Abstract
Purpose :
To evaluate the role of substance P (SP)/neurokinin-1 receptor (NK1R) pathway in corneal epithelium wound healing in a pre-clinical model of stem cell deficiency (SCD).
Methods :
Eight-week-old C57BL6/N (WT) and B6.Cg-Tac1tm1Bbm/J (TAC1-KO) male mice underwent complete corneal disepithelization, including the limbus. Animals were followed-up for 14 days, corneal epithelial wound closure and transparency were assessed by biomicroscopy. To test the effect of NK1R blockade, WT mice received 0.1 or 1 mg/mL NK1R antagonist Fosaprepitant solution topically for 16 days after disepithelization (FOSA 0.1 and FOSA 1). After animal sacrifice, the number of goblet and conjunctival cells infiltrating the cornea was quantified with Periodic Acid Schiff and cytokeratin-8 and 19 stainings, respectively. Cytokeratin-12 was employed as a marker of corneal epithelial cells. The number of stem cells was quantified with p63 and BrdU co-staining.
Results :
TAC1-KO mice showed a significant increase in epithelial wound healing rate (p<0.001) and corneal transparency (p<0.001) up to 14 days after disepithelization, compared to WT. Similarly, FOSA 1 mice showed a significant improvement in wound closure rate and transparency starting from day five when compared to WT mice (p<0.05), while FOSA 0.1 group did not show any improvement. TAC1-KO and FOSA 1 mice showed reduced number of infiltrating goblet and conjunctival cells (p<0.05) and increased number of corneal epithelial stem cells (p<0.01).
Conclusions :
These results suggest that excessive expression of SP is associated with SCD and results in conjunctival infiltration and exhaustion of residual stem cells, supporting the hypothesis that blockade of neurokinin-1 receptor could be used as an adjuvant treatment in SCD.
This is a 2021 ARVO Annual Meeting abstract.