Allergic rhinitis, microbiota and passive smoke in children. a pilot study

Allergic rhinitis (AR) is one of the most common allergic diseases affecting children. Objective assessment of nasal obstruction is possible through active anterior rhi- nomanometry (AAR). Several factors, such as passive smoke exposure (PSE), are trig- gers for worsening nasal obstruction and chronic inflammation. PSE affects bacterial eubiosis in the upper respiratory tract. This study evaluates the influence of PSE and cotinine levels on both nasal obstruction and local microbiome composition in chil- dren with AR. Fifty patients (aged between 6 and 16 years) with AR monosensitized grass pollen were enrolled. They underwent skin prick tests, a nasal swab to evaluate the microbial composition of the anterior nostrils, a basal AAR, a post-decongestion AAR, and spirometry. Serum cotinine levels were assessed to evaluate PSE. A signifi- cantly lower percentage of mean nasal flow (mNF%) was observed before and after hydrazine administration in subjects exposed to passive smoke (Exp group) compared with the non-exposed group. In contrast, higher cotinine levels were observed in the Exp group than in the controls. PSE has been associated with a decrease in biodiver- sity and a change in the nasal microbiome composition; instead, although to a differ- ent extent, the abundance of specific taxa resulted in being correlated to cotinine levels and nasal flow. Children with AR exposed to passive smoke with positive serum cotinine could represent a risk factor for developing nasal obstruction and microbial dysbiosis, suggesting their possible role in pathophysiological processes.