Abstract
Purpose :
Bacterial endophthalmitis remain one of the major complications of ocular surgeries and trauma. The current treatment involves intravitreal injections of antibiotics which control bacterial growth but not inflammation. We adapted integrative transcriptomics and metabolomics approach to identify immunomodulatory pathways altered during endophthalmitis. The aim of this study is to investigate the role of GSNO, whose levels drastically reduced in Staphylococcus (S) aureus infected mouse retina.
Methods :
Endophthalmitis was induced by intravitreal injections of S.aureus in B6 mice. Both prophylactic and therapeutic efficacy of GSNO was determined by giving GSNO via intravitreal, oral or combination route. Disease progression was monitored by eye exam using microscope, bacterial burden enumeration, inflammatory mediators and ERG determination. For in vitro studies, human retinal cells were treated with GSNO prior to S.aureus infection. The expression of inflammatory mediators was performed by qPCR and ELISA. Cultured retinal cells were evaluated for viability post GSNO treatment with S.aureus infection. ARPE-19 cells were used to determine the effect of GSNO on outer blood-retinal barrier (BRB) integrity in response to S.aureus infection by assessing the expression of tight junction proteins and fluorescein isothiocyanate (FITC)-dextran transepithelial permeability assay.
Results :
Our data showed that GSNO(1µg/eye) treatment significantly reduced bacterial burden and pro-inflammatory mediators' levels when administered prophylactically. The oral administration of GSNO(1mg/kg) for 48h also exerted protective effects as evidenced by a gradual decline in bacterial cfu as well as in intraocular inflammation. In vitro studies showed attenuation of S. aureus induced inflammatory mediators in cultured retinal cells. Oral GSNO treatment exhibited synergy with intravitreal vancomycin injection in bacteria-infected eyes. Interestingly, GSNO treatment reduced bacteria-induced RPE cell death indicating cytoprotection. Moreover,GSNO strengthened the outer BRB as evidenced by preserved ZO-1 staining and reduced transepithelial permeability in response to S.aureus infection.
Conclusions :
Our study revealed that GSNO administration exert both antibacterial, anti-inflammatory and cytoprotective properties in the eye. Thus, GSNO can be used as immunomodulatory therapeutic to ameliorate bacterial endophthalmitis.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.