The Link between Oral and Gut Microbiota in Inflammatory Bowel Disease and a Synopsis of Potential Salivary Biomarkers

Abstract

The objective of this review is to provide recent evidence for the oral–gut axis connection and to discuss gastrointestinal (GI) immune response, inflammatory bowel disease (IBD) pathogenesis, and potential salivary biomarkers for determining GI health. IBD affects an estimated 1.3% of the US adult population. While genetic predisposition and environment play a role, abnormal immune activity and microbiota dysbiosis within the gastrointestinal tract are also linked in IBD pathogenesis. It has been inferred that a reduced overall richness of bacterial species as well as colonization of opportunistic bacteria induce systemic inflammation in the GI tract. Currently, there is supporting evidence that both oral and gut microbiota may be related to the development of IBD. Despite this, there are currently no curative therapies for IBD, and diagnosis requires samples of blood, stool, and invasive diagnostic imaging techniques. Considering the relative ease of collection, emerging evidence of association with non-oral diseases may imply that saliva microbiome research may have the potential for gut diagnostic or prognostic value. This review demonstrates a link between saliva and intestinal profiles in IBD patients, suggesting that saliva sampling has the potential to serve as a non-invasive biomarker for gut diseases such as IBD in the oral–gut axis.

The Clinical, Microbiological, and Immunological Effects of Probiotic Supplementation on Prevention and Treatment of Periodontal Diseases: A Systematic Review and Meta-Analysis

“…S. Bouldarii is a yeast probiotic that is non-colonizing [ 117 ], which likely caused nonsignificant changes in plaque accumulation [ 58 ]. However, the improvements in other clinical parameters (PPD and CAL) may be due to its role in immunomodulation [ 118 ].…”

Correlation between faecal microbial taxa and ulcerative colitis in different phases of disease activity in a north Indian cohort

“…However, in our case none of the UC patients were using PPIs suggesting other factors responsible for Streptococcus abundance. Interestingly, evidences are now emerging and pointing to association between higher levels of gut inflammation in IBD patients and increase in bacteria typical of the oral cavity 28 . Although oral microbes are innately resistant to colonization in healthy guts, it has been proposed that inflammation or strain-specific adaptation (including antibiotic resistance and virulence genes) of oral microbes allows their colonization in the gut resulting in exaggerated inflammatory response 31 .…”

Oral Mucosa as a Potential Site for Diagnosis and Treatment of Allergic and Autoimmune Diseases

“…Bidirectional causality between IBD and oral lesions has also been speculated, specially involving microbiota [ 126 , 127 ]. Dysbiosis in the oral mucosa microbiota has been described in patients with IBD [ 128 , 129 ], while pathogenesis in the oral cavity cause shifts in both oral and intestinal microbiota [ 126 , 130 ]. In this regard, oral microbes may migrate to the gut and exacerbate various gastrointestinal diseases [ 130 ].…”