Surfactant Protein D Expression in Chronic Rhinosinusitis Patients and Immune Responses In Vitro to Aspergillus and Alternaria in a Nasal Explant Model

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Abstract
Objectives/Hypothesis: Common fungi have been implicated in the pathogenesis of chronic rhinosinusitis (CRS) with eosinophilic mucus (EMCRS). Surfactant protein (SP)‐D plays an important role in the immune response to Aspergillus fumigatus in the lungs. We sought to determine whether SP‐D is expressed in nasal mucosa and investigated the response of SP‐D in vitro to fungal allergens.Study Design and Methods: 1) Nasal biopsies from 59 CRS and EMCRS patients, stratified into allergic fungal sinusitis (AFS), nonallergic fungal eosinophilic sinusitis (NAFES), and nonallergic nonfungal eosinophilic sinusitis (NANFES) were studied by quantitative reverse‐transcriptase polymerase chain reaction (qRT‐PCR), immunostaining and enzyme‐linked immunosorbent assay (ELISA). 2) Nasal tissue from three CRS and three NANFES patients was cultured with fungal allergens in a nasal explant in vitro model for 24 hours at increasing concentrations and mRNA SP‐D secreted SP‐D protein levels in response to the fungi determined by qRT‐PCR and ELISA.Results: Staining for SP‐D was detected in the submucosal glands from the nasal biopsies in all patient groups except for AFS. By ELISA, SP‐D was undetectable in AFS and decreased in NAFES, NANFES, and CRS compared with controls. CRS patients in vitro cultured with Aspergillus and Alternaria allergens in a nasal tissue explant model induced up‐regulation of SP‐D by qRT‐PCR. In contrast, NANFES nasal tissue explants cultured with Aspergillus allergens induced down‐regulation of SP‐D.Conclusions: We report for the first time the expression of SP‐D in both diseased and normal nasal mucosa. SP‐D expression in CRS patients is up‐regulated by fungal allergens in an in vitro model. These results may provide potential novel therapy for treatment of CRS.