Comparison of the burden of familial hypercholesterolemia between two cohorts of French Canadians hospitalized 25 years apart for coronary heart disease

BACKGROUND

Familial hypercholesterolemia (FH) is associated with lifelong elevated plasma concentrations of low-density lipoprotein cholesterol (LDL-C) and high risk of premature coronary heart disease (CHD). Clinical recommendations and treatments have emerged to facilitate the management of FH patients. Their impact on the burden of FH is however not well documented.

OBJECTIVE

To compare the burden of FH between patients hospitalized for a CHD event 25 years apart in the French-Canadian founder population.

METHODS

Lipid profiles, cardiovascular risk factors, treatments and FH status of 2,029 patients consecutively hospitalized for an acute CHD event between 2017 and 2022 (2022 Cohort) were compared to those of 2,506 patients with angiographically-confirmed CHD who were admitted between 1995 and 1998 (1998 Cohort).

RESULTS

At the time of admission, 24.6 % of CHD patients had LDL-C levels >5.0 mmol/L in 1998 compared to 1.4 % in 2022, and FH was diagnosed in 9.6 % of patients in the 1998 cohort compared to 5.5 % in 2022 (p<0.001). FH patients hospitalized for a CHD event were older in 2022 than in 1998 (p <0.001). The prevalence of premature CHD requiring a hospitalization significantly decreased from 1998 to 2022 (64.3% vs. 44.1 %, p<0.001). At the moment of admission, 18.2 % of FH patients had LDL-C concentration <2.0 mmol/L in 2022 vs 0 % in 1998 (p <0.001).

CONCLUSIONS

Over 25 years, FH patients tend to be older and contribute to a lower proportion of hospitalizations for CHD in the French-Canadian founder population. Despite significant improvement in diagnosis and treatment, FH management remains however sub-optimal.

Inhibition of Angiopoietin-Like Protein 3 or 3/8 Complex and ApoC-III in Severe Hypertriglyceridemia

PURPOSE OF REVIEW

The role of the inhibition of ANGPTL3 in severe or refractory hypercholesterolemia is well documented, less in severe hyperTG. This review focuses on the preclinical and clinical development of ApoC-III inhibitors and ANGPTL3, 4, and 3/8 complex inhibitors for the treatment of severe or refractory forms of hypertriglyceridemia to prevent cardiovascular disease or other morbidities.

RECENT FINDINGS

APOC3 and ANGPTL3 became targets for drug development following the identification of naturally occurring loss of function variants in families with a favorable lipid profile and low cardiovascular risk. The inhibition of ANGPTL3 covers a broad spectrum of lipid disorders from severe hypercholesterolemia to severe hypertriglyceridemia, while the inhibition of ApoC-III can treat hypertriglyceridemia regardless of the severity. Preclinical and clinical data suggest that ApoC-III inhibitors, ANGPTL3 inhibitors, and inhibitors of the ANGPTL3/8 complex that is formed postprandially are highly effective for the treatment of severe or refractory hypertriglyceridemia. Inhibition of ANGPTL3 or the ANGPTL3/8 complex upregulates LPL and facilitates the hydrolysis and clearance of triglyceride-rich lipoproteins (TRL) (LPL-dependent mechanisms), whereas ApoC-III inhibitors contribute to the management and clearance of TRL through both LPL-dependent and LPL-independent mechanisms making it possible to successfully lower TG in subjects completely lacking LPL (familial chylomicronemia syndrome). Most of these agents are biologicals including monoclonal antibodies (mAb), antisense nucleotides (ASO), small interfering RNA (siRNA), or CRISPR-cas gene editing strategies.

Social representations of intellectual disability; a comparison between cultures

OBJECTIVES

People with Intellectual disability consistently appear to be one of the most looked-down upon and repressed subgroups of society in many cultures. The main aim of this study was to compare social representations of intellectual disability in its various aspects between different cultures.

MATERIALS AND METHODS

The study was conducted in four different sites: Beirut-Lebanon, Algiers-Algeria, Tours-France and Namur-Belgium. Participants were asked to complete a questionnaire evaluating social representations of intellectual disability.

RESULTS

A total of 755 participants consented to take part in the study. Gender only affected social representations in the Lebanese population. Overall, Algerians appeared to have the least positive social representations and Lebanon to have more positive attitudes, while France and Belgium tended to have the most favourable representations.

DISCUSSION AND CONCLUSIONS

Findings highlight the imbalance between a European and a non-European country showing the importance of developing tailored interventions to improve general attitudes towards intellectual disability.

Correlation between chylomicronemia diagnosis scores and post-heparin lipoprotein lipase activity

INTRODUCTION

Sustained chylomicronemia is a defect in post-prandial triglyceride management characterized by severe hypertriglyceridemia (triglyceride > 10 mmol/L) due to functional or genetic defects in lipoprotein lipase (LPL)-mediated triglyceride-rich lipoprotein lipolysis. Familial chylomicronemia syndrome (FCS) is a rare mendelian form of chylomicronemia caused by loss-of-function variants in LPL or LPL-related genes. Most individuals with chylomicronemia however present multifactorial chylomicronemia (MCS), in which LPL bio-availability and activity are variable. FCS and MCS differ in terms of clinical characteristics and risk of disease, and diagnosis scoring systems have been proposed to accurately distinguish FCS from MCS.

OBJECTIVE

The aim of this study was to assess the strength of the relationship between plasma post-heparin LPL activity and two published chylomicronemia diagnosis scoring systems.

DESIGN AND METHODS

Post-heparin plasma LPL activity was measured using colorimetric assays in a sample of 29 subjects with sustained chylomicronemia (20 FCS and 9 MCS). Chylomicronemia diagnosis scores were obtained for all subjects using the scoring system A (model A), which integrates apolipoprotein B and free glycerol, a surrogate marker of triglyceride hydrolysis, and the scoring system B (model B). Correlation analyses were conducted to estimate the linear relationship between LPL activity and the two diagnosis scoring systems.

RESULTS

There was a significant (p < 0.001) difference in post-heparin LPL activity between FCS and MCS. Both scoring systems significantly correlated with post-heparin LPL activity (model A: r_s = -0.64, p < 0.001; model B: r_s = -0.54, p = 0.002).

CONCLUSIONS

These result suggest that chylomicronemia diagnosis scoring systems correlate with LPL activity and adequately contribute to distinguish FCS from MCS.

Atherosclerotic plaque regression in homozygous familial hypercholesterolaemia: a case report of a long-term lipid-lowering therapy involving LDL-receptor-independent mechanisms

Background

Homozygous familial hypercholesterolaemia (HoFH) is a rare and life-threatening genetic disease characterized by extremely elevated low-density lipoprotein cholesterol (LDL-C) levels, important xanthomatosis and increased risk of premature atherosclerotic cardiovascular disease. Management of HoFH at an early stage is recommended but conventional lipid-lowering therapies (LLTs) dependent on the LDL-receptor for clearance of LDL particles, are usually not sufficient. However, agents acting independently of the LDL-receptor, such as inhibitors of microsomal triglyceride transfer protein (MTP) or angiopoietin-like protein 3 (ANGPTL3), administered in combination, on top of standard-of-care LLT constitute a promising therapy for HoFH.

Case summary

The present case describes a long-term (>10 years) follow-up of a 52-year-old woman with severe HoFH, who was treated with conventional lipid-lowering medications (i.e. statins and ezetimibe) for several years before experiencing the risks and benefits that were encountered with the use of LDL-receptor-independent agents (MTP and ANGPTL3 inhibitors). This combination therapy demonstrated a good long-term safety and efficacy profile, while continuous monitoring of hepatic enzymes (sometimes requiring dose adjustments) and fat accumulation is recommended when using lomitapide.

Discussion

Treating this HoFH patient with an LLT involving the combination of MTP and ANGPTL3 LDL-receptor-independent inhibitors (lomitapide and evinacumab, respectively) showed remarkable improvement in LDL-C levels, disappearance of xanthomatosis and regression in atherosclerotic plaques. In addition to safety and efficacy, one should question the affordability and access hurdle that emerging combination of expensive therapies might constitute in the future for the payers. These challenges could eventually limit the clinical use of those innovative treatments despite their clinical benefit.

Comparison over 25 years of the burden of familial hypercholesterolemia on hospitalizations for coronary heart disease in a French-Canadian founder population

Background

Over the last 25 years, effective treatments, such as potent statins, ezetimibe and PCSK9 inhibitors have gradually emerged to treat heterozygous familial hypercholesterolemia (FH) and guidelines have been progressively developed internationally to promote FH health surveillance, early diagnosis and optimal clinical management. However, the impact of these measures on the burden of FH is not well documented. Although recent genetic and epidemiological studies suggest that the prevalence of familial hypercholesterolaemia (FH) is approximately twice than initialy expected (1:250) (1), it remains significantly higher among French Canadians (FC) (2,3).

Purpose

To compare over 25 years the management and burden of FH among patients hospitalized for an acute coronary heart disease (CHD) event in a FC founder population with a high prevalence of FH.

Methods

Lipid profiles, cardiovascular risk factors, lipid management and FH status of 2,029 FC patients consecutively hospitalized for an acute CHD event between 2017 and 2022 (2022 Cohort) were compared to those of 2,506 patients with angiographically-confirmed CHD who were admitted between 1995 and 1998 (1998 Cohort) (4). FH status was based on molecular, Simon Broome or FH Canada (5) criteria. Statistical comparisons were made using Chi-square and Student's t-tests for independent samples.

Results

Over a 25-year interval, most patients hospitalized for CHD were men (74.5% in 1998 vs 73.4% in 2022). At the time of admission, 23.0% of CHD patients had LDL-Cholesterol levels &gt;5.0 mmol/L in 1998 compared to 1.3% in 2022 (p&lt;0.001). FH was diagnosed in 9.6% of patients in the 1998 cohort compared to 5.5% in 2022 (p&lt;0.001). Overall, the prevalence of obesity, type 2 diabetes and uncontrolled hypertension tended to be higher in 1998, including in FH (p&lt;0.05). The proportion of FH patients hospitalized for CHD who were treated with a statin or a combination of lipid-lowering agents at the moment of admission was 28.4% in 1998 compared to 61.2% in 2022 (p&lt;0.001). FH patients hospitalized for CHD were significantly older in 2022 than in 1998 (59.03±11.17 vs 50.14±11.32 years; p&lt;0.001). Accordingly, the prevalence of premature CHD requiring an hospitalization significantly decreased from 1998 to 2022 in FH (64.3% vs. 44.1%, p&lt;0.001).

Conclusions

Over a 25-year period, FH patients hospitalized for CHD tend to be older and contribute to a lower proportion of hospitalizations. Despite significant improvement in treatment, FH diagnosis and management remain sub-optimal, even in a founder population where FH represents a significant population burden.

Funding Acknowledgement

Type of funding sources: None.

Medical Student Perspectives on Undergraduate Oncology Education in the UK

AIMS

The British Oncology Network for Undergraduate Societies (BONUS) surveyed students who attended an oncology revision day to determine their views on the current quantity, quality and type of curriculum-based oncology teaching they have experienced.

MATERIALS AND METHODS

Students attending two BONUS revision days received a questionnaire assessing their experience of oncology teaching within the medical curriculum and interest in pursuing a future career in oncology using a 10-point Likert scale. Data were collected with informed consent to be anonymised and used for research. Student demographics and qualitative and quantitative data about experiences of oncology education were analysed.

RESULTS

In total, 451 students registered to attend the revision days. After removal of duplicates, non-responders and non-UK participants, responses from 153 students studying across years 1-6 at 22 UK medical schools were analysed. The mean quantity of oncology lectures students reported receiving was 8.9 hours and the mean quantity of clinic/ward-based oncology teaching was 7.5 hours. Ninety (62.1%) of the 145 students who responded to the relevant question reported that they had received dedicated teaching in oncology. Students who had received dedicated oncology teaching reported a statistically significantly higher mean quality 6.1 (95% confidence interval 5.6-6.5) versus 5.0 (95% confidence interval 4.3-5.5; P = 0.003) and quantity 5.2 (95% confidence interval 4.7-5.6) versus 4.3 (95% confidence interval 3.7-4.9; P = 0.03) of oncology teaching compared with those who had not received this.

CONCLUSION

Appropriate oncology education is essential for all medical students due to the high prevalence of cancer. All future doctors need the appropriate knowledge and communication skills to care for cancer patients. Our analysis provides quantitative evidence to support the value of specialist oncology teaching within the medical school curriculum in improving student-reported experience. National student-led revision days and events may widen interest in a future career in oncology and aid collaboration between oncology societies. It is important for the general undergraduate medical curriculum to integrate specialty content. An integrated curriculum should facilitate a holistic approach that spans prevention, screening, treatment and palliation rather than being split by subspeciality.

Lessons learned from the evinacumab trials in the treatment of homozygous familial hypercholesterolemia

Homozygous familial hypercholesterolemia (HoFH) is a life-threatening disease characterized by extremely elevated LDL cholesterol (LDL-C) levels which result in premature atherosclerotic cardiovascular disease. As conventional lipid-lowering therapies, which mainly depend on LDL receptors for LDL particle clearance, remain insufficient for reaching the recommended LDL-C levels in HoFH, agents acting independently of LDL receptors, such as ANGPTL3 inhibitors, constitute a promising target. Evinacumab, a monoclonal antibody directed against ANGPTL3, was approved in the USA in 2021 for treating patients with HoFH. Evinacumab has shown an adequate safety profile with strong LDL-lowering efficacy. This review highlights the development path of evinacumab and provides insight on the lessons learned from trials as well as the hurdles facing accessibility.

Global perspective of familial hypercholesterolaemia: a cross-sectional study from the EAS Familial Hypercholesterolaemia Studies Collaboration (FHSC)

BACKGROUND

The European Atherosclerosis Society Familial Hypercholesterolaemia Studies Collaboration (FHSC) global registry provides a platform for the global surveillance of familial hypercholesterolaemia through harmonisation and pooling of multinational data. In this study, we aimed to characterise the adult population with heterozygous familial hypercholesterolaemia and described how it is detected and managed globally.

METHODS

Using FHSC global registry data, we did a cross-sectional assessment of adults (aged 18 years or older) with a clinical or genetic diagnosis of probable or definite heterozygous familial hypercholesterolaemia at the time they were entered into the registries. Data were assessed overall and by WHO regions, sex, and index versus non-index cases.

FINDINGS

Of the 61 612 individuals in the registry, 42 167 adults (21 999 [53·6%] women) from 56 countries were included in the study. Of these, 31 798 (75·4%) were diagnosed with the Dutch Lipid Clinic Network criteria, and 35 490 (84·2%) were from the WHO region of Europe. Median age of participants at entry in the registry was 46·2 years (IQR 34·3-58·0); median age at diagnosis of familial hypercholesterolaemia was 44·4 years (32·5-56·5), with 40·2% of participants younger than 40 years when diagnosed. Prevalence of cardiovascular risk factors increased progressively with age and varied by WHO region. Prevalence of coronary disease was 17·4% (2·1% for stroke and 5·2% for peripheral artery disease), increasing with concentrations of untreated LDL cholesterol, and was about two times lower in women than in men. Among patients receiving lipid-lowering medications, 16 803 (81·1%) were receiving statins and 3691 (21·2%) were on combination therapy, with greater use of more potent lipid-lowering medication in men than in women. Median LDL cholesterol was 5·43 mmol/L (IQR 4·32-6·72) among patients not taking lipid-lowering medications and 4·23 mmol/L (3·20-5·66) among those taking them. Among patients taking lipid-lowering medications, 2·7% had LDL cholesterol lower than 1·8 mmol/L; the use of combination therapy, particularly with three drugs and with proprotein convertase subtilisin-kexin type 9 inhibitors, was associated with a higher proportion and greater odds of having LDL cholesterol lower than 1·8 mmol/L. Compared with index cases, patients who were non-index cases were younger, with lower LDL cholesterol and lower prevalence of cardiovascular risk factors and cardiovascular diseases (all p<0·001).

INTERPRETATION

Familial hypercholesterolaemia is diagnosed late. Guideline-recommended LDL cholesterol concentrations are infrequently achieved with single-drug therapy. Cardiovascular risk factors and presence of coronary disease were lower among non-index cases, who were diagnosed earlier. Earlier detection and greater use of combination therapies are required to reduce the global burden of familial hypercholesterolaemia.

FUNDING

Pfizer, Amgen, Merck Sharp & Dohme, Sanofi-Aventis, Daiichi Sankyo, and Regeneron.

Discovery of a dual Ras and ARF6 inhibitor from a GPCR endocytosis screen

Internalization and intracellular trafficking of G protein-coupled receptors (GPCRs) play pivotal roles in cell responsiveness. Dysregulation in receptor trafficking can lead to aberrant signaling and cell behavior. Here, using an endosomal BRET-based assay in a high-throughput screen with the prototypical GPCR angiotensin II type 1 receptor (AT1R), we sought to identify receptor trafficking inhibitors from a library of ~115,000 small molecules. We identified a novel dual Ras and ARF6 inhibitor, which we named Rasarfin, that blocks agonist-mediated internalization of AT1R and other GPCRs. Rasarfin also potently inhibits agonist-induced ERK1/2 signaling by GPCRs, and MAPK and Akt signaling by EGFR, as well as prevents cancer cell proliferation. In silico modeling and in vitro studies reveal a unique binding modality of Rasarfin within the SOS-binding domain of Ras. Our findings unveil a class of dual small G protein inhibitors for receptor trafficking and signaling, useful for the inhibition of oncogenic cellular responses.

While Ras is a promising target for cancer therapy, development of inhibitors targeting Ras signaling has proven challenging. Here, the authors report the discovery of Rasarfin, a small molecule from a phenotypic screen on G protein-coupled receptor (GPCR) endocytosis that acts as a dual Ras and ARF6 inhibitor.

Identifying Markers of Cardiovascular Event-Free Survival in Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant trait characterized by elevated low-density lipoprotein-cholesterol (LDL-C) concentrations appearing at birth and is associated with increased risk of premature atherosclerotic cardiovascular disease (CVD). However, in some cases, FH subjects over 70 years of age have surprisingly never experienced any CVD symptoms throughout their entire lives. The objective of this study consists of identifying biological and environmental markers acting as cardioprotective factors and associated with unexpected survival in FH. Upon age and reported cardiovascular events (CVE) stratification, we identified a total of 458 French–Canadian FH subjects with premature reported CVE, and 1297 young adults as well as 24 elderly subjects (≥70 years) who have never reported CVE requiring hospitalization. Logistic regression models were used to depict cardioprotective markers among FH survivors (≥70 years). Regression analyses of the FH cohort showed that female sex (odds ratio (OR) = 12.92 (4.23–39.46); p < 0.0001), high levels of high-density lipoprotein (HDL)-C (OR = 6.76 (2.43–18.79); p = 0.0002) and elevated concentrations of adiponectin (OR = 71.40 (5.20–980.47); p = 0.001) were significant contributory factors in reducing FH-related CVD risk. Notably, female (OR = 11.45 (1.25–105.98); p = 0.031) and high HDL-C (OR = 9.78 (1.75–54.67); p = 0.009) were shown to be significant covariates associated with survival in FH. Non-smoking (OR = 11.73 (4.36–31.56); p < 0.0001) was also identified as an environmental factor associated with CVE-free survival. Based on this configured model of premature CVE occurrence, these results demonstrated that, beyond LDL-C levels, female sex, high HDL-C, elevated adiponectin and non-smoking are important markers that contribute to a reduced risk of CVD and CVE-free survival in FH.

Lomitapide for treatment of homozygous familial hypercholesterolemia: The Québec experience

BACKGROUND AND AIMS

Homozygous familial hypercholesterolemia (HoFH) is an orphan disease, most often caused by bi-allelic mutations of the LDLR gene. Patients with HoFH have elevated LDL-C levels >13 mmol/L, tendinous xanthomata and severe, premature atherosclerotic cardiovascular disease (ASCVD). Untreated, most HoFH patients die of ASCVD in youth. New therapeutic modalities include lomitapide, an inhibitor of microsomal triglyceride transfer protein that lowers hepatic LDL-C production. We have recently identified 79 Canadian patients with HoFH. Here, we describe our experience with lomitapide in the province of Quebec, a geographic area known to have a high prevalence of HoFH.

METHODS

This is a retrospective case series of 12 HoFH patients followed at three lipidology centers in the province of Quebec.

RESULTS

Mean age of the patients was 44 ± 18 years; age at time of HoFH diagnosis ranged from 2 to 59 years. All patients were on a statin and ezetimibe 10 mg/day and five patients were treated with LDL apheresis. Treatment with lomitapide reduced LDL-C levels by 38% (intention-to-treat). Intolerable gastrointestinal side effects were observed in 3/12 patients and were the main reason for treatment discontinuation. Three patients tolerated lomitapide at doses ranging between 5 and 30 mg/day without major side effects. Downwards drug titration was necessary in the 6 remaining patients because of gastrointestinal side effects (n = 5) and elevated liver enzymes (n = 1), and 2 of them finally discontinued treatment.

CONCLUSIONS

Lomitapide may be used to further decrease LDL-C in HoFH patients; gastrointestinal side effects and hepatic toxicity may limit adherence.

Dissection of Clinical and Gene Expression Signatures of Familial versus Multifactorial Chylomicronemia

Familial chylomicronemia syndrome (FCS) is a rare disorder associated with chylomicronemia (CM) and an increased risk of pancreatitis. Most individuals with CM do not have FCS but exhibit multifactorial CM (MCM), which differs from FCS in terms of risk and disease management. This study aimed to investigate clinical and gene expression profiles of FCS and MCM patients. Anthropometrics, clinical, and biochemical variables were analyzed in 57 FCS and 353 MCM patients. Gene expression analyses were performed in a subsample of 19 FCS, 28 MCM, and 15 normolipidemic controls. Receiver operating characteristic (ROC) curve analyses were performed to analyze the capacity of variables to discriminate FCS from MCM. Sustained fasting triglycerides ≥20 mmol/L (>15 mmol/L with eruptive xanthomas), history of pancreatitis, poor response to fibrates, diagnosis of CM at childhood, body mass index <22 kg/m², and delipidated apolipoprotein B or glycerol levels <0.9 g/L and <0.05 mmol/L, respectively, had an area under the ROC curve ≥0.7. Gene expression analyses identified 142 probes differentially expressed in FCS and 32 in MCM compared with controls. Among them, 13 probes are shared between FCS and MCM; 63 are specific to FCS and 2 to MCM. Most FCS-specific or shared biomarkers are involved in inflammatory, immune, circadian, postprandial metabolism, signaling, docking systems, or receptor-mediated clearance mechanisms. This study reveals differential signatures of FCS and MCM. It opens the door to the identification of key mechanisms of CM expression and potential targets for the development of new treatments.

4944The contribution of familial hypercholesterolemia (FH) to premature coronary artery disease decreased by 2-fold between 1998 and 2018 in a founder population with high prevalence of FH

Background

Familial hypercholesterolemia (FH) is an autosomal dominant trait associated with high risk of premature coronary artery disease (CAD). The worldwide prevalence of FH is estimated at 1:250 to 1:500. In certain populations, including French Canadians (FC), the prevalence is significantly higher however. From 1995 to 1998, FH contributed to 9.6% of angiographically proven CAD in a FC founder population, the burden being the highest in men aged <50 years (20.6%). In the past 2 decades, powerful statins, ezetimibe and other low-density lipoprotein-Cholesterol (LDL-C) modulators, such as PCSK9 inhibitors, have been progressively introduced and several FH diagnosis scoring systems or guidelines have been developed and disseminated in order to facilitate FH recognition and management. The impact of these measures on the FH burden is however not documented.

Purpose

To compare the burden of FH twenty years apart in FC patients hospitalized for CAD.

Methods

Lipid profiles, cardiovascular risk factors and FH status of 1,132 FC patients who were hospitalized for a CAD event and who consecutively attended the cardiovascular disease clinic in 2017 and 2018 were compared to those of 2,506 who consecutively presented angiographically proven CAD two decades ago. FH status was based on Simon Broome and FH Canada definitions. In 1998, all consenting CAD patients were also molecularly screened for the most prevalent FH causing mutations in FC. Comparisons between groups were performed using Chi-square and independent samples Student's t-test.

Results

Most patients in both cohorts were males (74.5% vs 73.9% in 1998 vs. 2018, respectively). At admission, mean LDL-C (± SD) was 3.99±1.67 in 1998 vs. 2.22±1.06 in 2018 (p<0.001). The proportion of patients who were treated with a statin or another lipid lowering agent was 32.9% in 1998 compared to 67.6% in 2018 (p<0.001) and the drug regimen was also significantly different. In 1998, 24.6% of patients had LDL-C >5.0 mmol/L at admission compared to 4.2% in 2018. Definite FH was diagnosed in 9.6% of patients in the 1998 cohort compared to 4.7% in the 2018 cohort (p<0.001). FH patients hospitalized for CAD were significantly older in 2018 than in 1998 (56.3±11.3 vs. 49.2±10.9 in men, p=0.001; 61.1±11.8 vs. 53.2±12.3 in women, p=0.02). In the same period, the relative burden of diabetes and other lipid disorders, including high-density lipoprotein dysmetabolism significantly increased (p<0.001).

Conclusions

Over a period of 20 years, in a founder population with a high prevalence of FH, the contribution of FH to hospitalizations for CAD decreased by 2-fold and affected patients now tend to be hospitalized at an older age than 2 decades ago. This suggests that early diagnosis and more effective management of FH in the last 2 decades have contributed to significantly decrease its burden.

Acknowledgement/Funding

ECOGENE-21, Amgen, Sanofi

Pharmacogenomics of statin-related myopathy: Meta-analysis of rare variants from whole-exome sequencing

AIMS

Statin-related myopathy (SRM), which includes rhabdomyolysis, is an uncommon but important adverse drug reaction because the number of people prescribed statins world-wide is large. Previous association studies of common genetic variants have had limited success in identifying a genetic basis for this adverse drug reaction. We conducted a multi-site whole-exome sequencing study to investigate whether rare coding variants confer an increased risk of SRM.

METHODS AND RESULTS

SRM 3-5 cases (N = 505) and statin treatment-tolerant controls (N = 2047) were recruited from multiple sites in North America and Europe. SRM 3-5 was defined as symptoms consistent with muscle injury and an elevated creatine phosphokinase level >4 times upper limit of normal without another likely cause of muscle injury. Whole-exome sequencing and variant calling was coordinated from two analysis centres, and results of single-variant and gene-based burden tests were meta-analysed. No genome-wide significant associations were identified. Given the large number of cases, we had 80% power to identify a variant with minor allele frequency of 0.01 that increases the risk of SRM 6-fold at genome-wide significance.

CONCLUSIONS

In this large whole-exome sequencing study of severe statin-related muscle injury conducted to date, we did not find evidence that rare coding variants are responsible for this adverse drug reaction. Larger sample sizes would be required to identify rare variants with small effects, but it is unclear whether such findings would be clinically actionable.

Monitoring G protein-coupled receptor and β-arrestin trafficking in live cells using enhanced bystander BRET

Endocytosis and intracellular trafficking of receptors are pivotal to maintain physiological functions and drug action; however, robust quantitative approaches are lacking to study such processes in live cells. Here we present new bioluminescence resonance energy transfer (BRET) sensors to quantitatively monitor G protein-coupled receptors (GPCRs) and β-arrestin trafficking. These sensors are based on bystander BRET and use the naturally interacting chromophores luciferase (RLuc) and green fluorescent protein (rGFP) from Renilla. The versatility and robustness of this approach are exemplified by anchoring rGFP at the plasma membrane or in endosomes to generate high dynamic spectrometric BRET signals on ligand-promoted recruitment or sequestration of RLuc-tagged proteins to, or from, specific cell compartments, as well as sensitive subcellular BRET imaging for protein translocation visualization. These sensors are scalable to high-throughput formats and allow quantitative pharmacological studies of GPCR trafficking in real time, in live cells, revealing ligand-dependent biased trafficking of receptor/β-arrestin complexes.

Cellular signaling processes often involve trafficking of receptors and other proteins between subcellular compartments. Here the authors demonstrate a method based on the concept of Enhanced bystander Bioluminescence Resonance Energy Transfer (EbBRET) that allows efficient real time monitoring of endocytosis and trafficking.

Differential regulation of endosomal GPCR/β-arrestin complexes and trafficking by MAPK

β-Arrestins are signaling adaptors that bind to agonist-occupied G protein-coupled receptors (GPCRs) and target them for endocytosis; however, the mechanisms regulating receptor/β-arrestin complexes and trafficking in endosomes, remain ill defined. Here we show, in live cells, differential dynamic regulation of endosomal bradykinin B2 receptor (B2R) complexes with either β-arrestin-1 or -2. We find a novel role for MAPK in the B2R/β-arrestin-2 complex formation, receptor trafficking and signaling mediated by an ERK1/2 regulatory motif in the hinge domain of the rat β-arrestin-2 (PET(178)P), but not rat β-arrestin-1 (PER(177)P). While the ERK1/2 regulatory motif is conserved between rat and mouse β-arrestin-2, it is surprisingly not conserved in human β-arrestin-2 (PEK(178)P). However, mutation of lysine 178 to threonine is sufficient to confer MAPK sensitivity to the human β-arrestin-2. Furthermore, substitution for a phosphomimetic residue in both the rat and the human β-arrestin-2 (T/K178D) significantly stabilizes B2R/β-arrestin complexes in endosomes, delays receptor recycling to the plasma membrane and maintains intracellular MAPK signaling. Similarly, the endosomal trafficking of β2-adrenergic, angiotensin II type 1 and vasopressin V2 receptors was altered by the β-arrestin-2 T178D mutant. Our findings unveil a novel subtype specific mode of MAPK-dependent regulation of β-arrestins in intracellular trafficking and signaling of GPCRs, and suggest differential endosomal receptor/β-arrestin-2 signaling roles among species.

Allosteric and biased g protein-coupled receptor signaling regulation: potentials for new therapeutics

G protein-coupled receptors (GPCRs) are seven-transmembrane proteins that participate in many aspects of the endocrine function and are important targets for drug development. They transduce signals mainly, but not exclusively, via hetero-trimeric G proteins, leading to a diversity of intracellular signaling cascades. Ligands binding at the hormone orthosteric sites of receptors have been classified as agonists, antagonists, and/or inverse agonists based on their ability to mainly modulate G protein signaling. Accumulating evidence also indicates that such ligands, alone or in combination with other ones such as those acting outside the orthosteric hormone binding sites (e.g., allosteric modulators), have the ability to selectively engage subsets of signaling responses as compared to the natural endogenous ligands. Such modes of functioning have been variously referred to as "functional selectivity" or "ligand-biased signaling." In this review, we provide an overview of the current knowledge regarding GPCR-biased signaling and their functional regulation with a focus on the evolving concept that receptor domains can also be targeted to allosterically bias signaling, and discuss the usefulness of such modes of regulation for the design of more efficient therapeutics.

Biasing the prostaglandin F2α receptor responses toward EGFR-dependent transactivation of MAPK

The G protein-coupled prostaglandin F2α (PGF2α) receptor [F prostanoid (FP) receptor] has been implicated in many physiological events including cardiovascular, respiratory, immune, reproductive, and endocrine responses. Binding of PGF2α to FP receptor elicits inositol production and protein kinase C-dependent MAPK activation through Gα(q) coupling. Here we report that AL-8810, previously characterized as an orthosteric antagonist of PGF2α-dependent, Gα(q)-mediated signaling, potently activates ERK1/2 in a protein kinase C-independent manner. Rather, AL-8810 promoted ERK1/2 activation via an epidermal growth factor receptor transactivation mechanism in both human embryonic kidney 293 cells and in the MG-63 osteoblast-like cells, which express endogenous FP receptors. Neither AL-8810- nor PGF2α-mediated stimulation of FP receptor promoted association with β-arrestins, suggesting that MAPK activation induced by these ligands is independent of β-arrestin's signaling scaffold functions. Interestingly, the spatiotemporal activation of ERK1/2 promoted by AL-8810 and PGF2α showed almost completely opposite responses in the nucleus and the cytosol. Finally, using [(3)H]thymidine incorporation, we noted differential regulation of PGF2α- and AL-8810-induced cell proliferation in MG-63 cells. This study reveals, for the first time, the signaling biased nature of FP receptor orthosteric ligands toward MAPK signaling. Our findings on the specific patterns of ERK1/2 activation promoted by FP receptor ligands may help dissect the distinct roles of MAPK in FP receptor-dependent physiological responses.

[Cochlear implants in elderly: performance outcomes in the long term]

OBJECTIVES

To study and compare the evolving capacities of speech discrimination with cochlear implants in older patients compared to patients implanted at a younger age.

METHODOLOGY

A retrospective study comparing a group of 52 patients aged over 65 with a control group of 58 patients aged between 30 and 50 years, followed for 5 years after implantation. We analyzed and compared the evolution of speech discrimination in silence (disyllabic words, sentences) and noise (sentences, S/N ratio: +10 dB) after implantation.

RESULTS

In the group of elderly patients, the speech discrimination in silence remains stable over time (for disyllabic words, score at 6 months: 72.8 +/- 20.2%; score at 5 years: 73.7% +/- 19.7). Discrimination in noise tends to improve (mean score at 6 months: 70.5% +/- 21.5; score at 5 years: 76.9% +/- 16.9). The results obtained are in silence are comparable to the results of the group of patients aged between 30 and 50. In noise, their performance remains lower than the control group (mean differences between scores: -10.8; confidence interval at 95%: -17.9, -5.3).

CONCLUSION

The cochlear implant is effective over the long term in elderly patients, for speech discrimination in quiet and in noise. In silence, their performance is comparable to younger patients with implants.

Non-Hodgkin's lymphomas with Burkitt-like cells are associated with c-Myc amplification and poor prognosis

Out of 344 patients with newly diagnosed non-Hodgkin's lymphoma (NHL), this study identified 16 patients presenting Burkitt-like cells (BLCs) after cytological and/or histological review. Conventional cytogenetic analysis showed at diagnosis complex chromosomal abnormalities in 13 cases and a normal karyotype in three cases. However, neither t(8;14)(q24;q32) nor the variants t(2;8)(p12;q24) or t(8;22)(q24;q11) was detected. FISH studies showed c-MYC amplification in all cases with four to more than seven copies in 10 - 77% metaphase or inter-phase cells. This study did not observe any gene fusion signal for c-MYC/IgH excluding a t(8;14) translocation and partial tri or polysomy of chromosome 8. It also excluded in that cases a break apart for the c-MYC locus. This study also never detected IgL/c-MYC, IgK/c-MYC or X-c-MYC. The BLCs were present whatever the lymphoma sub-type: follicular lymphoma (FL) was diagnosed in six out of 16 patients, mantle cell lymphoma (MCL) in four out of 16 patients, marginal zone lymphoma (MZL) in two out of 16 patients and diffuse large B-cell lymphomas (DLBCL) in three out of 16 patients. One additional patient presented a T-cell lymphoma. The clinical course was aggressive with a poor prognosis, as death occurred in nine patients, within 6 months after diagnosis for eight of them. These data could suggest a sub-group of NHL patients (15 B-NHL, 1 T-NHL) have been identified with a poor prognosis characterized by the association of Burkitt-like cells and c-MYC amplification without t(8;14)(q24;q32) or its variants. The possibility that this profile may represent a distinct morphologic NHL sub-set remains to be determined on a large cohort of patients.

HsS versus a balanced salt solution as a corneal wetting agent during routine cataract extraction and lens implantation

PURPOSE

To evaluate HsS (elastoviscous hylan surgical shield, 0.45%) as an alternative to repeated corneal irrigation with a balanced salt solution during cataract surgery.

SETTING

York Finch General Hospital, Toronto, Ontario (Center A), and Centre Hospitalier de St. Laurent, St. Laurent, Quebec (Center B), Canada.

METHODS

This dual-center, randomized, prospective clinical trial comprised 60 patients (40 at Center A; 20 at Center B) who had routine small incision cataract surgery (Center A, endolenticular phacoemulsification; Center B, Khoury manual phacofragmentation) with in-the-bag implantation of a posterior chamber intraocular lens. The corneal irrigating fluid was randomly assigned to be HsS or a balanced salt solution. The frequency of required applications, duration of efficacy of each application, and assessment of corneal moisture, clarity, transparency, and reflection in the HsS and balanced salt solution groups were recorded and compared.

RESULTS

Mean frequency of applications was 13.9 per procedure in the balanced salt solution group and 1.3 per procedure in the HsS group (P = .0001). Mean duration of effectiveness per application was 23.4 minutes for HsS and 2.0 minutes for balanced salt solution (P = .0001). No significant differences in safety or effect on corneal health were observed between the two solutions.

CONCLUSION

The HsS was significantly more effective than a balanced salt solution in maintaining corneal moisture, clarity, and transparency. The use of HsS may be a safer, more effective option in ophthalmic surgery because it minimizes the obstructed visualization of the surgical field caused by frequent corneal irrigation and loss of surgeon concentration.

Direct effects of halothane on coronary blood flow, myocardial oxygen consumption, and myocardial segmental shortening in in situ canine hearts

Previous in vivo studies of the coronary vascular effects of halothane (HAL) were complicated by varying hemodynamic conditions and global cardiac work demands. Accordingly, the current study evaluated changes in coronary blood flow (CBF) and associated variables during selective intracoronary administrations of HAL in in situ canine hearts using an extracorporeal-controlled pressure perfusion system. Findings during HAL were compared to those during isoflurane (ISO). The left anterior descending coronary artery (LAD) of 8 open-chest dogs anesthetized with fentanyl and midazolam was perfused at constant pressure (109 +/- 2 mm Hg) with HAL-free arterial blood or with blood equilibrated in an extracorporeal oxygenator with HAL (0.5%, 1.0%, 2.0% in 95% O2-5.0% CO2). In the LAD bed, measurements of CBF were obtained with an electromagnetic flowmeter and used to calculate myocardial oxygen consumption (MVO2). Percent segmental shortening (%SS) was measured with ultrasonic crystals. Changes in CBF by HAL were compared to those during maximal vasodilation with adenosine. Separate studies (n = 5) were performed using 1.4% [1 minimum alveolar anesthetic concentration (MAC)] ISO and the findings compared to those during an equianesthetic (1.0%) concentration of HAL. HAL caused concentration-dependent increases in CBF, and decreases in MVO2 and %SS. With 2.0% HAL, the level of CBF was 50% of the maximal adenosine-induced response. At equianesthetic concentrations, HAL caused increases in CBF that were one-third of those caused by ISO, while the decreases in MVO2 and %SS caused by the drugs were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor necrosis factor alpha (TNF alpha) downregulates c-kit proto-oncogene product expression in normal and acute myeloid leukemia CD34+ cells via p55 TNF alpha receptors

Tumor necrosis factor alpha (TNF alpha), as a modulator of hematopoiesis, interacts with many growth factor receptors, such as interleukin-3, granulocyte-macrophage colony-stimulating factor (CSF), and granulocyte-CSF receptors. Here, we studied the interactions between TNF alpha and the stem cell factor (SCF) receptor, c-kit, in normal CD34+ hematopoietic progenitors and their leukemic counterpart, ie, acute myeloid leukemic (AML) CD34+ cells coexpressing c-kit antigen. The results showed that (1) incubation of normal bone marrow mononuclear cells with 200 U/mL rhTNF alpha for 20 hours induced a diminution of 31.2% +/- 5.2% of CD34+ cells coexpressing c-kit; (2) the same decrease was observed using purified CD34+ cells and, furthermore, their proliferative response to SCF was inhibited by 31.5% +/- 7.3% after exposure to TNF alpha; (3) similar experiments performed on CD34+ c-kit+ AML cells from 11 patients gave comparable results. Further analysis at the mRNA level indicated that TNF alpha decreased c-kit mRNA transcripts. Moreover, using monoclonal antibodies against the two types of TNF alpha receptors, p75 and p55, we showed that the downregulation of c-kit proto-oncogene product by TNF alpha, on normal and leukemic CD34+ cells, was exclusively mediated by the TNF alpha p55 receptor. Therefore, we conclude that TNF alpha acts as a downregulator of the SCF receptor expression.

Nitric oxide does not mediate coronary vasodilation by isoflurane

BACKGROUND

Isoflurane causes vasodilation in the coronary circulation. The current study employed a canine model permitting selective intracoronary administrations of isoflurane (1) to test the hypothesis that coronary vasodilation by isoflurane is mediated by nitric oxide and (2) to evaluate the persistence of coronary vasodilation during an extended exposure to isoflurane.

METHODS

Open-chest dogs anesthetized with fentanyl and midazolam were studied. The left anterior descending coronary artery (LAD) was perfused via extracorporeal system with normal arterial blood or with arterial blood equilibrated with 1.4% (1 MAC) isoflurane. In the LAD bed, coronary blood flow (CBF) was measured with an electromagnetic flowmeter and used to calculate myocardial oxygen consumption (MVO2). In series 1, performed at constant coronary perfusion pressure (CPP), the LAD was exposed to 3 h of isoflurane in two groups of eight dogs: control group, normal coronary endothelium; and experimental group, intracoronary infusion of the nitric oxide synthase inhibitor L-NAME (0.15 mg/min for 30 min). Series 2 was performed with CBF constant; thus, CPP varied directly with coronary vascular resistance. In this series, initial steady-state changes in CPP by isoflurane were evaluated in the same four dogs before and after L-NAME.

RESULTS

In the control group of series 1, isoflurane caused a maximal, initial increase in CBF of 444%; however, CBF decreased progressively reaching a value not significantly different from baseline after 3 h of isoflurane. Isoflurane caused a significant (approximately 35%) decrease in MVO2, which persisted during the 3-h administration. Findings after L-NAME (experimental group) were not significantly different from those in control group. In series 2, isoflurane caused significant decreases in CPP that were not affected by L-NAME.

CONCLUSIONS

The lack of effect of L-NAME on isoflurane-induced coronary vasodilation suggests that nitric oxide does not mediate this response. The increase in CBF during prolonged isoflurane waned over time, perhaps because of tachyphylaxis or emergence of a competitive vasoconstrictor mechanism, e.g., metabolic factors secondary to reduced oxygen demands.

Efficacy of recombinant human erythropoietin in the treatment of refractory anemias without excess of blasts in myelodysplastic syndromes

To determine the efficacy of recombinant human erythropoietin at pharmacological doses in myelodysplastic syndromes (MDS) without excess of blasts, 20 patients with refractory anemias (RA) or refractory anemias with ring sideroblasts (RARS) were treated in an open study with escalating doses from 40 U/kg to 300 U/kg three times a week subcutaneously during a period of 3 months. Maintenance therapy at the lowest effective dose was continued in responders. A dose response of CFU-E and BFU-E to Epo was analysed at the entry. Bone marrow examination with an in vitro study of hematopoietic progenitors was performed before and after the first three months. Seven of 20 patients responded: a total recovery was observed in 3 patients; one became transfusion independent and a reduction of 50% of the transfusion requirement was achieved in 3 others. 3 patients are still receiving treatment for 2, 3 and 4 years. No significant correlation was found between the in vitro and clinical response. A non parametric analysis of responders and non responders emphasised the importance of a long delay between the diagnosis and the treatment, (p = 0.024) and an endogenous Epo level less than 100 mU/ml (p = 0.025) in order to predict the efficacy of rhEpo. This study offers evidence that patients with refractory anemias without excess of blasts in the bone marrow respond to rhEpo at pharmacological doses. Larger studies are required in order to define the patients who may respond and to elucidate the mechanism of the positive effect of rhEpo.

Reversible inhibitory effects and absence of toxicity of the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) in human long-term bone marrow culture

The effects of acetyl-N-Ser-Asp-Lys-Pro (Ac-SDKP) in human long-term bone marrow cultures (LTBMCs) were assessed by measuring the number of progenitors and the development of stromal cells over a 6-week course. In a first set of experiments, AcSDKP was added weekly at each medium change. Under these conditions, no significant effect of the peptide was observed. In contrast, by adding AcSDKP daily at 10(-10) M, the growth of the progenitors of the non-adherent (NA) compartment was inhibited by about 35%. This inhibition was entirely reversible; after stopping the addition of the peptide at the fourth week, the number of progenitors returned to control level within 2 weeks. Conversely, AcSDKP did not significantly change the number of the progenitors present in the adherent layer. In addition, AcSDKP did not affect the formation of the stromal layer nor induce the secretion of cytokines, such as tumor necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), granulocyte colony-stimulating factor (G-CSF), interleukin 3 (IL-3), or interleukin 6 (IL-6). Our results indicate that AcSDKP has inhibitory but reversible effects on NA progenitors and does not induce long-term modifications of the microenvironment, both of particular interest for its clinical application.

Tumor necrosis factor alpha in human long-term bone marrow cultures: distinct effects on nonadherent and adherent progenitors

Although tumor necrosis factor alpha (TNF alpha) exerts a variety of activities on hematopoietic cells, suggesting it may have some potential therapeutic applications, its long-term effects on hematopoiesis are not well defined. Therefore, we took the advantage of long-term bone marrow cultures (LTBMCs) to evaluate the long-term role of TNF alpha on both the microenvironment and the hematopoietic progenitors. LTBMCs were inoculated with 100 U/ml of recombinant human TNF alpha (rhTNF alpha) either at the onset of the cultures (d0) or at day 21 (d21) when the adherent layer (AL) was already established. Then TNF alpha was added at each weekly medium change. The cellularity and the content of progenitors in both the nonadherent layer (NAL) and AL, the formation of the AL, and the presence of various cytokines in the supernatants were examined weekly. The data showed 1) a strong and durable inhibitory effect on total nonadherent cells; 2) a rapid and transient inhibition of NA progenitors, whereas adherent progenitors were lately affected; and 3) microenvironmental changes consisting of the disappearance of adipocytes and the secretion of high levels of interleukin 6. The results suggest that the inhibitory effects of TNF alpha on the NAL are in part counterbalanced by stromal modifications that in turn lead to a faster exhaustion of hematopoiesis.

Effects of butyric acid on cell cycle regulation and induction of histone H1(0) in mouse cells and tissue culture. Inducibility of H1 (0)in the late S-G2 phase of the cell cycle

We have examined the regulation of the synthesis of histone H1(0) in cultured mammalian cells treated with butyric acid. Treatment of cells with the inducer results in the arrest of synthesis of DNA and the other histones, while increasing the synthesis of H1(0) by a factor of 11. The induction of H1(0) by butyric acid occurs in a pulse with a peak at six hours, followed by a decrease to negligible levels. This pulse-like induction appears to be due to the fact that the cells are inducible for H1(0) only in the late S or G2 phases of the cell cycle. This, coupled with the fact that butyric acid blocks cells in G1, results in the burst of H1(0) synthesis after addition of the inducer. The G1 block provoked by butyric acid does not appear to result from the accumulation of H1(0). Removal of butyric acid from G1-blocked cells resulted in the resumption of cellular proliferation without prior loss of H1(0), demonstrating that the presence of this histone is not sufficient to prevent cellular proliferation.

Immunopathologic and morphologic studies of skeletal muscle in Chagas' disease

Skeletal muscle biopsies from 21 individuals infected with Trypanosoma cruzi were studied my means of immunofluorescence, ultrastructural immunochemical, light and electron microscopic, and histochemical procedures. In 12 cases, definite morphologic alterations were found. These alterations were coincident with the presence of circulating antibodies against the plasma membrane of striated muscle fibers and endothelial cells (EVI antibodies). In almost all cases the lesions also presented autologous immunoglobulins bound to the plasma membrane of muscle fibers and endothelial cells. Interstitial inflammatory exudate was not observed in the diseased muscle. On the basis of these observations, it is suggested that the EVI antibody is related to some of the pathogenetic mechanism of skeletal muscle damage in Chagas' disease.