Regulation of interleukin 33/ST2 signaling of human corneal epithelium in allergic diseases

AIM: To identify the function of ST2 and explore the role of IL-33/ST2 signaling in regulating the pro-allergic cytokine production in human corneal epithelial cells (HCECs). METHODS: Human corneal tissues and cultured primary HCECs were treated with IL -33 in different concentrations without or with different inhibitors to evaluate the expression, location and signaling pathways of ST2 in regulating production of pro -allergic cytokine and chemokine. The expression of mRNA was determined by reverse transcription and real time PCR, and protein production was measured by enzyme-linked immunosorbent assay (ELISA), immunohistochemical and immunofluorescent staining. ST2 protein was detected in donor corneal epithelium, and ST2 signal was enhanced by exposure to IL-33. RESULTS: IL-33 significantly stimulated production of pro - allergic cytokines thymic stromal lymphopoietin (TSLP) and chemokine (CCL2, CCL20, CCL22) in HCECs at both mRNA and protein levels. These stimulated productions of pro -allergic mediators by IL -33 were blocked by ST2 antibody or soluble ST2 protein(P<0.05). Interestingly, the I kappa B-alpha inhibitor BAY11-7082 or NF-kappa B activation inhibitor quinazoline blocked NF -kappa B p65 protein nuclear translocation, and also suppressed the productions of these pro -allergic cytokines and chemokine induced by IL-33. CONCLUSION: These findings demonstrate that IL-33/ST2 signaling plays an important role in regulating IL-33 induced pro -allergic responses. IL -33 and ST2 could become novel molecular targets for the intervention of allergic diseases in ocular surface.