The effect of milk and casein proteins on the adherence of Streptococcus mutans to saliva-coated hydroxyapatite

The Role of Breastfeeding in Acute Respiratory Infections in Infancy

BACKGROUND

Acute respiratory infections (ARIs) affect the respiratory tract, are often caused by viruses such as respiratory syncytial virus and rhinovirus, and present symptoms such as coughing, fever, respiratory distress and breathing difficulty. The global adherence to exclusive breastfeeding (BF) for the first 6 months of life has reached 44%, supported by World Health Organization and United Nations International Children's Emergency Fund efforts. BF provides vital nutrients and contributes to infant immune system development, protecting against infections. The role of BF in preventing and reducing complications of ARIs in infants is gaining attention, prompting a review of current data and future research needs. This review aims to summarize the evidence on the role of BF in reducing the risk and severity of ARIs in infants, elucidate the adaptations in breast milk composition during infections and identify relevant research needs.

METHODS AND RESULTS

Human milk (HM) is rich in immunoglobulins, antimicrobial peptides, and immunomodulatory factors that protect against various pathogens, including respiratory viruses. Several studies have demonstrated that BF is associated with a significant reduction in hospitalization, oxygen requirements, and mortality in infants with ARIs. The effectiveness of BF varies according to the specific respiratory virus, and a longer duration of exclusive BF appears to enhance its protective effect. It is documented that the composition of HM adjusts dynamically in response to infections, fortifying the infant's immune defenses. Specific immunological components of HM, including leukocytes and immunoglobulins, increase in response to infection in the infant, contributing to the enhancement of the immune defense in infants. Immune-boosting microRNAs enhance immune transfer to the infants and promote early gut maturation, and the HM microbiome along with other factors modifies the the infant's gut microbiome and immune system.

CONCLUSIONS

BF defends infants from respiratory infections, and the investigation of the microRNAs in HM offers new insights into its antiviral properties. The promotion of BF, especially in vulnerable communities, is of paramount importance in alleviating the global burden of ARIs in infancy.

Online LC-ESI-MS/MS comparative analysis of N/O-glycopatterns in human colostrum from different ethnic groups in Northwest China

Human milk oligosaccharides, including free oligosaccharides and glycoconjugates, exert a key role in neonatal health and development. Changes in free oligosaccharides of milk from different ethnic groups have been documented. In this study, human milk was collected from Han, Hui, and Tibetan populations in northwest China, and differences in N/O-glycome among these three ethnic groups were systematically compared using online high-performance liquid chromatography-tandem mass spectrometry. Among the 63 detected N-glycans, 35 showed significant differences between the three ethnic groups (p < 0.05). Among the 70 detected O-glycans, four neutral O-glycans and six acidic O-glycans exhibited significant differences among the three ethnic groups (p < 0.05), with six acidic O-glycans reported for the first time. Overall, the extent of milk N/O-glycosylation was higher in the Han population than in the Hui or Tibetan groups. This trend was particularly pronounced for the main sialylated N/O-glycans. Except for sulfated O-glycans, which were higher in the milk from Tibetan mothers, the other types of N/O-glycans were present in similar proportions across all ethnic groups. Understanding the composition of N/O-glycans in human milk can help research on the structure-function relationship of glycans.

Potential Renal Acid Load, Salivary Buffer Capacity and Healthy Eating Index as Predictors of Children's Dental Caries: A Cross-Sectional Study

INTRODUCTION

Dental caries is one of the most common childhood diseases. This study purposed to investigate the prediction capability of potential renal acid load (PRAL), salivary buffer capacity (SBC), and Healthy Eating Index (HEI) on children's dental caries.

METHODS

The decay, missing, filing, and teeth for primary teeth (dmft)/Decay, Missing, Filling, and Teeth for permanent teeth (DMFT) indexes of the children aged 7-12 years who applied to our faculty were recorded. Approximately 1 mL of unstimulated saliva samples were collected, and SBC was evaluated. PRAL and HEI scores were calculated by entering the data in the form of a daily nutrition record of the children into the BeBiS software (Ebispro for Windows, Stuttgart, Germany). The association of dental caries indices with PRAL, SBC, and HEI was analyzed using an independent sample t-test. A binomial logistic regression analysis was performed to predict the dental caries burden. The statistical significance level was adjusted to a=0.05.

RESULTS

A total of 150 children, 88 (58.6%) females and 62 (41.4%) males, were included in the study. Significant differences were found between the low and high dental caries groups for dmft regarding PRAL and SBC (p<0.001). A significant difference was found between the low and high dental caries groups for DMFT in terms of SBC (p<0.05).

CONCLUSION

In our study, established regression models significantly predicted dental caries in primary teeth. SBC was the most influential factor in predicting dental caries compared to PRAL and HEI. There was a significant relationship between SBC, PRAL, and caries in primary teeth. In the model we created, the strongest predictor was SBC.

Prevention of Initial Bacterial Attachment by Osteopontin and Other Bioactive Milk Proteins

A considerable body of work has studied the involvement of osteopontin (OPN) in human physiology and pathology, but comparably little is known about the interaction of OPN with prokaryotic cells. Recently, bovine milk OPN has been proposed as a therapeutic agent to prevent the build-up of dental biofilms, which are responsible for the development of caries lesions. Bioactive milk proteins are among the most exciting resources for caries control, as they hamper bacterial attachment to teeth without affecting microbial homeostasis in the mouth. The present work investigated the ability of OPN to prevent the adhesion of three dental biofilm-forming bacteria to saliva-coated surfaces under shear-controlled flow conditions in comparison with the major milk proteins α-lactalbumin, β-lactoglobulin, αs1-casein, β-casein and κ-casein, as well as crude milk protein. OPN was the most effective single protein to reduce the adhesion of Actinomyces naeslundii, Lactobacillus paracasei subsp. paracasei and Streptococcus mitis. β-casein and crude milk protein also had a pronounced effect on all three species, which suggests binding to different microbial surface structures rather than the blocking of a specific bacterial adhesin. Bioactive milk proteins show potential to delay harmful biofilm formation on teeth and hence the onset of biofilm-related oral disease.

Effect of Beverage Consumption Frequency on DMFT Index among Iranian Adult Population: An AZAR Cohort Study

Background

Given the effect of oral and dental condition on emotional and physical health and the different effects of beverage consumption on decayed, missing, and filled teeth (DMFT) as one of the indicators of oral health in different populations, this study aimed to investigate the effect of beverage consumption and its frequency on DMFT among Iranian adult population.

Materials and Methods

The data of this cross-sectional study were obtained from AZAR (Azerbaijan) cohort, conducted on 15,006 adults aged 35 to 70 years old in Shabestar County, Iran. Demographic and nutritional data were collected by nutritionists through the "Food Frequency Questionnaire," and DMFT index by general practitioners trained by a dentist according to the World Health Organization (WHO) guidelines. Beverages including milk, doogh, natural fruit juice, black tea, nonalcoholic beer, coffee, sugar-sweetened beverages, and artificial fruit juice were studied.

Results

A total of 14,966 adults with the mean age of 49.64 ± 9.28 were enrolled. The participants' mean DMFT value was 21.27 ± 8.95. Weekly consumption of tea and coffee beverages resulted in 13% (95% confidence interval: 3% to 22%) lower DMFT compared to daily consumption (p=0.01). However, there was no association between DMFT and other beverages.

Conclusion

The higher DMFT values with the daily consumption of tea and coffee beverages showed that a part of adults' oral health is affected by beverages; therefore, this should be considered by healthcare authorities in order to manage carries development in the communities.

A Healthier Smile in the Past? Dental Caries and Diet in Early Neolithic Farming Communities from Central Germany

Dental health is closely linked to an individual’s health and diet. This bioarcheological study presents dental caries and stable isotope data obtained from prehistoric individuals (n = 101) from three Early Neolithic sites (c. 5500-4800 BCE) in central Germany. Dental caries and ante-mortem tooth loss (AMTL) were recorded and related to life history traits such as biological sex and age at death. Further, we correlate evidence on caries to carbon and nitrogen isotope data obtained from 83 individuals to assess the relationship between diet and caries. In 68.3% of the adults, carious lesions were present, with 10.3% of teeth affected. If AMTL is considered, the values increase by about 3%. The prevalence of subadults (18.4%) was significantly lower, with 1.8% carious teeth. The number of carious teeth correlated significantly with age but not sex. The isotopic data indicated an omnivorous terrestrial diet composed of domestic plants and animal derived protein but did not correlate with the prevalence of carious lesions. The combined evidence from caries and isotope analysis suggests a prevalence of starchy foods such as cereals in the diet of these early farmers, which aligns well with observations from other Early Neolithic sites but contrasts to Late Neolithic and Early Bronze Age populations in Germany.

Murine Salivary Amylase Protects Against Streptococcus mutans-Induced Caries

Saliva protects dental surfaces against cavities (i. e., dental caries), a highly prevalent infectious disease frequently associated with acidogenic Streptococcus mutans. Substantial in vitro 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 S. mutans 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 in vitro experiments with samples of whole stimulated saliva, amylase expression did not affect the adherence of S. mutans to saliva-coated hydroxyapatite and slightly increased its aggregation in solution (i.e., oral clearance). Conversely, S. mutans 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 S. mutans of amylase bound to hydroxyapatite suppresses growth. However, this effect was overshadowed in vivo, as the recoveries of S. mutans from dental plaque were similar between both groups of mice, suggesting that amylase expression helps decrease plaque acids from S. mutans 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.

Current Perspective of Sialylated Milk Oligosaccharides in Mammalian Milk: Implications for Brain and Gut Health of Newborns

Human milk oligosaccharides (HMOs) are the third most abundant solid component after lactose and lipids of breast milk. All mammal milk contains soluble oligosaccharides, including neutral milk oligosaccharides (NMOs) without sialic acid (Sia) moieties and acidic oligosaccharides or sialylated milk oligosaccharides (SMOs) with Sia residues at the end of sugar chains. The structural, biological diversity, and concentration of milk oligosaccharides in mammalian milk are significantly different among species. HMOs have multiple health benefits for newborns, including development of immune system, modification of the intestinal microbiota, anti-adhesive effect against pathogens, and brain development. Most infant formulas lack oligosaccharides which resemble HMOs. Formula-fed infants perform poorly across physical and psychological wellbeing measures and suffer health disadvantages compared to breast-fed infants due to the differences in the nutritional composition of breast milk and infant formula. Of these milk oligosaccharides, SMOs are coming to the forefront of research due to the beneficial nature of Sia. This review aims to critically discuss the current state of knowledge of the biology and role of SMOs in human milk, infant formula milks, and milk from several other species on gut and brain health of human and animal offspring.

Influence of 2'-fucosyllactose and galacto-oligosaccharides on the growth and adhesion of Streptococcus mutans

Human milk oligosaccharides, such as 2'-fucosyllactose (2'-FL), and galacto-oligosaccharides (GOS), a prebiotic carbohydrate mixture, are being increasingly added to infant formulas, necessitating the understanding of their impact on the oral microbiota. Here, for the first time, the effects of 2'-FL and GOS on the planktonic growth and adhesion characteristics of the caries-associated oral pathogen Streptococcus mutans were assessed, and the results were compared against the effects of xylitol, lactose and glucose. There were differences in S. mutans growth between 2'-FL and GOS. None of the three S. mutans strains grew with 2'-FL, while they all grew with GOS as well as lactose and glucose. Xylitol inhibited S. mutans growth. The adhesion of S. mutans CI 2366 to saliva-coated hydroxyapatite was reduced by 2'-FL and GOS. Exopolysaccharide-mediated adhesion of S. mutans DSM 20523 to a glass surface was decreased with 2'-FL, GOS and lactose, and the adhesion of strain CI 2366 strain was reduced only by GOS. Unlike GOS, 2'-FL did not support the growth of any S. mutans strain. Neither 2'-FL nor GOS enhanced the adhesive properties of the S. mutans strains, but they inhibited some of the tested strains. Thus, the cariogenic tendency may vary between infant formulas containing different types of oligosaccharides.

Alteration of the goat milk glycoproteins N/O-glycome at different lactation stages

Goat milk oligosaccharides represent an unexplored multi-functional ingredient for the dairy industry. Here, we qualitatively and quantitatively compared the N/O-glycome at different lactation stages via online hydrophilic interaction chromatography-tandem mass spectrometry. Complex N-glycans and high mannose N-glycans constituted 82.1% and 17.9% of the glycan pool, respectively. N-glycans with isomers containing non-bisected antenna complex structures accounted for 30.8%. N-glycans modified with Neu5Ac, Neu5Gc and fucosylated were 3.7%, 5.3% and 35.3%. The triantennary trifucosylated complex N-glycan (H5N5F3) was reported for the first time. A comparison between colostrum and mature milk revealed a 1.20-fold decrease in total N-glycans and 1.66-fold decrease in fucosylation with ongoing lactation, echoing the trend in human milk. Similarly, Neu5Ac- and Neu5Gc-modified sialylation decreased by 1.69 and 3.62 times, respectively. In the O-glycome, 46.2% of structures were O-linked core 1, 23.1% were O-linked core 2, 7.7% were O-linked core 3 and core 4. As lactation progressed, overall O-glycans content decreased by 1.26-fold. Unlike human milk, Neu5Ac- and Neu5Gc-modified sialylation increased by 4.4 and 2 times, respectively. These findings will facilitate research on the structure-function relationship of goat milk oligosaccharides and the development of formula food targeting different age groups.

Proteolytic Activity of Bacillus subtilis upon κ-Casein Undermines Its "Caries-Safe" Effect

Milk is believed to be a relatively “caries-safe” food. This belief relies on the fact that caseins, which constitute around 80% of milk’s protein content, were found to inhibit the adhesion of Streptococcus mutans to enamel and, therefore, decrease biofilm formation. While S. mutans is considered a leading cause of dental disorders, Bacillus subtilis is a non-pathogenic foodborne bacterium, frequently contaminating milk and its products. This study aimed to investigate the effects of dairy-associated foodborne bacteria such as B. subtilis on biofilm formation by S. mutans in the presence of casein proteins. Our results indicate that there is a significant decrease in total biofilm formation by S. mutans exposed to a casein protein mixture in a mono-species culture, whereas, in the co-culture with B. subtilis, an inhibitory effect of the caseins mixture on S. mutans biofilm formation was observed. Proteolytic activity analysis suggested that B. subtilis is capable of breaking down milk proteins, especially κ-casein, which enables biofilm formation by S. mutans in the presence of milk caseins. Therefore, these findings may challenge the assumption that milk is “caries-safe”, especially in a complex microbial environment.

Casein Phosphopeptide-Amorphous Calcium Phosphate Attenuates Virulence and Modulates Microbial Ecology of Saliva-Derived Polymicrobial Biofilms

BACKGROUND

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) acts as a salivary biomimetic that provides bioavailable calcium and phosphate ions to augment fluoride-mediated remineralisation of early caries lesions. However, there are indications that it may also have beneficial ecological effects on the oral microbiome.

OBJECTIVE

This in vitro study investigated whether CPP-ACP could influence microbial counts, acidogenicity, and the relative abundance of specific caries- and health-associated bacterial -species in polymicrobial biofilms.

METHODS

Saliva-derived polymicrobial biofilms were grown for 96 h in a cariogenic environment and treated every 12 h with 2% CPP-ACP or vehicle control. Colony forming units (CFUs) and acidogenicity were estimated from the treated biofilms. Microbial ecological effects of CPP-ACP were assessed based on the relative abundance of 14 specific caries- and health-associated -bacterial species using a real-time quantitative PCR assay. -Results: CPP-ACP-treated biofilms showed relatively modest, but significant, reductions in microbial CFUs (21% reduction, p = 0.008) and acidogenicity (33% reduction, p < 0.001), compared to the control-treated biofilms. The CPP-ACP treated biofilms also exhibited significantly lower bacterial loads of cariogenic Scardovia wiggsiae (fold change 0.017, p < 0.001) and Prevotella denticola(fold change 0.005, p < 0.001), and higher bacterial loads of commensal Streptococcus sanguinis(fold change 30.22, p < 0.001), S. mitis/oralis(fold change 9.66, p = 0.012), and S. salivarius/thermophilus(fold change 89.35, p < 0.001) than the control-treated biofilms.

CONCLUSIONS

The results indicate that CPP-ACP has virulence-attenuating attributes that can influence a beneficial microbial ecological change in the biofilm.

Characterization of the in situ pellicle ultrastructure formed under the influence of bovine milk and milk protein isolates

OBJECTIVES

The present study aimed to investigate if bovine milk or milk protein isolates, respectively, alter the ultrastructure of thein situ pellicle and might therefore have an influence on oral health.

METHODS

In situ pellicle samples were formed on bovine enamel slabs exposed in the oral cavity of three subjects for 6, 30, 60 or 120 min. After 3 min of pellicle formation, mouthrinses were performed for 3 min with (non-)homogenized UHT- or fresh milk (0.3% or 3.8% fat), 30% UHT-treated cream or different types of casein- or milk protein isolates containing preparations. The specimens were removed after the exposure times and transmission electron microscopy (TEM) was performed. Native pellicle samples served as controls.

RESULTS

Topical ultrastructural pellicle modifications were detected after mouthrinses with all types of homogenized UHT- or fresh milk and after the application of a 3% native casein micelles containing experimental solution. Atypical globular protein structures, identified as casein micelles, were temporarily adsorbed onto the pellicle. They were closely associated with lipid droplets. Furthermore, the mouthrinses occasionally affected the morphology of salivary bacteria. However, no notable ultrastructural alterations remained after 120 min of pellicle formation.

CONCLUSION

For the first time, bovine milk- and micellar casein-induced pellicle modifications were revealed by TEM. The adsorption of micellar casein is possibly due to its molecular interactions.

CLINICAL SIGNIFICANCE

Bovine milk or micellar caseins provide some potential for the development of preventive strategies against bacterial biofilm formation or erosive processes at the tooth surface.

Acquired Enamel Pellicle Modification with Casein and Mucin in Different Concentrations and its Impact on Initial Dental Erosion

Casein and mucin have been shown to improve the erosion-protective properties of the pellicle when applied in combination. The aim of this in vitro study was to optimize the concentrations of these 2 proteins to achieve a maximum protective effect. For the 2 parts of this study, we prepared a total of 195 human enamel specimens and randomly assigned them to 13 groups, corresponding to 11 different casein-mucin concentration-combinations tested and 2 negative control groups (humid chamber). They underwent 5 cycles, consisting of pellicle formation from human whole saliva (2 h, 30°C), modification of the pellicle with casein and mucin in different concentrations (immersion in protein solutions for 2 h, 30°C), and erosion for 1 min in citric acid (0.65%, pH 3.5, 30°C). Surface microhardness (SMH), surface reflection intensity (SRI), and in the first part also calcium release were monitored during the cycling process, and analyzed with Kruskal-Wallis and post hoc Dunn’s tests. The results suggest that the best concentrations to achieve the highest erosion-protective effect are 3.0% casein and 0.81% mucin, which lead to a significant protection as measured by SMH as well as SRI compared to the unmodified pellicle. For the calcium release, no significant differences were found. This concentration combination corresponds to a general raise of the protein concentrations and a change in the molar ratio of the proteins as compared to earlier studies. Casein and mucin could now be incorporated at the determined concentration as natural ingredients in oral care products designed to protect against erosion.

Sialylated Oligosaccharides and Glycoconjugates of Human Milk. The Impact on Infant and Newborn Protection, Development and Well-Being

Human milk not only has nutritional value, but also provides a wide range of biologically active molecules, which are adapted to meet the needs of newborns and infants. Mother’s milk is a source of sialylated oligosaccharides and glycans that are attached to proteins and lipids, whose concentrations and composition are unique. Sialylated human milk glycoconjugates and oligosaccharides enrich the newborn immature immune system and are crucial for their proper development and well-being. Some of the milk sialylated oligosaccharide structures can locally exert biologically active effects in the newborn’s and infant’s gut. Sialylated molecules of human milk can be recognized and bound by sialic acid-dependent pathogens and inhibit their adhesion to the epithelial cells of newborns and infants. A small amount of intact sialylated oligosaccharides can be absorbed from the intestine and remain in the newborn’s circulation in concentrations high enough to modulate the immunological system at the cellular level and facilitate proper brain development during infancy. Conclusion: The review summarizes the current state of knowledge on sialylated human milk oligosaccharides and glycoconjugates, discusses the significance of sialylated structures of human milk in newborn protection and development, and presents the advantages of human milk over infant formula.

Effects of citric acid modified with fluoride, nano-hydroxyapatite and casein on eroded enamel

OBJECTIVES

The aim of this in vitro study was to evaluate the effects of citric acid containing fluoride, nano-hydroxyapatite, and casein on eroded enamel.

DESIGN

The crowns of 120 extracted bovine incisors were embedded in acrylic resin. An enamel window (2 × 3 mm) was created on the surface. Before in vitro pellicle formation samples were eroded in 1% citric acid (pH = 3.2) for 1 h at 36 °C and were randomly classified to eight groups (n = 15) as follows: Positive control: 1% citric acid, Negative control: Distilled water, F1: 0.047 mmol/L sodium fluoride, F2: 0.071 mmol/L sodium fluoride, NHA1: %0.05 Nano-Hydroxyapatite, NHA2: %0.1 Nano-Hydroxyapatite, C1: %0.02 Casein, C2: %0.2 Casein. Erosion cycling was performed three times daily for 3 days. In each cycle, the samples were immersed in 10 mL of control or modified solutions (10 min) and in 10 mL of artificial saliva (60 min). The surface roughness and enamel loss were analyzed by using profilometer, scanning electron microscopy (SEM) and atomic force microscopy techniques (AFM).

RESULTS

Among the groups, the positive control group was found to be having the highest erosive wear. Erosive wear in the F2, NHA2, C1, and C2 groups was not significantly different from the negative control group (p > 0.05). The C1 and C2 groups showed that erosion terminated and minimal tissue recovery occurred on the enamel surface.

CONCLUSION

Although all modifications reduced further demineralization, the citric acid modification with casein was found to be having a greater impact on dental erosion than the others.

4000 years of human dietary evolution in central Germany, from the first farmers to the first elites

Investigation of human diet during the Neolithic has often been limited to a few archaeological cultures or single sites. In order to provide insight into the development of human food consumption and husbandry strategies, our study explores bone collagen carbon and nitrogen isotope data from 466 human and 105 faunal individuals from 26 sites in central Germany. It is the most extensive data set to date from an enclosed geographic microregion, covering 4,000 years of agricultural history from the Early Neolithic to the Early Bronze Age. The animal data show that a variety of pastures and dietary resources were explored, but that these changed remarkably little over time. In the human δ¹⁵N however we found a significant increase with time across the different archaeological cultures. This trend could be observed in all time periods and archaeological cultures (Bell Beaker phenomenon excluded), even on continuously populated sites. Since there was no such trend in faunal isotope values, we were able largely to exclude manuring as the cause of this effect. Based on the rich interdisciplinary data from this region and archaeological period we can argue that meat consumption increased with the increasing duration of farming subsistence.

In δ¹³C, we could not observe any clear increasing or decreasing trends during the archaeological time periods, either for humans or for animals, which would have suggested significant changes in the environment and landscape use. We discovered sex-related dietary differences, with males of all archaeological periods having higher δ¹⁵N values than females, and an age-related increasing consumption of animal protein. An initial decrease of δ¹⁵N-values at the age of 1–2 years reveals partial weaning, while complete weaning took place at the age of 3–4 years.

Self-reported bovine milk intake is associated with oral microbiota composition

Bovine milk intake has been associated with various disease outcomes, with modulation of the gastro-intestinal microbiome being suggested as one potential mechanism. The aim of the present study was to explore the oral microbiota in relation to variation in self-reported milk intake. Saliva and tooth biofilm microbiota was characterized by 16S rDNA sequencing, PCR and cultivation in 154 Swedish adolescents, and information on diet and other lifestyle markers were obtained from a questionnaire, and dental caries from clinical examination. A replication cohort of 31,571 adults with similar information on diet intake, other lifestyle markers and caries was also studied. Multivariate partial least squares (PLS) modelling separated adolescents with low milk intake (lowest tertile with <0.4 servings/day) apart from those with high intake of milk (≥3.7 servings/day) based on saliva and tooth biofilm, respectively. Taxa in several genera contributed to this separation, and milk intake was inversely associated with the caries causing Streptococcus mutans in saliva and tooth biofilm samples by sequencing, PCR and cultivation. Despite the difference in S. mutans colonization, caries prevalence did not differ between milk consumption groups in the adolescents or the adults in the replication cohort, which may reflect that a significant positive association between intake of milk and sweet products was present in both the study and replication group. It was concluded that high milk intake correlates with different oral microbiota and it is hypothesized that milk may confer similar effects in the gut. The study also illustrated that reduction of one single disease associated bacterial species, such as S. mutans by milk intake, may modulate but not prevent development of complex diseases, such as caries, due to adverse effects from other causal factors, such as sugar intake in the present study.

Impact of Acquired Pellicle Modification on Adhesion of Early Colonizers

New preventive approaches against dental erosion caused by acidic drinks and beverages include fortification of beverages with natural polymers. We have shown that the mixture of casein and mucin significantly improved the erosion-inhibiting properties of the human pellicle layer. This study aimed to investigate the effect of pellicle modification by casein, mucin and a casein-mucin mixture on the adhesion of early bacterial colonizers. Test specimens of human tooth enamel were prepared, covered with saliva and coated with 0.5% aqueous (aq.) casein, 0.27% aq. mucin or with 0.5% aq. casein-0.27% aq. mucin, after which the adhesion of Streptococcus gordonii, Streptococcus oralis, and Actinomyces odontolyticus was measured after incubation for 30 min and 2 h. log10 colony-forming units were compared by nonparametric tests. All three bacterial strains adhered in higher number to pellicle-coated enamel than to native enamel. The protein modifications of pellicle all decreased the counts of adhering bacteria up to 0.34 log10/mm2, the most efficient being the casein-mucin mixture. In addition to the recently shown erosion-reducing effect by casein-mucin, modification of the pellicle may inhibit bacterial adherence compared to untreated human pellicle.

Holes in teeth - Dental caries in Neolithic and Early Bronze Age populations in Central Germany

This study provides diachronic insight into the epidemiology of carious defects in teeth of Neolithic and Early Bronze Age populations in Central Germany over a period of 4000 years. The data were retrieved from skeletal remains uncovered at 21 sites throughout the Middle Elbe-Saale region (MES), comprising a total of 494 individuals with preserved teeth. The data generated were examined for age- and sex-related differences in order to gain information about the dietary habits and socio-economic structures of the period with the goal of identifying potential diachronic changes. The results indicated that dietary habits changed over the course of the Neolithic period: the prevalence of caries significantly decreased between the Early and Late Neolithic. The adults from the Early Neolithic sample, particularly those from the LBK bore the highest rate of caries. This highlights the essential importance of cereals in the diet of the early farmers in the Middle Elbe-Saale region. As time went on, meat and dairy products became more and more important, which had a positive impact on dental health. The data also show sex-specific differences: women were more often affected by caries than men and female jaws also generally exhibited greater numbers of carious teeth than their male counterparts. Dental health is a reflection of both biological factors and of economic and sociocultural structures.

Effect of CPP/ACP on initial bioadhesion to enamel and dentin in situ

The present in situ study investigated the influence of a preparation containing CPP/ACP (caseinphosphopeptide-amorphous calcium phosphate) (GC Tooth mousse) on initial bacterial colonization of enamel and dentin. Therefore, pellicle formation was performed in situ on bovine enamel and dentin specimens fixed to individual upper jaw splints worn by 8 subjects. After 1 min of pellicle formation GC Tooth mousse was used according to manufacturer's recommendations. Rinses with chlorhexidine served as positive controls. Specimens carried without any rinse served as negative controls. After 8 h overnight exposure of the splints, bacterial colonization was quantified by fluorescence microscopy (DAPI and BacLight live/dead staining). Additionally, the colony forming units (CFU) were determined after desorption. Furthermore, the effects on Streptococcus mutans bacteria were tested in vitro (BacLight). There was no significant impact of CPP/ACP on initial bacterial colonization proved with DAPI and BacLight. Determination of CFU showed statistical significance for CPP/ACP to reduce bacterial adherence on enamel. The in vitro investigation indicated no antimicrobial effects for CPP/ACP on Streptococcus mutans suspension. Under the chosen conditions, CPP/ACP (GC Tooth mousse) had no significant impact on initial biofilm formation on dental hard tissues. The tested preparation cannot be recommended for biofilm management.

Antiadhesion agents against Gram-positive pathogens

ABSTRACT 

A fundamental step of Gram-positive pathogenesis is the bacterial adhesion to the host tissue involving interaction between bacterial surface molecules and host ligands. This review is focused on antivirulence compounds that target Gram-positive adhesins and on their potential development as therapeutic agents alternative or complementary to conventional antibiotics in the contrast of pathogens. In particular, compounds that target the sortase A, wall theicoic acid inhibitors, carbohydrates able to bind bacterial proteins and proteins capable of influencing the bacterial adhesion, were described. We further discuss the advantages and disadvantages of this strategy in the development of novel antimicrobials and the future perspective of this research field still at its first steps.

Strategies for a direct characterization of phosphoproteins on hydroxyapatite surfaces

We show in this work how systems formed by phosphoproteins on calcium phosphate surfaces can be directly characterized, in real time, in liquid medium, without the need for elution or labeling. Specifically, we show how this is possible by applying three different techniques: ellipsometry, quartz crystal microbalance with dissipation, and atomic force microscopy-based friction force spectroscopy. We apply these techniques to study two different model systems, i.e. those formed upon the adsorption of two model phosphoproteins (κ- and β-casein) on hydroxyapatite (HA) surfaces. Information on the kinetics of adsorption, surface excess, viscoelasticity, water content, thickness of the layers, and protein-surface interaction is provided. Results indicate that both phosphoproteins form homogeneous elastic highly hydrated monolayers on the HA surfaces, the strength of β-casein layers being higher by approximately a factor of 4. Based on the experimental results, models for the conformation of κ- and β-casein molecules adsorbed on HA surfaces are proposed.

The effects of beverages on plaque acidogenicity after a sugary challenge

BACKGROUND

Caries prevention traditionally has emphasized the restriction of cariogenic foods and beverages, but it has placed less emphasis on how the choice, combination and sequence of consumed foods and beverages may help reduce plaque acidogenicity. The authors conducted a study to examine whether whole milk, 100 percent apple juice or tap water affect dental plaque acidity in people after a sugary challenge.

METHODS

Twenty adults participated in a randomized controlled crossover study. Participants consumed four combinations of foods: 20 grams of dry sugary Froot Loops (FL) (Kellogg's, Battle Creek, Mich.) cereal, 20 g of FL followed by 50 milliliters of milk (FL/milk), 20 g of FL followed by 50 mL of juice (FL/juice) and 20 g of FL followed by 50 mL of water (FL/water). The authors used a touch microelectrode to take plaque pH readings at the interproximal space just below the contact area between the maxillary premolars on both left and right sides at two and five minutes after FL consumption and at two to 30 minutes after milk, juice or water consumption.

RESULTS

Consumption of FL plaque pH (standard deviation [SD]) was 5.83 (0.68) at 30 minutes, whereas plaque pH (SD) in the FL/milk group was 6.48 (0.30), which was significantly higher than that for FL/juice (5.83 [0.49]) or FL/water (6.02 [0.41]) (P < .005) at 35 minutes.

CONCLUSION

Drinking milk after a sugary cereal challenge significantly reduced plaque pH drop due to the sugary challenge.

PRACTICAL IMPLICATIONS

When discussing the cariogenicity of foods and beverages with patients, dentists and other health care professionals should emphasize that the order of ingesting sugary and nonsugary foods is important and may affect their oral health.

Anti-caries DNA vaccine-induced secretory immunoglobulin A antibodies inhibit formation of Streptococcus mutans biofilms in vitro

AIM

To investigate the effects of anti-caries DNA vaccine-induced salivary secretory immunoglobulin A (S-IgA) antibodies on Streptococcus mutans (S. mutans) adherence and biofilms formation in vitro.

METHODS

Adult female Wistar rats were intranasally immunized with the anti-caries DNA vaccine pGJA-P/VAX. Their saliva samples were collected at different times after the immunization, and S-IgA antibody level in the saliva and its inhibition on S. mutans adherence were examined. The effects of S-IgA in the saliva with the strongest inhibitory effects were examined at 3 different stages, ie acquired pellicles, biofilm formation and production of mature biofilms. The number of viable bacteria and depth of the biofilm at 16 h in each stage were determined using counting colony forming units and using a confocal laser scanning microscopy (CLSM). The participation of S-IgA in acquired pellicles and its aggregation with S. mutans were also observed under CLSM.

RESULTS

The S-IgA titer in saliva reached its peak and exhibited the strongest inhibition on S. mutans adhesion at 10 weeks after the immunization. The colonies and depth of the biofilm in the saliva-pretreated group were 41.79% and 41.02%, respectively, less than the control group. The colonies and depth of the biofilm in the co-culture group were 27.4% and 22.81% less than the control group. The assembly of S. mutans and S-IgA was observed under CLSM after co-cultivation. In the mature-stage biofilm, no differences were observed between the different groups.

CONCLUSION

These results demonstrate that the anti-caries DNA vaccine induces the production of specific S-IgA antibodies that may prevent dental caries by inhibiting the initial adherence of S. mutans onto tooth surfaces, thereby reducing the accumulation of S. mutans on the acquired pellicles.

Effects of human milk on adhesion of Streptococcus mutans to saliva-coated hydroxyapatite in vitro

Adhesion of bacteria to pellicle-coated tooth surfaces is the first step in biofilm formation on teeth. The aim of this study was to explore whether human milk prevents or promotes adhesion of cariogenic Streptococcus mutans to saliva-coated hydroxyapatite (HA) using an in vitro model system. S. mutans binding to HA coated with human parotid saliva (s-HA) or human milk was studied, in addition to binding inhibition to s-HA by human milk. S. mutans did not bind to HA coated with milk. S. mutans binding to s-HA was inhibited by milk from 15 (71 %) of 21 women, whereas milk from the remaining 6 mothers enhanced binding of S. mutans to s-HA. Inhibition of S. mutans binding correlated with bacterial binding to s-HA (r = 0.76). Human milk does not mediate adhesion of S. mutans to HA in vitro, but affects adhesion in an individually varying fashion. Phenotypic variations in milk and saliva glycosylation may explain the inhibitory capacity and possibly affect susceptibility to colonization by S. mutans in childhood.

The effect of traditional African food mixtures on growth, pH and extracellular polysaccharide production by mutans streptococci in vitro

Four, traditional African food mixtures (maize plus milk and sugar, maize plus gravy, samp plus beans, brown bread plus margarine and peanut butter) were evaluated for their ability to sustain the growth of mutans streptococci in batch culture. A synthetic complex medium, brain heart infusion with 3% sucrose was used as an experimental control. Six NCTC laboratory reference strains and five clinical isolates collected from the plaque of children were investigated. The doubling time of bacterial strains was prolonged in maize plus gravy (2.5-6.0 h) and samp plus beans (1.3-9.9h), and the number of cell divisions was low, compared with bread plus margarine plus peanut butter (0.7-5.1h). The least amount of acid was produced in maize plus milk plus sugar (3.92+/-8.15 mmole/mL), and the average pH during the fermentation of maize plus milk plus sugar, maize plus gravy and samp plus beans did not drop below the critical point for enamel demineralisation, pH 5.7. Bacterial growth in samp plus beans produced a small quantity of lactic acid (0.46+/-1.10 mmole/mL) compared to bread plus margarine and peanut butter (2.64+/-3.30 mmole/mL) and BHI plus 3% sucrose (12.23+/-10.72 mmole/mL). Extracellular polysaccharide (ECP) produced was lowest in maize plus milk and sugar (0.22+/-0.33 mg/mL), compared with the remaining food mixtures (0.47-1.75 mg/mL). Statistical analysis showed that the influence of the mixed-foods on doubling time (F=3.01, P=0.03), pH (F=14.41, P<0.0001) and ECP (F=135.32, P<0.0001) was greater than the significant variance found between mutans streptococci strains. Results suggest that the level of mutans streptococci activity in samp plus beans, maize plus milk and sugar and maize plus gravy contributes little towards the formation of dental caries, and that significant differences exist between mutans streptococci laboratory reference and clinical strains in response to traditional African food mixtures.

Identification by mass spectroscopy of F4ac-fimbrial-binding proteins in porcine milk and characterization of lactadherin as an inhibitor of F4ac-positive Escherichia coli attachment to intestinal villi in vitro

Enterotoxigenic Escherichia coli (ETEC) must attach to the intestinal surface to cause diarrhea. Milk and colostrum play an important role in protecting suckling piglets against ETEC through their constituent antibodies as well as non-immunoglobulin factors. We used affinity chromatography and liquid chromatography-mass spectrometry to identify lactadherin, beta-casein, whey acidic protein, lipoprotein lipase, and several structural cellular proteins as non-immunoglobulin F4ac fimbriae-binding porcine milk proteins. To determine their potential biological relevance in a digestive environment, we treated porcine milk with pepsin or pepsin-pancreating in vitro, and found that pepsin digestion did not interfere with the F4-binding capacity of lactadherin as well as it revealed a cryptic F4-binding site(s) in alpha-S(1) casein and heart fatty acid binding protein. We also demonstrated that lactadherin interfered with attachment of F4ac-positive ETEC to porcine small intestinal villi in vitro and that this interference was carbohydrate dependent. Thus, our evidence suggests that lactadherin and the other F4-binding milk proteins, together with other defense components of milk, could play a role in protection of neonatal piglets against ETEC induced diarrhea.

The oral environment: the challenge for antimicrobials in oral care products

For any antibacterial/ anti-plaque system from an oral care product to be effective, it must firstly be delivered and retained at relevant sites in the oral cavity and secondly, remain active within the chosen formulation to successfully target the biofilm cells within dental plaque. This must include inhibition of the growth and metabolism of relevant organisms associated with disease. This review will concentrate on understanding the environmental conditions in which such oral care products must work and summarise the activity within the oral cavity of the main antibacterial and anti-plaque agents in common oral care products, namely chlorhexidine, essential oils, metal salts and Triclosan. Routes to further enhance the activity of these products, together with the use of relatively novel formats such as confectionery products to provide added consumer oral health benefits will be considered.

Anti-adhesion therapy of bacterial diseases: prospects and problems

The alarming increase in drug-resistant bacteria makes a search for novel means of fighting bacterial infections imperative. An attractive approach is the use of agents that interfere with the ability of the bacteria to adhere to tissues of the host, since such adhesion is one of the initial stages of the infectious process. The validity of this approach has been unequivocally demonstrated in experiments performed in a wide variety of animals, from mice to monkeys, and recently also in humans. Here we review various approaches to anti-adhesion therapy, including the use of receptor and adhesin analogs, dietary constituents, sublethal concentrations of antibiotics and adhesin-based vaccines. Because anti-adhesive agents are not bactericidal, the propagation and spread of resistant strains is much less likely to occur than as a result of exposure to bactericidal agents, such as antibiotics. Anti-adhesive drugs, once developed, may, therefore, serve as a new means to fight infectious diseases.

Moderation of oral bacterial adhesion on saliva-coated hydroxyapatite by polyaspartate

AIMS

Synthetic sodium alpha,beta-polyaspartate (PA) has been investigated as a moderator of adhesion and the subsequent biofilm formation by oral bacteria.

METHODS AND RESULTS

The inhibition of bacterial adhesion by PA was assessed by (i) a 30-min incubation with Streptococcus sanguis in a microtitre assay with the wells coated with hydroxyapatite (HAP) and (ii) an 18-h challenge with human salivary microflora in a HAP disc assay. In contrast to HAP-coated surfaces, clean polystyrene surfaces in the microtitre assay exhibited no anti-adhesion properties. It has been found that PA significantly and similarly adsorbs onto HAP surfaces in the presence and absence of salivary coating. The HAP disc assay also showed that PA, both in aqueous solutions and in toothpaste, reduced the level of adhered microflora and this effect was enhanced by added propylene oxide-ethylene oxide copolymers.

CONCLUSION

The principal finding from this work is the potential role for PA as an inhibitor of dental plaque formation. PA may significantly modify the salivary pellicle.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work indicates the use of PA in controlling the development of dental plaque and the formation of bacterial biofilm in general.

Influence of dentifrices and dietary components in saliva on wettability of pellicle-coated enamel in vitro and in vivo

In vitro salivary pellicles were found to be less hydrophobic by water contact angles than clinically formed pellicles. In this study, water contact angles were measured on enamel coated with pellicles adsorbed from reconstituted human whole saliva (RHWS) and after exposure to dentifrices or dietary components. In addition, adhesion of Streptococcus oralis J22 to pellicles formed from RHWS with minor amounts of milk added and after exposure to dentifrices was studied. Exposure of RHWS-pellicles to milk or salad oil yielded an increase in the hydrophobicity of in vitro pellicles to values observed in vivo, but a decrease was seen after exposure to a sugar solution. Pellicles formed from saliva with 0.4% milk added attracted less S. oralis cells than pellicles formed in the absence of milk components. Exposure of pellicles formed from saliva with milk added to various dentifrices had a variable effect on bacterial adhesion: markedly lower numbers of adhering S. oralis were found for a dentifrice with NaF, but exposure to dentifrices containing SnF2 or hexametaphosphate showed slightly increased adhesion. In summary, dietary components have influence on the hydrophobicity of enamel pellicles, while combinations of dietary components and dentifrices certainly influence the adhesiveness of the pellicles. The effects of dietary components on pellicle conditioning film should be taken into consideration in research on the development of ingredients to control intraoral surface chemistry and microbiology, as well as in the development of oral products.

Interactions Between Escherichia coli and Newcastle Disease Virus in Chickens

We investigated the interaction between Newcastle disease virus (NDV) and Escherichia coli in cell cultures, embryonated eggs, and 8-wk-old chickens. We measured the interactions on the basis of bacterial adherence and NDV hemagglutination titer in chickens, chicken embryos, and chicken embryo cell culture. Depending on the inoculation order of E. coli, a significant alteration of the growth of NDV was observed in both chickens and chicken embryos. When certain strains of E. coli were given before NDV exposure, the virus titers were lowered. In chickens, the mean virus titer was significantly (P < 0.05) lowered in the crop, the proventriculus, the gizzard, and the jejunum. However, there were no significant differences (P < 0.05) between the two groups for NDV titers in the duodenum, ileum, and cecum. In chicken embryos, when E. coli serotypes O78 and O119:B14 were inoculated before NDV exposure, the mean NDV titers were significantly (P < 0.5) lowered. However, there were no significant differences (P < 0.05) in NDV titer between the two groups when E. coli serotypes O78:K80:NM and O1ab:K NM were inoculated 24 hr before NDV exposure. When NDV was given prior to E. coli exposure, NDV titer was higher in both chickens and chicken embryos. In chickens, when NDV was given 48 hr before E. coli inoculation, NDV was detected in the proventriculus, gizzard, jejunum, ileum, and cecum, whereas no virus was detected in the control groups (NDV only). In the crop, NDV was detected at a significantly (P < 0.05) higher titer in the E. coli-inoculated group when compared with the control group that received NDV alone. In chicken embryos, virus titer was significantly (P < 0.05) higher when NDV was given 24 hr before E. coli inoculation for all three NDV strains used (Ulster and V4 strains). Adherence of E. coli to chicken embryo kidney (CEK) cells was significantly higher (P < 0.05) when the CEK cells were infected first with NDV and then by E. coli. The mean bacterial count per microscopic field in NDV-uninfected monolayers was eight compared with 112 for the NDV-infected monolayers. In approximately 10% of the fields in NDV-infected monolayers, the bacteria were too numerous to count.

Passive immunization with bovine milk containing antibodies to a cell surface protein antigen-glucosyltransferase fusion protein protects rats against dental caries

Cell surface protein antigen (PAc) and glucosyltransferases (GTF) of Streptococcus mutans are major colonization factors of the organism. We prepared bovine milk containing antibodies against a fusion of the saliva-binding alanine-rich region of PAc with the glucan-binding domain of GTF-I. This study examined the effect of the immune milk on the cariogenicity of S. mutans in a rat model. Concentrated immune milk was fed to rats once a day for 55 days. The group that received immune milk had significantly less caries development than controls.

Stability and activity of specific antibodies against Streptococcus mutans and Streptococcus sobrinus in bovine milk fermented with Lactobacillus rhamnosus strain GG or treated at ultra-high temperature

Passive local immunization against dental caries is a promising approach to its prevention, as clinical evidence of active oral or nasal immunization is still limited and controversial. By means of systemic immunization of pregnant cows with a multivalent vaccine, high titres of IgG antibodies against human cariogenic bacteria, Streptococcus mutans and Streptococcus sobrinus, were produced in bovine colostrum. The purified immune product (IP) of this preparation has a number of anticariogenic properties, such as inhibition of streptococcal adherence to saliva-coated hydroxyapatite and inhibition of glucosyltransferase enzymes. This study investigated whether IP antibodies remained active and functional when added to ultra-high temperature (UHT)-treated milk or to Lactobacillus rhamnosus GG (LGG)-fermented milk stored for an extended time. LGG was chosen because of its widely known health benefits in humans and animals. A commercial UHT toddler's milk was supplemented with IP and stored for 2 months at 5, 21 and 30 degrees C. The antistreptococcal titres in UHT milk did not decline at any temperature during storage, and UHT-IP inhibited the adherence of S. mutans for up to 2 months. This was not the case with UHT toddler's milk without IgG antibodies. Milk was fermented with live LGG cells in the presence or absence of 5% IP. The antistreptococcal titres declined to about 30% of the original titres after storage. Fresh milk alone slightly enhanced streptococcal adhesion but fresh milk with IP inhibited the adherence of S. mutans by over 50%. LGG-positive fermented milk without antibodies also inhibited (P < 0.05) the adhesion by about 40%. In both LGG-fermented and UHT immune milk, the activity of antibodies against cariogenic streptococci was maintained during the expected shelf-life of these products. From the anticariogenic point of view it may be beneficial to add bovine-specific antibodies against mutans streptococci to probiotic LGG-containing milk products.