Mechanoreceptor Piezo1-Mediated Interleukin Expression in Conjunctival Epithelial Cells: Linking Mechanical Stress to Ocular Inflammation

Abstract

PurposeMechanical stress on the ocular surface, such as from eye-rubbing, has been reported to lead to inflammation and various ocular conditions. We hypothesized that the mechanosensitive Piezo1 channel in the conjunctival epithelium contributes to the inflammatory response at the ocular surface after receiving mechanical stimuli. MethodsHuman conjunctival epithelial cells (HConjECs) were treated with Yoda1, a Piezo1-specific agonist, and various allergens to measure cytokine expression levels using qRT-PCR and Western blot. Piezo1 activation-induced intracellular signaling pathways were also investigated. Mechanical stretching experiments were conducted to simulate Piezo1 activation in HConjECs. In in vivo studies, using immunohistochemistry, rats were administered Yoda1 eye drops to examine the inflammatory response in the conjunctiva and Piezo1-induced signaling activation. ResultsHConjECs expressed functional Piezo1 channel, and its activation significantly increased IL-6 and IL-8 expression through the p38 MAPK-CREB pathway. Piezo1-induced [Ca2+]i elevation was crucial for the production of IL-6. Mechanical stretching mimicked these effects. In vivo, Yoda1 administration led to enhanced immunoreactivity of phospho-p38 MAPK and phospho-CREB and increased IL-6 in the rat conjunctival epithelium. Significant neutrophil infiltration was also observed after Piezo1 channel activation without affecting eosinophil numbers. ConclusionMechanical stress-induced Piezo1 channel activation in conjunctival epithelial cells can cause ocular inflammation by upregulating pro-inflammatory cytokines via the p38 MAPK-CREB pathway and promoting neutrophil infiltration. These findings suggest that mechanical stimuli on ocular surface tissues are significant risk factors for ocular inflammation. HighlightsO_LIPiezo1 channel activation increased IL-6 via p38 MAPK-CREB pathway in Human conjunctival epithelial cells (HConjECs). C_LIO_LIPiezo1 activation mimicked fungal extract but not pollen or dust mite. C_LIO_LIMechanical stretching mimicked Piezo1 effects, boosting IL-6 production in HConjECs. C_LIO_LIPiezo1 activation elevated p-p38 MAPK, p-CREB, and IL-6 in the rat conjunctiva. C_LIO_LIPiezo1 activation leads to neutrophil infiltration in the rat conjunctival epithelium. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=152 SRC="FIGDIR/small/600298v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@1c68f87org.highwire.dtl.DTLVardef@f9226corg.highwire.dtl.DTLVardef@42f264org.highwire.dtl.DTLVardef@1378c99_HPS_FORMAT_FIGEXP M_FIG C_FIG Mechanosensitive Piezo1 channel activation induces IL-6 expression in the conjunctival epithelial cells via elevation of [Ca2+]i and activation of p38 MAPK and transcription factor CREB. Mechanical stress stimulates Piezo1 channel and Ca2+ influx through it, which induces activation of p38 MAPK. A transcription factor CREB is phosphorylated after p38 MAPK activation, then promotes IL-6 transcription.