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Spišská V, Kubištová A, Novotný J, Bendová Z. Impact of Prenatal LPS and Early-life Constant Light Exposure on Circadian Gene Expression Profiles in Various Rat Tissues. Neuroscience 2024; 551:17-30. [PMID: 38777136 DOI: 10.1016/j.neuroscience.2024.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/23/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024]
Abstract
Exposure to lipopolysaccharide (LPS) during prenatal development leads to various changes in neurobiological and behavioural patterns. Similarly, continuous exposure to constant light (LL) during the critical developmental period of the circadian system affects gene expression in various tissues in adulthood. Given the reciprocal nature of the interaction between the circadian and the immune systems, our study primarily investigated the individual effects of both interventions and, more importantly, their combined effect. We aimed to explore whether there might be a potential synergistic effect on circadian rhythms and their parameters, focussing on the expression of clock genes, immune-related genes, and specific genes in the hippocampus, pineal gland, spleen and adrenal gland of rats at postnatal day 30. Our results show a significant influence of prenatal LPS and postnatal LL on the expression profiles of all genes assessed. However, the combination of prenatal LPS and postnatal LL only revealed an enhanced negative effect in a minority of the comparisons. In most cases, it appeared to attenuate the changes induced by the individual interventions, restoring the measured parameters to values closer to those of the control group. In particular, genes such as Nr1d1, Aanat and Tph1 showed increased amplitude in the pineal gland and spleen, while the kynurenine enzymes Kynu and KatII developed circadian rhythmicity in the adrenal glands only after the combined interventions. Our data suggest that a mild immunological challenge during prenatal development may play a critical role in triggering an adaptive response of the circadian clock later in life.
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Affiliation(s)
- Veronika Spišská
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Aneta Kubištová
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jiří Novotný
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Zdeňka Bendová
- Department of Physiology, Faculty of Science, Charles University, Prague, Czech Republic; National Institute of Mental Health, Klecany, Czech Republic.
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Dhillon SK, Lear CA, Davidson JO, Magawa S, Gunn AJ, Bennet L. The neural and cardiovascular effects of exposure of gram-positive bacterial inflammation in preterm fetal sheep. J Cereb Blood Flow Metab 2024; 44:955-969. [PMID: 37824725 PMCID: PMC11318397 DOI: 10.1177/0271678x231197380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 04/17/2023] [Accepted: 05/27/2023] [Indexed: 10/14/2023]
Abstract
Perinatal infection or inflammation are associated with adverse neurodevelopmental effects and cardiovascular impairments in preterm infants. Most preclinical studies have examined the effects of gram-negative bacterial inflammation on the developing brain, although gram-positive bacterial infections are a major contributor to adverse outcomes. Killed Su-strain group 3 A streptococcus pyogenes (Picibanil, OK-432) is being used for pleurodesis in fetal hydrothorax/chylothorax. We therefore examined the neural and cardiovascular effects of clinically relevant intra-plural infusions of Picibanil. Chronically instrumented preterm (0.7 gestation) fetal sheep received an intra-pleural injection of low-dose (0.1 mg, n = 8) or high-dose (1 mg, n = 8) Picibanil or saline-vehicle (n = 8). Fetal brains were collected for histology one-week after injection. Picibanil exposure was associated with sustained diffuse white matter inflammation and loss of immature and mature oligodendrocytes and subcortical neurons, and associated loss of EEG power. These neural effects were not dose-dependent. Picibanil was also associated with acute changes in heart rate and attenuation of the maturational increase in mean arterial pressure. Even a single exposure to a low-dose gram-positive bacterial-mediated inflammation during the antenatal period is associated with prolonged changes in vascular and neural function.
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Affiliation(s)
| | - Christopher A Lear
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Shoichi Magawa
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
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3
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White OR, Corry KA, Moralejo DH, Law JB, Snyder JM, Mietzsch U, Juul SE, Wood TR. Rectal temperature after hypoxia-ischemia predicts white matter and cortical pathology in the near-term ferret. Pediatr Res 2024; 95:84-92. [PMID: 37684430 DOI: 10.1038/s41390-023-02793-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 08/11/2023] [Accepted: 08/15/2023] [Indexed: 09/10/2023]
Abstract
BACKGROUND Neonatal encephalopathy (NE) remains a common cause of infant morbidity and mortality. Neuropathological corollaries of NE associated with acute hypoxia-ischemia include a central injury pattern involving the basal ganglia and thalamus, which may interfere with thermoregulatory circuits. Spontaneous hypothermia (SH) occurs in both preclinical models and clinical hypoxic-ischemic NE and may provide an early biomarker of injury severity. To determine whether SH predicts the degree of injury in a ferret model of hypoxic-ischemic NE, we investigated whether rectal temperature (RT) 1 h after insult correlated with long-term outcomes. METHODS Postnatal day (P)17 ferrets were presensitized with Escherichia coli lipopolysaccharide before undergoing hypoxia-ischemia/hyperoxia (HIH): bilateral carotid artery ligation, hypoxia-hyperoxia-hypoxia, and right ligation reversal. One hour later, nesting RTs were measured. RESULTS Animals exposed to HIH were separated into normothermic (NT; ≥34.4 °C) or spontaneously hypothermic (SH; <34.4 °C) groups. At P42, cortical development, ex vivo MRI, and neuropathology were quantitated. Whole-brain volume and fractional anisotropy in SH brains were significantly decreased compared to control and NT animals. SH brains also had significantly altered gyrification, greater cortical pathology, and increased corpus callosum GFAP staining relative to NT and control brains. CONCLUSION In near-term-equivalent ferrets, nesting RT 1 h after HIH may predict long-term neuropathological outcomes. IMPACT High-throughput methods to determine injury severity prior to treatment in animal studies of neonatal brain injury are lacking. In a gyrified animal model of neonatal inflammation-sensitized hypoxic-ischemic brain injury in the ferret, rectal temperature 1 h after hypoxia predicts animals who will have increased cortical pathology and white matter changes on MRI. These changes parallel similar responses in rodents and humans but have not previously been correlated with long-term neuropathological outcomes in gyrified animal models. Endogenous thermoregulatory responses to injury may provide a translational marker of injury severity to help stratify animals to treatment groups or predict outcome in preclinical studies.
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Affiliation(s)
- Olivia R White
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Kylie A Corry
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Daniel H Moralejo
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Janessa B Law
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Jessica M Snyder
- Department of Comparative Medicine, University of Washington, Seattle, WA, USA
| | - Ulrike Mietzsch
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Sandra E Juul
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, WA, USA
- Center on Human Development and Disability, University of Washington, Seattle, WA, USA
| | - Thomas R Wood
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, WA, USA.
- Center on Human Development and Disability, University of Washington, Seattle, WA, USA.
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Chang C, Vivekanandarajah A, Waters KA, Machaalani R. Cell death in the lateral geniculate nucleus, and its possible relationship with nicotinic receptors and sudden infant death syndrome (SIDS). Mol Neurobiol 2023; 60:4120-4131. [PMID: 37041306 DOI: 10.1007/s12035-023-03332-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 03/28/2023] [Indexed: 04/13/2023]
Abstract
The role of the lateral geniculate nucleus (LGN) in vision has been extensively studied, yet its extraretinal capacities are still being investigated, including its role in arousal from sleep. The β2 nicotinic acetylcholine receptor (nAChR) subunit is involved in the laminal organisation of the LGN with magnocellular (MC) and parvocellular (PC) neurons. Sudden infant death syndrome (SIDS) occurs during a sleep period and, neuropathologically, is associated with increased neuronal cell death and altered nAChRs. A recent qualitative pilot study from our group implicates the possibility of increased neuronal death/apoptosis in the SIDS LGN. The present study used quantitative analysis to report the baseline expression of apoptotic and nAChR subunits α7 and β2 in the PC and MC layers of the LGN, to determine correlations amongst these markers within layers and across layers, and to evaluate changes in the expression of these markers in the LGN of SIDS infants, along with associations with SIDS risk factors, such as age, sex, cigarette smoke exposure, bed-sharing, and presence of an upper respiratory tract infection (URTI). Tissue was immunohistochemically stained for cell death markers of active caspase-3 (Casp-3) and TUNEL, and for the α7 and β2 nAChR subunits. Amongst 43 cases of sudden and unexpected deaths in infancy (SUDI), classifications included explained deaths (eSUDI, n = 9), SIDS I (n = 5) and SIDS II (n = 29). Results indicated a strong correlation of the apoptotic markers and β2 nAChR subunit between the LGN layers, but not across the markers within the layers. Amongst the diagnostic groups, compared to eSUDI, the SIDS II cases had decreased Casp-3 expression while β2 nAChR expression was increased in both PC and MC layers. Amongst the SIDS risk factors, URTI and bed-sharing were associated with changes in neuronal death but not in the α7 and β2 markers. In conclusion, our findings do not support a role for the α7 and β2 nAChRs in apoptotic regulation of the LGN layers during infancy. However, for SIDS victims, an inverse correlation between the changes for markers of apoptosis and the β2 nAChR subunit expression suggests altered LGN function.
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Affiliation(s)
- Cynthia Chang
- Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Arunnjah Vivekanandarajah
- Discipline of Medicine, Central Clinical School, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia
| | - Karen A Waters
- Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia
- Discipline of Child and Adolescent Health, Children's Hospital at Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia
| | - Rita Machaalani
- Sydney Medical School, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, 2006, Australia.
- Discipline of Child and Adolescent Health, Children's Hospital at Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia.
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Barks JD, Liu Y, Dopp IA, Silverstein FS. Azithromycin reduces inflammation-amplified hypoxic-ischemic brain injury in neonatal rats. Pediatr Res 2022; 92:415-423. [PMID: 34625655 PMCID: PMC8989723 DOI: 10.1038/s41390-021-01747-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 06/07/2021] [Accepted: 06/16/2021] [Indexed: 11/17/2022]
Abstract
BACKGROUND Systemic inflammation amplifies neonatal hypoxic-ischemic (HI) brain injury. Azithromycin (AZ), an antibiotic with anti-inflammatory properties, improves sensorimotor function and reduces tissue damage after neonatal rat HI brain injury. The objective of this study was to determine if AZ is neuroprotective in two neonatal rat models of inflammation-amplified HI brain injury. DESIGN/METHODS Seven-day-old (P7) rats received injections of toll-like receptor agonists lipopolysaccharide (LPS) or Pam3Cys-Ser-(Lys)4 (PAM) prior to right carotid ligation followed by 50 min (LPS + HI) or 60 min (PAM + HI) in 8% oxygen. Outcomes included contralateral forelimb function (forepaw placing; grip strength), survival, %Intact right hemisphere (brain damage), and a composite score incorporating these measures. We compared postnatal day 35 outcomes in controls and groups treated with three or five AZ doses. Then, we compared P21 outcomes when the first (of five) AZ doses were administered 1, 2, or 4 h after HI. RESULTS In both LPS + HI and PAM + HI models, AZ improved sensorimotor function, survival, brain tissue preservation, and composite scores. Benefits increased with five- vs. three-dose AZ and declined with longer initiation delay. CONCLUSIONS Perinatal systemic infection is a common comorbidity of neonatal asphyxia brain injury and contributes to adverse outcomes. These data support further evaluation of AZ as a candidate treatment for neonatal neuroprotection. IMPACT AZ treatment decreases sensorimotor impairment and severity of brain injury, and improves survival, after inflammation-amplified HI brain injury, and this can be achieved even with a 2 h delay in initiation. This neuroprotective benefit is seen in models of inflammation priming by both Gram-negative and Gram-positive infections. This extends our previous findings that AZ treatment is neuroprotective after HI brain injury in neonatal rats.
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Affiliation(s)
- John D.E. Barks
- Department of Pediatrics, University of Michigan Medical School, The University of Michigan, Ann Arbor, MI
| | - Yiqing Liu
- Department of Pediatrics, University of Michigan Medical School, The University of Michigan, Ann Arbor, MI
| | - Ian A. Dopp
- Department of Pediatrics, University of Michigan Medical School, The University of Michigan, Ann Arbor, MI
| | - Faye S. Silverstein
- Department of Pediatrics, University of Michigan Medical School, The University of Michigan, Ann Arbor, MI,Department of Neurology, University of Michigan Medical School, The University of Michigan, Ann Arbor, MI
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Combined exposure to maternal high-fat diet and neonatal lipopolysaccharide disrupts stress-related signaling but normalizes spatial memory in juvenile rats. Brain Behav Immun 2022; 102:299-311. [PMID: 35259428 DOI: 10.1016/j.bbi.2022.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/27/2022] [Accepted: 03/03/2022] [Indexed: 10/18/2022] Open
Abstract
Both neonatal infections and exposure to maternal obesity are inflammatory stressors in early life linked to increased rates of psychopathologies related to mood and cognition. Epidemiological studies indicate that neonates born to mothers with obesity have a higher likelihood of developing neonatal infections, however effects on offspring physiology and behavior resulting from the combination of these stressors have yet to be investigated. The aim of this study was to explore immediate and persistent phenotypes resulting from neonatal lipopolysaccharide (nLPS) administration in rat offspring born to dams consuming a high-fat diet (HFD). Neural transcript abundance of genes involved with stress regulation and spatial memory were examined alongside related behaviors. At the juvenile age point, unlike offspring exposed to maternal HFD (mHFD) or nLPS alone, offspring with combined exposure to mHFD + nLPS displayed altered transcript abundances of stress-related genes in the ventral hippocampus (HPC) in a manner conducive to potentiating stress responses. For memory-related phenotypes, juveniles exposed to mHFD + nLPS exhibited normalized spatial memory and levels of memory-related gene expression in the dorsal HPC similar to control diet offspring, while control diet + nLPS, and mHFD offspring exhibited reduced levels of memory-related gene expression and impaired spatial memory. These findings suggest that dual exposure to unique inflammatory stressors in early life can disrupt neural stress regulation but normalize spatial memory processes.
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Temporal Characterization of Microglia-Associated Pro- and Anti-Inflammatory Genes in a Neonatal Inflammation-Sensitized Hypoxic-Ischemic Brain Injury Model. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:2479626. [PMID: 35281473 PMCID: PMC8906938 DOI: 10.1155/2022/2479626] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/22/2021] [Accepted: 01/27/2022] [Indexed: 02/06/2023]
Abstract
Hypoxic-ischemic encephalopathy (HIE) mainly affects preterm and term newborns, leading to a high risk of brain damage. Coexisting infection/inflammation and birth asphyxia are key factors associated with intracerebral increase of proinflammatory cytokines linked to HIE. Microglia are key mediators of inflammation during perinatal brain injury, characterized by their phenotypic plasticity, which may facilitate their participation in both the progression and resolution of injury-induced inflammation. The purpose of this study was to investigate the temporal expression of genes associated with pro- and anti-inflammatory cytokines as well as the nucleotide-binding domain, leucine-rich repeat protein (NLRP-3) inflammasome from microglia cells. For this purpose, we used our established neonatal rat model of inflammation-sensitized hypoxic-ischemic (HI) brain injury in seven-day-old rats. We assessed gene expression profiles of 11 cytokines and for NLRP-3 using real-time PCR from sorted CD11b/c microglia of brain samples at different time points (3.5 h after LPS injection and 0, 5, 24, 48, and 72 hours post HI) following different treatments: vehicle, E. coli lipopolysaccharide (LPS), vehicle/HI, and LPS/HI. Our results showed that microglia are early key mediators of the inflammatory response and exacerbate the inflammatory response following HI, polarizing into a predominant proinflammatory M1 phenotype in the early hours post HI. The brains only exposed to HI showed a delay in the expression of proinflammatory cytokines. We also demonstrated that NLRP-3 plays a role in the inflammatory resolution with a high expression after HI insult. The combination of both, a preinfection/inflammation condition and hypoxia-ischemia, resulted in a higher proinflammatory cytokine storm, highlighting the significant contribution of acute inflammation sensitizing prior to a hypoxic insult on the severity of perinatal brain damage.
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Sullivan BA, Fairchild KD. Vital signs as physiomarkers of neonatal sepsis. Pediatr Res 2022; 91:273-282. [PMID: 34493832 DOI: 10.1038/s41390-021-01709-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/24/2021] [Accepted: 07/27/2021] [Indexed: 02/08/2023]
Abstract
Neonatal sepsis accounts for significant morbidity and mortality, particularly among premature infants in the Neonatal Intensive Care Unit. Abnormal vital sign patterns serve as physiomarkers of sepsis and provide early warning of illness before overt clinical decompensation. The systemic inflammatory response to pathogens signals the autonomic nervous system, leading to changes in temperature, respiratory rate, heart rate, and blood pressure. In infants with comorbidities of prematurity, vital sign abnormalities often occur in the absence of infection, which confounds sepsis diagnosis. This review will cover the mechanisms of vital sign changes in neonatal sepsis, including the cholinergic anti-inflammatory pathway mediated by the vagus nerve, which is critical to the host response to infectious and inflammatory insults. We will also review the clinical implications of vital sign changes in neonatal sepsis, including their use in early warning scores and systems to direct clinicians to the bedside of infants with physiologic changes that might be due to sepsis. IMPACT: This manuscript summarizes and reviews the relevant literature on the physiological manifestations of neonatal sepsis and how we monitor and analyze these through vital signs and advanced analytics.
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Affiliation(s)
- Brynne A Sullivan
- Division of Neonatology, Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, USA.
| | - Karen D Fairchild
- Division of Neonatology, Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, USA
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9
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Peripheral immune cells and perinatal brain injury: a double-edged sword? Pediatr Res 2022; 91:392-403. [PMID: 34750522 PMCID: PMC8816729 DOI: 10.1038/s41390-021-01818-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 08/24/2021] [Accepted: 09/14/2021] [Indexed: 01/07/2023]
Abstract
Perinatal brain injury is the leading cause of neurological mortality and morbidity in childhood ranging from motor and cognitive impairment to behavioural and neuropsychiatric disorders. Various noxious stimuli, including perinatal inflammation, chronic and acute hypoxia, hyperoxia, stress and drug exposure contribute to the pathogenesis. Among a variety of pathological phenomena, the unique developing immune system plays an important role in the understanding of mechanisms of injury to the immature brain. Neuroinflammation following a perinatal insult largely contributes to evolution of damage to resident brain cells, but may also be beneficial for repair activities. The present review will focus on the role of peripheral immune cells and discuss processes involved in neuroinflammation under two frequent perinatal conditions, systemic infection/inflammation associated with encephalopathy of prematurity (EoP) and hypoxia/ischaemia in the context of neonatal encephalopathy (NE) and stroke at term. Different immune cell subsets in perinatal brain injury including their infiltration routes will be reviewed and critical aspects such as sex differences and maturational stage will be discussed. Interactions with existing regenerative therapies such as stem cells and also potentials to develop novel immunomodulatory targets are considered. IMPACT: Comprehensive summary of current knowledge on the role of different immune cell subsets in perinatal brain injury including discussion of critical aspects to be considered for development of immunomodulatory therapies.
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Zen R, Terashima T, Tsuji S, Katagi M, Ohashi N, Nobuta Y, Higuchi A, Kanai H, Murakami T, Kojima H. Ambient Temperature Is Correlated With the Severity of Neonatal Hypoxic-Ischemic Brain Injury via Microglial Accumulation in Mice. Front Pediatr 2022; 10:883556. [PMID: 35601427 PMCID: PMC9120824 DOI: 10.3389/fped.2022.883556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/14/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND The pathophysiology of neonatal hypoxic-ischemic encephalopathy (HIE) has been studied in several rodent models to develop novel treatments. Although it is well known that high ambient temperature results in severe HIE, the effect of subtle changes in ambient temperature during a hypoxic-ischemic (HI) insult has not been studied. Therefore, in order to clarify the difference of pathophysiological change among the HIE models due to the influence of small changes in chamber temperature, three-step gradual change of 0.5°C each were prepared in ambient temperature during hypoxic exposure. METHODS Blood flow in the left common carotid artery (CCA) of neonatal mice was interrupted using bipolar electronic forceps under general and local anesthesia. The mice were subsequently subjected to 10% hypoxic exposure for 50 min at 36.0, 36.5, or 37.0°C. A control group was also included in the study. The size of the striatum and hippocampus and the volume reduction rate of the hemisphere in the section containing them on the ischemic side were evaluated using microtubule associated protein 2 (MAP2) immunostaining. The accumulation of Iba1-positive cells was investigated to assess inflammation. Additionally, rotarod and open-field tests were performed 2 weeks after HI insult to assess its effect on physiological conditions. RESULTS MAP2 staining revealed that the higher the temperature during hypoxia, the more severe the volume reduction rate in the hemisphere, striatum, and hippocampus. The number of Iba1-positive cells in the ipsilateral lesion gradually increased with increasing temperature, and there was a significant difference in motor function in the 36.5 and 37.0°C groups compared with the sham group. In the open-field tests, there was a significant decrease in performance in the 37.0°C groups compared with the 36.0°C and sham groups. CONCLUSIONS Even a small gradual change of 0.5°C produced a significant difference in pathological and behavioral changes and contributed to the accumulation of Iba1-positive cells. The arrangement of ambient temperature is useful for creating a rodent model with the appropriate severity of the targeted neuropsychological symptoms to establish a novel therapy for HIE.
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Affiliation(s)
- Rika Zen
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Otsu, Japan.,Department of Obstetrics and Gynecology, Shiga University of Medical Science, Otsu, Japan
| | - Tomoya Terashima
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Shunichiro Tsuji
- Department of Obstetrics and Gynecology, Shiga University of Medical Science, Otsu, Japan
| | - Miwako Katagi
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Natsuko Ohashi
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Yuri Nobuta
- Department of Obstetrics and Gynecology, Shiga University of Medical Science, Otsu, Japan
| | - Asuka Higuchi
- Department of Obstetrics and Gynecology, Shiga University of Medical Science, Otsu, Japan
| | - Hirohiko Kanai
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Otsu, Japan
| | - Takashi Murakami
- Department of Obstetrics and Gynecology, Shiga University of Medical Science, Otsu, Japan
| | - Hideto Kojima
- Department of Stem Cell Biology and Regenerative Medicine, Shiga University of Medical Science, Otsu, Japan
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11
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Dias ML, O'Connor KM, Dempsey EM, O'Halloran KD, McDonald FB. Targeting the Toll-like receptor pathway as a therapeutic strategy for neonatal infection. Am J Physiol Regul Integr Comp Physiol 2021; 321:R879-R902. [PMID: 34612068 DOI: 10.1152/ajpregu.00307.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Toll-like receptors (TLRs) are crucial transmembrane receptors that form part of the innate immune response. They play a role in the recognition of various microorganisms and their elimination from the host. TLRs have been proposed as vital immunomodulators in the regulation of multiple neonatal stressors that extend beyond infection such as oxidative stress and pain. The immune system is immature at birth and takes some time to become fully established. As such, babies are especially vulnerable to sepsis at this early stage of life. Findings suggest a gestational age-dependent increase in TLR expression. TLRs engage with accessory and adaptor proteins to facilitate recognition of pathogens and their activation of the receptor. TLRs are generally upregulated during infection and promote the transcription and release of proinflammatory cytokines. Several studies report that TLRs are epigenetically modulated by chromatin changes and promoter methylation upon bacterial infection that have long-term influences on immune responses. TLR activation is reported to modulate cardiorespiratory responses during infection and may play a key role in driving homeostatic instability observed during sepsis. Although complex, TLR signaling and downstream pathways are potential therapeutic targets in the treatment of neonatal diseases. By reviewing the expression and function of key Toll-like receptors, we aim to provide an important framework to understand the functional role of these receptors in response to stress and infection in premature infants.
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Affiliation(s)
- Maria L Dias
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Karen M O'Connor
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Eugene M Dempsey
- Irish Centre for Maternal and Child Health Research, University College Cork, Cork, Ireland.,Department of Pediatrics and Child Health, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland.,Irish Centre for Maternal and Child Health Research, University College Cork, Cork, Ireland
| | - Fiona B McDonald
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland.,Irish Centre for Maternal and Child Health Research, University College Cork, Cork, Ireland
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12
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Long X, Huang Y, He J, Zhang X, Zhou Y, Wei Y, Tang Y, Liu L. Upregulation of miR‑335 exerts protective effects against sepsis‑induced myocardial injury. Mol Med Rep 2021; 24:806. [PMID: 34542164 PMCID: PMC8477184 DOI: 10.3892/mmr.2021.12446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 07/28/2021] [Indexed: 12/12/2022] Open
Abstract
Septicemia is associated with excessive inflammation, oxidative stress and apoptosis, causing myocardial injury that results in high mortality and disability rates worldwide. The abnormal expression of multiple microRNAs (miRNAs/miRs) is associated with more severe sepsis‑induced myocardial injury (SIMI) and miR‑335 has been shown to protect cardiomyocytes from oxidative stress. The present study aimed to investigate the role of miR‑335 in SIMI. An SIMI model was established by cecal ligation and puncture (CLP) in mice. An miRNA‑335 precursor (pre‑miR‑335) was transfected to accelerate miR‑335 expression and an miR‑335 inhibitor (anti‑miR‑335) was used to inhibit miR‑335 expression. CLP or sham surgery was performed on pre‑miR‑335, anti‑miR‑335 and wild‑type mice and miR‑335 expression was determined by reverse transcription‑quantitative PCR. Inflammatory factors (TNF‑α, IL‑6 and IL‑10) and troponin (cTNI), brain natriuretic peptide (BNP), creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) were assessed using commercial kits. Apoptosis was detected by flow cytometry and cardiac function was assessed using a Langendorff isolated cardiac perfusion system. miR‑335 expression was upregulated and an elevation in inflammatory factors and cTNI, BNP, CK, LDH and AST was observed. Compared with the wild‑type control group, pre‑miR‑335 mice treated with CLP exhibited significantly reduced left ventricular development pressure, maximum pressure increased reduction rates, as well as decreased levels of TNF‑α, IL‑6 and IL‑10, myocardial injury and apoptosis; by contrast, these features were amplified in CLP‑treated anti‑miR‑335 mice. In conclusion, the upregulation of miR‑335 exerted ameliorative effects on myocardial injury following sepsis and may indicate a novel therapeutic intervention for SIMI.
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Affiliation(s)
- Xian Long
- Department of Clinic, Medicine School, Changsha Social Work College, Changsha, Hunan 410004, P.R. China
- Department of Pharmacology, Hunan Academy of Chinese Medicine, Changsha, Hunan 410008, P.R. China
- Department of Pharmacology, Hunan Normal University, Changsha, Hunan 410013, P.R. China
| | - Yongpan Huang
- Department of Clinic, Medicine School, Changsha Social Work College, Changsha, Hunan 410004, P.R. China
| | - Jianbin He
- Department of Respiratory and Critical Care Medicine, The First People's Hospital of Huaihua, Affiliated to University of South China, Huaihua, Hunan 418000, P.R. China
| | - Xiang Zhang
- Department of Clinic, Medicine School, Changsha Social Work College, Changsha, Hunan 410004, P.R. China
| | - Yan Zhou
- Department of Clinic, Medicine School, Changsha Social Work College, Changsha, Hunan 410004, P.R. China
| | - Yingmin Wei
- Department of Clinic, Medicine School, Changsha Social Work College, Changsha, Hunan 410004, P.R. China
| | - Ying Tang
- Department of Clinic, Medicine School, Changsha Social Work College, Changsha, Hunan 410004, P.R. China
| | - Lijing Liu
- Department of Clinic, Medicine School, Changsha Social Work College, Changsha, Hunan 410004, P.R. China
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13
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Evaluating Neuroprotective Effects of Uridine, Erythropoietin, and Therapeutic Hypothermia in a Ferret Model of Inflammation-Sensitized Hypoxic-Ischemic Encephalopathy. Int J Mol Sci 2021; 22:ijms22189841. [PMID: 34576001 PMCID: PMC8469346 DOI: 10.3390/ijms22189841] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/04/2021] [Accepted: 09/08/2021] [Indexed: 11/17/2022] Open
Abstract
Perinatal hypoxic-ischemic (HI) brain injury, often in conjunction with an inflammatory insult, is the most common cause of death or disability in neonates. Therapeutic hypothermia (TH) is the standard of care for HI encephalopathy in term and near-term infants. However, TH may not always be available or efficacious, creating a need for novel or adjunctive neurotherapeutics. Using a near-term model of inflammation-sensitized HI brain injury in postnatal day (P) 17 ferrets, animals were randomized to either the control group (n = 43) or the HI-exposed groups: saline vehicle (Veh; n = 42), Ur (uridine monophosphate, n = 23), Epo (erythropoietin, n = 26), or TH (n = 24) to test their respective therapeutic effects. Motor development was assessed from P21 to P42 followed by analysis of cortical anatomy, ex vivo MRI, and neuropathology. HI animals took longer to complete the motor assessments compared to controls, which was exacerbated in the Ur group. Injury resulted in thinned white matter tracts and narrowed cortical sulci and gyri, which was mitigated in Epo-treated animals in addition to normalization of cortical neuropathology scores to control levels. TH and Epo treatment also resulted in region-specific improvements in diffusion parameters on ex vivo MRI; however, TH was not robustly neuroprotective in any behavioral or neuropathological outcome measures. Overall, Ur and TH did not provide meaningful neuroprotection after inflammation-sensitized HI brain injury in the ferret, and Ur appeared to worsen outcomes. By comparison, Epo appears to provide significant, though not complete, neuroprotection in this model.
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14
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Kelly SB, Stojanovska V, Zahra VA, Moxham A, Miller SL, Moss TJM, Hooper SB, Nold MF, Nold-Petry CA, Dean JM, Bennet L, Polglase GR, Gunn AJ, Galinsky R. Interleukin-1 blockade attenuates white matter inflammation and oligodendrocyte loss after progressive systemic lipopolysaccharide exposure in near-term fetal sheep. J Neuroinflammation 2021; 18:189. [PMID: 34465372 PMCID: PMC8408978 DOI: 10.1186/s12974-021-02238-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 08/11/2021] [Indexed: 12/14/2022] Open
Abstract
Background Increased systemic and tissue levels of interleukin (IL)-1β are associated with greater risk of impaired neurodevelopment after birth. In this study, we tested the hypothesis that systemic IL-1 receptor antagonist (Ra) administration would attenuate brain inflammation and injury in near-term fetal sheep exposed to lipopolysaccharide (LPS). Methods Chronically instrumented near-term fetal sheep at 0.85 of gestation were randomly assigned to saline infusion (control, n = 9), repeated LPS infusions (0 h = 300 ng, 24 h = 600 ng, 48 h = 1200 ng, n = 8) or repeated LPS plus IL-1Ra infusions (13 mg/kg infused over 4 h) started 1 h after each LPS infusion (n = 9). Sheep were euthanized 4 days after starting infusions for histology. Results LPS infusions increased circulating cytokines and were associated with electroencephalogram (EEG) suppression with transiently reduced mean arterial blood pressure, and increased carotid artery perfusion and fetal heart rate (P < 0.05 vs. control for all). In the periventricular and intragyral white matter, LPS-exposure increased IL-1β immunoreactivity, numbers of caspase 3+ cells and microglia, reduced astrocyte and olig-2+ oligodendrocyte survival but did not change numbers of mature CC1+ oligodendrocytes, myelin expression or numbers of neurons in the cortex and subcortical regions. IL-1Ra infusions reduced circulating cytokines and improved recovery of EEG activity and carotid artery perfusion. Histologically, IL-1Ra reduced microgliosis, IL-1β expression and caspase-3+ cells, and improved olig-2+ oligodendrocyte survival. Conclusion IL-1Ra improved EEG activity and markedly attenuated systemic inflammation, microgliosis and oligodendrocyte loss following LPS exposure in near-term fetal sheep. Further studies examining the long-term effects on brain maturation are now needed. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02238-4.
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Affiliation(s)
- Sharmony B Kelly
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - Vanesa Stojanovska
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia
| | - Valerie A Zahra
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia
| | - Alison Moxham
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia
| | - Suzanne L Miller
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - Timothy J M Moss
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia
| | - Stuart B Hooper
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - Marcel F Nold
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Paediatrics, Monash University, Melbourne, Victoria, Australia.,Monash Newborn, Monash Children's Hospital, Melbourne, Australia
| | - Claudia A Nold-Petry
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Paediatrics, Monash University, Melbourne, Victoria, Australia
| | - Justin M Dean
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Graeme R Polglase
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia
| | - Alistair J Gunn
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Robert Galinsky
- The Ritchie Centre, Hudson Institute of Medical Research, 27-31 Wright street, Melbourne, Victoria, 3168, Australia. .,Department of Obstetrics and Gynaecology, Monash University, Melbourne, Victoria, Australia.
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15
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Tetorou K, Sisa C, Iqbal A, Dhillon K, Hristova M. Current Therapies for Neonatal Hypoxic-Ischaemic and Infection-Sensitised Hypoxic-Ischaemic Brain Damage. Front Synaptic Neurosci 2021; 13:709301. [PMID: 34504417 PMCID: PMC8421799 DOI: 10.3389/fnsyn.2021.709301] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/19/2021] [Indexed: 12/15/2022] Open
Abstract
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.
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Affiliation(s)
| | | | | | | | - Mariya Hristova
- Perinatal Brain Repair Group, Department of Maternal and Fetal Medicine, UCL Institute for Women’s Health, London, United Kingdom
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16
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Microglia-Mediated Neurodegeneration in Perinatal Brain Injuries. Biomolecules 2021; 11:biom11010099. [PMID: 33451166 PMCID: PMC7828679 DOI: 10.3390/biom11010099] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 12/13/2022] Open
Abstract
Perinatal brain injuries, including encephalopathy related to fetal growth restriction, encephalopathy of prematurity, neonatal encephalopathy of the term neonate, and neonatal stroke, are a major cause of neurodevelopmental disorders. They trigger cellular and molecular cascades that lead in many cases to permanent motor, cognitive, and/or behavioral deficits. Damage includes neuronal degeneration, selective loss of subclasses of interneurons, blocked maturation of oligodendrocyte progenitor cells leading to dysmyelination, axonopathy and very likely synaptopathy, leading to impaired connectivity. The nature and severity of changes vary according to the type and severity of insult and maturation stage of the brain. Microglial activation has been demonstrated almost ubiquitously in perinatal brain injuries and these responses are key cell orchestrators of brain pathology but also attempts at repair. These divergent roles are facilitated by a diverse suite of transcriptional profiles and through a complex dialogue with other brain cell types. Adding to the complexity of understanding microglia and how to modulate them to protect the brain is that these cells have their own developmental stages, enabling them to be key participants in brain building. Of note, not only do microglia help build the brain and respond to brain injury, but they are a key cell in the transduction of systemic inflammation into neuroinflammation. Systemic inflammatory exposure is a key risk factor for poor neurodevelopmental outcomes in preterm born infants. Based on these observations, microglia appear as a key cell target for neuroprotection in perinatal brain injuries. Numerous strategies have been developed experimentally to modulate microglia and attenuate brain injury based on these strong supporting data and we will summarize these.
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17
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Neonatal proinflammatory challenge evokes a microglial response and affects the ratio between subtypes of GABAergic interneurons in the hippocampus of juvenile rats: sex-dependent and sex-independent effects. Brain Struct Funct 2021; 226:563-574. [DOI: 10.1007/s00429-020-02199-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 12/16/2020] [Indexed: 10/22/2022]
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18
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Wu Z, Xue H, Zhang Y, Zhao P. Dexmedetomidine alleviates neurobehavioral impairments and myelination deficits following lipopolysaccharide exposure in early postnatal rats. Life Sci 2020; 263:118556. [PMID: 33038375 DOI: 10.1016/j.lfs.2020.118556] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 09/13/2020] [Accepted: 09/28/2020] [Indexed: 01/22/2023]
Abstract
AIMS White matter injury (WMI) is the main form of brain injury in preterm neonate survivors, and perinatal inflammation is implicated in the pathogenesis of WMI. It has been demonstrated that dexmedetomidine, an anesthetic adjuvant, possesses neuroprotective effects in both preclinical and clinical trials. The present study was conducted to explore whether dexmedetomidine could protect against neurobehavioral impairments and myelination deficits caused by lipopolysaccharide (LPS) exposure in the early postnatal rat brain. MAIN METHODS LPS (2 mg/kg) was intraperitoneally (i.p.) injected in Sprague-Dawley rat pups on postnatal day 2 (P2). Dexmedetomidine (25 μg/kg) or vehicle was given i.p. immediately after LPS injection. STAT3 and p-STAT3 expression were detected by western blot in rat brain 24 h after drug administration. Immunostaining for GFAP to was performed to evaluate astrocytic response at 24 h post-LPS and P14. Neurobehavioral tests (the righting reflex, negative geotaxis, and wire hanging maneuver tests) were performed from P5 to P10. Histological analysis of myelin content was accessed by immunohistochemistry for CNPase and MBP at P14. KEY FINDINGS Our results showed that treatment with dexmedetomidine significantly ameliorated LPS-induced neurobehavioral abnormalities and myelin damage, which is accompanied by suppression of STAT3 activation and reactive astrogliosis. SIGNIFICANCE Dexmedetomidine can alleviate neurobehavioral impairments and myelination deficits after LPS exposure in early postnatal rats, probably by mitigating STAT3-mediated reactive astrogliosis. Our results suggest that dexmedetomidine might be a promising agent to treat brain injury in neonates.
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Affiliation(s)
- Ziyi Wu
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Hang Xue
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Yahan Zhang
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Ping Zhao
- Department of Anesthesiology, Shengjing Hospital of China Medical University, Shenyang 110004, China.
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19
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Serdar M, Kempe K, Herrmann R, Picard D, Remke M, Herz J, Bendix I, Felderhoff-Müser U, Sabir H. Involvement of CXCL1/CXCR2 During Microglia Activation Following Inflammation-Sensitized Hypoxic-Ischemic Brain Injury in Neonatal Rats. Front Neurol 2020; 11:540878. [PMID: 33123073 PMCID: PMC7573390 DOI: 10.3389/fneur.2020.540878] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 08/31/2020] [Indexed: 12/15/2022] Open
Abstract
Background: Microglia are key mediators of inflammation during perinatal brain injury. As shown experimentally after inflammation-sensitized hypoxic ischemic (HI) brain injury, microglia are activated into a pro-inflammatory status 24 h after HI involving the NLRP3 inflammasome pathway. The chemokine (C-X-C motif) ligand 1 (CXCL1), and its cognate receptor, CXCR2, have been shown to be involved in NLRP3 activation, although their specific role during perinatal brain injury remains unclear. In this study we investigated the involvement of CXCL1/CXCR2 in brain tissue and microglia and brain tissue after inflammation-sensitized HI brain injury of newborn rats. Methods: Seven-day old Wistar rat pups were either injected with vehicle (NaCl 0.9%) or E. coli lipopolysaccharide (LPS), followed by left carotid ligation combined with global hypoxia (8% O2 for 50 min). Pups were randomized into four different treatment groups: (1) Sham group (n = 21), (2) LPS only group (n = 20), (3) Veh/HI group (n = 39), and (4) LPS/HI group (n = 42). Twenty-four hours post hypoxia transcriptome and gene expression analysis were performed on ex vivo isolated microglia cells in our model. Additionally protein expression was analyzed in different brain regions at the same time point. Results: Transcriptome analyses showed a significant microglial upregulation of the chemokine CXCL1 and its receptor CXCR2 in the LPS/HI group compared with the other groups. Gene expression analysis showed a significant upregulation of CXCL1 and NLRP3 in microglia cells after inflammation-sensitized hypoxic-ischemic brain injury. Additionally, protein expression of CXCL1 was significantly upregulated in cortex of male pups from the LPS/HI group. Conclusion: These results indicate that the CXCL1/CXCR2 pathway may be involved during pro-inflammatory microglia activation following inflammation-sensitized hypoxic-ischemic brain injury in neonatal rats. This may lead to new treatment options altering CXCR2 activation early after HI brain injury.
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Affiliation(s)
- Meray Serdar
- Department of Pediatrics I/Neonatology and Experimental Perinatal Neurosciences, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Karina Kempe
- Department of Pediatrics I/Neonatology and Experimental Perinatal Neurosciences, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Ralf Herrmann
- Department of Pediatrics I/Neonatology and Experimental Perinatal Neurosciences, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Daniel Picard
- Department of Pediatric Oncology, Hematology, and Clinical Immunology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Marc Remke
- Department of Pediatric Oncology, Hematology, and Clinical Immunology, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
| | - Josephine Herz
- Department of Pediatrics I/Neonatology and Experimental Perinatal Neurosciences, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Ivo Bendix
- Department of Pediatrics I/Neonatology and Experimental Perinatal Neurosciences, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Ursula Felderhoff-Müser
- Department of Pediatrics I/Neonatology and Experimental Perinatal Neurosciences, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Hemmen Sabir
- Department of Pediatrics I/Neonatology and Experimental Perinatal Neurosciences, University Hospital Essen, University Duisburg-Essen, Essen, Germany.,Department of Neonatology and Pediatric Intensive Care, Children's Hospital University of Bonn, Bonn, Germany.,German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
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20
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Li W, Luo S, Wan C. Characterization of fever and sickness behavior regulated by cytokines during infection. BEHAVIOUR 2020. [DOI: 10.1163/1568539x-bja10028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
In response to invasion of pathogens, hosts present fever and a series of behavioural changes including reduced grooming, reduction of foraging, decreased locomotion, withdrawing from social activities and reproductive process, which are collectively termed sickness behaviour. Fever as well as sickness behaviour are adaptive and benefit the host to reduce pathology caused by infections and opportunity costs for time away from foraging, reproduction and predator avoidance. Antipathogenic fever and sickness behaviour are mediated proximately by cytokines including pro- and anti-inflammatory cytokines. Pro-inflammation cytokines trigger these sickness responses, while anti-inflammatory cytokines constrain these responses and prevent damage to host from exaggerated responses. The present study reviews the characterization of fever and sickness behaviour regulated by cytokines during infection.
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Affiliation(s)
- Weiran Li
- aDepartment of Pediatrics, West China Second University Hospital, Sichuan University, No 20, 3rd section of Renmin South Road, Chengdu 610041, P.R. China
- bKey Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu 610041, P.R. China
| | - Shuanghong Luo
- aDepartment of Pediatrics, West China Second University Hospital, Sichuan University, No 20, 3rd section of Renmin South Road, Chengdu 610041, P.R. China
- bKey Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu 610041, P.R. China
| | - Chaomin Wan
- aDepartment of Pediatrics, West China Second University Hospital, Sichuan University, No 20, 3rd section of Renmin South Road, Chengdu 610041, P.R. China
- bKey Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu 610041, P.R. China
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21
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Pires JM, Foresti ML, Silva CS, Rêgo DB, Calió ML, Mosini AC, Nakamura TKE, Leslie ATF, Mello LE. Lipopolysaccharide-Induced Systemic Inflammation in the Neonatal Period Increases Microglial Density and Oxidative Stress in the Cerebellum of Adult Rats. Front Cell Neurosci 2020; 14:142. [PMID: 32581717 PMCID: PMC7283979 DOI: 10.3389/fncel.2020.00142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/28/2020] [Indexed: 01/09/2023] Open
Abstract
Inflammatory processes occurring in the perinatal period may affect different brain regions, resulting in neurologic sequelae. Injection of lipopolysaccharide (LPS) at different neurodevelopmental stages produces long-term consequences in several brain structures, but there is scarce evidence regarding alterations in the cerebellum. The aim of this study was to evaluate the long-term consequences on the cerebellum of a systemic inflammatory process induced by neonatal LPS injection. For this, neonatal rats were randomly assigned to three different groups: naïve, sham, and LPS. Saline (sham group) or LPS solution (1 mg/kg) was intraperitoneally injected on alternate postnatal days (PN) PN1, PN3, PN5, and PN7. Spontaneous activity was evaluated with the open field test in adulthood. The cerebellum was evaluated for different parameters: microglial and Purkinje cell densities, oxidative stress levels, and tumor necrosis factor alpha (TNF-α) mRNA expression. Our results show that administration of LPS did not result in altered spontaneous activity in adult animals. Our data also indicate increased oxidative stress in the cerebellum, as evidenced by an increase in superoxide fluorescence by dihydroethidium (DHE) indicator. Stereological analyses indicated increased microglial density in the cerebellum that was not accompanied by Purkinje cell loss or altered TNF-α expression in adult animals. Interestingly, Purkinje cells ectopically positioned in the granular and molecular layers of the cerebellum were observed in animals of the LPS group. Our data suggest that neonatal LPS exposure causes persistent cellular and molecular changes to the cerebellum, indicating the susceptibility of this region to systemic inflammatory insults in infancy. Further investigation of the consequences of these changes and the development of strategies to avoid those should be subject of future studies.
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Affiliation(s)
| | - Maira Licia Foresti
- Physiology Department, Universidade Federal de São Paulo, São Paulo, Brazil.,Instituto D'Or de Pesquisa e Ensino, Rio de Janeiro, Brazil
| | | | | | | | - Amanda Cristina Mosini
- Physiology Department, Universidade Federal de São Paulo, São Paulo, Brazil.,Associação Brasileira de Epilepsia, São Paulo, Brazil
| | | | | | - Luiz Eugênio Mello
- Physiology Department, Universidade Federal de São Paulo, São Paulo, Brazil.,Instituto D'Or de Pesquisa e Ensino, Rio de Janeiro, Brazil
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22
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Late Brain Involvement after Neonatal Immune Activation. BIOMED RESEARCH INTERNATIONAL 2019; 2019:9573248. [PMID: 31467920 PMCID: PMC6699266 DOI: 10.1155/2019/9573248] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 06/07/2019] [Indexed: 01/18/2023]
Abstract
The neonatal immune system is still immature, which makes it more susceptible to the infectious agents. Neonatal immune activation is associated with increased permeability of the blood-brain barrier, causing an inflammatory cascade in the CNS and altering behavioral and neurochemical parameters. One of the hypotheses that has been studied is that neuroinflammation may be involved in neurodegenerative processes, such as Alzheimer's disease (AD). We evaluate visuospatial memory, cytokines levels, and the expression of tau and GSK-3β proteins in hippocampus and cortex of animals exposed to neonatal endotoxemia. C57BL/6 mice aging two days received a single injection of subcutaneous lipopolysaccharide (LPS). At 60,120, and 180 days of age, visual-spatial memory was evaluated and the hippocampus and cortex were dissected to evaluate the cytokines levels and expression of tau and GSK-3β proteins. The animals exposed to LPS in the neonatal period present with visuospatial memory impairment at 120 and 180 days of age. Here there was an increase of TNF-α and IL-1β levels in the hippocampus and cortex only at 60 days of age. Here there was an increase in the expression of GSK-3β in hippocampus of the animals at 60, 120, and 180 days of age. In the cortex, this increase occurred in the 120 and 180 days of age. Tau protein expression was high in hippocampus and cortex at 120 days of age and in hippocampus at 180 days of age. The data observed show that neonatal immune activation may be associated with visuospatial memory impairment, neuroinflammation, and increased expression of GSK-3β and Tau proteins in the long term.
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23
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Serdar M, Kempe K, Rizazad M, Herz J, Bendix I, Felderhoff-Müser U, Sabir H. Early Pro-inflammatory Microglia Activation After Inflammation-Sensitized Hypoxic-Ischemic Brain Injury in Neonatal Rats. Front Cell Neurosci 2019; 13:237. [PMID: 31178702 PMCID: PMC6543767 DOI: 10.3389/fncel.2019.00237] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/09/2019] [Indexed: 12/18/2022] Open
Abstract
Background: Perinatal asphyxia, leading to neonatal encephalopathy, is one of the leading causes for child mortality and long-term morbidities. Neonatal encephalopathy rates are significantly increased in newborns with perinatal infection. Therapeutic hypothermia is only neuroprotective in 50% of cooled asphyxiated newborns. As shown experimentally, cooling has failed to be neuroprotective after inflammation-sensitized hypoxic ischemic (HI) brain injury. Microglia are thought to be key players after inflammation-sensitized HI brain injury. We performed this study investigating early microglia phenotype polarization in our newborn animal model of inflammation-sensitized HI brain injury, better understanding the underlying pathophysiological processes. Methods: Seven days old Wistar rat pups were injected with either vehicle (NaCl 0.9%) or E. coli lipopolysaccharide (LPS), followed by left carotid ligation combined with global hypoxia inducing a mild unilateral hypoxic-ischemic injury. Pups were randomized to (1) Sham group (n = 41), (2) LPS only group (n = 37), (3) Veh/HI group (n = 56), and (4) LPS/HI group (n = 79). On postnatal days 8 and 14 gene-expression analysis or immunohistochemistry was performed describing early microglia polarization in our model. Results: We confirmed that LPS pre-sensitization significantly increases brain area loss and induced microglia activation and neuronal injury after mild hypoxia-ischemia. Additionally, we show that microglia upregulate pro-inflammatory genes involving NLRP-3 inflammasome gene expression 24 h after inflammation-sensitized hypoxic-ischemic brain injury. Conclusion: These results demonstrate that microglia are early key mediators of the inflammatory response following inflammation-sensitized HI brain injury and that they polarize into a predominant pro-inflammatory phenotype 24 h post HI. This may lead to new treatment options altering microglia phenotype polarization early after HI brain injury.
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Affiliation(s)
- Meray Serdar
- Department of Pediatrics I, Neonatology and Experimental Perinatal Neuroscience, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Karina Kempe
- Department of Pediatrics I, Neonatology and Experimental Perinatal Neuroscience, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Mandana Rizazad
- Department of Pediatrics I, Neonatology and Experimental Perinatal Neuroscience, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Josephine Herz
- Department of Pediatrics I, Neonatology and Experimental Perinatal Neuroscience, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Ivo Bendix
- Department of Pediatrics I, Neonatology and Experimental Perinatal Neuroscience, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Ursula Felderhoff-Müser
- Department of Pediatrics I, Neonatology and Experimental Perinatal Neuroscience, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Hemmen Sabir
- Department of Pediatrics I, Neonatology and Experimental Perinatal Neuroscience, University Hospital Essen, University Duisburg-Essen, Essen, Germany
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children’s Hospital Düsseldorf, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
- Department of Neonatology and Pediatric Intensive Care, Children’s Hospital, University of Bonn, Bonn, Germany
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Wood T, Moralejo D, Corry K, Snyder JM, Traudt C, Curtis C, Nance E, Parikh P, Juul SE. A Ferret Model of Encephalopathy of Prematurity. Dev Neurosci 2019; 40:475-489. [PMID: 31079096 PMCID: PMC6658350 DOI: 10.1159/000498968] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/18/2019] [Indexed: 12/14/2022] Open
Abstract
There is an ongoing need for relevant animal models in which to test therapeutic interventions for infants with neurological sequelae of prematurity. The ferret is an attractive model species as it has a gyrified brain with a white-to-gray matter ratio similar to that in the human brain. A model of encephalopathy of prematurity was developed in postnatal day 10 (P10) ferret kits, considered to be developmentally equivalent to infants of 24-26 weeks' gestation. Cross-fostered P10 ferret kits received 5 mg/kg of lipopolysaccharide (LPS) before undergoing consecutive hypoxia-hyperoxia-hypoxia (60 min at 9%, 120 min at 60%, and 30 min at 9%). Control animals received saline vehicle followed by normoxia. The development of basic reflexes (negative geotaxis, cliff aversion, and righting) as well as gait coordination on an automated catwalk were assessed between P28 and P70, followed by ex vivo magnetic resonance imaging (MRI) and immunohistochemical analysis. Compared to controls, injured animals had slower overall reflex development between P28 and P40, as well as smaller hind-paw areas consistent with "toe walking" at P42. Injured animals also displayed significantly greater lateral movement during CatWalk assessment as a result of reduced gait coordination. Ex vivo MRI showed widespread white-matter hyperintensity on T2-weighted imaging as well as altered connectivity patterns. This coincided with white-matter dysmaturation characterized by increased intensity of myelin basic protein staining, white-matter thinning, and loss of oligodendrocyte transcription factor 2 (OLIG2)-positive cells. These results suggest both pathological and motor deficits consistent with premature white-matter injury. This newborn ferret model can therefore provide an additional platform to assess potential therapies before translation to human clinical trials.
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Affiliation(s)
- Thomas Wood
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, Washington, USA,
| | - Daniel Moralejo
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Kylie Corry
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Jessica M Snyder
- Department of Comparative Medicine, University of Washington, Seattle, Washington, USA
| | - Christopher Traudt
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Chad Curtis
- Department of Chemical Engineering, University of Washington, Seattle, Washington, USA
| | - Elizabeth Nance
- Department of Chemical Engineering, University of Washington, Seattle, Washington, USA
| | - Pratik Parikh
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Sandra E Juul
- Division of Neonatology, Department of Pediatrics, University of Washington, Seattle, Washington, USA
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25
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McMillin M, Grant S, Frampton G, Petrescu AD, Williams E, Jefferson B, Thomas A, Brahmaroutu A, DeMorrow S. Elevated circulating TGFβ1 during acute liver failure activates TGFβR2 on cortical neurons and exacerbates neuroinflammation and hepatic encephalopathy in mice. J Neuroinflammation 2019; 16:69. [PMID: 30940161 PMCID: PMC6446280 DOI: 10.1186/s12974-019-1455-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 03/18/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Acute liver failure resulting from drug-induced liver injury can lead to the development of neurological complications called hepatic encephalopathy (HE). Hepatic transforming growth factor beta 1 (TGFβ1) is upregulated due to liver failure in mice and inhibiting circulating TGFβ reduced HE progression. However, the specific contributions of TGFβ1 on brain cell populations and neuroinflammation during HE are not known. Therefore, the aim of this study was to characterize hepatic and brain TGFβ1 signaling during acute liver failure and its contribution to HE progression using a combination of pharmacological and genetic approaches. METHODS C57Bl/6 or neuron-specific transforming growth factor beta receptor 2 (TGFβR2) null mice (TGFβR2ΔNeu) were treated with azoxymethane (AOM) to induce acute liver failure and HE. The activity of circulating TGFβ1 was inhibited in C57Bl/6 mice via injection of a neutralizing antibody against TGFβ1 (anti-TGFβ1) prior to AOM injection. In all mouse treatment groups, liver damage, neuroinflammation, and neurological deficits were assessed. Inflammatory signaling between neurons and microglia were investigated in in vitro studies through the use of pharmacological inhibitors of TGFβ1 signaling in HT-22 and EOC-20 cells. RESULTS TGFβ1 was expressed and upregulated in the liver following AOM injection. Pharmacological inhibition of TGFβ1 after AOM injection attenuated neurological decline, microglia activation, and neuroinflammation with no significant changes in liver damage. TGFβR2ΔNeu mice administered AOM showed no effect on liver pathology but significantly reduced neurological decline compared to control mice. Microglia activation and neuroinflammation were attenuated in mice with pharmacological inhibition of TGFβ1 or in TGFβR2ΔNeu mice. TGFβ1 increased chemokine ligand 2 (CCL2) and decreased C-X3-C motif ligand 1 (CX3CL1) expression in HT-22 cells and reduced interleukin-1 beta (IL-1ß) expression, tumor necrosis factor alpha (TNFα) expression, and phagocytosis activity in EOC-20 cells. CONCLUSION Increased circulating TGFβ1 following acute liver failure results in activation of neuronal TGFβR2 signaling, driving neuroinflammation and neurological decline during AOM-induced HE.
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Affiliation(s)
- Matthew McMillin
- Central Texas Veterans Health Care System, Temple, TX, USA.,Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, USA.,Department of Internal Medicine, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
| | - Stephanie Grant
- Central Texas Veterans Health Care System, Temple, TX, USA.,Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, USA.,Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
| | - Gabriel Frampton
- Central Texas Veterans Health Care System, Temple, TX, USA.,Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, USA.,Department of Internal Medicine, Dell Medical School, The University of Texas at Austin, Austin, TX, USA
| | - Anca D Petrescu
- Central Texas Veterans Health Care System, Temple, TX, USA.,Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, USA.,Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
| | - Elaina Williams
- Central Texas Veterans Health Care System, Temple, TX, USA.,Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, USA.,Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
| | - Brandi Jefferson
- Central Texas Veterans Health Care System, Temple, TX, USA.,Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, USA
| | - Alison Thomas
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, USA
| | - Ankita Brahmaroutu
- Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, USA
| | - Sharon DeMorrow
- Central Texas Veterans Health Care System, Temple, TX, USA. .,Department of Medical Physiology, College of Medicine, Texas A&M University Health Science Center, Temple, TX, USA. .,Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA. .,Department of Internal Medicine, Dell Medical School, The University of Texas at Austin, Austin, TX, USA.
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26
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Falck M, Osredkar D, Maes E, Flatebø T, Wood TR, Walløe L, Sabir H, Thoresen M. Hypothermia Is Neuroprotective after Severe Hypoxic-Ischaemic Brain Injury in Neonatal Rats Pre-Exposed to PAM3CSK4. Dev Neurosci 2018; 40:189-197. [PMID: 29860252 DOI: 10.1159/000487798] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/15/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Preclinical research on the neuroprotective effect of hypothermia (HT) after perinatal asphyxia has shown variable results, depending on comorbidities and insult severity. Exposure to inflammation increases vulnerability of the neonatal brain to hypoxic-ischaemic (HI) injury, and could be one explanation for those neonates whose injury is unexpectedly severe. Gram-negative type inflammatory exposure by lipopolysaccharide administration prior to a mild HI insult results in moderate brain injury, and hypothermic neuroprotection is negated. However, the neuroprotective effect of HT is fully maintained after gram-positive type inflammatory exposure by PAM3CSK4 (PAM) pre-administration in the same HI model. Whether HT is neuroprotective in severe brain injury with gram-positive inflammatory pre-exposure has not been investigated. METHODS 59 seven-day-old rat pups were subjected to a unilateral HI insult, with left carotid artery ligation followed by 90-min hypoxia (8% O2 at Trectal 36°C). An additional 196 pups received intraperitoneal 0.9% saline (control) or PAM1 mg/kg, 8 h before undergoing the same HI insult. After randomisation to 5 h normothermia (NT37°C) or HT32°C, pups survived 1 week before they were sacrificed by perfusion fixation. Brains were harvested for hemispheric and hippocampal area loss analyses at postnatal day 14, as well as immunostaining for neuron count in the HIP CA1 region. RESULTS Normothermic PAM animals (PAM-NT) had a comparable median area loss (hemispheric: 60% [95% CI 33-66]; hippocampal: 61% [95% CI 29-67]) to vehicle animals (Veh-NT) (hemispheric: 58% [95% CI 11-64]; hippocampal: 60% [95% CI 19-68]), which is defined as severe brain injury. Furthermore, mortality was low and similar in the two groups (Veh-NT 4.5% vs. PAM-NT 6.6%). HT reduced hemispheric and hippocampal injury in the Veh group by 13 and 28%, respectively (hemispheric: p = 0.048; hippocampal: p = 0.042). HT also provided neuroprotection in the PAM group, reducing hemispheric injury by 22% (p = 0.03) and hippocampal injury by 37% (p = 0.027). CONCLUSION In these experiments with severe brain injury, Toll-like receptor-2 triggering prior to HI injury does not have an additive injurious effect, and there is a small but significant neuroprotective effect of HT. HT appears to be neuroprotective over a continuum of injury severity in this model, and the effect size tapers off with increasing area loss. Our results indicate that gram-positive inflammatory exposure prior to HI injury does not negate the neuroprotective effect of HT in severe brain injury.
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Affiliation(s)
- Mari Falck
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Damjan Osredkar
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Department of Paediatric Neurology, University Children's Hospital Ljubljana, Ljubljana, Slovenia
| | - Elke Maes
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Torun Flatebø
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Thomas Ragnar Wood
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Lars Walløe
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Hemmen Sabir
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Department of General Paediatrics, Neonatology and Paediatric Cardiology, University Children's Hospital, Heinrich Heine University, Düsseldorf, Germany.,Department of Pediatrics I/Neonatology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Marianne Thoresen
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Neonatal Neuroscience, Translational Medicine, University of Bristol, Bristol, United Kingdom
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