Cyclosporine immunomodulation retards regeneration of surgically transected corneal nerves.
OBJECTIVE
To determine whether immunomodulation with cyclosporine (CsA) affects reinnervation after surgical transection of stromal nerves.


METHODS
Thy1-YFP+ neurofluorescent mice underwent lamellar corneal surgery and 3 days later, received artificial tears or CsA eye drops for 6 weeks. Serial in vivo wide-field stereofluorescent microscopy was performed to determine changes in nerve fiber density (NFD). Real-time quantitative PCR was performed to determine the expression of neurotrophins and cytokines (IL6 and TNF-α). Compartmental culture of trigeminal ganglion neurons was performed in Campenot devices to determine whether CsA directly affects neurite outgrowth.


RESULTS
Yellow fluorescent protein (YFP)-positive cells significantly increased at 3 and 7 days after surgery. The number of YFP-positive cells in the cornea was significantly lower in the CsA group than that in the control group. The percentage increase in NFD between 2 to 6 weeks was greater in the control group (80% ± 10%, P = 0.05) than that in the CsA group (39% ± 21%). The CsA group also exhibited lower expression of IL6 and TNF-α (P = 0.01). In compartmental culture experiments, neurite outgrowth toward side compartments containing CsA was significantly less (2.29 ± 0.4 mm, P = 0.01) than that toward side compartments containing vehicle (3.97 ± 0.71 mm).


CONCLUSIONS
Immunomodulation with CsA reduces the expression of cytokines (IL6) in the cornea and retards regenerative sprouting from transected corneal stromal nerve trunks. In addition, CsA has a direct growth inhibitory action on neurites as well.
Corneal Neurobiology Laboratory, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, College of Medicine, Chicago, Illinois 60612, USA.
Abed
A
Namavari
Shweta
S
Chaudhary
Jin-Hong
JH
Chang
Lisette
L
Yco
Snehal
S
Sonawane
Vishakha
V
Khanolkar
Beatrice Y
BY
Yue
Joy
J
Sarkar
Sandeep
S
Jain
D000818:Animals; D003315:Cornea / Q000294:innervation* / Q000502:physiology* / Q000601:surgery; D003319:Corneal Stroma / Q000294:innervation; D016572:Cyclosporine / Q000494:pharmacology*; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D015850:Interleukin-6 / Q000378:metabolism; D051379:Mice; D009414:Nerve Growth Factors / Q000378:metabolism; D016501:Neurites / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012038:Regeneration / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D007166:Immunosuppressive Agents; D015850:Interleukin-6; D009414:Nerve Growth Factors; D014409:Tumor Necrosis Factor-alpha; D016572:Cyclosporine