Antigen-presenting cells in human periodontal disease tissues

Comparative analysis of antigen-presenting cells in gingival tissues in healthy and periodontitis patients

AIMS

Microbial flora of dental plaque trigger innate and adaptive immune responses. The function of antigen-presenting cells (APCs) is to bridge the innate and adaptive immune systems. The human immune system contains three main types of APCs: dendritic cells (DC) (Langerhans cells (LCs) and interstitial DCs, IDCs), macrophages and B lymphocytes. In this study, the distribution and density of all APCs in healthy and inflamed human gingival tissue were comparatively analysed.

METHODS

Research was conducted on gingival biopsy specimens obtained from 55 patients and classified in three groups: healthy gingiva (control group, n=10), moderate periodontal disease (PD) (n=21) and severe PD (n=24). For APCs' identification antibodies raised against CD1a (for LCs), S100 protein (for iDCs), CD68 (for macrophages) and CD20 (for B lymphocytes) were used.

RESULTS

Increased density of IDCs, macrophages and B lymphocytes in lamina propria and reduced density of LCs in the gingival epithelium were found in patients with periodontitis. Simultaneously, it was noticed an increased concentration of macrophages and B cells in the gingival epithelium in patients with PD. No statistically significant difference in the distribution and density of APC was found among patients with moderate and advanced periodontitis.

CONCLUSIONS

It was hypothesised that in the periodontitis the role of antigen presentation was largely taken from LCs by the DCs, macrophages and B cells. These APCs are thought to have less protective and tolerogenic potential than LCs and this is a significant reason for alveolar bone destruction in periodontitis.

Immunomodulation—What to Modulate and Why? Potential Immune Targets

Despite over 50 years of research into the immunology of periodontal disease, the precise mechanisms and the role of many cell types remains an enigma. Progress has been limited by the inability to determine disease activity clinically. Understanding the immunopathogenesis of periodontal disease however is fundamental if immunomodulation is to be used as a therapeutic strategy. It is important for the clinician to understand what could be modulated and why. In this context, potential targets include different immune cell populations and their subsets, as well as various cytokines. The aim of this review is to examine the role of the principal immune cell populations and their cytokines in the pathogenesis of periodontal disease and their potential as possible therapeutic targets.

Distribution of Dendritic Cells and Langerhans Cells in Peri-implant Mucosa

Background

Peri-implant diseases leading to the failure of dental implants is concern in the field of dentistry. Difference in immune response around peri-implant tissues with healthy tissue might be responsible for the hidden cause of peri-implant diseases. Hence, in the current study, the dispersion of the dendritic cell (DC) subpopulations and Langerhans cells (LCs) was evaluated in healthy peri-implant mucosa (HPIM) and healthy mucosa (HM) to know the imbalance in immune homeostasis.

Subjects and Methods

A total of 15 nonsmoker participants were selected for the study. First sample of the HM was obtained before the implant placement (Group I) and second sample of peri-implant mucosa was obtained at the time of placement of the gingival former (Group II). Immunochemistry was used to quantify DCs and LCs in the samples.

Statistical Analysis Used

To analyze the distribution of cells in the epithelium and lamina propria, Wilcoxon matched pairs test was used.

Results

Mean numbers of CD1a (LCs) in the epithelium and lamina propria of Group I and Group II were 25.2 ± 6.41 and 27.47 ± 10.26 and 19.27 ± 7.27 and 12.46 ± 3.04, respectively. Mean numbers of factor XIIIa (DCs) in the epithelium and lamina propria in Group I and Group II were 30.37 ± 5.42 and 86.93 ± 13.99 and 50.47 ± 7.27 and 124.33 ± 10.27, respectively. Statistically significant differences in the number of cells in the epithelium and lamina propria of Group I and Group II were noted (P = 0.001 and P = 0.001).

Conclusions

CD1a-positive LCs were more in the epithelium rather than lamina propria in Group II. Higher numbers of factor XIIIa-positive DCs were observed in the lamina propria than epithelium in Group I and II.

Discriminating between Interstitial and Circulating Leukocytes in Tissues of the Murine Oral Mucosa Avoiding Nasal-Associated Lymphoid Tissue Contamination

Periodontitis is a chronic inflammatory response to a microbial biofilm that destroys bone and soft tissues supporting the teeth. Murine models of periodontitis based on Porphyromonas gingivalis (Pg) colonization have shown that extravasation of leukocytes into oral tissue is critical to driving alveolar bone destruction. Identifying interstitial leukocytes is key to understanding the immunopathogenesis of periodontitis. Here, we describe a robust flow cytometry assay based on intravenous FITC-conjugated anti-mouse CD45 mAb that distinguishes interstitial leukocytes in the oral mucosa of mice from those circulating within the vasculature or in post-dissection contaminating blood. Unaccounted circulating leukocytes skewed the relative frequency of B cells and granulocytes and inflated the numbers of all leukocyte cell types. We also describe a dissection technique that avoids contamination of oral mucosal tissues with nasal-associated lymphoid tissues (NALT), a B cell rich organ that can inflate leukocyte numbers at least 10-fold and skew the assessment of interstitial CD4 T cell phenotypes. Unlike circulating CD4 T cells, interstitial CD4 T cells were almost exclusively antigen-experienced cells (CD44^hi). We report for the first time the presence of antigen-experienced Pg-specific CD4 T cells in NALT following oral feeding of mice with Pg. This new combined flow cytometry and dissection approach allows identification of leukocytes infiltrating the connective tissues of the murine oral mucosa and avoids confounding analyses of leukocytes not recruited to inflamed oral mucosal tissues in disease conditions like periodontitis, candidiasis, or sialadenitis.

Immature, but Not Mature, Dendritic Cells Are More Often Present in Aggressive Periodontitis Than Chronic Periodontitis: An Immunohistochemical Study

BACKGROUND

Dendritic cells (DCs) form a key link between innate and adaptive immune responses. The aim of this study is to analyze presence and distribution of immature (im) and mature (m) DCs in gingival tissue samples obtained from patients diagnosed with aggressive periodontitis (AgP), chronic periodontitis (CP), and clinically healthy periodontium (control group).

METHODS

Gingival tissue samples obtained from patients with: 1) AgP (aged <35 years); 2) CP (aged ≥35 years); and 3) control group (aged >18 years) (n = 10 per group) were collected. Two-way analysis of variance and posterior Fisher least significant difference test were used to observe differences between the means of cells positively marked for imDC (S100, CD1a, and CD207) and mDC (CD208) immunomarkers.

RESULTS

imDCs were more numerous in AgP than CP and control groups, being statistically significant only for S100+ cells. Conversely, mDCs were visualized in higher numbers in CP than AgP and control groups (both P <0.05). Considering frequency of immunostained cells, the number of S100+ cells was greater than CD207+ and CD1a+ cells, followed by a lesser number of CD208+ cells, in all groups.

CONCLUSIONS

Considering that the ability of DCs to regulate immunity is dependent on DC maturation, results suggest that predominance of imDCs appears to be involved in AgP pathogenesis, probably due to lack of ability to induce immune cell activation. Further studies are necessary to elucidate the role of DC maturation in regulating immune responses in periodontal disease.

Variability of the dendritic cell response triggered by different serotypes of Aggregatibacter actinomycetemcomitans or Porphyromonas gingivalis is toll-like receptor 2 (TLR2) or TLR4 dependent

BACKGROUND

Different serotypes of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis have been shown to induce differential dendritic cell (DC) responses. This study investigates whether cytokine and CC-chemokine receptor (CCR) production by DCs stimulated with different serotypes of A. actinomycetemcomitans or P. gingivalis is Toll-like receptor 2 (TLR2) and/or TLR4 dependent.

METHODS

DCs were obtained from healthy individuals and primed at a multiplicity of infection (MOI) of 10(2) with different A. actinomycetemcomitans or P. gingivalis serotypes in the presence or absence of anti-TLR2 or anti-TLR4 blocking antibodies. TLR2 and TLR4 expression, CCR5 and CCR6 expression, and interleukin (IL)-1β, IL-10, IL-12, and IL-23 expression and secretion were quantified by flow cytometry, real-time reverse-transcription polymerase chain reaction, and enzyme-linked immunosorbent assay.

RESULTS

When DCs were stimulated with serotype b of A. actinomycetemcomitans or serotype K1 of P. gingivalis, higher levels of TLR2 or TLR4, respectively, were detected compared to DCs stimulated with the other serotypes. Similarly, higher levels of cytokines and CCRs were detected in serotype b- or serotype K1-primed DCs compared to the others, and these increased levels positively correlated with levels of TLR2 or TLR4. When TLR2 signaling was blocked using a specific anti-TLR2 monoclonal antibody, serotype b-induced cytokine and CCR expression was inhibited; when TLR4 signaling was blocked, serotype K1-induced response was inhibited.

CONCLUSIONS

These results demonstrate that the variability of secretion of cytokines and expression of CCRs detected in DCs stimulated with different serotypes of A. actinomycetemcomitans or P. gingivalis is TLR2 or TLR4 dependent, respectively.

Inflammatory and immune pathways in the pathogenesis of periodontal disease

The pathogenesis of periodontitis involves a complex immune/inflammatory cascade that is initiated by the bacteria of the oral biofilm that forms naturally on the teeth. The susceptibility to periodontitis appears to be determined by the host response; specifically, the magnitude of the inflammatory response and the differential activation of immune pathways. The purpose of this review was to delineate our current knowledge of the host response in periodontitis. The role of innate immunity, the failure of acute inflammation to resolve (thus becoming chronic), the cytokine pathways that regulate the activation of acquired immunity and the cells and products of the immune system are considered. New information relating to regulation of both inflammation and the immune response will be reviewed in the context of susceptibility to, and perhaps control of, periodontitis.

[Lymphocyte migration under exposure of homeopathic remedies for periodontal inflammation - a controlled pilot study]

BACKGROUND

Several homeopathic remedies are applied in the treatment of periodontal inflammation. However, little is known about their basic active principles. Therefore, we aimed at investigating the effects of homeopathic drugs in periodontal inflammation by observing lymphocyte migration activity in vitro.

MATERIAL AND METHODS

Lymphocytes from blood samples of 3 periodontitis patients and 3 matched healthy volunteers were extracted and embedded in collagen matrix migration assays together with highly diluted (D12 and C200) aqueous extracts from Mercurius solubilis, Silicea, Sulphur, Tuberculinum, or placebo. Lymphocyte migration and lymphocyte speed were observed in a 60-min time frame. Statistical analysis was performed using univariate statistics and SiZer time series analysis.

RESULTS

While C-dilutions did not reveal clear differences between placebo and substances, strong effects were observed in D-dilutions compared to placebo. The strongest effects were achieved in lymphocytes exposed to Sulfur D12. While most specific effects were observed in Sulphur D12 showing an activating effect on periodontitis patient lymphocytes (mean activity: 11,1% (placebo) vs. 23,8% (verum)), there was no effect in healthy volunteers (25,8% (placebo) vs. 25,6% (verum)). SiZer analysis confirmed this effect to be significant.

CONCLUSION

The basic active principles of highly diluted substances are still a matter of controversial debate. Although conclusions are limited due to low sample size, results from our pilot study might encourage further investigations on the role of highly diluted Sulphur in the treatment of periodontitis. Apart from a reproduction study with Sulphur, other immunological experiments, i.e. the investigation of cell limes via flow cytometry, should be performed to underpin these results.

Interleukin-17 and interleukin-18 levels in different stages of inflammatory periodontal disease

Context:

Chronic periodontitis is an inflammatory condition of the tooth supporting structures. There is increasing evidence that the cytokines interleukin-17 (IL-17) and interleukin-18 (IL-18) play a role in progression of chronic periodontitis.

Aim:

The objective of this study was to compare the levels of the cytokines IL-17 and IL-18 in gingival tissue extracts from individuals with healthy gingiva, chronic gingivitis, and mild chronic periodontitis.

Settings and Design:

The study was performed in a hospital-based population with an experimental design.

Materials and Methods:

A total of 69 individuals (n = 23 per group) were recruited for the study. Group 1 included 23 individuals with healthy gingiva and Group 2 included 23 chronic gingivitis patients and Group 3 included 23 patients with mild chronic periodontitis. Gingival tissues were collected during surgical procedures and levels of IL-17 and IL-18 were determined using enzyme-linked immunosorbent assay.

Statistical Analysis:

Intergroup comparison was done by posthoc Tukey's test.

Results:

The gingival tissue concentration of IL-17 was found to be highest in Group 2 (415.19 ± 76.84 pg/mg) followed by Group 3 (193.77 ± 37.32 pg/mg) and Group 1 (20.49 ± 6.05 pg/mg). Concentrations of IL-18 were significantly higher (P < 0.01) in Group 2 (1479.42 ± 330.33 pg/mg) when compared with Group 1 (385.18 ± 71.26 pg/mg) and Group 3 (330.24 ± 48.56 pg/mg).

Conclusion:

There appears to be considerable variation of IL-17 and IL-18 levels in gingival tissue during periodontal health and disease.

Cellular composition of long-standing gingivitis and periodontitis lesions

BACKGROUND AND OBJECTIVE

Insufficient information on the cellular composition of long-standing gingivitis lesions without signs of attachment loss makes an understanding of differences in cellular composition between "destructive" and "nondestructive" periodontal lesions difficult. The aim of the current study was to analyze differences in cell characteristics between lesions representing long-standing gingivitis and severe periodontitis.

MATERIAL AND METHODS

Two groups of patients were recruited. One group consisted of 36 patients, 33-67 years of age, with severe generalized periodontitis (periodontitis group). The second group consisted of 28 patients, 41-70 years of age, with overt signs of gingival inflammation but no attachment loss (gingivitis group). From each patient a gingival biopsy was obtained from one selected diseased site and prepared for immunohistochemical analysis.

RESULTS

Periodontitis lesions were twice as large and contained significantly larger proportions, numbers and densities of cells positive for CD138 (plasma cells) and CD68 (macrophages) than did gingivitis lesions. The proportion of B cells that expressed the additional CD5 marker (B-1a cells) was significantly larger in periodontitis lesions than in gingivitis lesions. The densities of T cells and B cells did not differ between periodontitis lesions and gingivitis lesions. T cells were not the dominating cell type in gingivitis lesions, as B cells together with their subset plasma cells comprised a larger number and proportion than T cells.

CONCLUSION

Periodontitis lesions at teeth with advanced attachment and bone loss exhibit quantitative and qualitative differences in relation to gingivitis lesions at teeth with no attachment and bone loss. It is suggested that the large number and high density of plasma cells are the hallmarks of advanced periodontitis lesions and the most conspicuous difference in relation to long-standing gingivitis lesions.

Porphyromonas gingivalis lipopolysaccharide weakly activates M1 and M2 polarized mouse macrophages but induces inflammatory cytokines

Porphyromonas gingivalis is associated with chronic periodontitis, an inflammatory disease of the tooth's supporting tissues. Macrophages are important in chronic inflammatory conditions, infiltrating tissue and becoming polarized to an M1 or M2 phenotype. As responses to stimuli differ between these phenotypes, we investigated the effect of P. gingivalis lipopolysaccharide (LPS) on M1 and M2 macrophages. M1 and M2 polarized macrophages were produced from murine bone marrow macrophages (BMMϕ) primed with gamma interferon (IFN-γ) or interleukin-4 (IL-4), respectively, and incubated with a low or high dose of P. gingivalis LPS or control TLR2 and TLR4 ligands. In M1-Mϕ, the high dose of P. gingivalis LPS (10 μg/ml) significantly increased the expression of CD40, CD86, inducible nitric oxide synthase, and nitric oxide secretion. The low dose of P. gingivalis LPS (10 ng/ml) did not induce costimulatory or antibacterial molecules but did increase the secretion of IL-1α, IL-6, IL-12p40, IL-12p70, and tumor necrosis factor alpha (TNF-α). P. gingivalis LPS marginally increased the expression of CD206 and YM-1, but it did enhance arginase expression by M2-Mϕ. Furthermore, the secretion of the chemokines KC, RANTES, eotaxin, and MCP-1 from M1, M2, and nonpolarized Mϕ was enhanced by P. gingivalis LPS. TLR2/4 knockout macrophages combined with the TLR activation assays indicated that TLR2 is the main activating receptor for P. gingivalis LPS and whole cells. In conclusion, although P. gingivalis LPS weakly activated M1-Mϕ or M2-Mϕ compared to control TLR ligands, it induced the secretion of inflammatory cytokines, particularly TNF-α from M1-Mϕ and IL-10 from M2-Mϕ, as well as chemotactic chemokines from polarized macrophages.

Immunophenotypic characterization and distribution of dendritic cells in odontogenic cystic lesions

OBJECTIVE

To analyze the expression and distribution patterns of mature dendritic cells (mDCs) and immature DCs (imDCs) in radicular cysts (RCs), dentigerous cysts (DtCs), and keratocystic odontogenic tumors (KCOTs).

MATERIALS AND METHODS

Forty-nine odontogenic cystic lesions (OCLs) (RCs, n = 20; DtCs, n = 15; KCOTs, n = 14) were assessed using the following markers: S100, CD1a and CD207 for imDCs; and CD83 for mDCs.

RESULTS

Almost all cases were S100, CD1a, and CD207 positive, whereas 63% were CD83 positive. RCs presented greater number of immunostained cells, followed by DtCs, and KCOTs. The number of S100+ cells was greater than both CD1a+ and CD207+ cells (P < 0.001), which showed approximately similar amounts, followed by lower number of CD83+ cells (P < 0.001) in each OCL type. Different from S100+ cells, both CD1a+ and CD207+ cells on the epithelium (P < 0.05) and CD83+ cells on the capsule (P < 0.05) were preferentially observed. In RCs, significant correlation was found between the thickness epithelium with S100+ and CD1a+ cells, and between the degree of inflammation with CD83+ cells.

CONCLUSIONS

Dendritic cell populations in OCLs can be phenotypically heterogeneous, and it could represent distinct lineages and/or functional stages. It is suggested that besides DC-mediated immune cell interactions, DC-mediated tissue differentiation and maintenance in OCLs should also be considered.

Immunohistological analysis of CD1a langerhans cells and CD57 natural killer cells in healthy and diseased human gingival tissue: A comparative study

Background:

Cell interaction between dendritic cells (DC) and natural killer (NK) cells in the periodontal milieu is not yet fully known, although these cells are individually known to contribute to the pathogenesis of periodontal disease.

Materials and Methods:

Fifty subjects (25 males and 25 females) were included in the study. The subjects were divided into three groups: Group A comprised 16 subjects with clinically healthy gingiva; group B 17 subjects with gingivitis; and group C 17 subjects with gingivitis; and group C 17 subjects with moderate periodontitis (PPD ≥ 5 mm and CAL ≥ 3 mm in at least six sites). Gingival samples were collected and immunohistochemical study was done using CD57 and CD1a antibody. Statistical analysis was done using analysis of variance (ANOVA), followed by Tukey-Kramer multiple comparison for CD1a and Tukey's highly significant difference (HSD) test for CD57.

Results and Conclusion:

The study showed an inverse relationship between the CD1a⁺ (langerhans) cells and CD57⁺ (natural killer) cells. There was a significant increase in CD57⁺ cells and reduction in CD1a levels as periodontal disease progressed. The significant reduction in CD1a levels in periodontal disease when compared to health could possibly be a result of NK cells down regulating it. Reduction in CD1a levels may result in a low inflammatory response subsequently resulting in tissue destruction.

Are peri-implantitis lesions different from periodontitis lesions?

AIM

To compare histopathological characteristics of peri-implantitis and periodontitis lesions.

METHODS

A search was conducted on publications up to July 2010. Studies carried out on human biopsy material and animal experiments were considered.

RESULTS

While comprehensive information exists regarding histopathological characteristics of human periodontitis lesions, few studies evaluated peri-implantitis lesions in human biopsy material. Experimental peri-implantitis lesions were evaluated in 10 studies and three of the studies included comparisons to experimental periodontitis. Human biopsy material: the apical extension of the inflammatory cell infiltrate (ICT) was more pronounced in peri-implantitis than in periodontitis and was in most cases located apical of the pocket epithelium. Plasma cells and lymphocytes dominated among cells in both types of lesions, whereas neutrophil granulocytes and macrophages occurred in larger proportions in peri-implantitis.

EXPERIMENTAL STUDIES

placement of ligatures together with plaque formation resulted in loss of supporting tissues and large ICTs around implants and teeth. Following ligature removal, a "self-limiting" process occurred in the tissues around teeth with a connective tissue capsule that separated the ICT from bone, while in peri-implant tissues the ICT extended to the bone crest.

CONCLUSION

Despite similarities regarding clinical features and aetiology of peri-implantitis and periodontitis, critical histopathological differences exist between the two lesions.

Immunocompetent cells and cytokine expression in the rat periodontal ligament at the initial stage of orthodontic tooth movement

OBJECTIVE

The aim of the present study is to investigate the involvement of immunocompetent cells, pro-inflammatory cytokines and HSP, to evaluate a change of periodontal ligament during the initial stage of orthodontic tooth movement.

DESIGN

In the present study, we investigated the distributional density of immunocompetent cells, the localisation of cytokines, and the expression levels of their mRNA in the periodontal ligament during the initial stage of orthodontic tooth movement, using immunohistochemistry and real-time PCR.

RESULTS

Orthodontic tooth movement led to significant recruitment of OX6(+) cells and ED1(+) cells in the rat PDL. Double-immunofluorescence staining showed that some ED1(+) cells expressed pro-inflammatory factors of IL-1β and TNF-α in the PDL during orthodontic tooth movement. Real-time PCR analysis revealed that the expression levels of IL-1β (Il1b) and TNF-α (Tnf) mRNA gradually increased following its decrease after 1h of orthodontic tooth movement. These findings suggest that ED1(+) cells are involved in the expression of TNF-α and IL-1β and the subsequent regulation of bone resorption on pressure side. HSP27 (Hspb1) mRNA levels were significantly increased as compared with the control at 1h of the initial stage of treatment.

CONCLUSION

ED1(+) cells involved in the expression of TNF-α and IL-1β may play an important role in the initial reaction of the PDL and in the induction of the osteoclastic bone resorption during orthodontic tooth movement.

Cardiovascular disease and the role of oral bacteria

In terms of the pathogenesis of cardiovascular disease (CVD) the focus has traditionally been on dyslipidemia. Over the decades our understanding of the pathogenesis of CVD has increased, and infections, including those caused by oral bacteria, are more likely involved in CVD progression than previously thought. While many studies have now shown an association between periodontal disease and CVD, the mechanisms underpinning this relationship remain unclear. This review gives a brief overview of the host-bacterial interactions in periodontal disease and virulence factors of oral bacteria before discussing the proposed mechanisms by which oral bacterial may facilitate the progression of CVD.

Antigen recognition and presentation in periapical tissues: a role for TLR expressing cells?

Bacteria are the prime cause of periapical diseases and root canal microbiology is a well-researched area of endodontics. Antigen-presenting cells (APCs) are present in periapical lesions of endodontic origin and play a substantial role in recognizing, processing and presenting pathogenic antigens to the adaptive immune system such as an effective and long-lasting immune response is generated against the specific pathogens. Toll-like receptors (TLRs) are germ-line encoded pathogen recognition receptors (PRR) expressed by various APCs which induce their maturation, lead to gene transcription in the nucleus and the production of several pro- and anti-inflammatory cytokines. Thirteen TLRs have been discovered, 10 of which have been identified in humans so far. Preliminary studies of dental pulp tissue have demonstrated various cell types expressing different TLRs in response to commonly encountered microorganisms. However, there is little information available regarding the expression and function of the various TLRs in human periapical lesions. This review discusses the interactions of various APCs in periapical lesions and the possible roles of different TLRs and APCs in pulp/periapical pathogen recognition and presentation to the adaptive immune system in the initiation and sustaining of periapical diseases.

Effect of smoking on Langerhans and dendritic cells in patients with chronic gingivitis

BACKGROUND

Previous literature showed contrasting results regarding dendritic cell (DC) counts in patients with periodontal diseases. Although smoking decreases the number of DCs in the lungs, the effect of smoking on the quantitative distribution of Langerhans cells (LCs) and DCs in patients with chronic gingivitis has not been investigated to our knowledge.

METHODS

Gingival samples were obtained from 30 patients (15 smokers and 15 non-smokers). Immunohistochemical staining was performed to identify CD1a+ immature LCs and CD83+ mature DCs. The inflammatory infiltrate was evaluated and counted. Densities of cells were calculated within the oral epithelium (OE), sulcular epithelium (SE), and lamina propria (LP) for CD1a+ cells and within the LP for CD83+ cells. Results were compared between groups. This study evaluates whether the high number of cigarettes and smoking years affects densities of cells. Correlations among densities of LCs and DCs with densities of inflammatory infiltrate, number of cigarettes, and smoking years were performed.

RESULTS

Densities of inflammatory infiltrate and CD1a+ cells from the SE and LP were significantly lower for smokers than for non-smokers (P <0.05). This result could not be identified for CD1a+ cells from the OE and for CD83+ cells from the LP. The number of cigarettes and smoking years did not affect densities of cells. No statistically significant correlations could be drawn among densities of LCs and DCs and inflammatory infiltrate, number of cigarettes, and smoking years.

CONCLUSION

Smoking proved to affect the quantitative distribution of LCs and DCs in patients with chronic gingivitis.

Sex differences in destructive periodontal disease: exploring the biologic basis

BACKGROUND

Epidemiologic studies provide broad-based evidence that men are at greater risk for developing destructive periodontal disease than women, even after adjusting for behavioral and environmental factors, such as oral hygiene practice and smoking. What requires clarification, however, is whether sex-specific differences in immune function provide a plausible biologic basis for a sexual dimorphism in susceptibility to destructive periodontal disease. This review examines evidence that might provide an underlying biologic basis for a sexual dimorphism in the prevalence and severity of destructive periodontal disease.

METHODS

A narrative review of the literature related to sexual dimorphism in pathogen-mediated inflammatory diseases and immune response was retrieved from searches of computerized databases (MEDLINE, PubMed, and SCOPUS).

RESULTS

Sex steroids exert profound effects on multiple immunologic parameters regulating both the amplification and resolution of inflammation. Strong evidence exists for sexual dimorphisms in immune function, involving both innate and acquired immunity. Injury and infection have been associated with higher levels of inflammatory cytokines, including interleukin-1β and tumor necrosis factor-α, in men than women, paralleling observed sex-specific differences in periodontitis.

CONCLUSION

Differential gene regulation, particularly in sex steroid-responsive genes, may contribute to a sexual dimorphism in susceptibility to destructive periodontal disease.

Rheumatoid arthritis and periodontal disease

The prevalence of periodontal disease has increased two-fold among patients with rheumatoid arthritis (RA) compared to the general population. This increased prevalence is unrelated to secondary Sjögren's syndrome but instead reflects shared pathogenic mechanisms, including an increased prevalence of the shared epitope HLA-DRB1-04; exacerbated T-cell responsiveness with high tissue levels of IL-17; exaggerated B-cell responses, with plasma cells being the predominant cell type found within gingival tissue affected with periodontitis and B cells being twice as numerous as T cells; RANK overexpression; and an increase in the ratio of RANK-L over osteoprotegerin with a high level of RANK-L expression on gingival B cells, most notably those capable of recognizing Porphyromonas gingivalis. Other factors conducive to periodontitis include smoking and infection with the Epstein-Barr virus or cytomegalovirus, which act by promoting the growth of organisms such as P. gingivalis, whose DNA is often found in synovial tissue from RA patients. P. gingivalis produces the enzyme peptidylarginine deiminase that induces citrullination of various autoantigens, and levels of anti-CCP antibodies are considerably higher in RA patients with than without periodontal disease, suggesting that periodontitis may contribute to the pathogenesis of RA. Further support for this hypothesis comes from evidence that other antigens involved in RA, such as HC-gp39, are also present in gingival tissue. TNFα antagonists slow alveolar resorption but may perpetuate infection of periodontal pockets. Therefore, rheumatology patients, including those taking biotherapies, are likely to benefit from increased referral to dental care (e.g., scaling, root planing and, if needed, dental surgery), particularly as periodontitis is also associated with an increased risk of premature atheroma.

Immunological techniques: ELISA, flow cytometry, and immunohistochemistry

Techniques to analyze the host immune response elicited by the presence of oral microorganisms and their products are central to our understanding of the local and systemic effects of oral diseases. This immune response has been extensively investigated for periodontal disease. The local response may result in lesions involving the gingival tissues and depending upon host susceptibility and microbial virulence may lead to local tissue destruction. More recently, however, the importance of the systemic inflammatory and immune response to oral organisms has been recognized. These systemic responses have been associated with an increased risk for cardiovascular disease, diabetes, and preterm low birth weight. A number of techniques are used extensively by researchers investigating humoral and cellular immune responses to oral organisms both in local oral tissues and fluids and systemically in peripheral blood. These are enzyme-linked immunosorbent assay (ELISA) to quantify specific antibody and cytokines in serum, gingival crevicular fluid (GCF), and saliva; characterization of T cells from peripheral blood and gingival tissues using flow cytometry; and immunohistological analysis of the inflammatory cell infiltrate in gingival tissues.

Interstitial and Langerhans' dendritic cells in chronic periodontitis and gingivitis

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

Characteristics of resident dendritic cells in various regions of rat periodontal ligament

In the periodontal ligament (PDL) of normal rat molars, a considerable number of dendritic cells (DCs) are distributed as resident immunocompetent cells. We have hypothesized that the resident type of DCs can alter their morphology and phenotype to adapt to the microenvironment of the PDL. Thus, we have compared the characteristics of DCs in various regions of rat PDL by immunoelectron microscopy and gene expression analysis by means of reverse transcription/polymerase chain reaction. DCs in the periapical region show immature characteristics, i.e., small round profiles and few organelles. In the mesial region, which is the most stable area in the PDL, the density of DCs is the highest. DCs in the furcal region show the characteristics of activated antigen-presenting cells, i.e., CD86(high) expression, electron-dense lysosomes, and cell-to-cell contacts with lymphocytes. When the PDL is bacterially challenged by pulp exposure, the number of CD86+ DCs and contacts with lymphocytes increase in the furcal region. Gene expression analysis for the furcal region has also shown the up-regulation of the major histocompatibility complex class II alpha-chain, CD83, CD86, and the antigen-presenting cell-lectin-like receptor A1. Thus, we have demonstrated heterogeneity in resident DCs. This may be associated with the difference in DCs regarding their state of maturation/activation, which may further reflect microenvironmental differences such as the amount of external antigens.

Epstein-Barr virus (EBV)-infected monocytes facilitate dissemination of EBV within the oral mucosal epithelium

Epstein-Barr virus (EBV) causes hairy leukoplakia (HL), a benign lesion of oral epithelium that occurs primarily in the setting of human immunodeficiency virus (HIV)-associated immunodeficiency. However, the mechanisms of EBV infection of oral epithelium are poorly understood. Analysis of HL tissues shows a small number of EBV-positive intraepithelial macrophages and dendritic/Langerhans cells. To investigate a role for these cells in spreading EBV to epithelial cells, we used tongue and buccal explants infected ex vivo with EBV. We showed that EBV first infects submucosal CD14(+) monocytes, which then migrate into the epithelium and spread virus to oral epithelial cells, initiating productive viral infection within the terminally differentiated spinosum and granulosum layers. Incubation of EBV-infected monocytes and oral explants with antibodies to CCR2 receptor and monocyte chemotactic protein 1 prevented entry of monocytes into the epithelium and inhibited EBV infection of keratinocytes. B lymphocytes played little part in the spread of EBV to keratinocytes in our explant model. However, cocultivation of EBV-infected B lymphocytes with uninfected monocytes in vitro showed that EBV may spread from B lymphocytes to monocytes. Circulating EBV-positive monocytes were detected in most HIV-infected individuals, consistent with a model in which EBV may be spread from B lymphocytes to monocytes, which then enter the epithelium and initiate productive viral infection of keratinocytes.

Toll-like receptor 2-mediated dendritic cell activation by a Porphyromonas gingivalis synthetic lipopeptide

A PG1828 gene-encoded triacylated lipoprotein was previously isolated from a Porphyromonas gingivalis lipopolysaccharide preparation as a Toll-like receptor (TLR) 2 agonist and its lipopeptide derivatives were synthesized based on the chemical structure. In the present study, granulocyte-macrophage colony stimulating factor-differentiated bone marrow-derived dendritic cells (BMDDCs) were stimulated separately with the P. gingivalis synthetic lipopeptide N-palmitoyl-S-[2-pentadecanoyloxy, 3-palmitoyloxy-(2R)-propyl]-l-Cys-Asn-Ser-Gln-Ala-Lys (PGTP2-RL) and its glyceryl stereoisomer (PGTP2-SL). Only PGTP2-RL activated BMDDCs from wild-type mice to secrete tumour necrosis factor-alpha, interleukin (IL)-6, IL-10 and IL-12p40, whilst PGTP2-RL-induced cytokine production was eliminated in TLR2 knockout (-/-) BMDDCs. BMDDCs from wild-type mice but not TLR2-/- mice responded to PGTP2-RL as well as Pam(3)CSK(4) by increasing the expression of maturation markers, including CD80 (B7-1), CD86 (B7-2), CD40, CD275 (B7RP-1/inducible T-cell co-stimulatory ligand) and major histocompatibility complex class II. Taken together, these results indicate that the fatty acid residue at the glycerol position in the P. gingivalis lipopeptide plays a pivotal role in TLR2-mediated dendritic cell activation.

A possible CD1a Langerhans cell-mast cell interaction in chronic hyperplastic candidosis

AIMS

T lymphocyte-antigen-presenting cell (APC) interaction plays a central role in T lymphocyte activation and APC maturation. We therefore studied the CD1a-positive Langerhans cells with respect to receptor activator of nuclear factor kappa B ligand (RANKL)-positive cells in chronic hyperplastic candidosis (CHC).

MATERIALS AND METHODS

Tissue sections of CHC were compared with leukoplakia and healthy oral mucosa using RANKL and CD1a monoclonal antibodies in an avidin-biotin peroxidase complex protocol. Two different antigen-retrieval protocols, pepsin preincubation and Tris-EDTA heat treatment, were used.

RESULTS

CD1a-positive Langerhans cells were in healthy and leukoplakia epithelium found in the middle layer, but in CHC in all layers of the epithelium, at the basement membrane and as mononuclear round cells in the lamina propria. Use of pepsin digestion enabled studies of mast cells and their activation in the form of degranulation of RANKL.

CONCLUSIONS

The numerical, morphological and topographical versatility of the CD1a-positive Langerhans cells in CHC can be clarified by dendritic cell (DC) recruitment into the epithelium. RANK-positive and RANKL-sensitive DCs have ample opportunity to interact with local T lymphocytes. Use of an optimized antigen-retrieval protocol enabled demonstration of an active engagement (degranulation) of mast cells, which represent a rapidly available source of soluble RANKL.

Anti-P. gingivalis response correlates with atherosclerosis

Significant associations between atherosclerosis and both Porphyromonas gingivalis, a major periodontopathogen, and the respiratory pathogen, Chlamydia pneumoniae, have been shown. Many individuals with evidence of atherosclerosis demonstrate seropositivity to these pathogens. The aim of the present study was to examine the atherogenic effect of repeated immunizations with either or both of these agents, and to determine if molecular mimicry of bacterial heat-shock protein (HSP), termed GroEL, and host (h) HSP60 was involved. Atherogenesis was examined in apolipoprotein-E-deficient (-/-) mice following intraperitoneal immunizations with P. gingivalis, C. pneumoniae, P. gingivalis, and C. pneumoniae or vehicle. Lesion area in the proximal aorta and levels of serum antibodies to P. gingivalis, C. pneumoniae, and GroEL were measured. The increased pathogen burden of P. gingivalis, but not of C. pneumoniae, enhanced atherosclerosis. hHSP60 was detected in lesions, and in P. gingivalis-immunized mice, lesion development was correlated with anti-GroEL antibody levels, supporting the involvement of molecular mimicry between GroEL and hHSP60.

Do Langerhans cells behave similarly in elderly and younger patients with chronic periodontitis?

OBJECTIVE

The purpose of this study was to compare the number, the distribution and the expression of markers of maturation of Langerhans cells (LC) in elderly and younger patients with chronic periodontitis in order to evidence the effect of aging on LC in inflammatory gingival tissue.

METHODS

Gingival tissue specimens presenting chronic periodontitis from 8 elderly patients aged >75 (group E) and from 8 younger patients aged 50-60 (considered as controls, group C) were used for immunohistochemistry with monoclonal antibodies against CD45RB (leucocytes), CD1a (LC), markers of LC maturation (DC-LAMP, CD83) and number of immunolabelled cell subsets was evaluated using image analysis.

RESULTS

The difference in the number of CD45RB+ leucocytes in the upper connective tissue between groups was not significant. In group E, the number of CD1a+ LC was significantly decreased (P<0.002) in the epithelium and significantly increased (P<0.0004) in the upper connective tissue. Furthermore, in group E, intraepithelial CD1a+ LC are more often observed in the upper epithelium and their dendritic processes were shorter and less numerous. Concerning the expression of markers of maturation, the numbers of intraepithelial DC-LAMP+ cells and CD83+ cells were significantly increased (P<0.0007 and P<0.02, respectively) in group E.

CONCLUSION

During chronic periodontitis in elderly patients, the decrease in the number of intraepithelial LC and the alteration of dendritic processes could be balanced by a cellular distribution often observed in the upper epithelium associated with changes in cell maturation in response to bacterial elements.

Dendritic cells at the oral mucosal interface

The mucosal lining of the respiratory and digestive systems contains the largest and most complex immune system in the body, but surprisingly little is known of the immune system that serves the oral mucosa. This review focuses on dendritic cells, particularly powerful arbiters of immunity, in response to antigens of microbial or tumor origin, but also of tolerance to self-antigens and commensal microbes. Although first discovered in 1868, the epidermal dendritic Langerhans cells remained enigmatic for over a century, until they were identified as the most peripheral outpost of the immune system. Investigators' ability to isolate, enrich, and culture dendritic cells has led to an explosion in the field. Presented herein is a review of dendritic cell history, ontogeny, function, and phenotype, and the role of different dendritic cell subsets in the oral mucosa and its diseases. Particular emphasis is placed on the mechanisms of recognition and capture of microbes by dendritic cells. Also emphasized is how dendritic cells may regulate immunity/tolerance in response to oral microbes.

Effect of adoptive transfer of antigen-specific B cells on periodontal bone resorption

BACKGROUND AND OBJECTIVES

Host immune responses to periodontal pathogens have been considered to contribute to the alveolar bone destruction in periodontitis. However, the role of B lymphocytes in the pathogenesis of periodontal bone loss is not clear.

METHODS

We examined the effect of adoptive transfer of antigen-specific B cells from rat spleens on experimental periodontal bone resorption. Donor rats were immunized intraperitoneally (i.p.) with formalin-killed Actinobacillus actinomycetemcomitans. Antigen-specific B cells were prepared from splenocytes by first binding CD43(+) cells to Petri dishes coated with anti-CD43 antibody to remove T cells, and non-binding cells were passed through a nylon wool column to deplete accessory cells. The retained cells were then collected and bound to A. actinomycetemcomitans-coated Petri dishes for enrichment of A. actinomycetemcomitans-binding B cells (AAB). A. actinomycetemcomitans non-binding B cells (ANB) and B cells from non-immunized donor rats (NIB) were also collected from these procedures. Each type of B cell was injected into a group of recipient rats that were then orally infected with live A. actinomycetemcomitans.

RESULTS

At termination, the antibody levels to A. actinomycetemcomitans in serum and gingival wash fluids were significantly higher in the recipients transferred with AAB when compared to the recipients transferred with ANB or NIB. A markedly elevated number of antibody-forming cells were observed in the spleens of the recipients transferred with AAB, and these recipient rats also exhibited significantly increased bone resorption when compared to the other groups.

CONCLUSIONS

It is suggested that B cells can contribute to periodontal bone resorption and that antigen-triggering of B cells is required for the bone resorption.

Aspects of adaptive host response in periodontitis

OBJECTIVE

To review host response in periodontitis with respect to cellular composition of lesions, T cell receptor (TCR) gene expression, cytokine profiles of T-helper (Th) cells and autoimmune components.

MATERIAL AND METHODS

The studies included were confined to human material (biopsies, gingival crevicular fluid, blood from subjects with periodontitis).

RESULTS AND CONCLUSIONS

In periodontitis lesions, plasma cells are the most common cell type and represent about 50% of all cells, while B cells comprise about 18%. The proportion of B cells is larger than that of T cells and Th cells occur in larger numbers than T cytotoxic cells. Polymorphonuclear cells and macrophages are found in fractions of less than 5% of all cells. Lesions in aggressive and chronic forms of periodontitis exhibit similar cellular composition. Differences in disease severity, however, may reflect increases in plasma cell and B cell densities. B cells serve as important antigen-presenting cells in periodontitis. The periodontitis lesion expresses a unique TCR gene repertoire that is different from that in blood. The role of superantigens in periodontitis is unclear. There are few studies using comparative designs and unbiased quantitative methods regarding Th-1 and Th-2 cells in periodontitis. The relative dominance of B cells and plasma cells in periodontitis lesions cannot entirely be explained by enhanced Th-2 functions but maybe because of an imbalance between Th-1 and Th-2. Autoimmune reactions are evident in periodontitis lesions. The role of auto-antibodies in the regulation of host response in periodontitis, however, needs to be clarified. Auto-reactive B cells occur in larger proportions in subjects with periodontitis than in healthy controls.

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

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

Relative Proportions of T-Cell Subpopulations and Cytokines That Mediate and Regulate the Adaptive Immune Response in Patients With Aggressive Periodontitis

BACKGROUND

Both the virulence factors of periodontopathic bacteria and the immune response against them have been involved in tissue destruction observed in periodontal disease. Considering the regulatory role of cytokines produced by T cells, the purpose of this study was to compare the CD3+, CD4+, and CD8+ subpopulations of T cells, and to characterize the mRNA of cytokines involved in the adaptive immune response in a group of healthy/gingivitis 1 (HI/G1) individuals and aggressive periodontitis (AgP) patients.

METHODS

The percentages of T-cell subpopulations were analyzed in 10 gingival samples of HI/G1 individuals and 10 gingival samples of AgP patients by immunohistochemistry. The presence of interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-5, IL-10, IL- 13, and transforming growth factor (TGF)-beta was measured by reverse transcription polymerase chain reaction (RT-PCR) of mRNA extracted from complete gingival biopsies.

RESULTS

Significant differences were found in CD3+ and CD4+ cell counts between both groups. The parameters were lower in the gingival biopsies from AgP patients while CD8+ counts were similar in both groups. The cytokine mRNA analysis showed constant expression of IL-2 and IFN-gamma in all cases. The mRNA of IL-5 and IL-10 was present in the majority of HI/G1 (N = 10, N = 9, respectively) but was not in the AgP group (N = 2, N = 1). IL-13 and TGF-beta were only detected in HI/G1 (N = 2, N = 3) and IL-4 was not detected in any of the individuals.

CONCLUSIONS

These results indicate that the role of the CD8+ subpopulation in aggressive periodontitis lesions is limited. On the other hand, cytokines IL-2 and IFN-gamma may not be relevant in the progression of aggressive periodontitis.

Fimbriated Porphyromonas gingivalis is more efficient than fimbria-deficient P. gingivalis in entering human dendritic cells in vitro and induces an inflammatory Th1 effector response

Porphyromonas gingivalis is a fimbriated mucosal pathogen implicated in chronic periodontitis (CP). The fimbriae are required for invasion of the gingival mucosa and for induction of CP in animal models of periodontitis. CP is associated with infection of immature dendritic cells (DCs) by P. gingivalis in situ and with increased numbers of dermal DCs (DDCs) and mature DCs in the lamina propria. The role of fimbriae in gaining entry into human DCs and how this modulates the inflammatory and effector immune responses, however, have not been explored. To address this, we generated monocyte-derived DCs (MDDCs) in vitro which phenotypically and functionally resemble DDCs. We show here that virulent fimbriated P. gingivalis 381, in contrast to its fimbria-deficient mutant, P. gingivalis DPG3, efficiently gains entry to MDDCs in a manner dependent on active cell metabolism and cytoskeletal rearrangement. In addition, uptake of 381, unlike DPG3, induces DCs to undergo maturation, upregulate costimulatory molecules, and secrete inflammation cytokines interleukin-1beta (IL-1beta), IL-6, tumor necrosis factor alpha, IL-10, and IL-12. Moreover, MDDCs pulsed with 381 also stimulated a higher autologous mixed lymphocyte reaction and induced a Th1-type response, with gamma interferon (IFN-gamma) being the main cytokine. Monocytes used as controls demonstrated fimbria-dependent uptake of 381 as well but produced low levels of inflammatory cytokines compared to MDDCs. When MDDCs were pulsed with recombinant fimbrillin of P. gingivalis (10 micro g/ml), maturation of MDDCs was also induced; moreover, matured MDDCs induced proliferation of autologous CD4(+) T cells and release of IFN-gamma. Thus, these results establish the significance of P. gingivalis fimbriae in the uptake of P. gingivalis by MDDCs and in induction of immunostimulatory Th1 responses.

Oral microbial heat-shock proteins and their potential contributions to infections

The oral cavity is a complex ecosystem in which several hundred microbial species normally cohabit harmoniously. However, under certain special conditions, the growth of some micro-organisms with a pathogenic potential is promoted, leading to infections such as dental caries, periodontal disease, and stomatitis. The physiology and pathogenic properties of micro-organisms are influenced by modifications in environmental conditions that lead to the synthesis of specific proteins known as the heat-shock proteins (HSPs). HSPs are families of highly conserved proteins whose main role is to allow micro-organisms to survive under stress conditions. HSPs act as molecular chaperones in the assembly and folding of proteins, and as proteases when damaged or toxic proteins have to be degraded. Several pathological functions have been associated with these proteins. Many HSPs of oral micro-organisms, particularly periodontopathogens, have been identified, and some of their properties-including location, cytotoxicity, and amino acid sequence homology with other HSPs-have been reported. Since these proteins are immunodominant antigens in many human pathogens, studies have recently focused on the potential contributions of HSPs to oral diseases. The cytotoxicity of some bacterial HSPs may contribute to tissue destruction, whereas the presence of common epitopes in host proteins and microbial HSPs may lead to autoimmune responses. Here, we review the current knowledge regarding HSPs produced by oral micro-organisms and discuss their possible contributions to the pathogenesis of oral infections.

Multiple dendritic cell (DC) subpopulations in human gingiva and association of mature DCs with CD4+ T-cells in situ

Gingival epithelium is a site of active trafficking of Langerhans cells (LCs), while the lamina propria in chronic periodontitis (CP) contains CD83+ mature dendritic cells (mDCs) and CD4+ T-cells. The immune cells that contribute to the mDCs, and whether mDCs engage with T-cells in situ, are unclear. Using several immunohistochemical approaches, combined with fluorescence-, light-, and scanning laser confocal-microscopy, we show that, in addition to LCs, the gingiva contains dermal DCs (DDCs) in the lamina propria; moreover, DDCs increase in number during CP. Furthermore, DDCs, LCs, and B-cells co-express CD83 in CP and contribute to the mDC pool. Double-staining for CD83 and CD4 revealed that mDCs associate with clusters of CD4+ T-cells in the lamina propria. Analysis of these data suggests that multiple DC subsets mature in the gingiva and that mature DCs engage in antigen presentation with T-cells in chronic periodontitis.