Hyperhomocysteinemia-induced death of retinal ganglion cells: The role of Müller glial cells and NRF2

Soumya Navneet, Jing Zhao, Jing Wang, Barbara A Mysona, Shannon Barwick, Navneet Ammal Kaidery, Alan B Saul, Ismail Kaddour-Djebbar, Wendy B Bollag, Bobby Thomas, Kathryn Elizabeth Bollinger, Sylvia B Smith

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Hyperhomocysteinemia (Hhcy), or increased levels of the excitatory amino acid homocysteine (Hcy), is implicated in glaucoma, a disease characterized by increased oxidative stress and loss of retinal ganglion cells (RGCs). Whether Hhcy is causative or merely a biomarker for RGC loss in glaucoma is unknown. Here we analyzed the role of NRF2, a master regulator of the antioxidant response, in Hhcy-induced RGC death in vivo and in vitro. By crossing Nrf2 −/− mice and two mouse models of chronic Hhcy (Cbs +/- and Mthfr +/- mice), we generated Cbs +/- Nrf2 −/− and Mthfr +/- Nrf2 −/− mice and performed systematic analysis of retinal architecture and visual acuity followed by assessment of retinal morphometry and gliosis. We observed significant reduction of inner retinal layer thickness and reduced visual acuity in Hhcy mice lacking NRF2. These functional deficits were accompanied by fewer RGCs and increased gliosis. Given the key role of Müller glial cells in maintaining RGCs, we established an ex-vivo indirect co-culture system using primary RGCs and Müller cells. Hhcy-exposure decreased RGC viability, which was abrogated when cells were indirectly cultured with wildtype (WT) Müller cells, but not with Nrf2 −/− Müller cells. Exposure of WT Müller cells to Hhcy yielded a robust mitochondrial and glycolytic response, which was not observed in Nrf2 −/− Müller cells. Taken together, the in vivo and in vitro data suggest that deleterious effects of Hhcy on RGCs are likely dependent upon the health of retinal glial cells and the availability of an intact retinal antioxidant response mechanism.

Original languageEnglish (US)
Article number101199
JournalRedox Biology
Volume24
DOIs
StatePublished - Jun 1 2019

Fingerprint

Hyperhomocysteinemia
Retinal Ganglion Cells
Neuroglia
Antioxidants
Excitatory Amino Acids
Oxidative stress
Biomarkers
Homocysteine
Cell death
Health
Availability
Gliosis
Glaucoma
Visual Acuity
Coculture Techniques
Cell Survival
Oxidative Stress
Cell Death

Keywords

  • Cystathionine β-synthase
  • Ganglion cells
  • Glaucoma
  • Homocysteine
  • Hyperhomocysteinemia
  • Methylene tetrahydrofolate reductase
  • Mouse
  • NRF2
  • Retina

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry

Cite this

Hyperhomocysteinemia-induced death of retinal ganglion cells : The role of Müller glial cells and NRF2. / Navneet, Soumya; Zhao, Jing; Wang, Jing; Mysona, Barbara A; Barwick, Shannon; Ammal Kaidery, Navneet; Saul, Alan B; Kaddour-Djebbar, Ismail; Bollag, Wendy B; Thomas, Bobby; Bollinger, Kathryn Elizabeth; Smith, Sylvia B.

In: Redox Biology, Vol. 24, 101199, 01.06.2019.

Research output: Contribution to journalArticle

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abstract = "Hyperhomocysteinemia (Hhcy), or increased levels of the excitatory amino acid homocysteine (Hcy), is implicated in glaucoma, a disease characterized by increased oxidative stress and loss of retinal ganglion cells (RGCs). Whether Hhcy is causative or merely a biomarker for RGC loss in glaucoma is unknown. Here we analyzed the role of NRF2, a master regulator of the antioxidant response, in Hhcy-induced RGC death in vivo and in vitro. By crossing Nrf2 −/− mice and two mouse models of chronic Hhcy (Cbs +/- and Mthfr +/- mice), we generated Cbs +/- Nrf2 −/− and Mthfr +/- Nrf2 −/− mice and performed systematic analysis of retinal architecture and visual acuity followed by assessment of retinal morphometry and gliosis. We observed significant reduction of inner retinal layer thickness and reduced visual acuity in Hhcy mice lacking NRF2. These functional deficits were accompanied by fewer RGCs and increased gliosis. Given the key role of M{\"u}ller glial cells in maintaining RGCs, we established an ex-vivo indirect co-culture system using primary RGCs and M{\"u}ller cells. Hhcy-exposure decreased RGC viability, which was abrogated when cells were indirectly cultured with wildtype (WT) M{\"u}ller cells, but not with Nrf2 −/− M{\"u}ller cells. Exposure of WT M{\"u}ller cells to Hhcy yielded a robust mitochondrial and glycolytic response, which was not observed in Nrf2 −/− M{\"u}ller cells. Taken together, the in vivo and in vitro data suggest that deleterious effects of Hhcy on RGCs are likely dependent upon the health of retinal glial cells and the availability of an intact retinal antioxidant response mechanism.",
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AU - Barwick, Shannon

AU - Ammal Kaidery, Navneet

AU - Saul, Alan B

AU - Kaddour-Djebbar, Ismail

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