Serum immunoglobulin G antibody to Porphyromonas gingivalis in rapidly progressive periodontitis: titer, avidity, and subclass distribution

Interaction Between Autophagy and Porphyromonas gingivalis-Induced Inflammation

Autophagy is an immune homeostasis process induced by multiple intracellular and extracellular signals. Inflammation is a protective response to harmful stimuli such as pathogen microbial infection and body tissue damage. Porphyromonas gingivalis infection elicits both autophagy and inflammation, and dysregulation of autophagy and inflammation promotes pathology. This review focuses on the interaction between autophagy and inflammation caused by Porphyromonas gingivalis infection, aiming to elaborate on the possible mechanism involved in the interaction.

Variations in IgG antibody subclass responses to oral bacteria: Effects of periodontal disease and modifying factors

BACKGROUND AND OBJECTIVE

Local and systemic IgG antibodies or oral bacteria have been described with periodontitis. We extended these observations by assessing the impact of a range of intrinsic factors on serum IgG subclass antibodies to both commensal and pathogenic oral bacteria that would contribute to variations in immune protection or disease susceptibility in periodontitis have not been described.

METHODS

Subjects (n = 278) were classified as healthy, gingivitis, or periodontitis and categorized as mild, moderate, and severe periodontitis. Demographic stratification included sex, age, race/ethnicity, smoking, and obesity. Whole formalin-fixed bacteria were used as antigens to detect serum immunoglobulin (Ig)G subclass antibody levels using an ELISA.

RESULTS

The greatest differences in variations in IgG subclasses occurred in periodontitis versus health or gingivitis to bacteria considered oral pathogens (eg, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Treponema denticola) with IgG1, IgG2, and IgG4 increased by three- to sevenfold with Pg. Differences in subclass levels and distribution were also observed related to disease severity, particularly related to individual subclass responses to Pg. Examination of the overall population showed that females had elevated antibody, reflected by elevated IgG2 amounts/proportions. The older group of subjects demonstrated elevated antibody to multiple oral bacteria, lacking any particular subclass pattern. IgG2 antibody to Aa and Pg was increased in smokers. Multiple IgG subclass antibody levels to oral pathogens were significantly decreased in the obese subset within this population.

CONCLUSION

This investigation identified patterns of IgG subclass antibody responses to oral bacteria and demonstrated substantial effects of disease impacting the level and subclass distribution of antibody to an array of oral bacteria. Altered subclass antibody profiles most often in IgG2 levels and for antibody to P. gingivalis were found related to sex, age, disease severity, race/ethnicity, smoking, and obesity to both pathogens and commensal bacteria.

Heterogeneity of human serum antibody responses to P. gingivalis in periodontitis: Effects of age, race/ethnicity, and sex

Aging humans display an increased prevalence and severity of periodontitis, although the mechanisms underlying these findings remain poorly understood. This report examined antigenic diversity of P. gingivalis related to disease presence and patient demographics. Serum IgG antibody to P. gingivalis strains ATCC33277, FDC381, W50 (ATCC53978), W83, A7A1-28 (ATCC53977) and A7436 was measured in 426 participants [periodontally healthy (n = 61), gingivitis (N = 66) or various levels of periodontitis (N = 299)]. We hypothesized that antigenic diversity in P. gingivalis could contribute to a lack of "immunity" in the chronic infections of periodontal disease. Across the strains, the antibody levels in the oldest age group were lower than in the youngest groups, and severe periodontitis patients did not show higher antibody with aging. While 80 % of the periodontitis patients in any age group showed an elevated response to at least one of the P. gingivalis strains, the patterns of individual responses in the older group were also substantially different than the other age groups. Significantly greater numbers of older patients showed strain-specific antibody profiles to only 1 strain. The findings support that P. gingivalis may demonstrate antigenic diversity/drift within patients and could be one factor to help explain the inefficiency/ineffectiveness of the adaptive immune response in managing the infection.

Immunization with cell-free-generated vaccine protects from Porphyromonas gingivalis-induced alveolar bone loss

Introduction

Periodontal diseases (PD) are complex oral inflammatory diseases initiated by keystone bacteria such as Porphyromonas gingivalis. A vaccine for PD is desirable as clinical treatment involves protracted maintenance strategies aimed to retain dentition. Although prior immunization approaches targeting P. gingivalis have reported variable success in limiting facets of disease such as oral bone loss, it remains that a vaccine for this disease may be attainable.

Aim

To investigate cell‐free protein synthesis (CFPS) as a platform to produce vaccinable targets suitable for efficacy testing in a P. gingivalis‐induced murine oral bone loss model.

Materials and Methods

Recombinantly generated P. gingivalis minor fimbriae protein (Mfa1), RgpA gingipain hemagglutinin domain 1 (HA1), and RgpA gingipain hemagglutinin domain 2 (HA2) were combined in equivalent doses in adjuvants and injected intramuscularly to immunize mice. Serum levels of protein‐specific antibody were measured by ELISA, and oral bone levels were defined by morphometrics.

Results

Recombinantly generated P. gingivalis proteins possessed high fidelity to predicted size and elicited protein‐specific IgG following immunization. Importantly, immunization with the vaccine cocktail protected from P. gingivalis elicited oral bone loss.

Conclusion

These data verify the utility of the CFPS technology to synthesize proteins that have the capacity to serve as novel vaccines.

Revisiting the Page & Schroeder model: the good, the bad and the unknowns in the periodontal host response 40 years later

In their classic 1976 paper, Page & Schroeder described the histopathologic events and the types of myeloid cells and lymphocytes involved in the initiation and progression of inflammatory periodontal disease. The staging of periodontal disease pathogenesis as 'initial', 'early', 'established' and 'advanced' lesions productively guided subsequent research in the field and remains fundamentally valid. However, major advances regarding the cellular and molecular mechanisms underlying the induction, regulation and effector functions of immune and inflammatory responses necessitate a reassessment of their work and its integration with emerging new concepts. We now know that each type of leukocyte is actually represented by functionally distinct subsets with different, or even conflicting, roles in immunity and inflammation. Unexpectedly, neutrophils, traditionally regarded as merely antimicrobial effectors in acute conditions and protagonists of the 'initial' lesion, are currently appreciated for their functional versatility and critical roles in chronic inflammation. Moreover, an entirely new field of study, osteoimmunology, has emerged and sheds light on the impact of immunoinflammatory events on the skeletal system. These developments and the molecular dissection of crosstalk interactions between innate and adaptive leukocytes, as well as between the immune system and local homeostatic mechanisms, offer a more nuanced understanding of the host response in periodontitis, with profound implications for treatment. At the same time, deeper insights have generated new questions, many of which remain unanswered. In this review, 40 years after Page & Schroeder proposed their model, we summarize enduring and emerging advances in periodontal disease pathogenesis.

The B Cell-Stimulatory Cytokines BLyS and APRIL Are Elevated in Human Periodontitis and Are Required for B Cell-Dependent Bone Loss in Experimental Murine Periodontitis

B-lineage cells (B lymphocytes and plasma cells) predominate in the inflammatory infiltrate of human chronic periodontitis. However, their role in disease pathogenesis and the factors responsible for their persistence in chronic lesions are poorly understood. In this regard, two cytokines of the TNF ligand superfamily, a proliferation-inducing ligand (APRIL) and B-lymphocyte stimulator (BLyS), are important for the survival, proliferation, and maturation of B cells. Thus, we hypothesized that APRIL and/or BLyS are upregulated in periodontitis and contribute to induction of periodontal bone loss. This hypothesis was addressed in both human and mouse experimental systems. We show that, relative to healthy controls, the expression of APRIL and BLyS mRNA and protein was upregulated in natural and experimental periodontitis in humans and mice, respectively. The elevated expression of these cytokines correlated with increased numbers of B cells/plasma cells in both species. Moreover, APRIL and BLyS partially colocalized with κ L chain-expressing B-lineage cells at the epithelial-connective tissue interface. Ligature-induced periodontitis resulted in significantly less bone loss in B cell-deficient mice compared with wild-type controls. Ab-mediated neutralization of APRIL or BLyS diminished the number of B cells in the gingival tissue and inhibited bone loss in wild-type, but not in B cell-deficient, mice. In conclusion, B cells and specific cytokines involved in their growth and differentiation contribute to periodontal bone loss. Moreover, APRIL and BLyS have been identified as potential therapeutic targets in periodontitis.

Immuno-pathogenesis of Periodontal Disease: Current and Emerging Paradigms

Periodontal disease (PD) is a highly complex disease involving many factors; however, two principal facets central to initiation and progression of the majority of PD are the composition of the microbes in the sub-gingival plaque, and the host immune response to these organisms. Numerous studies point to the complexity of PD, and to the fact that despite innate and adaptive immune activation, and resultant inflammation, our immune response fails to cure disease. Stunning new findings have begun to clarify several complexities of the host-pathogen interaction of PD pointing to key roles for microbial dysboisis and immune imbalance in the pathogenesis of disease. Furthermore, these investigations have identified novel translational opportunities to intercede in PD treatment. In this review we will highlight a select few recent findings in innate and adaptive immunity, and host pathogen interactions of PD at a micro-environmental level that may have profound impact on PD progression.

Autopathogenic correlation of periodontitis and rheumatoid arthritis

Recently, a number of studies have pointed to a potential relationship between periodontitis (PO) and RA and vice versa. Both diseases are characterized by chronic inflammation, osseous destruction, damage of the supporting soft tissues, similar cellular immune responses and common immunogenetic findings. Although a definite, methodological report associating these diseases is missing from the literature, it is possible that both diseases share a common aetiopathogenic background. This background includes the post-translation modification citrullination, which guides the conversion of the amino acid arginine to citrulline in certain self-proteins, generating neo-epitope structures. This results in reduced self-tolerance, development of autoimmunity and the production of ACPAs. The current hypothesis suggests that certain oral bacteria induce the citrullination of proteins under the action of the enzyme peptidyl arginine deiminase (PAD), which exists in both Porphyromonas gingivalis and inflammatory cells. Antibodies against citrullinated proteins and peptides constitute a common serological finding in both RA and PO. The aim of this review is to map the immunological and serological profiles of PO, and to unveil the parameters that connect PO with the appearance of RA at clinical, prognostic and pathogenetic levels. Until now, there have been no reports sufficiently mapping the immunological profile of PO and defining its aetiopathogenic connection with RA, although a similarity between the immunological profile of PO and RA is highly expected.

A targeted fimA DNA vaccine prevents alveolar bone loss in mice after intra-nasal administration

AIM

To construct a dendritic cell (DC)-targeted DNA vaccine against FimA of Porphyromonas gingivalis and evaluate the immunogenicity and protection in mice.

MATERIALS AND METHODS

A targeted DNA plasmid pCTLA4-FimA, which encodes the signal peptide and extracellular regions of mouse cytotoxic T lymphocyte-associated antigen 4 (CTLA4), the hinge and Fc regions of human Igγ1 and FimA of P. gingivalis, was constructed. Mice were immunized with pCTLA4-FimA, the non-targeted DNA plasmid pFimA, which contains only fimA gene, or pCI vector intra-nasally. Serum and saliva antibody responses were detected by enzyme-linked immunosorbent assay. The protection against P. gingivalis-induced periodontitis was evaluated by measuring alveolar bone loss in mice.

RESULTS

Mice immunized with pCTLA4-FimA showed elevated levels of specific serum IgG and salivary IgA antibody responses compared with mice immunized with pFimA (p<0.01). Both pFimA and pCTLA4-FimA immunized groups showed significantly lower alveolar bone loss, with the magnitude protection greater in the latter (p<0.01), compared with the pCI immunized group.

CONCLUSIONS

The DC-targeted DNA construct pCTLA4-FimA enhanced both systemic and mucosal immunity following intra-nasal immunization. A DNA-based immunization strategy may be an effective way to attenuate periodontitis induced by P. gingivalis.

Feasibility and therapeutic strategies of vaccines against Porphyromonas gingivalis

Periodontitis is a chronic infectious disease that is highly prevalent worldwide and is characterized by inflammation of the gums, and loss of connective tissue and bone support. The Gram-negative anerobic bacterium Porphyromonas gingivalis is generally accepted as the main etiological agent for chronic periodontitis. The objective of this paper is to elucidate the feasibility of achieving protection against periodontitis though immunization against P. gingivalis. Until now, animal studies have showed no complete protection against P. gingivalis. However, current knowledge about P. gingivalis structures could be applicable for further research to develop a successful licensed vaccine and alternative therapeutic strategies. This review reveals that a multicomponent vaccine against P. gingivalis, which includes structures shared among P. gingivalis serotypes, will be feasible to induce broad and complete protection.

The association of Fcgamma receptor IIIb genetic polymorphism and susceptibility to periodontitis in Taiwanese individuals

AIM

The allelic polymorphism of FcgammaRIIIb, the neutrophil-specific receptor involved in the phagocytosis of immunoglobulin G-opsonized bacteria, has functionally distinct capacities that are important in host defence mediated by neutrophils. The aim of this study was to identify whether the polymorphism of FcgammaRIIIb is associated with periodontitis in Taiwanese individuals.

MATERIALS AND METHODS

This case-control study included of 93 aggressive periodontitis (AgP) patients, 372 chronic periodontitis (CP) patients and 158 healthy controls (HC). The FcgammaRIIIb genotypes were determined by PCR using allele-specific primers. The risk for periodontitis associated with genotypes was calculated as the odds ratio (OR).

RESULTS

A significant difference was observed in the distribution of the FcgammaRIIIb genotype between either AgP and HC, or AgP and CP, but not between CP and HC. The OR for carriage of the NA2 allele (NA1NA2+NA2NA2 versus NA1NA1) in AgP was 3.27 [95% confidence interval (CI)=1.57-7.51, p=0.0027] and 2.94 (95% CI=1.49-6.48, p=0.0037), as compared with HC and CP. After adjusting for possible confounding factors, the association was still significant.

CONCLUSIONS

The results of the present study suggest that subjects carrying at least one copy of the FcgammaRIIIb-NA2 allele might be associated with susceptibility to AgP. However, the clinical implications of the FcgammaRIIIb allelic polymorphism should be determined by further studies.

Porphyromonas gingivalis may play an important role in the pathogenesis of periodontitis-associated rheumatoid arthritis

Rheumatoid arthritis (RA) is a common, systemic autoimmune disease which leads to destruction of the joint architecture and consequent disability. Although the aetiology of RA remains unknown, accumulating studies have established a strong association between RA and periodontitis (PD). Recently, anti-cyclic citrullinated peptide (anti-CCP) autoantibody and citrullinated peptide have been realized to be involved in the breaking of self-tolerance and development of autoimmune in RA. The citrullinated peptide is generated by post-translational modification (citrullination) of protein-bound arginine by peptidylarginine deiminase (PAD). Porphyromonas gingivalis(P. gingivalis), the major aetiological agent of PD and the only bacterium known to express a PAD enzyme, has been reported to be significantly associated with RA. The antibody titers to P. gingivalis are significantly increased in patients with RA and P. gingivalis antibody titers are significantly correlated with anti-CCP antibody isotypes that are specific to RA. Recent study indicates that the major synovial targets of the RA-specific anti-CCP autoantibodies are deiminated forms of the alpha- and beta- chains of fibrin. Meanwhile, it is also confirmed that bacterial PAD produced by P. gingivalis has the capacity of deiminating arginine in fibrin found in the periodontal lesion. What's more, it has been demonstrated that citrullination of HLA binding peptide causes a 100-fold increase in peptide-MHC affinity and leads to the activation CD4(+)T cells in HLA DRB1 0401 transgenic mice. Therefore, we postulate that P. gingivalis may play a crucial role in the pathogenesis of periodontitis-associated RA. P. gingivalis, which colonizes in the oral cavity, produces PAD enzyme continuously that leads to the citrullination of RA autoantigen such as fibrin in synovium joint. These PAD engendered antigens, presented in association with major histocompatibility complex (MHC) molecules by antigen-presenting cells (APC), ultimately lead to production of the anti-CCP antibody. The anti-CCP antibodies form immune complexes with citrullinated proteins, which can be bound by inflammatory cells via their Fc receptors. The roles of these immune complexes and inflammatory cells are mediated by a complex cascade involving complement activation. These mechanisms result in a release of mediators of inflammation and joint destruction ultimately leading to the onset of RA. This hypothesis reveals that oral bacterial infection may play a role in peptide citrullination which might be involved in loss of self-tolerance and development of autoimmune in RA.

Binding of complement inhibitor C4b-binding protein contributes to serum resistance of Porphyromonas gingivalis

The periodontal pathogen Porphyromonas gingivalis is highly resistant to the bactericidal activity of human complement, which is present in the gingival crevicular fluid at 70% of serum concentration. All thirteen clinical and laboratory P. gingivalis strains tested were able to capture the human complement inhibitor C4b-binding protein (C4BP), which may contribute to their serum resistance. Accordingly, in serum deficient of C4BP, it was found that significantly more terminal complement component C9 was deposited on P. gingivalis. Moreover, using purified proteins and various isogenic mutants, we found that the cysteine protease high molecular weight arginine-gingipain A (HRgpA) is a crucial C4BP ligand on the bacterial surface. Binding of C4BP to P. gingivalis appears to be localized to two binding sites: on the complement control protein 1 domain and complement control protein 6 and 7 domains of the alpha-chains. Furthermore, the bacterial binding of C4BP was found to increase with time of culture and a particularly strong binding was observed for large aggregates of bacteria that formed during culture on solid blood agar medium. Taken together, gingipains appear to be a very significant virulence factor not only destroying complement due to proteolytic degradation as we have shown previously, but was also inhibiting complement activation due to their ability to bind the complement inhibitor C4BP.

Antibody responses to Porphyromonas gingivalis (P. gingivalis) in subjects with rheumatoid arthritis and periodontitis

Antibody titers to P. gingivalis are increased in patients with rheumatoid arthritis and are associated with disease-specific autoimmunity.

BACKGROUND

Periodontitis (PD) has been implicated as a risk factor for rheumatoid arthritis (RA). We sought to characterize antibody titers to P. gingivalis (a pathogen in PD) in subjects with RA, PD, and in healthy controls and to examine their relationship with disease autoantibodies.

METHODS

P. gingivalis antibody was measured in subjects with RA (n=78), PD (n=39), and in controls (n=40). Group frequencies of bacterial titer elevations were compared using the Chi-square test and antibody titers were compared using non-parametric tests. Correlations of P. gingivalis titer with C-reactive protein (CRP), antibody to cyclic citrullinated peptide (anti-CCP), and rheumatoid factor (RF) were examined in those with RA while CRP and autoantibody concentrations were compared based on seropositivity to P. gingivalis.

RESULTS

Antibody titers to P. gingivalis were highest in PD, lowest in controls, and intermediate in RA (p=0.0003). Elevations in P. gingivalis (titer> or =800) were more common in RA and PD (67% and 77%, respectively) than in controls (40%) (p=0.002). In RA, there were significant correlations with P. gingivalis titer with CRP, anti-CCP-IgM, and -IgG-2. CRP (p=0.006), anti-CCP-IgM (p=0.01) and -IgG2 (p=0.04) concentrations were higher in RA cases with P. gingivalis titers > or =800 compared to cases with titers <800.

CONCLUSION

Antibodies to P. gingivalis are more common in RA subjects than controls, although lower than that in PD. Associations of P. gingivalis titers with RA-related autoantibody and CRP concentrations suggests that infection with this organism plays a role in disease risk and progression in RA.

Serum antibody levels in smoker and non-smoker saudi subjects with chronic periodontitis

BACKGROUND

Cigarette smoking is a significant risk factor for the initiation and progression of periodontal disease. Studies have shown altered serum and gingival crevicular fluid inflammatory cytokine profiles, immune cell function, and altered proteolytic regulation in smokers. The observations are not consistent, and to date, there is no clear mechanism to explain how smoking may affect periodontal disease. Hence, the present study was undertaken to assess the alterations of serum immunoglobulin levels in smokers with periodontitis and its potential role as a risk indicator of the disease process.

METHODS

In this study, 30 patients who smoked and 30 patients who did not smoke with chronic periodontitis and 30 healthy subjects were enrolled. Serum immunoglobulin (Ig) G, IgA, and IgM levels were estimated with immunoturbidimetric assay. The IgG subclass (IgG1, IgG2, IgG3, and IgG4) levels were performed using single radial immunodiffusion assay.

RESULTS

Levels of serum IgG and IgA were significantly lower in smokers compared to non-smokers and healthy controls (P <0.001). Although IgM levels were low in smokers, it was not significant. Of the four subclasses of IgG studied, the IgG2 was found to be significantly lower among smokers with periodontitis.

CONCLUSIONS

Current observations indicate that cigarette smoking may be associated with the suppression of B-cell function and immunoglobulin production. The alteration of antibody levels further explains the potential mechanism by which smoking exacerbates periodontal disease. Further studies at the molecular level may highlight the specific mechanism by which tobacco can interact with cells of the immune system and its impact on periodontal disease process.

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.

Biphasic effect of gingipains from Porphyromonas gingivalis on the human complement system

Periodontitis is an inflammatory disease of the supporting structures of the teeth and is caused by, among other agents, Porphyromonas gingivalis. P. gingivalis is very resistant to killing by human complement, which is present in a gingival fluid at 70% of the serum concentration. We found that the incubation of human serum with purified cysteine proteases of P. gingivalis (gingipains) or P. gingivalis wild-type strains W83 and W50 resulted in a drastic decrease of the bactericidal activity of the serum. In contrast, serum treated with P. gingivalis mutants lacking gingipains (particularly strains without HRgpA) maintained significant bactericidal activity. To understand in detail the mechanism by which gingipains destroy the serum bactericidal activity, we investigated the effects of gingipains on the human complement system. We found that all three proteases degraded multiple complement components, with arginine-specific gingipains (HRgpA and RgpB) being more efficient than lysine-specific gingipain (Kgp). Interestingly, all three proteases at certain concentrations were able to activate the C1 complex in serum, which resulted in the deposition of C1q on inert surfaces and on bacteria themselves. It is therefore plausible that P. gingivalis activates complement when present at low numbers, resulting in a local inflammatory reaction and providing the bacteria with a colonization opportunity and nutrients. At later stages of infection the concentration of proteases is high enough to destroy complement factors and thus render the bacteria resistant to the bactericidal activity of complement.

Immunoglobulin G subclass antibody profiles in Porphyromonas gingivalis-associated aggressive and chronic periodontitis patients

BACKGROUND/AIMS

The immunoglobulin G (IgG) antibody response is considered to be protective and beneficial for the control of periodontal lesions. This study analysed IgG subclass antibody levels of Porphyromonas gingivalis in patients with both aggressive periodontitis (AgP) and chronic periodontitis (CP).

METHODS

Subgingival plaque and peripheral blood samples were collected from patients with localized AgP (n = 13), generalized AgP (n = 28) and generalized CP (n = 27) and from 14 periodontally healthy controls. P. gingivalis was identified in subgingival pockets using a polymerase chain reaction. Simultaneously, serum IgG subclass antibody against P. gingivalis whole cells/P. gingivalis fimbriae were measured using enzyme-linked immunosorbent assay.

RESULTS

P. gingivalis was frequently detected in periodontitis patients. Anti-P. gingivalis whole cell IgG1 was elevated in all P. gingivalis-positive patients in the three periodontitis groups. Although increased anti-P. gingivalis IgG1 was also observed in the bacterium-positive healthy controls, the level was lower than that found in the three periodontitis groups. Levels of IgG1, IgG2, IgG3 and IgG4 to P. gingivalis did not differ among bacterium-positive patients in the three periodontitis groups; a significant increase of IgG2 level was not observed in localized AgP. Anti-fimbriae IgG subclass levels of IgG1, IgG2 and IgG4 did not differ among bacterium-positive subjects in all groups, while the anti-fimbriae IgG3 level in generalized CP was significantly higher than that in localized and generalized AgP.

CONCLUSIONS

P. gingivalis infection elicited an IgG subclass antibody response in both periodontitis patients and healthy subjects, while higher anti-P. gingivalis IgG1 levels were found in the three periodontitis groups compared with the healthy control group.

T-cell expression cloning of Porphyromonas gingivalis genes coding for T helper-biased immune responses during infection

Exposure of the mouse oral cavity to Porphyromonas gingivalis results in the development of gingivitis and periapical bone loss, which apparently are associated with a Th1 response to bacterial antigens. We have used this infection model in conjunction with direct T-cell expression cloning to identify bacterial antigens that induce a preferential or biased T helper response during the infectious process. A P. gingivalis-specific CD4 T-cell line derived from mice at 3 weeks postchallenge was used to directly screen a P. gingivalis genomic expression library. This screen resulted in the identification of five genes coding for previously identified proteins and three other putative protein antigens. One of the identified proteins, P. gingivalis thiol peroxidase, was studied in detail because this molecule belongs to a protein family that is apparently involved in microbial pathogenesis. Infection of mice with P. gingivalis, either via the subcutaneous route or after exposure of the animal's oral cavity to viable bacteria, resulted in the induction of a strong thiol peroxidase-specific immune response characterized by the production of high titers of specific serum immunoglobulin G2a antibody and the production of gamma interferon by antigen-stimulated lymphoid cells, a typical Th1-biased response. Thus, the use of a proven T-cell expression cloning approach and a mouse model of periodontal disease resulted in the identification and characterization of P. gingivalis proteins that might be involved in pathogenesis.

Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis subgingival presence, species-specific serum immunoglobulin G antibody levels, and periodontitis disease recurrence

BACKGROUND AND OBJECTIVE

The biological and clinical effects of antibody against periodontal pathogenic bacteria are incompletely understood. This study evaluated the inter-relationships among periodontal levels of cultivable Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, species-specific serum immunoglobulin G (IgG) antibody levels, and periodontitis disease activity.

MATERIAL AND METHODS

Forty-three adults who had previously been treated for periodontitis and who also harbored cultivable A. actinomycetemcomitans or P. gingivalis were evaluated semiannually for clinical disease recurrence over a 36-month period. Each patient provided subgingival microbial samples, for the recovery of A. actinomycetemcomitans and P. gingivalis, from the two deepest pockets in each dentition sextant. A. actinomycetemcomitans and P. gingivalis serum IgG antibody levels were assessed using enzyme-linked immunosorbent assay (ELISA), together with whole-cell sonicate extracts from A. actinomycetemcomitans serotypes a-c and P. gingivalis ATCC 33277. Data were analyzed using the Mantel-Haenszel chi-square and Fisher exact two-tailed tests.

RESULTS

Eighteen (60.0%) of 30 A. actinomycetemcomitans-positive subjects, and 10 (76.9%) of 13 P. gingivalis-positive subjects, exhibited recurrent periodontal breakdown within 36 months of periodontal therapy. Nineteen (67.9%) of the 28 patients with active periodontitis had A. actinomycetemcomitans or P. gingivalis serum antibody levels below designated threshold values. In comparison, 10 (66.7%) of 15 culture-positive clinically stable subjects showed A. actinomycetemcomitans or P. gingivalis serum antibody levels above threshold values. The difference between specific antibody levels in periodontitis-active and periodontitis-stable patients was statistically significant (p = 0.032).

CONCLUSIONS

Serum levels of IgG antibodies against A. actinomycetemcomitans or P. gingivalis in periodontitis-stable patients were higher than those in patients with active periodontitis. The results suggest that elevated levels of IgG antibody against A. actinomycetemcomitans and P. gingivalis have a detectable protective effect against periodontal infections with these microorganisms.

Serum IgG1 and IgG2 antibody responses to Porphyromonas gingivalis in patients with periodontitis

BACKGROUND/AIMS

Protein and carbohydrate antigens of Porphyromonas gingivalis interact with the host to produce antibody of different subclasses. IgG1 and IgG2 antibodies frequently account for approximately 90% of the total serum IgG. This work aimed to investigate serum IgG1 and IgG2 antibody responses of periodontitis patients to protein and carbohydrate-rich antigens of P. gingivalis.

METHODS

Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blots of P. gingivalis antigens and proteinase K digested antigens rich in carbohydrates were used to investigate the molecular weight of antigen recognised by serum IgG1 and IgG2. Enzyme-linked immunosorbent assay was used to measure levels of IgG1 and IgG2 antibody to P. gingivalis and radial immunodiffusion was used to estimate the total concentration of IgG1 and IgG2 in serum.

RESULTS

Serum IgG antibodies bound to antigens of molecular weights 47, 39 and 32 kDa. Antigen most frequently recognised by both IgG1 and IgG2 antibody had a molecular weight of 47 kDa. Serum IgG2 antibody bound to carbohydrate antigen with a molecular weight of 32 kDa but there was no recognition of carbohydrate antigens by IgG1 antibodies. There was no correlation between the titre of anti-P. gingivalis IgG1 or IgG2 antibody and the total concentration of serum IgG1 or IgG2 antibodies of all specificities.

CONCLUSION

Both IgG1 and IgG2 antibodies recognised a dominant antigen of 47 kDa, probably Arg-gingipain. Much of the response to carbohydrate antigen is of the IgG2 subclass. Neither the level of IgG1 nor the IgG2 antibody specific to P. gingivalis was related to the total serum concentration of that antibody.

Gingipain-Specific IgG in the Sera of Patients With Periodontal Disease Is Necessary for Opsonophagocytosis ofPorphyromonas gingivalis

BACKGROUND

Porphyromonas gingivalis is a primary etiologic agent of generalized aggressive periodontitis (GAgP), and gingipains, a group of cysteine proteinases, are critical virulence factors expressed by this organism. GAgP patients develop specific antibodies to gingipains; however, the function of these antibodies in the clearance of P. gingivalis infection is poorly understood.

METHODS

In this study, we defined the levels of gingipain-specific antibodies in GAgP patient sera and examined the ability of gingipain-specific antibodies to facilitate opsonophagocytosis of P. gingivalis by human polymorphonuclear leukocytes (PMNs) using a fluorescent phagocytosis assay.

RESULTS

GAgP patient sera possessed elevated levels of P. gingivalis-, arginine-gingipain (Rgp)A-, RgpB-, and lysine-gingipain (Kgp)-specific IgG (Kgp > RgpA > P. gingivalis > RgpB). Adsorption of GAgP sera with P. gingivalis whole organisms, RgpA, RgpB, and Kgp conjugated to sepharose beads reduced opsonophagocytosis of P. gingivalis by PMNs.

CONCLUSIONS

Our studies demonstrate that GAgP patient sera possess elevated levels of P. gingivalis- and gingipain-specific IgG. Furthermore, we show that gingipain antibodies promote uptake of P. gingivalis by PMNs, and our data suggest that gingipain-specific antibodies may be important for the control of P. gingivalis infections.

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.

Porphyromonas gingivalis-specific immunoglobulin G prevents P. gingivalis-elicited oral bone loss in a murine model

Active immunization with Porphyromonas gingivalis whole-cell preparations has been shown to prevent P. gingivalis infection and oral bone loss. Employing passive antibody transfer and opsonization, we demonstrate with this study that immunization-elicited P. gingivalis-specific immunoglobulin G facilitates clearance of P. gingivalis in a subcutaneous chamber model and prevents P. gingivalis-elicited oral bone loss.

Gm (23) allotypes and Fcgamma receptor genotypes as risk factors for various forms of periodontitis

OBJECTIVES

Given the diversity of the distribution of the Gm (23) allotypes and FcgammaR genotypes in different ethnic groups, it was our purpose to examine their clinical significance in periodontitis in Taiwan.

MATERIAL & METHODS

Genomic DNA of 50 patients with chronic periodontitis (CP), 30 patients with generalized aggressive periodontitis (G-AP) and 74 healthy controls were harvested. The Gm (23) allotypes were determined by radial immunodiffusion test, and the FcgammaR IIa (CD32) and IlIb (CD16) genotypes were determined by polymerase chain reaction-based allele-specific oligonucleotide hybridization.

RESULTS

The overall carrier rate of the Gm (23+) allotype was higher than 85%, and the Gm (23-) allotype was statistically over-represented in patients with CP compared to the controls. There were no differences in the distributions of the three genotypes of FcgammaR IIa and IIIb among the three tested groups. The frequency of the R131 allele of the FcgammaR IIa polymorphisms was higher in G-AP than in CP when R/H allelic frequencies (p = 0.01) were examined by the chi2 test.

CONCLUSION

The Gm (23-) allotype might be a potential risk factor for CP. Although the R131 allele of FcgammaR IIa occurred more frequently in G-AP than in CP, its clinical significance could not be justified in this study.

Quadrant root planing versus same-day full-mouth root planing. III. Dynamics of the immune response

OBJECTIVES

The aim of this study was to determine whether same-day full-mouth scaling and root planing (FM-SRP) and quadrant scaling and root planing (Q-SRP) resulted in variations in the systemic humoral immune response dynamics (antibody titres and avidity) during active treatment and 3 and 6 months post-therapy.

MATERIALS AND METHODS

Forty patients with chronic periodontitis were recruited into this study. Subjects were randomised into two groups and received either scaling and root planing quadrant by quadrant at 2-weekly intervals (Q-SRP group) or same-day full-mouth scaling and root planing (FM-SRP group). Clinical measurements and serum samples were obtained at baseline and approximately 6 weeks after the last clinical intervention (R1) and 6 months after the initiation of therapy (R2). Furthermore, serum samples were obtained from each patient undergoing therapy (Q-SRP and FM-SRP) at 3 bi-weekly instances so as to determine the short-term effects of each session of scaling and root planing on the dynamics of the humoral immune response. Serum antibody titre was assayed by enzyme-linked immunosorbent assay (ELISA) and antibody avidity was measured by thiocyanate dissociation against five putative periodontal pathogens: Porphyromonas gingivalis; Actinobacillus actinomycetemcomitans; Prevotella intermedia; Treponema denticola and Bacteroides forsythus.

RESULTS

Both therapies resulted in similar antibody titre reductions against the majority of the organisms tested and although there was a distinct trend for antibody avidity to increase following therapy, this was not found to be statistically significant, reflecting marked inter-individual variation. In addition, no evidence emerged from this study to support increased antibody titres following the active phases of both treatment approaches due to an inoculation effect. Nevertheless, significant short-term increases in antibody avidity to most test bacteria were noted for both treatment strategies.

CONCLUSION

Both therapies were associated with a reduction in antibody titres and an increase in the binding ability or avidity of antibodies, but there was a marked inter-subject variability and statistical significance was reached for only some of the test bacteria. No significant differences in the humoral antibody dynamics were found between the two treatment approaches.

Immunoglobulin G profiles in different forms of periodontitis

BACKGROUND

Races and Gm(23) allotypes can modify the serum levels of IgG subclasses. The average serum levels of IgG subclasses of African-Americans have been reported to be higher than those of Caucasians in both healthy young adults and patients with aggressive periodontitis; Gm(23)-positive subjects generally had higher IgG2 levels than Gm(23)-negative subjects.

OBJECTIVE

We examined serum immunoglobulin G (IgG) concentrations in Taiwanese patients with different forms of periodontitis.

METHODS

The serum levels of four IgG subclasses were determined by enzyme-linked immunosorbent assay and Gm(23) allotypes were verified by radial immunodiffusion tests in 50 patients with chronic periodontitis, 30 patients with aggressive periodontitis, and 74 healthy controls.

RESULTS

There were no differences in the concentrations of four IgG subclasses in patients with chronic periodontitis compared with age-matched controls. However, in subjects younger than 35 years, levels of IgG2 were significantly elevated in patients with aggressive periodontitis compared with controls. We also found significant differences in IgG2 levels within the control group when stratified by age (< or = 35 years and > 35 years). Gm(23) allotypes were not correlated with the serum levels of IgG2 in either patient group.

CONCLUSION

Microbial challenge might not provoke significant changes in systemic IgG response in patients with chronic periodontitis. However, in patients with aggressive periodontitis, IgG2 levels were increased when compared with age-matched controls. Gm(23) allotypes had no influence on IgG2 levels in well-established generalized chronic periodontitis or aggressive periodontitis.

Serum antibody reactivity against recombinant PrtC of Porphyromonas gingivalis following periodontal therapy

OBJECTIVES

In 34 patients with chronic periodontitis, the presence of IgA, IgG, and IgG subclass serum antibodies against recombinant PrtC (rPrtC) of Porphyromonas gingivalis was assessed by immunoblot analysis 24 months after therapy.

METHODS

rPrtC was produced from P. gingivalis ATTC 33277 using the plasmid pGEX-2T. In addition, intraoral colonization with P. gingivalis was detected by PCR in subgingival plaque and swab samples from buccal mucosae, tonsils and tongue at baseline, 10 d, and 3, 6, 9, 12, 18, and 24 months.

RESULTS

All patients were found to harbor P. gingivalis in the oral cavity at least once during the observation period. The identified antibody responses against the rPrtC of P. gingivalis were IgA (97%, i.e. 33/34 patients) and IgG (100%, i.e. 34/34), with an IgG subclass distribution of IgG2 (65%, i.e. 22/34 patients) > IgG3 (47%, i.e. 16/34) > IgG1 (38%, i.e. 13/34) > IgG4 (29%, i.e. 10/34). Anti-rPrtC IgA and IgG antibody reactivity was found in all but one patients (anti-rPrtC IgA negative), who tested negative for P. gingivalis at all of the assessed intraoral sites for at least 6 months before sera collection. There was no association between IgG subclass reactivity against the rPrtC of P. gingivalis and progression of periodontal attachment loss.

CONCLUSION

The results indicated that anti-rPrtC IgA and IgG antibodies may serve as an indicator for past or present intraoral colonization with P. gingivalis.

Fusobacterium nucleatum impairs serum binding to Porphyromonas gingivalis biofilm

Mouse immune sera obtained by immunization with Fusobacterium nucleatum and then Porphyromonas gingivalis demonstrated an impaired binding capacity to P. gingivalis-biofilm and lower avidity to P. gingivalis when compared with sera obtained from mice immunized with P. gingivalis alone.

Prior exposure of mice to Fusobacterium nucleatum modulates host response to Porphyromonas gingivalis

Multiple periodontal pathogens sequentially colonize the subgingival niche during the conversion from gingivitis to destructive periodontal disease. An animal model of sequential immunization with key periodontal pathogens has been developed to determine whether T- and B-lymphocyte effector functions are skewed and fail to protect the host from pathogenic challenge. The present study was performed to evaluate the immunomodulatory effect of exposure to Fusobacterium nucleatum prior to Porphyromonas gingivalis. Group 1 (control) mice were immunized with phosphate-buffered saline, group 2 were immunized with F. nucleatum prior to P. gingivalis and group 3 were immunized with P. gingivalis alone. All the T-cell clones derived from group 2 demonstrated type 2 helper T-cell clone (Th2 subsets), whereas those from group 3 mice demonstrated Th1 subsets. Exposure of mice to F. nucleatum prior to P. gingivalis interfered with the opsonophagocytosis function of sera against P. gingivalis. In adoptive T-cell transfer experiments, in vivo protective capacity of type 2 helper T-cell clones (Th2) from group 2 was significantly lower than type 1 helper T-cell clones (Th1) from group 3 against the lethal dose infection of P. gingivalis. Western blot analysis indicated a different pattern of recognition of P. gingivalis fimbrial proteins between sera from group 2 and group 3. In conclusion, these studies suggest that exposure of a host to F. nucleatum prior to the periodontal pathogen P. gingivalis modulates the host immune responses to P. gingivalis at the humoral, cellular and molecular levels.

Porphyromonas gingivalis-specific IgG subclass antibody levels as immunological risk indicators of periodontal bone loss

BACKGROUND

It has been well demonstrated a positive association between the magnitude of host antibody response and periodontal disease status. Previous studies also reported that Porphyromonas gingivalis-specific IgG subclass antibodies were elevated in sera from adult periodontitis patients. However, the rôle and the association of these IgG subclass antibodies to the development of periodontal diseases are poorly understood.

AIM

The aim of present investigation was to examine the relation of serum IgG subclass antibody levels and alveolar bone loss in treated and untreated periodontitis patients.

METHODS

Serum samples were taken from 20 treated and maintained periodontitis patients (SPT patients), 30 untreated patients and 19 periodontally healthy subjects. We determined the IgG subclass antibody titers to P. gingivalis whole cells using an enzyme-linked immunosorbent assay (ELISA). Subgingival plaque samples were taken from the mesio-buccal surface of 6 randomly selected teeth of SPT patients and evaluated for the presence of P. gingivalis by immunofluorescence microscopy. Clinical measurements were also taken including full mouth intraoral radiographs to measure interproximal alveolar bone loss at baseline (BLS1) and at a 5-year recall visit in the SPT patients (BLS2).

RESULTS

Our results indicated that both patient groups had detectable levels of IgG1, IgG2, and IgG4. Significantly higher IgG1 was observed in both patient groups compared to the healthy subjects. The untreated patients also exhibited significantly elevated IgG2 response (p<0.05). The mean IgG4 level of the SPT patients was significantly higher compared to the other subject group (p<0.05). A statistically significant positive correlation between IgG2 levels and changes in bone levels (DeltaBLS: BLS2-BLS1) was seen in the SPT patients (p<0.001). SPT patients with high IgG2 and low IgG4 showed greater bone loss than those with low IgG2 and high IgG4 (p<0.05), although the mean prevalence of P. gingivalis in the 2 groups did not differ significantly.

CONCLUSION

Our data suggest that the prolonged IgG2 response after periodontal treatment may be indicative of recurrent or persistent periodontal destruction.

Fimbriae of Porphyromonas gingivalis induce opsonic antibodies that significantly enhance phagocytosis and killing by human polymorphonuclear leukocytes

Porphyromonas gingivalis has been strongly implicated in the pathogenesis of human periodontitis. Fimbriae mediate adherence and colonization of the oral cavity by this organism and may, therefore, have potential for use as antigen in an anti-P. gingivalis vaccine. The purpose of our study was to determine whether P. gingivalis fimbriae have opsonic target sites and whether they are accessible on the cell surfaces and cross-reactive among P. gingivalis fimbrial types and serotypes. Rabbits were immunized with a vaccine. The antiserum reacted with a 43-kDa fimbrillin monomer and a 43-kDa component in whole-cell sonicates of P. gingivalis 33277, but it showed only very weak reactivity in the 43-kDa region of Western blots of a whole-cell sonicate of strain DPG3, a mutant that does not express functional fimbriae. The antibody enhanced chemiluminescence approximately six-fold relative to preimmune serum values and significantly enhanced phagocytosis and killing of P. gingivalis 33277 by human polymorphonuclear leukocytes. Peak opsonic activity was observed at week 6 followed by a plateau that remained until week 16. The fimbria-deficient mutant DPG3 did not bind antifimbrial antibody and was not opsonized, whereas strain 381, the parent of the mutant, was opsonized. The specific antibody bound to and opsonized P. gingivalis strains 33277 and 381 (fimbria type I) but not W50, A7A-1-28, 9-14K-1 or FAY-19M-1 (fimbrial types II-V). Specific antibody bound to strain 2561 (fimbrial type I) but, as assessed by chemiluminescence, did not opsonize it. While fimbriae have opsonic target sites that are accessible on P. gingivalis cell surfaces, the relevant opsonic target sites do not appear to be shared across serotypes or fimbrial types. Thus, a vaccine containing, as antigen, fimbrial protein from a single P. gingivalis strain would likely be ineffective against infections by P. gingivalis strains expressing other fimbrial types.

Identification and characterization of B-cell epitopes of a 53-kDa outer membrane protein from Porphyromonas gingivalis

We have previously reported that Porphyromonas gingivalis FDC 381 possesses a 53-kDa protein antigen (Ag53) on its outer membrane that evokes a strong humoral immune response in many patients with periodontal disease and that the humoral immune responses to Ag53 differ greatly among patients. To understand how the individual humoral immune system against Ag53 was determined, the regions of Ag53 recognized by specific antibody (B-cell epitopes) and dominant subclasses of serum immunoglobulin G (IgG) against major B-cell epitopes were examined by enzyme-linked immunosorbent assay. This study used sera from six patients with periodontitis, which all reacted strongly with sonic extracts of P. gingivalis 381 and with purified Ag53, and sera from six periodontally healthy children, which did not react with either sonic extracts of P. gingivalis 381 or Ag53. The epitopes were identified using synthetic 5-residue overlapping decapeptides covering the entire Ag53. Thirteen of 89 synthetic decapeptides showed a strong reaction with sera from the periodontal patients, but no reaction with those from the healthy children. Four peptides of 13 exerted different immune responses among patients. Furthermore, restriction analyses of the highly antigenic regions revealed that three sequences, RAAIRAS, YYLQ and MSPARR, were identified as major B-cell epitopes. Additionally, these epitopes were recognized mainly by the IgG2 isotype. These data suggest that the difference of B-cell epitopes might influence individual differences in antibody titer against Ag53 and also that the epitopes recognized commonly by multiple antibodies are quite valuable for peptide vaccine development against P. gingivalis infection.

Antigenic cross-reactivity among Porphyromonas gingivalis serotypes

The goal of our research program is to develop a Porphyromonas gingivalis vaccine. Vaccine development requires identification of antigenic components shared by the many clonal types of P. gingivalis. The purpose of the present study was to evaluate the extent and nature of antigenic cross-reactivity among serotypes of P. gingivalis and to identify shared antigenic components. Strains selected to represent serotypes A-D were 33277, A7A1-28 W50 and 381, respectively. Using intact cells, antibodies were raised in rabbits. Titers were assessed by enzyme-linked immunosorbent assay (ELISA) using intact cells as antigen, Western blots were prepared and biologic activity was measured as opsonization (chemiluminescence expressed as mV) and enhancement of phagocytosis and killing by polymorphonuclear leukocytes. Extensive cross-reactivity that varied greatly among serotypes was observed by ELISA. The Western blots showed an even greater extent of cross-reactivity, with shared protein components at approximately 140, 130, 37, 32 and 28 kDa and a shared variable molecular mass smear considered to be lipopolysaccharide and other carbohydrate. Additional protein components at 110, 85, 35 and 20 kDa appeared to be shared by some but not all serotypes. In the functional assays, strains 33277 and 381 were equally well opsonized by anti-33277 and anti-381 (500-650 mV) but opsonized to a much lesser extent by anti-A7A1-28 and anti-W50 (roughly 125 mV and 350 mV respectively). A7A1-28 and W50 were opsonized by all four immune sera almost equally but to a much lower extent (roughly 400 mV and 250 mV respectively). Enhancement of phagocytosis and killing in the presence of active complement mirrored opsonization with the exception that 381 was reasonably well opsonized by anti-A7A1-28 (400 mV) and anti-W50 (350 mV), but poorly killed. The protein components at 140, 130, 37 and 28 kDa shared by all of the four serotypes appear to have potential as vaccine candidate antigens.

"Checkerboard" assessments of periodontal microbiota and serum antibody responses: a case-control study

BACKGROUND

We explored the association between subgingival microbial profiles and serum IgG responses to periodontal microbiota in relation to clinical periodontal status.

METHODS

One hundred thirty-one (131) periodontitis patients aged 29 to 74 years (mean 51.8) were age- and gender-matched with 74 periodontally intact controls (range 26 to 77, mean 49.3). Smoking habits and health history were recorded and assessments of plaque, bleeding on probing, probing depth, and attachment level were performed at 6 sites per tooth on all present teeth, excluding third molars. Subgingival plaque samples were obtained from each tooth in one upper and one lower quadrant (maximum 14 samples/subject; 2,440 samples total) and analyzed with respect to 19 species by means of whole genomic DNA probes. Serum IgG antibodies against the same 19 species were assessed by an immunoassay.

RESULTS

Cases displayed an average of 22.7 teeth, 20.3 sites with probing depth > or =6 mm, and 18.9 sites with attachment loss > or =6 mm. Corresponding figures for controls were 27.1, 0.1, and 1.0, respectively. Heavy smoking was 3 times more frequent among cases than controls (32.1% versus 9.6%). Higher levels of Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia, Prevotella nigrescens, Prevotella melaninogenica, Bacteroides forsythus, Fusobacterium nucleatum, Treponema denticola, Eubacterium nodatum, Peptostreptococcus micros, and Campylobacter rectus were found in cases and higher levels of Eikenella corrodens, Veillonella parvula, and Actinomyces naeslundii in controls. Cases displayed higher IgG levels against P. gingivalis and Actinobacillus actinomycetemcomitans, while controls displayed higher levels against F. nucleatum, T. denticola, E. nodatum, and Capnocytophaga ochracea. Positive correlations between bacterial colonization and antibody responses were identified for 9 species in controls. In cases, however, statistically significant correlations were observed for only 3 species out of which only one was positive (V. parvula). Both bacterial levels and antibody responses declined in ages over 55 years. A logistic regression employing selected elements of bacterial colonization and antibody responses as independent variables resulted in 81.1% correct diagnosis, with sensitivity of 83.1%, specificity of 77.8%, positive predictability of 86%, and negative predictability of 73.7%. Smoking did not reach statistical significance in this model.

CONCLUSION

A combined microbial colonization/antibody response profile can effectively discriminate between periodontitis patients and periodontally intact controls.

Porphyromonas gingivalis induction of mediator and cytokine secretion by human gingival fibroblasts

We hypothesized that bacterial viability and strain characteristics of Porphyromonas gingivalis could affect the induction of pro-inflammatory mediator secretion by human gingival fibroblast cultures. Both killed and viable P. gingivalis elicited production of prostaglandin E2, interleukin-1 beta (IL-1 beta), IL-6 and IL-8, although killed P. gingivalis induced generally higher levels, particularly IL-6 and IL-8, compared with the viable bacteria. P. gingivalis strains, which exhibited wild-type levels of trypsin-like protease activity, stimulated human gingival fibroblasts to secrete increased levels of prostaglandin E2 and IL-1 beta, although minimal levels of IL-6 and IL-8 were noted in supernatants from the gingival fibroblast cells. P. gingivalis strains BEI and NG4B19, which have either decreased or undetectable levels of trypsin-like protease, respectively, induced significantly greater IL-6 and IL-8 levels in gingival fibroblast cultures compared with the other strains. The ability of antibody to P. gingivalis to alter human gingival fibroblast production of pro-inflammatory mediators was tested using nonhuman primate antisera. Both immune and nonimmune sera altered the P. gingivalis-generated pattern of mediators from the gingival fibroblasts. We conclude that: (i) viable and killed P. gingivalis were capable of inducing various pro-inflammatory cytokines from human gingival fibroblasts; (ii) strain differences in cytokine induction were noted, and the expression of a trypsin-like protease activity was related to decreased extracellular levels of IL-6 and IL-8; and (iii) the presence of serum, particularly with specific antibody to P. gingivalis, significantly altered human gingival fibroblast cytokine production compared with P. gingivalis alone.

Serum immunoglobulin G (IgG) and IgG subclass responses to the RgpA-Kgp proteinase-adhesin complex of Porphyromonas gingivalis in adult periodontitis

Serum immunoglobulin G (IgG), IgM, and IgG subclass responses to the RgpA-Kgp proteinase-adhesin complex of Porphyromonas gingivalis were examined by enzyme-linked immunosorbent assay using adult periodontitis patients and age- and sex-matched controls. Twenty-five sera from subjects with adult periodontitis (diseased group) and 25 sera from healthy subjects (control group) were used for the study. Sera and subgingival plaque samples from 10 sites were collected from each patient at the time of clinical examination. The level of P. gingivalis in the plaque samples was determined using a DNA probe. Highly significant positive associations between the percentage of sites positive for P. gingivalis and measures of disease severity (mean pocket depth, mean attachment loss, and percentage of sites that bled on probing) were found. The diseased group had significantly higher specific IgG responses to the RgpA-Kgp complex than did the control group, and the responses were significantly associated with mean probing depths and percentage of sites positive for P. gingivalis. Analysis of the IgG subclass responses to the RgpA-Kgp complex revealed that the subclass distribution for both the diseased and control groups was IgG4 > IgG2 > IgG3 = IgG1. The IgG2 response to the complex was positively correlated with mean probing depth, whereas the IgG4 response was negatively correlated with this measure of disease severity. Immunoblot analysis of the RgpA-Kgp complex showed that sera from healthy subjects and those with low levels of disease, with high IgG4 and low IgG2 responses, reacted with the RgpA27, Kgp39, and RgpA44 adhesins; however, sera from diseased subjects with low IgG4 and high IgG2 responses reacted only with the RgpA44 and/or Kgp44 adhesins. Epitope mapping of the RgpA27 adhesin localized a major epitope recognized by IgG4 antibodies in sera from subjects with high IgG4 and low IgG2 responses to the RgpA-Kgp complex which was not recognized by sera from diseased subjects with low IgG4 and high IgG2 responses.

The molecular cloning, nucleotide sequence and expression of an antigenic determinant from Porphyromonas gingivalis

A genomic library generated in Escherichia coli was probed with a monoclonal antibody (mAb) LDS28, which reacts with a species-specific cell-surface antigen of Porphyromonas gingivalis. A clone designated pGPR2.1 was shown to express a 46-kDa protein reactive with mAb LDS28, which maps to a 1.7-kb HincII fragment. DNA sequence analysis revealed pGPR2.1 contains a 5653-bp insert with six open reading frames, one of which shows significant DNA homology with the rnhB gene of E. coli. Several subclones of pGPR2.1 were randomly generated in plasmid vector pTTQ18* using restriction enzyme Sau3a. Immunoblotting of subclones demonstrated that the LDS28-reactive antigen was coded for by an open reading frame predicted to specify a protein of 455 amino acids (50 kDa). This open reading frame was designated pgaA (Porphyromonas gingivalis antigen). The predicted amino acid sequence of PgaA contains a putative ABC signature for binding NTPs as well as a predicted transmembrane domain. Minicell labelling of pGPR2.1-encoded proteins and subclone derivatives revealed that pgaA directs expression of protein of multiple molecular weights (31-46 kDa) from its own promoter in E. coli, and that some of these forms may be caused by proteolysis of a 50-kDa precursor which itself shows a reduced apparent molecular weight (46 kDa) on sodium dodecyl sulphate-polyacrylamide gel electrophoresis.

Antibody reactive with Porphyromonas gingivalis serotypes K1-6 in adult and generalized early-onset periodontitis

BACKGROUND

Six serotypes of Porphyromonas gingivalis have recently been described. We sought to test the hypothesis that serotype specific carbohydrates from these strains are important antigens that elicit potent immune responses.

METHODS

Serum concentrations of IgG reactive with P. gingivalis serotypes K1-K6 were determined for 28 adult (AP) and 28 generalized early-onset (G-EOP) periodontitis patients previously determined to be seropositive for a broken cell preparation of P. gingivalis. To confirm relationships suggested for K1, K2, and K6 in the analysis of initial data, the study population was increased to 133.

RESULTS

Frequency of seropositivity for the 6 serotypes ranged from 26 to 54% of subjects. IgG concentrations ranged from 0 to 453 microg/ml with many subjects seropositive to more than one serotype. Concentrations for the subset of patients who was seropositive were high (mean responses ranged from 20 to 105 microg/ml for the 6 serotypes). Significant correlations between seropositivity to serotypes K1 and K5 as well as between K5 and K6 were found.

CONCLUSIONS

We examined the relationship of diagnosis, race, gender, smoking, probing depth, attachment loss, and antibody reaction with the P. gingivalis serotypes by analysis of variance. Initial findings suggested potential relationships between diagnosis, smoking, race, gender, and antibody reactive with serotypes K1, K2, and K6. A significant relationship did exist between smoking and decreased antibody reactive with P. gingivalis serotype K2. No other relationships were substantiated. We also examined the IgG subclass distribution and found that responses were almost exclusively IgG2. These data support the concept that antibody responses to all 6 serotypes are common in both AP and G-EOP and that these K serotype carbohydrates elicit potent IgG2 responses.