Abstract
Purpose :
Herein, we sought to determine if pDC-derived secretome could be used as a topical agent to ameliorate corneal nerve dysfunction.
Methods :
The BDCA2-DTR transgenic mouse strain, in which pDCs selectively express the diphtheria toxin receptor (DTR) allowing for selective depletion and subsequent nerve degeneration, was utilized for ex vivo electrophysiology studies on corneal nerve terminals. Animals were treated with pDC secretome drops, beginning 1 day after initial depletion. Electrophysiologic recordings were taken at day 3 post-depletion and analysis was performed in Spike2 (v9.1). Furthermore, in a ciliary nerve ligation model of neuropathic corneal pain (NCP), we assessed the therapeutic potential of pDC secretome. Treatments began at day 4 post-ligation and continued until day 14 post-ligation. Spontaneous and evoked pain responses were assessed by palpebral opening measurements and hyperosmolar saline, respectively.
Results :
Analysis of cold receptor recordings revealed no significant differences in cooling response among any group. However, there was a significant reduction in cooling threshold following pDC depletion, which was rescued by pDC secretome treatment (26.85 + 0.65 °C vs 29.52 + 0.42 °C; p<0.05), restoring the cooling threshold to control levels (29.21 + 0.51). Furthermore, nerve terminal exhaustion as assessed by the ratio of basal firing rates before and after the cooling stimulus was reduced following pDC depletion and rescued by pDC secretome treatment (0.534 + 0.079 vs 1.105 + 0.100; p<0.01). Spontaneous pain responses, assessed by palpebral opening, were worse in the vehicle-treated compared to pDC secretome-treated group (0.667 + 0.028 vs 0.846 + 0.021; p<0.001). Similarly, evoked pain responses were worse in the vehicle-treated compared to pDC secretome-treated group (30.25 + 1.50 wipes/30 sec vs 15.38 + 1.29 wipes/30 sec; p<0.0001).
Conclusions :
Herein, we demonstrate that pDC secretome restores normal functioning of corneal cold receptors in ex vivo electrophysiology. Importantly, in a translational model of NCP, pDC secretome treatment improved both spontaneous and evoked pain responses. Thus, pDC secretome is a viable therapeutic modality for further development and may hold promise in treatment of NCP and other corneal nerve related diseases, for which there are currently few treatment options available, in order to restore corneal nerve homeostasis.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.