investigated. RESULTS: Administration of insulin (10 mU/L) during reoxygenation protected cardiomyocytes against hypercontracture development (cell length as % of end-hypoxic length: control 61.6+/-3.2; insulin 76.3+/-2.9; n=26; p<0.05 vs. control). Cytosolic [Ca2+] recovery during the first 2 min of reoxygenation was accelerated (fura-2 ratio after 2 min of reoxygenation; control 1.01+/-0.05; insulin 0.79+/-0.04; n=26; p<0.05 vs. control). The beneficial effects of insulin on cytosolic [Ca2+] recovery and hypercontracture were suppressed in the presence of inhibitors of PI 3-kinase (LY294002, 1 microM), eNOS (L-NMMA, 100 microM), PKG (KT 5823, 1 microM), or sarcoplasmic reticulum Ca2+ pump (SERCA) (thapsigargin, 150 nM). Insulin increased phosphorylation and activity of eNOS and augmented phospholamban phosphorylation in reoxygenated cardiomyocytes. Correlated with phospholamban phosphorylation, insulin also augmented SR Ca2+ load. CONCLUSIONS: Insulin protects cardiomyocytes against reoxygenation-induced hypercontracture. This is due to acceleration of cytosolic [Ca2+] recovery by enhanced Ca2+ sequestration into the sarcoplasmic reticulum via SERCA activation. This protective mechanism is activated through the survival pathway consisting of PI 3-kinase, eNOS, and PKG.