Neuroprotectin D1 synthesis and corneal nerve regeneration after experimental surgery and treatment with PEDF plus DHA.
OBJECTIVE
This study was conducted to define whether pigment epithelial-derived growth factor (PEDF), together with docosahexaenoic acid (DHA), enhances the synthesis of neuroprotectin D1 (NPD1) and the regeneration of corneal nerves damaged after surgery.


METHODS
Corneal stromal dissection was performed in the left eyes of adult New Zealand rabbits treated with DHA+PEDF, PEDF, or DHA for 6 weeks. In vivo confocal images of the corneas were obtained at 2, 4, and 8 weeks, and nerve areas were quantified. At 8 weeks after treatment, corneas were stained with tubulin betaIII antibody, and the epithelial nerve area and the sub-basal and stromal nerve plexus were quantified. At 1 week and 2 weeks after treatment, lipids were extracted from corneas, and the synthesis of NPD1 was analyzed by mass spectrometry. Epithelial cell density was quantified by confocal microscopy 8 weeks after surgery.


RESULTS
In vivo confocal images at 2 and 4 weeks after surgery showed a 2.5-fold increase in corneal nerve area in PEDF+DHA-treated animals compared with control animals. Increased nerve surface areas in epithelia, subepithelia, and stroma were observed in rabbits treated for 8 weeks with PEDF+DHA. PEDF or DHA alone did not produce a significant increase. NPD1 synthesis peaked at 1 week and was four times higher in the PEDF+DHA-treated group than in the controls.


CONCLUSIONS
PEDF+DHA promotes the regeneration of corneal nerves. Neurotrophin-mediated NPD1 synthesis is suggested to precede nerve regeneration by demonstration of its accumulation upon addition of DHA and PEDF at earlier time points. Therefore, this signaling mechanism upregulates corneal nerve regeneration and may be targeted in neurotrophic keratitis, dry eye after refractive surgery, and other corneal diseases.
Department of Ophthalmology and Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, School of Medicine, New Orleans, Louisiana 70112, USA.
M Soledad
MS
Cortina
Jiucheng
J
He
Na
N
Li
Nicolas G
NG
Bazan
Haydee E P
HE
Bazan
D000818:Animals; D002452:Cell Count; D003315:Cornea / Q000294:innervation*; D003319:Corneal Stroma / Q000294:innervation / Q000601:surgery; D016039:Corneal Transplantation; D004281:Docosahexaenoic Acids / Q000378:metabolism / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005136:Eye Proteins / Q000627:therapeutic use*; D005260:Female; D008297:Male; D013058:Mass Spectrometry; D018613:Microscopy, Confocal; D009414:Nerve Growth Factors / Q000627:therapeutic use*; D009416:Nerve Regeneration / Q000187:drug effects*; D011817:Rabbits; D015843:Serpins / Q000627:therapeutic use*; D012668:Trigeminal Ganglion / Q000502:physiology*; D014404:Tubulin / Q000378:metabolism; D000099174:Pigment Epithelium-Derived Factor
D004281:Docosahexaenoic Acids; D005136:Eye Proteins; D009414:Nerve Growth Factors; D015843:Serpins; D014404:Tubulin; D000099174:Pigment Epithelium-Derived Factor; C487679:protectin D1