The role of toll-like receptor 4 in corneal epithelial wound healing

Area of Science:

• Ophthalmology
• Immunology
• Cell Biology

Background:

• Corneal epithelial wound healing is a complex process involving cell migration, proliferation, and inflammation.
• Toll-like receptors (TLRs) are key components of the innate immune system, but their specific roles in ocular surface repair are not fully understood.

Purpose of the Study:

• To investigate the role of Toll-like receptor 4 (TLR4) in the process of corneal epithelial wound healing.
• To determine if TLR4 activation influences the migration and proliferation of human corneal epithelial cells (HCEC).

Main Methods:

• Examined TLR4 expression in vivo using immunostaining in a murine corneal wound model.
• Assessed TLR4 expression and activation in primary and immortalized HCEC.
• Utilized scratch assays, Transwell migration assays, and Ki67 immunostaining to evaluate wound closure, migration, and proliferation.
• Administered lipopolysaccharide (LPS) to activate TLR4 and CLI-095 to inhibit it.
• Measured inflammatory cytokine expression (IL-6, TNF-α, CXCL8/IL8, CCL5/RANTES) and signaling pathway activation (p42/44, p38).

Main Results:

• TLR4 expression was significantly upregulated in the corneal epithelium following wounding, both in vivo and in vitro.
• Activation of TLR4 with LPS significantly enhanced HCEC migration, proliferation, and wound closure.
• Inhibition of TLR4 led to a significant decrease in these repair processes.
• LPS treatment increased the expression of pro-inflammatory cytokines and activated key signaling pathways (p42/44, p38).

Conclusions:

• Epithelial wounding induces the expression and activation of functional TLR4 on corneal epithelial cells.
• TLR4 signaling plays a crucial role in promoting early corneal epithelial wound repair by enhancing cell migration and proliferation.