Interleukin-18 expression and modulation in human corneal epithelial cells.

Area of Science:

• Ophthalmology
• Immunology
• Cell Biology

Background:

• Interleukin-18 (IL-18) is a pro-inflammatory cytokine that induces interferon-gamma (IFN-gamma) production by T-cells.
• The role of IL-18 in corneal inflammation is not well understood.
• Expression of IL-18 in human corneal epithelial cells has not been previously reported.

Purpose of the Study:

• To investigate whether human corneal epithelial cells can produce IL-18.
• To determine if pro-inflammatory mediators modulate IL-18 expression in these cells.
• To assess the potential role of corneal IL-18 in IFN-gamma-dependent inflammation.

Main Methods:

• Northern blot analysis and ELISA were used to detect IL-18 mRNA and protein in human corneal epithelial cells (HCEC and HCET).
• Cells were treated with lipopolysaccharide (LPS), phorbol 12-myristate 13-acetate (PMA), or poly (dI:dC) to assess modulation of IL-18 expression.
• IL-18 bioactivity was measured using a leukocyte IFN-gamma induction assay, and IL-18 was localized in human cornea via immunohistochemistry.

Main Results:

• Human corneal epithelial cells constitutively express IL-18 mRNA and bioactive protein.
• Pro-inflammatory agents (LPS, PMA, poly (dI:dC)) upregulated IL-18 expression.
• Immunohistochemistry confirmed IL-18 protein expression in the epithelial cells of whole human cornea.

Conclusions:

• This study provides the first evidence that human corneal epithelial cells produce the IFN-gamma inducing factor IL-18.
• Corneal IL-18 production is inducible by pro-inflammatory stimuli.
• Corneal IL-18 may play a significant role in initiating IFN-gamma-mediated inflammatory responses within the cornea.