Significance of serum antibody against surface antigens of Actinobacillus actinomycetemcomitans in patients with adult periodontitis

Serotypes of Aggregatibacter actinomycetemcomitans in patients with different ethnic backgrounds

BACKGROUND

The identification of Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) serotypes may add some important information to the understanding of the pathogenetic background of severe periodontal infections. This study compared serotypes of A. actinomycetemcomitans in two groups of periodontal patients with different ethnic backgrounds.

METHODS

A total of 194 patients (96 Germans and 98 Koreans) with aggressive or severe chronic periodontitis participated in the study. Microbiologic analysis of pooled samples from subgingival plaque was performed by using a real-time polymerase chain reaction (PCR) test for A. actinomycetemcomitans. In patients who tested positive for A. actinomycetemcomitans, serotypes (a through f) were determined by nucleic acid-based methods.

RESULTS

The prevalence of patients who tested positive for A. actinomycetemcomitans with the real-time PCR was comparable in both groups (Germans: 27.0%; Koreans: 22.2%). In German patients, the serotypes detected most frequently were b (33.3%), c (25.0%), and a (20.8%), whereas in Korean patients, the serotype distribution was different, with serotypes c (61.9%) and d (19.0%) accounting for >80% of the complete serotype spectrum.

CONCLUSION

Even if the percentage of patients who tested positive for A. actinomycetemcomitans was identical in patients with generalized aggressive and severe chronic periodontitis and different ethnic backgrounds, the distribution of A. actinomycetemcomitans serotypes may exhibit marked differences.

Prevalence and distribution of principal periodontal pathogens worldwide

BACKGROUND

Detailed genetic analysis of bacteria has demonstrated an unanticipated genetic diversity within species, which often reveals evolutionary lineages that are disproportionately associated with infection. There is evidence that some evolutionary lineages of bacteria have adapted to particular ethnic groups.

AIM

This review analyzes to what extent observed differences in periodontal disease prevalence among ethnically or geographically distinct populations may be explained by restricted host adaptation of clones of principal periodontal pathogens.

RESULTS

Carriage rates of several putative periodontal pathogens and particular subsets of these species vary between ethnic groups. Few of these differences can, with the limited information available, be directly related to differences in periodontal disease prevalence. Asian populations are regularly colonized with Actinobacillus actinomycetemcomitans serotype c with questionable pathogenic potential. Conversely, the JP2 clone of A. actinomycetemcomitans has enhanced virulence and causes significantly higher prevalence of aggressive periodontitis in adolescents whose descent can be traced back to the Mediterranean and Western parts of Africa. Some genetically distinct types of Porphyromonas gingivalis are more associated with disease than others, but additional work is required to relate this to clinical differences.

CONCLUSIONS

Studies that take into account differences linked to the genetics of both patients and potential pathogens are likely to give better insight into the aetiology of periodontal diseases.

Destructive periodontitis lesions are determined by the nature of the lymphocytic response

It is now 35 years since Brandtzaeg and Kraus (1965) published their seminal work entitled "Autoimmunity and periodontal disease". Initially, this work led to the concept that destructive periodontitis was a localized hypersensitivity reaction involving immune complex formation within the tissues. In 1970, Ivanyi and Lehner highlighted a possible role for cell-mediated immunity, which stimulated a flurry of activity centered on the role of lymphokines such as osteoclast-activating factor (OAF), macrophage-activating factor (MAF), macrophage migration inhibition factor (MIF), and myriad others. In the late 1970s and early 1980s, attention focused on the role of polymorphonuclear neutrophils, and it was thought that periodontal destruction occurred as a series of acute exacerbations. As well, at this stage doubt was being cast on the concept that there was a neutrophil chemotactic defect in periodontitis patients. Once it was realized that neutrophils were primarily protective and that severe periodontal destruction occurred in the absence of these cells, attention swung back to the role of lymphocytes and in particular the regulatory role of T-cells. By this time in the early 1990s, while the roles of interleukin (IL)-1, prostaglandin (PG) E(2), and metalloproteinases as the destructive mediators in periodontal disease were largely understood, the control and regulation of these cytokines remained controversial. With the widespread acceptance of the Th1/Th2 paradigm, the regulatory role of T-cells became the main focus of attention. Two apparently conflicting theories have emerged. One is based on direct observations of human lesions, while the other is based on animal model experiments and the inability to demonstrate IL-4 mRNA in gingival extracts. As part of the "Controversy" series, this review is intended to stimulate debate and hence may appear in some places provocative. In this context, this review will present the case that destructive periodontitis is due to the nature of the lymphocytic infiltrate and is not due to periodic acute exacerbations, nor is it due to the so-called virulence factors of putative periodontal pathogens.

Identification of periodontopathic bacteria in gingival tissue of Japanese periodontitis patients

INTRODUCTION

The identification of invading periodontopathic bacteria in tissues is important to determine their role in the pathogenesis of periodontal disease. The objective of this study was to identify periodontopathic bacteria in diseased gingival tissue of periodontitis patients.

METHODS

Subgingival plaque and gingival tissue were collected from 32 generalized chronic periodontitis (CP), 16 generalized aggressive periodontitis (GAgP) and eight localized aggressive periodontitis (LAgP) patients. Detection frequencies and quantities of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Tannerella forsythensis were investigated by polymerase chain reaction. The prevalences of Streptococcus oralis and Streptococcus sobrinus were also examined and the distribution of A. actinomycetemcomitans serotypes was observed.

RESULTS

P. gingivalis and T. forsythensis were detected in approximately 70% of tissue samples and 50% of plaque samples in the three periodontitis groups. Prevalence of A. actinomycetemcomitans in tissue samples was higher in the LAgP (63%) group than in either the CP (16%) or the GAgP (38%) group. A. actinomycetemcomitans serotype c was detected in 50% of LAgP patients. Detection frequencies of S. oralis and S. sobrinus were markedly low in both plaque and tissue samples from all three periodontitis groups. Amounts of P. gingivalis, A. actinomycetemcomitans and T. forsythensis in the tissue samples were not different among the three periodontitis groups.

CONCLUSION

P. gingivalis, A. actinomycetemcomitans and T. forsythensis can localize in diseased gingival tissue and may be involved in periodontal tissue destruction. Serotype c is the predominant serotype of A. actinomycetemcomitans in Japanese LAgP patients.

Elevated serum IgG titer and avidity to Actinobacillus actinomycetemcomitans serotype c in Japanese periodontitis patients

AIM

The purpose of this study was to characterize serum antibody responses to different serotypes of Actinobacillus actinomycetemcomitans strains in various forms of periodontitis and to determine whether any specific type of A. actinomycetemcomitans was associated with any specific form of periodontitis in a Japanese population.

METHODS

Sonicated whole cell and autoclaved serotype antigens of A. actinomycetemcomitans were used. Serum IgG titer and avidity to A. actinomycetemcomitans were measured by enzyme-linked immunoabsorbant assay (ELISA) and ammonium thiocyanate-dissociation ELISA, respectively, in 46 aggressive periodontitis patients (8 localized, 38 generalized), 28 chronic periodontitis patients, and 18 periodontally healthy subjects. The presence of A. actinomycetemcomitans in plaque and saliva samples was determined using polymerase chain reaction.

RESULTS

Generalized aggressive and chronic periodontitis patients exhibited significantly higher IgG titers than healthy subjects to both sonicated and autoclaved antigens of serotype c strains, while IgG titer to serotype b (Y4) was significantly higher in localized aggressive periodontitis patients compared to healthy subjects. No A. actinomycetemcomitans was detected in localized aggressive periodontitis patients. A. actinomycetemcomitans-positive patients exhibited significantly higher IgG titer and avidity to serotype c than A. actinomycetemcomitans-negative patients. In A. actinomycetemcomitans-positive patients, a significantly positive correlation was observed between antibody titer and avidity to serotype c. A. actinomycetemcomitans-positive patients with generalized aggressive periodontitis showed lower IgG avidities to serotype c than those with chronic periodontitis, though no statistically significant difference was found.

CONCLUSION

A. actinomycetemcomitans serotype c may play a significant role in chronic and generalized aggressive periodontitis, while A. actinomycetemcomitans serotype b may be associated with localized aggressive periodontitis in a Japanese population.

Detection of periodontopathic bacteria and an oxidative stress marker in saliva from periodontitis patients

We assessed the salivary levels of periodontopathic bacteria and 8-hydroxydeoxyguanosine (8-OHdG) in patients with periodontitis. The salivary levels of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythia (formerly Bacteroides forsythus) were assessed using real-time polymerase chain reaction. The 8-OHdG levels were determined using an enzyme-linked immunosorbent assay. The salivary levels of 8-OHdG, P. gingivalis, and T. forsythia in the periodontitis patients were significantly higher than those in healthy subjects. By contrast, the A. actinomycetemcomitans level in healthy subjects was higher than that in periodontitis patients. 8-OHdG was significantly correlated with P. gingivalis. Statistically significant decreases in the levels of P. gingivalis, probing depth, bleeding on probing, and 8-OHdG were observed after initial periodontal treatment. These results suggest that the 8-OHdG levels in saliva reflect the load of periodontal pathogens. 8-OHdG could be a useful biomarker for assessing periodontal status accurately, and for evaluating the efficacy of periodontal treatment.

Subgingival microflora in Turkish patients with periodontitis

BACKGROUND

No information exists on periodontitis-associated subgingival microbiota from Turkey. We determined the occurrence, interspecies relationships, and clonal characteristics for a group of periodontal bacteria in a Turkish study population.

METHODS

Subgingival microbial samples were obtained from patients with localized (LAgP, N = 18) or generalized (GAgP, N = 17) types of aggressive periodontitis, generalized chronic periodontitis (GCP, N = 14), and non-periodontitis subjects (N = 20). Culture methods were used to recover 6 periodontal bacterial species and yeasts, and a polymerase chain reaction technique was used to detect Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. Intraspecies characterization of A. actinomycetemcomitans was carried out by serotyping and genotyping.

RESULTS

All species, except for Micromonas micros (formerly Peptostreptococcus micros) occurred more frequently (P < 0.05) in periodontitis than non-periodontitis subjects. Detection frequencies for Tannerella forsythensis (formerly Bacteroides forsythus) and Campylobacter rectus differed among the periodontitis subgroups; the lowest frequency occurred in LAgP. The mean proportions of A. actinomycetemcomitans, P. gingivalis, and C. rectus were higher (P < 0.008) in GAgP than in non-periodontitis subjects. Significant positive associations were seen between 7 of the 22 possible combinations (P < 0.05). A. actinomycetemcomitans serotype c (34%) and non-serotypeable isolates (34%) were the most common antigenic types among the 305 strains analyzed. Eleven arbitrarily primed (AP)-PCR genotypes were distinguished among 273 isolates from 29 subjects. Yeasts were found in 23% of the 69 subjects.

CONCLUSIONS

The results on the Turkish study population were generally in line with earlier reports on the occurrence and interspecies relationships of certain bacteria in periodontitis. However, A. actinomycetemcomitans was not overrepresented in LAgP, and the serotype distribution resembled that reported from the East. The high frequency of non-serotypeable isolates suggests local characteristics of the species.

Actinobacillus actinomycetemcomitans in a rural adult population in southern Thailand

The prevalence of Actinobacillus actinomycetemcomitans isolates was examined in a rural population of southern Thailand. Sixty individuals aged 30-39 and 50-59 years were randomly selected from a group of 363 persons, living in four villages, who had been clinically examined previously. A subgingival plaque sample was taken with a curette from the mesial aspect of the two upper and lower first molars. Each sample was dispersed in 3.3 ml of VMGA III transport medium and spread onto Trypticase Soy Broth with Bacitracin and Vancomycin (TSBV)-agar plates on the same day. After incubation in 10% CO2 for 5 days the plates were examined for typical A. actinomycetemcomitans colonies which were tested for catalase activity. Each strain was further tested for biochemical characteristics, serotyped against serotype-specific antisera a-e and ribotyped after DNA digestion using the restriction endonucleases HindIII and EcoRI. For 53 (88%) of the 60 individuals, A. actinomycetemcomitans was present in at least one subgingival sample, which is considerably higher than the prevalence in Western European adults. In 11 individuals, two or three different strains were found. Serotypes a and c were the most prevalent, and serotype b was found only once among 46 tested isolates. Eleven ribotypes were found among the 46 strains. While the same ribotype could be found among individuals of the same village, no ribotype of A. actinomycetemcomitans was unique for individuals of any one village. The study demonstrated a high prevalence of A. actinomycetemcomitans among adults of the rural population of southern Thailand and indicates that this species is present as part of the resident oral flora in this population.

Expression of cytokines and inducible nitric oxide synthase in inflamed gingival tissue

BACKGROUND

Periodontopathic bacteria induce inflammation of periodontal tissues. The cytokines and nitric oxide released in periodontal lesions have been reported to play a protective role in bacterial infection and to relate to the process of inflammation. To clarify the relationship between colonization of periodontopathic bacteria and cytokines, we evaluated profiles of inflammatory cytokines, chemokine, anti-inflammatory cytokines, and inducible nitric oxide synthase (iNOS) and colonization by Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans, which are major pathogens of periodontitis.

METHODS

mRNA expression of cytokines and iNOS in inflamed and healthy gingival tissue was determined using reverse transcription-polymerase chain reaction (RT-PCR), and the relationship between their profiles and the detection of specific bacteria was analyzed.

RESULTS

The relative expression of interleukin (IL)-6 and iNOS mRNAs in periodontal lesions was significantly higher than those in healthy individuals. IL-6 mRNA expression was also significantly higher at bleeding on probing (BOP)-positive sites than at BOP-negative sites. The expressions of IL-1alpha and IL-8 increased, but IL-10 expression decreased at sites where A. actinomycetemcomitans was detected. We found no correlation between the expression of cytokine and iNOS mRNA and infection by P. gingivalis.

CONCLUSIONS

The expression of IL-6 may reflect inflammation in gingival tissue, and iNOS may be involved in the inflammatory process in periodontitis. The presence of A. actinomycetemcomitans or P. gingivalis might relate to the different cytokine profiles of IL-1alpha, IL-8, and IL-10.

W, ITANO EN. Anticorpos antileucotoxina contra Actinobacillus actinomycetemcomitans em amostras de soro e saliva de pacientes com periodontite juvenil localizada

A leucotoxina de Actinobacillus actinomycetemcomitans é considerada seu principal fator de virulência com potencial de causar agressão às defesas do hospedeiro. No presente trabalho, foram analisados os níveis séricos e salivares de anticorpos antileucotoxina de A. actinomycetemcomitans em soros e salivas de pacientes com periodontite juvenil localizada (PJL) e controles saudáveis. Adicionalmente, foi realizada a análise de complexo imune (CI) nas amostras de saliva. Foram utilizados os métodos ELISA clássico com a leucotoxina obtida por gel filtração em Sephadex G-200 e ELISA de captura utilizando IgG de coelho anti-A. actinomycetemcomitans FDC Y4 leucotóxico adsorvido com uma cepa da mesma espécie, porém, não leucotóxica. Os resultados obtidos demonstraram níveis séricos de IgG significativamente mais elevados em pacientes com PJL em relação aos controles sadios, tanto por ELISA clássico como por ELISA de captura (p < 0,05). No entanto, não foram observadas diferenças entre os níveis de IgG, IgA-S e CI nas salivas dos indivíduos examinados. Estes resultados sugerem que, embora A. actinomycetemcomitans apresente vários fatores de virulência que afetam a resposta imune do hospedeiro, ocorre resposta imune à leucotoxina nos pacientes com PJL. Esse aumento de IgG na circulação sangüínea pode contribuir na defesa do hospedeiro, limitando a lesão nas regiões periodontais amplamente colonizadas por A. actinomycetemcomitans.

A rapid DNA probe method for detection of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans

BACKGROUND

The objective of the present study was to develop a rapid DNA probe method for the microbiological detection of periodontitis that can be used in dental clinics. By using the DNA probe, we also investigated the correlation between the occurrence of putative periodontopathic bacteria and clinical parameters.

METHODS

This rapid DNA probe method minimizes the use of a water bath for ordinary hybridization and washing in order to shorten the total reaction time. The detection process could be completed within 2 hours. In order to evaluate the clinical application of the DNA probe, subgingival plaque samples were taken from patients with periodontitis before initial therapy. After the therapy, the patients were microbiologically and clinically evaluated.

RESULTS

When the DNA probe method was compared with the culture method, the agreement was 88% for Porphyromonas gingivalis and 67% for Actinobacillus actinomycetemcomitans. A statistically significant association was found between the detection of P. gingivalis and probing depth, bleeding on probing (chi2 test: P <0.001, P <0.05). A significant association was also shown between the detection of A. actinomycetemcomitans and probing depth in patients aged 35 or older (chi2 test: P <0.001). The detection rate of A. actinomycetemcomitans was highest in teenagers. At shallow periodontal pocket sites (PD < or =3 mm) in teenagers, no P. gingivalis was found, while 22% of the sites harbored A. actinomycetemcomitans. After the therapy, the frequency of detection of P. gingivalis decreased significantly only in the clinically improved sites (chi2 test: P <0.001).

CONCLUSIONS

The rapid DNA probe method appears promising as an efficient tool for rapid clinical detection of periodontopathic bacteria.

Protective effect of serum antibodies against a 110-kilodalton protein of Actinobacillus actinomycetemcomitans following periodontal therapy

Thirty-four adult patients with untreated periodontitis were randomly assigned to receive full mouth scaling alone or scaling with an adjunctive antimicrobial therapy, both followed by supportive periodontal therapy. At 24 months, specific serum immunoglobulin A (IgA), IgG and IgG subclass antibody reactivities against a 110-kDa protein of Actinobacillus actinomycetemcomitans were assessed by Western blot. In patients harboring A. actinomycetemcomitans intraorally, the IgG4 antibody reactivity against the 110-kDa protein of A. actinomycetemcomitans was associated with significantly increased survival rates of teeth and of sites not exhibiting 2 mm or more of probing attachment loss. The same trend was found for IgG3 and IgG2 antibody reactivities, but it was statistically insignificant. No association with clinical treatment outcome was observed for IgA, IgG and IgG1 antibody reactivities. The results indicated that systemic IgG4 antibody reactivity against the 110-kDa protein of A. actinomycetemcomitans may have a protective effect against periodontal disease progression in patients harboring A. actinomycetemcomitans and receiving periodontal therapy.

The pathogenesis of periodontal diseases

This informational paper was prepared by the Research, Science, and Therapy Committee of The American Academy of Periodontology, and is intended for the information of the dental profession. The purpose of the paper is to provide an overview of current knowledge relating to the pathogenesis of periodontal diseases. The paper will review biological processes thought to provide protection against periodontal infections. It will further discuss the mechanisms thought to be responsible for both overcoming and subverting such protective mechanisms and those that lead to destruction of periodontal tissues. Since an understanding of pathogenic mechanisms of disease is one foundation upon which new diagnostic and therapeutic modalities are based, the practitioner can use this information to help make decisions regarding the appropriate application of such new modalities in patient care settings.

Doença periodontal: estudo da resposta imune humoral

Foram comparados os níveis de IgG e IgA séricas e de IgG e IgA secretora (IgA-S) salivares reativas com Actinobacillus actinomycetemcomitans (Aa) e dosadas IgM, IgG e IgA séricas totais em pacientes com Periodontite de Incidência Precoce (PIP), Periodontite de Adulto (PA) e controles saudáveis (sem doença periodontal). Os níveis de anticorpos para Aa foram determinados por ELISA, e a dosagem de Igs séricas totais foi realizada por imunodifusão radial simples, utilizando-se como antígenos extrato sonicado de uma mistura de cinco isolados de Aa provenientes de pacientes com PIP e extrato sonicado de Aa de referência FDC Y4. Não foi observada diferença significativa entre os níveis séricos de anticorpos IgG e IgA e os níveis salivares de anticorpos IgG e IgA-S para Aa nos grupos PIP (n = 9), PA (n = 20) e indivíduos sadios (n = 20). Esses resultados sugerem a inexistência de alterações significativas na resposta imune humoral anti-Aa em pacientes com periodontite. A dosagem de Igs séricas totais também não revelou diferença estatisticamente significante entre pacientes com PIP (n = 9), PA (n = 9) ou controles saudáveis (n = 9).

The importance of fimbriae in the virulence and ecology of some oral bacteria

Cumulative evidence indicates that bacterial adherence to mucosal and tooth surfaces as well as bacterial coaggregation are essential steps for colonization of various oral bacterial species. Bacterial fimbriae have been shown to play an important role in the interaction between bacteria and host cells or among bacterial cells. The properties of fimbriae from selected species of oral bacteria are discussed in terms of virulence traits and ecological significance. Among others, Porphyromonas gingivalis fimbriae have been most extensively studied. The fimbrial structure is composed of 41-kDa fimbrillin proteins. DNA sequencing of the fimbrillin gene (fimA) from nine strains of P. gingivalis suggests intraspecies variation in the structure of fimA, while retaining common immunochemical specificities. P. gingivalis fimbriae exhibit a wide variety of biological activities including immunogenicity, binding to various host proteins, stimulation of cytokine production and promotion of bone resorption, Actinobacillus actinomycetemcomitans also possesses fimbriae; however, little is known concerning their chemical, genetical, and biological properties. Fimbriae of Prevotella intermedia are shown to induce hemagglutination reaction, while those of Prevotella loescheii are found to cause coaggregation with other bacteria, i.e., Actinomyces viscosus and sanguis streptococci. Fimbriae from gram-positive oral bacteria such as oral Actinomyces and sanguis streptococci are described. These fimbriae may participate in coaggregation, binding to saliva-coated hydroxyapatite or glycoprotein of the surface layer of oral epithelial cells. Taken together, fimbriae are key components in cell-to-surface and cell-to-cell adherence of oral bacteria and pathogenesis of some oral and systemic diseases.

Molecular characterization of an outer membrane protein of Actinobacillus actinomycetemcomitans belonging to the OmpA family

The major outer membrane protein (OMP) of Actinobacillus actinomycetemcomitans is an OmpA homolog that demonstrates electrophoretic heat modifiability. The gene encoding this protein was isolated from a genomic library of A. actinomycetemcomitans NCTC 9710 by immunoscreening with serum from a patient with localized juvenile periodontitis. Expression of the cloned gene in Escherichia coli and subsequent Western blot analysis revealed a protein with an approximate molecular mass of 34 kDa. The amino acid sequence predicted from the cloned gene demonstrated that the mature protein had a molecular mass of 34,911 Da and significant identity to members of the OmpA family of proteins. We have named the major OMP of A. actinomycetemcomitans Omp34, and its corresponding gene has been named omp34.

Prevalence of Actinobacillus actinomycetemcomitans serotypes in Japanese patients with periodontitis

Oral Actinobacillus actinomycetemcomitans strains are serologically classified into 5 distinct groups, a to e. We examined the distribution of A. actinomycetemcomitans serotypes in Japanese patients with periodontitis. A total of 157 A. actinomycetemcomitans clinical isolates from diseased sites of 39 patients with periodontitis were serotyped by using serotype-specific rabbit antisera against A. actinomycetemcomitans serotypes a, b, c, d and e strains. In the immunodiffusion assay, autoclaved extracts of 42, 6, 39, 9 and 41 A. actinomycetemcomitans clinical isolates reacted with serotypes a, b, c, d and e antisera, respectively. Although 37 patients were infected with a serotype strain, 2 patients harbored 2 different serotype strains, b/e and b/untypeable. To establish a correlation between serotype and genotype of A. actinomycetemcomitans clinical isolates from 2 patients who had different serotype strains, we used arbitrarily primed polymerase chain reaction (AP-PCR) to fingerprint clinical isolates of different serotypes. The AP-PCR genotypes among 4 clinical isolates (b/e and b/untypeable) were identical to that of A. actinomycetemcomitans Y4 (serotype b), indicating the presence of multiple A. actinomycetemcomitans serotypes which are genetically homogeneous in the periodontally diseased sites of patients with periodontitis.

Opsonization of Actinobacillus actinomycetemcomitans by immunoglobulin G antibodies to the O polysaccharide of lipopolysaccharide

Sera of localized juvenile periodontitis (LJP) patients colonized by Actinobacillus actinomycetemcomitans serotype b often contain markedly elevated levels of immunoglobulin G (IgG) antibodies to serospecific determinants in the O polysaccharide of lipopolysaccharide (LPS), as well as to outer membrane proteins of this species. IgG antibodies in LJP sera are known to opsonize A. actinomycetemcomitans for subsequent phagocytosis and killing by human neutrophils. The objective of this study was to determine whether outer membrane proteins or serospecific determinants in LPS are the primary target for opsonic IgG antibodies in LJP sera. An A. actinomycetemcomitans serotype b O-polysaccharide affinity column was constructed and subsequently used to purify LPS-specific IgG antibodies from LJP serum. The affinity-purified anti-LPS IgG antibodies were enriched in content of IgG2 (66.2%, compared with 37.0% in the total IgG fraction) and were immunospecific for A. actinomycetemcomitans serotype b LPS. In an opsonophagocytic assay using neutrophils from donors who were homozygous for the H131 allotype of Fcy receptor IIa (CD32), it was found that LPS-specific IgG antibodies exhibited substantially greater opsonic activity toward A. actinomycetemcomitans serotype b than an LJP IgG fraction that was depleted of LPS-reactive antibodies but contained antibodies against outer membrane proteins of this species. The results of this study indicate that serospecific determinants in the O polysaccharide of A. actinomycetemcomitans serotype b are a principal target for opsonic antibodies in sera of LJP subjects.

Specific antibody reactivity against a 110-kilodalton Actinobacillus actinomycetemcomitans protein in subjects with periodontitis

The purpose of the present study was to determine the serum immunoglobulin A (IgA), IgM, and IgG reactivities against proteins of Actinobacillus actinomycetemcomitans in patients with periodontitis. Serum samples from 20 patients with early-onset periodontitis, 20 patients with adult periodontitis, and 20 age- and sex-matched healthy controls were assessed by immunoblot analysis. IgG antibody reactivity against a sarcosyl-insoluble 110-kDa protein of A. actinomycetemcomitans was detected in 65 and 45% of patients with early-onset periodontitis and adult peritonitis, respectively, and IgA antibodies against this protein were found in 70 and 55% of these patients, respectively. However, control subjects showed no IgG reactivity, and IgA antibodies against the sarcosyl-insoluble 110-kDa protein were detected in only 5% of the patients (P < 0.05). There was no IgM antibody reactivity against this protein in any of the diseased or healthy subjects. The sensitivity and specificity of serum IgA antibody reactivity against the 110-kDa protein in detecting subgingival A. actinomycetemcomitans infection, as determined by PCR, were 77 and 66%, respectively. The results of the study indicated that the sarcosyl-insoluble 110-kDa protein is a potential candidate for use in the serodiagnosis of periodontal disease.

Characterization of Actinobacillus actinomycetemcomitans hemolysin

Twenty out of 33 Actinobacillus actinomycetemcomitans strains formed hemolytic colonies on horse blood agar plates under anaerobic conditions. The hemolytic activity found in A. actinomycetemcomitans strain 137HE was examined. This activity was detected in the late exponential to early stationary phases of growth. Human erythrocytes were the most susceptible, followed by rabbit, sheep, horse and swine red blood cells. The majority of activity was detected in the cell-associated vesicle fraction. Zwitterionic detergent 3-[(3-cholamidopropyl)-dimethyl-ammonio]-1-propanesulfonate (CHAPS) extract from whole cells was semipurified by ammonium sulfate precipitation, preparative isoelectric focusing (IEF) and gel-filtration chromatography to yield a major band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) with a molecular mass of 12 kDa. Heating at 80 C for 30 min and treatment with proteinase K or trypsin resulted in complete disappearance of the hemolytic activity. Sulphydryl reagents enhanced activity and small amounts of cholesterol inhibited it. In summary, we demonstrated the presence of hemolysin in A. actinomycetemcomitans, and examined and characterized it.

Isolation and characterization of hemolytic genes from Actinobacillus actinomycetemcomitans

Periodontopathic Actinobacillus actinomyceremcomitans produces hemolysin and other leukotoxins. In the present study, two distinct clones which lysed horse erythrocytes were isolated by screening genomic DNA libraries of A. actinomycetemcomitans ATCC 43718 on blood agar plates. DNA hybridization analysis indicates that there were two distinct hemolytic genes present. Sonicated extracts from both Escherichia coli clones possessed hemolytic activities on horse, sheep and human erythrocytes, but not those of rabbit. Rabbit antiserum to A. actinomycetemcomitans ATCC 43718 whole cells inhibited the hemolytic activities of these clones.

An antiserum to a synthetic fimbrial peptide of Actinobacillus actinomycetemcomitans blocked adhesion of the microorganism

The purpose of this study is to certify the importance of the fimbriae as an attachment factor of Actinobacillus actinomycetemcomitans, a human periodontopathic bacterium, and the significance of anti-fimbrial antibody function as an attachment inhibitor. Fimbrial antigen was prepared from the A. actinomycetemcomitans 310-a strain. Oligopeptides were synthesized according to the amino acid sequence of the fimbrial protein. The peptide antigen was conjugated with branched lysine polymer resin beads. The peptide antigen was suspended in PBS emulsified with incomplete Freund's adjuvant and used to immunize rabbits. A rabbit antiserum reacted with an approximately 54 kDa protein of the fimbriae protein from A. actinomycetemcomitans 310-a and with those of other fimbriated strains. This antiserum strongly inhibited the attachment of fimbriated A. actinomycetemcomitans strains to saliva-coated hydroxyapatite beads, buccal epithelial cells, and a fibroblast cell line, Gin-1. Such a synthetic fimbrial peptide antigen may be effective in inducing antibodies which inhibit adhesion and subsequent colonization by A. actinomycetemcomitans.

Characterization of an antiproliferative surface-associated protein from Actinobacillus actinomycetemcomitans which can be neutralized by sera from a proportion of patients with localized juvenile periodontitis

The gentle agitation of suspensions of Actinobacillus actinomycetemcomitans serotype a, b, or c in saline resulted in the release of a proteinaceous surface-associated material (SAM) which produced a dose-dependent inhibition of tritiated thymidine incorporation by the osteoblast-like cell line MG63 in culture. This cell line was sensitive to low concentrations of SAM (50% inhibitory concentration, 200 ng/ml for serotype c). Immunoglobulin G antibodies to constituents of the SAM were found in the blood of patients with localized juvenile periodontitis (LJP). Sera from 9 of 16 patients with LJP significantly neutralized the antiproliferative activity of the SAM, while sera from 15 controls, with no evidence of periodontal disease, were unable to neutralize this activity. Neutralization was not directly related to the patient's antibody titer to the whole SAM. Characterization of the antiproliferative activity in the SAM demonstrated that it was not cytotoxic and was heat and trypsin sensitive. The active component separated in a well-defined peak in anion-exchange high-performance liquid chromatography (HPLC) which, when further analyzed by size exclusion HPLC, revealed a single active peak, which had an apparent molecular mass of approximately 8 kDa. The lipopolysaccharide from A. actinomycetemcomitans was only weakly active. SAM from Porphyromonas gingivalis W50 and Eikenella corrodens NCTC 10596 did not exhibit any antiproliferative activity with this cell line, even at concentrations as high as 10 micrograms/ml. This study has shown that SAM from A. actinomycetemcomitans contains a potent antiproliferative protein whose activity can be neutralized by antibodies in the sera from some patients with LJP.

Locally delivered minocycline and guided tissue regeneration to treat post-juvenile periodontitis. A case report

A case of post-juvenile periodontitis in a 28-year-old female patient is described along with new periodontal treatment modalities. Administration of minocycline-HCl with local drug delivery system was introduced as a part of initial periodontal therapy following microbiological and immunological examinations. The lesions were subsequently treated by guided tissue regeneration, which resulted in considerable gain of attachment with minimal recession of marginal gingiva. This observation suggests that the local delivery of antibiotics and regenerative therapy may prove to be effective alternative modalities in treatment of post-juvenile periodontitis.

Infection by Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans, and antibody responses at different ages in humans

This study examined the serum IgG and IgM responses against Porphyromonas gingivalis and 3 serotypes of Actinobacillus actinomycetemcomitans, and the correlations of these responses with age and homologous infection. A total of 90 individuals were included in this study: 40 subjects with gingivitis, 40 periodontally healthy subjects, and 10 adult periodontitis subjects. The subjects in the gingivitis and periodontally healthy groups were divided into 4 stages based on their physiological age: early childhood, school age, puberty, and adult. In the gingivitis group, there was a positive correlation between increase in age and increase in serum IgG antibody levels against P. gingivalis until puberty. However, no statistically significant difference was found between the puberty stage and the adult stage. The average level of IgG antibodies against A. actinomycetemcomitans in the school age gingivitis group was significantly higher than that in the early childhood gingivitis group for all serotypes (p < 0.01). In serotype c, IgG antibody levels in the school age gingivitis group were significantly higher than in the early childhood gingivitis group or the adult gingivitis group (p < 0.01). With both P. gingivalis and A. actinomycetemcomitans, positive correlations between elevated IgG level and infections by these microorganisms were found in the puberty gingivitis and adult periodontitis groups.