Expression of the interleukin-4 receptor α in human conjunctival epithelial cells

Aim To investigate the expression and function of interleukin-4 receptor alpha (IL-4R alpha) in human conjunctival epithelial cells (HCjECs). Methods The presence of IL-4R alpha mRNA and protein was examined by reverse transcription (RT) PCR and immunohistology, respectively. Cell surface expression was examined by flow cytometry. The effects of interleukin (IL)-4 or IL-13 on the tyrosine phosphorylation of signal transducer and the activator of transcription 6 (STAT6) were evaluated by immunoblot analyses. The transcripts upregulated upon IL-4 stimulation were examined using GeneChip, and confirmed by quantitative RT-PCR. Results IL-4R alpha mRNA and protein were detected in human conjunctival epithelium. IL-4R alpha protein was expressed on the cell surface of HCjECs. IL-4 and IL-13 induced tyrosine phosphorylation of STAT6. GeneChip analysis showed that nine transcripts were upregulated more than fourfold by IL-4 stimulation in the primary HCjECs from two individuals. Quantitative RT-PCR assay confirmed the upregulation of these transcripts: lecithin retinol acyltransferase (LRAT), calpain (CAPN14), tumour necrosis factor alpha-induced protein 6 (TNFAIP6), RAS guanyl-releasing protein 1 (RASGRP1), endothelin receptor type A (EDNRA), hyaluronan synthase 3 (HAS3), cathepsin C (CTSC), carbonic anhydrase II (CA2) and cytokine-inducible SH2-containing protein (CISH). Conclusions HCjECs expressed functioning IL-4R alpha, and IL-4 stimulation induced the expression of several genes.