Cross-reactive adaptive immune response to oral commensal bacteria results in an induction of receptor activator of nuclear factor-kappaB ligand (RANKL)-dependent periodontal bone resorption in a mouse model.

INTRODUCTION: The present study examined whether induction of an adaptive immune response to orally colonizing non-pathogenic Pasteurella pneumotropica by immunization with the phylogenetically closely related bacterium, Actinobacillus actinomycetemcomitans, can result in periodontal bone loss in mice. METHODS: BALB/c mice harboring P. pneumotropica (P. pneumotropica(+) mice) in the oral cavity or control P. pneumotropica-free mice were immunized with fixed A. actinomycetemcomitans. The animals were sacrificed on day 30, and the following measurements were carried out: (i) serum immunoglobulin G and gingival T-cell responses to A. actinomycetemcomitans and P. pneumotropica; (ii) periodontal bone loss; and (iii) identification of receptor activator of nuclear factor-kappaB ligand (RANKL) -positive T cells in gingival tissue. RESULTS: Immunization with A. actinomycetemcomitans induced a significantly elevated serum immunoglobulin G response to the 29-kDa A. actinomycetemcomitans outer membrane protein (Omp29), which showed strong cross-reactivity with P. pneumotropica OmpA compared to results in the control non-immunized mice. The A. actinomycetemcomitans-immunized P. pneumotropica(+) mice developed remarkable periodontal bone loss in a RANKL-dependent manner, as determined by the abrogation of bone loss by treatment with osteoprotegerin-Fc. The T cells isolated from the gingival tissue of A. actinomycetemcomitans-immunized P. pneumotropica(+) mice showed an in vitro proliferative response to both A. actinomycetemcomitans and P. pneumotropica antigen presentation, as well as production of soluble(s)RANKL in the culture supernatant. Double-color confocal microscopy demonstrated that the frequency of RANKL(+) T cells in the gingival tissue of A. actinomycetemcomitans-immunized P. pneumotropica(+) mice was remarkably elevated compared to control mice. CONCLUSION: The induction of an adaptive immune response to orally colonizing non-pathogenic P. pneumotropica results in RANKL-dependent periodontal bone loss in mice.

Potent stimulation of murine B cells to proliferate and to secrete immunoglobulins by a lipoteichoic acid-like molecule produced by Clostridium botulinum C and D.

Bacterial products have served as important immunological tools to study lymphocyte activation. The lipopolysaccharides of the Gram-negative bacteria are well known to be potent activators of B lymphocytes. Several Gram-positive bacteria produce exotoxins that are superantigens for T cells. In the present study, we demonstrate that the Gram-positive bacteria Clostridium botulinum C and D produce a high molecular weight mitogen (Cb mitogen) that is a potent activator of murine B lymphocytes. The Cb mitogen was discovered as a consequence of our attempt to investigate a possible superantigen activity present in the botulinum exotoxins. We observed initially that mouse spleen cells were strongly stimulated to proliferate by culture supernatants of C. botulinum C and D. However, the characterization of the responding cell ruled out superantigen because only the B lymphocytes were stimulated to proliferate and to secrete immunoglobulins, and they did so independent of T cell help. In addition, the molecular characterization of the Cb mitogen demonstrated that the purified botulinum toxin was devoid of mitogenic activity. In contrast, the fractionation of the culture supernatant of C. botulinum C in an FPLC Superose 12 column indicated that the Cb mitogen was present in the void volume of the column (MW > or = 300 kDa) which had no toxigenic activity. However, the fractions containing molecules of 150 kDa were highly toxic for mice and had no mitogenic activity. The possibility that LPS was present as a contaminant in the Cb mitogen preparations was excluded because spleen cells from the LPS non-responder C3H/HeJ mice responded well to the Cb mitogen, and the antibiotic polymyxin B, which is an inhibitor of LPS, had no effect on the Cb-mitogen activity. However, an anti-lipoteichoic acid monoclonal antibody (3-1 mAb) inhibited to a great extent the proliferation of spleen cells induced by the Cb mitogen but had no effect on the LPS or concanavalin A stimulation of these cells. Moreover, the Cb mitogen was specifically adsorbed and eluted from a protein G Sepharose column to which the anti-lipoteichoic acid 3-1 mAb had been conjugated. These results support the view that lipoteichoic acid is a selective B cell mitogen.

Potent stimulation of murine B cells to proliferate and to secrete immunoglobulins by a lipoteichoic acid-like molecule produced by Clostridium botulinum C and D

Bacterial products have served as important immunological tools to study ly,phocyte activation. The lipopolysaccharides of the Gram-negative bacteria are well known to be potent activators of B lymphocytes. Several Gram-positive bacteria produce exotoxins that are superantigens for T cells. In the present study, we demonstrate that the Gram-positive bacteria Clostridium botulinum C and D produce a high molecular weight mitogen (Cb mitogen) that is a potent activator of murine B lymphocytes. The Cb mitogen was discovered as a consequence of our attempt to investigate a possible superantigen activity present in the botulinum exotoxins. We observed initially that mouse spleen cells were strongly stimulated to proliferate by culture supernatants of C. botulinum C and D. However, the characterization of the responding cell ruled out superantigen because only the B lymphocytes were stimulated to proliferate and to secrete immunoglobulins, and they did so independent of T cell help. In addition, the molecular characterization of the Cb mitogen demonstrated that the purified botulinum toxin was devoid of mitogenic activity. In contrast, the fractionation of the culture supernatant of C. botulinum C in an FPLC Superose 12 column indicated that the Cb mitogen was present in the void volume of the column (MW ò 300 kDa) which had no toxigenic activity. However, the fractions containing molecules of 150 KDa were highly toxic for mice and had no mitogenic activity...

Phenotypic analyses of mononuclear cells recovered from healthy and diseased human periodontal tissues.

Mononuclear cells were recovered from the gingival tissues of normal individuals and from patients with periodontal disease. Lymphocyte phenotypic markers were identified by immunofluorescence after reaction with monoclonal antibodies to T-cell subset markers. The normal tissues exhibited T4/T8 ratios almost identical to those in the peripheral blood. The diseased tissue cell ratios were significantly reduced, in both the adult periodontitis and the juvenile periodontitis groups (P less than 0.01 and P less than 0.02, respectively), indicating alterations in the T-cell subset distribution in these tissues. Each diseased patient showed a much decreased T4/T8 ratio in the gingival lymphocytes when these were compared with the peripheral blood ratio from the same patient. The T4/T8 ratios of the more severe sites were significantly lower than those of the less severe sites in the same disease category. The decreases in subset ratios could be attributed to statistically significant reductions in T4+-lymphocyte recoveries relative to peripheral blood and also to slight relative increases in T8+ lymphocytes. A highly significant (P less than 0.001) correlation between the average probeable periodontal pocket depth and the T4/T8 ratio of each disease category was demonstrated. The relative recoveries of B cells from the various tissues did not differ between diseased and normal tissues. It is suggested that T-cell regulatory expression in gingival tissues is distinct from peripheral blood regulatory expression and that there is a local immunoregulatory imbalance in periodontal disease.

Purification and partial sequence of human osteoclast-activating factor: identity with interleukin 1 beta.

The lymphokine osteoclast-activating factor (OAF) was purified to homogeneity. OAF was produced by human peripheral blood mononuclear cells stimulated with concanavalin A and phorbol myristate acetate under serum-free culture conditions. OAF was purified by sequential gel filtration, ion-exchange, and reverse-phase HPLC by following bone resorptive activity. Homogeneity was indicated by the criteria of a single 17,800-dalton band on silver-stained polyacrylamide gels, a single pI 6.8 band on isoelectric focusing, and a single aminoterminal sequence. Purified OAF stimulated half-maximal release of calcium from fetal rat long bones at a concentration of approximately 0.66 ng/ml. The amino-terminal sequence of OAF was determined and found to be identical to that of interleukin 1 beta. Homogeneous OAF possessed an activity of 8.2 X 10(6) U/mg in the thymocyte proliferation assay. Because the m.w., isoelectric point, amino-terminal sequence, and specific activity in the thymocyte proliferation assay are the same for homogeneous OAF and interleukin 1 beta, we conclude that they are the same molecule, and that interleukin 1 beta is the major protein with OAF activity produced by lectin-stimulated peripheral blood mononuclear cells.

Immune ascites in the guinea pig: specificity of cells and antibody in an induced peritoneal exudate.

Strain 2 guinea pigs, immunized with Lys10-Lys(Dnp) in CFA and repeatedly injected intraperitoneally with adjuvant, developed ascites. The fluid was harvested over 8 months in total amounts up to 2 liters per animal and contained substantial amounts of cells and antibody which reacted with the immunizing antigen and related peptides. The antibody was of the IgG and IgA classes and showed restricted heterogeneity. Among synthetic Dnp-oligopeptides, both the cells, studied by antigen-stimulated thymidine incorporation, and the purified antibody, studied by fluorescence quenching, demonstrated the same specificity for the immunizing antigen as has previously been noted in lymph node cells and in serum antibody. The technique offers a means for studying more cells and more antibody than has previously been possible from individual guinea pigs.

Antigen recognition: the specificity of an isolated T lymphocyte population.

Guinea pig lymph node lymphocytes were separated into T and B cell fractions on immunoabsorbent columns. Separated cells were functionally distinct: T cells proliferated in response to ConA, PHA, soluble and alloantigen, whereas anti-Ig reagents only stimulated B cells. The in vitro proliferative response of guinea pig lymph node T lymphocytes was then shown to be highly discriminating when elicited by a series of structurally similar synthetic DNP-oligolysine antigens. Proliferation was always most extensive in response to the homologous, immunizing antigen, and less intense to cross-reacting DNP-oligolysines. Specificity of proliferation was maintained in the absence of both B lymphocytes and antibody secreting cells, suggesting that T cell recognition is not "acquired" from B cells or secreted antibody, but is a property inherent to the T cell.