Human embryonic implantation involves major invasion of the uterine wall and remodeling of the uterine arteries by extravillous cytotrophoblast cells (EVCT). Abnormalities in these early steps of ...placental development lead to poor placentation and fetal growth defects and are frequently associated with preeclampsia, a major complication of human pregnancy. We recently showed that oxidized low-density lipoproteins (oxLDLs) are present in situ in EVCT and inhibit cell invasion in a concentration-dependent manner. The aim of the present study was to better understand the mechanisms by which oxLDL modulate trophoblast invasion. We therefore investigated the presence of oxLDL receptors in our cell culture model of human invasive primary EVCT. We found using immunocytochemistry and immunoblotting that the lectin-like oxLDL receptor-1 was the scavenger receptor mainly expressed in EVCT and was probably involved in oxLDL uptake. We next examined the effect of low-density lipoprotein oxidative state on trophoblast invasion in vitro using EVCT cultured on Matrigel-coated Transwell. We demonstrated that only oxLDL containing a high proportion of oxysterols and phosphatidylcholine hydroperoxide derivatives that provide ligands for liver X receptor (LXR) and peroxisomal proliferator-activated receptor γ (PPARγ), respectively, reduced trophoblast invasion. We next investigated the presence and the role of these nuclear receptors and found that in addition to PPARγ, human invasive trophoblasts express LXRβ, and activation of these nuclear receptors by specific synthetic or natural ligands inhibited trophoblast invasion. Finally, using a PPARγ antagonist, we suggest that LXRβ, rather than PPARγ, is involved in oxLDL-mediated inhibition of human trophoblast invasion in vitro.
Human implantation involves a major invasion of the uterine wall and remodeling of the uterine arteries by trophoblastic cells. Abnormalities in these early steps of placental development lead to ...poor placentation, fetal growth defects and are frequently associated with pre-eclampsia, a serious disease specific to human pregnancy. Lipid metabolism is altered during human pregnancy, with low-density lipoproteins (LDL) becoming more susceptible to oxidation. The aim of this study was to localize oxidized LDL (oxLDL) at the implantation site and to investigate the role of oxLDL in human trophoblast invasion in vitro. We showed by immunohistochemistry that oxLDL was present in cytotrophoblasts of villous and extravillous origin in sections of first trimester human placenta. We purified primary invasive extravillous cytotrophoblasts isolated from the chorionic villi of human first trimester placenta and cultured them on Matrigel-coated transwells. We demonstrated using this invasion assay that oxLDL, but not native LDL, inhibited cell invasion in a concentration-dependent manner. These results suggest that human trophoblast invasion may be modulated by oxLDL in vivo and provide new insights into the pathophysiology of pre-eclampsia associated with oxidative stress and defective trophoblast invasion.
Invasive cytotrophoblasts play a key role in the development of human placenta and is therefore essential for subsequent development of the embryo. Human implantation is characterized by a major ...trophoblastic invasion that offers a unique model of a controlled and oriented tumor-like process. The ligand-activated nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) modulates cell growth and differentiation and might be therefore considered as a tumor suppressor. We have recently reported that PPARγ, in synergy with its dimerization partner retinoid X receptor (RXR)α, controls the invasion of human primary cytotrophoblasts. Because these cells are unable to replicate in culture, we have, in the present study, transformed these primary cells with the simian virus 40 large T antigen for studying the role of PPARγ in cell invasion process. Our results show that the cell line human invasive proliferative extravillous cytotrophoblast (HIPEC) 65 expressed markers of human invasive primary cytotrophoblast as determined by immunocytochemistry, immunobloting and real-time RT–PCR, and were highly invasive in vitro. We have next studied the role of PPARγ/RXRα heterodimers in cell proliferation and invasion. Our results show that PPARγ and RXRα are co-expressed by HIPEC 65 and that, as commonly observed, activation of PPARγ/RXRα heterodimers with the specific PPARγ agonist rosiglitazone induced lipid droplet accumulation as revealed by oil red O staining. Treatment with rosiglitazone or with the natural PPARγ agonist 15-deoxy-δ-(12,14) PGJ2 did not modify cell growth, but interestingly, activation of PPARγ by this synthetic (rosiglitazone) or natural (15d-PGJ2) ligand markedly inhibited cell invasion in a concentration-dependent manner. Finally, we showed that other potential natural PPARγ ligand such as oxidized—but not native—low-density lipoprotein inhibited cell invasion. This proliferative and invasive human cytotrophoblast cell line from extravillous origin provides a new tool for studying specifically the role of PPARγ in the control of cell invasion.
Invasive cytotrophoblasts play a key role in the development of human placenta and is therefore essential for subsequent development of the embryo. Human implantation is characterized by a major ...trophoblastic invasion that offers a unique model of a controlled and oriented tumor-like process. The ligand-activated nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) modulates cell growth and differentiation and might be therefore considered as a tumor suppressor. We have recently reported that PPARgamma, in synergy with its dimerization partner retinoid X receptor (RXR)alpha, controls the invasion of human primary cytotrophoblasts. Because these cells are unable to replicate in culture, we have, in the present study, transformed these primary cells with the simian virus 40 large T antigen for studying the role of PPARgamma in cell invasion process. Our results show that the cell line human invasive proliferative extravillous cytotrophoblast (HIPEC) 65 expressed markers of human invasive primary cytotrophoblast as determined by immunocytochemistry, immunobloting and real-time RT-PCR, and were highly invasive in vitro. We have next studied the role of PPARgamma/RXRalpha heterodimers in cell proliferation and invasion. Our results show that PPARgamma and RXRalpha are co-expressed by HIPEC 65 and that, as commonly observed, activation of PPARgamma/RXRalpha heterodimers with the specific PPARgamma agonist rosiglitazone induced lipid droplet accumulation as revealed by oil red O staining. Treatment with rosiglitazone or with the natural PPARgamma agonist 15-deoxy-delta-(12,14) PGJ<2< did not modify cell growth, but interestingly, activation of PPARgamma by this synthetic (rosiglitazone) or natural (15d-PGJ<2<) ligand markedly inhibited cell invasion in a concentration-dependent manner. Finally, we showed that other potential natural PPARgamma ligand such as oxidized--but not native--low-density lipoprotein inhibited cell invasion. This proliferative and invasive human cytotrophoblast cell line from extravillous origin provides a new tool for studying specifically the role of PPARgamma in the control of cell invasion.
Knowledge on the myeloproliferative neoplasms (MPNs) – polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF) – has accumulated since the discovery of the ...JAK/STAT-activating mutations associated with MPNs:
JAK2
V617F, observed in PV, ET and PMF; and the
MPL
and
CALR
mutations, found in ET and PMF. The intriguing lack of disease specificity of these mutations, and of the chronic inflammation associated with MPNs, triggered a quest for finding what precisely determines that MPN patients develop a PV, ET or PMF phenoptype. The mechanisms of action of MPN-driving mutations, and concomitant mutations (
ASXL1, DNMT3A, TET2
, others), have been extensively studied, as well as the role played by these mutations in inflammation, and several pathogenic models have been proposed. In parallel, different types of drugs have been tested in MPNs (JAK inhibitors, interferons, hydroxyurea, anagrelide, azacytidine, combinations of those), some acting on both JAK2 and inflammation. Yet MPNs remain incurable diseases. This review aims to present current, detailed knowledge on the pathogenic mechanisms specifically associated with PV, ET or PMF that may pave the way for the development of novel, curative therapies.
Knowledge on the myeloproliferative neoplasms (MPNs) - polycythemia vera (PV), essential thrombocythemia (ET), primary myelofibrosis (PMF) - has accumulated since the discovery of the ...JAK/STAT-activating mutations associated with MPNs:
V617F, observed in PV, ET and PMF; and the
and
mutations, found in ET and PMF. The intriguing lack of disease specificity of these mutations, and of the chronic inflammation associated with MPNs, triggered a quest for finding what precisely determines that MPN patients develop a PV, ET or PMF phenoptype. The mechanisms of action of MPN-driving mutations, and concomitant mutations (
, others), have been extensively studied, as well as the role played by these mutations in inflammation, and several pathogenic models have been proposed. In parallel, different types of drugs have been tested in MPNs (JAK inhibitors, interferons, hydroxyurea, anagrelide, azacytidine, combinations of those), some acting on both JAK2 and inflammation. Yet MPNs remain incurable diseases. This review aims to present current, detailed knowledge on the pathogenic mechanisms specifically associated with PV, ET or PMF that may pave the way for the development of novel, curative therapies.
Myeloproliferative neoplasms (MPNs) are a heterogeneous group of clonal diseases characterized by the excessive and chronic production of mature cells from one or several of the myeloid lineages. ...Recent advances in the biology of MPNs have greatly facilitated their molecular diagnosis since most patients present with mutation(s) in the JAK2, MPL, or CALR genes. Yet the roles played by these mutations in the pathogenesis and main complications of the different subtypes of MPNs are not fully elucidated. Importantly, chronic inflammation has long been associated with MPN disease and some of the symptoms and complications can be linked to inflammation. Moreover, the JAK inhibitor clinical trials showed that the reduction of symptoms linked to inflammation was beneficial to patients even in the absence of significant decrease in the JAK2-V617F mutant load. These observations suggested that part of the inflammation observed in patients with JAK2-mutated MPNs may not be the consequence of JAK2 mutation. The aim of this paper is to review the different aspects of inflammation in MPNs, the molecular mechanisms involved, the role of specific genetic defects, and the evidence that increased production of certain cytokines depends or not on MPN-associated mutations, and to discuss possible nongenetic causes of inflammation.
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