Porphyromonas gingivalis promotes murine abdominal aortic aneurysms via matrix metalloproteinase-2 induction

Cardiovascular Diseases and Periodontitis

Periodontitis is a chronic inflammatory disease of the tooth-supporting connective tissue and alveolar bone that is initiated by a bacterial biofilm in periodontal pockets. It affects about half of adults in the Western world, and is associated with a range of systemic comorbidities, e.g., cardiovascular disease (CVD), diabetes and rheumatoid arthritis, and these diseases share overlapping systemic and target tissue inflammatory mechanisms. Indeed, mounting evidence has indicated that their association is causal and built on the presence of systemic low-grade inflammation (LGI). Prior research linking periodontitis to CVD has mainly been derived from experimental studies, observational data, and small interventional trials with surrogate markers of CVD, e.g., endothelial dysfunction. However, recent data from randomised studies have demonstrated that intensive treatment of periodontitis can reduce blood pressure in patients with hypertension in conjunction with reduction of systemic inflammatory markers. Furthermore, targeted anti-inflammatory therapy has been shown to reduce recurrent events in patients with established CVD and LGI. Along this line, the concept of residual inflammatory risk has emerged as an independent new risk factor for atherothrombotic CVD. The present review summarizes translational evidence indicating that periodontitis is a risk factor for CVD dependent on LGI, and we conclude that treatment of periodontitis is likely to contribute importantly to reduction of residual inflammatory risk.

Pathological and immunological differences of arterial thrombi and wall caused by three different periodontal bacterial injections in rat models and proposals on the pathogeneses of vascular diseases

OBJECTIVES

Periodontal bacteria that have been studied show a strong connection to various vascular diseases. Among the many kinds of periodontal bacteria, Porphyromonas gingivalis (Pg) is well examined in the general aspects and in a rat model. However, whether other periodontal bacteria work or react differently is not studied well.

MATERIAL AND METHODS

We chose Aggregatibacter actinomycetemcomitans (Aa) and Prevotella intermedia (Pi) as different types of periodontal bacteria. Low-density and high-density bacterial solutions were injected in the small artery of rats' groins using our rat model. Eighteen limbs of 9 SD male rats (500-650 g) were used. After 7 days, 14-18 days, and 28 days, the rats were sacrificed. A pathological and an immuno-histochemical study was conducted and reported on the low-density group with 12 limbs because the Pi group lacked a high-density study. Immuno-histochemical staining of live Pg was performed on three limbs of three rats at 1 h, 3 h, and 1 week after injection.

RESULTS

The appearances from the acute, at 7 days, to chronic phases, at 28 days, were observed. The differences of the species were certainly observed in the internal elastic lamina (IEL), and immuno-histochemical reactions. The inflammatory reactions, such as cellular distribution or intra-thrombus materials, were similar in all. One week later, we could not see any living bacteria in the specimen or immunological observation.

CONCLUSIONS

The three species were essentially the same, except for Aa's stronger disruption of IEL, and more CD3 (Pan T cell) in Pi and more CD79a (Pan B cell) in Pg. We propose a new concept of a possible mechanism of vascular diseases, in which the work of LPS (lipopolysaccharides) and a toll-like receptor (TLR) is emphasized.

Systemic immune response against the oral pathogens Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans is associated with the formation and rupture of intracranial aneurysms

BACKGROUND AND PURPOSE

Periodontal infections are associated with the formation and rupture of intracranial aneurysms (IAs). This study investigated the role of two key periodontal pathogens, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans.

METHODS

Immunoglobulin A (IgA) and IgG antibodies against P. gingivalis and A. actinomycetemcomitans were measured with enzyme immune assay from the serum of 227 IA patients, of whom 64 also underwent clinical oral examination. As a control group, 1096 participants in a cross-sectional health survey, Health 2000, underwent serological studies and oral examination. Logistic regression was used for multivariate analysis. Immunohistochemistry was performed to demonstrate bacteria-derived epitopes in the IA wall.

RESULTS

Widespread gingivitis and severe periodontitis were more common in IA patients than in controls (2× and 1.5×, respectively). IgA antibodies against P. gingivalis and A. actinomycetemcomitans were 1.5× and 3-3.4× higher, respectively, in both unruptured and ruptured IA patients compared to controls (p ≤ 0.003). IgG antibodies against P. gingivalis were 1.8× lower in unruptured IA patients (p < 0.001). In multivariate analysis, high IgA, but low IgG, antibody levels against P. gingivalis (odds ratio [OR] = 1.4, 95% confidence interval [Cl] = 1.1-1.8 and OR = 1.5, 95% Cl = 1.1-1.9; OR = 0.6, 95% Cl = 0.4-0.7 and OR = 0.5, 95% Cl = 0.4-0.7) and against A. actinomycetemcomitans (OR = 2.3, 95% Cl = 1.7-3.1 and OR = 2.1, 95% Cl = 1.5-2.9; OR = 0.6, 95% Cl = 0.4-0.8 and OR = 0.6, 95% Cl = 0.5-0.9) were associated with the risk of IA formation and rupture. Immunohistochemistry showed P. gingivalis epitopes in the IA wall.

CONCLUSIONS

Exposure to the periodontal pathogens P. gingivalis and A. actinomycetemcomitans and dysfunctional acquired immune response against them may increase the risk of IA formation and IA rupture.

Porphyromonas gingivalis and Its Systemic Impact: Current Status

The relationship between periodontitis and systemic diseases, notably including atherosclerosis and diabetes, has been studied for several years. Porphyromonas gingivalis, a prominent component of oral microorganism communities, is the main pathogen that causes periodontitis. As a result of the extensive analysis of this organism, the evidence of its connection to systemic diseases has become more apparent over the last decade. A significant amount of research has explored the role of Porphyromonas gingivalis in atherosclerosis, Alzheimer's disease, rheumatoid arthritis, diabetes, and adverse pregnancy outcomes, while relatively few studies have examined its contribution to respiratory diseases, nonalcoholic fatty liver disease, and depression. Here, we provide an overview of the current state of knowledge about Porphyromonas gingivalis and its systemic impact in an aim to inform readers of the existing epidemiological evidence and the most recent preclinical studies. Additionally, the possible mechanisms by which Porphyromonas gingivalis is involved in the onset or exacerbation of diseases, together with its effects on systemic health, are covered. Although a few results remain controversial, it is now evident that Porphyromonas gingivalis should be regarded as a modifiable factor for several diseases.

Further evidence on the relationship between abdominal aortic aneurysm and periodontitis: A cross-sectional study

BACKGROUND

Periodontitis is a chronic inflammatory disease characterized by Gram-negative bacteria responsible for the degradation of tissues surrounding tooth. Moreover, periopathogens can invade the bloodstream, disseminate and promote cardiovascular disease, such as the link between Porphyromonas gingivalis and atherosclerosis. The aim of this study was to explore the relationship between the severity of periodontitis and of abdominal aortic aneurysm (AAA).

METHODS

This cross-sectional study compared patients with stable AAA (n = 30) and patients with unstable AAA (n = 31) based on aortic diameter, growth rate, and eligibility for surgical intervention. Periodontal clinical parameters were recorded as well as the Periodontal Inflamed Surface Area and the Periodontal Index for Risk of Infectiousness (PIRI). Microbiological analyses were performed on saliva and supragingival and subgingival plaque. Quantification of Tannerella forsythia (Tf), Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), Fusobacterium nucleatum (Fn), and Prevotella intermedia (Pi) was done by quantitative polymerase chain reaction.

RESULTS

The two AAA groups were homogeneous for age, sex, and most risk factors except hypertension and chronic obstructive pulmonary disease. Periodontal parameters were comparable but the proportion of patients with high PIRI scores was greater in those with unstable AAA (51.6% versus 23.3%). The probing depth (PD) and the proportion of PD >6 mm were positively correlated with AAA size and thrombus volume. Several associations were found between periopathogens such as Pg and AAA diameters and volumes, but no difference could be evidenced between stable and unstable AAA groups.

CONCLUSIONS

Periodontitis was highly prevalent in both stable and unstable AAA patients. Severe and progressive periodontitis (stage IV and grade C) tended to be more frequent in the group of patients with unstable AAA. Moreover, Pg was observed in all the samples (saliva, supragingival, and subgingival plaque) and was correlated with AAA diameters and volumes. The study evidenced potential relationships between periodontitis severity and size of AAA.

Role of oral pathogens in the pathogenesis of intracranial aneurysm: review of existing evidence and potential mechanisms

Degeneration of intracranial aneurysm wall is under active research and recent studies indicate an increased risk of rupture of intracranial aneurysm among patients with periodontal diseases. In addition, oral bacterial DNA has been identified from wall samples of ruptured and unruptured aneurysms. These novel findings led us to evaluate if oral diseases could predispose to pathological changes seen on intracranial aneurysm walls eventually leading to subarachnoid hemorrhage. The aim of this review is to consider mechanisms on the relationship between periodontitis and aneurysm rupture, focusing on recent evidence.

Increased Heart Failure Prevalence in Patients with a High Antibody Level Against Periodontal Pathogen

The aim of this study was to assess whether a specific cardiovascular disease was related to an increased antibody level against a periodontal pathogen.A strong association between cardiovascular disease and periodontitis was shown, however, the causal relationship was not proven. Increased inflammatory reaction of patients with periodontitis was a possible factor, which connected periodontal infection and vascular diseases.We assessed medical history, blood data, and periodontal conditions in patients with cardiovascular diseases. Serum IgG antibody titers against major periodontal pathogens and existence of salivary periodontal bacteria were analyzed.In total, 348 subjects were enrolled in this study. The patients who exhibited 10,000 counts/mL or more of salivary Porphyromonas gingivalis were divided into two groups according to the antibody level of the pathogen. Patients with a high antibody level against Porphyromonas gingivalis exhibited a high rate of heart failure compared to the low antibody group. Mean probing pocket depth and clinical attachment level significantly increased in the high antibody group. We found that the high anti-Porphyromonas gingivalis antibody group also experienced enhanced antibody levels against other periodontal bacteria.An increased heart failure prevalence was found in patients with a high antibody level against a major periodontal pathogen, Porphyromonas gingivalis.

Periodontitis May Deteriorate Sinus of Valsalva Dilatation in Marfan Syndrome Patients

Marfan syndrome (MFS) is a systemic connective tissue disorder that is caused by mutations of fibrillin-1. While MFS patients are at a high risk of periodontitis and aortic diseases, little causal information has been provided to date. To clarify the relationship, their oral condition and sinus of Valsalva (SoV) were evaluated.The subjects were patients with MFS (n = 33) who attended the University of Tokyo Hospital. We divided them into two groups; MFS patients with highly dilated (the diameters were equal to or more than 39 mm) SoV (high group, n = 18) and MFS patients with mildly dilated (less than 39 mm) SoV (mild group, n = 15). Blood examinations, echocardiograms, and full-mouth clinical measurements, including number of teeth, probing pocket depth (PPD), bleeding on probing (BOP), and community periodontal index (CPI) were performed.We found that the high group patients had greater rates of BOP compared to that of the mild group. Furthermore, the high group tended to have higher serum levels of C-reactive protein, matrix metalloproteinase-9, and transforming growth factor-β compared to the mild group.Periodontitis may deteriorate SoV dilatation in MFS patients.

Ethical guidelines, animal profile, various animal models used in periodontal research with alternatives and future perspectives

Laboratory animal models serve as a facilitator to investigate the etiopathogenesis of periodontal disease, are used to know the efficacy of reconstructive and regenerative procedures, and are also helpful in evaluation of newer therapeutic techniques including laser and implant therapies prior to application in the human beings. The aim of this review is to know the different animal models used in various specialties of dental research and to know the ethical guidelines prior to the usage of experimental models with main emphasis on how to refine, replace, and reduce the number of animal models usage in the laboratory. An online search for experimental animal models used in dental research was performed using MEDLINE/PubMed database. Publications from 2009 to May 2013 in the specialty of periodontics were included in writing this review. A total of 652 references were published in PubMed/MEDLINE databases based on the search terms used. Out of 245 studies, 241 were related to the periodontal research published in English from 2009 to 2013. Relevant papers were chosen according to the inclusion and exclusion criteria. After extensive electronic and hand search on animal models, it has been observed that various animal models were used in dental research. Search on animal models used for dental research purpose revealed that various animals such as rats, mice, guinea pigs, rabbit, beagle dogs, goats, and nonhuman primates were extensively used. However, with the new advancement of ex vivo animal models, it has become easy to investigate disease pathogenesis and to test the efficacy of newer therapeutic modalities with the reduced usage of animal models. This review summarized the large amount of literature on animal models used in periodontal research with main emphasis on ethical guidelines and on reducing the animal model usage in future perspective.

The implication of periodontitis in vascular endothelial dysfunction

BACKGROUND

Periodontitis is the most common oral infection seen in humans worldwide. It is characterized by gradual destruction of tooth supporting tissues, eventually leading to loss of tooth. The periodontal biofilm associated with periodontitis comprises of gram-positive and gram-negative bacteria, instrumental for the initiation and progression of periodontitis. Evidence-based literature has identified the nature of periodontal infection as a possible causative condition in the inducement of 'low-grade systemic inflammation and infection'. The periodontal pathogens exert systemic effects via the haematogenous route.

AIM

The present review provides an insight into the pathophysiology of the endothelial dysfunction with reference to periodontal infection and highlights the association between periodontitis and endothelial dysfunction. Various studies addressing the implication of periodontitis on endothelial dysfunction will be described, with a focus of periodontal treatment on improvement of endothelial function.

MATERIALS AND METHODS

Studies examining the effects of periodontitis on vascular endothelial function were segregated. Studies conducted on both animal and human models were identified using MEDLINE database search with key search terms such as 'Periodontitis', 'vascular endothelium', 'endothelial dysfunction', 'periodontal bacteria' and 'periodontal therapy'. Systematic reviews and meta-analysis were also screened. Only studies published in English language were considered. The review has been prepared by screening MEDLINE database from 1989 to 2012.

RESULTS AND CONCLUSIONS

Chronic periodontitis results in altered vascular response, increased expression of pro-inflammatory cytokines and adhesion molecules inducing vascular endothelial dysfunction. Periodontal therapy may ameliorate the perturbed vascular endothelial function.

Influence of periodontitis on abdominal aortic aneurysms

Periodontitis is known to be a risk factor for abdominal aortic aneurysm (AAA). However, the influence of periodontitis on AAA development is to be elucidated. This article is to review the relationship between periodontitis and AAA. We focused on the roles of specific periodontopathic bacteria in AAA, matrix metalloproteinases and toll-like receptors in the pathophysiology in the section of experimental analysis. Furthermore, we showed clinical data of periodontitis in patients with AAA. We concluded that periodontal pathogens play a critical role in the AAA development.

High incidence of periodontitis in Japanese patients with abdominal aortic aneurysm

Periodontitis is known to be a risk factor for abdominal aortic aneurysm (AAA). However, the influence of periodontitis on AAA in Japanese patients has not yet been elucidated. The aim of this clinical investigation was to assess the relationship between periodontal bacterial burden in AAA patients.We studied 12 AAA patients and 24 age- and sex-matched non-AAA cardiovascular patients. We examined periodontitis and the presence of the periodontal pathogens Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Prevotella intermedia in oral samples using polymerase chain reaction assays.We found that the AAA patients had deeper pocket depth compared to the non-AAA patients (3.53 ± 0.38 mm versus 2.67 ± 0.17 mm, P < 0.05). However, the populations of periodontal bacteria were comparable between the two groups. Periodontitis may have a greater effect on aneurysm progression compared to other cardiovascular diseases.

Incidence of periodontitis in Japanese patients with cardiovascular diseases: a comparison between abdominal aortic aneurysm and arrhythmia

Although there is a link between periodontitis and cardiovascular disease (CVD), the influence of periodontitis on CVD is unclear. The aim of this study was to assess the relationship between periodontal bacterial burden and CVD. We studied 142 patients with tachyarrhythmia (TA) and 25 patients with abdominal aortic aneurysm (AAA). We examined periodontitis and the presence of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans and Prevotella intermedia in the patients' saliva and subgingival plaque using PCR. We also measured serum antibody titers against the pathogens using ELISA. We found that the patients with AAA had fewer remaining teeth (14.6 ± 2.0 vs. 20.9 ± 0.7, P < 0.05) and deeper pocket depth (3.01 ± 0.26 vs. 2.52 ± 0.05 mm, P < 0.05) compared to the TA patients. The existence of each periodontal bacterium in their saliva or subgingival plaque and serum antibody titers was comparable between the two groups. Periodontitis may have a larger affect on aneurysm progression compared to arrhythmia.

High incidence and severity of periodontitis in patients with Marfan syndrome in Japan

Marfan syndrome (MFS) is a systemic connective tissue disorder caused by mutations in the extracellular matrix protein fibrillin-1. While it is known that patients with MFS are at high risk of dental disorders and cardiovascular diseases, little information has been provided to date. To clarify the prevalence of periodontitis in patients with MFS, their oral condition and cardiovascular complications were evaluated. The subjects were patients with MFS (n = 40) who attended the University of Tokyo hospital; age- and gender-matched healthy individuals (n = 14) constituted a control group. Cardiovascular complications and full-mouth clinical measurements, including number of teeth, probing of pocket depth (PD), bleeding on probing (BOP), and community periodontal index (CPI) were recorded. MFS patients had more frequent cardiovascular complications (95 %) compared with the controls (0 %). MFS patients had periodontitis (CPI 3 and 4) more frequently (87.5 %) than the age- and gender-matched control subjects (35.7 %). Furthermore, MFS patients had significantly more severe periodontitis (CPI 2.90 ± 0.12 vs 1.64 ± 0.32) and fewer remaining teeth (26.7 ± 0.4 vs 28.4 ± 0.4) compared with the controls. However, PD and BOP were comparable between MFS patients and the control group. A high incidence of periodontitis and cardiovascular complications was observed in Japanese MFS patients.

Porphyromonas gingivalis promotes neointimal formation after arterial injury through toll-like receptor 2 signaling

We previously demonstrated that Porphyromonas gingivalis infection induces neointimal hyperplasia with an increase in monocyte chemoattractant protein (MCP)-1 after arterial injury in wild-type mice. Toll-like receptor (TLR) 2 is a key receptor for the virulence factors of P. gingivalis. The aim of this study was to assess whether TLR2 plays a role in periodontopathic bacteria-induced neointimal formation after an arterial injury. Wild-type and TLR2-deficient mice were used in this study. The femoral arteries were injured, and P. gingivalis or vehicle was injected subcutaneously once per week. Fourteen days after arterial injury, the murine femoral arteries were obtained for histopathologic and immunohistochemical analyses. The immunoglobulin-G levels of the P. gingivalis-infected groups were significantly increased in comparison with the level in the corresponding noninfected groups in both wild-type and TLR2-deficient mice. TLR2 deficiency negated the P. gingivalis-induced neointimal formation in comparison with the wild-type mice, and reduced the number of positive monocyte chemoattractant protein-1 cells in the neointimal area. These findings demonstrate that P. gingivalis infection can promote neointimal formation after an arterial injury through TLR2 signaling.

CD14 directs adventitial macrophage precursor recruitment: role in early abdominal aortic aneurysm formation

Background

Recruitment of macrophage precursors to the adventitia plays a key role in the pathogenesis of abdominal aortic aneurysms (AAAs), but molecular mechanisms remain undefined. The innate immune signaling molecule CD14 was reported to be upregulated in adventitial macrophages in a murine model of AAA and in monocytes cocultured with aortic adventitial fibroblasts (AoAf) in vitro, concurrent with increased interleukin‐6 (IL‐6) expression. We hypothesized that CD14 plays a crucial role in adventitial macrophage precursor recruitment early during AAA formation.

Methods and Results

CD14^−/− mice were resistant to AAA formation induced by 2 different AAA induction models: aortic elastase infusion and systemic angiotensin II (AngII) infusion. CD14 gene deletion led to reduced aortic macrophage infiltration and diminished elastin degradation. Adventitial monocyte binding to AngII‐infused aorta in vitro was dependent on CD14, and incubation of human acute monocytic leukemia cell line‐1 (THP‐1) monocytes with IL‐6 or conditioned medium from perivascular adipose tissue (PVAT) upregulated CD14 expression. Conditioned medium from AoAf and PVAT induced CD14‐dependent monocyte chemotaxis, which was potentiated by IL‐6. CD14 expression in aorta and plasma CD14 levels were increased in AAA patients compared with controls.

Conclusions

These findings link CD14 innate immune signaling via a novel IL‐6 amplification loop to adventitial macrophage precursor recruitment in the pathogenesis of AAA.

Porphyromonas gingivalis strain specific interactions with human coronary artery endothelial cells: a comparative study

Both epidemiologic and experimental findings suggest that infection with Porphyromonas gingivalis exacerbates progression of atherosclerosis. As P. gingivalis exhibits significant strain variation, it is reasonable that different strains possess different capabilities and/or mechanisms by which they promote atherosclerosis. Using P. gingivalis strains that have been previously evaluated in the ApoE null atherosclerosis model, we assessed the ability of W83, A7436, 381, and 33277 to adhere, invade, and persist in human coronary artery endothelial (HCAE) cells. W83 and 381 displayed an equivalent ability to adhere to HCAE cells, which was significantly greater than both A7436 and 33277 (P<0.01). W83, 381, and 33277 were more invasive than A7436 (P<0.0001). However, only W83 and A7436 were able to remain viable up to 48 hours in HCAE cell cultures, whereas 381 was cleared by 48 hours and 33277 was cleared by 24 hours. These differences in persistence were in part due to strain specific differences in intracellular trafficking. Both W83 and 381 trafficked through the autophagic pathway, but not A7436 or 33277. Internalized 381 was the only strain that was dependent upon the autophagic pathway for its survival. Finally, we assessed the efficacy of these strains to activate HCAE cells as defined by production of IL-6, IL-8, IL-12p40, MCP-1, RANTES, TNF-α, and soluble adhesion molecules (sICAM-1, sVCAM-1, and sE-selectin). Only moderate inflammation was observed in cells infected with either W83 or A7436, whereas cells infected with 381 exhibited the most profound inflammation, followed by cells infected with 33277. These results demonstrate that virulence mechanisms among different P. gingivalis strains are varied and that pathogenic mechanisms identified for one strain are not necessarily applicable to other strains.

Periodontal pathogen Aggregatibacter actinomycetemcomitans deteriorates pressure overload-induced myocardial hypertrophy in mice

Although a relationship between periodontitis and myocardial hypertrophy has been reported, the precise mechanism has not been clarified. The purpose of this study was to investigate the association between periodontal infection and myocardial hypertrophy. Transverse aortic constriction (TAC) was performed. Mice were injected with Aggregatibacter actinomycetemcomitans (A.a.) (0.1 mL of 10(8) CFU/mL) in the infected group and PBS in the control group. Echocardiography, histopathology, and immunohistochemistry were performed. Echocardiography indicated that left ventricular fractional shortening had decreased in the infected group compared to the control group on day 28. Heart to body weight ratio increased in the infected group compared to the control group. Histopathologically, A.a.-infected mice showed markedly enhanced cardiac hypertrophy, fibrosis and arteriosclerosis 4 weeks after TAC operation. Immunohistochemistry revealed that expression of MMP-2 in the interstitial tissue was enhanced in the infected group. These results suggested that the periodontal pathogen caused a deterioration of pressure overload-induced myocardial hypertrophy through MMP activation.

The calcium chloride-induced rodent model of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) affects ∼5% men aged over 65 years and is an important cause of death in this population. Research into AAA pathogenesis has been fuelled by the need to identify new diagnostic biomarkers and therapeutic targets for this disease. One animal model of AAA involves peri-vascular application of calcium chloride (CaCl(2)) onto the infra-renal aorta of mice and rats to induce extracellular matrix remodelling. Twenty-three studies assessing CaCl(2)-induced AAA and six studies assessing AAA induced by a modified CaCl(2) method were identified. In the current report the preparation and pathological features of this AAA model are discussed. We also compared this animal model to human AAA. CaCl(2)-induced AAA shows the following pathological characteristics typically found in human AAA: calcification, inflammatory cell infiltration, oxidative stress, neovascularisation, elastin degradation and vascular smooth muscle cell apoptosis. A number of mechanisms involved in CaCl(2)-induced AAA have been identified which may be relevant to the pathogenesis of human AAA. Key molecules include c-Jun N-terminal kinase, peroxisome proliferator-activated receptor-γ, chemokine (C-C motif) receptor 2, group x secretory phospholipase A2 and plasminogen. CaCl(2)-induced AAA does not display aortic thrombus, atherosclerosis and rupture which are classical features of human AAA. Advantages of the CaCl(2)-induced AAA technique include (1) it can be applied to wild type mice making assessment of transgenic rodent models more straight forward and rapid; and (2) CaCl(2)-induced AAAs are usually developed in the infra-renal abdominal aorta, which is the most common location of human AAA. Currently findings obtained from the CaCl(2)-induced AAA model or other animal models of AAA have not been translated into the human situation. It is hoped that this deficiency will be corrected over the next decade with a number of clinical trials currently examining novel treatment options for AAA patients.

Porphyromonas gingivalis accelerates neointimal formation after arterial injury

BACKGROUND

Inflammation plays a key role in neointimal hyperplasia after an arterial injury. Chronic infectious disorders, such as periodontitis, are associated with an increased risk of cardiovascular diseases. However, the effects of a periodontal infection on vascular remodeling have not been examined. We assess the hypothesis that periodontal infection could promote neointimal formation after an arterial injury.

METHODS

Mice were implanted with subcutaneous chambers (n = 41). Two weeks after implantation, the femoral arteries were injured, and Porphyromonas gingivalis (n = 21) or phosphate-buffered saline (n = 20) was injected into the chamber. The murine femoral arteries were obtained for the histopathological analysis. The expression level of mRNA in the femoral arteries was analyzed using quantitative reverse transcriptase polymerase chain reaction (n = 19-20).

RESULTS

The intima/media thickness ratio in the P. gingivalis infected group was found to be significantly increased in comparison to the non-infected group. The expression of matrix metalloproteinase-2 mRNA was significantly increased in the P. gingivalis infected group compared to the non-infected group.

CONCLUSION

These findings demonstrate that P. gingivalis injection can promote neointimal formation after an arterial injury. Periodontitis may be a critical factor in the development of restenosis after arterial intervention.

Clarithromycin suppresses the periodontal bacteria-accelerated abdominal aortic aneurysms in mice

BACKGROUND AND OBJECTIVE

Although clarithromycin (CAM) has many biological functions, including regulation of MMPs, little is known about its effect on abdominal aortic aneurysms. Periodontopathic bacteria have been reported to be associated with several kinds of circulatory diseases. The purpose of this study was therefore to clarify the effect of CAM on periodontopathic bacteria-accelerated abdominal aortic aneurysms.

MATERIAL AND METHODS

Abdominal aortic aneurysm was produced in mice by the peri-aortic application of 0.25 m CaCl(2). The mice were inoculated once per week with live Porphyromonas gingivalis, which is one of the major periodontopathic bacteria. Test mice (n=8) were given a daily oral dose of CAM, while control mice (n=13) were not.

RESULTS

Four weeks after the operation, the P. gingivalis-injected and CAM-treated mice showed a significant decrease in the aortic diameter in comparison with the mice only injected with P. gingivalis. Histopathologically, the samples obtained from the P. gingivalis-injected and CAM-treated mice showed less elastic degradation. Moreover, the plasma MMP-2 concentration of the CAM-treated mice decreased significantly.

CONCLUSION

These findings suggest that CAM administration is useful to suppress periodontal bacteria-accelerated abdominal aortic aneurysms via MMP regulation.

Porphyromonas gingivalis participates in pathogenesis of human abdominal aortic aneurysm by neutrophil activation. Proof of concept in rats

Background

Abdominal Aortic Aneurysms (AAAs) represent a particular form of atherothrombosis where neutrophil proteolytic activity plays a major role. We postulated that neutrophil recruitment and activation participating in AAA growth may originate in part from repeated episodes of periodontal bacteremia.

Methods and Findings

Our results show that neutrophil activation in human AAA was associated with Neutrophil Extracellular Trap (NET) formation in the IntraLuminal Thrombus, leading to the release of cell-free DNA. Human AAA samples were shown to contain bacterial DNA with high frequency (11/16), and in particular that of Porphyromonas gingivalis (Pg), the most prevalent pathogen involved in chronic periodontitis, a common form of periodontal disease. Both DNA reflecting the presence of NETs and antibodies to Pg were found to be increased in plasma of patients with AAA. Using a rat model of AAA, we demonstrated that repeated injection of Pg fostered aneurysm development, associated with pathological characteristics similar to those observed in humans, such as the persistence of a neutrophil-rich luminal thrombus, not observed in saline-injected rats in which a healing process was observed.

Conclusions

Thus, the control of periodontal disease may represent a therapeutic target to limit human AAA progression.