Periodontal Disease Bacteria Research Articles

Quantitative investigation of the bacterial content of periodontal abscess samples by real-time PCR

ObjectivesPeriodontal abscesses, which are part of the acute periodontal disease group characterized by the destruction of periodontal tissue with deep periodontal pockets, bleeding on probing, suppuration, and localized pus accumulation, cause rapid destruction of tooth-supporting tissues. This study aimed to evaluate the microbial content of periodontal abscesses by specific and culture-independent qPCR. MethodsThis study was conducted on 30 volunteers diagnosed with periodontal abscesses and presenting with complaints of localized pain, swelling, and tenderness in the gingiva. Genomic DNA was isolated from the samples taken. Escherichia coli bacteria were used for the standard curve created to calculate the prevalence of target bacteria in the total bacterial load. 16S rRNA Universal primers were used to assess the total bacterial load and prevalence. Bacterial counts were analyzed with Spearman's rank correlation coefficients (ρ) matrix. ResultsFrom the analysis of Real-Time PCR, Porphyromonas gingivalis (30, 100%), Prevotella intermedia (30, 100%), and Fusobacterium nucleatum (30, 100%) were detected in all samples. Campylobacter rectus (29, 96.6%), Porphyromonas endodontalis (29, 96.6%), Tannerella forsythia (28, 93.3%), Filifactor alocis (28, 93.3%), and Actinomyces naeslundii (28, 93.3%) were also frequently detected. ConclusionsPeriodontal abscesses were found to be polymicrobial, and not only periodontal pathogens appeared to be associated with the development of periodontal abscesses. The presence, prevalence, and number of Porphyromonas endodontalis and Propionibacterium acnes in the contents of periodontal abscesses were determined for the first time in our study. Further studies are needed to better understand the roles of bacteria in periodontal disease, including abscesses.

Isolation, identification and antibiotic susceptibility of gram-negative anaerobic bacteria in oral cavity

Gram-negative bacteria include more than 20 genera. The most commonly isolated genera are: Bacteriodes spp., Porphiromonas spp., Fusobacterium spp. and Prevotella spp. The following genera were isolated somewhat less frequently: Tanerella spp., Leptotricha spp., Veilonella spp.,Wollinela spp., Selenomonas spp. and Treponema spp. Anaerobic bacteria have an anaerobic type of metabolism and therefore their incubation is significantly longer and more demanding than aerobic bacteria. The genera Prevotella spp., Porphyromonas spp. and Fusobacterium spp. are part of the resident flora of the oral cavity and in unfavorable conditions cause periodontal diseases, and sometimes dentogenic infections and systemic diseases, such as Alzheimer?s disease, cardiovascular diseases, metabolic diseases and inflammatory bowel diseases. The three most important steps for the successful diagnosis of anaerobic bacteria are: proper sampling with avoiding sample contamination, rapid transport of samples to the microbiological laboratory and proper handling of samples. A combination of beta-lactam with the addition of beta-lactamase inhibitors, metronidazole, clindamycin and moxifloxacin is used for treatment for infections caused by anaerobic Gram-negative bacteria. It is important to note that antibiotics should be used only with a clear indication and to choose the right antibiotic in the optimal dose. The aim of this review is to point out the role of Gram-negative anaerobic bacteria in periodontal diseases, and its isolation, identification and antibiotic susceptibility.

Molecular Detection of Porphyromonas gingivalis in COVID-19 Patients

Background:SARS-CoV-2 infection has caused a global pandemic that continues to negatively impact human health. A large group of microbial domains including bacteria co-evolved and interacted in complex molecular pathogenesis along with SARS-CoV-2. Evidence suggests that periodontal disease bacteria are involved in COVID-19, and are associated with chronic inflammatory systemic diseases. This study was performed to investigate the association between bacterial loads of Porphyromonas gingivalis and pathogenesis of SARS-CoV-2 infection. Fifty patients with confirmed COVID-19 by reverse transcriptase-polymerase chain reaction, their age ranges between 20-76 years, and 35 healthy volunteers (matched accordingly with age and sex to the patients) participated in this case control study. Oral hygiene status was determined by the simplified oral hygiene index. Blood and saliva samples were obtained from patients and controls, Porphyromonas gingivalis quantification from extracted DNA of blood and saliva samples performed by means of real-time polymerase chain reaction. The present result revealed that the quantity of salivary Porphyromonas gingivalis was significantly higher (p=0.003) in the patients’ group than in the controls group, while there was no significant difference in the number of bacteria in the blood samples between the two groups. Moreover, the number of bacteria in severe cases was higher than that in moderate and mild with no significant differences, and there was a significant increase in the number of bacteria among patients with poor oral hygiene compared to patients with good oral hygiene. This study demonstrated that the high level of salivary Porphyromonas gingivalis in patients increases in number with disease severity, which may indicate that bacterial infections contribute to the spread of the disease.

Limosilactobacillus (Lactobacillus) fermentum ALAL020, a Probiotic Candidate Bacterium, Produces a Cyclic Dipeptide That Suppresses the Periodontal Pathogens Porphyromonas gingivalis and Prevotella intermedia

Periodontal disease develops as a result of oral microbiota in dysbiosis, followed by the growth of periodontal pathogens such as Porphyromonas gingivalis and Prevotella intermedia. In case of acute symptoms, antibacterial agents and disinfectants are administered, however the appearance of drug-resistant bacteria and allergies cause problems. In recent years, studies on the effects of probiotics have been conducted as an alternative therapy for periodontitis. However, the basic mechanism of the inhibitory effect of probiotic bacteria on periodontal disease has not been clearly elucidated. To clarify the antibacterial mechanism of probiotics against periodontal pathogens, we used Limosilactobacillus (Lactobacillus) fermentum ALAL020, which showed the strongest antibacterial activity against P. gingivalis and P. intermedia among 50 screened lactic acid bacteria strains. The antibacterial substances produced were identified and structurally analyzed. After neutralizing the MRS liquid culture supernatant of ALAL020 strain, the molecular weight (m/z) of the main antibacterial substance separated by gel filtration column chromatography and reverse phase HPLC was 226.131. This low molecular weight compound was analyzed by LC-MS and disclosed the composition formula C11H18O3N2, however the molecular structure remained unknown. Then, structural analysis by NMR revealed C11H18O3N2 as the cyclic dipeptide, “hexahydro-7-hydroxy-3- (2-methylpropyl) pyrrolo [1,2-a] pyrazine-1,4-dion cyclo (Hyp-Leu) “. Based on the results of this analysis, cyclo (Hyp-Leu) was chemically synthesized and the antibacterial activity against P. gingivalis and P. intermedia was measured. The minimum inhibitory concentration (MIC) was 2.5 g/L and the minimum bactericidal concentration (MBC) was shown to be less than 5 g/L. In addition, an in vitro epithelial tissue irritation test at 10 g/L showed no tissue toxicity. So far there are no reports of this peptide being produced by probiotic bacteria. Furthermore, antibacterial activity of this cyclic dipeptide against periodontal disease bacteria has not been confirmed. The results of this study might lead to a comprehensive understanding of the antibacterial mechanism against periodontal disease bacteria in future, and are considered applicable for the prevention of periodontal disease.

Portable Electrochemical DNA Sensors Based on Gene Amplification Reactions to Screen and Identify Pathogen and SNPs.

In this paper, we introduce portable sensors based on genetic measurements that can be used in the field for the diagnosis of infectious diseases and disease risk based on SNPs (single nucleotide polymorphisms). In particular, the sensors are based on electrochemical measurements that can be performed with printed electrodes and small measuring devices. Indicator molecules that can bind to nucleic acid molecules in various ways are already known, and some of these molecules have electrochemical activity. First, we investigated the change in their electrochemical responses in a solution system. As a result, we searched for nucleic acid-binding molecules whose current value changes in the presence of DNA. In addition, when we measured the change in the current value, associated with the amplification of specific genes, such as PCR (polymerase chain reaction) and LAMP (loop-mediated isothermal amplification), we found that the current value decreased with the number of amplifications, indicating that specific genes can be monitored electrochemically. Based on this principle, we showed that pathogenic microorganisms and viruses, such as Salmonella, O157 E. coli, hepatitis B virus, periodontal disease bacteria, antibiotic-resistant bacteria and influenza virus, were able to be measured. The method was also applied to the diagnosis of SNPs, such as ApoE (apolipoprotein E), which is a risk factor for Alzheimer’s disease. Rapid PCR was available with a microfluidic device, and a simple method was also presented with the isothermal amplification of LAMP.

Can negative results of 40 g glucose load test exclude auto-brewery syndrome? Comment to: "Auto-brewery syndrome caused by oral fungi and periodontal disease bacteria" by Takahashi etal. Acute Med Surg. 2021 May 3; 8: e652.

Can negative results of 40 g glucose load test exclude auto-brewery syndrome? Comment to: "Auto-brewery syndrome caused by oral fungi and periodontal disease bacteria" by Takahashi etal. Acute Med Surg. 2021 May 3; 8: e652.

P9‐26: Induction of asthma by sensitization to substances derived from periodontal disease bacteria

P9‐26: Induction of asthma by sensitization to substances derived from periodontal disease bacteria

Effect of Fermented Rice Drink “Amazake” on Patients with Nonalcoholic Fatty Liver Disease and Periodontal Disease: A Pilot Study

The worldwide increase in nonalcoholic fatty liver disease (NAFLD) is a major public health problem. Obesity and diabetes are risk factors for NAFLD and the development of liver fibrosis is a risk factor for liver cancer. Periodontal disease bacteria can also exacerbate NAFLD. We previously reported that amazake, a traditional Japanese fermented food, improves the quality of life (QOL) of patients with liver cirrhosis. In this study, we investigated the effect of amazake intake on NAFLD patients with periodontal disease. Ten patients (mean age: 57.1 ± 19.2 years) consumed 100 g of amazake daily for 60 days. On days 0 and 60, their body mass index (BMI), body fat percentage, serum biochemical parameters, periodontal disease bacteria in saliva, and ten visual analog scales (VASs), namely, sense of abdomen distension, edema, fatigue, muscle cramps, loss of appetite, taste disorder, constipation, diarrhea, depression, and sleep disorder, were measured. For periodontal bacteria, the numbers of six types of bacteria in saliva (Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Aggregatibacter actinomycetemcomitans, Prevotella intermedia, and Fusobacterium necleatum) and P. gingivalis-specific fimA genotype were determined. After 60 days of amazake consumption, eosinophils (p < 0.05), immune reactive insulin (IRI) (p < 0.01), and HOMA-IR (p < 0.05) had significantly increased and tumor necrosis factor α (TNFα) (p < 0.01), muscle cramps (p < 0.05), and depression (p < 0.05) had significantly decreased. All subjective symptoms improved after amazake intake. No change was observed in the periodontal bacteria. In conclusion, amazake significantly decreased TNFα and improved the QOL of the patients with NAFLD and periodontitis. However, caution should be exercised because amazake, which is manufactured using techniques that lead to concentrations of glucose from the saccharification of rice starch, may worsen glucose metabolism in NAFLD patients. Amazake may be an effective food for improving the symptoms of a fatty liver if energy intake is regulated.

The Loop-Mediated Isothermal Amplification Technique in Periodontal Diagnostics: A Systematic Review.

The course of periodontal disease is affected by many factors; however, the most significant are the dysbiotic microflora, showing different pathogenicity levels. Rapid colonization in the subgingival environment can radically change the clinical state of the periodontium. This systematic review aims to present an innovative technique of loop-mediated isothermal amplification for rapid panel identification of bacteria in periodontal diseases. The decisive advantage of the loop-mediated isothermal amplification (LAMP) technique in relation to molecular methods based on the identification of nucleic acids (such as polymerase chain reaction (PCR or qPCR) is the ability to determine more pathogens simultaneously, as well as with higher sensitivity. In comparison with classical microbiological seeding techniques, the use of the LAMP method shortens a few days waiting time to a few minutes, reducing the time necessary to identify the species and determine the number of microorganisms. The LAMP technology requires only a small hardware base; hence it is possible to use it in outpatient settings. The developed technique provides the possibility of almost immediate assessment of periodontal status and, above all, risk assessment of complications during the treatment (uncontrolled spread of inflammation), which can certainly be of key importance in clinical work.

P0398PREVALENCE OF RED COMPLEX OF PERIODONTAL DISEASE BACTERIA IN TONSILS OF IGA NEPHROPATHY PATIENTS

Abstract Background and Aims IgA nephropathy (IgAN) is one of most common primary glomerulonephritis, whose pathogenesis had remained unclear. We had reported that C.rectus and T.denticola, kinds of major periodontal disease bacteria, in tonsils with IgA nephropathy patients were specific to IgAN patients compared with chronic tonsillitis (Nagasawa-Y et al, Plos One, 2014). We also reported C.rectus and S.mutans increased proteinuria synergistically (Misaki-T et al, Nephron, 2018). Red complex of bacteria related with periodontal disease consists of P.gingivalis, T.denticola, and Tannerella forsythia, which has strongest pathogenicity of periodontal disease (Figure 1). But, in this point there were no report of prevalence of red complex of periodontal bacteria in IgA nephropathy. In this study, we evaluated the periodontal disease bacteria including P.gingivalis, T.denticola, and Tannerella forsythia in tonsils of IgAN patients, and the relationship between these periodontal bacteria clinical features in IgAN patients. Method Tonsils were obtained from 23 IgAN patients and 63 chronic tonsillitis patients when the tonsillectomy was operated. mRNAs were extracted from tonsils and the prevalences of P.gingivalis, T.denticola, and Tannerella forsythia were evaluated by RT-PCR using bacteria specific primers. All patients gave the written informed consent which was approved by Hyogo College of medicine. Results Average age was 33+-14 in IgAN patients, and the age in control patients was 27+-7. The average proteinuria in IgAN patietns was 0.9+-1.1g/gcre, and average hematuria was (2+). The prevalence of T.denticola was very low in both groups (0%, 1.6% respectively). The prevalence of P.gingivalis in IgA patients was significantly higher than that in control patients (33% vs 3.2%, respectively, P<0.0001), and the prevalence of Tannerella forsythia in IgAN patients was also significantly higher than that in control (28% vs 6.4%, respectively, P<0.05) which had not been reported (Figure 2). The types of cilia of P.gingivalis (fim A types) were also evaluated. Obviously untypeable of fim A, which is usually minor type, was dominant in IgAN patients. Conclusion Prevalence of red complex of periodontal disease bacteria, especially P.gingivalis, Tannerella forsythia in IgAN patient was higher than that in control. Red complex of periodontal disease bacteria might have some relationship with pathogenesis of IgAN

Characterization and immunostimulatory activity of extracellular vesicles from Filifactor alocis.

Filifactor alocis, a gram-positive, obligate anaerobic rod, is an emerging periodontal pathogen that is frequently isolated from patients with periodontitis, peri-implantitis, and apical periodontitis. Recent studies have shown that extracellular vesicles (EVs) from gram-negative periodontal pathogens, so-called outer membrane vesicles (OMVs), harbor various effector molecules responsible for inducing host inflammatory responses. However, there are no reports of EVs from F. alocis. In this study, we purified and characterized the protein profiles of EVs from F. alocis and investigated their immunostimulatory activity on human monocytic THP-1 and human oral keratinocyte HOK-16B cell lines. Highly pure EVs were obtained from F. alocis using density gradient ultracentrifugation. Nanoparticle tracking analysis and transmission electron microscopy showed that F. alocis EVs were between 50 and 270nm in diameter. Proteome analysis identified 28 proteins, including lipoproteins, autolysins, F. alocis complement inhibitor (FACIN), transporter-related proteins, metabolism-related proteins, and ribosomal proteins. Human cytokine array analysis showed that F. alocis EVs remarkably induced the expression of CCL1, CCL2, MIP-1, CCL5, CXCL1, CXCL10, ICAM-1, IL-1β, IL-1ra, IL-6, IL-8, MIF, SerpinE, and TNF-α in THP-1 cells and CXCL1, G-CSF, GM-CSF, IL-6, and IL-8 in HOK-16B cells. The immunostimulatory activity of F. alocis EVs was similar to that of the whole bacterial cells. Our findings provide new insight into the role of EVs from gram-positive oral bacteria in periodontal diseases.

The Inhibition of Acetylshikonin on Bacteria and its Trypsin-like Protease and Glycosidic Enzyme may be Essential to Conquer Periodontal Ecological Niche

Background/Purposes: The objective of this study was to evaluate the inhibitory effects of acetylshikonin on bacteria in periodontal disease and the activities of trypsin-like protease and glycosidic enzyme of P. gingivalis in vitro. Methods: The inhibition activity of acetylshikonin against bacteria was identified by microbial sensitivity tests of broth dilution method on 96-microwell plate. Trypsin-like protease and glycosidic enzyme activities were measured by a fluorescence spectrophotometer. Results: The minimum inhibitory concentration of acetylshikonin on gram-negative were found to be 0.0625mg/ml, 0.125mg/ml, 0.125mg/ml, 0.25mg/ml, 0.25mg/ml and 0.5mg/ml, for S. intermedius, P. micros, P. acnes, L. acidophilus, A. viscosus and E. lentum respectively. Acetylshikonin showed extensive antibacterial activity against gram-negative bacteria, and it was more active against gram-positive bacteria. The acetylshikonin inhibited the activities of both trypsin-like protease and glycosidic enzyme by 45% and 95% with the final concentration of acetylshikonin from 0.0195 to 2.5 mg/ml. Conclusion: The inhibition activity of acetylshikonin on bacteria and its enzyme of trypsin-like protease and glycosidic may be essential to conquer periodontal ecological niche for treating periodontal disease.

성인의 타액 내 구강세균 검출과 위험요인에 관한 연구

구강질환은 단독 진행만이 아닌 혼합감염증으로 발생하므로 치아우식증 및 치주질환에 관여하는 원인 균주들의 명확한 분석이 필요하다. 이에, 본 연구는 치아우식증 및 치주질환의 원인균으로 잘 알려져 있는 세균을 검출하기 위해 타액을 채취하였다. 성인의 연령, 흡연 및 음주, 질병유무에 따른 구강세균분포 차이를 보고 구강세균의 위험요소를 확인하고자 한다. 본 연구 대상은 20대 이상 65세 미만 성인 120명을 대상으로 2014년 3월 15일 - 5월 10일까지 조사하였다. 타액 내 gDNA를 추출 후 PCR 방법을 이용하여 구강질환의 균 분포도를 확인하였다. 그 결과, S. mutans는 72명, P. intermedia 88명, S. mutans와 P. intermedia 균이 모두 검출된 성인은 54명, 구강세균이 검출되지 않은 성인은 14명으로 나타났다. 구강세균의 위험 요소 결과, 흡연자는 비흡연자에 비해 S. mutans 2.8배, P. intermedia 3.5배 더 높게 나타났다. 음주자는 비음주자에 비해 S. mutans 검출 위험도가 3.3배 더 높은 것으로 나타났으며, 전신질환자는 정상인에 비해 P. intermedia 검출된 위험도가 4.1배 더 높은 것으로 나타났다. 흡연, 음주, 전신질환은 구강 내 세균 검출위험도가 높은 인자임을 확인할 수 있었다. 또한 연령이 증가할수록 치주질환 세균이 더 많이 검출되었으며, 20대는 치아우식증과 치주질환이 공존하는 연령대인 만큼 구강세균의 분포가 더 두드러지게 나타남을 알 수 있었다. 구강세균이 검출된 성인은 치아우식증과 치주질환에 이환될 위험도가 그만큼 높다고 볼 수 있으므로, 구강환경을 청결히하고 정기적인 치과방문을 통해 구강질환을 예방해야 할 것이다. As oral diseases are developed by mixed infections, not by any single element, an accurate analysis of the causative microorganisms related to dental caries and periodontal diseases is required. In this study, saliva was collected from selected adults to determine if the bacteria that are well known as the causative microorganisms of dental caries and periodontal diseases would be detected in their saliva. In addition, this study examined whether there would be any differences among adults according to age, smoking, drinking and presence or absence of diseases in the distribution of oral bacteria to determine the risk factors for oral bacteria. The study subjects were 120 adults ranging in age from 20 to 65 years. The experiment data was collected from March 15, to May 2014. The gDNA was collected from the saliva, and the distribution of bacteria for oral diseases was investigated by PCR. The findings of the study were as follows. S. mutans was detected from 72 adults, and P. intermedia was detected from 88 adults. Both bacteria were detected from 54 adults, and no oral bacteria was detected in 14 adults. An analysis of the risk factors of oral bacteria showed that smokers had a 2.8-fold higher risk of S. mutans than nonsmokers, and the former had a 3.5-fold higher risk of P. intermedia than the latter. Drinkers had a 3.3-fold higher risk of S. mutans than nondrinkers. Patients who suffered from systemic diseases had a 4.1-fold higher risk of P. intermedia than those with no diseases. Therefore, smoking, drinking and systemic diseases are factors that increase the likelihood of oral bacteria detection. More periodontal disease bacteria were detected from older adults, and more oral bacteria were found in adults who were in their 20s, as dental caries and periodontal diseases were more common in this age group. The adults in which oral bacteria were detected are more likely to have dental caries or periodontal diseases, and they should try to keep their mouth cavity clean and make regular visits to a dental clinic to prevent possible oral diseases.

Periodontal disease associated with red complex bacteria in dogs

Red complex bacteria (Treponema denticola, Tannerella forsythia and Porphyromonas gingivalis) play a major role in the aetiology of periodontal disease in humans. This study was designed to evaluate the association of such bacteria with periodontal disease in dogs. Seventy-three subgingival samples taken from dogs ranging from 2 months to 12 years (median age 4 years) were tested for red complex bacteria using a polymerase chain reaction assay. Thirty-six of 73 (49 · 3%) dogs were found to be positive for T. forsythia and P. gingivalis. Dogs with gingivitis or periodontitis were more likely to be infected with T. forsythia and P. gingivalis [odds ratio (OR) 5 · 4 (confidence interval (CI) 1 · 9-15 · 6), P = 0 · 002] than healthy animals. Only 3 (4 · 1%) of 73 samples were positive for red complex bacteria, but the association with periodontal disease was not significant. The results indicate that involvement of red complex bacteria in periodontal disease in dogs is similar to that observed in humans. Only the concurrent presence of T. forsythia and P. gingivalis were correlated to periodontal disease in dogs in this study.

Photodynamic Therapy and its Role in Periodontitis Treatment

Photodynamic therapy is a novel therapeutic approach for eradicating pathogenic bacteria in periodontal disease. Inactivation of microorganisms using photodynamic therapy has been defined as either antimicrobial photodynamic therapy (aPDT), photodynamic antimicrobial chemotherapy (PACT) or photodynamic disinfection. The use of aPDT requires a non-toxic photosensitizer, harmless visible light and oxygen. The photosensitizer binds to targeted bacteria and then can be activated by light of the appropriate wavelength in the presence of oxygen. Photoinactivation of bacteria is tightly restricted to the localization of the photosensitizer, ensuring the protection of distant cells from side-effects. Because of the fact that conventional treatment such as scaling and root planing (SRP) does not completely eliminate periodontal pathogens, especially in deep periodontal pockets, aPDT may be considered to be an alternative therapeutic strategy. This article describes the mechanism of aPDT and novel approaches such as nanoparticles. The aim of the study was to review the literature concerning the assessment of the effectiveness of aPDT in periodontitis treatment. Although studies have not indicated the superiority of aPDT compared to conventional periodontitis treatment, antimicrobial photodynamic treatment has been reported to be effective as an adjunct to conventional therapy to destroy bacteria in sites where there is limited access for mechanical instrumentation.

Determining the Presence of Periodontopathic Virulence Factors in Short-Term Postmortem Alzheimer's Disease Brain Tissue

The aim of this study was to establish a link between periodontal disease and Alzheimer's disease (AD) with a view to identifying the major periodontal disease bacteria (Treponema denticola, Tannerella forsythia, and Porphyromonas gingivalis) and/or bacterial components in brain tissue from 12 h postmortem delay. Our request matched 10 AD cases for tissue from Brains for Dementia Research alongside 10 non-AD age-related controls with similar or greater postmortem interval. We exposed SVGp12, an astrocyte cell line, to culture supernatant containing lipopolysaccharide (LPS) from the putative periodontal bacteria P. gingivalis. The challenged SVGp12 cells and cryosections from AD and control brains were immunolabeled and immunoblotted using a battery of antibodies including the anti-P. gingivalis-specific monoclonal antibody. Immunofluorescence labeling demonstrated the SVGp12 cell line was able to adsorb LPS from culture supernatant on its surface membrane; similar labeling was observed in four out of 10 AD cases. Immunoblotting demonstrated bands corresponding to LPS from P. gingivalis in the SVGp12 cell lysate and in the same four AD brain specimens which were positive when screened by immunofluorescence. All controls remained negative throughout while the same four cases were consistently positive for P. gingivalis LPS (p = 0.029). This study confirms that LPS from periodontal bacteria can access the AD brain during life as labeling in the corresponding controls, with equivalent/longer postmortem interval, was absent. Demonstration of a known chronic oral-pathogen-related virulence factor reaching the human brains suggests an inflammatory role in the existing AD pathology.

Serum antibodies to periodontal pathogens are a risk factor for Alzheimer's disease

Chronic inflammation in periodontal disease has been suggested as a potential risk factor in Alzheimer's disease (AD). The purpose of this study was to examine serum antibody levels to bacteria of periodontal disease in participants who eventually converted to AD compared with the antibody levels in control subjects. Serum samples from 158 participants in the Biologically Resilient Adults in Neurological Studies research program at the University of Kentucky were analyzed for immunoglobulin G antibody levels to seven oral bacteria associated with periodontitis, including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Campylobacter rectus, Treponema denticola, Fusobacterium nucleatum, Tannerella forsythia, and Prevotella intermedia. All 158 participants were cognitively intact at baseline venous blood draw. In all, 81 of the participants developed either mild cognitive impairment (MCI) or AD or both, and 77 controls remained cognitively intact in the years of follow-up. Antibody levels were compared between controls and subjects with AD at baseline draw and after conversion and controls and subjects with MCI at baseline draw and after conversion using the Wilcoxon rank-sum test. AD and MCI participants were not directly compared. Linear regression models were used to adjust for potential confounding. Antibody levels to F nucleatum and P intermedia were significantly increased (α = 0.05) at baseline serum draw in the patients with AD compared with controls. These results remained significant when controlling for baseline age, Mini-Mental State Examination score, and apolipoprotein epsilon 4 status. This study provides initial data that demonstrate elevated antibodies to periodontal disease bacteria in subjects years before cognitive impairment and suggests that periodontal disease could potentially contribute to the risk of AD onset/progression. Additional cohort studies profiling oral clinical presentation with systemic response and AD and prospective studies to evaluate any cause-and-effect association are warranted.

Capacity of photodynamic therapy for microbial reduction in periodontal pockets

Practitioners are not successful in implemented treatments due to the great difficulty in completely removing bacterial deposits and their endotoxins. This study aimed to evaluate the capacity of photodynamic therapy to reduce the numbers of viable bacteria in periodontal pockets. Microbiological samples were collected before and after scaling and after photodynamic therapy. Photodynamic therapy was performed through the insertion of the photosensitizer toluidine blue and Endo PTC into the pocket for 3 min, followed by photosensitization with low-intensity diode of 4 J/cm(2). The results (log(10)) were submitted to a descriptive analysis and a t-test. A reduction of 81.24% in the numbers of bacteria after scaling was observed, as well as 95.90% after photodynamic therapy (P < 0.01). Photodynamic therapy is indicated as an adjuvant treatment to reduce the numbers of viable bacteria in periodontal diseases.

The structure, dynamics, and energetics of protein adsorption—lessons learned from adsorption of statherin to hydroxyapatite

Proteins are found to be involved in interaction with solid surfaces in numerous natural events. Acidic proteins that adsorb to crystal faces of a biomineral to control the growth and morphology of hard tissue are only one example. Deducing the mechanisms of surface recognition exercised by proteins has implications to osteogenesis, pathological calcification and other proteins functions at their adsorbed state. Statherin is an enamel pellicle protein that inhibits hydroxyapatite nucleation and growth, lubricates the enamel surface, and is recognized by oral bacteria in periodontal diseases. Here, we highlight some of the insights we obtained recently using both thermodynamic and solid state NMR measurements to the adsorption process of statherin to hydroxyapatite. We combine macroscopic energy characterization with microscopic structural findings to present our views of protein adsorption mechanisms and the structural changes accompanying it and discuss the implications of these studies to understanding the functions of the protein adsorbed to the enamel surfaces.

Folding of the C-terminal bacterial binding domain in statherin upon adsorption onto hydroxyapatite crystals

Statherin is an enamel pellicle protein that inhibits hydroxyapatite (HAP) nucleation and growth, lubricates the enamel surface, and is recognized by oral bacteria in periodontal diseases. We report here from solid-state NMR measurements that the protein's C-terminal region folds into an alpha-helix upon adsorption to HAP crystals. This region contains the binding sites for bacterial fimbriae that mediate bacterial cell adhesion to the surface of the tooth. The helical segment is shown through long-range distance measurements to fold back onto the intermediate region (residues Y16-P28) defining the global fold of the protein. Statherin, previously shown to be unstructured in solution, undergoes conformation selection on its substrate mineral surface. This surface-induced folding of statherin can be related to its functionality in inhibiting HAP crystal growth and can explain how oral pathogens selectively recognize HAP-bound statherin.