Anna Haukioja

Acid Production from Sugars and Sugar Alcohols by Probiotic Lactobacilli and Bifidobacteria in vitro

Some probiotic bacterial strains have been suggested to improve oral health. However, lactobacilli and bifidobacteria are associated with the progression of dental caries. The pH fall caused by 14 probiotic and dairy bacterial strains from glucose, lactose, sucrose, sorbitol and xylitol was followed. All strains used glucose, nine lactose and seven sucrose. Six of the lactobacilli caused a small decrease in pH with sorbitol and two with xylitol. None of the bifidobacteria fermented sugar alcohols. As all the strains could be considered acidogenic, more long-term clinical trials are needed before recommendations for oral health purposes can be made.

Probiotic Lactobacillus reuteri strains ATCC PTA 5289 and ATCC 55730 differ in their cariogenic properties in vitro

OBJECTIVE The effects of probiotics on cariogenic biofilms remain controversial. Our aim was to characterise two probiotic Lactobacillus reuteri strains, ATCC PTA 5289 and ATCC 55730 from a cariogenic standpoint in vitro. These strains are used in commercial products designed for oral health purposes. DESIGN The adhesion and biofilm formation were studied on saliva-coated hydroxyapatite. The effects of glucose or sucrose on the biofilm formation were also tested. Arginine metabolism was assessed by measuring the pH in the presence of glucose and arginine. The degradation of hydroxyapatite was measured in three different growth media. Streptococcus mutans strains Ingbritt and MT 8148 were used as positive controls for bacterial adhesion and degradation of hydroxyapatite. RESULTS Strain ATCC PTA 5289 adhered on saliva-coated hydroxyapatite and formed detectable biofilm, but strain ATCC 55730 was poor in both adhesion and biofilm formation. Both strains were arginolytic and raised the pH in the presence of arginine. The amount of dissolved calcium from hydroxyapatite correlated with bacterial growth rate and the final pH of the growth medium. CONCLUSION L. reuteri strains ATCC PTA 5289 and ATCC 55730 differed in their adhesion, biofilm formation and arginine metabolism in vitro. Thus, these probiotic lactobacilli are likely to differ in their behaviour and cariogenic potential also in an oral environment.

Persistent oral human papillomavirus infection is associated with smoking and elevated salivary immunoglobulin G concentration

BACKGROUND Prevalence and risk factors for human papillomavirus (HPV) persistence in oral mucosa are largely unknown. Furthermore, the antiviral effects of saliva in the outcome of oral HPV infections are unexplored. OBJECTIVES To compare the levels of selected salivary defence proteins in women with a persistent oral HPV infection and in those without any signs of oral HPV. Lifestyle factors including the use of oral contraceptives, oral sex, smoking and alcohol drinking habits were also assessed. STUDY DESIGN This nested case-control study of the Finnish Family HPV Study included 60 women with a persistent oral HPV infection and 117 women who remained HPV DNA negative throughout a 6-year follow-up. Whole saliva samples and oral scrapings for HPV testing were collected at the same visit. The oral HPV status was related to salivary concentrations of lactoferrin, lysozyme, IgA, IgG, total protein and sodium as well as to the use of oral contraceptives, oral sex, smoking and alcohol drinking habits. RESULTS Women with a persistent oral HPV infection had higher salivary levels of IgG (p=0.007) and lysozyme (p=0.002, when adjusted to the total protein concentration), than those without an HPV infection. Lactoferrin and IgA concentrations were not related to the HPV-status. Smoking increased the risk of a persistent oral HPV infection (p=0.020), but the oral HPV status was not related to other life-style factors studied. CONCLUSIONS Smoking is a risk factor for a persistent oral HPV infection. Oral HPV infection may be associated with increased concentrations of salivary IgG and lysozyme.

Effects of Lactobacillus reuteri PTA 5289 and L. paracasei DSMZ16671 on the adhesion and biofilm formation of Streptococcus mutans.

Probiotics have decreased the counts of salivary mutans streptococci (MS) in clinical studies. The aim of this study was to compare the effects of Lactobacillus reuteri PTA 5289 and L. paracasei DSMZ16671 on the adhesion of a reference strain and a clinical isolate of Streptococcus mutans and on the counts of MS in a biofilm. The adhesion of S. mutans Ingbritt and the clinical isolate S. mutans 2366 to a smooth glass surface and saliva-coated hydroxyapatite (SHA) were studied in the presence of and without the lactobacilli. A three-species biofilm formed on saliva-coated hydroxyapatite discs was used in the biofilm experiments. The lactobacilli did not affect adhesion to the glass surface but interfered with binding to SHA. No effects of the lactobacilli were detected on the MS levels in the three-species biofilms. The results of the SHA binding experiments best reflected the results of the existing clinical studies.

Bifidobacteria inhibit the growth of Porphyromonas gingivalis but not of Streptococcus mutans in an in vitro biofilm model

There is growing interest in the use of probiotic bifidobacteria for enhancement of the therapy, and in the prevention, of oral microbial diseases. However, the results of clinical studies assessing the effects of bifidobacteria on the oral microbiota are controversial, and the mechanisms of actions of probiotics in the oral cavity remain largely unknown. In addition, very little is known about the role of commensal bifidobacteria in oral health. Our aim was to study the integration of the probiotic Bifidobacterium animalis subsp. lactis Bb12 and of oral Bifidobacterium dentium and Bifidobacterium longum isolates in supragingival and subgingival biofilm models and their effects on other bacteria in biofilms in vitro using two different in vitro biofilms and agar-overlay assays. All bifidobacteria integrated well into the subgingival biofilms composed of Porphyromonas gingivalis, Actinomyces naeslundii, and Fusobacterium nucleatum and decreased significantly only the number of P. gingivalis in the biofilms. The integration of bifidobacteria into the supragingival biofilms containing Streptococcus mutans and A. naeslundii was less efficient, and bifidobacteria did not affect the number of S. mutans in biofilms. Therefore, our results suggest that bifidobacteria may have a positive effect on subgingival biofilm and thereby potential in enhancing gingival health; however, their effect on supragingival biofilm may be limited.

Probiotic intervention influences the salivary levels of Matrix Metalloproteinase (MMP)-9 and Tissue Inhibitor of metalloproteinases (TIMP)-1 in healthy adults

OBJECTIVE To study the effect of orally administered Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus rhamnosus GG on the salivary levels of Matrix Metalloproteinases (MMP)-8, MMP-9 and of Tissue Inhibitor of Metalloproteinases (TIMP)-1 in healthy adults. Furthermore, the correlations between MMP-8, MMP-9 and TIMP-1 and plaque and gingival indices, salivary mutans streptococci and lactobacilli counts, and stimulated saliva secretion rate were analysed. DESIGN The salivary samples originated from a randomized controlled trial where healthy student volunteers consumed probiotic or placebo lozenges twice a day for four weeks. The saliva samples were collected and clinical parameters measured at the baseline and at the end of the original study. For this study, the salivary levels of MMP-8, MMP-9 and TIMP-1 were analysed with immunofluorometric assay (IFMA) and enzyme-linked immunosorbent assay (ELISA). RESULTS In the probiotic group (n=29), salivary MMP-9 levels increased (p<0.01) and TIMP-1 levels decreased (p<0.01) significantly during the intervention. Furthermore, MMP-9/TIMP-1 ratio differed significantly from the baseline level (p<0.01). These changes were not observed in the control group (n=31). In the whole data, salivary MMP-9 and gingival index correlated (r=0.260, p<0.05 at baseline and r=0.354, p<0.01 at the end of the study). Intergroup differences or correlations with other clinical parameters were not found. Probiotic consumption did not affect the saliva flow rate. CONCLUSIONS Increased MMP-9 and decreased TIMP-1 levels in saliva may indicate that probiotics have immunomodulatory effects in the oral cavity. Furthermore, increased salivary MMP-9 levels may be an indication of the defensive potential of matrix metalloproteinases.

Persistent Oral Human Papillomavirus (HPV) Infection is Associated with Low Salivary Levels of Matrix Metalloproteinase 8 (MMP-8)

BACKGROUND A persistent human papillomavirus (HPV) infection is a prerequisite for a HPV related cancer to develop. Asymptomatic, persistent HPV infections are not only found in genital tract, but also on oral mucosa. Oral HPV persistence may be associated with behavioural factors, but data on the role of innate immunity in oral HPV infections are still limited. OBJECTIVES Salivary concentrations of matrix metalloproteinases MMP-8 and MMP-9, tissue inhibitor of MMPs (TIMP-1), myeloperoxidase, and serum concentrations of MMP-8 were analysed in women with a persistent oral HPV infection and, as a control, in women who remained HPV DNA-negative during a 6-year follow-up. The effects of smoking, lactation and alcohol use on the salivary and serum parameters were assessed, too. STUDY DESIGN A nested case-control setting was used to select a subgroup of 57 women with a persistent oral HPV infection and 102 controls from the Finnish Family HPV Study. RESULTS The salivary MMP-8/TIMP-1 molar ratio was lower in HPV DNA-positive women than in controls (p=0.036). The difference was more pronounced in non-smoking women, in this group also the salivary MMP-8 levels differed (p=0.047). There was a correlation between the salivary concentrations of myeloperoxidase and MMP-8 (r=0.567, p<0.001) or MMP-9 (r=0.234, p=003), but no correlation between salivary and serum MMP-8 levels. The MMP-9 concentration and the MMP-9/TIMP-1 molar ratio were significantly lower in smokers than in non-smokers (p=0.020 and p=0.003, respectively). CONCLUSIONS Persistent oral HPV infection was associated with a low salivary MMP-8 concentration indicating eventually a failure in oral anti-inflammatory defence.