Abstract
We previously profiled duodenal microbiome in active (a-), gluten-free diet (GFD) celiac disease (CD) patients and controls finding higher levels of the Proteobacterium Neisseria flavescens in a-CD patients than in the other two groups. Here, we investigate the oropharyngeal microbiome in CD patients and controls to evaluate whether this niche share microbial composition with the duodenum. We characterized by 16S rRNA gene sequencing the oropharyngeal microbiome in 14 a-CD, 22 GFD patients and 20 controls. Bacteroidetes, Proteobacteria and Firmicutes differed significantly between the three groups. In particular, Proteobacteria abounded in a-CD and Neisseria species mostly accounted for this abundance (p < 0.001), whereas Bacteroidetes were more present in control and GFD microbiomes. Culture-based oropharyngeal microbiota analysis confirmed the greater abundance of Proteobacteria and of Neisseria species in a-CD. Microbial functions prediction indicated a greater metabolic potential for degradation of aminoacids, lipids and ketone bodies in a-CD microbiome than in control and GFD microbiomes, in which polysaccharide metabolism predominated. Our results suggest a continuum of a-CD microbial composition from mouth to duodenum. We may speculate that microbiome characterization in the oropharynx, which is a less invasive sampling than the duodenum, could contribute to investigate the role of dysbiosis in CD pathogenesis.
Highlights
Celiac disease (CD) is a complex autoimmune enteropathy triggered by ingestion of gluten in genetically susceptible individuals[1], alterations in the gut microbiome have been implicated in its pathogenesis[2,3,4,5]
The objectives of our study were: (1) to characterize by 16S rRNA sequencing and by a culture-based approach the oropharyngeal microbiota in three groups: a-celiac disease (CD), gluten-free diet (GFD) patients and control subjects; (2) to evaluate if the CD-associated oropharyngeal microbiome share the duodenal microbial composition as previously found[3] and here profiled in a new subgroup of active CD (a-CD) patients, which would suggest a continuum between these two niches[3]; and (3) to evaluate, by microbial functions prediction, if the metabolic potential is different in a-CD, GFD patients and controls
Mean age did not differ among the groups, whereas female gender was lower (p = 0.001) in a-CD than in GFD patients (Table S1)
Summary
Celiac disease (CD) is a complex autoimmune enteropathy triggered by ingestion of gluten in genetically susceptible individuals[1], alterations in the gut microbiome (virus and some bacterial strains) have been implicated in its pathogenesis[2,3,4,5]. The CD trigger (i.e., gluten) is first processed in the mouth, and here the oral microbiota might have an impact on the immunogenic peptides produced after this first part of digestion process[10] In this scenario, the objectives of our study were: (1) to characterize by 16S rRNA sequencing and by a culture-based approach the oropharyngeal microbiota in three groups: a-CD, GFD patients and control subjects; (2) to evaluate if the CD-associated oropharyngeal microbiome share the duodenal microbial composition as previously found[3] and here profiled in a new subgroup of a-CD patients, which would suggest a continuum between these two niches[3]; and (3) to evaluate, by microbial functions prediction, if the metabolic potential is different in a-CD, GFD patients and controls.
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