Persistent cortical and white matter inflammation after therapeutic hypothermia for ischemia in near-term fetal sheep.
Electroencephalogram
Gitter cells
Hypoxia-ischemia
Microglial phenotype
Neuroinflammation
Therapeutic hypothermia
Journal
Journal of neuroinflammation
ISSN: 1742-2094
Titre abrégé: J Neuroinflammation
Pays: England
ID NLM: 101222974
Informations de publication
Date de publication:
11 Jun 2022
11 Jun 2022
Historique:
received:
15
12
2021
accepted:
23
05
2022
entrez:
11
6
2022
pubmed:
12
6
2022
medline:
15
6
2022
Statut:
epublish
Résumé
Therapeutic hypothermia significantly improves outcomes after moderate-severe hypoxic-ischemic encephalopathy (HIE), but it is partially effective. Although hypothermia is consistently associated with reduced microgliosis, it is still unclear whether it normalizes microglial morphology and phenotype. Near-term fetal sheep (n = 24) were randomized to sham control, ischemia-normothermia, or ischemia-hypothermia. Brain sections were immunohistochemically labeled to assess neurons, microglia and their interactions with neurons, astrocytes, myelination, and gitter cells (microglia with cytoplasmic lipid granules) 7 days after cerebral ischemia. Lesions were defined as areas with complete loss of cells. RNAscope Ischemia-normothermia was associated with severe loss of neurons and myelin (p < 0.05), with extensive lesions, astrogliosis and microgliosis with a high proportion of gitter cells (p < 0.05). Microglial wrapping of neurons was present in both the ischemia groups. Hypothermia improved neuronal survival, suppressed lesions, gitter cells and gliosis (p < 0.05), and attenuated the reduction of myelin area fraction. The "M1" marker CD86 and "M2" marker CD206 were upregulated after ischemia. Hypothermia partially suppressed CD86 in the cortex only (p < 0.05), but did not affect CD206. Hypothermia prevented lesions after cerebral ischemia, but only partially suppressed microglial wrapping and M1 marker expression. These data support the hypothesis that persistent upregulation of injurious microglial activity may contribute to partial neuroprotection after hypothermia, and that immunomodulation after rewarming may be an important therapeutic target.
Sections du résumé
BACKGROUND
BACKGROUND
Therapeutic hypothermia significantly improves outcomes after moderate-severe hypoxic-ischemic encephalopathy (HIE), but it is partially effective. Although hypothermia is consistently associated with reduced microgliosis, it is still unclear whether it normalizes microglial morphology and phenotype.
METHODS
METHODS
Near-term fetal sheep (n = 24) were randomized to sham control, ischemia-normothermia, or ischemia-hypothermia. Brain sections were immunohistochemically labeled to assess neurons, microglia and their interactions with neurons, astrocytes, myelination, and gitter cells (microglia with cytoplasmic lipid granules) 7 days after cerebral ischemia. Lesions were defined as areas with complete loss of cells. RNAscope
RESULTS
RESULTS
Ischemia-normothermia was associated with severe loss of neurons and myelin (p < 0.05), with extensive lesions, astrogliosis and microgliosis with a high proportion of gitter cells (p < 0.05). Microglial wrapping of neurons was present in both the ischemia groups. Hypothermia improved neuronal survival, suppressed lesions, gitter cells and gliosis (p < 0.05), and attenuated the reduction of myelin area fraction. The "M1" marker CD86 and "M2" marker CD206 were upregulated after ischemia. Hypothermia partially suppressed CD86 in the cortex only (p < 0.05), but did not affect CD206.
CONCLUSIONS
CONCLUSIONS
Hypothermia prevented lesions after cerebral ischemia, but only partially suppressed microglial wrapping and M1 marker expression. These data support the hypothesis that persistent upregulation of injurious microglial activity may contribute to partial neuroprotection after hypothermia, and that immunomodulation after rewarming may be an important therapeutic target.
Identifiants
pubmed: 35690757
doi: 10.1186/s12974-022-02499-7
pii: 10.1186/s12974-022-02499-7
pmc: PMC9188214
doi:
Types de publication
Journal Article
Randomized Controlled Trial, Veterinary
Langues
eng
Sous-ensembles de citation
IM
Pagination
139Subventions
Organisme : Health Research Council of New Zealand
ID : 17/601
Organisme : Health Research Council of New Zealand
ID : 16/003
Organisme : Marsden Fund
ID : 17-UOA232
Informations de copyright
© 2022. The Author(s).
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