Alarmins from corneal epithelial cells upregulate CCL11 and VCAM-1 in corneal fibroblasts.
OBJECTIVE
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.
Department of Ophthalmology, Kochi Medical School, Nankoku City, Kochi, Japan. k.fukuda@kochi-u.ac.jp
Ken
K
Fukuda
Waka
W
Ishida
Hiroshi
H
Tanaka
Yosuke
Y
Harada
Akira
A
Matsuda
Nobuyuki
N
Ebihara
Atsuki
A
Fukushima
D054413:Chemokine CCL11 / Q000378:metabolism*; D016207:Cytokines / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D019573:Epithelium, Corneal / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D018793:Interleukin-13 / Q000502:physiology; D015847:Interleukin-4 / Q000502:physiology; D007637:Keratoconjunctivitis / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D009336:Necrosis / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism*
C515456:CCL11 protein, human; D054413:Chemokine CCL11; D016207:Cytokines; D018793:Interleukin-13; D016328:NF-kappa B; D012333:RNA, Messenger; D019010:Vascular Cell Adhesion Molecule-1; D015847:Interleukin-4
adhesion molecule; alarmin; allergy; chemokine; corneal fibroblasts