Macaca fascicularis as a model in which to assess the safety and efficacy of a vaccine for periodontitis

Transcriptomic phases of periodontitis lesions using the nonhuman primate model

We used a nonhuman primate model of ligature-induced periodontitis to identify patterns of gingival transcriptomic after changes demarcating phases of periodontitis lesions (initiation, progression, resolution). A total of 18 adult Macaca mulatta (12-22 years) had ligatures placed (premolar, 1st molar teeth) in all 4 quadrants. Gingival tissue samples were obtained (baseline, 2 weeks, 1 and 3 months during periodontitis and at 5 months resolution). Gene expression was analyzed by microarray [Rhesus Gene 1.0 ST Array (Affymetrix)]. Compared to baseline, a large array of genes were significantly altered at initiation (n = 6049), early progression (n = 4893), and late progression (n = 5078) of disease, with the preponderance being up-regulated. Additionally, 1918 genes were altered in expression with disease resolution, skewed towards down-regulation. Assessment of the genes demonstrated specific profiles of epithelial, bone/connective tissue, apoptosis/autophagy, metabolism, regulatory, immune, and inflammatory responses that were related to health, stages of disease, and tissues with resolved lesions. Unique transcriptomic profiles occured during the kinetics of the periodontitis lesion exacerbation and remission. We delineated phase specific gene expression profiles of the disease lesion. Detection of these gene products in gingival crevicular fluid samples from human disease may contribute to a better understanding of the biological dynamics of the disease to improve patient management.

Oral microbiome interactions with gingival gene expression patterns for apoptosis, autophagy and hypoxia pathways in progressing periodontitis

Oral mucosal tissues must react with and respond to microbes comprising the oral microbiome ecology. This study examined the interaction of the microbiome with transcriptomic footprints of apoptosis, autophagy and hypoxia pathways during periodontitis. Adult Macaca mulatta (n = 18; 12-23 years of age) exhibiting a healthy periodontium at baseline were used to induce progressing periodontitis through ligature placement around premolar/molar teeth. Gingival tissue samples collected at baseline, 0·5, 1 and 3 months of disease and at 5 months for disease resolution were analysed via microarray. Bacterial samples were collected at identical sites to the host tissues and analysed using MiSeq. Significant changes in apoptosis and hypoxia gene expression occurred with initiation of disease, while autophagy gene changes generally emerged later in disease progression samples. These interlinked pathways contributing to cellular homeostasis showed significant correlations between altered gene expression profiles in apoptosis, autophagy and hypoxia with groups of genes correlated in different directions across health and disease samples. Bacterial complexes were identified that correlated significantly with profiles of host genes in health, disease and resolution for each pathway. These relationships were more robust in health and resolution samples, with less bacterial complex diversity during disease. Using these pathways as cellular responses to stress in the local periodontal environment, the data are consistent with the concept of dysbiosis at the functional genomics level. It appears that the same bacteria in a healthy microbiome may be interfacing with host cells differently than in a disease lesion site and contributing to the tissue destructive processes.

A Pre-Clinical Safety Evaluation of SBP (HBsAg-Binding Protein) Adjuvant for Hepatitis B Vaccine

Although adjuvants are a common component of many vaccines, there are few adjuvants licensed for use in humans due to concerns about their toxic effects. There is a need to develop new and safe adjuvants, because some existing vaccines have low immunogenicity among certain patient groups. In this study, SBP, a hepatitis B surface antigen binding protein that was discovered through screening a human liver cDNA expression library, was introduced into hepatitis B vaccine. A good laboratory practice, non-clinical safety evaluation was performed to identify the side effects of both SBP and SBP-adjuvanted hepatitis B vaccine. The results indicate that SBP could enhance the HBsAg-specific immune response, thus increasing the protection provided by the hepatitis B vaccine. The safety data obtained here warrant further investigation of SBP as a vaccine adjuvant.

Immune system transcriptome in gingival tissues of young nonhuman primates

BACKGROUND AND OBJECTIVE

Young/adolescent humans harbor many microorganisms associated with periodontal disease in adults and show substantial gingival inflammatory responses. However, younger individuals do not demonstrate the soft- and hard-tissue destruction that hallmark periodontitis.

MATERIAL AND METHODS

This study evaluated responses to the oral microbial ecology in gingival tissues from clinically healthy young Macaca mulatta (< 3 years of age) compared with older animals (5-23 years of age). RNA was isolated from the tissues and analyzed for the transcriptome using the Rhesus Macaque GeneChip (Affymetrix).

RESULTS

Global transcriptional profiling of four age groups revealed a subset of 159 genes that were differentially expressed across at least one of the age comparisons. Correlation metrics generated a relevance network abstraction of these genes. Partitioning of the relevance network revealed seven distinct communities comprising functionally related genes associated with host inflammatory and immune responses. A group of genes was identified that were selectively increased/decreased or positively/negatively correlated with gingival profiles in the animals. A principal components analysis created metagenes of expression profiles for classifying the 23 animals.

CONCLUSION

The results provide novel system-level insights into gene-expression differences in gingival tissues from healthy young animals, weighted toward host responses associated with anti-inflammatory biomolecules or those linked with T-cell regulation of responses. The combination of the regulated microenvironment may help to explain the apparent 'resistance' of younger individuals to developing periodontal disease.

Genetic and intervention studies implicating complement C3 as a major target for the treatment of periodontitis

Chronic periodontitis is induced by a dysbiotic microbiota and leads to inflammatory destruction of tooth-supporting connective tissue and bone. The third component of complement, C3, is a point of convergence of distinct complement activation mechanisms, but its involvement in periodontitis was not previously addressed. We investigated this question using two animal species models, namely, C3-deficient or wild-type mice and nonhuman primates (NHPs) locally treated with a potent C3 inhibitor (the compstatin analog Cp40) or an inactive peptide control. In mice, C3 was required for maximal periodontal inflammation and bone loss, and for the sustenance of the dysbiotic microbiota. The effect of C3 on the microbiota was therefore different from that reported for the C5a receptor, which is required for the initial induction of dysbiosis. C3-dependent bone loss was demonstrated in distinct models, including Porphyromonas gingivalis-induced periodontitis, ligature-induced periodontitis, and aging-associated periodontitis. Importantly, local treatment of NHPs with Cp40 inhibited ligature-induced periodontal inflammation and bone loss, which correlated with lower gingival crevicular fluid levels of proinflammatory mediators (e.g., IL-17 and RANKL) and decreased osteoclastogenesis in bone biopsy specimens, as compared with control treatment. To our knowledge, this is the first time, for any disease, that complement inhibition in NHPs was shown to inhibit inflammatory processes that lead to osteoclastogenesis and bone loss. These data strongly support the feasibility of C3-targeted intervention for the treatment of human periodontitis.

Comparative analysis of gingival tissue antigen presentation pathways in ageing and periodontitis

AIM

Gingival tissues of periodontitis lesions contribute to local elevations in mediators, including both specific T cell and antibody immune responses to oral bacterial antigens. Thus, antigen processing and presentation activities must exist in these tissues to link antigen-presenting cells with adaptive immunity. We hypothesized that alterations in the transcriptome of antigen processing and presentation genes occur in ageing gingival tissues and that periodontitis enhances these differences reflecting tissues less capable of immune resistance to oral pathogens.

MATERIALS AND METHODS

Rhesus monkeys (n = 34) from 3 to 23 years of age were examined. A buccal gingival sample from healthy or periodontitis sites was obtained, total RNA isolated, and microarray analysis was used to describe the transcriptome.

RESULTS

The results demonstrated increased transcription of genes related to the MHC class II and negative regulation of NK cells with ageing in healthy gingival tissues. In contrast, both adult and ageing periodontitis tissues showed decreased transcription of genes for MHC class II antigens, coincident with up-regulation of MHC class I-associated genes.

CONCLUSION

These transcriptional changes suggest a response of healthy ageing tissues through the class II pathway (i.e. endocytosed antigens) and altered responses in periodontitis that could reflect host-associated self-antigens or targeting cytosolic intracellular microbial pathogens.

Periodontal disease immunology: 'double indemnity' in protecting the host

During the last two to three decades our understanding of the immunobiology of periodontal disease has increased exponentially, both with respect to the microbial agents triggering the disease process and the molecular mechanisms of the host engagement maintaining homeostasis or leading to collateral tissue damage. These foundational scientific findings have laid the groundwork for translating cell phenotype, receptor engagement, intracellular signaling pathways and effector functions into a 'picture' of the periodontium as the host responds to the 'danger signals' of the microbial ecology to maintain homeostasis or succumb to a disease process. These findings implicate the chronicity of the local response in attempting to manage the microbial challenge, creating a 'Double Indemnity' in some patients that does not 'insure' health for the periodontium. As importantly, in reflecting the title of this volume of Periodontology 2000, this review attempts to inform the community of how the science of periodontal immunology gestated, how continual probing of the biology of the disease has led to an evolution in our knowledge base and how more recent studies in the postgenomic era are revolutionizing our understanding of disease initiation, progression and resolution. Thus, there has been substantial progress in our understanding of the molecular mechanisms of host-bacteria interactions that result in the clinical presentation and outcomes of destructive periodontitis. The science has embarked from observations of variations in responses related to disease expression with a focus for utilization of the responses in diagnosis and therapeutic outcomes, to current investigations using cutting-edge fundamental biological processes to attempt to model the initiation and progression of soft- and hard-tissue destruction of the periodontium. As importantly, the next era in the immunobiology of periodontal disease will need to engage more sophisticated experimental designs for clinical studies to enable robust translation of basic biologic processes that are in action early in the transition from health to disease, those which stimulate microenvironmental changes that select for a more pathogenic microbial ecology and those that represent a rebalancing of the complex host responses and a resolution of inflammatory tissue destruction.

Macaque models of human infectious disease

Macaques have served as models for more than 70 human infectious diseases of diverse etiologies, including a multitude of agents—bacteria, viruses, fungi, parasites, prions. The remarkable diversity of human infectious diseases that have been modeled in the macaque includes global, childhood, and tropical diseases as well as newly emergent, sexually transmitted, oncogenic, degenerative neurologic, potential bioterrorism, and miscellaneous other diseases. Historically, macaques played a major role in establishing the etiology of yellow fever, polio, and prion diseases. With rare exceptions (Chagas disease, bartonellosis), all of the infectious diseases in this review are of Old World origin. Perhaps most surprising is the large number of tropical (16), newly emergent (7), and bioterrorism diseases (9) that have been modeled in macaques. Many of these human diseases (e.g., AIDS, hepatitis E, bartonellosis) are a consequence of zoonotic infection. However, infectious agents of certain diseases, including measles and tuberculosis, can sometimes go both ways, and thus several human pathogens are threats to nonhuman primates including macaques. Through experimental studies in macaques, researchers have gained insight into pathogenic mechanisms and novel treatment and vaccine approaches for many human infectious diseases, most notably acquired immunodeficiency syndrome (AIDS), which is caused by infection with human immunodeficiency virus (HIV). Other infectious agents for which macaques have been a uniquely valuable resource for biomedical research, and particularly vaccinology, include influenza virus, paramyxoviruses, flaviviruses, arenaviruses, hepatitis E virus, papillomavirus, smallpox virus, Mycobacteria, Bacillus anthracis, Helicobacter pylori, Yersinia pestis, and Plasmodium species. This review summarizes the extensive past and present research on macaque models of human infectious disease.

Cellular and humoral systemic and mucosal immune responses stimulated in volunteers by an oral polybacterial immunomodulator "Dentavax"

The oral polybacterial immunomodulator Dentavax (D), composed of killed cells from Klebsiella pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, Candida albicans and Lactobacillus acidophilus and their lysates was created for immunoprophylaxis and therapy of oral mucosa and parodont inflammations. The stimulating effect of the preparation was evaluated in twelve volunteers immunized for 10 consecutive days. On days 7, 14, 21, 28 and 49 after the last immunization peripheral blood (PB) lymphocyte subsets, T lymphocyte activation and PB phagocytic activity, were studied by flow cytometry. PB lymphocyte proliferative responses to PHA, rIL-2, LPS and D were evaluated radiometrically. The production of TNF-alpha in supernatants of in vitro stimulated lymphocytes and specific IgA, IgM and IgG antibodies in serum and saliva was determined by ELISA. Ultrastructural morphologic changes in T and B lymphocyte populations were also investigated. Although no significant changes in the levels of basic lymphocyte subsets were detected, the early/late (CD57+/CD57-) CD8 T effectors ratio was increased at the end of the studied period, as were the percentage of PHA-responding (CD69+) T cells and PB phagocytizing cells. The most prominent lymphoprolipherative responses were measured upon costimulation with LPS+D and PHA+D on day 21. Electron-microscopic studies demonstrated a significant effect of D on both T and B cell activity. TNF-alpha concentration increased progressively from day 7 till the end of the investigation. Maximal concentrations were observed after stimulation with D and LPS. An increased level of specific salivary and serum antibodies against the components of D was found, with highest levels between days 7 and 21. Specific secretory IgA predominated in saliva as compared to IgM and IgG. Our results demonstrate the stimulating effect of Dentavax on PB lymphocyte functional activity and the specific humoral systemic and mucosal immunity.

Immune responses and vaccination against periodontal infections

BACKGROUND

The infectious aetiology of periodontitis is complex and no curative treatment modality exists. Palliative therapy is available.

AIMS

To review the evidence that active or passive immunization against periodontitis provides immune protection.

MATERIAL AND METHODS

PubMed (Medline), the National Institutes of Health, the Food and Drug Administration, and the Center for Disease Control electronic databases were searched to extrapolate information on immune responses to immunization against periodontitis.

RESULTS

Studies in non-human primate models using ligature-induced experimental periodontitis suggest that antibody responses by active immunization against Porphyromonas gingivalis can safely be induced, enhanced, and obtained over time. Immune responses to whole bacterial cell and purified protein preparations considered as vaccine candidates have been evaluated in different animal models demonstrating that there are several valid vaccine candidates. Data suggest that immunization reduces the rate and severity of bone loss. It is also, temporarily, possible to alter the composition of the subgingival microflora. Natural active immunization by therapeutic interventions results in antibody titre enhancement and potentially improves treatment outcomes. Passive immunization of humans using P. gingivalis monoclonal antibodies temporarily prevents colonization of P. gingivalis. Probiotic therapy may be an alternative approach. Regulatory and safety issues for human periodontal vaccine trials must be considered. Shared infectious aetiology between periodontitis and systemic diseases may enhance vaccine effort developments.

CONCLUSIONS

Proof of principle that active and passive immunization can induce protective antibody responses is given. The impact of natural immunization and passive immunization in humans should be explored and may, presently, be more feasible than active immunization studies.

Evaluation of a monovalent companion animal periodontal disease vaccine in an experimental mouse periodontitis model

Periodontal disease in companion animals is clinically similar to that of human periodontal disease. Despite the usage of veterinary procedures and antibiotic therapy, the disease still remains as one of the most highly prevalent disorders seen by veterinarians. The goal of this study was to evaluate the immunogenic properties and vaccine performance of a monovalent canine periodontal disease vaccine in the mouse oral challenge model of periodontitis. Mice vaccinated subcutaneously with inactivated, whole-cell bacterin preparations of Porphyromonas gulae displayed both high titers of anti-P. gulae specific antibodies and significantly reduced alveolar bone loss in response to homologous, heterologous, and cross-species challenge. Based on the results of these studies, a periodontal disease vaccine may be a useful tool in preventing the progression of periodontitis in animals.

Periodontitis in humans and non-human primates: oral-systemic linkage inducing acute phase proteins

BACKGROUND

The acute phase response (APR) represents a systemic counterpart to the localized inflammatory response. This report describes patient-oriented and non-human primate model studies to determine the effect of periodontal disease on systemic acute phase proteins (APP).

METHODS

Patient-oriented studies included comparison of the levels of APP, using enzyme-linked immunosorbent assay (ELISA), with the presence and severity of periodontitis in localized chronic periodontitis (LCP), generalized aggressive periodontitis (GAP), and Sjogren's syndrome (SS) patients. The non-human primate experiments evaluated the serum level of APPs under natural conditions, following mechanical hygiene, experimental gingivitis, and during ligature-induced periodontitis.

RESULTS

Analysis of the LCP population showed what appeared to be a threshold of periodontal disease severity required for elevating the C-reactive protein (CRP) and haptoglobin (HG). The results demonstrated a significant elevation in CRP in the GAP versus the control groups, as well as lower levels of all mediators in healthy non-smokers (HNS) versus smokers (HS), suggesting that these systemic inflammatory markers were altered in response to challenge by noxious materials from smoking. Significantly different levels of CRP, HG, and alpha1-antiproteinase were noted in the SS patients suggesting that the autoimmune aspects of Sjögren's syndrome may impact upon oral health and systemic responses. Parallel evidence was also obtained from the primate studies. Providing mechanical oral hygiene, which significantly lowered clinical inflammation and bleeding of the gingiva, decreased the serum APP levels. Both CRP and fibrinogen were significantly elevated during progressing periodontitis, which also appeared to have an impact on serum lipids and lipoproteins.

CONCLUSIONS

These findings supported results relating chronic oral infections and the inflammation of periodontitis as contributors to and/or triggers for systemic inflammatory responses. Finally, similarities in the clinical and microbiological parameters of gingival inflammation and periodontitis between humans and non-human primates was extended to identification of changes in serum APP in the non-human primates that appeared to be in direct response to the induction of progressing periodontitis. These systemic changes provide additional evidence for the biological plausibility of periodontal infections contributing to various systemic diseases.

A primer of primate pathology: lesions and nonlesions

Nonhuman primates are important laboratory animals for biomedical, pharmacology, and toxicology research. To effectively use primates as models, their gross and histologic anatomy, physiology and natural history, as well as common health problems and the source from which the primate is obtained, must be known and understood by pathologists involved in study design and/or interpretation. The first very important lesson in the "primer" is: there is no such thing as a generic monkey. Brand names (ie, species and subspecies) are important. Several taxonomic groups of primates are used in research including: prosimians, such as galagos and lemurs; New World monkeys, particularily marmosets; Old World monkeys, especially macaques and baboons; and the chimpanzee, an African ape. Differences between taxa are exemplified by the glucocorticoid resistance of New World monkeys compared to Old World monkeys, which results in the requirement for Vitamin D3 and their high circulating levels of steroids such as cortisone and progesterone. Differences in ovarian histology between Old and New World monkeys probably relate to steroid receptor biology as well. There are also variations in disease manifestations, even among closely related primate species such as rhesus and cynomolgus macaques (cynos). For example type D retrovirus infection is accompanied by lymphomas in cynos, but not rhesus. The second important lesson in this "primer" is: "not test article related" does not always mean "normal." Lymphoid nodules in bone marrow or salivary gland, a common background finding in macaques, often signal the presence of type D retrovirus. Other histologic changes and normal anatomic variations may be confusing to individuals not routinely examining primate tissues. The objective of this paper is to familiarize pathologists with the use of primates in research as well as lesions and nonlesions (normal anatomy or physiology) of primates that may influence study design and confound interpretation.

Nonhuman primates: a critical role in current disease research

This review article emphasizes the critical role of nonhuman primates (NHPs) in biomedical research. It focuses on the most recent contributions that NHPs have made to the understanding, treatment, and prevention of important infectious diseases (e.g., acquired immunodeficiency syndrome, hepatitis, malaria) and chronic degenerative disorders of the central nervous system (e.g., Parkinson's and Alzheimer's diseases). The close phylogenetic relation of NHPs to humans not only opens avenues for testing the safety and efficacy of new drugs and vaccines but also offers promise for evaluating the potential of new gene-based treatments for human infectious and genetic diseases.

Immunostimulating and protective effects of an oral polybacterial immunomodulator 'Dentavax' in a rabbit experimental model

The immunostimulating and protective effects of an oral polybacterial immunomodulator, Dentavax (D), composed of killed cells from Klebsiella pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, Candida albicans and Lactobacillus acidophilus and their lysates, have been investigated on an experimental rabbit model. In this model, mixed suspensions of the above bacterial wild strains have been injected in six sides of oral mucosa. A long-lasting inflammation with the development of infiltrates and confluating abscesses has been observed. The influence of orally given Dentavax on the course of the model infection as well as on the dynamics of the immune response has been studied. A two-fold decrease in the duration and severity of inflammatory reaction, confirmed by the histological findings, has been registered. In immunised animals, an activation of polymorphonuclear phagocytosis, together with stimulation of humoral systemic and mucosal immunity with synthesis of specific serum (predominantly, IgG) and coproantibodies (predominantly, S-IgA) determined by ELISA, has been found. The results obtained proved the strong immunostimulating and protective effects of the preparation D, which is meant for the prophylaxis and treatment of inflammatory periodontal diseases.

Porphyromonas gingivalis induction of mediator and cytokine secretion by human gingival fibroblasts

We hypothesized that bacterial viability and strain characteristics of Porphyromonas gingivalis could affect the induction of pro-inflammatory mediator secretion by human gingival fibroblast cultures. Both killed and viable P. gingivalis elicited production of prostaglandin E2, interleukin-1 beta (IL-1 beta), IL-6 and IL-8, although killed P. gingivalis induced generally higher levels, particularly IL-6 and IL-8, compared with the viable bacteria. P. gingivalis strains, which exhibited wild-type levels of trypsin-like protease activity, stimulated human gingival fibroblasts to secrete increased levels of prostaglandin E2 and IL-1 beta, although minimal levels of IL-6 and IL-8 were noted in supernatants from the gingival fibroblast cells. P. gingivalis strains BEI and NG4B19, which have either decreased or undetectable levels of trypsin-like protease, respectively, induced significantly greater IL-6 and IL-8 levels in gingival fibroblast cultures compared with the other strains. The ability of antibody to P. gingivalis to alter human gingival fibroblast production of pro-inflammatory mediators was tested using nonhuman primate antisera. Both immune and nonimmune sera altered the P. gingivalis-generated pattern of mediators from the gingival fibroblasts. We conclude that: (i) viable and killed P. gingivalis were capable of inducing various pro-inflammatory cytokines from human gingival fibroblasts; (ii) strain differences in cytokine induction were noted, and the expression of a trypsin-like protease activity was related to decreased extracellular levels of IL-6 and IL-8; and (iii) the presence of serum, particularly with specific antibody to P. gingivalis, significantly altered human gingival fibroblast cytokine production compared with P. gingivalis alone.

Function of anti-Porphyromonas gingivalis immunoglobulin classes in immunized Macaca fascicularis

We previously reported that Macaca fascicularis immunized with formalin-killed Porphyromonas gingivalis were protected against the bone loss of periodontitis. To examine mechanisms of protection, we determined specific immunoglobulin G (IgG), IgM and IgA titers and opsonic capacities of sera from immunized and control animals. Serum IgG and IgA titers to P. gingivalis appeared early and persisted throughout the 36-week observation period. IgM titers were elevated until 6 to 12 weeks and then decreased through week 36. A significant association was observed between peak IgM titers prior to ligature placement and protection against bone loss (measured at week 30). In control monkeys, no significant IgG, IgA or IgM titers were seen. In sera from immunized animals, significant opsonic capacity was seen by 6-12 weeks and persisted throughout the study. In contrast, control sera showed only low opsonization capacity. Anti P. gingivalis antibody titers in purified IgG, IgA and IgM fractions were determined by enzyme-linked immunosorbent assay, and opsonic activity was demonstrated only in the IgG fraction.

Animal models for Porphyromonas gingivalis-mediated periodontal disease

Porphyromonas gingivalis is one of the principal pathogens in the development of adult periodontitis. Several different animal models have been used to evaluate the complex interactions between P. gingivalis and the host and these have been an important research tool for studying the pathogenesis of P. gingivalis-mediated periodontal diseases.

Evidence for serum immunoglobulin G (IgG) antibody responses in Macaca fascicularis identified by monoclonal antibodies to human IgG subclasses

This investigation determined the capacity of murine monoclonal antibodies directed to human immunoglobulin G (IgG) subclasses to identify molecules with conserved epitopes in the serum of the nonhuman primate, Macaca fascicularis. We subsequently utilized this cross-reactivity to document the characteristics of IgG subclass antibody responses in M. fascicularis to parenteral immunization with intact oral microorganisms, antigens from oral microorganisms, and finally a defined protein toxin, tetanus toxoid. The IgG response in nonhuman primates immunized with tetanus toxoid showed a 40-fold and 110-fold increase after primary and secondary immunizations, respectively. The major IgG subclass responses were IgG1 and IgG3, with little, though significant, responses in the IgG4 and IgG2 subclasses. Seventy-five to 94% of the natural IgG antibody in nonhuman primate sera to Porphyromonas gingivalis, Prevotella intermedia and Campylobacter rectus was IgG1. IgG2 and IgG3 predominated to Bacteroides fragilis, IgG4 to Actinomyces viscosus and an equal distribution among the subclasses was noted in response to Fusobacterium nucleatum. Parenteral immunization of nonhuman primates with intact P. gingivalis elicited primarily IgG3 and IgG4, while the post-immunization IgG response to P. intermedia was largely IgG1. Nonhuman primates were also parenterally immunized with cell envelope antigens of P. gingivalis, P. intermedia, or a combination of cell envelope antigen from C. rectus and F. nucleatum and cell wall antigens of A. viscosus. The greatest IgG antibody response seen post-immunization was reactive with anti-human IgG1 for all of these antigens except to C. rectus which bound nonhuman primate antibody reactive with anti-human IgG2. It appears that the bacteria and their products exhibit unique differences in their induction of serum IgG subclass antibody responses. The characteristics of their immunogenicity as detected by the nonhuman primate may contribute to the ability of the immune responses to effectively interact with these pathogens.

Characteristics of systemic antibody responses of nonhuman primates to cell envelope and cell wall antigens from periodontal pathogens

The immune response of the primate, Macaca fascicularis, to cell envelope (CEA) or cell wall (CWA) antigens of several periodontal pathogens was examined to develop a strategy to interfere with ligature-induced periodontitis. Animals were parenterally immunized with CEA of either Porphyromonas gingivalis, Prevotella intermedia or a combination of CEA/CWA of Campylobacter rectus, Fusobacterium nucleatum and Actinomyces viscosus. Serum samples were taken every 2-4 weeks over a 4-month period, which included a 13-week interval with molar teeth ligated. All of the nonhuman primates in the study exhibited baseline levels of IgG, IgM and IgA antibody to formalinized whole cells of the bacteria. These levels increased significantly following immunization and were elevated above baseline throughout the remainder of the experiment. The largest change in antibody responses was seen in IgA antibody levels of P. gingivalis and C. rectus (42-fold above baseline), IgM antibody to P. intermedia, (41-fold increase) and IgG antibody to F. nucleatum and A. viscosus (32 and 63-fold increases). Moreover, the nonhuman primates exhibited differences in isotype response levels to whole microorganisms compared with the cell envelope antigens. These findings demonstrate the capacity of these nonhuman primates to produce an active immune response to microorganisms chronically colonizing the subgingival microbiota. Additionally, it appears that the bacteria may exhibit some unique differences in their immunogenicity as detected by the nonhuman primate and may contribute to the ability of the immune responses to effectively interact with these pathogens.

Stimulating effect of an oral polybacterial immunomodulator on the proliferative activity of guinea pig lymphocytes

A preparation for the prophylaxis and treatment of inflammations of oral mucosa and parodont Dentavax (D) was investigated in guinea pigs. Animals were given orally D for 5 consecutive days and a month later the procedure was repeated. On day 3, 10, 21, and 28 after immunization and reimmunization lymphoproliferative responses to PHA, rIL-2, LPS and D were measured by the radiometric blast transformation assay in peripheral blood, spleen, mesenteric lymph nodes (MLN) and Peyer's patches (PP). The percentage of cells entering S and G2/M-phases of cell cycle was assessed by the flow cytometric DNA analysis. A correlation in proliferative activity of cells after in vitro stimulation with PHA and LPS has been established by both methods. Peak values of lymphocyte stimulation were found on day 10, especially after the second administration of D in all organs tested, mainly in MLNs and spleen. Electron-microscopic studies demonstrated an extensive development of the endoplasmatic reticulum in plasmatic cells from spleen, PPs, mesenteric, bronchial and inguinal lymph nodes. The results obtained may be considered a proof of the immunostimulating effect of Dentavax.

Shared antigens of Porphyromonas gingivalis and Bacteroides forsythus

Periodontitis in humans is caused by a group of predominantly gram-negative, anaerobic bacteria among which Porphyromonas gingivalis and Bacteroides forsythus are prominent. A similar group is present and presumably plays a similar role in experimental periodontitis in the primate Macaca fascicularis. Nevertheless, immunization using a vaccine containing only killed P. gingivalis suppresses the progress of experimental periodontitis in M. fascicularis. We investigated the hypothesis that gram-negative periodontopathic bacterial may share antigens, and immunization with one species may induce antibodies reactive with other gram-negative species. Using enzyme-linked immunosorbent assay (ELISA), Western and dot immunoblots with nonabsorbed and absorbed and immune and preimmune sera we show that monkeys immunized with P. gingivalis produce antibodies reactive not only with antigens of P. gingivalis but also with those of B. forsythus. Similarly, rabbits immunized with P. gingivalis or with B. forsythus produce antibodies that react with antigens of both bacteria. Cross-reactive antibodies bind to epitopes in lipid A and possibly in core carbohydrate of lipopolysaccharide. Using complexes of lipopolysaccharide with polymyxin B, bovine serum albumin and apolipoprotein A1 specificity of binding was documented. Using sera from monkeys immunized with P. gingivalis, cross-reactivity with Actinobacillus actinomycetemcomitans could not be demonstrated by ELI-SA, although binding to lipopolysaccharide but not to lipid A was demonstrated by Western and dot immunoblots. Antibodies to shared lipopolysaccharide epitopes of periodontopathic bacteria may account, at least in part, for the immune protection observed in immunized monkeys, and shared epitopes may have potential as a vaccine for periodontitis in humans.

Induction of systemic murine B-cell responses by Fusobacterium nucleatum and Porphyromonas gingivalis

The purpose of this study was to examine the antigenic abilities of Fusobacterium nucleatum strain ATCC 25586 and Porphyromonas gingivalis strain W50 black inbred BALB/cABom mice immunized subcutaneously. Furthermore, we aimed to analyze whether the outer membranes (OM) and whole cells (WC) of F. nucleatum or P. gingivalis had an effect on the levels of antibody response and whether a combination of both could either enhance or suppress the B-cell response. A single-cell assay, solid-phase enzyme-linked immunospot (ELISPOT), was used to analyze the splenic B-cell response (immunoglobulin A (IgA), IgG and IgM). Enzyme-linked immunosorbent assay (ELISA) and immunoblotting were used to verify the specific antibody response in the sera. A statistically significant lower level of spontaneous antibody production was observed in the group immunized with P. gingivalis OM compared with groups immunized with F. nucleatum and saline. The specific antibody titers measured by ELISA indicated that the bacterial preparations were able to induce IgG and IgM response. The preparations containing P. gingivalis OM induced higher humoral response than the preparations containing P. gingivalis WC, but for F. nucleatum such a difference was not observed. The prominent proteins revealed had apparent molecular masses of 40 kDa for F. nucleatum and 115, 55-56 and 43 kDa for P. gingivalis; whereas the immunoreactive proteins were 70, 65 and 40 kDa for mice immunized with F. nucleatum and 115, 55-56, 43 and 33-34 kDa for mice immunized with P. gingivalis. Quantitative analysis of B-cell response at the single cell level with ELISPOT revealed that some component(s) of P. gingivalis OM may have a suppressive ability on splenocytes incubated for a short time.

Characteristics of systemic antibody responses of nonhuman primates following active immunization with Porphyromonas gingivalis, Prevotella intermedia and Bacteroides fragilis

Periodontal disease is an infectious disease manifested by the progressive change of a healthy resident commensal microbiota to a pathogenic one characterized by a specific microbiota. Thus, the prospect for the use of selected bacteria or their antigens as a vaccine to interfere with the microbial changes and resulting progression of periodontal tissue destruction has been proposed. As a first step in examining the use of bacterial antigens as immunogens in periodontitis, this study characterized the humoral immune response in Macaca fascicularis after systemic immunization with intact Porphyromonas gingivalis, Prevotella intermedia and Bacteroides fragilis. Parental immunization of the nonhuman primate with the intact bacteria resulted in the production of specific and significantly elevated levels of antibodies to P. gingivalis and P. intermedia, with the predominant isotype being immunoglobulin G (IgG). In contrast, the principal response to the nonoral, intestinal bacterium, B. fragilis, was of the IgM isotype. Immunization increased IgG, IgM, and IgA antibody by 14-227 fold to P. gingivalis and 8-108 fold to P. intermedia. The level of serum IgA antibody increased (77-227 fold). The kinetics of the antibody response post-immunization and post-ligation differed with respect to each of the bacteria tested. IgG antibody to P. gingivalis increased through week 16 of the experiment and remained elevated above baseline through week 32. The IgG antibody level to P. intermedia peaked at 4 weeks following the third immunization and decreased post-ligation to near baseline levels by week 16. Characterization of the immune response after active immunization in the nonhuman primate has demonstrated a substantial and specific increase in antibody response which was sustained for several weeks. The insights obtained from these studies should help optimize the potential for immunologic interference with progressing periodontitis.

Diagnostic strategies of periodontitis based on the molecular mechanisms of periodontal tissue destruction

OBJECTIVE

Periodontitis is a disease showing differences in disease progression between patients and between sites within a patient. Routine clinical examinations today are not useful enough to distinguish susceptible patients and active lesions from resistant patients and chronic lesions. Diagnostic markers should be pathogenic and inflammatory factors participating in periodontal tissue destruction. These are both local and systemic factors.

MATERIALS AND METHODS

First of all, pathogenic factors and proinflammatory cytokines or mediators in gingival crevicular fluid (GCF) were examined and the difference was found between active and inactive periodontitis lesions distinguished by attachment loss. Active lesions were detected by discriminant-function analysis of these examinations, although the sensitivity of differential diagnosis was low. Then, we established a novel needle biopsy for understanding the pathophysiological conditions elicited in active and chronic inflammatory processes of periodontal tissue destruction. A variety of cytokines and mediators were detected in biopsied specimens by reversed transcription polymerase chain reactions (RT-PCR). Cytokine profiles were varied in inflammed periodontal biopsies. As IFN gamma mRNA expression was enhanced in inflamed gingiva, antigen-presenting-cell (APC) functions of human gingival fibroblasts (HGF) were examined.

RESULTS

Despite the phenotypical resemblance of IFN gamma-treated HGF to so-called APC, HLA-DR positive HGF could not induce proliferation but suppressed proliferation of alloreactive peripheral blood T cells (PBT). However, HLA-DR positive HGF stimulated the proliferative responses of PBT which had been primed with allo-APC. Regulatory immune responses by IFN gamma were different in T cell conditions.

CONCLUSIONS

Various kinds of cytokines participated in periodontal inflammation, and every cytokine is multi-functional. Complex and compound inflammatory processes can be clarified by examining cytokine networks and the precise effects of each cytokine on each of the cell types comprising periodontal tissue. It is, therefore, necessary for establishing diagnostic strategies to integrate pathogenic and inflammatory factors in periodontal tissue destruction.

Current concepts in diagnosis and treatment of periodontitis

This article describes some areas of periodontal research and current opinions regarding detection of disease progression, as well as risk indicators and risk factors associated with disease progression. Longitudinal probing of periodontal attachment level is considered the gold standard for detection of disease activity although there are problems with this concept. Digital subtraction radiography can assist in the detection of minor changes of alveolar bone height and density. Risk factors such as composition of subgingival plaque and gingival crevicular fluid, as well as the effect of smoking are discussed. Adjunctive treatment with both antibiotics and nonsteroidal anti-inflammatory drugs, systemic or local, seems to be helpful in some forms of disease. Immunization to prevent colonization of tooth surfaces and pockets by periodontal pathogens does not seem to be feasible in the near future.