beta 2-Microglobulin in saliva and its relation to flow rate in different glands in man

The Effect of Oral Probiotics (Streptococcus Salivarius k12) on the Salivary Level of Secretory Immunoglobulin A, Salivation Rate, and Oral Biofilm: A Pilot Randomized Clinical Trial

We aimed to assess the effect of oral probiotics containing the Streptococcus salivarius K12 strain on the salivary level of secretory immunoglobulin A, salivation rate, and oral biofilm. Thirty-one consenting patients meeting the inclusion criteria were recruited in this double-blind, placebo-controlled, two-arm, parallel-group study and randomly divided into probiotic (n = 15) and placebo (n = 16) groups. Unstimulated salivation rate, concentration of salivary secretory immunoglobulin A, Turesky index, and Papillary-Marginal-Attached index were assessed after 4 weeks of intervention and 2 weeks of washout. Thirty patients completed the entire study protocol. We found no increase in salivary secretory immunoglobulin A levels and salivary flow rates in the probiotic group compared with placebo. Baseline and outcome salivary secretory immunoglobulin A concentrations (mg/L) were 226 ± 130 and 200 ± 113 for the probiotic group and 205 ± 92 and 191 ± 97 for the placebo group, respectively. A significant decrease in plaque accumulation was observed in the probiotic group at 4 and 6 weeks. Within the limitations of the present study, it may be concluded that probiotic intake (Streptococcus salivarius K12) does not affect salivation rates and secretory immunoglobulin A salivary levels but exhibits a positive effect on plaque accumulation. Trial registration NCT05039320. Funding: none.

The host defense peptide LL-37 is detected in human parotid and submandibular/sublingual saliva and expressed in glandular neutrophils

The human host defense peptide, LL-37, is an important player in the first line of defense against invading microorganisms. LL-37 and its precursor, hCAP18, have been detected in unstimulated whole saliva but no reports showing hCAP18/LL-37 in isolated, parotid, and/or submandibular/sublingual saliva have been presented. Here, we measured the levels of hCAP18/LL-37 in human parotid and submandibular/sublingual saliva and investigated the expression of hCAP18/LL-37 in parotid and submandibular gland tissue. Parotid and submandibular/sublingual saliva was collected from healthy volunteers, and the levels of hCAP18/LL-37 in saliva were analyzed by dot blot, ELISA, and western blotting. Cellular expression of hCAP18/LL-37 in human parotid and submandibular glands was investigated by immunohistochemistry. Immunoreactivity for hCAP18/LL-37 was detected in both parotid and submandibular/sublingual saliva of all individuals. The concentration of hCAP18/LL-37 was similar in parotid and submandibular/sublingual saliva, and was determined by densitometric scanning of each dot and normalization to the total protein concentration of each sample, and by ELISA. Double immunohistochemistry revealed that intravascular neutrophils of both parotid and submandibular glands express hCAP18/LL-37. For the first time, we demonstrate hCAP18/LL-37 in isolated human parotid and submandibular/sublingual saliva and expression of hCAP18/LL-37 in glandular intravascular neutrophils, indicating that neutrophils of the major salivary glands contribute to the LL-37 content of whole saliva.

Presence of Lactobacillus reuteri in saliva coincide with higher salivary IgA in young adults after intake of probiotic lozenges

The aim of this study was to compare the concentration of salivary immunoglobulin A (IgA) and the selected interleukins (IL)-1β, IL-6, IL-8 and IL-10 in young individuals with presence and non-presence of Lactobacillus reuteri in saliva after a three-week intervention with probiotic lozenges. The study group consisted of 47 healthy individuals aged 18-32 years with no clinical signs of oral inflammation. In a randomised, double-blind, placebo-controlled, cross-over trial participants ingested two lozenges per day containing two strains of the probiotic bacterium L. reuteri or placebo lozenges. The intervention and wash-out periods were three weeks. Stimulated and unstimulated whole saliva was collected at baseline and immediately after termination of the intervention periods. The samples were analysed for total protein, salivary IgA and selected cytokines. In this extended analysis, data were collected by analysing baseline and follow-up saliva samples related to ingestion of the probiotic lozenges for the presence of L. reuteri through DNA-extraction, PCR-amplification and gel-electrophoresis. At baseline, 27% of the individuals displayed presence of L. reuteri and 42% were positive immediately after the three-week probiotic intervention. Individuals with presence of L. reuteri in saliva had significantly higher (P<0.05) concentrations of salivary IgA and %IgA/protein at the termination of the probiotic intake compared with non-presence. No differences in the cytokine levels were observed. In conclusion, detectable levels of L. reuteri in saliva coincided with higher concentrations of salivary IgA and %IgA/protein in stimulated whole saliva after the three-week daily intake of probiotic lozenges. Our findings suggest that monitoring the presence of probiotic candidates in the oral environment is important to interpret and understand their possible immune-modulating role in maintaining oral health.

Salivary IgA response to probiotic bacteria and mutans streptococci after the use of chewing gum containing Lactobacillus reuteri

We investigated whether ingestion of probiotic bacteria could influence salivary IgA levels, specific anti-mutans streptococci IgA levels and specific antibodies towards the ingested probiotic bacterium. The study was a randomised, double-blind, placebo-controlled trial, where the test group (n = 11) received twice daily chewing of gum containing Lactobacillus reuteri (2 × 10(8)  CFU per dose) and the control group (n = 12) received placebo. Resting saliva was collected before and after 12 weeks of treatment and 4 weeks after end of treatment. Total salivary IgA concentrations were measured by ELISA. Specific IgA reactivity was determined using a whole-cell ELISA. Results were expressed as % IgA per protein in saliva. The level of total IgA% per protein increased significantly between pretreatment levels (13.5%) and follow-up treatment levels (14.4%) within the test group only (P < 0.05). No changes were seen in the control group during the trial. The level of probiotic-reactive antibodies decreased significantly between pre- and post-treatment samples (from 12.2% to 9.0%, P < 0.05) in the test group. Similarly, the level of specific mutans streptococci antibodies decreased significantly between pre- and post-treatment samples (P < 0.05) in the test group only (for Streptococcus mutans from 20.1% to 15.0%; for Streptococcus sobrinus from 7.4% to 5.3%). Ingestion of probiotic bacteria might influence the adaptive immune response of the host.

Saliva-bacterium interactions in oral microbial ecology

Saliva is thought to have a significant impact on the colonization of microorganisms in the oral cavity. Salivary components may participate in this process by one of four general mechanisms: binding to microorganisms to facilitate their clearance from the oral cavity, serving as receptors in oral pellicles for microbial adhesion to host surfaces, inhibiting microbial growth or mediating microbial killing, and serving as microbial nutritional substrates. This article reviews information pertinent to the molecular interaction of salivary components with bacteria (primarily the oral streptococci and Actinomyces) and explores the implications of these interactions for oral bacterial colonization and dental plaque formation. Knowledge of the molecular mechanisms controlling bacterial colonization of the oral cavity may suggest methods to prevent not only dental plaque formation but also serious medical infections that may follow microbial colonization of the oral cavity.

Salivary IgA, lysozyme and beta 2-microglobulin in periodontal disease

The concentrations of IgA, lysozyme and beta 2-microglobulin (beta 2-m) were quantitated in wax-stimulated mixed saliva from 28 patients with severe periodontitis and from 28 healthy controls. The mutual correlations between IgA, lysozyme and beta 2-m were determined. In patients with periodontitis decreased lysozyme concentrations were detected when compared with controls (P less than 0.05). The correlation between IgA and beta 2-m concentrations was highly significant in both groups studied (P less than 0.0001, and P less than 0.002), whereas beta 2-m and lysozyme concentrations were positively correlated in patients but not in controls. In addition, a significant correlation between IgA and lysozyme was found only in periodontal patients (P less than 0.001).

Correlations between human salivary levels of lysozyme, lactoferrin, salivary peroxidase and secretory immunoglobulin A with different stimulatory states and over time

Within-subject correlations for the levels of these salivary proteins were determined in unstimulated and stimulated parotid saliva collected from 8 subjects and for stimulated parotid saliva collected from the same subjects once a week for a 4-week period. Initial correlations between unstimulated and stimulated samples were high and statistically significant (p less than 0.05) for all four proteins. When data were adjusted for variation attributable to flow rate and total protein, some correlations remained the same and those for lysozyme, lactoferrin and salivary peroxidase increased. However, the correlation for secretory immunoglobulin A decreased to a point where it was no longer statistically significant. In the weekly comparison, within-subject correlations across weeks were significant (p less than or equal to 0.05) for lysozyme, lactoferrin and salivary peroxidase, but not for immunoglobulin A. After adjustment for flow rate and total protein, the pattern of correlation was unchanged. Thus the relative rankings of subjects for levels of lysozyme, lactoferrin or salivary peroxidase may be consistent across stimulatory states, even though absolute concentrations may change; levels of these proteins in stimulated parotid saliva may be maintained over time. Secretory immunoglobulin A appears to be more subject to short-term variation.

Agglutination of Streptococcus mutans by low-molecular-weight salivary components: effect of beta 2-microglobulin

Radiolabeled monomeric human beta 2-microglobulin (beta 2m) was tested for binding to Streptococcus mutans strains in buffers containing 1 mM calcium (Ca2+). Binding was seen to strains with a previously established binding capacity of aggregated beta 2m. Monomeric beta 2m agglutinated beta 2m-binding strains when Ca2+ was present. At Ca2+ concentrations of 1.4 mM, 0.032 micrograms of monomeric beta 2m per ml caused bacterial agglutination. Parotid saliva was gel filtered on a Sephadex G-75 column, and low-molecular-weight fractions containing beta 2m could agglutinate S. mutans cells. Five of six strains that could bind beta 2m were agglutinated by these fractions, but only one of five nonbinding strains was. All strains tested were agglutinated by void volume fractions. A new method for the measurement of turbidity in bacterial agglutination inhibition experiments with parotid saliva was used. Suspensions containing parotid saliva, bacteria, and control serum were directly compared in a spectrophotometer with test suspensions containing goat anti-human beta 2m, bacteria, and saliva. Thus, the spectrophotometer directly read the difference in agglutination of the two suspensions, and the result was presented as one curve by the recorder. Agglutination of five beta 2m-binding strains of S. mutans was inhibited or decreased by the addition of goat anti-human beta 2m as compared with control serum. The agglutination of two beta 2m-nonbinding strains and one with variable binding was not inhibited. Thus, salivary beta 2m may contribute to agglutination of S. mutans cells in parotid saliva.

Actinomyces viscosus and Actinomyces naeslundii agglutinins in human saliva

The objectives were to determine the degree of Actinomyces agglutinating activity in human saliva and to begin characterizing the agglutination mechanism. Agglutination titres of whole saliva collected from adults and 6-yr-old children were compared. Titres for A. naeslundii were always higher than for A. viscosus. The mean A. naeslundii titre for the adults' and children's samples were equivalent. The children had a slightly lower mean titre than the adults for A. viscosus. No correlation was found between IgA concentrations and agglutination titre. Agglutinating activity was partially impaired by incubation with anti-IgA serum. Activity in submandibular/sublingual saliva was resistant to heat at 56 degrees C but sensitive to boiling. Boiling the bacteria had no effect. In sugar inhibition tests, only galactosides (beta-Gal) and glucosamine (for A. viscosus) affected Actinomyces agglutination but impairment was only temporary. Agglutinating activity was diminished by incubating saliva with hydroxyapatite. Thus, Actinomyces agglutinins 1) are probably distinct from IgA but may complex with it; 2) may include both beta-Gal and higher affinity sites; and 3) may contribute to salivary pellicle.