Localized Juvenile Periodontitis Research Articles

A Comparison between Scaling and Root Planning (SRP), Antibiotic and Diode Laser Application in Treatment of Localized Juvenile Periodontitis (Microscopical Study)

The present study aimed to study different ways for treatment of Localized Juvenile periodontitis, cultural and microscopic results of specimens from base line, appeared the following bacterial strains: Bacteroides gracilis ,Fusobacterium nuclautum, Porphyromonas intermedia, Actinomyces, peptostreptococcus species, eikenella corrodens, streptococcus intermedius, Streptococcus salivaris. Which distribution in 50% gram positive and 50% gram negative. Cultural and microscopical result after ten days of the experimental design appeared significant difference P≥ 0.05, at the SRP group results of microscopic and culturing show Peptostreptoccal species, Prevotella intermedia, Fusobacterium nuclautum, Streptococcus Saliveris. While at the SRP and antibiotic treated group (Doxycyclin 100 mg) the pattern of microbial study appeared the following bacteria: Fusobacterium nucleotum, Peptostreptococcus, Streptococcus salivaris. At the other hand the results of third group SRP and diode Laser appeared no growth of microorganism at all site subjected to Laser 0.8 w, 940 nm for 20 sec after ten days of study.

Епідеміологія і етіопатогенетичні фактори розвитку агресивних форм пародонтиту

The purpose of the work was to study the etiology and main etiopathological factors of the development of aggressive forms of periodontitis based on the analysis of additional pathogenetic aspects of mineral metabolism disorders according to modern literature. Materials and methods. The bibliosemantic method was used to clarify the state of the problem, study the analysis of the results of previous scientific research based on literature sources and electronic resources. Results. Periodontitis is the most widespread disease among all periodontal pathologies (chronic generalized periodontitis occurs in 90% of cases). Until recently, aggressive forms of periodontitis were not given due attention, since according to epidemiological studies by S. Renvert and M. Wikstom (1996), in the general structure of periodontal diseases, aggressive forms of periodontitis occur with a frequency of 5–10%. To understand the mechanisms of the development of aggressive forms of periodontitis, attention is paid to their development in children and adolescents. Clinical and radiological examinations of children and adolescents showed different frequency of aggressive forms of periodontitis (localized juvenile periodontitis and generalized juvenile periodontitis): in the USA – 2.27%, in Denmark – 0.1%, in Finland – 0.1%, in Nigeria – 0.8%, in Brazil – 0.3%, in England – 0.17%, in Chile – 0.32%. Studies have shown that aggressive forms of periodontitis are equally common in children and adolescents, regardless of gender. At the same time, localized juvenile periodontitis is 3 times more common in boys, not the same for girls. A new and rather promising vector of periodontology is the study of the role of juvenile changes in the bone skeleton on the development and course of periodontal diseases. The development of mineral metabolism disorders in aggressive forms of periodontitis in different age groups requires further study, while the data obtained by molecular geneticists become relevant for understanding the possible ways of research. Considering the fact that the jaw bones are a component of the skeleton, the strength of which can be affected by various exogenous and endogenous factors, in particular genetic ones, the main direction of searching for candidate sensitivity genes is conducted among the markers of bone metabolism disorders. Of many candidate genes that determine bone mineral density, the most well-known is the vitamin D receptor gene. Conclusion. The analysis of the available literature showed that the study of the role of mineral and bone metabolism disorders in the emergence and development of aggressive forms of periodontitis has a wide scientific perspective, and obtaining new data on the state of systemic regulatory factors and their effects on the local mechanisms of periodontal tissue damage will allow not only to improve the diagnosis of various forms, but also to increase the effectiveness of the treatment of this pathology

Optical profile: A key determinant of antibacterial efficacy of photodynamic therapy in dentistry

BackgroundPeriodontal disease effects 20–50% of the population worldwide, posing a global health challenge. It has been reported to be more prevalent among adults. Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) is an important organism associated with localized juvenile periodontitis. Photodynamic therapy (PDT) has been widely utilized for the treatment of periodontal disease; however, the effect of laser (light) profile on the antibacterial efficacy of PDT remains to be established. The quantitative measurement of laser profile is required to confirm the in vitro efficacy of PDT. AimIn the present study, a low cost PDT system comprising of six copper tube waveguides (CTW) was developed to provide more uniform irradiation of the culture plate. MethodsThe antibacterial effect of PDT, in combination with 200 μg/mL methylene blue (MB) as photosensitizer and 60 sec of irradiation, was studied on A. actinomycetemcomitans and Streptococcus mutans (S. mutans). In the present case, 660 nm laser guided with unpolished CTW, polished CTW, and optical fiber waveguide (OFW) provided radiant exposure of 0.86, 1.38, and 1.36 J/cm2, respectively, for a 24‐well culture plate. ResultsThe designed PDT system provided antimicrobial efficacy of 98% and 91% for A. actinomycetemcomitans and S. mutans, respectively, which was significantly higher as compared to OFW guided PDT. ConclusionThe results of the study highlighted the importance of laser profile as a key parameter that determines the survival rate of bacteria at the edge of the culture plate. Thus, the dose of PDT at the margin of optical profile is important for antibacterial activity for in vitro evaluation.

Complications of Teeth Affected by Molar-Incisor Malformation and Pathogenesis According to Microbiome Analysis

A molar-incisor malformation (MIM) is a recently reported dental anomaly that causes premature loss of the first molar with severe dentoalveolar infection. However, there has been no research on the pathogenesis yet. The aim of this study was to report the clinical process of MIMs and investigate the pathogenesis by conducting a microbiome analysis. An eight-year-old girl was diagnosed with MIM and after two years, four permanent first molars were sequentially extracted due to severe dentoalveolar infection. We recorded the patient`s clinical progress and collected oral microbiome samples from the extracted teeth with MIM and sound teeth as controls. The sites of microbiome sampling were represented by five habitats in two groups. Group (1) was the perio group: ① supragingival plaque, ② subgingival plaque, and ③ a pical abscess; and group (2) was the endo group: ④ coronal pulp chamber and ⑤ root canal. The perio group was composed predominantly of genera Streptococcus, Veilonella, and Leptotrichia. Spirochetes appeared in one sample from a severe periodontal abscess. Aggregatibacter actinomyces were not identified. In the endo groups, pulp necrosis was observed in all MIM and the genera Peptostreptococcus and Parvimonas predominated. In conclusion, MIM teeth caused localized tooth-related periodontitis with pulp necrosis rather than localized juvenile periodontitis, resulting in a poor prognosis, and timely extraction is highly recommended.

Potential role of diacylglycerol kinases in immune-mediated diseases.

The mechanism promoting exacerbated immune responses in allergy and autoimmunity as well as those blunting the immune control of cancer cells are of primary interest in medicine. Diacylglycerol kinases (DGKs) are key modulators of signal transduction, which blunt diacylglycerol (DAG) signals and produce phosphatidic acid (PA). By modulating lipid second messengers, DGK modulate the activity of downstream signaling proteins, vesicle trafficking and membrane shape. The biological role of the DGK α and ζ isoforms in immune cells differentiation and effector function was subjected to in deep investigations. DGK α and ζ resulted in negatively regulating synergistic way basal and receptor induced DAG signals in T cells as well as leukocytes. In this way, they contributed to keep under control the immune response but also downmodulate immune response against tumors. Alteration in DGKα activity is also implicated in the pathogenesis of genetic perturbations of the immune function such as the X-linked lymphoproliferative disease 1 and localized juvenile periodontitis. These findings suggested a participation of DGK to the pathogenetic mechanisms underlying several immune-mediated diseases and prompted several researches aiming to target DGK with pharmacologic and molecular strategies. Those findings are discussed inhere together with experimental applications in tumors as well as in other immune-mediated diseases such as asthma.

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.

Herpesvirus-bacteria synergistic interaction in periodontitis.

The etiopathogenesis of severe periodontitis includes herpesvirus-bacteria coinfection. This article evaluates the pathogenicity of herpesviruses (cytomegalovirus and Epstein-Barr virus) and periodontopathic bacteria (Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis) and coinfection of these infectious agents in the initiation and progression of periodontitis. Cytomegalovirus and A.actinomycetemcomitans/P. gingivalis exercise synergistic pathogenicity in the development of localized ("aggressive") juvenile periodontitis. Cytomegalovirus and Epstein-Barr virus are associated with P. gingivalis in adult types of periodontitis. Periodontal herpesviruses that enter the general circulation may also contribute to disease development in various organ systems. A 2-way interaction is likely to occur between periodontal herpesviruses and periodontopathic bacteria, with herpesviruses promoting bacterial upgrowth, and bacterial factors reactivating latent herpesviruses. Bacterial-induced gingivitis may facilitate herpesvirus colonization of the periodontium, and herpesvirus infections may impede the antibacterial host defense and alter periodontal cells to predispose for bacterial adherence and invasion. Herpesvirus-bacteria synergistic interactions, are likely to comprise an important pathogenic determinant of aggressive periodontitis. However, mechanistic investigations into the molecular and cellular interaction between periodontal herpesviruses and bacteria are still scarce. Herpesvirus-bacteria coinfection studies may yield significant new discoveries of pathogenic determinants, and drug and vaccine targets to minimize or prevent periodontitis and periodontitis-related systemic diseases.

Avidity of antibody responses to Actinobacillus actinomycetemcomitans in periodontitis.

We designed a study to examine the serum IgG antibody avidity characteristics in: (i) normal subjects (N); (ii) Actinobacillus actinomycetemcomitans-infected adult periodontitis (AP Aa+); (iii) A. actinomycetemcomitans-infected localized juvenile periodontitis (LJP Aa+); and (iv) AP subjects (AP) with various antibody patterns and disease presentation. Although there were significant elevations in antibody levels for AP Aa+ and LJP Aa+ patients compared with AP and normal patients (P < 0.0001), there were no significant differences in the avidity indices (AI). Correlations of antibody levels to avidity revealed that functional activity of the antibody as measured by avidity was independent of antibody levels. Increasing antibody levels correlated with an increase in the number of infected sites, yet there was a trend for A1 to decrease with increased infection. Avidity indices for all patient groups did not appear to show a strong biologic relationship to plaque; however, in AP Aa+ and LJP Aa+ patients there was a generally positive relationship between avidity and bleeding on probing or pocket depth. In AP Aa+ and LJP Aa+ patients, and in AP patients there was a positive relationship of avidity through a threshold of approximately 8 active disease sites. This study hypothesized that antibody avidity to A. actinomycetemcomitans could help to explain the relationship between the active host response and chronic infection with this pathogen. The results provide evidence that both antibody levels and avidity may contribute to the variation in host resistance to infection and disease associated with A. actinomycetemcomitans.

Association between lactoferrin gene polymorphisms and aggressive periodontitis among Taiwanese patients

A dramatic difference in the frequencies of the Lys/Arg single nucleotide polymorphism in the lactoferrin genotype between a small population of patients with localized juvenile periodontitis and healthy subjects has been reported. As the single nucleotide polymorphism could be associated with ethnicity, the present study aimed to investigate the association between polymorphisms of the lactoferrin gene and periodontitis. Sixty-five patients with aggressive periodontitis, 278 with chronic periodontitis and 88 healthy controls were genotyped for the Lys/Arg polymorphism of the lactoferrin gene at position 29 [reference sequence (rs) 1126478] in the N-terminal alpha-helical region. The frequencies of the GG genotype and the G allele were highest in the aggressive periodontitis group, followed by the chronic periodontitis group and then the healthy controls. The frequency of the G allele was significantly higher in aggressive periodontitis and chronic periodontitis groups than in healthy controls (p = 0.0037 and 0.0212). Although the difference of the GG genotype distribution between subjects with chronic periodontitis and healthy controls did not reach significance, the distribution of genotypes between aggressive periodontitis and healthy controls was significantly different. The association of the gene polymorphism and aggressive periodontitis still existed, even after adjusting for age, gender and smoking status by logistic regression analysis (GG/AG+AA: odds ratio = 2.16, 95% confidence interval = 1.09-4.35, p = 0.0287). After the study, subjects were further stratified by their smoking status; the GG genotype was still significantly associated with the risk of aggressive periodontitis in the nonsmoking group (odds ratio = 2.69, p = 0.018). However, there were no statistical differences between chronic periodontitis vs. healthy controls and aggressive periodontitis vs. healthy controls in the smoking group. The present study revealed that the A/G polymorphism in the lactoferrin gene might be associated with aggressive periodontitis. The A allele might reduce the risk of development of aggressive periodontitis in a Taiwanese population. Our results also support the hypothesis that lactoferrin genetic polymorphisms could play a role in the risk for periodontitis separate from the smoking factor. The functionality of this gene's polymorphisms has to be further elucidated.

Bacteroides gingivalis-specific serum IgG and IgA subclass antibodies in periodontal diseases

The level of serum IgM, IgG and IgA antibodies including IgG1, IgG2, IgG3, IgG4, IgA1 and IgA2 subclass-specific antibodies to Bacteroides (Porphyromonas) gingivalis fimbriae and to lipopolysaccharide (LPS) were analysed in patients with different forms of periodontal disease (PD) and control subjects by ELISA. Among PD subjects, sera obtained from adult periodontitis (AP), rapidly progressive periodontitis (RPP) and gingivitis contained high titres of fimbriae-specific IgG antibodies (7500-15,000 ELISA units) followed by IgA (90-700 units) and IgM (30-90 units). In contrast, sera from localized juvenile periodontitis (LJP) subjects exhibited much lower titres of fimbriae-specific IgG (89 +/- 11 units), IgA (31 +/- 5 units) and IgM (17 +/- 3 units) antibodies. A similar response pattern was also seen in sera from normal subjects aged 35-41 years who practice normal oral hygiene, while sera of younger adults (aged 18-24) with superior hygiene did not have any antigen-specific antibodies. Analysis of IgG subclass anti-fimbriae responses revealed that the major response was IgG3 followed by IgG1, IgG2 and IgG4 in AP, RPP and gingivitis. Although lower, a similar pattern of IgG subclass titre was seen in LJP and normal subjects aged 35-41 years. When IgA subclass responses were measured in AP and RPP, higher titres of the fimbriae-specific response were noted with IgA1 when compared with IgA2. However, lower but approximately equal levels of fimbriae-specific IgA1 and IgA2 titres were seen in other PD groups. When anti-B. gingivalis LPS-specific responses were measured, the sera of AP patients contained high levels of IgG antibodies (2265 +/- 224 units) followed by IgA (411 +/- 90 units) and IgM (214 +/- 56 units). Further, IgG anti-LPS responses were mainly IgG2 followed by IgG4, IgG3 and IgG1. For IgA subclass responses, higher titres of anti-LPS-specific antibodies were noted in IgA2 subclass over IgA1. These results showed that higher anti-B. gingivalis antibody responses occur in PD when compared with healthy individuals and protein and lipid-carbohydrate antigens of B. gingivalis induce distinct patterns of antigen-specific IgG and IgA subclass responses.

Interdisciplinary treatment of localized juvenile periodontitis: A new perspective to an old problem

What can be done for a 17-year-old girl with localized juvenile periodontitis, a Class II malocclusion, and flared teeth? Is it possible to regain epithelial attachment and rebuild the bone architecture? Is it possible to achieve good esthetics and occlusion with conventional orthodontic treatment, or is an interdisciplinary approach needed? What sequence should be followed? What is the prognosis for the affected teeth in the long term? Our aim in this article was to review the literature and present a clinical case to shed more light on the subject.

The effect of periodontal flap surgery on Matrix metalloproteinases (MMPs) and Tissue inhibitors of matrix metalloproteinase-1 (TIMP-1) levels in gingival crevicular fluids of periodontitis patients

As we all know, periodontal disease is characterized by inflammation that can lead to periodontal attachment loss and bone destruction and is largely initiated by bacterial plaque. It is now recognized that during active periodontitis, degradation of the collagenous matrices which support the skeletal framework of gingival complex is due in part to matrix metalloproteinase (MMPs) expressed in situ by inflammatory cells(monocytes, macrophages, lymphocytes, polymorphonuclear cells) and resident cells(fibroblasts, epithelial cells, and endothelial cells), and they are thought to be partly responsible for other kinds of diseases as well. MMPs belong to the matrixin family, which is composed of at least 23 related zincdependent endopeptidases that are able to degrade extracellular matrix proteins at a pH close to neutral. And they can be divided into several major subgroups, such as the interstitial collagenases (MMP-1. -8 and -13), the gelatinases (MMP-2 and -9; also called type IV collagenase), the stromelysins(MMP-3, -10 and -11) and the membrane-bound group(MMP-14, -15, -16 and -17). Among them, several MMPs (like MMP-1, 2, 8, 9 and 13) as well as tissue inhibitors of matrix metalloproteinase-1(TIMP-1) are thought to be more strongly related to overwhelming periodontal disease, such as adult periodontitis (AP) and localized juvenile periodontitis(LJP) by previous classification. The purpose of this study is to find out whether specific MMPs(-1, -8, -9, -13) or TIMP -1 are present in periodontitis patients and to determine if there are any significant differences between the amount

Primary immune deficiencies − improving our understanding of their role in immunological disease

Primary immune deficiencies − improving our understanding of their role in immunological disease

Relationship of Actinobacillus actinomycetemcomitans serotype b to aggressive periodontitis: frequency in pure cultured isolates.

To our knowledge, the association of the five serotypes of Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) to the new diagnostic classification scheme defined by the American Academy of Periodontology in 1999 has not yet been described. The goal of this study was to characterize the frequencies of the five serotypes of A. actinomycetemcomitans in A. actinomycetemcomitans isolates from various forms of periodontitis using both old and new diagnostic classifications and to determine the relationships between serotype and age and clinical diagnosis. A total of 345 A. actinomycetemcomitans isolates from 115 A. actinomycetemcomitans culture-positive subjects (mean age 38.0 +/- 18.3 years, 59% female) were collected. Based on the new classifications, 33 subjects had aggressive periodontitis and 82 chronic periodontitis. According to old classifications, there were six prepubertal periodontitis (PPP), 12 localized juvenile periodontitis (LJP), 15 post-localized juvenile periodontitis (PLJP), 28 refractory periodontitis (Ref-P), and 54 adult periodontitis (AP) cases. Serotypes of A. actinomycetemcomitans were determined by an indirect immunofluorescence assay using serotype-specific polyclonal antisera to A. actinomycetemcomitans strains ATCC 29523, ATCC 43728, ATCC 33384, IDH 781 and IDH 1705 (serotype a, b, c, d, and e, respectively). Proportions of serotype b were examined between different diagnostic and age groups with a Z-test for proportions. Most subjects (n = 100, 86.96%) were infected with a single serotype (22 serotype a, 44 serotype b, 30 serotype c, 1 serotype d, and 3 serotype e). There were 11 subjects (9.57%) with two serotypes and two subjects (1.74%) with 3 serotypes. Two individuals had isolates lacking any detectable serotype antigen. Serotype b was the predominant serotype in children under 18 years of age and young adults between 19 to 35 years, although serotype b status was not significantly associated with age. Serotypes d and e were not found in patients under 35 years old. In 62 adult patients, one subject had serotype d and three had serotype e. Serotype b was the most common serotype in aggressive periodontitis (60.61%). The proportion of cases with serotype b was significantly higher in aggressive periodontitis compared to chronic periodontitis (P = 0.031). Other serotypes were not significantly associated with new diagnostic categories. Serotypes d and e were not detected in aggressive periodontitis. The results of this study show that proportions of serotype b of A. actinomycetemcomitans are significantly greater in culture-positive patients with aggressive periodontitis than those with chronic periodontitis.

Normal Cell Surface Expression and Selective Loss of Functions Resulting from Phe110 to Ser and Cys126 to Trp Substitutions in the Formyl Peptide Receptor

The N‐formyl peptide receptor (FPR) is a G protein‐coupled chemoattractant receptor that mediates diverse leukocyte functions when stimulated by bacteria‐derived N‐formyl peptides such as fMet‐Leu‐Phe (fMLF). Impaired neutrophil responsiveness to fMLF parallels increased susceptibility to periodontal microorganisms among patients with localized juvenile periodontitis (LJP). To determine whether the recently identified FPR mutations in LJP patients are responsible for selective loss of receptor‐mediated functions, we prepared and analyzed RBL‐2H3 cells expressing FPR bearing Phe110 to Ser (FPR‐F110S) or Cys‐126 to Trp (FPR‐C126W) replacement as well as a FPR double mutant (FPR‐FSCW). All mutant receptors were expressed normally on the cell surface, but were unable to mediate release of β‐hexosaminidase upon fMLF stimulation. FPR‐C126W effectively mediated fMLF uptake, an indication of receptor‐mediated endocytosis, whereas FPR‐F110S and FSCW exhibited markedly reduced ability to uptake fMLF. Both FPR‐F110S and FPR‐C126W were defective in chemotaxis and displayed reduced Ca2 + mobilization, but mutation at both positions partially restored the ability to respond to fMLF in chemotaxis assay and was nearly normal in Ca2 + mobilization assay. All mutants exhibited diminished accumulation of inositol phosphates. FPR‐F110S displayed a delayed and significantly reduced ERK phosphorylation whereas FPR‐FSCW nearly lost the ability to phosphorylate ERK. Taken together, these results indicate compromised signaling capabilities due to the FPR mutations, but the loss of function is selective and could be partially rescued by mutations at both positions.

One of two human lactoferrin variants exhibits increased antibacterial and transcriptional activation activities and is associated with localized juvenile periodontitis.

The iron-binding protein lactoferrin is a ubiquitous and abundant constituent of human exocrine secretions. Lactoferrin inhibits bacterial growth by sequestering essential iron and also exhibits non-iron-dependent antibacterial, antifungal, antiviral, antitumor, anti-inflammatory, and immunoregulatory activities. All of these non-iron-dependent activities are mediated by the highly charged N terminus of lactoferrin. In this study we characterized a Lys/Arg polymorphism at position 29 in the N-terminal region of human lactoferrin that results from a single nucleotide polymorphism in exon 1 of the human lactoferrin gene. We expressed cDNAs encoding both lactoferrin variants in insect cells and purified the two proteins by ion exchange chromatography. The two lactoferrin variants exhibited nearly identical iron-binding and iron-releasing activities and equivalent bactericidal activities against a strain of the gram-negative bacterium Actinobacillus actinomycetemcomitans. When tested against the gram-positive species Streptococcus mutans and Streptococcus mitis, however, lactoferrin containing Lys at position 29 exhibited significantly greater bactericidal activity than did lactoferrin containing Arg. In addition, the Lys-containing lactoferrin stimulated bovine tracheal epithelial cells to synthesize much higher levels of tracheal antimicrobial peptide mRNA than did the Arg-containing variant. A genotyping assay that distinguished between the two alleles based on a polymorphic EarI restriction site showed that the Lys and Arg alleles had frequencies of 24% and 76%, respectively, among 17 healthy human subjects, and 72% and 28%, respectively, among nine patients with localized juvenile periodontitis. Our findings suggest that these two lactoferrin variants are functionally different and that these differences may contribute to the pathogenesis of localized juvenile periodontitis.

Susceptibilities of different Actinobacillus actinomycetemcomitans strains to lactoperoxidase–iodide–hydrogen peroxide combination and different antibiotics

Actinobacillus actinomycetemcomitans has an important aetiological role in localized juvenile periodontitis and in progressive periodontitis in adults. A. actinomycetemcomitans is found mainly in periodontal pockets but also in whole saliva, a potential transmission medium. It is sensitive to peroxidase–halide systems, but the differences between periodontitis associated clinical isolates and type strains are unclear. The sensitivities of these 2 strain groups to lactoperoxidase (LP)–iodide (I −)–hydrogen peroxide (H 2O 2) combinations were investigated, and the sensitivities were compared with the susceptibilities to four antibiotics. There was great variation between the sensitivities of different strains, but the 2 strain groups responded similarly. The LP (75 μg)–I − (100 nmol)–H 2O 2 (1000 nmol) combination produced a similar degree of inhibition as 2 μg ampicillin. The LP–I − system might be a potential antimicrobial agent against A. actinomycetemcomitans transmission via saliva.

T-cell-receptor gene usage of Actinobacillus actinomycetemcomitans-reactive periodontal CD4+ T cells from localized juvenile periodontitis patients and human peripheral blood leukocyte-reconstituted NOD/SCID mice.

We investigated the variable Valpha and Vbeta gene usage of Actinobacillus actinomycetemcomitans-reactive periodontal CD4+ T cell receptors (TCR) from: (i) four A. actinomycetemcomitans-infected localized juvenile periodontitis (LJP) patients, (ii) four groups of A. actinomycetemcomitans-inoculated NOD/SCID mice engrafted with individual LJP-derived HuPBL and (iii) HuPBL samples of four LJP patients and two healthy control subjects, by quantitative PCR analyses. The results show that: (i) the majority of the TCR genes (82.5% of Valpha and 91.1% of Vbeta) used by periodontal CD4+ T cells in A. actinomycetemcomitans-inoculated HuPBL-engrafted NOD/SCID mice overlap with those used by local periodontal T cells in LJP patients, (ii) although A. actinomycetemcomitans-reactive periodontal CD4+ TCR repertoire is relatively widespread, there are a few dominant genes shared by the LJP patients, suggesting a limited number of antigens or epitopes commonly recognized and (iii) A. actinomycetemcomitans likely lacks superantigenic characteristics. These results suggest A. actinomycetemcomitans-associated human CD4+ T cell repertoire established in HuPBL-NOD/SCID mice provides a useful approach to study specific aspects of immune-parasite interactions in the periodontium.

Monocyte differentiation in localized juvenile periodontitis is skewed toward the dendritic cell phenotype.

Several lines of evidence indicate that the monocytes of subjects with localized juvenile periodontitis (LJP) are functionally distinct from cells of age- and race-matched nonperiodontitis (NP) subjects. Among the abnormalities are the propensity to secrete large amounts of prostaglandin E(2) and the induction of immunoglobulin G2 (IgG2) antibodies. The experiments described here were performed to further characterize the LJP monocytes and to determine if these cells mature differently than NP monocytes. When adherent monocytes from LJP subjects were cultured in the presence of human serum, both macrophages and cells with the morphology of immature monocyte-derived dendritic cells (MDDC) were observed. Within 4 days the prevalence of the immature MDDC was approximately twofold higher in LJP cultures than in NP cultures. In addition to their dendritic morphology, these cells were CD11c(+) and CD14(-) or CD14(low) and stimulated potent autologous mixed leukocyte reactions, consistent with differentiation to the MDDC phenotype. Like LJP monocytes, cultures of MDDC generated with interleukin-4 and granulocyte-macrophage colony-stimulating factor selectively induced IgG2 in cultures of pokeweed mitogen-stimulated NP leukocytes. Together, these data suggest that the monocytes of LJP subjects have a propensity to differentiate into MDDC and that this differentiation may be related to the high levels of IgG2 that are observed in the sera of LJP subjects. As high levels of circulating IgG2 are correlated with less severe disease, the propensity of LJP monocytes to differentiate into MDDC may have important implications for both the host response against oral pathogens and the progression of LJP.

Population structure and genetic diversity of Actinobacillus actinomycetemcomitans strains isolated from localized juvenile periodontitis patients.

The phylogeny of 20 Actinobacillus actinomycetemcomitans strains isolated from patients with localized juvenile periodontitis (LJP) was investigated by using partial sequence analysis of 16S rRNA genes, arbitrarily primed PCR (AP-PCR), and four additional PCR assays that amplified polymorphic regions in the leukotoxin (lkt), cytolethal distending toxin (cdt), major fimbrial subunit (flp-1), and serotype-specific O polysaccharide gene clusters. Our analysis also included four strains isolated from healthy subjects and nine reference strains. We found that A. actinomycetemcomitans strains comprised three major phylogenetic lineages. One lineage consisted of serotype b strains, a second lineage consisted of serotype c strains, and a third lineage consisted of serotype a, d, e, and f strains. 16S rRNA sequences within each lineage were highly conserved (<1% base substitutions), whereas sequences between lineages were exceptionally divergent (1.9 to 5.0% substitutions). Two strains exhibited 16S rRNA sequences that were even more distantly related to those of the three major lineages (2.7 to 6.7% substitutions), indicating that additional minor lineages or variants exist. The distribution of 16S rRNA sequences and lkt, cdt, flp-1, and AP-PCR genotypes was consistent with a clonal population structure, with little evidence of assortative recombination between strains of different serotypes. Strains from all three major lineages were recovered from LJP patients, suggesting that phylogenetically diverse strains of A. actinomycetemcomitans carry pathogenic potential.