Maternal one carbon metabolism through increased oxidative stress and disturbed angiogenesis can influence placental apoptosis in preeclampsia

Accepted Manuscript Maternal one carbon metabolism through increased oxidative stress and disturbed angiogenesis can influence placental apoptosis in preeclampsia

Vaishali V. Kasture, Deepali P. Sundrani, Sadhana R. Joshi PII: DOI: Reference:

S0024-3205(18)30291-1 doi:10.1016/j.lfs.2018.05.029 LFS 15723

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ACCEPTED MANUSCRIPT Maternal one carbon metabolism through increased oxidative stress and disturbed angiogenesis can influence placental apoptosis in preeclampsia Vaishali V. Kasture, Deepali P. Sundrani, Sadhana R. Joshi* Department of Mother and Child Health, Interactive Research School for Health Affairs (IRSHA), Bharati

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Vidyapeeth (Deemed to be University), Pune, India

* Corresponding author: Dr. Sadhana Joshi,

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Professor and Head Department of Mother and Child Health,

Interactive Research School for Health Affairs (IRSHA),

Pune-Satara Road, Pune 411043, India

E-mail: [email protected]

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ORCID-0000-0003-0551-7183

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Tel: (020) 24366920

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Bharati Vidyapeeth (Deemed to be University), Pune

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ACCEPTED MANUSCRIPT ABSTRACT

Adequate maternal nutrition is critical for a healthy pregnancy outcome and poor maternal nutrition is known to be associated with pregnancy complications like preeclampsia. We have earlier demonstrated that there is an imbalance in the levels of micronutrients (folate and vitamin B 12) along with low levels of long chain polyunsaturated fatty acids (LCPUFA) and high homocysteine levels in women with preeclampsia.

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Homocysteine is known to be involved in the formation of free radicals leading to increased oxidative stress. Higher oxidative stress has been shown to be associated with increased apoptotic markers in the placenta.

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Preeclampsia is of placental origin and is associated with increased oxidative stress, disturbed angiogenesis and placental apoptosis. The process of angiogenesis is important for placental and fetal development and various

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angiogenic growth factors inhibit apoptosis by inactivation of proapoptotic proteins through a series of cellular signalling pathways. We propose that an altered one carbon cycle resulting in increased oxidative stress and

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impaired angiogenesis will contribute to increased placental apoptosis leading to preeclampsia. Understanding the association of one carbon cycle components and the possible mechanisms through which they regulate

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apoptosis will provide clues for reducing risk of pregnancy complications.

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Keywords- Apoptosis, Angiogenesis, Homocysteine, Preeclampsia, One carbon metabolism, Oxidative stress

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ACCEPTED MANUSCRIPT INTRODUCTION The nutritional status of the woman (both prior to conception and during pregnancy) is known to influence pregnancy outcome. Inadequate supplies of nutrients during these periods induce differential adaptations in the development of essential tissues and downregulate fetal growth [1]. These changes can provide immediate survival for the fetus, but may have long term effects and can increase the risk for obesity, type-2 diabetes and cardiovascular diseases in the offspring [2].

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Epidemiological and biological evidence suggest that maternal nutritional deficiency can contribute to pregnancy complications such as preeclampsia [3, 4]. Preeclampsia, a pregnancy related complication is a major

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cause of maternal morbidity, accounts for 14% of maternal deaths and 15% of preterm births [5]. The precise

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origin of preeclampsia remains unclear but the placenta is suggested to be an important component in the pathogenesis of preeclampsia. Two interrelated events viz. placental hypoxia/ischemia and maternal endothelial

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dysfunction are the main clinical attributes of preeclampsia [6]. It is well known that sub-optimal levels of micronutrients like folate and vitamin B12 involved in the one carbon cycle lead to increased homocysteine

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levels and are associated with preeclampsia [7, 8].

Recent reports suggest that hyperhomocysteinemia induces apoptosis through increased oxidative stress [9]. Apoptosis plays an important role in maintaining the homeostasis of various cells including placental

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trophoblastic cells [10] and is often influenced by oxidative stress [11]. This oxidative stress is known to be

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associated with abnormal spiral artery remodelling in the placenta, thereby impairing angiogenesis [12]. Studies have reported that vascular endothelial growth factor (VEGF), an angiogenic factor has an antiapoptotic activity

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and prevents endothelial apoptosis by influencing the expression of antiapoptotic proteins [13]. Studies in our department have reported altered maternal and placental angiogenesis in women with preeclampsia [8, 14].

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Increased expression of apoptosis related genes have been reported in the placenta from women with preeclampsia and are suggested to affect placental function [15]. Along with disturbed angiogenesis, oxidative stress is also reported to contribute to the pathophysiology of preeclampsia [16]. Based on the above literature, we propose that placental apoptosis in women with preeclampsia is likely to be influenced by disturbed one carbon metabolites folate, vitamin B12 along with long chain polyunsaturated fatty acids through increased homocysteine and oxidative stress and altered angiogenesis. The current review highlights the role of one carbon metabolism and angiogenesis in influencing apoptosis in women with preeclampsia.

ONE CARBON CYCLE

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ACCEPTED MANUSCRIPT One carbon metabolism provides one carbon units for both purine and pyrimidine base synthesis and produces S-adenosylmethionine (SAM), the universal methyl group donor for various biological reactions [17]. Dietary folate (i.e. vitamin B9) initiates the one carbon metabolism by donating its carbon atom to form various carbon derivatives like N-10 formyl tetrahydrofolate (THF), N5, N10 methynyl THF, N5 N10 methylene THF and N5 methyl THF [18]. N5 methyl THF then donates its methyl group for the remethylation of homocysteine to methionine in presence of methionine synthase enzyme and its cofactor, vitamin B 12 [19]. Methionine

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adenosyl transferase (MAT) acts on methionine to produce SAM [20]. SAM serves as a major methyl group donor for various biomolecules like DNA (deoxyribonucleic acid), RNA (ribonucleic acid), lipids and proteins

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and participates in various biochemical reactions. Phospholipids also require methyl group for conversion of

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phosphatidylethanolamine to phosphatidylcholine by the enzyme phosphatidyl ethanolamine N-methyl transferase (PEMT) [21]. By donating its methyl group to various biomolecules SAM is converted to S-adenosyl

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homocysteine (SAH). The SAM: SAH ratio is called methylation index and it is an indicator for methylation potential of an individual [22]. Thus, any alteration in the one carbon cycle components may affect the supply of

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methyl groups for DNA and histone methylation reactions thereby resulting in altered gene expression patterns. SAH is further converted to homocysteine which again with the help of N5 methyl THF is converted to methionine by remethylation pathway thus recycling methionine. The previously generated homocysteine enters

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the next pathway i.e. transsulphuration pathway. In this pathway cystathionne beta synthase (CBS) produces

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cystathionine with the help of serine and then cystathionine is converted to L-cysteine by the action of enzyme cystathionine gamma lyase (CSE). This is the two way process of formation of L-cysteine from homocysteine

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and requires vitamin B6 acts as a cofactor [23]. L-cysteine is converted to glutathione with the help of glutamate and glycine and gamma-glutamylcysteine as an intermediate. Glutathione is a major antioxidant which prevents

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cellular damage caused by reactive oxygen species (ROS). However, alterations in the transsulphuration pathway may result in accumulation of homocysteine and increase oxidative stress in the cell. Elevated levels of homocysteine have been postulated to cause oxidative stress and endothelial dysfunction ultimately leading to hypertension and proteinuria during gestation [24]. Further, increased homocysteine and oxidative stress may also result in disturbed placental biology by upregulation of apopototic markers [25].

APOPTOSIS

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ACCEPTED MANUSCRIPT Apoptosis is a cellular mechanism for cell deletion and is termed as programmed cell death. It is a very complex, regulated and energy dependent molecular event vital for processes like cell morphogenesis, normal cell turnover, embryonic development, maintenance of tissue homeostasis and removal of destructive cells [26]. It has a critical role in placental development; since, it is required during trophoblast differentiation and proliferation [27]. Degradation of the extracellular matrix, loss of survival signals and activation of specific death inducing ligands results in increased apoptosis [28]. Apoptotic cells undergo various biochemical

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modifications such as cell shrinkage, blebbing, nuclear degeneration, protein cleavage and protein cross linking resulting in apoptotic cell death [29]. These modifications are caused by apoptotic markers like caspases

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(cysteine-aspartic proteases) referred as the intracellular machinery responsible for apoptosis [30]. Other

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proteases that can effectively induce apoptosis include granzymes, cathepsins, proteasomal proteases and matrix metalloproteinases (MMPs) [31].

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Caspases are a set of cysteine proteases that have cysteine residue at their active site and cleave the aspartic acid residue on the target protein. In the apoptotic cell, caspases are formed as inactive precursors

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known as procaspases (zymogens). These are then activated by dimerization and mediate cell death [32]. There are two types of caspases; initiator and executioner procaspases. Initiator caspases as the name suggests are activated first and then they cleave and activate the executioner procaspases. Initiator caspases are categorised

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as caspase 2, 8, 9 and 10 while executioner caspases are categorised as caspase 1, 4 and 5 [33]. Based on the

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involvement of various adaptor proteins and initiator caspases, there are two types of apoptotic pathways: first is the death receptor or extrinsic pathway and second is the mitochondrial or intrinsic pathway. These two

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Extrinsic pathway

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pathways are known to be linked and can influence each other [26].

Extrinsic pathway is mediated through various apoptosis inducing cells (macrophages, natural killer cells) and involves various extracellular signals. Extracellular signals are various ligands that trigger various death receptors in the target cell. The various pairs of extracellular signal and their respective death receptors are: first apoptotic signal ligand/ first apoptotic signal receptor (FasL/FasR), tumor necrosis factor alpha/ tumor necrosis factor receptor 1(TNFα/TNFR1), APO3L/DR3 (death domain receptor 3), APO2L/DR4 (death domain receptor 4) and APO2L/DR5 (death domain receptor 5) [34-36]. When the ligand binds to its corresponding death receptors, death inducing signalling complex (DISC) is formed, which consists of cytosolic tail of the receptor and adaptor proteins [like, FADD (Fas associated death domain), TRADD (tumor necrosis factor

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ACCEPTED MANUSCRIPT associated death domain)] and procaspase 8 or 10 [37]. After formation of DISC, there is recruitment of caspase 8 that results in dimerization and cleavage of caspase 8 into its active form. Activated caspase 8 initiates apoptosis through activation of executioner caspases [38].

Intrinsic pathway Apoptosis can also be initiated inside the cell through the intrinsic pathway, in response to DNA

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damage, cell injury and lack of oxygen. All these changes cause loss of mitochondrial transmembrane potential [39] and release of cytochrome c in the cytosol. Cytochrome c is a water soluble component of the electron

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transport chain in the mitochondria. It binds to the apoptotic protease activating factor 1 (ApaF-1) and

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procaspase 9 to form a wheel like heptamer called as apoptosome [40]. The clustering of procaspase 9 in a close proximity leads to its activation. Activated caspase 9 leads to the activation of downstream executioner

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procaspases and induces apoptosis [41].

As mentioned earlier the two apoptotic pathways (extrinsic and intrinsic) can influence each other and

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amplify the apoptotic signals. The interaction between the two pathways is regulated by activating BH 3 interacting domain death agonist (BID) which is a proapoptotic marker of the B cell lymphoma 2 (Bcl-2) protein family [42]. This family consists of proapoptotic markers like Bcl-2 associated X-protein (BAX), Bcl-2

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associated death protein (BAD), BID and antiapoptotic markers like Bcl-2, B cell lymphoma extra large (Bcl-

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XL) and B cell lymphoma extra small (Bcl- XS) [43]. When the extrinsic pathway is activated, BID is cleaved by caspase 8 at its N-terminal region of Asp59 and is called truncated Bid (t-Bid). After cleavage t-Bid

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translocates to the mitochondria and promotes oligomerization of BAX which inhibits antiapoptotic marker Bcl2, thereby, releasing cytochrome-c. Release of cytochrome-c activates the intrinsic pathway and amplifies death

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signal cascade of caspases 9 and 3 [44]. Fig. 1 shows the two different types of apoptotic pathways and the interconnecting link between them.

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Fig.1 Schematic representation of interconnected apoptotic pathways - Extrinsic pathway- extracellular signals like FASL and TNFα activate caspase 8 and caspase 3 resulting in DNA fragmentation and apoptosis. Intrinsic pathway- Intracellular signals trigger release of Cytoc from mitochondria into cytoplasm. Cytoc forms

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apoptosome complex with APAF-1 and activates caspase 9 which in turn activates caspase 3.

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The two pathways are interlinked through Bid

FasR: first apoptotic signal receptor, FasL: first apoptotic signal ligand, FADD: first apoptotic signal death domain, TNF: tumor necrosis factor, TNFR: tumor necrosis factor receptor, TRADD: tumor necrosis factor death domain, BID: BH3 interacting domain death agonist, tBID: truncated BID, APAF1: apoptotic protease

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activating factor, Cytoc: cytochrome C, BAX: Bcl-2 associated X-protein

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APOPTOSIS AND ANGIOGENESIS IN PLACENTAL/ DEVELOPMENT Trophoblast mediated invasion is an important process for the development of the placenta. Different cytokines, growth factors and proteases interact with trophoblastic cells thereby stimulating the cells to invade maternal uterine tissues, resulting in the remodelling of spiral arteries to increase the blood flow between mother and fetus [45, 46]. Normal human pregnancy is subjected to apoptosis in different types of placental cells like endothelial, stromal and trophoblast cells [47]. Placental villi are subjected to changes in apoptosis throughout gestation [48]. During the process of vascular remodelling, the endothelial cells are stimulated to secrete chemokines, which attract various apoptosis inducing cells such as macrophages and natural killer cells (NK Cells) which 7

ACCEPTED MANUSCRIPT causes endothelial destruction by Fas ligand pathway i.e. the extrinsic pathway [49]. Abnormal remodelling of spiral arteries is associated with oxidative stress/hypoxia thus impairing angiogenesis in the embryo [50]. Endothelial cell apoptosis disturbs the vascular network called vasculogenesis in the embryo, which leads to embryonal death [51]. Different endothelial growth factors like the vascular endothelial growth factor (VEGF) family and proteases like MMPs are involved in the process of vasculogenesis and angiogenesis. VEGF plays an important role to protect endothelial cells from undergoing apoptosis; and other factors like placenta derived

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growth factor (PlGF) and angiopoetin-1 have modulating effects on vessel formation [52]. Studies on mice embryo indicate that silencing of VEGF gene and vascular endothelial (VE)-cadherin gene, which mediates

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adhesion between endothelial cells, results in increased endothelial cell apoptosis and thereby induces

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embryonal death [53, 54]. Thus, these growth factors have antiapoptotic effects and therefore are essential for normal placental and embryonal development. VEGF mediates its antiapoptotic effects via its receptor fms like

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tyrosine kinase-1 (Flk-1) through the phosphatidylinositol 3-kinase/Akt signal transduction pathway (PI3K/Akt). It is suggested that inactivation of VE-cadherin gene blocks the capability of VEGF-A to stimulate

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the PI3K/Akt pathway thereby resulting in apoptosis [55].

MMPs are a large family of zinc-dependent endopeptidases and are involved in remodelling of extracellular matrix and placental angiogenesis. They play an intriguing role in apoptosis by regulating cell

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survival and proliferation, both positively and negatively [56]. They promote programmed cell death by anoikis

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[57] i.e. cleavage of cadherins and integrins which mediates cell-cell interactions and adhesion [58]. MMP-1 (collagenase 1), MMP-7 (matrilysin) and MMP-9 (gelatinase B) are involved in apoptosis by degrading ECM

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proteins like laminin, fibronectin and vitronectin [59, 60]. Increased expression of MMP-3 (stromelysin-1) is shown to have an antiapoptotic effect, however when overexpressed it has been shown to induce apoptosis in

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epithelial cells by degrading the laminin protein [61]. Further, evidence also shows that MMP-7 releases membrane bound Fas Ligand (FasL) which induces apoptosis of neighbouring cells [62]. Growth factors (VEGF, PlGF, epidermal growth factor and insulin like growth factor), extracellular matrix components (fibronectin and vitronectin) and differentiation related genes (Bcl-2) activate the tyrosine kinase receptor (RTK), which further activates phosptatidylinositol (pI) 3-kinase. pI 3-kinase then phosphorylates a membrane-associated inositol phospholipid which then attracts intracellular signaling proteins like protein kinase B (Akt), that is activated by phosphorylation [63]. Activated Akt is released from the plasma membrane and inactivates a protein called Bad through phosphorylation. In the unphosphorylated state, Bad promotes apoptosis by binding to the antiapoptotic marker, Bcl2 and inhibits its function. On phosphorylation

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ACCEPTED MANUSCRIPT by Akt, Bad releases Bcl2, which is the active inhibitory protein of apoptosis thereby promoting cell survival

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[64] (Fig. 2).

Fig. 2 Role of VEGF in regulating apoptosis through PI3-K/Akt pathway - Survival signals like VEGF and

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PlGF activate RTK receptors which phosphorylates Akt. This active Akt phosphorylates Bad into its inactivated form which reacts with 14-3-3 protein and apoptosis is inhibited. Unphosphorylated Bad inactivates

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antiapoptotic marker Bcl2 and induces apoptosis.

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RTK: Receptor tyrosine kinase, PI 3-K: phosphoinositide 3- Kinase, PDK 1: phosphoinositide dependent kinase 1, Akt: Protein kinase B, Bad: Bcl-2 associated regulator of death, AIP: Apoptosis inhibitory protein, Bcl2: B

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cell lymphoma 2

Angiogenic factors VEGF and angiopoietin (Ang-1) activate the survival promoting PI3K/Akt

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pathway, mitogen activated protein kinase (MAPKs), and extracellular signal-regulated kinases (ERK1/2) leading to stabilization of antiapoptotic protein Bcl-2 [65, 66]. Activation of the serine/ threonine kinase Akt triggers the phosphorylation of proapoptotic proteins like Bad and inhibits apoptosis [67]. Akt also activates the endothelial NO synthase, which contributes in endothelial cell survival by inhibiting the cysteine protease activity of caspases [68]. On the other hand, antiangiogenic factors like endostatin, angiostatin and thrombospondin-1 inhibit endothelial cell proliferation and angiogenesis and stimulate endothelial cell death [69]. This proapoptotic activity of the antiangiogenic proteins is mediated through tyrosine kinase signalling and reduction of the antiapoptotic proteins Bcl-2 and Bcl-X [71] (Fig 3). Disturbed angiogenesis and apoptosis are

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ACCEPTED MANUSCRIPT known to play a significant role in the pathophysiology of preeclampsia and the next section discusses the role

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of angiogenesis and apoptosis in preeclampsia.

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Fig. 3 Angiogenesis, its factors and their association with apoptosis - Angiogenesis stimulators- VEGF and angiopoetin are positive inducer for NO synthase, PI3/Akt and MAPK, ERK1/2. NO synthase and PI3/Akt pathway inhibit caspases and Bad which are proapoptotic markers, and MAPK, ERk1/2 activates Bcl2 which is

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an antiapoptotic marker and thus inhibits apoptosis.

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Angiogenesis inhibitors-Angiostatin, thrombospondin and endostatin are negative inducers of angiogenesis that inhibit PI3/Akt pathway but activate caspase 3, p38 and tyrosine kinase thereby inducing apoptosis. VEGF: Vascular endothelial growth factor, NO: Nitric Oxide, PI3/Akt: phosphoinositide 3- Kinase/ Protein

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kinase B, MAPK: mitogen activated protein kinase, ERK: Extracellular signal-regulated kinases, Bad: Bcl-2 associated regulator of death, Bcl-2: B cell lymphoma 2, P38: P38 mitogen-activated protein kinases, Bcl-XL: B

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cell lymphoma extra large

ANGIOGENESIS AND APOPTOSIS IN PREECLAMPSIA Preeclampsia is a pregnancy complication characterized by impaired invasion of fetal trophoblasts, causing abnormal spiral artery remodelling and leading to a decrease in the blood flow between the mother and fetus [70]. This affects placental oxygen and transfer of nutrients to the fetus. In order to compensate for the blood flow deficiency, the mother develops hypertension and increases the blood flow. Thus, preeclampsia originates from the placenta resulting in maternal endothelial and vascular dysfunction [71, 72]. Evidence

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ACCEPTED MANUSCRIPT suggests that aberrant placentation due to shallow trophoblastic invasion, triggers placental oxidative stress [73] leading to increased inflammatory response and endothelial dysfunction. Vascularisation is an important physiological event during pregnancy, which ensures blood flow between mother and fetus [74]. Imbalance between pro-angiogenic and anti-angiogenic factors is known to play a key role in development of preeclampsia [75]. VEGF is the best known pro-angiogeneic marker and is important for maintenance of endothelial cell function. Reduction in the levels of VEGF results in hypertension

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and proteinuria in women with preeclampsia [76-79].

Studies from our department and others have reported an imbalance between pro-angiogenic factors

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like VEGF and anti-angiogenic factor like soluble fms-like tyrosine kinase-1 (sFlt-1) in the maternal plasma

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along with altered gene expression of angiogenic factor genes in placental tissues complicated with preeclampsia [80-83]. A longitudinal study from our department has also reported lower plasma levels of

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angiogenic factors and higher anti-angiogenic factors in women with preeclampsia right from early pregnancy [84]. It is suggested that sFlt-1 binds to free VEGF, making it unavailable for signalling to its receptors and

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mediating its biological function resulting in endothelial dysfunction. Evidence also suggests that targeting sFlt1/PlGF could be beneficial in combating preeclampsia, since increased sFlt-1/PlGF ratio has been observed in the maternal blood of women with preeclampsia[85,86].

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In addition to growth factors, proteases like MMPs also play an important role in placental

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development. Trophoblast cell invasion is regulated by MMPs and their inhibiting factors known as tissue inhibitors of MMPs (TIMPs) [87, 88]. Several MMPs like MMP-1, -2, -9, -3, -7, -13 and -14 have been shown

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to be directly linked to the process of vascular remodelling [89]. MMP-2 has a major role during implantation and MMP-9 is required during invasion [90]. Studies also indicate that MMP-3 participates in the process of

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trophoblast invasion in healthy pregnancies [89, 91]. Changes in the levels and activity of several MMPs as well as TIMPs have been observed in cases with defective trophoblast invasion and endothelial dysfunction, suggesting that these proteases act as key mediators in the pathological features of preeclampsia [92]. Several studies have reported altered maternal plasma/serum and placental levels of MMPs and their inhibitors in women with preeclampsia [93-95]. These studies suggest that an imbalance in the levels of MMPs and TIMPs generate vasoconstrictors promoting vasoconstriction and disturbed vascular remodelling which could result in hypertension in women with preeclampsia. In preeclampsia, there is an altered balance between proliferation and apoptosis of villous trophoblast [96, 97]. In support of this, studies have suggested an increase in apoptotic nuclei [98] and Fas expression and

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ACCEPTED MANUSCRIPT decrease in Fas ligand expression in preeclampsia placenta [98, 99]. There are inconsistent reports on the levels of apoptotic markers in preeclampsia with some reporting higher placental protein expression of apoptotic markers like p53, p21, and BAX [100-103]; whereas few studies suggest no change in Fas and decrease in antiapoptotic markers like Bcl-2 [104, 105] in women with preeclampsia. A recent study from our group has reported differential placental proteome levels in preeclampsia and control pregnancies particularly placental proteins involved in angiogenesis, apoptosis (TF, PRDX3, PRDX6) and placental development [106].

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Based on the above literature, it is clear that placental apoptosis is implicated in the pathophysiology of preeclampsia. However, whether increased apoptosis in preeclampsia is associated with disturbed one carbon

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metabolism is not clear. The next section describes the possible link between one carbon metabolism and

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placental apoptosis in preeclampsia.

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INTERLINK BETWEEN MATERNAL ONE CARBON METABOLISM AND PLACENTAL APOPTOSIS IN PREECLAMPSIA

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Micronutrients like folate and vitamin B12 which are components of the one carbon cycle are important determinants of pregnancy outcome. It has been suggested that an imbalance in the levels of folate and other B vitamins play a role in the pathogenesis of preeclampsia [107, 108]. As described in the one carbon cycle, folate

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and vitamin B12 maintain the methyl group supply for various macromolecules like DNA, neurotransmitters,

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proteins and membrane phospholipids [109]. Changes in the fatty acid status have also shown to influence DNA methylation patterns [110]. Imbalance of these nutrients in the diet during pregnancy may alter key methylation

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reactions during development [111]. Disruption of these patterns by perturbations in maternal nutrition may affect the pregnancy outcome and have long-term implications for the offspring.

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It is well known that suboptimal levels of folate and vitamin B12 can also lead to increased homocysteine levels which further result in increased oxidative stress [112]. Our earlier departmental studies have reported increased maternal homocysteine levels right early pregnancy in women with preeclampsia as compared to normotensive women [7]. Low levels of fatty acids particularly omega-3 fatty acid are also reported to be associated with maternal homocysteine and oxidative stress levels [113, 114]. Oxidative stress has an important role in developing endothelial dysfunction. Increased placental oxidative stress and endothelial dysfunction is shown to be associated with pregnancy complications like preeclampsia [115]. Higher levels of malondialdehyde (MDA) and Bcl-2 related ovarian killer (BOK) are upregulated in the placenta during hypoxia [89]. Lipid peroxidation

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ACCEPTED MANUSCRIPT and apoptosis in preeclampsia are reported to be associated with increased activity of caspase 9 and 3 in the placenta although caspase 8 is reported to be negatively associated [116, 117]. Oxidative stress and apoptosis are interlinked as ROS and cellular redox change play a crucial role in the signalling of apoptosis [118]. In a rat model of preeclampsia, the oxidative stress markers as well as apoptotic index (BAX/BCL-2) were reported to be higher while the glutathione levels were lower [119]. In addition, hyperhomocysteinemia is shown to be associated with increased levels of P38 MAP kinase

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in endothelial cells and homocysteine treated platelets [120, 121] and it is also known to increase the activity of caspase 3 in endothelial cells [122, 123]. Homocysteine also induces p53 expression and caspases dependent

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apoptosis in endothelial cells and umbilical vein [124]. Further, it is suggested that alterations in the levels of

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maternal micronutrients (folic acid, vitamin B12) along with reduced omega-3 fatty acids and increased homocysteine and oxidative stress levels may influence the flux of methyl groups towards DNA, histones and

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phospholipids thereby resulting in altered epigenetic patterns. These epigenetic modifications may further contribute to adverse fetal outcomes like preterm birth or low birth weight [125-127]. It is likely that

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disturbances in the one carbon metabolism resulting in increased homocysteine and oxidative stress may epigenetically program the trophoblastic cells for apoptosis. Fig. 4 demonstrates the role of the one carbon

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cycle, its cofactors and their possible influence on apoptosis in a trophoblast cell.

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Fig. 4 A possible interlink between one carbon cycle and apoptosis - Altered levels of folate and vitamin B12

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Tetrahydrofolate,

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placental angiogenesis in preeclampsia

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leads to increased homocysteine and oxidative stress resulting in increased placental apoptosis and altered

SAM:

S-Adenosyl

methionine,

SAH:

S-Adenosyl

homocysteine,

PEMT:

Phosphatidylethanolamine methyl transferase, MTHFR: Methyltetrahydrofolate reductase, VEGF: Vascular

CONCLUSION

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endothelial growth factor, MS: Methionine synthase

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Evidence suggests that homocysteine, oxidative stress, angiogenesis and apoptosis are inter-related in the pathophysiology of preeclampsia. Therefore, future studies need to understand the role of the one carbon metabolism in influencing the process of apoptosis and its association with placental angiogenesis. It is likely that altered one carbon metabolism due to imbalance in micronutrients like folate, vitamin B 12 as well as long chain polyunsaturated fatty acids contribute to increased placental apoptosis in women with preeclampsia. In future, animal and human studies can be planned to understand the effect of supplementation of one carbon metabolites on placental apoptosis in preeclampsia. This would also help in elucidating the underlying biochemical and molecular mechanisms through which one carbon metabolites influence apoptosis in

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ACCEPTED MANUSCRIPT preeclampsia. It is likely that a combined supplementation of folate, vitamin B12 and long chain polyunsaturated fatty acids from early pregnancy may be useful in reducing the risk of developing preeclampsia.

ACKNOWLEDGEMENT Author VK is the recipient of an ‘INSPIRE fellowship’ from the Department of Science and Technology,

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Government of India.

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ACCEPTED MANUSCRIPT REFERENCES

1.

Zhang S, Regnault TR, Barker PL, Botting KJ, McMillen IC, McMillan CM, Roberts CT, Morrison JL (2015) Placental adaptations in growth restriction. Nutrients 7(1):360-389. doi: 10.3390/nu7010360.

2.

Gale CR, Jiang B, Robinson SM, Godfrey KM, Law CM, Martyn CN (2006) Maternal diet during pregnancy and carotid intima–media thickness in children. Arteriosclerosis thrombosis and vascular biology

3.

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26(8):1877-82. doi: 10.1161/01.0000228819.13039.b8

Fattah FH, Shuaib FM, Darwish OA, Habashy MM (2016) Relationship between Nutritional Pattern and

RI

Occurrence of Pre-Eclampsia and Eclampsia among Primigravidae. Journal of High Institute of Public

4.

Ho-Sun Lee

SC

Health 41(4):439-58.

(2015) Impact of Maternal Diet on the Epigenome during In Utero Life and the

NU

Developmental Programming of Diseases in Childhood and Adulthood Nutrients 7(11): 9492–9507. doi: 10.3390/nu7115467

Backes CH, Markham K, Moorehead P, Cordero L, Nankervis CA, Giannone PJ (2011) Maternal

MA

5.

preeclampsia and neonatal outcomes. Journal of pregnancy 2011:214365 doi: 10.1155/2011/214365. 6.

Myatt L, Webster RP (2009) Vascular biology of preeclampsia. Journal of Thrombosis and Haemostasis

Wadhwani NS, Patil VV, Mehendale SS, Wagh GN, Gupte SA, Joshi SR (2016) Increased homocysteine

PT E

7.

D

7(3):375-84. doi: 10.1111/j.1538-7836.2008.03259.x

levels exist in women with preeclampsia from early pregnancy. The Journal of Maternal-Fetal & Neonatal

8.

CE

Medicine 29(16):2719-25.doi.org/10.3109/14767058.2015.1102880 Kulkarni AV, Mehendale SS, Yadav HR, Kilari AS, Taralekar VS, Joshi SR (2010) Circulating angiogenic

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factors and their association with birth outcomes in preeclampsia. Hypertension research 33(6):561. doi: 10.1038/hr.2010.31 9.

Zhang Z, Wei C, Zhou Y, Yan T, Wang Z, Li W, & Zhao L (2017) Homocysteine Induces Apoptosis of Human Umbilical Vein Endothelial Cells via Mitochondrial Dysfunction and Endoplasmic Reticulum Stress. Oxidative Medicine and Cellular Longevity 2017:5736506. doi: 10.1155/2017/5736506.

10. Gong JS, Kim GJ (2014) The role of autophagy in the placenta as a regulator of cell death. Clinical and experimental reproductive medicine 41(3) 97-107. doi: 10.5653/cerm.2014.41.3.97 11. Luo D, Caniggia I, Post M (2014) Hypoxia-inducible regulation of placental BOK expression. Biochemical Journal 1461(3):391-402. doi: 10.1042/BJ20140066.

16

ACCEPTED MANUSCRIPT 12. Crocker IP, Tansinda DM, Baker PN (2004) Altered cell kinetics in cultured placental villous explants in pregnancies complicated by pre-eclampsia and intrauterine growth restriction. J Pathol 204(1):11-8. doi: 10.1002/path.1610 13. Gerber HP, Dixit V, Ferrara N (1998) Vascular endothelial growth factor induces expression of the antiapoptotic proteins Bcl-2 and A1 in vascular endothelial cells. Journal of Biological Chemistry 273(21) 13313-13316.

PT

14. Sundrani DP, Reddy US, Joshi AA, Mehendale SS, Chavan-Gautam PM, Hardikar AA, Chandak GR, Joshi SR (2013) Differential placental methylation and expression of VEGF, FLT-1 and KDR genes in human

RI

term and preterm preeclampsia. Clinical epigenetics 5(1):6. doi: 10.1186/1868-7083-5-6.

SC

15. Mendilcioglu I, Karaveli S, Erdogan G, Simsek M, Taskin O, Ozekinci M (2010) Apoptosis and expression of Bcl-2, Bax, p53, caspase-3, and Fas, Fas ligand in placentas complicated by preeclampsia. Clinical and

NU

experimental obstetrics & gynecology 38(1):38-42.

16. Pereira RD, De Long NE, Wang RC, Yazdi FT, Holloway AC, Raha S (2015) Angiogenesis in the placenta: role

of

reactive

oxygen

2015.814543.doi:10.1155/2015/814543

species

signaling.

BioMed

research

international

MA

the

17. Roje S (2006) S-Adenosyl-L-methionine: beyond the universal methyl group donor. Phytochemistry.

D

67(15):1686-9 doi:10.1016/j.phytochem.2006.04.019

PT E

18. Stover PJ, Field MS (2011) Trafficking of intracellular folates. Advances in Nutrition: An International Review Journal 2(4):325-31. doi: 10.3945/an.111.000596

CE

19. Ho E, Beaver LM, Williams DE, Dashwood RH (2011) Dietary factors and epigenetic regulation for prostate cancer prevention. Advances in Nutrition: An International Review Journal 2(6):497-510. doi:

AC

10.3945/an.111.001032

20. Markham GD, Pajares MA (2009) Structure-function relationships in methionine adenosyltransferases. Cellular and molecular life sciences 66(4):636-48. doi: 10.1007/s00018-008-8516-1. 21. Valtolina C, Vaandrager AB, Favier RP, RobbenJH, Tuohetahuntila M, Kummeling A, Rothuizen J et al (2015)

No up-regulation of the phosphatidylethanolamine N-methyltransferase pathway and choline

production by sex hormones in cats. BMC veterinary research 11:280. doi: 10.1186/s12917-015-0591-6 22. Waterland RA, Dolinoy DC, Lin JR, Smith CA, Shi X, Tahiliani KG (2006) Maternal methyl supplements increase offspring DNA methylation at Axin Fused. Genesis 44(9):401-6. doi:10.1002/dvg.20230

17

ACCEPTED MANUSCRIPT 23. Cuskelly GJ, Stacpoole PW, Williamson J, Baumgartner TG, Gregory JF (2001) Deficiencies of folate and vitamin B 6 exert distinct effects on homocysteine, serine, and methionine kinetics. American Journal of Physiology-Endocrinology And Metabolism 281(6):E1182-90. 24. Falcao S, Stoyanova E, Cloutier G, Maurice RL, Gutkowska J, Lavoie JL (2009) Mice overexpressing both human angiotensinogen and human renin as a model of superimposed preeclampsia on chronic hypertension. Hypertension 54(6):1401-7. doi: 10.1161/HYPERTENSIONAHA.109.137356.

PT

25. Luo D, Caniggia I, Post M (2014) Hypoxia-inducible regulation of placental BOK expression. Biochem J 461(3):391-402. doi: 10.1042/BJ20140066.

RI

26. Elmore S (2007) Apoptosis: a review of programmed cell death. Toxicologic pathology 35(4):495-516.

SC

doi:10.1080/01926230701320337

27. Zhao WX, Zhuang X, Huang TT, Feng R, Lin JH (2015) Effects of Notch2 and Notch3 on cell proliferation

NU

and apoptosis of trophoblast cell lines. International journal of medical sciences 12(11):867-74. doi: 10.7150/ijms.12935.

MA

28. Vachon, PH (2011). Integrin signaling, cell survival, and anoikis: distinctions, differences, and differentiation. Journal of signal transduction 738137. doi: 10.1155/2011/738137 29. Hengartner MO (2000) The biochemistry of apoptosis. Nature. 407(6805):770-6 doi :10.1038/35037710

D

30. McIlwain DR, Berger T, Mak TW (2015) Caspase functions in cell death and disease. Cold Spring Harbor

PT E

perspectives in biology 7(4). pii: a026716. doi: 10.1101/cshperspect.a026716 31. Lockshin RA, Zakeri Z. (2004) Caspase-independent cell death? Oncogene; 23: 2766–2773

CE

32. Fink SL, Cookson BT (2005) Apoptosis, pyroptosis, and necrosis: mechanistic description of dead and dying eukaryotic cells. Infection and immunity 73(4):1907-16. doi:10.1128/IAI.73.4.1907-1916.2005

AC

33. Chang HY, Yang X (2000) Proteases for cell suicide: functions and regulation of caspases. Microbiology and molecular biology reviews 64(4):821-46. 34. Peter ME, Krammer PH (1998) Mechanisms of CD95 (APO-1/Fas)-mediated apoptosis. Current opinion in immunology 10 (5):545-51. 35. Ashkenazi A, Dixit VM (1998) Death receptors: signaling and modulation. Science 281(5381):1305-8. 36. Chicheportiche Y, Bourdon PR, Xu H, Hsu YM, Scott H, Hession C, Garcia I, Browning JL (1997) TWEAK, a new secreted ligand in the tumor necrosis factor family that weakly induces apoptosis. Journal of Biological Chemistry 272(51):32401-10.

18

ACCEPTED MANUSCRIPT 37. Kischkel FC, Hellbardt S, Behrmann I, Germer M, Pawlita M, Krammer PH, Peter ME (1995) Cytotoxicity-dependent APO-1 (Fas/CD95)-associated proteins form a death-inducing signaling complex (DISC) with the receptor. The EMBO journal 14(22):5579. 38. Mcllwain DR, Berger T, Mak TW (2013) Caspase functions in cell death and disease. Cold Spring Harb Perspect Biol 5(4):a008656. doi: 10.1101/cshperspect.a008656. 39. Saelens X, Festjens N, Walle LV, Van Gurp M, van Loo G, Vandenabeele P (2004) Toxic proteins released

PT

from mitochondria in cell death. Oncogene 23(16):2861-74. doi:10.1038/sj.onc.1207523 40. Hill MM, Adrain C, Duriez PJ, Creagh EM, Martin SJ (2004) Analysis of the composition, assembly and

activity

of

native

Apaf‐1

apoptosomes.

EMBO

journal

23(10):2134-45.

SC

doi:10.1038/sj.emboj.7600210

The

RI

kinetics

41. Parrish AB, Freel CD, Kornbluth S (2013) Cellular mechanisms controlling caspase activation and function.

NU

Cold Spring Harbor perspectives in biology 5(6):a008672. doi:10.1101/cshperspect.a008672 42. Cory S, Adams JM. (2002) The Bcl2 family: regulators of the cellular life-or-death switch. Nature Reviews

MA

Cancer 2(9):647-56. doi:10.1038/nrc883

43. Reed JC, Zha H, Aime-Sempe C, Takayama S, Wang HG(1996) Structure-function analysis of Bcl-2 family proteins. Regulators of programmed cell death. Adv Exp Med Biol 406:99-112.

D

44. Li H, Zhu H, Xu CJ, Yuan J (1998) Cleavage of BID by caspase 8 mediates the mitochondrial damage in

PT E

the Fas pathway of apoptosis. Cell 94(4):491-501. 45. Hayes EK, Tessier DR, Percival ME, Holloway AC, Petrik JJ, Gruslin A, Raha S (2014) Trophoblast

CE

invasion and blood vessel remodeling are altered in a rat model of lifelong maternal obesity. Reproductive Sciences 21(5):648-57. doi: 10.1177/1933719113508815.

AC

46. Rundhaug, J. E. (2005). Matrix metalloproteinases and angiogenesis. Journal of cellular and molecular medicine, 9(2), 267-285. 47. Smith S, Baker PN, Symonds EM (1997) Placental apoptosis in normal human pregnancy. American journal of obstetrics and gynecology 177 (1):57-65. 48. Black S, Kadyrov M, Kaufmann P, Ugele B, Emans N, Huppertz B (2004) Syncytial fusion of human trophoblast depends on caspase 8. Cell Death & Differentiation 11(1):90-8. doi:10.1038/sj.cdd.4401307 49. Smith SD, Dunk CE, Aplin JD, Harris LK, Jones RL (2009) Evidence for immune cell involvement in decidual spiral arteriole remodeling in early human pregnancy. The American journal of pathology 174(5):1959-71. doi:10.2353/ajpath.2009.080995

19

ACCEPTED MANUSCRIPT 50. Crocker IP, Tansinda DM, Baker PN (2004) Altered cell kinetics in cultured placental villous explants in pregnancies complicated by pre‐eclampsia and intrauterine growth restriction. The Journal of pathology 204(1):11-8. doi:10.1002/path.1610 51. Isner JM, Asahara T. Angiogenesis and vasculogenesis as therapeutic strategies for postnatal neovascularisation (1999) Journal of Clinical Investigation 103(9):1231. doi:10.1172/JCI6889 52. Suri C, Jones PF, Patan S, Bartunkova S, Maisonpierre PC, Davis S, Sato TN, Yancopoulos GD (1996)

PT

Requisite role of angiopoietin-1, a ligand for the TIE2 receptor, during embryonic angiogenesis Cell 87(7):1171-80

RI

53. Carmeliet P, Lampugnani MG, Moons L, Breviario F, Compernolle V, Bono F, Balconi G, Spagnuolo R,

SC

Oosthuyse B, Dewerchin M, Zanetti A (1999) Targeted deficiency or cytosolic truncation of the VEcadherin gene in mice impairs VEGF-mediated endothelial survival and angiogenesis Cell 98(2):147-57.

NU

54. Carmeliet P, Ferreira V, Breier G, Pollefeyt S (1996) Abnormal blood vessel development and lethality in embryos lacking a single VEGF allele. Nature 380(6573):435. doi:10.1038/380435a0

MA

55. Dimmeler S, Zeiher AM (2000) Endothelial cell apoptosis in angiogenesis and vessel regression. Circulation research 87(6):434-9.

56. Egeblad M., & Werb Z. (2002). New functions for the matrix metalloproteinases in cancer

D

progression. Nature Reviews Cancer, 2(3), 161-174.

PT E

57. Frisch, SM. and Screaton, RA. (2001). Anoikis mechanisms. Current opinion in cell biology, 13(5), pp.555562.

CE

58. Levkau, B, Kenagy, RD, Karsan A, Weitkamp B, Clowes AW, Ross R. and Raines EW. (2002). Activation of metalloproteinases and their association with integrins: an auxiliary apoptotic pathway in human

AC

endothelial cells. Cell death and differentiation, 9(12), p.1360. 59. Lee SR, Lo EH. (2004) Induction of caspase-mediated cell death by metalloproteinases in cerebral endothelial cells after hypoxiareoxygeneration. J Cereb Blood Flow Metab 24: 720–727. 60. Chintala SK, Zhang X, Austin JS, Fini ME. (2002) Deficiency in matrix metalloproteinase B (MMP-9) protects against retinal ganglion cell death after optic nerve ligation. J Biol Chem 277: 47461–47468. 18. 61. Sympson, Carolyn J, Rabih S. Talhouk, Caroline M. Alexander, Jennie R. Chin, Shirley M. Clift, Mina J. Bissell, and Zena Werb. (1994) Targeted expression of stromelysin-1 in mammary gland provides evidence for a role of proteinases in branching morphogenesis and the requirement for an intact basement membrane for tissue-specific gene expression. J Cell Biol 125: 681–693.

20

ACCEPTED MANUSCRIPT 62. Powell WC, Fingleton B, Wilson CL, Boothby M, Matrisian LM. (1999). The metalloproteinase Matrilysin (MMP-7) proteolytically generates active soluble Fas ligand and potentiates epithelial cell apoptosis. Curr Biol 9: 1441–1447 63. Kennedy SG, Wagner AJ, Conzen SD, Jordan J, Bellacosa A, Tsichlis PN, Hay N (1997) The PI 3kinase/Akt signaling pathway delivers an anti-apoptotic signal. Genes & development 11(6) 701-713. 64. Vara JÁ, Casado E, de Castro J, Cejas P, Belda IC, González BM (2004) PI3K/Akt signalling pathway and

PT

cancer. Cancer treatment reviews 30(2):193-204.

65. Breitschopf K, Haendeler J, Malchow P, Zeiher AM, Dimmeler S (2000) Posttranscriptional modification

RI

of Bcl-2: molecular characterization of the involved signaling pathways. Mol Cell Biol 20:1886-96.

SC

doi: 10.1128/MCB.20.5.1886-1896.2000

66. Dimmeler S, Breitschopf K, Haendeler J, Zeiher AM (1999) Dephosphorylation targets Bcl-2 for ubiquitin-

NU

dependent degradation: a link between the apoptosome and the proteasome pathway. Journal of Experimental Medicine 189(11):1815-22.

MA

67. Khwaja A (1999) Apoptosis: Akt is more than just a Bad kinase. Nature 401(6748):33-4. 68. Dimmeler S, Haendeler J, Nehls M, Zeiher AM (1997) Suppression of apoptosis by nitric oxide via inhibition of interleukin-1β–converting enzyme (ice)-like and cysteine protease protein (cpp)-32–like

D

proteases. Journal of Experimental Medicine 185(4):601-8.

PT E

69. Guo NH, Krutzsch HC, Inman JK, Roberts DD (1997) Thrombospondin 1 and type I repeat peptides of thrombospondin 1 specifically induce apoptosis of endothelial cells. Cancer research 57(9):1735-42.

CE

70. Roberts, JM. And Escudero C. (2012). The placenta in preeclampsia. Pregnancy Hypertension: An International Journal of Women's Cardiovascular Health, 2(2), pp.72-83.

AC

71. LaMarca B. (2012). Endothelial dysfunction; an important mediator in the Pathophysiology of Hypertension during Preeclampsia. Minerva ginecologica, 64(4), 309. 72. Sánchez-Aranguren LC, Prada CE, Riaño-Medina CE, Lopez M. (2014) Endothelial dysfunction and preeclampsia: role of oxidative stress. Frontiers in physiology.;5. 73. Yiyenoğlu, ÖB, Uğur, MG, Özcan, HÇ, Can G, Öztürk E, Balat Ö, & Erel Ö. (2014). Assessment of oxidative stress markers in recurrent pregnancy loss: a prospective study. Archives of gynecology and obstetrics, 289(6), 1337-1340. 74. Duan J, Chabot-Lecoanet AC, Perdriolle-Galet E, Christov C, Hossu G, Cherifi A, Morel O (2016) Uteroplacental vascularisation in normal and preeclamptic and intra-uterine growth restriction pregnancies: third

21

ACCEPTED MANUSCRIPT trimester quantification using 3D power Doppler with comparison to placental vascular morphology (EVUPA): a prospective controlled study. BMJ open 1;6(3):e009909. doi: 10.1136/bmjopen-2015-009909 75. Jardim LL, Rios DR, Perucci LO, de Sousa LP, Gomes KB, Dusse LM (2015) Is the imbalance between proangiogenic and anti-angiogenic factors associated with preeclampsia?. Clinica Chimica Acta. 20;447:34-8. doi: 10.1016/j.cca.2015.05.004 76. Venkatesha S, Toporsian M, Lam C, Hanai JI, Mammoto T, Kim YM, Bdolah Y, Lim KH, Yuan HT,

PT

Libermann TA, Stillman IE (2006) Soluble endoglin contributes to the pathogenesis of preeclampsia. Nature medicine 12(6):642. doi:10.1038/nm1429

RI

77. Levine RJ, Maynard SE, Qian C, Lim KH, England LJ, Yu KF, Schisterman EF, Thadhani R, Sachs BP,

SC

Epstein FH, Sibai BM (2004) Circulating angiogenic factors and the risk of preeclampsia. New England journal of medicine 12;350(7):672-83.

NU

78. Maynard SE, Min JY, Merchan J, Lim KH, Li J, Mondal S, Libermann TA, Morgan JP, Sellke FW, Stillman IE, Epstein FH (2003) Excess placental soluble fms-like tyrosine kinase 1 (sFlt1) may contribute to endothelial

MA

dysfunction, hypertension, and proteinuria in preeclampsia. The Journal of clinical investigation 1;111(5):64958. doi: 10.1172/JCI200317189

79. Polliotti BM, Fry AG, Saller Jr DN, Mooney RA, Cox C, Miller RK (2003) Second-trimester maternal serum

D

placental growth factor and vascular endothelial growth factor for predicting severe, early-onset preeclampsia.

PT E

Obstetrics & Gynecology 1;101(6):1266-74.

80. Kulkarni AV, Mehendale SS, Yadav HR, Kilari AS, Taralekar VS, Joshi SR (2010) Circulating angiogenic

CE

factors and their association with birth outcomes in preeclampsia. Hypertens Res 33: 561–567 81. Sundrani DP, Reddy US, Joshi AA, Mehendale SS, Chavan-Gautam PM, Hardikar AA, Chandak GR, Joshi SR

AC

(2013) Differential placental methylation and expression of VEGF, FLT-1 and KDR genes in human term and preterm preeclampsia. Clinical epigenetics 5(1):6. doi: 10.1186/1868-7083-5-6 82. Schoofs K, Grittner U, Engels T, Pape J, Denk B, Henrich W, Verlohren S (2014) The importance of repeated measurements of the sFlt-1/PlGF ratio for the prediction of preeclampsia and intrauterine growth restriction. Journal of perinatal medicine 1;42(1):61-8. doi: 10.1515/jpm-2013-0074 83. Romero R, Nien JK, Espinoza J, Todem D, Fu W, Chung H, Kusanovic JP, Gotsch F, Erez O, Mazaki-Tovi S, Gomez R (2008) A longitudinal study of angiogenic (placental growth factor) and anti-angiogenic (soluble endoglin and soluble vascular endothelial growth factor receptor-1) factors in normal pregnancy and patients

22

ACCEPTED MANUSCRIPT destined to develop preeclampsia and deliver a small for gestational age neonate. The journal of maternal-fetal & neonatal medicine 1;21(1):9-23. doi: 10.1080/14767050701830480 84. Sahay AS, Patil VV, Sundrani DP, Joshi AA, Wagh GN, Gupte SA, Joshi SR (2014) A longitudinal study of circulating angiogenic and antiangiogenic factors and AT1-AA levels in preeclampsia. Hypertension Research. 37(8):753. doi: 10.1038/hr.2014.71 85. Mimura K, Tomimatsu T, Sharentuya N, et al (2010) Nicotine restores endothelial dysfunction caused by

PT

excess sFlt1 and sEng in an in vitro model of preeclamptic vascular endothelium: a possible therapeutic role of nicotinic acetylcholine receptor (nAChR) agonists for preeclampsia. Am J Obstet Gynecol

RI

202(5):464.e1-6. [36]

SC

86. Stepan H, Herraiz I, Schlembach D, et al. (2015) Implementation of the sFlt-1/PlGF ratio for prediction and diagnosis of pre-eclampsia in singleton pregnancy: implications for clinical practice. Ultrasound Obstet

NU

Gynecol 45:241–6

87. Amalinei C, Căruntu ID, Bălan RA (2007) Biology of metalloproteinases. Rom J Morphol Embryol

MA

48(4):323-34.

88. Visse R, Nagase H (2003) Matrix metalloproteinases and tissue inhibitors of metalloproteinases: structure, function, and biochemistry. Circulation research 2;92(8):827-39.

in

Severe

Early-and

Late-Onset

PT E

MMP-13

D

89. Laskowska M (2017) Altered Maternal Serum Matrix Metalloproteinases MMP-2, MMP-3, MMP-9, and Preeclampsia.

BioMed

research

international

doi: 10.1155/2017/6432426

CE

90. Staun-Ram E, Goldman S, Gabarin D, Shalev E (2004) Expression and importance of matrix metalloproteinase 2 and 9 (MMP-2 and-9) in human trophoblast invasion. Reproductive Biology and

AC

Endocrinology 2(1):59.

91. Husslein H, Haider S, Meinhardt G, Prast J, Sonderegger S, Knofler M (2009) Expression, regulation and functional characterization of matrix metalloproteinase-3 of human trophoblast. Placenta 1;30(3):284-91. doi: 10.1016/j.placenta.2008.12.002 92. Sosa EY, Flores-Pliego A, Espejel-Nunez A, Medina-Bastidas D, Vadillo-Ortega F, Zaga-Clavellina V, Estrada-Gutierrez G (2017) New Insights into the Role of Matrix Metalloproteinases in Preeclampsia. International journal of molecular sciences 20;18(7):1448. doi: 10.3390/ijms18071448

23

ACCEPTED MANUSCRIPT 93. Rahat B, Sharma R, Bagga R, Hamid A, Kaur J (2016) Imbalance between matrix metalloproteinases and their tissue inhibitors in preeclampsia and gestational trophoblastic diseases. Reproduction 1;152(1):11-22. doi: 10.1530/REP-16-0060 94. CT Palei A, P Granger J, E Tanus-Santos J (2013) Matrix metalloproteinases as drug targets in preeclampsia. Current drug targets Mar 1;14(3):325-34. 95. Poon LC, Nekrasova E, Anastassopoulos P, Livanos P, Nicolaides KH (2009) First‐trimester maternal

PT

serum matrix metalloproteinase‐9 (MMP‐9) and adverse pregnancy outcome. Prenatal diagnosis 1;29(6):553-9. DOI: 10.1002/pd.2234

RI

96. Huppertz B (2011) Placental pathology in pregnancy complications. Thrombosis research 127:S96-9. doi:

SC

10.1016/S0049-3848(11)70026-3.

97. Heazell AE, Buttle HR, Baker PN, Crocker IP (2008) Altered expression of regulators of caspase activity

NU

within trophoblast of normal pregnancies and pregnancies complicated by preeclampsia. Reproductive Sciences 15(10):1034-43. doi: 10.1177/1933719108322438.

MA

98. Leung DN, Smith SC, To KF, Sahota DS, Baker PN (2001) Increased placental apoptosis in pregnancies complicated by preeclampsia. American journal of obstetrics and gynecology 184(6):1249-50.

D

doi:10.1067/mob.2001.112906

99. Allaire AD, Ballenger KA, Wells SR, McMahon MJ, Lessey BA (2000) Placental apoptosis in

PT E

preeclampsia. Obstetrics & Gynecology 96(2):271-6. 100. Sharp AN, Heazell AE, Crocker IP, Mor G (2010) Placental apoptosis in health and disease. American

CE

Journal of Reproductive Immunology 64(3):159-69. doi: 10.1111/j.1600-0897.2010.00837 101. Cobellis L, de Falco M, Torella M, Trabucco E, Caprio F, Federico E, Manente L, Coppola G, Laforgia V,

AC

Cassandro R, Colacurci N (2007) Modulation of Bax expression in physiological and pathological human placentas throughout pregnancy. in vivo 21(5):777-83. 102. Levy R, Smith SD, Yusuf K, Huettner PC, Kraus FT, Sadovsky Y, Nelson DM. (2002) Trophoblast apoptosis from pregnancies complicated by fetal growth restriction is associated with enhanced p53 expression. American journal of obstetrics and gynecology 186(5):1056-61. 103. Fulop V, Mok SC, Genest DR, Gati I, Doszpod J, Berkowitz RS (1998)

p53, p21, Rb and mdm2

oncoproteins. Expression in normal placenta, partial and complete mole, and choriocarcinoma. The Journal of reproductive medicine 43(2):119-27.

24

ACCEPTED MANUSCRIPT 104. Ishihara N, Matsuo H, Murakoshi H, Laoag-Fernandez JB, Samoto T, Maruo T (2002) Increased apoptosis in the syncytiotrophoblast in human term placentas complicated by either preeclampsia or intrauterine growth retardation. American journal of obstetrics and gynecology 186(1):158-66. 105. Levy R, Smith SD, Yusuf K, Huettner PC, Kraus FT, Sadovsky Y, Nelson DM. (2002) Trophoblast apoptosis from pregnancies complicated by fetal growth restriction is associated with enhanced p53 expression. American journal of obstetrics and gynecology 186(5):1056-61.

PT

106. Mary S, Kulkarni MJ, Malakar D, Joshi SR, Mehendale SS, Giri AP (2017) Placental proteomics provides insights into pathophysiology of pre-eclampsia and predicts possible markers in plasma. Journal of

RI

proteome research 16(2):1050-60. doi: 10.1021/acs.jproteome.6b00955

SC

107. Kharb S, Aggarwal D, Bala J, Nanda S. Evaluation of Homocysteine, Vitamin B12 and Folic Acid Levels During all the Trimesters in Pregnant and Preeclamptic Womens. Current hypertension reviews. 2016 Dec

NU

1;12(3):234-8. doi: 10.2174/1573402112666161010151632

108. Acılmıs YG, Dikensoy E, Kutlar AI, Balat O, Cebesoy FB, Ozturk E, Cicek H, Pence S. Homocysteine,

MA

folic acid and vitamin B12 levels in maternal and umbilical cord plasma and homocysteine levels in placenta in pregnant women with pre‐eclampsia. Journal of Obstetrics and Gynaecology Research. 2011 Jan 1;37(1):45-50.

D

109. Umhau JC, Dauphinais KM, Patel SH, Nahrwold DA, Hibbeln JR, Rawlings RR, George DT (2006) The

PT E

relationship between folate and docosahexaenoic acid in men. Eur J Clin Nutr 60:352-7 110. Hussey B, Lindley MR, Mastana SS. Omega 3 fatty acids, inflammation and DNA methylation: an

CE

overview. Clinical Lipidology. 2017 Jan 1;12(1):24-32. 111. Maloney CA, Hay SM, Rees WD. Folate deficiency during pregnancy impacts on methyl metabolism

8.

AC

without affecting global DNA methylation in the rat fetus. British journal of nutrition. 2007 Jun;97(6):1090-

112. Fenech M. (2012) Folate (vitamin B9) and vitamin B12 and their function in the maintenance of nuclear and mitochondrial genome integrity. Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 733(1):21-33. doi: 10.1016/j.mrfmmm.2011.11.003 113. Wadhwani N, Patil V, Pisal H, Joshi A, Mehendale S, Gupte S, Wagh G, Joshi S. (2014) Altered maternal proportions of long chain polyunsaturated fatty acids and their transport leads to disturbed fetal stores in preeclampsia. Prostaglandins, Leukotrienes and Essential Fatty Acids (PLEFA) (1):21-30. doi: 10.1016/j.plefa.2014.05.006

25

ACCEPTED MANUSCRIPT 114. Kulkarni AV, Mehendale SS, Yadav HR, Joshi SR (2011) Reduced placental docosahexaenoic acid levels associated with increased levels of sFlt-1 in preeclampsia. Prostaglandins, Leukotrienes and Essential Fatty Acids 84(1):51-5. doi.org/10.1016/j.plefa.2010.09.005 115. Burdon C, Mann C, Cindrova-Davies T, Ferguson-Smith AC, Burton GJ (2007) Oxidative stress and the induction of cyclooxygenase enzymes and apoptosis in the murine placenta. Placenta 28(7):724-33. doi:10.1016/j.placenta.2006.12.001

PT

116. Luo D, Caniggia I, Post M (2014) Hypoxia-inducible regulation of placental BOK expression. Biochemical Journal 461(3):391-402. doi: 10.1042/BJ20140066

RI

117. Shaker OG, Sadik NA (2013) Pathogenesis of preeclampsia: implications of apoptotic markers and

SC

oxidative stress. Human & experimental toxicology (11):1170-8. doi: 10.1177/0960327112472998 118. Kannan K, Jain SK (2000) Oxidative stress and apoptosis. Pathophysiology 2000 7(3):153-63.

NU

119. Beausejour A, Bibeau K, Lavoie JC, St-Louis J, Brochu M (2007) Placental oxidative stress in a rat model of preeclampsia. Placenta 28(1):52-8.doi:10.1016/j.placenta.2005.12.003

MA

120. Wang J, Ge J, Yang LN, Xue D, Li J (2011) Protective effects and its mechanism on neural cells after folic acid intervention in preeclampsia rat model. Zhonghua fu chan ke za zhi 46(8):605-9. 121. Leoncini G, Bruzzese D, Signorello MG (2006) Activation of p38 MAPKinase/cPLA2 pathway in

D

homocysteine‐treated platelets. Journal of Thrombosis and Haemostasis 4(1):209-16.

PT E

122. Grethe S, Ares MP, Andersson T, & Porn-Ares MI (2004) p38 MAPK mediates TNF-induced apoptosis in endothelial cells via phosphorylation and downregulation of Bcl-xL. Experimental cell research 298(2),

CE

632-642. doi:10.1016/j.yexcr.2004.05.007 123. Zhang C, Cai Y, Adachi MT, Oshiro S, Aso T, Kaufman RJ, Kitajima S (2001) Homocysteine induces

AC

programmed cell death in human vascular endothelial cells through activation of the unfolded protein response. Journal of Biological Chemistry 276(38):35867-74. doi:10.1074/jbc.M100747200 124. Lee SJ, Kim KM, Namkoong S, Kim CK, Kang YC, Lee H, Ha KS, Han JA, Chung HT, Kwon YG, Kim YM (2005) Nitric oxide inhibition of homocysteine-induced human endothelial cell apoptosis by downregulation of p53-dependent Noxa expression through the formation of S-nitrosohomocysteine. Journal of Biological Chemistry 280(7):5781-8. doi:10.1074/jbc.M411224200 125. Khot V, Kale A, Joshi A, Chavan-Gautam P, Joshi S (2014) Expression of genes encoding enzymes involved in the one carbon cycle in rat placenta is determined by maternal micronutrients (folic acid,

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acids.

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10.1155/2014/613078. 126. Dhobale M, Joshi S (2012) Altered maternal micronutrients (folic acid, vitamin B12) and omega 3 fatty acids through oxidative stress may reduce neurotrophic factors in preterm pregnancy. The Journal of Maternal-Fetal & Neonatal Medicine 25(4):317-23. doi: 10.3109/14767058.2011.579209 127. Sundrani DP, Gautam PM, Mehendale SS, Joshi SR (2011) Altered metabolism of maternal micronutrients

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and omega 3 fatty acids epigenetically regulate matrix metalloproteinases in preterm pregnancy: A novel

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hypothesis. Medical hypotheses 277(5):878-83. doi: 10.1016/j.mehy.2011.08.001.

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Graphical abstract

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