Murine Salivary Amylase Protects Against Streptococcus mutans -Induced Caries

• Published in: Frontiers in physiology Vol. 12; p. 699104
• Main Authors: Culp, David J, Robinson, Bently, Cash, Melanie N
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 02-07-2021
• Subjects: aggregation; animal model; infectious disease; innate immunity; microbiome; Physiology; Streptococcus; aggregation; Streptococcus; innate immunity; animal model; infectious disease; microbiome
• ISSN: 1664-042X; 1664-042X
• DOI: 10.3389/fphys.2021.699104

Saliva protects dental surfaces against cavities (i. e., dental caries), a highly prevalent infectious disease frequently associated with acidogenic
. Substantial
evidence supports amylase, a major constituent of saliva, as either protective against caries or supporting caries. We therefore produced mice with targeted deletion of salivary amylase (Amy1) and determined the impact on caries in mice challenged with
and fed a diet rich in sucrose to promote caries. Total smooth surface and sulcal caries were 2.35-fold and 1.79-fold greater in knockout mice, respectively, plus caries severities were twofold or greater on sulcal and smooth surfaces. In
experiments with samples of whole stimulated saliva, amylase expression did not affect the adherence of
to saliva-coated hydroxyapatite and slightly increased its aggregation in solution (i.e., oral clearance). Conversely,
in biofilms formed in saliva with 1% glucose displayed no differences when cultured on polystyrene, but on hydroxyapatite was 40% less with amylase expression, suggesting that recognition by
of amylase bound to hydroxyapatite suppresses growth. However, this effect was overshadowed
, as the recoveries of
from dental plaque were similar between both groups of mice, suggesting that amylase expression helps decrease plaque acids from
that dissolve dental enamel. With amylase deletion, commensal streptococcal species increased from ~75 to 90% of the total oral microbiota, suggesting that amylase may promote higher plaque pH by supporting colonization by base-producing oral commensals. Importantly, collective results indicate that amylase may serve as a biomarker of caries risk.