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 can attenuate neuroinflammation 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 (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.
Results
LPS 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.
Conclusion
IL-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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Posted 17 Feb, 2021
On 15 Mar, 2021
Received 28 Feb, 2021
Received 28 Feb, 2021
On 07 Feb, 2021
On 07 Feb, 2021
Received 07 Feb, 2021
Invitations sent on 05 Feb, 2021
On 04 Feb, 2021
On 04 Feb, 2021
On 04 Feb, 2021
On 02 Feb, 2021
Posted 17 Feb, 2021
On 15 Mar, 2021
Received 28 Feb, 2021
Received 28 Feb, 2021
On 07 Feb, 2021
On 07 Feb, 2021
Received 07 Feb, 2021
Invitations sent on 05 Feb, 2021
On 04 Feb, 2021
On 04 Feb, 2021
On 04 Feb, 2021
On 02 Feb, 2021
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 can attenuate neuroinflammation 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 (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.
Results
LPS 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.
Conclusion
IL-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.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6
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