Bacteria induce autophagy in a human ocular surface cell line.

Area of Science:

• Cell Biology
• Microbiology
• Ophthalmology

Background:

• Autophagy is a cellular defense mechanism against pathogens.
• The role of autophagy in corneal infections by bacteria is not well understood.
• Understanding bacterial manipulation of autophagy is crucial for ocular health.

Purpose of the Study:

• To create a human corneal epithelial cell line that reports autophagy activity.
• To investigate if common ocular bacterial pathogens induce autophagy in corneal cells.
• To explore how bacterial secretomes affect autophagy in the ocular surface.

Main Methods:

• Developed a lentivirus-based autophagy reporter cell line using human corneal limbal epithelial (HCLE) cells expressing LC3-GFP.
• Validated the reporter system using known autophagy inducers (rapamycin, ammonium chloride) and inhibitors (3-MA, bafilomycin).
• Exposed the reporter cells to secretomes from various ocular bacterial pathogens and analyzed LC3-GFP puncta formation.

Main Results:

• The HCLE autophagy reporter cell line was successfully developed and validated.
• Secretomes from Escherichia coli, Serratia marcescens, and Staphylococcus aureus (MSSA and MRSA) induced autophagy.
• Acinetobacter baumannii and other tested bacteria did not induce autophagy. Differences in autophagy activation were observed between MRSA and MSSA isolates.
• Inhibition of autophagy with 3-MA increased susceptibility to S. marcescens and MRSA, but not with bafilomycin A1.

Conclusions:

• A novel autophagy reporter cell line for corneal research has been established.
• Specific ocular bacterial pathogens differentially modulate autophagy in corneal epithelial cells.
• Findings suggest bacterial species and even strains (MRSA vs. MSSA) vary in their ability to manipulate host autophagy, impacting keratitis pathogenesis.