Alarmins from corneal epithelial cells upregulate CCL11 and VCAM-1 in corneal fibroblasts

Invest Ophthalmol Vis Sci. 2013 Aug 27;54(8):5817-23. doi: 10.1167/iovs.13-11969.


Purpose: Severe ocular allergic diseases are characterized by pronounced conjunctival inflammation triggered by T helper 2 (Th2) cells and corneal epithelial damage induced by eosinophils. To examine the role of alarmins released by damaged corneal epithelial cells in tissue eosinophilia, we investigated the effects of a supernatant derived from necrotic human corneal epithelial (HCE) cells on expression of the chemokine CCL11 (eotaxin) and the adhesion molecule VCAM-1 in human corneal fibroblasts.

Methods: An alarmin preparation was obtained as the material released from HCE cells after three cycles of freezing and thawing. CCL11 released into culture medium and cell surface expression of VCAM-1 were measured with enzyme-linked immunosorbent assays, and the amounts of CCL11 and VCAM-1 mRNAs were quantitated by reverse transcription and real-time polymerase chain reaction analysis. Signaling by the transcription factor NF-κB was evaluated by immunoblot and immunofluorescence analyses.

Results: The combination of the necrotic HCE cell supernatant and either interleukin (IL)-4 or IL-13 induced synergistic increases in CCL11 release, VCAM-1 expression, and the abundance of CCL11 and VCAM-1 mRNAs in corneal fibroblasts. The necrotic HCE cell supernatant also induced NF-κB activation in corneal fibroblasts, whereas an inhibitor of NF-κB and IL-1 receptor antagonist each attenuated CCL11 release induced by the alarmin preparation and either IL-4 or IL-13.

Conclusions: Alarmins including IL-1 released from necrotic corneal epithelial cells cooperate with Th2 cytokines to induce CCL11 production and VCAM-1 expression in corneal fibroblasts, and may thereby play an important role in tissue eosinophilia associated with ocular allergic diseases.

Keywords: adhesion molecule; alarmin; allergy; chemokine; corneal fibroblasts.

MeSH terms

  • Chemokine CCL11 / metabolism*
  • Cytokines / physiology*
  • Enzyme-Linked Immunosorbent Assay
  • Epithelium, Corneal / metabolism*
  • Fibroblasts / metabolism*
  • Humans
  • Interleukin-13 / physiology
  • Interleukin-4 / physiology
  • Keratoconjunctivitis / metabolism*
  • NF-kappa B / metabolism
  • Necrosis / metabolism
  • RNA, Messenger / metabolism
  • Real-Time Polymerase Chain Reaction
  • Signal Transduction / physiology
  • Vascular Cell Adhesion Molecule-1 / metabolism*


  • CCL11 protein, human
  • Chemokine CCL11
  • Cytokines
  • Interleukin-13
  • NF-kappa B
  • RNA, Messenger
  • Vascular Cell Adhesion Molecule-1
  • Interleukin-4