Glucocorticoids Protect Neonatal Rat Brain in Model of Hypoxic-Ischemic Encephalopathy (HIE)

Intranasal therapies for neonatal hypoxic-ischemic encephalopathy: Systematic review, synthesis, and implications for global accessibility to care

Neonatal hypoxic-ischemic encephalopathy (HIE) is the leading cause of neurodevelopmental morbidity in term infants worldwide. Incidence of HIE is highest in low and middle-income communities with minimal access to neonatal intensive care and an underdeveloped infrastructure for advanced neurologic interventions. Moreover, therapeutic hypothermia, standard of care for HIE in high resourced settings, is shown to be ineffective in low and middle-income communities. With their low cost, ease of administration, and capacity to potently target the central nervous system, intranasal therapies pose a unique opportunity to be a more globally accessible treatment for neonatal HIE. Intranasal experimental therapeutics have been studied in both rodent and piglet models, but no intranasal therapeutics for neonatal HIE have undergone human clinical trials. Additional research must be done to expand the array of treatments available for use as intranasal therapies for neonatal HIE thus improving the neurologic outcomes of infants worldwide.

Advances in Therapies to Treat Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxic-ischemic encephalopathy (HIE) is a condition that results in brain damage in newborns due to insufficient blood and oxygen supply during or after birth. HIE is a major cause of neurological disability and mortality in newborns, with over one million neonatal deaths occurring annually worldwide. The severity of brain injury and the outcome of HIE depend on several factors, including the cause of oxygen deprivation, brain maturity, regional blood flow, and maternal health conditions. HIE is classified into mild, moderate, and severe categories based on the extent of brain damage and resulting neurological issues. The pathophysiology of HIE involves different phases, including the primary phase, latent phase, secondary phase, and tertiary phase. The primary and secondary phases are characterized by episodes of energy and cell metabolism failures, increased cytotoxicity and apoptosis, and activated microglia and inflammation in the brain. A tertiary phase occurs if the brain injury persists, characterized by reduced neural plasticity and neuronal loss. Understanding the cellular and molecular aspects of the different phases of HIE is crucial for developing new interventions and therapeutics. This review aims to discuss the pathophysiology of HIE, therapeutic hypothermia (TH), the only approved therapy for HIE, ongoing developments of adjuvants for TH, and potential future drugs for HIE.

Perinatal asphyxia and hypothermic treatment from the endocrine perspective

Introduction

Perinatal asphyxia is one of the three most important causes of neonatal mortality and morbidity. Therapeutic hypothermia represents the standard treatment for infants with moderate-severe perinatal asphyxia, resulting in reduction in the mortality and major neurodevelopmental disability. So far, data in the literature focusing on the endocrine aspects of both asphyxia and hypothermia treatment at birth are scanty, and many aspects are still debated. Aim of this narrative review is to summarize the current knowledge regarding the short- and long-term effects of perinatal asphyxia and of hypothermia treatment on the endocrine system, thus providing suggestions for improving the management of asphyxiated children.

Results

Involvement of the endocrine system (especially glucose and electrolyte disturbances, adrenal hemorrhage, non-thyroidal illness syndrome) can occur in a variable percentage of subjects with perinatal asphyxia, potentially affecting mortality as well as neurological outcome. Hypothermia may also affect endocrine homeostasis, leading to a decreased incidence of hypocalcemia and an increased risk of dilutional hyponatremia and hypercalcemia.

Conclusions

Metabolic abnormalities in the context of perinatal asphyxia are important modifiable factors that may be associated with a worse outcome. Therefore, clinicians should be aware of the possible occurrence of endocrine complication, in order to establish appropriate screening protocols and allow timely treatment.

A systematic review of immune-based interventions for perinatal neuroprotection: closing the gap between animal studies and human trials

BACKGROUND

Perinatal infection/inflammation is associated with a high risk for neurological injury and neurodevelopmental impairment after birth. Despite a growing preclinical evidence base, anti-inflammatory interventions have not been established in clinical practice, partly because of the range of potential targets. We therefore systematically reviewed preclinical studies of immunomodulation to improve neurological outcomes in the perinatal brain and assessed their therapeutic potential.

METHODS

We reviewed relevant studies published from January 2012 to July 2023 using PubMed, Medline (OvidSP) and EMBASE databases. Studies were assessed for risk of bias using the SYRCLE risk of bias assessment tool (PROSPERO; registration number CRD42023395690).

RESULTS

Forty preclinical publications using 12 models of perinatal neuroinflammation were identified and divided into 59 individual studies. Twenty-seven anti-inflammatory agents in 19 categories were investigated. Forty-five (76%) of 59 studies reported neuroprotection, from all 19 categories of therapeutics. Notably, 10/10 (100%) studies investigating anti-interleukin (IL)-1 therapies reported improved outcome, whereas half of the studies using corticosteroids (5/10; 50%) reported no improvement or worse outcomes with treatment. Most studies (49/59, 83%) did not control core body temperature (a known potential confounder), and 25 of 59 studies (42%) did not report the sex of subjects. Many studies did not clearly state whether they controlled for potential study bias.

CONCLUSION

Anti-inflammatory therapies are promising candidates for treatment or even prevention of perinatal brain injury. Our analysis highlights key knowledge gaps and opportunities to improve preclinical study design that must be addressed to support clinical translation.

Restraint stress during neonatal hypoxia-ischemia alters brain injury following normothermia and hypothermia

Rodent models of neonatal hypoxic-ischemic (HI) injury require a subset of animals to be immobilized for continuous temperature monitoring during the insult and subsequent treatment. Restrained animals are discarded from the analysis due to the effect of restraint on the brain injury as first demonstrated by Thoresen et al 1996. However, the effects of restraint on responses to hypothermic (HT) post-insult therapy are not well described. We examine the effects of restraint associated with different probe placements on HI brain injury. We have conducted a meta-analysis of 23 experiments comparing probe rats (skin n = 42, rectal n = 35) and free-moving matched non-probe controls (n = 80) that underwent HI injury (left common carotid artery ligation and 90 min 8% O₂ ) at postnatal day 7 (P7), followed by 5 h of NT (37°C) or HT (32°C). On P14, brain regions were analyzed for injury (by neuropathology and area loss), microglial reactivity and brain-derived neurotrophic factor (BDNF). HI injury was mitigated in NT skin and rectal probe rats, with greater neuroprotection among the rectal probe rats. Following HT, the skin probe rats maintained the restraint-associated neuroprotection, while brain injury was significantly exacerbated among the rectal probe rats. Microglial reactivity strongly correlated with the acquired injury, with no detectable difference between the groups. Likewise, we observed no differences in BDNF signal intensity. Our findings suggest a biphasic neuroprotection from restraint stress, which becomes detrimental in combination with HT and the presumed discomfort from the rectal probe. This finding is useful in highlighting unforeseen effects of common experimental designs or routine clinical management.

Hypothermia is not therapeutic in a neonatal piglet model of inflammation-sensitized hypoxia-ischemia

BACKGROUND

Perinatal inflammation combined with hypoxia-ischemia (HI) exacerbates injury in the developing brain. Therapeutic hypothermia (HT) is standard care for neonatal encephalopathy; however, its benefit in inflammation-sensitized HI (IS-HI) is unknown.

METHODS

Twelve newborn piglets received a 2 µg/kg bolus and 1 µg/kg/h infusion over 52 h of Escherichia coli lipopolysaccharide (LPS). HI was induced 4 h after LPS bolus. After HI, piglets were randomized to HT (33.5 °C 1-25 h after HI, n = 6) or normothermia (NT, n = 6). Amplitude-integrated electroencephalogram (aEEG) was recorded and magnetic resonance spectroscopy (MRS) was acquired at 24 and 48 h. At 48 h, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)-positive brain cell death, microglial activation/proliferation, astrogliosis, and cleaved caspase-3 (CC3) were quantified. Hematology and plasma cytokines were serially measured.

RESULTS

Two HT piglets died. aEEG recovery, thalamic and white matter MRS lactate/N-acetylaspartate, and TUNEL-positive cell death were similar between groups. HT increased microglial activation in the caudate, but had no other effect on glial activation/proliferation. HT reduced CC3 overall. HT suppressed platelet count and attenuated leukocytosis. Cytokine profile was unchanged by HT.

CONCLUSIONS

We did not observe protection with HT in this piglet IS-HI model based on aEEG, MRS, and immunohistochemistry. Immunosuppressive effects of HT and countering neuroinflammation by LPS may contribute to the observed lack of HT efficacy. Other immunomodulatory strategies may be more effective in IS-HI.

IMPACT

Acute infection/inflammation is known to exacerbate perinatal brain injury and can worsen the outcomes in neonatal encephalopathy. Therapeutic HT is the current standard of care for all infants with NE, but the benefit in infants with coinfection/inflammation is unknown. In a piglet model of inflammation (LPS)-sensitized HI, we observed no evidence of neuroprotection with cooling for 24 h, based on our primary outcome measures: aEEG, MRS Lac/NAA, and histological brain cell death. Additional neuroprotective agents, with beneficial immunomodulatory effects, require exploration in IS-HI models.

Association Among the Gut Microbiome, the Serum Metabolomic Profile and RNA m6A Methylation in Sepsis-Associated Encephalopathy

Objective: To investigate the relationship among the gut microbiome, serum metabolomic profile and RNA m6A methylation in patients with sepsis-associated encephalopathy (SAE), 16S rDNA technology, metabolomics and gene expression validation were applied.

Methods: Serum and feces were collected from patients with and without (SAE group and non-SAE group, respectively, n = 20). The expression of serum markers and IL-6 was detected by enzyme-linked immunosorbent assay (ELISA), and blood clinical indicators were detected using a double antibody sandwich immunochemiluminescence method. The expression of RNA m⁶A regulator were checked by Q-RTPCR. The gut microbiome was analyzed by 16S rDNA sequencing and the metabolite profile was revealed by liquid chromatography-mass spectrometry (LC-MS/MS).

Results: In the SAE group, the IL-6, ICAM-5 and METTL3 levels were significantly more than those in the non-SAE group, while the FTO levels were significantly decreased in the SAE group. The diversity was decreased in the SAE gut microbiome, as characterized by a profound increase in commensals of the Acinetobacter, Methanobrevibacter, and Syner-01 genera, a decrease in [Eubacterium]_hallii_group, while depletion of opportunistic organisms of the Anaerofilum, Catenibacterium, and Senegalimassilia genera were observed in both groups. The abundance of Acinetobacter was positively correlated with the expression of METTL3. The changes between the intestinal flora and the metabolite profile showed a significant correlation. Sphingorhabdus was negatively correlated with 2-ketobutyric acid, 9-decenoic acid, and l-leucine, and positively correlated with Glycyl-Valine [Eubacterium]_hallii_group was positively correlated with 2-methoxy-3-methylpyazine, acetaminophen, and synephrine acetonide.

Conclusion: The gut microbiota diversity was decreased. The serum metabolites and expression of RNA m6A regulators in PBMC were significantly changed in the SAE group compared to the non-SAE group. The results revealed that serum and fecal biomarkers could be used for SAE screening.

Down-Regulated microRNA-192-5p Protects Against Hypoxic-Ischemic Brain Damage via Regulation of YAP1-Mediated Hippo Signaling Pathway

Hypoxic-ischemic brain damage (HIBD) is a familiar neurological disorder. Emerging reports manifest that microRNAs (miRs) are related to the progression of HIBD. The goal of this study is to explore the mechanism of miR-192-5p in HIBD via regulation of Yes-associated protein 1 (YAP1)-mediated Hippo signaling pathway. The miR-192-5p, YAP1, and Hippo pathway-related factors Phospho (p)-Triaminoguanidinium azide (TAZ) in hippocampal tissues and neurons were detected. The regulatory relationship between miR-192-5p and YAP1 was verified. Neonatal hypoxic ischemia and oxygen-glucose deprivation (OGD) were used to simulate HIBD in vivo and in vitro. The neurobehavioral impairment, neuronal damage and vascular endothelial growth factor (VEGF) expression of neonatal rats in each group were detected. The viability, apoptosis and VEGF expression of hippocampal neurons in each group were also examined. MiR-192-5p expression was elevated while YAP1 expression was reduced in hippocampal tissues of HIBD rats in vivo and OGD neurons in vitro. MiR-192-5p had a targeting relation with YAP1. Suppressed miR-192-5p or overexpressed YAP1 in HIBD rats alleviated neurobehavioral impairment and neuronal damage, and decreased the expression levels of p-TAZ and VEGF expression in vivo. Reduced miR-192-5p or augmented YAP1 decelerated the neuron apoptosis, decreased the p-TAZ level and VEGF level and promoted cell viability of OGD hippocampal neurons in vitro. The study highlights that inhibited miR-192-5p protects against HIBD via regulation of YAP1 and Hippo signaling pathway, which is beneficial for HIBD treatment.

Current Therapies for Neonatal Hypoxic-Ischaemic and Infection-Sensitised Hypoxic-Ischaemic Brain Damage

Neonatal hypoxic-ischaemic brain damage is a leading cause of child mortality and morbidity, including cerebral palsy, epilepsy, and cognitive disabilities. The majority of neonatal hypoxic-ischaemic cases arise as a result of impaired cerebral perfusion to the foetus attributed to uterine, placental, or umbilical cord compromise prior to or during delivery. Bacterial infection is a factor contributing to the damage and is recorded in more than half of preterm births. Exposure to infection exacerbates neuronal hypoxic-ischaemic damage thus leading to a phenomenon called infection-sensitised hypoxic-ischaemic brain injury. Models of neonatal hypoxia-ischaemia (HI) have been developed in different animals. Both human and animal studies show that the developmental stage and the severity of the HI insult affect the selective regional vulnerability of the brain to damage, as well as the subsequent clinical manifestations. Therapeutic hypothermia (TH) is the only clinically approved treatment for neonatal HI. However, the number of HI infants needed to treat with TH for one to be saved from death or disability at age of 18-22 months, is approximately 6-7, which highlights the need for additional or alternative treatments to replace TH or increase its efficiency. In this review we discuss the mechanisms of HI injury to the immature brain and the new experimental treatments studied for neonatal HI and infection-sensitised neonatal HI.

Neuropathophysiology of coronavirus disease 2019: neuroinflammation and blood brain barrier disruption are critical pathophysiological processes that contribute to the clinical symptoms of SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) is caused by the novel SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) first discovered in Wuhan, Hubei province, China in December 2019. SARS-CoV-2 has infected several millions of people, resulting in a huge socioeconomic cost and over 2.5 million deaths worldwide. Though the pathogenesis of COVID-19 is not fully understood, data have consistently shown that SARS-CoV-2 mainly affects the respiratory and gastrointestinal tracts. Nevertheless, accumulating evidence has implicated the central nervous system in the pathogenesis of SARS-CoV-2 infection. Unfortunately, however, the mechanisms of SARS-CoV-2 induced impairment of the central nervous system are not completely known. Here, we review the literature on possible neuropathogenic mechanisms of SARS-CoV-2 induced cerebral damage. The results suggest that downregulation of angiotensin converting enzyme 2 (ACE2) with increased activity of the transmembrane protease serine 2 (TMPRSS2) and cathepsin L in SARS-CoV-2 neuroinvasion may result in upregulation of proinflammatory mediators and reactive species that trigger neuroinflammatory response and blood brain barrier disruption. Furthermore, dysregulation of hormone and neurotransmitter signalling may constitute a fundamental mechanism involved in the neuropathogenic sequelae of SARS-CoV-2 infection. The viral RNA or antigenic peptides also activate or interact with molecular signalling pathways mediated by pattern recognition receptors (e.g., toll-like receptors), nuclear factor kappa B, Janus kinase/signal transducer and activator of transcription, complement cascades, and cell suicide molecules. Potential molecular targets and therapeutics of SARS-CoV-2 induced neurologic damage are also discussed.

Bidirectional Crosstalk Between Hypoxia Inducible Factors and Glucocorticoid Signalling in Health and Disease

Glucocorticoid-induced (GC) and hypoxia-induced transcriptional responses play an important role in tissue homeostasis and in the regulation of cellular responses to stress and inflammation. Evidence exists that there is an important crosstalk between both GC and hypoxia effects. Hypoxia is a pathophysiological condition to which cells respond quickly in order to prevent metabolic shutdown and death. The hypoxia inducible factors (HIFs) are the master regulators of oxygen homeostasis and are responsible for the ability of cells to cope with low oxygen levels. Maladaptive responses of HIFs contribute to a variety of pathological conditions including acute mountain sickness (AMS), inflammation and neonatal hypoxia-induced brain injury. Synthetic GCs which are analogous to the naturally occurring steroid hormones (cortisol in humans, corticosterone in rodents), have been used for decades as anti-inflammatory drugs for treating pathological conditions which are linked to hypoxia (i.e. asthma, ischemic injury). In this review, we investigate the crosstalk between the glucocorticoid receptor (GR), and HIFs. We discuss possible mechanisms by which GR and HIF influence one another, in vitro and in vivo, and the therapeutic effects of GCs on HIF-mediated diseases.

A New Sequential Forward Feature Selection (SFFS) Algorithm for Mining Best Topological and Biological Features to Predict Protein Complexes from Protein-Protein Interaction Networks (PPINs)

Protein-protein interaction plays an important role in the understanding of biological processes in the body. A network of dynamic protein complexes within a cell that regulates most biological processes is known as a protein-protein interaction network (PPIN). Complex prediction from PPINs is a challenging task. Most of the previous computation approaches mine cliques, stars, linear and hybrid structures as complexes from PPINs by considering topological features and fewer of them focus on important biological information contained within protein amino acid sequence. In this study, we have computed a wide variety of topological features and integrate them with biological features computed from protein amino acid sequence such as bag of words, physicochemical and spectral domain features. We propose a new Sequential Forward Feature Selection (SFFS) algorithm, i.e., random forest-based Boruta feature selection for selecting the best features from computed large feature set. Decision tree, linear discriminant analysis and gradient boosting classifiers are used as learners. We have conducted experiments by considering two reference protein complex datasets of yeast, i.e., CYC2008 and MIPS. Human and mouse complex information is taken from CORUM 3.0 dataset. Protein interaction information is extracted from the database of interacting proteins (DIP). Our proposed SFFS, i.e., random forest-based Brouta feature selection in combination with decision trees, linear discriminant analysis and Gradient Boosting Classifiers outperforms other state of art algorithms by achieving precision, recall and F-measure rates, i.e. 94.58%, 94.92% and 94.45% for MIPS, 96.31%, 93.55% and 96.02% for CYC2008, 98.84%, 98.00%, 98.87 % for CORUM humans and 96.60%, 96.70%, 96.32% for CORUM mouse dataset complexes, respectively.

DNA repair pathways and their roles in drug resistance for lung adenocarcinoma

Lung cancer is the leading cancer type of death rate. The lung adenocarcinoma subtype is responsible for almost half of the total lung cancer deaths. Despite the improvements in cancer treatment in recent years, lung adenocarcinoma patients' overall survival rate remains poor. Immunetherapy and chemotherapy are two of the most widely used options for the treatment of cancer. Although many cancer types initially respond to these treatments, the development of resistance is inevitable. The rapid development of drug resistance mainly characterizes lung adenocarcinoma. Despite being the subject of many studies in recent years, the resistance initiation and progression mechanism is still unclear. In this review, we have examined the role of the primary DNA repair pathways (non-homologous end joining (NHEJ) pathway, homologous-recombinant repair (HR) pathway, base excision repair (BER) pathway, and nucleotide excision repair (NER) pathway and transactivation mechanisms of tumor protein 53 (TP53) in drug resistance development. This review suggests that mentioned pathways have essential roles in developing the resistance against chemotherapy and immunotherapy in lung adenocarcinoma patients.

Neurological Outcome Following Newborn Encephalopathy With and Without Perinatal Infection: A Systematic Review

Background: Studies have suggested that neurological outcome may differ in newborns with encephalopathy with and without perinatal infection. We aimed to systematically review this association. Methods: We conducted this systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Studies were obtained from four databases including Pubmed, Embase, Web of Science, and The Cochrane Database. Newborns with encephalopathy with and without markers of perinatal infection were compared with regard to neurodevelopmental assessments, neurological disorders, and early biomarkers of brain damage. Risk of bias and quality of evidence were assessed by the Newcastle-Ottawa scale and Grading of Recommendations Assessment, Development and Evaluation (GRADE). Results: We screened 4,284 studies of which eight cohort studies and one case-control study met inclusion criteria. A narrative synthesis was composed due to heterogeneity between studies. Six studies were classified as having low risk of bias, while three studies were classified as having high risk of bias. Across all outcomes, the quality of evidence was very low. The neurological outcome was similar in newborns with encephalopathy with and without markers of perinatal infection. Conclusions: Further studies of higher quality are needed to clarify whether perinatal infection may affect neurological outcome following newborn encephalopathy. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42020185717.

Proteomic changes in the hippocampus and motor cortex in a rat model of cerebral palsy: Effects of topical treatment

Cerebral palsy (CP) is a non-progressive motor-impairment disorder related to brain injury early in development. To gain new insights into the mechanisms of CP and the therapeutic efficacy of Baimai ointment, we used a high-throughput quantitative proteomic approach to evaluate proteomic changes in the hippocampus and motor cortex in a rat model of CP induced by lipopolysaccharide (LPS) combined with hypoxia/ischemia (H/I). More than 2000 proteins were identified in each brain region with high confidence. Quantitative analysis demonstrated profound disturbances in the proteomes of the hippocampus and motor cortex after LPS + H/I, in addition to the disruption of the motor system. In contrast, the topical application of Baimai ointment not only alleviated the motor deficit in the CP model rats, but also restored the proteomes in the brain cortex. Furthermore, astrocytes in the hippocampus were strongly activated in the Baimai-treated CP rat brains, associated with an increase in neurotrophic factors. Proteomic analysis demonstrated that the CP model induced neuroinflammatory responses in the brain which were reversed by the topical application of Baimai ointment. This study highlights the unexpected roles of hippocampus and motor cortex neurons in CP progress and treatment, thus providing potentially novel therapeutic targets for CP.

Effects of prenatal photobiomodulation treatment on neonatal hypoxic ischemia in rat offspring

Neonatal hypoxic-ischemic (HI) injury is a severe complication often leading to neonatal death and long-term neurobehavioral deficits in children. Currently, the only treatment option available for neonatal HI injury is therapeutic hypothermia. However, the necessary specialized equipment, possible adverse side effects, and limited effectiveness of this therapy creates an urgent need for the development of new HI treatment methods. Photobiomodulation (PBM) has been shown to be neuroprotective against multiple brain disorders in animal models, as well as limited human studies. However, the effects of PBM treatment on neonatal HI injury remain unclear. Methods: Two-minutes PBM (808 nm continuous wave laser, 8 mW/cm² on neonatal brain) was applied three times weekly on the abdomen of pregnant rats from gestation day 1 (GD1) to GD21. After neonatal right common carotid artery ligation, cortex- and hippocampus-related behavioral deficits due to HI insult were measured using a battery of behavioral tests. The effects of HI insult and PBM pretreatment on infarct size; synaptic, dendritic, and white matter damage; neuronal degeneration; apoptosis; mitochondrial function; mitochondrial fragmentation; oxidative stress; and gliosis were then assessed. Results: Prenatal PBM treatment significantly improved the survival rate of neonatal rats and decreased infarct size after HI insult. Behavioral tests revealed that prenatal PBM treatment significantly alleviated cortex-related motor deficits and hippocampus-related memory and learning dysfunction. In addition, mitochondrial function and integrity were protected in HI animals treated with PBM. Additional studies revealed that prenatal PBM treatment significantly alleviated HI-induced neuroinflammation, oxidative stress, and myeloid cell/astrocyte activation. Conclusion: Prenatal PBM treatment exerts neuroprotective effects on neonatal HI rats. Underlying mechanisms for this neuroprotection may include preservation of mitochondrial function, reduction of inflammation, and decreased oxidative stress. Our findings support the possible use of PBM treatment in high-risk pregnancies to alleviate or prevent HI-induced brain injury in the perinatal period.

Immunomodulatory Mechanism and Potential Therapies for Perinatal Hypoxic-Ischemic Brain Damage

Hypoxia-ischemia (HI) is one of the most common causes of death and disability in neonates. Currently, the only available licensed treatment for perinatal HI is hypothermia. However, it alone is not sufficient to prevent the brain injuries and/or neurological dysfunction related to HI. Perinatal HI can activate the immune system and trigger the peripheral and central responses which involve the immune cell activation, increase in production of immune mediators and release of reactive oxygen species. There is mounting evidence indicating that regulation of immune response can effectively rescue the outcomes of brain injury in experimental perinatal HI models such as Rice-Vannucci model of newborn hypoxic-ischemic brain damage (HIBD), local transient cerebral ischemia and reperfusion model, perinatal asphyxia model, and intrauterine hypoxia model. This review summarizes the many studies about immunomodulatory mechanisms and therapies for HI. It highlights the important actions of some widely documented therapeutic agents for effective intervening of HI related brain damage, namely, HIBD, such as EPO, FTY720, Minocycline, Gastrodin, Breviscapine, Milkvetch etc. In this connection, it has been reported that the ameboid microglial cells featured prominently in the perinatal brain represent the key immune cells involved in HIBD. To this end, drugs, chemical agents and herbal compounds which have the properties to suppress microglia activation have recently been extensively explored and identified as potential therapeutic agents or strategies for amelioration of neonatal HIBD.

Viral pathogen-induced mechanisms to antagonize mammalian interferon (IFN) signaling pathway

Antiviral responses of interferons (IFNs) are crucial in the host immune response, playing a relevant role in controlling viralw infections. Three types of IFNs, type I (IFN-α, IFN-β), II (IFN-γ) and III (IFN-λ), are classified according to their receptor usage, mode of induction, biological activity and amino acid sequence. Here, we provide a comprehensive review of type I IFN responses and different mechanisms that viruses employ to circumvent this response. In the first part, we will give an overview of the different induction and signaling cascades induced in the cell by IFN-I after virus encounter. Next, highlights of some of the mechanisms used by viruses to counteract the IFN induction will be described. And finally, we will address different mechanism used by viruses to interference with the IFN signaling cascade and the blockade of IFN induced antiviral activities.

Methylprednisolone Reduces Persistent Post-ischemic Inflammation in a Rat Hypoxia-Ischemia Model of Perinatal Stroke

In perinatal stroke, the initial injury results in a chronic inflammatory response caused by the release of proinflammatory cytokines, gliosis and microglia activation. This chronic and ongoing inflammatory response exacerbates the brain injury, often resulting in encephalopathy and cerebral palsy (CP). Using a neonatal rat model of hypoxia-ischemia (HI) at postnatal day (P)7, we demonstrated that chronic inflammation is persistent and continues into the tertiary phase of perinatal stroke and can be attenuated by the administration of methylprednisolone sodium-succinate (MPSS, 30 mg/kg), a US Food and Drug Administration (FDA) approved anti-inflammatory agent. The inflammatory response was assessed by real-time quantitative PCR and ELISA for markers of inflammation (CCL3, CCL5, IL18 and TNFα). Structural changes were evaluated by histology (LFB/H&E), while cellular changes were assessed by Iba-1, ED1, GFAP, NeuN, Olig2 and CC1 immunostaining. Functional deficits were assessed with the Cylinder test and Ladder Rung Walking test. MPSS was injected 14 days after HI insult to attenuate chronic inflammation. In neonatal conditions such as CP, P21 is a clinically relevant time-point in rodents, corresponding developmentally to a 2-year-old human. Administration of MPSS resulted in reduced structural damage (corpus callosum, cortex, hippocampus, striatum), gliosis and reactive microglia and partial restoration of the oligodendrocyte population. Furthermore, significant behavioural recovery was observed. In conclusion, we demonstrated that administration of MPSS during the tertiary phase of perinatal stroke results in attenuation of the chronic inflammatory response, leading to pathophysiological and functional recovery. This work validates the high clinical impact of MPSS to treat neonatal conditions linked to chronic inflammation.

Repression of the Glucocorticoid Receptor Increases Hypoxic-Ischemic Brain Injury in the Male Neonatal Rat

Hypoxic-ischemic encephalopathy (HIE) resulting from asphyxia is the most common cause of neonatal brain damage and results in significant neurological sequelae, including cerebral palsy. The current therapeutic interventions are extremely limited in improving neonatal outcomes. The present study tests the hypothesis that the suppression of endogenous glucocorticoid receptors (GRs) in the brain increases hypoxic-ischemic (HI) induced neonatal brain injury and worsens neurobehavioral outcomes through the promotion of increased inflammation. A mild HI treatment of P9 rat pups with ligation of the right common carotid artery followed by the treatment of 8% O₂ for 60 min produced more significant brain injury with larger infarct size in female than male pups. Intracerebroventricular injection of GR siRNAs significantly reduced GR protein and mRNA abundance in the neonatal brain. Knockdown of endogenous brain GRs significantly increased brain infarct size after HI injury in male, but not female, rat pups. Moreover, GR repression resulted in a significant increase in inflammatory cytokines TNF-α and IL-10 at 6 h after HI injury in male pups. Male pups treated with GR siRNAs showed a significantly worsened reflex response and exhibited significant gait disturbances. The present study demonstrates that endogenous brain GRs play an important role in protecting the neonatal brain from HI induced injury in male pups, and suggests a potential role of glucocorticoids in sex differential treatment of HIE in the neonate.

A case of methylprednisolone treatment for metronidazole-induced encephalopathy

Background

Metronidazole, a common antimicrobial agent, can induce encephalopathy in rare cases. After discontinuing metronidazole, most patients show clinical improvement. However, in the face of deteriorating conditions, there have done not to have reports of effective drug treatment.

Case presentation

A 57-year-old man was admitted to our hospital due to dysarthria and ataxic gait after taking metronidazole at the dose of about 32 g for 20 days. Neurological examination showed that his upward and outward movements of bilateral eyeballs were limited, and horizontal and vertical nystagmus were noted. The brain magnetic resonance imaging showed hyper-intensities in the bilateral cerebellar dentate nuclei, medulla oblongata, midbrain and red nuclei in T2W and FLAIR images. However, the patient’s clinical symptoms worsened after drug cessation. High-dose intravenous methylprednisolone pulse therapy was applied, and this led to a drastic improvement of his symptoms and signs.

Conclusions

In our case, we suggest that early methylprednisolone intervention can prevent the progression of metronidazole-induced encephalopathy and accelerate neurological recovery. We infer that the progression of encephalopathy is related to the delayed toxicity caused by high dose or concentration of metronidazole.

Analysis of long non-coding RNA expression profiles in neonatal rats with hypoxic-ischemic brain damage

Hypoxic-ischemic brain damage (HIBD) which is a common cause of acute mortality and neurological dysfunction in neonates still lacks effective therapeutic methods. Long non-coding RNAs (lncRNAs) were demonstrated to play a crucial role in many diseases. To give a foundation for subsequent functional studies of lncRNAs in HIBD, we investigated the profiling of lncRNAs and messenger RNAs (mRNAs) using neonatal HIBD rat model. Six neonatal rats were divided into sham-operated group (n = 3) and HIBD group (n = 3) randomly. Deep RNA sequencing was implemented to find out the meaningful lncRNAs and mRNAs. Quantitative real-time PCR was used to validate expressions of lncRNAs and mRNAs. The Gene Ontology (GO) and kyoto encyclopedia of genes a genomes (KEGG) database were used to predict functions of lncRNAs. A total of 328 differentially expressed lncRNAs (177 down-regulated vs 151 up-regulated) and 7157 differentially expressed mRNAs (2552 down-regulated vs 4605 up-regulated) were identified. The Quantitative real-time PCR results showed significant differential expressions of five lncRNAs and five mRNAs which were consistent with the RNA-Seq data. Gene ontology and KEGG analysis showed these lncRNAs and their expression-correlated mRNAs were closely related to the Janus tyrosine kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, NF-kappa B signaling pathway, Toll-like receptor signaling pathway, calcium signaling pathway, Notch signaling pathway, mitogen activated protein kinase signaling pathway, neuroactive ligand-receptor interaction pathway and more. The results of our study identified the characterization and expression profiles of lncRNAs in neonatal HIBD and may be a basis for further therapeutic research. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* and *Open Data* because it provided all relevant information to reproduce the study in the manuscript and because it made the data publicly available. The data can be accessed at https://osf.io/yf3da/. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

FGF21 promotes functional recovery after hypoxic-ischemic brain injury in neonatal rats by activating the PI3K/Akt signaling pathway via FGFR1/β-klotho

Perinatal asphyxia often results in neonatal cerebral hypoxia-ischemia (HI), which is associated with high mortality and severe long-term neurological deficits in newborns. Currently, there are no effective drugs to mitigate the functional impairments post-HI. Previous studies have shown that fibroblast growth factor 21 (FGF21) has a potential neuroprotective effect against brain injury. However, the effect of FGF21 on neonatal HI brain injury is unclear. In the present study, both in vivo and in vitro models were used to assess whether recombinant human FGF21 (rhFGF21) could exert a neuroprotective effect after HI and explore the associated mechanism. The results showed that the rhFGF21 treatment remarkably reduced the infarct volume, ameliorated the body weight and improved the tissue structure after HI in neonatal rats. In addition, the rhFGF21 treatment lengthened the running endurance times in the rotarod test and decreased the mean escape latencies and increased the number of platform crossings in the Morris water maze test at 21 d post-HI insult. In contrast, the FGFR1 inhibitor PD173074 and PI3K inhibitor LY294002 partially reversed these therapeutic effects. In isolated primary cortical neurons, the rhFGF21 treatment protected primary neurons from oxygen-glucose deprivation (OGD) insult by inhibiting neuronal apoptosis and promoting neuronal survival. Both our in vivo and in vitro results reveal that rhFGF21 could inhibit neuronal apoptosis by activating the PI3K/Akt signaling pathway via FGF21/FGFR1/β-klotho complex formation. Therefore, rhFGF21 may be a promising therapeutic agent for promoting functional recovery after HI-induced neonatal brain injury.

Intranasal delivery of a Fas-blocking peptide attenuates Fas-mediated apoptosis in brain ischemia

Ischemic stroke-induced neuronal cell death results in the permanent disabling of brain function. Apoptotic mechanisms are thought to play a prominent role in neuronal injury and ample evidence implicates Fas signaling in mediating cell death. In this study, we describe the neuroprotective effects of a Fas-blocking peptide (FBP) that by obstructing Fas signaling in cerebral ischemia inhibits apoptosis. Using an intranasal administration route in a rat model of focal cerebral ischemia, we demonstrate that nose-to-brain delivery of FBP after middle cerebral artery occlusion (MCAO) surgery results in the delivery and retention of FBP in Fas-expressing ischemic areas of the brain. A single intranasal administration of 2 mg/kg FBP resulted in significantly reduced neuronal cell death by inhibiting Fas-mediated apoptosis leading to decreased infarct volumes, reduced neurologic deficit scores and recovery from cerebral ischemia. Intranasally delivered FBP might be a promising strategy for the treatment of cerebral ischemic stroke.

Repression of the Glucocorticoid Receptor Aggravates Acute Ischemic Brain Injuries in Adult Mice

Strokes are one of the leading causes of mortality and chronic morbidity in the world, yet with only limited successful interventions available at present. Our previous studies revealed the potential role of the glucocorticoid receptor (GR) in the pathogenesis of neonatal hypoxic-ischemic encephalopathy (HIE). In the present study, we investigate the effect of GR knockdown on acute ischemic brain injuries in a model of focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO) in adult male CD1 mice. GR siRNAs and the negative control were administered via intracerebroventricular (i.c.v.) injection 48 h prior to MCAO. The cerebral infarction volume and neurobehavioral deficits were determined 48 h after MCAO. RT-qPCR was employed to assess the inflammation-related gene expression profiles in the brain before and after MCAO. Western Blotting was used to evaluate the expression levels of GR, the mineralocorticoid receptor (MR) and the brain-derived neurotrophic factor/tropomyosin receptor kinase B (BDNF/TrkB) signaling. The siRNAs treatment decreased GR, but not MR, protein expression, and significantly enhanced expression levels of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) in the brain. Of interest, GR knockdown suppressed BDNF/TrkB signaling in adult mice brains. Importantly, GR siRNA pretreatment significantly increased the infarction size and exacerbated the neurobehavioral deficits induced by MCAO in comparison to the control group. Thus, the present study demonstrates the important role of GR in the regulation of the inflammatory responses and neurotrophic BDNF/TrkB signaling pathway in acute ischemic brain injuries in adult mice, revealing a new insight into the pathogenesis and therapeutic potential in acute ischemic strokes.

The Combination of Human Urinary Kallidinogenase and Mild Hypothermia Protects Adult Rats Against Hypoxic-Ischemic Encephalopathy-Induced Injury by Promoting Angiogenesis and Regeneration

Objectives: Human Urinary Kallidinogenase (HUK) is a tissue kallikrein that plays neuroprotective role in ischemic conditions via different mechanisms. Mild hypothermia (MH) is another robust neuroprotectant that reduces mortality but does not profoundly ameliorate the neurological outcome in hypoxic-ischemic encephalopathy (HIE) patients. However, whether the combination of HUK and MH can be used as a promising neuroprotective treatment in HIE is unknown. Methods: One-hundred and forty-four adult Wistar rats were randomly divided into five groups: Sham, HIE, HUK, MH and a combination of HUK and MH treatment. The HIE rat model was established by right carotid dissection followed by hypoxia aspiration. The survival curve was created within 7 days, and the neurological severity scores (NSS) were assessed at days 0, 1, 3, and 7. Nissl staining, Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL), immunofluorescent staining and western blotting were used to evaluate neuronal survival, apoptosis and necrosis, tight-junction proteins Claudin-1 and Zonula occludens-1 (ZO-1), vascular endothelial growth factor (VEGF), doublecortex (DCX), bradykinin receptor B1 (BDKRB1), BDKRB2 and Ki67 staining. Results: The combined treatment rescued all HIE rats from death and had a best survival curve compared to HIE. The Combination also reduced the NSS scores after HIE at days 7, better than HUK or MH alone. The combination of HUK and MH reserved more cells in Nissl staining and inhibited neuronal apoptosis and necrosis as well as significantly attenuated HIE-induced decreases in claudin-1, ZO-1, cyclin D1 and BDKRB1/B2 in comparison to HUK or MH treatment alone. Moreover, the combined treatment increased the expression of VEGF and DCX as well as the number of Ki67-labeled cells. Conclusions: This study demonstrates that both HUK and MH are neuroprotective after HIE insult; however, the combined therapy with HUK and MH enhanced the efficiency and efficacy of either therapy alone in the treatment of HIE, at least partially by promoting angiogenesis and regeneration and rescuing tight-junction loss. The combination of HUK and MH seems to be a feasible and promising clinical strategy to alleviate cerebral injury following HIE insult. Highlights: -The combination of HUK and MH distinctly reduces neurological dysfunction in HIE rats.-HUK enhances the neuroprotective effects of MH in HIE.-MH attenuates tight-junction disruption, upregulates the BDKR B1/2, DCX and cyclin D1.-The combination of MH and HUK enhances the expressions of MH/HUK mediated-BDKR B1/2, DCX, cyclin D1 and Ki67 positive cells.

The fetus at the tipping point: modifying the outcome of fetal asphyxia

Brain injury around birth is associated with nearly half of all cases of cerebral palsy. Although brain injury is multifactorial, particularly after preterm birth, acute hypoxia-ischaemia is a major contributor to injury. It is now well established that the severity of injury after hypoxia-ischaemia is determined by a dynamic balance between injurious and protective processes. In addition, mothers who are at risk of premature delivery have high rates of diabetes and antepartum infection/inflammation and are almost universally given treatments such as antenatal glucocorticoids and magnesium sulphate to reduce the risk of death and complications after preterm birth. We review evidence that these common factors affect responses to fetal asphyxia, often in unexpected ways. For example, glucocorticoid exposure dramatically increases delayed cell loss after acute hypoxia-ischaemia, largely through secondary hyperglycaemia. This critical new information is important to understand the effects of clinical treatments of women whose fetuses are at risk of perinatal asphyxia.

Pregnancy as a valuable period for preventing hypoxia-ischemia brain damage

Neonatal brain Hypoxia-Ischemia (HI) is one of the major causes of infant mortality and lifelong neurological disabilities. The knowledge about the physiopathological mechanisms involved in HI lesion have increased in recent years, however these findings have not been translated into clinical practice. Current therapeutic approaches remain limited; hypothermia, used only in term or near-term infants, is the golden standard. Epidemiological evidence shows a link between adverse prenatal conditions and increased risk for diseases, health problems, and psychological outcomes later in life, what makes pregnancy a relevant period for preventing future brain injury. Here, we review experimental literature regarding preventive interventions used during pregnancy, i.e., previous to the HI injury, encompassing pharmacological, nutritional and/or behavioral strategies. Literature review used PubMed database. A total of forty one studies reported protective properties of maternal treatments preventing perinatal hypoxia-ischemia injury in rodents. Pharmacological agents and dietary supplementation showed mainly anti-excitotoxicity, anti-oxidant or anti-apoptotic properties. Interestingly, maternal preconditioning, physical exercise and environmental enrichment seem to engage the same referred mechanisms in order to protect neonatal brain against injury. This construct must be challenged by further studies to clearly define the main mechanisms responsible for neuroprotection to be explored in experimental context, as well as to test their potential in clinical settings.

Corticosteroids and perinatal hypoxic-ischemic brain injury

Perinatal hypoxic-ischemic (HI) brain injury is the major cause of neonatal mortality and severe long-term neurological morbidity. Yet, the effective therapeutic interventions currently available are extremely limited. Corticosteroids act on both mineralocorticoid (MR) and glucocorticoid (GR) receptors and modulate inflammation and apoptosis in the brain. Neuroinflammatory response to acute cerebral HI is a major contributor to the pathophysiology of perinatal brain injury. Here, we give an overview of current knowledge of corticosteroid-mediated modulations of inflammation and apoptosis in the neonatal brain, focusing on key regulatory cells of the innate and adaptive immune response. In addition, we provide new insights into targets of MR and GR in potential therapeutic strategies that could be beneficial for the treatment of infants with HI brain injury.

Intestinal microbiota impact sepsis associated encephalopathy via the vagus nerve

OBJECTIVE

The pathogenesis of sepsis associated encephalopathy (SAE) remains poorly understood. Vagus nerve plays an important role in gut-microbiota-brain axis. This study aimed to investigate whether vague nerve is a key mediator of the impact of intestinal microbiota on SAE.

METHODS

Male rats were randomly divided into four groups (n=20): SHAM (SH) group, lipopolysaccharide (LPS) group, fecal microbiota transplantation (FMT) +LPS group, and vagotomy (VGX)+LPS+FMT group. The left cervical vagotomy was performed 30min before LPS administration in LPS+FMT+VGX group. LPS+ FMT and LPS+FMT+VGX groups received nasogastric infusion of feces from healthy donor three times a day. Fecal samples were collected every two days to monitor changes in microbiota composition by 16S rDNA analysis. Brain function was evaluated by behavioral tests and EEG. The levels of tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6, IL-10 in brain cortex were detected by ELISA. The expression of Iba-1 in brain cortex was assessed by immunohistochemistry and Western blot analysis.

RESULTS

Significant modification of microbiota composition, characterized by a profound increase of commensals in the Firmicutes phylum and depletion of opportunistic organisms in the Proteobacteria phylum, was observed in FMT groups compared to LPS group. Furthermore, we identified a reconstituted bacterial community enriched in Firmicutes and depleted of Proteobacteria. In both FMT groups the diversity of the fecal microbiota and the microbiota composition were similar to SH group. LPS mice treated with FMT demonstrated a better spatial memory and less EEG abnormalities, significantly attenuated levels of IL-1β, IL-6, TNF-α, and decreased number of Iba-1 positive microglia in the cortex, but these beneficial effects of FMT were reversed by VGX.

CONCLUSIONS

FMT can change intestinal microbiota in sepsis patients, and vagus nerve is a key mediator between intestinal microbiota and SAE. These findings suggest that FMT and vagus nerve are potential therapy targets for treating SAE.

Neonatal Lipopolysaccharide Exposure Gender-Dependently Increases Heart Susceptibility to Ischemia/Reperfusion Injury in Male Rats

Background: Adverse stress exposure during the early neonatal period has been shown to cause aberrant development, resulting in an increased risk of adult disease. We tested the hypothesis that neonatal exposure to lipopolysaccharide (LPS) does not alter heart function at rest condition but causes heart dysfunction under stress stimulation later in life. Methods: Saline control or LPS were administered to neonatal rats via intraperitoneal injection. Experiments were conducted in 6 week-old male and female rats. Isolated hearts were perfused in a Langendorff preparation. Results: Neonatal LPS exposure exhibited no effects on the body weight of the developing rats, but induced decreases in the left ventricle (LV) to the body weight ratio in male rats. Neonatal LPS exposure showed no effects on the baseline heart function determined by in vivo and ex vivo experiments, but caused decreases in the post-ischemic recovery of the LV function in male but not female rats. Neonatal LPS-mediated LV dysfunction was associated with an increase in myocardial infarct size and the LDH release in the male rats. Conclusion: The present study provides novel evidence that neonatal immune challenges could induce gender-dependent long-term effects on cardiac development and heart function, which reinforces the notion that adverse stress exposure during the early neonatal period can aggravate heart functions and the development of a heart ischemia-sensitive phenotype later in life.