Conversion of a stable T-cell lesion to a progressive B-cell lesion in the pathogenesis of chronic inflammatory periodontal disease: an hypothesis

Alveolar bone loss is a significant contributor to tooth loss in dentate HIV+ patients: A retrospective study

BACKGROUND

The study objectives were to determine tooth loss prevalence and to investigate the relationship between tooth loss and potential risk factors among adult dentate HIV+ patients on newer antiretroviral therapy (ART) regimens.

METHODS

Health records of 450 human immunodeficiency virus (HIV)-infected individuals were surveyed. Eighty-eight records of dentate HIV+ individuals with full-mouth periodontal charting and intra-oral periapical radiographs were identified. We collected data on demographics, systemic risk factors, oral health, and HIV disease measures. Caries exposure and alveolar bone loss (ABL) were radiographically assessed.

RESULTS

Eighty-eight percent of patients showed tooth loss. Patients with ABL ≥15% had a higher number of missing teeth (p < .01). Stepwise regression analyses indicated that tooth loss was positively associated with age (β = 0.45, p < .01) and ABL (β = 0.39, p < .01). By contrast number of years on ART was negatively associated with tooth loss (β = -0.28, p < .05).

CONCLUSIONS

Tooth loss remains prevalent among HIV+ patients, and periodontal disease is a significant contributor. The number of years on ART seem to improve oral health behavior and reduce tooth loss.

Identifying immuno-related diagnostic genes and immune infiltration signatures for periodontitis and alopecia areata

BACKGROUND

Although there have been indications that periodontitis (PD) may be susceptible to alopecia areata (AA), the underlying mechanism of its pathogenesis remains poorly understood. The objective of our study is to conduct further research into the occurrence of this complication.

METHODS

The gene expression omnibus (GEO) database was the source of acquisition for both PD and AA datasets. Various methods, including the differentially expressed genes (DEGs) analysis, functional enrichment analysis, protein-protein interaction (PPI) network construction, Cytohubba algorithms, and RandomForest algorithms, were utilized to identify candidate hub immuno-related genes (IRGs) for diagnosing AA with PD. The diagnostic efficacy was assessed by constructing receiver operating characteristic (ROC) curves. To further deepen our understanding, immune cell infiltration, flow cytometry assay, and immunofluorescence techniques were employed to uncover immune cell dysregulation in PD and AA.

RESULTS

899 and 803 DEGs were detected in AA and PD, respectively, with an intersection of 150 common DEGs enriched in immune regulation. Further analysis of the junction of shared DEGs and IRGs was analyzed using the PPI network, Mcode, and Cytohubba algorithms. Three hub genes (CTSS, IL2RG, and ITGAL) were subsequently selected by Cytohubba and RandomForest algorithms and were found to be promising candidate hub genes with high diagnostic values (AUC ranging from 0.776 to 0.909) for diagnosing AA with PD. Additionally, various dysregulated immune cells were observed, with mast cells potentially serving as markers for AA and plasma for PD.

CONCLUSION

Three candidate hub IRGs (CTSS, IL2RG, and ITGAL) were identified with considerable diagnostic values. Besides, mast cells could serve as markers for AA, while plasma may indicate PD. Our research has the potential to identify shared diagnostic candidate genes and immune cells for AA and PD patients.

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.

The familial trend of the local inflammatory response in periodontal disease

OBJECTIVES

The imbalanced host response in front of a dysbiotic biofilm is one of the major aspects of severe periodontitis, which also presents a strong familial aggregation related to the susceptibility factors transmission within family members. This study hypothesized that aggressive periodontitis (GAgP) patients and their descendants could present a similar trend of a local inflammatory response that is different from healthy controls.

METHODS

Fifteen GAgP subjects and their children and fifteen healthy subjects and their children were clinically assessed, and the concentration of interferon (IFN)-γ, interleukin (IL)-10, IL-17, IL-1β, IL-4, IL-6, IL-8, and tumor necrosis factor (TNF)-α was evaluated in the gingival fluid using the multiplexed bead immunoassay.

RESULTS

Children from the GAgP group presented lower IL-10 and IFN-γ subgingival concentration than Health children, despite no difference in the clinical parameters. GAgP parents showed a lower IFN-γ, IL-10, and IL-6 than healthy subjects. IL-10/IL-1β and IFN-γ/IL-4 ratios were reduced in GAgP dyads, suggesting a familial trend in the subgingival cytokine's profile. The cytokines correlated to the clinical data and were predictors of probing depth increase.

CONCLUSION

GAgP parents and their children presented a similar cytokine profile and an imbalance in the subgingival response characterized by decreased IFN-γ/IL-4 and IL10/IL-1β ratios.

Tristetraprolin Is Required for Alveolar Bone Homeostasis

Tristetraprolin (TTP) is an RNA-binding protein that targets numerous immunomodulatory mRNA transcripts for degradation. Many TTP targets are key players in the pathogenesis of periodontal bone loss, including tumor necrosis factor-α. To better understand the extent that host immune factors play during periodontal bone loss, we assessed alveolar bone levels, inflammation and osteoclast activity in periodontal tissues, and immune response in draining cervical lymph nodes in TTP-deficient and wild-type (WT) mice in an aging study. WT and TTP-deficient (knockout [KO]) mice were used for all studies under specific pathogen-free conditions. Data were collected on mice aged 3, 6, and 9 mo. Microcomputed tomography (µCT) was performed on maxillae where 3-dimensional images were generated and bone loss was assessed. Decalcified sections of specimens were scored for inflammation and stained with tartrate-resistant acid phosphate (TRAP) to visualize osteoclasts. Immunophenotyping was performed on single-cell suspensions isolated from primary and peripheral lymphoid tissues using flow cytometry. Results presented indicate that TTP KO mice had significantly more alveolar bone loss over time compared with WT controls. Bone loss was associated with significant increases in inflammatory cell infiltration and an increased percentage of alveolar bone surfaces apposed with TRAP+ cells. Furthermore, it was found that the draining cervical lymph nodes were significantly enlarged in TTP-deficient animals and contained a distinct pathological immune profile compared with WT controls. Finally, the oral microbiome in the TTP KO mice was significantly different with age from WT cohoused mice. The severe bone loss, inflammation, and increased osteoclast activity observed in these mice support the concept that TTP plays a critical role in the maintenance of alveolar bone homeostasis in the presence of oral commensal flora. This study suggests that TTP is required to inhibit excessive inflammatory host responses that contribute to periodontal bone loss, even in the absence of specific periodontal pathogens.

Azithromycin as an adjunct to non-surgical periodontal therapy: a systematic review

The aim of this study was to investigate the current published work relating to the clinical benefits of the use of systemic azithromycin as an adjunct to non-surgical periodontal therapy. A published work search of PubMed, EMBASE and Cochrane Register of Controlled Trials up to 27 April 2016 was undertaken. The large degree of heterogeneity in the types of studies, treatment protocols, test subjects, sample size and exclusion criteria indicated that the use of narrative synthesis of all relevant studies was a valid method of review. Of the 194 eligible studies, 15 were found to be of relevance. The majority of studies demonstrated an additional clinical benefit when azithromycin is used as an adjunct to non-surgical periodontal therapy, particularly in deeper pockets (≥6 mm). In conclusion, the current body of research on the adjunctive use of systemic azithromycin in non-surgical periodontal therapy suggests there is a clinical benefit and that this benefit is greatest in deeper initial pockets (≥6 mm). The findings also suggest that future studies need to be more careful in subject selection to identify susceptible patients or at risk sites, both the immunoregulatory effects and antibiotic resistance of azithromycin needs to be reported, and that study populations need to be more homogeneous.

Chemokines in Oral Inflammatory Diseases: Apical Periodontitis and Periodontal Disease

The inflammatory oral diseases are characterized by the persistent migration of polymorphonuclear leukocytes, monocytes, lymphocytes, plasma and mast cells, and osteoblasts and osteoclasts. In the last decade, there has been a great interest in the mediators responsible for the selective recruitment and activation of these cell types at inflammatory sites. Of these mediators, the chemokines have received particular attention in recent years. Chemokine messages are decoded by specific receptors that initiate signal transduction events, leading to a multitude of cellular responses, including chemotaxis and activation of inflammatory and bone cells. However, little is known about their role in the pathogenesis of inflammatory oral diseases. The purpose of this review is to summarize the findings regarding the role of chemokines in periapical and periodontal tissue inflammation, and the integration, into experimental models, of the information about the role of chemokines in human diseases.

Human Memory B Cells in Healthy Gingiva, Gingivitis, and Periodontitis

The presence of inflammatory infiltrates with B cells, specifically plasma cells, is the hallmark of periodontitis lesions. The composition of these infiltrates in various stages of homeostasis and disease development is not well documented. Human tissue biopsies from sites with gingival health (n = 29), gingivitis (n = 8), and periodontitis (n = 21) as well as gingival tissue after treated periodontitis (n = 6) were obtained and analyzed for their composition of B cell subsets. Ag specificity, Ig secretion, and expression of receptor activator of NF-κB ligand and granzyme B were performed. Although most of the B cell subsets in healthy gingiva and gingivitis tissues were CD19(+)CD27(+)CD38(-) memory B cells, the major B cell component in periodontitis was CD19(+)CD27(+)CD38(+)CD138(+)HLA-DR(low) plasma cells, not plasmablasts. Plasma cell aggregates were observed at the base of the periodontal pocket and scattered throughout the gingiva, especially apically toward the advancing front of the lesion. High expression of CXCL12, a proliferation-inducing ligand, B cell-activating factor, IL-10, IL-6, and IL-21 molecules involved in local B cell responses was detected in both gingivitis and periodontitis tissues. Periodontitis tissue plasma cells mainly secreted IgG specific to periodontal pathogens and also expressed receptor activator of NF-κB ligand, a bone resorption cytokine. Memory B cells resided in the connective tissue subjacent to the junctional epithelium in healthy gingiva. This suggested a role of memory B cells in maintaining periodontal homeostasis.

Gingival crevicular fluid and serum levels of APRIL, BAFF and TNF-alpha in rheumatoid arthritis and osteoporosis patients with periodontal disease

BACKGROUND

This study was performed to evaluate gingival crevicular fluid (GCF) and serum levels of a proliferation inducing ligand (APRIL) and B cell activating factor (BAFF) and compare this to differences between TNF-alpha levels in rheumatoid arthritis (RA), osteoporosis (OPR) and systemically healthy women with periodontal disease (SH).

DESIGN

Gingival crevicular fluid (GCF) and serum samples were obtained before any periodontal intervention from 17 RA, 19 OPR patients and 13 SH women with periodontitis. Full-mouth clinical periodontal measurements were recorded. APRIL, BAFF and TNF-α levels were determined by ELISA. Statistical analysis was performed using multivariate analysis, ANOVA and Spearman correlation.

RESULTS

Pocket depths differed in site-specific comparisons, but otherwise clinical measurements were similar in the three study groups. Multivariate least squares regression ANOVA adjusted for age and for plaque index indicated that total amounts of TNF-α and concentrations of TNF-α, BAFF and APRIL were significantly greater in the RA patients than in the SH group (p<0.05), and GCF concentrations of BAFF were greater in OPR patients than in SH. Serum TNF-α and BAFF were significantly higher in the RA group compared to SH (p<0.05) and serum TNF-α was greater in RA than in OPR (p<0.05). APRIL and BAFF correlated with RANKL levels in GCF and serum (p<0.05).

CONCLUSION

Despite long-term usage of anti-inflammatory drugs in the RA and OPR patients, increased TNF-family cytokines, might suggest that these patients have a propensity to overproduce these inflammatory mediators but whether this results from greater disease activity or contribute to greater disease activity remains moot.

Saliva and serum levels of B-cell activating factors and tumor necrosis factor-α in patients with periodontitis

BACKGROUND

B-lymphocytes play a central and critical role in the adaptive immune response against invading pathogens. This study evaluates saliva and serum levels of APRIL (a proliferation-inducing ligand), B-cell activating factor (BAFF), tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-10 in patients with chronic periodontitis (CP) or aggressive periodontitis (AgP) and periodontally healthy individuals.

METHODS

Twenty-five patients with AgP, 20 patients with CP, and 20 periodontally healthy individuals were included. Smoking status was recorded, and all individuals were divided into non-smokers and smokers. Saliva and serum samples were collected before clinical periodontal measurements. APRIL, BAFF, TNF-α, IL-6, and IL-10 levels in serum and saliva samples were determined by enzyme-linked immunosorbent assay. Statistical analysis was performed using multivariate analysis of variance and bivariate correlation.

RESULTS

Serum and saliva levels of TNF-α, APRIL, BAFF, IL-6, and IL-10 were similar in CP and AgP groups. Serum levels of TNF-α, APRIL, and BAFF and saliva levels of BAFF were significantly higher in periodontitis groups than healthy controls (P <0.05). Non-smokers with CP or AgP had lower levels of saliva TNF-α and APRIL and serum APRIL and IL-6 than smokers with CP or AgP (P <0.05). Saliva APRIL and serum TNF-α and IL-6 levels were significantly higher in healthy smokers than healthy non-smokers (P <0.05). Clinical periodontal parameters correlated positively with TNF-family cytokines and negatively with IL-10 (P <0.05).

CONCLUSIONS

Within the limits of this study, it may be suggested that elevated salivary and serum TNF-α, APRIL, and BAFF in patients with periodontitis may contribute to the dominance of B cells in periodontitis lesions. Moreover, higher levels in healthy smokers than non-smoking counterparts may play a role in detrimental effects of smoking on periodontal tissues.

Role of TLR2-dependent IL-10 production in the inhibition of the initial IFN-γ T cell response to Porphyromonas gingivalis

P.g., a Gram-negative bacterium, is one of the main etiological agents of the chronic inflammatory disease, periodontitis. Disease progression is thought to occur as a result of an inadequate immune response, which although happens locally, can also occur distally as a result of the dissemination of P.g. into the circulation. As IL-10 and TLR2 are pivotal molecules in the immune response that P.g. elicits, we hypothesized that TLR2-mediated IL-10 production, following the initial systemic exposure to P.g., inhibits the IFN-γ T cell response. To address this hypothesis, mice were primed with P.g., and the types of cells producing IL-10 and the capacity of T cells to produce IFN-γ following blocking or neutralization of IL-10 were assessed. Our results showed that upon initial encounter with P.g., splenic T cells and CD11b(+) cells produce IL-10, which when neutralized, resulted in a substantial increase in IFN-γ production by T cells. Furthermore, IL-10 production was dependent on TLR2/1 signaling, partly in response to the major surface protein, FimA of P.g. In addition, P.g. stimulation resulted in the up-regulation of PD-1 and its ligand PD-L1 on CD4 T cells and CD11b(+) cells, respectively. Up-regulation of PD-1 was partially dependent on IL-10 but independent of TLR2 or FimA. These results highlight the role of IL-10 in inhibiting T cell responses to the initial systemic P.g. exposure and suggest multiple inhibitory mechanisms potentially used by P.g. to evade the host's immune response, thus allowing its persistence in the host.

The interleukin-4 -34TT and -590TT genotype is correlated with increased expression and protein production in aggressive periodontitis

Aggressive periodontitis (AgP) is a severe periodontal disease characterized by rapid destruction of the tissues supporting the teeth in otherwise healthy individuals. The frequency of the interleukin-4 homozygous -34TT and -590TT genotype was increased in patients in comparison with controls. This study aimed to test the functional effect of this specific genotype in AgP patients by analyzing gene expression of IL-4 and STAT6, and protein concentration of IL-4, in activated CD4+ T cells. Results revealed an increased IL-4 and STAT6 expression and IL-4 production in the cells of the patients who were homozygous for the -34T and -590T alleles in comparison with the patients who were homozygous for the -34C and -590C alleles (p<0.05). These findings demonstrate that the IL-4 -34TT and -590TT genotype has a functional effect on T helper (Th) cells of patients with AgP, inducing increased expression of IL-4 and STAT6, and increased production of IL-4.

Mapping the pathogenesis of periodontitis: a new look

Chronic adult periodontitis is a bacterially induced chronic inflammatory disease that destroys the connective tissue and bone that support teeth. Concepts of the specific mechanisms involved in the disease have evolved with new technologies and knowledge. Histopathologic observations of diseased human tissues were used previously to speculate on the causes of periodontitis and to describe models of pathogenesis. Experimental evidence later emerged to implicate bacterial plaque deposits as the primary factor initiating periodontitis. At the same time, specific bacteria and immunoinflammatory mechanisms were differentially implicated in the disease. In the mid-1990s, early insights about complex diseases, such as periodontitis, led to new conceptual models of the pathogenesis of periodontitis. Those models included the bacterial activation of immunoinflammatory mechanisms, some of which targeted control of the bacterial challenge and others that had adverse effects on bone and connective tissue remodeling. Such models also acknowledged that different environmental and genetic factors modified the clinical phenotype of periodontal disease. However, the models did not capture the dynamic nature of the biochemical processes, i.e., that innate differences among individuals and changes in environmental factors may accelerate biochemical changes or dampen that shift. With emerging genomic, proteomic, and metabolomic data and systems biology tools for interpreting data, it is now possible to begin describing the basic elements of a new model of pathogenesis. Such a model incorporates gene, protein, and metabolite data into dynamic biologic networks that include disease-initiating and -resolving mechanisms. This type of model has a multilevel framework in which the biochemical networks that are regulated by innate and environmental factors can be described and the interrelatedness of networks can be captured. New models in the next few years will be merely frameworks for integrating key knowledge as it becomes available from the "-omics" technologies. However, it is possible to describe some of the key elements of the new models and discuss distinctions between the new and older models. It is hoped that improved conceptual models of pathogenesis will assist in focusing new research and speed the translation of new data into practical applications.

Increased susceptibility to tumor necrosis factor-alpha in butyric acid-induced apoptosis is caused by downregulation of cFLIP expression in Jurkat T cells

Butyric acid is one of the major extracellular metabolites of periodontopathic Gram-negative bacteria. We previously demonstrated that butyric acid induced apoptosis in human T cells. In the present study, we examined the interaction between butyric acid and TNF-alpha in Jurkat T-cell apoptosis. Simultaneous treatment with TNF-alpha enhanced butyric acid-induced apoptosis by promoting caspase activity more than was achieved by either reagent alone. We examined which genes were associated with the increased susceptibility to TNF-alpha caused by butyric acid, and revealed that expression of cFLIP decreased with increased concentrations of butyric acid. Furthermore, exogenous expression of cFLIP protein suppressed the enhancing effect by TNF-alpha in the apoptosis. These results suggest that butyric acid downregulates cFLIP expression and increases the susceptibility to TNF-alpha by activating caspases via the death receptor signal.

T cells are able to promote lipopolysaccharide-induced bone resorption in mice in the absence of B cells

BACKGROUND AND OBJECTIVE

T cells and their cytokines are believed to be key factors in periodontal disease and bone resorption. We previously showed that T cells transferred to nude mice were related to inflammatory bone resorption in vivo. However, it has not been clarified whether T cells can induce bone resorption in the absence of B cells. In this study, we therefore investigated the ability of T cells to induce bone resorption without B cells, using both T cell- and B cell-deficient mice with severe combined immune deficiency (SCID).

MATERIAL AND METHODS

Escherichia coli lipopolysaccharide (LPS) was injected into the gingivae of SCID mice reconstituted by T cells (SCID + T mice). Wild-type C.B-17 mice and SCID mice were used as control animals. Alveolar bone resorption and production of cytokines in the gingivae were then compared histopathologically and immunohistologically.

RESULTS

The degree of bone resorption in SCID + T mice was significantly greater than that in SCID mice but less than that in wild-type mice. The same tendency was found for expression of receptor activator of nuclear factor kappaB ligand. The number of interferon-gamma-positive cells in SCID + T mice was the highest of the three groups. In contrast, interleukin-4-positive cells were detected in wild-type mice but not in SCID + T and SCID mice.

CONCLUSION

The results suggest that T cells are able to promote LPS-induced bone resorption in the absence of B cells. The expressions of cytokines in the presence of B cells are quite different.

Relationship between the presence of periodontopathic bacteria and the expression of chemokine receptor mRNA in inflamed gingival tissues

BACKGROUND AND OBJECTIVE

Periodontal disease is a chronic disease characterized by the interaction between periodontopathic bacteria and the host immune response. The aim of this study was to investigate the correlation between periodontopathic bacteria and host immune cell infiltrates.

MATERIAL AND METHODS

Twenty-two patients with chronic periodontitis were included in this study. Gingival tissues were taken at the periodontal surgery after completion of initial therapy. Three types of periodontopathic bacteria were detected by polymerase chain reaction, and the prevalence of mRNA expression of chemokine receptors was examined by reverse-transcription-polymerase chain reaction in the gingival tissues. The infiltration of T and B cells was determined by an immunohistochemical method.

RESULTS

In the patients, both Porphyromonas gingivalis and Tanerella forsythia were detected, and the mRNA expression of chemokine receptors CXCR1&2, CXCR4, CCR1, CCR2, CCR3 and CCR4 were more prevalent. The mean number of infiltrated B cells was significantly larger than that of T cells in the sites harboring both P. gingivalis and T. forsythia. Similarly, in the sites where P. gingivalis was detected but T. forsythia was not, the mean number of B cells was significantly larger than that of T cells. In the sites with mRNA expression of CCR2 and CCR3, the mean number of B cells was significantly larger.

CONCLUSION

These results suggest that a high proportion of T helper 2-associated chemokine receptor-positive T cells may be associated with the predominance of B cells and may play an important role in the formation of chronic periodontitis in sites where both P. gingivalis and T. forsythia are detected.

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.

Mast cells and lymphocyte subsets in pulps from healthy and carious human teeth

OBJECTIVE

To evaluate the presence of cytolytic T lymphocytes (CD8+), memory T cells (CD45RO+), helper T lymphocytes (CD4+), and mast cells in pulps from healthy and carious human teeth.

STUDY DESIGN

The teeth were separated into groups: I = unerupted; II = partially erupted, without caries; III = erupted, without caries; IV = erupted with shallow dentine caries; and V = teeth with pulp polyps. The immunoperoxidase staining procedure was used to detect CD8, CD45RO, CD4, and tryptase (mast cell marker) antigens. The number of each cell type was obtained by counting the number of cells per mm2.

RESULTS

Mast cells were only present in pulp polyps. Pulps from carious teeth contained more CD4+ and CD8+ cells than from noncarious teeth. There was a significant decrease in the number of lymphocytes in pulp polyps in comparison to the other groups.

CONCLUSIONS

Mast cells probably do not contribute to the early vascular or specific immune responses in the initial dental pulp pathosis, although they may be involved in a chronic phase of pulp inflammation such as pulp polyps. On the other hand, CD4+ and CD8+ T cells participate mainly in initial phenomena of the immune response to incipient caries and seem not to substantially contribute to the response in pulp polyps.

Relative Plaque Removal of Three Toothbrushes in a Nine-Period Crossover Study

BACKGROUND

This study measured the ability of three toothbrushes to remove plaque following three single brushing episodes with each toothbrush.

METHODS

This was a randomized, controlled, examiner-blind, nine-period crossover study conducted in 72 adult subjects over a 3-month period that examined plaque removal with a rechargeable power toothbrush and two manual toothbrushes. During the course of this study, subjects brushed three times with each of the toothbrushes. Plaque was scored before and after brushing using the Rustogi Modification of the Navy Plaque Index.

RESULTS

Average baseline plaque scores were between 0.373 and 0.376 for the three treatment groups. The power toothbrush delivered an adjusted (via analysis of covariance) mean difference between baseline and post-brushing plaque scores of 0.270, whereas the manual toothbrushes delivered adjusted mean differences of 0.211 (control ADA manual toothbrush) and 0.190 (experimental manual toothbrush). The power toothbrush demonstrated a statistically significantly greater reduction in plaque than the ADA reference manual toothbrush (P < 0.001), which in turn had a statistically significantly greater reduction in plaque than the experimental manual toothbrush (P < 0.001). The powered toothbrush group had, on average, 42.4% and 28.2% greater plaque removal scores than the experimental manual toothbrush and ADA reference manual toothbrush groups, respectively. Results for the interproximal and gingival regions also demonstrated statistically significantly (P < 0.001) greater plaque removal for the powered toothbrush relative to the control manual toothbrushes.

CONCLUSION

The powered toothbrush was found to deliver greater plaque removal by 42.4% and 28.2% compared to the control manual toothbrushes.

Etiology and pathogenesis of periodontal diseases

The two most prevalent and most investigated periodontal diseases are dental plaque-induced gingivitis and chronic periodontitis. The last 10 to 15 years have seen the emergence of several important new findings and concepts regarding the etiopathogenesis of periodontal diseases. These findings include the recognition of dental bacterial plaque as a biofilm, identification and characterization of genetic defects that predispose individuals to periodontitis, host-defense mechanisms implicated in periodontal tissue destruction, and the interaction of risk factors with host defenses and bacterial plaque. This article reviews current aspects of the etiology and pathogenesis of periodontal diseases.

Quantification of mast cells in different stages of human periodontal disease

OBJECTIVE AND METHODS

Among the cells involved in immune and inflammatory responses in periodontal disease, mast cells have been shown to be capable of generating a large number of biologically active substances. The present study was undertaken to identify and quantify the presence of mast cells in different stages of human periodontal disease using histochemical (toluidine blue) and immunohistochemical (tryptase-positive mast cells) techniques.

RESULTS

Mast cell densities (cells per mm(2)) were significantly increased in chronic periodontitis/gingivitis lesions compared with clinically healthy gingival tissues (Health) uniquely by immunohistochemical technique. Interestingly, mast cells were distributed specially in close apposition to mononuclear cells.

CONCLUSIONS

In human periodontal disease there is an increase in the number of mast cells that may be participating either in the destructive events or in the defense mechanism of periodontal disease via secretion of cytokines, including perpetuation of the Th2 response, and cellular migration and healing processes.

The potential role of interleukin-17 in the immunopathology of periodontal disease

BACKGROUND

Interleukin-17 (IL-17) is exclusively produced by activated T cells, and this cytokine can induce inflammatory responses, support immune responses (Th1), and stimulate osteoclastic bone resorption in combination with receptor activator of NF-kappaB (RANK) and RANK ligand (RANKL). These biological functions are relevant to the aetiopathogenesis of periodontitis, and thus we sought to investigate whether IL-17 is produced in periodontal lesions and to assess the relationship of gene expression between IL-17 and other cytokines, and to determine the effect of IL-17 on IL-6 production in human gingival fibroblasts (HGF).

MATERIALS AND METHODS

IL-17 was detected and measured in periodontal tissues obtained as biopsy samples during periodontal surgery and in the cell-free culture supernatants cultured ex vivo, by using Western immunoblotting and enzyme-linked immunosorbent assay, respectively. IL-17 and other cytokine gene expression were investigated by the reverse transcription-polymerase chain reaction (RT-PCR) method. The contribution of IL-17 to IL-6 production by HGF was studied.

RESULTS

IL-17 protein was moderately detected in periodontal tissues. In contrast, IL-17 mRNA was expressed only in nine of 23 periodontitis tissue samples by RT-PCR. The IL-17 mRNA-positive samples simultaneously expressed mRNAs encoding interferon (IFN)-gamma, IL-2, RANK, and RANKL, but not IL-4. IL-10 (Th2 cytokine) was detected more frequently in the samples than IFN-gamma and IL-2 (Th1 cytokine). Recombinant human IL-17 induced IL-6 production from HGF in a dose- and time-dependent fashion.

CONCLUSIONS

These results indicate that IL-17 is produced in periodontal lesions, which may be involved in Th1 modulation and enhance inflammatory reactions via gingival fibroblast-derived mediators in periodontal disease. Thus, IL-17, together with other cytokines, has a potential role in the aetiopathogenesis of periodontal disease.

Actinobacillus actinomycetemcomitans-induced periodontal disease in mice: patterns of cytokine, chemokine, and chemokine receptor expression and leukocyte migration

Although the pathogenesis of periodontal disease (PD) is not well known, cytokines, chemotactic factors and inflammatory cells are certainly involved in the disease outcome. Here, we characterized the evolution of the PD induced by Actinobacillus actinomycetemcomitans in mice, showing that oral inoculation of these bacteria leads to the migration of leukocytes to periodontal tissues and marked alveolar bone resorption. We found the expression of pro-inflammatory and Th1-type cytokines including TNF-alpha, IFN-gamma and IL-12 in periodontal tissues after infection with A. actinomycetemcomitans, from the early stages after infection and throughout the course of the disease. Similar kinetics of expression were found for the chemokines CCL5, CCL4, CCL3 and CXCL10 and for the receptors CCR5 and CXCR3, all of them linked to the Th1-type pattern. The expression of the Th2-type mediators IL-10, CCL1 and their receptors CCR4 and CCR8 was detected only after 30 days of infection, determining a time-dependent mixed pattern of polarized immune response. The chemokine expression was correlated with the presence of polymorphonuclear leukocytes, macrophages, CD4 and CD8 lymphocytes, and B cells in the inflammatory infiltrate. Interestingly, during the predominance of the Th1-type response, a sharp increase in the number of inflammatory cells and intense bone loss was seen. By contrast, after the increased expression of Th2-type mediators, the number of inflammatory cells remained constant. Our data demonstrate that mice subjected to oral inoculation of A. actinomycetemcomitans represent a useful model for the study of PD. In addition, our results suggest that expression of cytokines and chemokines can drive the selective recruitment of leukocyte subsets to periodontal tissues, which could determine the stable or progressive nature of the lesion.

Immunohistochemical analysis of soft tissues in implants with healthy and peri-implantitis condition, and aggressive periodontitis

Today, implant-supported prostheses are widely accepted as a reliable treatment modality, but failures in longitudinal studies have been shown. In some cases, peri-implantitis with a progressive periodontal bone loss takes place, and mechanical or load factors and biological or plaque-induced lesions have been claimed as main etiologic factors. We compared five cases of peri-implantitis, with five cases of healthy peri-implant tissues and five cases of aggressive periodontitis in order to give new findings on the osseointegration loss process. Biopsy specimens from the peri-implant tissues including oral (O), sulcular, and junctional epithelium and the underlying and supracrestal connective tissue, were taken in all cases for histological and immunohistochemical analysis. T lymphocytes were the most prominent cell in the peri-implantitis (PG) and aggressive periodontitis (AG) groups, but not in the peri-implant healthy group (HG). CD1a-positive cells (Langerhans and immature dendritic cells) were observed more frequently in the O than in the sulcular-junctional (S-J) epithelium: they were located in the basal and parabasal layers, without any differences between the three groups. Vascular proliferation analysed by immunoreactivity for CD34, Factor VIII, and vascular endothelial growth factor was more prominent in the PG comparing with HG and AG in the S-J area. Apoptosis, analysed by bcl2 and p53 immunoreactivity, was similar in the three groups. In conclusion, we suggest that the osseointegration loss process is due to an inflammatory process similar to that observed in aggressive periodontitis according to the number of T lymphocytes, but not to the vascular proliferation.

Quantitative assessment of apoptotic and proliferative gingival keratinocytes in oral and sulcular epithelium in patients with gingivitis and periodontitis

BACKGROUND

Periodontal disease is caused by a chronic infection inducing an inflammatory reaction that leads to a breakdown of tooth-supporting tissue. The maintenance of an equilibrium between the host defence and microorganisms in the sulcus is essential to preserve health. All multicellular organisms have mechanisms for killing their own cells, and use physiological cell death for defence, development, homeostasis and ageing. Apoptosis and proliferation are very important phenomena in regulating this and a disturbance is often associated with disease e.g. cancer, AIDS, Alzheimer's disease, rheumatoid arthritis.

OBJECTIVE

The aim of this study was to determine whether the number of apoptotic and proliferative gingival keratinocytes differed between patients with gingivitis and those with periodontitis.

MATERIAL AND METHODS

The distribution of neutrophil elastase, PCNA/cyclin, DNA fragmentation (apoptosis) and p53 was determined with immunocytochemical techniques. We used paraffin-embedded sections from gingival biopsies and did quantitative analyses.

RESULTS AND CONCLUSION

These showed that 5-12% of the keratinocytes in the basal layers of the epithelium proliferated in the two groups. Fewer apoptotic cells were seen in the oral epithelium than in the sulcus in all subjects in both groups. Only in the most apical part of the sulcus, close to the junctional epithelium, did the number of apoptotic keratinocytes exceed the proliferative ones in patients with periodontitis.

Antigen-presenting cells in human periodontal disease tissues

T cells are present in the inflammatory infiltrates of periodontal disease lesions and require antigen presentation by antigen-presenting cells (APCs). While it is still not known whether Th1 or Th2 cells predominate in these lesions, it has been reported that different APCs may induce activation of different T-cell subsets. An immunoperoxidase technique was used to investigate the presence of CD1a+, CMRF-44+, CMRF-58+ and CD83+ dendritic cells, CD14+ macrophages or dendritic cell precursors and CD19+ B cells in gingival biopsies from 21 healthy or gingivitis and 25 periodontitis subjects. The samples were divided into three groups according to the size of infiltrate (group 1, small infiltrates; group 2, medium infiltrates; group 3, extensive infiltrates). The presence of numerous CD1a+ Langerhans cells was noted in the epithelium with no differences between the healthy/gingivitis and periodontitis groups. The percentage of CD83+ dendritic cells in the infiltrates was higher than the percentage of CD1a+, CMRF-44+ or CMRF-58+ dendritic cells. Endothelial cells positive for CD83 were found predominantly in areas adjacent to infiltrating cells, CD83+ dendritic cells being noted in the region of CD83+ endothelium. The percentage of CD14+ cells in the inflammatory infiltrates was similar to that of CD83+ dendritic cells. B cells were the predominant APC in group 2 and 3 tissues. The percentage of B cells in group 3 periodontitis lesions was increased in comparison with group 1 periodontitis tissues and also in comparison with group 3 healthy/gingivitis sections. Functional studies are required to determine the roles of different APC subpopulations in periodontal disease.

Oligoclonal accumulations of T-cell clones in gingivitis and periodontitis lesions

Gingivitis and periodontitis have distinct clinical and immunopathological characteristics. We have previously demonstrated that T cells infiltrating periodontitis lesions recognize a restricted repertoire of antigens or antigenic epitopes. However, the clonality of T cells in the gingivitis lesion is not known. Therefore, we carried out a clonal analysis of T cells infiltrating gingivitis lesions using combined reverse transcription-polymerase chain reaction and single-strand conformation polymorphism (SSCP) analysis. As with periodontitis lesions, SSCP analysis demonstrated the emergence of a number of distinct bands suggesting clonal accumulation in the gingivitis lesion. Although the mean number of distinct bands in gingival tissue was significantly higher than that in peripheral blood mononuclear cells, numerical analysis clearly demonstrated that there was no difference in the total number of bands in gingival tissue specimens between the different disease types. Although there were slight variations in the number of distinct bands in each Vbeta family, there was no significant difference between gingivitis lesions and periodontitis lesions. These results demonstrate that antigen-specific T-cell responses also take place in gingivitis lesions. It remains to be determined, however, what role these antigen-specific T cells play and what antigens the T cells recognize in the pathogenesis of periodontal disease.

Some effects of non-surgical therapy on gingival inflammatory cell subsets in patients with early-onset periodontitis associated with Actinobacillus actinomycetemcomitans

BACKGROUND

Limited information is available as to whether local cellular immunity in early-onset periodontitis (EOP) subjects harboring Actinobacillus actinomycetemcomitans (Aa) differs from that in patients without Aa. In addition, the effect of scaling and root planing on various lymphocyte subsets is described rather sparsely.

METHODS

In 10 subjects with early-onset periodontitis harboring Aa (EOP-Aa) and in 10 subjects without Aa (EOP-nonAa), clinical measurements were recorded and gingival biopsies were performed before and after scaling and root planing. The specimens were cut into serial sections; using the alkaline phosphatase-antialkaline phosphatase technique, monoclonal antibodies to CD20 (B cells), CD30 (plasma cells), and CD45RO (T-memory cells) were applied as well as polyclonal antibodies to alpha, gamma, and mu chains (Ig A, G, and M). Cells were counted from an area of 0.25 mm2 in areas showing the largest infiltration.

RESULTS

Before therapy, mean counts of all cell phenotypes were found to be markedly enhanced in the EOP-Aa group compared to EOP-nonAa subjects. Following scaling and root planing, the numbers of all phenotypes decreased in both groups. However, comparing the data before and after therapy in the EOP-Aa group, the P value was <0.05 only for CD30-positive cells. In the EOP-nonAa group, the differences before and after therapy reached statistical significance (P<0.05) for all cell counts, except for IgM-positive cells. Furthermore, reduction of probing depth and gain of clinical attachment reached the 0.05 level of statistical significance only in EOP-nonAa subjects.

CONCLUSIONS

In EOP subjects harboring Aa, inflammatory cell subsets were detected in 2- to 3-fold higher numbers compared to patients without Aa. Scaling and root planing resulted in a decrease of all cell phenotypes studied in individuals without Aa, whereas in subjects with Aa, the only significant decrease that was seen occurred in plasma cells.

Cytokine gene expression in chronic periodontitis

BACKGROUND

Cytokines play an important rôle in controlling inflammatory processes and tissue homeostasis. Periodontitis, as any other chronic inflammatory disease, results from a disarrangement of host factors, mainly cytokines and the initiating agent. Modulation of the cytokines is not only controlled by the host but also by infecting bacteria and their products.

AIM

In the present study, we examined the cytokine mRNA expression profiles in six patients, each presenting sites affected with (1) severe progressive periodontitis, (2) chronic, but stable periodontal lesions, and (3) with healthy sites. Analysis using a quantitative RT-PCR included IFN-gamma, IL-1beta, IL-2, IL-4, IL-5, IL-6, and TNF-alpha.

MATERIAL AND METHODS

6 patients with chronic periodontitis were following treatment observed for a period of six years for local sites staying healthy, local sites with periodontal pathology but without signs of progression of attachment loss and sites with verified progression were biopsied. The biopsies were lyzed and analyzed for levels of cytokine mRNAs.

RESULTS

Results revealed considerable variation not only between patients, but also between individual sites. Each patient's site has thus to be looked at as an independent entity.

CONCLUSIONS

The local action of cytokines, which is heavily dependent on recruitment, interaction and activation of immunocompetent cells can explain the site-specific nature of cytokine expression. Cytokine data from individual sites together with the local clinical status and data from the literature demonstrate the complexity of periodontal disease pathogenesis. To gain insight to specific mechanisms further studies are needed.

Cytokines in periodontal disease: where to from here?

Numerous studies have attempted to elucidate the cytokine networks involved in chronic periodontitis, often with conflicting results. A variety of techniques were used to study cells in situ, cells extracted from gingival tissues, peripheral blood mononuclear cells, purified cell populations, and T cell lines and clones. Bacterial components, including sonicates, killed cells, outer membrane components, and purified antigens, have all been used to stimulate cells in vitro, making comparisons of cytokine profiles difficult. As it is likely that different cells are present at different disease stages, the inability to determine disease activity clinically is a major limitation of all these studies. In the Context of tissue destruction, cytokines such as IL-1, IL-6 and IL-18 are likely to be important, as are their regulating cytokines IL-10 and IL-11. In terms of the nature of the inflammatory infiltrate, two apparently conflicting hypotheses have emerged: one based on direct observations of human lesions, the other based on animal experimentation and the inability to demonstrate IL-4 mRNA in gingival extracts. In the first of these, Th1 responses are responsible for the stable lesion, while in the second Th2 responses are considered protective. Using Porphyromonas gingivalis-specific T cell lines we have shown a tendency for IFN-gamma production rather than IL-4 or IL-10 when antigen is presented with peripheral blood mononuclear cells which may contain dendritic cells. It is likely that the nature of the antigen-presenting cell is fundamental in determining the nature of the cytokine profile, which may in turn open up possibilities for new therapeutic modalities.

Some local and systemic immunological features of prepubertal periodontitis

OBJECTIVES

The aim of the present investigation was to study local (gingival) and systemic host defense characteristics in a sample of children exhibiting local prepubertal periodontitis (LPP).

MATERIAL AND METHODS

2 groups of subjects were included in the present study. One group consisted of 11 children (9.5+/-2.0 years) with signs of periodontal disease (LPP group). A 2nd group comprised 21 adults (48.1+/-5.8 years) with advanced periodontal disease: adult periodontitis (AP) group. Gingival biopsies and a sample of peripheral blood were obtained in each individual of the AP group and in 7 out of the 11 subjects in the LPP group. The biopsies were prepared for morphometrical and immunohistochemical analysis and the blood samples prepared for immunohistochemical analysis.

RESULTS

The cellular infiltrates in the biopsies of the LPP group contained a larger proportion of lymphocytes and, in particular B cells, than was the case in the AP group. The TCR Valpha/Vbeta gene expression in the lesions in the AP group was dominated by Vbeta 17 and in the LPP group by Valpha2. The content in peripheral blood of various lymphocyte sub-populations and TCR Valpha/Vbeta gene expression in the 2 groups was almost similar.

CONCLUSION

It is suggested that (i) the systemic host response in children with prepubertal periodontitis has many features in common with that seen in adult patients but that (II) local defense mechanisms in the periodontitis lesion of LPP differ from those in adult periodontitis.

Some effects of non-surgical therapy on gingival inflammatory cell subsets in patients with adult and early-onset periodontitis

BACKGROUND

Limited information is available to determine if there is a distinction in local cellular immunity between adult and early-onset periodontitis. Furthermore, the effect of scaling and root planing on various lymphocyte subsets is sparsely described.

METHODS

Clinical measurements were recorded and gingival biopsies were performed before and after scaling and root planing in 10 subjects with adult (AP) and in 10 with early-onset periodontitis (EOP). The specimens were cut into serial sections and, using the alkaline phosphatase-anti-alkaline phosphatase technique, monoclonal antibodies to CD20 (B-cells), CD30 (plasma cells), and CD45RO (T-memory cells) were applied, as well as polyclonal antibodies to alpha, gamma, and mu chains (Ig A, G, and M). Areas showing the largest infiltration cells were counted.

RESULTS

Mean counts of all cell phenotypes in the AP versus the EOP group did not show any significant differences before therapy (P >0.05). Following scaling and root planing, numbers of all phenotypes decreased in both groups. Comparing the data before and after therapy, P values were >0.05 in the AP group, except for IgA-positive cells. In the EOP group, the differences before and after therapy reached statistical significance (P<0.05) for all cell counts, except for IgM-positive cells. Furthermore, reduction of probing depth and gain of clinical attachment reached the 0.05 level of statistical significance only in EOP subjects.

CONCLUSIONS

Local cellular immunity in patients with adult onset periodontitis does not appear to differ from the immune response in patients with early onset periodontitis. Scaling and root planing causes a decrease in the inflammatory cells subsets tested, however, this decline seems to be more pronounced in EOP than in AP subjects.

Antigenic specificity of gingival crevicular fluid antibody to Actinobacillus actinomycetemcomitans

Elevated antibody levels to periodontopathogens in GCF have been identified and used as support for local antibody synthesis in periodontitis. This study examined both cross-sectional and longitudinal GCF samples for the antigenic specificity of antibody in the fluid. GCF samples were collected from each tooth of 27 periodontitis patients infected with A. actinomycetemcomitans. Levels of IgG antibody in the GCF were assessed by means of an ELISA and compared with serum for determination of local elevations. A proportion of those GCF samples that exhibited significantly elevated antibody were examined by Western immunoblotting to outer membrane antigens from A. actinomycetemcomitans. Homologous sera were also examined for comparison of antibody specificities. Of the sites with elevated IgG antibody, 87% were colonized by A. actinomycetemcomitans; however, 46% of sites with A. actinomycetemcomitans infection did not have elevated antibody. Cross-sectional studies identified a 78 to 100% agreement between the antibody specificities in GCF and those in serum. Additionally, patterns of antibody reactivity in both GCF and serum in the subjects were often very distinctive. Longitudinal alterations in GCF antibody were examined in 15 patients through a monitoring interval of up to 2 years and showed a general conservation of specificities. However, 7/15 patients exhibited a definite acquisition of different antibody specificities during the monitoring. These results describe a relationship between elevated local antibody and A. actinomycetemcomitans infection. Furthermore, the antibody specificities in serum appear to reflect generally the local response to this pathogen.

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.

Comparison of gingival and peripheral blood T cells among patients with periodontitis suggests skewing of the gingival T cell antigen receptor V beta repertoire

The present study investigated the expression of different variable regions of T cell receptor beta-chain (V beta) among functional subsets of T cells, i.e. CD45RO+ (activated/memory), CD4+ and CD8+ in gingiva and peripheral blood of patients with periodontitis. Gingival tissue specimens (n = 25) and peripheral blood were procured from 18 patients with periodontitis during periodontal surgery or extraction. Single-cell suspensions of gingival tissues were made by enzymatic digestion. These cells were immunofluorescently labeled with a panel of monoclonal antibodies specific for 18 TCR V beta regions, in concert with markers for various T cell subsets. The cells were then analyzed with 3-color multivariate flow cytometry. Results demonstrated that a significantly higher proportion of T cells in gingiva expressed V beta 5.2 (0.0005), V beta 6 (0.0007) and V beta 9 (0.003) regions compared to those in peripheral blood. Comparison of CD45RO+ (activated/memory) and CD45RO- (naïve) subsets of gingival T cells revealed differences in the expression of TCR V beta regions. V beta 5.2 expression was significantly higher among CD45RO+ gingival T cells (p = 0.004), whereas V beta 14 expression was elevated among the CD45RO- subset relative to peripheral blood (p = 0.008). Analysis of TCR V beta region expression among CD4+ and CD8+ subsets did not reveal any statistically significant differences between gingiva and peripheral blood, although some V beta regions approached significance. Collectively, these results demonstrate that the T cell repertoire in the gingival compartment differs significantly from that in the peripheral blood. Furthermore, since the skewing of TCR V beta was observed among naïve, as well as activated/memory T cells, it is likely that both developmental and environmental factors are influential in shaping the gingival TCR repertoire in patients with periodontitis. Elucidation of the cause of the skewed expression of T cell receptors in gingiva can provide insights into the specificity of T cells in periodontitis.