Lymphocytes from chronically inflamed human gingiva. II. Immunoglobulin production in vitro

Cytokine profiles of cells extracted from humans with periodontal diseases

FACS analysis was used to determine the percent interferon (IFN)-gamma-, interleukin (IL)-4-, IL-10-, and CD30-positive T-cells extracted from adult periodontitis (AP) and healthy/gingivitis (H/G) subjects. Additionally, the percentages of IL-1 beta-, IL-10- and IL-12-producing B-cells and macrophages were ascertained. The percent IL-10+ CD8 cells extracted from AP lesions was decreased compared with H/G tissues (p = 0.033), and the percent CD30+ CD4 (p = 0.001) and CD30+ CD8 (p = 0.028) cells was higher in AP than in H/G tissues. The percentages of IL-1 beta + macrophages (p = 0.003) and IL-12+ B-cells (p = 0.034) were both higher in AP lesions than in H/G tissues. The specific effect of Porphyromonas gingivalis on the cytokine profiles of peripheral blood mononuclear cells isolated from P. gingivalis-infected AP and H/G patients was also determined. While there were no significant differences in the percent cytokine-positive T-cells after stimulation with P. gingivalis outer membrane antigens (OM) for 6 days compared with cells incubated in medium only, the percent CD30+ CD4 cells increased significantly (p = 0.047 and p = 0.063 for AP and H/G groups, respectively). There was also an increase in the percent IL-1 beta + B-cells from AP patients (p = 0.029), and the percent IL-12+ monocytes from AP and H/G subjects was higher than the percent IL-12+ B-cells, both after stimulation with P. gingivalis OM (p = 0.005 for the AP group and p = 0.058 and therefore not quite significant for the H/G group) and when incubated in medium alone (p = 0.016 and p = 0.015 for AP and H/G groups, respectively). This study has shown that IL-10+ CD8 cells may be significant in gingival lesions, and that CD30+ T-cells indicative of Th2 or Th0 cells may play a role in progressive periodontal disease. This study has also shown that B-cells produce IL-1 in the gingival lesion and that P. gingivalis may be significant in the induction of B-cell-induced IL-1.

Expression of receptor beta-chain variable region by T cells in human periodontal disease

T cells play a major part in the immune response in periodontal diseases. In order to determine any selective T-cell receptor (TCR) beta-chain variable region (V beta) usage in the infiltrates of healthy/ gingivitis (H/G) and adult periodontitis (AP), cells were extracted from gingival biopsies, the CD4 and CD8 cells stained with antibodies to eight V beta regions, and two-colour flow cytometry used to analyse the data. The frequencies of CD4 and CD8 cells expressing each of the TCR-V beta families varied from 0 to 46% between individuals. A high percentage of CD4 and CD8 cells expressed the V beta 13 family in several AP biopsies, but, in a number of H/G tissues, a high percentage of T cells expressed up to three families including the V beta 13 region, these varying from individual to individual. The mean results showed a significantly greater percentage of V beta 5.2-3-positive CD4 cells (p = 0.003) and V beta 5.1- and 5.2-3-positive CD8 cells (p = 0.003 and 0.025, respectively) isolated from H/G than AP tissues. The percentage of V beta 3.1-positive CD4 cells extracted from H/G tissues was also higher but not quite significant at the 0.05 level (p = 0.051). Sections of gingival tissue in biopsies from H/G and AP were stained in situ; there were no significant differences in the mean expression of V beta 3.1-, 5.1- or 5.2-3-positive cells. A second aim was to determine the effect of Porphyromonas gingivalis on the TCR repertoire. There were no differences in the mean percentage of CD4 or CD8 cells expressing the eight TCR-V beta regions between the two groups after stimulation in vitro with P. gingivalis outer-membrane antigens. There was, however, a trend towards a decrease in the percentage of positive CD4 and CD8 T cells after culture with the antigen. This was significant for CD4 cells from H/G expressing the V beta 5.1 and 5.3 TCRs (p = 0.032 and p = 0.038, respectively). This trend was not evident for V beta 5.2-3-positive CD4 cells or V beta 5.1-positive CD8 cells isolated from both H/G and AP nor for V beta 3.1-positive CD8 cells from AP. The results show that there may be restricted V beta usage in gingival tissues, particularly in H/G tissues. The V beta 5 and 3.1 families may be selected for in the gingival tissues and may also be involved in P. gingivalis activation.

Establishment of peripheral blood and gingival T lymphocyte clones responsive to Porphyromonas gingivalis

T cells are central to the immune response to infection and studies have indicated a local immunoregulatory imbalance may exist in human periodontal disease. Since Porphyromonas gingivalis is generally recognized as a major periodontopathogen, the aim of this study was to establish T cell lines and clones specific to P. gingivalis from the gingival tissues and peripheral blood of P. gingivalis--infected subjects. Two subjects were selected from two groups of individuals (one from each group) established on the basis of P. gingivalis in their plaque and the presence of serum antibodies which react with P. gingivalis antigens. The two groups differed however in their clinical susceptibility (adult periodontitis) or resistance (gingivitis) to periodontal breakdown. The mean ages +/- standard error of the mean of the two groups were 47.9 +/- 2.2 and 49.6 +/- 3.7, respectively, so that resistance in the gingivitis group was related to the age of the subjects. T cell lines and clones were established from the peripheral blood of one patient from each of the two groups and also from the gingival tissues of the same periodontitis subject. This study has demonstrated the capability of establishing P. gingivalis-specific T cell lines and clones from P. gingivalis-infected subjects and FACS analysis of the T cell receptor variable regions demonstrated that the clones were indeed monoclonal. The CD4:CD8 ratios of the peripheral blood-derived T cell lines were 1.2 and 0.4 for the gingivitis-derived line and the periodontitis-derived line, respectively, thus supporting the clinical differences displayed by the two subjects.

Characterization of T lymphocyte clones derived from Porphyromonas gingivalis infected subjects

Porphyromonas gingivalis plays a major role in the pathogenesis of periodontal disease, however some individuals with P. gingivalis infection do not experience periodontal breakdown. The aim of this study was to investigate the proliferative responses of two highly defined groups of subjects and to establish and characterize peripheral blood and gingival cell T cell lines and clones from subjects from these groups. The two groups were selected on the basis of P. gingivalis in their plaque and the presence of serum anti-P. gingivalis antibodies. Both groups therefore were seen to have P. gingivalis and to have responded to it. They however differed only in their clinical susceptibility (adult periodontitis) or resistance (gingivitis) to periodontal breakdown. Dose responses of peripheral blood mononuclear cells extracted from the subjects showed a trend towards a lower response by the adult periodontitis group to P. gingivalis outer membrane (OM) antigens. Peripheral blood T cell lines and clones responsive to P. gingivalis OM were established from a high responding gingivitis subject and a low responding adult periodontitis subject. Gingival T cell lines and clones were also derived from cells extracted from the periodontal tissues of the same periodontitis subject. The majority of T cells in the peripheral blood T cell line from the gingivitis subject were CD4 while those from the adult periodontitis subject were CD8. The gingival T cell line was CD3+ve CD4-ve and CD8-ve. All lines and clones proliferated slowly to P. gingivalis OM but phytohaemagglutinin (PHA) induced an increase in DNA synthesis in those derived from the gingivitis subject with little to no effect on those established from the adult periodontitis subject. Furthermore, PHA inhibited the proliferative response of the CD8 clone derived from the adult periodontitis subject. Phenotypic analysis demonstrated that all the peripheral blood clones expressed the alpha beta TCR while the gingival T cell clones expressed the gamma-delta TCR. All clones had the memory/primed CD45RO+ve phenotype and at least 80% of cells in each clone were HLA-DR+ve. A lower percent of gingival cells expressed CD45RA than the CD4 peripheral blood clones and the two CD8 clones also had a decreased CD45RA expression. The gingival T cell clones also expressed a low percent CD25 as did the CD8 clone derived from the adult periodontitis subject. The results suggest that clones derived from the gingivitis and adult periodontitis subject may be functionally different. The presence of gamma-delta T cells in adult periodontitis remains to be confirmed and their function determined.

Cytokine profiles of Porphyromonas gingivalis-reactive T lymphocyte line and clones derived from P. gingivalis-infected subjects

Porphyromonas gingivalis is generally recognized as a major periodontopathogen such that a study of T cell responses to this organism may help to elucidate immune regulation in periodontal disease.

OBJECTIVE

The aim of this study was to examine interleukin (IL)-4, interferon (IFN)-gamma and IL-10 production by P. gingivalis-responsive T cell lines and clones derived from the peripheral blood of two P. gingivalis-infected subjects with different disease expression and from the gingival tissues of one of the P. gingivalis-infected subjects.

MATERIALS AND METHODS

FACS analysis was used to determine the percentage of T cells staining positive for cytoplasmic IL-4, IFN-gamma and IL-10 and reverse transcriptase polymerase chain reaction (RT-PCR) was performed to determine the presence of mRNA for IL-4 and IFN-gamma in the T cell lines and clones.

RESULTS

FACS analysis showed that virtually all the T cell lines and clones contained IL-4- and IFN-gamma-producing T cells. The RT-PCR results generally supported this trend. However, a higher percentage of cells in the clones derived from one subject produced IL-4 while a lower percentage produced IFN-gamma compared with the clones derived from the other subject. FACS analysis also demonstrated that the lines and clones derived from the two subjects showed differences in IL-10 production.

CONCLUSION

This study has demonstrated that there may be differences in IL-4 and IL-10 production by the P. gingivalis responsive lines and clones derived from P. gingivalis-infected subjects with different disease expression. Any relationship to disease however, remains to be determined.

Cellular adhesion molecules on periodontal lymphocytes

T cell induced differentiation of B cells has been shown to be dependent on the CD2/LFA-3 and LFA-1/ICAM-1 pathways. Flow cytometric analysis was used to examine these adhesion molecules on T and B cells extracted from gingival tissues before and after stimulation with the putative periodontopathic bacteria, Porphyromonas gingivalis and Fusobacterium nucleatum. Adhesion molecule expression on peripheral blood cells from healthy adults was used as a control. Approximately 50 per cent of B cells extracted from gingival tissues expressed LFA-3 and ICAM-1 compared with 30 per cent positive peripheral blood B cells. Around 50 per cent of gingival T cells expressed CD2 relative to 76 per cent positive peripheral blood T cells. However, 40-50 per cent of both gingival and peripheral blood T cells expressed LFA-1. There was no difference in the expression of adhesion molecules on T and B cells extracted from health/marginal gingivitis or adult periodontitis lesions. After stimulation of gingival cells in vitro, the per cent CD2 positive T cells and LFA-3 and ICAM-1 positive B cells remained relatively stable over the six-day culture period, although P. gingivalis and F. nucleatum appeared to induce an increase in the percentage of gingival T cells expressing LFA-1. In contrast to the gingival lymphocytes, stimulation of peripheral blood cells resulted in an increase in the per cent CD2 positive T cells, LFA-3 and ICAM-1 positive B cells, with a decrease in LFA-1 positive T cells. The results therefore demonstrated that gingival T and B cells express adhesion molecules in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin 1, interleukin 6 and transforming growth factor-beta production by human gingival mononuclear cells following stimulation with Porphyromonas gingivalis and Fusobacterium nucleatum

Gingival mononuclear cell production of interleukin 1 (IL-1), interleukin 6 (IL-6) and transforming growth factor-beta (TGF-beta) after stimulation with the putative periodontopathic bacteria, Porphyromonas gingivalis and Fusobacterium nucleatum was investigated. Using an ELISA method, gingival mononuclear cells extracted from 18 adult periodontitis subjects were found to be producing IL-1. However, IL-1 activity could only be detected in 5 out of these 18 cases when tested using a thymocyte proliferation bio-assay, suggesting the presence of IL-1 inhibitors. Depletion of monocytes from peripheral blood cultures resulted in a significant decrease in IL-1 activity following P. gingivalis stimulation while there was no effect in the level of IL-1 activity following stimulation with F. nucleatum. This suggests that P. gingivalis and F. nucleatum stimulate different cell types to produce IL-1. Like IL-1, IL-6 production by gingival mononuclear cells was significantly greater than that produced by the control peripheral blood mononuclear cells. Following P. gingivalis and F. nucleatum stimulation, higher levels of IL-6 could be detected; however, both organisms stimulated similar levels. Intracytoplasmic immunofluorescence staining demonstrated a lower percent TGF-beta+ cells in bacterial stimulated peripheral blood mononuclear cell cultures compared with cells in medium alone. In the gingival mononuclear cell cultures, the percentage TGF-beta+ cells peaked at day 1 in F. nucleatum-stimulated, whereas in P. gingivalis-stimulated cultures the peak TGF-beta+ cells occurred at day 3, again suggesting stimulation of different cell subsets. These results illustrate that different periodontopathic bacteria may stimulate different cell types to produce cytokines which may have synergistic or antagonistic effects.

Different responses in B cells induced by Porphyromonas gingivalis and Fusobacterium nucleatum

A phenotypic study had shown that gingival B cells respond differently to two periodontopathic bacteria, Porphyromonas gingivalis and Fusobacterium nucleatum. Further investigation now shows a reduction in the percentage of Ki-67 + T cells in cultures of gingival and peripheral blood mononuclear cells stimulated with P. gingivalis for 3 and 6 days, respectively, but no suppression of Ki-67 expression in B cells in response to either P. gingivalis or F. nucleatum. Depletion studies of cultures of peripheral blood mononuclear cells showed that in the absence of CD4 cells, the percentage of CD19+ and CD20+ B cells stimulated with P. gingivalis increased after 6 days whereas depletion of CD8 cells resulted in a rise in the percentage of F. nucleatum- and P. gingivalis-stimulated B cells, although this was not significant in the case of P. gingivalis. Specific antibody to P. gingivalis and F. nucleatum was found in culture supernatants of gingival but not of peripheral blood mononuclear cells, indicating a possible higher frequency of antigen-specific B cells in periodontal lesions. IgG was the predominant isotype in both gingival and control peripheral blood cultures, followed closely by IgA in gingival cultures. F. nucleatum stimulated higher levels of Ig in cultures of peripheral blood mononuclear cells than P. gingivalis or cells cultured in medium only, whereas in gingival cell cultures, stimulation by P. gingivalis appeared to result in higher levels of IgG. Also Ig was present at day 3 in gingival cultures, whereas in the blood cell cultures, Ig was only detected at day 6, further suggesting a degree of activation of of gingival B cells.(ABSTRACT TRUNCATED AT 250 WORDS)

CD45RA and CD45RO positive CD4 cells in human peripheral blood and periodontal disease tissue before and after stimulation with periodontopathic bacteria

Flow cytometric analysis was used to examine naive and primed or memory CD4 cells extracted from periodontal lesions compared with cells from peripheral blood of healthy subjects before and after stimulation with the periodontopathic bacteria, Porphyromonas gingivalis and Fusobacterium nucleatum. In peripheral blood, approximately 60% and 40% of CD4 cells were CD45RO+ and CD45RA+ respectively at day 0. Phytohaemagglutinin (PHA) induced CD45RO expression on almost 100% of CD4 cells. However, P. gingivalis and F. nucleatum stimulation did not cause any significant change in percentage of CD45RO+ CD4 cells except for a loss of antigen at day 6 together with re-expression at day 7, which also occurred on cells cultured in medium only. CD45RA expression on PHA and bacterial-stimulated peripheral blood CD4 cells remained fairly stable for the 10-d culture period. Greater than 90% CD4 cells extracted from healthy or marginal gingivitis (H/MG) and adult periodontitis (AP) lesions were CD45RO+ and this was maintained on AP cells throughout the 6-d culture period, except for a small decrease in the percentage of positive cells induced by P. gingivalis at day 3. Approximately 9% CD4 cells from H/MG tissue were CD45RA+, but about 22% AP cells expressed this antigen, and this increased again in P. gingivalis- and F. nucleatum-stimulated cultures after 3 d. Therefore, in peripheral blood P. gingivalis and F. nucleatum do not act as nonspecific T-cell mitogens and, in AP cells, these bacteria induce changes in phenotype, supporting previous data that although they may be polyclonal B-cell activators, they activate antigen specific T-cells.

Autoimmunity to collagen in adult periodontal disease: immunoglobulin classes in sera and tissue

The immunoglobulin class distribution of antibody to human collagen type I has been examined in sera and gingival extracts from patients with adult chronic periodontitis. Tissue extracts were made either by simple washing or ultrasonication. With either method, IgG and IgA antibodies to collagen were present in higher concentration in tissue extracts than in autologous serum when adjustment was made for dilution differences. No significant differences were found for IgM antibodies. Antibodies to human collagen type I are usually "natural antibodies" of the IgM class and, therefore, our findings suggest a class switch to IgG in inflamed gingivae, presumably due to prolonged antigenic stimulation.

Phenotypic analysis of B-cells extracted from human periodontal disease tissue

B-cells extracted from periodontal disease tissue were analyzed for the presence of activation markers using a range of monoclonal antibodies. In adult periodontitis (AP), 6% of B-cells expressed the IL-2 receptor (CD25) compared with 1-2% in peripheral blood and healthy or marginal gingivitis (H/MG) gingival B-cells. There was also an increase in the mean percentage of IgD-positive B-cells and a decrease in CD21 and CD22 expression. In both AP and H/MG lesions, 20-22% of the B-cells expressed CD23 compared with less than 5% in peripheral blood. As B-cells are activated by day 3 in culture and start differentiating into immunoglobulin-secreting cells by day 6, B-cell phenotypes were assayed at these times in this study. Following stimulation with the periodontopathic bacterium Porphyromonas gingivalis, the expression of CD23, CD21 and CD22 on B-cells extracted from AP lesions remained relatively constant over the 6-d culture period. However, with Fusobacterium nucleatum stimulation, there was a significant decrease in CD23, CD21 and CD22 expression after 3 d in culture, which corresponds to the activation time for B-cells. These results show that B-cells extracted from periodontal disease tissue display a range of activation markers and on stimulation, demonstrate differing responses to individual periodontopathic bacteria.

Possible mechanisms involved in the immunoregulation of chronic inflammatory periodontal disease

It is generally agreed that immunological mechanisms are involved in the pathogenesis of periodontal disease; however, regulation of these mechanisms has hitherto received scant attention. Regulatory networks exist at both a cellular and a molecular level. At the cellular level, the existence of helper (T4-positive) and suppressor (T8-positive) T lymphocytes, the expression of Class II major histocompatibility complex antigens, and the heterogeneity of macrophage subpopulations are central to an understanding of the regulatory mechanisms involved. It is only recently that studies of these separate components, in both humans and experimental animals, have begun to provide a basis for understanding the complex interactions occurring in periodontal disease. Studies using the human experimental gingivitis model have shown an immunoregulatory picture consistent with a controlled immunological reaction with an essentially normal T4:T8 ratio of 2.0. In contrast, studies utilizing cells extracted from adult periodontitis lesions have shown a reduced T4:T8 ratio (approximately 1.0) and an inability to respond in, or to stimulate, an autologous mixed lymphocyte reaction. Animal studies using athymic nude rats have supported the concept of a central role for T-cell control in periodontal disease and the possibility of an imbalance in this control with disease progression. These results are reviewed and areas of future research explored.

Gingivitis

Gingivitis is caused by substances derived from microbial plaque accumulating at or near the gingival sulcus; all other suspected local and systemic etiologic factors either enhance plaque accumulation or retention, or enhance the susceptibility of the gingival tissue to microbial attack. Microbial species specifically associated with gingival health include Streptococcus sanguis 1, S. D-7, and Fusobacterium naviforme. Bacteria involved in the etiology of gingivitis include specific species of Streptococcus, Fusobacterium, Actinomyces, Veillonella, and Treponema and possibly Bacteroides, Capnocytophaga, and Eikenella. Microbial colonization and participation is sequential, with the complexity of the associated flora increasing with time. The pathogenesis has been separated into the initial, early, and established stages, each with characteristic features. The initial lesion is an acute inflammation which can be induced experimentally by application of extracts of plaque bacteria to normal gingiva. The early lesion is characterized by a lymphoid cell infiltrate predominated by T lymphocytes, characteristic of lesions seen at sites of cell-mediated hypersensitivity reactions. The early lesion can be induced by application of purified contact antigens to the gingival tissues of previously sensitized animals. As the clinical condition worsens, the established lesion appears, predominated by B lymphocytes and plasma cells. Established lesions may remain stable for indefinite periods of time, they may revert, or they may progress. Periodontal destruction does not result from the conversion of a predominantly T cell to a predominantly B cell lesion as has been suggested, but rather from episodes of acute inflammation. Clinical manifestations of gingivitis are episodic phenomena characterized by discontinuous bursts of acute inflammation. Most lesions are transient or persistent but not progressive. Attachment loss may precede alveolar bone loss and may occur without the manifestations of a concurrent or a precursor gingivitis. On the other hand, the evidence indicates that a portion of gingivitis lesions can and does progress to periodontitis. Gingivitis and the periodontal microflora differ in children and adults. Clinical signs of gingivitis either do not appear as plaque accumulates, or they are greatly delayed in children, and the inflammatory infiltrate consists mostly of T lymphocytes. The conversion to a B cell lesion does not appear to occur. The evidence supports the conclusion that gingivitis is a disease, and that control and prevention is a worthwhile goal and a health benefit.(ABSTRACT TRUNCATED AT 400 WORDS)

The nature of the inflammatory infiltrates in childhood gingivitis, juvenile periodontitis and adult periodontitis: immunocytochemical studies using a monoclonal antibody to HLADr

Routinely fixed and processed gingival biopsies from childhood gingivitis, juvenile periodontitis and chronic adult periodontitis patients have been stained immunocytochemically with a monoclonal anti HLADr antibody to aid in the identification and quantification of cell types in the inflammatory infiltrates. Using immunoperoxidase staining and morphological criteria, 9 cell types were quantified in 30 patients. Lesions in the 3 groups were found to differ widely both in size and composition. In the small childhood gingivitis lesions, most cells were small lymphocytes, over half of which were HLADr positive, whereas in juvenile periodontitis biopsies, well over half the infiltrate was plasma cells. The chronic adult periodontitis samples showed greater variability in composition between these 2 extremes, perhaps reflecting differences in disease activity. These results suggest that, when disease is quiescent, the volume of inflamed gingival connective tissue is small and is dominated by B-small lymphocytes, whilst on activation, the lesion increases in size and much of the B-lymphocyte population is transformed to plasma cells. This view corroborates the results of other workers with regard to juvenile periodontitis, but suggests a different interpretation of the quiescent lesion of childhood gingivitis from that current in the literature.

Interleukin-2 production and bone-resorption activity in vitro by unstimulated lymphocytes extracted from chronically-inflamed human periodontal tissues

Lymphocytes isolated from chronically-inflamed tissues were assessed for their ability to produce lymphokines without further stimulation in vitro. Cells were extracted from tissue obtained from 42 patients undergoing periodontal surgery. Cultures were set up in triplicate and supernatants collected after 48 h were assayed for interleukin-2 (IL-2) or bone-resorptive activity. IL-2 was assayed in the cultured supernatants from 20 patients using a previously-standardized T-cell growth assay, with maximally-stimulated peripheral blood-lymphocytes as a positive control. Bone-resorptive activity (BRA) was assessed in culture supernatants from another 22 patients using an in-vitro mouse-calvaria culture-system in which calcium release was measured with a calcium analyser. IL-2 was detected in 12 out of the 20 unstimulated cultures; BRA was detected in 14 of the 22 unstimulated cultures. There appeared to be no relationship between IL-2 production and BRA and the severity of the disease as assessed by loss of attachment. Nevertheless, it seems that most of the cells extracted from chronically-inflamed tissue were producing lymphokines which may indicate stimulation in vivo prior to cell extraction.

Quantitation of sheep IgG1, IgG2, IgA, IgM and albumin by radioimmunoassay

A solid phase radioimmunoassay procedure for the measurement of immunoglobulins (IgG1, IgG2, IgA and IgM) and albumin in sheep body fluids (serum, intestinal lymph, caudal mediastinal lymph, bile, mammary secretions and intestinal secretions) is described. This method was found to be easy to perform, rapid, sensitive and reproducible. Results obtained were consistent with those previously reported using radial immunodiffusion and nephelometric techniques.