Severe Periodontitis Enhances Macrophage Activation via Increased Serum Lipopolysaccharide

Cutting Edge: Hematopoietic Stem Cell Expansion and Common Lymphoid Progenitor Depletion Require Hematopoietic-Derived, Cell-Autonomous TLR4 in a Model of Chronic Endotoxin

Hematopoietic stem and progenitors cells (HSPCs) are activated through TLR4 in vitro. However, it remains unclear whether in vivo TLR4 sensing by HSPCs occurs directly or via other cell intermediates. In this study, we examined the cellular mechanisms underlying murine hematopoietic stem cell (HSC) expansion and common lymphoid progenitor (CLP) depletion in a model of chronic low-dose LPS. Using adoptive-transfer approaches, we show that HSC and CLP sensitivity to chronic LPS depends on hematopoietic-derived, cell subset-autonomous TLR4. Like murine progenitors, human HSPCs are activated by TLR4 in vitro. Using humanized mice, a preclinical model relevant to human physiology, we show that persistent endotoxin increases the frequency of Ki-67(+) HSCs and severely depletes CLPs and B precursors. Together, our findings show that murine HSPCs directly respond to endotoxin in vivo and that persistent LPS, a feature of several diseases of global health significance, impairs human lymphopoiesis.

The Two-Way Association of Periodontal Infection with Systemic Disorders: An Overview

Oral cavity that harbors diverse bacterial populations could also act as a site of origin for spread of pathogenic microorganisms to different body sites, particularly in immunocompromised hosts, patients, the elderly, or the underprivileged. A number of recent publications have advocated that patients with periodontal diseases are more susceptible to metabolic endotoxemia, inflammation, obesity, type 2 diabetes, and other related systemic complications, concluding that periodontal diseases could be a potential contributing risk factor for a wide array of clinically important systemic diseases. However, despite a significant increase in the prevalence of periodontal infections and systemic diseases in the past few decades, the fundamental biological mechanisms of connection between these ailments are still not fully explicated. Consequently, the mechanisms by which this bidirectional damage occurs are being explored with a concentric vision to develop strategies that could prevent or control the complications of these ailments. This paper attempts to summarize and hypothesize the diverse mechanisms that hint to a certain connection between the two prevalent chronic situations.

Periodontal innate immune mechanisms relevant to atherosclerosis

Atherosclerosis is a common cardiovascular disease in the USA where it is a leading cause of illness and death. Atherosclerosis is the most common cause for heart attack and stroke. Most commonly, people develop atherosclerosis as a result of diabetes, genetic risk factors, high blood pressure, a high-fat diet, obesity, high blood cholesterol levels, and smoking. However, a sizable number of patients suffering from atherosclerosis do not harbor the classical risk factors. Ongoing infections have been suggested to play a role in this process. Periodontal disease is perhaps the most common chronic infection in adults with a wide range of clinical variability and severity. Research in the past decade has shed substantial light on both the initiating infectious agents and host immunological responses in periodontal disease. Up to 46% of the general population harbors the microorganism(s) associated with periodontal disease, although many are able to limit the progression of periodontal disease or even clear the organism(s) if infected. In the last decade, several epidemiological studies have found an association between periodontal infection and atherosclerosis. This review focuses on exploring the molecular consequences of infection by pathogens that exacerbate atherosclerosis, with the focus on infections by the periodontal bacterium Porphyromonas gingivalis as a running example.

P. gingivalis lipopolysaccharide intensifies inflammation post-myocardial infarction through matrix metalloproteinase-9

Periodontal disease (PD) strongly correlates with increased mortality post-myocardial infarction (MI); however, the underlying mechanisms are unknown. Matrix metalloproteinase (MMP)-9 levels directly correlate with dysfunction and remodeling of the left ventricle (LV) post-MI. Post-MI, MMP-9 is produced by leukocytes and modulates inflammation. We have shown that exposure to Porphyromonas gingivalis lipopolysaccharide (PgLPS), an immunomodulatory molecule identified in PD patients, increases LV MMP-9 levels in mice and leads to cardiac inflammation and dysfunction. The aim of the study was to determine if circulating PgLPS exacerbates the LV inflammatory response post-MI through MMP-9 dependent mechanisms. We exposed wild type C57BL/6J and MMP-9(-/-) mice to PgLPS (ATCC 33277) for a period of 28 days before performing MI, and continued to deliver PgLPS for up to 7 days post-MI. We found systemic levels of PgLPS 1) increased MMP-9 levels in both plasma and infarcted LV resulting in reduced wall thickness and increased incidence of LV rupture post-MI and 2) increased systemic and local macrophage chemotaxis leading to accelerated M1 macrophage infiltration post-MI and decreased LV function. MMP-9 deletion played a protective role by attenuating the inflammation induced by systemic delivery of PgLPS. In conclusion, MMP-9 deletion has a cardioprotective role against PgLPS exposure, by attenuating macrophage mediated inflammation.

LPS-induced inflammatory response after therapy of aggressive periodontitis

We have reported a lipopolysaccharide (LPS)-induced hyper-inflammatory response in localized aggressive periodontitis (LAP). It is unknown whether treatment is able to modulate this LPS responsiveness. Fifty-nine individuals with LAP were treated by mechanical debridement and systemic antibiotics. Clinical parameters and cyto/chemokine responsiveness of whole blood stimulated with Porphyromonas gingivalis or Escherichia coli LPS were monitored at baseline and 3, 6, and 12 months post-treatment. Overall, clinical parameters were improved following treatment. Additionally, P. gingivalis LPS induction of eotaxin, IFNγ, IL10, IL12p40, IL1β, IL6, IP10, MCP1, MIP1α, GM-CSF, and TNFα was significantly decreased (p < .05). Similarly, induction of eotaxin, INFγ, IL10, IL12p40, GM-CSF, and TNFα by E. coli LPS was also reduced post-treatment. These reductions correlated with decreases in clinical parameters. Importantly, these reductions in LPS responsiveness were most robust at 3 months, and some lost significance at 6 to 12 months post-treatment. In conclusion, LPS-induced hyper-inflammatory response in LAP can be partially modulated by periodontal therapy. Conversely, rebound in the hyper-responsiveness of some mediators, in the presence of improved clinical parameters, suggests that this phenotype could be partially influenced by a genetic trait and play a role in future disease recurrence (ClinicalTrials.gov, NCT01330719).

Very low density lipoproteins derived from periodontitis patients facilitate macrophage activation via lipopolysaccharide function

OBJECTIVE

Periodontitis, a chronic oral infection caused mainly by gram-negative bacteria, induces endotoxemia and associates with the risk for atherosclerosis. We investigated the effect of periodontal treatment on proatherogenic properties of very low density lipoproteins (VLDL).

METHODS

VLDL were isolated from 30 systemically healthy periodontitis patients before (pre-treatment) and 3 months after treatment (post-treatment). The mass compositions were analyzed, and VLDL-induced changes in cellular cholesterol content and expression of selected genes of human THP-1 macrophages were measured.

RESULTS

Periodontal treatment decreased the local inflammation in the periodontium, but did not have a significant effect on C-reactive protein (CRP) levels, VLDL composition, or VLDL potential to induce cholesterol uptake or gene expression by the macrophages. Incubation of macrophages in the presence of VLDL resulted in more than twofold increase in their cellular cholesterol content. Uptake of VLDL with ensuing macrophage cholesterol accumulation correlated positively with VLDL-associated lipopolysaccharide (LPS) activity (r=0.436, P=.016) and apolipoprotein E content (r=0.374, P=.046). Pre-treatment VLDL derived from the patients with high CRP levels displayed higher LPS activity than that of VLDL derived from patients with low CRP (above vs. below median, P=.007). In addition, pre-treatment VLDL isolated from patients with high systemic inflammation induced higher relative mRNA expression of CD14, TNF-α, MCP-1, and IL-6 in the macrophages.

CONCLUSION

Inflammation and endotoxemia induced by severe periodontitis may increase VLDL-dependent macrophage activation and cellular cholesterol accumulation, and thereby atherogenesis.

Oxidative burst intensity of peripheral phagocytic cells and periodontitis in Down syndrome

BACKGROUND

This study investigated the oxidative burst function of peripheral phagocytic cells (granulocytes and monocytes) and assessed the relation between oxidative burst and periodontal status in adult individuals with Down syndrome (DS) vs. other groups.

METHODS

Of 55 DS individuals (18-56 years old), 74 individuals with mental retardation (MR) and 88 medically healthy controls (HC) participated in the study. The MR and HC groups were age, race and gender matched with the DS group. Gingival index, plaque index, probing depth, attachment level and bleeding on probing were recorded for each subject. Whole blood was collected for granulocyte/monocyte oxidative burst tests. Oxidative burst was determined by flow cytometry in terms of percentage of cells actively involved in oxidative burst, and oxidative intensity (magnitude of ROIs per cell).

RESULTS

The basal oxidative burst intensity of DS granulocytes was higher than that of HC and MR granulocytes (p = 0.05). The Escherichia coli stimulated oxidative burst intensity of DS monocytes was higher than that of HC and MR monocytes (p = 0.05). Regression analysis controlling for age, sex, race and plaque levels showed a significant association between monocyte oxidative burst intensity and loss of periodontal attachment in DS subjects (p < 0.01). Regression analysis also showed a significant association between granulocyte oxidative burst intensity and bleeding on probing in all subjects (p < 0.05).

CONCLUSIONS

Oxidative burst activity of peripheral monocytes and granulocytes is elevated in DS affected individuals and may contribute to periodontal tissue inflammation and loss of periodontal attachment in this susceptible group.

A. actinomycetemcomitans LPS Enhances Foam Cell Formation Induced by LDL

The objective of this study was to examine whether native low-density lipoprotein (LDL) induces foam cell formation by macrophages and to examine the effect of lipopolysaccharide (LPS) on native LDL-induced foam cell formation by macrophages in vitro. RAW 264.7 cells were cultured with LDL or high-density lipoprotein (HDL) in the presence of LPS derived from Aggregatibacter actinomycetemcomitans. Foam cell formation was determined by staining with Oil-red-O to visualize cytoplasmic lipid droplet accumulation. The expression of LDL-receptor and the degree of internalization of FITC-conjugated LDL in RAW 264.7 cells were examined by immunofluorescence microscopy. The images were digitally recorded and analyzed with Image J software. Statistical analysis was performed by JMP software. Foam cell formation was induced by the addition of native LDL in dose- and time-dependent manners, whereas HDL showed no effect. LPS enhanced the foam cell formation induced by native LDL. In addition, LPS stimulated the expression of LDL-receptor protein on RAW 264.7 cells and enhanced the internalization of LDL. The enhancement of foam cell formation induced by LPS and LDL was inhibited by the depolymerizing agent nocodazole and amiloride analog 5-(N-ethyl-N-isoprophyl) amiloride (EIPA). Our findings indicate that LPS plays an important role in foam cell formation by LDL-stimulated macrophages.

Minocycline hydrochloride nanoliposomes inhibit the production of TNF-α in LPS-stimulated macrophages

Background

As an adjunctive treatment of chronic periodontitis, it seems that the application of periocline or the other antimicrobials is effective against periodontopathogens. In this study, nanoliposomes were investigated as carriers of minocycline hydrochloride and the inhibition effects of minocycline hydrochloride nanoliposomes on the proliferation and lipopolysaccharide (LPS)-stimulated production of tumor necrosis factor-α (TNF-α) of macrophages were elucidated.

Methods

After stimulation with 10 μg/mL LPS, murine macrophages (ANA-1) were treated with 10, 20, 40, 50 and 70 μg/mL 2% minocycline hydrochloride nanoliposomes, minocycline hydrochloride solution, and periocline for 6, 12, 24, 48 and 60 hours, respectively. A tetrazolium (MTT) assay was used to evaluate macrophages cell proliferation rate and the levels of TNF-α mRNA were measured by SYBR Green Real Time PCR.

Results

Ten to 70 μg/mL 2% minocycline hydrochloride nanoliposomes, minocycline hydrochloride solution, and periocline showed dose- and time-dependent inhibition of ANA-1 proliferation. Minocycline hydrochloride nanoliposomes showed dose- and ratio-dependent inhibition of LPS-stimulated TNF-α secretion of ANA-1. The inhibition effect of 10 μg/mL minocycline hydrochloride nanoliposomes was significantly better than that of two positive control groups, and equated to that of 60 or 70 μg/mL periocline. The expression of TNF-α mRNA in experimental group continued to reduce linearly with time.

Conclusion

All three preparations of minocycline hydrochloride showed dose- and time-dependent inhibition of proliferation of ANA-1. Minocycline hydrochloride nanoliposomes have stronger and longer inhibition effect on LPS-stimulated TNF-α secretion of macrophages cell than minocycline hydrochloride solution and periocline.

Recognition of Porphyromonas gingivalis gingipain epitopes by natural IgM binding to malondialdehyde modified low-density lipoprotein

Objective

Increased risk for atherosclerosis is associated with infectious diseases including periodontitis. Natural IgM antibodies recognize pathogen-associated molecular patterns on bacteria, and oxidized lipid and protein epitopes on low-density lipoprotein (LDL) and apoptotic cells. We aimed to identify epitopes on periodontal pathogen Porphyromonas gingivalis recognized by natural IgM binding to malondialdehyde (MDA) modified LDL.

Methods and Results

Mouse monoclonal IgM (MDmAb) specific for MDA-LDL recognized epitopes on P. gingivalis on flow cytometry and chemiluminescence immunoassays. Immunization of C57BL/6 mice with P. gingivalis induced IgM, but not IgG, immune response to MDA-LDL and apoptotic cells. Immunization of LDLR^−/− mice with P. gingivalis induced IgM, but not IgG, immune response to MDA-LDL and diminished aortic lipid deposition. On Western blot MDmAb bound to P. gingivalis fragments identified as arginine-specific gingipain (Rgp) by mass spectrometry. Recombinant domains of Rgp produced in E. coli were devoid of phosphocholine epitopes but contained epitopes recognized by MDmAb and human serum IgM. Serum IgM levels to P. gingivalis were associated with anti-MDA-LDL levels in humans.

Conclusion

Gingipain of P. gingivalis is recognized by natural IgM and shares molecular identity with epitopes on MDA-LDL. These findings suggest a role for natural antibodies in the pathogenesis of two related inflammatory diseases, atherosclerosis and periodontitis.

Phagocytic cell activity and periodontitis in Down syndrome

BACKGROUND

This study investigated the phagocytic function of peripheral granulocytes and monocytes from adult individuals with Down syndrome (DS) and assessed the relation between phagocytic function and periodontal status.

METHODS

Fifty-five DS individuals (18-56 years old), 74 mentally retarded individuals, and 88 medically healthy controls (HC) participated in the study. Gingival inflammation index, plaque index, probing depth, periodontal attachment level (AL), and bleeding on probing were taken for each subject. Whole blood was collected for granulocyte/monocyte phagocytosis tests. Phagocytic function was determined by flow cytometry in terms of percentage of cells actively involved in phagocytosis, and phagocytic intensity (magnitude of the bacterial staining per cell).

RESULTS

Phagocytic intensity of both granulocytes and monocytes was comparable in HC and DS subjects. While AL was directly related to phagocytic intensity of both granulocytes (r = 0.14, P = 0.03) and monocytes (r = 0.2, P = 0.003) in all subjects, this relationship was stronger in DS than in other subjects, even after controlling for known risk factors for periodontitis (P < 0.05). Monocyte phagocytic intensity was the only necessary predictor of AL (P = 0.003), indicating a similar relationship between AL and phagocytic activity in either cell type.

CONCLUSIONS

While granulocyte and monocyte phagocytic intensities are similar in Down and non-DS individuals, phagocytic intensity was associated with more AL in DS than non-DS individuals.

Local inflammatory markers and systemic endotoxin in aggressive periodontitis

While much research has focused on local and systemic factors contributing to periodontal disease, little is known regarding mechanisms linking these factors. We have previously reported a systemic hyper-inflammatory response to bacterial endotoxin in localized aggressive periodontitis (LAP). The objectives of this study were to delineate cyto/chemokines in gingival crevicular fluid (GCF) and evaluate systemic levels of endotoxin associated with LAP. Clinical parameters, GCF, and peripheral blood were collected from: 34 LAP, 10 healthy siblings, and nine healthy unrelated control individuals. Cyto/chemokines were quantified in GCF, systemic endotoxin levels were quantified in plasma, and correlation analysis was performed among all parameters. Nine mediators were elevated in LAP diseased sites as compared with healthy sites (TNFα, INFγ, IL1β, IL2, IL6, IL10, Il12p40, GMCSF, and MIP1α, p < 0.001), while MCP1, IL4, and IL8 were elevated in healthy sites (p < 0.01). Four- to five-fold-higher endotoxin levels were detected in LAP plasma compared with that from healthy participants (p < 0.0001), which correlated with all clinical parameters and most cyto/chemokines analyzed. In conclusion, higher systemic levels of endotoxin were found in LAP, which correlates with an exacerbated local inflammatory response and clinical signs of disease. (Clinicaltrials.gov number, NCT01330719).

Alterations of Serum Lipid and Inflammatory Cytokine Profiles in Patients with Coronary Heart Disease and Chronic Periodontitis: A Pilot Study

Serum lipid and inflammatory cytokine profiles were assessed in 124 in-patients with coronary heart disease (CHD) (CHD group) and 43 inpatients with no evidence of CHD (control group). In all patients, research questionnaires and examinations of periodontal health were conducted and venous blood samples were analysed. Both groups were divided into two subgroups according to the presence or absence of chronic periodontitis in individual patients. The prevalence of chronic periodontitis was higher in patients from the CHD group than in the control group. Levels of total cholesterol, triglycerides, low-density lipoprotein, oxidized low-density lipoprotein, high-sensitivity C-reactive protein, interleukin-6 and tumour necrosis factor-a were significantly higher in CHD patients with chronic periodontitis than in those without periodontitis. In conclusion, chronic periodontitis may be associated with CHD.

Stimulants of Toll-like receptors 2 and 4 are elevated in saliva of periodontitis patients compared with healthy subjects

AIM

Because the absorption of stimulants of Toll-like receptor (TLR)2 and TLR4 from the gastrointestinal tract into the circulation has been proposed to promote the development of atherosclerosis and insulin resistance, we aimed to quantify the abundance of stimulants of TLR2 and TLR4 in human saliva.

METHODS

A recently developed bioassay based upon measurement of NF-κB activation in TLR-deficient human embryonic kidney (HEK)-293 cells transfected with human TLR2 or TLR4 and calibrated with synthetic bacterial lipopeptide (Pam(3) CSK(4) ) or Escherichia coli lipopolysaccharide (LPS), was used to establish the normal range of TLR stimulants in saliva of 20 healthy subjects and 20 subjects with periodontal disease.

RESULTS

Median soluble stimulants of TLR2 and TLR4 were significantly higher in saliva of periodontitis patients compared with saliva of healthy subjects; 3450 versus 77 ng/ml Pam(3) CSK(4) equivalents (p<0.0001) and 138 versus 7 ng/ml LPS equivalents, respectively (p<0.0001). Salivary TLR stimulant levels remained relatively stable in healthy subjects over several days. Six strains of oral Gram-negative bacteria, including Tannerella forsythensis, Lysobacter enzymogenes, Prevotella intermedia, Prevotella oris and Porphyromonas gingivalis, from a panel of nine examined did not stimulate TLR4-dependent signalling.

CONCLUSIONS

Elevated salivary TLR stimulants may represent a novel mechanism by which periodontitis increases the risk of developing cardiovascular disease and insulin resistance.

Endotoxemia is associated with an increased risk of incident diabetes

OBJECTIVE

Diabetes is accompanied with a chronic low-grade inflammation, which may in part be mediated by endotoxins derived from Gram-negative bacteria.

RESEARCH DESIGN AND METHODS

We investigated in a population-based cohort whether endotoxemia is associated with clinically incident diabetes. The serum endotoxin activity was measured by limulus assay from the FINRISK97 cohort comprising 7,169 subjects aged 25-74 years and followed up for 10 years.

RESULTS

Both the subjects with prevalent diabetes (n = 537) and those with incident diabetes (n = 462) had higher endotoxin activity than the nondiabetic individuals (P < 0.001). The endotoxin activity was significantly associated with increased risk for incident diabetes with a hazard ratio 1.004 (95% CI 1.001-1.007; P = 0.019) per unit increase resulting in a 52% increased risk (P = 0.013) in the highest quartile compared with the lowest one. The association was independent of diabetes risk factors: serum lipids, γ-glutamyl transferase, C-reactive protein, BMI, and blood glucose. Furthermore, the association of endotoxemia with an increased risk of incident diabetes was independent of the metabolic syndrome as defined either by the National Cholesterol Educational Program-Adult Treatment Panel III or the International Diabetes Federation. Endotoxin activity was linearly related (P < 0.001) to the number of components of the metabolic syndrome.

CONCLUSIONS

Both prevalent and incident diabetes were associated with endotoxemia, which may link metabolic disorders to inflammation. The results suggest that microbes play a role in the pathogenesis of diabetes.

Adipocyte-macrophage interaction may mediate LPS-induced low-grade inflammation: Potential link with metabolic complications

Chronic low-grade infection has been suggested to be associated with metabolic disorder such as diabetes. However, the molecular mechanism underlying this important association is largely unknown. The only clue established so far is that many subjects exhibit elevated levels of C-reactive protein as measured by highly sensitive assay. Here, we hypothesized that adipocyte–macrophage interaction plays a key role in amplifying such low grade infection to the level of influencing metabolic disorders. The presence of macrophages in abdominal adipose tissues was investigated by immunohistochemistry. To see whether molecules associated with acute phase protein, LPS signaling, and persistent recruitment of monocytes, are produced at higher amounts in adipocytes co-cultured with macrophages stimulated with low concentration of LPS (1 ng/ml), we measured serum amyloid A (SAA), LPS binding protein (LBP), soluble CD14 (sCD14), and RANTES levels in culture supernatant of co-cultures. Lastly, we investigated in vivo effect of low-grade LPS infusion on the production of these molecules using obese model mice. The macrophages were certainly identified in abdominal adipose tissues. Investigated molecules, especially LBP, SAA, and RANTES were produced at higher amounts in co-cultures stimulated with LPS compared with the cells without LPS. The ob/ob, and high-fat diet-induced obesity mice produced higher amounts of LBP, SAA, and RANTES one day after LPS infusion (1 ng/ml/g body weight) compared with ob/– and normal-fat fed control mice. Thus, adipocytes and infiltrated macrophages, and their interaction with low endotoxin stimulation appear to play an important role in amplifying and maintaining LPS-induced low-grade inflammation.

Short-term effects of periodontal therapy as an adjunct to anti-lipemic treatment

OBJECTIVE

This study was conducted to assess the effect of improved periodontal health following periodontal treatment on metabolic lipid control of patients on anti-lipemic treatment.

MATERIALS AND METHODS

The study population consisted of 20 patients aged 34-62 years with diagnoses of hyperlipidemia and chronic periodontitis. All patients used statin to treat their elevated levels of low-density lipoprotein cholesterol. Blood samples were obtained for measurement of serum lipids, fasting plasma glucose, and high sensitive C-reactive protein. Periodontal parameters, including plaque index, gingival index, probing pocket depth, clinical attachment level, and percentage of bleeding on probing, were evaluated. All parameters were assessed in each subject at baseline, after 3 months as a control (at the time of periodontal treatment), and 3 months after the non-surgical periodontal treatment that included scaling and root planning.

RESULTS

All lipid parameters decreased after the periodontal treatment, but only the decreases in total cholesterol and low-density lipoprotein cholesterol levels reached statistical significance compared to baseline (P = 0.002 and P = 0.003, respectively).

CONCLUSION

Improved periodontal health may influence metabolic control of hyperlipidemia and could be considered as an adjunct to the standard measures of hyperlipidemic patient care.

Soluble CD14 induces cytokine release by human oral epithelial cells

BACKGROUND AND OBJECTIVE

The epithelial cell barrier is the first line of host defense against bacterial aggression in periodontal sites. In view of the fact that oral epithelial cells do not express membrane CD14 and that high levels of the soluble form of the CD14 receptor have been detected in the gingival crevicular fluid of patients with periodontitis, we investigated the effects of recombinant soluble CD14 (rsCD14), alone and in combination with Aggregatibacter actinomycetemcomitans lipopolysaccharide (LPS) on the inflammatory response of human oral epithelial cells.

MATERIAL AND METHODS

The oral epithelial cell line GMSM-K was stimulated with rsCD14, alone or in combination with A. actinomycetemcomitans LPS, and the levels of the inflammatory mediators interleukin (IL)-6, IL-8 and chemokine (C-C motif) ligand 5 (CCL5) were determined using ELISAs. Activation of the transcription factors nuclear factor-κB (NF-κB) and activator protein-1 was also monitored using ELISAs.

RESULTS

rsCD14 significantly induced the secretion of IL-6, IL-8 and CCL5 by oral epithelial cells. The combination of rsCD14 and A. actinomycetemcomitans LPS augmented this effect. Activation of the NF-κB pathway was significantly increased in epithelial cells treated with rsCD14 compared with a nonstimulated control, whereas there was no effect on the activation of activator protein-1.

CONCLUSION

rsCD14 stimulated the inflammation cascade in oral epithelial cells, both alone or when associated with bacterial LPS, through an NF-κB-dependent pathway. This suggests that the presence of soluble CD14 in periodontitis lesions may contribute to the inflammatory process of periodontal disease.

Systemic endotoxin levels in chronic indolent periodontal infections

BACKGROUND AND OBJECTIVE

Periodontal disease has been linked with an increased risk of various systemic diseases. A plausible biologic explanation for this link includes the opportunity for oral pathogens to translocate to the circulation as a result of breakdown in integrity of the oral epithelium. This study refined a methodology used to detect endotoxin activity in the serum of subjects with indolent periodontal infections.

MATERIAL AND METHODS

The QCL Kinetic Chromogenic Assay (Cambrex) is a kinetic measure of endotoxin activity. Sera from 211 pregnant women with periodontitis enrolled in the Obstetrics and Periodontal Therapy Trial were used to develop the assay further and to evaluate the detection of endotoxin activity that might accompany a low-level bacteremia in chronic periodontitis.

RESULTS

We optimized the system to increase the sensitivity and reproducibility of the assay. The refined system was able to detect endotoxin activity in serum at > 0.0125 EU/mL. At baseline (13-16 wk of gestation), 35.5% of the women were positive for endotoxin activity (1.62 +/- 2.21; range: 0.38-15 EU/mL).

CONCLUSION

This report describes a sensitive measure of endotoxin activity in serum. The procedure allowed us to document levels of this microbial virulence factor in serum of individuals with indolent infections such as periodontal disease.

Lipoproteins and lipoprotein metabolism in periodontal disease

A growing body of evidence indicates that the incidence of atherosclerosis is increased in subjects with periodontitis - a chronic infection of the oral cavity. This article summarizes the evidence that suggests periodontitis shifts the lipoprotein profile to be more proatherogenic. LDL-C is elevated in periodontitis and most studies indicate that triglyceride levels are also increased. By contrast, antiatherogenic HDL tends to be low in periodontitis. Periodontal therapy tends to shift lipoprotein levels to a healthier profile and also reduces subclinical indices of atherosclerosis. In summary, periodontal disease alters lipoprotein metabolism in ways that could promote atherosclerosis and cardiovascular disease.

Involvement of adhesion molecule in in vitro plaque-like formation of macrophages stimulated with Aggregatibacter actinomycetemcomitans lipopolysaccharide

BACKGROUND AND OBJECTIVE

Inflammatory agents, such as lipopolysaccharide (LPS), in periodontal pockets may promote atherogenesis by activating leukocytes. In our previous study, we developed a microchannel chip to observe the cell adhesion process in a fluid system. The objective of this investigation was to examine the mechanism by which periodontopathic bacterial LPS enhances plaque-like formation on a microchannel chip.

MATERIAL AND METHODS

To evaluate the effect of Aggregatibacter actinomycetemcomitans LPS on the expression of adhesion molecules, e.g. intercellular adhesion molecule 1 (ICAM-1), lymphocyte function-associated antigen 1 (LFA-1) and L-selectin, on the surface of murine macrophage RAW264.7 cells, the expression of each adhesion molecule was examined by flow cytometry and western blot analysis. Moreover, a flow test on the microchannel chip involving anti-adhesion molecule antibodies was conducted to clarify which adhesion molecule is related to plaque-like formation of RAW264.7 cells.

RESULTS

The expressions of ICAM-1 and LFA-1 on the surface of RAW 264.7 cells increased following 12 h culture with LPS; L-selectin expression was unaffected. An increase in ICAM-1 expression was also confirmed by western blot analysis. The flow test revealed that anti-ICAM-1 antibody inhibited plaque-like formation of LPS-stimulated macrophages on the micropillars of the microchannel chip.

CONCLUSION

These findings indicate that ICAM-1 plays an important role in plaque-like formation of LPS-stimulated macrophages. Our microchannel chip is a suitable tool for the investigation of etiological factors of atherosclerosis, including periodontitis, in vitro.

Minimal penetration of lipopolysaccharide across the murine blood-brain barrier

LPS given peripherally or into the brain induces a neuroinflammatory response. How peripheral LPS induces its effects on brain is not clear, but one mechanism is that LPS crosses the blood-brain barrier (BBB). Alternatively, LPS acts outside the BBB by stimulating afferent nerves, acting at circumventricular organs, and altering BBB permeabilities and functions. Here, we labeled LPS with radioactive iodine (I-LPS) and coinjected it with radioactively labeled albumin (I-Alb) which acted as a vascular space marker. Measurable amounts of I-LPS associated with the BBB, most reversibly bound to brain endothelia. Brain endothelia also sequestered small amounts of I-LPS and about 0.025% of an intravenously injected dose of I-LPS crossed the BBB to enter the CNS. Disruption of the BBB with repeated injections of LPS did not enhance I-LPS uptake. Based on dose-response curves in the literature of the amounts of LPS needed to stimulate brain neuroimmune events, it is unlikely that enough peripherally administered LPS enters the CNS to invoke those events except possibly at the highest doses used and for the most sensitive brain functions. I-LPS injected into the lateral ventricle of the brain entered the circulation with the reabsorption of cerebrospinal fluid (bulk flow) as previously described. In conclusion, brain uptake of circulating I-LPS is so low that most effects of peripherally administered LPS are likely mediated through LPS receptors located outside the BBB.

ADRP/ADFP and Mal1 expression are increased in macrophages treated with TLR agonists

Activation of macrophages by TLR agonists enhances foam cell formation, but the underlying mechanisms are not understood. We examined the effects of TLR agonists on ADRP/ADFP, a protein associated with forming lipid droplets, and Mal1 a fatty acid-binding protein, in two mouse macrophage cell lines and human monocytes. Low doses of LPS, a TLR4 agonist increased both mRNA and protein levels of ADRP/ADFP and Mal1 in RAW 264.7 macrophages. Following pretreatment with Intralipid, fatty acids, or acetyl-LDL to increase triglyceride or cholesterol ester storage, LPS treatment still increased ADRP/ADFP and Mal1 mRNA levels. LPS also induced ADRP/ADFP and Mal1 in J774 macrophages and ADRP/ADFP in human monocytes. Zymosan, a fungal product that activates TLR2, poly-I:C, a viral mimetic that activates TLR3, and imiquimod, a TLR7 agonist, also increased ADRP/ADFP. Zymosan, but not poly-I:C or imiquimod, induced Mal1. In contrast, neither gene was induced by TNFalpha, IL-1beta, IL-6, or interferon-gamma. Thus TLR agonists induce ADRP/ADFP and Mal1, which likely contributes to macrophage triglyceride and cholesterol ester storage leading to foam cell formation.

The blood-brain barrier and immune function and dysfunction

The blood-brain barrier (BBB) is the monocellular interface that divides the peripheral circulation from direct contact with the central nervous system (CNS). This interface consists of several parallel barriers that include most notably the capillary bed of the CNS and the choroid plexus. These barriers at one level create the dichotomy between the circulating factors of the immune system and the components of the CNS only to regulate interactions between the immune and central nervous systems at other levels. The BBB is thus an integral part of the neuroimmune axis. Here, we will consider four aspects of BBB-neuroimmune interactions: BBB disruption as mediated by LPS and cytokines, cytokine transport across the BBB, immune cell trafficking, and effects of lipopolysaccharide (LPS) on various functions of the BBB.

Strong and persistent microbial and inflammatory stimuli overcome the genetic predisposition to higher matrix metalloproteinase-1 (MMP-1) expression: a mechanistic explanation for the lack of association of MMP1-1607 single-nucleotide polymorphism genotypes with MMP-1 expression in chronic periodontitis lesions

AIMS

Our objective was to evaluate the association between the MMP1-1607 single-nucleotide polymorphism (SNP), periodontopathogens and inflammatory cytokines with matrix metalloproteinase-1 (MMP-1) mRNA levels in vitro and in vivo.

MATERIALS AND METHODS

This study investigated the influence of genetic (MMP1-1607 SNP), microbial (Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Actinobacillus actinomycetemcomitans) and inflammatory [tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta)] factors on the determination of MMP-1 mRNA levels in periodontal tissues of non-smoker chronic periodontitis (CP, N=178) and control (C, N=190) groups. The effects of single and repeated lipopolysaccharide (LPS) and inflammatory cytokine stimulation of macrophages with distinct MMP1-1607 SNP genotypes were also investigated.

RESULTS

In healthy tissues, the MMP1-1607 2G allele was associated with higher MMP-1 levels while in CP MMP-1 levels were associated with the presence and load of periodontopathogens, and also with TNF-alpha and IL-1beta expression irrespective of the MMP1-1607 genotype. In vitro data demonstrate that in 2G macrophages low- and intermediate-dose LPS and TNF-alpha+IL-1beta stimulation was associated with increased MMP-1 expression, while strong and repeated stimulation resulted in higher MMP-1 levels irrespective of the MMP1-1607 genotype.

CONCLUSION

Our data demonstrate a limited role for MMP1-1607 SNP in periodontitis, where the extensive chronic antigenic challenge exposure overcomes the genetic control and plays a major role in the determination of MMP-1 expression.

Effects of improvement in periodontal inflammation by toothbrushing on serum lipopolysaccharide concentration and liver injury in rats

OBJECTIVE

Periodontitis increases the serum lipopolysaccharide level, contributing to liver injury. Toothbrushing improves periodontitis and may also affect serum lipopolysaccharide concentration and periodontitis-induced liver injury. The purpose of the present study was to examine whether the improvement in periodontal inflammation by toothbrushing clinically affects the serum lipopolysaccharide level and hepatic pathological changes in rat periodontitis.

MATERIAL AND METHODS

Thirty male Wistar rats were divided into 5 groups, 2 groups receiving topical application of pyrogen-free water to the gingival sulcus for 4 or 8 weeks. The next 2 groups received topical application of lipopolysaccharide and proteases for 4 or 8 weeks. The last group received topical application of lipopolysaccharide and proteases for 8 weeks, and the palatal gingiva was brushed with a powered toothbrush once a day for 4 weeks prior to the end of the experimental period.

RESULTS

Topical application of lipopolysaccharide and proteases induced not only periodontal inflammation but also an elevation in the serum lipopolysaccharide concentration, with increasing hepatic inflammation, steatosis and 8-hydroxydeoxyguanosine levels in a time-dependent manner. The rats that received gingival stimulation showed decreased polymorphonuclear leukocyte infiltration and collagen loss levels in the periodontal lesions. Furthermore, this group also showed a decrease in serum lipopolysaccharide concentration and hepatic inflammation, steatosis and 8-hydroxydeoxyguanosine levels, compared with the group receiving no treatment.

CONCLUSIONS

Toothbrushing promoted healing of periodontal lesions, decreased serum lipopolysaccharide concentration and suppressed liver injury in a rat periodontitis model.

Endotoxin levels are associated with high-density lipoprotein, triglycerides, and troponin in patients with acute coronary syndrome and angina: possible contributions from periodontal sources

BACKGROUND

Recent studies have reported an association between poor dental health and acute coronary syndrome (ACS). The purpose of this study was to correlate the presence of periodontitis with serum endotoxin/lipopolysaccharides (LPS), lipid profiles, troponin, and immunoglobulin G (IgG) antibody to Porphyromonas gingivalis in control patients or patients with ACS or angina at the time of hospital admission.

METHODS

Blood samples from 194 subjects presenting with ACS, angina, or non-cardiac chest pain were analyzed for endotoxin/LPS (Limulus amebocyte lysate assay), lipid profile, troponin, and IgG antibody to P. gingivalis. Data were collected from hospital charts and dental records, and health questionnaire responses.

RESULTS

Subjects with ACS or angina were more likely to have poor oral care, fewer remaining teeth, and increased alveolar radiographic bone loss compared to subjects with chest pain. In all subjects, endotoxin/LPS and IgG antibody to P. gingivalis tended to increase in association with increased radiographic bone loss. Endotoxin/LPS increased directly with triglyceride and troponin levels (P = 0.04 and P = 0.006, respectively) and inversely with high-density lipoprotein (HDL) levels (P = 0.002). IgG antibody to P. gingivalis levels was directly correlated with very low-density lipoprotein (P = 0.03) and triglycerides (P = 0.06) and inversely with low-density lipoprotein (P = 0.01).

CONCLUSIONS

Results showed more alveolar bone loss in patients with cardiac disease than in patients without cardiac disease, but there was no difference between the groups in the serum levels of endotoxin/LPS or IgG antibody to P. gingivalis. However, there were associations between endotoxin/LPS and levels of serum triglycerides, troponin, and HDL.

Lipopolysaccharide associates with pro-atherogenic lipoproteins in periodontitis patients

INTRODUCTION

Periodontitis patients are known to suffer from endotoxemia, which may be among the major risk factors for atherosclerosis. In health, lipopolysaccharide (LPS) is mainly carried with high density lipoprotein (HDL) particles. Shift of LPS toward lipoproteins with lower densities may result in less effective endotoxin scavenging. Our aim was to determine plasma LPS activity and lipoprotein-distribution before and after treatment in periodontitis patients.

PATIENTS AND METHODS

Very low and intermediate density (VLDL-IDL), low density (LDL), HDL 2, HDL3, and lipoprotein-deficient plasma (LPDP) were isolated by sequential ultracentrifugation. Patients included 34 subjects aged 53.5 +/- 8.3 years, before and 6 months after periodontal treatment.

RESULTS

The mean LPS distribution decreased among lipoprotein classes as follows: VLDL-IDL 41.3 +/- 12.1%, LPDP 25.0 +/- 7.0%, HDL3 13.1 +/- 5.2%, LDL 11.5 +/- 3.7%, and HDL2 9.2 +/- 2.8%. Plasma and VLDL-IDL-associated LPS correlated positively, and LDL- and HDL-associated LPS negatively with clinical periodontal parameters and plasma cytokine concentrations. Mean plasma LPS activity increased after periodontal treatment from 44.0 +/- 17.0 to 55.7 +/- 24.2 EU/ml (P = 0.006). No significant changes were found in LPS lipoprotein distribution and lipoprotein compositions after the treatment.

CONCLUSIONS

Endotoxemia increases with severity of periodontitis. In periodontitis, LPS associates preferentially with the pro-atherogenic VLDL-IDL fraction. Periodontal treatment has only minor effects on plasma LPS activity or distribution, which reflects persistence of the disease.

Proinflammatory effect in whole blood by free soluble bacterial components released from planktonic and biofilm cells

BACKGROUND

Aggregatibacter actinomycetemcomitans is an oral bacterium associated with aggressive forms of periodontitis. Increasing evidence points to a link between periodontitis and cardiovascular diseases, however, the underlying mechanisms are poorly understood. This study investigated the pathogenic potential of free-soluble surface material, released from live planktonic and biofilm A. actinomycetemcomitans cells.

RESULTS

By employing an ex vivo insert model (filter pore size 20 nm) we demonstrated that the A. actinomycetemcomitans strain D7S and its derivatives, in both planktonic and in biofilm life-form, released free-soluble surface material independent of outer membrane vesicles. This material clearly enhanced the production of several proinflammatory cytokines (IL-1 beta, TNF-alpha, IL-6, IL-8, MIP-1 beta) in human whole blood, as evidenced by using a cytokine antibody array and dissociation-enhanced-lanthanide-fluorescent-immunoassay. In agreement with this, quantitative real-time PCR indicated a concomitant increase in transcription of each of these cytokine genes. Experiments in which the LPS activity was blocked with polymyxin B showed that the stimulatory effect was only partly LPS-dependent, suggesting the involvement of additional free-soluble factors. Consistent with this, MALDI-TOF-MS and immunoblotting revealed release of GroEL-like protein in free-soluble form. Conversely, the immunomodulatory toxins, cytolethal distending toxin and leukotoxin, and peptidoglycan-associated lipoprotein, appeared to be less important, as evidenced by studying strain D7S cdt/ltx double, and pal single mutants. In addition to A. actinomycetemcomitans a non-oral species, Escherichia coli strain IHE3034, tested in the same ex vivo model also released free-soluble surface material with proinflammatory activity.

CONCLUSION

A. actinomycetemcomitans, grown in biofilm and planktonic form, releases free-soluble surface material independent of outer membrane vesicles, which induces proinflammatory responses in human whole blood. Our findings therefore suggest that release of surface components from live bacterial cells could constitute a mechanism for systemic stimulation and be of particular importance in chronic localized infections, such as periodontitis.

Local and systemic responses in matrix metalloproteinase 8-deficient mice during Porphyromonas gingivalis-induced periodontitis

Periodontitis is a bacterium-induced chronic inflammation that destroys tissues that attach teeth to jaw bone. Pathologically excessive matrix metalloproteinase 8 (MMP-8) is among the key players in periodontal destruction by initiating type I collagen degradation. We studied MMP-8 in Porphyromonas gingivalis-induced periodontitis by using MMP-8-deficient (MMP8(-/-)) and wild-type (WT) mice. Alveolar bone loss, inflammatory mediator expression, serum immunoglobulin, and lipoprotein responses were investigated to clarify the role of MMP-8 in periodontitis and systemic inflammatory responses. P. gingivalis infection induced accelerated site-specific alveolar bone loss in both MMP8(-/-) and WT mice relative to uninfected mice. The most extensive bone degradation took place in the P. gingivalis-infected MMP8(-/-) group. Surprisingly, MMP-8 significantly attenuated (P < 0.05) P. gingivalis-induced site-specific alveolar bone loss. Increased alveolar bone loss in P. gingivalis-infected MMP8(-/-) and WT mice was associated with increase in gingival neutrophil elastase production. Serum lipoprotein analysis demonstrated changes in the distribution of high-density lipoprotein (HDL) and very-low-density lipoprotein (VLDL) particles; unlike the WT mice, the MMP8(-/-) mice underwent a shift toward a smaller HDL/VLDL particle sizes. P. gingivalis infection increased the HDL/VLDL particle size in the MMP8(-/-) mice, which is an indicator of lipoprotein responses during systemic inflammation. Serum total lipopolysaccharide activity and the immunoglobulin G-class antibody level in response to P. gingivalis were significantly elevated in both infected mice groups. Thus, MMP-8 appears to act in a protective manner inhibiting the development of bacterium-induced periodontal tissue destruction, possibly through the processing anti-inflammatory cytokines and chemokines. Bacterium-induced periodontitis, especially in MMP8(-/-) mice, is associated with systemic inflammatory and lipoprotein changes that are likely involved in early atherosclerosis.

Cytokine secretion from monocytes persists differentially after activator removal-One mechanism of long-term biological response to implants

Biomedical implants significantly improve the quality of life in an ever-increasing number of patients. However, inflammation of tissues around implants remains a long-term, post-placement sequelae that may contribute to implant failure. Infection-mediated failure is partly a consequence of inappropriate host response and chronic inflammation, and is mediated primarily by the secretory products of monocytes and macrophages. Although the secretion of inflammatory mediators from activated monocytes is well characterized, the resolution of mediator levels post-activation is relatively unstudied. The current study defines the time course of cytokine secretion by activated human monocytes after the activator has been removed. THP1 human monocytes were activated by LPS, and cytokine secretion was monitored over time after LPS removal using enzyme-linked immunosorbent assays (TNFalpha or IL8) or a cytokine array. The release of cytokines was compared with conditions without LPS removal. As expected, secretion of nearly all cytokines was reduced when LPS was removed, but the amount of the reduction was highly cytokine-dependent. Furthermore, levels of cytokines were stable in medium alone but not in cell-culture, suggesting an active process to either degrade or internalize secreted cytokines. Our results are consistent with clinical experience that inflammation resolves rapidly after treatment to remove bacteria or inflamed tissue. However, the differential cytokine regulation indicates a sophisticated coordination of cytokine levels probably associated with management of the wound healing response after removal of the bacterial insult. This wound healing response is one critical component of the long-term success of biomedical implants.

Beneficial Effects of Periodontal Treatment on Metabolic Control of Hypercholesterolemia

BACKGROUND

The authors aimed to evaluate whether local periodontal therapy may influence plasma lipid levels in patients with periodontitis.

METHODS

Fifty patients (31 females and 19 males, age 36-66 yr) were randomly assigned to the treatment and control groups. Lipid profile and dental variables were measured at baseline and at the end of the study in both groups.

RESULTS

In the third month, there was a significant decrease in total and low density lipoprotein (LDL) cholesterol levels of the treatment group compared with baseline values. Also, the reduction in bleeding on probing, pocket depth, attachment loss, plaque index and gingival index were statistically significant in the treatment group.

CONCLUSIONS

The present study indicates that periodontitis causes changes in total and LDL cholesterol levels and local periodontal treatment resulted in a significant decrease in these markers. These results suggest a potential effect of periodontitis-driven systemic inflammation on lipid metabolism.

Endotoxemia, immune response to periodontal pathogens, and systemic inflammation associate with incident cardiovascular disease events

OBJECTIVE

In periodontitis, overgrowth of gram-negative bacteria may cause endotoxemia and systemic inflammation leading to cardiovascular diseases (CVD). We investigated in a prospective study the associations of serum endotoxin, antibodies to periodontal pathogens, and inflammation markers with the risk of incident CVD.

METHODS AND RESULTS

The FINRISK 1992 cohort of 6051 individuals was followed up for 10 years. We examined 185 incident CVD events and a control cohort of 320 individuals using a prospective case-cohort design. High antibody response to periodontal pathogens independently predicted incident CVD events with hazard ratios (HR, quartile 4 versus quartiles 1 to 3, 95% CI) of 1.87 (1.13 to 3.08). The subjects with a high antibody response and high CRP or interleukin (IL)-6 had multivariate-adjusted HRs of 3.01 (1.27 to 7.09) and 3.11 (1.42 to 6.83) compared with low-responders, respectively. The corresponding HRs for high endotoxin concentration were 1.82 (1.22 to 2.73, alone), 3.92 (1.99 to 7.74, with CRP), 3.54 (1.78 to 7.03, with IL-6), and 2.26 (1.13 to 4.52, with tumor necrosis factor (TNF)-alpha) after adjusting for age and gender. These associations were abolished after adjusting for serum lipids. High endotoxin/HDL ratio, however, had a multivariate-adjusted HR of 1.92 (1.19 to 3.08) for CVD events.

CONCLUSIONS

Our results suggest that the exposure to periodontal pathogens or endotoxin induces systemic inflammation leading to increased risk for CVD.

Periodontal disease and systemic conditions: a bidirectional relationship

For decades, physicians and dentists have paid close attention to their own respective fields, specializing in medicine pertaining to the body and the oral cavity, respectively. However, recent findings have strongly suggested that oral health may be indicative of systemic health. Currently, this gap between allopathic medicine and dental medicine is quickly closing, due to significant findings supporting the association between periodontal disease and systemic conditions such as cardiovascular disease, type 2 diabetes mellitus, adverse pregnancy outcomes, and osteoporosis. Significant effort has brought numerous advances in revealing the etiological and pathological links between this chronic inflammatory dental disease and these other conditions. Therefore, there is reason to hope that the strong evidence from these studies may guide researchers towards greatly improved treatment of periodontal infection that would also ameliorate these systemic illnesses. Hence, researchers must continue not only to uncover more information about the correlations between periodontal and systemic diseases but also to focus on positive associations that may result from treating periodontal disease as a means of ameliorating systemic diseases.

Periodontal disease and atherosclerosis from the viewpoint of the relationship between community periodontal index of treatment needs and brachial-ankle pulse wave velocity

BACKGROUND

It has been suggested that periodontal disease may be an independent risk factor for the development of atherosclerosis. However, the relationship between periodontal disease and atherosclerosis has not been fully elucidated. This study aimed to assess the effects of periodontal disease on atherosclerosis.

METHODS

The study design was a cross-sectional study. Subjects were 291 healthy male workers in Japan. We used the Community Periodontal Index of Treatment Needs (CPITN) score, average probing depth and gingival bleeding index (rate of bleeding gums) to assess the severity of periodontal disease. We also used the Brachial-Ankle Pulse Wave Velocity (baPWV) as the index for the development of atherosclerosis.

RESULTS

The unadjusted odds ratio (OR) of atherosclerosis in relation to the CPITN score was 1.41 [95% CI: 1.16-1.73]. However, after adjustment for age, systolic blood pressure and smoking, the CPITN score had no relationship with atherosclerosis (adjusted OR: 0.91 [0.68-1.20]).

CONCLUSION

Our results show no relationship between mild periodontal disease and atherosclerosis after appropriate adjustments.

Dental infections and cardiovascular diseases: a review

Accumulating evidence suggests that chronic infections, such as periodontitis, are associated with increased risk for cardiovascular diseases (CVD). The mechanisms behind the association are not known. Like herpes viruses and Chlamydia pneumoniae, periodontal pathogens cause atherosclerosis in experimental animals and have been found in human atherosclerotic lesions. Higher concentrations of total and low density lipoprotein (LDL) cholesterol and triglycerides and lower concentrations of high density lipoprotein (HDL) cholesterol have been observed in individuals with periodontitis before periodontal treatment. Periodontitis also induces a peripheral inflammatory and immune response, reflected in elevated concentrations of C-reactive protein (CRP) and IgA-class antibodies to periodontal pathogens. The prevalence of CVD seems to be highest in those individuals in whom periodontitis coexists with elevated CRP levels. This may indicate that periodontitis is a CVD risk factor in individuals who react to the infection with a systemic inflammatory and immune response. This may be due to genetic reasons and may also apply to other chronic low-grade infections.