High-throughput sequencing provides insights into oral microbiota dysbiosis in association with inflammatory bowel disease.

Although the prevalence of inflammatory bowel disease (IBD) has been increasing worldwide, the etiology remains elusive. Investigating oral microbiota dysbiosis is essential to understanding IBD pathogenesis. Our study evaluated variations in salivary microbiota and identified potential associations with IBD. The saliva microbiota of 22 IBD patients and 8 healthy controls (HCs) was determined using 16S ribosomal RNA (rRNA) gene sequencing and analyzed using QIIME2. A distinct saliva microbiota dysbiosis in IBD, characterized by alterations in microbiota biodiversity and composition, was identified. Saccharibacteria (TM7), Absconditabacteria (SR1), Leptotrichia, Prevotella, Bulleidia, and Atopobium, some of which are oral biofilm-forming bacteria, were significantly increased. Moreover, levels of inflammatory cytokines associated with IBD were elevated and positively correlated with TM7 and SR1. Functional variations include down-regulation of genetic information processing, while up-regulation of carbohydrate metabolism and protein processing in the endoplasmic reticulum in IBD. Our data implicate salivary microbiota dysbiosis involving in IBD pathogenesis.

Qi Y ，Zang SQ ，Wei J ，Yu HC ，Yang Z ，Wu HM ，Kang Y ，Tao H ，Yang MF ，Jin L ，Zen K ，Wang FY ... -  《-》

Dysbiosis of salivary microbiota in inflammatory bowel disease and its association with oral immunological biomarkers.

Said HS ，Suda W ，Nakagome S ，Chinen H ，Oshima K ，Kim S ，Kimura R ，Iraha A ，Ishida H ，Fujita J ，Mano S ，Morita H ，Dohi T ，Oota H ，Hattori M ... -  《-》

The oral-gut axis: Salivary and fecal microbiome dysbiosis in patients with inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a group of chronic inflammatory disorders that fall into two main categories: Crohn's disease (CD) and ulcerative colitis (UC). The gastrointestinal tract extends from the mouth to the anus and harbors diverse bacterial communities. Several sequencing-based studies have identified an intestinal enrichment of oral-associated bacteria and demonstrated their ability to induce intestinal inflammation in mice, suggesting that intestinal pathobionts originate from the oral cavity, particularly members of the genus Streptococcus. This study aimed to investigate the composition of the salivary and fecal microbiome of IBD patients (n = 14) compared to healthy controls (n = 12) and to determine the abundance of common bacterial taxa in both niches. Metagenomic DNA was extracted from saliva and fecal samples, and the 16S rRNA gene was targeted for sequencing. Our results revealed that the overall microbial composition of saliva was significantly altered in the IBD patients compared to the control subjects (p = 0.038). At the genus level, Veillonella and Prevotella were highly abundant in IBD (median: 25.4% and 22.2%, respectively) compared to the control group (17.9% and 13.4%, respectively). In contrast, Neisseria, Streptococcus, Haemophilus, and Fusobacterium were associated with a healthy gut state. Regarding the fecal microbiome, the IBD group had a significantly higher abundance of Clostridium sensu stricto 1 and Escherichia-Shigella (both comprising pathogenic bacteria) compared with the control group. Members of both bacterial groups have previously been shown to positively correlate with intestinal inflammation and high expression of pro-inflammatory cytokines that disrupt intestinal barrier integrity. In addition, we demonstrate that the increased abundance of Clostridium sensu stricto 1 and Escherichia-Shigella has also been associated with significant upregulation of certain metabolic pathways in the feces of the IBD group, including bacterial invasion of epithelial cells. Streptococcus was the only common genus detected in both the salivary and fecal microbiome and represented the oral-gut axis in our study. Using culture-based methods, we isolated 57 and 91 Streptococcus strains from saliva as well as 40 and 31 strains from fecal samples of the controls and IBD patients, respectively. The phylogenetic tree of streptococci based on sodA sequences revealed several patient-specific clusters comprising salivary and fecal streptococcal isolates from the same patient and belonging to the same species, suggesting that the oral cavity is an endogenous reservoir for intestinal strains.

Abdelbary MMH ，Hatting M ，Bott A ，Dahlhausen A ，Keller D ，Trautwein C ，Conrads G ... -  《Frontiers in Cellular and Infection Microbiology》

New Insights into the Role of Oral Microbiota Dysbiosis in the Pathogenesis of Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a group of chronic intestinal inflammatory disorders with a prolonged duration characterized by recurrent relapse and remission. The exact etiology of IBD remains poorly understood despite the identification of relevant risk factors, including individual genetic susceptibility, environmental triggers, and disruption of immune homeostasis. Dysbiosis of the gut microbiota is believed to exacerbate the progression of IBD. Recently, increasing evidence has also linked oral microbiota dysbiosis with the development of IBD. On the one hand, IBD patients show significantly unbalanced composition and function of the oral microbiota known as dysbiosis. On the other, overabundances of oral commensal bacteria with opportunistic pathogenicity have been found in the gut microbiota of IBD patients. Herein, we review the current information on the causative factors of IBD, especially recent evidence of IBD-associated oral microbiota dysbiosis, which has seldom been covered in the previous literature review, highlighting the pathogenic mechanisms of specific oral bacteria in the development of IBD. Ectopic colonization of several oral bacteria, including a subset of Porphyromonas gingivalis, Streptococcus mutans, Fusobacterium nucleatum, Campylobacter concisus, and Klebsiella pneumoniae, may lead to destruction of the intestinal epithelial barrier, excessive secretion of inflammatory cytokines, disruption of the host immune system, and dysbiosis of gut microbiota, consequently aggravating chronic intestinal inflammation. Studying oral microbiota dysbiosis may open future horizons for understanding IBD pathogenesis and provide novel biomarkers for IBD. This review also presents the current treatment and new perspectives for IBD treatment.

Qi Y ，Wu HM ，Yang Z ，Zhou YF ，Jin L ，Yang MF ，Wang FY ... -  《-》

Site- and Taxa-Specific Disease-Associated Oral Microbial Structures Distinguish Inflammatory Bowel Diseases.

The gut and oral microbiome have independently been shown to be associated with inflammatory bowel disease (IBD). However, it is not known to what extent gut and oral microbial disease markers converge in terms of their composition in IBD. Further, the spatial and temporal variation within the oral microenvironments of IBD remain to be elucidated. We used a prospectively recruited cohort of patients with IBD (n = 47) and unrelated healthy control patients (n = 18) to examine the spatial and temporal distribution of microbiota within the various oral microenvironments, represented by saliva, tongue, buccal mucosa, and plaque, and compared them with stool. Microbiome characterization was performed using 16S rRNA gene sequencing. The oral microbiome displayed IBD-associated dysbiosis, in a site- and taxa-specific manner. Plaque samples depicted a relatively severe degree of dysbiosis, and the disease-associated dysbiotic bacterial groups were predominantly the members of the phylum Firmicutes. Our 16S rRNA gene analyses show that oral microbiota can distinguish patients with IBD from healthy control patients, with salivary microbiota performing the best, closely matched by stool and other oral sites. Longitudinal profiles of microbial composition suggest that some taxa are more consistently perturbed than others, preferentially in a site-dependent fashion. Collectively, these data indicate the potential of using oral microbial profiles in screening and monitoring patients with IBD. Furthermore, these results support the importance of spatial and longitudinal microbiome sampling to interpret disease-associated dysbiotic states and eventually to gain insights into disease pathogenesis.

Somineni HK ，Weitzner JH ，Venkateswaran S ，Dodd A ，Prince J ，Karikaran A ，Sauer CG ，Abramowicz S ，Zwick ME ，Cutler DJ ，Okou DT ，Chopra P ，Kugathasan S ... -  《-》