Abstract
Purpose :
Gram-positive bacteria, especially staphylococci remain the leading cause of bacterial endophthalmitis. The severe vision loss is attributed, in part, to their increasing resistance to antibiotics, leading to treatment failure. Hence, newer antimicrobials are needed to combat multidrug resistant ocular infections. The aim of this study is to identify non-antibiotic drugs/molecules and test their therapeutic efficacy using experimental models of S. aureus (SA) endophthalmitis.
Methods :
Temporal transcriptomic analysis was performed using mouse retina infected with SA. The transcriptomic data was used for systems biology analyses to establish gene signature sets and to identify potential candidate drugs using connectivity map (CMAP). The MIC and cytotoxicity of the predicted drugs were determined. In vitro studies were performed on human Muller glia and retinal pigment epithelial cells to check modulation of inflammatory responses challenged with methicillin-sensitive strain (RN6390) and methicillin-resistant strain (USA300). In vivo efficacy of the drugs was evaluated in mouse model of USA300 endophthalmitis. The effect of drug treatment on SA-induced gene expression was performed by RNAseq of BMDMs.
Results :
Our systems biology and CMAP analysis predicted three drugs, Dequalinium chloride (DC), Clofilium tosylate (CT) and Glybenclamide (Glb) which counter regulate the infection signatures of SA endophthalmitis. All predicted drugs exhibited anti-inflammatory properties in cells when challenged with sensitive or resistant strains of SA. Moreover, post drug treatment, a reduction in inflammation was also observed in response to LPS stimuli and heat-killed SA in cultured retinal cells. DC and CT were more effective than Glb in all the cell lines. The RNAseq analyses revealed downregulation of inflammatory signatures in MRSA infected BMDMs. In vivo data showed that while all three drugs reduced intraocular inflammation, DC and CT could reduce the bacterial burden as well.
Conclusions :
The predicted three drugs were able to suppress inflammatory mediators during ocular SA and MRSA infection in cells. DC and CT were effective in controlling bacterial burden, while all three efficiently suppressed inflammatory responses in MRSA infected mice eyes.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.