Interleukin-1 blockade attenuates white matter inflammation and oligodendrocyte loss after progressive systemic lipopolysaccharide exposure in near-term fetal sheep

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.

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Interleukin-1 Blockade Attenuates White Matter Inflammation and Oligodendrocyte Loss After Progressive Systematic Lipopolysaccharide Exposure in Near-Term Fetal Sheep

10.21203/rs.3.rs-202147/v1 ◽

2021 ◽

Author(s):

Sharmony B. Kelly ◽

Vanesa Stojanovska ◽

Valerie Zahra ◽

Alison Moxham ◽

Suzanne L Miller ◽

...

Keyword(s):

White Matter ◽

Carotid Artery ◽

Interleukin 1 ◽

Brain Maturation ◽

Saline Control ◽

Fetal Sheep ◽

Eeg Activity ◽

Arterial Blood ◽

Near Term ◽

Artery Perfusion

Abstract BackgroundIncreased 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 can attenuate neuroinflammation and injury in near-term fetal sheep exposed to lipopolysaccharide (LPS). MethodsChronically instrumented near-term fetal sheep at 0.85 of gestation were randomly assigned to saline (control, n=9), LPS infusions (0 h=300 ng, 24 h=600 ng, 48 h=1200 ng, n=8) or LPS plus 3 infusions of IL-1Ra (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.ResultsLPS infusions 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). In the periventricular and intragyral white matter, LPS-exposure increased IL-1β immunoreactivity, apoptosis and microglial activation, and reduced astrocyte and total oligodendrocyte survival, but did not change 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 apoptosis, and improved total oligodendrocyte survival.ConclusionIL-1Ra improved EEG activity and markedly attenuated systemic inflammation, microgliosis and oligodendrocyte loss, but did not improve survival of astrocytes after LPS-induced inflammation in near-term fetal sheep. Further studies of long term brain maturation are now needed.

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Window of Opportunity of Cerebral Hypothermia for Postischemic White Matter Injury in the Near-Term Fetal Sheep

Journal of Cerebral Blood Flow & Metabolism ◽

10.1097/01.wcb.0000123904.17746.92 ◽

2004 ◽

Vol 24 (8) ◽

pp. 877-886 ◽

Cited By ~ 80

Author(s):

Vincent Roelfsema ◽

Laura Bennet ◽

Sherly George ◽

David Wu ◽

Jian Guan ◽

...

Keyword(s):

White Matter ◽

Cerebral Ischemia ◽

Caspase 3 ◽

Basic Protein ◽

White Matter Injury ◽

Window Of Opportunity ◽

Reactive Microglia ◽

Fetal Sheep ◽

Near Term ◽

Protein Density

Postresuscitation cerebral hypothermia is consistently neuroprotective in experimental preparations; however, its effects on white matter injury are poorly understood. Using a model of reversible cerebral ischemia in unanesthetized near-term fetal sheep, we examined the effects of cerebral hypothermia (fetal extradural temperature reduced from 39.4±0.1°C to between 30 and 33°C), induced at different times after reperfusion and continued for 72 hours after ischemia, on injury in the parasagittal white matter 5 days after ischemia. Cooling started within 90 minutes of reperfusion was associated with a significant increase in bioactive oligodendrocytes in the intragyral white matter compared with sham cooling (41±20 vs 18±11 per field, P < 0.05), increased myelin basic protein density and reduced expression of activated caspase-3 (14±12 vs 91±51, P < 0.05). Reactive microglia were profoundly suppressed compared with sham cooling (4±6 vs 38±18 per field, P < 0.05) with no effect on numbers of astrocytes. When cooling was delayed until 5.5 hours after reperfusion there was no significant effect on loss of oligodendrocytes (24±12 per field). In conclusion, hypothermia can effectively protect white matter after ischemia, but only if initiated early after the insult. Protection was closely associated with reduced expression of both activated caspase-3 and of reactive microglia.

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Insulin-Like Growth Factor (IGF)-1 Suppresses Oligodendrocyte Caspase-3 Activation and Increases Glial Proliferation after Ischemia in Near-Term Fetal Sheep

Journal of Cerebral Blood Flow & Metabolism ◽

10.1097/01.wcb.0000067720.12805.6f ◽

2003 ◽

Vol 23 (6) ◽

pp. 739-747 ◽

Cited By ~ 84

Author(s):

Yun Cao ◽

Alistair Jan Gunn ◽

Laura Bennet ◽

David Wu ◽

Sherly George ◽

...

Keyword(s):

White Matter ◽

Growth Factor ◽

Caspase 3 ◽

Dependent Manner ◽

Insulin Like Growth Factor ◽

Fetal Sheep ◽

Reactive Glia ◽

Glial Proliferation ◽

Bilateral Carotid ◽

Near Term

Insulin-like growth factor (IGF-1) markedly increases myelination and glial numbers in white matter after ischemia in near-term fetal sheep; however, it is unclear whether this is due to reduced cell loss or increased secondary proliferation. Brain injury was induced in near-term fetal sheep by 30 minutes of bilateral carotid artery occlusion. Ninety minutes after the occlusion, fetuses were given, intracerebroventricularly, either a single dose of IGF-1 (either 3 or 30 μg), or 3 μg followed by 3 μg over 24 hours (3 + 3 μg). White matter was assessed 4 days after reperfusion. Three micrograms, but not 30 μg of IGF-1 prevented loss of oligodendrocytes and myelin basic protein density ( P < 0.001) compared to the vehicle-treated ischemia controls. No additional effect was observed in the 3 + 3 μg group. IGF-1 treatment was associated with reduced caspase-3 activation and increased glial proliferation in a similar dose-dependent manner. Caspase-3 was only expressed in oligodendrocytes that showed apoptotic morphology. Proliferating cell nuclear antigen co-localized with both oligodendrocytes and astrocytes and microglia. Thus, increased oligodendrocyte numbers after IGF-1 treatment is partly due to suppression of apoptosis, and partly to increased proliferation. In contrast, the increase in reactive glia was related only to proliferation. Speculatively, reactive glia may partly mediate IGF-1 white matter protection.

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Peripheral chemoreflex activation and cardiac function during hypoxemia in near term fetal sheep without placental compromise

Journal of Applied Physiology ◽

10.1152/japplphysiol.01111.2020 ◽

2021 ◽

Author(s):

Juulia Lantto ◽

Tiina Erkinaro ◽

Mervi Haapsamo ◽

Heikki Huhta ◽

Leena Alanne ◽

...

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Carotid Artery ◽

Arterial Oxygen ◽

Sheep Model ◽

Fetal Sheep ◽

Descending Aorta ◽

Arterial Blood ◽

Near Term ◽

Peripheral Chemoreflex

A drop in arterial oxygen content activates fetal chemoreflex including an increase in sympathetic activity leading to peripheral vasoconstriction and redistribution of blood flow to protect the brain, myocardium, and adrenal glands. By using a chronically instrumented fetal sheep model with intact placental circulation at near-term gestation, we investigated the relationship between peripheral chemoreflex activation induced by hypoxemia and central hemodynamics. 17 Åland landrace sheep fetuses at 115-128/145 gestational days were instrumented. Carotid artery was catheterised in 10 fetuses and descending aorta in 7 fetuses. After a 4-day recovery, baseline measurements of fetal arterial blood pressures, blood gas values, and fetal cardiovascular hemodynamics by pulsed Doppler ultrasonography were obtained under isoflurane-anesthesia. Comparable data to baseline was collected 10 (acute hypoxemia) and 60 minutes (prolonged hypoxemia) after maternal hypo-oxygenation to saturation level of 70-80% was achieved. During prolonged hypoxemia, pH and base excess (BE) were lower, and lactate levels higher in the descending aorta than in the carotid artery. During hypoxemia mean arterial blood pressure (MAP) in the descending aorta increased, while in the carotid artery MAP decreased. In addition, right pulmonary artery pulsatility index values increased, and the diastolic component in the aortic isthmus blood flow velocity waveform became more retrograde. Both fetal ventricular cardiac outputs were maintained even during prolonged hypoxemia when significant fetal metabolic acidemia developed. Fetal chemoreflex activation induced by hypoxemia decreased the perfusion pressure in the cerebral circulation. Fetal weight-indexed LVCO or AoI Net Flow-ratio did not correlate with a drop in carotid artery blood pressure.

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Magnesium sulfate reduces EEG activity but is not neuroprotective after asphyxia in preterm fetal sheep

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x16655548 ◽

2016 ◽

Vol 37 (4) ◽

pp. 1362-1373 ◽

Cited By ~ 19

Author(s):

Robert Galinsky ◽

Vittoria Draghi ◽

Guido Wassink ◽

Joanne O Davidson ◽

Paul P Drury ◽

...

Keyword(s):

White Matter ◽

Magnesium Sulfate ◽

Marked Reduction ◽

Neuronal Loss ◽

Periventricular White Matter ◽

Fetal Sheep ◽

Eeg Activity ◽

Fetal Movements ◽

To Receive ◽

Anticonvulsant Effects

Magnesium sulfate is now widely recommended for neuroprotection for preterm birth; however, this has been controversial because there is little evidence that magnesium sulfate is neuroprotective. Preterm fetal sheep (104 days gestation; term is 147 days) were randomly assigned to receive sham occlusion (n = 7), i.v. magnesium sulfate (n = 10) or saline (n = 8) starting 24 h before asphyxia until 24 h after asphyxia. Sheep were killed 72 h after asphyxia. Magnesium sulfate infusion reduced electroencephalograph power and fetal movements before asphyxia. Magnesium sulfate infusion did not affect electroencephalograph power during recovery, but was associated with marked reduction of the post-asphyxial seizure burden (mean ± SD: 34 ± 18 min vs. 107 ± 74 min, P < 0.05). Magnesium sulfate infusion did not affect subcortical neuronal loss. In the intragyral and periventricular white matter, magnesium sulfate was associated with reduced numbers of all (Olig−2+ve) oligodendrocytes in the intragyral (125 ± 23 vs. 163 ± 38 cells/field) and periventricular white matter (162 ± 39 vs. 209 ± 44 cells/field) compared to saline-treated controls ( P < 0.05), but no effect on microglial induction or astrogliosis. In conclusion, a clinically comparable dose of magnesium sulfate showed significant anticonvulsant effects after asphyxia in preterm fetal sheep, but did not reduce asphyxia-induced brain injury and exacerbated loss of oligodendrocytes.

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Differential effects of slow rewarming after cerebral hypothermia on white matter recovery after global cerebral ischemia in near-term fetal sheep

Scientific Reports ◽

10.1038/s41598-019-46505-0 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

V. Draghi ◽

G. Wassink ◽

K. Q. Zhou ◽

L. Bennet ◽

A. J. Gunn ◽

...

Keyword(s):

White Matter ◽

Cerebral Ischemia ◽

Global Cerebral Ischemia ◽

Fetal Sheep ◽

Differential Effects ◽

Near Term

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Human Amnion Epithelial Cells Protect against White Matter Brain Injury after Repeated Endotoxin Exposure in the Preterm Ovine Fetus

Cell Transplantation ◽

10.3727/096368916x693572 ◽

2017 ◽

Vol 26 (4) ◽

pp. 541-553 ◽

Cited By ~ 19

Author(s):

Tamara Yawno ◽

Tharani Sabaretnam ◽

Jingang Li ◽

Courtney Mcdonald ◽

Rebecca Lim ◽

...

Keyword(s):

Brain Injury ◽

White Matter ◽

Epithelial Cells ◽

Fetal Brain ◽

Brain Inflammation ◽

Periventricular White Matter ◽

Fetal Sheep ◽

Human Amnion ◽

Activated Microglia ◽

Amnion Epithelial Cells

Intrauterine inflammation is a significant cause of injury to the developing fetal brain. Using a preterm fetal sheep model of in utero infection, we asked whether human amnion epithelial cells (hAECs) were able to reduce inflammation-induced fetal brain injury. Surgery was undertaken on pregnant sheep at ~105 days gestation (term is 147 days) for implantation of vascular catheters. Lipopolysaccharide (LPS; 150 ng/kg bolus) or saline was administered IV at 109, 110, and 111 days. Sixty million fluorescent-labeled hAECs were administered at 110, 111, and 112 days gestation via the brachial artery catheter. Brains were collected at 114 days for histological assessment. hAECs were observed within the cortex, white matter, and hippocampus. Compared to control lambs, LPS administration was associated with significant and widespread fetal brain inflammation and injury as evidenced by increased number of activated microglia in the periventricular white matter ( p = 0.02), increased pyknosis, cell degeneration ( p = 0.01), and a nonsignificant trend of fewer oligodendrocytes in the subcortical and periventricular white matter. Administration of hAECs to LPS-treated animals was associated with a significant mitigation in both inflammation and injury as evidenced by fewer activated microglia ( p = 0.03) and pyknotic cells ( p = 0.03), significantly more oligodendrocytes in the subcortical and periventricular white matter ( p = 0.01 and 0.02, respectively), and more myelin basic protein-positive cells within the periventricular white matter ( p = 0.02). hAEC administration to fetal sheep exposed to multiple doses of LPS dampens the resultant fetal inflammatory response and mitigates associated brain injury.

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Human Umbilical Cord Blood Therapy Protects Cerebral White Matter from Systemic LPS Exposure in Preterm Fetal Sheep

Developmental Neuroscience ◽

10.1159/000490943 ◽

2018 ◽

Vol 40 (3) ◽

pp. 258-270 ◽

Cited By ~ 13

Author(s):

Madison C.B. Paton ◽

Beth J. Allison ◽

Jingang Li ◽

Michael C. Fahey ◽

Amy E. Sutherland ◽

...

Keyword(s):

Cell Death ◽

Brain Injury ◽

White Matter ◽

Cell Therapy ◽

Cord Blood ◽

Umbilical Cord ◽

Umbilical Cord Blood ◽

Brain Inflammation ◽

Human Umbilical Cord ◽

Fetal Sheep

Background: Infants born preterm following exposure to in utero inflammation/chorioamnionitis are at high risk of brain injury and life-long neurological deficits. In this study, we assessed the efficacy of early intervention umbilical cord blood (UCB) cell therapy in a large animal model of preterm brain inflammation and injury. We hypothesised that UCB treatment would be neuroprotective for the preterm brain following subclinical fetal inflammation. Methods: Chronically instrumented fetal sheep at 0.65 gestation were administered lipopolysaccharide (LPS, 150 ng, 055:B5) intravenously over 3 consecutive days, followed by 100 million human UCB mononuclear cells 6 h after the final LPS dose. Controls were administered saline instead of LPS and cells. Ten days after the first LPS dose, the fetal brain and cerebrospinal fluid were collected for analysis of subcortical and periventricular white matter injury and inflammation. Results: LPS administration increased microglial aggregate size, neutrophil recruitment, astrogliosis and cell death compared with controls. LPS also reduced total oligodendrocyte count and decreased mature myelinating oligodendrocytes. UCB cell therapy attenuated cell death and inflammation, and recovered total and mature oligodendrocytes, compared with LPS. Conclusions: UCB cell treatment following inflammation reduces preterm white matter brain injury, likely mediated via anti-inflammatory actions.

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Delayed intranasal infusion of human amnion epithelial cells improves white matter maturation after asphyxia in preterm fetal sheep

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x17729954 ◽

2017 ◽

Vol 39 (2) ◽

pp. 223-239 ◽

Cited By ~ 19

Author(s):

Lotte G van den Heuij ◽

Mhoyra Fraser ◽

Suzanne L Miller ◽

Graham Jenkin ◽

Euan M Wallace ◽

...

Keyword(s):

White Matter ◽

Epithelial Cells ◽

Cortical Area ◽

Caspase 3 ◽

Specific Treatment ◽

Brain Weight ◽

Fetal Sheep ◽

Human Amnion ◽

White Matter Maturation ◽

Amnion Epithelial Cells

Perinatal hypoxic-ischemic (HI) brain injury remains highly associated with neurodevelopmental disability after preterm birth. There is increasing evidence that disability is linked with impaired white matter maturation, but there is no specific treatment. In this study, we evaluated whether, in preterm fetal sheep, delayed intranasal infusion of human amnion epithelial cells (hAECs) given 1, 3 and 10 days after severe HI, induced by umbilical cord occlusion for 25 min, can restore white matter maturation or reduce delayed cell loss. After 21 days recovery, asphyxia was associated with reduced electroencephalographic (EEG) maturation, brain weight and cortical area, impaired maturation of oligodendrocytes (OLs), no significant loss of total OLs but a marked reduction in immature/mature OLs and reduced myelination. Intranasal infusion of hAECs was associated with improved brain weight and restoration of immature/mature OLs and fractional area of myelin basic protein, with reduced microglia and astrogliosis. Cortical EEG frequency distribution was partially improved, with reduced loss of cortical area, and attenuated cleaved-caspase-3 expression and microgliosis. Neuronal survival in deep grey matter nuclei was improved, with reduced microglia, astrogliosis and cleaved-caspase-3-positive apoptosis. These findings suggest that delayed intranasal hAEC administration has potential to alleviate chronic dysmaturation after perinatal HI.

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