On the ecosystemic network of saliva in healthy young adults.

A dysbiotic state is believed to be a key factor in the onset of oral disease. Although oral diseases have been studied for decades, our understanding of oral health, the boundaries of a healthy oral ecosystem and ecological shift toward dysbiosis is still limited. Here, we present the ecobiological heterogeneity of the salivary ecosystem and relations between the salivary microbiome, salivary metabolome and host-related biochemical salivary parameters in 268 healthy adults after overnight fasting. Gender-specific differences in the microbiome and metabolome were observed and were associated with salivary pH and dietary protein intake. Our analysis grouped the individuals into five microbiome and four metabolome-based clusters that significantly related to biochemical parameters of saliva. Low salivary pH and high lysozyme activity were associated with high proportions of streptococcal phylotypes and increased membrane-lipid degradation products. Samples with high salivary pH displayed increased chitinase activity, higher abundance of Veillonella and Prevotella species and higher levels of amino acid fermentation products, suggesting proteolytic adaptation. An over-specialization toward either a proteolytic or a saccharolytic ecotype may indicate a shift toward a dysbiotic state. Their prognostic value and the degree to which these ecotypes are related to increased disease risk remains to be determined.

Salivary agglutinin is the major component in human saliva that modulates the lectin pathway of the complement system.

Saliva interacts with blood after mucosal damage or leakage of gingival crevicular fluid. Surface-adsorbed salivary agglutinin (SAG) activates the lectin pathway (LP) of the complement system via mannose-binding lectin, while SAG in solution inhibits complement activation. In the present study we investigated if, next to SAG, whole and glandular saliva itself and other salivary glycoproteins activate or inhibit the LP. Complement activation was measured by detecting C4 deposition on microtiter plates coated with saliva or purified proteins. Complement inhibition was measured after incubating serum with saliva or proteins in microtiter plates coated with mannan, an LP activator. Adsorbed whole, sublingual and submandibular saliva showed LP-dependent complement activation. Blood group secretors, but not non-secretors, activated the LP. Saliva of both secretors and non-secretors inhibited C4 deposition on mannan. After depletion of SAG, saliva no longer inhibited the LP. Other salivary proteins, including amylase, MUC5B and histatin 2, did not activate or inhibit the LP. Surface-adsorbed whole saliva and glandular saliva samples activate the LP of complement, depending on the presence of SAG and the secretor status of the donor. In solution, saliva inhibits the LP, depending on the presence of SAG, but independent of the secretor status.

Thickened saliva after effective management of drooling with botulinum toxin A.

AIM: The aim of this study was to evaluate the rheological properties of saliva after submandibular botulinum toxin type A (BoNT-A) injections. METHOD: We enrolled 15 children (11 males and six females; age range 3-17 y, mean age 9 y 10 mo) diagnosed with spastic (n=9) or dyskinetic (n=6) quadriplegic cerebral palsy (CP); Gross Motor Function Classification System level IV or V; and two children with intellectual disability (IQ<70) who experienced moderate to severe drooling. Salivary flow rate and drooling quotient were measured at baseline and at different times after BoNT-A injections up to 24 weeks. The mucin concentration of saliva was analysed before and after BoNT-A treatment. RESULTS: Both submandibular salivary flow rate (baseline 0.38 mL/min; 24 wks after injection 0.26 mL/min) and drooling quotient (baseline 42.5%; 24 wks 28.80%) were substantially reduced, with a concomitant increase in mucin concentration within 8 weeks after BoNT-A injection (from 0.612 to 1.830 U/mL). The parents of nine children observed thickened saliva. Swallowing and chewing were problematic in seven children. Two of these children needed treatment with mucolytics because of pooling of thickened saliva in the throat. INTERPRETATION: When making decisions about the use of BoNT-A, the risk of problems with masticatory and swallowing functions as a result of thickening of saliva after BoNT-A treatment should be taken into account.