Redefining the human corneal immune compartment using dynamic intravital imaging.

Area of Science:

• Ophthalmology
• Immunology
• Cell Biology

Background:

• The human cornea's immune cells are crucial for vision preservation.
• Immune cells in the cornea are traditionally identified as dendritic cells (DCs).
• Altered immune cell morphology is a known indicator of corneal inflammation and injury.

Purpose of the Study:

• To investigate the identity and behavior of immune cells in the healthy human cornea.
• To challenge the prevailing assumption that corneal immune cells are primarily DCs.
• To understand how corneal immune cells respond to acute and chronic inflammatory stimuli.

Main Methods:

• Development and application of functional in vivo confocal microscopy (Fun-IVCM) for human corneal imaging.
• In vivo imaging of immune cell dynamics within the corneal epithelium and stroma.
• Observation of immune cell behavior under normal conditions and in response to stimuli like contact lens wear and allergies.

Main Results:

• Many resident immune cells in the healthy human cornea are T cells, specifically intraepithelial lymphocytes (IELs).
• These corneal IELs display rapid, continuous movement and interact with corneal DCs and sensory nerves.
• Macrophages and T cells were observed patrolling the corneal stroma, with altered behaviors noted during inflammation.

Conclusions:

• The study redefines the understanding of immune cell populations in the human cornea, identifying T cells as key residents.
• Corneal T cells (IELs) exhibit unique motility and interactions, contributing to immune surveillance.
• The findings provide new insights into the dynamic response of corneal immune cells to various stimuli, including therapeutic interventions.