Publications by authors named "Christian Wadsack"

54 Publications

Fetal High-Density Lipoproteins: Current Knowledge on Particle Metabolism, Composition and Function in Health and Disease.

Biomedicines 2021 Mar 30;9(4). Epub 2021 Mar 30.

Division of Pharmacology, Otto Loewi Research Center, Medical University of Graz, Universitätsplatz 4, 8010 Graz, Austria.

Cholesterol and other lipids carried by lipoproteins play an indispensable role in fetal development. Recent evidence suggests that maternally derived high-density lipoprotein (HDL) differs from fetal HDL with respect to its proteome, size, and function. Compared to the HDL of adults, fetal HDL is the major carrier of cholesterol and has a unique composition that implies other physiological functions. Fetal HDL is enriched in apolipoprotein E, which binds with high affinity to the low-density lipoprotein receptor. Thus, it appears that a primary function of fetal HDL is the transport of cholesterol to tissues as is accomplished by low-density lipoproteins in adults. The fetal HDL-associated bioactive sphingolipid sphingosine-1-phosphate shows strong vasoprotective effects at the fetoplacental vasculature. Moreover, lipoprotein-associated phospholipase A2 carried by fetal-HDL exerts anti-oxidative and athero-protective functions on the fetoplacental endothelium. Notably, the mass and activity of HDL-associated paraoxonase 1 are about 5-fold lower in the fetus, accompanied by an attenuation of anti-oxidative activity of fetal HDL. Cholesteryl ester transfer protein activity is reduced in fetal circulation despite similar amounts of the enzyme in maternal and fetal serum. This review summarizes the current knowledge on fetal HDL as a potential vasoprotective lipoprotein during fetal development. We also provide an overview of whether and how the protective functionalities of HDL are impaired in pregnancy-related syndromes such as pre-eclampsia or gestational diabetes mellitus.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/biomedicines9040349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8067099PMC
March 2021

Induction of the sphingosine-1-phosphate signaling pathway by TGF-β1 during Langerhans-type dendritic cell differentiation.

Eur J Immunol 2021 Mar 26. Epub 2021 Mar 26.

Division of Immunology and Pathophysiology, Otto Loewi Research Center, Medical University of Graz, Graz, Styria, Austria.

Gene profiling revealed that the S1P signaling pathway is induced by TGF-β1 during LC commitment of monocytopoietic cells. Constitutive-active TGF-β1-S1P signaling seems to elevate the activation threshold of LCs and thereby prevent inappropriate and overshooting immune responses to microbial and physicochemical environmental signals. In turn, signals that lead to LC migration may disrupt this pathway via inhibiting S1P bioavailability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/eji.202049013DOI Listing
March 2021

Placental mobilization of free fatty acids contributes to altered materno-fetal transfer in obesity.

Int J Obes (Lond) 2021 May 26;45(5):1114-1123. Epub 2021 Feb 26.

Department of Obstetrics and Gynaecology, Medical University of Graz, Graz, Austria.

Background: Metabolic changes in obese pregnant women, such as changes of plasma lipids beyond physiological levels, may subsequently affect fetal development in utero. These metabolic derangements may remain in the offspring and continue throughout life. The placenta mediates bidirectional exchange of nutrients between mother and fetus. The impact of prepregnancy obesity on placental transfer of lipids is still unknown.

Objective: We aimed to examine materno-to-fetal free fatty acid (FFA) transfer by a combined experimental and modeling approach. Flux of C-labeled FFA was evaluated by ex vivo perfusion of human placentae as a function of prepregnancy obesity. Mathematical modeling complemented ex vivo results by providing FFA kinetic parameters.

Results: Obesity was strongly associated with elevated materno-to-fetal transfer of applied C-FFA. Clearance of polyunsaturated C-docosahexaenoic acid (DHA) was most prominently affected. The use of the mathematical model revealed a lower tissue storage capacity for DHA in obese compared with lean placentae.

Conclusion: Besides direct materno-to-fetal FFA transfer, placental mobilization accounts for the fetal FA supply. Together, with metabolic changes in the mother and an elevated materno-fetal FFA transfer shown in obesity, these changes suggest that they may be transmitted to the fetus, with yet unknown consequences.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41366-021-00781-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8081658PMC
May 2021

Endothelial Lipase Modulates Paraoxonase 1 Content and Arylesterase Activity of HDL.

Int J Mol Sci 2021 Jan 13;22(2). Epub 2021 Jan 13.

Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria.

Endothelial lipase (EL) is a strong modulator of the high-density lipoprotein (HDL) structure, composition, and function. Here, we examined the impact of EL on HDL paraoxonase 1 (PON1) content and arylesterase (AE) activity in vitro and in vivo. The incubation of HDL with EL-overexpressing HepG2 cells decreased HDL size, PON1 content, and AE activity. The EL modification of HDL did not diminish the capacity of HDL to associate with PON1 when EL-modified HDL was incubated with PON1-overexpressing cells. The overexpression of EL in mice significantly decreased HDL serum levels but unexpectedly increased HDL PON1 content and HDL AE activity. Enzymatically inactive EL had no effect on the PON1 content of HDL in mice. In healthy subjects, EL serum levels were not significantly correlated with HDL levels. However, HDL PON1 content was positively associated with EL serum levels. The EL-induced changes in the HDL-lipid composition were not linked to the HDL PON1 content. We conclude that primarily, the interaction of enzymatically active EL with HDL, rather than EL-induced alterations in HDL size and composition, causes PON1 displacement from HDL in vitro. In vivo, the EL-mediated reduction of HDL serum levels and the consequently increased PON1-to-HDL ratio in serum increase HDL PON1 content and AE activity in mice. In humans, additional mechanisms appear to underlie the association of EL serum levels and HDL PON1 content.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms22020719DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7828365PMC
January 2021

Research on nanoparticles in human perfused placenta: State of the art and perspectives.

Placenta 2021 Jan 28;104:199-207. Epub 2020 Dec 28.

Laboratory for Particles-Biology Interactions, Empa, Swiss Federal Laboratories for Materials Science and Technology, Lerchenfeldstrasse 5, 9014, St. Gallen, Switzerland. Electronic address:

Increasing human exposure to nanoparticles (NPs) from various sources raises concerns for public health, especially for vulnerable risk groups like pregnant women and their developing fetuses. However, nanomedicine and the prospect of creating safe and effective NP-based formulations of drugs hold great promise to revolutionize treatment during pregnancy. With maternal and fetal health at stake, risks and opportunities of NPs in pregnancy need to be carefully investigated. Importantly, a comprehensive understanding of NP transport and effects at the placenta is urgently needed considering the central position of the placenta at the maternal-fetal interface and its many essential functions to enable successful pregnancy. The perfusion of human placental tissue provides a great opportunity to achieve predictive human relevant insights, circumventing uncertainties due to considerable differences in placental structure and function across species. Here, we have reviewed the current literature on the ex vivo human placenta perfusion of NPs. From 16 available studies, it was evident that placental uptake and transfer of NPs are highly dependent on their characteristics like size and surface modifications, which is in line with previous observations from in vitro and animal transport studies. These studies further revealed that special considerations apply for the perfusion of NPs and we identified relevant controls that should be implemented in future perfusion studies. While current studies mostly focused on placental transfer of NPs to conclude on potential fetal exposure, the ex vivo placental perfusion model has considerable potential to reveal novel insights on NP effects on placental tissue functionality and signaling that could indirectly affect maternal-fetal health.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.placenta.2020.12.014DOI Listing
January 2021

Plasma proteins facilitates placental transfer of polystyrene particles.

J Nanobiotechnology 2020 Sep 9;18(1):128. Epub 2020 Sep 9.

Department of Obstetrics and Gynecology, Medical University of Graz, Auenbruggerplatz 14, 8036, Graz, Austria.

Background: Nanoparticles, which are exposed to biological fluids are rapidly interacting with proteins and other biomolecules forming a corona. In addition to dimension, charge and material the distinct protein corona influences the interplay of nanoparticles with tissue barriers. In this study we were focused on the impact of in situ formed human plasma protein corona on the transfer of 80 nm polystyrene nanoparticles (PS-particles) across the human placenta. To study materno-to fetal PS transfer we used the human ex vivo placental perfusion approach, which represents an intact and physiological tissue barrier. To analyze the protein corona of PS particles we performed shotgun proteomics of isolated nanoparticles before and after tissue exposure.

Results: Human plasma incubated with PS-particles of 80 nm and subsequent formed protein corona enhanced the transfer across the human placenta compared to PS-corona formed by bovine serum albumin and dextran which served as a control. Quantitative and qualitative changes of plasma proteins determined the changes in PS transfer across the barrier. Based on the analysis of the PS-proteome two candidate proteins, namely human albumin and immunoglobulin G were tested if these proteins may account for the enhanced PS-transfer across the placenta. Interestingly, the protein corona formed by human albumin significantly induced the transfer of PS-particles across the tissue compared to the formed IgG-corona.

Conclusion: In total we demonstrate the PS corona dynamically and significantly evolves upon crossing the human placenta. Thus, the initial composition of PS particles in the maternal circulation is not predictive for their transfer characteristics and performance once beyond the barrier of the placenta. The precise mechanism of these effects remains to be elucidated but highlights the importance of using well designed biological models when testing nanoparticles for biomedical applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12951-020-00676-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7487953PMC
September 2020

Interplay of drug transporters P-glycoprotein (MDR1), MRP1, OATP1A2 and OATP1B3 in passage of maraviroc across human placenta.

Biomed Pharmacother 2020 Sep 12;129:110506. Epub 2020 Jul 12.

Charles University, Faculty of Pharmacy in Hradec Kralove, Department of Pharmacology and Toxicology, Akademika Heyrovskeho 1203, Hradec Kralove, Czech Republic. Electronic address:

Special attention is required when pharmacological treatment is indicated for a pregnant woman. P-glycoprotein (MDR1) is a well-known transporter localized in the maternal blood-facing apical membrane of placental syncytiotrophoblast and is considered to play an important role in protecting the developing fetus. Maraviroc, a MDR1 substrate that is registered for treatment of HIV infection, shows a low toxicity profile, suggesting favorable tolerability also if administered to pregnant women. Nevertheless, there is only poor understanding to date regarding the extent to which it permeates across the placental barrier and what are the transport mechanisms involved. Endeavoring to clarify the passage of maraviroc across placenta, we used in this study the method of closed-circuit perfusion of maraviroc across human placental cotyledon. The data obtained confirmed slight involvement of MDR1, but they also suggest possible interaction with other transport system(s) working in the opposite direction from that of MDR1. Complementary in vitro studies, including cellular experiments on choriocarcinoma BeWo cells as well as transporter-overexpressing MDCKII and A431 cell lines and accumulation in placental fresh villous fragments, revealed maraviroc transport by MRP1, OATP1A2, and OATP1B3 transporters. Based on mRNA expression data in the placental tissue, isolated trophoblasts, and fetal endothelial cells, especially MRP1 and OATP1A2 seem to play a crucial role in cooperatively driving maraviroc into placental tissue. By the example of maraviroc, we show here the important interplay of transporters in placental drug handling and its possibility to overcome the MDR1-mediated efflux.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.biopha.2020.110506DOI Listing
September 2020

Endothelial Sphingolipid De Novo Synthesis Controls Blood Pressure by Regulating Signal Transduction and NO via Ceramide.

Hypertension 2020 05 16;75(5):1279-1288. Epub 2020 Mar 16.

From the Department of Pathology and Laboratory Medicine, Cardiovascular Research Institute, Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY (A.C., L.S., A.G., L.R., I.d.G., D.B., A.D.L.).

Ceramides are sphingolipids that modulate a variety of cellular processes via 2 major mechanisms: functioning as second messengers and regulating membrane biophysical properties, particularly lipid rafts, important signaling platforms. Altered sphingolipid levels have been implicated in many cardiovascular diseases, including hypertension, atherosclerosis, and diabetes mellitus-related conditions; however, molecular mechanisms by which ceramides impact endothelial functions remain poorly understood. In this regard, we generated mice defective of endothelial sphingolipid de novo biosynthesis by deleting the Sptlc2 (long chain subunit 2 of serine palmitoyltransferase)-the first enzyme of the pathway. Our study demonstrated that endothelial sphingolipid de novo production is necessary to regulate (1) signal transduction in response to NO agonists and, mainly via ceramides, (2) resting eNOS (endothelial NO synthase) phosphorylation, and (3) blood pressure homeostasis. Specifically, our findings suggest a prevailing role of C16:0-Cer in preserving vasodilation induced by tyrosine kinase and GPCRs (G-protein coupled receptors), except for Gq-coupled receptors, while C24:0- and C24:1-Cer control flow-induced vasodilation. Replenishing C16:0-Cer in vitro and in vivo reinstates endothelial cell signaling and vascular tone regulation. This study reveals an important role of locally produced ceramides, particularly C16:0-, C24:0-, and C24:1-Cer in vascular and blood pressure homeostasis, and establishes the endothelium as a key source of plasma ceramides. Clinically, specific plasma ceramides ratios are independent predictors of major cardiovascular events. Our data also suggest that plasma ceramides might be indicative of the diseased state of the endothelium.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1161/HYPERTENSIONAHA.119.14507DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7145736PMC
May 2020

Sphingolipid Signature of Human Feto-Placental Vasculature in Preeclampsia.

Int J Mol Sci 2020 Feb 4;21(3). Epub 2020 Feb 4.

Department of Obstetrics and Gynecology, Medical University of Graz, 8036 Graz, Austria.

Bioactive sphingolipids are emerging as key regulators of vascular function and homeostasis. While most of the clinical studies have been devoted to profile circulating sphingolipids in maternal plasma, little is known about the role of the sphingolipid at the feto-placental vasculature, which is in direct contact with the offspring circulation. Our study aims to compare the sphingolipid profile of normal with preeclamptic (PE) placental chorionic arteries and isolated endothelial cells, with the goal of unveiling potential underlying pathomechanisms in the vasculature. Dihydrosphingosine and sphingomyelin (SM) concentrations (C16:0-, C18:0-, and C24:0- sphingomyelin) were significantly increased in chorionic arteries of preeclamptic placentas, whereas total ceramide, although showing a downward trend, were not statistically different. Moreover, RNA and immunofluorescence analysis showed impaired sphingosine-1-phosphate (S1P) synthesis and signaling in PE vessels. Our data reveal that the exposure to a deranged maternal intrauterine environment during PE alters the sphingolipid signature and gene expression on the fetal side of the placental vasculature. This pathological remodeling consists in increased serine palmitoyltransferase (SPT) activity and SM accrual in PE chorionic arteries, with concomitance impairment endothelial S1P signaling in the endothelium of these vessels. The increase of endothelial S1P phosphatase, lyase and S1PR2, and blunted S1PR1 expression support the onset of the pathological phenotype in chorionic arteries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms21031019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037072PMC
February 2020

Neonatal HDL Counteracts Placental Vascular Inflammation via S1P-S1PR1 Axis.

Int J Mol Sci 2020 01 25;21(3). Epub 2020 Jan 25.

Department of Obstetrics and Gynecology, Medical University of Graz, 8036 Graz, Austria.

Placental inflammation and dysfunction during pregnancy are associated with short- and long-term adverse outcomes for the offspring. However, the mechanisms of vascular protection at the feto-placental interface are still poorly investigated. The high-density lipoprotein (HDL) associated sphingosine-1-phosphate (S1P) has been described as a powerful anti-inflammatory complex. This study aimed to elucidate the role of cord blood-derived HDL (nHDL) in feto-placental endothelial dysfunction. Here, we report that the exposure of primary fetal placental arterial endothelial cell (fPAEC) to healthy nHDL-S1P attenuated the ability of TNFα to activate NF-κB signaling and increase the expression of pro-inflammatory markers. Moreover, the angiotensin II (AngII)-induced reactive oxygen species (ROS) production was blunted in the presence of nHDL, whereas it was preserved when the cells were preincubated with S1P receptor antagonists, suggesting that S1P accounts for the vascular protective function of nHDL at the feto-placental unit. These results highlight the importance of HDL and S1P metabolism and signaling in pregnancy pathophysiology.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms21030789DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037016PMC
January 2020

Placental Hofbauer Cell Polarization Resists Inflammatory Cues In Vitro.

Int J Mol Sci 2020 Jan 22;21(3). Epub 2020 Jan 22.

Department of Obstetrics and Gynecology, Research Facility, Medical University of Graz, Graz, Austria.

Feto-placental Hofbauer cells (HBCs) are macrophages residing in placental stroma. They are generally described as anti-inflammatory M2 polarized cells, promoting tolerance and tissue remodeling. In certain pathologies, however, a possible phenotypical switch towards pro-inflammatory M1 macrophages has been proposed. The study aimed to determine if HBCs can acquire an M1 phenotype under pro-inflammatory conditions in vitro. HBCs were isolated from healthy human term placentas. Cells were cultivated upon addition of LPS and INF-γ or IL-4 and IL-13 to induce the M1 and M2 phenotype, respectively. Specific cell polarization markers and cytokines, associated with respective phenotypes, were investigated by flow cytometry and ELISA. THP-1 macrophages served as positive control. Pro-inflammatory stimuli reduced M2 markers CD163 and DC-SIGN, but did not induce M1 markers. TNF-α release was increased, but at the same time TGF-β and IL-10 release was upregulated, resembling in part the M2b sub-phenotype. Anti-inflammatory stimuli had no effect on HBC polarization. HBCs maintain their M2 phenotype in vitro despite inflammatory stimuli, which might represent a state of adaption and tolerance to avoid rejection of the semiallogeneic feto-placental unit.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/ijms21030736DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7038058PMC
January 2020

Circulating cord blood HDL-S1P complex preserves the integrity of the feto-placental vasculature.

Biochim Biophys Acta Mol Cell Biol Lipids 2020 04 15;1865(4):158632. Epub 2020 Jan 15.

Department of Obstetrics and Gynecology, Medical University of Graz, Graz, Austria. Electronic address:

Perinatal and long-term offspring morbidities are strongly dependent on the preservation of placental vascular homeostasis during pregnancy. In adults, the HDL-apoM-S1P complex protects the endothelium and maintains vascular integrity. However, the metabolism and biology of cord blood-derived HDLs (referred to as neonatal HDL, nHDL) strikingly differ from those in adults. Here, we investigate the role of neonatal HDLs in the regulation of placental vascular function. We show that nHDL is a major carrier of sphingosine-1-phosphate (S1P), which is anchored to the particle through apoM (r = 0.90, p < 0.0001) in the fetal circulation. Furthermore, this complex interacts with S1P receptors on the feto-placental endothelium and activates specifically extracellular signal-regulated protein kinases 1 and 2 (ERK) and phospholipase C (PLC) downstream signaling, promotes endothelial cell proliferation and calcium flux. Notably, the nHDL-S1P complex triggers actin filaments reorganization, leading to an enhancement of placental endothelial barrier function. Additionally, nHDL induces vasorelaxation of isolated placental chorionic arteries. Taken together, these results suggest that circulating nHDL exerts vasoprotective effects on the feto-placental endothelial barrier mainly via S1P signaling.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbalip.2020.158632DOI Listing
April 2020

Sexual dimorphism of miRNA signatures in feto-placental endothelial cells is associated with altered barrier function and actin organization.

Clin Sci (Lond) 2020 01;134(1):39-51

Department of Obstetrics and Gynecology, Medical University of Graz, Graz, Austria.

Endothelial function and the risk for endothelial dysfunction differ between males and females. Besides the action of estrogen, sex chromosome gene expression and programming effects also provoke this sexual dimorphism. MicroRNAs (miRNAs) have emerged as regulators of endothelial cell function and dysfunction. We here hypothesized distinct miRNA expression patterns in male versus female human endothelial cells that contribute to the functional differences. We used our well-established model of fetal endothelial cells isolated from placenta (fpEC) and analyzed sexual dimorphic miRNA expression and potentially affected biological functions. Next-generation miRNA sequencing of fpEC isolated after pregnancies with male and female neonates identified sex-dependent miRNA expression patterns. Potential biological pathways regulated by the altered set of miRNAs were determined using mirPath and mirSystem softwares, and suggested differences in barrier function and actin organization. The identified pathways were further investigated by monolayer impedance measurements (ECIS) and analysis of F-actin organization (Phalloidin). Nine miRNAs were differentially expressed in fpEC of male versus female neonates. Functional pathways most significantly regulated by these miRNAs included 'Adherens junction', 'ECM receptor interaction' and 'Focal adhesion'. These pathways control monolayer barrier function and may be paralleled by altered cytoskeletal organization. In fact, monolayer impedance was higher in fpEC of male progeny, and F-actin staining revealed more pronounced peripheral stress fibers in male versus female fpEC. Our data highlight that endothelial cell function differs between males and females already in utero, and that altered miRNAs are associated with sex dependent differences in barrier function and actin organization.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1042/CS20190379DOI Listing
January 2020

Evidence of Human Milk Oligosaccharides in Cord Blood and Maternal-to-Fetal Transport across the Placenta.

Nutrients 2019 Nov 4;11(11). Epub 2019 Nov 4.

Department of Obstetrics and Gynecology, Medical University of Graz, 8036 Graz, Austria.

Human milk oligosaccharides (HMOs) are present in maternal serum in early gestation, raising the question of whether HMOs can cross the placental barrier and reach fetal circulation. Here, we aimed to detect HMOs in cord blood, and assess HMO composition and concentration in relation to maternal HMOs. In an ex-vivo placental perfusion model, we asked whether HMOs can pass over the placenta. Using HPLC, we measured HMOs in maternal serum and matching venous cord blood samples collected at delivery from normal pregnancies ( = 22). To investigate maternal-to-fetal transport, we perfused isolated placental cotyledons from term pregnancies ( = 3) with 2'-fucosyllactose (2'FL) in a double closed setting. We found up to 18 oligosaccharides typically present in maternal serum in all cord serum samples investigated. Median total cord blood HMO concentration did not differ from the concentration in maternal serum. HMO composition resembled the composition in maternal serum, with the strongest correlations for 2'FL and LDFT. After 180 min perfusion, we found 22% of maternally offered 2'FL in the fetal circuit without reaching equilibrium. Our results provide direct evidence of HMOs in cord blood, and suggest that the placenta transfers HMOs from the maternal to fetal circuit. Future studies will investigate potential differences in the transfer of specific HMOs, or in pregnancy disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nu11112640DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893815PMC
November 2019

Endothelial lipase increases antioxidative capacity of high-density lipoprotein.

Biochim Biophys Acta Mol Cell Biol Lipids 2019 10 17;1864(10):1363-1374. Epub 2019 Jun 17.

Otto Loewi Research Center, Division of Physiological Chemistry, Medical University of Graz, Neue Stiftingtalstraße 6/3, 8010 Graz, Austria.

Endothelial lipase (EL) is a strong determinant of structural and functional properties of high-density lipoprotein (HDL). We examined whether the antioxidative capacity of HDL is affected by EL. EL-modified HDL (EL-HDL) and control EV-HDL were generated by incubation of HDL with EL- overexpressing or control HepG2 cells. As determined by native gradient gel electrophoresis, electron microscopy, and small-angle X-ray scattering EL-HDL is smaller than EV-HDL. Mass spectrometry revealed an enrichment of EL-HDL with lipolytic products and depletion of phospholipids and triacylglycerol. Kinetics of conjugated diene formation and HPLC-based malondialdehyde quantification revealed that EL-HDL exhibited a significantly higher resistance to copper ion-induced oxidation and a significantly higher capacity to protect low-density lipoprotein (LDL) from copper ion-induced oxidation when compared to EV-HDL. Depletion of the lipolytic products from EL-HDL abolished the capacity of EL-HDL to protect LDL from copper ion-induced oxidation, which could be partially restored by lysophosphatidylcholine enrichment. Proteomics of HDL incubated with oxidized LDL revealed significantly higher levels of methionine 136 sulfoxide in EL-HDL compared to EV-HDL. Chloramine T (oxidizes methionines and modifies free thiols), diminished the difference between EL-HDL and EV-HDL regarding the capacity to protect LDL from oxidation. In absence of LDL small EV-HDL and EL-HDL exhibited higher resistance to copper ion-induced oxidation when compared to respective large particles. In conclusion, the augmented antioxidative capacity of EL-HDL is primarily determined by the enrichment of HDL with EL-generated lipolytic products and to a lesser extent by the decreased HDL particle size and the increased activity of chloramine T-sensitive mechanisms.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbalip.2019.06.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6699986PMC
October 2019

Expression of the neonatal Fc-receptor in placental-fetal endothelium and in cells of the placental immune system.

Placenta 2019 03 28;78:36-43. Epub 2019 Feb 28.

Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria. Electronic address:

Introduction: Starting from the second trimester of pregnancy, passive immunity is provided to the human fetus by transplacental transfer of maternal IgG. IgG transfer depends on the neonatal Fc receptor, FcRn. While FcRn localization in the placental syncytiotrophoblast (STB) has been demonstrated unequivocally, FcRn expression in placental-fetal endothelial cells (pFECs), which are part of the materno-fetal barrier, is still unclear. Therefore, this study aimed to elucidate the spatio-specific expression pattern of FcRn in placental tissue.

Methods: FcRn expression was investigated by western blotting in term placentas and in isolated human placental arterial and venous endothelial cells (HPAEC, HPVEC) using a validated affinity-purified polyclonal anti-peptide antibody against the cytoplasmic tail of FcRn α-chain. In situ localization of FcRn and IgG was studied by immunofluorescence microscopy on tissue sections of healthy term placentas.

Results: FcRn expression was demonstrated in placental vasculature particularly, in HPAEC, and HPVEC. FcRn was localized in cytokeratin 7 STB and in CD31 pFECs in terminal as well as stem villi in situ. Additionally, CD68 placental macrophages exhibited FcRn expression in situ. Endogenous IgG partially co-localized with FcRn in STB, pFECs, and in placental macrophages.

Discussion: Placental FcRn expression in endothelial cells and macrophages is analogous to the expression pattern in other organs. FcRn expression in pFECs suggests an involvement of FcRn in IgG transcytosis and/or participation in recycling/salvaging of maternal IgG present in the fetal circulation. FcRn expression in placental macrophages may account for recycling of monomeric IgG and/or processing and presentation of immune complexes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.placenta.2019.02.012DOI Listing
March 2019

High density lipoprotein cholesterol and proteome in SR-B1 KO mice: lost in precipitation.

J Transl Med 2018 11 12;16(1):309. Epub 2018 Nov 12.

Department of Nutrition, Diabetes and Metabolism, Pontificia Universidad Católica de Chile, Santiago, Chile.

Scavenger receptor class B type 1 (SR-B1) plays an essential role in high density lipoprotein (HDL) metabolism. SR-B1 deficient (SR-B1 KO) mice are prone to atherosclerosis and exhibit abnormally large, cholesterol-rich, dysfunctional HDL. In a recent issue of J Transl Med, Cao et al. described results of proteomics analyses of HDL isolated from wild-type (WT) and SR-B1 KO mice using precipitation of large lipoproteins with polyethylene glycol (PEG). They report abnormalities in SR-B1 KO HDL protein components that correlate with HDL function. In this commentary, we describe and discuss the differences in the results published by Cao et al. and those obtained in a recent study from our laboratory using shotgun proteomics of HDL of SR-B1 KO mice isolated by ultracentrifugation. We propose that different HDL purification procedures used may account for the discrepancies observed. We show that SR-B1 KO HDL purification using either PEG or dextran sulfate precipitation results in enrichment of small HDL subclasses, and may therefore underestimate alterations in lipoprotein composition or function. Compared to HDL obtained by ultracentrifugation, HDL isolated by PEG precipitation show a lower ApoE/ApoA-I proportion and reduced cholesterol content. HDL protein components described by Cao et al. or our laboratory are mostly inconsistent: only 33 HDL proteins were detected in both datasets, whereas a significant number of proteins were only identified by Cao et al. (n = 43) or Contreras-Duarte et al. (n = 26) datasets. The relative abundance of HDL-associated peptide and protein levels in WT vs SR-B1 HDL were also highly different in both datasets. This study indicates that caution must be taken when interpreting results from HDL isolated by chemical precipitation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12967-018-1683-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6233513PMC
November 2018

Pharmacological Inhibition of Serine Palmitoyl Transferase and Sphingosine Kinase-1/-2 Inhibits Merkel Cell Carcinoma Cell Proliferation.

J Invest Dermatol 2019 04 3;139(4):807-817. Epub 2018 Nov 3.

Gottfried Schatz Research Center, Division of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria; Center for Explorative Lipidomics, BioTechMed-Graz, Graz, Austria. Electronic address:

The majority of Merkel cell carcinoma, a highly aggressive neuroendocrine cancer of the skin, is associated with Merkel cell polyomavirus infection. Polyomavirus binding, internalization, and infection are mediated by glycosphingolipids. Besides receptor function, bioactive sphingolipids are increasingly recognized as potent regulators of several hallmarks of cancer. Merkel cell polyomavirus and Merkel cell polyomavirus cells express serine palmitoyl transferase subunits and sphingosine kinase (SK) 1/2 mRNA. Induced expression of Merkel cell polyomavirus-large tumor antigen in human lung fibroblasts resulted in upregulation of SPTLC1-3 and SK 1/2 expression. Therefore, we exploited pharmacological inhibition of sphingolipid metabolism as an option to interfere with proliferation of Merkel cell polyomavirus Merkel cell carcinoma cell lines. We used myriocin (a serine palmitoyl transferase antagonist) and two SK inhibitors (SKI-II and ABC294640). In MKL-1 and WaGa cells myriocin decreased cellular ceramide, sphingomyelin, and sphingosine-1-phosphate content. SKI-II increased ceramide species but decreased sphingomyelin and sphingosine-1-phosphate concentrations. Aberrant sphingolipid homeostasis was associated with reduced cell viability, increased necrosis, procaspase-3 and PARP processing, caspase-3 activity, and decreased AKT phosphorylation. Myriocin and SKI-II decreased tumor size and Ki-67 staining of xenografted MKL-1 and WaGa tumors on the chorioallantoic membrane. Our data suggest that pharmacological inhibition of sphingolipid synthesis could represent a potential therapeutic approach in Merkel cell carcinoma.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jid.2018.10.024DOI Listing
April 2019

BMI-Independent Effects of Gestational Diabetes on Human Placenta.

J Clin Endocrinol Metab 2018 09;103(9):3299-3309

Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Zentrum München at Eberhard Karls University Tübingen, Tübingen, Germany.

Purpose: Recently, alterations in maternal lipid metabolism were associated with gestational diabetes mellitus (GDM). However, detailed plasma lipid profiles and their relevance for placental and fetal metabolism are currently not understood.

Methods: Maternal and placental lipid profiles were characterized in women with GDM and women with normal glucose tolerance (NGT). Inflammatory gene expression was compared in placentas and primary term trophoblasts between the groups. In addition, trophoblasts were stimulated with nonesterified fatty acids (NEFAs), and effects on gene expression were quantified. Finally, placental macrophage content and cord blood concentrations of inflammatory parameters and NEFAs were compared between women with GDM and women with NGT with similar body mass index (BMI).

Results: Palmitate and stearate levels were elevated in both maternal plasma and placental tissue of women with GDM. Placental GDM-associated elevations of IL6, IL8, and TLR2 expression were reflected in trophoblasts derived from women with GDM. Stimulation of primary trophoblasts with palmitate led to increased mRNA expression and protein release of the cytokine IL6 and the chemokine IL8. In line with this, elevated amounts of CD68-positive cells were quantified in the placental tissue of women with GDM. No GDM-associated elevations in a range of inflammatory parameters and NEFAs in cord blood of NGT vs GDM neonates was found.

Conclusions: GDM, independently of BMI, altered maternal plasma NEFAs and the placental lipid profile. GDM was associated with trophoblast and whole-placenta lipoinflammation; however, this was not accompanied by elevated concentrations of inflammatory cytokines or NEFAs in neonatal cord blood.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1210/jc.2018-00397DOI Listing
September 2018

Relation of placental alkaline phosphatase expression in human term placenta with maternal and offspring fat mass.

Int J Obes (Lond) 2018 06 13;42(6):1202-1210. Epub 2018 Jun 13.

Faculty of Medicine, University of Southampton, Southampton, UK.

Introduction: Alkaline phosphatase is implicated in intestinal lipid transport and in the development of obesity. Placental alkaline phosphatase is localised to the microvillous plasma membrane of the placental syncytiotrophoblast at the maternal-fetal interface, but its role is unclear. We investigated the relations of placental alkaline phosphatase activity and mRNA expression with maternal body composition and offspring fat mass in humans.

Methods: Term human placentas from the UK Birthright cohort (n = 52) and the Southampton Women's Survey (SWS) (n = 95) were studied. In the Birthright cohort, alkaline phosphatase activity was measured in placental microvillous plasma membrane vesicles. In the SWS, alkaline phosphatase mRNA was measured using Nanostring. Alkaline phosphatase gene expression was compared to other lipid-related genes.

Results: In Birthright samples placental microvillous plasma membrane alkaline phosphatase activity was positively associated with maternal triceps skinfold thickness and BMI (β = 0.04 (95% CI: 0.01-0.06) and β = 0.02 (0.00-0.03) µmol/mg protein/min per SD, P = 0.002 and P = 0.05, respectively) after adjusting for potential confounders. In SWS samples placental alkaline phosphatase mRNA expression in term placenta was positively associated with maternal triceps skinfold (β = 0.24 (0.04, 0.44) SD/SD, P = 0.02), had no association with neonatal %fat mass (β = 0.01 (-0.20 to 0.21) SD/SD, P = 0.93) and was negatively correlated with %fat mass at ages 4 (β = -0.28 (-0.52 to -0.04) SD/SD, P = 0.02), 6-7 (β = -0.25 (-0.49 to -0.02) SD/SD, P = 0.03) years. When compared with placental expression of other genes, alkaline phosphatase expression was positively related to genes including the lysophosphatidylcholine transporter MFSD2A (major facilitator superfamily domain containing 2A, P < 0.001) and negatively related to genes including the fatty acid transport proteins 2 and 3 (P = 0.001, P < 0.001).

Conclusions: Our findings suggest relationships between placental alkaline phosphatase and both maternal and childhood adiposity. The inverse relationship between placental alkaline phosphatase gene expression and childhood %fat mass suggests that placental alkaline phosphatase may help to protect the foetus from the adverse effects of maternal obesity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41366-018-0136-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6173293PMC
June 2018

Gestational diabetes mellitus modulates cholesterol homeostasis in human fetoplacental endothelium.

Biochim Biophys Acta Mol Cell Biol Lipids 2018 09 18;1863(9):968-979. Epub 2018 May 18.

Immunology and Pathophysiology, Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Medical University of Graz, Austria. Electronic address:

Gestational diabetes mellitus (GDM) is associated with excessive oxidative stress which may affect placental vascular function. Cholesterol homeostasis is crucial for maintaining fetoplacental endothelial function. We aimed to investigate whether and how GDM affects cholesterol metabolism in human fetoplacental endothelial cells (HPEC). HPEC were isolated from fetal term placental arterial vessels of GDM or control subjects. Cellular reactive oxygen species (ROS) were detected by HDCFDA fluorescent dye. Oxysterols were quantified by gas chromatography-mass spectrometry analysis. Genes and proteins involved in cholesterol homeostasis were detected by real-time PCR and immunoblotting, respectively. Cholesterol efflux was determined from [H]-cholesterol labeled HPEC and [C]-acetate was used as cholesterol precursor to measure cholesterol biosynthesis and esterification. We detected enhanced formation of ROS and of specific, ROS-derived oxysterols in HPEC isolated from GDM versus control pregnancies. ROS-generated oxysterols were simultaneously elevated in cord blood of GDM neonates. Liver-X receptor activation in control HPEC by synthetic agonist TO901319, 7-ketocholesterol, or 7β-hydroxycholesterol upregulated ATP-binding cassette transporters (ABC)A1 and ABCG1 expression, accompanied by increased cellular cholesterol efflux. Upregulation of ABCA1 and ABCG1 and increased cholesterol release to apoA-I and HDL (78 ± 17%, 40 ± 9%, respectively) were also observed in GDM versus control HPEC. The LXR antagonist GGPP reversed ABCA1 and ABCG1 upregulation and reduced the increased cholesterol efflux in GDM HPEC. Similar total cellular cholesterol levels were detected in control and GDM HPEC, while GDM enhanced cholesterol biosynthesis along with upregulated 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and sterol O-acyltransferase 1 (SOAT1) mRNA and protein levels. Our results suggest that in GDM cellular cholesterol homeostasis in the fetoplacental endothelium is modulated via LXR activation and helps to maintain its proper functionality.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbalip.2018.05.005DOI Listing
September 2018

Endothelial indoleamine 2,3-dioxygenase-1 regulates the placental vascular tone and is deficient in intrauterine growth restriction and pre-eclampsia.

Sci Rep 2018 04 3;8(1):5488. Epub 2018 Apr 3.

Gottfried Schatz Research Centre for Cell Signalling, Metabolism and Ageing, Department of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, 8010, Austria.

Indoleamine 2,3-dioxygenase-1 (IDO1) mediates the degradation of L-tryptophan (L-Trp) and is constitutively expressed in the chorionic vascular endothelium of the human placenta with highest levels in the microvasculature. Given that endothelial expression of IDO1 has been shown to regulate vascular tone and blood pressure in mice under the condition of systemic inflammation, we asked whether IDO1 is also involved in the regulation of placental blood flow and if yes, whether this function is potentially impaired in intrauterine growth restriction (IUGR) and pre-eclampsia (PE). In the large arteries of the chorionic plate L-Trp induced relaxation only after upregulation of IDO1 using interferon gamma and tumor necrosis factor alpha. However, ex vivo placental perfusion of pre-constricted cotyledonic vasculature with L-Trp decreases the vessel back pressure without prior IDO1 induction. Further to this finding, IDO1 protein expression and activity is reduced in IUGR and PE when compared to gestational age-matched control tissue. These data suggest that L-Trp catabolism plays a role in the regulation of placental vascular tone, a finding which is potentially linked to placental and fetal growth. In this context our data suggest that IDO1 deficiency is related to the pathogenesis of IUGR and PE.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-018-23896-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5883010PMC
April 2018

Placental fatty acid transfer.

Curr Opin Clin Nutr Metab Care 2018 03;21(2):78-82

BioTechMed-Graz, Graz, Austria.

Purpose Of Review: This review outlines recent advances in placental lipid transport in relation to maternal metabolic status and pregnancy outcome. A particular focus of this review will be on the way these findings may influence our understanding of placental transfer of the essential fatty acid docosahexaenoic acid (DHA) which is crucial for fetal neurodevelopment and of lipid transfer as a predisposing factor for childhood obesity.

Recent Findings: Placental metabolism may determine the quantity and composition of fatty acids delivered to the fetus. Maternal factors, such as obesity, appear to regulate placental lipid metabolism and may influence fatty acids delivery to the fetus. Although the role of placental metabolism is now recognized, new evidence also suggests important roles for nontraditional fatty acid transporters such as Mfsd2a which facilitates transfer of DHA.

Summary: Placental lipid metabolism is likely to be a determinant of placental transfer of fatty acids to the fetus. Maternal conditions, such as obesity, have now been shown to regulate placental lipid metabolism and thus may influence fatty acid transfer and fetal development. However, it is not yet clear how regulation of placental lipid metabolism affects fatty acid delivery to the fetus and its long-term health.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1097/MCO.0000000000000443DOI Listing
March 2018

Maternal Gestational Diabetes Mellitus increases placental and foetal lipoprotein-associated Phospholipase A2 which might exert protective functions against oxidative stress.

Sci Rep 2017 10 3;7(1):12628. Epub 2017 Oct 3.

Department of Obstetrics and Gynaecology, Medical University of Graz, Graz, Austria.

Increased Lipoprotein associated phospholipase A (LpPLA) has been associated with inflammatory pathologies, including Type 2 Diabetes. Studies on LpPLA and Gestational Diabetes Mellitus (GDM) are rare, and have focused mostly on maternal outcome. In the present study, we investigated whether LpPLA activity on foetal lipoproteins is altered by maternal GDM and/or obesity (a major risk factor for GDM), thereby contributing to changes in lipoprotein functionality. We identified HDL as the major carrier of LpPLA activity in the foetus, which is in contrast to adults. We observed marked expression of LpPLA in placental macrophages (Hofbauer cells; HBCs) and found that LpPLA activity in these cells was increased by insulin, leptin, and pro-inflammatory cytokines. These regulators were also increased in plasma of children born from GDM pregnancies. Our results suggest that insulin, leptin, and pro-inflammatory cytokines are positive regulators of LpPLA activity in the foeto-placental unit. Of particular interest, functional assays using a specific LpPLA inhibitor suggest that high-density lipoprotein (HDL)-associated LpPLA exerts anti-oxidative, athero-protective functions on placental endothelium and foetus. Our results therefore raise the possibility that foetal HDL-associated LpPLA might act as an anti-inflammatory enzyme improving vascular barrier function.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-017-13051-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5626711PMC
October 2017

Human Placental Hofbauer Cells Maintain an Anti-inflammatory M2 Phenotype despite the Presence of Gestational Diabetes Mellitus.

Front Immunol 2017 31;8:888. Epub 2017 Jul 31.

Perinatal Research Laboratory, Department of Obstetrics and Gynecology, Medical University of Graz, Graz, Austria.

Background: Hofbauer cells (HBCs) are macrophages of the feto-placental unit. Despite the general view that these cells have an anti-inflammatory M2 phenotype, recent studies have claimed that pregnancy pathologies-e.g., gestational diabetes mellitus (GDM)-cause a switch from an M2 to an M1 pro-inflammatory phenotype in HBCs. The pilot-study presented here challenges this claim, showing that HBCs maintain anti-inflammatory properties in spite of the hyperglycemic, low-grade inflammatory environment of GDM.

Methods: HBCs were isolated from placentae of healthy women ( = 5) and women with GDM ( = 6) diagnosed in the second trimester. FACS was used to measure surface markers associated with either M1 or M2 phenotype on the cells. In addition, placental tissue sections were subjected to immune histochemical imaging to assess the phenotype within the tissue context. Supernatant from control and GDM HBCs was collected at defined time points and used in a multiplex ELISA-on-beads approach to assess secretion of cytokines, chemokines, and growth factors. The effect of HBC cell culture supernatant on placental endothelial activation was investigated.

Results: FACS and immune staining showed that, indeed, M2 markers, such as CD206 and CD209, are increased in HBCs isolated from GDM placentae. Also, the M1 marker CD86 was increased, but only by trend. Secretion of numerous cytokines, chemokines and growth factors was not changed; pro-inflammatory interleukin (IL)-1β and IL-6 release form GDM HBC was increased but not significant. Exposure to GDM HBC supernatant did not induce cell adhesion molecules (VCAM-1, selectins, vascular endothelial-cadherin) in placental endothelial cells compared to supernatant from control HBCs, an induction of intracellular adhesion molecule 1 was observed however.

Conclusion: Our study-although performed in a small set of patients-shows that placental macrophages maintain their anti-inflammatory, tissue remodeling M2 phenotype even in pregnancies affected by gestational diabetes. This consistent phenotype might be important for propagation of maternal tolerance toward the fetus and for protection of the fetus from a low-grade inflammatory environment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fimmu.2017.00888DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5534476PMC
July 2017

The influence of placental metabolism on fatty acid transfer to the fetus.

J Lipid Res 2017 02 2;58(2):443-454. Epub 2016 Dec 2.

Faculty of Engineering and Environment, University of Southampton, SO17 1BJ, UK

The factors determining fatty acid transfer across the placenta are not fully understood. This study used a combined experimental and computational modeling approach to explore placental transfer of nonesterified fatty acids and identify the rate-determining processes. Isolated perfused human placenta was used to study the uptake and transfer of C-fatty acids and the release of endogenous fatty acids. Only 6.2 ± 0.8% of the maternal C-fatty acids taken up by the placenta was delivered to the fetal circulation. Of the unlabeled fatty acids released from endogenous lipid pools, 78 ± 5% was recovered in the maternal circulation and 22 ± 5% in the fetal circulation. Computational modeling indicated that fatty acid metabolism was necessary to explain the discrepancy between uptake and delivery of C-fatty acids. Without metabolism, the model overpredicts the fetal delivery of C-fatty acids 15-fold. Metabolic rate was predicted to be the main determinant of uptake from the maternal circulation. The microvillous membrane had a greater fatty acid transport capacity than the basal membrane. This study suggests that incorporation of fatty acids into placental lipid pools may modulate their transfer to the fetus. Future work needs to focus on the factors regulating fatty acid incorporation into lipid pools.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1194/jlr.P072355DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5282960PMC
February 2017

Going into labor and beyond: phospholipase A2 in pregnancy.

Reproduction 2016 06 23;151(6):R91-R102. Epub 2016 Feb 23.

Department of Obstetrics and GynecologyMedical University of Graz, Graz, Austria

The phospholipase A2 (PLA2) family is a very diverse group of enzymes, all serving in the cleavage of phospholipids, thereby releasing high amounts of arachidonic acid (AA) and lysophospholipids. AA serves as a substrate for prostaglandin production, which is of special importance in pregnancy for the onset of parturition. Novel research demonstrates that PLA2 action affects the immune response of the mother toward the child and is therefore probably implied in the tolerance of the fetus and prevention of miscarriage. This review presents data on the biochemical and enzymatic properties of PLA2 during gestation with a special emphasis on its role for the placental function and development of the fetus. We also critically discuss the possible pathophysiological significance of PLA2 alterations and its possible functional consequences. These alterations are often associated with pregnancy pathologies such as preeclampsia and villitis or pregnancy complications such as obesity and diabetes in the mother as well as preterm onset of labor.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1530/REP-15-0519DOI Listing
June 2016

Interference with distinct steps of sphingolipid synthesis and signaling attenuates proliferation of U87MG glioma cells.

Biochem Pharmacol 2015 Jul 19;96(2):119-30. Epub 2015 May 19.

Institute of Molecular Biology and Biochemistry, Medical University of Graz, Austria; BioTechMed Graz, Austria. Electronic address:

Glioblastoma is the most common malignant brain tumor, which, despite combined radio- and chemotherapy, recurs and is invariably fatal for affected patients. Members of the sphingolipid (SL) family are potent effectors of glioma cell proliferation. In particular sphingosine-1-phosphate (S1P) and the corresponding G protein-coupled S1P receptors transmit proliferative signals to glioma cells. To investigate the contribution to glioma cell proliferation we inhibited the first step of de novo SL synthesis in p53(wt) and p53(mut) glioma cells, and interfered with S1P signaling specifically in p53(wt) U87MG cells. Subunit silencing (RNAi) or pharmacological antagonism (using myriocin) of serine palmitoyltransferase (SPT; catalyzing the first committed step of SL biosynthesis) reduced proliferation of p53(wt) but not p53(mut) GBM cells. In U87MG cells these observations were accompanied by decreased ceramide, sphingomyelin, and S1P content. Inhibition of SPT upregulated p53 and p21 expression and induced an increase in early and late apoptotic U87MG cells. Exogenously added S1P (complexed to physiological carriers) increased U87MG proliferation. In line, silencing of individual members of the S1P receptor family decreased U87MG proliferation. Silencing and pharmacological inhibition of the ATP-dependent cassette transporter A1 (ABCA1) that facilitates S1P efflux in astrocytes attenuated U87MG growth. Glyburide-mediated inhibition of ABCA1 resulted in intracellular accumulation of S1P raising the possibility that ABCA1 promotes S1P efflux in U87MG glioma cells thereby contributing to inside-out signaling. Our findings indicate that de novo SL synthesis, S1P receptor-mediated signaling, and ABCA1-mediated S1P efflux could provide pharmacological targets to interfere with glioma cell proliferation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bcp.2015.05.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4490581PMC
July 2015