The interaction between neuropeptides and the innate immune system in the nasal mucosa of healthy individuals and subjects with allergic rhinitis

Abstract

Allergic rhinitis is a highly common disease prevalent worldwide. The symptoms include rhinorrhea, itchy eyes and swelling. It is driven by Immunoglobulin E and a type 2 T cell response resulting in inflammation in the upper airways. Allergic rhinitis is often under diagnosed and has no cure, only treatments with varying efficiency. The role of the peripheral nervous system has classically not been thought of as part of the immune system. Recent studies have however, been successful in demonstrating its involvement. One of its most studied mediators, substance P (SP), seems to have a role in priming the innate immune system for incoming dangers. SP and Toll-like Receptors (TLRs) have been shown to regulate one another’s expression in healthy individuals. This project aimed to compare this cross-talk in healthy and allergic subjects. Analysis was made for additional receptors CD10, NK1R and VIPR2 and will also involve the cytokine interleukin 6 (IL-6) which is an important pro-inflammatory cytokine expressed following TLR ligand binding. Healthy and allergic individuals volunteered to leave nasal epithelial cells for culturing. These samples were stimulated with either SP or with R837, the synthetic ligand for TLR7. The project included three major methods; Enzyme-linked immunosorbent assay (ELISA), Realtime quantitative PCR and fluorescent activated cell sorting (FACS). Stimulation with R837 did not give any significant differences in the transcription of genes coding for SP, tac1, and its receptor of choice, tacr1, between 7 healthy and 9 allergic subjects. Real-time qPCR for genes tlr4 and tlr9 showed that transcription of tlr4 was significantly elevated in allergic subjects and that the same was true for transcription of tlr9 but in healthy individuals, following SP exposure. Competitive-ELISA for SP proved that allergic individuals have a slower response to R837 stimulation, secreting significantly less of SP after 15 minutes compared to healthy individuals. The FACS results were hard to interpret and are unusable due to heavily split cells and persistent infections that resulted in a too small patient group for the allergic subjects (n=1). Future projects could include more patients for FACS, more extensive analysis for CD10, incorporating it in the qPCR analysis and to perform an ELISA measuring the antiinflammatory neuropeptide Vasoactive Intestinal Peptide (VIP) as it has antagonistic properties towards SP