Michael J. Lipinski

Detecting and assessing macrophages in vivo to evaluate atherosclerosis noninvasively using molecular MRI.

We investigated the ability of targeted immunomicelles to detect and assess macrophages in atherosclerotic plaque using MRI in vivo. There is a large clinical need for a noninvasive tool to assess atherosclerosis from a molecular and cellular standpoint. Macrophages play a central role in atherosclerosis and are associated with plaques vulnerable to rupture. Therefore, macrophage scavenger receptor (MSR) was chosen as a target for molecular MRI. MSR-targeted immunomicelles, micelles, and gadolinium–diethyltriaminepentaacetic acid (DTPA) were tested in ApoE−/− and WT mice by using in vivo MRI. Confocal laser-scanning microscopy colocalization, macrophage immunostaining and MRI correlation, competitive inhibition, and various other analyses were performed. In vivo MRI revealed that at 24 h postinjection, immunomicelles provided a 79% increase in signal intensity of atherosclerotic aortas in ApoE−/− mice compared with only 34% using untargeted micelles and no enhancement using gadolinium–DTPA. Confocal laser-scanning microscopy revealed colocalization between fluorescent immunomicelles and macrophages in plaques. There was a strong correlation between macrophage content in atherosclerotic plaques and the matched in vivo MRI results as measured by the percent normalized enhancement ratio. Monoclonal antibodies to MSR were able to significantly hinder immunomicelles from providing contrast enhancement of atherosclerotic vessels in vivo. Immunomicelles provided excellent validated in vivo enhancement of atherosclerotic plaques. The enhancement seen is related to the macrophage content of the atherosclerotic vessel areas imaged. Immunomicelles may aid in the detection of high macrophage content associated with plaques vulnerable to rupture.

MRI to detect atherosclerosis with gadolinium-containing immunomicelles targeting the macrophage scavenger receptor.

The ability to specifically image macrophages may enable improved detection and characterization of atherosclerosis. In this study we evaluated the in vitro uptake of gadolinium (Gd)‐containing immunomicelles (micelles linked to macrophage‐specific antibody), micelles, and standard contrast agents by murine macrophages, and sought to determine whether immunomicelles and micelles improve ex vivo imaging of apolipoprotein E knockout (ApoE KO) murine atherosclerosis. Murine RAW 264.7 macrophages were incubated with Gd‐DTPA, micelles, and immunomicelles. Cell pellets were prepared and imaged using a 1.5 T MR system with an inversion recovery spin‐echo sequence to determine the in vitro T1 values. Ex vivo analysis of mouse aortas was performed using a 9.4T MR system with a high‐spatial‐resolution sequence (78 × 39 × 78 μm3). The T1 value was significantly decreased in cells treated with micelles compared to Gd‐DTPA (P < 0.0001), and in cells incubated at 4°C with immunomicelles compared to micelles (P < 0.05). Ex vivo MRI signal intensity (SI) was significantly increased by 81% and 20% in aortas incubated with immunomicelles and micelles, respectively. Confocal microscopy demonstrated in vitro and ex vivo uptake of fluorescent immunomicelles by macrophages. Immunomicelles and micelles improve in vitro and ex vivo MR detection of macrophages, and may prove useful in the detection of macrophage‐rich plaques. Magn Reson Med, 2006.

The impact of proprotein convertase subtilisin-kexin type 9 serine protease inhibitors on lipid levels and outcomes in patients with primary hypercholesterolaemia: a network meta-analysis.

AIMS We performed a network meta-analysis of randomized controlled trials (RCTs) in patients with primary hypercholesterolaemia to compare the impact of proprotein convertase subtilisin-kexin type 9 serine protease (PCSK9) inhibitors with placebo and ezetimibe on lipid levels and outcomes. METHODS AND RESULTS MEDLINE/PubMed, Cochrane CENTRAL, and ClinicalTrials.gov were searched for RCTs assessing PCSK9 inhibitors vs. other therapies in patients with primary hypercholesterolaemia. Network meta-analysis with both a frequentist approach and a Bayesian framework was performed to directly and indirectly compare PCSK9 inhibition on lipid levels with ezetimibe and placebo. Odds ratios with 95% confidence intervals (OR [95% CIs]) were generated with random-effects models to compare outcomes. Our meta-analysis included 17 RCTs with 13 083 patients that were randomized to PCSK9 inhibitors (n = 8250), placebo (n = 3957), ezetimibe (n = 846), or PCSK9 inhibitors and ezetimibe (n = 30). The mean age was 59 ± 10, 52% were male, 34% had coronary artery disease, 51% had hypertension, 19% had diabetes mellitus, baseline LDL of 122 ± 36 mg/dL, total cholesterol of 199 ± 39 mg/dL, and HDL of 51 ± 14 mg/dL. inhibitors significantly reduced LDL cholesterol by 57% relative to placebo (P < 0.001) and 36.1% relative to ezetimibe (P < 0.001). Proprotein convertase subtilisin-kexin type 9 serine protease inhibitors reduced the incidence of all-cause mortality [OR 0.43 (95% CI 0.22-0.82), P = 0.01] but was associated with an increased incidence of neurocognitive adverse events [OR 2.34 (95% CI 1.11-4.93), I(2) = 4%, P = 0.02] when compared with placebo. CONCLUSION Proprotein convertase subtilisin-kexin type 9 serine protease inhibition significantly improved lipid profiles and reduced the incidence of all-cause mortality compared with placebo but had a higher rate of neurocognitive adverse events. Thus, PCSK9 inhibitor therapy may serve as an alternative for patients with statin intolerance and for those who do not respond to other lipid reduction therapy.

Late gadolinium enhancement on cardiac magnetic resonance predicts adverse cardiovascular outcomes in nonischemic cardiomyopathy: a systematic review and meta-analysis.

Background—Late gadolinium enhancement (LGE) by cardiac MR (CMR) is a predictor of adverse cardiovascular outcomes in patients with nonischemic cardiomyopathy (NICM). However, these findings are limited by single-center studies, small sample sizes, and low event rates. We performed a meta-analysis to evaluate the prognostic role of LGE by CMR (LGE-CMR) imaging in patients with NICM. Methods and Results—PubMed, Cochrane CENTRAL, and EMBASE were searched for studies looking at the prognostic value of LGE-CMR in patients with NICM. The primary end points included all-cause mortality, heart failure hospitalization, and a composite end point of sudden cardiac death (SCD) or aborted SCD. Pooling of odds ratios was performed using a random-effect model, and annualized event rates were assessed. Data were included from 9 studies with a total of 1488 patients and a mean follow-up of 30 months. Patients had a mean age of 52 years, 67% were men, and the average left ventricular ejection fraction was 37% on CMR. LGE was present in 38% of patients. Patients with LGE had increased overall mortality (odds ratio, 3.27; P<0.00001), heart failure hospitalization (odds ratio, 2.91; P=0.02), and SCD/aborted SCD (odds ratio, 5.32; P<0.00001) compared with those without LGE. The annualized event rates for mortality were 4.7% for LGE+ subjects versus 1.7% for LGE− subjects (P=0.01), 5.03% versus 1.8% for heart failure hospitalization (P=0.002), and 6.0% versus 1.2% for SCD/aborted SCD (P<0.001). Conclusions—LGE in patients with NICM is associated with increased risk of all-cause mortality, heart failure hospitalization, and SCD. Detection of LGE by CMR has excellent prognostic characteristics and may help guide risk stratification and management in patients with NICM.

Prognostic value of stress cardiac magnetic resonance imaging in patients with known or suspected coronary artery disease: a systematic review and meta-analysis.

OBJECTIVES This study sought to perform a systematic review and meta-analysis to understand the role of stress cardiac magnetic resonance imaging (CMR) in assessing cardiovascular prognosis in patients with known or suspected coronary artery disease (CAD). BACKGROUND Although stress CMR is excellent for the diagnosis of obstructive CAD, the prognostic value of stress CMR has been less well described. METHODS PubMed, Cochrane CENTRAL, and metaRegister of Controlled Trials were searched for stress CMR studies with >6 months of prognostic data. Primary endpoints were cardiovascular death, myocardial infarction (MI), and a composite outcome of cardiovascular death or MI during follow-up. Summary effect estimates were generated with random-effects modeling, and annualized event rates were assessed. RESULTS Nineteen studies (14 vasodilator, 4 dobutamine, and 1 that used both) involved a total of 11,636 patients with a mean follow-up of 32 months. Patients had a mean age of 63 ± 12 years, 63% were male, and 26% had previous MI; mean left ventricular ejection fraction was 61 ± 12%; and late gadolinium enhancement was present in 29% and ischemia in 32%. Patients with ischemia had a higher incidence of MI (odds ratio [OR]: 7.7; p < 0.0001), cardiovascular death (OR: 7.0; p < 0.0001), and the combined endpoint (OR: 6.5; p < 0.0001) compared with those with a negative study. The combined outcome annualized events rates were 4.9% for a positive versus 0.8% for a negative stress CMR (p < 0.0001), 2.8% versus 0.3% for cardiovascular death (p < 0.0001), and 2.6% versus 0.4% for MI (p < 0.0005). The presence of late gadolinium enhancement was also significantly associated with a worse prognosis. CONCLUSIONS A negative stress CMR study is associated with very low risk of cardiovascular death and MI. Stress CMR has excellent prognostic characteristics and may help guide risk stratification of patients with known or suspected CAD.

Scaffold Thrombosis After Percutaneous Coronary Intervention With ABSORB Bioresorbable Vascular Scaffold: A Systematic Review and Meta-Analysis

OBJECTIVES The aim of this study was to determine the risk of scaffold thrombosis (ST) after percutaneous coronary intervention (PCI) with placement of an ABSORB bioresorbable vascular scaffold (BVS) (Abbott Vascular, Santa Clara, California) by conducting a systematic review and meta-analysis. BACKGROUND PCI with BVS placement holds great potential, but concern has recently been raised regarding the risk of ST. METHODS MEDLINE/PubMed, Cochrane CENTRAL, and meeting abstracts were searched for all studies that included outcomes data for patients after PCI with BVS placement. For studies comparing BVSs with drug-eluting stents (DES), pooled estimates of outcomes, presented as odds ratios (ORs) with 95% confidence intervals (CIs), were generated with random-effects models. RESULTS Our analysis included 10,510 patients (8,351 with a BVS and 2,159 with DES) with a follow-up of 6.4 ± 5.1 months and 60 ± 11 years of age; 78% were male, 36% had stable angina, and 59% had acute coronary syndrome (ACS). Among patients with a BVS, cardiovascular death occurred in 0.6%, myocardial infarction (MI) in 2.1%, target lesion revascularization in 2.0%, and definite/probable ST in 1.2% of patients. Of BVS patients, 0.27% had acute ST and 0.57% had subacute ST. Meta-analysis demonstrated that patients who received a BVS were at a higher risk of MI (OR: 2.06, 95% CI: 1.31 to 3.22, p = 0.002) and definite/probable ST (OR: 2.06, 95% CI: 1.07 to 3.98, p = 0.03) compared with patients who received DES, whereas there was a trend toward decreased all-cause mortality with a BVS (OR: 0.40, 95% CI: 0.15 to 1.06, p = 0.06). CONCLUSIONS Patients undergoing PCI with a BVS had increased definite/probable ST and MI during follow-up compared with DES. Further studies with long-term follow-up are needed to assess the risk of ST with a BVS.

Lymphocytes and the Adventitial Immune Response in Atherosclerosis

Although much of the research on atherosclerosis has focused on the intimal accumulation of lipids and inflammatory cells, there is an increasing amount of interest in the role of the adventitia in coordinating the immune response in atherosclerosis. In this review of the contributions of the adventitia and adventitial lymphocytes to the development of atherosclerosis, we discuss recent research on the formation and structural nature of adventitial immune aggregates, potential mechanisms of crosstalk between the intima, media, and adventitia, specific contributions of B lymphocytes and T lymphocytes, and the role of the vasa vasorum and surrounding perivascular adipose tissue. Furthermore, we highlight techniques for the imaging of lymphocytes in the vasculature.

Meta-Analysis of Randomized Controlled Trials of Statins Versus Placebo in Patients With Heart Failure

Although statins have been shown to improve outcomes in retrospective analyses of patients with heart failure (HF), recent randomized placebo-controlled trials have shown mixed results. The goal of this study was to systematically review randomized trials comparing statins to placebo for HF and compare the impact of different statins. CENTRAL, mRCT, and PubMed were searched for eligible studies that prospectively randomized patients with HF to statins or placebo. Primary end points were all-cause mortality, cardiovascular mortality, hospitalization for worsening HF, adverse drug events, and changes in left ventricular ejection fraction (LVEF). Pooling was performed with random effect methods with summary effect estimates (95% confidence intervals). Ten studies (10,192 patients) with follow-up from 3 to 47 months were included. Three trials randomized patients to rosuvastatin, 1 to simvastatin, and 6 to atorvastatin. Overall, statins did not affect all-cause or cardiovascular mortality but did significantly decrease hospitalization for worsening HF during follow-up (odds ratio [OR] 0.67, p = 0.008). Patients randomized to statins had a significant 4.2% increase in LVEF at follow-up (95% confidence interval 1.3 to 7.1, p = 0.004). Furthermore, post hoc analyses showed heterogeneity among different statins and demonstrated that randomization to atorvastatin significantly decreased all-cause mortality (OR 0.39, p = 0.004), decreased hospitalization for worsening HF (OR 0.30, p <0.000 01), and randomization to atorvastatin and simvastatin led to a significant improvement in LVEF, whereas these benefits were not observed in patients randomized to rosuvastatin. In conclusion, meta-analysis of randomized controlled trials demonstrated that statins are safe and improve LVEF and decrease hospitalization for worsening HF.

B-Cell Aortic Homing and Atheroprotection Depend on Id3

Rationale: B cells are abundant in the adventitia of normal and diseased vessels. Yet, the molecular and cellular mechanisms mediating homing of B cells to the vessel wall and B-cell effects on atherosclerosis are poorly understood. Inhibitor of differentiation-3 (Id3) is important for atheroprotection in mice and polymorphism in the human ID3 gene has been implicated as a potential risk marker of atherosclerosis in humans. Yet, the role of Id3 in B-cell regulation of atherosclerosis is unknown. Objective: To determine if Id3 regulates B-cell homing to the aorta and atheroprotection and identify molecular and cellular mechanisms mediating this effect. Methods and Results: Loss of Id3 in Apoe−/− mice resulted in early and increased atherosclerosis. Flow cytometry revealed a defect in Id3−/− Apoe−/− mice in the number of B cells in the aorta but not the spleen, lymph nodes, and circulation. Similarly, B cells transferred from Id3−/− Apoe−/− mice into B-cell–deficient mice reconstituted spleen, lymph node, and blood similarly to B cells from Id3+/+ Apoe−/− mice, but aortic reconstitution and B-cell–mediated inhibition of diet-induced atherosclerosis was significantly impaired. In addition to retarding initiation of atherosclerosis, B cells homed to regions of existing atherosclerosis, reduced macrophage content in plaque, and attenuated progression of disease. The chemokine receptor CCR6 was identified as an important Id3 target mediating aortic homing and atheroprotection. Conclusions: Together, these results are the first to identify the Id3-CCR6 pathway in B cells and demonstrate its role in aortic B-cell homing and B-cell–mediated protection from early atherosclerosis.

Survival and cardiac remodeling benefits in patients undergoing late percutaneous coronary intervention of the infarct-related artery: evidence from a meta-analysis of randomized controlled trials

OBJECTIVES Our purpose was to perform a systematic review and meta-analysis of randomized trials comparing percutaneous coronary intervention (PCI) of the infarct-related artery (IRA) with medical therapy in patients randomized >12 h after acute myocardial infarction (AMI). BACKGROUND There is ongoing uncertainty about the risk-benefit ratio of late PCI in stable patients with AMI. METHODS PubMed, CENTRAL, and other databases were searched (July 2007). Studies were included if they compared PCI with medical management and randomized patients >12 h and up to 60 days after AMI, and were excluded if patients were hemodynamically unstable. Odds ratios (ORs) were pooled for dichotomous outcomes, with all-cause mortality as the primary end point. Left cardiac remodeling parameters were also pooled with generic inverse-variance weighting. RESULTS We retrieved 10 studies that enrolled 3,560 patients, with median time from AMI to randomization of 12 days (range 1 to 26 days), and follow-up of 2.8 years (42 days to 10 years). Randomization allocated 1,779 subjects to PCI and 1,781 to medical treatment. There were 112 (6.3%) and 149 (8.4%) deaths in the 2 groups, respectively, yielding significantly improved survival in the PCI group (OR 0.49 [95% confidence interval (CI) 0.26 to 0.94], p = 0.030). These benefits were associated with similarly favorable effects on cardiac remodeling, such as improved left ventricular ejection fraction in the PCI group (+4.4% change [95% CI 1.1 to 7.6], p = 0.009). CONCLUSIONS Percutaneous coronary intervention of the IRA performed late (12 h to 60 days) after AMI is associated with significant improvements in cardiac function and survival.