Lipopolysaccharide regulates thymic stromal lymphopoietin expression via TLR4/MAPK/Akt/NF-κB signaling pathways in nasal fibroblasts: differential inhibitory effects of macrolide and corticosteroid

Abstract BackgroundChronic rhinosinusitis (CRS) is inflammatory disease of sinonasal mucosa. Thymic stromal lymphopoietin (TSLP) is associated with Th-2 response and induced by pathogen, allergen, Toll-like receptor (TLR) ligands, and cytokines. Fibroblasts have known to modulators of wound healing, from inflammation to tissue remodeling. We examined effect of lipopolysaccharide (LPS) on TSLP production and underlying mechanisms. We aimed to determine whether effects of commonly used medications in CRS, corticosteroids and macrolides, are related to LPS-induced TSLP in nasal fibroblasts.ResultsFibroblasts were isolated from inferior turbinate tissues of CRS patients. TSLP and TLR4 expression was determined by RT-PCR, western blot, ELISA, and immunofluorescence staining. MAPK, Akt, and NF-κB phosphorylation was determined by western blot and/or luciferase assay. LPS increased TSLP expression in a dose- and time-dependent manner. LPS antagonist and corticosteroids inhibited TLR4 expression in LPS-stimulated fibroblasts. LPS-RS, macrolides, corticosteroids, and specific inhibitors suppressed LPS-induced alterations. Ex vivo culture showed similar results.ConclusionsLPS induces TSLP production via TLR4, MAPK, Akt, and NF-κB pathways. Effects of corticosteroids and macrolides are related to LPS-induced TSLP expression. We would explore new treatment modalities targeting LPS-induced TSLP production that could replace current usage of corticosteroid and macrolides in treatment of CRS.