The effects of undernutrition and dexamethasone treatment on cultured rat neonatal cardiomyocytes

It is well-established that undernutrition during pregnancy increases offspring’s risk of disease in later life. Studies have found that maternal protein restriction during rodent gestation programmes premature hypertrophic growth and decreased mitotic index of cardiomyocytes, as well as impaired contractile ability of the heart. All of these are predisposing factors to cardiovascular disease. To date, few studies have focused on the underlying mechanisms that lead to such alterations in the structure and function of the cardiovascular system. This study aimed to investigate if protein deficiency during gestation impacts upon cardiomyocyte proliferation, and glucose uptake and transport in vitro, and if programming effects can be demonstrated in culture. Methods. Trial 1: Ten pregnant wistar rats were fed either a control or low protein (MLP) diet throughout gestation. Pups were culled on the day of birth and hearts were taken to isolate cardiomyocytes. After 10 days in culture (baseline) some cardiomyocytes were treated with 100nM and 10μM of dexamethasone (Dex) for 48 hours (Day 2). Both untreated and Dex treated cultures were analysed for proliferation and differentiation rates, and glucose uptake. Trial 2: Gestational diet and culturing of cardiomyocyte cells was the same as in trial one. Cultures were treated with 10nM and 100nM Dex and analysed at the same time points for proliferation and differentiation rates, cell apoptosis and mRNA expression of glucose transporters. Results. In trial one, MLP diet increased day 2 binucleation. High concentrations of Dex increased insulin stimulated glucose uptake in MLP neonatal cardiomyocytes indicating they had an increased sensitivity to glucocorticoids. In trial two, Dex treatment decreased expression of GLUT 4 and increased expression of glucocorticoid receptor (GR) mRNA. Conclusion. Results indicate possible remodelling of the heart in rat offspring exposed to MLP diet in utero, but it remains unclear as to what mechanism underpins MLP cultures increased sensitivity to glucocorticoids. There were some similarities to the findings of in vivo studies, but responses varied between trials. This indicates that cell culture is unlikely to become a viable alternative model, but it is a useful tool for exploring focused mechanisms of fetal programming

The effects of undernutrition and dexamethasone treatment on cultured rat neonatal cardiomyocytes

It is well-established that undernutrition during pregnancy increases offspring’s risk of disease in later life. Studies have found that maternal protein restriction during rodent gestation programmes premature hypertrophic growth and decreased mitotic index of cardiomyocytes, as well as impaired contractile ability of the heart. All of these are predisposing factors to cardiovascular disease. To date, few studies have focused on the underlying mechanisms that lead to such alterations in the structure and function of the cardiovascular system. This study aimed to investigate if protein deficiency during gestation impacts upon cardiomyocyte proliferation, and glucose uptake and transport in vitro, and if programming effects can be demonstrated in culture. Methods. Trial 1: Ten pregnant wistar rats were fed either a control or low protein (MLP) diet throughout gestation. Pups were culled on the day of birth and hearts were taken to isolate cardiomyocytes. After 10 days in culture (baseline) some cardiomyocytes were treated with 100nM and 10μM of dexamethasone (Dex) for 48 hours (Day 2). Both untreated and Dex treated cultures were analysed for proliferation and differentiation rates, and glucose uptake. Trial 2: Gestational diet and culturing of cardiomyocyte cells was the same as in trial one. Cultures were treated with 10nM and 100nM Dex and analysed at the same time points for proliferation and differentiation rates, cell apoptosis and mRNA expression of glucose transporters. Results. In trial one, MLP diet increased day 2 binucleation. High concentrations of Dex increased insulin stimulated glucose uptake in MLP neonatal cardiomyocytes indicating they had an increased sensitivity to glucocorticoids. In trial two, Dex treatment decreased expression of GLUT 4 and increased expression of glucocorticoid receptor (GR) mRNA. Conclusion. Results indicate possible remodelling of the heart in rat offspring exposed to MLP diet in utero, but it remains unclear as to what mechanism underpins MLP cultures increased sensitivity to glucocorticoids. There were some similarities to the findings of in vivo studies, but responses varied between trials. This indicates that cell culture is unlikely to become a viable alternative model, but it is a useful tool for exploring focused mechanisms of fetal programming

Maternal high-fat feeding in pregnancy programmes atherosclerotic lesion size in the ApoE*3 Leiden mouse

Periods of rapid growth seen during the early stages of fetal development, including cell proliferation and differentiation, are greatly influenced by the maternal environment. We demonstrate here that over-nutrition, specifically exposure to a high fat diet in utero, programmed the extent of atherosclerosis in the offspring of ApoE*3 Leiden transgenic mice. Pregnant ApoE*3 Leiden mice were fed either a control chow diet (2.8% fat, n=12) or a high-fat, moderate-cholesterol diet (MHF, 19.4% fat, n=12). Dams were fed the chow diet during the suckling period. At 28d postnatal age wild type and ApoE*3 Leiden offspring from chow or MHF-fed mothers were fed either a control chow diet (n=37) or a diet rich in cocoa butter (15%) and cholesterol (0.25%), for 14 weeks to induce atherosclerosis (n=36). Offspring from MHF-fed mothers had 1.9-fold larger atherosclerotic lesions (p<0.001). There was no direct effect of prenatal diet on plasma triglycerides or cholesterol, however transgenic ApoE*3 Leiden offspring displayed raised cholesterol when on an atherogenic diet compared to wild-type controls (p=0.031). Lesion size was correlated with plasma lipid parameters after adjustment for genotype, maternal diet and postnatal diet (R2=0.563, p<0.001). ApoE*3 Leiden mothers fed a MHF diet developed hypercholesterolemia (plasma cholesterol 2-fold higher than in chow fed mothers, p=0.011). The data strongly suggest that maternal hypercholesterolaemia programmes later susceptibility to atherosclerosis. This is consistent with previous observations in humans and animal models

Maternal high-fat feeding in pregnancy programmes atherosclerotic lesion size in the ApoE*3 Leiden mouse

Periods of rapid growth seen during the early stages of fetal development, including cell proliferation and differentiation, are greatly influenced by the maternal environment. We demonstrate here that over-nutrition, specifically exposure to a high fat diet in utero, programmed the extent of atherosclerosis in the offspring of ApoE*3 Leiden transgenic mice. Pregnant ApoE*3 Leiden mice were fed either a control chow diet (2.8% fat, n=12) or a high-fat, moderate-cholesterol diet (MHF, 19.4% fat, n=12). Dams were fed the chow diet during the suckling period. At 28d postnatal age wild type and ApoE*3 Leiden offspring from chow or MHF-fed mothers were fed either a control chow diet (n=37) or a diet rich in cocoa butter (15%) and cholesterol (0.25%), for 14 weeks to induce atherosclerosis (n=36). Offspring from MHF-fed mothers had 1.9-fold larger atherosclerotic lesions (p<0.001). There was no direct effect of prenatal diet on plasma triglycerides or cholesterol, however transgenic ApoE*3 Leiden offspring displayed raised cholesterol when on an atherogenic diet compared to wild-type controls (p=0.031). Lesion size was correlated with plasma lipid parameters after adjustment for genotype, maternal diet and postnatal diet (R2=0.563, p<0.001). ApoE*3 Leiden mothers fed a MHF diet developed hypercholesterolemia (plasma cholesterol 2-fold higher than in chow fed mothers, p=0.011). The data strongly suggest that maternal hypercholesterolaemia programmes later susceptibility to atherosclerosis. This is consistent with previous observations in humans and animal models

Maternal high-fat feeding in pregnancy programmes atherosclerotic lesion size in the ApoE*3 Leiden mouse

Periods of rapid growth seen during the early stages of fetal development, including cell proliferation and differentiation, are greatly influenced by the maternal environment. We demonstrate here that over-nutrition, specifically exposure to a high fat diet in utero, programmed the extent of atherosclerosis in the offspring of ApoE*3 Leiden transgenic mice. Pregnant ApoE*3 Leiden mice were fed either a control chow diet (2.8% fat, n=12) or a high-fat, moderate-cholesterol diet (MHF, 19.4% fat, n=12). Dams were fed the chow diet during the suckling period. At 28d postnatal age wild type and ApoE*3 Leiden offspring from chow or MHF-fed mothers were fed either a control chow diet (n=37) or a diet rich in cocoa butter (15%) and cholesterol (0.25%), for 14 weeks to induce atherosclerosis (n=36). Offspring from MHF-fed mothers had 1.9-fold larger atherosclerotic lesions (

Comprehensive Cancer-Predisposition Gene Testing in an Adult Multiple Primary Tumor Series Shows a Broad Range of Deleterious Variants and Atypical Tumor Phenotypes.

Multiple primary tumors (MPTs) affect a substantial proportion of cancer survivors and can result from various causes, including inherited predisposition. Currently, germline genetic testing of MPT-affected individuals for variants in cancer-predisposition genes (CPGs) is mostly targeted by tumor type. We ascertained pre-assessed MPT individuals (with at least two primary tumors by age 60 years or at least three by 70 years) from genetics centers and performed whole-genome sequencing (WGS) on 460 individuals from 440 families. Despite previous negative genetic assessment and molecular investigations, pathogenic variants in moderate- and high-risk CPGs were detected in 67/440 (15.2%) probands. WGS detected variants that would not be (or were not) detected by targeted resequencing strategies, including low-frequency structural variants (6/440 [1.4%] probands). In most individuals with a germline variant assessed as pathogenic or likely pathogenic (P/LP), at least one of their tumor types was characteristic of variants in the relevant CPG. However, in 29 probands (42.2% of those with a P/LP variant), the tumor phenotype appeared discordant. The frequency of individuals with truncating or splice-site CPG variants and at least one discordant tumor type was significantly higher than in a control population (χ2 = 43.642; p ≤ 0.0001). 2/67 (3%) probands with P/LP variants had evidence of multiple inherited neoplasia allele syndrome (MINAS) with deleterious variants in two CPGs. Together with variant detection rates from a previous series of similarly ascertained MPT-affected individuals, the present results suggest that first-line comprehensive CPG analysis in an MPT cohort referred to clinical genetics services would detect a deleterious variant in about a third of individuals.JW is supported by a Cancer Research UK Cambridge Cancer Centre Clinical Research Training Fellowship. Funding for the NIHR BioResource – Rare diseases project was provided by the National Institute for Health Research (NIHR, grant number RG65966). ERM acknowledges support from the European Research Council (Advanced Researcher Award), NIHR (Senior Investigator Award and Cambridge NIHR Biomedical Research Centre), Cancer Research UK Cambridge Cancer Centre and Medical Research Council Infrastructure Award. The University of Cambridge has received salary support in respect of EM from the NHS in the East of England through the Clinical Academic Reserve. The views expressed are those of the authors and not necessarily those of the NHS or Department of Health. DGE is an NIHR Senior Investigator and is supported by the all Manchester NIHR Biomedical Research Centre

Comprehensive Rare Variant Analysis via Whole-Genome Sequencing to Determine the Molecular Pathology of Inherited Retinal Disease

Inherited retinal disease is a common cause of visual impairment and represents a highly heterogeneous group of conditions. Here, we present findings from a cohort of 722 individuals with inherited retinal disease, who have had whole-genome sequencing (n = 605), whole-exome sequencing (n = 72), or both (n = 45) performed, as part of the NIHR-BioResource Rare Diseases research study. We identified pathogenic variants (single-nucleotide variants, indels, or structural variants) for 404/722 (56%) individuals. Whole-genome sequencing gives unprecedented power to detect three categories of pathogenic variants in particular: structural variants, variants in GC-rich regions, which have significantly improved coverage compared to whole-exome sequencing, and variants in non-coding regulatory regions. In addition to previously reported pathogenic regulatory variants, we have identified a previously unreported pathogenic intronic variant in $\textit{CHM}$ in two males with choroideremia. We have also identified 19 genes not previously known to be associated with inherited retinal disease, which harbor biallelic predicted protein-truncating variants in unsolved cases. Whole-genome sequencing is an increasingly important comprehensive method with which to investigate the genetic causes of inherited retinal disease.This work was supported by The National Institute for Health Research England (NIHR) for the NIHR BioResource – Rare Diseases project (grant number RG65966). The Moorfields Eye Hospital cohort of patients and clinical and imaging data were ascertained and collected with the support of grants from the National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital, National Health Service Foundation Trust, and UCL Institute of Ophthalmology, Moorfields Eye Hospital Special Trustees, Moorfields Eye Charity, the Foundation Fighting Blindness (USA), and Retinitis Pigmentosa Fighting Blindness. M.M. is a recipient of an FFB Career Development Award. E.M. is supported by UCLH/UCL NIHR Biomedical Research Centre. F.L.R. and D.G. are supported by Cambridge NIHR Biomedical Research Centre

Phenotypic Characterization of EIF2AK4 Mutation Carriers in a Large Cohort of Patients Diagnosed Clinically With Pulmonary Arterial Hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare disease with an emerging genetic basis. Heterozygous mutations in the gene encoding the bone morphogenetic protein receptor type 2 (BMPR2) are the commonest genetic cause of PAH, whereas biallelic mutations in the eukaryotic translation initiation factor 2 alpha kinase 4 gene (EIF2AK4) are described in pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Here, we determine the frequency of these mutations and define the genotype-phenotype characteristics in a large cohort of patients diagnosed clinically with PAH. METHODS: Whole-genome sequencing was performed on DNA from patients with idiopathic and heritable PAH and with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis recruited to the National Institute of Health Research BioResource-Rare Diseases study. Heterozygous variants in BMPR2 and biallelic EIF2AK4 variants with a minor allele frequency of <1:10 000 in control data sets and predicted to be deleterious (by combined annotation-dependent depletion, PolyPhen-2, and sorting intolerant from tolerant predictions) were identified as potentially causal. Phenotype data from the time of diagnosis were also captured. RESULTS: Eight hundred sixty-four patients with idiopathic or heritable PAH and 16 with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis were recruited. Mutations in BMPR2 were identified in 130 patients (14.8%). Biallelic mutations in EIF2AK4 were identified in 5 patients with a clinical diagnosis of pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Furthermore, 9 patients with a clinical diagnosis of PAH carried biallelic EIF2AK4 mutations. These patients had a reduced transfer coefficient for carbon monoxide (Kco; 33% [interquartile range, 30%-35%] predicted) and younger age at diagnosis (29 years; interquartile range, 23-38 years) and more interlobular septal thickening and mediastinal lymphadenopathy on computed tomography of the chest compared with patients with PAH without EIF2AK4 mutations. However, radiological assessment alone could not accurately identify biallelic EIF2AK4 mutation carriers. Patients with PAH with biallelic EIF2AK4 mutations had a shorter survival. CONCLUSIONS: Biallelic EIF2AK4 mutations are found in patients classified clinically as having idiopathic and heritable PAH. These patients cannot be identified reliably by computed tomography, but a low Kco and a young age at diagnosis suggests the underlying molecular diagnosis. Genetic testing can identify these misclassified patients, allowing appropriate management and early referral for lung transplantation

Phenotypic Characterization of <i>EIF2AK4</i> Mutation Carriers in a Large Cohort of Patients Diagnosed Clinically With Pulmonary Arterial Hypertension

Background: Pulmonary arterial hypertension (PAH) is a rare disease with an emerging genetic basis. Heterozygous mutations in the gene encoding the bone morphogenetic protein receptor type 2 ( BMPR2 ) are the commonest genetic cause of PAH, whereas biallelic mutations in the eukaryotic translation initiation factor 2 alpha kinase 4 gene ( EIF2AK4 ) are described in pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Here, we determine the frequency of these mutations and define the genotype-phenotype characteristics in a large cohort of patients diagnosed clinically with PAH. Methods: Whole-genome sequencing was performed on DNA from patients with idiopathic and heritable PAH and with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis recruited to the National Institute of Health Research BioResource–Rare Diseases study. Heterozygous variants in BMPR2 and biallelic EIF2AK4 variants with a minor allele frequency of &lt;1:10 000 in control data sets and predicted to be deleterious (by combined annotation-dependent depletion, PolyPhen-2, and sorting intolerant from tolerant predictions) were identified as potentially causal. Phenotype data from the time of diagnosis were also captured. Results: Eight hundred sixty-four patients with idiopathic or heritable PAH and 16 with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis were recruited. Mutations in BMPR2 were identified in 130 patients (14.8%). Biallelic mutations in EIF2AK4 were identified in 5 patients with a clinical diagnosis of pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Furthermore, 9 patients with a clinical diagnosis of PAH carried biallelic EIF2AK4 mutations. These patients had a reduced transfer coefficient for carbon monoxide (K co ; 33% [interquartile range, 30%–35%] predicted) and younger age at diagnosis (29 years; interquartile range, 23–38 years) and more interlobular septal thickening and mediastinal lymphadenopathy on computed tomography of the chest compared with patients with PAH without EIF2AK4 mutations. However, radiological assessment alone could not accurately identify biallelic EIF2AK4 mutation carriers. Patients with PAH with biallelic EIF2AK4 mutations had a shorter survival. Conclusions: Biallelic EIF2AK4 mutations are found in patients classified clinically as having idiopathic and heritable PAH. These patients cannot be identified reliably by computed tomography, but a low K co and a young age at diagnosis suggests the underlying molecular diagnosis. Genetic testing can identify these misclassified patients, allowing appropriate management and early referral for lung transplantation. </jats:sec