Molecular and clinical analyses of Helicobacter pylori colonization in inflamed dental pulp

Background

Recently, dental pulp has been considered a possible source of infection of Helicobacter pylori (H. pylori) in children. We previously developed a novel PCR system for H. pylori detection with high specificity and sensitivity using primer sets constructed based on the complete genome information for 48 H. pylori strains. This PCR system showed high sensitivity with a detection limit of 1–10 cells when serial dilutions of H. pylori genomic DNA were used as templates. However, the detection limit was lower (10²–10³ cells) when H. pylori bacterial DNA was detected from inflamed pulp specimens. Thus, we further refined the system using a nested PCR method, which was much more sensitive than the previous single PCR method. In addition, we examined the distribution and virulence of H. pylori in inflamed pulp tissue.

Methods

Nested PCR system was constructed using primer sets designed from the complete genome information of 48 H. pylori strains. The detection limit of the nested PCR system was 1–10 cells using both H. pylori genomic DNA and bacterial DNA isolated from inflamed pulp specimens. Next, distribution of H. pylori was examined using 131 inflamed pulp specimens with the nested PCR system. In addition, association between the detection of H. pylori and clinical information regarding endodontic-infected teeth were investigated. Furthermore, adhesion property of H. pylori strains to human dental fibroblast cells was examined.

Results

H. pylori was present in 38.9% of inflamed pulp specimens using the nested PCR system. H. pylori was shown to be predominantly detected in primary teeth rather than permanent teeth. In addition, samplings of the inflamed pulp were performed twice from the same teeth at 1- or 2-week intervals, which revealed that H. pylori was detected in most specimens in both samplings. Furthermore, H. pylori strains showed adhesion property to human dental fibroblast cells.

Conclusion

Our results suggest that H. pylori colonizes inflamed pulp in approximately 40% of all cases through adhesion to human dental fibroblast cells.

Inhibitory effect of surface pre-reacted glass-ionomer (S-PRG) eluate against adhesion and colonization by Streptococcus mutans

Surface Pre-reacted Glass-ionomer (S-PRG) filler is a bioactive filler produced by PRG technology, which has been applied to various dental materials. A S-PRG filler can release multiple ions from a glass-ionomer phase formed in the filler. In the present study, detailed inhibitory effects induced by S-PRG eluate (prepared with S-PRG filler) against Streptococcus mutans, a major pathogen of dental caries, were investigated. S-PRG eluate effectively inhibited S. mutans growth especially in the bacterium before the logarithmic growth phase. Microarray analysis was performed to identify changes in S. mutans gene expression in the presence of the S-PRG eluate. The S-PRG eluate prominently downregulated operons related to S. mutans sugar metabolism, such as the pdh operon encoding the pyruvate dehydrogenase complex and the glg operon encoding a putative glycogen synthase. The S-PRG eluate inhibited several in vitro properties of S. mutans relative to the development of dental caries especially prior to active growth. These results suggest that the S-PRG eluate may effectively inhibit the bacterial growth of S. mutans following downregulation of operons involved in sugar metabolism resulting in attenuation of the cariogenicity of S. mutans, especially before the active growth phase.

Current knowledge among Japanese experienced general dentists regarding prevention of infective endocarditis

Infective endocarditis (IE), a life-threatening condition predominantly occurring in patients with underlying heart disease, is mainly caused by bacteremia induced by invasive dental treatment. However, the amount of related information shared between cardiologists and dentists appears to be inadequate. In the present study, a survey regarding prevention of IE, composed of 13 major questions, 2 of which also allowed free comments, was sent to approximately 3000 dentists belonging to a prefectural dental association in Japan. Of the 13.6% who returned the forms, more than 80% were general dentists with more than 20 years of experience. Approximately, 55% of the responders reported that they had opportunities to prescribe antibiotics prior to performing treatments with risk of IE, though noted difficulties with designation of which patients with heart disease were at risk. Most of the dentists considered that oral surgery procedures have a high risk for IE, whereas less invasive procedures were considered to be not associated with the disease. Approximately, 35% selected oral amoxicillin, with a dose of 2.0 g (20%) or 500 mg (27%) prescribed for adults, and 50 mg (10%) or 30 mg (12%) per kg of body weight for children. However, the timing of the antibiotics administration varied. The present results reveal current knowledge regarding prevention of IE among general dentists in Japan, and should be valuable for construction of a protocol to establish consensus between dentists and cardiologists.

Campylobacter rectus in the Oral Cavity Correlates with Proteinuria in Immunoglobulin A Nephropathy Patients

BACKGROUND

Periodontitis-related pathogens, such as Campylobacter or Treponema species, have recently been shown to be associated with immunoglobulin A nephropathy (IgAN). Some strains of Streptococcus mutans, a major pathogen of dental caries, harbour the cnm gene that encodes a collagen-binding protein (Cnm). This has also been demonstrated to be associated with urinary protein levels in IgAN patients.

OBJECTIVES

The purpose of the present study was to analyse the association of IgAN with C. rectus, Treponema denticola and cnm-positive S. mutans in the oral cavity of humans.

METHODS

The presence of C. rectus, T. denticola and cnm-positive S. mutans strains in saliva samples of 117 IgAN patients and 56 healthy controls was evaluated by PCR, and the subjects' clinical parameters were analysed.

RESULTS

C. rectus was significantly more prevalent in the IgAN group than in the control group (p < 0.05). The C. rectus-positive group was significantly associated with proteinuria in the IgAN group (p < 0.05). In addition, the C. rectus-positive and cnm-positive S. mutans group was shown to be more closely associated with urinary protein levels than the other groups (p < 0.0083).

CONCLUSION

Our results suggest that harbouring C. rectus in the oral cavity could be associated with proteinuria in IgAN patients.

A Potential New Risk Factor for Stroke: Streptococcus Mutans With Collagen-Binding Protein

BACKGROUND

Among human oral bacteria, particular kinds of Streptococcus mutans (SM) known as dental caries pathogens contain a collagen-binding protein, Cnm, and show platelet aggregation inhibition and matrix metalloproteinase-9 activation. We have previously reported that these strains may be a risk factor for intracerebral hemorrhage. As a major sample-providing hospital, we report the clinical details, including intracranial aneurysms and ischemic stroke.

METHODS

After the study received approval from the Ethical Committee, 429 samples of whole saliva were obtained from patients who were admitted to or visited our hospital between February 16, 2010, and February 28, 2011. The study cohort comprised 48 patients with cardioembolic stroke (CES), 151 with non-CES infarct, 54 with intracerebral hemorrhage (ICH), 43 with ruptured intracranial aneurysm (RIA), and 97 with unruptured intracranial aneurysm (UIA). Cultured SM was identified as Cnm-positive when the corresponding gene was positive. The results were compared with those from 79 healthy volunteers. Relationships between Cnm-positive SM and known risk factors, including hypertension, diabetes, hyperlipidemia, smoking, and alcohol consumption, were analyzed.

RESULTS

A statistically significant high Cnm-positive rate was observed in patients with CES, non-CES infarct, ICH, and RIA (P = 0.002, 0.039, 0.013, and 0.009, respectively). There were no relationships between Cnm-positive SM and known risk factors.

CONCLUSIONS

Specific types of oral SM can be a risk factor for cardioembolic infarct, intracerebral hemorrhage, and intracranial aneurysm rupture. Further study is needed.

Longitudinal comparison of Streptococcus mutans-induced aggravation of non-alcoholic steatohepatitis in mice

Background: We previously reported that intravenous administration of Streptococcus mutans strain TW871 caused typical non-alcoholic steatohepatitis (NASH)-like findings in a high-fat diet (HFD) mouse model at 16 weeks after initiating the experiment.

Objective: The purpose of the present study was to analyse mice administered S. mutans TW871 fed a HFD for various periods of time.

Methods: First, 6-week-old C57BL/6J mice were fed an HFD for 4 weeks, then TW871 (1 × 10⁷ CFU) or phosphate-buffered saline (PBS) were intravenously administered. Mice were euthanized 12, 16, 20, and 48 weeks after starting the experiment, and conventional clinical and histopathological evaluations were performed.

Results: Typical NASH-like findings were not identified in the mice at 12 weeks, while they were observed in the TW871 group at 16 weeks, and the severity of NASH symptoms were increased at 20 weeks. Furthermore, signs of severe NASH were also observed at 48 weeks. In contrast, in the PBS-administered group, the NASH findings were identified only at 48 weeks and no typical NASH features were observed at 12, 16, or 20 weeks.

Conclusion: These results suggest that intravenous administration of a specific S. mutans strain aggravates NASH in a time-dependent manner in the mice in contrast to mice without S. mutans exposure.

Comprehensive assessment of the impact of life habits on sleep disturbance, chronotype, and daytime sleepiness among high-school students

OBJECTIVE

Sleep affects adolescents in various ways. However, the effects of multiple factors on sleep hygiene remain unclear. A comprehensive assessment of the effects of life habits on sleep in high-school students was conducted.

METHODS

A cross-sectional survey of 344 high school students (age range 15-17; 171 boys, 173 girls) in Tokyo, Japan was conducted in 2015. Complete responses were provided by 294 students. Demographic variables, Pittsburgh Sleep Quality Index (PSQI), diurnal type scale, Pediatric Daytime Sleepiness Scale (PDSS), and life habits such as dinnertime, viewing electronic displays, caffeine intake, sunlight in the morning, and the brightness of the room in the night were asked.

RESULTS

The mean scores were PSQI: 5.9 (±2.3), PDSS: 19.0 (±5.8), and the diurnal type scale: 16.7 (±3.4). Using an electronic display in bed (OR = 3.01; (95%CI) 1.24-7.30), caffeine intake at night always (OR = 2.22; 1.01-4.90), and waking up before dawn (OR = 3.25; 1.34-7.88) were significantly associated with sleep disturbance. Irregular timing of the evening meal (OR = 2.06; 1.10-3.84) and display viewing within 2 h before bedtime (OR = 2.50; 1.01-6.18) or in bed (OR = 3.60; 1.41-9.21) were significantly associated with excessive daytime sleepiness. Using an electronic display within 2 h before bedtime (OR = 2.64; 1.10-6.38) or in bed (OR = 3.50; 1.40-8.76) and a living room which is bright at night (OR = 1.89; 1.06-3.36) were significantly associated with eveningness.

CONCLUSION

Each type of sleep-related problem had its own associated life habit factors.

Long-Term Outcome of Aortic Root Remodeling for Patients With and Without Acute Aortic Dissection

BACKGROUND

Valve-preserving aortic surgery is increasingly used in acute aortic dissection type A (AADA). The object of this study was to compare the long-term results of aortic root remodeling (remodeling) for patients with and without AADA.Methods and Results:Between October 1995 and December 2013, 776 patients underwent valve-preserving root replacement, of whom 59 patients with AADA (<2 weeks from onset, 56±16 years, 48 male) underwent remodeling (the remodeling-group); 7 patients had bicuspid anatomy (12%), 3 had Marfan syndrome (5%), and 1 had undergone previous cardiac surgery (2%). For this analysis the control group of patients who underwent remodeling for stable aneurysm (n=59) was generated using a propensity score matching. The long-term outcomes regarding survival and reoperation on the aortic valve were compared between the 2 groups. Pre- and intraoperative patients' characteristics were comparable between groups. Early death was 7% in the AADA group and 3% in the control group (P=0.40). Actuarial survival at 10 years of the AADA group (72±6%) was insignificantly lower than that of the control group (83±5%) (P=0.16). Freedom from reoperation at 10 years was similar (AADA group: 98±2%, control group: 97±3%, P=0.99). Multivariable Cox's proportional hazards model could not identify an independent predictor for late reoperation but advanced age for late death.

CONCLUSIONS

Long-term stability of remodeling was comparable between patients with and without AADA.

Pathological Quantification of Carotid Artery Plaque Instability in Patients Undergoing Carotid Endarterectomy

BACKGROUND

Unstable atherosclerotic carotid plaques cause cerebral thromboemboli and ischemic events. However, this instability has not been pathologically quantified, so we sought to quantify it in patients undergoing carotid endarterectomy (CEA).Methods and Results:Carotid plaques were collected during CEA from 67 symptomatic and 15 asymptomatic patients between May 2015 and August 2016. The specimens were stained with hematoxylin-eosin and elastica-Masson. Immunohistochemistry was performed using an endothelial-specific antibody to CD31, CD34 and PDGFRβ. The histopathological characteristics of the plaques were studied. By multiple-variable logistic regression analysis, plaque instability correlated with the presence of plaque rupture [odds ratio (OR), 9.75; P=0.013], minimum fibrous cap thickness (OR per 10 μm 0.70; P=0.025), presence of microcalcifications in the fibrous cap (OR 7.82; P=0.022) and intraplaque microvessels (OR 1.91; P=0.043). Receiver-operating characteristics analyses showed that these factors combined into a single score diagnosed symptomatic carotid plaques in patients with carotid artery stenosis with a high level of accuracy (area under the curve 0.92; 95% confidence interval 0.85-0.99 vs. asymptomatic).

CONCLUSIONS

This analysis of carotid plaque instability strongly suggested that the diagnostic scoring of carotid plaque instability improves the understanding and treatment of carotid artery disease in patients undergoing CEA.

The in vivo Inhibition of Oral Biofilm Accumulation and Streptococcus mutans by Ceramic Water

Combustion-synthesized titanium carbide ceramics uniformly disperse silver, producing silver ions and hydroxyl radicals in water. This generates antimicrobial activity against various bacteria. One such bacterium is Streptococcus mutans, a gram-positive anaerobic bacterium known as a major pathogen of dental caries. In this study, we analyzed the inhibition of oral biofilms and S. mutans by ceramic water in in vitro and human studies. S. mutans strains showed significantly lower antimicrobial and sucrose-dependent adhesion activity in the presence of ceramic powder compared with untreated culture medium. Confocal microscopy revealed that S. mutans biofilm structures with ceramic powder were thin and coarse. Twenty-seven volunteers (13 males, 14 females; 18-37 years old, mean 25.2 years) were enrolled for subsequent studies. After each meal, one group was asked to rinse with ceramic water while the other rinsed with untreated water for 1 week. After 1 week, the rinsing contents were switched between the groups and the same protocol was followed for an additional week. After rinsing with ceramic water, the average plaque score was 43.0 ± 3.7, which was significantly lower than the baseline value (74.1 ± 5.7, p < 0.001). However, no significant difference was observed when rinsing with untreated water. In addition, the total number of S. mutans in saliva was significantly reduced after rinsing with ceramic water compared with untreated water (p < 0.05). These results suggest that ceramic water possesses antimicrobial activity against S. mutans and inhibits biofilm formation. Rinsing with ceramic water can also inhibit dental plaque formation and S. mutans colonization in humans.

Genetic Mapping of the Absence of Third Molars in EL Mice to Chromosome 3

We noted the absence of all 4 third molars (M3) in Epilepsy-Like disorder (EL) mice, an animal model for the study of epilepsy. This study was conducted to identify the major candidate chromosome and to detect the region that included the candidate gene causing the absence of M3 in EL mice. Linkage analysis was performed on genetic crosses of EL mice and MSM ( Mus musculus molossinus) strain mice, which had a normal complement of teeth. Genome-wide screening by individual genotyping of F2intercross mice identified mouse chromosome 3 as one of the candidate chromosomes. Based on high linkage scores in detailed genotyping of F2intercross and N2backcross mice, the candidate locus for the absence of M3 in EL mice was mapped on the middle of chromosome 3.

Contributions of Streptococcus mutans Cnm and PA antigens to aggravation of non-alcoholic steatohepatitis in mice

Streptococcus mutans, a major pathogen of dental caries, can cause infective endocarditis after invading the bloodstream. Recently, intravenous administration of specific S. mutans strains was shown to aggravate non-alcoholic steatohepatitis (NASH) in a mouse model fed a high-fat diet. Here, we investigated the mechanism of this aggravation in a NASH mouse model by focusing on the S. mutans cell surface collagen-binding protein (Cnm) and the 190-kDa protein antigen (PA). Mice that were intravenously administered a S. mutans strain with a defect in Cnm (TW871CND) or PA (TW871PD) did not show clinical or histopathological signs of NASH aggravation, in contrast to those administered the parent strain TW871. The immunochemical analyses demonstrated higher levels of interferon-γ and metallothionein expression in the TW871 group than in the TW871CND and TW871PD groups. Analysis of bacterial affinity to cultured hepatic cells in the presence of unsaturated fatty acids revealed that the incorporation rate of TW871 was significantly higher than those of TW871CND and TW871PD. Together, our results suggest that Cnm and PA are important cell surface proteins for the NASH aggravation caused by S. mutans adhesion and affinity for hepatic cells.

A specific Streptococcus mutans strain aggravates non-alcoholic fatty liver disease

OBJECTIVE

Streptococcus mutans, a major dental caries pathogen, has shown to be associated with the aggravation of cerebral hemorrhage and inflammatory bowel diseases. In this study, we evaluated the effects ofS. mutans on the development of non-alcoholic steatohepatitis (NASH) in a mouse model.

MATERIALS AND METHODS

Streptococcus mutans oral strain MT8148 (serotype c) and a blood isolate TW871 (k) were used. C57BL/6J mice (6 weeks old)were fed a high-fat diet for 4 weeks; the test strains or phosphate-buffered saline was then intravenously administered. Mice were euthanized after 8 or 12 weeks. Whole body, extirpated liver, and visceral fat weights were determined, and histopathological evaluations of the liver specimens were performed.

RESULTS

Mice infected with TW871 showed significantly greater body and liver weights than those administered MT8148 or phosphate-buffered saline. Histopathological analyses revealed prominent infiltration of inflammatory cells and adipocellular deposition in livers extirpated 8 weeks after an infection with TW871; fibrosis was also observed in livers extirpated after 12 weeks.

CONCLUSION

These results suggest that a specific strain of S. mutans could induce NASH.

Control of the wetting properties of ^{4}He crystals in superfluid

To investigate whether it is possible to control the wetting of ^{4}He crystals on a wall in superfluid, the contact angles of ^{4}He crystals were measured on rough and smooth walls at very low temperatures. A rough wall was prepared in a simple manner in which a commercially available coating agent for car mirrors, which makes the glass surface superhydrophobic, was used to coat a glass plate. The contact angles of ^{4}He crystals were increased by approximately 10^{∘} on the rough wall coated with the agent. Therefore, the increase in the repellency of ^{4}He crystals in superfluid was demonstrated to be possible on a very rough surface. The enhancement of the contact angles and a scanning electron microscopy image of the coated surface both suggest that a Cassie-Baxter state of ^{4}He crystals was realized on the surface; the crystals did not have full contact with the wall, but entrapped superfluid was present beneath the crystals in the hollow parts of the rough wall.

Abstract WP220: The Association Between Collagen-binding Protein of Streptococcus Mutans and Deep Microbleeds

Introduction: Poor oral hygiene had been recognized as a vascular risk factor. Recently, we showed that cnm gene positive Streptococcus mutans (cnm-positive S.mutans) encoding collagen-binding protein (CBP) was associated with intracerebral hemorrhage (ICH). Deep cerebral microbleeds (CMBs), a biomarker of hemorrhagic small vessel disease, is also associated with cnm-positive S.mutans in a population cohort study.

Hypothesis: In this study, we aim to ascertain the correlation in acute stroke setting and investigated whether other factors, collagen binding activities of each S.mutans strain’s CBP or inflammatory markers, effects in the correlation.

Methods: We enrolled 99 acute stroke patients between February and August 2014. S.mutans was isolated from saliva, and cnm-gene was screened using PCR technique and collagen binding activities was evaluated using type I collagen assay. CMBs were evaluated on T2* gradient-recalled echo MRI.

Result: 67 subjects with ischemic stroke, 5 with transient ischemic attack, and 27 with ICH were included. The presence of cnm-positive S. mutans was significantly associated with ICH [odds ratio vs. ischemic stroke, 3.8; 95% CI, 1.06-13.8], increased number of deep CMBs [median (IQR), 3 (2-9) vs. 0 (0-1), p=0.0002], and fibrinogen [361 (336-459) vs. 320 (274-365) mg/dl, p=0.01]. The relative ratio for number of deep CMBs, cnm-positive S.mutans was 2.2 [95%CI 1.1-4.7] after adjustment of age, sex, systolic blood pressure and creatinine clearance. In subjects positive for S. mutans, collagen binding activity was positively correlated with the number of deep CMBs [γ=0.054; R2, 0.405; p<0.0001].

Conclusions: In acute stroke setting, we ascertained that cnm-positive S.mutans is independently associated with deep CMBs and ICH, and inflammation may have a mechanistic link.

Interactions among Collective Spectators Facilitate Eyeblink Synchronization

Whereas the entrainment of movements and aspirations among audience members has been known as a basis of collective excitement in the theater, the role of the entrainment of cognitive processes among audience members is still unclear. In the current study, temporal patterns of the audience's attention were observed using eyeblink responses. To determine the effect of interactions among audience members on cognitive entrainment, as well as its direction (attractive or repulsive), the eyeblink synchronization of the following two groups were compared: (1) the experimental condition, where the audience members (seven frequent viewers and seven first-time viewers) viewed live performances in situ, and (2) the control condition, where the audience members (15 frequent viewers and 15 first-time viewers) viewed videotaped performances in individual experimental settings (results reported in previous study.) The results of this study demonstrated that the mean values of a measure of asynchrony (i.e., D interval) were much lower for the experimental condition than for the control condition. Frequent viewers had a moderate attractive effect that increased as the story progressed, while a strong attractive effect was observed throughout the story for first-time viewers. The attractive effect of interactions among a group of spectators was discussed from the viewpoint of cognitive and somatic entrainment in live performances.

Relationship between Cnm-positive Streptococcus mutans and cerebral microbleeds in humans

OBJECTIVE

Cerebral hemorrhage has been shown to occur in animals experimentally infected with Streptococcus mutans carrying the collagen-binding Cnm gene. However, the relationship between cerebral microbleeds and oral hygiene, with a focus on Cnm gene-positive S. mutans infection, remains unclear.

MATERIAL AND METHODS

One hundred and thirty-nine subjects participated. The presence or absence of Cnm-positive S. mutans and its collagen-binding activity were investigated using saliva samples, and relationship with cerebral microbleeds detected on MRI investigated, including clinical information and oral parameters.

RESULTS

Fifty-one subjects were identified as Cnm-positive S. mutans carriers (36.7%), with cerebral microbleeds being detected in 43 (30.9%). A significantly larger number of subjects carried Cnm-positive S. mutans in the cerebral microbleeds (+) group. S. mutans with Cnm collagen-binding ability was detected in 39 (28.1%) of all subjects, and the adjusted odds ratio for cerebral microbleeds in the Cnm-positive group was 14.4. Regarding the presence of cerebral microbleeds, no significant differences were noted in the number of remaining teeth, dental caries, or in classic arteriosclerosis risk factors.

CONCLUSIONS

The occurrence of cerebral microbleeds was higher in subjects carrying Cnm-positive S. mutans, indicating that the presence of Cnm-positive S. mutans increases cerebral microbleeds, and is an independent risk for the development of cerebrovascular disorders.

Emotionally excited eyeblink-rate variability predicts an experience of transportation into the narrative world

Collective spectator communications such as oral presentations, movies, and storytelling performances are ubiquitous in human culture. This study investigated the effects of past viewing experiences and differences in expressive performance on an audience’s transportive experience into a created world of a storytelling performance. In the experiment, 60 participants (mean age = 34.12 years, SD = 13.18 years, range 18–63 years) were assigned to watch one of two videotaped performances that were played (1) in an orthodox way for frequent viewers and (2) in a modified way aimed at easier comprehension for first-time viewers. Eyeblink synchronization among participants was quantified by employing distance-based measurements of spike trains, D^spike and D^interval (Victor and Purpura, 1997). The results indicated that even non-familiar participants’ eyeblinks were synchronized as the story progressed and that the effect of the viewing experience on transportation was weak. Rather, the results of a multiple regression analysis demonstrated that the degrees of transportation could be predicted by a retrospectively reported humor experience and higher real-time variability (i.e., logarithmic transformed SD) of inter blink intervals during a performance viewing. The results are discussed from the viewpoint in which the extent of eyeblink synchronization and eyeblink-rate variability acts as an index of the inner experience of audience members.

Spin-dependent acoustic response in the nonunitary A1 and A2 phases of superfluid 3He under high magnetic fields

The transverse acoustic impedance of superfluid ^{3}He was measured in the A1 and A2 phases up to 13 T to investigate the surface states in nonunitary superfluids. The temperature dependence of the impedance was much larger in the A1 phase than in the A2 phase. This nonsymmetric behavior indicates that momentum exchange with walls for spin-down surface states is quite different from that for spin-up surface states. The spin-dependent response might be a reflection of an essential feature of the nonunitary states where gap amplitudes depend on spin states. Weak-coupling theories ignore any spin-dependent processes and do not account for the nonsymmetric behavior.

Variation of expression defects in cell surface 190-kDa protein antigen of Streptococcus mutans

Streptococcus mutans, which consists of four serotypes, c, e, f, and k, possesses a 190-kDa cell surface protein antigen (PA) for initial tooth adhesion. We used Western blot analysis to determine PA expression in 750 S. mutans isolates from 150 subjects and found a significantly higher prevalence of the isolates with PA expression defects in serotypes f and k compared to serotypes c and e. Moreover, the defect patterns could be classified into three types; no PA expression on whole bacterial cells and in their supernatant samples (Type N1), PA expression mainly seen in supernatant samples (Type N2), and only low expression of PA in the samples of whole bacterial cells (Type W). The underlying reasons for the defects were mutations in the gene encoding PA as well as in the transcriptional processing of this gene for Type N1, defects in the sortase gene for Type N2, and low mRNA expression of PA for Type W. Since cellular hydrophobicity and phagocytosis susceptibility of the PA-defective isolates were significantly lower than those of the normal expression isolates, the potential implication of such defective isolates in systemic diseases involving bacteremia other than dental caries was suggested. Additionally, multilocus sequence typing was utilized to characterize S. mutans clones that represented a proportion of isolates with PA defects of 65-100%. Therefore, we described the molecular basis for variation defects in PA expression of S. mutans. Furthermore, we also emphasized the strong association between PA expression defects and serotypes f and k as well as the clonal relationships among these isolates.