Comparison of Microbial Populations in Saliva and Feces from Healthy and Celiac Adolescents with Conventional and Molecular Approaches after Cultivation on Gluten-Containing Media: An Exploratory Study.

Tilen Senicar,Valerija Tkalec,Jernej Dolinsek,Andraz Kukovicic,Maja Rupnik,Aleksander Mahnic

doi:10.3390/microorganisms9112375

Tilen Senicar, Valerija Tkalec + Show 4 more

Open Access

https://doi.org/10.3390/microorganisms9112375

Copy DOI

Abstract

Microbes capable of metabolizing gluten are common in various parts of the intestinal tract. In this study, saliva and fecal samples were obtained from 10 adolescents (13–18 years of age), five of which had celiac disease (CD) and five of which were healthy volunteers (HV). Culture-enriched saliva and fecal samples were compared with molecular profiling, and microorganisms displaying lysis zones on gluten-containing media (i.e., gluten-degrading microorganisms; GDMs) were isolated. In total, 45 gluten-degrading strains were isolated, belonging to 13 genera and 15 species, including Candida albicans and Veillonella. GDMs were more common in HVs compared to CD patients and more diverse in saliva compared to feces. In saliva, GDMs showed partial overlap between HVs and CD patients. Bacterial communities in fecal samples determined with amplicon sequencing significantly differed between CD patients and HVs. Overall, 7–46 of all operational taxonomic units (OTUs) per sample were below the detection limit in the fecal samples but were present in the cultivated samples, and mainly included representatives from Lactobacillus and Enterococcus. Furthermore, differences in fecal short-chain fatty-acid concentrations between CD patients and HVs, as well as their correlations with bacterial taxa, were demonstrated.

Highlights

Celiac disease (CD) is a chronic inflammatory disease with a global prevalence of approximately 1%
The bacterial populations from the original samples and various cultivation conditions were characterized by 16S rRNA amplicon sequencing, and short-chain fatty acid (SCFA)
The fecal bacterial communities significantly differed between CD patients and healthy volunteers (HV) (AMOVA, p = 0.04)

Summary

Introduction

Celiac disease (CD) is a chronic inflammatory disease with a global prevalence of approximately 1%. Inflammation in CD occurs due to abnormal immune responses after gluten intake in genetically susceptible individuals [1]. Microbiota from different intestinal tract niches and their metabolites can be associated with CD in several ways [2,3,4,5,6]. Salivary and fecal microbiota differ between CD patients and healthy controls [2,3,4,7]; no disease-specific microbial signatures have been described. Specific changes were associated with different clinical manifestations of the disease [2]. Microbiota either exhibited a protective role or exacerbated the immune response to gluten, depending on the bacterial community composition [2,8]. Microbiota can serve as a reservoir of enzymes for gluten degradation [8], which can result in products with either increased or decreased immunogenic properties [2,9,10]

Objectives

Methods

Results

Discussion

Conclusion