Cloning, characterization, and antigen specificity of T-lymphocyte subsets extracted from gingival tissue of chronic adult periodontitis patients

Inflammation indices in association with periodontitis and cancer

Inflammation is a complex physiological process that plays a pivotal role in many if not all pathological conditions, including infectious as well as inflammatory diseases, like periodontitis and autoimmune disorders. Inflammatory response to periodontal biofilms and tissue destruction in periodontitis is associated with the release of inflammatory mediators. Chronic inflammation can promote the development of cancer. Persistence of inflammatory mediators plays a crucial role in this process. Quantification and monitoring of the severity of inflammation in relation to cancer is essential. Periodontitis is mainly quantified based on the severity and extent of attachment loss and/or pocket probing depth, in addition with bleeding on probing. In recent years, studies started to investigate inflammation indices in association with periodontal diseases. To date, only few reviews have been published focusing on the relationship between blood cell count, inflammation indices, and periodontitis. This review presents a comprehensive overview of different systemic inflammation indices, their methods of measurement, and the clinical applications in relation to periodontitis and cancer. This review outlines the physiological basis of inflammation and the underlying cellular and molecular mechanisms of the parameters described. Key inflammation indices are commonly utilized in periodontology such as the neutrophil to lymphocyte ratio. Inflammation indices like the platelet to lymphocyte ratio, platelet distribution width, plateletcrit, red blood cell distribution width, lymphocyte to monocyte ratio, delta neutrophil index, and the systemic immune inflammation index are also used in hospital settings and will be discussed. The clinical roles and limitations, relationship to systemic diseases as well as their association to periodontitis and treatment response are described.

Immunomodulation—What to Modulate and Why? Potential Immune Targets

Despite over 50 years of research into the immunology of periodontal disease, the precise mechanisms and the role of many cell types remains an enigma. Progress has been limited by the inability to determine disease activity clinically. Understanding the immunopathogenesis of periodontal disease however is fundamental if immunomodulation is to be used as a therapeutic strategy. It is important for the clinician to understand what could be modulated and why. In this context, potential targets include different immune cell populations and their subsets, as well as various cytokines. The aim of this review is to examine the role of the principal immune cell populations and their cytokines in the pathogenesis of periodontal disease and their potential as possible therapeutic targets.

Roles of Porphyromonas gingivalis and its virulence factors in periodontitis

Periodontitis is an infection-driven inflammatory disease, which is characterized by gingival inflammation and bone loss. Periodontitis is associated with various systemic diseases, including cardiovascular, respiratory, musculoskeletal, and reproductive system related abnormalities. Recent theory attributes the pathogenesis of periodontitis to oral microbial dysbiosis, in which Porphyromonas gingivalis acts as a critical agent by disrupting host immune homeostasis. Lipopolysaccharide, proteases, fimbriae, and some other virulence factors are among the strategies exploited by P. gingivalis to promote the bacterial colonization and facilitate the outgrowth of the surrounding microbial community. Virulence factors promote the coaggregation of P. gingivalis with other bacteria and the formation of dental biofilm. These virulence factors also modulate a variety of host immune components and subvert the immune response to evade bacterial clearance or induce an inflammatory environment. In this chapter, our focus is to discuss the virulence factors of periodontal pathogens, especially P. gingivalis, and their roles in regulating immune responses during periodontitis progression.

Treponema denticola enolase contributes to the production of antibodies against ENO1 but not to the progression of periodontitis

Autoantibodies against alpha-enolase (ENO1) are often detected in various infectious and autoimmune diseases. Anti-ENO1 antibody titers were reported to be associated with the severity of periodontitis in patients with rheumatoid arthritis. Because the enolase of the periodontal pathogen Treponema denticola (TdEno) has the highest homology with ENO1 among the enolases of human-associated bacteria, we hypothesized that anti-ENO1 autoantibodies produced during the immune response to TdEno may contribute to the progression of periodontitis and tested it in human and mouse systems. In human subjects with healthy periodontium or chronic periodontitis, a strong positive correlation between the levels of anti-TdEno and anti-ENO1 antibodies was observed. In addition, the purified anti-TdEno antibodies recognized ENO1 as well as TdEno in a dot blot, confirming the cross-reactivity between TdEno and ENO1. However, anti-ENO1 antibody titers were not associated with the severity of periodontitis. To further investigate the role of TdEno in the production of anti-ENO1 antibodies and the progression of periodontitis, mice received an oral gavage of P. gingivalis alone, subcutaneous immunization with TdEno alone, or both P. gingivalis oral gavage and TdEno immunization. Immunization with TdEno induced not only anti-TdEno but also anti-mouse Eno1 (mEno1) antibodies and increased the expression of TNFα in the gingival tissues. However, alveolar bone loss was not increased by TdEno immunization. In conclusion, autoreactive anti-ENO1/mEno1 antibodies that are produced as byproducts during the antibody response to TdEno play a minimal role in the progression of periodontitis in the absence of rheumatoid arthritis.

Regulatory T-cells Infiltrate Periodontal Disease Tissues

CD4+CD25+ regulatory T (Tr) cells are critical in regulating the immune response and thereby play an important role in the defense against infection and control of autoimmune diseases. Our previous studies demonstrated the involvement of autoimmune responses in periodontitis. The aim of this study was to identify CD4+CD25+ Tr cells in periodontitis tissues and compare them with those in gingivitis tissues. Immunohistological analysis of CD4, CD25, and CTLA-4 and the gene expression analysis of FOXP3, TGF-β1, and IL-10 on gingival biopsies revealed the presence of CD4+CD25+ Tr cells in all tissues. In periodontitis, the percentage of CD4+CD25+ Tr cells increased with increasing proportions of B-cells relative to T-cells. FOXP3, a characteristic marker for CD4+CD25+ Tr cells, TGF-β1 and IL-10 were expressed more highly in periodontitis compared with gingivitis. These findings suggest that CD4+CD25+ Tr cells and possibly other regulatory T-cell populations do exist and may play regulatory roles in periodontal diseases.

The role of osteoimmunology in periodontal disease

Periodontal disease is a pathological condition that involves inflammation of the tooth supporting structures. It occurs in response to the presence of bacterial plaque on the tooth structure. The host defense system, including innate and adaptive immunity, is responsible for combating the pathologic bacteria invading the periodontal tissue. Failure to eradicate the invading pathogens will result in a continuous state of inflammation where inflammatory cells such as lymphocytes, PMNs, and macrophages will continue to produce inflammatory mediators in an effort to destroy the invaders. Unfortunately, these inflammatory mediators have a deleterious effect on the host tissue as well as foreign microbes. One of the effects of these mediators on the host is the induction of matrix degradation and bone resorption through activation of proteases and other inflammatory mediators that activate osteoclasts.

Antibody and T cell responses to Fusobacterium nucleatum and Treponema denticola in health and chronic periodontitis

The characteristics of the T cell response to the members of oral flora are poorly understood. We characterized the antibody and T cell responses to FadA and Td92, adhesins from Fusobacterium nucleatum, an oral commensal, and Treponema denticola, a periodontal pathogen, respectively. Peripheral blood and saliva were obtained from healthy individuals and patients with untreated chronic periodontitis (CP, n = 11 paris) and after successful treatment of the disease (n = 9). The levels of antigen-specific antibody were measured by ELISA. In plasma, IgG1 was the most abundant isotype of Ab for both Ags, followed by IgA and then IgG4. The levels of FadA-specific salivary IgA (sIgA) were higher than Td92-specific sIgA and the FadA-specific IgA levels observed in plasma. However, the periodontal health status of the individuals did not affect the levels of FadA- or Td92-specific antibody. Even healthy individuals contained FadA- and Td92-specific CD4⁺ T cells, as determined by the detection of intracytoplasmic CD154 after short-term in vitro stimulation of peripheral blood mononuclear cells (PBMCs) with the antigens. Patients with CP tended to possess increased numbers of FadA- and Td92-specific CD4⁺ T cells but reduced numbers of Td92-specific Foxp3⁺CD4⁺ Tregs than the healthy subjects. Both FadA and Td92 induced the production of IFNγ and IL-10 but inhibited the secretion of IL-4 by PBMCs. In conclusion, F. nucleatum induced Th3 (sIgA)- and Th1 (IFNγ and IgG1)-dominant immune responses, whereas T. denticola induced a Th1 (IFNγ and IgG1)-dominant response. This IFNγ-dominant cytokine response was impaired in CP patients, and the Td92-induced IFNγ levels were negatively associated with periodontal destruction in patients. These findings may provide new insights into the homeostatic interaction between the immune system and oral bacteria and the pathogenesis of periodontitis.

Single-strand conformation polymorphism analysis for the diagnosis of T-cell clonality in periodontal disease

T cells recognize antigens via the T-cell receptor (TCR). Diversity in antigen recognition by T cells is generated in part by the recombination of V, (D), J, and C segments of the TCR. It is further enhanced by the N region, in addition to non-germline-encoded nucleotides at the V-(D)-J junction. It is generally believed that each T cell bears a distinct clonotype of TCR and that each clonotype is responsible for an antigen-specific T-cell response. T-cell clonal expansion has been detected in the peripheral blood or the disease-affected sites in patients with infections, autoimmune diseases, malignancy, and post-transplantation complications. Since antigen stimulation of T cells induces the proliferation of specific T cells, clonal T-cell expansion is considered to be a result of an antigen-specific immune response. For the analysis of such antigen-specific T cells, it is common to use their specific antigens if they are known. However, there are many diseases, such as periodontal diseases, in which there are a number of putative pathogenic antigens involved. In these circumstances, the detection of clonally expanded T cells is an effective method to evaluate whether antigen-specific immune responses are involved, since only a few clonally expanded T cells are detected in healthy individuals. In addition, the characterization of any clonally expanded T cells that are detected would further promote the understanding of the disease mechanisms. By using single-strand conformation polymorphism (SSCP) analysis, we demonstrated that oligoclonal T-cell accumulation was present in periodontitis lesions, in contrast to a heterogeneous T-cell population in the peripheral blood. SSCP is a powerful tool for analyzing specific T-cell responses both in vitro and in vivo.

Inhibition of apoptosis in periodontitis

This study investigated whether the prolonged survival of inflammatory cells in periodontal disease could be due to the inhibition of apoptosis by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) decoy receptors and inhibition of the terminal stages of apoptosis signaling by inhibitor of apoptosis (IAP) family members. Gingival tissue samples were taken from healthy individuals and those with chronic periodontitis. The expression of TRAIL, TRAIL receptors, TUNEL, cleaved caspase-3, xIAP, and survivin was determined immunohistologically and at the level of mRNA expression. Higher levels of TRAIL and the TRAIL decoy receptor, TRAIL R4, were expressed in the diseased periodontal tissues (p < 0.005). Statistically (p < 0.05) higher levels of cleaved caspase-3 and the cleaved caspase-3 inhibitors, xIAP and survivin, were seen. Similar changes were seen at the level of mRNA. The results indicate that apoptosis in periodontitis may be inhibited by elevated expression of TRAIL decoy receptors and cleaved caspase-3 inhibitors.

Characterization of CD4+CD25+ natural regulatory T cells in the inflammatory infiltrate of human chronic periodontitis

Periodontitis is an infectious disease, where putative periodontopathogens trigger chronic inflammatory and immune responses against periodontal structures, in which an unbalanced host response is also determinant to the disease outcome. It is reasonable to assume that patient susceptibility to periodontal tissue destruction could be determined by the balance between the response against periodontopathogens and regulatory mechanisms of these events mediated by suppressive T cells. In the present study, we identified and characterized natural regulatory T cells (Tregs) in the inflammatory infiltrate of human chronic periodontitis (CP) with emphasis on phenotypic analyses that were carried out to address the participation of Tregs in CP. Results showed that patients with CP presented increased frequency of T lymphocytes and CD4+CD25+ T cells in the inflammatory infiltrate of gingival tissues. These cells exhibited the phenotypic markers of Tregs such as forkhead box p3 (Foxp3), CTLA-4, glucocorticoid-inducible TNFR, CD103, and CD45RO and seemed to be attracted to the inflammation site by the chemokines CCL17 and CCL22, as their expression and its receptor CCR4 were increased in CP patients. Moreover, besides the increased detection of Foxp3 mRNA, diseased tissues presented high expression of the regulatory cytokines IL-10 and TGF-beta. In addition, the inflammatory infiltrate in CP biopsies was composed of CD25+Foxp3+ and CD25+TGF-beta+ cells, thus corroborating the hypothesis of the involvement of Tregs in the pathogenesis of CP. Finally, these results indicate that Tregs are found in the chronic lesions and must be involved in the modulation of local immune response in CP patients.

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.

Muscarinic cholinoceptor activation modulates DNA synthesis and CD40 expression in fibroblast cells

1 The aim of the present work was to examine the role of muscarinic acetylcholine receptors (mAChR) on DNA synthesis and CD40 expression in human fibroblast cells. Neonatal human skin fibroblast cultures were stimulated with carbachol in presence or absence of specific antagonists and the following parameters were measured: identification of mAChR subtypes, DNA synthesis, inositol phosphates (InsP) production and CD40 expression. 2 Human fibroblasts express mAChR with Kd 0.47 +/- 0.11 nm and Bmax 236 +/- 22 fmol mg protein(-1). Carbachol stimulates DNA synthesis, InsP and the expression of CD40. All these effects were inhibited by atropine, mustard hydrochloride (4-DAMP) and pirenzepine but not by AF-DX 116 and tropicamide, indicating that M3 and M1 mAChR are implicated in carbachol action. The relative Ki of the antagonists obtained by competition binding assay was in parallel to the relative potency for blocking both carbachol-stimulated InsP accumulation and DNA synthesis. 3 The intracellular pathway leading to carbachol-induced biological effects involved phospholipase C and calcium/calmodulin, as U-73122 and trifluoroperazine blocked carbachol effects, respectively. Calphostin C, a protein kinase C inhibitor, had no effect, indicating that this enzyme does not participate in the system. 4 These results may contribute to a better understanding of the modulatory role of the parasympathetic muscarinic system on normal human fibroblast function.

Increased infiltration of CD1d and natural killer T cells in periodontal disease tissues

BACKGROUND

Natural killer T (NKT) cells are a unique T lymphocyte subset that has been implicated in the regulation of immune responses associated with a broad range of diseases including autoimmunity, infectious diseases, and cancer. In contrast to conventional T cells, NKT cells are reactive to major histocompatibility complex (MHC) class I-like molecule CD1d. Considering the periodontitis having both aspects of infection and autoimmunity in nature, CD1d and reactive NKT cells are of particular importance.

OBJECTIVE

The aim of the present study was to examine whether the expression of CD1 isoforms and Valpha24(+) invariant NKT cells is associated with different disease entities, namely gingivitis and periodontitis.

MATERIAL AND METHODS

Immunohistochemical analysis was performed on cryostat sections of gingival tissues from 19 patients with periodontitis and eight patients with gingivitis using antibodies to CD1a, b, c, d, Valpha24(+) invariant NKT cells, CD83, CD3 and CD19.

RESULTS

Although all four subsets of CD1 molecules were expressed in periodontal lesions, CD1d was most abundant. CD1d expression was more frequent in periodontitis than gingivitis and increased together with increase of invariant NKT cell infiltration. Double immunohistochemical staining showed co-expression of CD1d and CD19 on identical cells and proximate infiltration of CD1d(+) and invariant NKT cells.

CONCLUSION

These findings suggest that CD1d-expressing B cells could activate NKT cells by CD1d-restricted manner and this NKT cell activation may play roles in pathogenesis of periodontal diseases.

Gene expression analysis of the CD4+ T-cell clones derived from gingival tissues of periodontitis patients

The function of T cells infiltrating periodontitis lesions is complex and has not been fully elucidated. Here, we established T-cell clones from the gingival tissues of periodontitis patients and examined their gene expression. A total of 57 and 101 T-cell clones were established by means of immobilized anti-CD3 antibody and IL-2 from gingival tissues and peripheral blood, respectively. The gingival T-cell clones were derived from three patients, and the peripheral blood T-cell clones from two of these patients and a further patient whose gingival T-cell clones were not established. Gingival tissues were also obtained from a further 19 periodontitis patients. The expression of cytokines and molecules related to both regulatory function and tissue destruction were examined by means of reverse-transcription polymerase chain reaction. All the gingival T-cell clones expressed mRNA for TGF-beta1, CTLA-4, and CD25, and all the T-cell clones from peripheral blood expressed IFN-gamma and TGF-beta1 mRNAs. Most but not all the T-cell clones from gingival tissues and peripheral blood expressed mRNA for IFN-gamma and, CD25 and CTLA-4, respectively. The frequency of T-cell clones and gingival tissues expressing FOXP3, a possible master gene for mouse CD4(+)CD25(+) regulatory T cells, was very high (97%, 93%, and 100% for gingival T-cell clones, peripheral blood T-cell clones, and gingival tissues, respectively). Whereas the frequency of IL-4-expressing T-cell clones was lower for gingival T-cell clones (70% vs. 87%), the frequency of the gingival T-cell clones expressing IL-10 and IL-17 was higher than peripheral blood T-cell clones (75% vs. 62% for IL-10, 51% vs. 11% for IL-17). A similar expression profile was observed for gingival T-cell clones compared with gingival tissue samples with the exception of IL-4 expression, where the frequency of positive samples was lower in the gingival tissues (70% vs. 11%). These results suggest that the individual T cells infiltrating gingival lesions can express mRNA for both Th1 and Th2 cytokines as well as regulatory cytokines simultaneously.

Aspects of adaptive host response in periodontitis

OBJECTIVE

To review host response in periodontitis with respect to cellular composition of lesions, T cell receptor (TCR) gene expression, cytokine profiles of T-helper (Th) cells and autoimmune components.

MATERIAL AND METHODS

The studies included were confined to human material (biopsies, gingival crevicular fluid, blood from subjects with periodontitis).

RESULTS AND CONCLUSIONS

In periodontitis lesions, plasma cells are the most common cell type and represent about 50% of all cells, while B cells comprise about 18%. The proportion of B cells is larger than that of T cells and Th cells occur in larger numbers than T cytotoxic cells. Polymorphonuclear cells and macrophages are found in fractions of less than 5% of all cells. Lesions in aggressive and chronic forms of periodontitis exhibit similar cellular composition. Differences in disease severity, however, may reflect increases in plasma cell and B cell densities. B cells serve as important antigen-presenting cells in periodontitis. The periodontitis lesion expresses a unique TCR gene repertoire that is different from that in blood. The role of superantigens in periodontitis is unclear. There are few studies using comparative designs and unbiased quantitative methods regarding Th-1 and Th-2 cells in periodontitis. The relative dominance of B cells and plasma cells in periodontitis lesions cannot entirely be explained by enhanced Th-2 functions but maybe because of an imbalance between Th-1 and Th-2. Autoimmune reactions are evident in periodontitis lesions. The role of auto-antibodies in the regulation of host response in periodontitis, however, needs to be clarified. Auto-reactive B cells occur in larger proportions in subjects with periodontitis than in healthy controls.

Characterization of heat shock protein-specific T cells in atherosclerosis

A role for infection and inflammation in atherogenesis is widely accepted. Arterial endothelium has been shown to express heat shock protein 60 (HSP60) and, since human (hHSP60) and bacterial (GroEL) HSP60s are highly conserved, the immune response to bacteria may result in cross-reactivity, leading to endothelial damage and thus contribute to the pathogenesis of atherosclerosis. In this study, GroEL-specific T-cell lines from peripheral blood and GroEL-, hHSP60-, and Porphyromonas gingivalis-specific T-cell lines from atherosclerotic plaques were established and characterized in terms of their cross-reactive proliferative responses, cytokine and chemokine profiles, and T-cell receptor (TCR) Vbeta expression by flow cytometry. The cross-reactivity of several lines was demonstrated. The cytokine profiles of the artery T-cell lines specific for GroEL, hHSP60, and P. gingivalis demonstrated Th2 phenotype predominance in the CD4 subset and Tc0 phenotype predominance in the CD8 subset. A higher proportion of CD4 cells were positive for interferon-inducible protein 10 and RANTES, with low percentages of cells positive for monocyte chemoattractant protein 1 and macrophage inflammatory protein 1alpha, whereas a high percentage of CD8 cells expressed all four chemokines. Finally, there was overexpression of the TCR Vbeta5.2 family in all lines. These cytokine, chemokine, and Vbeta profiles are similar to those demonstrated previously for P. gingivalis-specific lines established from periodontal disease patients. These results support the hypothesis that in some patients cross-reactivity of the immune response to bacterial HSPs, including those of periodontal pathogens, with arterial endothelial cells expressing hHSP60 may explain the apparent association between atherosclerosis and periodontal infection.

Relative Proportions of T-Cell Subpopulations and Cytokines That Mediate and Regulate the Adaptive Immune Response in Patients With Aggressive Periodontitis

BACKGROUND

Both the virulence factors of periodontopathic bacteria and the immune response against them have been involved in tissue destruction observed in periodontal disease. Considering the regulatory role of cytokines produced by T cells, the purpose of this study was to compare the CD3+, CD4+, and CD8+ subpopulations of T cells, and to characterize the mRNA of cytokines involved in the adaptive immune response in a group of healthy/gingivitis 1 (HI/G1) individuals and aggressive periodontitis (AgP) patients.

METHODS

The percentages of T-cell subpopulations were analyzed in 10 gingival samples of HI/G1 individuals and 10 gingival samples of AgP patients by immunohistochemistry. The presence of interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-5, IL-10, IL- 13, and transforming growth factor (TGF)-beta was measured by reverse transcription polymerase chain reaction (RT-PCR) of mRNA extracted from complete gingival biopsies.

RESULTS

Significant differences were found in CD3+ and CD4+ cell counts between both groups. The parameters were lower in the gingival biopsies from AgP patients while CD8+ counts were similar in both groups. The cytokine mRNA analysis showed constant expression of IL-2 and IFN-gamma in all cases. The mRNA of IL-5 and IL-10 was present in the majority of HI/G1 (N = 10, N = 9, respectively) but was not in the AgP group (N = 2, N = 1). IL-13 and TGF-beta were only detected in HI/G1 (N = 2, N = 3) and IL-4 was not detected in any of the individuals.

CONCLUSIONS

These results indicate that the role of the CD8+ subpopulation in aggressive periodontitis lesions is limited. On the other hand, cytokines IL-2 and IFN-gamma may not be relevant in the progression of aggressive periodontitis.

Interleukin-4 gene polymorphisms in Japanese and Caucasian patients with aggressive periodontitis

OBJECTIVES

Recently, interleukin (IL) 4 gene polymorphisms have been analyzed in association with periodontitis. Genetic differences between Caucasian and Japanese patients with periodontitis have previously been detected. The aim of the present study was to analyze IL-4 genotypes in Caucasian and Japanese patients with aggressive periodontitis (AgP).

MATERIAL AND METHODS

One hundred and twenty-four subjects were included in the study, 31 Japanese and 30 Caucasian patients with generalized AgP, plus 30 Japanese and 33 Caucasian healthy controls. IL-4 polymorphisms were determined by polymerase chain reaction. A logistic regression was used to investigate the possible association of the genotypes with the disease in both populations. Odds ratio (OR) estimates were analyzed for allele frequencies.

RESULTS

No significant association of IL-4 polymorphisms with the risk of AgP was determined in either population. However, the allele frequencies showed different results between populations. The carriage of the polymorphism in intron 2 was higher in Caucasian patients compared with controls (OR: 2.0, 95% confidence interval: [1.0;4.2]. Furthermore, the frequency of the IL-4 promoter/intron 2 composite genotype (PP+/IP+) in patients and controls, respectively, was found to be approximately 25% and 60% higher in the Japanese population than in the Caucasian population.

CONCLUSION

There was no evidence of an association of IL-4 genotypes and AgP in either population, although the frequencies of the IL-4 genotypes in the Japanese and the Caucasians were different.

Fimbriated Porphyromonas gingivalis is more efficient than fimbria-deficient P. gingivalis in entering human dendritic cells in vitro and induces an inflammatory Th1 effector response

Porphyromonas gingivalis is a fimbriated mucosal pathogen implicated in chronic periodontitis (CP). The fimbriae are required for invasion of the gingival mucosa and for induction of CP in animal models of periodontitis. CP is associated with infection of immature dendritic cells (DCs) by P. gingivalis in situ and with increased numbers of dermal DCs (DDCs) and mature DCs in the lamina propria. The role of fimbriae in gaining entry into human DCs and how this modulates the inflammatory and effector immune responses, however, have not been explored. To address this, we generated monocyte-derived DCs (MDDCs) in vitro which phenotypically and functionally resemble DDCs. We show here that virulent fimbriated P. gingivalis 381, in contrast to its fimbria-deficient mutant, P. gingivalis DPG3, efficiently gains entry to MDDCs in a manner dependent on active cell metabolism and cytoskeletal rearrangement. In addition, uptake of 381, unlike DPG3, induces DCs to undergo maturation, upregulate costimulatory molecules, and secrete inflammation cytokines interleukin-1beta (IL-1beta), IL-6, tumor necrosis factor alpha, IL-10, and IL-12. Moreover, MDDCs pulsed with 381 also stimulated a higher autologous mixed lymphocyte reaction and induced a Th1-type response, with gamma interferon (IFN-gamma) being the main cytokine. Monocytes used as controls demonstrated fimbria-dependent uptake of 381 as well but produced low levels of inflammatory cytokines compared to MDDCs. When MDDCs were pulsed with recombinant fimbrillin of P. gingivalis (10 micro g/ml), maturation of MDDCs was also induced; moreover, matured MDDCs induced proliferation of autologous CD4(+) T cells and release of IFN-gamma. Thus, these results establish the significance of P. gingivalis fimbriae in the uptake of P. gingivalis by MDDCs and in induction of immunostimulatory Th1 responses.

Generation of gingival T cell lines/clones specific with Porphyromonas gingivalis pulsed dendritic cells from periodontitis patients

OBJECTIVES AND BACKGROUND

It is well documented that in periodontitis lesions, most infiltrated gingival T cells are antigen-specific memory T cells. These cells play an important role as regulators and effector cells in the pathogenesis of periodontitis. In this study, we used dendritic cells (DCs) as antigen-presenting cells to generate human gingival T cell lines and clones specific for Porphyromonas gingivalis from periodontitis patients.

METHODS

Autologous DCs were derived from the patients' adherent monocytes using granulocyte-macrophage colony-stimulating factor and interleukin (IL)-4. Lymphocytes were isolated from gingival biopsies using collagenase enzyme digestion and the number was increased by subsequent culturing in IL-2-containing medium. T cells were then negatively sorted using flow cytometry, cocultured with P. gingivalis-pulsed DCs and subsequently expanded in the culture medium containing IL-2. T cells were kept viable and active by periodic exposure to antigen-pulsed DCs. The specificity of the T cell lines was tested against four plaque bacteria: P. gingivalis, Actinobacillus actinomycetemcomitans, Prevotella intermedia and Actinomyces viscosus. The established T cell lines were then cloned. Three P. gingivalis-specific T cell lines and 12 gingival T cell clones were generated. They all showed good specificity against P. gingivalis but not to other plaque bacteria.

RESULTS

All T cell clones were positive for CD4 and the majority of them produced interferon gamma, but a minimal or negligible amount of IL-5.

CONCLUSIONS

The data obtained clearly showed that monocyte-derived DCs could be used as powerful antigen-presenting cells to generate antigen-specific T cells from periodontitis tissues.

P. gingivalis-specific T-cell lines produce Th1 and Th2 cytokines

Cytokines produced by T-cells in periodontal lesions may determine the nature of the adaptive immune response. Since different antigen-presenting cells (APC) may direct the Th1/Th2 response, P. gingivalis-specific T-cell lines were established by different APC subpopulations, and their cytokine profiles were determined. Peripheral blood mononuclear cells induced similar percentages of IL-4+ and IFN-gamma+ T-cells and lower percentages of IL-10+ T-cells. Epstein-Barr virus-transformed B-cells (LCL) induced higher percentages of IL-4+ cells than IFN-gamma+ cells, with lower percentages of IL-10+ cells. Peripheral blood mononuclear cells induced a higher percent of IFN-gamma+ CD8 cells than LCL (p = 0.004). Purified B-cells, monocytes, and dendritic cells induced similar percentages of IL-4+ and IFN-gamma+ cells, although again, the percentage of IL-10+ cells was lower. The results of the present study have demonstrated that, as measured by FACS analysis of intracytoplasmic cytokines, P. gingivalis-specific T-cells produce both Th1 and Th2 cytokines, regardless of the APC population.

Accumulation of human heat shock protein 60-reactive T cells in the gingival tissues of periodontitis patients

Heat shock protein 60s (hsp60) are remarkably immunogenic, and both T-cell and antibody responses to hsp60 have been reported in various inflammatory conditions. To clarify the role of hsp60 in T-cell responses in periodontitis, we examined the proliferative response of peripheral blood mononuclear cells (PBMC), as well as the cytokine profile and T-cell clonality, for periodontitis patients and controls following stimulation with recombinant human hsp60 and Porphyromonas gingivalis GroEL. To confirm the infiltration of hsp60-reactive T-cell clones into periodontitis lesions, nucleotide sequences within complementarity-determining region 3 of the T-cell receptor (TCR) beta-chain were compared between hsp60-reactive peripheral blood T cells and periodontitis lesion-infiltrating T cells. Periodontitis patients demonstrated significantly higher proliferative responses of PBMC to human hsp60, but not to P. gingivalis GroEL, than control subjects. The response was inhibited by anti-major histocompatibility complex class II antibodies. Analysis of the nucleotide sequences of the TCR demonstrated that human hsp60-reactive T-cell clones and periodontitis lesion-infiltrating T cells have the same receptors, suggesting that hsp60-reactive T cells accumulate in periodontitis lesions. Analysis of the cytokine profile demonstrated that hsp60-reactive PBMC produced significant levels of gamma interferon (IFN-gamma) in periodontitis patients, whereas P. gingivalis GroEL did not induce any skewing toward a type1 or type2 cytokine profile. In control subjects no significant expression of IFN-gamma or interleukin 4 was induced. These results suggest that periodontitis patients have human hsp60-reactive T cells with a type 1 cytokine profile in their peripheral blood T-cell pools.

Immunohistological study of interferon-gamma- and interleukin-4-bearing cells in human periodontitis gingiva

The purpose was to investigate the balance between interferon (IFN)-gamma- and interleukin (IL)-4-bearing cells in various human inflamed gingiva by immunohistochemistry. Gingival tissues obtained from patients with gingivitis or periodontitis were divided into three groups based on the degree of histopathological inflammation, mild, moderate and severe. The tissues were also divided into four groups according to the clinical probing depth (PD). IFN-gamma- and IL-4-bearing cells in gingival tissues were stained immunohistologically and counted. The ratio of IL-4-bearing cells to IFN-gamma-bearing cells was calculated for each section. IFN-gamma-bearing cells were widespread in the connective tissue and their number increased significantly with the severity of inflammation and an increase of PD. IL-4-bearing cells were located beneath the pocket epithelium and their number showed no significant differences among the inflammation or PD groups. The ratios of IL-4-bearing cells to IFN-gamma-bearing cells in the severe inflammation or deep PD groups were significantly lower than those in the moderate inflammation or shallow PD groups. These results suggest that a low ratio of IL-4-bearing cells to IFN-gamma-bearing cells might be involved in the destruction of periodontal tissue.

Involvement of T-lymphocytes in periodontal disease and in direct and indirect induction of bone resorption

Periodontal disease is a peripheral infection involving species of gram-negative organisms. T-lymphocytes can be found in the dense inflammatory infiltrate in this disease. CD4+ and CD8+ T-cells are present in periodontal lesions, as are memory/activated T-lymphocytes. In addition, Th1- and Th2-type T-lymphocytes and their associated cytokines with a subtle polarization to Th1 may be present. Th1-type T-cells up-regulate the production of pro-inflammatory cytokines IL-1 and TNF-alpha, which can induce bone resorption indirectly by promoting differentiation of osteoclast precursors and subsequently by activating osteoclasts. Such osteoclast differentiation is dependent on stimulation of osteoprotegerin ligand (OPG-L) production by osteoblastic cells. By contrast, activated T-cells, by virtue of direct production and expression of OPG-L, can directly promote osteoclast differentiation. OPG-L appears to be predominantly expressed on Th1-type cells. The direct and indirect T-cell involvement in periodontal bone resorption appears to be dependent on the degree of Th1-type T-cell recruitment into inflamed gingival tissues. This T-cell recruitment is regulated by adhesion molecules and chemokines/chemokine receptors. The adhesion molecules involved include alpha4 and alpha6 integrins, LFA-1, and ICAM-1. The Th1-type T-cells preferentially express CCR5 and CXCR3, which are found prominently in diseased gingivae. By contrast, little CCR4, expressed by Th2-type T-cells, can be detected. Also, the chemokine ligands RANTES, MIP1-alpha (both CCR5), and IP-10 (CXCR3 ligand) were elevated in inflamed periodontal tissues. The T-cell features in diseased periodontal tissues can be compared with those in rheumatoid arthritis, wherein bone resorption often attributed to Th1-type T-cell involvement has also been demonstrated.

Elevated proportion of natural killer T cells in periodontitis lesions: a common feature of chronic inflammatory diseases

Although periodontitis is a chronic inflammatory disease caused by a group of so-called periodontopathic bacteria, autoimmune mechanisms have also been implicated in the disease process. Recently, a unique subset of lymphocytes designated natural killer (NK) T cells expressing the Valpha24JalphaQ invariant T cell receptor (TCR) has been reported to have a regulatory role in certain autoimmune diseases. Therefore, we investigated the proportion of the invariant Valpha24JalphaQ TCR within the Valpha24 T cell population in periodontitis lesions and gingivitis lesions using single-strand conformation polymorphism methodology. NK T cells were identified with a specific JalphaQ probe whereas the total Valpha24 TCR was identified using an internal Calpha probe. NK T cells were a significant proportion of the total Valpha24 population both in periodontitis lesions and to a lesser extent in gingivitis lesions but not in the peripheral blood of either periodontitis patients or nondiseased controls. Using immunohistochemistry, some of Valpha24(+) cells in the periodontitis lesions seemed to associate with CD1d(+) cells, which are specific antigen-presenting cells for NK T cells. Although the mechanism underlying the elevation of NK T cells in periodontitis and in gingivitis lesions remains unclear, it can be postulated that NK T cells are recruited to a play regulatory role in the immune response to bacterial infection.

A novel factor isolated from Actinobacillus actinomycetemcomitans stimulates mouse B cells and human peripheral blood mononuclear cells

A novel immunostimulating factor (ISTF) of Actinobacillus actinomycetemcomitans ATCC 29522 was isolated and characterized as inducing proliferation of mouse B cells and human peripheral blood mononuclear cells. This factor was isolated from the bacterial culture medium and purified by size exclusion chromatography, dye-ligand affinity chromatography, immunoaffinity chromatography using monoclonal antibodies, and preparative electrophoresis. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the purified ISTF migrated as a single band corresponding to a molecular mass of 13 kDa. ISTF was a proteinaceous material distinct from lipopolysaccharide; it directly induced the proliferation of B lymphocytes but had no effect on the proliferation of T lymphocytes, even in the presence of antigen-presenting cells. A B-lymphocyte-mitogenic activity of ISTF was also shown by flow cytometric analysis of responding cell subpopulations. Immunoblot analysis revealed that ISTF was a component of the outer membranes of bacteria, could exist as a soluble form, and was released by growing and/or lysed bacteria. These results suggest that ISTF produced by A. actinomycetemcomitans may play an important role in immunopathologic changes associated with A. actinomycetemcomitans infections.

Cytokine profiles of T-lymphocytes from gingival tissues with pathological pocketing

Periodontal disease is an infection in which destruction occurs at sites remote from the infection, resulting in pathological pocketing. Intervening between the infection and the destruction is a dense mononuclear inflammatory infiltrate. It has been suggested that this infiltrate might have characteristics and the destructive potential of Th1-type T lymphocytes. To ascertain the nature of the infiltrates we investigated the expression of mRNA for IL-2, IL-5, and IFN-gamma by gingival mononuclear cells (GMC) from healthy (n = 8) or adult periodontitis (AP) patients (n = 25) by using cytokine-specific reverse-transcription/polymerase-chain-reaction (RT-PCR). GMC, as obtained from patients' tissues, expressed IL-2, IFN-gamma, or IL-5 mRNA. Significantly higher proportions of GMC from AP patients expressed IL-2 and IFN-gamma mRNA than did those from healthy subjects. IFN-gamma was the most consistent cytokine message detected. In other experiments, gingival T-lymphocytes (n = 12) and CD4+ and CD8+ gingival T-lymphocytes (n = 16) were isolated from gingival tissues removed surgically from AP patients. AP gingival T-lymphocytes expressed mRNA for IL-2, IFN-gamma, or IL-6 prior to stimulation. After stimulation with Con A, the cells significantly up-regulated IL-5 and IL-6 message expression. Both CD4+ and CD8+ gingival T-lymphocytes expressed IFN-gamma, IL-5, and some IL-2. This cumulative cytokine profile observed in these experiments is consistent with the predominance of Th1-type cells in pathological tissues and with Th2-type cells, which can also be present, being up-regulated under appropriate stimulation. Importantly, CD4+ and CD8+ lymphocytes were shown to express T1- and T2-type cytokine message, emphasizing the potential for CD8+ T-lymphocytes to participate in periodontal disease pathology.

Elevated humoral immune response to heat shock protein 60 (hsp60) family in periodontitis patients

The presence of antibodies to the 60-kD human and Porphyromonas gingivalis GroEL hsp60 in the sera and inflamed gingival tissues of periodontitis patients was examined. In order to obtain the antigens, recombinant plasmids carrying human hsp60 and P. gingivalis GroEL genes were constructed and expressed as histidine-tagged recombinant proteins. Immunoreactivities of these proteins were confirmed by MoAbs specific to mammalian hsp60 and cross-reactive with both mammalian and bacterial hsp60. Western blot analysis clearly demonstrated that the number of periodontitis patients showing a positive response to P. gingivalis GroEL was higher than the number of periodontally healthy subjects. Furthermore, anti-P. gingivalis GroEL antibody was detected in all samples of gingival tissue extracts. For human hsp60, a higher frequency of seropositivity was found in the periodontitis patients than in the healthy subjects. In addition, the periodontitis patients demonstrated stronger reactivity compared with the healthy subjects. Quantitative analysis of serum antibodies by ELISA also demonstrated that the levels of antibodies in the sera of patients were significantly higher than those of control subjects. In the gingival tissue extracts, seven out of 10 patients demonstrated a positive response to human hsp60 and tso of these demonstrated strong positivity. Affinity-purified serum antibodies to human hsp60 and P. gingivalis GroEL from selected patients reacted with P. gingivalis GroEL and human hsp60, respectively, suggesting cross-reactivity of antibodies. These results suggest that molecular mimicry between GroEL of the periodontopathic bacterium P. gingivalis and autologous human hsp60 may play some role in immune mechanisms in periodontitis.

The immune modulation of B-cell responses by Porphyromonas ginginvalis and interleukin-10

BACKGROUND

Polyclonal B-cell activation induced by periodontopathic bacteria has been cited as being important for elevated numbers of B cells, but the role of bacteria in the pathogenesis of periodontal disease remains unknown. In this study, we used an in vitro model to investigate the activation of immune cells by the periodontopathic bacterium Porphyromonas gingivalis in healthy subjects.

METHODS

Peripheral blood mononuclear cells (PBMC) or purified subsets of lymphocytes were stimulated with sonicated extracts of P. gingivalis for 24 hours. Cells were harvested and monitored for expression of CD69 by flow cytometry. Cytokine production (IL-10, IL-12, and IL-15) in P. gingivalis-stimulated PBMC cultures was measured by ELISA. To identify IL-10 producer cells, a cell depletion experiment was used and confirmed by the ability of the purified cell population to produce IL-10. To evaluate the effect of P. gingivalis and IL-10, the proliferative response of purified B cells was assessed by [3H] thymidine uptake.

RESULTS

PBMC cultured with P. gingivalis led to a large number of activated B and natural killer (NK) cells as monitored by CD69 expression. When positively sorted cells were used, the bacterium itself could directly activate only B cells but not NK cells, alphabeta, and gammadelta T cells. Measurement of B-cell regulatory cytokine production in P. gingivalis-stimulated PBMC cultures revealed a large amount of IL-10 but no detectable IL-12 or IL-15; the major producing cells were monocytes, not B cells or alphabeta T cells. When IL-10 was added to B cells in the presence of bacteria, significantly increased B-cell proliferative responses were observed.

CONCLUSIONS

These results suggest that P. gingivalis, both directly and indirectly via macrophage IL-10, may play an important role in polyclonal B-cell activation associated with periodontal disease.

Th1 and Th2 cytokine profile in patients with early onset periodontitis and their healthy siblings

Early onset periodontitis (EOP) is a chronic inflammatory periodontal disease with a strong genetic link affecting individuals aged 17 to 25. In the familial studies we tested the hypothesis about the role of Th1 and Th2 cytokines in the pathogenesis of EOP disease. The study involved 6 individuals with EOP disease and their 6 siblings with healthy periodontium. Actinobacillus actinomycetemcomitans (A. a), a bacterium typical for EOP, was detected in all people studied. Th1 and Th2 cytokine production was measured after in vitro stimulation. Peripheral blood mononuclear cells (PBMC) were isolated and cultivated for 24 h and 7 days with PWM, A. a. or Escherichia coli. The levels of IL-4, IFN-gamma, IgA, IgG and IgM were measured by ELISA methods. After in vitro stimulation of PBMC, a significantly higher production of IL-4 and significantly lower production of IFN-gamma were found in the group of patients compared with their healthy siblings. The increased level of IL-4 in patients was in good agreement with an increased level of IgM after stimulation of lymphocytes with E. coli. These results support Seymour's hypothesis according to which patients with progressive disease primarily activate Th2 lymphocytes while non-susceptible individuals activate Th1 lymphocytes.

T-cell antigen specificity in humans following stimulation with Porphyromonas gingivalis

The effects of Porphyromonas gingivalis stimulation on T-cell clonality and cytokine mRNA expression in peripheral blood mononuclear cells from individuals with gingivitis and periodontitis were investigated. Clonality of T cells was investigated by reverse transcription-polymerase chain reaction (RT-PCR) and single-strand conformation polymorphism analysis. Cytokine mRNA expression was investigated by RT-PCR. Whereas unstimulated mononuclear cells did not demonstrate obvious clonality, clonal expansion was found in most Vbeta families after stimulation. However, there was no relation between clonal change and disease category or the presence of P. gingivalis infection. Messenger RNA for interferon-gamma and interleukin-13 was upregulated whereas interleukin-4 and -10 were downregulated following P. gingivalis stimulation. Interleukin-12p35 demonstrated no consistent pattern. This study supports the concept that P. gingivalis stimulates T cells in an antigen-specific fashion. It further suggests that peripheral blood T cells may preferentially produce interferon-gamma and interleukin-13 in response to P. gingivalis stimulation irrespective of disease or P. gingivalis status.

Depressed responsiveness of peripheral blood mononuclear cells to heat-shock proteins in periodontitis patients

The extensive homology between human and bacterial heat shock proteins (HSPs) may play a role in autoimmune reactions in periodontitis. Thus, we questioned whether peripheral blood mononuclear cell (PBMC) proliferative responses to HSPs are different between periodontitis patients and control subjects with gingivitis. The proliferative responses of PBMCs of patients (n = 10) and controls (n = 12) to recombinant mycobacterial HSP60 (MycHSP60) and HSP70 (MycHSP70), as well as recombinant human HSP60 (HumHSP60) and HSP70 (HumHSP70), were investigated. In addition, the proliferative responses to Candida albicans and purified protein derivatives of Mycobacterium (PPD) were included. Mean responses to HumHSP60, MycHSP60, and HumHSP70 were significantly lower for patients compared with controls. The responses to MycHSP70 showed a similar trend. However, when Candida and PPD were used as antigens, there was no difference in responses of the PBMCs between the periodontitis patients and controls. The level of IFN-gamma in the supernatants of the cells stimulated with HSPs was lower in the patients compared with controls. This concurs with the current hypothesis that periodontitis patients have a depressed Th1 response. Furthermore, we found that with an increasing estimated subgingival bacterial load, periodontitis patients mount a decreasing immune response to HSPs, while the controls showed a positive correlation between these two parameters. From these findings, we speculate that poor reactivity to HSPs may be a susceptibility factor for destructive periodontal disease and may need to be considered in the pathogenesis of this condition.

In vitro induction of activation-induced cell death in lymphocytes from chronic periodontal lesions by exogenous Fas ligand

Periodontitis is a chronic inflammatory disease which gradually destroys the supporting tissues of the teeth, leading to tooth loss in adults. The lesions are characterized by a persistence of inflammatory cells in gingival and periodontal connective tissues. To understand what mechanisms are involved in the establishment of chronic lesions, we hypothesized that infiltrating lymphocytes might be resistant to apoptosis. However, both Bcl-2 and Bcl-xL were weakly detected in lymphocytes from the lesions, compared with those from peripheral blood, suggesting that these cells are susceptible to apoptosis. Nevertheless, very few apoptotic cells were observed in tissue sections from the lesions. Lymphocytes from the lesions expressed mRNA encoding Fas, whereas Fas-ligand mRNA was very weakly expressed in lymphocytes from the lesions and in periodontal tissues. Since the results indicated that lymphocytes in the lesions might be susceptible to Fas-mediated apoptosis but lack the death signal, we next investigated if these lymphocytes actually undergo apoptosis by the addition of anti-Fas antibodies in vitro. Fas-positive lymphocytes from the lesions underwent apoptosis by these antibodies, but Fas-negative lymphocytes and Fas-positive peripheral lymphocytes did not undergo apoptosis by these antibodies. These results indicate that lymphocytes in the lesions are susceptible to activation-induced cell death and are induced to die by apoptosis after the addition of exogenous Fas ligand.

CD40 engagement modulates the production of matrix metalloproteinases by gingival fibroblasts

Chronic periodontitis is a destructive inflammatory disease linked with unbalanced production between matrix metalloproteinases (MMPs), such as interstitial collagenase (MMP-1) and stromelysin-1 (MMP-3) and their endogenous tissue inhibitors of MMPs (TIMPs). In addition to aberrant MMP-1 and MMP-3 expression, periodontal lesions are characterized by dense infiltrations of activated T lymphocytes which may interact with CD40-expressing gingival fibroblasts in the connective tissue via the CD40L-CD40 pathway. In this study we investigated whether CD40 cross-linking influenced MMP production by gingival fibroblasts. Therefore, we analysed the CD40L-induced MMP production by these fibroblasts in the presence of cytokines that are increased in periodontal lesions, such as IL-1beta, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). We show that CD40 ligation on gingival fibroblasts resulted in a decrease of their MMP-1 and MMP-3 production, while MMP-2 and TIMP-1 production were unaffected as determined by Western blot. This down-regulatory effect of CD40 engagement on MMP-1 and MMP-3 production by gingival fibroblasts was also present when MMP production was up-regulated by IL-1beta and TNF-alpha or down-regulated by IFN-gamma. These results suggest that CD40 ligation on gingival fibroblasts leads to a restraining of MMP-1 and MMP-3 production by gingival fibroblasts and thereby may be an important mechanism in the retardation of further periodontal tissue damage.

T cell responses to 53-kDa outer membrane protein of Porphyromonas gingivalis in humans with early-onset periodontitis

Patients with early-onset periodontitis (EOP) are susceptible to infection with periodontopathic bacteria, such as Porphyromonas gingivalis. Ag53, 53-kDa outer membrane protein of P. gingivalis, evokes strong humoral immune responses in EOP patients. In a first step to clarify how host immune cells recognize Ag53, we established Ag53-specific short-term T cell lines from 22 subjects including 6 EOP patients and 16 healthy donors, using overlapping peptides based on Ag53 amino acid sequences. All T cell lines from active EOP patients recognized a common region (p141-181, especially p141-161) on Ag53, while those from healthy donors showed heterogeneous specificity. p141-181 was not recognized by T cell lines established from EOP patients following therapy. A monoclonal antibody to HLA-DRB 1 inhibited Ag53-induced proliferation of most of the T cell lines. Our observations suggest that, although antigen-presenting molecules are common in EOP patients and in healthy individuals, p141-161 includes a major T cell epitope(s) on Ag53 for active EOP patients but not for healthy individuals or inactive EOP patients.

Detection of clonotypic changes of T cells after stimulation with Porphyromonas gingivalis

The aim of this study was to investigate whether Porphyromonas gingivalis stimulation would induce a selective activation and expansion of a limited T-cell receptor V beta repertoire or T-cell clonotype. Using samples from patients with chronic inflammatory periodontal diseases, we examined TCRBV gene usage and T-cell clonotypes of peripheral blood mononuclear cells incubated in the presence or absence of P. gingivalis outer membrane through a combination of reverse transcription polymerase chain reaction (RT-PCR) and subsequent single strand conformation polymorphism (SSCP) analysis. There was no difference in the mean expression for most BV families with or without P. gingivalis outer membrane in the culture. However, in individual cases, a few BV gene families did become overexpressed or underexpressed following stimulation, although a consistent pattern did not emerge. SSCP analysis showed that several new distinct bands appeared after stimulation, indicating distinct clonal accumulations, although the number of distinct bands decreased in most cases. These data suggest that clonotypic change occurred following stimulation with P. gingivalis outer membrane. Furthermore, the possibility of superantigen stimulation by P. gingivalis is unlikely to be due to the small change in BV gene usage and clonal T-cell accumulations with P. gingivalis outer membrane stimulation, as evidenced by SSCP. Thus, RT-PCR and SSCP analysis is useful in evaluating the host response to periodontopathic antigens.

Characteristics of Prevotella intermedia-specific CD4+ T cell clones from peripheral blood of a chronic adult periodontitis patient

Periodontitis is a chronic destructive inflammatory disease associated with periodontopathic bacteria. In addition, autoantigens such as collagen and heat shock proteins (hsp) have been suggested to play a role. Established periodontal lesions are characterized by dense infiltrations of immune cells such as cytokine-producing CD4+ and CD8+ T cells. CD4+ T cells specific for Prevotella intermedia can be isolated from lesional gingiva, suggesting an active role for CD4+ T cells in the response to this bacterium. We therefore investigated the characteristics of a panel of 13 P. intermedia-specific CD4+ T cells generated from the peripheral blood of a patient with chronic adult periodontitis. All 13 P. intermedia-specific CD4+ T cells recognized the antigens in the context of HLA-DR. The T cell clones were mainly classified as Th0, producing comparable amounts of interferon-gamma (IFN-gamma) and IL-4, and Th2, producing high amounts of IL-4 and almost no IFN-gamma. None of the P. intermedia-specific T cell clones recognized antigens of the periodontopathic bacteria Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis and of the autoantigens collagen and hsp. The reactivity profile of the T cell clones to size-fractionated cell envelope antigens of P. intermedia indicated that P. intermedia-specific CD4+ T cell clones recognize probably five different antigen specificities in the context of the MHC class II molecules, DR7 or DR15. These results suggest that a broad panel of cell-associated protein antigens play a role in the induction of P. intermedia-specific CD4+ T cell response.

Inflammatory mediators of the terminal dentition in adult and early onset periodontitis

Based upon the prosthodontic literature, subjects who are at the transition stage between natural dentition and edentulism are called "terminal dentition" (TD) cases. The aim of the present cross-sectional investigation was to characterize the local and systemic inflammatory responses in 2 groups of patients with terminal dentition periodontitis. Eight severe adult periodontitis terminal dentition (AP-TD) subjects and 8 early onset periodontitis terminal dentition (EOP-TD) subjects were entered into the study. Our purpose was to measure an extended battery of cytokines in the gingival crevicular fluid (GCF) and in lipopolysaccharide (LPS)-stimulated monocytic culture supernatants as well as gingival mononuclear cell messenger RNA (mRNA) transcripts determined from biopsy samples. Within the GCF there were 3 tiers (levels) of mediators based upon approximate 10-fold differences in concentration. The highest tier included prostaglandin E2 (PGE2), interleukin-1 beta (IL-1 beta) and interleukin-2 (IL-2), the intermediate tier included tumor necrosis factor alpha (TNF alpha) and interferon gamma (IFN-gamma) and at the lowest concentration level were interleukin-4 (IL-4) and interleukin-6 (IL-6). Thus, the GCF analysis clearly indicated that in both AP-TD and EOP-TD groups the monocytic, i.e. IL-1 beta and PGE2 and Th1, i.e. IL-2 and IFN-gamma, inflammatory mediator levels quantitatively dominated over the Th2 mediators, i.e. IL-4 and IL-6. LPS-stimulated monocytic release of IL-1 beta, PGE2 and TNF alpha was significantly elevated in both AP-TD and EOP-TD groups compared to those of a control group of 21 subjects with moderate to advanced adult periodontitis. The cytokine mRNA expression of isolated gingival mononuclear cells showed that in both the AP-TD and the EOP-TD groups Th1 and Th2 cytokines were expressed, with low levels of IL-4 and IL-12. In conclusion, our data suggest that this cross-sectional TD periodontitis model may reflect progressive periodontal disease associated with tooth loss. Furthermore, although Th1 cytokine levels in the GCF dominate over the Th2 response, monocytic activation provides the main source of proinflammatory mediators. In addition, LPS-stimulated peripheral blood monocytes demonstrate an upregulated inflammatory mediator secretion in the terminal dentition.

Antigen-presenting properties of gingival fibroblasts in chronic adult periodontitis

Chronic periodontitis is characterized by dense infiltrations of T lymphocytes in the connective tissue, which consists mainly of gingival fibroblasts. It is becoming increasingly clear that T lymphocytes and gingival fibroblasts are capable of influencing each other. For example, the T cell cytokine interferon-gamma (IFN-gamma) is able to induce MHC class II molecules on the surface of several cell types, including gingival fibroblasts. Histological sections of chronically inflamed gingival tissue showed a great number of CD4+ and CD8+ T cells that produced IFN-gamma, and in addition showed abundant expression of MHC class II molecules on gingival fibroblasts. Therefore, we investigated whether these gingival fibroblasts acquire the capacity to carry out MHC class II-restricted functions such as antigen presentation to local T cells. In this study, we show that IFN-gamma-treated gingival fibroblasts were able to function as antigen-presenting cells (APC) for superantigen-mediated T cell proliferation. However, these fibroblasts failed to present whole-cell antigens of periodontitis-associated bacteria. Moreover, gingival fibroblasts inhibited the presentation of the whole-cell antigens of these bacteria by professional APC. This inhibition could be overcome by the addition of IL-2. These results suggest that gingival fibroblasts play an important role in the local specific immune response in chronic inflammatory periodontal lesions by regulating the response of infiltrating T cells.

Cytokine messenger RNA expression in chronic inflammatory periodontal disease

It has previously been reported that, in periodontitis lesions, T cells with a memory/activated phenotype and with a type 2 cytokine profile accumulate in an oligoclonal fashion. Delineation of the role of cytokines in periodontal inflammation has, however, been complicated because of cross-regulation and because of their overlapping and often redundant effects. The aim of this study was to examine messenger RNA levels for interferon gamma, interleukin 4 (IL-4), IL-10, IL-12 and IL-13 in gingival tissues and peripheral blood mononuclear cells of patients with adult periodontitis. Reverse transcription polymerase chain reaction and subsequent image analysis was used to determine the level of mRNA for each cytokine. The mean expression of interferon gamma mRNA was significantly higher in peripheral blood mononuclear cells than in gingival tissues. In contrast, the mean expression of IL-10 mRNA was higher in gingival tissues than in peripheral blood mononuclear cells. This high expression of IL-10 mRNA was, in fact, seen in only 7 gingival tissue samples with the majority of samples showing levels similar to peripheral blood mononuclear cells. There was no difference in the mean expression of IL-12 p35 mRNA between gingival tissues and peripheral blood mononuclear cells. However, IL-12 p40 mRNA was expressed higher in gingival tissues than in peripheral blood mononuclear cells in 6 out of 16 samples with significant difference of mean expression. Like IL-10, gingival tissue samples and peripheral blood mononuclear cells expressed similar levels of IL-12 p40 mRNA. There was no difference in the mean expression of IL-13 in gingival tissues and peripheral blood mononuclear cells. Nevertheless, more peripheral blood mononuclear cell samples demonstrated high IL-13 mRNA expression than gingival tissue samples. IL-4 mRNA was weak but detectable in 3 gingival tissue samples. These results support the concept that cytokines form complex networks in periodontitis lesions and that their overlapping and redundant effects should be taken into account when considering the pathology of inflammatory periodontal disease. Dichotomous expression of IL-10 and IL-12 p40 mRNA in the periodontal lesion may be associated with disease entity.

Interleukin-10 promotes anti-collagen antibody production in type I diabetic peripheral B lymphocytes

Previous studies have shown that type I diabetes (IDDM) increases the risk of developing periodontitis by 2-3-fold. IDDM patients exhibit destruction of the pancreatic beta cells, most probably caused by an autoimmune reaction. Evidence is accumulating to support the role of the autoimmune response in periodontal pathogenesis. A cytokine, interleukin (IL)-10, has been reported to selectively promote the expansion of a B lymphocyte lineage (CD5/LY1/B1) which has the propensity for secreting high levels of autoantibody. Therefore, the purpose of this project was to evaluate IL-10 production, percentage of CD5 B cells and the frequency of anti-collagen secreting cells in peripheral blood mononuclear cells of age, gender and race matched IDDM patients and controls. IL-10 production was evaluated by an ELISA using the supernatant of adherent peripheral blood cells cultured for 24 h in the presence of Porphyromonas gingivalis lipopolysaccharide (LPS). In 8 of 31 patients, IL-10 levels were significantly increased in IDDM compared to controls and a higher percentage of CD5 B cells was also observed by flow cytometry. In addition, these patients exhibited a higher frequency of anti-collagen secreting cells as elucidated by an ELISPOT. Moreover, treatment with a neutralizing anti-IL-10 antibody diminished the anti-collagen antibody response by 70%. These findings support the concept that a subset of IDDM patients possess an extremely robust IL-10 response following exposure to Gram-negative LPS, which could predispose them to the development of periodontitis through a heightened autoimmune mechanism.