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Cytokine, chemokine, and adhesion molecule expression mediated by MAPKs in human corneal fibroblasts exposed to

Yang Liu1, Kazuhiro Kimura, Ryoji Yanai

  • 1Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan.

Investigative Ophthalmology & Visual Science
|July 29, 2008
PubMed
Abstract

Insights

Polyinosinic-polycytidylic acid [poly(I:C)] activates Toll-like receptor 3 (TLR3) in corneal fibroblasts, triggering inflammatory responses. This study elucidates the pathways involved in poly(I:C)-induced inflammation in the cornea.

Area of Science:

  • Immunology
  • Ophthalmology
  • Molecular Biology

Background:

  • Viral infections trigger immune responses via pattern recognition receptors like Toll-like receptor 3 (TLR3).
  • Polyinosinic-polycytidylic acid [poly(I:C)] is a synthetic analog of viral double-stranded RNA, known to activate TLR3.
  • Corneal fibroblasts play a role in ocular immune responses, but their specific responses to TLR3 activation are not fully understood.

Purpose of the Study:

  • To investigate the effects of poly(I:C) on human corneal fibroblasts.
  • To identify the proinflammatory cytokines, chemokines, and adhesion molecules induced by poly(I:C).
  • To elucidate the underlying signaling pathways, including mitogen-activated protein kinases (MAPKs) and nuclear factor-kappaB (NF-kappaB), involved in these responses.

Main Methods:

  • Human corneal fibroblasts were treated with poly(I:C).
  • Expression of adhesion molecules (ICAM-1, VCAM-1) and TLR3 was assessed via immunoblot and immunofluorescence.
  • Cytokine and chemokine release (IL-6, IL-8, G-CSF, MIP-1beta, eotaxin, RANTES) was measured using assay kits.
  • MAPK activation, IkappaB-alpha phosphorylation/degradation, and NF-kappaB p65 nuclear translocation were analyzed by immunoblot and immunofluorescence.

Main Results:

  • Poly(I:C) upregulated TLR3 expression and induced the release of multiple proinflammatory cytokines and chemokines.
  • Expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 was significantly increased.
  • Poly(I:C) activated MAPKs (ERK, p38, JNK) and induced NF-kappaB pathway activation, evidenced by IkappaB-alpha degradation and p65 nuclear translocation.
  • Specific MAPK inhibitors differentially affected poly(I:C)-induced responses.

Conclusions:

  • Poly(I:C) activates TLR3 in corneal fibroblasts, leading to MAPK-dependent expression of inflammatory mediators and NF-kappaB activation.
  • Corneal fibroblasts are key players in orchestrating local immune and inflammatory responses within the corneal stroma during viral infections.
  • These findings highlight the role of corneal fibroblasts in antiviral immunity and potential therapeutic targets.

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