Serum IgG to heat shock proteins and Porphyromonas gingivalis antigens in diabetic patients with periodontitis

Mediators between oral dysbiosis and cardiovascular diseases

Clinical periodontitis is associated with an increased risk for cardiovascular diseases (CVDs) through systemic inflammation as the etiopathogenic link. Whether the oral microbiota, especially its quality, quantity, serology, and virulence factors, plays a role in atherogenesis is not clarified. Patients with periodontitis are exposed to bacteria and their products, which have access to the circulation directly through inflamed oral tissues and indirectly (via saliva) through the gastrointestinal tract, resulting in systemic inflammatory and immunologic responses. Periodontitis is associated with persistent endotoxemia, which has been identified as a notable cardiometabolic risk factor. The serology of bacterial biomarkers for oral dysbiosis is associated with an increased risk for subclinical atherosclerosis, prevalent and future coronary artery disease, and incident and recurrent stroke. In addition to species-specific antibodies, the immunologic response includes persistent, cross-reactive, proatherogenic antibodies against host-derived antigens. Periodontitis may affect lipoprotein metabolism at all levels, and all lipoprotein classes are affected. Periodontitis or its bacterial signatures may be involved not only in increased storage of proatherogenic lipids but also in attenuation of the anti-atherogenic processes, thereby putatively increasing the net risk of atherosclerosis. In this review we summarize possible molecular mediators between the dysbiotic oral microbiota and atherosclerotic processes.

Oxidative Stress in the Local and Systemic Events of Apical Periodontitis

Oxidative stress is involved in the pathogenesis of a variety of inflammatory disorders. Apical periodontitis (AP) usually results in the formation of an osteolytic apical lesion (AL) caused by the immune response to endodontic infection. Reactive oxygen species (ROS) produced by phagocytic cells in response to bacterial challenge represent an important host defense mechanism, but disturbed redox balance results in tissue injury. This mini review focuses on the role of oxidative stress in the local and associated systemic events in chronic apical periodontitis. During endodontic infection, ligation of Toll-like receptors (TLRs) on phagocytes' surface triggers activation, phagocytosis, synthesis of ROS, activation of humoral and cellular responses, and production of inflammatory mediators, such as, cytokines and matrix metalloproteinases (MMPs). The increment in ROS perturbs the normal redox balance and shifts cells into a state of oxidative stress. ROS induce molecular damage and disturbed redox signaling, that result in the loss of bone homeostasis, increased pro-inflammatory mediators, and MMP overexpression and activation, leading to apical tissue breakdown. On the other hand, oxidative stress has been strongly involved in the pathogenesis of atherosclerosis, where a chronic inflammatory process develops in the arterial wall. Chronic AP is associated with an increased risk of cardiovascular diseases (CVD) and especially atherogenesis. The potential mechanisms linking these diseases are also discussed.

Heat Shock Protein Antibody Titers Are Reduced by Statin Therapy in Dyslipidemic Subjects: A Pilot Study

Antibody titers to heat shock protein (Hsp)-60 and -65 are positively related to risk of vascular disease and cardiovascular endpoints. There are few data on the factors that regulate the levels of these antibodies. It is known that the statins have antiinflammatory and immunoregulatory properties. The authors examined the effects of 2 statins, simvastatin (Zocor®) and atorvastatin (Lipitor®) on antibody titers to Hsp-60, -65, and -70 in a group of dyslipidemic patients. Twenty patients attending a lipid clinic, and previously not receiving lipid-lowering treatment, were treated with 10 mg of simvastatin (n=11) or atorvastatin (n=9) for 4 months. An additional 14 patients were recruited from the same clinic at the same hospital as a control group. The medication of these latter patients was unaltered for 4 months and the same parameters were measured as for the statin group. Antibody titers to Hsp-60, -65, and -70 were measured by enzyme-linked immunosorbent assay and lipoprotein profile and highly sensitive serum C-reactive protein (CRP) were measured by routine methods before and after treatment. Pretreatment and posttreatment data were compared by paired t or Mann-Whitney tests. Overall statin treatment was associated with a significant reduction in median antibody titers to Hsp-60 (17.2%, p=0.03), Hsp-65 (15.9%, p=0.003) and Hsp-70 (8.3%, p=0.006), but not in control patients. Both statins caused a reduction in median serum CRP concentrations (45% overall, p<0.05), but significant changes were not observed in the control patients. The effects on Hsp antibody titers were not related to changes in serum CRP concentrations (p>0.05). However, there was a significant correlation between changes in antibody titers to Hsp-60 vs Hsp-65 (p<0.01), Hsp-60 vs Hsp-70 (p<0.05), and Hsp-65 vs Hsp-70 (p<0.001). Statin treatment was associated with a reduction in antibody titers to Hsp-60, -65, and -70. This reduction is not fully explained by the antiinflammatory effects of the statins but may be due to their other immunomodulatory properties.

Periodontitis and atherosclerosis: an observational study

BACKGROUND

Poor oral health has been related with cardiovascular diseases. Specifically, periodontitis has been implicated in the pathogenesis of atherosclerosis. Our aim was to evaluate the relationship between the degree of carotid atherosclerosis and severity of periodontitis in a patient cohort.

METHODS

Fifty adult patients receiving carotid duplex scans in a cerebral hemodynamics lab were included in the study. Ultrasound protocol included measurement of carotid intima-media thickness (IMT), which is a marker of atherosclerosis, and characterization of any atherosclerotic plaques in the cervical common and internal carotid arteries. Patients were divided into two main groups: the test group had IMT ≥ 1 mm or the presence of any carotid atherosclerotic plaque, and the control group had IMT < 1 mm and absence of atherosclerotic plaques. Periodontal evaluation was performed in all the teeth and characterized according to the clinical attachment level, which between 1 mm and 2 mm was classified as slight, 3 mm and 4 mm as moderate and ≥5 mm as severe.

RESULTS

The control group included 15 (30%), while the test group included 35 (70%) subjects. The most common diagnosis was severe periodontitis (40%); moderate and slight periodontitis were also frequent occurrences (32% and 28%, respectively). In the control group, 53.3% had slight, 33.3% had moderate and 13.3% had severe periodontitis. In the test group, those percentages were respectively 22.2%, 44.4% and 33.3%. Patients with atheroma plaque had the highest percentage of severe periodontitis (70.6%). More severe periodontitis was related to atherosclerosis (P = 0.007).

CONCLUSION

This study showed an association between periodontitis severity and carotid atherosclerosis, suggesting that periodontal disease might be a risk indicator for atherosclerotic disease.

Microbial carriage state of peripheral blood dendritic cells (DCs) in chronic periodontitis influences DC differentiation, atherogenic potential

The low-grade oral infection chronic periodontitis (CP) has been implicated in coronary artery disease risk, but the mechanisms are unclear. In this study, a pathophysiological role for blood dendritic cells (DCs) in systemic dissemination of oral mucosal pathogens to atherosclerotic plaques was investigated in humans. The frequency and microbiome of CD19(-)BDCA-1(+)DC-SIGN(+) blood myeloid DCs (mDCs) were analyzed in CP subjects with or without existing acute coronary syndrome and in healthy controls. FACS analysis revealed a significant increase in blood mDCs in the following order: healthy controls < CP < acute coronary syndrome/CP. Analysis of the blood mDC microbiome by 16S rDNA sequencing showed Porphyromonas gingivalis and other species, including (cultivable) Burkholderia cepacia. The mDC carriage rate with P. gingivalis correlated with oral carriage rate and with serologic exposure to P. gingivalis in CP subjects. Intervention (local debridement) to elicit a bacteremia increased the mDC carriage rate and frequency in vivo. In vitro studies established that P. gingivalis enhanced by 28% the differentiation of monocytes into immature mDCs; moreover, mDCs secreted high levels of matrix metalloproteinase-9 and upregulated C1q, heat shock protein 60, heat shock protein 70, CCR2, and CXCL16 transcripts in response to P. gingivalis in a fimbriae-dependent manner. Moreover, the survival of the anaerobe P. gingivalis under aerobic conditions was enhanced when within mDCs. Immunofluorescence analysis of oral mucosa and atherosclerotic plaques demonstrate infiltration with mDCs, colocalized with P. gingivalis. Our results suggest a role for blood mDCs in harboring and disseminating pathogens from oral mucosa to atherosclerosis plaques, which may provide key signals for mDC differentiation and atherogenic conversion.

Determinants of serum IgG responses to periodontal bacteria in a nationally representative sample of US adults

AIM

To assess the distribution of elevated antibody titres to multiple periodontal bacteria, including established/putative pathogens and health-related species, by selected demographic, behavioural, and oral- and general health-related characteristics.

METHODS

Data from 8153 >or=40-year-old participants from the third National Health and Nutrition Examination Survey were used, including 1588 edentulous individuals. We used checkerboard immunoblotting to assess serum IgG levels to 19 periodontal species. Thresholds for elevated antibody responses were defined for each species using the 90th percentile titre in periodontal healthy participants, using two alternative definitions of periodontitis.

RESULTS

Edentulous individuals showed lower antibody responses than dentate participants, notably for titres to "red complex" species and Actinobacillus actinomycetemcomitans. Elevated titres to Porphyromonas gingivalis were twice as prevalent in participants with periodontitis than in periodontal healthy individuals. Non-Hispanic blacks and Mexican-Americans were more likely to display elevated titres for P. gingivalis compared with non-Hispanic whites (22.9%versus 19.4%versus 9.5%). Current smokers were significantly less likely to exhibit high titres to multiple bacteria than never smokers.

CONCLUSION

Demographic, behavioural, and oral- and general health-related characteristics were strong determinants of systemic antibody responses to periodontal bacteria in a nationally representative sample of US adults.

[Diabetes mellitus and periodontal disease]

INTRODUCTION

This review highlights the relations between diabetes mellitus and periodontal disease, as well as the pathogenic mechanisms which are still the subject of investigations. The possible pathogenic mechanisms important for developing periodontal disease in the diabetics are: vascular gingival changes, the disorders in the metabolism of the collagen, disorders in the function of the polimorphonuclear leukocytes and specific microbial flora in the parodontal pockets.

CONCLUSION

It is clear that adequate early recognition and good treatment are very important and significant for treatment of diabetic periodontal disease.

Joint Effects of Antibody to Heat Shock Protein 60, Hypertension, and Diabetes on Risk of Coronary Heart Disease in Chinese

Background: Several studies have suggested an association between antibody to human heat shock protein 60 (anti-Hsp60) and coronary atherosclerosis, but the results have been inconsistent. The aim of this study was to investigate the association between anti-Hsp60 and coronary heart disease (CHD) and to determine whether anti-Hsp60, hypertension, and diabetes have joint effects on CHD risk.

Methods: We measured the concentrations of anti-Hsp60 in 1003 CHD patients and 1003 age- and sex-matched control subjects without CHD events.

Results: Concentrations of anti-Hsp60 were significantly higher in CHD patients than in controls. Increasing concentrations of anti-Hsp60 were significantly associated with higher risk of CHD (P for trend &lt;0.0001) and with increasing severity of CHD as assessed by number of diseased vessels detected with angiography [odds ratio (OR) 3.67, 95% CI 1.56–8.64, P = 0.003] after multivariate adjustment for traditional CHD risk factors. There were strong joint effects of high concentrations of anti-Hsp60 and hypertension (OR 5.17, 95% CI 3.95–6.75, P &lt; 0.0001) and diabetes (OR 6.49, 95% CI 4.52–9.33, P &lt; 0.0001) on CHD risk; simultaneous occurrence of high anti-Hsp60 concentrations, hypertension, and diabetes conferred a dramatically higher risk of CHD (OR 20.99, 95% CI 12.50–35.24, P &lt; 0.0001) in multivariate analyses.

Conclusions: Anti-Hsp60 is independently associated with CHD risk, and a combination of high anti-Hsp60, hypertension, and diabetes is particularly detrimental for CHD risk.

The autoimmune origin of atherosclerosis

Atherosclerosis is a chronic inflammatory disease. Many studies and observations suggest that it could be caused by an immune reaction against autoantigens at the endothelial level, the most relevant of which are oxidized LDL and heat shock proteins (HSP) 60/65. Endothelial dysfunction plays a fundamental role. The first antigen is related to the increased leakage and oxidation of LDL; the second to cellular reaction to stress. Experimental and clinical observations confirm the pathogenetic role of these antigens. Both innate and adaptive immunity and impaired regulatory mechanisms of the autoimmune reaction are involved. Different triggering factors are examined: infectious agents, smoking, air pollution, diabetes and hypercholesterolemia. Analogies and differences between systemic atherosclerosis and transplant-related coronary atherosclerosis help to understand their respective nature. Immune mechanisms might be responsible for the passage from stable plaque to unstable and rupture-prone plaque. Finally, prospects of treatment and prevention are linked to the induction of tolerance to responsible antigens, activation of immune regulatory response and the use of immunomodulatory drugs.

Association between indices of body mass and antibody titres to heat-shock protein-60, -65 and -70 in healthy Caucasians

We have previously shown that antibody titres to several heat-shock proteins (Hsps) are elevated in dyslipidaemic patients and subjects with established vascular disease. Obesity is known to be associated with raised serum inflammatory markers suggesting a state of heightened immune activation. Hence, we have investigated the association between indices of obesity and several Hsp antibody titres in healthy subjects. Subjects (n=170) were recruited from among employees at the University of Surrey and the Royal Surrey County Hospital, Guildford, UK. Of these subjects, 35 were obese with a body mass index (BMI)>/=30 kg/m(2) (19 male and 16 female subjects), 58 were overweight with 30>BMI>/=25 kg/m(2) (36 male and 22 female subjects) and 77 were of a normal weight with BMI<25 kg/m(2) (31 male and 46 female subjects). Overall, obese subjects had significantly higher plasma anti-Hsp-60 (P<0.001), anti-Hsp-65 (P<0.05) and anti-Hsp-70 (P<0.05) compared with overweight and normal weight subjects.

Fungal heat-shock proteins in human disease

Heat-shock proteins (hsps) have been identified as molecular chaperones conserved between microbes and man and grouped by their molecular mass and high degree of amino acid homology. This article reviews the major hsps of Saccharomyces cerevisiae, their interactions with trehalose, the effect of fermentation and the role of the heat-shock factor. Information derived from this model, as well as from Neurospora crassa and Achlya ambisexualis, helps in understanding the importance of hsps in the pathogenic fungi, Candida albicans, Cryptococcus neoformans, Aspergillus spp., Histoplasma capsulatum, Paracoccidioides brasiliensis, Trichophyton rubrum, Phycomyces blakesleeanus, Fusarium oxysporum, Coccidioides immitis and Pneumocystis jiroveci. This has been matched with proteomic and genomic information examining hsp expression in response to noxious stimuli. Fungal hsp90 has been identified as a target for immunotherapy by a genetically recombinant antibody. The concept of combining this antibody fragment with an antifungal drug for treating life-threatening fungal infection and the potential interactions with human and microbial hsp90 and nitric oxide is discussed.

Antibodies against heat shock proteins in environmental stresses and diseases: friend or foe?

Heat shock proteins (Hsps) can be found in two forms, intracellular and extracellular. The intracellular Hsps are induced as a result of stress and have been found to be cytoprotective in many instances due to their chaperone functions in protein folding and in protein degradation. The origin and role of extracellular Hsps is less clear. Although they were suspected originally to be released from damaged cells (necrosis), their presence in most normal individuals rather suggests that they have regulatory functions in circulation. As immunodominant molecules, Hsps can stimulate the immune system, leading to the production of autoantibodies recognizing epitopes shared by microbial and human Hsps. Thus, extracellular Hsps can influence the inflammatory response as evidenced by the production of inflammatory cytokines. Antibodies to Hsps have been found under normal conditions but seem to be increased in certain stresses and diseases. Such antibodies could regulate the inflammatory response positively or negatively. Here, we review the literature on the findings of antibodies to Hsps in situations of environmental or occupational stress and in a number of diseases and discuss their possible significance for the diagnosis, prognosis, or pathogenesis of these diseases.

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.

G(-) anaerobes-reactive CD4+ T-cells trigger RANKL-mediated enhanced alveolar bone loss in diabetic NOD mice

Diabetic patients experience a higher risk for severe periodontitis; however, the underlying mechanism remains unclear. We investigated the contribution of antibacterial T-cell-mediated immunity to enhanced alveolar bone loss during periodontal infection in nonobese diabetic (NOD) mice by oral inoculation with Actinobacillus actinomycetemcomitans, a G(-) anaerobe responsible for juvenile and severe periodontitis. The results show that 1) inoculation with A. actinomycetemcomitans in pre-diabetic NOD mice does not alter the onset, incidence, and severity of diabetes; 2) after A. actinomycetemcomitans inoculation, diabetic NOD mice (blood glucose >200 mg/dl and with severe insulitis) exhibit significantly higher alveolar bone loss compared with pre-diabetic and nondiabetic NOD mice; and 3) A. actinomycetemcomitans-reactive CD4+ T-cells in diabetic mice exhibit significantly higher proliferation and receptor activator of nuclear factor kappaB ligand (RANKL) expression. When diabetic mice are treated with the RANKL antagonist osteoprotegerin (OPG), there is a significant reversal of alveolar bone loss, as well as reduced RANKL expression in A. actinomycetemcomitans-reactive CD4+ T-cells. This study clearly describes the impact of autoimmunity to anaerobic infection in an experimental periodontitis model of type 1 diabetes. Thus, microorganism-reactive CD4+ T-cells and the RANKL-OPG axis provide the molecular basis of the advanced periodontal breakdown in diabetes and, therefore, OPG may hold therapeutic potential for treating bone loss in diabetic subjects at high risk.

Involvement of periodontopathic biofilm in vascular diseases

Oral bacteria inhabit biofilms, which are firm clusters adhering in layers to surfaces and are not easily eliminated by immune responses and are resistant to antimicrobial agents. Dental plaque is one such biofilm. In the past 10 years, subgingival plaque bacteria forming biofilms have been increasingly reported to be involved in systemic diseases. A close relationship between microbial infections and vascular disease has also been reported in the past two decades. The present review discusses the significance of the ecologic characteristics of biofilms formed by periodontopathic bacteria in order to further clarify the associations between periodontal disease and systemic disease. We focus on the relationships between periodontal disease-associated bacteria forming biofilms and vascular diseases including atherosclerosis and carotid coronary stenotic artery disease, and we discuss the direct and indirect effects on vascular diseases of lipopolysaccharides as well as heat shock proteins produced by periodontopathic bacteria.

Oral microbial heat-shock proteins and their potential contributions to infections

The oral cavity is a complex ecosystem in which several hundred microbial species normally cohabit harmoniously. However, under certain special conditions, the growth of some micro-organisms with a pathogenic potential is promoted, leading to infections such as dental caries, periodontal disease, and stomatitis. The physiology and pathogenic properties of micro-organisms are influenced by modifications in environmental conditions that lead to the synthesis of specific proteins known as the heat-shock proteins (HSPs). HSPs are families of highly conserved proteins whose main role is to allow micro-organisms to survive under stress conditions. HSPs act as molecular chaperones in the assembly and folding of proteins, and as proteases when damaged or toxic proteins have to be degraded. Several pathological functions have been associated with these proteins. Many HSPs of oral micro-organisms, particularly periodontopathogens, have been identified, and some of their properties-including location, cytotoxicity, and amino acid sequence homology with other HSPs-have been reported. Since these proteins are immunodominant antigens in many human pathogens, studies have recently focused on the potential contributions of HSPs to oral diseases. The cytotoxicity of some bacterial HSPs may contribute to tissue destruction, whereas the presence of common epitopes in host proteins and microbial HSPs may lead to autoimmune responses. Here, we review the current knowledge regarding HSPs produced by oral micro-organisms and discuss their possible contributions to the pathogenesis of oral infections.

Assessment of periodontal conditions and systemic disease in older subjects

BACKGROUND

An increased risk for periodontitis has been associated both with type-1 or insulin dependent diabetes (IDDM) and with type-2 or non-insulin dependent diabetes (NIDDM).

AIMS

1) To describe and analyze periodontal conditions in older low-income ethnic diverse subjects with or without a diagnosis of diabetes. 2) To assess to what extent diabetes mellitus is associated with periodontal status, and 3) how periodontitis ranks as a coexisting disease among other diseases in subjects with diabetes mellitus.

MATERIAL AND METHODS

Radiographic signs of alveolar bone loss were studied in 1101 older subjects 60-75 years old (mean age 67.6, SD+/-4.7). The number of periodontal sites and the proportions of teeth with probing depth (PD) > or =5 mm, clinical attachment levels (CAL) > or =4 mm were studied in a subset of 701 of the subjects.

RESULTS

IDDM was reported by 2.9% and NIDDM by 9.2% of the subjects. The number of remaining teeth did not differ by diabetic status. The number of sites with PD > or =5 mm and the proportion of PD with > or =5 mm was significantly smaller in the non-diabetic group (chi2=46.8, p<0.01, and chi2=171.1, p<0.001, respectively). Statistical analysis failed to demonstrate group differences for the number and proportions of sites with CAL > or =4 mm and for radiographic findings of alveolar bone loss. Combining all periodontal parameters revealed that the Mantel-Haenszel common odds of having IDDM/NIDDM and periodontitis was 1.8 : 1 (95% CI: 1.1-3.1, p<0.03). The common odds ratio estimate of an association between heart disease and diabetes was 3.6 : 1 (95% CI: 2.1-2.6, p<0.001).

CONCLUSIONS

Probing depth differences between IDDM/NIDDM vs. non-diabetic subjects may reflect the presences of pseudo-pockets and not progressive periodontitis in many subjects with diabetes mellitus. Periodontitis is not a predominant coexisting disease in older subjects with diabetes mellitus.