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TRPV1 Activation Is Required for Hypertonicity-Stimulated Inflammatory Cytokine Release in Human Corneal Epithelial Cells

Zan Pan, Zheng Wang, Hua Yang, Fan Zhang, Peter S Reinach

Invest Ophthalmol Vis Sci. 2011 Jan 21;52(1):485-93.

PMID: 20739465

Abstract:

Purpose:
To determine whether hypertonic stress promotes increases in inflammatory cytokine release through transient receptor potential vanilloid channel type 1 (TRPV1) signaling pathway activation in human corneal epithelial cells (HCECs).
Methods:
Hyperosmotic medium was prepared by supplementing isotonic Ringers solution with sucrose. Ca2+ signaling was measured in fura2-AM-loaded HCECs using a single-cell fluorescence imaging system. Western blot analysis evaluated the phosphorylation status of EGFR, ERK, p38 MAPK, and nuclear factor (NF)-κB. ELISA assessed the effect of TRPV1 activation on the release of IL-6 and IL-8.
Results:
A 450 mOsm hypertonic stress elicited 2-fold Ca2+ transients that were suppressed by the TRPV1-selective antagonists capsazepine and JYL 1421. Such transients were enhanced by PGE2. Hypertonicity-induced EGF receptor (EGFR) transactivation was suppressed by preincubating HCECs with capsazepine, matrix metalloproteinase 1 (MMP1) inhibitor TIMP-1, broad-spectrum MMP inhibitor GM 6001, heparin-bound (HB)-EGF inhibitor CRM 197, or EGFR inhibitor AG 1478. ERK and p38 MAPK and NF-κB activation after EGFR transactivation occurred in tonicity and in a time-dependent manner. Hypertonicity-induced increases in IL-6 and IL-8 releases were suppressed by exposure to capsazepine, AG 1478, ERK inhibitor PD 98059, p38 inhibitor SB 203580, or NF-κB inhibitor PDTC.
Conclusions:
Hypertonic stress-elicited TRPV1 channel stimulation mediates increases in a proinflammatory cytokine IL-6 and a chemoattractant IL-8 by eliciting EGFR transactivation, MAPK, and NF-κB activation. Selective drug modulation of either TRPV1 activity or its signaling mediators may yield a novel approach to suppressing inflammatory responses occurring in dry eye syndrome.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
IAR42415514 InSolution SB 203580 InSolution SB 203580 Price
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