Serum antibodies to oral Bacteroides asaccharolyticus (Bacteroides gingivalis): relationship to age and periondontal disease

The role of acquired host immunity in periodontal diseases

The aim of this narrative review is to relate the contribution of European researchers to the complex topic of the host immune system in periodontal disease, focusing on acquired immunity. Other chapters in this volume will address the genetics and autoantibody responses and other forms of immunity to periodontal disease. While the contribution of European authors is the focus, global literature is included in this descriptive narrative for contextual clarity, albeit many with European co-authors. The topic is relatively intense and is thus broken down into sections outlined below, tackled as descriptive narratives to enhance understanding. Any attempt at a systematic or scoping review was quickly abandoned given the descriptive nature and marked variation of approach in almost all publications. Even the most uniform area of this acquired periodontal immunology literature, antibody responses to putative pathogens in periodontal diseases, falls short of common structures and common primary outcome variables one would need and expect in clinical studies, where randomized controlled clinical trials (RCTs) abound. Addressing 'the host's role' in immunity immediately requires a discussion of host susceptibility, which necessitates consideration of genetic studies (covered elsewhere in the volume and superficially covered here).

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.

Deposition of Immune Complexes in Gingival Tissues in the Presence of Periodontitis and Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a complex chronic autoimmune disease characterized by tissue damage and widespread inflammation in response to environmental challenges. Deposition of immune complexes in kidneys glomeruli are associated with lupus nephritis, determining SLE diagnosis. Periodontitis is a chronic inflammatory disease characterized by clinical attachment and bone loss, caused by a microbial challenge - host response interaction. Deposition of immune complex at gingival tissues is a common finding in the course of the disease. Considering that, the primary aim of this study is to investigate the deposition of immune complexes at gingival tissues of SLE patients compared to systemically healthy ones, correlating it to periodontal and systemic parameters. Twenty-five women diagnosed with SLE (SLE+) and 25 age-matched systemically healthy (SLE-) women were included in the study. Detailed information on overall patient's health were obtained from file records. Participants were screened for probing depth (PD), clinical attachment loss (CAL), gingival recession (REC), full-mouth bleeding score (FMBS) and plaque scores (FMPS). Bone loss was determined at panoramic X-ray images as the distance from cementenamel junction to alveolar crest (CEJ-AC). Gingival biopsies were obtained from the first 15 patients submitted to surgical periodontal therapy of each group, and were analyzed by optical microscopy and direct immunofluorescence to investigate the deposition of antigen-antibody complexes. Eleven (44%) patients were diagnosed with active SLE (SLE-A) and 14 (56%) with inactive SLE (LES-I). Mean PD, CAL and FMBS were significantly lower in SLE+ than SLE-(p < 0.05; Mann Whitney). The chronic use of low doses of immunosuppressants was associated with lower prevalence of CAL >3 mm. Immunofluorescence staining of markers of lupus nephritis and/or proteinuria was significantly increased in SLE+ compared to SLE-, even in the presence of periodontitis. These findings suggest that immunomodulatory drugs in SLE improves periodontal parameters. The greater deposition of antigen-antibody complexes in the gingival tissues of patients diagnosed with SLE may be a marker of disease activity, possibly complementing their diagnosis.

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.

Robert J. Genco: Pioneer in Oral Science Advancement

Professor Robert J. Genco made extraordinary research advances in immunology, periodontology, and microbiology research, pioneering major advances in oral science. In addition to his extraordinary research advancements in oral biology, his pioneering advances in oral science leadership at the local/university, national, and international levels are recognized worldwide, as are his educational advancements. In his era, he is truly the "father" of oral science.

Ageing effects on humoral immune responses in chronic periodontitis

Periodontal disease is a dominant global bacterial infection that increases with ageing.

AIM

This report focuses on host adaptive immune responses in periodontitis. While experimental models and humans diagnosed with periodontitis demonstrate an antigenic specificity for particular oral bacteria, we have a limited understanding of (i) how ageing affects the adaptive immune responses to these bacteria that chronically colonize the oral cavity for decades prior to disease expression and (ii) how the magnitude and specificity of the response interface with pathogens that emerge within the bacterial ecology during exacerbations of disease.

MATERIALS AND METHODS

Serum antibody levels to a group of pathogenic and commensal oral bacteria were measured in a population of individuals from 21 to 74 years of age, stratified based on clinical status of the periodontium, smoking and sex.

RESULTS

Clinical parameters were not significantly different within health, gingivitis or periodontitis groups related to age. Antibody to oral pathogens and commensals was similar in different age groups in each of the clinical categories, with no age correlation noted in the periodontitis patients.

CONCLUSIONS

The adaptive immune responses to oral bacteria that chronically colonize the oral cavity appear generally unaffected by age, but clearly are linked to the extent of disease.

Transcriptome Analysis of B Cell Immune Functions in Periodontitis: Mucosal Tissue Responses to the Oral Microbiome in Aging

Evidence has shown activation of T and B cells in gingival tissues in experimental models and in humans diagnosed with periodontitis. The results of this adaptive immune response are noted both locally and systemically with antigenic specificity for an array of oral bacteria, including periodontopathic species, e.g., Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans. It has been recognized through epidemiological studies and clinical observations that the prevalence of periodontitis increases with age. This report describes our studies evaluating gingival tissue transcriptomes in humans and specifically exploiting the use of a non-human primate model of naturally occurring periodontitis to delineate gingival mucosal tissue gene expression profiles focusing on cells/genes critical for the development of humoral adaptive immune responses. Patterns of B cell and plasmacyte genes were altered in aging healthy gingival tissues. Substantial increases in a large number of genes reflecting antigen-dependent activation, B cell activation, B cell proliferation, and B cell differentiation/maturation were observed in periodontitis in adults and aged animals. Finally, evaluation of the relationship of these gene expression patterns with those of various tissue destructive molecules (MMP2, MMP9, CTSK, TNFα, and RANKL) showed a greater frequency of positive correlations in healthy tissues versus periodontitis tissues, with only MMP9 correlations similar between the two tissue types. These results are consistent with B cell response activities in healthy tissues potentially contributing to muting the effects of the tissue destructive biomolecules, whereas with periodontitis this relationship is adversely affected and enabling a progression of tissue destructive events.

Learned and unlearned concepts in periodontal diagnostics: a 50-year perspective

In the past 50 years, conceptual changes in the field of periodontal diagnostics have paralleled those associated with a better scientific understanding of the full spectrum of processes that affect periodontal health and disease. Fifty years ago, concepts regarding the diagnosis of periodontal diseases followed the classical pathology paradigm. It was believed that the two basic forms of destructive periodontal disease were chronic inflammatory periodontitis and 'periodontosis'- a degenerative condition. In the subsequent 25 years it was shown that periodontosis was an infection. By 1987, major new concepts regarding the diagnosis and pathogenesis of periodontitis included: (i) all cases of untreated gingivitis do not inevitably progress to periodontitis; (ii) progression of untreated periodontitis is often episodic; (iii) some sites with untreated periodontitis do not progress; (iv) a rather small population of specific bacteria ('periodontal pathogens') appear to be the main etiologic agents of chronic inflammatory periodontitis; and (v) tissue damage in periodontitis is primarily caused by inflammatory and immunologic host responses to infecting agents. The concepts that were in place by 1987 are still largely intact in 2012. However, in the decades to come, it is likely that new information on the human microbiome will change our current concepts concerning the prevention, diagnosis and treatment of periodontal diseases.

Cleavage of IgG1 in gingival crevicular fluid is associated with the presence of Porphyromonas gingivalis

BACKGROUND AND OBJECTIVES

Immunoglobulin (Ig) G1 plays an important role in the adaptive immune response. Kgp, a lysine-specific cysteine protease from Porphyromonas gingivalis, specifically hydrolyses IgG1 heavy chains. The purpose of this study was to examine whether cleavage of IgG1 occurs in gingival crevicular fluid (GCF) in vivo, and whether there is any association with the presence of Porphyromonas gingivalis and other periodontopathogens.

MATERIAL AND METHODS

GCF was obtained from nine patients with aggressive periodontitis, nine with chronic periodontitis and five periodontally healthy individuals. The bacterial loads of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Treponema denticola, Prevotella intermedia and Tannerella forsythia were analysed by real-time polymerase chain reaction, and the presence and cleavage of IgG1 and IgG2 were determined using Western blotting. Kgp levels were measured by ELISA.

RESULTS

Cleaved IgG1 was identified in the GCF from 67% of patients with aggressive periodontitis and in 44% of patients with chronic periodontitis. By contrast, no cleaved IgG1 was detectable in healthy controls. No degradation of IgG2 was detected in any of the samples, regardless of health status. Porphyromonas gingivalis was found in high numbers in all samples in which cleavage of IgG1 was detected (P < 0.001 compared with samples with no IgG cleavage). Furthermore, high numbers of Tannerella forsythia and Prevotella intermedia were also present in these samples. The level of Kgp in the GCF correlated with the load of Porphyromonas gingivalis (r = 0.425, P < 0.01). The presence of Kgp (range 0.07-10.98 ng/mL) was associated with proteolytic fragments of IgG1 (P < 0.001). However, cleaved IgG1 was also detected in samples with no detectable Kgp.

CONCLUSION

In patients with periodontitis, cleavage of IgG1 occurs in vivo and may suppress antibody-dependent antibacterial activity in subgingival biofilms especially those colonized by Porphyromonas gingivalis.

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

BACKGROUND

Chronic inflammation in periodontal disease has been suggested as a potential risk factor in Alzheimer's disease (AD). The purpose of this study was to examine serum antibody levels to bacteria of periodontal disease in participants who eventually converted to AD compared with the antibody levels in control subjects.

METHODS

Serum samples from 158 participants in the Biologically Resilient Adults in Neurological Studies research program at the University of Kentucky were analyzed for immunoglobulin G antibody levels to seven oral bacteria associated with periodontitis, including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Campylobacter rectus, Treponema denticola, Fusobacterium nucleatum, Tannerella forsythia, and Prevotella intermedia. All 158 participants were cognitively intact at baseline venous blood draw. In all, 81 of the participants developed either mild cognitive impairment (MCI) or AD or both, and 77 controls remained cognitively intact in the years of follow-up. Antibody levels were compared between controls and subjects with AD at baseline draw and after conversion and controls and subjects with MCI at baseline draw and after conversion using the Wilcoxon rank-sum test. AD and MCI participants were not directly compared. Linear regression models were used to adjust for potential confounding.

RESULTS

Antibody levels to F nucleatum and P intermedia were significantly increased (α = 0.05) at baseline serum draw in the patients with AD compared with controls. These results remained significant when controlling for baseline age, Mini-Mental State Examination score, and apolipoprotein epsilon 4 status.

CONCLUSIONS

This study provides initial data that demonstrate elevated antibodies to periodontal disease bacteria in subjects years before cognitive impairment and suggests that periodontal disease could potentially contribute to the risk of AD onset/progression. Additional cohort studies profiling oral clinical presentation with systemic response and AD and prospective studies to evaluate any cause-and-effect association are warranted.

The formation of immune complexes is involved in the acute phase of periodontal destruction in rats

BACKGROUND AND OBJECTIVE

Loss of clinical attachment and alveolar bone destruction are major symptoms of periodontitis, caused by not only the destructive effect of periodontopathic bacteria but also the overactive response of the host immune system against periodontal pathogens. The details of the participation of the immune system in the onset and progression of periodontitis are unclear. In this study, we attempted to determine whether the host immune system, and in particular the formation of immune complexes, is involved in the periodontal destruction.

MATERIAL AND METHODS

We applied ovalbumin or lipopolysaccharide (LPS) as antigens and their specific immunoglobulin G (IgG) antibodies purified from rat serum to rat gingival sulcus alternately. Loss of attachment, alveolar bone destruction and the numbers of inflammatory cells infiltrating the periodontal tissue and osteoclasts on the alveolar bone surface were investigated histometrically. The formation of immune complex was confirmed by immunohistological staining of complement C1qB.

RESULTS

Loss of attachment and the presence of C1qB were observed histopathologically in both experimental groups. The group that had been treated with LPS and anti-LPS IgG showed greater loss of attachment. The number of inflammatory cells in the periodontal tissue was increased in both experimental groups, while osteoclasts at the alveolar bone crest were observed only in the group that had been treated with LPS and anti-LPS IgG.

CONCLUSION

In the present study, we showed that the formation of immune complex appears to be involved in the acute phase of periodontal destruction and that the biological activity of antigens is also important.

Bacterial-killing effect of atmospheric pressure non-equilibrium plasma jet and oral mucosa response

Recently, plasma sterilization has attracted increasing attention in dental community for the atmospheric pressure non-equilibrium plasma jet (APNPs), which is driven by a kilohertz pulsed DC power, may be applied to the dental and oral diseases. However, it is still in doubt whether APNPs can effectively kill pathogenic bacteria in the oral cavity and produce no harmful effects on normal oral tissues, especially on normal mucosa. The aim of this study was to evaluate the bacterial-killing effect of APNPs in the biofilms containing a single breed of bacteria (Porphyromonas gingivalis, P.g.), and the pathological changes of the oral mucosa after treatment by APNPs. P.g. was incubated to form the biofilms in vitro, and the samples were divided into three groups randomly: group A (blank control); group B in which the biofilms were treated by APNPs (the setting of the equipment: 10 kHz, 1600 ns and 8 kV); group C in which the biofilms were exposed only to a gas jet without ignition of the plasma. Each group had three samples and each sample was processed for up to 5 min. The biofilms were then fluorescently stained, observed and photographed under a laser scanning confocal microscope. In the animal experiment, six male Japanese white rabbits were divided into two groups randomly (n=3 in each group) in terms of the different post-treatment time (1-day group and 5-day group). The buccal mucosa of the left side and the mucosa of the ventral surface of the tongue were treated by APNPs for 10 min in the same way as the bacterial biofilm experiment in each rabbit, and the corresponding mucosa of the other sides served as normal control. The clinical manifestations of the oral mucosa were observed and recorded every day. The rabbits were sacrificed one or five day(s) after APNPs treatment. The oral mucosa were harvested and prepared to haematoxylin and eosin-stained sections. Clinical observation and histopathological scores were used to assess mucosal changes. The results showed the obvious P.g. biofilms were formed at 10 days, and most of the bacteria in groups A and C were alive under a laser scanning confocal microscope, but the bacteria in the group B were almost all dead. In animal experiment, no ulcers, anabrosis and oral mucositis were found in both the 1-day and 5-day groups. The average mucous membrane irritation index was -0.83 and -0.67 in the 1-day and 5-day groups, respectively, suggesting that no intense mucosal membrane irritation responses occurred. It was concluded that APNPs could effectively kill P.g. in the biofilms and did not cause any pathological changes in the normal mucosa, suggesting that the plasma jet (APNPs) may be applied to oral diseases as a novel sterilization device in the future.

Can oral pathogens influence allergic disease?

The hygiene hypothesis contends that fewer opportunities for infections and microbial exposures have resulted in more widespread asthma and atopic disease. Consistent with that hypothesis, decreases in infectious oral diseases over the past half century have coincided with increases in the prevalence of asthma and other allergic diseases. This observation has led some researchers to speculate that exposures to oral bacteria, including pathogens associated with periodontal diseases, such as gingivitis and periodontitis, might play a protective role in the development of asthma and allergy. Colonization of the oral cavity with bacteria, including some species of periodontal pathogens, begins shortly after birth, and the detection of serum antibodies to oral pathogens in early childhood provides evidence of an early immune response to these bacteria. Current knowledge of the immune response to oral bacteria and the immunologic pathogenesis of periodontal diseases suggests biologically plausible mechanisms by which oral pathogens could influence the risk of allergic disease. However, studies investigating the association between oral pathogen exposures and allergic disease are few in number and limited by cross-sectional or case-control design, exclusion of young children, and use of surrogate measures of oral bacterial colonization. Additional studies, particularly well-designed case-control studies among very young children and prospective birth cohort studies, are needed.

Selective serotonin reuptake inhibitors attenuate the antigen presentation from dendritic cells to effector T lymphocytes

Fluoxetine, one of the selective serotonin reuptake inhibitors (SSRIs), has been found to possess immune modulation effects, in addition to its antidepressant effects. However, it remains unclear whether SSRIs can suppress the antigen-presenting function of dendritic cells (DCs). Therefore, Fluoxetine was applied to a co-culture of Aggregatibacter actinomycetemcomitans (Aa)-reactive T cells (×Aa-T) isolated from Aa-immunized mice and DCs. This resulted in the suppressed proliferation of ×Aa-T stimulated with Aa-antigen presentation by DCs. Specifically, Fluoxetine increased the extracellular 5-hydroxytryptamine (5-HT) in the ×Aa-T/DC co-culture, whereas exogenously applied 5-HT promoted T-cell proliferation in the ×Aa-T/DC co-culture, indicating that Fluoxetine-mediated suppression of ×Aa-T/DC responses cannot be attributed to extracellular 5-HT. Instead, Fluoxetine remarkably suppressed the expression of costimulatory molecule ICOS-L on DCs. Fluoxetine also promoted a greater proportion of CD86(Low) immature DCs than CD86(High) mature DCs, while maintaining the expression levels of CD80, MHC-class-II and PD-L1. These results suggested that Fluoxetine suppressed the ability of DCs to present bacterial antigens to T cells, and the resulting T-cell proliferation, in a SERT/5-HT-independent manner and that diminished expression of ICOS-L on DCs and increase of CD86(Low) immature DCs caused by Fluoxetine might be partially associated with Fluoxetine-mediated suppression of DC/T-cell responses.

Immune response of macrophages from young and aged mice to the oral pathogenic bacterium Porphyromonas gingivalis

Periodontal disease is a chronic inflammatory gum disease that in severe cases leads to tooth loss. Porphyromonas gingivalis (Pg) is a bacterium closely associated with generalized forms of periodontal disease. Clinical onset of generalized periodontal disease commonly presents in individuals over the age of 40. Little is known regarding the effect of aging on inflammation associated with periodontal disease. In the present study we examined the immune response of bone marrow derived macrophages (BMM) from young (2-months) and aged (1-year and 2-years) mice to Pg strain 381. Pg induced robust expression of cytokines; tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10, chemokines; neutrophil chemoattractant protein (KC), macrophage colony stimulating factor (MCP)-1, macrophage inflammatory protein (MIP)-1α and regulated upon activation normal T cell expressed and secreted (RANTES), as well as nitric oxide (NO, measured as nitrite), and prostaglandin E2 (PGE2) from BMM of young mice. BMM from the 2-year age group produced significantly less TNF-α, IL-6 and NO in response to Pg as compared with BMM from 2-months and 1-year of age. We did not observe any difference in the levels of IL-1β, IL-10 and PGE2 produced by BMM in response to Pg. BMM from 2-months and 1-year of age produced similar levels of all chemokines measured with the exception of MCP-1, which was reduced in BMM from 1-year of age. BMM from the 2-year group produced significantly less MCP-1 and MIP-1α compared with 2-months and 1-year age groups. No difference in RANTES production was observed between age groups. Employing a Pg attenuated mutant, deficient in major fimbriae (Pg DPG3), we observed reduced ability of the mutant to stimulate inflammatory mediator expression from BMMs as compared to Pg 381, irrespective of age. Taken together these results support senescence as an important facet of the reduced immunological response observed by BMM of aged host to the periodontal pathogen Pg.

Role of periodontal pathogenic bacteria in RANKL-mediated bone destruction in periodontal disease

Accumulated lines of evidence suggest that hyperimmune responses to periodontal bacteria result in the destruction of periodontal connective tissue and alveolar bone. The etiological roles of periodontal bacteria in the onset and progression of periodontal disease (PD) are well documented. However, the mechanism underlying the engagement of periodontal bacteria in RANKL-mediated alveolar bone resorption remains unclear. Therefore, this review article addresses three critical subjects. First, we discuss earlier studies of immune intervention, ultimately leading to the identification of bacteria-reactive lymphocytes as the cellular source of osteoclast-induction factor lymphokine (now called RANKL) in the context of periodontal bone resorption. Next, we consider (1) the effects of periodontal bacteria on RANKL production from a variety of adaptive immune effector cells, as well as fibroblasts, in inflamed periodontal tissue and (2) the bifunctional roles (upregulation vs. downregulation) of LPS produced from periodontal bacteria in a RANKL-induced osteoclast-signal pathway. Future studies in these two areas could lead to new therapeutic approaches for the management of PD by down-modulating RANKL production and/or RANKL-mediated osteoclastogenesis in the context of host immune responses against periodontal pathogenic bacteria.

Determinants of serum IgG responses to periodontal bacteria in a nationally representative sample of US adults

AIM

To assess the distribution of elevated antibody titres to multiple periodontal bacteria, including established/putative pathogens and health-related species, by selected demographic, behavioural, and oral- and general health-related characteristics.

METHODS

Data from 8153 >or=40-year-old participants from the third National Health and Nutrition Examination Survey were used, including 1588 edentulous individuals. We used checkerboard immunoblotting to assess serum IgG levels to 19 periodontal species. Thresholds for elevated antibody responses were defined for each species using the 90th percentile titre in periodontal healthy participants, using two alternative definitions of periodontitis.

RESULTS

Edentulous individuals showed lower antibody responses than dentate participants, notably for titres to "red complex" species and Actinobacillus actinomycetemcomitans. Elevated titres to Porphyromonas gingivalis were twice as prevalent in participants with periodontitis than in periodontal healthy individuals. Non-Hispanic blacks and Mexican-Americans were more likely to display elevated titres for P. gingivalis compared with non-Hispanic whites (22.9%versus 19.4%versus 9.5%). Current smokers were significantly less likely to exhibit high titres to multiple bacteria than never smokers.

CONCLUSION

Demographic, behavioural, and oral- and general health-related characteristics were strong determinants of systemic antibody responses to periodontal bacteria in a nationally representative sample of US adults.

B cells as under-appreciated mediators of non-auto-immune inflammatory disease

B lymphocytes play roles in many auto-immune diseases characterized by unresolved inflammation, and B cell ablation is proving to be a relatively safe, effective treatment for such diseases. B cells function, in part, as important sources of regulatory cytokines in auto-immune disease, but B cell cytokines also play roles in other non-auto-immune inflammatory diseases. B cell ablation may therefore benefit inflammatory disease patients in addition to its demonstrated efficacy in auto-immune disease. Current ablation drugs clear both pro- and anti-inflammatory B cell subsets, which may unexpectedly exacerbate some pathologies. This possibility argues that a more thorough understanding of B cell function in human inflammatory disease is required to safely harness the clinical promise of B cell ablation. Type 2 diabetes (T2D) and periodontal disease (PD) are two inflammatory diseases characterized by little autoimmunity. These diseases are linked by coincident presentation and alterations in toll-like receptor (TLR)-dependent B cell cytokine production, which may identify B cell ablation as a new therapy for co-affected individuals. Further analysis of the role B cells and B cell cytokines play in T2D, PD and other inflammatory diseases is required to justify testing B cell depletion therapies on a broader range of patients.

Human gingival fibroblasts are critical in sustaining inflammation in periodontal disease

BACKGROUND AND OBJECTIVE

A major factor in the pathogenesis of periodontal disease, which is one of the biofilm infectious diseases, is thought to be lipopolysaccharide (LPS), owing to its ability to cause inflammation and promote tissue destruction. Moreover, the elimination of pathogens and their component LPSs is essential for the successful treatment of periodontal disease. Lipopolysaccharide tolerance is a mechanism that prevents excessive and prolonged responses of monocytes and macrophages to LPS. Since persistence of inflammation is necessary for inflammatory cytokine production, cells other than monocytes and macrophages are thought to maintain the production of cytokines in the presence of LPS. In this study, we investigated whether human gingival fibroblasts (HGFs), the most abundant structural cell in periodontal tissue, might be able to maintain inflammatory cytokine production in the presence of LPS bynot displaying LPS tolerance.

MATERIAL AND METHODS

Human gingival fibroblasts were pretreated with LPS (from Porphyromonas gingivalis and Escherichia coli) and then treated with LPS, and the amounts of interleukin (IL)-6 and IL-8 in the cell culture supernatants were measured. The expression of negative regulators of LPS signalling (suppressor of cytokine signalling-1, interleukin-1 receptor-associated-kinase M and SH2 domain-containing inositol-5-phosphatase-1) was also examined in LPS-treated HGFs.

RESULTS

Human gingival fibroblasts did not display LPS tolerance but maintained production of IL-6 and IL-8 when pretreated with LPS, followed by secondary LPS treatment. Lipopolysaccharide-treated HGFs did not express negative regulators.

CONCLUSION

These results demonstrate that HGFs do not show LPS tolerance and suggest that this characteristic of HGFs sustains the inflammatory response in the presence of virulence factors.

Neutrophils in chronic and aggressive periodontitis in interaction with Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans

BACKGROUND AND OBJECTIVE

This study analyzed the interaction of Porphyromonas gingivalis ATCC 33277 and Aggregatibacter actinomycetemcomitans Y4 with peripheral blood polymorphonuclear neutrophils taken from patients with aggressive periodontitis and chronic periodontitis.

MATERIAL AND METHODS

Peripheral blood polymorphonuclear neutrophils obtained from 12 patients with chronic periodontitis, six patients with aggressive periodontitis and 12 healthy controls were exposed to P. gingivalis and A. actinomycetemcomitans following opsonization of the bacteria using the patient's own serum. Serum immunoglobulin G (IgG) levels against both periodontopathogens were measured. Phagocytosis and killing of the bacteria, as well as the extracellular human neutrophil elastase activity, were quantified. The total amount and the extracellular release of reactive oxygen species were measured using luminol-dependent and isoluminol-dependent chemiluminescence.

RESULTS

Polymorphonuclear neutrophils from patients with chronic (62.16 +/- 19.39%) and aggressive (43.26 +/- 26.63%) periodontitis phagocytosed more P. gingivalis than the healthy controls (24.43 +/- 19.87%) at the 30-min time point after exposure to the bacteria (p < 0.05). High serum IgG levels against P. gingivalis and A. actinomycetemcomitans were detected in subjects with periodontitis. Polymorphonuclear neutrophils from subjects with chronic and aggressive periodontitis released significantly more reactive oxygen species and demonstrated greater human neutrophil elastase activity in the absence of any stimulus than polymorphonuclear neutrophils from healthy controls (p < 0.05). Polymorphonuclear neutrophils in chronic periodontitis released significantly more reactive oxygen species when exposed to P. gingivalis and A. actinomycetemcomitans than polymorphonuclear neutrophils in aggressive periodontitis.

CONCLUSION

High serum IgG levels against P. gingivalis and A. actinomycetemcomitans promote phagocytosis in periodontitis. The extracellular release of reactive oxygen species and neutrophil elastase by polymorphonuclear neutrophils may also contribute to damage of the surrounding periodontal tissues.

Mechanisms of resistance of Porphyromonas gingivalis to killing by serum complement

The complement system plays an important role in the host defense against infection, and the formation of the terminal complement complex on the bacterial surface has been shown to be particularly important in killing of gram-negative bacteria. The gram-negative periodontal pathogen Porphyromonas gingivalis is resistant to complement killing, and possible mechanisms suggested for this resistance include protease production and capsule formation. In this study, P. gingivalis Arg- and Lys-gingipain deletion mutants and polysaccharide synthesis deletion mutants have been used to investigate these hypotheses. When Arg- and Lys-gingipain protease mutants were incubated in 20% normal human serum, deposition of complement components on the cell surface was significantly increased compared to that for the wild-type organism. However, despite the increased deposition, the protease mutants maintained resistance to killing and their viability was equal to that seen with heat-inactivated serum. Similar data were obtained when the wild-type organism was treated with gingipain protease inhibitors. K-antigen expression mutants were also resistant to killing. However, mutants which no longer synthesized a surface anionic polysaccharide (APS) (a phosphorylated branched mannan) were extremely sensitive to serum killing. These mutants lack the organized dense glycan surface layer present on the parent strain on the basis of electron microscopy. We conclude that the production of APS at the surface of P. gingivalis rather than Arg- and Lys-gingipain synthesis is the principal mechanism of serum resistance in P. gingivalis.

Oral pathogens and allergic disease: results from the Third National Health and Nutrition Examination Survey

BACKGROUND

The hygiene hypothesis contends that fewer opportunities for infection have led to increases in the prevalences of asthma and other allergic diseases.

OBJECTIVE

This study evaluated the association between asthma, wheeze, and hay fever and antibodies to 2 oral bacteria associated with periodontal disease.

METHODS

Data were obtained from the Third National Health and Nutrition Examination Survey. Serum levels of IgG antibodies to Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were quantified by enzyme-linked immunoassays in 9385 subjects age 12 years and older. The outcomes were current asthma, wheeze, and hay fever. Odds ratios (ORs) representing a 1-log-unit increase in IgG concentrations were estimated with logistic regression. ORs were adjusted for 8 confounders and weighted to represent the US population.

RESULTS

For each disease outcome, geometric mean antibody concentrations were higher in persons without the disease outcome than with the disease outcome. For a 1-log-unit increase in P gingivalis antibody concentration, adjusted ORs were 0.41 (95% CI, 0.20-0.87) for asthma, 0.43 (0.23-0.78) for wheeze, and 0.45 (0.23-0.93) for hay fever. For A actinomycetemcomitans, those ORs were 0.56 (0.19-1.72), 0.39 (0.17-0.86), and 0.48 (0.23-1.03), respectively.

CONCLUSION

Consistent with the hygiene hypothesis, higher concentrations of IgG antibodies to P gingivalis were significantly associated with lower prevalences of asthma, wheeze, and hay fever, and higher concentrations of IgG antibodies to A actinomycetemcomitans were significantly associated with a lower prevalence of wheeze.

CLINICAL IMPLICATIONS

Colonization of the oral cavity by bacteria and other microbes might play a protective role in the etiology of allergic disease.

Antibody response after single-visit full-mouth ultrasonic debridementversusquadrant-wise therapy

INTRODUCTION

The aim of this study was to compare serum antibody responses to periodontal pathogens after single-visit full-mouth ultrasonic debridement and quadrant-wise therapy.

MATERIAL AND METHODS

Thirty-six subjects with chronic periodontitis were randomized into three groups: quadrant-wise debridement in four visits, one-visit full-mouth debridement with water and with povidone iodine. Blood samples were collected before and immediately after treatment and 1, 3 and 6 months post-therapy. Serum antibody titres and avidity to Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Prevotella intermedia and Treponema denticola were determined by enzyme-linked immunosorbent assay (ELISA) and thiocyanate ELISA, respectively.

RESULTS

IgG titres to P. gingivalis significantly decreased at 1, 3 and 6 months in full-mouth debridement with water group, while significant reductions were seen only at 3 and 6 months after quadrant-wise debridement. Both full-mouth groups showed significant reduction in IgG titres to A. actinomycetemcomitans at 3 and 6 months. Significant increases in antibody avidity to P. gingivalis and A. actinomycetemcomitans were noted 3 months following full-mouth debridement with povidone.

CONCLUSION

Both full-mouth and quadrant treatments generally resulted in a decrease in antibody titres and increase in antibody avidity. Full-mouth debridement induced an earlier reduction of IgG titre to P. gingivalis and A. actinomycetemcomitans, than quadrant-wise therapy.

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.

Role of oxyR in the oral anaerobe Porphyromonas gingivalis

Porphyromonas gingivalis is an anaerobic microorganism that inhabits the oral cavity, where oxidative stress represents a constant challenge. A putative transcriptional regulator associated with oxidative stress, an oxyR homologue, is known from the P. gingivalis W83 genome sequence. We used microarrays to characterize the response of P. gingivalis to H2O2 and examine the role of oxyR in the regulation of this response. Most organisms in which oxyR has been investigated are facultative anaerobes or aerobes. In contrast to the OxyR-regulated response of these microorganisms to H2O2, the main feature of the response in P. gingivalis was a concerted up-regulation of insertion sequence elements related to IS1 transposases. Common OxyR-regulated genes such as dps and ahpFC were not positively regulated in P. gingivalis in response to H2O2. However, their expression was dependent on the presence of a functional OxyR, as revealed by microarray comparison of an oxyR mutant to the wild type. Phenotypic characterization of the oxyR mutant showed that OxyR plays a role in both the resistance to H2O2 and the aerotolerance of P. gingivalis. Escherichia coli and other bacteria with more complex respiratory requirements use OxyR for regulating resistance to H2O2 and use a separate regulator for aerotolerance. In P. gingivalis, the presence of a single protein combining the two functions might be related to the comparatively smaller genome size of this anaerobic microorganism. In conclusion, these results suggest that OxyR does not act as a sensor of H2O2 in P. gingivalis but constitutively activates transcription of oxidative-stress-related genes under anaerobic growth.

Infection patterns in chronic and aggressive periodontitis

BACKGROUND

We revisited the postulate that localized aggressive periodontitis (LAP) patients have robust serum antibody (ab) responses to periodontal pathogens while patients with generalized aggressive periodontitis (GAP) show weak responses. We also studied ab responses in localized chronic (LCP) and generalized chronic periodontitis (GCP).

METHODS

Fifty-seven patients (14-74 years, 25% male, 70% Hispanic, 26% African American) were studied (15 LAP, 19 GAP, 11 LCP, 12 GCP patients). Three plaque samples/subject were analysed with respect to 15 species, and serum immunoglobulin G (IgG) responses to the same bacteria were determined. Ab responses were expressed as log-transformed titres, and "infection ratios", i.e., log-transformed ratios of ab titre over the subject-based mean bacterial load for the homologous species.

RESULTS

The results failed to corroborate the postulate that LAG patients have robust responses to infecting agents while GAP subjects exhibit weak responses. This held true for ab to "red complex", "orange complex", and health-associated species, and for both titres and infection ratios. Similarly, no differences were found between ab titres or infection ratios in chronic and aggressive periodontitis, or their extent-based subdivisions.

CONCLUSIONS

A distinction between the two principal categories of the current periodontitis classification cannot be established by the study of infection patterns.

The Relationship BetweenPorphyromonas gingivalisInfection and Local and Systemic Factors in Children

BACKGROUND

Porphyromonas gingivalis (P. gingivalis) is a major pathogen related to periodontitis. There are few reports on the prevalence and effect of P. gingivalis in children. The purpose of the present study was to describe in children the level of DNA-P gingivalis in subgingival plaque and the IgG serum reactivity to P. gingivalis (IgG-Pg), and examine their relationship to demographic, systemic, and oral variables.

METHODS

Thirty-four children, aged 1.83 to 13.42 years, were included in the study; 16 with no systemic disease and 18 with systemic conditions. The demographic data for caries incidence, plaque and gingival indices, probing depth, and alveolar bone height were recorded. The IgG-Pg and DNA-Pg levels were determined by enzyme-linked immunosorbent assay and DNA-DNA hybridization, respectively. The relationships between the IgG-Pg and DNA-Pg values to the demographics, oral parameters, and systemic conditions were examined.

RESULTS

IgG-Pg was evident in 53% of the children and DNA-Pg in 47%. IgG-Pg values significantly correlated positively with age, plaque index, and bone height. DNA-Pg values had statistically significant positive correlations with age. IgG-Pg and DNA-Pg values correlated with probing depth among children with systemic diseases. Neither the IgG-Pg nor the DNA-Pg values had a significant correlation to systemic conditions. Multiple regression analyses indicated that only age remained significantly related to IgG-Pg and DNA-Pg values.

CONCLUSIONS

P. gingivalis can be found in significant levels in the plaque of young children and elicits an immune reaction that increases with age and may be related to incipient signs of periodontal disease. Plaque DNA-Pg and serum IgG-Pg levels correlate significantly.

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.

Evidence for local production of antibodies to auto and non-self antigens in periodontal disease

Autoimmune mechanisms may contribute to periodontal disease (PD) pathogenesis; autoantibody to collagen type 1 is produced at the periodontal site and local levels are found to be higher than in serum.

OBJECTIVES

To find any evidence of autoimmune destruction in diseased periodontal tissues in patients with periodontitis. The study examines the relationship of antibodies to a self antigen collagen Type 1 and antigens from two periodontal pathogens namely Porphyromonas gingivalis (Pg), Actinobacillus actinomycetemcomitans (Aa) and a non-oral bacterium Bacteroides fragilis (Bf) in disease sites and in serum.

MATERIALS AND METHODS

Granulomatous tissues from periodontally diseased sites and serum samples were obtained from 13 patients (15 sites) undergoing surgical therapy. Tissues were homogenized at 4 degrees C on Tris saline buffer [1 g (5 ml)-1], homogenate was centrifuged and the resultant supernatants were used in assays. Antibody to collagen and Aa, Pg and Bf in tissue eluates and serum were determined by competitive enzyme linked immunosorbant assay (ELISA) and conventional ELISA respectively using an alkaline phosphatase/p-nitrophenyl phosphate enzyme-substrate system. Sera from age and sex matched healthy subjects and pooled human serum were used as controls. Antibody (Ab) levels in tissues and serum were standardized by concomitant albumin assay.

RESULTS

Level of antibodies to collagen type 1 in tissue was significantly higher than in serum (P = 0.0001). Antibody levels in tissue to Pg were significantly higher than in serum (P = 0.0271). Ab levels to both Aa and Bf in tissues and serum were not significantly different from each other.

CONCLUSIONS

These findings confirm the process of the local production of antibodies to autoantigen namely collagen type-1 and to bacterial antigens in the granulomatous tissues housed within the periodontal lesions in patients with periodontitis.

Antibody Responses of Periodontitis Patients to Gingipains ofPorphyromonas gingivalis

BACKGROUND

Arginine- and lysine-specific cysteine proteinases (arg-gingipain: Rgp, lys-gingipain: Kgp) are major virulence factors of Porphyromonas gingivalis. Recent reports have suggested that antibodies against gingipains can play a protective role against infection by P. gingivalis. The purpose of this study was to evaluate the IgG responses of patients with periodontitis to functional domains of gingipains.

METHODS

A group of 29 periodontitis patients and 10 periodontally healthy subjects (control group) were recruited into this study. We prepared three recombinant fragments of rgp A (catalytic domain; r-Rgp CAT) and two hemagglutinin domains (r-Rgp 44, and r-Rgps 15-27) corresponding to amino acid residues 228 to 719, 720 to 1136, and 1137 to 1704, respectively. One fragment of the Kgp catalytic domain (r-Kgp CAT) corresponding to amino acid residues 229 to 737 and expressed in Escherichia coli was also used. IgG antibody levels to these recombinant proteins in sera from the subjects were determined by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

We found that IgG levels against r-Rgp 44 and r-Rgps 15-27 in sera obtained from the patients were significantly higher than those in the healthy group (P<0.01). In contrast, no significant differences in IgG levels against r-Rgp CAT and r-Kgp CAT were found between the control and patient groups. The IgG responses to P. gingivalis sonic extracts, r-Rgp 44 and r-Rgps 15-27, were related to probing depth in sera from patients, but those to r-Rgp CAT and r-Kgp CAT were not.

CONCLUSION

The present findings suggest that the low responsiveness of IgG antibody against the catalytic domains of gingipain, r-Rgp CAT, and r-Kgp CAT is a key factor in infection by P. gingivalis.

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.

Porphyromonas gingivalis lipopolysaccharide signaling in gingival fibroblasts-CD14 and Toll-like receptors

Periodontal disease is the major cause of adult tooth loss and is commonly characterized by a chronic inflammation caused by infection of oral bacteria. Porphyromonas gingivalis (P. gingivalis) is one of the suspected periodontopathic bacteria and is frequently isolated from the periodontal pockets of patients with chronic periodontal disease. The lipopolysaccharide (LPS) of P. gingivalis is a key factor in the development of periodontitis. Gingival fibroblasts, which are the major constituents of gingival connective tissue, may directly interact with bacteria and bacterial products, including LPS, in periodontitis lesions. It is suggested that gingival fibroblasts play an important role in the host responses to LPS in periodontal disease. P. gingivalis LPS enhances the production of inflammatory cytokines such as interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) in gingival fibroblasts. However, the receptor that binds with P. gingivalis LPS on gingival fibroblasts remained unknown for many years. Recently, it was demonstrated that P. gingivalis LPS binds to gingival fibroblasts. It was also found that gingival fibroblasts express CD14, Toll-like receptor 4 (TLR4), and myeloid differentiation primary response gene 88 (MyD88). P. gingivalis LPS treatment of gingival fibroblasts activates several intracellular proteins, including protein tyrosine kinases, and up-regulates the expression of monocyte chemoattractant protein-1 (MCP-1), extracellular signal-regulated kinase 1 (ERK1), and signal-regulated kinase 2 (ERK2), IL-1 receptor-associated kinase (IRAK), nuclear factor-kappaB (NF-kappaB), and activating protein-1 (AP-1). These results suggest that the binding of P. gingivalis LPS to CD14 and TLR4 on gingival fibroblasts activates various second-messenger systems. In this article, we review recent findings on the signaling pathways induced by the binding of P. gingivalis LPS to CD14 and Toll-like receptors (TLRs) in gingival fibroblasts.

Purification and partial characterization of a dipeptidyl peptidase from Prevotella intermedia

A peptidase hydrolyzed X-Pro-p-nitroanilide was purified from the cell extract of Prevotella intermedia ATCC 25611 by ion-exchange chromatography and hydrophobic interaction chromatography. The purified enzyme exhibited a molecular size of 74 kDa from sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the maximum enzyme activity was found between pH 7.0 and pH 7.5. This peptidase was a serine enzyme and hydrolyzed Lys-Pro-p-nitroanilide, Arg-Pro-p-nitroanilide, and Ala-Pro-p-nitroanilide, but Lys-Ala-p-nitroanilide was not split. The enzyme may be classified as a dipeptidyl peptidase IV.

Serum antibodies of periodontitis patients compared to the lipopolysaccharides of Porphyromonas gingivalis and Fusobacterium nucleatum

Serum antibody titers against the lipopolysaccharides (LPSs) of Porphyromonas gingivalis and Fusobacterium nucleatum were compared between 9 periodontitis patients and 24 healthy persons. The IgG titers against the LPSs of P. gingivalis ATCC 33277(T) and W50 were clearly higher in the patients than in the healthy persons. However, IgM titers against the LPSs of P. gingivalis strains were relatively low, and no significant difference was observed between the patients and healthy persons. On the other hand, IgG and IgM titers against the LPS of Fusobacterium nucleatum JCM 8532(T) in some patients were significantly higher than those in the healthy persons, although the difference in IgG titers was not large compared to that of the LPS of P. gingivalis. These results suggest that the antibody measurement of patients' sera against the LPS of periodontal bacteria can be applied for the diagnosis of periodontitis.

Serum markers of periodontal disease status and inflammation in hemodialysis patients

BACKGROUND

Hemodialysis (HD) patients face a 25% annual mortality rate, with 50% of reported deaths attributed to cardiovascular disease. All-cause and cardiovascular mortality correlate with such acute-phase proteins as C-reactive protein (CRP). Hepatic CRP synthesis is upregulated by inflammation; however, elevated CRP values frequently are found in the absence of apparent infection or inflammation. Because destructive periodontal diseases have been associated with elevated CRP levels, we questioned whether destructive periodontal diseases could contribute to elevated CRP values in HD populations.

METHODS

Sera from 86 consecutive dentate HD patients were assayed for levels of immunoglobulin G (IgG) antibody to six periodontal species by means of an enzyme-linked immunosorbent assay.

RESULTS

CRP values for the subject population ranged from less than 6.9 to 159 mg/L (median, 8.2 mg/L). Univariate comparisons between subjects with or without elevated CRP levels (>10 mg/L) showed that CRP level elevation was associated significantly (P < 0.05) with greater doses of human recombinant erythropoietin and lower levels of hemoglobin, serum iron, transferrin saturation (TSat), albumin averaged over the 3 preceding months, total cholesterol, and triglycerides. Log serum IgG antibody levels to Porphyromonas gingivalis also were significantly greater in the group with elevated CRP levels (P = 0.013). Subsequent multivariate logistic regression showed that log serum antibody levels to P gingivalis remained significant (P = 0.02) after controlling for nonperiodontal sources of elevated CRP, hemoglobin, TSat, and triglyceride values.

CONCLUSION

These results suggest that elevated levels of IgG antibody to bacterial species associated with destructive periodontal diseases are associated with elevated CRP values in HD populations.

Simple and rapid detection of serum antibody to periodontopathic bacteria by dot blotting

The aim of this study was to detect the specific immunoglobulin G antibodies against periodontopathic bacteria by dot blotting. In the procedure used, bacterial preparations were blotted on a nitrocellulose membrane. After blocking the nonspecific binding sites, the diluted serum was blotted onto the preparations. The membrane was immersed in secondary antibodies and then in substrate buffer. The colored blots were then evaluated. To test the reliability of this procedure, 20 serum samples were examined for antibody: ten for anti-Porphyromonas gingivalis antibody, and the other ten for anti-Actinobacillus actinomycetemcomitans antibody. Five samples out of each set of ten had previously been confirmed as having high enzyme-linked immunosorbant assay (ELISA) titers to the antigen, while the other five had been confirmed as having average titer levels. Both whole-cell sonic extracts and fimbriae of P. gingivalis were used as antigens in the dot blotting, in order to compare their use as antigens in assays of the patients' sera. ELISA was also used to measure anti-P. gingivalis antibody titers. For the measurement of IgG antibodies against A. actinomycetemcomitans, formalin-killed whole cells were used. Fifty serum samples were examined for IgG antibodies against A. actinomycetemcomitans by dot blotting and ELISA. With both antigens, after 4 h, coloration of blots was more clearly visible for the high-titer sera than for the average-titer sera. The intensity of coloration of the blots for P. gingivalis and A. actinomycetemcomitans showed correlation with the ELISA titers. A particularly significant correlation was shown when P. gingivalis fimbriae were used as antigen. These results suggest that this dot blot method is a simple and rapid means of detection of serum antibodies, and that it shows promise as a chair-side assay method.

Effect of anti-CD14 antibody on experimental periodontitis induced by Porphyromonas gingivalis lipopolysaccharide

The lipopolysaccharide (LPS) released by Porphyromonas gingivalis, a Gram-negative bacterium found in the periodontal pockets of patients with periodontitis, induces bone resorbing activity in vivo. We previously showed that a receptor for LPS on human gingival fibroblasts and gingival epithelial cells is CD14. In this study, we established a mouse model of experimental periodontitis by applying a P. gingivalis LPS solution to the buccal region of mice. P. gingivalis LPS-induced bone resorption and interleukin-6 production in the gingival tissues were significantly inhibited by pretreatment with anti-CD14 antibody for 5 weeks prior to LPS treatment. This result suggests that anti-CD14 antibody may be usable as a prototype for the development of drugs for the treatment of periodontal disease.