Sex differences in neonatal brain injury and inflammation.

Neonatal brain injury and associated inflammation is more common in males. There is a well-recognised difference in incidence and outcome of neonatal encephalopathy according to sex with a pronounced male disadvantage. Neurodevelopmental differences manifest from an early age in infancy with females having a lower incidence of developmental delay and learning difficulties in comparison with males and male sex has consistently been identified as a risk factor for cerebral palsy in epidemiological studies. Important neurobiological differences exist between the sexes with respect to neuronal injury which are especially pronounced in preterm neonates. There are many potential reasons for these sex differences including genetic, immunological and hormonal differences but there are limited studies of neonatal immune response. Animal models with induced neonatal hypoxia have shown various sex differences including an upregulated immune response and increased microglial activation in males. Male sex is recognized to be a risk factor for neonatal hypoxic ischemic encephalopathy (HIE) during the perinatal period and this review discusses in detail the sex differences in brain injury in preterm and term neonates and some of the potential new therapies with possible sex affects.

Melatonin Alters Innate Immune Function in Infants with Neonatal Encephalopathy.

INTRODUCTION: Melatonin has been suggested an adjunctive therapy in neonatal encephalopathy (NE). Melatonin reduces oxidative stress and neutrophil activation; however, the immunological effects in NE have not been studied. METHODS: Infants with NE and neonatal controls were prospectively recruited. Whole blood was sampled in the first week of life. Following endotoxin and or melatonin treatment, diurnal variation was measured by RT PCR for circadian rhythm genes (brain and Muscle Arnt-Like protein [BMAL1], circadian locomotor output cycles kaput [CLOCK], Nuclear Receptor Subfamily 1 Group D Member 2 [REV Erß], and cryptochrome circadian clock [CRY]). Neutrophil and monocyte cell surface markers of activation CD11b, reactive oxygen intermediates (ROIs), and Toll-like receptor (TLR)-4 were also examined by flow cytometry in matching samples. RESULTS: Serum and RNA samples from forty infants were included (controls n = 20; NE n = 20) over the first week of life. Melatonin reduced neutrophil CD11b and TLR-4 expression in response to LPS in infants with NE compared to controls. There were no differences in ROIs. BMAL1 and CLOCK baseline gene expression levels were similar. BMAL1 was significantly decreased with LPS stimulation in NE. There was no significant diurnal variation in melatonin, neutrophil, and monocyte function or circadian genes. CONCLUSIONS: Melatonin alters immune function ex vivo in infants with NE. Infants with NE have altered immune circadian responses following LPS stimulation, which have potential for modulation.

Selective modulation of monocyte and neutrophil responses with activated protein C in preterm infants.

BACKGROUND: Inflammation is associated with many disorders of preterm infants including periventricular leukomalacia, chronic lung disease, and necrotizing enterocolitis. Activated protein c (APC) has shown positive immunomodulatory effects. OBJECTIVES: We aimed to study neutrophil and monocyte function in response to lipopolysaccharide (LPS) and APC stimulation ex vivo in preterm infants <32 weeks gestation over the first week of life compared to neonatal and adult controls. METHODS: Peripheral blood was taken on day 1, 3, and 7 and stimulated with LPS in the absence or presence of APC. Expression of toll-like receptor 4 (TLR4) and CD11b and reactive oxygen intermediate (ROI) release from neutrophils and monocytes was examined by flow cytometry. RESULTS: LPS induced neutrophil ROI in adults and preterm infants and was significantly reduced by APC. Baseline and LPS-induced monocyte ROI production in preterm neonates was increased compared to adult and term controls. Neutrophil TLR4 baseline expression was higher in term controls compared to preterm infants. CONCLUSION: Increased systemic ROI release in preterm infants may mediate tissue damage, ROI was reduced by APC. However, due to the high risk of hemorrhage further examination of APC mutant forms with anti-inflammatory but decreased anticoagulant properties is merited.

Altered Cytokine Endotoxin Responses in Neonatal Encephalopathy Predict MRI Outcomes.

Background: Neonatal encephalopathy (NE) is associated with adverse neurodevelopmental outcome and is linked with systemic inflammation. Pro-inflammatory and anti-inflammatory cytokines are known to play a role in the pathology of NE by activating innate immune cells. Methods: Eighty-seven infants were enrolled including 53 infants with NE of whom 52 received therapeutic hypothermia (TH) and 34 term infant healthy controls (TC). Whole blood sampling was performed in the first 4 days of life, and a 14-spot ELISA Multiplex Cytokine Array was carried out on baseline samples or after stimulation with lipopolysaccharide (LPS) as an additional inflammatory stimulus. The cytokine medians were examined for differences between infants with NE and healthy TC; and then short-term outcomes of Sarnat stage, seizures, and MRI brain were examined within the NE group. The potential of LPS stimulation to predict abnormal MRI was explored using receiver operating characteristic (ROC) curves. Results: At baseline, infants with NE had significantly higher levels of erythropoietin (Epo), interleukin (IL)-6, and IL-1ra and significantly lower vascular endothelial growth factor (VEGF) than had controls. All cytokines were increased after LPS stimulation in infants with NE with an excessive Epo and IL-1ra response than in controls. Infants with NE had lower IL-8, IL-2, IL-6, tumor necrosis factor (TNF)-α, granulocyte-macrophage colony-stimulating factor (GM-CSF), VEGF, and interferon (IFN)-γ than controls had following LPS. GM-CSF and IFN-γ, IL-1ß, IL-1ra, and VEGF were higher on days 1-2 in NE infants with abnormal neuroimaging. GM-CSF, IFN-γ, and TNF-α levels with LPS stimulation were different upon stimulation between normal and abnormal neuroimaging. TNF-α is the only strong cytokine predictor both pre- and post-LPS stimulation of abnormal brain imaging. Conclusions: Altered cytokine responses are found in infants with NE vs. controls, and more significant differences are unmasked by the additional stimulus of LPS, which potentially improves the predictive power of these cytokines for the detection of abnormal MRIs. Infants with NE undergoing TH demonstrate both trained immunity and tolerance, and understanding these responses will facilitate adjunctive immunomodulatory treatments.

Neutrophils: Need for Standardized Nomenclature.

Neutrophils are the most abundant innate immune cell with critical anti-microbial functions. Since the discovery of granulocytes at the end of the nineteenth century, the cells have been given many names including phagocytes, polymorphonuclear neutrophils (PMN), granulocytic myeloid derived suppressor cells (G-MDSC), low density neutrophils (LDN) and tumor associated neutrophils (TANS). This lack of standardized nomenclature for neutrophils suggest that biologically distinct populations of neutrophils exist, particularly in disease, when in fact these may simply be a manifestation of the plasticity of the neutrophil as opposed to unique populations. In this review, we profile the surface markers and granule expression of each stage of granulopoiesis to offer insight into how each stage of maturity may be identified. We also highlight the remarkable surface marker expression profiles between the supposed neutrophil populations.

Altered distributions and functions of natural killer T cells and γδ T cells in neonates with neonatal encephalopathy, in school-age children at follow-up, and in children with cerebral palsy.

We enumerated conventional and innate lymphocyte populations in neonates with neonatal encephalopathy (NE), school-age children post-NE, children with cerebral palsy and age-matched controls. Using flow cytometry, we demonstrate alterations in circulating T, B and natural killer cell numbers. Invariant natural killer T cell and Vδ2+ γδ T cell numbers and frequencies were strikingly higher in neonates with NE, children post-NE and children with cerebral palsy compared to age-matched controls, whereas mucosal-associated invariant T cells and Vδ1 T cells were depleted from children with cerebral palsy. Upon stimulation ex vivo, T cells, natural killer cells and Vδ2 T cells from neonates with NE more readily produced inflammatory cytokines than their counterparts from healthy neonates, suggesting that they were previously primed or activated. Thus, innate and conventional lymphocytes are numerically and functionally altered in neonates with NE and these changes may persist into school-age.

An observational study of sleep in childhood post-neonatal encephalopathy.

AIM: Neonatal encephalopathy (NE) is associated with altered cognitive, motor, sensory abilities and behavioural outcomes. This case-control study aimed to assess whether Quality of Life (QoL) and sleep disorders are affected in older children following NE compared to age-matched controls. METHODS: Children at school-age post-NE were recruited and compared to age-matched controls. Sleep and QoL were assessed with the Pediatric Quality of Life Inventory and the Child Sleep Habit Questionnaire. RESULTS: One hundred children were recruited with an age range of 4-6 years, including children post-NE (n=45) and age-matched controls (n = 55). Significantly higher pathological sleep scores were evident in 58% of children post-NE compared to controls (43.8 vs 40.2; p = 0.001). Children post-NE had increased bedtime resistance (p = 0.028) and sleep anxiety (p = 0.01) compared to controls. Children in the post-NE group had lower total QoL scores versus controls (mean score 82.5 vs 95.8; p < 0.01). Children with mild NE also had lower total QoL scores than controls (90.0 vs 95.8, p = 0.003). There was a strong correlation between low QoL with high total sleep scores (Rho 0.339, p = 0.014). CONCLUSION: There were high rates of sleep issues in school-aged children with mild and moderate-severe NE. Consideration and management of sleep problems may improve QoL in childhood post-NE.

Protein C Pathway in Paediatric and Neonatal Sepsis.

Protein C plays a major role in the physiological regulation of coagulation pathways through inactivation of factor Va, factor VIIIa, and plasminogen activator inhibitor. Protein C is involved in the control of inflammation during sepsis, by inhibiting release of pro-inflammatory cytokines, thereby controlling neutrophil, and monocyte effects on injured tissue. Recombinant human activated protein C (rhAPC) reduced mortality in adult sepsis in earlier studies but had no significant benefit in more recent trials. Protein C levels are reduced during paediatric and neonatal sepsis, which may play a major role in the development of disseminated intravascular thrombosis, purpura fulminans, and multiorgan dysfunction. The role of protein C in paediatric sepsis requires further clinical and immunological evaluation to define the patient subgroups who may benefit from this therapy. Newer versions of rhAPC are under development with less risk of haemorrhage potentially broadening the scope of this intervention.

Cytokine dysregulation persists in childhood post Neonatal Encephalopathy.

BACKGROUND: Cytokines are possible mediators of neuroinflammation and associated with adverse outcome in neonatal encephalopathy (NE). Our aim was to explore cytokine response in children with Neonatal Encephalopathy (NE) at school age compared to age-matched controls. METHOD: Follow up at school age, children who had NE and age-matched controls were assessed for their cytokine responses and neurodevelopment outcome. Pro- and anti-inflammatory cytokines in the serum, [Interleukin (IL)-1α, IL-1ß, IL-2, IL-6, IL-8, IL-18, Tumor necrosis factor (TNF)-α, TNF ß, Interferon (IFN)-γ, granulocyte-macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF), erythropoietin (EPO), IL-10 & IL-1RA] were measured at baseline and in response to in vitro stimulation with lipopolysaccharide (LPS: endotoxin). RESULTS: GM-CSF, TNF-ß, IL-2 IL-6 and IL-8 were significantly elevated at school age following NE (n = 40) compared to controls (n = 37). A rise in GM-CSF, IL-8, TNF-α, IL-1ß, & IL-6 were seen in NE group following LPS stimulation. Relative LPS hypo-responsiveness was also noted in children with severe NE with IL-10, VEGF, EPO and TNF-ß. Elevated TNF-ß was associated with low gross motor scores on assessment at school age. CONCLUSION: School-age children post-NE had significantly altered cytokine responses to endotoxin compared to controls. TNF-ß was associated with adverse developmental outcomes. This suggests the inflammatory process may persist into childhood and a longer therapeutic window may be available for neuroprotection therapies.

Neonatal Encephalopathy Is Associated With Altered IL-8 and GM-CSF Which Correlates With Outcomes.

Aim: To investigate the relationship between cytokines associated with innate immune cell activation and brain injury and outcome in infants with NE compared to neonatal controls. Methods: Serum and CSF biomarkers associated with activated neutrophils and monocytes [Interleukin-8 (IL-8) and Granulocyte-Macrophage-Colony-Stimulating-Factor (GM-CSF)] were serially measured using duplex immunoassays on days 1, 3 and 7 in term newborns with NE and controls. Results were compared to grade of encephalopathy, seizures, MRI brain imaging, mortality and Bayley Score of Infant and Toddler Development (Bayley-III) at 2 years of age. Results: Ninety-four infants had serum samples collected with 34 CSF samples. NE Grade II/III was significantly associated with elevated on day 2 serum IL-8. Mortality was best predicted by elevated day 1 IL-8. GM-CSF was initially elevated on day 1 and abnormal MRI imaging was associated with decreased day 2 GM-CSF. Elevated GM-CSF at day of life 6-7 correlated negatively with composite cognitive, language and motor Bayley-III scores at 2 years. Conclusion: Moderate or severe NE and mortality was associated with elevated IL-8. Day 2 GM-CSF could predict abnormal MRI results in NE and Bayley-III. Therefore, these cytokines are altered in NE and may predict early outcomes and further implicate inflammatory processes in NE.

Coagulation Profiles Are Associated With Early Clinical Outcomes in Neonatal Encephalopathy.

Introduction: Neonatal encephalopathy (NE) is associated with coagulation abnormalities. We aimed to investigate the serial alterations in coagulation profiles in term infants with NE and correlate with their clinical outcomes. This was a prospective cohort study in a tertiary referral, university-affiliated maternity hospital. Neonates exposed to perinatal asphyxia were recruited (n = 82) and 39 received therapeutic hypothermia. Infants had serial coagulation tests including platelets, prothrombin time (PT), activated partial thromboplastin time (aPTT) and fibrinogen in the first week of life. The main outcome measures included MRI brain and EEG seizures. Our results show that mortality was predicted on day 1 by decreased Fibrinogen (AUC = 0.95, p = 0.009) and by PT on day 2 with a cutoff of 22 s. An abnormal MRI was predicted by Fibrinogen on day 3 with a cut-off value of 2 g/L. For prediction of grade II/III NE, PT on day 2 of life was strongest with a cut-off value of 14 s. Only elevated APTT levels on day 1 of life were predictive of seizures (AUC = 0.65, p = 0.04). Conclusion: Coagulation parameters are strong predictors of outcomes such as abnormal NE grade, seizures, and mortality.

Phytoestrogens Activate the Estrogen Receptor in HepG2 Cells.

Phytoestrogens are popular alternatives to estrogen therapy however their effects on hemostasis in postmenopausal women are unknown. This chapter describes a protocol to determine the effect of the phytoestrogens genistein, daidzein and equol, on the expression of key genes from the hemostatic system in human hepatocyte cell models and to determine the role of estrogen receptors in mediating any response seen using in vitro culture systems and Taqman(®) gene expression analysis.

Estrogen receptor alpha augments changes in hemostatic gene expression in HepG2 cells treated with estradiol and phytoestrogens.

Phytoestrogens are popular alternatives to estrogen therapy however their effects on hemostasis in post-menopausal women are unknown. The aim of this study was to determine the effect of the phytoestrogens, genistein, daidzein and equol on the expression of key genes from the hemostatic system in human hepatocyte cell models and to determine the role of estrogen receptors in mediating any response seen. HepG2 cells and Hep89 cells (expressing estrogen receptor alpha (ERα)) were incubated for 24 h with 50 nM 17ß-estradiol, genistein, daidzein or equol. Tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), Factor VII, fibrinogen γ, protein C and protein S mRNA expression were determined using TaqMan PCR. Genistein and equol increased tPA and PAI-1 expression in Hep89 cells with fold changes greater than those observed for estradiol. In HepG2 cells (which do not express ERα), PAI-1 and tPA expression were unchanged. Increased expression of Factor VII was observed in phytoestrogen treated Hep89 cells but not in similarly treated HepG2s. Prothrombin gene expression was increased in equol and daidzein treated HepG2 cells in the absence of the classical estrogen receptors. These data suggest that phytoestrogens can regulate the expression of coagulation and fibrinolytic genes in a human hepatocyte cell line; an effect which is augmented by ERα.

Genistein alters coagulation gene expression in ovariectomised rats treated with phytoestrogens.

Recent data has shown that hormone therapy (HT) increases the risk of cardiovascular and thromboembolic disease, particularly in users of oral HT. Phytoestrogens are popular alternatives to oestrogen therapy; however, their effects on cardiovascular risk are unknown. We investigated the effect of the phytoestrogen, genistein on the expression of genes and proteins from the haemostatic system in the liver in an ovariectomised rat model. Fifty-nine virgin female Sprague-Dawley rats were fed with soy-free chow supplemented with 17ß estradiol (E2) (daily uptake 0.19 or 0.75 mg/kg body weight), or genistein (daily uptake 6 or 60 mg/kg body weight), for three months and compared to soy-free control rats. Gene expression of prothrombin, factor VII, fibrinogen alpha and fibrinogen beta was increased with E2 and genistein compared to the soy-free control group (p<0.001). Genistein increased factor VII significantly more than E2 (p<0.005). Plasminogen mRNA was increased in both treatment groups compared to the soy-free control, with genistein expression significantly higher than E2 (p<0.001). Tissue plasminogen inhibitor (tPA), plasminogen activator inhibitor-1 (PAI-1) and C-reactive protein (CRP) expression were also increased in both groups relative the soy-free control. Results of protein analysis largely concurred with those of the mRNA. Oestrogen receptor ß (ERß) was undetected while oestrogen receptor α (ERα) was detected in each sample group. Genistein can increase the expression of coagulation and fibrinolytic genes. This effect was similar and in some cases higher than 17ß estradiol. These results suggest that genistein may not be neutral with respect to the haemostatic system.