Novel therapeutic targets and emerging treatments for atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of morbidity and mortality worldwide. Even with excellent control of low-density lipoprotein cholesterol (LDL-C) levels, adverse cardiovascular events remain a significant clinical problem worldwide, including among those without any traditional ASCVD risk factors. It is necessary to identify novel sources of residual risk and to develop targeted strategies that address them. Lipoprotein(a) has become increasingly recognized as a new cardiovascular risk determinant. Large-scale clinical trials have also signalled the potential additive cardiovascular benefits of decreasing triglycerides beyond lowering LDL-C levels. Since CANTOS (Anti-inflammatory Therapy with Canakinumab for Atherosclerotic Disease) demonstrated that antibodies against interleukin-1β may decrease recurrent cardiovascular events in secondary prevention, various anti-inflammatory medications used for rheumatic conditions and new monoclonal antibody therapeutics have undergone rigorous evaluation. These data build towards a paradigm shift in secondary ASCVD prevention, underscoring the value of targeting multiple biological pathways in the management of both lipid levels and systemic inflammation. Evolving knowledge of the immune system, and the gut microbiota may result in opportunities for modifying previously unrecognized sources of residual inflammatory risk. This review provides an overview of novel therapeutic targets for ASCVD and emerging treatments with a focus on mechanisms, efficacy, and safety.

Differences in predictors of incident heart failure according to atherosclerotic cardiovascular disease status

AIMS

Heart failure (HF) is a common cause of morbidity and mortality, related to a broad range of sociodemographic, lifestyle, cardiometabolic, and comorbidity risk factors, which may differ according to the presence of atherosclerotic cardiovascular disease (ASCVD). We assessed the association between incident HF with baseline status across these domains, overall and separated according to ASCVD status.

METHODS AND RESULTS

We included 5758 participants from the Baker Biobank cohort without HF at baseline enrolled between January 2000 and December 2011. The primary endpoint was incident HF, defined as hospital admission or HF-related death, determined through linkage with state-wide administrative databases (median follow-up 12.2 years). Regression models were fitted adjusted for sociodemographic variables, alcohol intake, smoking status, measures of adiposity, cardiometabolic profile measures, and individual comorbidities. During 65 987 person-years (median age 59 years, 38% women), incident HF occurred among 784 participants (13.6%) overall. Rates of incident HF were higher among patients with ASCVD (624/1929, 32.4%) compared with those without ASCVD (160/3829, 4.2%). Incident HF was associated with age, socio-economic status, alcohol intake, smoking status, body mass index (BMI), waist circumference, waist-hip ratio, systolic blood pressure (SBP), and low- and high-density lipoprotein cholesterol (LDL-C and HDL-C), with non-linear relationships observed for age, alcohol intake, BMI, waist circumference, waist-hip ratio, SBP, LDL-C, and HDL-C. Risk factors for incident HF were largely consistent regardless of ASCVD status, although diabetes status had a greater association with incident HF among patients without ASCVD.

CONCLUSIONS

Incident HF is associated with a broad range of baseline sociodemographic, lifestyle, cardiometabolic, and comorbidity factors, which are mostly consistent regardless of ASCVD status. These data could be useful in efforts towards developing risk prediction models that can be used in patients with ASCVD.

Asymptomatic people with well-controlled HIV do not have abnormal left ventricular global longitudinal strain

Background

Previous studies have reported impairment in systolic and diastolic function in people with HIV (PWHIV). Our aim was to determine if echocardiographically measured left ventricular (LV) global longitudinal strain (GLS) is abnormal in asymptomatic PWHIV.

Methods

A cross-sectional study of PWHIV (n = 98, 89% male, median age 53 years) and HIV-negative people (n = 50, median age 53 years) without known cardiovascular disease were recruited from a single centre. All participants completed a health/lifestyle questionnaire, provided a fasting blood sample, and underwent a comprehensive echocardiogram for assessment of diastolic and systolic LV function, including measurement of GLS.

Results

All PWHIV were receiving antiretroviral therapy (ART) for a median of 12 years (IQR: 6.9, 22.4), the majority with good virological control (87% suppressed) and without immunological compromise (median CD4 598 cells/µl, IQR: 388, 841). Compared with controls of similar age and gender, there was no difference in GLS [mean GLS -20.3% (SD 2.5%) vs. -21.0% (SD 2.5%), p = 0.14] or left ventricular ejection fractions [65.3% (SD 6.3) vs. 64.8% (SD 4.8), p = 0.62]. Following adjustment for covariates (gender, heart rate, systolic and diastolic blood pressure, and fasting glucose), the difference in GLS remained non-significant. There were no differences in LV diastolic function between the groups. Exposure to at least one mitochondrially toxic ART drug (didanosine, stavudine, zidovudine, or zalcitabine) was not associated with impairment of LV systolic function.

Conclusion

No clinically significant impairment of myocardial systolic function, as measured by LV GLS, was detected in this predominantly Caucasian male population of PWHIV on long-term ART, with no history of cardiovascular disease.

Impact of rosuvastatin on atherosclerosis in people with HIV at moderate cardiovascular risk: a randomised, controlled trial

BACKGROUND

People living with HIV-1 (PLHIV) are at increased risk for cardiovascular disease.

OBJECTIVE

This study aimed to determine if PLHIV would benefit from starting statins at a lower threshold than currently recommended in the general population.

DESIGN

A double-blind multicentre, randomised, placebo-controlled trial was performed.

METHODS

Participants (n = 88) with well controlled HIV, at moderate cardiovascular risk (Framingham score of 10-15%), and not recommended for statins were recruited from Australia and Switzerland. They were randomized 1 : 1 to rosuvastatin (n = 44) 20 mg daily, 10 mg if co-administered with ritonavir/cobicistat-boosted antiretroviral therapy, or placebo (n = 40) for 96 weeks. Assessments including fasting blood collection and carotid--intima media thickness (CIMT) were performed at baseline, and weeks 48 and 96. The primary outcome was the change from baseline to week 96 in CIMT (clinicaltrials.gov: NCT01813357).

RESULTS

Participants were predominantly men [82 (97.6%); mean age 54 years (SD 6.0)]. At 96 weeks, there was no difference in the progression of CIMT between the rosuvastatin (mean 0.004 mm, SE 0.0036) and placebo (0.0062 mm, SE 0.0039) arms (P = 0.684), leading to no difference in CIMT levels between groups at week 96 [rosuvastatin arm, 0.7232 mm (SE 0.030); placebo arm 0.7785 mm (SE 0.032), P = 0.075].Adverse events were common (n = 146) and predominantly in the rosuvastatin arm [108 (73.9%)]. Participants on rosuvastatin were more likely to cease study medication because of an adverse event [7 (15.9%) vs. 2 (5.0%), P = 0.011].

CONCLUSION

In PLHIV, statins prescribed at a lower threshold than guidelines did not lead to improvements in CIMT but was associated with significant adverse events.

The Baker Biobank: Understanding Cardiovascular Outcomes

BACKGROUND

Cardiovascular diseases (CVDs) and diabetes are two of the most important public health problems. Outcomes for patients with these disorders vary considerably, likely due to the added influence of a range of interacting clinical, metabolic, environmental, lifestyle, genetic and psychosocial risk factors associated with these diseases. The Baker Biobank study was designed to characterise these factors to inform better risk prediction, earlier diagnosis and better treatment of CVDs and diabetes.

METHODS

This paper describes the detailed methods for the establishment of the Baker Biobank. The study collected extensive phenotypic detail about the participants recruited from Victoria, Australia. Data and samples were collected at the Departments of Cardiology and Respiratory Medicine at the Alfred Hospital and Healthy Hearts Program at the Baker Institute.

RESULTS

A total of 6,530 adults with age 18-69 years were recruited into the Biobank. The majority of these participants (63%) were male. The mean (standard deviation [SD]) age of the Biobank Cohort at the time of data collection was 57(15) years. The study collected data on socio-demographic characteristics, behavioural and lifestyle factors, anthropometric measurements, medical and medication history, and blood levels of various biomarkers. The study also collected and stored Guthrie cards, serum, plasma, buffy coat, whole blood collected in Tempus tubes (for RNA extraction). For some samples extracted DNA and RNA is stored. The Biobank data is also linked to echocardiogram, hospital admission, pathology and mortality datasets. The Baker Biobank data and samples are available for health researchers with approval of Biobank Steering Group and Human Research Ethics Committee.

CONCLUSION

The Baker Biobank provides valuable data and samples into the study of the interplay among cardiovascular diseases risk factors and their impact on morbidity and mortality in Australia.

HIV disease, metabolic dysfunction and atherosclerosis: A three year prospective study

HIV infection is known to be associated with cardiometabolic abnormalities; here we investigated the progression and causes of these abnormalities. Three groups of participants were recruited: HIV-negative subjects and two groups of treatment-naïve HIV-positive subjects, one group initiating antiretroviral treatment, the other remaining untreated. Intima-media thickness (cIMT) increased in HIV-positive untreated group compared to HIV-negative group, but treatment mitigated the difference. We found no increase in diabetes-related metabolic markers or in the level of inflammation in any of the groups. Total cholesterol, low density lipoprotein cholesterol and apoB levels were lower in HIV-positive groups, while triglyceride and Lp(a) levels did not differ between the groups. We found a statistically significant negative association between viral load and plasma levels of total cholesterol, LDL cholesterol, HDL cholesterol, apoA-I and apoB. HIV-positive patients had hypoalphalipoproteinemia at baseline, and we found a redistribution of sub-populations of high density lipoprotein (HDL) particles with increased proportion of smaller HDL in HIV-positive untreated patients, which may result from increased levels of plasma cholesteryl ester transfer protein in this group. HDL functionality declined in the HIV-negative and HIV-positive untreated groups, but not in HIV-positive treated group. We also found differences between HIV-positive and negative groups in plasma abundance of several microRNAs involved in lipid metabolism. Our data support a hypothesis that cardiometabolic abnormalities in HIV infection are caused by HIV and that antiretroviral treatment itself does not influence key cardiometabolic parameters, but mitigates those affected by HIV.

Role of intramural platelet thrombus in the pathogenesis of wall rupture and intra-ventricular thrombosis following acute myocardial infarction

Left ventricular thrombus (LVT) and rupture are important mechanical complications following myocardial infarction (MI) and are believed to be due to unrelated mechanisms. We studied whether, in fact, wall rupture and LVT are closely related in their pathogenesis with intramural platelet thrombus (IMT) playing a pivotal role. Male 129sv and C57Bl/6 mice underwent operation to induce MI, and autopsy was performed to confirm rupture deaths. Haemodynamic features of rupture events were monitored by telemetry in conscious mice. Detailed histological examination was conducted with special attention to the presence of IMT in relation to rupture location and LVT formation. IMT was detected in infarcted hearts of 129sv (82%) and C57Bl/6 (39%) mice with rupture in the form of a narrow streak spanning the wall or an occupying mass dissecting the infarcted myofibers apart. IMT often contained dense inflammatory cells and blood clot, indicating a dynamic process of thrombus formation and destruction. Notably, IMT was found extending into the cavity to form LVT. Haemodynamic monitoring by telemetry revealed that rupture occurred either as a single event or recurrent episodes. Importantly, the anti-platelet drug clopidogrel, but not aspirin, reduced the prevalence of rupture (10% vs. 45%) and IMT, and suppressed the degree of inflammation. Thus, IMT is a key pathological element in the infarcted heart closely associated with the complications of rupture and LVT. IMT could be either triggered by a wall tear or act as initiator of rupture. IMT may propagate towards the ventricular chamber to trigger LVT.

Impact of High-Sensitivity Troponin I Testing with Sex-Specific Cutoffs on the Diagnosis of Acute Myocardial Infarction

BACKGROUND

High-sensitivity cardiac troponin I (hs-cTnI) assays show sex-dependent differences in the 99th percentile of healthy populations, with concentrations in women approximately 50% lower. The adoption of sex-specific cutoffs seems appropriate, although it is not yet clear what effect these will have on acute myocardial infarction (AMI) diagnosis and management.

METHODS

We conducted a retrospective pre- and postchangeover analysis of troponin I testing in the 6 months before and after moving from the contemporary Abbott Architect TnI assay (cTnI) to hs-cTnI at 2 tertiary centers in Australia and New Zealand. The cTnI cutoff was 30 ng/L for both sexes, whereas a female-specific cutoff of 16 ng/L was adopted upon changeover to hsTnI.

RESULTS

Changeover from the cTnI assay to the hs-cTnI assay increased the number of female patients with increased troponin I concentrations at both sites (from 29.7% to 34.9% and from 22.4% to 30.8%; P < 0.001). There was no statistically significant change in the number of men with increased concentrations in the same time period (P = 0.09). The increased percentage of women with increased troponin I was not associated with an increase in the number of women with AMI diagnoses at either center. Angiographic data available from 1 center showed no change in the percentage of angiograms performed in women.

CONCLUSIONS

Although increasing the proportion of women with increased troponin I, adopting sex-specific cutoffs with the hs-cTnI assay did not lead to an increase in AMI diagnoses in females, or in the number of women undergoing angiography.

How do we improve peer review for manuscripts from culturally divergent origins?

Objective and informed peer review is critically important to the progress of science. These standards can sometimes be at risk in the evaluation of manuscripts from less culturally familiar places and such evaluations therefore require particular vigilance. Alternative publication strategies may be particularly helpful in these circumstances.

Internal relationship between symptomatic venous thromboembolism and risk factors: up-regulation of integrin β1, β2 and β3 levels

BACKGROUND

To compare different expression of core proteins among venous thromboembolism (VTE) and those with risk factor groups and analyze the relative risk for VTE after integrating integrin β1, β2 and β3 expression.

METHODS

A total of 1006 subjects were recruited and divided into VTE group, risk factor groups and control (non- risk factor) group. Flow cytometry was performed to detect the expression of integrin β1, β2 and β3. The relative risk for VTE was evaluated with independent, parallel and serial methods.

RESULTS

The expression of integrin β1 increased markedly in VTE patients, and those with risk factors (acute infection, malignancy, and autoimmune diseases), respectively (P < 0.001 or 0.01). The expression of integrin β1 in trauma/surgery group was not significantly different with control group (P > 0.05). The expression of integrin β2 or β3 significantly increased in VTE group, but that in risk factor groups was not significantly increased (P > 0.05). Multivariate analysis revealed the trauma/surgery groups had no significantly increased risk for VTE.

CONCLUSIONS

VTE group patients have significantly increased expression of integrin β1, β2 and β3, and risk factor groups (acute infection, malignancy and autoimmune disease) have significantly increased expression of integrin β1. The significant increase in integrin β2, β3 expression is a marker differentiating of VTE group patients with other risk factor groups. Trauma/surgery group has no increased expression of integrin β1, β2 and β3 as other risk factors. Thus, that trauma/surgery may be not the "true" risk factor for VTE.

Haemodynamical stress in mouse aortic arch with atherosclerotic plaques: Preliminary study of plaque progression

Atherosclerotic plaques develop at particular sites in the arterial tree, and this regional localisation depends largely on haemodynamic parameters (such as wall shear stress; WSS) as described in the literature. Plaque rupture can result in heart attack or stroke and hence understanding the development and vulnerability of atherosclerotic plaques is critically important. The purpose of this study is to characterise the haemodynamics of blood flow in the mouse aortic arch using numerical modelling. The geometries are digitalised from synchrotron imaging and realistic pulsatile blood flow is considered under rigid wall assumptions. Two cases are considered; arteries with and without plaque. Mice that are fed under fat diet present plaques in the aortic arch whose size is dependent on the number of weeks under the diet. The plaque distribution in the region is however relatively constant through the different samples. This result underlines the influence of the geometry and consequently of the wall shear stresses for plaque formation with plaques growing in region of relative low shear stresses. A discussion of the flow field in real geometry in the presence and absence of plaques is conducted. The presence of plaques was shown to alter the blood flow and hence WSS distribution, with regions of localised high WSS, mainly on the wall of the brachiocephalic artery where luminal narrowing is most pronounced. In addition, arch plaques are shown to induce recirculation in the blood flow, a phenomenon with potential influence on the progression of the plaques. The oscillatory shear index and the relative residence time have been calculated on the geometry with plaques to show the presence of this recirculation in the arch, an approach that may be useful for future studies on plaque progression.

C-reactive protein as a predictor of cardiovascular risk in HIV-infected individuals

Background In some studies HIV infection confers approximately two-fold higher risk of cardiac events compared with the general population. C-reactive protein (CRP) is a well-characterised biomarker of cardiac events in the general population and is also elevated in patients with HIV infection. The aim of this study was to determine the predictive value of CRP for cardiac events in HIV-infected individuals.

METHODS

We retrospectively analysed CRP levels in stored plasma samples from HIV-infected patients who did or did not experience a coronary event in a case-controlled manner. All CRP measurements were performed using a high-sensitivity assay (hs-CRP).

RESULTS

Of the study participants with samples available, we found slightly elevated hs-CRP levels in the cardiac cases (median 3.5, IQR 1.6-14.4, n=23) compared with controls (median 2.6, IQR1.2-8.3, n=49) which were shown to not be statistically significant P=0.20. Analysis of CRP as a binary variable (≥5mgL(-1)) was also not statistically significant (OR: 1.32, 95% CI 0.48-3.63).

CONCLUSIONS

CRP levels may indicate elevated risk of future cardiac events, however this must be interpreted with caution due to the generalised elevation of CRP during HIV infection. CRP has no predictive value for atherosclerosis, and further research is required to improve early prediction of cardiovascular disease in HIV infection.

The effect of HIV infection on atherosclerosis and lipoprotein metabolism: a one year prospective study

OBJECTIVES

HIV infection is associated with dyslipidaemia and increased risk of cardiovascular disease. The effects of HIV infection and antiretroviral treatment on surrogate markers of atherosclerosis, and lipoprotein metabolism were evaluated in a 12 month prospective study.

METHODS AND RESULTS

Treatment-naive HIV patients were recruited into one of three groups: untreated HIV infection not likely to require initiation of antiretroviral therapy (ART) for at least 12 months; initiating treatment with non nucleoside reverse transcriptase inhibitor-containing ART regimen and initiating treatment with protease inhibitor-containing ART regimen. The patients underwent assessment of carotid intima-media thickness (cIMT), pulse wave velocity (PWV), brachial flow-mediated dilation (FMD) and variables of plasma lipoprotein metabolism at baseline and 12 months. The findings were compared with published values for age and sex matched HIV-negative healthy subjects in a cross-sectional fashion. cIMT and FMD were lower while PWV was higher in HIV-patients compared with HIV-negative individuals; none of the markers changed significantly during 12 months follow up. HIV patients had hypoalphalipoproteinemia and elevated plasma levels of lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein. The only significant changes in lipid-related variables were elevation of total cholesterol and triglycerides in patients treated with PI-containing regimen and elevation of plasma LCAT levels in patients treated with NNRTI-containing regimen. The ability of whole and apoB-depleted plasma to effect cholesterol efflux was not impaired in all three groups.

CONCLUSIONS

This study did not find evidence for rapid progression of subclinical atherosclerosis and deterioration of dyslipidaemia in HIV patients within 1 year.

PAK4 kinase activity and somatic mutation promote carcinoma cell motility and influence inhibitor sensitivity

Hepatocyte growth factor (HGF) and its receptor (c-Met) are associated with cancer cell motility and invasiveness. p21-activated kinase 4 (PAK4), a potential therapeutic target, is recruited to and activated by c-Met. In response, PAK4 phosphorylates LIM kinase 1 (LIMK1) in an HGF-dependent manner in metastatic prostate carcinoma cells. PAK4 overexpression is known to induce increased cell migration speed but the requirement for kinase activity has not been established. We have used a panel of PAK4 truncations and mutations in a combination of over-expression and RNAi rescue experiments to determine the requirement for PAK4 kinase activity during carcinoma cell motility downstream of HGF. We find that neither the kinase domain alone nor a PAK4 mutant unable to bind Cdc42 is able to fully rescue cell motility in a PAK4-deficient background. Nevertheless, we find that PAK4 kinase activity and associated LIMK1 activity are essential for carcinoma cell motility, highlighting PAK4 as a potential anti-metastatic therapeutic target. We also show here that overexpression of PAK4 harboring a somatic mutation, E329K, increased the HGF-driven motility of metastatic prostate carcinoma cells. E329 lies within the G-loop region of the kinase. Our data suggest E329K mutation leads to a modest increase in kinase activity conferring resistance to competitive ATP inhibitors in addition to promoting cell migration. The existence of such a mutation may have implications for the development of PAK4-specific competitive ATP inhibitors should PAK4 be further explored for clinical inhibition.