Dept of Veterinary Surgery & Radiology, West Bengal University of Animal & Fishery Sciences, 37& 68 Khudiram Bose Sarani, Kolkata, 700037, India.
CSIR-IICB, Jadavpur, Kolkata, India.
Exp Eye Res. 2020 May;194:108009. doi: 10.1016/j.exer.2020.108009. Epub 2020 Mar 20.
Restoration of corneal sensitivity is of utmost importance to maintain corneal homeostasis following any injury or insult, for which, both corneal nerve regeneration and re-innervation are essential. Fibrosis poses a major impediment for re-innervation. We have in this study evaluated the influence of various nerve growth factors and corneal fibrosis on corneal nerve regeneration and reinnervation following lamellar flap surgery (LFS) and its modulation using antifibrotic drug pirfenidone. To achieve this, trigeminal ganglion cells were treated with pirfenidone, NGF, and NT-3 to evaluate their effect on trigeminal cell neurite growth. Following LFS, the gene expression of nerve growth factors NGF, BDNF and NT-3, Gap 43, Nogo-A and profibrotic factors Tenascin C, TGF-beta 1 were evaluated with and without pirfenidone. Wound fibrosis and corneal nerve regeneration using pirfenidone following LFS were evaluated by staining whole corneal mounts with α SMA and β tubulin 3. Safety of NGF and pirfenidone topical drops in normal unoperated cornea and its efficacy in enhancing corneal healing was evaluated following LFS. Our study shows, pirfenidone did not influence trigeminal cell neurite elongation; NGF and NT-3 significantly enhanced trigeminal cell neurite elongation. NT-3 also significantly increased neurite branching. There was significant increase in the gene expression of NGF, BDNF, NT-3, Gap- 43, TGF beta-1, Tenascin C, Nogo-A genes in the operated cornea compared to normal cornea, treatment of operated corneas with pirfenidone prevented the increased expression of these genes except Gap 43 which remained unchanged. The treatment of operated eyes with combination of NGF and pirfenidone positively influenced corneal healing compared to treatment with NGF alone, and had no adverse influence on the cornea. Pirfenidone appreciably reduced corneal fibrosis which aided in re-innervation. Both NGF and NT3 positively influence trigeminal neurite elongation. NGF and pirfenidone have complementary influence on corneal wound healing.
角膜敏感性的恢复对于维持任何损伤或刺激后的角膜内稳态至关重要，为此，角膜神经再生和再支配都是必不可少的。纤维化是再支配的主要障碍。在这项研究中，我们评估了各种神经生长因子和角膜纤维化对板层瓣手术（LFS）后角膜神经再生和再支配的影响，并使用抗纤维化药物吡非尼酮对其进行了调节。为此，我们用吡非尼酮、NGF 和 NT-3 处理三叉神经节细胞，以评估它们对三叉神经细胞突起生长的影响。在 LFS 后，评估了神经生长因子 NGF、BDNF 和 NT-3、Gap 43、Nogo-A 和促纤维化因子 Tenascin C、TGF-β1 的基因表达，同时评估了有无吡非尼酮的表达。用α SMA 和β tubulin 3 对 LFS 后用吡非尼酮处理的整个角膜进行染色，评估伤口纤维化和角膜神经再生。评估了 NGF 和吡非尼酮局部滴眼在正常未手术角膜中的安全性及其在 LFS 后增强角膜愈合的功效。我们的研究表明，吡非尼酮不会影响三叉神经细胞突起的伸长；NGF 和 NT-3 显著增强三叉神经细胞突起的伸长。NT-3 还显著增加了神经突分支。与正常角膜相比，手术角膜中 NGF、BDNF、NT-3、Gap-43、TGF-β1、Tenascin C、Nogo-A 基因的表达显著增加，与单独使用 NGF 相比，用吡非尼酮治疗手术角膜可防止这些基因表达增加，而 Gap-43 不变。与单独使用 NGF 相比，用 NGF 和吡非尼酮联合治疗对角膜愈合有积极影响，且对角膜无不良影响。吡非尼酮显著减少了角膜纤维化，有助于再支配。NGF 和 NT3 均能显著促进三叉神经突起伸长。NGF 和吡非尼酮对角膜伤口愈合有互补作用。
