Autoimmunity in periodontal disease

Alopecia and Periodontitis: Exploring the connecting dots

Alopecia areata is a systemic disease with nonscarring hair loss from the scalp, face, or any part of the body. The disease with undetermined etiology and pathogenesis has a considerable impact on the social life of patients which gradually builds up stress and expedites further deterioration of their condition. Interestingly, in such patients, besides stress-relieving exercises and immunomodulators, well-timed dental assessment and prompt treatment have contributed to improving the prognosis of alopecia. This depicts an interrelationship between alopecia and oral foci of infections. Over the past few decades, periodontitis has remained to be one of the predominant forms of oral focus of infection for systemic diseases. The present review throws light on the role of stress and autoimmunity in establishing a possible correlation between alopecia and periodontitis. It is augmented with documented case reports, demanding a complete oral examination in patients with the unexplained origin of alopecia. An interdisciplinary approach is the need of the hour which can prevent the progression of both the diseases as well as other oral infections.

Diet-induced Generalized Periodontitis in Lewis Rats

Periodontitis is an important public health concern worldwide. Because rodents from the genus Rattus are resistant to spontaneous periodontitis, experimental periodontitis must be initiated by mechanical procedures and interventions. Due to their exacerbated Th1 response and imbalanced Th17 regulatory T-cell responses, Lewis rats are highly susceptible to inducible inflammatory and autoimmune diseases. We hypothesized that feeding Lewis rats a diet high in sucrose and casein (HSC) would alter the oral microenvironment and induce inflammation and the development of periodontitis lesions without mechanical intervention. A baseline group (BSL, n = 8) was euthanized at age 6 wk. Beginning at 6 wk of age, 2 groups of Lewis rats were fed standard (STD, n = 12) or HSC (n = 20) chow and euthanized at 29 wk of age. We evaluated the degree of periodontitis through histology and μCT of maxillae and mandibles. The HSC-induced inflammatory response of periodontal tissues was assessed by using immunohistochemistry. Gene expression analysis of inflammatory cytokines associated with Th1 and Th17 responses, innate immunity cytokines, and tissue damage in response to bacteria were assessed also. The potential systemic effects of HSC diet were evaluated by assessing body composition and bone densitometry endpoints; serum leptin and insulin concentrations; and gene expression of inflammatory cytokines in the liver. Placing Lewis rats on HSC diet for 24 wk induced a host Th1-immune response in periodontal tissues and mild to moderate, generalized periodontitis characterized by inflammatory cell infiltration (predominantly T cells and macrophages), osteoclast resorption of alveolar bone, and hyperplasia and migration of the gingival epithelium. HSC-fed Lewis rats developed periodontitis without mechanical intervention in the oral cavity and in the absence of any noteworthy metabolic abnormalities. Consequently, the rat model we described here may be a promising approach for modeling mild to moderate periodontitis that is similar in presentation to the human disease.

Role of autoimmune responses in periodontal disease

Periodontal diseases are characterized by localized infections and inflammatory conditions that directly affect teeth supporting structures which are the major cause of tooth loss. Several studies have demonstrated the involvement of autoimmune responses in periodontal disease. Evidences of involvement of immunopathology have been reported in periodontal disease. Bacteria in the dental plaque induce antibody formation. Autoreactive T cells, natural killer cells, ANCA, heat shock proteins, autoantibodies, and genetic factors are reported to have an important role in the autoimmune component of periodontal disease. The present review describes the involvement of autoimmune responses in periodontal diseases and also the mechanisms underlying these responses. This review is an attempt to throw light on the etiopathogenesis of periodontal disease highlighting the autoimmunity aspect of the etiopathogenesis involved in the initiation and progression of the disease. However, further clinical trials are required to strengthen the role of autoimmunity as a cause of periodontal disease.

Patients with Peri-Implantitis, unlike Those with a Healthy Peri-Implant Microenvironment, Display Antibodies to More Than One Heat Shock Protein (HSP 27, HSP 65 and HSP 90) Linear Epitope

The success of a dental implant treatment requires hard and soft tissue integration and osseointegration, mechanisms that entail a direct anchorage of the implant in the bone without interposition of soft tissue. Peri-implantitis is defined as an inflammatory reaction of the tissues surrounding a functioning dental implant. During inflammation, a high incidence of autoantibodies has been reported. The hypothesis of the present study is that the occurrence of autoantibodies to self-antigens including extracellular matrix (ECM) molecules and heat shock proteins (HSPs) might affect the dental implant outcome. Therefore, we evaluated the occurrence of antibodies to ECM molecules (Collagen (C) I, III, IV, V, fibronectin, laminin) and HSPs (HSP 27, HSP 65, HSP 90) in subjects with a healthy peri-implant microenvironment (n=29) as compared to patients with peri-implantitis (n=13). We also evaluated the HSP 27 expression in gingival fibroblasts grown in an inflammatory microenvironment. Antibodies to conformational ECM epitopes of CI, CIII and laminin were observed both in subjects with healthy peri-implant conditions and peri-implantitis. Antibodies to more than one HSP linear epitope were found in patients with peri-implantitis but not with healthy peri-implant conditions (p=0.024). Gingival fibroblasts grown in an inflammatory microenvironment showed increased HSP 27 cytoplasmic and plasma membrane expression as compared to fibroblasts grown in normal conditions. Immunity to multiple linear HSPs epitopes in patients with peri-implantitis and not in patients with a healthy peri-implant microenvironment might be relevant for monitoring the implant outcome and help to understand the role of subsets of autoantibodies in implant osseointegration.

Involvement of autoimmunity in the pathogenesis of aggressive periodontitis

The aim of this study was to investigate the involvement of autoimmune reactions to native and post-translationally modified extracellular matrix components in the pathogenesis of periodontitis. Sera from individuals with aggressive periodontitis (AgP, n = 25), chronic periodontitis (CP, n = 14), and gingivitis (G, n = 18) were tested for the presence of autoantibodies against: (a) native collagen type I (CI) and collagen type III (CIII); (b) CI and CIII post-translationally modified by reactive oxygen species (ROS) of the type present during inflammation; and (c) citrullinated filaggrin-derived peptides (CCP). Autoantibodies to native and ROS-modified CI and CIII as well as autoantibodies to CCP were observed exclusively in patients with AgP and not in those with CP or G. In conclusion, autoimmune reactions to native and post-translationally modified self-antigens may play a role specifically in the pathogenesis of AgP.

Autoreactivity of serum immunoglobulin to periodontal tissue components: a pilot study

BACKGROUND

Periodontal diseases are inflammatory diseases resulting in the destruction of tissues of the periodontium. Although bacteria must be present for periodontal disease to occur, a susceptible host is also required, which is determined by genetic, environmental, and acquired factors. One such factor, autoimmunity, may play a role in the tissue destruction. Data indicate that some antibodies that occur in the gingival lesion are directed to host tissue components, such as type I collagen, although investigations of other periodontal autoimmune targets are limited.

METHODS

Histologic sections and extracts from periodontally healthy teeth and the associated soft tissues were probed with serum from localized aggressive periodontitis (LAgP), chronic periodontitis (CP), and periodontally healthy subjects to determine autoreactivity to components of the periodontium. Any autoreactivity observed was characterized further by mass spectrometry and enzyme-linked immunosorbent assay.

RESULTS

Autoreactivity to components of the periodontium was observed in CP and LAgP. Known autoimmune targets, such as collagen and heat shock protein, were identified along with multiple potential autoimmune targets, including members of the extracellular matrix, such as vimentin, spectrin, filamin, actin, lamin, keratin, and tubulin. Finally, it was determined that the autoreactivity observed in LAgP was more severe and diverse than that observed in CP.

CONCLUSION

These data demonstrated that autoimmune reactivity can play a role in the tissue destruction of periodontal disease but that the nature of the autoreactivity may differ based on the type and/or stage of periodontal disease.

Autoantibodies directed to extracellular matrix components in patients with different clinical forms of periodontitis

BACKGROUND

Periodontal disease occurs in different clinical forms, from mild and easily controllable to more aggressive inflammatory manifestations, with difficult clinical or surgical control. There is evidence that a local autoimmune reaction may participate in the onset and persistence of the aggressive forms of periodontal disease. As the underlying mechanism in this process is not fully understood, we decided to investigate whether patients bearing this form of disease presented higher levels of antibodies directed to extracellular matrix (ECM) components such as type I collagen, fibronectin, and laminin.

METHODS

Three groups of patients were selected by clinical criteria: 22 subjects with aggressive periodontitis (AgP) = group A; 18 subjects with chronic periodontitis (CP) = group B; and 10 healthy (H) volunteers without periodontal disease = group C. Autoantibody levels were evaluated in the sera of these patients using the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

The levels of autoantibodies directed to ECM components (type I collagen, fibronectin and laminin) in the sera of patients with AgP and CP were shown to be statistically different (P <0.05).

CONCLUSIONS

Although the present findings suggest an involvement of autoantibodies directed to ECM components per se in the pathogeny of certain types of periodontal disease, the available data do not support the classification of the lesions as autoimmune. Nevertheless, the findings open a possibility for the development of an additional method for a differential diagnosis of the aggressive forms of periodontal disease.

Anti-Neutrophil Cytoplasmic Autoantibodies: A Renewed Paradigm in Periodontal Disease Pathogenesis?

In the past, various models including the autoimmunity model have been proposed to explain the pathogenesis of periodontal diseases. The aim of this review is to introduce the pathogenic role of anti-neutrophil cytoplasmic autoantibodies (ANCAs) in various autoimmune diseases and compare these conditions with periodontal disease to elucidate common pathogenic mechanisms. Also, a novel model to explain the pathogenesis of periodontal disease based on the concept of ANCA-associated autoimmunity is proposed. This encompasses a wide array of biochemical mediators that range from direct and indirect initiators of ANCA production and eventual release of proinflammatory mediators and free radicals, all of which have been implicated in periodontal tissue destruction in the past. In addition, specific links between the typical ANCA-associated diseases and periodontal disease are discussed. Finally, a new paradigm in the periodontal disease-associated destruction is proposed that includes the currently accepted mechanism, namely, the genetic-microbial-host interactions.

A Model of Spontaneous Periodontitis in the Miniature Goat

BACKGROUND

The pathogenesis and progression of periodontal disease have been extensively studied through the use of animal models. However, no animal model has yet been established that is precisely similar to periodontitis in humans. In the present study, we examined the use of Shiba goats as a model for spontaneous periodontitis.

METHODS

Thirty-four Shiba goats (seven males and 27 females, aged 10 to 98 months) were used. We examined periodontitis in Shiba goats clinically, histopathologically, and microbiologically.

RESULTS

The mean probing depth (PD) of the 68 teeth examined was 2.7 +/- 0.8 mm. The incidences of PD > or =3 and 4 mm were 46.4% and 22.1%, respectively. The incidence of bleeding on probing in 68 sites and in 34 animals was 60.7% and 73.5%, respectively. The formation of vertical alveolar bone defects and downgrowth of gingival epithelial cells were found in the areas of periodontitis. The prevalence of Tannerella forsythensis, Campylobacter rectus, Fusobacterium necrophorum, Fusobacterium nucleatum, and Actinobacillus actinomycetemcomitans in subgingival plaque by polymerase chain reaction was 46.4%, 28.5%, 28.5%, 17.8%, and 3.5%, respectively. These percentages were increased in subgingival plaque from PD > or =3 mm.

CONCLUSIONS

The clinical, histopathological, and microbiological features of spontaneous periodontitis in Shiba goats were somewhat similar to those in human periodontitis. Moreover, there are some advantages of using the Shiba goat; the size of the oral cavity is suitable for periodontal treatment, and handling and housing are relatively easy. Therefore, these results suggest that the Shiba goat is a useful animal model for human periodontitis.

Streptococci and Actinomyces induce antibodies which cross react with epithelial antigens in periodontitis

Perturbation of epithelial structure is a prominent but poorly understood feature of the immunopathological response to bacterial antigens which characterizes the destructive lesion of periodontitis. Western analysis of sera from 22 patients with periodontitis detected multiple antigens in extracts of epithelial cells whereas sera from 12 periodontally healthy subjects displayed only trace reaction with epithelial antigens. To investigate a possible relationship between the bacterial flora adjacent to diseased sites and the presence of antibodies reactive with epithelium, subgingival plaque samples were taken from deep periodontal pockets and cultured anaerobically. Gram positive bacteria containing antigens cross-reactive with epithelial cells were reproducibly isolated by probing membrane colony-lifts with affinity-isolated (epithelium-specific) antibodies and identified by 16S rDNA sequence homology as streptococci (S. mitis, S. constellatus and two S. intermedius strains) and Actinomyces (A. georgiae, and A. sp. oral clone). Conversely, when serum from patients with periodontitis was absorbed with the captured bacterial species the number of epithelial antigens recognized was specifically reduced. It was concluded that development of cross-reactive antibodies related to these organisms may contribute to perturbation of the epithelial attachment to the tooth and the progression of periodontitis. These autoreactive antibodies could also be a contributing factor in other diseases affecting epithelia.

Serum IgG to heat shock proteins and Porphyromonas gingivalis antigens in diabetic patients with periodontitis

BACKGROUND

Past studies have reported a correlation between the presence and severity of periodontitis and serum antibody titers to species-specific antigens of Porphyromonas gingivalis or to cross-reactive antigens, such as lipopolysaccharide (LPS) and heat shock proteins (HSP), shared between P. gingivalis and other bacteria. Our recent study of periodontal treatment outcome in insulin-dependent (type 1) diabetes mellitus patients with severe periodontitis (IDDMI/periodontitis) resulted in two key findings: 1. serum glutamic acid decarboxylase autoantibody (GAD65 Ab) levels were significantly associated with periodontal pocket depth change (PDC) and 2. serum IgG titers to P. gingivalis cells were positively associated with GAD65 Ab level in seropositive (GAD65 Ab +) patients. We have therefore hypothesized that profiles of serum autoantibody levels and IgG titers, to P. gingivalis-specific antigens may be useful in assessing risk for refractory periodontitis in such patients.

AIM

To determine whether PDC resulting from non-surgical periodontal treatment can be predicted using profiles of baseline IgG titers to P. gingivalis-specific antigens, human HSP, and GAD65.

METHODS

PDC was assessed two months after non-surgical periodontal treatment of 7 GAD65 Ab + and 11 GAD65 AbIDDM/periodontitis patients. Pretreatment titers to GAD65, recombinant human heat shock proteins (HSP90, HSP70, and HSP60), and various P. gingivalis antigens were measured using radioligand precipitation or enzyme-linked immunosorbent (ELISA) assays and compared to the same measurements for 154 recent-onset IDDM patients and 46 non-diabetic controls.

RESULTS

Median titers (ELISA units) to HSP90 and HSP70 were significantly higher than non-diabetic controls for GAD65 Ab + (p degrees = 0.002) and GAD65 Ab- (p = 0.034) IDDM/periodontitis patients, respectively. Multivariate regression analysis indicated significant partial correlation of PDC with log-transformed titers to HSP90 (r = - 0.62, p = 0.008), HSP70 (r = + 0.62, p = 0.009), GAD65 (r = - 0.60, p = 0.01) and P. gingivalis LPS (r = - 0.5 1, p = 0.04). Furthermore, hierarchical clustering of baseline profiles of log-transformed HSP90, HSP70, and GAD65 Ab titers sorted patients into two distinct clusters with significantly different median PDC (1.45 min, n = 10 vs. 0.65 min, n = 8; p = 0.016, Mann-Whitney).

CONCLUSION

Pretreatment profiles of serum antibody titers to HSP90, HSP70, GAD65, and P. gingivalis LPS may be useful for predicting which patients with IDDM/periodontitis will have a poor response to non-surgical periodontal therapy.

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.

Treatment outcome for IDDM patients in relation to glutamic acid decarboxylase autoantibodies and serum IgG to periodontal pathogens

BACKGROUND

Patients with insulin-dependent diabetes mellitus (IDDM) have elevated risk for periodontitis (PD) relative to subjects without diabetes. Whether refractory PD in IDDM patients is related to autoimmunity as indicated by serum glutamic acid decarboxylase autoantibody GAD Ab levels or to host bacterial immunity as reflected by serum antibody titers to periodontal pathogens is unknown.

AIMS

To determine if non-surgical periodontal treatment outcome differs between GAD Ab-seropositive and -seronegative IDDM patients by assessing the following parameters: (1) pretreatment serum levels of GAD Ab, (2) pretreatment serum IgG titers to key periodontal pathogens, and (3) changes in periodontal pocket probing depth (PDC) after treatment.

METHODS

Before and two months after periodontal treatment of 11 GAD Ab-seronegative and 7 -seropositive subjects, PDC was assessed and serum GAD Ab and IgG to Porphyromonas gingivalis (Pg), Bacteroides forsythus (BJ), and Actinobacillus actinomycetemcomitans (Aa) were studied using established radioligand precipitation and enzyme-linked immunosorbent assays, respectively.

RESULTS

The PDC decrease was significantly better for GAD Ab-seronegative subjects than for seropositive subjects (median 1.4 mm+/-0.5 s.d. versus 0.5 mm+/-0.3 s.d., p<0.03, Mann-Whitney). GAD Ab levels and PDC were positively correlated (r=+0.71, p<0.05) for sero-positive subjects but were neutral (r=-0.07) for seronegative subjects. Serum IgG to Pg and GAD Ab levels were positively associated (r2=0.42) in seropositive subjects. Logistic regression analysis confirmed that GAD Ab status was the primary discriminator for PDC (p<0.04).

CONCLUSION

Detection of elevated GAD Ab levels in combination with elevated IgG titers to Pg before treatment is indicative of IDDM patients with refractory PD.

Identification and nucleotide sequence of the heat shock protein 60 (GroEL) gene of Bacteroides forsythus

Bacteroides forsythus is a Gram negative anaerobe associated with human periodontal disease. Heat shock proteins are immunodominant antigens in bacteria that can elicit strong and protective immune responses. The gene specifying the GroEL protein (hsp60, heat shock protein 60) of B. forsythus was isolated by PCR amplification using consensus primers based upon published nucleotide sequences of the groEL genes of several bacterial species. Translation of the gene sequence predicts a protein of 544 amino acids in length with a molecular mass of 58 kDa. B. forsythus GroEL demonstrates identities of 50 to 81% with the predicted amino acid sequences of GroEL proteins of several bacterial species and the human mitochondrial P1 protein.

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.

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.

Polyclonal B cell activators and in vitro induction of auto-antibody reactive with collagen

Cells producing autoantibodies are known to be present in chronically inflamed periodontal tissues. In sites of chronic inflammation, polyclonal B cell activators (PBA) are known to exhibit adjuvant activity when combined with foreign antigens. These results prompted an examination of PBA in eliciting an antibody response to an autoantigen (i.e. collagen type I). Rat lymphocytes were stimulated with rat collagen (type I), microbial PBA (LPS) or the combination of LPS plus rat collagen in vitro. Anti-collagen antibody-forming cells (AFC) were enumerated using an ELISPOT assay. Collagen or LPS alone elicited few anti-collagen AFC but the addition of LPS to collagen resulted in a substantial adjuvant effect and yielded maximal responses to collagen. Comparisons of anti-collagen AFC from short-term immunized (2-6 wk after booster), non-immunized and long-term immunized (3-4 months after booster) animals were performed. It revealed that cells from recently immunized rats were significantly easier to activate than the other 2 groups. The adjuvant effect of microbial PBA may be important in anti-collagen antibody production and thus the localization of PBA in periodontal pockets may explain why anti-collagen AFC are restricted to the chronically inflamed periodontal tissues.

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.

Mammalian viruses in human periodontitis

A prior investigation has demonstrated a higher prevalence of human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV) in subgingival specimens from periodontitis patients than from gingivitis patients. This study aimed to determine the frequency of HCMV, EBV-1, EBV-2, herpes simplex virus (HSV) and human immunodeficiency virus (HIV) in subgingival samples from 27 adults who each contributed both a periodontitis and a gingivitis site. Viral detection was performed using a nested-polymerase chain reaction method. Twenty-four subjects (89%) yielded at least one of the five test viruses from deep periodontal pockets, whereas only 15 (56%) showed viruses from shallow periodontal sites (P = 0.015; chi-square test). Viral co-infection occurred more frequently in deep than in shallow periodontal sites (P = 0.015). HCMV was detected with higher frequency in deep than in shallow periodontal sites (P = 0.023). The possible periodontopathogenic mechanisms of mammalian viruses in human periodontitis are discussed. The role and importance of HCMV and other mammalian viruses in the initiation and progression of destructive periodontal disease merits further investigation.

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

Chronic periodontitis is characterized by dense infiltrations of B and T lymphocytes within the gingival connective tissue. Distinct anaerobic gram-negative bacteria as well as autoimmunity to collagen have been reported to play a role in the etiology and the pathogenesis of this disease. Here we describe the cloning and characterization of CD4+ and CD8+ T lymphocytes isolated from inflamed gingival tissue obtained from four patients with chronic periodontitis. Clones were raised with phytohemagglutinin and interleukin-2 and tested for proliferation in response to whole-cell antigens of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, human collagen type I, and two bacterial heat shock proteins. CD4+ T-cell clones reactive with collagen type I were obtained from all four patients. Eighty percent of these clones had phenotypes resembling the mouse type 2 T helper (Th) phenotype, i.e., they produced high levels of interleukin-4 and low levels of gamma interferon. No collagen-type-I-reactive CD8+ clones were obtained. Bacterial-antigen-reactive CD4+ and/or CD8+ T-cell clones were also obtained from each patient, and the majority of the clones showed a Th0-like cytokine pattern and produced equal amounts of interleukin-4 and gamma interferon. Although most clones were reactive with P. intermedia, it seems that the immune response is not strictly directed against this particular microorganism, as clones reactive with one of the other bacteria were also obtained from two patients. We propose that collagen-specific CD4+ Th2-like T cells contribute to the chronicity of periodontitis but that their modes of activation might be controlled by Th0-like T cells specific for periodontitis-associated bacteria.