Oral Health Applications for Probiotics

Transcription

1 Oral Health Applications for Probiotics Andrew McBain Biofilm Research Group Manchester Pharmacy School University of Manchester Overview Oral microbiology introduction Dental probiotics and replacement therapy 1

2 The Oral Microbiota Distribution Accumulation at: Gingival margins (gingivitis / periodontal disease) Tooth fissures (dental caries) Tongue and other mucosal surfaces Density Saliva: c. 10 per ml Plaque c per gram Taxonomy c. 00* oral species. 0% currently uncultivated Firmicutes (e.g. streptococci) Actinobacteria (e.g. Actinomyces) Proteobacteria (e.g. Neisseria) Bacteroidetes (e.g. Porphyromonas) Fusobacteria (e.g. Fusobacterium) TM phylum (so far uncultivated) c. 0% culturability Aas JA et al. (00) Defining the normal bacterial flora of the oral cavity. J Clin Microbiol. 00 Nov;(11):1-.

3 How does plaque form? Aggregation Coaggregation Planktonic bacteria Coadhesion. Biofilm dispersion 1. Colonisation.Plaque development, Tooth surface, Plaque matrix;, Bacteria. The Oral Microbiota and Disease Processes The specific plaque hypothesis - specific pathogens The non-specific plaque hypothesis - all plaque is bad The ecological plaque hypothesis - change in environment -> adverse change in microbiota -> disease

4 The ecological plaque hypothesis for periodontal disease GINGIVAL HEALTH Plaque reduction Reduced inflammation Low GCF flow Higher oxygen Predominantly Gram +ve microflora Facultative anaerobes (Streprococci Actinomycetes etc. INFLAMMATORY RESPONSE ENVIRONMENTAL CHANGE ECOLOGICAL SHIFT GINGIVITIS Plaque accumulation Increased inflammation High GCF flow Lower oxygen Predominantly Gram -ve microflora Obligate anaerobes (Eubacterium Porthyromonas Fusobacteria etc.) Philip Marsh The ecological plaque hypothesis for dental caries HEALTH Sugar intake Neutral ph High: Strep. Gordonii Strep. Oralis Strep. Mitis A. naeslundii Enamel health Stress ENVIRONMENTAL SHIFT ECOLOGICAL SHIFT DISEASE Caries Acid production Low ph Increased: Strep. Mutans Lactobacilli Bifidobacteria Increased caries risk Philip Marsh

5 The Oral Systemic Interface Purported relationships between periodontal disease and heart disease Maternal oral health and premature birth Oral health and bacteraemia Oral bacterial involvement in device-related infections. 9 Traditional management Dental hygiene (Cleaning and antimicrobials) 10

6 Plaque and antimicrobials Biofilm bacteria are x less susceptible to antibiotics and biocides than are planktonic bacteria McBain, Plaque recalitrance Bulk phase [Nutrients] [Antimicrobials] [Oxygen] Taxonomically distinct cell clusters Phenotypically distinct cell clusters, Persister cells

7 Viability Profiling of Streptococcus mutans Biofilms Green= live Red= dead 1 Alternative approaches Replacement therapy applied directly to a site with the intention of combating or preventing an infection. Probiotics delivered orally and have been associated with a wide range of claimed localised and systemic beneficial effects, proven or otherwise. (prebiotic equivalents include urea and arginine) 1

8 Replacement therapy for the prevention of caries- a caries vaccine Jeffrey Hillman originally at the Forsyth Dental Center, Boston A key concept in this is the involvement of Streptococcus mutans in cariogenesis. Replacement therapy for caries involves the use of mutants that do not produce lactic acid From the press, Oragenics, Jeff s company, has patented a simple swab of bacteria that when wiped across a set of teeth will grant a lifetime of protection from tooth decay 1 Replacement Therapy Evidence? Evidence from rat studies for both caries and periodontal disease. Anecdotal evidence that Prof. Hillman and four colleagues have remained colonised by the effector strains for over 0 years Regulatory problems with using engineered mutans strains in humans, Now focusing on natural mutans and S. rattus. 1

9 Dental Probiotics Mainly lactobacilli (esp. L. reuteri) Classed as safe (GRAS) by the FDA Sporadic reports in the literature back to around 19 Lactobacilli are lactic acid bacteria and lactic acid causes caries? Is there a conflict? 1 Caglar et al. 00 Administered Lactobacillus reuteri ATCC 0 or placebo once daily to healthy young adults (10 in total) in four groups of 0 volunteers. Group A drank 00ml of water containing a probiotic through a straw; Group B 00ml placebo water; Group C sucked probiotic tablet and Group D sucked placebo tables. Consumption of the probiotics via the tablet route resulted in highly significant decreases in S. mutans counts. Significant decreases in mutans also occurred for individuals who used the straw. The authors postulated that the lowering of S. mutans might occur by a systemic mechanism rather than direct interaction between probiotic and S. mutans. 1 9

10 Krasse et al. 00 Administered two different Lactobacillus reuteri strains of human origin, or a placebo to 9 patients with moderate to severe gingivitis in Sweden. Improvements (decreases in gingival indexes) were reported for the probiotic and control groups which were more significant for the probiotic group (both Lactobacillus strains). Interestingly, one of the lactobacillus strains appeared to be better clinically than the others. 19 Iniesta et al. 01 Forty gingivitis subjects over weeks administration of a daily tablet, containing Lactobacillus reuteri or placebo. There were no significant changes between and within the groups in the clinical variables. In saliva, total anaerobic counts after weeks and counts of Prevotella intermedia after weeks, showed significant reductions in the test group. In subgingival samples, significant reductions were observed for P. gingivalis counts. L. reuteri ATCC-PTA-9 was more frequently detected than L. reuteri DSM-19 by PCR. The effect of L. reuteri administered in tablets resulted in a reduction in the number of selected periodontal pathogens in the subgingival microbiota, but without an associated clinical impact. 0 10

11 Sunstar GUM The lozenges are stated to contain at least 00 million active viable Lactobacillus reuteri ProdentisTM (a patented mixture of equal amounts of L. reuteri ATCC 0 and L. reuteri ATCC PTA 9) 1 Why lactobacilli as dental probiotics? GRAS (generally regarded as safe)- FDA Easy to scale up Palatable Antagonistic to pathogens? Immunomodulation? Efficacy? But is acidogenesis an issue? 11

12 Keller and Twetman, 01, Preclinical testing of L. reuteri in oral microbiotas 1

13 Mature plaques Facultative anaerobes Total anaerobes Gram-negative anaerobes Log10 cfu.mm - Total streptococci Total lactobacilli Lactobacillus reuteri Log10 cfu.mm - Nascent plaques Total anaerobes Total aerobes * * Log 10 CFU.mm - * Total lactobacilli * * Total streptococci Gram-negative anaerobes Log 10 CFU.mm - * * * Control PT LR PT Control BF LR BF Control PT LR PT Control BF LR BF Control PT LR PT Control BF LR BF 1

14 Persistence of L. reuteri in plaques 10 Total eubacteria 10 Lactobacillus group qpcr 10 Lactobacillus reuteri qpcr copies.mm - copies.mm - Up to three weeks after dosing Figure Box plots showing a comparison of L. reuteri tracked by colony morphology (backward diagonals) with major bacterial groups i.e. total anaerobes (white), aerobes (forward diagonals) and total lactobacilli (crossed pattern). The vertical dotted lines enclose period of probiotic treatment. The horizontal bar inside the box represents the median while * indicates significant change observed (p < 0.0). Direct antagonism? No inhibition detected against actinomyces, Veillonella dispar, Lactobacillus rhamnosus, Prevotella oralis, Streptococcus mutans, Neisseria subflava and Streptococcus oralis. Even at glycerol concentrations of 00mM both Lactobacillus reuteri strains L1 and L did not produce any zones of inhibition. 1

15 Conclusions Oral biofilms- taxonomically complex but relatively culturable. Specific pathogens implicated in disease but also, considerable functional redundancy in the oral microbiome Physical cleaning and antimicrobial- based control regimes remain the clinically proven option. Considerable interest in probiotics which are currently (perhaps counter-intuitively) dominated by organisms of intestinal origin. More good quality clinical trials are needed. Mechanisms poorly understood. Considerable potential. 9 1