Role of vascular endothelial growth factor in maintenance of pregnancy in mice

Placental expression of estrogen and progesterone receptors and vascular endothelial growth factor in buffaloes suffering from uterine torsion

BACKGROUND

Although several risk factors have been suggested for uterine torsion, the pathogenesis is still unclear. Therefore, the current study aims to investigate the pathogenesis of uterine torsion by assessing the histological, histochemical, and immunohistochemical changes that occur in the placenta obtained from uterine torsion cases. Immunohistochemical changes include investigation of the expression of estrogen receptors (ERs), progesterone receptors (PRs), and the vascular endothelial growth factor (VEGF) in the placental tissue.

METHODS

Forty intrapartum dairy cows were included in this investigation. The cows were divided into two equal groups. The first group was the uterine torsion (UT) group, while the second group was the normal control group (Ctrl). After caesarian section treatment, placentas were collected from all animals in the study. Histopathological, histochemical, and immunohistochemical examinations were performed. Estrogen receptors, progesterone receptors, and vascular endothelial growth factor expression in the placenta were evaluated.

RESULTS

The results revealed numerous trophoblast giant or binucleate cells in the trophoblastic epithelium. Through Masson's trichrome technique, the distribution of collagen fibers as shiny, blue-colored stripes on the fetal mesenchyme was observed. Additionally, the results showed a strong, intense PAS-positive reaction in the cytoplasmic vesicles of most trophoblastic cells due to mucopolysaccharides. The immunohistochemical findings of the UT placenta revealed moderate to weak staining for ERs in contrast to those of the Ctrl placenta, which revealed moderate staining for ERs. In addition, non-statistical differences in the expression of PRs were found between the two tested groups. For VEGF, strong positive immunoreactivity was found in the Ctrl group compared to the UT group, which exhibits a general absence in many trophoblast cells.

CONCLUSION

It can be concluded that significant variation was observed in the placentas obtained from buffaloes suffering from UT compared to those obtained from normal pregnant ones. These significant variations were involved in the decreased expression of ERs and VEGF in the UT group compared to the normal Ctrl one. Investigating the expression of these placental molecules may monitor the changes in the placental tissue and provide insight into the pathogenesis of UT.

Lack of association between the VEGFA gene polymorphisms and preterm birth in Korean women

Preterm birth (PTB), a pregnancy-related disease, is defined as a birth before 37 weeks of gestation. It is a major cause of maternal mortality and morbidity worldwide, and its incidence rate is steadily increasing. Various genetic factors can contribute to the etiology of PTB. Vascular endothelial growth factor A (VEGFA) gene is an important angiogenic gene and its polymorphisms have been reported to be associated with PTB development. Therefore, we conducted a case-control study to evaluate the association between VEGFA rs699947, rs2010963, and rs3025039 polymorphisms and PTB in Korean women. A total of 271 subjects (116 patients with PTB and 155 women at ≥38 weeks of gestation) were analyzed in this study. The genotyping of VEGFA gene polymorphisms was performed using polymerase chain reaction- restriction fragment length polymorphism. No significant association between the patients with PTB and the control groups was confirmed. In the combination analysis, we found a significant association between PTB and VEGFA rs699947 CC-rs2010963 GG-rs3025039 CC combination (odds ratio, 3.77; 95% confidence interval, 1.091 to 13.032; p = 0.031). The VEGFA rs699947, rs2010963, and rs3025039 polymorphisms might have no genetic association with the pathogenesis of PTB in Korean women. However, the combination analysis indicates the possibility that VEGFA acts in PTB pathophysiology. Therefore, larger sample sets and replication studies are required to further elucidate our findings.

Effect of Disulfiram on the Reproductive Capacity of Female Mice

In the process of assisted reproduction, the high-oxygen in vitro environment can easily cause oxidative damage to oocytes. Disulfiram (DSF) can play an anti-oxidant or pro-oxidant role in different cells, and the effect of DSF on oocytes remains unclear. Moreover, it remains unclear whether the use of DSF in the early stages of pregnancy has a negative impact on the fetus. In this study, we found that DSF increased serum FSH levels and increased the ovulation rate in mice. Moreover, DSF enhanced the antioxidant capacity of oocytes and contributed to the success rate of in vitro fertilization. Moreover, the use of DSF in early pregnancy in mice increased the uterine horn volume and the degree of vascularization, which contributed to a successful pregnancy. In addition, it was found that DSF regulated the mRNA expression of angiogenesis-related genes (VEGF), follicular development-related genes (C1QTNF3, mTOR and PI3K), ovulation-related genes (MAPK1, MAPK3 and p38 MAPK) and antioxidant-related genes (GPX4 and CAT). These results indicate that DSF is helpful for increasing the antioxidant capacity of oocytes and the ovulation rate. In early pregnancy in mice, DSF promotes pregnancy by increasing the degree and volume of uterine vascularization.

Vascular Endothelial Growth Factor Receptor 2: Molecular Mechanism and Therapeutic Potential in Preeclampsia Comorbidity with Human Immunodeficiency Virus and Severe Acute Respiratory Syndrome Coronavirus 2 Infections

This review explored the role of vascular endothelial growth factor receptor-2 (VEGFR-2) in the synergy of preeclampsia (PE), human immunodeficiency virus (HIV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Downregulation of VEGFR-2 in PE promotes endothelial dysfunction and prevents endothelial cell (EC) migration, proliferation, and differentiation. The HIV-1 accessory protein, tat (trans-activator of transcription), prevents VEGFR-2 signaling via the vascular endothelial growth factor A (VEGF-A) ligand. Combined antiretroviral therapy (cART) may cause immune reconstitution, impaired decidualization, and endothelial injury, thus may be a risk factor for PE development. The VEGF/VEGFR-2 interaction may be associated with SARS-CoV-2-related pulmonary oedema. Endothelial dysfunction and heightened inflammation are both associated with PE, HIV, and SARS-CoV-2 infection; therefore, it is plausible that both characteristics may be exacerbated in the synergy of these events. In addition, this review explored microRNAs (miR) regulating VEGFR-2. An overexpression of miR-126 is evident in PE, HIV, and SARS-CoV-2 infection; thus, modulating the expression of miR-126 may be a therapeutic strategy. However, the involvement of microRNAs in PE, HIV, and SARS-CoV-2 infection needs further investigating. Since these conditions have been evaluated independently, this review attempts to predict their clinical manifestations in their synergy, as well as independently; thereby providing a platform for early diagnosis and therapeutic potential in PE, HIV, and SARS-CoV-2 infection.

Role of Vascular Endothelial Growth Factor (VEGF) in Human Embryo Implantation: Clinical Implications

Vascular endothelial growth factor (VEGF) is a well-known angiogenic factor that plays a critical role in various physiological and pathological processes. VEGF also contributes to the process of embryo implantation by enhancing embryo development, improving endometrial receptivity, and facilitating the interactions between the developing embryo and the endometrium. There is a correlation between the alteration of VEGF expression and reproductive failure, including recurrent implantation failure (RIF) and recurrent miscarriage (RM). In order to clarify the role of VEGF in embryo implantation, we reviewed recent literature concerning the expression and function of VEGF in the reproductive system around the time of embryo implantation and we provide a summary of the findings reported so far. We also explored the effects and the possible underlying mechanisms of action of VEGF in embryo implantation.

Comparison of VEGF-A values between pregnant women with COVID-19 and healthy pregnancies and its association with composite adverse outcomes

The aim is to compare VEGF-A values between pregnant women with coronavirus disease 2019 (COVID-19) and healthy controls. Furthermore, the association of inflammation parameters, disease severity, and obstetric complications with VEGF-A was investigated. This prospective case-control study was conducted on pregnant women who were admitted to Ankara City Hospital between June 14, 2020 and August 28, 2020. Pregnant women with COVID-19 (n = 95) were compared with a control group of healthy pregnant women (n = 92) with similar clinical and demographic characteristics. Demographic features, clinical characteristics, laboratory test results, VEGF-A values were compared between the groups. A correlation analysis was performed between VEGF-A levels, inflammation parameters, and clinical characteristics of the cases for pregnant women with COVID-19. VEGF-A levels were also compared between patients with composite adverse outcome and patients without any complication in the COVID-19 group. The two groups were similar except for obstetric complications (p > .05). The obstetric complication rate was higher in the COVID-19 group (p =.02). The two groups were comparable in terms of neutrophil to lymphocyte ratio and VEGF-A values. VEGF-A values were slightly different between the trimesters. A negative moderate statistically significant correlation was found between the neutrophil and VEGF-A values (r = -0.231, p =.02). VEGF-A values were similar between patients with and without composite adverse outcomes (p > .05). VEGF-A values were similar between pregnant women with COVID-19 and healthy controls.

Maternal Choline Supplementation Modulates Placental Markers of Inflammation, Angiogenesis, and Apoptosis in a Mouse Model of Placental Insufficiency

Dlx3 (distal-less homeobox 3) haploinsufficiency in mice has been shown to result in restricted fetal growth and placental defects. We previously showed that maternal choline supplementation (4X versus 1X choline) in the Dlx3+/− mouse increased fetal and placental growth in mid-gestation. The current study sought to test the hypothesis that prenatal choline would modulate indicators of placenta function and development. Pregnant Dlx3+/− mice consuming 1X (control), 2X, or 4X choline from conception were sacrificed at embryonic (E) days E10.5, E12.5, E15.5, and E18.5, and placentas and embryos were harvested. Data were analyzed separately for each gestational day controlling for litter size, fetal genotype (except for models including only +/− pups), and fetal sex (except when data were stratified by this variable). 4X choline tended to increase (p < 0.1) placental labyrinth size at E10.5 and decrease (p < 0.05) placental apoptosis at E12.5. Choline supplementation decreased (p < 0.05) expression of pro-angiogenic genes Eng (E10.5, E12.5, and E15.5), and Vegf (E12.5, E15.5); and pro-inflammatory genes Il1b (at E15.5 and 18.5), Tnfα (at E12.5) and Nfκb (at E15.5) in a fetal sex-dependent manner. These findings provide support for a modulatory effect of maternal choline supplementation on biomarkers of placental function and development in a mouse model of placental insufficiency.

Association of VEGFA gene polymorphisms and VEGFA plasma levels with spontaneous preterm birth

BACKGROUND

Angiogenic pathway regulating genes such as vascular endothelial growth factor A (VEGFA) have been implicated in preterm birth (PTB) complications. Research shows that the VEGFA/VEGF receptor system plays an important role in the regulation of circulating progesterone level. Attenuation of VEGFA signaling at mid pregnancy results in onset of labor and parturition because of a reduction in circulating progesterone levels. The aim of this study was to investigate the association of VEGFA gene polymorphisms (rs2010963, rs3025039, rs699947, and rs10434) with spontaneous PTB and VEGFA plasma levels in preterm and term women.

STUDY DESIGN

Peripheral maternal blood from 495 women was used for extraction of DNA and genotyping was carried out using the SequenomMassARRAY platform. Maternal plasma was used to measure VEGFA levels.

RESULTS

Results showed a significant association between rs2010963 variants and PTB at both allelic and genotypic levels. The frequencies of CG and GG genotypes were significantly higher in the preterm group (96%) than in the term group (87%) (P=0.012). The odds of the G allele occurring among the preterm group was 1.8 times higher than those in the term group (odds ratio 1.8, 95% confidence interval 1.2-2.6, P=0.003). After adjustment for Bonferroni correction, the association between rs2010963 variants and PTB remained significant (P=0.004). The rs69947 was associated with PTB at a nominal significance level (P=0.030). There was no significant association between rs3025039, rs10434, and PTB in this population. VEGFA gene polymorphisms were not associated with VEGFA plasma levels. This study indicated for the first time that the VEGFA rs2010963 polymorphisms may play a potential role in preterm complications.

The luteotrophic function of galectin-1 by binding to the glycans on vascular endothelial growth factor receptor-2 in bovine luteal cells

The corpus luteum (CL) is a temporary endocrine gland producing a large amount of progesterone, which is essential for the establishment and maintenance of pregnancy. Galectin-1 is a β-galactose-binding protein that can modify functions of membrane glycoproteins and is expressed in the CL of mice and women. However, the physiological role of galectin-1 in the CL is unclear. In the present study, we investigated the expression and localization of galectin-1 in the bovine CL and the effect of galectin-1 on cultured luteal steroidogenic cells (LSCs) with special reference to its binding to the glycans on vascular endothelial growth factor receptor-2 (VEGFR-2). Galectin-1 protein was highly expressed at the mid and late luteal stages in the membrane fraction of bovine CL tissue and was localized to the surface of LSCs in a carbohydrate-dependent manner. Galectin-1 increased the viability in cultured LSCs. However, the viability of LSCs was decreased by addition of β-lactose, a competitive carbohydrate inhibitor of galectin-1 binding activity. VEGFR-2 protein, like galectin-1, is also highly expressed in the mid CL, and it was modified by multi-antennary glycans, which can be recognized by galectin-1. An overlay assay using biotinylated galectin-1 revealed that galectin-1 directly binds to asparagine-linked glycans (N-glycans) on VEGFR-2. Enhancement of LSC viability by galectin-1 was suppressed by a selective inhibitor of VEGFR-2. The overall findings suggest that galectin-1 plays a role as a survival factor in the bovine CL, possibly by binding to N-glycans on VEGFR-2.

Luteal activity of pregnant rats with hypo-and hyperthyroidism

Background

Luteal activity is dependent on the interaction of various growth factors, cytokines and hormones, including the thyroid hormones, being that hypo- and hyperthyroidism alter the gestational period and are also a cause of miscarriage and stillbirth. Because of that, we evaluated the proliferation, apoptosis and expression of angiogenic factors and COX-2 in the corpus luteum of hypo- and hyperthyroid pregnant rats.

Methods

Seventy-two adult female rats were equally distributed into three groups: hypothyroid, hyperthyroid and control. Hypo- and hyperthyroidism were induced by the daily administration of propylthiouracil and L-thyroxine, respectively. The administration began five days before becoming pregnant and the animals were sacrificed at days 10, 14, and 19 of gestation. We performed an immunohistochemical analysis to evaluate the expression of CDC-47, VEGF, Flk-1 (VEGF receptor) and COX-2. Apoptosis was evaluated by the TUNEL assay. We assessed the gene expression of VEGF, Flk-1, caspase 3, COX-2 and PGF2α receptor using real time RT-PCR. The data were analyzed by SNK test.

Results

Hypothyroidism reduced COX-2 expression on day 10 and 19 (P < 0.05), endothelial/pericyte and luteal cell proliferation on day 10 and 14 (p < 0.05), apoptotic cell numbers on day 19 (p < 0.05) and the expression of Flk-1 and VEGF on day 14 and 19, respectively (p < 0.05). Hyperthyroidism increased the expression of COX-2 on day 19 (P < 0.05) and the proliferative activity of endothelial/pericytes cells on day 14 (p <0.05), as well as the expression of VEGF and Flk-1 on day 19 (P < 0.05).

Conclusions

Hypothyroidism reduces the proliferation, apoptosis and expression of angiogenic factors and COX-2in the corpus luteum of pregnant rats, contrary to what is observed in hyperthyroid animals, being this effect dependent of the gestational period.

Obese melanocortin-4 receptor-deficient rats exhibit augmented angiogenic balance and vasorelaxation during pregnancy

While obesity is a major risk factor for preeclampsia, the mechanisms linking obesity and hypertension during preeclampsia remain unclear. Hypertension in preeclampsia is associated with placental ischemia-induced release of anti-angiogenic soluble fms-like tyrosine kinase (sFlt-1) into the maternal circulation, which antagonizes vascular endothelial growth factor (VEGF) promoting endothelial dysfunction. Haploinsufficiency, defined as loss of one copy of a gene via a mutation, of the melanocortin-4 receptor (MC4R) is the most common cause of monogenetic obesity in humans. The purpose of our study was to determine the effects of genetic obesity on angiogenic balance, endothelial function, and blood pressure in pregnant MC4R+/- and MC4R+/+ rats. At gestational day (GD) 18, body weight and total body fat mass were greater in MC4R+/- than MC4R+/+ rats. On GD 19, plasma sFlt-1 was not significantly different between groups. Interestingly, circulating VEGF was greater in the obese rats with the source being adipose tissue and not the placenta. Wire myography showed in third-order mesenteric arteries that sensitivity (logEC50) to endothelial dependent and nitric oxide donor-induced vasorelaxation was greater in MC4R+/- versus MC4R+/+. Mean arterial blood pressure was similar between groups. In conclusion, under normal pregnant conditions, genetically obese pregnant animals have greater angiogenic balance and dependency of vasorelaxation on nitric oxide signaling protecting against the development of hypertension. However, we speculate that, in the face of reduced uterine perfusion, a rise in circulating placental factors that target and reduce nitric oxide bioavailability exposes the susceptibility of genetically obese animals to greater hypertension in pregnancy.

KRN633, an inhibitor of vascular endothelial growth factor receptor tyrosine kinase, induces intrauterine growth restriction in mice

We previously reported that treatment with KRN633, a vascular endothelial growth factor receptor tyrosine kinase inhibitor, during mid-pregnancy caused intrauterine growth restriction resulting from impairment of blood vessel growth in the labyrinthine zone of the placenta and fetal organs. However, the relative sensitivities of blood vessels in the placenta and fetal organs to vascular endothelial growth factor (VEGF) inhibitors have not been determined. In this study, we aimed to examine the effects of KRN633 on the vasculatures of organs in mother mice and their newborn pups by immunohistochemical analysis. Pregnant mice were treated daily with KRN633 (5 mg/kg) either from embryonic day 13.5 (E13.5) to E17.5 or from E13.5 to the day of delivery. The weights of the pups of KRN633-treated mice were lower than those of the pups of vehicle-treated mothers. However, no significant difference in body weight was observed between the vehicle- and KRN633-treated mice. The vascular development in the organs (the pancreas, kidney, and intestine) and intestinal lymphatic formation of the pups of KRN633-treated mothers was markedly impaired. In contrast, the KRN633 treatment showed no significant effect on the vascular beds in the organs, including the labyrinthine zone of the placenta, of the mother mice. These results suggest that blood vessels in fetal organs are likely to be more sensitive to reduced VEGF signaling than those in the mother. A partial loss of VEGF function during pregnancy could suppress vascular growth in the fetus without affecting the vasculature in the mother mouse, thereby increasing the risk of intrauterine growth restriction.