Abstract
Purpose :
Ferroptosis is a recently discovered non-apoptotic mode of cell death triggered by downregulation of antioxidant enzyme glutathione peroxidase 4 (GPX4). In this study, we sought to determine the role of GPX4 signaling in regulating retinal ferroptosis in bacterial endophthalmitis
Methods :
In vivo (C57BL/6 mouse) and in vitro (BMDMs, retinal Muller glia) studies were performed by infecting with S. aureus (SA). Ferroptosis induced cell death and its regulation by GPX4 was assessed by pharmacological inhibition and activation approaches. In mice, disease progression was assessed by both non-invasive (ERG and fundus exam) and invasive (bacterial burden, cytokine levels) methods. Bacterial induced downregulation of GPX4 signaling was assessed by Western blot and immunofluorescence (IFA) whereas qPCR and ELISA assays were used to check the expression of inflammatory mediators in retinal tissue or cell lysates.
Results :
Our metabolomics and transcriptomic analysis of S. aureus infected mouse retinal tissues showed a time-dependent increase in mediators of ferroptosis. SA infection was found to increase labial iron pool (LIP) and lipid peroxidation (LPO) in infected mouse retinas and bone marrow derived macrophages (BMDM). This coincided with decreased GPX4 and increased ACSL4 expression. Supplementation of iron quencher, deferiprone (DFP) along with glutathione (GSH) exerted protective effects by reducing SA induced ferroptosis cell death and inflammation both in vivo and in vitro
Conclusions :
Our study demonstrate the role of antioxidant signaling GSH-GPX4 in regulating cell death and inflammation in bacterial endophthalmitis. Thus, GPX4 activation and reducing labial iron can be used as new therapeutic approaches to ameliorate bacterial endophthalmitis
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.