Maternal therapy with Ad.VEGF-A165 increases fetal weight at term in a guinea pig model of fetal growth restriction

OBJECTIVES: We have demonstrated that transient uterine artery VEGF overexpression improves fetal growth in growth restricted sheep pregnancy. We tested this hypothesis in guinea pig pregnancies, where placental physiology more closely resembles that in humans. METHOD: Virgin guinea pigs were nutrient restricted peri-conceptually to create fetal growth restriction (FGR). At day 29-36 (term=65days) at laparotomy Ad.VEGF-A165 or Ad.LacZ (1x1010vp) were applied externally to the uterine circulation using a thermosensitive gel. Dams were sacrificed after 3-8 days or at term. Pups were weighed and tissues sampled for vector spread, VEGF expression and its downstream effects. RESULTS: Ad.VEGF-A165 significantly increased fetal weight at term (88.01±13.36g, n=26) compared to control Ad.LacZ treatment (85.52±13.00g, n=19, p=0.028). Brain, liver, lung weight and crown rump length were significantly larger 3-8 days post-administration, VEGF expression was demonstrated by ELISA and confirmed by immunohistochemistry in transduced tissues. RT-PCR of term samples confirmed vector transduction in target tissues, but the transgene was undetectable in fetal samples. Tissue histological analysis and blood biochemistry/haematological examination was normal. Uterine arteries from Ad.VEGF-A165-treated dams relaxed more completely than those from Ad.LacZ treated dams. CONCLUSIONS: Maternal uterine artery Ad.VEGF-A165 increases fetal growth velocity and term fetal weight in growth restricted guinea pig pregnancy

GAA repeat expansion mutation mouse models of Friedreich ataxia exhibit oxidative stress leading to progressive neuronal and cardiac pathology

Friedreich ataxia (FRDA) is a neurodegenerative disorder caused by an unstable GAA repeat expansion mutation within intron 1 of the FXN gene. However, the origins of the GAA repeat expansion, its unstable dynamics within different cells and tissues, and its effects on frataxin expression are not yet completely understood. Therefore, we have chosen to generate representative FRDA mouse models by using the human FXN GAA repeat expansion itself as the genetically modified mutation. We have previously reported the establishment of two lines of human FXN YAC transgenic mice that contain unstable GAA repeat expansions within the appropriate genomic context. We now describe the generation of FRDA mouse models by crossbreeding of both lines of human FXN YAC transgenic mice with heterozygous Fxn knockout mice. The resultant FRDA mice that express only human-derived frataxin show comparatively reduced levels of frataxin mRNA and protein expression, decreased aconitase activity, and oxidative stress, leading to progressive neurodegenerative and cardiac pathological phenotypes. Coordination deficits are present, as measured by accelerating rotarod analysis, together with a progressive decrease in locomotor activity and increase in weight. Large vacuoles are detected within neurons of the dorsal root ganglia (DRG), predominantly within the lumbar regions in 6-month-old mice, but spreading to the cervical regions after 1 year of age. Secondary demyelination of large axons is also detected within the lumbar roots of older mice. Lipofuscin deposition is increased in both DRG neurons and cardiomyocytes, and iron deposition is detected in cardiomyocytes after 1 year of age. These mice represent the first GAA repeat expansion-based FRDA mouse models that exhibit progressive FRDA-like pathology and thus will be of use in testing potential therapeutic strategies, particularly GAA repeat-based strategies. © 2006 Elsevier Inc. All rights reserved

Neutrophils induce proangiogenic T cells with a regulatory phenotype in pregnancy

Although neutrophils are known to be fundamental in controlling innate immune responses, their role in regulating adaptive immunity is just starting to be appreciated. We report that human neutrophils exposed to pregnancy hormones progesterone and estriol promote the establishment of maternal tolerance through the induction of a population of CD4$^{+}$ T cells displaying a GARP$^{+}$CD127$^{Io}$FOXP3$^{+}$ phenotype following antigen activation. Neutrophil-induced T (niT) cells produce IL-10, IL-17, and VEGF and promote vessel growth in vitro. Neutrophil depletion during murine pregnancy leads to abnormal development of the fetal-maternal unit and reduced empbryo development, with placental architecture displaying poor trophoblast invasion and spiral artery development in the maternal decidua, accompanied by significantly attenuated niT cell numbers in draining lymph nodes. Using CD45 congenic cells, we show that induction of niT cells and their regulatory function occurs via transfer of apoptotic neutrophil-derived proteins, including forkhead box protein 1 (FOXO1), to T cells. Unlike in women with healthy pregnancies, neutrophils from blood and placental samples of preeclamptic women fail to induce niT cells as a direct consequence of their inability to transfer FOXO1 to T cells. Finally, neutrophil-selective FOXO1 knockdown leads to defective placentation and compromised embryo development, similar to that resulting from neutrophil depletion. These data define a nonredundant function of neutrophil-T cell interactions in the regulation of vascularization at the maternal-fetal interface.S.N. and M.P. were supported by the Wellcome Trust (Programme 086867/Z/08/Z). F.M.M.-B. is supported by the British Heart Foundation (CH/15/2/32064). D.J.W. is supported by the National Institute for Health Research University College London Hospitals Biomedical Research Centre. S.H.P.F. is a Research Fellow at CNPq. This work is part of the research themes contributing to the translational research portfolio of Barts and the London Cardiovascular Biomedical Research Unit, which is supported and funded by the National Institutes of Health Research

Heterogeneity of human adipose blood flow

BACKGROUND: The long time pharmacokinetics of highly lipid soluble compounds is dominated by blood-adipose tissue exchange and depends on the magnitude and heterogeneity of adipose blood flow. Because the adipose tissue is an infinite sink at short times (hours), the kinetics must be followed for days in order to determine if the adipose perfusion is heterogeneous. The purpose of this paper is to quantitate human adipose blood flow heterogeneity and determine its importance for human pharmacokinetics. METHODS: The heterogeneity was determined using a physiologically based pharmacokinetic model (PBPK) to describe the 6 day volatile anesthetic data previously published by Yasuda et. al. The analysis uses the freely available software PKQuest and incorporates perfusion-ventilation mismatch and time dependent parameters that varied from the anesthetized to the ambulatory period. This heterogeneous adipose perfusion PBPK model was then tested by applying it to the previously published cannabidiol data of Ohlsson et. al. and the cannabinol data of Johansson et. al. RESULTS: The volatile anesthetic kinetics at early times have only a weak dependence on adipose blood flow while at long times the pharmacokinetics are dominated by the adipose flow and are independent of muscle blood flow. At least 2 adipose compartments with different perfusion rates (0.074 and 0.014 l/kg/min) were needed to describe the anesthetic data. This heterogeneous adipose PBPK model also provided a good fit to the cannabinol data. CONCLUSION: Human adipose blood flow is markedly heterogeneous, varying by at least 5 fold. This heterogeneity significantly influences the long time pharmacokinetics of the volatile anesthetics and tetrahydrocannabinol. In contrast, using this same PBPK model it can be shown that the long time pharmacokinetics of the persistent lipophilic compounds (dioxins, PCBs) do not depend on adipose blood flow. The ability of the same PBPK model to describe both the anesthetic and cannabinol kinetics provides direct qualitative evidence that their kinetics are flow limited and that there is no significant adipose tissue diffusion limitation

Human physiologically based pharmacokinetic model for propofol

BACKGROUND: Propofol is widely used for both short-term anesthesia and long-term sedation. It has unusual pharmacokinetics because of its high lipid solubility. The standard approach to describing the pharmacokinetics is by a multi-compartmental model. This paper presents the first detailed human physiologically based pharmacokinetic (PBPK) model for propofol. METHODS: PKQuest, a freely distributed software routine , was used for all the calculations. The "standard human" PBPK parameters developed in previous applications is used. It is assumed that the blood and tissue binding is determined by simple partition into the tissue lipid, which is characterized by two previously determined set of parameters: 1) the value of the propofol oil/water partition coefficient; 2) the lipid fraction in the blood and tissues. The model was fit to the individual experimental data of Schnider et. al., Anesthesiology, 1998; 88:1170 in which an initial bolus dose was followed 60 minutes later by a one hour constant infusion. RESULTS: The PBPK model provides a good description of the experimental data over a large range of input dosage, subject age and fat fraction. Only one adjustable parameter (the liver clearance) is required to describe the constant infusion phase for each individual subject. In order to fit the bolus injection phase, for 10 or the 24 subjects it was necessary to assume that a fraction of the bolus dose was sequestered and then slowly released from the lungs (characterized by two additional parameters). The average weighted residual error (WRE) of the PBPK model fit to the both the bolus and infusion phases was 15%; similar to the WRE for just the constant infusion phase obtained by Schnider et. al. using a 6-parameter NONMEM compartmental model. CONCLUSION: A PBPK model using standard human parameters and a simple description of tissue binding provides a good description of human propofol kinetics. The major advantage of a PBPK model is that it can be used to predict the changes in kinetics produced by variations in physiological parameters. As one example, the model simulation of the changes in pharmacokinetics for morbidly obese subjects is discussed

Maternal cardiovascular and immune regulatory factors before the onset of pre-eclampsia

Pre-eclampsia is a pregnancy syndrome characterised by maternal hypertension and proteinuria and often associated with multi-organ dysfunction and fetal growth restriction. The aetiology of pre-eclampsia remains elusive, so a clearer understanding of the pathophysiology leading to the clinical syndrome would improve our ability to predict, prevent and treat this condition. Pre-eclampsia is known to be associated with impaired utero-placental blood flow, maternal endothelial dysfunction and an exaggerated systemic inflammatory response. Women at risk of pre-eclampsia have classical cardiovascular risk factors, including obesity and chronic hypertension. Surprisingly, smoking during pregnancy has a protective effect against pre-eclampsia. The reason behind this paradox is unknown. This thesis prospectively examines the sequence of changes in blood pressure, angiogenic and regulatory immune factors in a cohort of pregnant women recruited early in pregnancy and followed until childbirth. Pregnant women were assigned to three groups: low risk of pre-eclampsia, high risk of pre-eclampsia, or women who continued to smoke through pregnancy. Differences in prospectively determined immune-regulatory and angiogenic factors between groups were correlated with maternal blood pressure before the onset of pre-eclampsia, fetal growth restriction and pregnancy induced hypertension. Smokers were included to determine how they might be protected from developing pre-eclampsia, but vulnerable to fetal growth restriction. Results provide further insight into the pathogenesis of pre-eclampsia and a novel algorithm to identify women at risk of pre-eclampsia. Attempts to identify a putative angiotensin II receptor stimulating autoantibody are also described. Taken together, this thesis aims to enhance the understanding of the multiple pathological pathways leading to pre-eclampsia, in order to find novel pathways to improve the clinical outcome for mother and baby