Abstract
Although interleukin (IL)-13 and neurotrophins are functionally important for the pathogenesis of immune responses, the interaction of these pathways has not been explored. Herein, by interrogating IL-13-induced responses in human epithelial cells we show that neurotrophic tyrosine kinase receptor, type 1 (NTRK1), a cognate, high-affinity receptor for nerve growth factor (NGF), is an early transcriptional IL-13 target. Induction of NTRK1 was accompanied by accumulation of activating epigenetic marks in the promoter; transcriptional and epigenetic changes were signal transducer and activator of transcription 6 dependent. Using eosinophilic esophagitis as a model for human allergic inflammation, we found that NTRK1 was increased in inflamed tissue and dynamically expressed as a function of disease activity and that the downstream mediator of NTRK1 signaling early growth response 1 protein was elevated in allergic inflammatory tissue compared with control tissue. Unlike NTRK1, its ligand NGF was constitutively expressed in control and disease states, indicating that IL-13-stimulated NTRK1 induction is a limiting factor in pathway activation. In epithelial cells, NGF and IL-13 synergistically induced several target genes, including chemokine (C-C motif) ligand 26 (eotaxin-3). In summary, we have demonstrated that IL-13 confers epithelial cell responsiveness to NGF by regulating NTRK1 levels by a transcriptional and epigenetic mechanism and that this process likely contributes to allergic inflammation.