June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
PEDF+DHA stimulation of corneal nerve regeneration requires activation of Ca2+-independent Phospholipase A2-ζ and 15-lipoxygenase-1
Author Affiliations & Notes
  • Thang Luong PHAM
    Neuroscience Center, LSU Health, New Orleans, Louisiana, United States
  • Azucena H Kakazu
    Ophthalmology and Neuroscience, LSU Health, New Orleans, Louisiana, United States
  • Jiucheng He
    Ophthalmology and Neuroscience, LSU Health, New Orleans, Louisiana, United States
  • Bokkyoo Jun
    Neuroscience Center, LSU Health, New Orleans, Louisiana, United States
  • Nicolas Guillermo Bazan
    Ophthalmology and Neuroscience, LSU Health, New Orleans, Louisiana, United States
  • Haydee E P Bazan
    Ophthalmology and Neuroscience, LSU Health, New Orleans, Louisiana, United States
  • Footnotes
    Commercial Relationships   Thang PHAM, None; Azucena Kakazu, None; Jiucheng He, None; Bokkyoo Jun, None; Nicolas Bazan, None; Haydee Bazan, None
  • Footnotes
    Support  NIH grant R01-EY0119465 and a grant from Research Foundation to Prevent Blindness
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 1390. doi:
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    • Get Citation

      Thang Luong PHAM, Azucena H Kakazu, Jiucheng He, Bokkyoo Jun, Nicolas Guillermo Bazan, Haydee E P Bazan; PEDF+DHA stimulation of corneal nerve regeneration requires activation of Ca2+-independent Phospholipase A2-ζ and 15-lipoxygenase-1
      . Invest. Ophthalmol. Vis. Sci. 2017;58(8):1390.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Our recent studies in mice have shown that PEDF+DHA stimulates corneal nerve regeneration by targeting neurotrophins and semaphorin7a (ARVO, 2016). Here we investigate the role of Ca2+-independent phospholipase A2-ζ (iPLA2ζ) activity linked to PEDF-receptor (PEDF-R) and 15-lipooxygenease-1 (15-LOX-1) activation related to docosanoids formation in the molecular mechanism of PEDF+DHA action.

Methods : Mouse corneas (right eye) were injured by rotating a 2 mm trephine to cut the nerves at the stromal level. There were 4 treatment groups: (1) PEDF+DHA, (2) co-administration of Atglistatin (iPLA2ζ inhibitor) and PEDF+DHA, (3) co-administration of PD146176 (12,15-LOX-1 inhibitor) and PEDF+DHA, and (4) vehicle. To study gene expression and lipidomics, mice were euthanized and corneas were harvested at 3h. Tears from treated mice were also used to evaluate tear secretion by Schirmer’s test and levels of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and Sema7A were evaluated by western blot at different times after treatment. At day 7, whole corneas were excised, fixed and stained with monoclonal rabbit anti-PGP9.5 antibody. The whole mount images were used for nerve density.

Results : Synthesis of DHA derivatives 14HDHA and 17HDHA increased 3.5 and 9.5 fold after PEDF+DHA treatment for 3h. Secretion of BDNF, NGF, and Sema7A increased 2.3, 1.5 and 4 times, respectively at 6h; and tear volume increased 1.4 times compared to vehicle-treated mice at day 6. Regenerated nerve density was 80 ± 2.4% of unwounded corneas. This rate of regeneration was 125% faster than vehicle-treated corneas. Co-treatment with iPLA2ζ and 12,15-LOX-1 inhibitors reduced all of the PEDF+DHA-induced changes to the values of vehicle-treated corneas. Atglistatin decreased tear volume to 62% and nerve density to 75% of the PEDF+DHA values in treated corneas, while the inhibitory effects of PD146176 were 75% and 83%, respectively. In vehicle-treated corneas, tear secretion and nerve density values were 71% and 80% of PEDF+DHA-treated ones.

Conclusions : The molecular mechanism by which PEDF+DHA stimulates corneal nerve regeneration involves activation of iPLA2ζ and synthesis of DHA-derivative lipids that then induce the expression of specific neurotrophins and semaphorin 7A.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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