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.     

Mast Cells in Periodontal Disease of Individuals With and Without HIV Undergoing Highly Active Antiretroviral Therapy

Background: Mast cells appear to be associated with human periodontal disease. However, to the best of our knowledge, no studies have evaluated the presence of mast cells in individuals with human immunodeficiency virus (HIV) undergoing highly active antiretroviral therapy (HAART). Methods: Gingival samples were obtained from 50 individuals with and without HIV who presented with chronic gingivitis and periodontitis. Immunohistochemical staining was performed to identify c‐kit and tryptase mast cells. Inflammatory infiltrate was evaluated and quantified in the specimens of gingival tissue. In the inflammatory infiltrate subjacent to the pocket epithelium, the densities of the mast cells were calculated. These results were compared between the groups with and without HIV. Correlations could be drawn between the densities of c‐kit and tryptase mast cells and the density of inflammatory infiltrate, cluster of differentiation 4 (CD4)‐positive and CD8⁺ T‐lymphocyte levels, and viral loads. Results: Although the individuals with HIV had higher densities of c‐kit or tryptase mast cells than those without HIV, both groups presented with chronic gingivitis or periodontitis, and no statistically significant differences could be observed. Both strong and negative correlations could be observed among the inflammatory infiltrate, c‐kit, and tryptase in individuals both with and without HIV. Concerning the chronic gingivitis of the individuals with HIV, both strong and positive correlations could be observed between the density of c‐kit and CD8⁺ T‐lymphocyte levels. Conclusions: Individuals with HIV undergoing HAART, compared with individuals without HIV, had no statistically significant differences in mast cell densities in gingival tissue.     

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.     

Correlation of cytomegalovirus and human herpesvirus 7 with CD3+ and CD3+ CD4+ cells in chronic periodontitis patients

Thomasini RL, Bonon SH, Durante P, Costa SCB. Correlation of cytomegalovirus and human herpesvirus 7 with CD3 ⁺ and CD3 ⁺ CD4 ⁺ cells in chronic periodontitis patients. J Periodont Res 2012; 47: 114–120. © 2011 John Wiley & Sons A/S Background and Objective: Human chronic periodontitis is an inflammatory process characterized by dense accumulation of immune cells in the periodontal tissue. The periodontitis can lead to loss of teeth in the patient and the pathogenesis of this disease is not completely known. This study tested the hypothesis that chronic periodontitis‐affected sites can harbor betaherpesviruses and that viruses are linked to a profile of the inflammatory infiltrate. Material and Methods: Biopsies of periodontal tissue were taken from periodontitis‐affected patients and from healthy subjects. Immunohistochemistry was performed to count CD19⁺ B cells, CD3⁺ total T cells, T‐CD4⁺ and T‐CD8⁺ cell subsets, and PCR was performed to detect cytomegalovirus and human herpesvirus 6 and 7 in the samples. One slide of each sample was stained with Giemsa for histopathological examination and to evaluate the quality of the cellular infiltrate. Results: As expected, tissues collected from healthy subjects presented no significant level of inflammatory infiltration and were therefore excluded from immunostaining procedures. Results showed that CD19⁺ B cells were in higher number than CD3⁺ T cells in the periodontitis‐affected tissue, but this was not statistically significant. The T‐CD4⁺ lymphocyte subset was significantly higher than the T‐CD8⁺ lymphocyte subset (p = 0.004) in the samples. Cytomegalovirus and human herpesvirus 7 were found at periodontitis‐affected sites, but not in tissue collected from healthy subjects (p = 0.04 and p = 0.04, respectively). Human herpesvirus 6 was rarely detected. We found a correlation between cytomegalovirus and lower CD19⁺/CD3⁺ ratios (ratio < 0.9, p = 0.003) and between human herpesvirus 7 and lower CD19⁺/CD3⁺ ratios (ratio < 0.9, p = 0.003) and higher CD4⁺/CD8⁺ ratios (ratio > 1.1, p = 0.002). Conclusion: This study shows that cytomegalovirus and human herpesvirus 7 can be present at periodontitis‐affected sites but are uncommon at healthy periodontal sites. Moreover, our data suggest that cytomegalovirus can be related to an inflammatory infiltrate with predominance of CD3⁺ T cells, whereas human herpesvirus 7 can be associated with an infiltrate with predominance of T‐CD4⁺ cells. However, further studies are necessary to support this hypothesis. Herpesviruses could play a role in human chronic periodontitis by modulation of the T cell response.     

Presence of Porphyromonas gingivalis and plasma cell dominance in gingival tissues with periodontitis

Oral Diseases (2010) 16 , 375–381 Objective: Porphyromonas gingivalis can invade and survive within its host epithelial cells. The aim of this study was to test our hypothesis that persistent presence of intracellular periodontal pathogens in gingival tissue causes the chronic inflammation and that an inappropriate immune response is a risk factor for periodontitis. Methods: Together with the presence of P. gingivalis, the distribution of B cells, plasma cells, and CD4⁺, CD8⁺, and FOXP3⁺ regulatory T cells was evaluated in gingival tissues from healthy (n = 7) and periodontitis (n = 8) sites by in situ hybridization and immunohistochemistry, respectively. Results: Porphyromonas gingivalis was detected in proximity to inflammatory infiltrates in three and seven biopsies from the healthy and periodontitis sites, respectively. Compared with healthy sites, periodontal lesions contained a significantly increased number of each immune cell studied with a relative dominance of plasma cells over T cells. Conclusions: Persistent bacterial invasion of gingival tissues in combination with a plasma cell‐dominant immune response may be involved in the pathogenesis of periodontitis.     

Production of interleukin‐8 in vitro by mononuclear cells isolated from human periapical lesions

Introduction: Interleukin‐8 (IL‐8) is an important mediator of inflammation. However, little is known about its production in chronic dental periapical lesions and this was the main aim of this work. Methods: Inflammatory cells were isolated from clinically different periapical lesions and analyzed by morphological criteria. The mononuclear cells were isolated, phenotypically analyzed by immunocytochemistry and cultivated in vitro. IL‐8 was measured in culture supernatants of these periapical lesion mononuclear cells (PL‐MNC) using a microbeads fluorescence assay. Results: We found a relatively high production of IL‐8 in 19 out of 21 periapical lesions included in the study. The level of IL‐8 and the proportion of neutrophil granulocytes were significantly higher in the group of symptomatic lesions, compared to the asymptomatic lesions, but there was no statistically significant correlation between these parameters. According to the predominance of CD3⁺ T cells and Ig⁺/CD19⁺ B cells and plasma cells, lesions were divided into T‐type and B‐type lesions, respectively. The levels of IL‐8 were significantly higher in the culture supernatants of PL‐MNC in the T‐type lesions and were positively correlated with the proportion of macrophages/dendritic cells (CD11c⁺ cells) and CD4⁺ T cells. Such a correlation was not shown in B‐type lesions. Conclusion: These results suggest that PL‐MNC are a significant source of IL‐8, which is probably an important chemokine for the migration and function of different cell types at the site of chronic inflammation.     

Relationship Between Chemokines and Dendritic Cells in Human Chronic Periodontitis

Background: The purpose of this study was to evaluate the relationship between chemokines and dendritic cells (DCs) in human chronic periodontitis (CP). Methods: Gingival samples were obtained from 23 individuals with CP, and six samples of normal mucosa (NM) overlapping the third molar were used to control for the chemokine levels. Periodontal examination was conducted. Immunohistochemistry was performed for Factor XIIIa⁺ and cluster of differentiation (CD)1a⁺ immature DCs and CD83⁺ mature DCs. Levels of the CC chemokine ligand (CCL)2, CCL3, CCL5, CCL19, CCL20, and CXC chemokine ligand (CXCL)8 were measured in gingival tissues using enzyme‐linked immunosorbent assay. Inflammatory infiltrate, DCs, chemokines, classification of human CP, and clinical parameters were correlated and compared. Results: The expression of CCL2 and CCL20 was positively correlated with increased densities of CD1a⁺ DCs. CCL3 and CXCL8 were positively related to the clinical attachment level. CCL3, CCL5, CCL19, and CXCL8 levels increased in the gingival samples of patients with CP compared with NM, whereas CCL20 levels increased in advanced CP compared with mild–moderate CP. Conclusions: More CD1a⁺ immature DCs are related to CCL2 and CCL20. CCL3 and CXCL8 chemokines are related to a greater severity of human CP.     

Interstitial and Langerhans' dendritic cells in chronic periodontitis and gingivitis

The aim of the present study was to compare quantitatively the distribution of dendritic cell subpopulations in chronic periodontitis and gingivitis. Fourteen biopsies from patients with chronic periodontitis and fifteen from patients with gingivitis were studied. An immunoperoxidase technique was used to quantify the number of Langerhans' cells (CD1a) and interstitial dendritic cells (factor XIIIa) in the oral and sulcular and junctional/pocket epithelia and in the lamina propria. A greater number of factor XIIIa+ dendritic cells in the lamina propria and CD1a+ dendritic cells in the oral epithelium were observed in gingivitis compared to the periodontitis group (p = 0.05). In the sulcular and junctional/pocket epithelia and in the lamina propria, the number of CD1a+ dendritic cells was similar in the gingivitis and periodontitis groups. In conclusion, the number of Langerhans' cells in the oral epithelium and interstitial dendritic cells in the lamina propria is increased in gingivitis compared to periodontitis, which may contribute to the different pattern of host response in these diseases.     

CD29 expression on CD4+ gingival lymphocytes supports migration of activated memory T lymphocytes to diseased periodontal tissue

The cell surface phenotypes of CD4⁺ cells extracted from inflammatory periodontal disease tissues were analyzed using two- and three-color immunofluorescence and flow cytometry. Cells extracted from both adult periodontal and localized juvenile periodontitis lesions showed a depressed CD4/CD8 ratio (1.0±0.1 adult periodontitis and 1.1 ±0.1 localized juvenile periodontitis) compared with cells recovered from normal/marginal gingivitis tissue (1.8 ±0.2) or with normal peripheral blood cells (2.1 ±0.1) or periodontal disease blood cells (2.1±0.1 and 1.7±0.1 for adult periodontitis and juvenile periodontitis, respectively). The monoclonal antibodies anti-2H4 and anti-4B4 were used to identify the CD45RA and CD29 antigens respectively on CD4⁺ T cells from the periodontal disease lesions. In peripheral blood, CD29⁺ cells accounted for 66–77% of the CD4⁺ population, and CD45RA⁺ cells accounted for 22–27% of the CD4⁺ subset. No differences in expression were found between peripheral blood lymphocytes from normal subjects and from periodontal disease patients. Two-color analyses of lymphocytes from periodontal diseased tissues showed that 87–89% of the CD4⁺ population were CD29⁺ and that 70–79% of the CD4⁺ cells were CD45RA⁺. Normal tissues contained significantly fewer CD4⁺CD29⁺ cells (56±4%) and CD4⁺CD45RA⁺ cells (40±4%) on average, and few, if any double-labelled cells could be accounted for. These data implied that a significant percentage of the CD4⁺ cells from the diseased tissues were both CD29⁺ and CD45RA⁺ and that these populations are found in quite different proportions in diseased periodontal tissue than in peripheral blood or nondiseased tissue. In further analyses using three-color cytometry the mean percentage of CD4⁺CD29⁺CD45RA⁺ lymphocytes extracted from periodontal disease lesions was 43±9% of the CD4⁺ population. These results suggest that CD4⁺ T lymphocytes in periodontal disease not only demonstrate varying levels of maturity but also that the accumulation of CD4⁺ T cells within the periodontal tissues maybe a result of increased adhesion and transendothelial migration.     

Aggressive and Chronic Periodontitis Correlate With Distinct Cellular Sources of Key Immunoregulatory Cytokines

Background: Chronic periodontitis (CP) and aggressive periodontitis (AP) are inflammatory diseases and the main cause of dental loss in adults. We aimed to investigate the expression of adhesion molecules and the source of proinflammatory and anti‐inflammatory cytokines in circulating mononuclear cells from patients with CP and AP. Methods: Peripheral blood mononuclear cells from healthy controls and CP or AP patients were collected. The expression of the cell adhesion molecules CD11a and CD11b, and the cellular sources of interleukin (IL)‐4, IL‐10, IL‐12, interferon‐γ, and tumor necrosis factor‐α by distinct subpopulations of circulating leukocytes were determined using flow cytometry. Results: The expression of CD11a, but not CD11b, was significantly higher within the CD4⁺ and CD8⁺ T cells in CP and AP than in healthy controls. The frequencies of tumor necrosis factor‐α–expressing CD4⁺ T cells and CD14⁺ cells were higher in AP and CP, compared to healthy controls, respectively. Moreover, the frequency of IL‐10 expressing CD14⁺ cells was higher in CP, but not AP, compared to healthy controls CD4⁺ T cells committed to IL‐4 production was higher in CP than in healthy controls. Conclusion: These results suggest the participation of CD11a in the pathogenesis of periodontal lesions and show distinct cellular sources of immunoregulatory cytokines in AP versus CP.     

High Levels of CXC Ligand 12/Stromal Cell–derived Factor 1 in Apical Lesions of Endodontic Origin Associated with Mast Cell Infiltration

Introduction

CXC ligand 12/stromal-derived factor-1 (CXCL12/SDF-1) is a pleiotropic chemokine that regulates the influx of a wide range of leukocytes. The aim of this study was to characterize CXCL12/SDF-1 in apical lesions (ALs) of endodontic origin, with special emphasis in associated immune cell populations.

Methods

In this case-control study, 29 individuals with chronic apical periodontitis and 21 healthy volunteers were enrolled. ALs and healthy periodontal ligament samples were obtained for tissue homogenization, immune Western blotting, and enzyme-linked immunosorbent assay to determine CXCL12/SDF-1 forms and levels. Anatomopathologic diagnosis, immunostaining for CXCL12/SDF-1, CD117-CXCL12/SDF-1, and toluidine blue were also performed to identify tissue and cell localization. Finally, a set of tissue samples were digested and analyzed by flow cytometry to identify CXCL12/SDF-1 in different immune cell populations. Data were analyzed with Stata v11 and WinDi 2.9 software, and significance was considered if P < .05.

Results

CXCL12/SDF-1 was predominantly identified as monomers; levels of CXCL12/SDF-1 were significantly higher in ALs compared with controls, and it was primarily localized to inflammatory infiltrates. Expression of CXCL12/SDF-1 was colocalized to mast cells in tissue sections. Furthermore, CD117⁺ mast cells were the second most frequent infiltrating cells and the main CXCL12/SDF-1 expressing cells, followed by CD4⁺ lymphocytes, monocytes/macrophages, neutrophils, and dendritic cells.

Conclusions

ALs of endodontic origin demonstrated higher levels of CXCL12/SDF-1 compared with controls. CXCL12/SDF-1 was identified in immune cell populations, whereas mast cells represented the major CXCL12/SDF-1 expressing cells, suggesting that this chemokine might play a central role in apical tissue destruction, most probably inducing persistent recruitment of immune cells, particularly of mast cells.     

Role of Smoking and Type 2 Diabetes in the Immunobalance of Advanced Chronic Periodontitis

Background : This study evaluates the tissue levels of interleukin (IL)‐17⁺, IL‐15⁺, Foxp3⁺ cells, fibrosis, and plasma B‐cell infiltration in sites with chronic periodontitis in smokers and subjects with type 2 diabetes. Methods: Gingival biopsies were harvested from the following groups: systemically and periodontally healthy subjects (healthy group, n = 10); non‐smokers and subjects with advanced periodontitis and without diabetes (non‐risk factor/periodontitis group, n = 10); heavy smokers with advanced periodontitis and without diabetes (smoking/periodontitis group, ≥20 cigarettes per day for at least the past 5 years, n = 10); and non‐smoking poorly controlled subjects with diabetes (glycated hemoglobin levels ≥9%) with advanced periodontitis (diabetes mellitus/periodontitis group [DMP], n = 10). The number of IL‐17⁺, IL‐15⁺, and Foxp3⁺ cells was analyzed by immunohistochemistry, whereas the amount of fibrosis and plasma B‐cell infiltration in gingival tissue was analyzed by histomorphometry. Results: The number of Foxp3⁺ cells was significantly higher in the periodontitis groups compared to the healthy group (P <0.05). The DMP group presented higher levels of Foxp3⁺ cells than other periodontitis groups (P <0.05). The levels of IL‐15⁺ and IL‐17⁺ cells and the amount of fibrosis were higher in the DMP group than in the other groups (P <0.05). There was a trend for a decreased B‐cell infiltration in the DMP group (P >0.05). There was a slightly significant negative correlation between B‐cell infiltration and the amount of fibrosis (P <0.05). Conclusion: Upregulation of IL‐17⁺, IL‐15⁺, and Foxp3⁺ cells and increased amounts of fibrosis were observed in chronic periodontitis sites in subjects with type 2 diabetes, suggesting that periodontitis development in these subjects may be influenced by the T helper 17/T regulatory axis.     

Follicular dendritic cells confirm lymphoid organization in the minor salivary glands of primary Sjögren’s syndrome

Background: Sjögren’s syndrome (SS) is an autoimmune chronic inflammatory disorder affecting the salivary and lacrimal glands. The aim of this study was to explore immunophenotypic features of chronic inflammatory reactions in the minor salivary glands in patients with primary SS (pSS). Methods: Formalin‐fixed, paraffin‐embedded labial minor salivary gland tissue sections from randomly selected patients with pSS (n = 60) were investigated for the expression of CD21, CD23, CD35 and IgD by immunohistochemistry. Results: Based on the distribution and staining pattern of CD21, CD23, CD35 and IgD in lymphoid aggregates, several stages of chronic inflammatory reactions were observed. In 12/60 (20%) patients, lymphoid infiltrates with germinal centre (GC)‐like features such as extensive networks of CD21‐, CD23‐ and CD35‐positive cells were observed in the minor salivary gland tissue. Smaller networks and /or focal infiltrates with scattered CD21⁺, CD23⁺ and CD35⁺ cells were observed in the remaining 48/60 (80 %) cases. When dividing patients according to the presence (GC+) or the absence (GC?) of GC in the minor salivary glands, the mean focus score was significantly higher in the GC+ patients (P < 0.05). Double staining of the minor salivary glands revealed focal infiltrates with follicular dentritic cell networks and B cells resembling normal GCs in tonsillar tissue. Conclusion: A particular cellular profile was demonstrated in a sub‐group of patients with pSS and could be linked to serological aberrations. These findings warrant further prospective studies.     

Expression of TET2 enzyme indicates enhanced epigenetic modification of cells in periodontitis

DNA methylation is an important epigenetic mechanism involved in the regulation of gene expression, and a reduction in DNA methylation influences cell‐cycle progression and cell differentiation in inflammatory cells. The aim of the present study was to analyze the DNA‐methylation pattern at local and global/systemic levels in patients with periodontitis and gingivitis. Twenty‐one subjects with generalized, severe periodontitis and 17 subjects with gingival inflammation but no attachment loss were recruited. Gingival biopsies and peripheral blood samples were collected and prepared for immunohistochemical analysis of 5‐methylcytosine (5mC), 5‐hydroxymethylcytosine (5hmC), ten‐eleven translocation 2 (TET2), and DNA methyltransferase 1 (DNMT1). Whilst a similar pattern for 5mC and 5hmC DNA methylation was found in both types of lesions, a significantly larger proportion of TET2‐positive cells was found in periodontitis lesions than in gingivitis lesions. Quantitative real‐time PCR analysis showed no differences between gingivitis and periodontitis lesions regarding expression of TET2 and isocitrate dehydrogenase (IDH) genes, while the global level of 5hmC was significantly higher in blood than in tissue in patients with periodontitis. It is suggested that epigenetic changes are more common in periodontitis lesions than in gingivitis lesions and that such changes are tissue specific.     

Immunohistological analysis of Tannerella forsythia‐induced lesions in a murine model

Tannerella forsythia has been implicated as a defined periodontal pathogen. In the present study a mouse model was used to determine the phenotype of leukocytes in the lesions induced by subcutaneous injections of either live (group A) or nonviable (group B) T. forsythia. Control mice (group C) received the vehicle only. Lesions were excised at days 1, 2, 4, and 7. An avidin‐biotin immunoperoxidase method was used to stain infiltrating CD4⁺ and CD8⁺ T cells, CD14⁺ macrophages, CD19⁺ B cells, and neutrophils. Hematoxylin and eosin sections demonstrated lesions with central necrotic cores surrounded by neutrophils, macrophages and lymphocytes in both group A and group B mice. Lesions from control mice exhibited no or only occasional solitary leukocytes. In both groups A and B, neutrophils were the dominant leukocyte in the lesion 1 day after injection, the numbers decreasing over the 7‐day experimental period. There was a relatively low mean percent of CD4⁺ and CD8⁺ T cells in the lesions and, whereas the percent of CD8⁺ T cells remained constant, there was a significant increase in the percent of CD4⁺ T cells at day 7. This increase was more evident in group A mice. The mean percent of CD14⁺ macrophages and CD19⁺ B cells remained low over the experimental period, although there was a significantly higher mean percent of CD19⁺ B cells at day 1. In conclusion, the results showed that immunization of mice with live T. forsythia induced a stronger immune response than nonviable organisms. The inflammatory response presented as a nonspecific immune response with evidence of an adaptive (T‐cell) response by day 7. Unlike Porphyromonas gingivalis, there was no inhibition of neutrophil migration.     

Porphyromonas gingivalis antigen preferentially stimulates T cells to express IL‐17 but not receptor activator of NF‐κB ligand in vitro

Although T cells have been implicated in the pathogenesis and are considered to be central to both their progression and control of chronic inflammatory periodontal diseases, the precise contribution of T cells to tissue destruction has not been fully clarified. Recently, interleukin (IL)‐17 and receptor activator of Nuclear factor κB NF‐κB ligand (RANKL) have received much attention as a result of their proinflammatory and bone metabolic roles, respectively. We therefore investigated the effect of outer membrane protein (OMP) from Porphyromonas gingivalis (P. gingivalis) on the expression of IL‐17 and RANKL in peripheral blood mononuclear cells (PBMCs) and compared these between gingivitis and periodontitis, which are representative of stable and progressive lesions, respectively. The in situ expression of these molecules was also examined. P. gingivalis OMP stimulated PBMCs to express IL‐17 at both the mRNA and protein level. Although the mean expression of mRNA was not different between the two groups, the mean level of IL‐17 in the culture supernatants was higher in gingivitis patients than in periodontitis patients. However, the frequency of IL‐17‐positive samples was higher in the periodontitis patients. This stimulatory effect was not evident for RANKL expression in either periodontitis or gingivitis patients. In gingival tissue samples, IL‐17 mRNA was detected in gingivitis more frequently than in periodontitis. The expression of RANKL mRNA was much lower than that of IL‐17 in terms of both level and frequency. These results suggest that IL‐17 but not RANKL may be involved in the pathogenesis of periodontal diseases. However, there may be negative regulatory mechanisms for IL‐17 in gingivitis.     

The changes in T lymphocyte subsets following periodontal treatment in patients with chronic periodontitis

Objective: The aim of this study was to determine whether there was any change in T‐lymphocyte subsets in patients with chronic periodontitis after applying different periodontal treatment methods. Patients and methods: Twenty‐four patients with chronic periodontitis were included in the study. In every phase of the treatment (pretreatment, initial treatment, curettage and flap operations) the biopsy samples were taken from the gingival tissues at sites of chronic periodontitis. Then CD4⁺ and CD8⁺ lymphocyte and CD4⁺/CD8⁺ ratio values were determined using flow cytometry in the biopsy samples. At the same time, gingival pocket depth, Löe–Silness gingival index, and Silness–Löe plaque index scores were recorded to assess the periodontal status in patients. To determine the correlation between the clinical measurements and the laboratory results obtained before the treatment, after initial treatment, after curettage and after flap operations, we conducted an analysis using a paired t‐test. Results: Flow cytometry findings in the patients with chronic periodontitis showed that CD4⁺ and CD8⁺ lymphocyte values before treatment were under the normal value and the CD4⁺/CD8⁺ ratio was within the normal distribution interval. The CD4⁺/CD8⁺ ratio decreased postcurettage and postflap operation. This decrease was statistically significant (p < 0.001). The CD4⁺ and CD8⁺ lymphocyte values were increased postcurettage and postflap operation. This increase was also statistically significant (p < 0.001). Conclusions: These findings suggest that local immune response was poor in the patients with chronic periodontitis. CD4⁺ and CD8⁺ T‐lymphocytes could play a significant role in chronic periodontitis pathobiology.