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Published on: August 4, 2022
Suppression of NLRP3/Caspase-1/GSDMD Mediated Corneal Epithelium Pyroptosis Using Melatonin-Loaded Liposomes to
Qi Lou1, Lu Pan1, Shengjin Xiang1,2
1National Engineering Research Center of Ophthalmology and Optometry, School of Biomedical Engineering, Wenzhou Medical University, Wenzhou, 325027, People's Republic of China.
Introduction:
Benzalkonium chloride (BAC) is widely employed as a preservative in eye drops, which will cause the death of corneal epithelial cells due to ROS production, DNA strand breakage, and mitochondrial dysfunction, resulting in dry eye disease (DED)-like changes in ocular surface tissues. In this study, Melatonin (MT) liposomes (TAT-MT-LIPs) designed by loading MT into TAT-modified liposomes have been developed, characterized, and used for inhibiting BAC-induced DED (BAC-DED).
Methods:
The TAT was chemically grafted onto the Mal-PEG2000-DSPE by Michael's addition between the sulfhydryl group in TAT and the maleimide group in Mal-PEG2000-DSPE. TAT-MT-LIPs were prepared using film dispersion followed by the extrusion method and topically treated in rats once a day. BAC-DED was induced in rats by topical administration with 0.2% BAC twice daily. Defects, edema, and inflammation of the corneas, as well as IOP, were examined. Histologic analyses of corneas were performed to assess the change of mitochondrial DNA oxidation and NLRP3/Caspase-1/GSDMD signaling transduction.
Results:
After topical administration, TAT-MT-LIPs significantly alleviated DED-clinical symptoms of experimental animals by inhibiting tissue inflammation and preventing the loss of the corneal epithelium and conjunctival goblet cells. Our data suggested continuous ocular surface exposure of BAC-induced NLRP3/Caspase-1/GSDMD mediated corneal epithelium pyroptosis, which was not reported before. BAC caused substantial mt-DNA oxidation, which promoted the transduction of NLRP3/Caspase-1/GSDMD and consequent corneal epithelium pyroptosis. TAT-MT-LIPs could efficiently suppress the BAC-induced corneal epithelium pyroptosis and inflammation by inhibiting mt-DNA oxidation and the subsequent signal transmission.
Conclusion:
NLRP3/Caspase-1/GSDMD mediated corneal epithelium pyroptosis is involved in the development of BAC-DED. The present study provided new insights into the adverse effects of BAC, which can serve as a new target for protecting corneal epithelium when applying BAC as a preservative in eye drops. The developed TAT-MT-LIPs can efficiently inhibit BAC-DED and give great potential to be developed as a new DED treatment.
Insights
Benzalkonium chloride in eye drops causes dry eye disease (DED) by damaging corneal cells. Melatonin liposomes (TAT-MT-LIPs) effectively treated DED in rats by reducing inflammation and protecting corneal cells.
Area of Science:
- Ophthalmology
- Nanotechnology
- Cell Biology
Background:
- Benzalkonium chloride (BAC) is a common eye drop preservative.
- BAC causes dry eye disease (DED) by inducing corneal epithelial cell death via oxidative stress, DNA damage, and mitochondrial dysfunction.
- The NLRP3/Caspase-1/GSDMD pathway is implicated in BAC-induced corneal pyroptosis.
Purpose of the Study:
- To develop and characterize Melatonin (MT) liposomes (TAT-MT-LIPs) for inhibiting BAC-induced DED (BAC-DED).
- To investigate the protective effects of TAT-MT-LIPs against BAC-induced ocular surface damage.
- To elucidate the mechanism of action of TAT-MT-LIPs in mitigating BAC-DED.
Main Methods:
- TAT-MT-LIPs were synthesized by chemically grafting TAT onto Mal-PEG2000-DSPE and encapsulating MT.
- BAC-DED was induced in rats using topical 0.2% BAC administration.
- Corneal health, inflammation, mitochondrial DNA oxidation, and the NLRP3/Caspase-1/GSDMD pathway were assessed.
Main Results:
- TAT-MT-LIPs significantly alleviated DED symptoms, including corneal defects, edema, and inflammation.
- Treatment prevented loss of corneal epithelium and conjunctival goblet cells.
- TAT-MT-LIPs suppressed BAC-induced corneal pyroptosis by inhibiting mitochondrial DNA oxidation and the NLRP3/Caspase-1/GSDMD signaling pathway.
Conclusions:
- NLRP3/Caspase-1/GSDMD-mediated pyroptosis is a key mechanism in BAC-DED development.
- BAC's adverse effects on the cornea present a potential therapeutic target.
- TAT-MT-LIPs demonstrate significant potential as a novel treatment for BAC-induced DED.
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