Hypothermia and Rewarming Activate a Macroglial Unfolded Protein Response Independent of Hypoxic-Ischemic Brain Injury in Neonatal Piglets

Jennifer Lee-Summers, Bing Wang, Michael Reyes, Jillian S. Armstrong, Ewa Kulikowicz, Polan Santos, Jeong Hoo Lee, Raymond C Koehler, Lee J Martin

Research output: Contribution to journalArticle

Abstract

Therapeutic hypothermia provides incomplete neuroprotection after hypoxia-ischemia (HI)-induced brain injury in neonates. We previously showed that cortical neuron and white matter apoptosis are promoted by hypothermia and early rewarming in a piglet model of HI. The unfolded protein response (UPR) may be one of the potential mediators of this cell death. Here, neonatal piglets underwent HI or sham surgery followed by 29 h of normothermia, 2 h of normothermia + 27 h of hypothermia or 18 h of hypothermia + rewarming. Piglets recovered for 29 h. Immunohistochemistry for endoplasmic reticulum to nucleus signaling-1 protein (ERN1), a marker of UPR activation, was used to determine the ratios of ERN1+ macroglia and neurons in the motor subcortical white matter and cerebral cortex. The ERN1+ macroglia were immunophenotyped as oligodendrocytes and astrocytes by immunofluorescent colabeling. Temperature (p = 0.046) and HI (p < 0.001) independently affected the ratio of ERN1+ macroglia. In sham piglets, sustained hypothermia (p = 0.011) and rewarming (p = 0.004) increased the ERN1+ macroglia ratio above that in normothermia. HI prior to hypothermia diminished the UPR. Ratios of ERN1+ macroglia correlated with white matter apoptotic profile counts in shams (r = 0.472; p = 0.026), thereby associating UPR activation with white matter apoptosis during hypothermia and rewarming. Accordingly, macroglial cell counts decreased in shams that received sustained hypothermia (p = 0.009) or rewarming (p = 0.007) compared to those in normothermic shams. HI prior to hypothermia neutralized the macroglial cell loss. Neither HI nor temperature affected ERN1+ neuron ratios. In summary, delayed hypothermia and rewarming activate the macroglial UPR, which is associated with white matter apoptosis. HI may decrease the macroglial endoplasmic reticulum stress response after hypothermia and rewarming.

Original languageEnglish (US)
JournalDevelopmental Neuroscience
DOIs
StateAccepted/In press - Sep 14 2016

Fingerprint

Unfolded Protein Response
Rewarming
Hypothermia
Brain Injuries
Ischemia
Apoptosis
Neurons
Induced Hypothermia
Endoplasmic Reticulum Stress
Temperature
Hypoxia
Oligodendroglia
Motor Neurons
Astrocytes
Endoplasmic Reticulum
Cerebral Cortex
Cell Death
Cell Count
Immunohistochemistry
White Matter

Keywords

  • Apoptosis
  • Brain injury
  • Endoplasmic reticulum
  • Hypothermia
  • Ischemia
  • Neonate

ASJC Scopus subject areas

  • Neurology
  • Developmental Neuroscience

Cite this

Hypothermia and Rewarming Activate a Macroglial Unfolded Protein Response Independent of Hypoxic-Ischemic Brain Injury in Neonatal Piglets. / Lee-Summers, Jennifer; Wang, Bing; Reyes, Michael; Armstrong, Jillian S.; Kulikowicz, Ewa; Santos, Polan; Lee, Jeong Hoo; Koehler, Raymond C; Martin, Lee J.

In: Developmental Neuroscience, 14.09.2016.

Research output: Contribution to journalArticle

@article{905bcf95f851499091ee124a466e8b54,
title = "Hypothermia and Rewarming Activate a Macroglial Unfolded Protein Response Independent of Hypoxic-Ischemic Brain Injury in Neonatal Piglets",
abstract = "Therapeutic hypothermia provides incomplete neuroprotection after hypoxia-ischemia (HI)-induced brain injury in neonates. We previously showed that cortical neuron and white matter apoptosis are promoted by hypothermia and early rewarming in a piglet model of HI. The unfolded protein response (UPR) may be one of the potential mediators of this cell death. Here, neonatal piglets underwent HI or sham surgery followed by 29 h of normothermia, 2 h of normothermia + 27 h of hypothermia or 18 h of hypothermia + rewarming. Piglets recovered for 29 h. Immunohistochemistry for endoplasmic reticulum to nucleus signaling-1 protein (ERN1), a marker of UPR activation, was used to determine the ratios of ERN1+ macroglia and neurons in the motor subcortical white matter and cerebral cortex. The ERN1+ macroglia were immunophenotyped as oligodendrocytes and astrocytes by immunofluorescent colabeling. Temperature (p = 0.046) and HI (p < 0.001) independently affected the ratio of ERN1+ macroglia. In sham piglets, sustained hypothermia (p = 0.011) and rewarming (p = 0.004) increased the ERN1+ macroglia ratio above that in normothermia. HI prior to hypothermia diminished the UPR. Ratios of ERN1+ macroglia correlated with white matter apoptotic profile counts in shams (r = 0.472; p = 0.026), thereby associating UPR activation with white matter apoptosis during hypothermia and rewarming. Accordingly, macroglial cell counts decreased in shams that received sustained hypothermia (p = 0.009) or rewarming (p = 0.007) compared to those in normothermic shams. HI prior to hypothermia neutralized the macroglial cell loss. Neither HI nor temperature affected ERN1+ neuron ratios. In summary, delayed hypothermia and rewarming activate the macroglial UPR, which is associated with white matter apoptosis. HI may decrease the macroglial endoplasmic reticulum stress response after hypothermia and rewarming.",
keywords = "Apoptosis, Brain injury, Endoplasmic reticulum, Hypothermia, Ischemia, Neonate",
author = "Jennifer Lee-Summers and Bing Wang and Michael Reyes and Armstrong, {Jillian S.} and Ewa Kulikowicz and Polan Santos and Lee, {Jeong Hoo} and Koehler, {Raymond C} and Martin, {Lee J}",
year = "2016",
month = "9",
day = "14",
doi = "10.1159/000448585",
language = "English (US)",
journal = "Developmental Neuroscience",
issn = "0378-5866",
publisher = "S. Karger AG",

}

TY - JOUR

T1 - Hypothermia and Rewarming Activate a Macroglial Unfolded Protein Response Independent of Hypoxic-Ischemic Brain Injury in Neonatal Piglets

AU - Lee-Summers, Jennifer

AU - Wang, Bing

AU - Reyes, Michael

AU - Armstrong, Jillian S.

AU - Kulikowicz, Ewa

AU - Santos, Polan

AU - Lee, Jeong Hoo

AU - Koehler, Raymond C

AU - Martin, Lee J

PY - 2016/9/14

Y1 - 2016/9/14

N2 - Therapeutic hypothermia provides incomplete neuroprotection after hypoxia-ischemia (HI)-induced brain injury in neonates. We previously showed that cortical neuron and white matter apoptosis are promoted by hypothermia and early rewarming in a piglet model of HI. The unfolded protein response (UPR) may be one of the potential mediators of this cell death. Here, neonatal piglets underwent HI or sham surgery followed by 29 h of normothermia, 2 h of normothermia + 27 h of hypothermia or 18 h of hypothermia + rewarming. Piglets recovered for 29 h. Immunohistochemistry for endoplasmic reticulum to nucleus signaling-1 protein (ERN1), a marker of UPR activation, was used to determine the ratios of ERN1+ macroglia and neurons in the motor subcortical white matter and cerebral cortex. The ERN1+ macroglia were immunophenotyped as oligodendrocytes and astrocytes by immunofluorescent colabeling. Temperature (p = 0.046) and HI (p < 0.001) independently affected the ratio of ERN1+ macroglia. In sham piglets, sustained hypothermia (p = 0.011) and rewarming (p = 0.004) increased the ERN1+ macroglia ratio above that in normothermia. HI prior to hypothermia diminished the UPR. Ratios of ERN1+ macroglia correlated with white matter apoptotic profile counts in shams (r = 0.472; p = 0.026), thereby associating UPR activation with white matter apoptosis during hypothermia and rewarming. Accordingly, macroglial cell counts decreased in shams that received sustained hypothermia (p = 0.009) or rewarming (p = 0.007) compared to those in normothermic shams. HI prior to hypothermia neutralized the macroglial cell loss. Neither HI nor temperature affected ERN1+ neuron ratios. In summary, delayed hypothermia and rewarming activate the macroglial UPR, which is associated with white matter apoptosis. HI may decrease the macroglial endoplasmic reticulum stress response after hypothermia and rewarming.

AB - Therapeutic hypothermia provides incomplete neuroprotection after hypoxia-ischemia (HI)-induced brain injury in neonates. We previously showed that cortical neuron and white matter apoptosis are promoted by hypothermia and early rewarming in a piglet model of HI. The unfolded protein response (UPR) may be one of the potential mediators of this cell death. Here, neonatal piglets underwent HI or sham surgery followed by 29 h of normothermia, 2 h of normothermia + 27 h of hypothermia or 18 h of hypothermia + rewarming. Piglets recovered for 29 h. Immunohistochemistry for endoplasmic reticulum to nucleus signaling-1 protein (ERN1), a marker of UPR activation, was used to determine the ratios of ERN1+ macroglia and neurons in the motor subcortical white matter and cerebral cortex. The ERN1+ macroglia were immunophenotyped as oligodendrocytes and astrocytes by immunofluorescent colabeling. Temperature (p = 0.046) and HI (p < 0.001) independently affected the ratio of ERN1+ macroglia. In sham piglets, sustained hypothermia (p = 0.011) and rewarming (p = 0.004) increased the ERN1+ macroglia ratio above that in normothermia. HI prior to hypothermia diminished the UPR. Ratios of ERN1+ macroglia correlated with white matter apoptotic profile counts in shams (r = 0.472; p = 0.026), thereby associating UPR activation with white matter apoptosis during hypothermia and rewarming. Accordingly, macroglial cell counts decreased in shams that received sustained hypothermia (p = 0.009) or rewarming (p = 0.007) compared to those in normothermic shams. HI prior to hypothermia neutralized the macroglial cell loss. Neither HI nor temperature affected ERN1+ neuron ratios. In summary, delayed hypothermia and rewarming activate the macroglial UPR, which is associated with white matter apoptosis. HI may decrease the macroglial endoplasmic reticulum stress response after hypothermia and rewarming.

KW - Apoptosis

KW - Brain injury

KW - Endoplasmic reticulum

KW - Hypothermia

KW - Ischemia

KW - Neonate

UR - http://www.scopus.com/inward/record.url?scp=84988345807&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84988345807&partnerID=8YFLogxK

U2 - 10.1159/000448585

DO - 10.1159/000448585

M3 - Article

C2 - 27622292

AN - SCOPUS:84988345807

JO - Developmental Neuroscience

JF - Developmental Neuroscience

SN - 0378-5866

ER -