IADR Abstract Archives
Lactobacillus rhamnosus Capsular Polysaccharide Modulates Neural Responses in Caries
Objectives: The aim of the study was to investigate the impact of capsular polysaccharide (CPS) from a clinical isolate of Lactobacillus rhamnosus on neurogenic precursors.
Methods: L. rhamnosus LRHMDP2 was isolated from the initial stage of dental pulp infection of a carious tooth. CPS of L. rhamnosus LRHMDP2 was extracted by autoclaving. As a proxy for neural precursors of dental pulp human neural pericytes (HNPs) were grown in two different media: pericyte medium (PM) or neuro-glial medium comprising DMEM with N2 supplement. Cultures were challenged with CPS or PBS as controls and evaluated at 6 and 24 h time periods using immunohistochemistry for Notch1 intracellular domain (ICD-an indicator of Notch activation), Notch1 extracellular domain (ECD), and S100+ markers.
Results: Following a 6 h incubation, no differences of Notch expression between CPS-treated and control pericytes were noted. After 24 h incubation, Notch1 ICD expression was selectively down-regulated by CPS in cultures in PM despite up-regulation of Notch1 ECD. This result suggested that CPS inhibited proteolytic cleavage of the Notch1 ECD and subsequent activation of Notch signaling by the Notch1 ICD. Possibly, CPS could act as an analogue of the oligosaccharides of glycosylated Notch1 thereby blocking recognition sites for Notch ligands. Notch1 signaling was also suppressed in neuro-glial differentiation medium but with corresponding up-regulation of S100+ glial cell marker.
Conclusions: These findings provide novel evidence regarding the virulence potential of L. rhamnosus LRHMDP2 CPS to down-regulate Notch signaling and subsequently drive neural precursors into a glial fate. Disruption of the homeostatic balance regulating differentiation of neural precursors could perturb formation of protective tertiary dentine and open a pathway to infection of the pulp.
Methods: L. rhamnosus LRHMDP2 was isolated from the initial stage of dental pulp infection of a carious tooth. CPS of L. rhamnosus LRHMDP2 was extracted by autoclaving. As a proxy for neural precursors of dental pulp human neural pericytes (HNPs) were grown in two different media: pericyte medium (PM) or neuro-glial medium comprising DMEM with N2 supplement. Cultures were challenged with CPS or PBS as controls and evaluated at 6 and 24 h time periods using immunohistochemistry for Notch1 intracellular domain (ICD-an indicator of Notch activation), Notch1 extracellular domain (ECD), and S100+ markers.
Results: Following a 6 h incubation, no differences of Notch expression between CPS-treated and control pericytes were noted. After 24 h incubation, Notch1 ICD expression was selectively down-regulated by CPS in cultures in PM despite up-regulation of Notch1 ECD. This result suggested that CPS inhibited proteolytic cleavage of the Notch1 ECD and subsequent activation of Notch signaling by the Notch1 ICD. Possibly, CPS could act as an analogue of the oligosaccharides of glycosylated Notch1 thereby blocking recognition sites for Notch ligands. Notch1 signaling was also suppressed in neuro-glial differentiation medium but with corresponding up-regulation of S100+ glial cell marker.
Conclusions: These findings provide novel evidence regarding the virulence potential of L. rhamnosus LRHMDP2 CPS to down-regulate Notch signaling and subsequently drive neural precursors into a glial fate. Disruption of the homeostatic balance regulating differentiation of neural precursors could perturb formation of protective tertiary dentine and open a pathway to infection of the pulp.