Immunologic mechanisms of pathogenesis in periodontal diseases: an assessment

Semaphorin 3A attenuates the hypoxia suppression of osteogenesis in periodontal ligament stem cells

OBJECTIVE AND BACKGROUND

The occurrence and development of periodontitis are closely related to hypoxia of the periodontal microenvironment. Periodontal ligament stem cells (PDLSCs) are considered to have potential to regenerate periodontal tissues. Semaphorin 3A (Sema3A) plays an essential role in promoting osteogenesis. However, the effect of Sema3A on osteogenesis of PDLSCs under hypoxia remains unclear. The aim of this study was to investigate the effect of Sema3A on osteogenesis of PDLSCs under hypoxia.

METHODS

Isolated PDLSCs were identified using flow cytometry. Adipogenic differentiation potential was identified by oil red O staining. Osteogenesis was measured using Alizarin Red S staining and ALP staining. Intracellular hypoxia was induced using cobalt chloride (CoCl₂ ). The expression level of hypoxia-inducible factor-1α (HIF-1α) was detected via ELISA. Expression of osteogenic markers and Sema3A was analyzed using western blot and real-time PCR.

RESULTS

The proliferation and osteogenesis of PDLSCs were markedly inhibited with increased concentrations of CoCl₂ . Under the treatment with a low concentration of CoCl₂ , expression of related osteogenic markers and Sema3A decreased in a time-dependent manner. ARS and ALP staining results also showed that osteogenic calcification decreased under hypoxia. Apigenin, an inhibitor of HIF-1α, effectively up-regulated expression of Sema3A and osteogenic markers with CoCl₂ treatment. Moreover, exogenous Sema3A significantly increased the expression of osteogenesis-related markers and mineralization of PDLSCs according to ALP and ARS staining with CoCl₂ treatment.

CONCLUSIONS

Hypoxia markedly inhibited osteogenesis of PDLSCs. Sema3A explicitly attenuated the hypoxia suppression of osteogenesis in PDLSCs.

Biomarkers of oral inflammation in perinatally HIV-infected and perinatally HIV-exposed, uninfected youth

AIM

To examine oral biomarkers that have been associated with periodontal disease progression in HIV-infected adults in perinatally HIV-infected and HIV-exposed but uninfected youth.

MATERIAL AND METHODS

This was a cross-sectional, multicentre substudy of youth participating in the Oral Health Pediatric HIV/AIDS Cohort study. Gingival crevicular fluid repository samples from participants with and without periodontal disease (using Gingival Index [GI] and Bleeding on Probing [BOP] parameters on dental examination) were tested for concentration levels of inflammatory biomarkers. Associations were assessed using Wilcoxon test and Spearman correlation.

RESULTS

For perinatal HIV youth (n = 129), the markers consistently elevated (p < .05) in sites with GI ≥2 and in sites with BOP were interleukin-1β, 6 and 13, macrophage inflammatory protein-1α and metalloproteinase-9. Serum tumour necrosis factor-α and soluble CD14 were positively correlated with a summary count of elevated cytokines. No associations were seen among HIV-uninfected subjects (n = 71).

CONCLUSIONS

The association of oral biomarkers of inflammation with clinical indicators of periodontal inflammation and systemic immune activation suggests that perinatal HIV-infected youth may be at higher risk for developing significant periodontal disease, associated with tooth loss and HIV progression. More frequent dental care of this group is needed to prevent potential periodontal progression.

Treponema medium Glycoconjugate Inhibits Activation of Human Gingival Fibroblasts Stimulated with Phenol-Water Extracts of Periodontopathic Bacteria

Oral treponemes are well-known as causative agents of periodontal diseases; however, the details have not been fully clarified. Here, we examined the effects of Treponema medium glycoconjugate on the activation of human gingival fibroblasts using phenol-water extracts from Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum subsp. nucleatum, and Actinobacillus actinomycetemcomitans. The phenol-water extracts activated human gingival fibroblasts to mediate IL-8 production, as well as IL-8 mRNA expression, phosphorylation of p38 mitogen-activated protein kinase, and expression of intercellular adhesion molecule-1. T. medium glycoconjugate exhibited no activation of human gingival fibroblasts, while phenol-water extract-induced activation of human gingival fibroblasts was clearly inhibited by T. medium glycoconjugate. Furthermore, binding of biotinylated phenol-water extracts to CD14 in the presence of LPS-binding protein was blocked with T. medium glycoconjugate. These results suggest that T. medium glycoconjugate has an inhibitory effect on host cell activation by periodontopathic bacteria caused by binding to CD14- and LPS-binding protein.

Comparative Evaluation of Clinical, Hematological and Systemic Inflammatory Markers in Smokers and Non-Smokers with Chronic Periodontitis

Context:

Systemic conditions, especially chronic infections, have a direct impact on the general health and well-being of an individual. Similarly, the long-standing inflammatory changes seen during periodontitis have been associated with the altered diabetic control, preterm, low birth weight infants, and cardiovascular disease. Being a low-grade infection, the signs may not be as severe as seen in other systemic conditions, but they definitely cannot be ignored.

Aims:

The present study was designed to compare clinical, hematological, and systemic inflammatory markers in patients with chronic periodontitis.

Subjects and Methods:

A total of 90 chronic periodontitis patients were selected for the present study from the outpatient department of the Department of Periodontology, and the various clinical and hematological parameters were then assessed.

Statistical Analysis Used:

Z-test was used to compare the probing depth, clinical attachment loss, hematological parameter, and interleukin-6 values between Group A and Group B. Mann–Whitney U-test was used to compare gingival index, plaque index, and bleeding on probing between Group A and Group B.

Results:

The results of the study were based on the comparison of the clinical, hematological, and systemic inflammatory markers in smokers and nonsmokers with chronic periodontitis and came out to be statistically highly significant.

Conclusions:

With the resurgence of emphasis on significance of oral diseases related to systemic health, the medical professionals also need to familiarize themselves with the oral cavity and the oral-systemic inter-relationships to treat or reduce the morbidity of the underlying medical condition. Furthermore, the oral health care professionals must reach out to the medical community and the general public to improve patient care through education and communication about the oral health-systemic health link.

Serum ferritin level and red blood cell parameters in healthy controls and chronic periodontitis patients

Periodontitis, which is a chronic inflammatory disease causes reduction in the number of erythrocytes and hemoglobin. It is found to be caused by specific pathogenic subgingival plaque bacteria. Periodontitis is host mediated through release of pro inflammatory cytokines by local tissues and immune cells in response to bacterial flora and its products, especially lipopolysacharides. Periodontitis is found to have systemic effect and the cytokines produced inhibit proliferation and differentiation of erythrocytes leading to anaemia. This study evaluate level of hemoglobin erythrocytes, hematocrit and serum ferritin levels in healthy subjects and periodontitis patient.

Relationship between chemokines and dendritic cells in human chronic periodontitis

BACKGROUND

The purpose of this study was to evaluate the relationship between chemokines and dendritic cells (DCs) in human chronic periodontitis (CP).

METHODS

Gingival samples were obtained from 23 individuals with CP, and six samples of normal mucosa (NM) overlapping the third molar were used to control for the chemokine levels. Periodontal examination was conducted. Immunohistochemistry was performed for Factor XIIIa(+) and cluster of differentiation (CD)1a(+) immature DCs and CD83(+) mature DCs. Levels of the CC chemokine ligand (CCL)2, CCL3, CCL5, CCL19, CCL20, and CXC chemokine ligand (CXCL)8 were measured in gingival tissues using enzyme-linked immunosorbent assay. Inflammatory infiltrate, DCs, chemokines, classification of human CP, and clinical parameters were correlated and compared.

RESULTS

The expression of CCL2 and CCL20 was positively correlated with increased densities of CD1a(+) DCs. CCL3 and CXCL8 were positively related to the clinical attachment level. CCL3, CCL5, CCL19, and CXCL8 levels increased in the gingival samples of patients with CP compared with NM, whereas CCL20 levels increased in advanced CP compared with mild-moderate CP.

CONCLUSIONS

More CD1a(+) immature DCs are related to CCL2 and CCL20. CCL3 and CXCL8 chemokines are related to a greater severity of human CP.

Serum monocyte chemoattractant protein-1 is a biomarker in patients with diabetes and periodontitis

INTRODUCTION

The role of serum Monocyte Chemoattractant Protein-1 (MCP-1) as a biomarker of periodontitis is well documented; however, its role in diabetic patients with periodontitis is unknown.

AIM

This study was conducted to determine the presence and concentration of serum MCP-1 in diabetic patients with and without periodontitis and correlate it glycemic status with periodontitis.

MATERIALS AND METHODS

Adult diabetic patients were enrolled and grouped into group I, II, and III based on their glycemic status and serum MCP-1 estimated by ELISA. Linear regression and correlation tests were performed using R statistical software, Medcalc software to observe correlation between the serum MCP-1 and glycated hemoglobin level among different groups.

RESULTS

Serum samples obtained from 37 patients tested positive for MCP-1. Mean serum MCP-1 concentration was highest (482.3 pg/ml) in group III, lowest (149.3 pg/ml) in group I, and intermediate 398.8 pg/ml in group II. Correlation and regression analysis was done between HbA1c and serum MCP-1. A significant positive correlation (P < 0.001) was observed. Serum MCP-1 increased by 37.278 pg/ml for every 1% rise in HbA1c, and the levels were raised in group II and group III than in group I irrespective of their glycemic status. With an HbA1c range of 6.5-6.9% (group II), the serum MCP-1 values cluster around 380-410 pg/ml. Elevated levels of serum MCP-1 (>500 pg/ml) in three subjects corresponded to HbA1c values more than 12.2% (group III).

CONCLUSION

To our knowledge, this is the first study to document serum MCP-1 levels in diabetic patients with periodontitis. Glycemic status influences serum MCP-1, and lack of glycemic control contributes to increased serum MCP-1 levels. Serum MCP-1 may thus serve as a biomarker of inflammation and disease progression in diabetes with periodontitis.

Inflammatory mediators in the pathogenesis of periodontitis

Periodontitis is a chronic inflammatory condition of the periodontium involving interactions between bacterial products, numerous cell populations and inflammatory mediators. It is generally accepted that periodontitis is initiated by complex and diverse microbial biofilms which form on the teeth, i.e. dental plaque. Substances released from this biofilm such as lipopolysaccharides, antigens and other virulence factors, gain access to the gingival tissue and initiate an inflammatory and immune response, leading to the activation of host defence cells. As a result of cellular activation, inflammatory mediators, including cytokines, chemokines, arachidonic acid metabolites and proteolytic enzymes collectively contribute to tissue destruction and bone resorption. This review summarises recent studies on the pathogenesis of periodontitis, with the main focus on inflammatory mediators and their role in periodontal disease.

Bone remodeling-associated salivary biomarker MIP-1α distinguishes periodontal disease from health

BACKGROUND AND OBJECTIVE

The field of salivary diagnostics lacks an accepted and validated biomarker of alveolar bone remodeling. To address this, we examined levels of salivary biomolecules specifically associated with biological aspects of bone remodeling in subjects with chronic periodontitis in a case-control study.

MATERIAL AND METHODS

Levels of macrophage inflammatory protein-1α (MIP-1α), osteoprotegerin, C-telopeptide pyridinoline cross-links of type I collagen and β-C-terminal type I collagen telopeptide in unstimulated whole saliva of 80 subjects (40 subjects with moderate to severe chronic periodontitis and 40 sex- and age-matched healthy control subjects) were measured using enzyme immunosorbent assays. Saliva was collected before clinical examination, which included probing depth, clinical attachment loss and bleeding on probing.

RESULTS

The mean level of MIP-1α in subjects with periodontitis was 18-fold higher than in healthy subjects (p < 0.0001). Clinical periodontal indices correlated significantly with MIP-1α levels (p < 0.0001). Of the biomolecules examined, MIP-1α demonstrated the greatest ability to discriminate between periodontal disease and health as determined by the area under the curve (0.94) and classification and regression tree analysis (sensitivity 94% and specificity 92.7%). Osteoprotegerin levels were elevated 1.6-fold (p = 0.055), whereas C-telopeptide pyridinoline cross-links of type I collagen and β-C-terminal type I collagen telopeptide levels were below the level of detection in the majority of subjects.

CONCLUSION

These findings suggest that the chemokine MIP-1α may aid in identifying periodontitis. Future longitudinal studies are warranted to determine whether this biomarker can help in ascertaining the progression of bone loss in subjects with periodontal disease.

Comparative gender differences in local and systemic concentrations of pro-inflammatory cytokines in rats with experimental periodontitis

BACKGROUND AND OBJECTIVE

There have been few studies of gender differences in response to periodontitis. Thus, we compared gender-specific differences in systemic cytokine concentrations in rats with and without ligature-induced periodontitis.

MATERIAL AND METHODS

Experimental periodontal disease was initiated in Sprague-Dawley rats by placing a ligature around the crowns of the second right maxillary molar tooth. Sham-operated control groups were also created. Two weeks later, the right and left maxillary quadrants of teeth, liver and serum were collected from all the rats, and uterine horns were collected from the female rats. Liver and uterine samples were ground in phosphate-buffered saline (10 mg of tissue/mL of phosphate-buffered saline + protease inhibitor) containing a protease inhibitor, and cytokine concentrations were determined by enzyme-linked immunosorbent assay. Digital radiographs were made of maxillary quadrants, and the distance from cemento-enamel junction to alveolar crest was measured using image analysis software. Data were compared by factorial analysis of variance and a post-hoc Tukey test.

RESULTS

Female rats with ligatures had greater, but not significantly different, alveolar bone loss than males with ligatures. However, they had higher serum concentrations of interleukin-6, tumor necrosis factor-alpha and C-reactive protein, and liver C-reactive protein (p < 0.05). These females also had higher interleukin-6, tumor necrosis factor-alpha and vascular endothelial growth factor concentrations within the uterine horn, compared to female controls (p < 0.05). Male animals with ligatures had lower serum concentrations of C-reactive protein and higher interleukin-6 and tumor necrosis factor-alpha concentrations within serum, compared to male controls (p < 0.05).

CONCLUSION

Our study suggests that females with periodontal disease have a greater risk for inflammatory-based systemic diseases than males.

Mapping the pathogenesis of periodontitis: a new look

Chronic adult periodontitis is a bacterially induced chronic inflammatory disease that destroys the connective tissue and bone that support teeth. Concepts of the specific mechanisms involved in the disease have evolved with new technologies and knowledge. Histopathologic observations of diseased human tissues were used previously to speculate on the causes of periodontitis and to describe models of pathogenesis. Experimental evidence later emerged to implicate bacterial plaque deposits as the primary factor initiating periodontitis. At the same time, specific bacteria and immunoinflammatory mechanisms were differentially implicated in the disease. In the mid-1990s, early insights about complex diseases, such as periodontitis, led to new conceptual models of the pathogenesis of periodontitis. Those models included the bacterial activation of immunoinflammatory mechanisms, some of which targeted control of the bacterial challenge and others that had adverse effects on bone and connective tissue remodeling. Such models also acknowledged that different environmental and genetic factors modified the clinical phenotype of periodontal disease. However, the models did not capture the dynamic nature of the biochemical processes, i.e., that innate differences among individuals and changes in environmental factors may accelerate biochemical changes or dampen that shift. With emerging genomic, proteomic, and metabolomic data and systems biology tools for interpreting data, it is now possible to begin describing the basic elements of a new model of pathogenesis. Such a model incorporates gene, protein, and metabolite data into dynamic biologic networks that include disease-initiating and -resolving mechanisms. This type of model has a multilevel framework in which the biochemical networks that are regulated by innate and environmental factors can be described and the interrelatedness of networks can be captured. New models in the next few years will be merely frameworks for integrating key knowledge as it becomes available from the "-omics" technologies. However, it is possible to describe some of the key elements of the new models and discuss distinctions between the new and older models. It is hoped that improved conceptual models of pathogenesis will assist in focusing new research and speed the translation of new data into practical applications.

The bacterial flora in the teat duct of ewes can protect against and can cause mastitis

We studied the possible effects of bacterial populations within the teat duct, in the pathogenesis of ovine mastitis. In experiment I, 32 ewes were allocated into group A (ewes from which we isolated (+++ growth) coagulase-negative staphylococci), B (ewes from whose duct we isolated (+ growth) coagulase-negative staphylococci) or C (ewes from which we isolated Bacillus spp.) and subdivided into A1, B1, C1 (n=4; challenged by deposition of 1.250 cfu of Mannheimia haemolytica into the teat duct) or A2, B2, C2 (n=4; used as uninoculated controls); group D (n=8) contained ewes with no bacteria in their teat ducts and were challenged as above. There were less bacteriological isolations of flora (P = 0.018) and challenge (P<0.05) organisms from A1 than from A2 and D ewes; the severity of pathological findings in A1 (summed up score: 27) ewes was smaller than in D (summed up score: 36) ewes (P = 0.038). No such findings were evident with B1 or C1 ewes (P>0.4). In experiment II, ewes (groups E and F, n=6) from whose duct we isolated coagulase-negative staphylococci (+ growth) were used; in group G (n=6) ewes with no bacteria in their teat ducts were included. Teat chapping was applied in E and G ewes. All E ewes developed acute clinical mastitis within 24 h after teat chapping, although we had carried out no challenge; there were more bacteriological isolations of flora organisms from E than from F and G ewes (P < 0.001); the severity of pathological findings in E (score: 28) was greater than in F (score: 3) or G (score: 14) ewes. In experiment III, eight ewes with no bacteria in their teat ducts were allocated into group H or I (n=4) and challenged into the teat (group H) or into the gland (group I) with 10(6) cfu of a Staphylococcus simulans recovered from the teat duct of a group E ewe. Group H ewes developed transiently clinical followed by subclinical mastitis (based on bacteriological and cytological evidence), whilst group I ewes developed severe clinical disease. We conclude that staphylococcal flora present in high numbers within the teat duct of ewes can afford some protection against invading microorganisms. However with impeded defence mechanisms of the teat, the same flora may invade the mammary parenchyma and cause clinical mastitis.

Autoantibodies directed to extracellular matrix components in patients with different clinical forms of periodontitis

BACKGROUND

Periodontal disease occurs in different clinical forms, from mild and easily controllable to more aggressive inflammatory manifestations, with difficult clinical or surgical control. There is evidence that a local autoimmune reaction may participate in the onset and persistence of the aggressive forms of periodontal disease. As the underlying mechanism in this process is not fully understood, we decided to investigate whether patients bearing this form of disease presented higher levels of antibodies directed to extracellular matrix (ECM) components such as type I collagen, fibronectin, and laminin.

METHODS

Three groups of patients were selected by clinical criteria: 22 subjects with aggressive periodontitis (AgP) = group A; 18 subjects with chronic periodontitis (CP) = group B; and 10 healthy (H) volunteers without periodontal disease = group C. Autoantibody levels were evaluated in the sera of these patients using the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

The levels of autoantibodies directed to ECM components (type I collagen, fibronectin and laminin) in the sera of patients with AgP and CP were shown to be statistically different (P <0.05).

CONCLUSIONS

Although the present findings suggest an involvement of autoantibodies directed to ECM components per se in the pathogeny of certain types of periodontal disease, the available data do not support the classification of the lesions as autoimmune. Nevertheless, the findings open a possibility for the development of an additional method for a differential diagnosis of the aggressive forms of periodontal disease.

Severe Periodontitis Is Associated with Low Serum Albumin among Patients on Maintenance Hemodialysis Therapy

The relationship between periodontitis and two measures of systemic inflammation, serum albumin and C-reactive protein (CRP), were examined among patients who were receiving chronic outpatient hemodialysis. Adult patients at two locations, North Carolina and New York City, were evaluated by dentist examiners. Six sites per tooth (up to 32 teeth per patient) were examined. A periodontitis case was defined as > or = 60% of sites with attachment level > or = 4 mm. Multivariable logistic regression was used to determine the association of periodontitis with low serum albumin, defined as < 3.5 mg/dl, and with high CRP, defined as > 3.0 mg/dl. A total of 154 patients completed the study. The mean age was 54.6 yr (SD 13.3), and average duration of dialysis was 4.0 yr (3 mo to 16 yr). Eighty-six (54.6%) were men, and 89 (58.2%) were black. Common causes of end-stage kidney disease were hypertension (12.3%), diabetes (22.1%), glomerulonephritis (7.1%), and other (58.4%). The average number of teeth was 20.3 (SD 8.4). Thirty-five (23%) patients were periodontitis cases. Severe periodontitis was associated with low serum albumin (odds ratio 8.20; 95% confidence interval 1.61 to 41.82; P = 0.01) compared with individuals without severe periodontitis disease after adjustment for age, gender, race, diabetes, hypertension, body mass index, smoking, study site, total cholesterol, serum calcium, serum phosphorus, and normalized protein catabolic rate. There was no observed association of severe periodontitis with CRP. Investigation of the potential contribution of periodontitis to serum albumin and possibly to morbidity and mortality among patients with end-stage kidney disease seems warranted.

Retinoic acid-inducible gene-I is induced in gingival fibroblasts by lipopolysaccharide or poly IC: possible roles in interleukin-1beta, -6 and -8 expression

Retinoic acid-inducible gene-I (RIG-I) is a member of the DExH family of proteins, and little is known of its biological function in the oral region. We previously reported that interleukin 1beta (IL-1beta) induced RIG-I expression in gingival fibroblasts. In this study, we studied the mechanism of RIG-I expression induced by lipopolysaccharide (LPS) or double-stranded RNA (dsRNA) in gingival fibroblasts. We also addressed the role of RIG-I in the expression of IL-1beta, IL-6 and IL-8 in gingival fibroblasts stimulated with LPS or dsRNA. We stimulated cultured human gingival fibroblasts with LPS or dsRNA, and examined the expression of RIG-I mRNA and protein. The effect of cycloheximide, a protein synthesis inhibitor, on RIG-I induction by these stimuli was examined. The expression of IL-1beta, IL-6 and IL-8 in gingival fibroblasts transfected with RIG-I cDNA stimulated with LPS or dsRNA was examined. LPS or dsRNA induced the expression of mRNA and protein for RIG-I in concentration- and time-dependent manners. We also examined the localization of RIG-I, and found that it was expressed in cytoplasm. Cycloheximide did not suppress the LPS or dsRNA-induced RIG-I expression. Introduction of RIG-I cDNA into gingival fibroblasts resulted in enhanced expression of IL-1beta, IL-6 and IL-8; moreover, overexpression of RIG-I stimulated with LPS or dsRNA synergistically increased expression of IL-1beta, IL-6 and IL-8. RIG-I may have important roles in the innate immune response in the regulation of IL-1beta, IL-6 and IL-8 expression in gingival fibroblasts in response to LPS and dsRNA.

Expression of caspase-3, p53 and Bcl-2 in generalized aggressive periodontitis

BACKGROUND

Apoptosis, or programmed cell death is a form of physiological cell death. It is increased or decreased in the presence of infection, inflammation or tissue remodelling. Previous studies suggest that apoptosis is involved in the pathogenesis of inflammatory periodontal disease. The aim of the present study was to investigate the clinical features and known indicators of apoptosis (p53, Bcl-2, Caspase-3) in patients with generalized aggressive periodontitis (GAP) METHODS: Eight patients with GAP, who had sites with probing depths (PD) > 5 mm, and 10 periodontally-healthy persons were included in the study. Clinical examinations and PD were performed, and the plaque index and gingival index were recorded. Gingival tissues biopsies were obtained from active site of each patient and from healthy individuals. The expression of caspase-3, Bcl-2, and p53 was evaluated by immunohistochemistry

RESULTS

There were no significant differences between GAP and control group with respect to levels of caspase-3 and p53 expression (P > 0.05). Contrary, the frequency of grade 3 expression of Bcl-2 was higher in GAP group than the control group.

CONCLUSION

The higher frequency of Bcl-2 expression in GAP group indicates and delayed apoptosis can lead to increasing resident inflammatory cells in periodontal tissues and resulting in progressive periodontal destruction.

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.

Diagnostic biomarkers for oral and periodontal diseases

This article provides an overview of periodontal disease diagnosis that uses clinical parameters and biomarkers of the disease process.This article discusses the use of biomarkers of disease that can be identified at the tissue, cellular, and molecular levels and that are measurable in oral fluids such as saliva and gingival crevicular fluid. Biomarkers identified from these biologic fluids include microbial, host response, and connective tissue-related molecules that can target specific pathways of local alveolar bone resorption. Future prospects for oral fluid-based diagnostics that use micro-array and microfluidic technologies are presented.

Hereditary gingival fibromatosis associated with generalized aggressive periodontitis: a case report

BACKGROUND

Hereditary gingival fibromatosis is a rare, genetically inherited overgrowth condition that is clinically characterized by a benign fibrous enlargement of maxillary and mandibular keratinized gingiva. A syndromic association between gingival fibromatosis and a wide variety of other genetically inherited disorders has been described. However, its coexistence with aggressive periodontitis has not been reported.

METHODS

A 24-year-old African-American female, patient (proband X, [Px]) reported with a chief complaint of tooth mobility and gingival enlargement. Clinical examination revealed moderate to severe gingival overgrowth on both mandible and maxilla. Generalized attachment loss and mobility of the teeth were observed. Radiographic evaluation demonstrated severe alveolar bone loss. The patient was diagnosed with gingival fibromatosis and aggressive periodontitis based on the clinical and radiographic findings. Her brother (Bx) and her mother (Mx) were evaluated and diagnosed with gingival fibromatosis suggesting that this is a dominant trait in the family and gingival fibromatosis might be of hereditary origin. In addition, the brother also exhibited localized aggressive periodontitis. Medical history revealed no other systemic or local contributory factors associated with the oral findings in any of the subjects.

RESULTS

Surgical therapy included internal bevel gingivectomy combined with open flap debridement procedures for Px and Bx. Only internal bevel gingivectomy was performed for Mx since there was mild bone resorption and no intrabony defects. At the time of surgery, gingival biopsies were obtained and fixed in 4% paraformaldehyde. Multiple serial sections were stained with hematoxylin and eosin. Microscopic evaluation of the gingival specimens revealed large parallel collagen bundles associated with scarce fibroblasts in the connective tissue. The collagen bundles reached into the subepithelial connective tissue where elongated rete-pegs were also observed. Following the completion of the treatment, no signs of recurrence or bone resorption were observed over 2-year follow-up.

CONCLUSIONS

This is the first report of hereditary gingival fibromatosis associated with aggressive periodontitis. Combined treatment comprising removal of fibrotic gingival tissue and traditional flap surgery for the elimination of intrabony defects represents a unique treatment approach in periodontal therapy. Two-year follow-up revealed that both the gingival overgrowth and the destructive lesions were successfully treated.

Rate of cultivable subgingival periodontopathogenic bacteria in chronic periodontitis

Although microbiological studies have identified more than 400 bacterial species in periodontal pockets, only a limited number have been implicated as periodontal pathogens. The purpose of this study was to investigate the incidence of cultivable subgingival periodontopathogenic bacteria in chronic periodontitis. Bacterial samples were collected with sterile paper points from the deepest periodontal pockets ((5 mm) of 203 patients: 92 males and 111 females, aged 35-55 years. The samples were cultured under anaerobic and capnophilic conditions using selective and non-selective media. Isolates were characterized to species level by conventional biochemical tests and a commercial rapid test system. The isolates were Actinobacillus actinomycetemcomitans (26.8%), Porphyromonas gingivalis (21.9%), Capnocytophaga sputigena (16.7%), Eikenella corrodens (13.2%), Prevotella intermedia (10.5 %), Prevotella disiens (3.1%), Peptostreptococcus micros (2.9%), Capnocytophaga gingivalis (2.2%), Prevotella corporis (1.8%), Peptostreptococcus magnus (1.3%) and Fusobacterium nucleatum (0.4%). No periodontopathogenic bacterial growth was observed in 14 of the samples (6.2%). The number of samples associated with monobacterial growth and polybacterial growth were 74.9% and 18.2% respectively. It is concluded that the bacterial composition associated with a number of patients' samples is quite complex, and that some of cultivable anaerobic and capnophilic bacteria act as periodontal pathogens in chronic periodontitis.

Streptococci and Actinomyces induce antibodies which cross react with epithelial antigens in periodontitis

Perturbation of epithelial structure is a prominent but poorly understood feature of the immunopathological response to bacterial antigens which characterizes the destructive lesion of periodontitis. Western analysis of sera from 22 patients with periodontitis detected multiple antigens in extracts of epithelial cells whereas sera from 12 periodontally healthy subjects displayed only trace reaction with epithelial antigens. To investigate a possible relationship between the bacterial flora adjacent to diseased sites and the presence of antibodies reactive with epithelium, subgingival plaque samples were taken from deep periodontal pockets and cultured anaerobically. Gram positive bacteria containing antigens cross-reactive with epithelial cells were reproducibly isolated by probing membrane colony-lifts with affinity-isolated (epithelium-specific) antibodies and identified by 16S rDNA sequence homology as streptococci (S. mitis, S. constellatus and two S. intermedius strains) and Actinomyces (A. georgiae, and A. sp. oral clone). Conversely, when serum from patients with periodontitis was absorbed with the captured bacterial species the number of epithelial antigens recognized was specifically reduced. It was concluded that development of cross-reactive antibodies related to these organisms may contribute to perturbation of the epithelial attachment to the tooth and the progression of periodontitis. These autoreactive antibodies could also be a contributing factor in other diseases affecting epithelia.

Flow-cytometric analysis of T-lymphocyte subsets after different treatment methods in patients with pericoronitis

PURPOSE

The aim of this study was to determine whether there was any change in T-lymphocyte subsets in patients with periocoronitis after the application of different treatment methods.

PATIENTS AND METHODS

Twenty-six patients with acute pericoronitis were included in the study. In every phase of the treatment (pretreatment, postcurettage, and postextraction), the biopsy samples were taken from the gingival tissues at sites of pericoronitis. Then, CD4(+) and CD8(+) lymphocyte and CD4(+)/CD8(+) ratio values were determined using flow cytometry in the biopsy samples. At the same time, gingival index (Löe-Silness) and plaque index (Silness-Löe) scores were recorded to assess the periodontal status in patients. To determine the correlation between the clinical measurements and the laboratory results obtained before the treatment, after curettage, and after extraction, we conducted an analysis using a paired t-test.

RESULTS

The normal values in peripheral blood of CD4(+) and CD8(+) lymphocytes are 25% to 29% and 19% to 48%, respectively. However, the CD4(+) and CD8(+) lymphocyte values in the patients with acute pericoronitis were found to be 22.12% +/- 6.15% and 7.69% +/- 4.12%, respectively. These values are lower than the normal values. The CD4(+) lymphocyte value increased to 31.06% +/- 7.09% postcurettage and to 32.24% +/- 3.11% postextraction. The CD8(+) lymphocyte value increased to 16.21% +/- 5.27% postcurettage and to 18.25% +/- 3.13% postextraction. The CD4/CD8 ratio increased postcurettage and postextraction. This increase was statistically significant (P <.001). Postcurettage, there was decrease in clinical indexes, which was statistically significant (P <.001). A significant correlation between CD4(+) lymphocyte and ginigival index values and also between CD8(+) lymphocyte and plaque index values was determined postcurettage (P <.05).

CONCLUSION

CD4(+) and CD8(+) T-lymphocytes could play a significant role in pericoronitis pathobiology.

Gingival and dermal fibroblasts produce interleukin-1? converting enzyme and interleukin-1? but not interleukin-18 even after stimulation with lipopolysaccharide

Epithelial cells play a critical role in periodontal disease through the secretion of pro-inflammatory cytokines such as interleukin-1 beta (IL-1 beta) and interleukin-18 (IL-18). However, the role played by fibroblasts is still unclear. The rationale of this study was to throw light on the role of gingival fibroblasts in periodontal disease. We thus investigated the expression of IL-1 beta, IL-18, and ICE mRNA and the secretion of the corresponding proteins by human normal gingival fibroblasts before and after stimulation with lipopolysaccharide (LPS) from Porphyromonas gingivalis and Escherichia coli. IL-1 beta, IL-18, and ICE mRNA expression was evaluated by RT-PCR. Proteins were analyzed by Western blot and ELISA. We demonstrated that gingival fibroblasts expressed ICE mRNA. Basal expression of ICE was modulated following cell stimulation with lipopolysaccharide (5 mug/ml). However, gingival fibroblasts expressed low levels of IL-1 beta mRNA. The expression was potentiated by LPS. The expression of IL-1 beta mRNA was followed by the secretion of IL-1 beta but not IL-18 protein. Our study suggests that fibroblasts may be involved in the defense against infections via an IL-1 beta-mediated but not an IL-18-mediated mechanism.

Microbiological characteristics of subgingival microbiota in adult periodontitis, localized juvenile periodontitis and rapidly progressive periodontitis subjects

OBJECTIVE

To describe the prevalence of the cultivable subgingival microbiota in periodontal diseases and to draw attention to the polymicrobial nature of periodontic infections.

METHODS

The study population consisted of 95 patients, 51 females and 44 males, aged 14-62 years. Twenty-nine patients exhibited adult periodontitis (AP), six localized juvenile periodontitis (LJP), and 60 rapidly progressive periodontitis (RPP). Two to four pooled bacterial samples were obtained from each patient. Samples were collected with sterile paper points from the deepest periodontal pockets. The samples were cultured under anaerobic and microaerophilic conditions using selective and non-selective media. Isolates were characterized to species level by conventional biochemical tests and by a commercial rapid test system.

RESULTS

Prevotella intermedia and Capnocytophaga spp. were the most frequently detected microorganisms in all diagnostic groups. Porphyromonas gingivalis and Peptostreptococcus micros were found more frequently in AP and RPP patients, while Actinobacillus actinomycetemcomitans and Eikenella corrodens were associated with AP, LJP and RPP patients. The other bacterial species, including Actinomyces spp., Streptococcus spp. and Eubacterium spp., were detected at different levels in the three disease groups.

CONCLUSIONS

The data show the complexity of the subgingival microbiota associated with different periodontal disease groups, indicating that the detection frequency and levels of recovery of some periodontal pathogens are different in teeth affected by different forms of periodontal disease.

Detection of platelet-activating factor in gingival tissue surrounding failed dental implants

BACKGROUND

Dental implant therapy has entered routine clinical practice. However, the failure rate of implants at 5 years, due to biological factors, is still around 7%. The pathogenesis of implant loss involves a complex network of cells and inflammatory mediators. This study evaluated platelet-activating factor (PAF), a potent phospholipid mediator of inflammation, in soft tissue surrounding failed dental implants versus healthy implants.

METHODS

PAF was estimated on extracted lipids by bioassay on washed rabbit platelets; inflammatory cell populations were assessed semiquantitatively after staining, and microvessel density was evaluated after immunohistochemical staining.

RESULTS

Biologically active PAF was detected in the lipid extracts of samples excised from gingival tissue of patients with failed implants, but not in samples from patients with osseointegrated implants or from healthy edentulous subjects. The amount of PAF detected in failed implants was significantly higher than in healthy implants, suggesting a local production of this mediator.

CONCLUSIONS

The presence of PAF was associated with histopathological findings of local inflammation and increased blood vessel density.

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.

Antigenic specificity of gingival crevicular fluid antibody to Actinobacillus actinomycetemcomitans

Elevated antibody levels to periodontopathogens in GCF have been identified and used as support for local antibody synthesis in periodontitis. This study examined both cross-sectional and longitudinal GCF samples for the antigenic specificity of antibody in the fluid. GCF samples were collected from each tooth of 27 periodontitis patients infected with A. actinomycetemcomitans. Levels of IgG antibody in the GCF were assessed by means of an ELISA and compared with serum for determination of local elevations. A proportion of those GCF samples that exhibited significantly elevated antibody were examined by Western immunoblotting to outer membrane antigens from A. actinomycetemcomitans. Homologous sera were also examined for comparison of antibody specificities. Of the sites with elevated IgG antibody, 87% were colonized by A. actinomycetemcomitans; however, 46% of sites with A. actinomycetemcomitans infection did not have elevated antibody. Cross-sectional studies identified a 78 to 100% agreement between the antibody specificities in GCF and those in serum. Additionally, patterns of antibody reactivity in both GCF and serum in the subjects were often very distinctive. Longitudinal alterations in GCF antibody were examined in 15 patients through a monitoring interval of up to 2 years and showed a general conservation of specificities. However, 7/15 patients exhibited a definite acquisition of different antibody specificities during the monitoring. These results describe a relationship between elevated local antibody and A. actinomycetemcomitans infection. Furthermore, the antibody specificities in serum appear to reflect generally the local response to this pathogen.

The effect of interleukin-11 on the progression of ligature-induced periodontal disease in the beagle dog

BACKGROUND

The rate of progression of periodontal disease is dependent on the complex regulatory interactions between bacteria and the immune modulators of the host response. The purpose of this investigation was to determine if recombinant human interleukin-11 (rhIL-11), known to downregulate several inflammatory modulators, has the ability in subcutaneous administration to reduce the rate and/or extent of periodontal attachment loss and radiographic bone loss in a ligature-induced periodontal disease beagle dog model.

METHODS

Twenty 18-month-old female beagle dogs were brought to optimal periodontal health over a 2-week period. Periodontal disease was induced by placing 2.0 silk ligatures around the mandibular first molar and premolar teeth. The dogs were divided into 3 treatment groups and one control group. The 3 treatment groups received subcutaneous injections of either 15, 30, or 80 microg/kg of rhIL-11 in saline buffer twice a week. The placebo group received buffer only subcutaneously twice a week. The gingival health of each animal was measured by recording the presence or absence of gingival inflammation, plaque, and bleeding upon probing. Attachment levels and bone height were also measured. Treatment administration and clinical and radiographic evaluations were performed in a masked fashion.

RESULTS

At week 8, the placebo group had 3.89 mm of attachment loss and 73.8% radiographic bone remaining. The 15 microg/kg group had 1.99 mm attachment loss and 89.5% bone remaining; the 30 microg/kg group had 0.84 mm attachment loss and 92.5% bone remaining; and the 80 microg/kg group had 1.05 mm attachment loss and 85.5% bone remaining. All 3 treatment groups lost significantly less attachment and retained significantly more bone than did the placebo group.

CONCLUSIONS

The study indicates that subcutaneous injections of rhIL-11 were able to slow the progression of attachment and radiographic alveolar bone loss in a ligature-induced beagle dog model.

Gingival crevicular fluid inflammatory mediators and bacteriology of gingivitis in nonhuman primates related to susceptibility to periodontitis

The hypothesis to be tested was that the microbiota and resulting local host inflammatory response characteristics in oral conditions of high levels of chronic gingival inflammation increases susceptibility to progressing periodontitis. This study used cynomolgus monkeys, Macaca fascicularis (nonhuman primates), with high and low levels of long-standing gingival inflammation to define the profiles of gingival crevicular fluid mediators, cytokines and immunoglobulins; describe the subgingival microbiota; and evaluate their susceptibility to ligature-induced periodontitis. Sixteen nonhuman primates were stratified into two groups (HI, LO) based upon Bleeding Index as a measure of the natural level of inflammation (HI = 1.26 +/- 0.45; LO = 0.22 +/- 0.16). The host mediator levels, subgingival microbiota, and clinical characteristics of the LO and HI groups were compared after 30 days of oral hygiene, during a 30 day experimental gingivitis (7, 14, and 30 days), and during periodontitis (30, 60, and 90 days). The results demonstrated that nonhuman primates with high levels of long-standing gingival inflammation when compared to those nonhuman primates with low inflammation show: 1) different inflammatory mediator profiles in gingival crevicular fluid (particularly for immunoglobulin A (IgA) and IgG levels), 2) a different quantitative and qualitative subgingival microbiota; and 3) a similar progression of periodontitis. Thus, while variations in host inflammatory responses to local factors exist in the nonhuman primates, an extensive subgingival challenge (such as ligation) may negate these individual differences.

Generalized periodontal involvement in a young patient with systemic lupus erythematosus

Inflammation is considered to be a leading cause of morbidity in systemic lupus erythematosus (SLE), yet inflammatory periodontal involvement is rarely encountered. A young lady suffering from active SLE accompanied by severe periodontal loss, manifested by gingival recession of all her teeth, was referred to our clinic for treatment. The association between periodontal involvement and connective tissue diseases is unclear, and the literature dealing with periodontal involvement in patients suffering from Sjogren's syndrome and rheumatoid arthritis is comprised of studies showing both normal and pathological periodontal status. We discuss the possible underlying mechanisms.

CD4(+) T cells and the proinflammatory cytokines gamma interferon and interleukin-6 contribute to alveolar bone loss in mice

In this study, we used a mouse model to examine the role of the adaptive immune response in alveolar bone loss induced by oral infection with the human gram-negative anaerobic bacterium Porphyromonas gingivalis. Severe combined immunodeficient mice, which lack B and T lymphocytes, exhibited considerably less bone loss than did immunocompetent mice after oral infection, suggesting that lymphocytes contribute to this process. Bone loss after oral infection was decreased in mice deficient in major histocompatibility complex (MHC) class II-responsive CD4(+) T cells, but no change in bone loss was observed in mice deficient in MHC class I-responsive CD8(+) T cells or NK1(+) T cells. Mice lacking the cytokine gamma interferon or interleukin-6 also demonstrated decreased bone loss. These results suggest that the adaptive immune response, and in particular CD4(+) T cells and the proinflammatory cytokines that they secrete, are important effectors of bone loss consequent to P. gingivalis oral infection. The studies also reinforce the utility of the mouse oral infection model in dissecting the pathobiology of periodontal disease.

Virulence of a polymicrobic complex, Treponema denticola and Porphyromonas gingivalis, in a murine model

The effect of a polymicrobic infection employing Treponema denticola and Porphyromonas gingivalis in the murine lesion model was used to determine the synergistic virulence of these two periodontopathic bacteria. At high doses of P. gingivalis W50, addition of T. denticola in the infection mixture had no effect on the formation and size of the spreading lesion caused by this microorganism. However, at low P. gingivalis challenge doses, T. denticola significantly enhanced the virulence of P. gingivalis compared with monoinfection of this microorganism. A potential role of the trypsin-like protease enzyme activity of P. gingivalis in this synergistic virulence was tested using P. gingivalis mutants deficient (i.e., BEI) or devoid (i.e., NG4B19) of this protease activity. These findings demonstrated that T. denticola-P. gingivalis complexes exhibit enhanced virulence in this model and that even using a polymicrobic challenge infection, the trypsin-like protease activity was important to P. gingivalis virulence expression.

Immunization with Porphyromonas gingivalis cysteine protease: effects on experimental gingivitis and ligature-induced periodontitis in Macaca fascicularis

Targeting bacterial virulence factors such as proteases for immunization may hold the key to limiting or preventing loss of attachment and alveolar bone in periodontal disease. This study examined the clinical, microbiological, and immununological responses following active immunization with a purified Porphyromonas gingivalis cysteine protease (porphypain-2) in the nonhuman primate (Nhp) Macaca fascicularis. One group of Nhp was immunized with porphypain-2 antigen while control Nhp received placebo injections. All Nhp were subjected to experimental gingivitis followed by ligature-induced periodontitis in a split-mouth design. An enzyme-linked immunosorbent assay demonstrated that immunization elicited a significantly elevated and specific IgG antibody response to both whole cell P. gingivalis (36-fold) and to porphypain-2 (194-fold). Checkerboard hybridization DNA analysis of subgingival plaque from ligated sextants demonstrated that 25% more Gram-negative anaerobic species became significantly elevated from baseline and at earlier timepoints in the control group than in the immununized group. Immunization with this protease did not suppress the emergence of P. gingivalis. Clinical indices showed few changes related to immunization. Alveolar bone density changes demonstrated a highly significant loss in ligated sextants compared to non-ligated sextants within the control group (P < 0.001), and a smaller but significant difference within the immunized group (P = 0.043). Comparison of ligated sextants only demonstrated more bone loss in the control group versus the immunized group (-13.07+/-9.51 versus -9.41+/-6.18; computer-assisted densitometric image analysis units +/- SD); the difference approached, but did not reach, significance. The results suggest that porphypain-2 may contribute to the pathogenic potential of the subgingival plaque microbiota in the Nhp model of ligature-induced periodontitis, and that active immunization with porphypain-2 appeared capable of altering this pathogenic response.

Porphyromonas gingivalis virulence in a murine lesion model: effects of immune alterations

This study utilized various mouse strains with documented alterations in immune system components to assess their contribution to modify the virulence of Porphyromonas gingivalis. P. gingivalis W50 was cultivated on blood agar plates, harvested and used to challenge mice by subcutaneous injection on the dorsolateral surface of the back. Soft tissue lesion development was estimated by measuring the area of the spreading lesion formed by this microorganism over a period of 15 days. Challenge of various normal inbred and outbred mouse strains including: BALB/cN, BALB/cJ, BALB/c nu/+, ICR, B10.A(4R), B10.MBR, A/J, C57BL/6J, CBA/CaH, C.B-17/Icv Tacf DF and C3H/HeN with 2 x 10(10) bacteria showed similar lesion size among these strains (approximately 400 mm2). Genetically deficient mouse strains [C.B-17/Icr Tac (SCID); DBA/2 (C5 deficient); BALB/c nu/nu (T cell deficient); CBA/CaHN-XID/J (B cell deficient) and C3H/HeJ (LPS hyporesponsive)] demonstrated a lesion size which was similar to normal animals. C57BL/6J-BgJ (NK cell deficient) mice exhibited a significantly more severe lesion than the other strains tested. Following healing of the lesions, we initiated a secondary infection of the surviving animals to estimate the acquisition of protective immunity following recovery from the primary infection. Normal mice demonstrated a delayed onset and decrease in lesion size of 15 to 30% compared with the primary infection. In contrast, each of the immunodeficient strains appeared unable to develop immune protection to the secondary challenge. The findings suggest that protection against primary infections with P. gingivalis are mediated by innate immune mechanisms (PMN. NK cells). Additionally, it appears that T-cell-dependent humoral responses are critical to developing immunity to subsequent P. gingivalis infection.

Characteristics and responses of EBV immortalized B cells from periodontal disease patients

OBJECTIVE

This study was designed to examine human B cell responses to Actinobacillus actinomycetemcomitans (Aa). The general hypothesis to be tested was that Epstein-Barr virus (EBV) immortalized B cells could be used to investigate variations in B cell responsiveness of periodontitis patients to periodontal pathogens, and that B cells derived from the peripheral blood of periodontal disease patients infected with Aa demonstrate differences in in vitro activities compared to periodontally healthy subjects.

DESIGN

EBV-transformed B cell lines were used to analyze immunoglobulin and Aa-specific antibody responses, as well as to determine the frequencies of cells producing immunoglobulin (Ig) of a specific isotype and detect clones secreting antibodies specific for Aa. Lymphoblastoid cells lines (LCL) were derived by clonal transformation of peripheral blood lymphocytes from 10 Aa-infected patients with adult periodontitis (Aa-AP) and seven normal subjects.

METHODS

The B cells were incubated in Aa-coated polystyrene plates to separate adherent and non-adherent cells, and stimulate the cells with the whole bacteria. In addition, the B cells were stimulated with Aa LPS, E. coli LPS, or the polyclonal B cell activators (PBAs), pokeweed mitogen (PWM) and Staphylococcus aureus protein A (SpA). Both adherent and non-adherent cell populations were cultured for up to 15 days.

MAIN OUTCOME MEASURE

Total immunoglobulins (Igs) and antibody (IgG, IgA, IgM) levels to Aa in the culture supernatants were assessed using an ELISA. The distribution of IgG, IgA, IgM and Aa-specific antibody producing cells was analyzed by a double immunoenzymatic staining technique.

RESULTS

IgM levels produced by the LCLs were significantly increased vs IgG and IgA (P < 0.001). Three days after Aa stimulation, a marked increase in the level of total Igs and Aa-specific antibody was observed in adherent cells from Aa-AP (P < 0.05-0.03). Aa-specific antibody levels were significantly higher in the supernatants from Aa-AP vs normals throughout the culture interval (P < 0.03). There was also a significant increase in Aa-specific antibody levels after stimulation with Aa LPS or E. coli LPS (P < 0.05), whereas PWM and SpA had no significant effect on antibody to Aa. There was a predominance of IgM cells compared to IgG and IgA isotypes (P < 0.04) in LCLs from Aa-infected patients. After stimulation with Aa, a significant increase in the number of IgA (111%) and IgG (48%) secreting cells was observed, concomitant with a 74% decrease in the Ig-negative cell population. Total Aa+ cells increased significantly after stimulation (P < 0.001), predominated by Aa-specific IgG and IgM antibody producing cells.

CONCLUSIONS

These results showed that LCLs from Aa-infected patients were polyclonal with respect to isotype distribution. Further stimulation with Aa revealed a shift to cytoplasmic IgG and IgA expression, as well as increases in the Aa-specific B cell population. In contrast, the PBAs stimulated the LCLs to synthesize primarily IgM. Additionally, the findings indicated that: (1) without T cells, polyclonal activation of B cells may lead to elevated Aa-specific B cell populations; and (2) the presence of previously sensitized B cells is required to exert an antigen specific antibody response in the LCL. We conclude that secondary activation of primed B cells by oral bacteria or their products in advanced periodontal lesions may contribute to the local accumulation of significant numbers of Ig-producing cells. This report also suggested that EBV-mediated transformation can be used to probe B cell-bacterial interactions in studies of periodontitis.

Polyclonal B cell activators and in vitro induction of auto-antibody reactive with collagen

Cells producing autoantibodies are known to be present in chronically inflamed periodontal tissues. In sites of chronic inflammation, polyclonal B cell activators (PBA) are known to exhibit adjuvant activity when combined with foreign antigens. These results prompted an examination of PBA in eliciting an antibody response to an autoantigen (i.e. collagen type I). Rat lymphocytes were stimulated with rat collagen (type I), microbial PBA (LPS) or the combination of LPS plus rat collagen in vitro. Anti-collagen antibody-forming cells (AFC) were enumerated using an ELISPOT assay. Collagen or LPS alone elicited few anti-collagen AFC but the addition of LPS to collagen resulted in a substantial adjuvant effect and yielded maximal responses to collagen. Comparisons of anti-collagen AFC from short-term immunized (2-6 wk after booster), non-immunized and long-term immunized (3-4 months after booster) animals were performed. It revealed that cells from recently immunized rats were significantly easier to activate than the other 2 groups. The adjuvant effect of microbial PBA may be important in anti-collagen antibody production and thus the localization of PBA in periodontal pockets may explain why anti-collagen AFC are restricted to the chronically inflamed periodontal tissues.

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.

Host modulation of tissue destruction caused by periodontopathogens: effects on a mixed microbial infection composed of Porphyromonas gingivalis and Fusobacterium nucleatum

These studies determined the ability of selected periodontopathogens to synergistically initiate soft tissue destruction in a murine abscess model. The development of immunity following recovery from infection or by active immunization was also examined. Mice were infected with P. gingivalis W50, F. nucleatum T18, or a combination of the two microorganisms. F. nucleatum caused only a localized lesion in contrast to P. gingivalis which caused a spreading suppurative inflammatory lesion of the skin and subcutaneous tissues, which, depending upon the dose, could result in death. Infection of mice with a combination of P. gingivalis and F. nucleatum elicited a significantly greater lesion size (P<0.001) and lethality compared with P. gingivalis alone. Mice infected with a subclinical dose (no visible lesion) of P. gingivalis failed to develop protective immunity to a secondary P. gingivalis challenge. Mice that had recovered from P. gingivalis lesions demonstrated partial protection against subsequent P. gingivalis challenge; however, the immunity was less protective against the mixed F. nucleatum + P. gingivalis infection. Active immunization with P. gingivalis protected against both the P. gingivalis and F. nucleatum + P. gingivalis challenges and this protection was correlated with the levels of specific serum immunoglobulin G (IgG) antibody. The results indicated that the murine model is ideally suited to examine bacterially-mediated mixed infections that result in soft tissue destruction. This destruction can be minimized, but not abrogated, with development of immunity. Challenge with sufficient numbers of the pathogens can overwhelm the acquired immunity.

Specific issues in clinical trials on the use of barrier membranes in periodontal regeneration

There are presently a number of different barriers available for use clinically in guided tissue regeneration (GTR) procedures. A number of trials using these techniques and comparing different types of barrier membranes are being published in the scientific literature. This review discusses issues related to clinical trials on the use of barrier membranes in periodontal regeneration. Outcome measures, both clinical and histological, are discussed in relation to results following GTR procedures. The difference between regeneration and repair is reviewed as well as methods of clinical and histologic assessment of both these outcomes. Data regarding the impact of patient variables and tooth or defect variables on outcomes are presented and suggestions for study designs are made based on these variables. Aspects of assessing for an appropriate sample size in superiority and equivalency trials using GTR techniques are presented as well as interpretation of results following these trials and their clinical significance.

Factors affecting IL-1-mediated collagen metabolism by fibroblasts and the pathogenesis of periodontal disease: a review of the literature

Fibroblasts have been studied extensively for their contribution to connective tissue destruction in diseases where the metabolism of extracellular matrix components plays an essential part in their pathogenesis. A considerable dissolution, especially of collagen fibrils, is a well-known characteristic of the periodontal ligament and the gingival connective tissue in microbial-induced periodontal disease. Fibroblasts, responsible for the assembly of the extracellular matrix, are capable of responding directly to oral microbial challenges or indirectly, following activation of the host immune response, and can alter the composition of connective tissue in several ways: synthesis of inflammatory mediators, their receptors and antagonists; fibroblast proliferation; collagen synthesis; phagocytosis of collagen fibrils; and synthesis of proteolytic enzymes, including matrix metalloproteinases and their corresponding inhibitors. The contributions of these cellular fibroblastic properties to the pathogenesis of periodontal disease are reviewed in the context of the cytokine, interleukin-1, as the inflammatory regulator.