Background— Current epidemiological data suggest that dental infections affecting tooth-supporting tissues (periodontitis) can disseminate into the systemic circulation and thereby contribute to atherosclerosis progression. To test this hypothesis, we investigated the effect of repeated systemic inoculations with Porphyromonas gingivalis (Pg), a putative periodontal pathogen, on the progression of atherosclerosis in heterozygous apolipoprotein E–deficient (ApoE+/-) mice. Methods and Results— Ten-week-old, male ApoE+/- mice fed either a high-fat diet or regular chow were inoculated intravenously with live Pg (107 CFU) or vehicle once per week for 10, 14, or 24 consecutive weeks. Histomorphometry of plaque cross-sectional area in the proximal aortas, en face measurement of plaque area over the aortic trees, Pg 16S ribosomal DNA amplification with polymerase chain reaction, ELISA for systemic proinflammatory mediators, and immunolocalization of macrophages in the proximal aorta were performed. Atherosclerotic lesions of the proximal aortas and aortic trees were more advanced in Pg-challenged animals than in vehicle control animals and occurred earlier (at 10 weeks) when no lesions were apparent in control animals. At 24 weeks after inoculation, proximal aortic lesion size quantified by histomorphometry was 9-fold greater in chow-fed mice inoculated with Pg than in noninoculated mice (P<0.001) and was 2-fold greater in Pg-inoculated versus noninoculated high-fat diet–fed mice (P<0.001); all atherosclerotic lesions were macrophage-rich. Pg ribosomal DNA was found in the aortas, livers, and hearts 24 weeks after inoculation. Conclusions— These results provide evidence that long-term systemic challenge with Porphyromonas gingivalis, an oral pathogen, can accelerate atherogenic plaque progression

Acute coronary syndromes—unstable angina, myocardial infarction, and sudden cardiac death—are caused by acute disruption of an unstable coronary atheroma. Unstable plaques have three histologic characteristics: a large lipid core, many inflammatory cells, and a thin fibrous cap. Because the unstable plaque is not necessarily obstructive, it may cause no symptoms before rupture. The cellular processes that lead to the characteristic histologic features of unstable plaque have recently been identified. This new understanding of the cell biology of plaque instability suggests new therapeutic strategies: passivation of the endothelium, reduction of low-density lipoprotein (LDL) in the vessel wall by decreasing serum LDL levels or accelerating reverse cholesterol transport, inhibition of LDL oxidation, inhibition of inflammatory cytokine expression, and inhibition of thrombus formation. Although the morbidity and mortality resulting from acute coronary disease have been reduced by more than 50% over the past 30 years, it is reasonable to anticipate further reductions of similar magnitude in the decade ahead.

Context Although Chlamydia pneumoniae infection has been associated with the initiation and progression of atherosclerosis, results of clinical trials investigating antichlamydial antibiotics as adjuncts to standard therapy in patients with coronary artery disease (CAD) have been inconsistent. Objective To conduct a meta-analysis of clinical trials of antichlamydial antibiotic therapy in patients with CAD. Data Sources The MEDLINE and Cochrane Central Register of Controlled Trials databases were searched from 1966 to April 2005 for English-language trials of antibiotic therapy in patients with CAD. Bibliographies of retrieved articles were searched for further studies. Presentations at major scientific meetings (2003-2004) were also reviewed. Search terms included antibacterial agents, myocardial infarction, unstable angina, and coronary arteriosclerosis. Study Selection Eligible studies were prospective, randomized, placebo-controlled trials of antichlamydial antibiotic therapy in patients with CAD that reported all-cause mortality, myocardial infarction, or unstable angina. Of the 110 potentially relevant articles identified, 11 reports enrolling 19 217 patients were included. Data Extraction Included studies were reviewed to determine the number of patients randomized, mean duration of follow-up, and end points. End points of interest included all-cause mortality, myocardial infarction (MI), and a combined end point of MI and unstable angina. Data Synthesis Event rates were combined using a random-effects model. Antibiotic therapy had no impact on all-cause mortality among treated vs untreated patients (4.7% vs 4.6%; odds ratio [OR], 1.02; 95% confidence interval [CI], 0.89-1.16; P = .83), on the rates of MI (5.0% vs 5.4%; OR, 0.92; 95% CI, 0.81-1.04; P = .19), or on the combined end point of MI and unstable angina (9.2% vs 9.6%; OR, 0.91; 95% CI, 0.76-1.07; P = .25). Conclusion Evidence available to date does not demonstrate an overall benefit of antibiotic therapy in reducing mortality or cardiovascular events in patients with CAD.

Increased baseline values of the acute-phase reactant C-reactive protein (CRP) are significantly associated with future cardiovascular disease, and some in vitro studies have claimed that human CRP (hCRP) has proatherogenic effects. in vivo studies in apolipoprotein E-deficient mouse models, however, have given conflicting results. We bred atherosclerosis-prone mice (Apob100/100Ldlr–/–), which have human-like hypercholesterolemia, with hCRP transgenic mice (hCRP+/0) and studied lesion development at 15, 30, 40, and 50 weeks of age. Atherosclerotic lesions were smaller in hCRP+/0Apob100/100Ldlr–/– mice than in hCRP0/0Apob100/100Ldlr–/– controls, as judged from the lesion surface areas of pinned-out aortas from mice at 40 and 50 weeks of age. In lesions from 40-week-old mice, mRNA expression levels of several genes in the proteasome degradation pathway were higher in hCRP+/0Apob100/100Ldlr–/– mice than in littermate controls, as shown by global gene expression profiles. These results were confirmed by real-time PCR, which also indicated that the activities of those genes were the same at 30 and 40 weeks in hCRP+/0Apob100/100Ldlr–/– mice but were significantly lower at 40 weeks than at 30 weeks in controls. Our results show that hCRP is not proatherogenic but instead slows atherogenesis, possibly through proteasome-mediated protein degradation.

Since its discovery, Helicobacter pylori has been implicated in the pathogenesis of several diseases, both digestive and extradigestive. Interestingly, the majority of the extradigestive-related literature is focused on two vascular manifestations: stroke and ischemic heart disease. Potential mechanisms for the establishment of a H. pylori-induced ischemic heart disease have been proposed with regard to chronic inflammation, molecular mimicry, oxidative modifications, endothelial dysfunction, direct effect of the microorganism on atherosclerotic plaques as well as changes regarding traditional or novel risk factors for ischemic heart disease or even platelet-H. pylori interactions. A positive link between H. pylori infection and ischemic heart disease has been suggested by a series of studies focusing on epidemiologic evidence, dyslipidemic alterations, upregulation of inflammatory markers or homocysteine levels, induction of hypercoagulability, oxidation of low-density lipoprotein, causation of impaired endothelial function, detection of H. pylori DNA in atherosclerotic plaques, and participation of certain antigens and antibodies in a cross-reactivity model. There are studies, however, which investigated the relationship between H. pylori and ischemic heart disease with regard to the same parameters and failed to confirm the suggested positive association. Further studies in the direction of interaction between H. pylori and the host's genotype as well as a quest for evidence towards novel risk factors for ischemic heart disease such as oxidative stress, vascular remodeling, vascular calcification, or vasomotor activity, may reveal a field of great interest, thus contributing to the determination of new potential mechanisms.

Background— Innate immune reactions against bacteria and viruses have been implicated in the pathogenesis of atherosclerosis. To explore the molecular mechanism by which microbe recognition occurs in the artery wall, we characterized the expression of toll-like receptors (TLRs), a family of pathogen pattern recognition receptors, in atherosclerotic lesions. Methods and Results— Semiquantitative polymerase chain reaction and immunohistochemical analysis demonstrated that of 9 TLRs, the expression of TLR1, TLR2, and TLR4 was markedly enhanced in human atherosclerotic plaques. A considerable proportion of TLR-expressing cells were also activated, as shown by the nuclear translocation of nuclear factor-{kappa}B. Conclusion— Our findings illustrate a repertoire of TLRs associated with inflammatory activation in human atherosclerotic lesions, and they encourage further exploration of innate immunity in the pathogenesis of atherosclerosis.

Heparan sulfate in the extracellular matrix of the artery wall has been proposed to possess anti-atherogenic properties by interfering with lipoprotein retention, suppression of inflammation, and inhibition of smooth muscle cell growth. Previously, the amount of heparan sulfate in atherosclerotic lesions from humans and animals has been shown to be reduced but the identity or identities of the heparan sulfate molecules being down regulated in this disease are not known. In this study, atherosclerotic lesions were retrieved from 44 patients undergoing surgery for symptomatic carotid stenosis. Normal iliac arteries from organ donors were used as controls. Analysis of the specimens by gene microarray showed a selective reduction in perlecan gene expression, whereas, expression of the other heparan sulfate proteoglycans in the artery wall, agrin and collagen XVIII, remained unchanged. Expression of the large chondroitin sulfate proteoglycan, versican, also remained unchanged. Real-time PCR confirmed the decrease in perlecan gene expression and the unchanged expression of versican. The findings were supported by immunohistochemical analysis demonstrating a reduced accumulation of both perlecan core protein and heparan sulfate in carotid lesions. The study demonstrates a reduction of perlecan mRNA-expression and protein deposition in human atherosclerosis, which in part explains the low levels of heparan sulfate in this disease.