cRGD-Conjugated Bilirubin Nanoparticles Alleviate Dry Eye Disease Via Activating the PINK1-Mediated Mitophagy.

PURPOSE

The purpose of this study was to evaluate the cytoprotective effect and the mechanism of cRGD-conjugated bilirubin nanoparticles (cNPs@BR) in dry eye disease (DED).

METHODS

The binding capacity and cellular uptake of cNPs@BR in human corneal epithelial cells (HCECs) were assessed by immunofluorescence. The anti-inflammation and anti-oxidative stress effects of cNPs@BR were determined by flow cytometry, immunofluorescence, Western blot, chromatin immunoprecipitation (ChIP), and ELISA assay in LPS-stimulated RAW264.7 cells and hypertonic HCECs. The function of ocular surface barrier, tear production, and the number of goblet cells after cNPs@BR treatment were further assessed by fluorescein sodium staining, phenol red cotton threads, quantitative PCR (qPCR), hematoxylin and eosin (H&E) staining, and Periodic Acid-Schiff (PAS) staining in a 0.2% BAC-induced DED mouse model. Furthermore, the mechanism of cNPs@BR in treating DED was explored by RNA sequencing and RNA interference.

RESULTS

The cRGD peptide prolonged the retention time of nanoparticles on HCECs and enhanced the cellular uptake efficiency. In both cell models, 20 µM cNPs@BR pretreatment ameliorated oxidative stress by decreasing the intracellular reactive oxygen species (ROS) levels and the expression of NOX4 and 4-HNE, while promoting HO-1 and nuclear Nrf2 levels. Moreover, cNPs@BR alleviated the inflammatory response by inhibiting NF-κB p65 nuclear translocation and decreasing the expression of iNOS and the secretion of IL-1β, IL-6, and TNF-α. In addition, cNPs@BR protected ocular surface epithelium against oxidative stress and inflammation and restored conjunctival goblet cells in the mouse model of DED by activating PINK1-mediated mitophagy.

CONCLUSIONS

The cNPs@BR suppressed oxidative stress and inflammatory response in the ocular surface epithelium and restored goblet cells by activating PINK1-mediated mitophagy.