Abstract
Purpose :
The mechanisms for corneal epithelial wound healing remain to be elucidated. Our recent study identified the capacity of resident corneal plasmacytoid dendritic cells (pDCs) secreting neurotrophins which play a key role in tissue repair. This study tested the hypothesis that local pDCs promote corneal epithelial wound healing in a murine model.
Methods :
Corneal wounds were created by removing central 2-mm corneal epithelium in mice. At 16h after wounded in C57BL/6 (B6) mice, corneal pDCs (CD45+CD11bnegF4/80negB220+PDCA-1+Siglec-H+cells) frequency and expression of neurotrophins by pDCs were assessed via flow cytometry. At 1 day before wounded, local pDCs were depleted via single subconjunctival injection of 30ng diphtheria toxin (DT) into pDC-DTR mice, with B6 mice receiving DT and pDC-DTR mice receiving vehicle as controls, while pDCs were activated via injection of 20μg agonists of toll-like-receptor (TLR)-7 (R-848) or TLR9 (CpG-ODN-1862) into B6 mice, with non-CpG-ODN treatment as control. Corneal epithelial defect was visualized by fluorescein staining under slit lamp and calculated as the percentage of residual defect area.
Results :
Corneal pDCs frequency increased in wounded B6 mice (547.2±101.9 [Mean±SEM] pDCs/cornea, account for 30.2±2.3% of total CD45+ leukocytes) compared to the unwounded (73.8±5.7 pDCs and 13.5±0.9%; n=5/group; both p<0.01). Both frequency of neurotrophins-expressing pDCs (NGF-expressing pDCs, 48.2±0.7% vs. 31.8±3.0%; BDNF, 97.6±0.3% vs. 90.1±1.3%; NT4, 93.0±0.7% vs.78.7±2.1%; GDNF, 88.7±1.4% vs. 62.1±2.2%; all p<0.01) and expression levels of neurotrophins in pDCs (folds of medium fluoresence index to the unwounded: NGF, 3.1±0.09; BDNF, 1.8±0.08; NT4/5, 1.4±0.04; GDNF, 2.1±0.08; all p<0.01) increased in wounded mice. Further, pDCs depletion delayed corneal epithelial wound healing shown by larger corneal defect area in pDCs-depleted mice (48.3±11.8%) than in two controls (18.9±3.4% and 18.1±7.5%, respectively; n=4/group; p<0.05) at 24h following wounded. In contrast, activated pDCs accelerated the wound healing shown by smaller corneal epithelial defect area in R-848 (39.3±8.8%; p<0.01) or CpG-ODN-1862 (35.0±4.5%, p<0.01) treated mice than in non-CpG-ODN treated mice (70.9±2.2%, n=4/group) at 12h following wounded.
Conclusions :
Local pDCs promote corneal epithelial wound healing in mice after acute injury, which could be a potential target for restoration of corneal epithelial integrity.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.