Jianhui Zhu

Effects of total pathogen burden on coronary artery disease risk and C-reactive protein levels

Infection and inflammation have been suggested to play roles in coronary artery disease (CAD). We hypothesized that: (1) CAD risk is associated with the aggregate number of pathogens (pathogen burden), and (2) increased pathogen burden is associated with elevated levels of C-reactive protein (CRP), a marker of inflammation. We evaluated 233 patients for CAD. Blood samples from each patient were tested for immunoglobulin-G (IgG) antibodies to cytomegalovirus (CMV), Chlamydia pneumoniae, hepatitis A virus (HAV), herpes simplex virus type 1 (HSV-1) and HSV type 2 (HSV-2), and for the CRP levels. Of the 233 study subjects, 68% had evidence of CAD by coronary angiography. Although the prevalence of seropositivity for each pathogen tended to be higher in the patients with CAD than those without, only the association between CAD and seropositivity to HAV was significant in multivariate analysis. Over 75% of study subjects had been exposed to > or =3 of the 5 pathogens tested, and analysis determined that increasing pathogen burden was significantly associated with increasing CAD risk, even after adjustment for traditional CAD risk factors. The prevalence of CAD was 48%, 69%, and 85% in individuals with antibodies to < or =2 pathogens, to 3 or 4 pathogens, and to 5 pathogens, respectively. A similar association between increasing pathogen burden and CRP levels was also found. The pathogen burden remained a significant predictor of CRP levels after multivariate analysis. Our data suggest that infection does play a role in the genesis of atherosclerosis. However, the risk posed by infection is related to the pathogen burden that may contribute to CAD through inflammatory responses.

Effect of Lower Targets for Blood Pressure and LDL Cholesterol on Atherosclerosis in Diabetes: The SANDS Randomized Trial

CONTEXTnIndividuals with diabetes are at increased risk for cardiovascular disease (CVD), but more aggressive targets for risk factor control have not been tested.nnnOBJECTIVEnTo compare progression of subclinical atherosclerosis in adults with type 2 diabetes treated to reach aggressive targets of low-density lipoprotein cholesterol (LDL-C) of 70 mg/dL or lower and systolic blood pressure (SBP) of 115 mm Hg or lower vs standard targets of LDL-C of 100 mg/dL or lower and SBP of 130 mm Hg or lower.nnnDESIGN, SETTING, AND PARTICIPANTSnA randomized, open-label, blinded-to-end point, 3-year trial from April 2003-July 2007 at 4 clinical centers in Oklahoma, Arizona, and South Dakota. Participants were 499 American Indian men and women aged 40 years or older with type 2 diabetes and no prior CVD events.nnnINTERVENTIONSnParticipants were randomized to aggressive (n=252) vs standard (n=247) treatment groups with stepped treatment algorithms defined for both.nnnMAIN OUTCOME MEASURESnPrimary end point was progression of atherosclerosis measured by common carotid artery intimal medial thickness (IMT). Secondary end points were other carotid and cardiac ultrasonographic measures and clinical events.nnnRESULTSnMean target LDL-C and SBP levels for both groups were reached and maintained. Mean (95% confidence interval) levels for LDL-C in the last 12 months were 72 (69-75) and 104 (101-106) mg/dL and SBP levels were 117 (115-118) and 129 (128-130) mm Hg in the aggressive vs standard groups, respectively. Compared with baseline, IMT regressed in the aggressive group and progressed in the standard group (-0.012 mm vs 0.038 mm; P < .001); carotid arterial cross-sectional area also regressed (-0.02 mm(2) vs 1.05 mm(2); P < .001); and there was greater decrease in left ventricular mass index (-2.4 g/m(2.7) vs -1.2 g/m(2.7); P = .03) in the aggressive group. Rates of adverse events (38.5% and 26.7%; P = .005) and serious adverse events (n = 4 vs 1; P = .18) related to blood pressure medications were higher in the aggressive group. Clinical CVD events (1.6/100 and 1.5/100 person-years; P = .87) did not differ significantly between groups.nnnCONCLUSIONSnReducing LDL-C and SBP to lower targets resulted in regression of carotid IMT and greater decrease in left ventricular mass in individuals with type 2 diabetes. Clinical events were lower than expected and did not differ significantly between groups. Further follow-up is needed to determine whether these improvements will result in lower long-term CVD event rates and costs and favorable risk-benefit outcomes.nnnTRIAL REGISTRATIONnclinicaltrials.gov Identifier: NCT00047424.

Infection and Atherosclerosis Potential Roles of Pathogen Burden and Molecular Mimicry

Infection has been implicated as a cause of atherosclerosis since the first half of the 19th century. Over the years, sporadic publications have appeared in the literature reflecting a persistent but relatively low level of research activity in this area. In the last decade, however, publications relating to this topic have increased markedly. And very recently, new epidemiological and mechanistic data relating infection to several different diseases, including atherosclerosis, have appeared, stimulating the emergence of important paradigm shifts in how we think about the causes of chronic disease. The following article reviews some of these newer concepts as they relate to a possible role of infection in atherosclerosis.

Cytomegalovirus in the pathogenesis of atherosclerosis: the role of inflammation as reflected by elevated C-reactive protein levels.

OBJECTIVESnWe hypothesized that cytomegalovirus (CMV) infection: 1) stimulates an inflammatory response, reflected by elevated C-reactive protein (CRP) levels, and 2) predisposes to coronary artery disease (CAD), in part, through CMV-induced inflammation.nnnBACKGROUNDnAlthough some studies show an association between CMV and atherosclerosis, others do not. We believed that CMV exerted an atherogenic effect by inducing inflammation, and the disparate results may derive partly from individual variability in the capacity to control CMV inflammatory activity.nnnMETHODSnBlood samples were tested for CMV seropositivity and CRP levels from 238 individuals being evaluated for CAD by coronary angiography.nnnRESULTSnAn elevated CRP level (>0.5 mg/dl) was a significant CAD determinant even after adjustment for traditional CAD risk factors (odds ratio [OR] = 2.4; p = 0.02). Moreover, CMV seropositivity was significantly associated with increased CRP levels (p = 0.04 after adjustment for CAD risk factors), suggesting that CMV could evoke a subclinical inflammatory response. However, considerable host variation existed in this response to CMV. When adjusted for CAD risk factors, the OR for CAD were 1.3 in the subgroup with CMV seropositivity alone (p = 0.7), 2.3 in the subgroup with elevated CRP levels alone (p = 0.2), and 4.3 in the subgroup with combined CMV seropositivity and elevated CRP levels (p = 0.01).nnnCONCLUSIONSnOur results suggest that 1) CMV elicits a subclinical inflammatory response, but only in certain individuals, and 2) individuals with an inflammatory response appear susceptible to the atherogenic effects of CMV, whereas those without appear resistant. These results may partly explain the disparate results of studies attempting to relate CMV to atherogenesis.

Insights into the role of infection in atherogenesis and in plaque rupture.

The potential contribution of infection to the induction and progression of atherosclerosis has been characterized by profound controversy, continuing to the present time. Controversy also surrounds the concept that infection can precipitate plaque rupture, an event complicating the course of atherosclerosis and clinically characterized by acute myocardial infarction and death. The purpose of this article is (1) to review what we believe are the most compelling data that either are compatible with or refute the concept that infection plays a role in atherogenesis or plaque rupture; (2) to present the mechanisms that may contribute to such effects; and (3) to discuss the impact on the infection/atherosclerosis paradigm of the recent negative therapeutic trials examining the effects of macrolide antibiotics on cardiovascular end points in patients with coronary artery disease (CAD).nnAlthough anecdotal information existed for many years suggesting that acute infection can trigger an acute myocardial infarction,1,2 it was the groundbreaking work by Minick and Fabricant and their coworkers3,4 in the1970s that began the serious scientific exploration of the relation between infection and atherosclerosis. These investigators demonstrated that Marek’s disease virus, an avian herpesvirus, caused atherosclerotic-like lesions in multiple arteries of chickens and that infection of smooth muscle cells (SMCs) with the virus in vitro caused cholesterol accumulation.nnEvidence was subsequently published extending the infection/atherosclerosis paradigm to humans. Thus, pathogens were found to reside in human atherosclerotic vessels,5–8 and seroepidemiological studies demonstrated an association between pathogen-specific antibodies and atherosclerosis. Such associations were found with multiple pathogens, including cytomegalovirus (CMV), herpes simplex virus (HSV) types 1 and 2, Chlamydia pneumonia , Helicobacter pylori , and hepatitis A virus, as well as periodontal pathogens.9–16 However, other studies failed to show such associations,17,18 leading to discussions of the limitations of seroepidemiological studies in evaluating a causal role between …

The Possible Role of Hepatitis A Virus in the Pathogenesis of Atherosclerosis

The possible association between hepatitis A virus (HAV) infection and coronary artery disease (CAD) was studied. Blood from 391 patients undergoing coronary angiography was tested for serum IgG antibodies to HAV and C-reactive protein (CRP). Of the 391 patients, 205 (52%) had anti-HAV IgG antibodies. CAD prevalence was 74% in HAV-seropositive and 52% in HAV-seronegative patients (P<.0001); significance persisted after adjustment for either traditional CAD risk factors or for risk factors plus other infectious agents (cytomegalovirus, Chlamydia pneumoniae, Helicobacter pylori, and herpes simplex virus). In addition, CRP levels were significantly higher in HAV-seropositive than in HAV-seronegative patients (P=. 013) in both univariate and multivariate analyses. Logistic regression analysis demonstrated that HAV seropositivity is an independent predictor of risk for CAD and elevated CRP levels. HAV infection is therefore associated with CAD, which raises the possibility that this virus may play a causal role in atherogenesis.

Effects of Acute Mental Stress and Exercise on Inflammatory Markers in Patients With Coronary Artery Disease and Healthy Controls

Physical and mental stressors result in increased inflammation markers in populations free of coronary artery disease (CAD). However, inflammatory responses to mental and exercise challenges have not been established in patients with CAD. This study investigated the responses of inflammatory markers, including C-reactive protein (CRP), interleukin-6 (IL-6), and soluble intercellular adhesion molecule-1, in patients with CAD after successful elective percutaneous coronary intervention (n = 36, 59 +/- 8 years of age, 33% women) and healthy controls without a history of CAD (n = 28, 54 +/- 10 years of age, 36% women). Increases in inflammatory markers were examined in response to mental challenge tasks (anger recall and mental arithmetic) and treadmill exercise. Stress echocardiography was used to rule out stress-induced ischemia as a possible confounding factor. Results showed that CRP increased significantly to mental challenge and exercise (p values <0.01), and CRP responses were higher in patients with CAD than in controls (change in mental arithmetic 0.19 +/- 0.11 vs 0.01 +/- 0.03 mg/L, p = 0.003; change in exercise 0.57 +/- 0.11 vs 0.08 +/- 0.0.03 mg/L, p = 0.001). Increased norepinephrine responses were related to larger CRP and IL-6 increases to mental challenge tasks (p values <0.05). Exercise elicited increased CRP, IL-6, and soluble intercellular adhesion molecule-1 levels (p values <0.01), and these responses were larger than with mental challenge tasks (p values <0.05). In conclusion, mental stress and exercise induce increased levels of inflammatory markers in patients with CAD. These stress-induced increases are larger than in healthy subjects, occur in the absence of myocardial ischemia, and are related to the neurohormonal stress response.

Effects of MF-tricyclic, a selective cyclooxygenase-2 inhibitor, on atherosclerosis progression and susceptibility to cytomegalovirus replication in apolipoprotein-E knockout mice ☆

OBJECTIVESnWe examined whether selective cyclooxygenase-2 (COX-2) inhibition in apolipoprotein-E (apoE) deficient mice reduces cytomegalovirus (CMV) replication, and determined whether COX-2 anti-inflammatory activity leads to decreased atherosclerosis.nnnBACKGROUNDnEvidence suggests that CMV infection contributes to atherosclerosis and that this occurs in part through inflammatory mechanisms. Cyclooxygenase-2 inhibitors are potent anti-inflammatory agents. They also inhibit CMV replication in vitro.nnnMETHODSnThe apoE deficient mice were either treated or not treated with a selective COX-2 inhibitor, and either infected or not infected with CMV. Viral deoxyribonucleic acid load in salivary glands was determined by quantitative polymerase chain reaction. Atherosclerotic lesion analysis was performed by standard methods.nnnRESULTSnIn vivo COX-2 inhibition, unexpectedly increased viral load: in the CMV-infected animals viral load was 2.58 +/- 1.0 in the nontreated group, 4.74 +/- 1.38 in the group treated with 12 mg/kg/day MF-tricyclic, and 6.51 +/- 1.64 in the group treated with 24 mg/kg/day MF-tricyclic (p trend = 0.050). This increased viral load was paralleled by increased anti-CMV antibody titers. Most surprisingly, COX-2 inhibition significantly increased early atherosclerotic lesion area, independent of viral infection.nnnCONCLUSIONSnOur study demonstrates that selective inhibition of COX-2 in vivo increases viral load. The finding that inhibition of COX-2 increases atherosclerosis development in apoE deficient mice suggests, unexpectedly, that this enzyme exerts antiatherosclerosis activity, at least in this model.

Lack of association of Helicobacter pylori infection with coronary artery disease and frequency of acute myocardial infarction or death

We investigated the association between Helicobacter pylori (H. pylori) infection and coronary artery disease (CAD) in 2 study populations: (1) a cross-sectional study to determine risk of having CAD, and (2) a longitudinal study to determine risk of acute myocardial infarction (AMI) or death over a mean follow-up period of 3 years in patients with angiographically documented CAD. Blood samples were tested for serum immunoglobulin G antibodies to H. pylori and C-reactive protein (CRP) levels. Study 1: Of 391 patients (62% men, mean age 57 years), 41% had antibodies to H. pylori. CAD prevalence was 70% in H. pylori seropositive patients and 59% in seronegative patients (p = 0.03). Elevated CRP levels (>0.5 mg/dl) were significantly higher in patients with than without CAD (p = 0.02). By univariate analysis, CAD prevalence significantly increased stepwise depending on H. pylori seropositivity and elevated CRP levels (p = 0.008). Significance was lost after adjustment for traditional risk factors. Further analyses revealed that age was the critical confounder. Study 2: Of 929 patients (77% men, mean age 65 years), 56% had antibodies to H. pylori. By univariate analysis, the incidence of AMI or death was 22% in H. pylori seropositive patients and 18% in seronegative patients (p = 0.1). The adjusted hazard ratio of AMI or death for H. pylori seropositivity was 1.12 (95% confidence interval 0.81 to 1.54). Our data suggest that prior infection with H. pylori is not a major factor determining either risk of CAD, AMI, or death in patients with CAD.

IL-6 is produced by splenocytes derived from CMV-infected mice in response to CMV antigens, and induces MCP-1 production by endothelial cells: a new mechanistic paradigm for infection-induced atherogenesis

Abstract Atherosclerosis is an inflammatory disease. One of the candidate inflammatory triggers is infection. To further characterize the interaction between infection, cytokine induction, and atherosclerosis, we tested the hypothesis that cytomegalovirus (CMV) infection induces the pro-inflammatory cytokine interleukin-6 (IL-6), which in turn induces pro-atherosclerotic changes in vascular endothelial cells (ECs). ELISA was used to determine the levels of monocyte chemoattractant protein-1 (MCP-1) in the supernatant of mouse and human ECs incubated with IL-6, and IL-6 levels in supernatants of splenocytes, derived from CMV-infected and uninfected mice, stimulated with mice CMV antigens. IL-6 induced, in a dose response fashion, MCP-1 expression in human ECs: 0, 2, 10, and 50pg/ml IL-6 increased MCP-1 levels in EC conditioned medium from 1120±65 to 1148±105, 1395±40, and 2119±130pg/ml, respectively ( P P P