Immunohistological analysis of T cell functional subsets in chronic inflammatory periodontal disease

IL4 gene VNTR polymorphism in chronic periodontitis in end-stage renal disease patients

OBJECTIVE

Interleukin-4 gene polymorphisms were found to be associated with periodontitis. The purpose of this case-control study was to evaluate association of IL4 VNTR polymorphism with periodontitis in patients with end-stage renal disease (ESRD).

SUBJECTS AND METHODS

We examined 180 ESRD patients with chronic periodontitis, 82 without CP and 180 healthy controls. Genomic DNA from all subjects was genotyped for the IL4 VNTR polymorphism by polymerase chain reaction (PCR).

RESULTS

Genotype distribution in all groups followed Hardy-Weinberg equilibrium. Significant differences in genotype and allele frequencies were observed between groups. The patient group had higher frequency of P1 allele than controls, with odds ratio for P1 allele 1.6 (95% CI 1.1-2.3) and P1P1 genotype 2.73 (95% CI 1.06-7.5). There were no differences in polymorphism distribution between ESRD patients without CP and controls. Periodontal disease was more severe in older patients (≥50 years). Similarly, patients with T2DM had more severe manifestation of CP than patients without diabetes (p = 0.01 for plaque index, p = 0.004 for bleeding index and p = 0.03 for gingival index).

CONCLUSION

Our findings suggest that VNTR polymorphism in IL4 gene might be a risk factor for chronic periodontitis in patients with ESRD.

Regulatory T-cells Infiltrate Periodontal Disease Tissues

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

Evaluation of mRNA expression of the transcription factors of Th1 and Th2 subsets (T-bet and GATA-3) in periodontal health and disease - A pilot study in south Indian population

Background:

Based on their respective pro- or anti-inflammatory cytokine profiles, the Th1/Th2 paradigm explains pathogenic mechanisms involved in periodontal disease. Establishment of Th1 and Th2 subsets from a naive T-cell precursor depends on transcriptional regulation. The aim of this study was to compare the expression of master transcription factor regulators T-bet and GATA-3, respectively, to indicate the predominance of Th1 and Th2 subsets in the presence and absence of periodontal disease.

Materials and Methods:

A gingival tissue biopsy sample was obtained from each of 10 severe periodontitis patients (>5 mm attachment loss) and 10 periodontally healthy patients (no attachment loss). Biopsies were immediately processed by real-time reverse transcriptase polymerase chain reaction and the difference in mRNA expression of T-bet and GATA-3 was assessed for each group.

Results:

The mRNA expression of T-bet was marginally increased about 1.31-fold in disease, while the GATA-3 levels showed a significant decrease of 4.39-fold in disease.

Conclusion:

The advanced periodontal lesions lack Th2 cells, which produce anti-inflammatory cytokines. The biopsies were therefore dominated by Th1 cells, which activate macrophages and osteoclasts.

Association study between clinicopathological variables and periodontal breakdown in gingival pyogenic granuloma

OBJECTIVE

The aim was to investigate a possible association between the immunoexpression of interleukin (IL)-4 and clinicopathological parameters with the periodontal breakdown observed in gingival pyogenic granuloma (PG).

MATERIALS AND METHODS

Paraffin-embedded samples of gingival PG (n = 46) were prepared for histological and immunohistochemical assessment. Demographic and clinical parameters were assessed by criteria based on age stratum, gender, smoking habit, evolution course, location, lesion size, macroscopic appearance, predisposing factors, recurrence, and periodontal breakdown. Histological assessment included the appearance of epithelial lining, microvessel density, inflammatory infiltrate density, interstitial fibrosis, and histological arrangement. A staining intensity distribution (SID) score was used to assess IL-4 immunoreactivity. The association between candidate predictor variables and periodontal breakdown was analyzed individually and adjusted for confounding using a bivariate binary logistic regression model.

RESULTS

Mean IL-4 SID values were significantly increased for long-standing and large lesions, presence of periodontal breakdown, high microvessel density, and moderate-to-severe inflammatory infiltrate density. While bivariate and univariate analyses revealed a positive association of the evolution course ≥12 months, lesion size >1 cm, high microvessel density, moderate-to-severe inflammatory infiltrate density, and IL-4 SID score ≥8.04 with periodontal breakdown, after bivariate logistic regression analysis, only the evolution course ≥12 months, moderate-to-severe inflammatory infiltrate density, and IL-4 SID score ≥8.04 remained as robust predictors of periodontal damage. Confounding and interaction effects between candidate predictor variables were also noted.

CONCLUSION

These findings suggest that while evolution course, inflammatory infiltrate density, and the overexpression of IL-4 may act as predictors of periodontal breakdown in gingival PG, there are mutual confounding and synergistic biological interactive effects with respect to the lesion size and microvessel density in the susceptible host that may be also associated with the bone resorption and tissue destruction.

CLINICAL RELEVANCE

Although the first-line therapy of gingival PG continues to be the surgical excision, this approach poses unwanted complications such as severe mucogingival defects and recurrence. Hence, early diagnosis and detection of these three significant predictor variables as well as timely surgical excision might help prevent the periodontal tissue destruction observed in some of these lesions.

Th2 cytokines efficiently stimulate periostin production in gingival fibroblasts but periostin does not induce an inflammatory response in gingival epithelial cells

OBJECTIVES

This study aims to clarify whether gingival fibroblasts produce periostin in response to Th2 cytokines which are elevated in periodontitis lesion and, if so, whether periostin affects the inflammatory response and matrix-protein metabolism.

DESIGN

Human gingival fibroblasts, periodontal ligament cells and the gingival epithelial cell line epi4 were stimulated with interleukin-4 (IL-4), IL-13, tumour necrosis factor-α (TNF-α) and Porphyromonas gingivalis lipopolysaccharide (LPS). Periostin expression was analysed by real-time polymerase chain-reaction (PCR) and Western blotting. The expression of the IL-4 receptor α-chain was evaluated by immunocytochemistry. The effect of periostin on the production of inflammatory cytokines and the expression of matrix protein-related genes was analysed by real-time PCR and enzyme-linked immunosorbent assay (ELISA).

RESULTS

While IL-4 and IL-13 significantly induced periostin production in gingival fibroblasts and periodontal ligament cells, no effect was observed in epi4 cells. No stimulatory effect of TNF-α or P. gingivalis LPS on the production of periostin was observed. The effect of periostin on the production of inflammatory cytokines was weak in gingival fibroblasts; however, little or no effect was observed on periodontal ligament cells or epi4 cells. No significant effect of periostin on the expression of matrix protein-related genes was found.

CONCLUSION

The results suggest that gingival fibroblasts may be a source of periostin in periodontitis lesions but periostin has only a limited role either in the inflammatory response or in matrix-protein metabolism. Thus, the role of periostin in the cellular interaction between epithelial and mesenchymal cells in gingiva may be distinct from that of skin.

The Presence of IL-17+/FOXP3+ Double-positive Cells in Periodontitis

Increasing evidence suggests that distinct inflammatory cytokines convert forkhead box protein P3 (FOXP3+) regulatory T-cells (Tregs) into IL-17-producing cells (Th17 cells) in vitro. However, this functional plasticity has not been examined in the pathogenesis of periodontal disease. In this study, we analyzed the IL-17A+FOXP3+ cells present in periodontitis lesions to determine the association between Treg conversion and the pathogenesis of periodontitis. The immunohistochemical analysis of gingival tissues demonstrated that the numbers of Th17 cells (IL-17A+FOXP3−) and Tregs (IL-17A−FOXP3+) were greater in periodontitis lesions than in gingivitis lesions. We further identified a small number of IL-17A+FOXP3+ cells in periodontitis lesions but not in gingivitis lesions. The flow cytometry analysis of CD4+ T-cell lines established from gingival tissues and the peripheral blood of periodontitis patients showed that the proportion of Tregs was reduced and the proportion of IL-17A+FOXP3+ cells among all FOXP3+ cells was elevated in gingival tissue T-cell lines relative to the proportions in peripheral blood T-cell lines. Our findings indicate that Treg-Th17 conversion may occur in periodontitis lesions. Further studies addressing the role of Treg conversion during inflammatory responses against periodontopathic bacteria are needed.

Comparative study of the in situ immune response in oral and nasal mucosal leishmaniasis

Mucosal Leishmaniasis (ML) may occur in both nasal and oral mucosa. However, despite the impressive tissue destruction, little is known about the oral involvement. To compare some changes underlying inflammation in oral and nasal ML, we performed immunohistochemistry on mucosal tissue of 20 patients with ML (nasal [n = 12]; oral [n = 8] lesions) and 20 healthy donors using antibodies that recognize inflammatory markers (CD3, CD4, CD8, CD22, CD68, neutrophil elastase, CD1a, CLA, Ki67, Bcl-2, NOS2, CD62E, Fas and FasL). A significantly larger number of cells, mainly T cells and macrophages, were observed in lesions than in healthy tissue. In addition, high nitric oxide synthase 2 (NOS2) expression was associated with a reduced detection of parasites, highlighting the importance of NOS2 for parasite elimination. Oral lesions had higher numbers of neutrophils, parasites, proliferating cells and NOS2 than nasal lesions. These findings, together with the shorter duration of oral lesions and more intense symptoms, suggest a more recent inflammatory process. It could be explained by lesion-induced oral cavity changes that lead to eating difficulties and social stigma. In addition, the frequent poor tooth conservation and gingival inflammation tend to amplify tissue destruction and symptoms and may impair and confuse the correct diagnosis, thus delaying the onset of specific treatment.

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

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.

Lymphocyte subpopulation in healthy and diseased gingival tissue

In this study, infiltrating lymphocytes subpopulation in gingival sections of healthy, inflamed, and periodontitis lesions was investigated. A set of cluster of differentiation (CD) antigen specific monoclonal/polyclonal antibodies to detect different cell types within the tissues was used. These included anti-CD3 (pan T-cell), anti-CD45RO (memory T-cell), anti-CD20 (B-cell), and kappa light chain (plasma cells). Biopsies of gingival tissue were obtained from 17 patients who had clinically healthy gingiva, from 18 patients with gingivitis, and 17 patients with periodontitis.

A significantly greater proportion of T-cells (P < 0.00) was observed in healthy gingival and gingivitis tissue samples compared to periodontitis tissue samples. In addition, a greater proportion of B-cells was observed in periodontitis lesions than in the gingival lesions (P < 0.00). The memory T-cells and the kappa light-chain plasma cells were present in both healthy and diseased tissues, suggestive of previous activation by periodontal pathogenic microorganisms.

In conclusion, these differences in the relative proportions of B- and T-cells may reflect a difference in the immunopathology of periodontitis and gingivitis lesions.

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

BACKGROUND

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

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Immune processes in periodontal disease: a review

The inflammatory and immune processes in periodontitis are complex and, although a great deal of information is available, many questions remain. Variation in human susceptibility to periodontitis has long been accepted, but the pathological basis of this is poorly understood. Similarly, we know little of the differences, if any, between the pathology of chronic and aggressive periodontitis. Genetics and environmental influences play a role in the susceptibility process, but if and how that translates through the immune and inflammatory processes to produce the plasma cell-dominated lesions seen in periodontitis remain to be elucidated. This review will focus on immunological aspects of the inflammatory changes seen in gingivitis and periodontitis, addressing both humoral and cellular responses to the microbial insult from dental plaque. A tendency for an individual or site to form an extensive plasma cell infiltrate may indicate an inability to defend against periodontopathogens and thus a predisposition to periodontitis. The issues to be considered include: 1) homing of immune and inflammatory cells to target tissues; 2) their local proliferation and synthetic activity; 3) the cytokine profile of the leukocytes; 4) the immunoglobulin subclasses of locally produced antibodies; 5) mucosal and systemic immune characteristics of the response; 6) the humoral immune response in periodontal health and disease states; and 7) the antigenic target of the immune response in periodontal lesions.

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.

Soluble beta-1,3/1,6-glucan from yeast inhibits experimental periodontal disease in Wistar rats

OBJECTIVE

We have investigated whether a purified immunomodulatory water soluble beta-1,3/1,6-glucan isolated from the cell wall of Bakers yeast, Saccharomyces cerevisiae, would influence the progression of ligature-induced periodontal disease, and to modulate accompanying cytokine and hypothalamic-pituitary-adrenal (HPA) axis responses to a lipopolysaccharide (LPS) challenge.

MATERIAL AND METHODS

beta-1,3/1,6-glucan (10 mg/kg/day) was given in the drinking water to Wistar rats during the entire experiment, starting 14 days before disease induction, while control rats were given tap water only. Periodontal disease was assessed when the ligatures had been in place for 35 days.

RESULTS

Orally administered soluble beta-1,3/1,6-glucan significantly reduced periodontal bone loss as measured on digital X-rays (p=0,026). Glucan-treated rats also showed a significantly enhanced plasma level of the HPA axis-driven hormone corticosterone (p=0.047), and of the cytokine transforming growth factor-1beta (p=0.032), as well as a tendency to enhanced IL-10 (p=0.106), induced by intra-peritoneally administered LPS.

CONCLUSION

Soluble beta-1,3/1,6-glucan administered by the oral route diminishes ligature-induced periodontal bone loss in this model. This effect may be attributable to the well documented ability of beta-1,3/1,6-glucan to stimulate macrophage phagocytosis and to skew the T helper (Th)1/Th2 balance towards Th1 and T regulatory responses. The HPA axis may play a significant role in beta-1,3/1,6-glucan induced immune modulation.

Interleukin-18 Concentrations and the Pathogenesis of Periodontal Disease

BACKGROUND

Interleukin-18 (IL-18) is reported as an important regulatory cytokine in non-oral inflammation. Our objective was to compare the concentrations of IL-18 within diseased and healthy human gingiva with concentrations of other T(H)1 and T(H)2 cytokines to determine possible effects of IL-18 on gingival inflammation.

METHODS

Gingival biopsies were obtained prior to routine tooth extraction. Gingiva was grouped by the depth of the adjacent gingival sulcus: < or =3 healthy (featuring no bleeding on probing) and > or =3 mm diseased (featuring bleeding on probing). Diseased gingiva was subdivided into 3, 4 to 6 and >6 mm groups. Gingival interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12, IL-18, and interferon (IFN)-gamma concentrations were assessed by enzyme linked immunosorbent assay (ELISA). Data were compared by factorial analysis of variance and the Pearson's correlation test.

RESULTS

Concentrations of IL-2, IL-4, IL-6, IL-10, IL-18, and IFN-gamma adjacent to 4 to 6 mm diseased sites were greater than adjacent to < or =3 mm healthy sites (P <0.001). IL-12 concentrations were lower within diseased than within healthy gingiva (P <0.001). IL-6 and IL-18 concentrations were greater adjacent to >6 mm sites compared to healthy sites (P <0.001); the concentrations of the other cytokines (except IL-12) were similar to healthy sites. IL-6 and IL-18 concentrations were positively correlated, and IFN-gamma and IL-12 negatively correlated, with the adjacent gingival sulcular depth.

CONCLUSIONS

Periodontal inflammation may not successfully resolve because of accumulation of IL-6 and IL-18, and decreased concentrations of IL-12, within diseased gingiva. Because of the highly significant correlation between IL-18 concentration and gingival sulcular depth, IL-18 may be a useful target for either preventive or palliative therapy for periodontitis.

Chronic glycine treatment inhibits ligature-induced periodontal disease in Wistar rats

OBJECTIVE

Dysregulation of immune and stress responses plays a significant role for the development and progression of inflammatory diseases, including periodontal disease. The non-essential amino acid glycine modulates immune and central nervous system (CNS) responses, and has been shown to beneficially affect tissue destructive inflammatory conditions. The purpose of this study was to test the ability of orally administered glycine to influence periodontal disease progression, as well as immune and hypothalamic-pituitary-adrenal (HPA) responses following lipopolysaccharide stimulation.

METHODS

Glycine was supplied in the drinking water during the whole experiment to male Wistar rats, starting 3 days before the induction of experimental ligature-induced periodontal disease. Control rats were given tap water only. The periodontal breakdown was assessed after the ligatures had been in place for 34 days. Following intraperitonal lipopolysaccharide stimulation, concentrations of the proximal cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin-10, as well as the HPA axis-derived hormone corticosterone, were measured in blood serum.

RESULTS

Orally administered glycine significantly reduced periodontal bone loss as measured by digital X-rays (p = 0.007). Bone loss was negatively correlated with increased serum glycine, whereas no significant relationship was found with TNF-alpha, interleukin-10, or corticosterone.

CONCLUSION

Chronic ingestion of glycine supplied in the drinking water significantly reduced periodontal bone loss. No effect of glycine on immune and HPA-axis responses was revealed. Further studies are needed to clarify the mechanisms of action.

Interleukin-11 and IL-17 and the Pathogenesis of Periodontal Disease

BACKGROUND

Interleukin (IL)-11 and IL-17 are cytokines that modulate the inflammatory process and have not been assessed within normal or inflamed gingival tissues. Our purpose was to compare concentrations of human IL-11 and IL-17 within healthy and diseased human gingiva to determine their possible role in the initiation or progression of periodontal diseases.

METHODS

Biopsies from healthy (non-hemorrhagic gingiva adjacent to a < or = 3 mm gingival sulcus) and diseased gingiva (hemorrhagic gingiva adjacent to a > or = 3 mm periodontal pocket) were studied. IL-11, IL-17, RANTES, and IL-6 concentrations were assessed within solubilized gingival biopsies by enzyme-linked immunosorbent assay. Data were compared by factorial analysis of variance and a post-hoc Tukey honestly significant difference (HSD) test. Regression analysis and partial correlation analysis (adjusted for sample weight) were also used to determine correlations between the variables.

RESULTS

Interleukin-11 concentrations were highest within gingiva adjacent to 3 mm diseased pockets (P < 0.001), and IL-17 concentrations were highest at 4 to 5 mm sites compared to other sites (P < 0.001). Gingival concentrations of both cytokines were significantly lower in gingiva adjacent to a > or = 6 mm pocket. RANTES concentrations were significantly greater in gingiva adjacent to > or = 6 mm pockets than in tissues derived from other sites (P < 0.001). IL-11, IL-6, and RANTES concentrations were significantly correlated with sulcular depth.

CONCLUSIONS

Gingival concentrations of IL-11 and IL-17 are different in diseased gingiva adjacent to 3, 4 to 5, and > or = 6 mm pockets, suggesting that their concentrations change as a consequence of the progression of gingivitis to periodontitis and that both cytokines could have a significant role in this progression. These data may be useful for the design of procedures for prevention of periodontal disease.

Enhancement of Th2 pathways and direct activation of B cells by the gingipains of Porphyromonas gingivalis

Porphyromonas gingivalis cysteine proteinases (gingipains) have been associated with virulence in destructive periodontitis, a disease process that has been linked with Th2 pathways. Critical in maintaining Th2 activity is the response of B lymphocytes to environmental interleukin (IL)-4, a cytokine that also counteracts Th1-cell differentiation. Here we demonstrate that while the gingipains effectively degrade interleukin (IL)-4 under serum-free conditions, limited hydrolysis was observed in the presence of serum even after prolonged incubation. Gingipains up-regulated CD69 expression directly in purified peripheral blood B cell preparations. Further, the induction of IL-4 receptor expression on B cells by gingipains correlates with B cell activation, which is also manifested by a mitogenic response. These results suggest that the gingipains of P. gingivalis act during the early stage of B-cell growth as a competence signal, whereby sensitized B cells might become more responsive to further challenge in the disease-susceptible individual.

Oral treatment with SRP299 (killed Mycobacterium vaccae ) inhibits experimental periodontal disease in Wistar rats

OBJECTIVE

Mycobacterium vaccae injected subcutaneously was previously shown to prevent and treat ligature-induced periodontal disease (PD) in Wistar rats (Breivik & Rook 2000, 2002). Since mycobacteria are readily taken up via Peyer's patches in the intestine, we have now tested the ability of oral SRP299 (killed M. vaccae) to prevent ligature-enhanced PD in Wistar rats, and to modulate the accompanying cytokine and corticosterone responses.

MATERIAL AND METHODS

A single oral dose of SRP299 (1 mg) was given 14 days before the application of ligatures. PD was assessed when the ligatures had been in place for 56 days.

RESULTS

Oral SRP299 reduced bone loss (p = 0.036, X-ray; p = 0.061, histometry) and fibre loss, both on the ligatured (p = 0.0047) and control (p = 0.005) sides, and also reduced the level of TNF-alpha (p = 0.0137) and corticosterone (p = 0.048) induced by intraperitoneal endotoxin lipopolysaccharide (LPS).

CONCLUSIONS

SRP299 administered by the oral route diminishes ligature-induced bone and fibre loss in this model. This effect may be attributable to the known ability of SRP299 to evoke regulatory T cells, although the mechanism could not be investigated in this study. Treated rats also had less excitable hypothalamo-pituitary-adrenal (HPA) axes. HPA axis overactivity is a known risk factor in human PD. Trials of SRP299 in human PD are now justified.

Immunohistochemical analysis of Th1/Th2 cytokine profiles and androgen receptor expression in the pathogenesis of nifedipine-induced gingival overgrowth

BACKGROUND

Numerous studies have demonstrated that gingival overgrowth may be associated with androgen and cytokine expression in tissues.

OBJECTIVES

The aim of this study was to compare the expression of androgen receptor-presenting cells (AR+ cells) and Th1/Th2 cytokine [Th1: interleukin (IL)-2, interferon-gamma (IFN-gamma); Th2: IL-4, IL-10, IL-13] expression cells in tissue sections of patients with gingival overgrowth.

MATERIALS AND METHODS

Tissue samples were collected from patients with healthy periodontium (H group), adult periodontitis (P group), surgically extracted teeth (S group), and nifedipine-induced gingival overgrowth (NIGO group). The clinical periodontal parameters of pocket depth (PD), bleeding on probing (BOP), and plaque control record (PCR) were measured around selected sample teeth. Gingival biopsies were further processed by immunohistochemical staining method. The expressions of cells positive for AR, IL-2, IFN-gamma, IL-4, IL-10, and IL-13 were counted by predetermined semiquantitative methods.

RESULTS

Our results indicated that AR, IL-2, IFN-gamma, IL-4, IL-10, and IL-13 were intensively expressed in the nuclei of inflammatory cells and fibroblasts of gingival connective tissue. Stronger expressions of AR, IL-2, and IFN-gamma were found in the NIGO group. The AR+ cells/0.01 mm2 in gingival fibroblasts were significantly higher in the NIGO group (80.2 +/- 10.7) than those of the periodontitis group (52.5 +/- 11.8) and control group (37.4 +/- 11.3) (P < 0.05). The cytokine expression of the NIGO group showed a trend towards Th1-type expression (IL-2; P = 0.0001). In the surgically extracted tooth group, a stronger expression of Th2-type cytokine (IL-4, Il-10, IL-13; P < 0.05) was found in inflammatory cells. In a comparison of the IL-2/IL-4-labeled cell ratio of the four groups, a descending sequence was discovered as NIGO group (0.92 +/- 0.97) > H group (0.81 +/- 0.61) > P group (0.77 +/- 0.82) > S group (0.58 +/- 1.77).

CONCLUSIONS

Our data support the following: (i) taking nifedipine may elevate the expression of AR in susceptible oral tissue, e.g. gingiva; (ii) the cytokine profile of T-cells in NIGO tissue indicates a trend preferentially towards Th1 activity; and (iii) elevation of AR expression cells and prominent Th1 cytokine-labeled cells are two significant factors in the pathogenesis of NIGO.

Influence of periodontal disease on Th1/Th2-type cytokines in saliva of HIV-positive individuals

Cytokines present during immune responses have a tremendous influence on resistance/susceptibility to oral diseases including periodontal disease and oral opportunistic infections in the immunocompromised individual, as seen by altered Th cytokines in saliva with human immunodeficiency virus (HIV) disease progression and oropharyngeal candidiasis. This study was designed to evaluate whether the presence of severe periodontal disease has any influence on Th cytokines in saliva of HIV-positive persons. For this, saliva from a cohort of HIV-positive persons with mild or severe periodontitis was evaluated for Th cytokines. A dominant Th2-type cytokine profile in saliva was validated in HIV-positive subjects with considerable immune suppression, irrespective of periodontal disease status. However, no significant differences in concentrations of Th1- or Th2-type cytokines in saliva were observed when stratified by periodontal status. Thus, the lack of salivary influences by periodontitis eliminates periodontal disease as a variable in interpretations regarding correlates of local cytokines during oral manifestations of HIV.

The role of the TH1 and TH2 immune responses in loosening and osteolysis of cemented total hip replacements

The mechanisms underlying the development of osteolysis and aseptic loosening have an impact on the longevity of total hip replacements (THRs). This study examines the specific roles of lymphocytes in the TH1 and TH2 subsets in osteolysis and aseptic loosening of THR. Tissue from periprosthetic regions from patients with loose, cemented acetabular components were used to determine the TH1 and TH2 cytokine profile. Twelve tissue specimens from patients with radiographic signs of osteolysis, and nine tissue specimens from patients with no signs of osteolysis were harvested during revision surgery. Immunohistochemistry using primary antibodies against CD3, interferon (IFN)-gamma, interleukin (IL)-2, IL-4, and IL-10 was performed on frozen sections to determine the percentage of positive cells for each of the sections. No statistically significant differences in the percentage of positive cells expressing cytokines characteristic of the TH1 pathway (IFN-gamma, IL-2) or TH2 pathway (IL-4, IL-10) were found when comparing osteolytic and non-osteolytic tissues. However, significant numbers of T cells (averaging about 10% of the total cells) and TH1 and TH2 immune cytokines (averaging 3-5% of cells) implicate a possible role for immune processes at the prosthetic interface.

Association of the -1087 IL 10 gene polymorphism with severe chronic periodontitis in Swedish Caucasians

BACKGROUND

Severe forms of periodontitis are suggested to have a genetic basis.

OBJECTIVE

The aim of the present investigation was to study association of an IL10 gene polymorphism (G to A transition at the -1087 position) with severe chronic periodontitis.

MATERIALS AND METHODS

Two groups of Swedish Caucasian subjects were included. One group consisted of 60 patients (aged 36-74 years; mean 54.5+/-8.5) with severe and generalized chronic periodontitis. The patients exhibited bone loss >50% at all teeth. Thirty-nine periodontally healthy subjects between 35-78 years of age (mean 51.0+/-10.9) were also recruited. DNA was isolated from peripheral blood cells and genotyping was performed by combination of PCR with restriction endonuclease mapping.

RESULTS

The proportion of subjects that exhibited the GG genotype was significantly larger in the group with severe periodontitis than in the periodontally healthy group. The difference regarding the occurrence of the GG genotype between the two groups was more conspicuous in non-smokers and yielded an odds ratio of 6.1. The G allele carriage in non-smokers was >90 % in the periodontitis group and was significantly higher than in the healthy controls.

CONCLUSION

It is suggested that the -1087 IL10 polymorphism in Caucasian subjects of a north European origin is associated with severe chronic periodontitis.

Monocyte-derived RANTES is intrinsically elevated in periodontal disease while MCP-1 levels are related to inflammation and are inversely correlated with IL-12 levels

Bacteria colonizing tooth surfaces are essential in the induction of an inflammatory response in the periodontal tissues, but do not cause periodontitis in everyone, implicating differences in the host immune response. These possible differences were studied using lipopolysaccharide (LPS)-stimulated whole blood cell cultures (WBCC), which revealed a down regulation of monocyte derived interleukin-12 (IL-12p70) in untreated periodontitis patients and an up regulation after therapy. IL-12p70 is a crucial factor in the differentiation of Th1 cell responses. Since CC chemokines are able to influence the T cell differentiation via cytokine secretion in antigen-presenting cells, the production of CC chemokines in periodontitis was evaluated. Therefore WBCC were stimulated with LPS from Escherichia coli for 18 h and the levels of IL-12p70 and CC chemokines were measured in the supernatants by ELISA. Untreated periodontitis patients released 2 fold more RANTES (regulated on activation normal T cell expressed and secreted) (P = 0.01) and lower levels of IL-12p70 in comparison to controls (P < 0.05). A trend towards higher levels of macrophage chemoattractant protein-1 (MCP-1) (P = 0.07) was also seen in untreated periodontitis patients; while similar levels of monocyte derived chemokine (MDC) and macrophage inflammatory proteins-1 alpha and -1 beta (MIP-1 alpha and -1 beta) were found. After periodontal therapy no changes were seen with regard to MDC, MIP-1 alpha, MIP-1 beta and RANTES, whereas the MCP-1 levels decreased (P < 0.05) and the IL-12p70 levels strongly increased (P < 0.01). The data showed a consistent inverse correlation between the levels of MCP-1 and IL-12p70, and their proportional changes after therapy correlated with the clinical inflammatory response after therapy. This indicates that the disease state regulates the release of IL-12p70 and MCP-1 in E. coli LPS-stimulated WBCC. In contrast, the persistent augmented levels of RANTES after therapy are suggestive for an intrinsic behaviour.

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.

Immunohistochemical analysis of lymphocyte subpopulations in cyclosporin A-induced gingival overgrowth

BACKGROUND

Cyclosporin A (CsA) is an immunosuppressive agent that is known to induce gingival overgrowth (GO). Pharmacological, genetic, immunologic, and inflammatory factors seem to be involved in the complex pathogenesis of drug-induced GO. Lymphocyte subpopulations in human gingival connective tissue have been implicated in the pathogenesis of inflammatory periodontal diseases. One purpose of this study was to quantify CD4, CD8-, CD57-, and epithelial membrane antigen (EMA)-positive cells in the gingiva of renal transplant recipients treated with CsA, and compare them to findings in healthy controls. A second aim was to correlate cell numbers with clinical findings.

METHODS

The study included 19 kidney recipients who were taking CsA and had significant GO (CsAGO+), 13 recipients who were taking CsA but showed no GO (CsAGO-), and 14 systemically healthy individuals with gingivitis (C). Sections from gingival biopsies were incubated with monoclonal antibodies for CD4, CD8, EMA, and CD57, and then analyzed using the avidin-biotin complex method. In each specimen, the mononuclear cell types were quantified and their distribution was evaluated in 3 separate tissue zones: S = subepithelial connective tissue beneath the sulcular epithelium; O = subepithelial connective tissue beneath the oral epithelium; and M = middle connective tissue.

RESULTS

There were no significant differences among the groups with respect to the numbers of CD4+ and CD8+ cells in each of the 3 zones (P >0.05). In zone S, the CsAGO+ group had significantly more EMA-positive cells than either the C or CsAGO- groups (P <0.05). There were significant differences among the groups regarding numbers of CD57+ (natural killer) cells in zone M, with the lowest cell numbers in the CsAGO+ patients (P<0.05).

CONCLUSIONS

The results showed that low numbers of natural killer cells are important in the expression of plaque-induced inflammatory changes in CsA-associated GO. It appears that these cells may influence the drug's ability to induce proliferative activity.

Some cytokine profiles of T-helper cells in lesions of advanced periodontitis

OBJECTIVE

The aim of the present study was to analyze some cytokine profiles of T-helper cells in periodontitis lesions.

MATERIAL AND METHODS

22 adult patients (7 females and 15 males, aged 24-66 years) with advanced and generalized chronic periodontitis were recruited. Clinical and radiographical characteristics of periodontal disease was assessed. From each patient a gingival biopsy was obtained from one randomly selected diseased interproximal site. The soft tissue sample was prepared for immunohistochemical analysis. Double staining was performed to detect cells positive for both the CD4 marker and different cytokines, i.e. interleukin (IL)-2, IL-4, IL-6 and interferon-gamma (IFN-gamma).

RESULTS

The lesions in advanced periodontitis contained similar proportions of cells positive for the different cytokine markers examined. In addition, the number of cells expressing cytokine profiles for either T helper-1 (IFN-gamma + IL-2) or T helper-2 (IL-4 + IL-6) was similar.

CONCLUSION

It is suggested that the lesions of periodontitis are regulated by a combined Th-1 and Th-2 function.

Treatment with SRL172 (heat-killed Mycobacterium vaccae) inhibits progression of established experimental periodontal disease in Wistar rats

Periodontal disease is accompanied by a change in the periodontal bacterial flora, and an increase in Th2 cytokine expression. Therefore, preparations that can down-regulate Th2 responses and increase Th1 responses to bacteria may have therapeutic effects. SRL172, a preparation of heat-killed Mycobacterium vaccae (NCTC11659), has been shown to have these properties in man and animals and, in a previous study, a single subcutaneous injection of this material 13 days before application of ligatures to the right second molars of Wistar rats strikingly reduced subsequent destruction of the tooth-supporting tissues. The same material has therefore been tested in a therapeutic protocol, in rats with ongoing periodontal disease. A silk ligature was placed round the maxillary right second molar in the gingival sulcus on day 0. This was removed after two weeks, and the animals immediately received 0.1 mg SRL172 s.c. or saline. One week later (i.e. at three weeks), a boost of 1.0 mg SRL172 or saline was given. Animals were sacrificed at eight weeks (i.e. five weeks after the booster dose). Treatment of ongoing periodontal disease with SRL172 significantly reduced fibre loss (p = 0.046 by histometry) and bone loss (p = 0.0008 by radiography) on the ligatured side, and reduced fibre loss (p = 0.0086) on the control side. Thus SRL172 is an effective treatment in this model. As SRL172 has undergone extensive safety testing in man, these results justify clinical studies in periodontal disease, and such studies are now planned.

Macrophage inflammatory protein 3alpha-CC chemokine receptor 6 interactions play an important role in CD4+ T-cell accumulation in periodontal diseased tissue

The regulatory role of chemokines and chemokine receptors on specific lymphocyte recruitment into periodontal diseased tissue is poorly characterized. We observed that lymphocytes infiltrating inflamed gingival tissue expressed marked levels of CCR6. In periodontal diseased tissue, the expression of MIP-3alpha mRNA was detected by RT-PCR and further, MIP-3alpha was distributed in the basal layer of gingival epithelial cells, microvascular endothelial cells and the areas of inflammatory cells as shown by immunohistochemistry. Moreover, CCR6-expressing cells infiltrated into periodontal diseased tissue, and the proportion of CCR6-positive CD4+ T cells was significantly elevated in periodontal diseased tissue compared with peripheral blood in the same patients. Furthermore, gingival lymphocytes isolated from patients showed migration toward MIP-3alpha in an in vitro chemotaxis assay in which migration was abrogated by specific antibody to CCR6. Thus, these findings suggested that CCR6 and the corresponding chemokine, MIP-3alpha may have an important regulatory role in specific lymphocyte migration into inflamed periodontal tissue.

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.

A type 2 response in lipopolysaccharide (LPS)-stimulated whole blood cell cultures from periodontitis patients

It is acknowledged that periodontitis results from the interaction of the host immune response with bacteria accumulating on the tooth surfaces. Although bacteria are essential, they are insufficient to cause the disease. Despite this knowledge it remains unclear why certain individuals are more susceptible to periodontitis than others. Therefore the present study investigated whether differences exist in the actual immune response between periodontitis patients and controls after stimulation of peripheral blood cells. Whole blood cell cultures (WBCC) were stimulated with LPS from Escherichia coli during 18 h and the release of prostaglandin E2 (PGE2), IL-1beta, IL-6, IL-8, IL-10, IL-12p40, IL-12p70 and tumour necrosis factor-alpha (TNF-alpha) was measured. The levels of PGE2 were two-fold higher in the WBCC from periodontitis patients than from controls. In contrast, the levels of IL-12p70 in WBCC from patients were two-fold lower. Furthermore, WBCC from patients secreted lower levels of IL-1beta and higher levels of IL-8 when compared with WBCC from controls. No differences were observed with respect to IL-6, IL-10, IL-12p40 and TNF-alpha production. It is known from the literature that LPS-stimulated WBCC reflect specifically the behaviour of the monocytes and that monocytes are peripheral precursors of antigen-presenting cells (APC). Therefore it is concluded that the monocytes in the present WBCC from periodontitis patients are responsible for the higher levels of PGE2 and lower levels of IL-12p70. Since it is has been shown that APC-derived IL-12p70 induces type (Th1) cells that promote cellular immunity, while APC-derived PGE2 induces type 2-helper (Th2) cells that promote humoral immunity, it is postulated that APC from periodontitis patients may have a bias in directing Th2 responses and thereby promoting the humoral immunity in periodontitis.

Effective in vitro clearance of Porphyromonas gingivalis by Fc alpha receptor I (CD89) on gingival crevicular neutrophils

Porphyromonas gingivalis has been implicated as a causative pathogen in periodontitis. Immunotherapeutic approaches have recently been suggested to aid in the clearance of P. gingivalis from disease sites. Because antibody-Fc receptor (FcR) interactions play a role in the effector functions of polymorphonuclear neutrophils (PMN), we evaluated which FcR on PMN from gingival crevicular fluid (GCF) serves as an optimal target molecule for FcR-directed immunotherapy. GCF PMN and peripheral blood (PB) PMN from adult periodontitis patients were analyzed for their immunoglobulin G (IgG) and IgA FcR (Fc gamma R and Fc alpha R, respectively) expression and function by studying IgG- and IgA-mediated elimination of P. gingivalis. GCF PMN exhibited higher Fc alpha RI and Fc gamma RI levels and lower Fc gamma RIIa and Fc gamma RIIIb levels than PB PMN. Functional studies revealed that GCF PMN exhibited less of a capacity to phagocytose and kill IgG1-opsonized P. gingivalis than PB PMN. IgA1-mediated phagocytosis and killing capacity was, however, comparable between GCF PMN and PB PMN. In summary, these in vitro results document that Fc alpha RI represents a candidate target for FcR-directed immunotherapy for the clearance of P. gingivalis.

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

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

Anti-inflammatory cytokine IL-10 and T cell cytokine profile in periodontitis granulation tissue

Th2 cells are more abundant than Th1 cells in periodontitis lesions, but the relative importance of the Th1 and Th2 subsets in periodontal disease is not understood. In addition, the role of proinflammatory and anti-inflammatory cytokines in this disease process is unclear. Biopsies were obtained from 10 patients with early onset periodontitis (EOP) and 10 patients with adult periodontitis (AP). From all of the patients in the AP group we were able to obtain and section the gingival tissue to serve as controls. We used polyclonal monospecific antibodies to detect cells expressing IL-2, IL-4, IL-6, IL-10 and IL-15, tumour necrosis factor (TNF-alpha) and interferon-gamma (IFN-gamma) in formalin-fixed, paraffin-embedded sections of granulation tissue from periodontitis lesions. We also employed a series of oligonucleotide probes to detect cells expressing the cytokine transcripts in the same tissue biopsies. Cells that expressed IL-4 or IL-6 were more numerous than cells expressing either IL-2 or IFN-gamma. Th2 cells were more numerous in EOP and AP tissues. IL-15 substitutes for IL-2 in a number of biological activities related to the Th1 immune response, and interestingly, in periodontal lesions the IL-15-expressing cells outnumbered IL-2-expressing cells, suggesting that this is the pattern of immune regulation by T cells in the periodontium. The functional balance in the T cell subsets detected by their cytokine profiles underlies the importance of the anti-inflammatory mechanisms taking place in the diseased tissue. The numbers of inflammatory leucocytes that express the anti-inflammatory cytokine IL-10 are much more widely distributed than those that express the proinflammatory cytokines IL-6 and TNF-alpha. This study suggests that large numbers of infiltrating inflammatory cells as well as accessory cells are involved in the down-regulation of the inflammatory and immune response in periodontitis.

CD26 Immuno-Expression and Periodontal Disease Progression

Immunological mechanisms participate in the pathogenesis of human chronic inflammatory periodontal disease (CIPD). Human CD4(+) lymphocytes express functionally heterogeneous profiles of cytokine production. CD26 is an integral membrane glycoprotein, that is, a marker of Th1-like cytokine development. The purpose of the present study was to compare the immuno-expression of CD26 receptor in periodontal sites with and without clinical attachment loss (CAL). Five patients with rapidly progressing periodontitis and one with juvenile periodontitis were investigated. Each patient presented at least one site with and without CAL. Ten sites with CAL and nine without any CAL were biopsied, followed by the immunohistochemical identification of the CD26 receptor using the MIB-DS2/7 antibody. The results demonstrated that the percentage of positive cells for this antigen in the periodontal sites with CAL was not significantly different from those without attachment loss. Therefore, Th1 cell impairment may not be directly involved with periodontal attachment loss.

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

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

Selective expansion of T cells in gingival lesions of patients with chronic inflammatory periodontal disease

Chronic inflammatory periodontal diseases are characterized by a cellular infiltrate and are similar in many respects to other chronic inflammatory diseases. While periodontopathic bacteria have been recognized as the principal causative agent and the immune response to these bacteria is thought to be responsible for the tissue destruction, the full aetiological spectrum is still incompletely understood. In addition to many cell types such as polymorphonuclear leucocytes and macrophages, T cells have been implicated in pathogenesis and are considered to have regulatory roles in progression of the disease. Based on our recent studies demonstrating biased expression of several Vbeta families in periodontitis tissues, the aim of this study was to characterize further the T cells relevant to the disease process by reverse transcription-polymerase chain reaction-single-strand conformation polymorphism (RT-PCR-SSCP) and subsequent nucleotide sequence analysis of complementarity-determining region 3 (CDR3) of the TCR beta-chain. In spite of the likely involvement of numerous bacteria, the present study has clearly shown the oligoclonality of infiltrating T cells in periodontitis lesions in contrast to low clonality of peripheral blood T cells as evidenced by the appearance of distinct bands in gingival tissue samples and smear pattern of peripheral blood on SSCP gels. These were confirmed by the DNA sequencing of the CDR3 of Vbeta16 of selected samples. The analysis of deduced amino acid sequences demonstrated amino acid motifs in the CDR3 region of the periodontitis lesion-derived sequences from each patient. The results indicate that gingival tissue-infiltrating T cells recognizing a limited number of antigens or epitopes are involved in the disease process.