A Synthetic Small Molecule, LGM2605: A Promising Modulator of Increased Pro-Inflammatory Cytokine and Osteoclast Differentiation by Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin.

Our research explores the interplay between Aggregatibacter actinomycetemcomitans (Aa) cytolethal distending toxin (Cdt) and the host's inflammatory response in molar/incisor pattern periodontitis (MIPP). Cdt disrupts phosphatidylinositol-3,4,5-triphosphate (PIP3) signaling, influencing cytokine expression through canonical and non-canonical inflammasome activation as well as nuclear factor-κB (NF-κB) activation, leading to inflammation in MIPP. THP-1 differentiated macrophages (TDMs) exposed to Cdt exhibited an upregulation of pro-inflammatory genes and subsequent cytokine release. We analyzed the ability of a small molecule therapeutic, LGM2605, known for its anti-inflammatory properties, to reduce pro-inflammatory gene expression and cytokine release in Cdt-exposed and Aa-inoculated TDMs. LGM2605's mechanism of action involves inhibiting NF-κB while activating the Nrf2-transcription factor and antioxidants. Herein, we show that this small molecule therapeutic mitigates Cdt-induced pro-inflammatory cytokine expression and secretion. Our study also further defines Cdt's impact on osteoclast differentiation and maturation in MIPP. Cdt promotes increased TRAP+ cells, indicating heightened osteoclast differentiation, specific to Cdt's phosphatase activity. Cathepsin K levels rise during this process, reflecting changes in TRAP distribution between control and Cdt-treated cells. Exploring LGM2605's effect on Cdt-induced osteoclast differentiation and maturation, we found TRAP+ cells significantly reduced with LGM2605 treatment compared to Cdt alone. Upon LGM2605 treatment, immunocytochemistry revealed a decreased TRAP intensity and number of multinucleated cells. Moreover, immunoblotting showed reduced TRAP and cathepsin K levels, suggesting LGM2605's potential to curb osteoclast differentiation and maturation by modulating inflammatory cytokines, possibly involving Nrf2 activation. In summary, our research reveals the intricate connections between Cdt, pro-inflammatory cytokines, and osteoclast differentiation, offering novel therapeutic possibilities for managing these conditions.

Corrigendum: Aggregatibacter actinomycetemcomitans cytolethal distending toxin modulates host phagocytic function.

[This corrects the article DOI: 10.3389/fcimb.2023.1220089.].

A Modern Approach to Treat Molar/Incisor Pattern Periodontitis-Review.

Molar-incisor pattern periodontitis (MIPP) is a severe form of periodontal disease characterized by rapid attachment loss and bone destruction affecting the molars and incisors. Formerly referred to as aggressive periodontitis, the terminology for this condition was revised after the 2017 workshop on the classification of periodontal and peri-implant diseases and conditions. Despite the modification in nomenclature, the treatment strategies for MIPP remain a critical area of investigation. The core principles of MIPP treatment involve controlling local and systemic risk factors, managing inflammation, and arresting disease progression. Traditional non-surgical periodontal therapy, including scaling and root planing, is commonly employed as an initial step together with the prescription of antibiotics. Surgical intervention may be necessary to address the severe attachment loss. Surgical techniques like resective and regenerative procedures can aid in achieving periodontal health and improving esthetic outcomes. This review article aims to provide an overview of the current understanding and advancements in the treatment modalities of MIPP. Through an extensive analysis of the existing literature, we discuss various modern therapeutic approaches that have been explored for managing this challenging periodontal condition.

Aggregatibacter actinomycetemcomitans cytolethal distending toxin modulates host phagocytic function.

Cytolethal distending toxins (Cdt) are a family of toxins produced by several human pathogens which infect mucocutaneous tissue and induce inflammatory disease. Human macrophages exposed to Aggregatibacter actinomycetemcomitans (Aa) Cdt respond through canonical and non-canonical inflammasome activation to stimulate cytokine release. The inflammatory response is dependent on PI3K signaling blockade via the toxin's phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase activity; converting PIP3 to phosphatidylinsoitol-3,4-diphosphate (PI3,4P2) thereby depleting PIP3 pools. Phosphoinositides, also play a critical role in phagosome trafficking, serving as binding domains for effector proteins during phagosome maturation and subsequent fusion with lysosomes. We now demonstrate that AaCdt manipulates the phosphoinositide (PI) pools of phagosome membranes and alters Rab5 association. Exposure of macrophages to AaCdt slowed phagosome maturation and decreased phago-lysosome formation, thereby compromising macrophage phagocytic function. Moreover, macrophages exposed to Cdt showed decreased bactericidal capacity leading to increase in Aggregatibacter actinomycetemcomitans survival. Thus, Cdt may contribute to increased susceptibility to bacterial infection. These studies uncover an underexplored aspect of Cdt function and provide new insight into the virulence potential of Cdt in mediating the pathogenesis of disease caused by Cdt-producing organisms such as Aa.

Estimation and Co-Relation of the Neutrophil Count and Neutrophil Chemotaxis in Patients With Gingivitis, Chronic Periodontitis, and Localized Aggressive Periodontitis Compared With Healthy Controls.

INTRODUCTION: Neutrophils are the most plentiful WBCs found in human blood. They are the first cells to respond to wounds and foreign invaders in the human body. They help the body fight infections. The neutrophil count may be used to check for infections, inflammation, or any other underlying conditions. The lower the neutrophil count, the higher the infection risk. Chemotaxis is the ability of the body cells to move in a specific direction as a response to a chemical stimulus. Neutrophil chemotaxis, a feature of the innate immune response, is the directed migration of neutrophils from one site in the body to another to provide effector functions. The present study was aimed at estimating and co-relating the neutrophil count and neutrophil chemotaxis in patients who had gingivitis, chronic periodontitis, and localized aggressive periodontitis, and in healthy participants. METHODS: Eighty participants (40 males and 40 females), aged 20-50 years, were included in the study and divided into four groups: Group I: control group with healthy periodontium; Group II: participants with gingivitis; Group III: participants with periodontitis; and Group IV: participants with localized aggressive periodontitis. Blood samples were collected for hematological analysis to evaluate the neutrophil counts and neutrophil chemotaxis. RESULTS: The mean value of neutrophil count (%) was highest in Group IV (72.535) followed by Group III (71.29), Group II (62.13), and least in Group I (58.15). This difference is statistically significant (p < 0.001). On intergroup comparison, a statistically significant difference was noted between all the groups except between Group I and Group II, and between Group III and Group IV. The mean value of neutrophil count and neutrophil chemotaxis assay were found to be statistically significant in all four groups. CONCLUSION: This study shows a positive correlation between neutrophils and periodontal diseases which could be beneficial for further studies.

Anna Karenina and the subgingival microbiome associated with periodontitis.

BACKGROUND: Although localized aggressive periodontitis (LAP), generalized aggressive periodontitis (GAP), and chronic periodontitis (CP) are microbially driven diseases, our inability to separate disease-specific associations from those common to all three forms of periodontitis has hampered biomarker discovery. Therefore, we aimed to map the genomic content of, and the biological pathways encoded by, the microbiomes associated with these clinical phenotypes. We also estimated the extent to which these biomes are governed by the Anna Karenina principle (AKP), which states that eubiotic communities are similar between individuals while disease-associated communities are highly individualized. METHODS: We collected subgingival plaque from 25 periodontally healthy individuals and diseased sites of 59 subjects with stage 3 periodontitis and used shotgun metagenomics to characterize the aggregate of bacterial genes. RESULTS: Beta-dispersion metrics demonstrated that AKP was most evident in CP, followed by GAP and LAP. We discovered broad dysbiotic signatures spanning the three phenotypes, with over-representation of pathways that facilitate life in an oxygen-poor, protein- and heme-rich, pro-oxidant environment and enhance capacity for attachment and biofilm formation. Phenotype-specific indicators were more readily evident in LAP microbiome than GAP or CP. Genes that enable acetate-scavenging lifestyle, utilization of alternative nutritional sources, oxidative and nitrosative stress responses, and siderophore production were unique to LAP. An attenuation of virulence-related functionalities and stress response from LAP to GAP to CP was apparent. We also discovered that clinical phenotypes of disease resolved variance in the microbiome with greater clarity than the newly established grading system. Importantly, we observed that one third of the metagenome of LAP is unique to this phenotype while GAP shares significant functional and taxonomic features with both LAP and CP, suggesting either attenuation of an aggressive disease or an early-onset chronic disease. CONCLUSION: Within the limitations of a small sample size and a cross-sectional study design, the distinctive features of the microbiomes associated with LAP and CP strongly persuade us that these are discrete disease entities, while calling into question whether GAP is a separate disease, or an artifact induced by cross-sectional study designs. Further studies on phenotype-specific microbial genes are warranted to explicate their role in disease etiology. Video Abstract.

Effects of xipayi mouth rinse combined with minocycline on localized aggressive periodontitis' therapeutic effect and the levels of CRP, TNF-α, IL-6 in serum.

BACKGROUND: Localized aggressive periodontitis is rare periodontitis in clinical practice, which often occurs in young adults under 35 years old, seriously affecting patients' quality of life. As a tetracycline antibacterial drug, minocycline is also considered an essential choice to treat periodontal disease. However, few reports focused on the effect of xipayi mouth rinse combined with minocycline on periodontal pathogens. The goal of this study was to investigate the clinical effect of xipayi mouth rinse combined with minocycline in the treatment of localized aggressive periodontitis and its effect on the levels of CRP, TNF-α, and IL-6. METHODS: Ninety-six patients with limited aggressive periodontitis were selected and randomly divided into two groups. Forty-eight patients in the control group were treated with xipayi mouth rinse after primary periodontal treatment. Then, 48 patients in the experimental group were treated with xipayi mouth rinse combined with minocycline after primary periodontal treatment. The periodontal probe was applied to detect periodontal plaque index (PLI), periodontal pocket depth (PD), sulcus bleeding index (SBI), gingival index (GL), and clinical attachment loss (CAL) before and after treatment in both groups of patients. ELISA was used for detecting the expression levels of CRP, TNF-α, and IL-6 in the serum of patients in two groups before and after treatment. We compared the recurrence rates of the two groups after a 1-year follow-up. RESULTS: Compared with the control group, the PLI, PD, SBI, GL, CAL, and total masticatory efficiency of the experimental group were significantly better than those of the control group. The levels of inflammatory factors CRP, TNF-α, and IL-6 were significantly declined, and the total effective rate of treatment was significantly elevated. After follow-up, it was found there was no noticeable difference in the recurrence rate between the two groups. CONCLUSIONS: Xipayi mouth rinse, combined with minocycline in the treatment of localized aggressive periodontitis, can significantly improve the periodontal gingival condition and reduce the level of inflammatory factors. Also, the efficacy of the treatment was significant. This experiment has provided ideas for improving the clinical treatment of patients with localized aggressive periodontitis.

Aggregatibacter, A Low Abundance Pathobiont That Influences Biogeography, Microbial Dysbiosis, and Host Defense Capabilities in Periodontitis: The History of A Bug, And Localization of Disease.

Aggregatibacter actinomycetemcomitans, the focus of this review, was initially proposed as a microbe directly related to a phenotypically distinct form of periodontitis called localized juvenile periodontitis. At the time, it seemed as if specific microbes were implicated as the cause of distinct forms of disease. Over the years, much has changed. The sense that specific microbes relate to distinct forms of disease has been challenged, as has the sense that distinct forms of periodontitis exist. This review consists of two components. The first part is presented as a detective story where we attempt to determine what role, if any, Aggregatibacter plays as a participant in disease. The second part describes landscape ecology in the context of how the host environment shapes the framework of local microbial dysbiosis. We then conjecture as to how the local host response may limit the damage caused by pathobionts. We propose that the host may overcome the constant barrage of a dysbiotic microbiota by confining it to a local tooth site. We conclude speculating that the host response can confine local damage by restricting bacteremic translocation of members of the oral microbiota to distant organs thus constraining morbidity and mortality of the host.

Aggregatibacter actinomycetemcomitans LtxA Hijacks Endocytic Trafficking Pathways in Human Lymphocytes.

Leukotoxin (LtxA), from oral pathogen Aggregatibacter actinomycetemcomitans, is a secreted membrane-damaging protein. LtxA is internalized by ß2 integrin LFA-1 (CD11a/CD18)-expressing leukocytes and ultimately causes cell death; however, toxin localization in the host cell is poorly understood and these studies fill this void. We investigated LtxA trafficking using multi-fluor confocal imaging, flow cytometry and Rab5a knockdown in human T lymphocyte Jurkat cells. Planar lipid bilayers were used to characterize LtxA pore-forming activity at different pHs. Our results demonstrate that the LtxA/LFA-1 complex gains access to the cytosol of Jurkat cells without evidence of plasma membrane damage, utilizing dynamin-dependent and presumably clathrin-independent mechanisms. Upon internalization, LtxA follows the LFA-1 endocytic trafficking pathways, as identified by co-localization experiments with endosomal and lysosomal markers (Rab5, Rab11A, Rab7, and Lamp1) and CD11a. Knockdown of Rab5a resulted in the loss of susceptibility of Jurkat cells to LtxA cytotoxicity, suggesting that late events of LtxA endocytic trafficking are required for toxicity. Toxin trafficking via the degradative endocytic pathway may culminate in the delivery of the protein to lysosomes or its accumulation in Rab11A-dependent recycling endosomes. The ability of LtxA to form pores at acidic pH may result in permeabilization of the endosomal and lysosomal membranes.

Unique etiologic, demographic, and pathologic characteristics of localized aggressive periodontitis support classification as a distinct subcategory of periodontitis.

BACKGROUND: Localized aggressive periodontitis (LAgP) occurs in 2% of African-American adolescents but only 0.15% of white adolescents. First molars and incisors are affected by rapid onset and progression. METHODS: This nonsystematic critical review evaluated published data for LAgP and chronic periodontitis (CP), focusing on potential differences in epidemiology, microbiology, immunology, genetics, and response to therapy. RESULTS: LAgP differs from CP by localization to incisors and first molars, early onset and rapid progression in adolescents and young adults, and a 10-fold higher prevalence in populations of African or Middle Eastern origin, often with strong familial aggregation. The bacterium Aggregatibacter actinomycetemcomitans and hyperresponsive neutrophils are frequently observed. Antibiotic and nonsurgical therapies are highly effective. CONCLUSIONS: LAgP differs in many ways from the far more common CP that affects older adults. The substantial evidence of dissimilarities summarized in this review strongly supports the classification of LAgP as a distinct form of periodontitis. PRACTICAL IMPLICATIONS: Classifying LAgP as a distinct subcategory of periodontitis will encourage future research and does not conflict with the newly proposed "staging and grading" system. The silent onset and rapid progression of LAgP make early diagnosis and frequent follow-up with patients essential for effective treatment.

Generation of a recombinant Aggregatibacter actinomycetemcomitans RTX toxin in Escherichia coli.

A leukotoxin (LtxA) that is produced by Aggregatibacter actinomycetemcomitans (Aa) is an important virulence determinant in an aggressive form of periodontitis in adolescents. Understanding the function of this protein at the molecular level is critical to elucidating its role in the disease process. To accomplish genetic analysis of the protein structure and relating these observations to toxin function, we have developed an E. coli expression system for the generation and rapid purification of LtxA. Cloning the structural toxin gene, ltxA, from Aa strain JP2 under control of T7 promoter-1 of pCDFDuet-1 vector resulted in expression of a 114 KDa protein which could be easily purified by the presence of a carboxy-terminal engineered double hexahistidine (double-His6) tag and was immunologically reactive with an anti-LtxA monoclonal antibody, but was not cytotoxic. Cloning a second gene, ltxC, an acyltransferase gene, into the vector under control of T7 promoter-2, resulted in expression of the biologically active LtxA. The toxin was extracted from E. coli inclusion bodies, purified by immobilized metal affinity chromatography, and refolded by dialysis. When compared by circular dichroism (CD) spectroscopy analysis, acylated recombinant LtxA has a secondary structure consistent with wt LtxA, while variations in α-helical structure of nonacylated LtxA were observed. No modifications in α-helix were found upon the toxin's binding with liposome-incorporated cholesterol. Our results suggest that pure, biologically active recombinant LtxA can be isolated by a one-step affinity chromatography from E. coli. The toxic and structural properties of the recombinant LtxA are similar to its wt counterpart.

Clinical Characteristics of Localized Aggressive Periodontitis in Primary Dentition.

OBJECTIVES: Due to the low prevalence of localized aggressive periodontitis (LAP), clinical characteristics of LAP in primary dentition are derived from a few case reports/series in the literature. The goal of this study was to determine common clinical characteristics such as bone and root resorption patterns, in a series of cases with LAP in primary dentition. We hypothesize these cases present aggressive periodontal bone destruction starting mostly around first primary molars and atypical root resorption patterns. STUDY DESIGN: We have evaluated 33 LAP cases in primary dentition for pattern of bone destruction, root resorption and early exfoliation. RESULTS: Cases evaluated were aged 5-12 (mean=8.7 years). Thirty cases presented more severe bone loss on first than second molars, with relatively fast progression to second molars, altered pattern of root resorption, mostly external (n=16) and early exfoliation of primary teeth due to periodontal bone loss, rather than physiologic root resorption (n=11). CONCLUSIONS: This study showed common clinical characteristics found in LAP in primary molars, including possible initiation on first primary molars and abnormal root resorption patterns. These characteristics are important to be early identified and treated in order to prevent possible progression into the permanent dentition.

Cytokine response patterns to complex biofilms by mononuclear cells discriminate patient disease status and biofilm dysbiosis.

Localized aggressive periodontitis (LAP) is a rare form of periodontal disease with site-specific rapid tissue destruction. A lipopolysaccharide (LPS) hyper-inflammatory response was shown in LAP using peripheral whole blood, although responses to other bacterial surface components or complex oral biofilms have not been evaluated. Peripheral blood mononuclear cells (PBMCs) from 14 LAP patients, 15 healthy siblings (HS), and 13 unrelated healthy controls (HC) were stimulated with: LPS, lipoteichoic acid, or peptidoglycan; intact or sonically dispersed in vitro-grown biofilms from a LAP disease site, a LAP healthy site, or a healthy control site. Cell culture supernatants were assayed for 14 cyto/chemokines. Discriminant function analysis determined cyto/chemokines that discriminate disease status by response patterns to different stimuli. Qualitative differences in the cytokine response pattern among patient groups were observed to intact and dispersed biofilms, yet responses to healthy and diseased biofilms could not be discriminated. Despite an equivalent magnitude of response, LAP-derived PBMCs demonstrated a qualitatively different pattern of response to LPS and dispersed biofilms. PMBCs from each group responded distinctly to stimulation withsubgingival biofilms. Multiple underlying mechanisms related to bacterial-induced inflammatory responses can culminate in LAP disease initiation and/or progression, and biofilm homeostasis could play an important role.

Shifts of subgingival bacterial population after nonsurgical and pharmacological therapy of localized aggressive periodontitis, followed for 1 year by Ion Torrent PGM platform.

The possibility of targeting the hypervariable region V3 of the 16S rRNA gene using Ion Torrent Personal Genome Machine (PGM) could provide a complete analysis of subgingival plaque samples, potentially able to identify microbiological species missed by culture-based methods. A 16-year-old female smoker patient, affected by localized aggressive periodontitis, underwent a full-mouth disinfection protocol and was inserted in a 3-month recall program. Microbiological samples were collected at baseline and at 30, 100, 365 days follow-up and analyzed by Ion Torrent PGM. Capnocytophaga, Fusobacterium, Prevotella, and Treponema were the most represented pathogens at baseline. Nonsurgical treatment and systemic antibiotics drastically lowered the anaerobic species, and their presence remained limited after 100 days, while a consistent recolonization by anaerobic bacteria was detected at 365 days. The patient showed a general improvement of periodontal conditions. Differently from polymerase chain reaction and other microarray techniques, Ion Torrent performs a quantitative analysis of the microbiota, irrespective of the searched species. An accurate definition of the shifts of the bacterial community might help periodontal researchers for a better understanding of the impact of different treatment approaches or in intercepting nonresponsive conditions.

Evaluation of peripheral neutrophil functions in aggressive periodontitis patients and their family members in Indian population: An assessment of neutrophil chemotaxis, phagocytosis, and microbicidal activity.

BACKGROUND: Association of neutrophil function abnormalities with localized aggressive periodontitis (LAP) has been reported in Indian population. There are no published studies on the familial aggregation of aggressive periodontitis (AP) and neutrophil function abnormalities associated with it in Indian population. The present study aimed to assess neutrophil chemotaxis, phagocytosis, and microbicidal activity in AP patients and their family members of Indian origin, who may or may not be suffering from AP. MATERIALS AND METHODS: Eighteen families with a total of 51 individuals (18 probands, 33 family members) were included. Neutrophil chemotaxis was evaluated against an alkali-soluble casein solution using Wilkinson's method. Phagocytosis and microbicidal activity assay were performed using Candida albicans as an indicator organism. STATISTICAL ANALYSIS USED: The magnitude of association between the presence of defective neutrophil function and LAP or GAP was calculated using odds ratio and relative risk. Total incidence of AP, and in particular, LAP in the families attributable to the presence of defective neutrophil function was calculated by attributable risk. RESULTS: The association between depressed neutrophil chemotaxis and presence of AP and LAP or GAP in all the family members (n = 51) was found to be significant (P < 0.05) while that for phagocytic and microbicidal activity were observed to be nonsignificant. CONCLUSION: The results of the present study suggest high incidence of AP (LAP and GAP) within families was associated with depressed neutrophil chemotaxis. High prevalence of depressed neutrophil chemotaxis in the family members (61%) of LAP probands exhibiting depressed chemotaxis suggests that the observed abnormalities in neutrophil functions may also be inherited by the family members.

Nonsyndromic localized aggressive periodontitis of primary dentition: A rare case report.

Periodontitis is an inflammatory disease of the gingiva and tissues of the periodontium. It is characterized by pocket formation and destruction of supporting alveolar bone. Periodontal diseases of aggressive nature are not very common in children. They are usually associated with systemic conditions. The present case report is of a 5-year-old male child who reported with rapid attachment loss and bony defects of the gingiva and supporting structures. His family and medical history gave no contribution for the diagnosis. Blood investigations did not reveal any abnormality. The microbial examination of culture revealed the presence of periodontal pathogen Aggregatibacter actinomycetemcomitans. The treatment objective in the present case was to prevent the further progress of the condition, restore esthetic and function in the child which would psychologically benefit the child.

The JP2 genotype of Aggregatibacter actinomycetemcomitans and marginal periodontitis in the mixed dentition.

AIM: To perform a cross-sectional study on the carrier frequency of JP2 and non-JP2 genotypes of A. actinomycetemcomitans in Moroccan school children and relate the presence of these genotypes to the periodontal status in the mixed dentition. MATERIAL AND METHODS: A plaque sample from 513 children was analysed by PCR. JP2 genotype-positive subjects (n = 46), an equally sized group of non-JP2 genotype-positive subjects, and an A. actinomycetemcomitans-negative group were randomly chosen among the remaining subjects for clinical and radiographic examination. RESULTS: Among 513 children, 46 (9.0%) carried the JP2 genotype and 186 (36.3%) were positive for non-JP2 genotypes, whereas A. actinomycetemcomitans could not be detected in the remaining 281 subjects. Among 75 subjects with mixed dentition and selected for clinical examination, clinical attachment loss (CAL) ≥ 3 mm at two or more periodontal sites on primary teeth was found in the JP2 genotype-positive group only. In total, 6.7% of subjects with primary teeth present showed CAL ≥ 3 mm at two or more sites. CONCLUSIONS: The carrier frequency of the JP2 genotype of A. actinomycetemcomitans was at a comparable level to frequencies previously found in Moroccan adolescent populations. Clinical attachment loss, manifesting already in the primary dentition, was found only in the group of Moroccan children carrying the JP2 genotype of A. actinomycetemcomitans.

Clinical and microbiological characterization of localized aggressive periodontitis: a cohort study.

BACKGROUND: Localized aggressive periodontitis (LAgP) is an infectious periodontal disease which generally affects young people. Recent data suggest the involvement of different bacterial species in different populations. The causative bacterial species in Israel has never been identified despite a high prevalence of LAgP in this population. The objectives of this study were to characterize the bacterial microbiota of periodontal pockets within an Israeli LAgP population who were also clinically assessed. METHODS: Twenty-one LAgP patients (test) and 12 chronic periodontitis patients (control) were examined. Bacterial samples were collected from periodontal pockets and analysed by both culture and polymerase chain reaction techniques. Mann-Whitney U test and chi-square test were used to compare results between the groups. RESULTS: Higher levels of Parvimonas micra (>10(6) ), Aggregatibacter actinomycetemcomitans (>10(5) ), Fusobacterium nucleatum/F. periodonticum (>10(6) ), and Tannerella forsythia (levels of 10(5) to 10(6) bacteria) were detected in the LAgP group compared to the control (p < 0.05), while levels of Porphyromonas gingivalis and Prevotella intermedia were higher in the CP group. CONCLUSIONS: The characteristic periodontal bacterial flora of LAgP patients in Israel is mainly comprised of P. micra, A. actinomycetemcomitans, F. nucleatum/F. periodonticum and T. forsythia. Similar population based studies of each population will improve the quality of treatment of LAgP when individual sampling is not possible.

Antibiotic susceptibility of Aggregatibacter actinomycetemcomitans JP2 in a biofilm.

BACKGROUND: Localized aggressive periodontitis (LAgP) is an inflammatory disease associated with specific bacteria, particularly Aggregatibacter actinomycetemcomitans, which can result in early tooth loss. The bacteria grow as a biofilm known as subgingival plaque. Treatment includes mechanical debridement of the biofilm, often associated with empirical antibiotic treatment. OBJECTIVE: The aims of this study were to test in vitro the sensitivity of A. actinomycetemcomitans JP2 during planktonic and biofilm growth to doxycycline and to the combination of metronidazole and amoxicillin, which are two antibiotic protocols commonly used in clinical practice. DESIGN: Two in vitro biofilm models were used to test the effects of the antibiotics: a static 96-well plate assay was used to investigate the effect of these antibiotics on biofilm formation whilst a flow chamber model was used to examine the effect on established biofilms. RESULTS: Of the antibiotics tested in this model system, doxycycline was most efficacious with a minimal inhibitory concentration (MIC) against planktonic cells of 0.21 mg/L and minimal biofilm inhibitory concentration (MBIC) of 2.10 mg/L. The most commonly prescribed antibiotic regimen, amoxicillin + metronidazole, was much less effective against both planktonic and biofilm cells with an MIC and MBIC of 12.0 mg/L and 20.2 mg/L, respectively. A single treatment of the clinically achievable concentration of 10 mg/L doxycycline to sparse A. actinomycetemcomitans biofilms in the flow chamber model resulted in significant decreases in biofilm thickness, biovolume, and cell viability. Dense A. actinomycetemcomitans biofilms were significantly more resistant to doxycycline treatment. Low concentrations of antibiotics enhanced biofilm formation. CONCLUSION: A. actinomycetemcomitans JP2 homotypic biofilms were more susceptible in vitro to doxycycline than amoxicillin + metronidazole.

Assessment of peripheral neutrophil functions in patients with localized aggressive periodontitis in the Indian population.

BACKGROUND: Localized aggressive periodontitis (LAP) patients exhibit abnormal neutrophil functions to a variety of environmental and host stimuli. The aim of the present study was to evaluate neutrophils chemotaxis, phagocytosis, microbicidal activity and superoxide generation in LAP patients of Indian origin. MATERIALS AND METHODS: Eleven LAP patients and nine healthy subjects were included in the study. Neutrophil chemotaxis was evaluated against an alkali-soluble casein solution using Wilkinson's method. Phagocytosis and microbicidal activity assay were performed using Candida albicans as an indicator organism. Nitrobluetetrazolium (NBT) test was used to assess superoxide generation by neutrophils using E. coli endotoxin. RESULTS: The chemotactic activity and phagocytic and microbicidal activity were observed to be significantly reduced (P < 0.01) in LAP neutrophils. On the contrary, superoxide generation was observed to be significantly increased (P < 0.01) in LAP neutrophils compared with healthy individuals. CONCLUSION: The results of the present study suggest that neutrophil functions, namely chemotaxis, phagocytosis and microbicidal activity, are deficient LAP patients. However, superoxide generation was significantly increased when stimulated by endotoxins, which may explain the tissue damage seen in LAP. These abnormal neutrophil functions may predispose to increased susceptibility for LAP. Further large-scale studies are required in the Indian population to ascertain the cause-and-effect relationship of defective host factors and aggressive periodontitis and to develop treatment strategies for more predictable periodontal treatment outcome.