Limits...
Neuroprotection by selective neuronal deletion of Atg7 in neonatal brain injury.

Xie C, Ginet V, Sun Y, Koike M, Zhou K, Li T, Li H, Li Q, Wang X, Uchiyama Y, Truttmann AC, Kroemer G, Puyal J, Blomgren K, Zhu C - Autophagy (2016)

Bottom Line: There is an urgent need to elucidate the neuronal death mechanisms occurring after neonatal hypoxia-ischemia (HI).Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death.Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells.

View Article: PubMed Central - PubMed

Affiliation: a Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg , Gothenburg , Sweden.

ABSTRACT
Perinatal asphyxia induces neuronal cell death and brain injury, and is often associated with irreversible neurological deficits in children. There is an urgent need to elucidate the neuronal death mechanisms occurring after neonatal hypoxia-ischemia (HI). We here investigated the selective neuronal deletion of the Atg7 (autophagy related 7) gene on neuronal cell death and brain injury in a mouse model of severe neonatal hypoxia-ischemia. Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death. Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells. These findings reveal that selective neuronal deletion of Atg7 is strongly protective against neuronal death and overall brain injury occurring after HI and suggest that inhibition of HI-enhanced autophagy should be considered as a potential therapeutic target for the treatment of human newborns developing severe hypoxic-ischemic encephalopathy.

No MeSH data available.


Related in: MedlinePlus

Neuronal Atg7 deficiency attenuated hypoxia-ischemia-induced cytokine and chemokine expression and microglial activation. (A) Luminex assay of the cytosolic fraction of nonischemic (Cont) (n = 9 for Ctrl and n = 7 for atg7 KO) and for hypoxic-ischemic cortical tissue 24 h after HI (n = 9 for Ctrl and n = 7 for atg7 KO) demonstrated a decreased IL6, CXCL1, CCL2 and IL1B in KO mice. (B) Representative AIF1 immunostaining in the cortex of both Ctrl and atg7 KO mice 24 h after HI. (C) Double labeling of AIF1 and activated microglia marker galectin-3 (LGALS3) in the HI cortex. (D) Quantification of the number of AIF1-positive cells in both the cortex (*, P<0.05) and the striatum (**, P<0.01) confirmed a less pronounced microglia activation in KO mice. (n = 11/group). KO: atg7 KO (Atg7flox/flox; Nes-Cre) and Ctrl: Atg7flox/+; Nes-Cre.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4835980&req=5

f0007: Neuronal Atg7 deficiency attenuated hypoxia-ischemia-induced cytokine and chemokine expression and microglial activation. (A) Luminex assay of the cytosolic fraction of nonischemic (Cont) (n = 9 for Ctrl and n = 7 for atg7 KO) and for hypoxic-ischemic cortical tissue 24 h after HI (n = 9 for Ctrl and n = 7 for atg7 KO) demonstrated a decreased IL6, CXCL1, CCL2 and IL1B in KO mice. (B) Representative AIF1 immunostaining in the cortex of both Ctrl and atg7 KO mice 24 h after HI. (C) Double labeling of AIF1 and activated microglia marker galectin-3 (LGALS3) in the HI cortex. (D) Quantification of the number of AIF1-positive cells in both the cortex (*, P<0.05) and the striatum (**, P<0.01) confirmed a less pronounced microglia activation in KO mice. (n = 11/group). KO: atg7 KO (Atg7flox/flox; Nes-Cre) and Ctrl: Atg7flox/+; Nes-Cre.

Mentions: As neuroinflammation is involved in HI-induced cell death, we investigated the effect of neuronal autophagy inhibition on some inflammatory markers. The quantification of selected cytokines and chemokines, such as interleukins (IL1A [interleukin 1 α], IL1B [interleukin 1 β], IL6 [interleukin 6], IL10 [interleukin10], TNF [tumor necrosis factor], CXCL1[chemokine (C-X-C motif) ligand 1] and CCL2 [chemokine (C-C motif) ligand 2]) in brain homogenates revealed that IL1B, IL6, CXCL1 and CCL2 were less expressed in atg7 KO than Ctrl mice 24 h after HI (Fig. 7A). After HI, microglial cells positive for AIF1/IBA1 (allograft inflammatory factor 1), were activated and accumulated in the injured area after HI, as indicated by morphological examination (retracted processes and enlarged cell bodies) (Fig. 7B) and double labeling with LGALS3/galectin-3 (lectin, galactoside-binding, soluble, 3) (Fig. 7C). This microglial recruitment was less extensive in atg7 KO mice compared to Ctrl, as shown by quantification of the number of active AIF1-positive cells (Fig. 7D).Figure 7.


Neuroprotection by selective neuronal deletion of Atg7 in neonatal brain injury.

Xie C, Ginet V, Sun Y, Koike M, Zhou K, Li T, Li H, Li Q, Wang X, Uchiyama Y, Truttmann AC, Kroemer G, Puyal J, Blomgren K, Zhu C - Autophagy (2016)

Neuronal Atg7 deficiency attenuated hypoxia-ischemia-induced cytokine and chemokine expression and microglial activation. (A) Luminex assay of the cytosolic fraction of nonischemic (Cont) (n = 9 for Ctrl and n = 7 for atg7 KO) and for hypoxic-ischemic cortical tissue 24 h after HI (n = 9 for Ctrl and n = 7 for atg7 KO) demonstrated a decreased IL6, CXCL1, CCL2 and IL1B in KO mice. (B) Representative AIF1 immunostaining in the cortex of both Ctrl and atg7 KO mice 24 h after HI. (C) Double labeling of AIF1 and activated microglia marker galectin-3 (LGALS3) in the HI cortex. (D) Quantification of the number of AIF1-positive cells in both the cortex (*, P<0.05) and the striatum (**, P<0.01) confirmed a less pronounced microglia activation in KO mice. (n = 11/group). KO: atg7 KO (Atg7flox/flox; Nes-Cre) and Ctrl: Atg7flox/+; Nes-Cre.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835980&req=5

f0007: Neuronal Atg7 deficiency attenuated hypoxia-ischemia-induced cytokine and chemokine expression and microglial activation. (A) Luminex assay of the cytosolic fraction of nonischemic (Cont) (n = 9 for Ctrl and n = 7 for atg7 KO) and for hypoxic-ischemic cortical tissue 24 h after HI (n = 9 for Ctrl and n = 7 for atg7 KO) demonstrated a decreased IL6, CXCL1, CCL2 and IL1B in KO mice. (B) Representative AIF1 immunostaining in the cortex of both Ctrl and atg7 KO mice 24 h after HI. (C) Double labeling of AIF1 and activated microglia marker galectin-3 (LGALS3) in the HI cortex. (D) Quantification of the number of AIF1-positive cells in both the cortex (*, P<0.05) and the striatum (**, P<0.01) confirmed a less pronounced microglia activation in KO mice. (n = 11/group). KO: atg7 KO (Atg7flox/flox; Nes-Cre) and Ctrl: Atg7flox/+; Nes-Cre.
Mentions: As neuroinflammation is involved in HI-induced cell death, we investigated the effect of neuronal autophagy inhibition on some inflammatory markers. The quantification of selected cytokines and chemokines, such as interleukins (IL1A [interleukin 1 α], IL1B [interleukin 1 β], IL6 [interleukin 6], IL10 [interleukin10], TNF [tumor necrosis factor], CXCL1[chemokine (C-X-C motif) ligand 1] and CCL2 [chemokine (C-C motif) ligand 2]) in brain homogenates revealed that IL1B, IL6, CXCL1 and CCL2 were less expressed in atg7 KO than Ctrl mice 24 h after HI (Fig. 7A). After HI, microglial cells positive for AIF1/IBA1 (allograft inflammatory factor 1), were activated and accumulated in the injured area after HI, as indicated by morphological examination (retracted processes and enlarged cell bodies) (Fig. 7B) and double labeling with LGALS3/galectin-3 (lectin, galactoside-binding, soluble, 3) (Fig. 7C). This microglial recruitment was less extensive in atg7 KO mice compared to Ctrl, as shown by quantification of the number of active AIF1-positive cells (Fig. 7D).Figure 7.

Bottom Line: There is an urgent need to elucidate the neuronal death mechanisms occurring after neonatal hypoxia-ischemia (HI).Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death.Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells.

View Article: PubMed Central - PubMed

Affiliation: a Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg , Gothenburg , Sweden.

ABSTRACT
Perinatal asphyxia induces neuronal cell death and brain injury, and is often associated with irreversible neurological deficits in children. There is an urgent need to elucidate the neuronal death mechanisms occurring after neonatal hypoxia-ischemia (HI). We here investigated the selective neuronal deletion of the Atg7 (autophagy related 7) gene on neuronal cell death and brain injury in a mouse model of severe neonatal hypoxia-ischemia. Neuronal deletion of Atg7 prevented HI-induced autophagy, resulted in 42% decrease of tissue loss compared to wild-type mice after the insult, and reduced cell death in multiple brain regions, including apoptosis, as shown by decreased caspase-dependent and -independent cell death. Moreover, we investigated the lentiform nucleus of human newborns who died after severe perinatal asphyxia and found increased neuronal autophagy after severe hypoxic-ischemic encephalopathy compared to control uninjured brains, as indicated by the numbers of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3)-, LAMP1 (lysosomal-associated membrane protein 1)-, and CTSD (cathepsin D)-positive cells. These findings reveal that selective neuronal deletion of Atg7 is strongly protective against neuronal death and overall brain injury occurring after HI and suggest that inhibition of HI-enhanced autophagy should be considered as a potential therapeutic target for the treatment of human newborns developing severe hypoxic-ischemic encephalopathy.

No MeSH data available.


Related in: MedlinePlus