Calcitonin Gene-Related Peptide Regulates Specific Interferon-Stimulating Genes to Inhibit Apoptosis of Corneal Epithelial Cells in Dry Eye Disease.

PURPOSE: Calcitonin gene-related peptide (CGRP) has demonstrated the potential to treat dry eye disease (DED), although its mechanism is not well-understood. This study investigated the effect of CGRP on apoptosis of corneal epithelial cells in a model of DED.

METHODS

Tear samples were collected from patients with DED. Additionally, samples were collected from a rat model of DED and a CGRP overexpression human corneal epithelial (HCET) model. The concentrations of CGRP and IFN-γ in tears were detected by ELISA and analyzed in combination with clinical data. The apoptosis level of corneal epithelial cells was evaluated by Western blot, qRT-PCR, TUNEL staining, and flow cytometry. RNA-seq screening and validation of CGRP target proteins in corneal epithelial cells was also performed.

RESULTS

The findings of this study demonstrated a significant and positive correlation between CGRP expressed in tears of patients with DED and multiple clinical indicators of DED (P < 0.05). CGRP expression was similarly increased in the DED animal model. Exogenous CGRP peptides were observed to significantly inhibit the apoptosis of corneal tissue (P < 0.05). The CGRP overexpressing group similarly showed decreased levels of apoptosis in the corneal tissue (P < 0.05). Reduced apoptosis of corneal tissues was associated with the IFN-γ/JAK2/STAT1 pathway. RNA-seq suggested that CGRP(8-37) concurrently increased apoptosis, inhibited the expression of specific interferon-stimulating genes (SISGs), and was related to the activation of IFN-γ/JAK2/STAT1 (P < 0.05).

CONCLUSIONS

High CGRP concentration in tears of patients with DED demonstrated a significant correlation with severity of clinical symptoms. Increased CGRP was associated with reduced apoptosis of corneal epithelial cells in an animal model of DED. Molecular evaluation identified inhibition of SISGs and activation of IFN-γ/JAK2/STAT1 as CGRP-related mechanisms potentially mediating reduced apoptosis.