Oral bacterial diversity is inversely correlated with mucosal inflammation.

Karolin Hijazi,Sophie Shaw,Indrani Mukhopadhya,Francesco Santoro,Matthew Gemmell,Roderick W Morrison,Brennan Martin

doi:10.1111/odi.13420

Karolin Hijazi, Sophie Shaw + Show 5 more

Open Access

https://doi.org/10.1111/odi.13420

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Abstract

We investigated the relationship amongst the oral mucosal bacterial community, clinical severity and inflammatory markers in the two most common immune-mediated oral mucosal diseases, namely recurrent aphthous stomatitis (RAS) and oral lichen planus (LP). Patients with RAS (n=15) and LP (n=18) and healthy controls (n=13) were recruited using criteria to reduce the effect of factors that influence the microbiota structure independently of oral mucosal disease. Clinical severity was quantified using validated scoring methods. DNA was extracted from oral mucosal swabs for 16S rRNA gene high-throughput sequencing. Salivary cytokines were measured using cytometric bead assays. Correlation studies were conducted amongst microbial diversity, clinical scores and cytokine concentrations. We observed a significant reduction of bacterial diversity in LP and RAS patients compared to controls (p=.021 and .044, respectively). Reduced bacterial diversity in LP and RAS correlated with increased clinical scores of the two conditions (⍴=-0.551 to -0.714). A negative correlation was observed between microbial diversity and salivary interferon-γ, interleukin-17A and interleukin-1β (⍴=-0.325 to -0.449). This study reports reduced oral microbial diversity in the context of increased mucosal inflammation and supports the role for microbial diversity as a marker or contributor to oral mucosal inflammatory disease activity and development.

Highlights

Imbalances of the oral microbiota, commonly referred to as microbial dysbiosis, have been associated with a wide range of oral diseases (Kilian et al, 2016)
We investigated the correlation of oral bacterial diversity and salivary levels of Th1, Th2 and Th17 inflammatory cytokines implicated in lichen planus (LP) and recurrent aphthous stomatitis (RAS)
There has been lack of consistency in the findings of microbiome studies of immune-mediated oral mucosal disease published to date (He et al, 2017; Hijazi et al, 2015; Kim et al, 2016; Seoudi et al, 2015; Wang et al, 2016), and a microbial signature for LP and RAS patients has not been confirmed

Summary

| INTRODUCTION

Imbalances of the oral microbiota, commonly referred to as microbial dysbiosis, have been associated with a wide range of oral diseases (Kilian et al, 2016). A number of studies have reported enrichment or depletion of specific bacterial genera and species in oral samples from patients suffering from immune-mediated oral mucosal diseases, such as recurrent aphthous stomatitis (RAS) (Bankvall et al, 2014; Hijazi et al, 2015; Kim et al, 2016; Marchini, Campos, Silva, Paulino, & Nobrega, 2007; Seoudi, Bergmeier, Drobniewski, Paster, & Fortune, 2015) and oral lichen planus (LP) (Choi et al, 2016; KazanowskaDygdała et al, 2016; Pankhurst, Auger, & Hardie, 1988; Wang et al, 2016), for which historically the role of bacteria has been debated but never confirmed Oral mucosal diseases, such as RAS and LP, have a proven negative impact on patient quality of life (Hegarty, McGrath, Hodgson, & Porter, 2002; Liu, Xiao, He, & Jiang, 2012), but with little knowledge of the events at the mucosal interface that initiate and sustain inflammation, the treatment of these conditions remains untargeted and often ineffective (Belenguer-Guallar, Jimenez-Soriano, & Claramunt-Lozano, 2014). We investigated the correlation of oral bacterial diversity and salivary levels of Th1, Th2 and Th17 inflammatory cytokines implicated in LP and RAS

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| Statistical methods

Findings

| DISCUSSION