Abstract
Purpose :
Bacterial keratitis is a leading cause of corneal opacification and vision loss worldwide. A common causative organism of bacterial keratitis is Staphylococcus aureus (SA), a gram-positive pathogen known for its ability to develop antibiotic resistance. It is well established that SA is able to invade phagocytic and non-phagocytic cells and establish an intracellular niche. In addition to regulating metabolism and cell death, mitochondria are emerging as important mediators of host-pathogen interactions. This study investigated the effects of SA infection on mitochondrial dynamics, morphology, and metabolism in corneal epithelial cells.
Methods :
A standard invasive test strain of SA (RN6390) was used to infect telomerase-immortalized human corneal epithelial (hTCEpi) cells for up to 3 hours. Mitochondrial metabolism was quantified using a seahorse metabolic flux analyzer. Mitochondrial polarization and morphological changes were characterized using the membrane permeant MitoProbe JC1 and transmission electron microscopy (TEM), respectively. Mitophagy pathways were evaluated by western blot to detect PINK-1, PARKIN, FUNDC-1, BNIP3L/NIX. Mitochondrial fission was evaluated using western blot to detect DRP1, pDRP1-Ser 616 and FIS1.
Results :
SA induced mitochondrial depolarization as early as 30 minutes post-infection. The amount of depolarization increased with time, with complete depolarization seen at 3 hours. Infection with SA induced PINK1/PARKIN and FUNDC1-mediated mitophagy. Consistent with an increase in mitophagy, there was an increase in mitochondrial fission. There was evidence of morphological changes in mitochondria by TEM.
Conclusions :
SA invasion of hTCEpi cells alters mitochondrial and metabolic homeostasis in hTCEpi cells. Further studies are needed to determine how SA-induced mitochondrial alterations facilitate establishment an intracellular niche to promote SA survival.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.