Abstract
Purpose :
Klebsiella pneumoniae (KP) is a blood borne infection that may metastasis to the eye causing devastating visual disability. The retinal pigment epithelium (RPE) serves as an outer blood retinal barrier during KP infection. Nevertheless, knowledge of how and what promotes KP adheres and invades RPE cells in diabetic settings remained limited. In this study, we investigated the hypothesis that the molecular changes in the diabetic RPE environment facilitated KP endophthalmitis.
Methods :
We investigated the ability of KP to invade human RPE cells (ARPE-19) in in vitro diabetic condition (HIGH (27.5mM) versus CTRL (17.5mM) glucose in the culture medium). Adhesion and invasion assays were undertaken to investigate roles of tight junction proteins, adhesion molecules, acute inflammatory molecules, molecules involved in the PAMP, and antigen presentation pathway via ELISA or western blot or flow cytometric studies. The results were validated with microarray to perform transcriptomic profiling of KP-infected ARPE-19 cells in diabetic environment comparing to control, and characterized the cellular gene expression, and the role of genes encoding proteins, in the tight junction and focal adhesion pathway, antigen presentation pathway, and cytokine and cytokine receptor interaction pathway.
Results :
We concluded that KP adhesion and invasion to RPE were increased in hyperglycemic condition via breaking down specific tight junction pathway proteins (tight junction proteins and occludins) and enhancing specific adhesion molecules including vascular cell adhesion protein 1 (VCAM-1), epithelial cell adhesion molecule (EPCAM), and E-cadherin (CDH1 gene). Furthermore, during KP invasion, antigen presentation pathway was upregulated, with specifically through promoting HLA-DR gene. After KP colonization, cytokine-cytokine receptor interaction pathway was upregulated through IL-6 and NFkB signalling.
Conclusions :
This is the first study to highlight the tight junction proteins and focal adhesion molecules engaged, and the signal transduction after antigen presentation during KP invasion to the RPE cells in diabetic ocular condition in vitro. The data suggest that KP endophthalmitis is a result of specific inflammatory cascade and molecule activation.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.