Tobacco Smoke Exposure is Characterized by a Distinct Nasal Rhinotype in a Pediatric Population

Secondhand tobacco smoke exposure (TSE) increases susceptibility to respiratory diseases, but the mechanisms of action are poorly understood. Here we study the effect of TSE in the nasal microbiome of children, and to evaluate whether such effect is dose-dependent with measured levels of cotinine in saliva and urine. This study was performed at the Mount Sinai Kravis Childrens Hospital (New York, NY) and the Johns Hopkins Hospital (Baltimore, MD). We enrolled 236 children between 6 months and 10 years of age, both inpatients and outpatients. We collected swabs to characterize the diversity and composition of the nasal microbiome using 16S rRNA gene sequencing and measured cotinine levels in salivary and urinary samples to quantify TSE. We then determined the relationship between these measures and participant respiratory conditions, demographics and lifestyle factors. We found that infants with high cotinine levels had lower nasal microbiome alpha diversity and an enrichment in Moraxella, Dolosigranulum and Corynebacterium, which formed a distinct cluster in network analysis. A Dirichlet Multinomial Mixture model identified the existence of two distinct microbial rhinotypes, the first one characterized by significantly higher cotinine levels, lower alpha diversity, and enrichment of these taxa. Children with higher cotinine levels had reduced alpha diversity and a distinct nasal rhinotype. Our results suggest TSE is associated with alterations of the nasal microbiome and identify a rhinotype as a potential biomarker for TSE. ### Competing Interest Statement The authors have declared no competing interest.