Immunohistologic and morphometric analysis of cytotoxic T lymphocytes in gingivitis

T cell replicative senescence in human aging

The decline of the immune system appears to be an intractable consequence of aging, leading to increased susceptibility to infections, reduced effectiveness of vaccination and higher incidences of many diseases including osteoporosis and cancer in the elderly. These outcomes can be attributed, at least in part, to a phenomenon known as T cell replicative senescence, a terminal state characterized by dysregulated immune function, loss of the CD28 costimulatory molecule, shortened telomeres and elevated production of proinflammatory cytokines. Senescent CD8 T cells, which accumulate in the elderly, have been shown to frequently bear antigen specificity against cytomegalovirus (CMV), suggesting that this common and persistent infection may drive immune senescence and result in functional and phenotypic changes to the T cell repertoire. Senescent T cells have also been identified in patients with certain cancers, autoimmune diseases and chronic infections, such as HIV. This review discusses the in vivo and in vitro evidence for the contribution of CD8 T cell replicative senescence to a plethora of age-related pathologies and a few possible therapeutic avenues to delay or prevent this differentiative end-state in T cells. The age-associated remodeling of the immune system, through accumulation of senescent T cells has farreaching consequences on the individual and society alike, for the current healthcare system needs to meet the urgent demands of the increasing proportions of the elderly in the US and abroad.

T cell replicative senescence in human aging

The decline of the immune system appears to be an intractable consequence of aging, leading to increased susceptibility to infections, reduced effectiveness of vaccination and higher incidences of many diseases including osteoporosis and cancer in the elderly. These outcomes can be attributed, at least in part, to a phenomenon known as T cell replicative senescence, a terminal state characterized by dysregulated immune function, loss of the CD28 costimulatory molecule, shortened telomeres and elevated production of proinflammatory cytokines. Senescent CD8 T cells, which accumulate in the elderly, have been shown to frequently bear antigen specificity against cytomegalovirus (CMV), suggesting that this common and persistent infection may drive immune senescence and result in functional and phenotypic changes to the T cell repertoire. Senescent T cells have also been identified in patients with certain cancers, autoimmune diseases and chronic infections, such as HIV. This review discusses the in vivo and in vitro evidence for the contribution of CD8 T cell replicative senescence to a plethora of age-related pathologies and a few possible therapeutic avenues to delay or prevent this differentiative end-state in T cells. The age-associated remodeling of the immune system, through accumulation of senescent T cells has farreaching consequences on the individual and society alike, for the current healthcare system needs to meet the urgent demands of the increasing proportions of the elderly in the US and abroad.

Impact of photodynamic therapy on inflammatory cells during human chronic periodontitis

The aim of this study was to evaluate the effects of the photodynamic therapy (PDT) on the inflammatory infiltrate and on the collagen network organization in human advanced chronic periodontitis. Two different drug delivery systems (DDS) were tested (liposomes and nanoemulsions) to determine if the effects of PDT could differ according to the DDS used. Sixteen patients presenting two teeth with chronic advanced periodontitis and important tooth mobility with clinical indication of extraction were included in the group liposomes (group L, n=8) or in the group nanoemulsions (group N, n=8) in order to compare the effects of each DDS. Seven days before extractions one tooth of each patient was treated with PDT using phthalocyanine derivatives as photosensitizers and the contralateral tooth was taken as control. In group L the density of gingival collagen fibers (66±19%) was significantly increased (p<0.02) when compared to controls (35±21%). Concerning the antigen-presenting cells, PDT had differential effects depending on the drug delivery system; the number of macrophages was significantly decreased (p<0.05) in group L while the number of Langerhans cells was significantly decreased in group N (p<0.02). These findings demonstrate that PDT presents an impact on gingival inflammatory phenomenon during chronic periodontitis and leads to a specific decrease of antigen-presenting cells populations according to the drug delivery system used.

Immunohistochemical evaluation of the inflammatory response in periodontal disease

In order to contribute to the knowledge of the pathogenesis of periodontal disease, an immunohistochemical analysis of the density of inflammatory mononucleated cells and the number of dendritic cells was performed using anti-CD4, anti-CD20, anti-CD25, anti-CD68 and anti-protein S-100 antibodies in 17 cases of chronic gingivitis (CG) and 25 of chronic periodontitis (CP). The CD4+ and CD68+ cells exhibited a diffuse distribution in the connective tissue. CD20+ cell distribution was predominantly in groups and the CD25+ cells exhibited a diffuse or focal distribution. The S-100+ cells were identified in the epithelium and the lamina propria, exhibiting distinct morphology and number. The statistical analysis showed no significant differences (p>0.05) between CG and CP regarding the density of the CD4+ and CD20+ cells and the number of S-100+ cells. However, significant differences (p<0.05) were found between the groups in the density of CD25+ and CD68+ cells . The density of macrophages was greater in CG and the level of cellular activation of the lymphocyte infiltrate was greater in CP. No differences were detected between the aforementioned conditions regarding the density of the T and B lymphocytes and to the number of the dendritic cells.

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.

Langerhans cells express matrix metalloproteinases 9 and 2 and tissue inhibitors of metalloproteinases 1 and 2 in healthy human gingival tissue and in periodontitis

BACKGROUND

As antigen-presenting cells, Langerhans cells may play an important role in the initiation and maintenance of periodontal disease. This study is the first report that extends our knowledge of the expression of matrix metalloproteinases and their endogenous tissue inhibitors by Langerhans cells in healthy and diseased gingival tissues.

METHODS

Single and double immunolabeling procedures were carried out using monoclonal antibodies against CD1a, matrix metalloproteinases 2 and 9, and tissue inhibitors of matrix metalloproteinases 1 and 2, and analyzed by conventional and confocal microscopes.

RESULTS

Langerhans cells expressed matrix metalloproteinases 2 and 9, and tissue inhibitors of matrix metalloproteinases 1 and 2 in healthy and diseased gingival tissues. The tissue inhibitors of matrix metalloproteinase-positive Langerhans cells were mainly observed in the upper epithelial layers. Matrix metalloproteinase 9-positive Langerhans cells were observed especially during periodontitis and in the basal epithelial layer or crossing the basement membrane.

CONCLUSION

During periodontal disease, changes in the expression of matrix metalloproteinases and their tissue inhibitors by gingival Langerhans cells could be implicated in the migration of the cells towards the connective tissue.

The role of acquired immunity and periodontal disease progression

Our understanding of the pathogenesis in human periodontal diseases is limited by the lack of specific and sensitive tools or models to study the complex microbial challenges and their interactions with the host's immune system. Recent advances in cellular and molecular biology research have demonstrated the importance of the acquired immune system not only in fighting the virulent periodontal pathogens but also in protecting the host from developing further devastating conditions in periodontal infections. The use of genetic knockout and immunodeficient mouse strains has shown that the acquired immune response-in particular, CD4+ T-cells-plays a pivotal role in controlling the ongoing infection, the immune/inflammatory responses, and the subsequent host's tissue destruction. In particular, studies of the pathogen-specific CD4+ T-cell-mediated immunity have clarified the roles of: (i) the relative diverse immune repertoire involved in periodontal pathogenesis, (ii) the contribution of pathogen-associated Th1-Th2 cytokine expressions in periodontal disease progression, and (iii) micro-organism-triggered periodontal CD4+ T-cell-mediated osteoclastogenic factor, 'RANK-L', which is linked to the induction of alveolar bone destruction in situ. The present review will focus on some recent advances in the acquired immune responses involving B-cells, CD8+ T-cells, and CD4+ T-cells in the context of periodontal disease progression. New approaches will further facilitate our understanding of their underlying molecular mechanisms that may lead to the development of new treatment modalities for periodontal diseases and their associated complications.

Neutrophil proteinase 3-mediated induction of bioactive IL-18 secretion by human oral epithelial cells

IL-18, a potent IFN-gamma-inducing cytokine, is expressed by various nonimmune cells as well as macrophages, suggesting that it has important physiological and immunological roles. The present study focused on the mechanism of active IL-18 induction from human oral epithelial cells. The epithelial cells and the cell lines constitutively express IL-18 mRNA and the 24-kDa precursor form of IL-18. Bioactive IL-18 exhibiting IFN-gamma-inducing activity was detected in the supernatant of the cells on costimulation with neutrophil proteinase 3 (PR3) and LPS for 24 h after IFN-gamma-priming for 3 days. An active 18-kDa form of IL-18 was detected in lysate and supernatant of the cells only after the above treatment and the induction was inhibited by cycloheximide and by serine proteinase inhibitors. After the treatment, lactate dehydrogenase activity was not detected in the cell culture supernatant, and PR3 was detected only in the membrane and not in cytoplasm fractions of the cells. Caspase-1 was not detected in the cells even after the treatment and the IL-18 induction was not inhibited by a caspase-1 inhibitor. These results suggest that the PR3-mediated induction of bioactive IL-18 secretion from oral epithelial cells in combination with LPS after IFN-gamma-priming occurred via a caspase-1-independent pathway, and provide new insight into the possible involvement of a neutrophil proteinase in the induction of bioactive IL-18 in oral inflammation such as periodontitis.

Quantitative morphological analysis of Langerhans cells in healthy and diseased human gingiva

Langerhans cells (LC) are implicated in the initiation and maintenance of inflammatory periodontal diseases. The purpose of this immunohistological study using morphometric and automated image analysis was to determine the morphological features of CD1a+ LC in healthy and inflammatory gingiva according to their localisation in the upper epithelium or the basal layer. The study was on gingival samples from 11 healthy controls (C), eight patients with gingivitis (G) and 12 patients with severe chronic adult periodontitis (P). The results show that in the basal layer of all experimental groups, the perimeter, surface and equivalent diameter of CD1a+ LC were significantly decreased (P<0.005) when compared with those in the upper epithelium of the same group. Furthermore, CD1a+ LC had become more rounded, reflected by a significant increase in form factor (P<0.005), when located close to the epithelial basal membrane. In the upper epithelium of group P, the perimeter, surface and equivalent diameter of CD1a+ LC were significantly decreased (P<0. 05) and the form factor significantly increased (P<0.05) when compared with the upper epithelium of group C. This work provides evidence for important morphological variations in CD1a+ LC according to their location within the epithelium and the severity of the periodontal disease. The observed morphological changes may reflect a cellular adaptation during the epithelial transmigration and could eventually be involved in immune stimulation during periodontitis.

Collagen fibers and inflammatory cells in healthy and diseased human gingival tissues: a comparative and quantitative study by immunohistochemistry and automated image analysis

BACKGROUND

Periodontal disease is histologically characterized by the degradation of extracellular matrix components associated with a gingival infiltration of inflammatory cell populations. The purpose of this in situ study was to quantify inflammatory cell subsets and the area fraction (AA%) occupied by collagen fibers in healthy and diseased upper gingival connective tissue in order to investigate the association, if any, between collagen loss and inflammatory cell infiltrate.

METHODS

Paraffin gingival tissue sections from 10 healthy controls (C), 9 patients with gingivitis (G), and 10 patients with severe chronic periodontitis (P) were immunohistochemically stained by antibodies against CD45, CD3, CD8, CD20, CD68, TIA-1, and GrB molecules, and the collagen fibers were stained using sirius red F3Ba. The quantitative evaluations of inflammatory cell numbers and the AA% occupied by collagen fibers were performed by morphometric and automated image analysis.

RESULTS

In group P, CD45+, CD20+, CD68+, TIA-1+, and GrB+ cell numbers were significantly increased (P<0.05) when compared to both C and G groups. The present study revealed significant differences (P <0.01) between means of AA% observed in group C (63%), group G (46%), and group P (26%), and AA% of group G and group P was inversely correlated with the numbers of TIA-1+ cells (P<0.01) and GrB+ cells (P<0.01 and P<0.05, respectively).

CONCLUSIONS

This study showed great differences in the number of the distinct inflammatory cell subsets according to the severity of the periodontal disease and suggested that activated cytotoxic cells could play a pivotal role in the loss of collagen fibers observed during these pathological states. During periodontitis, collagen loss was significantly correlated with all inflammatory cell subset numbers. Finally, the quantitative evaluation of the area fraction occupied by gingival collagen fibers may reflect the clinical severity of the periodontal disease.

Immunohistological and morphometric analysis of intra-epithelial lymphocytes and Langerhans cells in healthy and diseased human gingival tissues

Periodontal diseases are histologically characterized by an infiltration of several inflammatory cell populations into the gingival epithelium and connective tissue, associated with degradation of extracellular matrix components. The purpose of this in situ study was to evaluate the inflammatory state of gingival tissues by the number of intra-epithelial lymphocyte (IEL) subsets and the area fraction (AA%) occupied by collagen fibres in the upper gingival connective tissue, and also to evaluate the number of CD1a+ Langerhans cells (LC) in order to show correlation(s), if any, between these histological findings. The gingival samples were from 10 clinically healthy controls (group C), 8 patients with gingivitis (group G) and 9 with chronic adult periodontitis (group P). A quantitative evaluation of the number of cell populations (CD1a+, CD45RB+, CD3+, CD8+, CD20+, TIA-1+ and GrB+ cells) and the area fraction (AA%) occupied by collagen fibres in the upper gingival connective tissue was made by morphometric and automated image analysis. The results showed that, compared with group C, all IEL subset numbers were significantly increased (p<0.05) in G and P groups, CD20+ excepted. In addition, there was a significant increase in the cytotoxic TIA-1+ IEL number (p<0.05) in group P when compared with group G. The study also showed a significant decrease in the number of CD1a+ LC in groups G and P (p<0.02 and p<0.001, respectively) when compared with group C. No significant difference was found in CD1a+ LC number between groups G and P. The determination of coefficients of correlation (r) with data obtained for each patient showed that in group G, CD1a+ LC number was significantly correlated with CD45RB+ (p<0.05) and CD3+ (p<0.01) IEL numbers whereas during periodontitis, CD1a+ LC number was significantly and inversely correlated with CD20+ (p<0.01), cytotoxic TIA-1+ (p<0.01) and with activated cytotoxic GrB+ (p<0.01) IEL numbers. Moreover, in group P a significant (p<0.05) positive correlation was shown between CD1a+ LC number and the AA% occupied by collagen fibres. This work demonstrates a decrease in CD1a+ LC number according to the severity of the periodontal disease estimated by the number of IEL and by the area fraction occupied by collagen fibres in human gingiva. The decrease of such cells could represent a way to avoid immune overstimulation.