Gamma interferon positively modulates Actinobacillus actinomycetemcomitans-specific RANKL+ CD4+ Th-cell-mediated alveolar bone destruction in vivo

Perspectives and challenges in developing small molecules targeting purine nucleoside phosphorylase

As a cytosolic enzyme involved in the purine salvage pathway metabolism, purine nucleoside phosphorylase (PNP) plays an important role in a variety of cellular functions but also in immune system, including cell growth, apoptosis and cancer development and progression. Based on its T-cell targeting profile, PNP is a potential target for the treatment of some malignant T-cell proliferative cancers including lymphoma and leukemia, and some specific immunological diseases. Numerous small-molecule PNP inhibitors have been developed so far. However, only Peldesine, Forodesine and Ulodesine have entered clinical trials and exhibited some potential for the treatment of T-cell leukemia and gout. The most recent direction in PNP inhibitor development has been focused on PNP small-molecule inhibitors with better potency, selectivity, and pharmacokinetic property. In this perspective, considering the structure, biological functions, and disease relevance of PNP, we highlight the recent research progress in PNP small-molecule inhibitor development and discuss prospective strategies for designing additional PNP therapeutic agents.

Regulatory T cells showed characteristics of T helper-17(Th17) cells in mice periodontitis model

OBJECTIVES

This study aimed to clarify the regulatory role of Th17-Treg balance in periodontitis and further reveal Treg plasticity.

MATERIALS AND METHODS

An experimental periodontitis model was established by ligation and injection of Pg-LPS. Inflammatory factors were measured by ELISA and RT-PCR. Alveolar bone absorption was evaluated by micro-CT and histomorphology. Quantities of Treg and Th17 cell and their related gene expression were examined. Furthermore, after magnetic bead-sorting spleen Treg cells, Treg/Th17 characteristic genes were explored. Immunofluorescence double staining of Foxp3 and IL-17 was conducted to further reveal Treg plasticity.

RESULTS

Inflammatory cytokines in serum and gingival tissue increased significantly in periodontitis, which revealed obvious crestal bone loss. Further analysis showed that the number of Th17 cells and expression of related genes increased more significantly than Treg cells, demonstrating Treg-Th17 imbalance. Flow cytometry showed that the proportions of Treg cells in the blood and spleen were lower in periodontitis group. Furthermore, Foxp3 was downregulated, and Rorc/ IL-17A were increased in Treg cells of periodontitis group. Immunofluorescence double staining showed significantly increased number of IL-17+Foxp3+ cells in periodontitis.

CONCLUSIONS

These results provided evidence that Treg cells showed characteristics of Th17 cells in mice with periodontitis, although its mechanisms require further study.

Maintaining homeostatic control of periodontal bone tissue

Alveolar bone is a unique osseous tissue due to the proximity of dental plaque biofilms. Periodontal health and homeostasis are mediated by a balanced host immune response to these polymicrobial biofilms. Dysbiotic shifts within dental plaque biofilms can drive a proinflammatory immune response state in the periodontal epithelial and gingival connective tissues, which leads to paracrine signaling to subjacent bone cells. Sustained chronic periodontal inflammation disrupts "coupled" osteoclast-osteoblast actions, which ultimately result in alveolar bone destruction. This chapter will provide an overview of alveolar bone physiology and will highlight why the oral microbiota is a critical regulator of alveolar bone remodeling. The ecology of dental plaque biofilms will be discussed in the context that periodontitis is a polymicrobial disruption of host homeostasis. The pathogenesis of periodontal bone loss will be explained from both a historical and current perspective, providing the opportunity to revisit the role of fibrosis in alveolar bone destruction. Periodontal immune cell interactions with bone cells will be reviewed based on our current understanding of osteoimmunological mechanisms influencing alveolar bone remodeling. Lastly, probiotic and prebiotic interventions in the oral microbiota will be evaluated as potential noninvasive therapies to support alveolar bone homeostasis and prevent periodontal bone loss.

Niche Specific Microbiota-Dependent and Independent Bone Loss around Dental Implants and Teeth

Oral mucosal homeostasis is achieved by complex immunologic mechanisms, orchestrating host immunity to adapt to the physiologic functions of the various specialized niches in the oral cavity. Dental implants introduce a novel mucosal niche to the immune system to deal with. Nevertheless, the immune mechanisms engaged toward implants and whether they have broader effects are not well defined. Using a murine model, we found an accumulation of neutrophils and RANKL-expressing T and B lymphocytes in the implant-surrounding mucosa, accompanied by local bone loss. Surprisingly, the presence of implants had an impact on remote periodontal sites, as elevated inflammation and accelerated bone loss were detected in intact distant teeth. This was due to microbial dysbiosis induced by the implants, since antibiotic treatment prevented bone loss around teeth. However, antibiotic treatment failed to prevent the loss of implant-supporting bone, highlighting the distinct mechanisms mediating bone loss at each site. Further analysis revealed that implants induced chronic lymphocyte activation and increased mRNA expression of IFN-α and accumulation of IFN-α–producing plasmacytoid dendritic cells, which we previously reported as bone-destructive immune responses. Collectively, this study demonstrates that implants have a strong and broad impact on oral mucosal homeostasis, inducing periodontal bone loss in a niche-specific manner that is both microbiota dependent and independent.

Transient Expression of IL-17A in Foxp3 Fate-Tracked Cells in Porphyromonas gingivalis-Mediated Oral Dysbiosis

In periodontitis Porphyromonas gingivalis contributes to the development of a dysbiotic oral microbiome. This altered ecosystem elicits a diverse innate and adaptive immune response that simultaneously involves Th1, Th17, and Treg cells. It has been shown that Th17 cells can alter their gene expression to produce interferon-gamma (IFN-γ). Forkhead box P3 (Foxp3) is considered the master regulator of Treg cells that produce inhibitory cytokines like IL-10. Differentiation pathways that lead to Th17 and Treg cells from naïve progenitors are considered antagonistic. However, it has been reported that Treg cells expressing IL-17A as well as IFN-γ producing Th17 cells have been observed in several inflammatory conditions. Each scenario appears plausible with T cell transdifferentiation resulting from persistent microbial challenge and consequent inflammation. We established that oral colonization with P. gingivalis drives an initial IL-17A dominated Th17 response in the oral mucosa that is dependent on intraepithelial Langerhans cells (LCs). We hypothesized that Treg cells contribute to this initial IL-17A response through transient expression of IL-17A and that persistent mucosal colonization with P. gingivalis drives Th17 cells toward an IFN-γ phenotype at later stages of infection. We utilized fate-tracking mice where IL-17A- or Foxp3-promoter activity drives the permanent expression of red fluorescent protein tdTomato to test our hypothesis. At day 28 of infection timeline, Th17 cells dominated in the oral mucosa, outnumbering Th1 cells by 3:1. By day 48 this dominance was inverted with Th1 cells outnumbering Th17 cells by nearly 2:1. Tracking tdTomato⁺ Th17 cells revealed only sporadic transdifferentiation to an IFN-γ-producing phenotype by day 48; the appearance of Th1 cells at day 48 was due to a late de novo Th1 response. tdTomato⁺ Foxp3⁺ T cells were 35% of the total live CD4⁺T cells in the oral mucosa and 3.9% of them developed a transient IL-17A-producing phenotype by day 28. Interestingly, by day 48 these IL-17A-producing Foxp3⁺ T cells had disappeared. Therefore, persistent oral P. gingivalis infection stimulates an initial IL-17A-biased response led by Th17 cells and a small but significant number of IL-17A-expressing Treg cells that changes into a late de novo Th1 response with only sporadic transdifferentiation of Th17 cells.

Inhibitory effect of serotype a of Aggregatibacter actinomycetemcomitans on the increased destructive potential of serotype b

OBJECTIVE

The serotype b of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) induces higher cytokine production in dendritic cells (DCs) compared with the other serotypes. However, this increased immunostimulatory potential was modified when DCs were co-infected with the other A. actinomycetemcomitans serotypes. This study aimed to analyze whether the production of interferon gamma (IFN-γ), C-reactive protein (CRP), matrix metalloproteinase (MMP)-2, and MMP-9, as well as the activity of osteoclasts, also varies when DCs are co-infected with the A. actinomycetemcomitans serotypes.

MATERIALS AND METHODS

Human DCs were stimulated with the A. actinomycetemcomitans serotypes using the following stimulatory conditions: serotype a/b/c/a+b/a+c/b+c/a+b+c. The IFN-γ, CRP, and MMP-2 levels were quantified by ELISA. The active form of MMP-9 was quantified using fluorescent functional assays. The MMP-2 gelatinolytic activity was identified by zymogram. The osteoclast activity was determined by quantifying the TRAP expression and resorption-pit formation using cytochemistry and osteoassays.

RESULTS

Higher levels of IFN-γ, CRP, MMP-2, MMP-9, and osteoclast activity were detected when DCs were stimulated with the serotype b of A. actinomycetemcomitans compared with the others. This increased immunostimulatory potential attributed to serotype b diminished when DCs were co-infected with the serotype a.

CONCLUSIONS

This study provides new insights into the virulence of A. actinomycetemcomitans and reveals important differences in the immunostimulatory and pro-destructive potential among its serotypes.

Application of molecular, microbiological, and immunological tests for the diagnosis of bone and joint tuberculosis

BACKGROUND

To evaluate the application of interferon gamma release assay (IGRA), rifampicin resistant real-time fluorescence quantitative PCR technique Xpert Mycobacterium tuberculosis/rifampicin (Xpert MTB/RIF), and the levels of TNF-α and TGF-β in the diagnosis of bone and joint tuberculosis.

METHODS

Eighty-six patients with bone and joint tuberculosis, diagnosed by pathology or microbiology, were examined by Xpert MTB/RIF and IGRA (T-SPOT. TB) for Mycobacterium tuberculosis infection, and the TNF-α and TGF-β levels of the patients were measured.

RESULTS

The sensitivity of IGRA in diagnosing bone and joint tuberculosis was 81.4%; Xpert MTB/RIF's sensitivity was 70.9%. The combined sensitivity of the two methods was 91.9%. The combined detection sensitivity of the two methods was higher than individual IGRA or Xpert MTB/RIF detection sensitivity. The TNF-α and TGF-β levels in bone and joint tuberculosis patients were higher than those in the control group.

CONCLUSION

Xpert MTB/RIF, IGRA, TNF-α, and TGF-βs expression have value in the rapid diagnosis of bone and joint tuberculosis, and the sensitivity and accuracy of bone and joint tuberculosis diagnosis by combining them can improve it.

The function of dendritic cells in modulating the host response

Dendritic cells (DCs) are antigen-presenting cells that capture, process, and present antigens to lymphocytes to initiate and regulate the adaptive immune response. DCs detect bacteria in skin and mucosa and migrate into regional lymph nodes, where they stimulate antigen-specific T and B lymphocyte activation and proliferation. DCs direct CD4 T cells to differentiate to T-cell subsets such as T helper cells types 1, 2, and 17, and regulatory T cells. The periodontium is chronically exposed to oral bacteria that stimulate an inflammatory response to induce gingivitis or periodontitis. DCs play both protective and destructive roles through activation of the acquired immune response and are also reported to be a source of osteoclast precursors that promote bone resorption. FOXO1, a member of the forkhead box O family of transcription factors, plays a significant role in the activation of DCs. The function of DCs in periodontal inflammation has been investigated in a mouse model by lineage-specific deletion of FOXO1 in these cells. Deletion of FOXO1 reduces DC protective function and enhances susceptibility to periodontitis. The kinase Akt, phosphorylates FOXO1 to inhibit FOXO activity. Hence the Akt-FOXO1 axis may play a key role in regulating DCs to have a significant impact on periodontal disease.

Parathyroid hormone-related peptide (1-34) reduces alveolar bone loss in type 1 diabetic rats

OBJECTIVE

To investigate the role of parathyroid hormone related protein (PTHrP) in diabetic periodontitis.

METHODS

After injected with 55mg/kg streptozotocin, diabetic rats were treated subcutaneously with low-dose (40μg/kg, once daily for 5days per week), middle-dose (80μg/kg) or high-dose (160μg/kg) PTHrP(1-34) peptide. Treatment continued for 12 weeks. Changes in periodontal tissues were confirmed by micro-computerized tomography assay and H&E analysis. We used tartrate resistant acid phosphatase (TRAP) staining to identify osteoclast cells. The expression of TNF-α, IL-1β and IL-6 was assessed by immunohistochemistry and Western blot.

RESULTS

Tooth-supporting structure loss was observed in periodontal tissues of diabetic rats. PTHrP (1-34) attenuated alveolar bone loss, especially in the middle-dose and high-dose group. Whereas TNF-α, IL-1β and IL-6 protein levels were increased in the diabetic gingival tissues, PTHrP (1-34) treatment inhibited the increase of IL-1β and IL-6, but had no effect on TNF-α.

CONCLUSION

Type 1 diabetes increased the susceptibility to periodontal disease. Intermittent administration of PTHrP (1-34) exhibited an inhibitory effect on alveolar bone resorption and the gingival inflammation in periodontal tissues of diabetic rats.

Protective and Destructive Immunity in the Periodontium: Part 2—T-cell-mediated Immunity in the Periodontium

Based on the results of recent research in the field and Part 1 of this article (in this issue), the present paper will discuss the protective and destructive aspects of the T-cell-mediated adaptive immunity associated with the bacterial virulent factors or antigenic determinants during periodontal pathogenesis. Attention will be focused on: (i) osteoimmunology and periodontal disease; (ii) some molecular techniques developed and applied to identify critical microbial virulence factors or antigens associated with host immunity (with Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis as the model species); and (iii) summarizing the identified virulence factors/antigens associated with periodontal immunity. Thus, further understanding of the molecular mechanisms of the host’s T-cell-mediated immune responses and the critical microbial antigens related to disease pathogenesis will facilitate the development of novel therapeutics or protocols for future periodontal treatments. Abbreviations used in the paper are as follows: A. actinomycetemcomitans ( Aa), Actinobacillus actinomycetemcomitans; Ab, antibody; DC, dendritic cells; mAb, monoclonal antibody; pAb, polyclonal antibody; OC, osteoclast; PAMP, pathogen-associated molecular patterns; P. gingivalis ( Pg), Porphyromonas gingivalis; RANK, receptor activator of NF-κB; RANKL, receptor activator of NF-κB ligand; OPG, osteoprotegerin; TCR, T-cell-receptors; TLR, Toll-like receptors.

Increased early inflammatory response and osteoclastic activity in gingival tissues following conventional osseous resective surgery compared with the fibre retention technique: a pilot study

BACKGROUND AND OBJECTIVE

The retention of suprabony connective fibres attached into the root cementum during fibre retention osseous resective surgery (FibReORS) results in a more conservative intrasurgical removal of bone, and limits further bone loss and patient morbidity during healing, compared with conventional osseous resective surgery (ORS). This may be a result of the protective effect of preserved connective tissue over the interproximal sites and the lower activation of the inflammatory mechanisms. Thus, the aim of this pilot study was to compare the expression of inflammatory and osteoclastic activity markers in gingival tissues following FibReORS and ORS in the early postsurgical phase.

MATERIAL AND METHODS

Twenty-six posterior sextants requiring osseous resective surgery were selected in 13 patients with chronic periodontitis: 13 sextants were randomly assigned to ORS and 13 to FibReORS in a split-mouth design. Gingival biospies were collected during the surgical sessions and at suture removal. Tissue samples were analysed to evaluate the expression of proinflammatory and immunity regulatory mediators (interleukin-1α, C-X-C motif chemokine ligand 5, interferon-γ and tumour necrosis factor-α), cluster of differentiation 14 (CD14; a monocyte/macrophage marker) and TRAP (an osteoclast marker) using immunohistochemical, immunofluorescence and cytofluorimetric analyses, respectively.

RESULTS

Postsurgery, a higher number of inflammatory cells and stronger expression of proinflammatory cytokines were observed in the epithelium and connective tissue of ORS gingival samples compared with FibReORS gingival samples (p < 0.001). This was accompanied by increased numbers of CD14-positive and TRAP-positive cells.

CONCLUSION

Retention of the supracrestal connective fibres appears to reduce the postsurgical intensity of the host-mediated inflammatory response.

Mucosal Langerhans Cells Promote Differentiation of Th17 Cells in a Murine Model of Periodontitis but Are Not Required for Porphyromonas gingivalis-Driven Alveolar Bone Destruction

Periodontitis is a chronic oral inflammatory disease affecting one in five individuals that can lead to tooth loss. CD4(+) Th cells activated by a microbial biofilm are thought to contribute to the destruction of alveolar bone surrounding teeth by influencing osteoclastogenesis through IL-17A and receptor activator for NF-κB ligand effects. The relative roles of mucosal Ag presentation cells in directing Th cell immune responses against oral pathogens and their contribution to destruction of alveolar bone remain unknown. We tested the contribution of mucosal Langerhans cells (LCs) to alveolar bone homeostasis in mice following oral colonization with a well-characterized human periodontal pathogen, Porphyromonas gingivalis We found that oral mucosal LCs did not protect from or exacerbate crestal alveolar bone destruction but were responsible for promoting differentiation of Th17 cells specific to P. gingivalis. In mice lacking LCs the Th17 response was suppressed and a Th1 response predominated. Bypassing LCs with systemic immunization of P. gingivalis resulted in a predominantly P. gingivalis-specific Th1 response regardless of whether LCs were present. Interestingly, we find that in vivo clonal expansion of P. gingivalis-specific Th cells and induced regulatory T cells does not depend on mucosal LCs. Furthermore, destruction of crestal alveolar bone induced by P. gingivalis colonization occurred regardless of the presence of mucosal LCs or P. gingivalis-specific Th17 cells. Our data indicate that both LCs and Th17 cells are redundant in contributing to alveolar bone destruction in a murine model of periodontitis.

Inflammatory Response Influences Treatment of Localized Aggressive Periodontitis

We previously reported a systemic hyperinflammatory response to bacterial lipopolysaccharide (LPS) in children with localized aggressive periodontitis (LAP). Additionally, different levels of this response were observed within the LAP group. It is unknown whether this hyperinflammatory response influences the clinical response to periodontal treatment in these children. Therefore, the goal of this study was to evaluate the influence of LPS responsiveness present prior to treatment on the clinical response to treatment within the LAP cohort. Prior to treatment, peripheral blood was collected from 60 African American participants aged 5 to 21 y, free of systemic diseases, and diagnosed with LAP. Blood was stimulated with ultrapure LPS from Escherichia coli, and Luminex assays were performed to quantify 14 cytokine/chemokine levels. Principal component and cluster analyses were used to find patterns of cytokine/chemokine expression among participants and subdivide them into clusters. Three distinct clusters emerged among LAP participants: a high responder group (high level of response for INFg, IL6, and IL12p40), a mixed responder group (low for some and high for other cytokines/chemokines), and a low responder group (low overall cytokine/chemokine response). Periodontal clinical parameters were compared among these groups prior to and 3, 6, and 12 mo following treatment with mechanical debridement and systemic antibiotics. High responders presented the lowest reductions in clinical parameters after treatment, whereas the low responders presented the highest reductions. In our LAP participants, distinct patterns of LPS response were significantly predictive of changes in clinical parameters after treatment. Future studies are needed to evaluate the underlying mechanisms predicting the heterogeneity of LAP activity, severity, and response to treatment (ClinicalTrials.gov NCT01330719).

Immunoexpression of transforming growth factor beta and interferon gamma in radicular and dentigerous cysts

INTRODUCTION

The aim of this study was to evaluate and compare the immunohistochemical expression of transforming growing factor beta (TGF-β) and interferon gamma (IFN-γ) between radicular cysts (RCs) and dentigerous cysts (DCs).

METHODS

Twenty RCs and DCs were selected for analysis of the immunoexpression of TGF-β and IFN-γ in the epithelium and capsule.

RESULTS

The cell reactivity of TGF-β and IFN-γ in the lining epithelium and capsule of RCs showed no significant differences when compared with DCs (P > .05). There was a tendency of a higher expression of TGF-β in the capsule of DCs.

CONCLUSIONS

Our results showed the presence of TGF-β and IFN-γ in RCs and DCs, supporting the hypothesis that both participate in the development of these lesions, where IFN-γ usually plays a role in bone resorption, which is counterbalanced by the osteoprotective activity performed by TGF-β.

Emerging roles of immunostimulatory oral bacteria in periodontitis development

Periodontitis is a common dental disease which results in irreversible alveolar bone loss around teeth, and subsequent tooth loss. Previous studies have focused on bacteria that damage the host and the roles of commensals to facilitate their colonization. Although some immune responses targeting oral bacteria protect the host from alveolar bone loss, recent studies show that particular host defense responses to oral bacteria can induce alveolar bone loss. Host-damaging and immunostimulatory oral bacteria cooperatively induce bone loss by inducing gingival damage followed by immunostimulation. In mouse models of experimental periodontitis induced by either Porphyromonas gingivalis or ligature, γ-proteobacteria accumulate and stimulate host immune responses to induce host damage. Here we review the differential roles of individual bacterial groups in promoting bone loss through the induction of host damage and immunostimulation.

Interferon-γ, interleukins-6 and -4, and factor XIII-A as indirect markers of the classical and alternative macrophage activation pathways in chronic periodontitis

BACKGROUND

Macrophages account for 5% to 30% of the inflammatory infiltrate in periodontitis and are activated by the classic and alternative pathways. These pathways are identified by indirect markers, among which interferon (IFN)-γ and interleukin-6 (IL)-6 of the classic pathway and IL-4 of the alternative pathway have been studied widely. Recently, factor XIII-A (FXIII-A) was reported to be a good marker of alternative pathway activation. The aim of this study is to determine the macrophage activation pathways involved in chronic periodontitis (CP) by the detection of the indirect markers IFN-γ, IL-6, FXIII-A, and IL-4.

METHODS

Biopsies were taken from patients with CP (n = 10) and healthy individuals (n = 10) for analysis of IFN-γ, IL-6, IL-4, and FXIII-A by Western blot (WB), immunohistochemistry (IHC), and enzyme-linked immunosorbent assay (ELISA). The same biopsies of healthy and diseased gingival tissue were used, and the expressions of these markers were compared between healthy individuals and those with CP.

RESULTS

The presence of macrophages was detected by CD68+ immunohistochemistry and their IFN-γ, IL-6, IL-4, and FXIII-A markers by WB, IHC, and ELISA in all samples of healthy and diseased tissue. IL-6, IL-4, and FXIII-A were significantly higher in patients with CP, whereas FXIII-A was higher in healthy individuals.

CONCLUSION

The presence of IFN-γ, IL-6, IL-4, and FXIII-A in healthy individuals and in patients with CP suggests that macrophages may be activated by both classic and alternative pathways in health and in periodontal disease.

The role of osteoimmunology in periodontal disease

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

Natural killer T cells mediate alveolar bone resorption and a systemic inflammatory response in response to oral infection of mice with Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

T and B cells are known to be involved in the disease process of periodontitis. However, the role of natural killer T cells in the pathogenesis of periodontitis has not been clarified.

MATERIALS AND METHODS

To examine the role of these cells, C57BL/6J (wild-type), CD1d(-/-) and α-galactosylceramide (αGC)-stimulated wild-type mice were orally infected with Porphyromonas gingivalis strain W83.

RESULTS

Apart from CD1d(-/-) mice, the level of alveolar bone resorption was elevated by the infection and was further accelerated in αGC-stimulated mice. The infection induced elevated levels of serum amyloid A and P. gingivalis-specific IgG in the sera, although the degree of elevation was much smaller in the CD1d(-/-) mice. Infection-induced RANKL elevation was only observed in αGC-stimulated mice. Although the cytokines produced by splenocytes were mainly T-helper 1 type in wild-type mice, those in αGC-stimulated mice were predominantly T-helper 2 type. In the liver, the infection demonstrated no effect on the gene expression for interferon-γ, interleukin-4 and RANKL except αGC-stimulated mice in which the infection upregulated the gene expressions.

CONCLUSION

This study is the first to show that natural killer T cells upregulated systemic and local inflammatory responses induced by oral infection with P. gingivalis, thereby contributing to the progression of alveolar bone resorption.

The transition state analog inhibitor of Purine Nucleoside Phosphorylase (PNP) Immucillin-H arrests bone loss in rat periodontal disease models

Purine nucleoside phosphorylase (PNP) is a purine-metabolizing enzyme that catalyzes the reversible phosphorolysis of 6-oxypurine (deoxy)nucleosides to their respective bases and (deoxy)ribose-1-phosphate. It is a key enzyme in the purine salvage pathway of mammalian cells. The present investigation sought to determine whether the PNP transition state analog inhibitor (Immucillin-H) arrests bone loss in two models of induced periodontal disease in rats. Periodontal disease was induced in rats using ligature or LPS injection followed by administration of Immucillin-H for direct analysis of bone loss, histology and TRAP staining. In vitro osteoclast differentiation and activation of T CD4+ cells in the presence of Immucillin-H were carried out for assessment of RANKL expression, PNP and Cathepsin K activity. Immucillin-H inhibited bone loss induced by ligatures and LPS, leading to a reduced number of infiltrating osteoclasts and inflammatory cells. In vitro assays revealed that Immucillin-H could not directly abrogate differentiation of osteoclast precursor cells, but affected lymphocyte-mediated osteoclastogenesis. On the other hand, incubation of pre-activated T CD4+ with Immucillin-H decreased RANKL secretion with no compromise of cell viability. The PNP transition state analog Immucillin-H arrests bone loss mediated by T CD4+ cells with no direct effect on osteoclasts. PNP inhibitor may have an impact in the treatment of diseases characterized by the presence of pathogens and imbalances of bone metabolism.

Langerhans cells down-regulate inflammation-driven alveolar bone loss

Excessive bone resorption is frequently associated with chronic infections and inflammatory diseases. Whereas T cells were demonstrated to facilitate osteoclastogenesis in such diseases, the role of dendritic cells, the most potent activators of naive T cells, remains unclear. Using a model involving inflammation-driven alveolar bone loss attributable to infection, we showed that in vivo ablation of Langerhans cells (LCs) resulted in enhanced bone loss. An increased infiltration of B and T lymphocytes into the tissue surrounding the bone was observed in LC-ablated mice, including receptor activator of NF-κB ligand (RANKL)-expressing CD4(+) T cells with known capabilities of altering bone homeostasis. In addition, the absence of LCs significantly reduced the numbers of CD4(+)Foxp3(+) T-regulatory cells in the tissue. Further investigation revealed that LCs were not directly involved in presenting antigens to T cells. Nevertheless, despite their low numbers in the tissue, the absence of LCs resulted in an elevated activation of CD4(+) but not CD8(+) T cells. This activation involved elevated production of IFN-γ but not IL-17 or IL-10 cytokines. Our data, thus, reveal a protective immunoregulatory role for LCs in inflammation-induced alveolar bone resorption, by inhibiting IFN-γ secretion and excessive activation of RANKL(+)CD4(+) T cells with a capability of promoting osteoclastogenesis.

Selective serotonin reuptake inhibitors attenuate the antigen presentation from dendritic cells to effector T lymphocytes

Fluoxetine, one of the selective serotonin reuptake inhibitors (SSRIs), has been found to possess immune modulation effects, in addition to its antidepressant effects. However, it remains unclear whether SSRIs can suppress the antigen-presenting function of dendritic cells (DCs). Therefore, Fluoxetine was applied to a co-culture of Aggregatibacter actinomycetemcomitans (Aa)-reactive T cells (×Aa-T) isolated from Aa-immunized mice and DCs. This resulted in the suppressed proliferation of ×Aa-T stimulated with Aa-antigen presentation by DCs. Specifically, Fluoxetine increased the extracellular 5-hydroxytryptamine (5-HT) in the ×Aa-T/DC co-culture, whereas exogenously applied 5-HT promoted T-cell proliferation in the ×Aa-T/DC co-culture, indicating that Fluoxetine-mediated suppression of ×Aa-T/DC responses cannot be attributed to extracellular 5-HT. Instead, Fluoxetine remarkably suppressed the expression of costimulatory molecule ICOS-L on DCs. Fluoxetine also promoted a greater proportion of CD86(Low) immature DCs than CD86(High) mature DCs, while maintaining the expression levels of CD80, MHC-class-II and PD-L1. These results suggested that Fluoxetine suppressed the ability of DCs to present bacterial antigens to T cells, and the resulting T-cell proliferation, in a SERT/5-HT-independent manner and that diminished expression of ICOS-L on DCs and increase of CD86(Low) immature DCs caused by Fluoxetine might be partially associated with Fluoxetine-mediated suppression of DC/T-cell responses.

Locally administered interferon-γ accelerates lipopolysaccharide-induced osteoclastogenesis independent of immunohistological RANKL upregulation

BACKGROUND AND OBJECTIVE

Interferon-γ (IFN-γ) potently inhibits RANKL-induced osteoclastogenesis in vitro. In contrast, previous studies have shown that an increase in IFN-γ expression is correlated with an increase in lipopolysaccharide (LPS)-induced bone loss in vivo. However, it is not clear whether local IFN-γ accelerates osteoclastogenesis or not in vivo. Therefore, the aim of this study was to clarify the role of local IFN-γ in LPS-induced osteoclastogenesis.

MATERIALS AND METHODS

We induced bone loss in calvaria by injecting LPS. One group of mice received an IFN-γ injection together with LPS injection, while another group received IFN-γ 2 d after LPS injection. Bone resorption was observed histologically. Next, we stimulated murine bone marrow macrophages with macrophage-colony stimulating factor and RANKL in vitro. We added different doses of IFN-γ and/or LPS at 0 or 48 h time points. Cells were stained with tartrate-resistant acid phosphatase at 72 h.

RESULTS

Local administration of IFN-γ together with LPS injection did not affect osteoclast formation. However, IFN-γ injected after LPS injection accelerated osteoclast formation. Also, we confirmed that IFN-γ added at 0 h inhibited RANKL-induced osteoclastogenesis in vitro. However, inhibition by IFN-γ added at 48 h was reduced compared with that by IFN-γ added at 0 h. Interestingly, IFN-γ together with a low concentration of LPS accelerated osteoclast formation when both were added at 48 h compared with no addition of IFN-γ.

CONCLUSION

The results suggest that local IFN-γ accelerates osteoclastogenesis in certain conditions of LPS-induced inflammatory bone loss.

Review of osteoimmunology and the host response in endodontic and periodontal lesions

Both lesions of endodontic origin and periodontal diseases involve the host response to bacteria and the formation of osteolytic lesions. Important for both is the upregulation of inflammatory cytokines that initiate and sustain the inflammatory response. Also important are chemokines that induce recruitment of leukocyte subsets and bone-resorptive factors that are largely produced by recruited inflammatory cells. However, there are differences also. Lesions of endodontic origin pose a particular challenge since that bacteria persist in a protected reservoir that is not readily accessible to the immune defenses. Thus, experiments in which the host response is inhibited in endodontic lesions tend to aggravate the formation of osteolytic lesions. In contrast, bacteria that invade the periodontium appear to be less problematic so that blocking arms of the host response tend to reduce the disease process. Interestingly, both lesions of endodontic origin and periodontitis exhibit inflammation that appears to inhibit bone formation. In periodontitis, the spatial location of the inflammation is likely to be important so that a host response that is restricted to a subepithelial space is associated with gingivitis, while a host response closer to bone is linked to bone resorption and periodontitis. However, the persistence of inflammation is also thought to be important in periodontitis since inflammation present during coupled bone formation may limit the capacity to repair the resorbed bone.

Transcriptional regulation of the mucosal immune system mediated by T-bet

The immune system faces the arduous task of defending the mucosal surfaces from invading pathogens, but must simultaneously repress responses against commensal organisms and other inert antigens that are abundant in the external environment, as inappropriate immune activation might expose the host to increased risk of autoimmunity. The behavior of individual immune cells is governed by the expression of transcription factors that are responsible for switching immune response genes on and off. T-bet (T-box expressed in T cells) has emerged as one of the key transcription factors responsible for controlling the fate of both innate and adaptive immune cells, and its expression in different immune cells found at mucosal surfaces is capable of dictating the critical balance between permitting robust host immunity and limiting susceptibility to autoimmunity and allergy.

Interferon-γ +874A/T polymorphism in relation to generalized chronic periodontitis and the presence of periodontopathic bacteria

BACKGROUND

Interferon gamma (IFN-γ) is one of the key regulatory cytokines that has a significant effect on immune responses. It may be important in the chronic inflammatory diseases such as periodontitis in which increased IFN-γ levels were found. The aim of this study was to analyze +874A/T polymorphism in the IFN-γ gene and its associations with the presence of periodontopathic bacteria and susceptibility to generalized chronic periodontitis (CP).

METHODS

A total of 498 unrelated Czech white subjects were included in the present study. Genomic DNA was obtained from the peripheral blood of 244 patients with CP and 254 healthy subjects. The IFN-γ +874A/T polymorphism was determined by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). Subgingival bacterial colonization (A. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythia, T. denticola, P. micros, F. nucleatum in subgingival pockets) was investigated by the DNA-microarray based periodontal pathogen detection kit in a subgroup of subjects (N=110).

RESULTS

Our results showed no differences in the allele and genotype frequencies of the IFN-γ +874A/T polymorphism between patients with CP and controls (P>0.05). Although we found significant differences in the occurrence of periodontal bacteria between patients with CP and healthy controls (from P<0.00001 to P<0.05), no significant association between IFN-γ +874A/T polymorphism and periodontal pathogens was observed in any group.

CONCLUSIONS

In conclusion, these findings indicate that putative functional variant in the IFN-γ is not associated with susceptibility to chronic periodontitis or microbial composition in the Czech population.

Destructive and protective roles of cytokines in periodontitis: a re-appraisal from host defense and tissue destruction viewpoints

Periodontal diseases (PD) are chronic infectious inflammatory diseases characterized by the destruction of tooth-supporting structures, being the presence of periodontopathogens required, but not sufficient, for disease development. As a general rule, host inflammatory mediators have been associated with tissue destruction, while anti-inflammatory mediators counteract and attenuate disease progression. With the discovery of several T-cell subsets bearing distinct immunoregulatory properties, this pro- vs. anti-inflammatory scenario became more complex, and a series of studies has hypothesized protective or destructive roles for Th1, Th2, Th17, and Treg subpopulations of polarized lymphocytes. Interestingly, the "protective vs. destructive" archetype is usually considered in a framework related to tissue destruction and disease progression. However, it is important to remember that periodontal diseases are infectious inflammatory conditions, and recent studies have demonstrated that cytokines (TNF-α and IFN-γ) considered harmful in the context of tissue destruction play important roles in the control of periodontal infection. Therefore, in this review, the state-of-the-art knowledge concerning the protective and destructive roles of host inflammatory immune response will be critically evaluated and discussed from the tissue destruction and control-of-infection viewpoints.

Evidence that metyrapone in the presence of inflammation modulates cytokine mRNA expression

OBJECTIVE

Metyrapone (MT) has been used clinically to decrease glucocorticoid levels in human and animal studies. However, the potential effects of MT in the presence of inflammation are poorly understood. Thus, the aim of this study was to evaluate the effects of the administration of MT on the mRNA levels of pro-inflammatory cytokines in the presence of inflammation induced by the well-established model of ligature-induced periodontitis in rats.

MATERIAL AND METHODS

Sixty animals were randomly assigned into three experimental groups of 20 rats each: G1-control; G2-periodontal disease (PD) induced by cotton ligature; G3-PD associated with 3 daily doses of MT (50mg/kg/3×3h). After 30 days, all animals were killed by decapitation. Blood samples were taken and the concentrations of corticosterone and catecholamines measured. Marginal tissues around ligated and non-ligated teeth were harvested and gene expression was assessed by quantitative polymerase chain reaction technique (qPCR). Moreover, the area of interradicular bone loss (ABL) was histometrically determined.

RESULTS

Data analysis showed that: (i) ligature placement resulted in a significant ABL, as compared to non-ligated sites of G1 group; (ii) mRNA levels of all the pro-inflammatory factors assessed (INF-γ, TNF-α, IL-1β and IL-6) were increased in the PD group (G2) (p<0.05) when compared to G1; (iii) there were no significant differences in corticosterone and catecholamine plasmatic levels between the three groups; (iv) MT administration, in the presence of inflammation, induces an increased ABL and significantly increased mRNA levels of all pro-inflammatory cytokines analyzed (p<0.05).

CONCLUSION

Within the limits of this study, it can be concluded that MT in the presence of inflammation may modulate expression of pro-inflammatory cytokines, regardless of its effect on plasma corticosterone levels.

Identification of immunological parameters associated with the alveolar bone level in periodontal patients

Purpose

The present study was performed to clarify the relationship between periodontal disease severity and selected immunological parameters consisting of serum IgG titer against periodontopathogenic bacteria, the expression of the helper T-cell cytokine by gingival mononuclear cells, and patients' immunoreactivity to cross-reactive heat shock protein (HSP) epitope peptide from P. gingivalis HSP60.

Methods

Twenty-five patients with moderate periodontitis had their gingival connective tissue harvested of gingival mononuclear cells during an open flap debridement procedure and peripheral blood was drawn by venipuncture to collect serum. The mean level of interproximal alveolar bone was calculated to be used as an index for periodontal disease severity for a given patient. Each of selected immunologic parameters was subject to statistical management to seek their correlations with the severity of periodontal disease.

Results

A significant correlation could not be identified between serum IgG titers against specific bacteria (Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans, and Streptococcus mutans) and the severity of periodontal disease. Expression of interleukin (IL)-10 by gingival mononuclear cells was statistically significant in the group of patients who had higher levels of alveolar bone height. However, a similar correlation could not be demonstrated in cases for IL-4 or interferon-γ. Patients' serum reactivity to cross-reactive epitope peptide showed a significant correlation with the amount of alveolar bone.

Conclusions

It was concluded that expression of IL-10 by gingival mononuclear cells and patients' sero-reactivity to the cross-reactive HSP peptide of P. gingivalis HSP60 were significantly correlated with alveolar bone height.

Association of a genetic polymorphism (-44 C/G SNP) in the human DEFB1 gene with expression and inducibility of multiple beta-defensins in gingival keratinocytes

Background

Human β-defensins (hBDs) are antimicrobial peptides with a role in innate immune defense. Our laboratory previously showed that a single nucleotide polymorphism (SNP) in the 5' untranslated region of the hBD1 gene (DEFB1), denoted -44 (rs1800972), is correlated with protection from oral Candida. Because this SNP alters the putative mRNA structure, we hypothesized that it alters hBD1 expression.

Methods

Transfection of reporter constructs and evaluation of antimicrobial activity and mRNA expression levels in keratinocytes from multiple donors were used to evaluate the effect of this SNP on constitutive and induced levels of expression.

Results

Transfection of CAT reporter constructs containing the 5' untranslated region showed that the -44 G allele yielded a 2-fold increase in CAT protein compared to other common haplotypes suggesting a cis effect on transcription or translation. The constitutive hBD1 mRNA level in human oral keratinocytes was significantly greater in cells from donors with the -44 GG genotype compared to those with the common CC genotype. Surprisingly, the hBD3 mRNA level as well as antimicrobial activity of keratinocyte extracts also correlated with the -44 G allele. Induced levels of hBD1, hBD2, and hBD3 mRNA were evaluated in keratinocytes challenged with Toll-like receptor 2 and 4 ligands, interleukin-1β, TNFα, and interferon-γ (IFNγ). In contrast to constitutive expression levels, IFNγ-induced keratinocyte hBD1 and hBD3 mRNA expression was significantly greater in cells with the common CC genotype, but there was no clear correlation of genotype with hBD2 expression.

Conclusion

The DEFB1 -44 G allele is associated with an increase in overall constitutive antimicrobial activity and expression of hBD1 and hBD3 in a manner that is consistent with protection from candidiasis, while the more common C allele is associated with IFNγ inducibility of these β-defensins and is likely to be more protective in conditions that enhance IFNγ expression such as chronic periodontitis. These results suggest a complex relationship between genetics and defensin expression that may influence periodontal health and innate immune responses.

Inhibitory effect of galectin-3 on the cytokine-inducing activity of periodontopathic Aggregatibacter actinomycetemcomitans endotoxin in splenocytes derived from mice

Galectins, a family of animal lectins, are involved not only in development and differentiation but also in immunoregulation and host-pathogen interactions. Galectin-3 interacts with lipopolysaccharides in gram-negative bacteria such as Escherichia coli, Salmonella minnesota and Pseudomonas aeruginosa. The present study investigated whether galectin-3 inhibited the cytokine-inducing activity of periodontopathic bacterial lipopolysaccharides using splenocytes derived from mice of different ages. Lipopolysaccharides were extracted from Aggregatibacter actinomycetemcomitans Y4 and Porphyromonas gingivalis ATCC 33277, and then purified. Enzyme-linked immunosorbent assay (ELISA) analysis revealed that galectin-3 adhered to A. actinomycetemcomitans lipopolysaccharides, but not to the lipopolysaccharides of P. gingivalis. Splenocytes were prepared from 1- or 7-month-old C57BL/6 mice. Either A. actinomycetemcomitans lipopolysaccharides (200 ng mL(-1)) alone or lipopolysaccharides and murine galectin-3 (10 microg mL(-1)) were added to culture solutions, and the release of interleukin-6 (IL-6) and interferon-gamma (IFNgamma) from splenocytes was measured by ELISA after a 17-h incubation. In all mice tested, A. actinomycetemcomitans lipopolysaccharide stimulation significantly increased the production of IL-6 and IFNgamma (P<0.01). Murine galectin-3 suppressed lipopolysaccharide-induced cytokine production in the splenocytes of the 1-month-old mice (P<0.02 for IL-6; P<0.05 for IFNgamma), but not in the splenocytes of the 7-month-old mice. This suggests that responses change with age.

The role of T cells in osteoporosis, an update

Emerging evidence highlights the importance of the interplay between the bone and immune systems. That evidence bolsters a longstanding recognition that estrogen deficiency, infection, inflammation, and autoimmune disorders are associated with systemic and local bone loss. Yet, only recently has an understanding emerged that T lymphocytes and their products act as key regulators of osteoclast formation, life span, and activity. This review presents this understanding of the process of T lymphocytes and their products mediating osteoporosis and explores some of the most recent findings and hypotheses to explain their action in bone. A more complete appreciation of the interactions between immune and bone cells should lead to targeted therapeutic strategies for diseases that affect either or both systems.

Involvement of SOCS3 in regulation of CD11c+ dendritic cell-derived osteoclastogenesis and severe alveolar bone loss

To investigate the role of suppressor of cytokine signaling (SOCS) molecules in periodontal immunity and RANKL-mediated dendritic cell (DC)-associated osteoclastogenesis, we analyzed SOCS expression profiles in CD4(+) T cells and the effect of SOCS3 expression in CD11c(+) DCs during periodontal inflammation-induced osteoclastogenesis and bone loss in nonobese diabetic (NOD) versus humanized NOD/SCID mice. Our results of ex vivo and in vitro analyses showed that (i) there is significantly higher SOCS3 expression associated with RANKL(+) T-cell-mediated bone loss in correlation with increased CD11c(+) DC-mediated osteoclastogenesis; (ii) the transfection of CD11c(+) DC using an adenoviral vector carrying a dominant negative SOCS3 gene significantly abrogates TRAP and bone-resorptive activity; and (iii) inflammation-induced TRAP expression, bone resorption, and SOCS3 activity are not associated with any detectable change in the expression levels of TRAF6 and mitogen-activated protein kinase signaling adaptors (i.e., Erk, Jnk, p38, and Akt) in RANKL(+) T cells. We conclude that SOCS3 plays a critical role in modulating cytokine signaling involved in RANKL-mediated DC-derived osteoclastogenesis during immune interactions with T cells and diabetes-associated severe inflammation-induced alveolar bone loss. Therefore, the development of SOCS3 inhibitors may have therapeutic potential as the target to halt inflammation-induced bone loss under pathological conditions in vivo.

IL-13 production by regulatory T cells protects against experimental autoimmune encephalomyelitis independently of autoantigen

Treatment with an anti-inflammatory Salmonella vaccine expressing enterotoxigenic Escherichia coli colonization factor Ag 1 (CFA/I) proved effective in stimulating protective, potent CD25(+)CD4(+) regulatory T (T(reg)) cells in susceptible mice challenged with experimental autoimmune encephalomyelitis (EAE). Because the Salmonella vector was considerably less protective, we questioned whether altering fimbrial subunit expression to resemble conventional Salmonella expression may impact T(reg) cell potency. The Salmonella-CFA/I vaccine was modified to limit fimbrial subunit expression to the intracellular compartment (Salmonella-CFA/I(IC)). SJL mice were challenged with proteolipid protein peptide 139-151 to induce EAE and orally treated with one of three Salmonella vaccines 6 days postchallenge. Treatment with Salmonella-CFA/I(IC) greatly reduced clinical disease, similarly as Salmonella-CFA/I, by subduing IL-17 and IL-21; however, mechanisms of protection differed as evident by increased IL-13 and IFN-gamma but diminished TGF-beta production by T(reg) cells from Salmonella-CFA/I(IC)-treated mice. Adoptive transfer of T(reg) cells from both CFA/I-expressing constructs was equivalent in protecting against EAE, showing minimal disease. Although not as potent in its protection, CD25(-)CD4(+) T cells from Salmonella-CFA/I(IC) showed minimal Th2 cells, but vaccination did prime these Th2 cells rendering partial protection against EAE challenge. In vivo IL-13 but not IFN-gamma neutralization compromised protection conferred by adoptive transfer with Salmonella-CFA/I(IC)-induced T(reg) cells. Thus, the Salmonella-CFA/I(IC) vaccine elicits T(reg) cells with attributes from both the Salmonella vector and Salmonella-CFA/I vaccines. Importantly, these T(reg) cells can be induced to high potency by simply vaccinating against irrelevant Ags, offering a novel approach to treat autoimmune diseases independently of the autoantigen.

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

BACKGROUND AND OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

The use of rodent models to investigate host-bacteria interactions related to periodontal diseases

Even though animal models have limitations, they are often superior to in vitro or clinical studies in addressing mechanistic questions and serve as an essential link between hypotheses and human patients. Periodontal disease can be viewed as a process that involves four major stages: bacterial colonization, invasion, induction of a destructive host response in connective tissue and a repair process that reduces the extent of tissue breakdown. Animal studies should be evaluated in terms of their capacity to test specific hypotheses rather than their fidelity to all aspects of periodontal disease initiation and progression. Thus, each of the models described below can be adapted to test discrete components of these four major steps, but not all of them. This review describes five different animal models that are appropriate for examining components of host-bacteria interactions that can lead to breakdown of hard and soft connective tissue or conditions that limit its repair as follows: the mouse calvarial model, murine oral gavage models with or without adoptive transfer of human lymphocytes, rat ligature model and rat Aggregatibacter actinomycetemcomitans feeding model.

Overexpression of interleukin-1beta and interleukin-6 may play an important role in periodontal breakdown in type 2 diabetic patients

BACKGROUND AND OBJECTIVE

This study evaluated whether the biochemical changes associated with type 2 diabetes modulate the expression of interleukin-1beta, interleukin-6, interleukin-8, and interferon-gamma in sites with chronic periodontitis.

MATERIAL AND METHODS

Biopsies were harvested and divided into three groups: group 1, systemically and periodontally healthy subjects (n = 10); group 2, systemically healthy subjects with moderate-to-severe chronic periodontitis (probing depth > 6 mm) (n = 20); and group 3, type 2 diabetic subjects with periodontitis (n = 20). Cytokine levels were assessed in the gingival tissues by enzyme-linked immunosorbent assay analysis.

RESULTS

Data analysis demonstrated that the interleukin-1beta, interleukin-6, interleukin-8, and interferon-gamma levels were higher in the presence of periodontal inflammation than in the absence of inflammation, regardless of systemic status. The interleukin-1beta and interleukin-6 levels were higher in diabetic subjects (group 3) than in systemically healthy patients with comparable types of periodontitis (group 2). No difference was observed for the interleukin-8 and interferon-gamma levels between groups 2 and 3.

CONCLUSION

Within the limits of this study, it was concluded that type 2 diabetes was associated with increased expression of interleukin-1beta and interleukin-6 in periodontally inflamed tissues of diabetic patients, relative to nondiabetic subjects, and that such overexpression may be involved in the mechanisms by which type 2 diabetes enhances periodontal destruction.