Neonatal brain injury and systemic inflammation: modulation by activated protein C ex vivo

Dietary vitamin B6 intake and stroke are negatively associated in adults: A cross-sectional study from the NHANES

Background

The relationship between dietary vitamin B6 and stroke risk is controversial; thus, we analyzed their correlation using data from the National Health and Nutrition Examination Survey (NHANES).

Method

Data from 2005 to 2018 were collected from the NHANES database. Two 24-h dietary recalls and a standard questionnaire were used to evaluate vitamin B6 intake and stroke prevalence. We used logistic regression models to estimate the association between dietary vitamin B6 intake and stroke risk and investigated the nonlinear relationship between them using a restricted cubic spline (RCS). Sensitivity analysis was conducted using propensity score matching (PSM).

Results

Among 24,214 participants, 921 were patients diagnosed with stroke, while 23,293 were without stroke. The multivariate logistic regression model revealed that individuals in the highest quartile of vitamin B6 consumption had a significantly lower stroke risk than those in the lowest quartile under the fully adjusted model (OR: 0.48, 95 % CI: 0.35-0.66, P < 0.001). Subgroup analyses showed that dietary intake of vitamin B6 was a significant protective factor against stroke risk in different populations, with the most pronounced effect in the population engaging in moderate-intensity physical activity (OR: 0.34, 95%CI: 0.20-0.57). The RCS models revealed a non-linear L-shaped relationship (P for nonlinearity = 0.006) between stroke and dietary intake of vitamin B6.

Conclusions

Our study shows that an increased intake of vitamin B6 could be an effective strategy in reducing the risk of stroke.

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.

Neonatal asphyxia as an inflammatory disease: Reactive oxygen species and cytokines

Neonatologists resuscitate asphyxiated neonates by every available means, including positive ventilation, oxygen therapy, and drugs. Asphyxiated neonates sometimes present symptoms that mimic those of inflammation, such as fever and edema. The main pathophysiology of the asphyxia is inflammation caused by hypoxic-ischemic reperfusion. At birth or in the perinatal period, neonates may suffer several, hypoxic insults, which can activate inflammatory cells and inflammatory mediator production leading to the release of larger quantities of reactive oxygen species (ROS). This in turn triggers the production of oxygen stress-induced high mobility group box-1 (HMGB-1), an endogenous damage-associated molecular patterns (DAMPs) protein bound to toll-like receptor (TLR) -4, which activates nuclear factor-kappa B (NF-κB), resulting in the production of excess inflammatory mediators. ROS and inflammatory mediators are produced not only in activated inflammatory cells but also in non-immune cells, such as endothelial cells. Hypothermia inhibits pro-inflammatory mediators. A combination therapy of hypothermia and medications, such as erythropoietin and melatonin, is attracting attention now. These medications have both anti-oxidant and anti-inflammatory effects. As the inflammatory response and oxidative stress play a critical role in the pathophysiology of neonatal asphyxia, these drugs may contribute to improving patient outcomes.

Haematological issues in neonates with neonatal encephalopathy treated with hypothermia

Neonatal encephalopathy (NE) is associated with abnormality of neurological function and involves multiorgan dysfunction. There are long-term complications such as cerebral palsy and developmental delay. Cardiac, renal, neurological and other organ dysfunctions are well described. Haematological dysfunction is relatively common and includes anaemia, thrombocytopenia, monocyte and neutrophil activation, hypofibrinogenemia and coagulopathy. There is a lack of consensus definitions of hematological parameters and optimal levels for intervention due to the lack of interventional studies in term neonates and the lack of knowledge of the optimal values during therapeutic hypothermia. However, derangements in hematological values are also associated with neurodevelopmental outcomes. This article outlines the different hematological complications associated with NE and therapeutic hypothermia and suggests a framework for management.

Crocin enhances hypothermia therapy in hypoxic ischemia-induced brain injury in mice

Hypoxic-ischemic encephalopathy (HIE) is a serious medical situation at labor which leads to severe brain damage. Hypothermia therapy is the standard treatment for infants with HIE, but the efficacy is limited. Combination treatments are considered to enhance the efficacy of hypothermia. Crocin is an extract from saffron which has anti-inflammatory, anti-oxidant, and neuroprotective properties. The present study sought to investigate whether crocin could act as a combined treatment with hypothermia in a mouse model of HIE. C57BL/6J mice at post-natal day 7 were subjected to left common carotid artery ligation, followed by treatment of crocin (10 mg/kg) and hypothermia, either alone or in combination. Brain edema and tissue infarct were measured to evaluate brain damage. Mediators involved in inflammatory response and oxidative stress were measured. Neurological severity score test was performed to evaluate the functional outcome. Results show that crocin treatment alone could reduce inflammation and brain damage after hypoxia-ischemia. Combined treatment of crocin and hypothermia exerted enhanced therapeutic effect compared with single treatment, resulting in significantly less brain damage, reduced inflammatory and oxidative responses, and improved functional outcome. Together, these data suggest that crocin plays a beneficial effect in the mouse model of HIE. It could also enhance the neuroprotective effect of hypothermia and might be considered as a combination therapeutic treatment with hypothermia in HIE.

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.

Dysregulated Monocyte and Neutrophil Functional Phenotype in Infants With Neonatal Encephalopathy Requiring Therapeutic Hypothermia

Neonatal encephalopathy (NE) is a significant cause of morbidity and mortality. Persistent inflammation and activation of leukocytes mediate brain injury in NE. The standard of care for NE, therapeutic hypothermia (TH), does not improve outcomes in nearly half of moderate to severe cases, resulting in the need for new adjuvant therapies, and immunomodulation holds promise. Our objective was to explore systemic leukocyte phenotype in infants with NE and healthy controls in response to lipopolysaccharide (LPS). Twenty-four infants with NE (NE II-20; NE III = 4) requiring TH and 17 term neonatal controls were enrolled, and blood samples were analyzed between days 1 and 4 of life at a mean (SD) timepoint of 2.1 (± 0.81) days of postnatal life at the time of the routine phlebotomy. Leukocyte cell surface expression levels of Toll-like receptor 4, NADPH oxidase (NOX2), CD11b, mitochondrial mass, and mitochondrial superoxide production were measured by flow cytometry. Gene expression of TRIF (TIR domain-containing adapter-inducing interferon-β), MyD88 and IRAK4 was measured by reverse transcription-polymerase chain reaction. Infants with NE had significantly lower expression of neutrophil CD11b and NOX2 with LPS stimulation compared to healthy term controls. Mitochondrial mass in neutrophils and monocytes was significantly increased in NE infants with LPS compared to controls, potentially indicating a dysregulated metabolism. Infants with NE had significantly lower IRAK4 at baseline than controls. NE infants display a dysregulated inflammatory response compared to healthy infants, with LPS hyporesponsiveness to CD11b and NOX2 and decreased IRAK4 gene expression. This dysregulated immune profile may indicate an adaptable response to limit hyperinflammation.

Evaluation of 3K3A-Activated Protein C to Treat Neonatal Hypoxic Ischemic Brain Injury in the Spiny Mouse

Neonatal hypoxic ischemic encephalopathy (HIE) resulting from intrapartum asphyxia is a global problem that causes severe disabilities and up to 1 million deaths annually. A variant form of activated protein C, 3K3A-APC, has cytoprotective properties that attenuate brain injury in models of adult stroke. In this study, we compared the ability of 3K3A-APC and APC (wild-type (wt)) to attenuate neonatal brain injury, using the spiny mouse (Acomys cahirinus) model of intrapartum asphyxia. Pups were delivered at 38 days of gestation (term = 39 days), with an intrapartum hypoxic insult of 7.5 min (intrapartum asphyxia cohort), or immediate removal from the uterus (control cohort). After 1 h, pups received a subcutaneous injection of 3K3A-APC or wild-type APC (wtAPC) at 7 mg/kg, or vehicle (saline). At 24 h of age, pups were killed and brain tissue was collected for measurement of inflammation and cell death using RT-qPCR and histopathology. Intrapartum asphyxia increased weight loss, inflammation, and apoptosis/necrosis in the newborn brain. 3K3A-APC administration maintained body weight and ameliorated an asphyxia-induced increase of TGFβ1 messenger RNA expression in the cerebral cortex, immune cell aggregation in the corpus callosum, and cell death in the deep gray matter and hippocampus. In the cortex, 3K3A-APC appeared to exacerbate the immune response to the hypoxic ischemic insult. While wtAPC reduced cell death in the corpus callosum and hippocampus following intrapartum asphyxia, it increased markers of neuro-inflammation and cell death in control pups. These findings suggest 3K3A-APC administration may be a useful therapy to reduce cell death and neonatal brain injury associated with HIE.

Altered endotoxin responsiveness in healthy children with Down syndrome

BACKGROUND

Down syndrome (DS) is the most common syndromic immunodeficiency with an increased risk of infection, mortality from sepsis, and autoinflammation. Innate immune function is altered in DS and therefore we examined responses in CD11b and Toll like receptor 4 (TLR-4), which are important immune cell surface markers upregulated in response to Lipopolysaccharide (LPS) endotoxin, and the immunomodulator melatonin. Neutrophil and monocyte responses to LPS and melatonin in children with Down syndrome (DS) who were clinically stable were compared to age-matched controls. Whole blood was incubated with LPS and melatonin and the relative expression of CD11b and TLR-4 evaluated by flow cytometry.

RESULTS

Children with DS had an increased response to LPS in neutrophils and intermediate monocytes, while also having elevated TLR-4 expression on non-classical monocytes compared to controls at baseline. Melatonin reduced CD11b expression on neutrophils, total monocytes, both classical and intermediate sub-types, in children with DS and controls.

CONCLUSION

Melatonin could represent a useful clinical adjunct in the treatment of sepsis as an immunomodulator. Children with DS had increased LPS responses which may contribute to the more adverse outcomes seen in sepsis.

Cytokine production pattern of T lymphocytes in neonatal arterial ischemic stroke during the first month of life-a case study

Background

The perinatal period carries the highest risk for stroke in childhood; however, the pathophysiology is poorly understood and preventive, prognostic, and therapeutic strategies are not available. A new pathophysiological model describes the development of neonatal arterial ischemic stroke (NAIS) as the combined result of prenatal inflammation and hypoxic–ischemic insult. Neuroinflammation and a systemic inflammatory response are also important features of NAIS. Identifying key players of the inflammatory system is in the limelight of current research.

Case presentation

We present four NAIS cases, in whom detailed analysis of intracellular and plasma cytokine levels are available from the first month of life. All neonates were admitted with the initial diagnosis of hypoxic ischemic encephalopathy (HIE); however, early MRI examination revealed NAIS. Blood samples were collected between 3 and 6 h of life, at 24 h, 72 h, 1 week, and 1 month of life. Peripheral blood mononuclear cells were assessed with flow cytometry and plasma cytokine levels were measured. Pooled data from the cohort of four NAIS patients were compared to infants with HIE.

At 6 and 72 h of age, the prevalence of IL10+ CD8+ lymphocytes remained lower in NAIS. At 6 h, CD8+ lymphocytes in NAIS produced more IL-17. At 72 h, CD8+ cells produced more IL-6 in severe HIE than in NAIS, but IL-6 production remained elevated in CD8 cells at 1 month in NAIS, while it decreased in HIE. At 1 week, the prevalence of TGF-β + lymphocytes prone to enter the CNS was elevated in NAIS. On the other hand, by 1 month of age, the prevalence of TGF-β + CD4+ lymphocytes decreased in NAIS compared to HIE. At 72 h, we found elevated plasma levels of IL-5, MCP-1, and IL-17 in NAIS. By 1 month, plasma levels of IL-4, IL-12, and IL-17 decreased in NAIS but remained elevated in HIE.

Conclusions

Differences in the cytokine network are present between NAIS and HIE. CD8 lymphocytes appear to shift towards the pro-inflammatory direction in NAIS. The inflammatory response appears to be more pronounced at 72 h in NAIS but decreases faster, reaching lower plasma levels of inflammatory markers at 1 month.

Role of Perinatal Inflammation in Neonatal Arterial Ischemic Stroke

Based on the review of the literature, perinatal inflammation often induced by infection is the only consistent independent risk factor of neonatal arterial ischemic stroke (NAIS). Preclinical studies show that acute inflammatory processes take place in placenta, cerebral arterial wall of NAIS-susceptible arteries and neonatal brain. A top research priority in NAIS is to further characterize the nature and spatiotemporal features of the inflammatory processes involved in multiple levels of the pathophysiology of NAIS, to adequately design randomized control trials using targeted anti-inflammatory vasculo- and neuroprotective agents.

Neuroprotective effects of hypothermia in inflammatory-sensitized hypoxic-ischemic encephalopathy

BACKGROUND

Despite the recent introduction of hypothermia as a mandatory standard of care, the incidence of neonatal encephalopathy in full-term newborns and its devastating neuro-behavioral outcomes continues to be a major individual, familial and social issue. Neonatal encephalopathy is mainly due to the compounding and interacting effects of hypoxia-ischemia and inflammation resulting from placental and other perinatal infections. It is unclear why hypothermia is effective in alleviating neonatal encephalopathy in some, but not all, full-term newborns. However, newborns exposed to inflammatory-sensitized hypoxia-ischemia seem to have less therapeutic benefit from hypothermia than those exposed to hypoxia-ischemia alone.

OBJECTIVES

To clarify this uncertainty, we tested the efficacy of hypothermia in a double-hit model of neonatal encephalopathy induced by inflammatory-sensitized hypoxia-ischemia.

METHODS

Using a rat preclinical model of endotoxin plus hypoxia-ischemia-induced neonatal encephalopathy of term newborns, we assessed the following in pups exposed (or not) to hypothermia: the extent of brain injuries and the expressions of molecules implicated in neural cell death, namely: pro-inflammatory cytokines, matrix metalloproteinase-9, antioxidant enzymes, as well as receptor-interacting protein-3.

RESULTS

Hypothermia was neuroprotective on inflammatory-sensitized hypoxia-ischemia-induced penumbra, but not core, brain injuries. This beneficial effect was associated with a hypothermia-induced increase of antioxidant enzymes (superoxide dismutase-1, glutathione peroxidase-1), but was not associated with any variations of the other inflammatory mediators tested, namely: interleukin-1β, interleukin-1 receptor antagonist, tumor necrosis factor-α and matrix metalloproteinase-9.

CONCLUSION

Hypothermia is neuroprotective against inflammatory-sensitized hypoxia-ischemia possibly through a hypothermia-induced increase of antioxidant enzymes. This neuroprotective effect seems to be independent of the interleukin-1 system.

Plasma Biomarkers of Oxidative Stress in Neonatal Brain Injury

Perinatal encephalopathy is a leading cause of lifelong disability. Increasing evidence indicates that the pathogenesis of perinatal brain damage is much more complex than originally thought, with multiple pathways involved. An important role of oxidative stress (OS) in the pathogenesis of brain injury is recognized for preterm and term infants. This article examines potential reliable and specific OS biomarkers that can be used in premature and term infants for the early detection and follow-up of the most common neonatal brain injuries, such as hypoxic-ischemic encephalopathy, intraventricular hemorrhage, and periventricular leukomalacia. The next step will be to explore the correlation between brain-specific OS biomarkers and functional brain outcomes.