miR-124 affects dendritic cells function in CRSwNP by regulating exosomes secretion in nasal mucosal epithelial cells

The intricate immunomodulatory mechanism underlying the onset and progression of chronic rhinosinusitis with nasal polyps (CRSwNP) in chronic sinusitis with nasal polyps remains poorly understood, particularly regarding the regulatory role of dendritic cells (DCs). MicroRNA has been identified as a modulator of DC function. Primary cells have a short time in vitro and their biological characteristics have not changed greatly which can better reflect the growth state of cells in the body, so as to obtain data closer to the physiological function in the body. Our research group has been engaged in the culture of human nasal epithelial progenitor cells (hNEPCs) for a long time, and in previous investigations, we observed downregulation of microRNA-124 (miR-124) in patients with chronic sinusitis and nasal polyps. Thus, our current study aims to elucidate the regulatory mechanism of DCs in chronic sinusitis with polyps by examining the impact of miR-124 on DCs in this context. To accomplish this, we took the nasal mucosa of CRSwNP patients and normal nasal mucosa of non-rhinitis patients for primary culture. We isolated exosomes from these cells for co-culture experiments with DCs. Flow cytometry analysis was employed to assess the maturation phenotypes (MHC II, CD80 and CD86), cell cycle and apoptosis levels of DCs. Furthermore, enzyme-linked immunosorbent assay was utilized to measure the levels of pro-inflammatory cytokines (IL-10, IL-12 and IL-23). The TLR4/NF-κB signalling pathway in co-cultured DCs was evaluated using the western blot assay. Through querying the Targetscan website, we predicted Rab27a as a target gene of miR-124, which was subsequently validated through double luciferase assay, flow cytometry and other experimental approaches. Our findings demonstrate that MiR-124 modulates the secretion of CRSwNP epithelial exosomes, thereby influencing DC function via its interaction with the target gene Rab27a. These results offer novel insights into potential therapeutic targets for the treatment of CRSwNP.