The oral mucosal and salivary microbial community of Behçet's syndrome and recurrent aphthous stomatitis

Abstract

Background: Behçet's syndrome (BS) is a multisystem immune-related disease of unknown etiology. Recurrent aphthous stomatitis (RAS) is characterized by the presence of idiopathic oral ulceration without extraoral manifestation. The interplay between the oral microbial communities and the immune response could play an important role in the etiology and pathogenesis of both BS and RAS.

Objective: To investigate the salivary and oral mucosal microbial communities in BS and RAS.

Methods: Purified microbial DNA isolated from saliva samples (54 BS, 25 healthy controls [HC], and 8 RAS) were examined by the human oral microbe identification microarray. Cultivable salivary and oral mucosal microbial communities from ulcer and non-ulcer sites were identified by matrix-assisted laser desorption/ionization time-of-flight analysis. Mycobacterium spp. were detected in saliva and in ulcer and non-ulcer oral mucosal brush biopsies following culture on Lowenstein-Jensen slopes and Mycobacterial Growth Indicator Tubes.

Results: There was increased colonization with Rothia denticariosa of the non-ulcer sites of BS and RAS patients (p<0.05). Ulcer sites in BS were highly colonized with Streptococcus salivarius compared to those of RAS (p<0.05), and with Streptococcus sanguinis compared to HC (p<0.0001). Oral mucosa of HC were more highly colonized with Neisseria and Veillonella compared to all studied groups (p<0.0001).

Conclusions: Despite the uncertainty whether the reported differences in the oral mucosal microbial community of BS and RAS are of causative or reactive nature, it is envisaged that restoring the balance of the oral microbial community of the ulcer sites may be used in the future as a new treatment modality for oral ulceration.

Keywords: Behçet's syndrome; microbiota; oral mucosa; recurrent aphthous stomatitis; saliva.

Fig. 1

Oral health status of participants with Behçet's syndrome (BS) in comparison to those with recurrent aphthous stomatitis (RAS) and healthy controls (HC). There is a statistically significant difference between BS and HC in all the investigated indices except the plaque index.

Fig. 2

Salivary microbial community analysis by human oral microbe identification microarray. (a) The average number of hits per sample for the salivary microbial community. There is no statistically significant difference in the number of hits per sample among all the investigated groups. (b) Multivariate analysis of variance showed imbalance in the salivary microbial community of orally active BS in comparison to HC.

Fig. 3

The oral mucosal and salivary microbial load of orally active BS, orally inactive BS, RAS, and healthy controls (HC). (a) There is no statistically significant difference in the oral mucosal microbial load between the four investigated groups (p=0.2283). (b) There is no statistically significant difference in the oral mucosal load colonizing both ulcerated and non-ulcerated oral mucosa of orally active BS (p=0.4595). (c) There is a statistically significant decrease in the salivary microbial load of the orally inactive BS in comparison to HC (p=0.0185).

Fig. 4

Rothia in ulcer sites of orally active BS. The proportion of Rothia denticariosa in relation to the other species of Rothia was less than that seen in the non-ulcerated sites. Data presented as percentage.