The Free Radical Diseases of Prematurity: From Cellular Mechanisms to Bedside

During the perinatal period, free radicals (FRs) are involved in several physiological roles such as the cellular responses to noxia, the defense against infectious agents, the regulation of cellular signaling function, and the induction of a mitogenic response. However, the overproduction of FRs and the insufficiency of an antioxidant mechanism result in oxidative stress (OS) which represents a deleterious process and an important mediator of damage to the placenta and the developing fetus. After birth, OS can be magnified by other predisposing conditions such as hypoxia, hyperoxia, ischemia, hypoxia ischemia-reperfusion, inflammation, and high levels of nonprotein-bound iron. Newborns are particularly susceptible to OS and oxidative damage due to the increased generation of FRs and the lack of adequate antioxidant protection. This impairment of the oxidative balance has been thought to be the common factor of the so-called "free radical related diseases of prematurity," including retinopathy of prematurity, bronchopulmonary dysplasia, intraventricular hemorrhage, periventricular leukomalacia, necrotizing enterocolitis, kidney damage, and oxidative hemolysis. In this review, we provide an update focused on the factors influencing these diseases refining the knowledge about the role of OS in their pathogenesis and the current evidences of such relationship. Mechanisms governing FR formation and subsequent OS may represent targets for counteracting tissue damage

Oxidative Stress Biomarkers: Establishment of Reference Values for Isoprostanes, AOPP, and NPBI in Cord Blood

Oxidative stress (OS) is a common pathogenic factor involved in the onset of several diseases in humans, from immunologic disorders to malignancy, being a serious public health problem. In perinatal period, OS has been associated with adverse outcome of pregnancy and neonatal diseases. Dangerous effects of OS are mediated by increased production of free radicals (FRs) following various mechanisms, such as hypoxia, ischemia reperfusion, hyperoxia, inflammation, mitochondrial dysfunction, Fenton chemistry, and prostaglandin metabolism. FRs have short half-life, and their measurement in vivo is faced with many challenges. However, oxyradical derivatives are stable and thus may be measured and monitored repeatedly. The quantification of OS is based on the measurement of specific biomarkers in biologic fluids and tissues, which reflect induced oxidative damage to lipids, proteins, and DNA. Prostanoids, non-protein-bound iron (NPBI), and advanced oxidation protein products (AOPP) are actually considered truly specific and reliable for neonatal injury. Defining reference values for these biomarkers is necessary to investigate their role in neonatal diseases or also to evaluate the success of treatments. In this work, we wanted to define laboratory reference values for biomarkers of OS in a healthy population of term newborns

C reactive protein in healthy term newborns during the first 48 hours of life

Background Early-onset neonatal sepsis (EOS) is a serious and potentially life-threatening disease in newborns. C reactive protein (CRP) is the most used laboratory biomarker for the detection of EOS. Little is known about normal reference values of CRP during the perinatal period as several factors are able to influence it. Objectives To identify an appropriate range of CRP values in healthy term newborns during the first 48 hours of life. Design CRP determination was performed in 859 term newborns at 12, 24 and 48 hours of life. Mode of delivery, maternal vaginal culture results, intrapartum antimicrobial prophylaxis (IAP) and other perinatal variables were recorded. Results CRP mean values were significantly higher at 48 hours (4.10 mg/L) than at both 24 (2.30 mg/L) and 12 hours of life (0.80 mg/L). CRP levels were affected by a number of perinatal proinflammatory variables. In particular, CRP mean values were significantly higher in babies born by vaginal delivery (3.80 mg/L) and emergency caesarean section (3.60 mg/L) than in babies born by elective caesarean section (2.10 mg/L). Completed course of IAP led to lower CRP mean values (2.90 mg/L) than IAP not completed (3.80 mg/L) or not performed (4.70 mg/L). Conclusions Postnatal age and mode of delivery significantly influence CRP values. Reliable reference values are crucial in order to obtain an adequate diagnostic accuracy

Serum Albumin Is Inversely Associated With Portal Vein Thrombosis in Cirrhosis

We analyzed whether serum albumin is independently associated with portal vein thrombosis (PVT) in liver cirrhosis (LC) and if a biologic plausibility exists. This study was divided into three parts. In part 1 (retrospective analysis), 753 consecutive patients with LC with ultrasound-detected PVT were retrospectively analyzed. In part 2, 112 patients with LC and 56 matched controls were entered in the cross-sectional study. In part 3, 5 patients with cirrhosis were entered in the in vivo study and 4 healthy subjects (HSs) were entered in the in vitro study to explore if albumin may affect platelet activation by modulating oxidative stress. In the 753 patients with LC, the prevalence of PVT was 16.7%; logistic analysis showed that only age (odds ratio [OR], 1.024; P = 0.012) and serum albumin (OR, -0.422; P = 0.0001) significantly predicted patients with PVT. Analyzing the 112 patients with LC and controls, soluble clusters of differentiation (CD)40-ligand (P = 0.0238), soluble Nox2-derived peptide (sNox2-dp; P < 0.0001), and urinary excretion of isoprostanes (P = 0.0078) were higher in patients with LC. In LC, albumin was correlated with sCD4OL (Spearman's rank correlation coefficient [r(s)], -0.33; P < 0.001), sNox2-dp (r(s), -0.57; P < 0.0001), and urinary excretion of isoprostanes (r(s), -0.48; P < 0.0001) levels. The in vivo study showed a progressive decrease in platelet aggregation, sNox2-dp, and urinary 8-iso prostaglandin F2 alpha-III formation 2 hours and 3 days after albumin infusion. Finally, platelet aggregation, sNox2-dp, and isoprostane formation significantly decreased in platelets from HSs incubated with scalar concentrations of albumin. Conclusion: Low serum albumin in LC is associated with PVT, suggesting that albumin could be a modulator of the hemostatic system through interference with mechanisms regulating platelet activation

Breast milk: To each his own. From metabolomic study, evidence of personalized nutrition in preterm infants

Objectives: The composition of milk from mothers delivering prematurely differs from that of full-term mature milk and changes over time. The aim of this study is to test the hypothesis that changes in milk metabolomic profile from mothers delivering prematurely persist over time when compared with mothers delivering at term. Methods: Nuclear magnetic resonance spectroscopy was used to analyze the metabolome pattern of human milk samples collected from 18 mothers. Twelve mothers collected 12 term milk samples (one for each mother) once between 4 and 7 d after delivery. Six mothers delivering prematurely (29–31 wk of gestational age) collected three samples each, once a week after delivery until the third week after birth. Results: Principal component analysis identified two distinct metabolite groups, one represented by the 18 preterm milk samples and the other by term milk samples. Metabolite profiling identified that lactose and oligosaccharide levels were significantly more represented in preterm than in milk term samples. Conclusions: The preterm milk metabolome pattern undergoes maturation during the first 3 wk after birth, but at the end of the third week it still does not resemble the term milk pattern. The specific changes in mothers’ milk metabolomic profiles according to their offspring might reflect the different nutritional requirement of each preterm infant. This knowledge is crucial to move from standardized nutritional protocols to tailored, individualized nutrition in preterm infants

Identification of a panel of cytokines in neonates with hypoxic ischemic encephalopathy treated with hypothermia

Purpose: Inflammation is a crucial but understudied mechanism of neuronal injury after hypoxia-ischemia. The aim was to identify a panel of cytokines involved in brain injury in neonates with hypoxic ischemic encephalopathy (HIE). Methods: Ten newborns with HIE undergoing to therapeutic hypothermia (TH, HIE Group) and 8 healthy newborns (CTRL Group) were enrolled. For the HIE group, 5 samples were collected: between 0 and 6 h of life (time 1), 12 h (time 2), 24 h (time 3), 48 h (time 4) and 96 h of life (time 5). For the CTRL group, one sample was collected. A panel of 48 inflammatory cytokines was determined in all samples. Data were analyzed using multivariate statistical analysis (Principal component analysis, PCA) Results: 17 cytokines, among 48 analyzed, were found to be significantly different, initially, between the CTRL and HIE groups: 12 with reported pro-inflammatory effects and 5 with reported anti-inflammatory effects. In the HIE group cytokines showed a decreasing trend during the TH and at the end of treatment comparable to the CTRL group. IL-18 did demonstrate a slight increase at time 3 during HT but decreased steadily at sampling times, 4 and 5. Conclusions: Our data demonstrates that many pathways of the inflammatory cascade are activated following hypoxic-ischemic injury. This information will increase our understanding of changes in cytokines over time in neonates with HIE undergoing TH

Regional differences of hypothermia on oxidative stress following hypoxia-ischemia: a study of DHA and hypothermia on brain lipid peroxidation in newborn piglets

Background: Oxidative stress plays an important part in the pathophysiology of hypoxic-ischemic encephalopathy (HIE) and is reliably measured through prostanoids following lipid peroxidation of polyunsaturated fatty acids (PUFAs). The aim of the study is to measure oxidative stress in the prefrontal cortex, white matter and hippocampus in the brains of hypoxic-ischemic piglets treated with docosahexaenoic acid (DHA) and therapeutic hypothermia (TH) and investigate the additive effects of DHA on hypothermia by factorial design. Methods: Fifty-five piglets were randomized as having severe global hypoxia (n=48) or not (sham, n=7). Hypoxic piglets were further randomized: vehicle (VEH), DHA, VEH + hypothermia (HT) or HT + DHA. A total of 5 mg/kg DHA was given intravenously 210 min after the end of hypoxia. Brain tissues were analyzed using liquid chromatography triple quadrupole mass spectrometry technique (LC-MS). A two-way analysis of variance (ANOVA) was performed with DHA and HT as main effects. Results: In the white matter, we found main effects of DHA on DH-isoprostanes (P=0.030) and a main effect of HT on F-4-neuroprostanes (F-4-NeuroPs) (P=0.007), F-2-isoprostanes (F-2-IsoPs) (P=0.043) and DH-isoprostanes (P=0.023). In the cortex, the ANOVA analysis showed the interactions of main effects between DHA and HT for neurofuranes (NeuroFs) (P=0.092) and DH-isoprostanes (P=0.015) as DHA significantly reduced lipid peroxidation in the absence of HT. DHA compared to VEH significantly reduced NeuroFs (P=0.019) and DH-isoprostanes (P=0.010). No differences were found in the hippocampus. Conclusion: After severe hypoxia, HT reduced lipid peroxidation in the white matter but not in the cortical gray matter. HT attenuated the reducing effect of DHA on lipid peroxidation in the cortex. Further studies are needed to determine whether DHA can be an effective add-on therapy for TH

Placental histological examination and the relationship with oxidative stress in preterm infants

Background Prenatal conditions of enhanced oxidative stress (OS) linked to inflammation or hypoxia have been associated with impaired fetal growth and preterm delivery. Little is known regarding biomarkers of OS in the cord blood of preterm infants and placental histological patterns. Objectives To test the hypothesis that placental lesions indicating chorioamnionitis (CA) or vascular underperfusion (VU) are associated with increased OS in the offspring. Methods 120 neonates born below 29+6 weeks of gestational age (GA) were enrolled. Histological characteristics of placentas from their mothers were classified as normal (CTRL group), histological CA (HCA) and vascular underperfusion (VU). Serum concentrations of isoprostanes (IsoPs), non-protein bound iron (NPBI) and advanced oxidative protein products (AOPP), were determined in cord blood. Results IsoPs, NPBI and AOPP were significantly increased in HCA group compared to CTRL group. The multivariable regression model, adjusted for GA, maternal age, parity, maternal diabetes, maternal obesity and presence/absence of fetal growth restriction (FGR), showed a significant association between the presence of HCA and increased OS biomarkers levels in cord blood (IsoPs: p = 0.006; NPBI: p = 0.014; AOPP: p = 0.007). Placental VU lesions were significantly associated with higher umbilical IsoPs, NPBI and AOPP levels (IsoPs: p = 0.008; NPBI: p = 0.002; AOPP: p = 0.040). In the cases of placental VU lesions associations were also found between high AOPP levels and low GA (p = 0.002) and the presence of fetal growth restriction (p = 0.014). Conclusions Placental lesions indicating inflammation or impaired perfusion are associated with higher cord blood levels of OS biomarkers explaining the fetal susceptibility to oxidative injury and the need of antioxidant protection