Dysbiosis by neutralizing commensal mediated inhibition of pathobionts

Abstract

Dysbiosis in the periodontal microbiota is associated with the development of periodontal diseases. Little is known about the initiation of dysbiosis. It was hypothesized that some commensal bacteria suppress the outgrowth of pathobionts by H2O2 production. However, serum and blood components released due to inflammation can neutralize this suppressive effect, leading to the initiation of dysbiosis. Agar plate, dual-species and multi-species ecology experiments showed that H2O2 production by commensal bacteria decreases pathobiont growth and colonization. Peroxidase and blood components neutralize this inhibitory effect primarily by an exogenous peroxidase activity without stimulating growth and biofilm formation of pathobionts directly. In multi-species environments, neutralization of H2O2 resulted in 2 to 3 log increases in pathobionts, a hallmark for dysbiosis. Our data show that in oral biofilms, commensal species suppress the amounts of pathobionts by H2O2 production. Inflammation can neutralize this effect and thereby initiates dysbiosis by allowing the outgrowth of pathobionts.

Nutritional stimulation of commensal oral bacteria suppresses pathogens: the prebiotic concept

“…Recently, it was shown that serum and blood components influence the microbiological balance by neutralizing the suppressive effect of commensal bacteria on pathogens, and thus might initiate a dysbiotic microbial biofilm composition (Herrero et al. ). Therefore, ensuring and restoring the health‐associated homeostasis of the resident oral microbiota as well as modulating the host immune response at diseased sites is a potential avenue for therapeutic intervention to promote oral health (Socransky & Haffajee , Marsh , ).…”

Clinical concentrations of peroxidases cause dysbiosis in in vitro oral biofilms

“…In brief, 7 μL of an overnight culture of a commensal species was spotted onto an agar plate and incubated for 24 hours in aerobic conditions, as described by Herrero et al . Afterwards, 7 μL of the peroxidase solution was spotted next to spots of the commensal species and left to dry for 5 minutes at 37°C under aerobic conditions.…”

“…After 48 hours of anaerobic incubation, a calibrated photograph was taken of the agar plate. The magnitude of inhibition was measured from the edge of the commensal colony to the border of the inhibited pathogen colony using ImageJ (http://rsb.info.nih.gov/ij/download.html) (Figure ) …”

“…In summary, it has been shown that commensal bacteria can suppress the overgrowth of pathobionts by producing H 2 O 2 . High concentrations of catalytic molecules, such as horseradish peroxidase, remove H 2 O 2 and cause dysbiosis . Current evidence indicates that the concentrations of myeloperoxidase in the gingival sulcus in health, gingivitis, and periodontitis are related to periodontal disease severity …”

“…Pathobionts appear to dysregulate the host inflammatory response, which can lead to chronic inflammation . Recently, it was shown that certain species of commensal bacteria suppress the outgrowth of periodontal pathobionts by producing hydrogen peroxide (H 2 O 2 ) . However, human serum, horseradish peroxidase, and blood components can neutralize this suppressive effect, leading to dysbiosis .…”