Abstract
Mouth breathing induces a series of diseases, while the influence on microbiota of oral cavity and salivary proteins remains unknown. In this study, for the first time, profiles of oral–nasal–pharyngeal microbiota among mouth-breathing children (MB group, n = 10) were compared with paired nose-breathing children (NB group, n = 10) using 16S ribosomal DNA (rDNA) (V3–V4 region) high-throughput sequencing. The differentially expressed salivary proteins were revealed using label-free quantification (LFQ) method, and their associations with bacterial abundance were measured by canonical correspondence analysis (CCA). The overall bacterial profiles differed between the two groups, and the differences were related to the duration of mouth breathing. The diversity of oral–pharyngeal microbiota was significantly higher, and the nasal–pharyngeal species tended to be consistent (unweighted UniFrac, p = 0.38) in the MB group. Opportunistic pathogens were higher in relative abundance as follows: Acinetobacter in the anterior supragingival plaque, Neisseria in unstimulated saliva, Streptococcus pneumoniae in the pharynx, and Stenotrophomonas in the nostrils. The expression level of oxidative-stress-related salivary proteins (lactoylglutathione lyase and peroxiredoxin-5) were upregulated, while immune-related proteins (integrin alpha-M and proteasome subunit alpha type-1) were downregulated in MB group. The differentially expressed proteins were associated with specific bacteria, indicating their potentials as candidate biomarkers for the diagnosis, putatively early intervention, and therapeutic target of mouth breathing. This study showed that mouth breathing influences the oral–nasal–pharyngeal microbiota and enriches certain pathogens, accompanied with the alterations in the salivary environment. Further research on the pathological mechanisms and dynamic changes in longitudinal studies are warranted.
Highlights
Microbiota and proteins play a very important role in human health and have a profound effect on human diseases
The sequences were clustered into 46,880 operational taxonomic units (OTUs) with 97% identity
34 phyla, 89 classes, 178 orders, 292 families, and 601 genera were annotated from the 46,880 OTUs
Summary
Microbiota and proteins play a very important role in human health and have a profound effect on human diseases. Mouth Breathing Causes Alterations deficiency virus (HIV) infection, cardiovascular diseases, and Alzheimer’s disease (AD) (Gao et al, 2018). Respiratory tract flora are associated with many diseases, such as asthma (Izuhara et al, 2016), cystic fibrosis (CF) (Pittman et al, 2017), chronic obstructive pulmonary disease (COPD) (Dima et al, 2016), pneumonia (Gollwitzer and Marsland, 2014), and lung cancer (Hosgood et al, 2014). Salivary proteins have been suggested to be a diagnostic tool for oral and systemic diseases, such as oral leukoplakia, caries, periodontal disease, Sjögren’s syndrome, cancer, cardiovascular disease, and stroke (Castagnola et al, 2017; Lorenzo-Pouso Alejandro et al, 2018). Whether exogenous factors, such as mouth breathing, will cause dysbiosis of the microbiota or alteration of saliva state. Mouth breathing has attracted more considerable attention, with prevalence between 48 and 56.8% (Felcar et al, 2010; Limeira et al, 2013)
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