Publications by authors named "An Van Den Bergh"

19 Publications

  • Page 1 of 1

Pharmacokinetic Drug-Drug Interaction of Apalutamide, Part 2: Investigating Interaction Potential Using a Physiologically Based Pharmacokinetic Model.

Clin Pharmacokinet 2020 09;59(9):1149-1160

Janssen Research & Development, Spring House, PA, USA.

Background: Apalutamide is predominantly metabolized via cytochrome P450 (CYP) 2C8 and CYP3A4, whose contributions change due to autoinduction with repeated dosing.

Objectives: We aimed to predict CYP3A4 and CYP2C8 inhibitor/inducer effects on the steady-state pharmacokinetics of apalutamide and total potency-adjusted pharmacologically active moieties, and simulated drug-drug interaction (DDI) between single-dose and repeated-dose apalutamide coadministered with known inhibitors/inducers.

Methods: We applied physiologically based pharmacokinetic modeling for our predictions, and simulated DDI between single-dose and repeated-dose apalutamide 240 mg coadministered with ketoconazole, gemfibrozil, or rifampicin.

Results: The estimated contribution of CYP2C8 and CYP3A4 to apalutamide metabolism is 58% and 13%, respectively, after single dosing, and 40% and 37%, respectively, at steady-state. Apalutamide exposure is predicted to increase with ketoconazole (maximum observed concentration at steady-state [C] 38%, area under the plasma concentration-time curve at steady-state [AUC] 51% [pharmacologically active moieties, C 23%, AUC 28%]) and gemfibrozil (C 32%, AUC 44% [pharmacologically active moieties, C 19%, AUC 23%]). Rifampicin exposure is predicted to decrease apalutamide (C 25%, AUC 34% [pharmacologically active moieties, C 15%, AUC 19%]).

Conclusions: Based on our simulations, no major changes in the pharmacokinetics of apalutamide or pharmacologically active moieties are expected with strong CYP3A4/CYP2C8 inhibitors/inducers. This observation supports the existing recommendations that no dose adjustments are needed during coadministration of apalutamide and the known inhibitors or inducers of CYP2C8 or CYP3A4.
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http://dx.doi.org/10.1007/s40262-020-00881-3DOI Listing
September 2020

Trifluoromethyl Dihydrothiazine-Based β-Secretase (BACE1) Inhibitors with Robust Central β-Amyloid Reduction and Minimal Covalent Binding Burden.

ChemMedChem 2019 11 12;14(22):1894-1910. Epub 2019 Nov 12.

Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Pharmaceutical Research Center, 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan.

The β-site amyloid precursor protein cleaving enzyme 1 (BACE1, also known as β-secretase) is a promising target for the treatment of Alzheimer's disease. A pK lowering approach over the initial leads was adopted to mitigate hERG inhibition and P-gp efflux, leading to the design of 6-CF dihydrothiazine 8 (N-(3-((4S,6S)-2-amino-4-methyl-6-(trifluoromethyl)-5,6-dihydro-4H-1,3-thiazin-4-yl)-4-fluorophenyl)-5-cyanopicolinamide). Optimization of 8 led to the discovery of 15 (N-(3-((4S,6S)-2-amino-4-methyl-6-(trifluoromethyl)-5,6-dihydro-4H-1,3-thiazin-4-yl)-4-fluorophenyl)-5-(fluoromethoxy)pyrazine-2-carboxamide) with an excellent balance of potency, hERG inhibition, P-gp efflux, and metabolic stability. Oral administration of 8 elicited robust Aβ reduction in dog even at 0.16 mg/kg. Reflecting the reduced hERG inhibitory activity, no QTc prolongation was observed at high doses. The potential for reactive metabolite formation of 15 was realized in a nucleophile trapping assay using [ C]-KCN in human liver microsomes. Utilizing covalent binding (CVB) in human hepatocytes and the maximum projected human dosage, the daily CVB burden of 15 was calculated to be at an acceptable value of below 1 mg/day. However, hepatotoxicity was observed when 15 was subjected to a two-week tolerance study in dog, which prevented further evaluation of this compound.
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http://dx.doi.org/10.1002/cmdc.201900478DOI Listing
November 2019

Discovery of an Extremely Potent Thiazine-Based β-Secretase Inhibitor with Reduced Cardiovascular and Liver Toxicity at a Low Projected Human Dose.

J Med Chem 2019 10 8;62(20):9331-9337. Epub 2019 Oct 8.

Genetic evidence points to deposition of amyloid-β (Aβ) as a causal factor for Alzheimer's disease. Aβ generation is initiated when β-secretase (BACE1) cleaves the amyloid precursor protein. Starting with an oxazine lead , we describe the discovery of a thiazine-based BACE1 inhibitor with robust Aβ reduction in vivo at low concentrations, leading to a low projected human dose of 14 mg/day where achieved sustained Aβ reduction of 80% at trough level.
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http://dx.doi.org/10.1021/acs.jmedchem.9b01140DOI Listing
October 2019

PBPK Absorption Modeling: Establishing the In Vitro-In Vivo Link-Industry Perspective.

AAPS J 2019 01 23;21(2):19. Epub 2019 Jan 23.

Biopharmaceutics and Specialty Dosage Forms, Pharmaceutical Sciences, Merck & Co., Inc., 770 Sumneytown Pike, WP75B-210, West Point, Pennsylvania, 19486-0004, USA.

The establishment of an in vitro-in vivo correlation (IVIVC) is considered the gold standard to establish in vivo relevance of a dissolution method and to utilize dissolution data in the context of regulatory bioequivalence questions, including the development of dissolution specifications. However, several recent publications, including industry surveys and reviews from regulatory agencies, have indicated a low success rate for IVIVCs, especially for immediate-release formulations. In recent years, the use of physiologically based pharmacokinetics (PBPK) and absorption modeling, as a tool to facilitate formulation development, has been attracting increased attention. This manuscript provides an industry perspective on the current challenges with establishing IVIVCs and the potential PBPK and absorption modeling offer to increase their impact. Case studies across both immediate-release and extended-release formulations from five pharmaceutical companies are utilized to demonstrate how physiologically based IVIVC (PB-IVIVC) may facilitate drug product understanding and to inform bioequivalence assessment and clinically relevant specifications. Finally, PB-IVIVC best practices and a strategy for model development and application are proposed.
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http://dx.doi.org/10.1208/s12248-019-0292-3DOI Listing
January 2019

Preclinical Bioavailability Strategy for Decisions on Clinical Drug Formulation Development: An In Depth Analysis.

Mol Pharm 2018 07 11;15(7):2633-2645. Epub 2018 Jun 11.

The aim of the presented retrospective analysis was to verify whether a previously proposed Janssen Biopharmaceutical Classification System (BCS)-like decision tree, based on preclinical bioavailability data of a solution and suspension formulation, would facilitate informed decision making on the clinical formulation development strategy. In addition, the predictive value of (in vitro) selection criteria, such as solubility, human permeability, and/or a clinical dose number (Do), were evaluated, potentially reducing additional supporting formulation bioavailability studies in animals. The absolute ( F) and relative ( F) bioavailability of an oral solution and suspension, respectively, in rat or dog and the anticipated BCS classification were analyzed for 89 Janssen compounds with 28 of these having F and F in both rat and dog at doses around 10 and 5 mg/kg, respectively. The bioavailability outcomes in the dog aligned well with a BCS-like classification based upon the solubility of the active pharmaceutical ingredient (API) in biorelevant media, while the alignment was less clear for the bioavailability data in the rat. A retrospective analysis on the clinically tested formulations for a set of 12 Janssen compounds confirmed that the previously proposed animal bioavailability-based decision tree facilitated decisions on the oral formulation type, with the dog as the most discriminative species. Furthermore, the analysis showed that based on a Do for a standard human dose of 100 mg in aqueous and/or biorelevant media, a similar formulation type would have been selected compared to the one suggested by the animal data. However, the concept of a Do did not distinguish between solubility enhancing or enabling formulations and does not consider the API permeability, and hence, it produces the risk of slow and potentially incomplete oral absorption of an API with poor intestinal permeability. In cases where clinical dose estimations are available early in development, the preclinical bioavailability studies and dose number calculations, used to guide formulation selection, may be performed at more relevant doses instead of the proposed standard human dose. It should be noted, however, that unlike in late development, there is uncertainty on the clinical dose estimated in the early clinical phases because that dose is usually only based on in vitro and/or in vivo animal pharmacology models, or early clinical biomarker information. Therefore, formulation strategies may be adjusted based on emerging data supporting clinical doses. In summary, combined early information on in vitro-assessed API solubility and permeability, preclinical suspension/solution bioavailability data in relation to the intravenous clearance, and metabolic pathways of the API can strengthen formulation decisions. However, these data may not always fully distinguish between conventional (e.g., to be taken with food), enhancing, and enabling formulations. Therefore, to avoid overinvestment in complex and expensive enabling technologies, it is useful to evaluate a conventional and solubility (and/or permeability) enhancing formulation under fasted and fed conditions, as part of a first-in-human study or in a subsequent early human bioavailability study, for compounds with high Do, a low animal F, or low F caused by precipitation of the solubilized API.
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http://dx.doi.org/10.1021/acs.molpharmaceut.8b00172DOI Listing
July 2018

IMI - oral biopharmaceutics tools project - evaluation of bottom-up PBPK prediction success part 1: Characterisation of the OrBiTo database of compounds.

Eur J Pharm Sci 2017 Jan 23;96:598-609. Epub 2016 Sep 23.

AstraZeneca, Sweden.

Predicting oral bioavailability (F) is of importance for estimating systemic exposure of orally administered drugs. Physiologically-based pharmacokinetic (PBPK) modelling and simulation have been applied extensively in biopharmaceutics recently. The Oral Biopharmaceutical Tools (OrBiTo) project (Innovative Medicines Initiative) aims to develop and improve upon biopharmaceutical tools, including PBPK absorption models. A large-scale evaluation of PBPK models may be considered the first step. Here we characterise the OrBiTo active pharmaceutical ingredient (API) database for use in a large-scale simulation study. The OrBiTo database comprised 83 APIs and 1475 study arms. The database displayed a median logP of 3.60 (2.40-4.58), human blood-to-plasma ratio of 0.62 (0.57-0.71), and fraction unbound in plasma of 0.05 (0.01-0.17). The database mainly consisted of basic compounds (48.19%) and Biopharmaceutics Classification System class II compounds (55.81%). Median human intravenous clearance was 16.9L/h (interquartile range: 11.6-43.6L/h; n=23), volume of distribution was 80.8L (54.5-239L; n=23). The majority of oral formulations were immediate release (IR: 87.6%). Human F displayed a median of 0.415 (0.203-0.724; n=22) for IR formulations. The OrBiTo database was found to be largely representative of previously published datasets. 43 of the APIs were found to satisfy the minimum inclusion criteria for the simulation exercise, and many of these have significant gaps of other key parameters, which could potentially impact the interpretability of the simulation outcome. However, the OrBiTo simulation exercise represents a unique opportunity to perform a large-scale evaluation of the PBPK approach to predicting oral biopharmaceutics.
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http://dx.doi.org/10.1016/j.ejps.2016.09.027DOI Listing
January 2017

The effect of UGT2B7*2 polymorphism on the pharmacokinetics of OROS® hydromorphone in Taiwanese subjects.

J Clin Pharmacol 2014 Oct 15;54(10):1170-9. Epub 2014 Apr 15.

Johnson & Johnson Pharmaceutical Research and Development, Beerse, Belgium.

This open-label, single-center, phase I study (NCT1487564) investigated the effect of uridine diphosphate-glucuronosyltransferase2B7 (UGT2B7*2) genetic polymorphism (H268Y) on the pharmacokinetics (PK) and safety of a single, oral, 16-mg dose of OROS® hydromorphone and its metabolite in healthy Taiwanese subjects. Plasma concentrations of hydromorphone and hydromorphone-3-glucuronide were determined in 28 subjects. PK parameters calculated included maximum plasma concentration (Cmax); time to reach maximum plasma concentration (tmax); area under plasma concentration-time curve from 0-48 hours (AUC0-48 h) and 0-infinite time (AUC∞); and hydromorphone-3-glucuronide:hydromorphone metabolic ratio (RM). Mean plasma concentrations of hydromorphone and hydromorphone-3-glucuronide reached a maximum between 12-18 hours and 18-21 hours, respectively. No clear trend in PK parameters and no clinically significant differences in the incidence of treatment-emergent adverse events (TEAEs) were observed among different UGT2B7 genotypes. Our study found UGT2B7 polymorphism had no apparent effect on PK of OROS® hydromorphone; hydromorphone was well tolerated in pain-free volunteers when coadministered with naltrexone.
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http://dx.doi.org/10.1002/jcph.305DOI Listing
October 2014

NO-dependent endothelial dysfunction in type II diabetes is aggravated by dyslipidemia and hypertension, but can be restored by angiotensin-converting enzyme inhibition and weight loss.

J Vasc Res 2013 31;50(6):486-97. Epub 2013 Oct 31.

Department of Cardiovascular Sciences, Research Unit of Experimental Cardiac Surgery, KU Leuven, Leuven, Belgium.

Aims: Insulin resistance, dyslipidemia and hypertension are independent mediators of endothelial dysfunction. It is incompletely defined whether dyslipidemia and hypertension in addition to diabetes mellitus type II (DMII), as seen in the metabolic syndrome (MS), worsen diabetes-induced endothelial dysfunction. Furthermore, it is unclear whether treatment influences endothelial dysfunction similarly in MS and DMII. Therefore, we studied vascular reactivity and the effect of in vivo treatment with angiotensin-converting enzyme inhibition (ACE-I) or hypocaloric diet in LDL receptor- and leptin-deficient (ob/ob), double knockout mice (DKO), featuring MS and in ob/ob mice with DMII.

Methods And Results: Vascular reactivity was studied in isolated aortic ring segments. Maximum vasorelaxant response to acetylcholine (Ach) was more depressed in DKO than in ob/ob mice, whereas response to bradykinin (BK) was equally attenuated in both genotypes (52 ± 3 and 23 ± 9% reversal of preconstriction induced by 10(-7) M phenylephrine in DKO vs. 76 ± 3 and 23 ± 8% reversal of preconstriction in ob/ob mice, respectively). ACE-I and hypocaloric diet improved ACh-induced vasorelaxation significantly (89 ± 2 and 59 ± 2% reversal of preconstriction in DKO vs. 80 ± 3 and 84 ± 4% in ob/ob mice, respectively), but not the response to BK.

Conclusion: These results indicate a differential impact of DMII and MS on endothelial function. ACE-I and hypocaloric diet improved ACh-, but not BK-induced vasorelaxation in these mouse models of DMII and MS.
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http://dx.doi.org/10.1159/000355221DOI Listing
January 2014

ACE-inhibition, but not weight reduction restores cardiomyocyte response to β-adrenergic stimulation in the metabolic syndrome.

BMC Cardiovasc Disord 2013 Jul 12;13:51. Epub 2013 Jul 12.

Department of Cardiovascular Sciences, Research Unit of Experimental Cardiac Surgery, KU Leuven, Herestraat 49, Leuven B-3000, Belgium.

Background: Diabetic cardiomyopathy is characterized by systolic and early diastolic ventricular dysfunction. In the metabolic syndrome (MS), ventricular stiffness is additionally increased in a later stage. It is unknown whether this is related to intrinsic cardiomyocyte dysfunction, extrinsic factors influencing cardiomyocyte contractility and/or cardiac function, or a combination of both. A first aim was to study cardiomyocyte contractility and Ca2+ handling in vitro in a mouse model of MS. A second aim was to investigate whether in vivo hypocaloric diet or ACE-inhibition (ACE-I) improved cardiomyocyte contractility in vitro, contractile reserve and Ca2+ handling.

Methods: This study was performed in LDL-receptor (LDLR-/-) and leptin-deficient (ob/ob), double knock-out mice (DKO), featuring obesity, type II diabetes, atherogenic dyslipidemia and hypertension. Single knock-out LDLR-/-, ob/ob and wild type mice were used as controls. Cellular contractility, Ca2+ handling and their response to in vivo treatment with diet or ACE-I were studied in isolated cardiomyocytes at baseline, during β-adrenergic stimulation or increased extracellular Ca2+, using field stimulation and patch-clamp.

Results: In untreated conditions, prolongation of contraction-relaxation cycle and altered Ca2+ handling are observed in MS. Response to increased extracellular Ca2+ and β-adrenergic stimulation is impaired and could not be rescued by weight loss. ACE-I restored impaired response to β-adrenergic stimulation in MS, but not the decreased response to increased extracellular Ca2+.

Conclusions: Cardiomyocyte contractility and β-adrenergic response are impaired in MS, due to alterations in cellular Ca2+ handling. ACE-I, but not weight loss, is able to restore cardiomyocyte response to β-adrenergic stimulation in MS.
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http://dx.doi.org/10.1186/1471-2261-13-51DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3729821PMC
July 2013

Prediction of human oral plasma concentration-time profiles using preclinical data: comparative evaluation of prediction approaches in early pharmaceutical discovery.

Clin Pharmacokinet 2011 Aug;50(8):505-17

ADME-TOX Department, Johnson and Johnson Pharmaceutical Research and Development, Beerse, Belgium.

Background And Objectives: Empirically based methods remain one of our tools in human pharmacokinetic predictions. The Dedrick approach and the steady-state plasma drug concentration (C(ss))-mean residence time (MRT) approach are based on the assumption that concentration-time profiles are similar among species, including man, and that curves derived from a variety of animal species can be superimposed after mathematical transformation. In the Dedrick approach the transformation is based on the slope and intercept of the allometric relationship. The C(ss)-MRT approach is based on the implementation of measured animal and predicted human MRT and dose/volume of distribution at steady state (V(ss)). The aims of the present study were to compare the predictive performance of concentration-time profiles obtained by these approaches, to evaluate the prediction of individual pharmacokinetic parameters by these approaches and to further refine these approaches incorporating the experience from our previous work.

Methods: A retrospective analysis using 35 proprietary compounds developed at Johnson & Johnson Pharmaceutical Research and Development was conducted to compare the accuracies of the Dedrick and C(ss)-MRT approaches for predicting oral concentration-time profiles and pharmacokinetic parameters in man. In the first step, input for the transformation was based on simple allometry. Then we assessed whether both methods could be fine-tuned by systematically incorporating correction factors (maximum life span potential, brain weight and plasma protein binding), depending on the interspecies relationship. In addition, for the C(ss)-MRT approach, we used formulas based on multivariate regression analysis as input for the transformation.

Results: Inclusion of correction factors significantly improved the profile predictability for the Dedrick and C(ss)-MRT approaches. This was mainly linked to an improved prediction of terminal elimination half-life (t(½)), MRT and the ratio between the maximum plasma concentration and the concentration at the last observed time point (C(max)/C(last)). No significant differences were observed between the Dedrick approach with correction factors, the C(ss)-MRT approach with correction factors and the C(ss)-MRT approach, based on the regression equations.

Conclusions: Based on the dataset evaluated in this study, we demonstrated that human plasma concentration-time profiles and pharmacokinetic parameters could be predicted with the Dedrick and C(ss)-MRT approaches and that if correction factors were implemented, the predictions improved significantly. With the requirement of only a limited preclinical in vivo pharmacokinetic dataset, these empirical methods could offer potential in the early stages of drug discovery.
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http://dx.doi.org/10.2165/11587230-000000000-00000DOI Listing
August 2011

Increased catecholamine secretion contributes to hypertension in TRPM4-deficient mice.

J Clin Invest 2010 Sep 2;120(9):3267-79. Epub 2010 Aug 2.

Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg, Germany.

Hypertension is an underlying risk factor for cardiovascular disease. Despite this, its pathogenesis remains unknown in most cases. Recently, the transient receptor potential (TRP) channel family was associated with the development of several cardiovascular diseases linked to hypertension. The melastatin TRP channels TRPM4 and TRPM5 have distinct properties within the TRP channel family: they form nonselective cation channels activated by intracellular calcium ions. Here we report the identification of TRPM4 proteins in endothelial cells, heart, kidney, and chromaffin cells from the adrenal gland, suggesting that they have a role in the cardiovascular system. Consistent with this hypothesis, Trpm4 gene deletion in mice altered long-term regulation of blood pressure toward hypertensive levels. No changes in locomotor activity, renin-angiotensin system function, electrolyte and fluid balance, vascular contractility, and cardiac contractility under basal conditions were observed. By contrast, inhibition of ganglionic transmission with either hexamethonium or prazosin abolished the difference in blood pressure between Trpm4-/- and wild-type mice. Strikingly, plasma epinephrine concentration as well as urinary excretion of catecholamine metabolites were substantially elevated in Trpm4-/- mice. In freshly isolated chromaffin cells, lack of TRPM4 was shown to cause markedly more acetylcholine-induced exocytotic release events, while neither cytosolic calcium concentration, size, nor density of vesicles were different. We therefore conclude that TRPM4 proteins limit catecholamine release from chromaffin cells and that this contributes to increased sympathetic tone and hypertension.
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http://dx.doi.org/10.1172/JCI41348DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2929713PMC
September 2010

Food-restriction in obese dyslipidaemic diabetic mice partially restores basal contractility but not contractile reserve.

Eur J Heart Fail 2009 Dec;11(12):1118-25

Department of Cardiovascular Diseases, Division of Experimental Cardiac Surgery, Katholieke Universiteit Leuven, Leuven, Belgium.

Aims: Weight reduction programmes in morbidly obese, diabetic, and hyperlipidaemic subjects usually improve cardiac load and subsequently reverse hypertrophy. However, their effect on contractile dysfunction and impaired cardiac functional reserve is unknown.

Methods And Results: The effect of food-restriction-induced weight loss on in vivo cardiac contractility before and during beta-adrenergic stimulation was assessed using left ventricular pressure-volume analysis in a mouse model featuring obesity and Type II diabetes (ob/ob), obesity, Type II diabetes, atherogenic dyslipidaemia, and hypertension (LDLR-/-;ob/ob), or wild-type. In addition, sarcoendoplasmic reticulum (SR) Ca(2+) reuptake, interstitial collagen accumulation, and aortic atherosclerosis were measured. Food-restriction resulted in a 54% lower weight. Weight loss largely normalized pre- and afterload in both ob/ob and LDLR-/-;ob/ob mice. Contractility and relaxation improved after weight loss, partly explained by improved SR Ca(2+) reuptake. Ventricular-vascular stiffening, interstitial collagen accumulation, and aortic atherosclerosis were less in food-restricted than in free-fed LDLR-/-;ob/ob mice. In contrast, cardiac reserve was similarly impaired in free-fed and food-restricted ob/ob and LDLR-/-;ob/ob mice.

Conclusion: Food-restriction in obese diabetic mice leads to improved cardiac performance by diminishing cardiac load and by ameliorating the intrinsic contractile properties of the cardiac muscle. However, cardiac reserve under dobutamine stimulation did not increase.
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http://dx.doi.org/10.1093/eurjhf/hfp156DOI Listing
December 2009

Ventricular phosphodiesterase-5 expression is increased in patients with advanced heart failure and contributes to adverse ventricular remodeling after myocardial infarction in mice.

Circulation 2009 Jan 12;119(3):408-16. Epub 2009 Jan 12.

Vesalius Research Center, Flanders Institute for Biotechnology, Leuven, Belgium.

Background: Ventricular expression of phosphodiesterase-5 (PDE5), an enzyme responsible for cGMP catabolism, is increased in human right ventricular hypertrophy, but its role in left ventricular (LV) failure remains incompletely understood. We therefore measured LV PDE5 expression in patients with advanced systolic heart failure and characterized LV remodeling after myocardial infarction in transgenic mice with cardiomyocyte-specific overexpression of PDE5 (PDE5-TG).

Methods And Results: Immunoblot and immunohistochemistry techniques revealed that PDE5 expression was greater in explanted LVs from patients with dilated and ischemic cardiomyopathy than in control hearts. To evaluate the impact of increased ventricular PDE5 levels on cardiac function, PDE5-TG mice were generated. Confocal and immunoelectron microscopy revealed increased PDE5 expression in cardiomyocytes, predominantly localized to Z-bands. At baseline, myocardial cGMP levels, cell shortening, and calcium handling in isolated cardiomyocytes and LV hemodynamic measurements were similar in PDE5-TG and wild-type littermates. Ten days after myocardial infarction, LV cGMP levels had increased to a greater extent in wild-type mice than in PDE5-TG mice (P<0.05). Ten weeks after myocardial infarction, LV end-systolic and end-diastolic volumes were larger in PDE5-TG than in wild-type mice (57+/-5 versus 39+/-4 and 65+/-6 versus 48+/-4 muL, respectively; P<0.01 for both). LV systolic dysfunction and diastolic dysfunction were more marked in PDE5-TG than in wild-type mice, associated with enhanced hypertrophy and reduced contractile function in isolated cardiomyocytes from remote myocardium.

Conclusions: Increased PDE5 expression predisposes mice to adverse LV remodeling after myocardial infarction. Increased myocardial PDE5 expression in patients with advanced cardiomyopathy may contribute to the development of heart failure and represents an important therapeutic target.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.108.822072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3791110PMC
January 2009

Long-term blinded placebo-controlled study of SNT-MC17/idebenone in the dystrophin deficient mdx mouse: cardiac protection and improved exercise performance.

Eur Heart J 2009 Jan 10;30(1):116-24. Epub 2008 Sep 10.

Department of Pediatric Neurology, University Hospitals Leuven, Herestraat, Leuven, Belgium.

Aims: Duchenne muscular dystrophy (DMD) is a severe and still incurable disease, with heart failure as a leading cause of death. The identification of a disease-modifying therapy may require early-initiated and long-term administration, but such type of therapeutic trial is not evident in humans. We have performed such a trial of SNT-MC17/idebenone in the mdx mouse model of DMD, based on the drug's potential to improve mitochondrial respiratory chain function and reduce oxidative stress.

Methods And Results: In this study, 200 mg/kg bodyweight of either SNT-MC17/idebenone or placebo was given from age 4 weeks until 10 months in mdx and wild-type mice. All evaluators were blinded to mouse type and treatment groups. Idebenone treatment significantly corrected cardiac diastolic dysfunction and prevented mortality from cardiac pump failure induced by dobutamine stress testing in vivo, significantly reduced cardiac inflammation and fibrosis, and significantly improved voluntary running performance in mdx mice.

Conclusion: We have identified a novel potential therapeutic strategy for human DMD, as SNT-MC17/idebenone was cardioprotective and improved exercise performance in the dystrophin-deficient mdx mouse. Our data also illustrate that the mdx mouse provides unique opportunities for long-term controlled prehuman therapeutic studies.
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http://dx.doi.org/10.1093/eurheartj/ehn406DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2639086PMC
January 2009

Dyslipidaemia in type II diabetic mice does not aggravate contractile impairment but increases ventricular stiffness.

Cardiovasc Res 2008 Jan 14;77(2):371-9. Epub 2007 Aug 14.

Laboratory of Experimental Cardiac Surgery, Department of Cardiovascular Disease, Katholieke Universiteit Leuven, Provisorium I, Minderbroedersstraat 19, K.U.Leuven postbus 01033 - FEHA, 3000 Leuven, Belgium.

Aims: Type II diabetes, often associated with abdominal obesity, frequently leads to heart failure. Clinical and epidemiological evidence suggests that supplemental dyslipidaemia and hypertension, as clustered in the metabolic syndrome, aggravate the cardiovascular outcome. The differential impact of type II diabetes and the metabolic syndrome on left ventricular function, however, remains incompletely defined.

Methods And Results: We studied left ventricular function in vivo using pressure-volume analysis in obese diabetic mice with leptin deficiency (ob/ob) and obese diabetic dyslipidemic mice with combined leptin and low-density lipoprotein-receptor deficiency (DKO). ob/ob and DKO mice developed a diabetic cardiomyopathy, characterized by impaired contractility and relaxation, from the age of 24 weeks onwards. This was-at least partially-explained by increased apoptosis and disturbed Ca(2+) reuptake in the sarcoplasmic reticulum (SR) in both mouse models. DKO, but not ob/ob, developed increased end-diastolic ventricular stiffness, paralleled by increased left ventricular myocardial fibrosis. Cardiac output was preserved in ob/ob mice by favourable loading conditions, whereas it decreased in DKO mice.

Conclusions: Type II diabetes in mice leads to impaired contractility and relaxation due to disturbed Ca(2+) reuptake in the SR, but only when dyslipidaemia and hypertension are superimposed does vascular-ventricular stiffening increase and left ventricular myocardial fibrosis develop.
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http://dx.doi.org/10.1093/cvr/cvm001DOI Listing
January 2008

Parameters of ventricular contractility in mice: influence of load and sensitivity to changes in inotropic state.

Pflugers Arch 2008 Mar 12;455(6):987-94. Epub 2007 Oct 12.

Department of Cardiovascular Diseases, Division of Experimental Cardiac Surgery, Katholieke Universiteit Leuven, Provisorium I, Minderbroedersstraat 19, K.U.Leuven postbus: 01033-FEHA, 3000 Leuven, Belgium.

We examined the relative usefulness of parameters to determine left ventricular contractility in mice invasively. The optimal parameter must be sensitive to changes in inotropy and insensitive to changes in loading. Furthermore, it should be able to confirm or reject the hypothesis of altered myocardial contractility after a limited number of experiments. Left ventricular function was assessed in closed-chest mice using a microtip pressure-conductance catheter at baseline and after increases in preload, afterload, or contractility. The parameters are differentially influenced by loading conditions and inotropic state. Only those parameters that could differentiate between basal and increased contractility with a power of 0.85 in ten or less experiments were considered useful. Ejection fraction, preload-recruitable stroke work (PRSW), and dP/dt(max)/V (ed) could demonstrate the smallest changes in contractility. Stroke work, maximal power and dP/dt(max) were most influenced by preload. End-systolic elastance, ejection fraction, and stroke work were afterload-dependent. Dividing the magnitude of the effect of inotropic stimulation to that of load changes gives an index for the usefulness for each parameter. A high ratio indicates that the change in parameter reflects inotropic rather than load change. This ratio was highest for PRSW, which seems to be the best parameter for judging contractility differences in mice.
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http://dx.doi.org/10.1007/s00424-007-0362-8DOI Listing
March 2008

A SERCA2 pump with an increased Ca2+ affinity can lead to severe cardiac hypertrophy, stress intolerance and reduced life span.

J Mol Cell Cardiol 2006 Aug 30;41(2):308-17. Epub 2006 Jun 30.

Laboratory of Physiology, University of Leuven, Belgium.

Abnormal Ca(2+) cycling in the failing heart might be corrected by enhancing the activity of the cardiac Ca(2+) pump, the sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) isoform. This can be obtained by increasing the pump's affinity for Ca(2+) by suppressing phospholamban (PLB) activity, the in vivo inhibitor of SERCA2a. In SKO mice, gene-targeted replacement of SERCA2a by SERCA2b, a pump with a higher Ca(2+) affinity, results in cardiac hypertrophy and dysfunction. The stronger PLB inhibition on cardiac morphology and performance observed in SKO was investigated here in DKO mice, which were obtained by crossing SKO with PLB(-/-) mice. The affinity for Ca(2+) of SERCA2 was found to be further increased in these DKO mice. Relative to wild-type and SKO mice, DKO mice were much less spontaneously active and showed a reduced life span. The DKO mice also displayed a severe cardiac phenotype characterized by a more pronounced concentric hypertrophy, diastolic dysfunction and increased ventricular stiffness. Strikingly, beta-adrenergic or forced exercise stress induced acute heart failure and death in DKO mice. Therefore, the increased PLB inhibition represents a compensation for the imposed high Ca(2+)-affinity of SERCA2b in the SKO heart. Limiting SERCA2's affinity for Ca(2+) is physiologically important for normal cardiac function. An improved Ca(2+) transport in the sarcoplasmic reticulum may correct Ca(2+) mishandling in heart failure, but a SERCA pump with a much higher Ca(2+) affinity may be detrimental.
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http://dx.doi.org/10.1016/j.yjmcc.2006.05.014DOI Listing
August 2006

Type II diabetic mice exhibit contractile dysfunction but maintain cardiac output by favourable loading conditions.

Eur J Heart Fail 2006 Dec 22;8(8):777-83. Epub 2006 May 22.

Laboratory of Experimental Cardiac Surgery, K.U. Leuven, Provisorium I, Minderbroedersstraat 17, 3000 Leuven, Belgium.

Background: Cardiomyopathy in type II diabetes is incompletely understood. The leptin receptor-deficient (db/db) mouse is a well-accepted model of type II diabetes. To date, left ventricular contractility has not been studied in animal models of type II diabetes with in vivo load-independent parameters.

Aim: To determine cardiac function in db/db mice in vivo.

Methods: Cardiac function in 12- and 24-week-old db/db and wild-type mice was assessed using a microtip-pressure-conductance catheter.

Results: Left ventricular contractile dysfunction, measured by load-independent parameters (preload recruitable stroke work, end-systolic elastance, dP/dt-V(ed)), is present in diabetic mice from age 24 weeks onwards. Despite this contractile dysfunction, the conventional parameters cardiac output, ejection fraction and dP/dt(max) were maintained, which was due to an increased preload and decreased afterload. Ventriculo-arterial coupling was increased and mechanical efficiency significantly reduced in db/db mice.

Conclusion: Our results demonstrate that, despite impaired cardiac contractility and mechanical efficiency, cardiac output is maintained in db/db mice by favourable loading conditions and that in vivo load-independent measurements are necessary to fully characterize cardiac performance in animal models of pathophysiological states.
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http://dx.doi.org/10.1016/j.ejheart.2006.03.001DOI Listing
December 2006

Interleukin-6 causes myocardial failure and skeletal muscle atrophy in rats.

Circulation 2005 Mar 14;111(8):996-1005. Epub 2005 Feb 14.

Laboratory of Pneumology, Respiratory Muscle Research Unit, Katholieke Universiteit Leuven, Leuven, Belgium.

Background: The impact of interleukin (IL)-6 on skeletal muscle function remains the subject of controversy.

Methods And Results: The effects of 7-day subcutaneous administration of recombinant human IL-6 were examined at 3 doses, 50, 100, or 250 microg x kg(-1) x d(-1), in rats. Skeletal muscle mass decreased dose-dependently (with increasing dose: in the diaphragm, -10%, P=NS; -15%, P=0.0561; and -15% P<0.05; and in the gastrocnemius, -9%, P=NS; -9%, P=NS; and -18%, P<0.005) because of decreases in cross-sectional area of all fiber types without alterations in diaphragm contractile properties. Cardiovascular variables showed a dose-dependent heart dilatation (for end-diastolic volume: control, 78 microL; moderate dose, 123 microL; and high dose, 137 microL, P<0.001), reduced end-systolic pressure (control, 113 mm Hg; moderate dose, 87 mm Hg; and high dose, 90 mm Hg; P=0.037), and decreased myocardial contractility (for preload recruitable stroke work: control, 79 mm Hg; moderate dose, 67 mm Hg; and high dose, 48 mm Hg; P<0.001). Lung edema was confirmed by an increased wet-to-dry ratio (control, 4.2; moderate dose, 4.6; and high dose, 4.5; P<0.001) and microscopy findings. These cardiovascular alterations led to decreases in organ blood flow, particularly in the diaphragm (control, 0.56 mL x min(-1) x g(-1); moderate dose, 0.21 mL x min(-1) x g(-1); and high dose, 0.23 mL x min(-1) x g(-1); P=0.037). In vitro recombinant human IL-6 administration did not cause any alterations in diaphragm force or endurance capacity.

Conclusions: IL-6 clearly caused ventilatory and peripheral skeletal muscle atrophy, even after short-term administration. Blood flow redistribution, resulting from the myocardial failure induced by IL-6, was likely responsible for this muscle atrophy, because IL-6 did not exert any direct effect on the diaphragm.
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http://dx.doi.org/10.1161/01.CIR.0000156469.96135.0DDOI Listing
March 2005