Background and objective: Serum periostin is increased in asthma and serves as a surrogate marker for IL-13 activity in the lung. Serum levels of periostin are the most robust biomarker predicting a favourable response to the anti-IL-13 drug, lebrikizumab. We investigated the mechanisms of IL-13 stimulation of periostin, the polarized secretion of periostin and whether periostin would have a direct effect on mucin secretion by airway cells. Methods: Normal human bronchial epithelial (NHBE) cells were cultured at air-liquid interface (ALI) in the presence of IL-13, and we evaluated the effect of the specific inhibitors, leflunomide (Janus kinase (JAK)/signal transducer and activator of transcription factor 6 (STAT6) inhibitor) or PD98059 (MEK/extracellular regulated protein kinase (ERK) inhibitor), on periostin production. We examined MUC5AC secretion from NHBE cells exposed to recombinant human (rh) periostin or IL-13 in the presence and absence of OC-20, a periostin-neutralizing antibody. Results: IL-13 induced periostin protein which was predominantly secreted towards the basal surface of the cells. Periostin production was much greater from goblet cells than ciliated cells (P < 0.001). Periostin production after exposure to IL-13 was attenuated by both leflunomide (P < 0.001) and PD98059 (P < 0.001). The addition of exogenous periostin modestly increased MUC5AC secretion (P < 0.01), but did not visibly change cell morphology. IL-13-induced MUC5AC secretion was attenuated by OC-20 (P < 0.01). Conclusion: Periostin production in differentiated airway cells is mediated by JAK/STAT6 and MEK/ERK pathways. Periostin secretion is much greater from immunologically active goblet cells. IL-13-driven mucin production is partially inhibited by OC-20.

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BackgroundCOPD is characterized by persistent and progressive airway inflammation. Although neutrophilic airway inflammation is generally accepted to be a major factor in the pathogenesis of COPD, the influence of the agents used for the treatment of COPD on neutrophil functions such as chemotaxis is not fully understood.PurposeThe present study aimed to examine the influence of tiotropium bromide on the production of interleukin (IL)-8 from human airway epithelial cells and lung fibroblasts (LFs) after lipopolysaccharide (LPS) stimulation in vitro.MethodsBEAS-2B cells, human bronchial epithelial cell line, and LFs, at a concentration of 5 × 105 cells/mL, were stimulated with LPS in the presence of various concentrations of tiotropium bromide. IL-8 in culture supernatants was examined by enzyme-linked immunosorbent assay (ELISA). IL-8 messenger ribonucleic acid (mRNA) expression was examined by real-time polymerase chain reaction. The influence of tiotropium bromide on LPS-induced signaling pathways was also analyzed by examining nuclear factor-kappa (NF-κ)B activation and signaling protein phosphorylation by ELISA.ResultsTiotropium bromide at >15 pg/mL inhibited IL-8 production from both BEAS-2B cells and LFs after LPS stimulation. Tiotropium bromide also suppressed IL-8 mRNA expression through the inhibition of NF-κB activation and signaling protein, extracellular-signal-regulated kinase 1/2, and c-Jun N-terminal kinase, phosphorylation.ConclusionThe present results strongly suggest that tiotropium bromide exerts the inhibitory effect on neutrophilic inflammation through the suppression of IL-8 production from epithelial cells and LFs by interfering with LPS-mediated signaling pathways and thus may contribute to lower cellular inflammation in COPD, which is responsible for favorable modification of the disease.

The nasal epithelium expressing enriched angiotensin-converting enzyme II (ACE2), the key cell entry receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), could serve as the first barrier to protect the airway from viral infection. Recent studies have demonstrated that higher viral loads were detected in the nasal cavity than the pharynx in coronavirus disease 2019 patients, and otolaryngologists should carefully consider infection prevention in clinical practice for the treatment of nasal conditions. Moreover, several studies have indicated that anosmia is one of the clinical characteristics of COVID-19, but the precise prevalence and mechanism remain unclear. Thus far, comorbidity of allergic rhinitis and chronic rhinosinusitis do not seem to be a major risk factor for severe COVID-19. However, we should develop strategies in clinical practice for treatment of nasal diseases during the pandemic. In this article, we reviewed current evidence of the relationship between COVID-19 and nasal conditions, such as COVID-19-related olfactory dysfunction, allergic rhinitis, and chronic rhinosinusitis.