An examination of the mechanisms driving the therapeutic effects of an AAV expressing a soluble variant of VEGF receptor-1.

In previous animal model studies, we demonstrated the potential of rAAV2-sVEGFRv-1, which encodes a truncated variant of the alternatively spliced soluble version of VEGF receptor-1 (VEGFR1), as a human gene therapy for age-related macular degeneration (AMD) and diabetic retinopathy (DR). Here, we elucidate in vitro some of the mechanisms by which rAAV2-sVEGFRv-1 exerts its therapeutic effects. Human umbilical vein endothelial cells (HUVECs) were infected with rAAV2-sVEGFRv-1 or a control virus vector in the presence of members of the VEGF family to identify potential binding partners via ELISA, which showed that VEGF-A, VEGF-B, and placental growth factor (PlGF) are all ligands of its transgene product. In order to determine the effects of rAAV2-sVEGFRv-1 on cell proliferation and permeability, processes that are important to the progression AMD and DR, HUVECs were infected with the therapeutic virus vector under the stimulation of VEGF-A, the major driver of the neovascularization that characterizes the forms of these conditions most associated with vision loss. rAAV2-sVEGFRv-1 treatment, as a result, markedly reduced the extent to which these processes occurred, with the latter determined by measuring zonula occludens 1 expression. Finally, the human microglial HMC3 cell line was used to show the effects of the therapeutic virus vector upon inflammatory processes, another major contributor to angiogenic eye disease pathophysiology, with rAAV2-sVEGFRv-1 reducing therein the secretion of pro-inflammatory cytokines interleukin (IL)-1ß and IL-6. Combined with our previously published in vivo data, the in vitro activity of the expressed transgene here further demonstrates the great promise of rAAV2-sVEGFRv-1 as a potential human gene therapeutic for addressing angiogenic ocular conditions.

Endothelial cell signature in muscle stem cells validated by VEGFA-FLT1-AKT1 axis promoting survival of muscle stem cell.

Endothelial and skeletal muscle lineages arise from common embryonic progenitors. Despite their shared developmental origin, adult endothelial cells (ECs) and muscle stem cells (MuSCs; satellite cells) have been thought to possess distinct gene signatures and signaling pathways. Here, we shift this paradigm by uncovering how adult MuSC behavior is affected by the expression of a subset of EC transcripts. We used several computational analyses including single-cell RNA-seq (scRNA-seq) to show that MuSCs express low levels of canonical EC markers in mice. We demonstrate that MuSC survival is regulated by one such prototypic endothelial signaling pathway (VEGFA-FLT1). Using pharmacological and genetic gain- and loss-of-function studies, we identify the FLT1-AKT1 axis as the key effector underlying VEGFA-mediated regulation of MuSC survival. All together, our data support that the VEGFA-FLT1-AKT1 pathway promotes MuSC survival during muscle regeneration, and highlights how the minor expression of select transcripts is sufficient for affecting cell behavior.

Tumor Infiltrating Effector Regulatory T Cells Express VEGF Receptor 2 in Patients With Colorectal Cancer.

BACKGROUND/AIM: Regulatory T cells (Tregs) suppress various anti-tumor immune responses in the tumor microenvironment (TME) and their control is considered essential to enhancing efficacy of cancer immunotherapy. The purpose of the study was to evaluate the strategy to regulate Tregs through the vascular endothelial growth factor (VEGF) pathway. MATERIALS AND METHODS: We evaluated VEGF receptor (VEGFR) expression in subtypes of Tregs by analysis of public databases and through flow cytometry by investigating surgically resected specimens and peripheral blood mononuclear cells (PBMCs) from 26 patients with advanced colorectal cancer (CRC). RESULTS: Analysis of The Cancer Genome Atlas colorectal adenocarcinoma dataset (n=592) showed that mRNA expression of both FLT1 (VEGFR1) and KDR (VEGFR2) was positively correlated with mRNA expression of FOXP3 as well as Treg signature. Clinical specimens revealed abundant VEGFR2 expression on Tregs, but very marginal VEGFR1 expression. The frequency of effector Tregs, the most immunosuppressive fraction of Tregs, was significantly higher in the tumor than in the PBMC and normal mucosa, and the majority of effector Tregs expressed VEGFR2. Furthermore, by using in vitro generated Tregs, the proportion of Tregs expressing IL-10 or TGF-ß1 was significantly inhibited by a VEGFR2 inhibitor. CONCLUSION: A therapeutic strategy targeting the VEGFR2 axis may have a potential to control effector Tregs in the CRC-TME.

sFlt-1 impairs neurite growth and neuronal differentiation in SH-SY5Y cells and human neurons.

Pre-eclampsia (PE) is a hypertensive disorder of pregnancy which is associated with increased risk of neurodevelopmental disorders in exposed offspring. The pathophysiological mechanisms mediating this relationship are currently unknown, and one potential candidate is the anti-angiogenic factor soluble Fms-like tyrosine kinase 1 (sFlt-1), which is highly elevated in PE. While sFlt-1 can impair angiogenesis via inhibition of VEGFA signalling, it is unclear whether it can directly affect neuronal development independently of its effects on the vasculature. To test this hypothesis, the current study differentiated the human neural progenitor cell (NPC) line ReNcell® VM into a mixed culture of mature neurons and glia, and exposed them to sFlt-1 during development. Outcomes measured were neurite growth, cytotoxicity, mRNA expression of nestin, MBP, GFAP, and ßIII-tubulin, and neurosphere differentiation. sFlt-1 induced a significant reduction in neurite growth and this effect was timing- and dose-dependent up to 100 ng/ml, with no effect on cytotoxicity. sFlt-1 (100 ng/ml) also reduced ßIII-tubulin mRNA and neuronal differentiation of neurospheres. Undifferentiated NPCs and mature neurons/glia expressed VEGFA and VEGFR-2, required for endogenous autocrine and paracrine VEGFA signalling, while sFlt-1 treatment prevented the neurogenic effects of exogenous VEGFA. Overall, these data provide the first experimental evidence for a direct effect of sFlt-1 on neurite growth and neuronal differentiation in human neurons through inhibition of VEGFA signalling, clarifying our understanding of the potential role of sFlt-1 as a mechanism by which PE can affect neuronal development.

Gene expression of iron transporters, markers of vascularization and structural integrity in placenta of mothers with and without anemia.

OBJECTIVE: To compare the mRNA expression of placental iron transporters (TfR-1 and FPN), markers of placental vascularization (VEGF and sFLT1) and marker of structural integrity (LMN-A) in term women with and without iron deficiency anemia. MATERIALS AND METHODS: A total of 30 pregnant women were enrolled; 15 cases of iron deficiency anemia (Hb 7-10.9 gm/dL) and 15 gestational age matched healthy controls (Hb ≥ 11 gm/dL). Peripheral venous blood was collected for assessment of hemoglobin levels and serum iron profile. Placental tissue was used for assessing the mRNA expression of TfR-1, FPN, VEGF, sFLT-1 and LMN-A via real time PCR. RESULTS: Placental expression of TfR-1, VEGF and LMN-A was increased in pregnant women with anemia compared to healthy pregnant controls. Placental expression of sFLT-1 was decreased in pregnant women with anemia compared to healthy pregnant controls. There was no change in the placental expression of FPN. CONCLUSION: The increased expression of TfR-1, VEGF and LMN-A in cases of iron deficiency anemia are most likely to be compensatory in nature to help maintain adequate fetal iron delivery. WHAT DOES THIS STUDY ADDS TO THE CLINICAL WORK: Compensatory changes in the placenta aimed at buffering transport of iron to the fetus are seen in pregnant women with anemia compared to healthy pregnant controls.

Geniposide alleviates imiquimod-induced psoriasis-like skin lesions in mice via inhibition of angiogenesis.

In this study, we aimed to evaluate the protective effect of geniposide (GEN) on imiquimod (IMQ)-induced psoriasis-like skin lesions in mice. Firstly, visual changes of psoriatic skin lesions were observed and the severity was recorded using psoriasis area and severity index (PASI) score. Histological changes were assessed by HE staining for epidermal thickness and Masson's staining for collagen fibers. Then, photographs of microvascular inside the skin were taken for macroscopic observation, and microscopic changes associated with angiogenesis were evaluated. Furthermore, expression of angiogenic factors were analyzed by ELISA, immunohistochemistry and immunofluorescence, separately. Lastly, the expression of VEGFR signaling-related proteins was detected by WB. Compared with control, IMQ drove a significant increment of epidermal thicknesses with higher PASI scores and more dermal collagen deposition. IMQ treatment led to abnormal keratinocyte proliferation, increased microvascular inside skin, growing production of angiogenesis-related factors, up-regulated expression of VEGFR1 and VEGFR2, and enhanced phosphorylation of p38. However, GEN significantly ameliorated the psoriatic skin lesions, the epidermal thickness, the formation of collagen fibers, and abnormal keratinocyte proliferation. Importantly, GEN inhibited angiogenesis, the production of angiogenic factors (VEGF-A, Ang-2, TNF-α, and IL-17A), and the proliferation of vascular endothelial cells. Simultaneously, GEN curbed the expression of VEGFR1, VEGFR2, p38, and P-p38 proteins involved in VEGFR signaling. Of note, the suppressive effect of GEN was reversed in the HUVECs with over-expressed VEGFR1 or VEGFR2 related to the cells without transfection. These findings suggest that VEGFR1 and VEGFR2 participate in the anti-angiogenesis of GEN in IMQ-induced psoriasis-like skin lesions in mice.

Ghrelin alleviates placental dysfunction by down-regulating NF-κB phosphorylation in LPS-induced rat model of preeclampsia.

In our previous study, we uncovered that ghrelin promotes angiogenesis in human umbilical vein endothelial cells (HUVECs) in vitro by activating the Jagged1/Notch2/VEGF pathway in preeclampsia (PE). However, the regulatory effects of ghrelin on placental dysfunction in PE are unclear. Therefore, we applied Normal pregnant Sprague-Dawley (SD) rats, treated with lipopolysaccharide (LPS), to establish a PE-like rat model. The hematoxylin-eosin (HE) staining method and immunohistochemistry (IHC) technology were used to detect morphological features of the placenta. IHC and Western blot were applied to examine Bax and Bcl-2 expression levels. The concentrations of serum soluble fms-like tyrosine kinase-1 (sFlt1) and placental growth factor (PIGF) were assessed by enzyme-linked immunosorbent assay (ELISA) kit. In addition, the apoptosis rates of JEG-3 and HTR-8/SVneo trophoblast cells were determined by Annexin V-FITC/PI apoptosis detection kit. Cell migratory capacities were assessed by scratch-wound assay, and RNA-sequencing assay was used to determine the mechanism of ghrelin in regulating trophoblast apoptosis. It has been found that ghrelin significantly reduced blood pressure, urinary protein, and urine creatinine in rats with PE, at the meanwhile, ameliorated placental and fetal injuries. Second, ghrelin clearly inhibited placental Bax expression and circulating sFlt-1 as well as elevated placental Bcl-2 expression and circulating PIGF, restored apoptosis and invasion deficiency of trophoblast cells caused by LPS in vitro. Finally, transcriptomics indicated that nuclear factor kappa B (NF-κB) was the potential downstream pathway of ghrelin. Our findings illustrated that ghrelin supplementation significantly improved LPS-induced PE-like symptoms and adverse pregnancy outcomes in rats by alleviating placental apoptosis and promoting trophoblast migration.

Establishment of a placental lncRNA-mRNA expression network for early-onset preeclampsia.

BACKGROUND: This study aimed to establish a placental long non-coding RNA (lncRNA)-mRNA expression network for early-onset preeclampsia (early-onset PE). METHODS: The RNA sequencing data of the GSE14821 dataset were acquired. Several crucial lncRNAs and mRNAs were exerted based on the differential expression analysis of lncRNA and mRNA. By analyzing the differentially expressed lncRNA and mRNA, we constructed a regulatory network to explore the mechanism of the lncRNA in early onset preeclampsia. RESULTS: A total of 4436 differentially expressed lncRNAs (DElncRNAs) were identified in early-onset PE placenta samples compared with control placenta samples. Pearson correlation analysis revealed significant correlations between 3659 DElncRNAs and 372 DEmRNAs. KEGG analysis showed that the DEmRNAs were enriched in cytokine-cytokine receptor and hypoxia-inducible factor (HIF)-1 pathways. Several well-known early-onset PE-related mRNAs, such as vascular endothelial growth factor A (VEGFA) and VEGF receptor 1 (FLT1), were involved in the two pathways. Weighted gene co-expression network analysis and cis-regulatory analysis further suggested the involvement of the two pathways and potential DElncRNA-DEmRNA interactions in early-onset PE. Moreover, the upregulation of representative DElncRNAs, such as RP11-211G3.3 and RP11-65J21.3, and DEmRNAs, such as VEGFA and FLT1, were validated in clinical placenta samples from patients with early-onset PE by quantitative reverse transcription PCR. Importantly, overexpression of RP11-65J21.3 significantly promoted the proliferation of HTR-8 trophoblast cells at 72 h after transfection. CONCLUSIONS: In conclusion, we identified placental DElncRNAs of early-onset PE and established a DElncRNA-DEmRNA network that was closely related to the cytokine-cytokine receptor and HIF-1 pathways. Our results provide potential diagnostic markers and therapeutic targets for early-onset PE management.

Prediction of preeclampsia using maternal circulating mRNAs in early pregnancy.

PURPOSE: Preeclampsia (PE) is one of the most common and serious complications of pregnancy, and novel methods for the early prediction of PE are needed for clinical application. METHODS: In this study, a circulating cell-free RNA (cfRNA) panel of target genes for PE prediction was designed and validated in a case-control cohort and a nested case-control cohort. The QPCR was applied to quantify the copy number of cfRNA, and the data were normalized as multiples of the median. Ratios of serum placental growth factor (PIGF) and soluble fms-like tyrosine kinase 1 (sFLT-1) were also measured, and transabdominal ultrasonography was conducted for subjects in the prospective cohort. Binary logistic regression models for PE prediction were constructed and tested. RESULTS: Our results revealed that the women with PE showed significant alterations in serum cfRNA profiles from early pregnancy onward and before the onset of PE symptoms. Compared with PIGF/sFLT-1 measurement and ultrasonographic imaging, cfRNA test can detect PE at a very early stage of pregnancy. The predictive model exhibited the best performance at gestation week 32, with a detection rate of 100%. At 12 weeks of gestation, the model still manifested an area under curve (AUC) of 0.9144, and sensitivity of 1.0000. If combined with clinical parameters and ultrasonographic indicators, the model can achieve the highest AUC for PE prediction at early gestation. CONCLUSION: Measurement of cfRNA can be used to effectively predict PE with high performance, providing an additional method for monitoring PE throughout the course of pregnancy.

Prior Exposure to Experimental Preeclampsia Increases Atherosclerotic Plaque Inflammation in Atherogenic Mice-Brief Report.

BACKGROUND: Women with a history of preeclampsia have evidence of premature atherosclerosis and increased risk of myocardial infarction and stroke compared with women who had a normotensive pregnancy. Whether this is due to common risk factors or a direct impact of prior preeclampsia exposure has never been tested in a mouse atherosclerosis model. METHODS: Pregnant LDLR-KO (low-density lipoprotein receptor knockout; n=35) female mice were randomized in midgestation to sFlt1 (soluble fms-like tyrosine kinase 1)-expressing adenovirus or identical control adenovirus. Postpartum, mice were fed high-fat diet for 8 weeks to induce atherogenesis. Comparison between the control and preeclampsia models was made for metabolic parameters, atherosclerosis burden and composition by histology, plaque inflammation by flow cytometry, and aortic cytokines and inflammatory markers using a cytokine array. RESULTS: In pregnant LDLR-KO mice, sFlt1 adenovirus significantly induced serum sFlt1, blood pressure, renal endotheliosis, and decreased pup viability. After 8 weeks of postpartum high fat feeding, body weight, fasting glucose, plasma cholesterol, HDL (high-density lipoprotein), and LDL (low-density lipoprotein) were not significantly different between groups with no change in aortic root plaque size, lipid content, or necrotic core area. Flow cytometry demonstrated significantly increased CD45+ aortic arch leukocytes and CD3+T cells and aortic lysate contained more CCL (CC motif chemokine ligand) 22 and fetuin A and decreased expression of IGFBP6 (insulin-like growth factor-binding protein 6) and CCL21 in preeclampsia-exposed mice compared with controls. CONCLUSIONS: In atherogenic LDLR-KO mice, exposure to sFlt1-induced preeclampsia during pregnancy increases future atherosclerotic plaque inflammation, supporting the concept that preeclampsia directly exacerbates atherosclerotic inflammation independent of preexisting risk factors. This mechanism may contribute to ischemic vascular disease in women after preeclampsia pregnancy.

Overexpression of Human sFLT1 in the Spongiotrophoblast Is Sufficient to Induce Placental Dysfunction and Fetal Growth Restriction in Transgenic Mice.

Preeclampsia (PE) is characterized by maternal hypertension and placental dysfunction, often leading to fetal growth restriction (FGR). It is associated with an overexpression of the anti-angiogenic sFLT1 protein, which originates from the placenta and serves as a clinical biomarker to predict PE. To analyze the impact of sFLT1 on placental function and fetal growth, we generated transgenic mice with placenta-specific human sFLT1 (hsFLT1) overexpression. Immunohistochemical, morphometrical, and molecular analyses of the placentas on 14.5 dpc and 18.5 dpc were performed with a focus on angiogenesis, nutrient transport, and inflammation. Additionally, fetal development upon placental hsFLT1 overexpression was investigated. Dams exhibited a mild increase in serum hsFLT1 levels upon placental hsFLT1 expression and revealed growth restriction of the fetuses in a sex-specific manner. Male FGR fetuses expressed higher amounts of placental hsFLT1 mRNA compared to females. FGR placentas displayed an altered morphology, hallmarked by an increase in the spongiotrophoblast layer and changes in labyrinthine vascularization. Further, FGR placentas showed a significant reduction in placental glycogen storage and nutrient transporter expression. Moreover, signs of hypoxia and inflammation were observed in FGR placentas. The transgenic spongiotrophoblast-specific hsFLT1 mouse line demonstrates that low hsFLT1 serum levels are sufficient to induce significant alterations in fetal and placental development in a sex-specific manner.

Molecular basis of VEGFR1 autoinhibition at the plasma membrane.

Ligand-independent activation of VEGFRs is a hallmark of diabetes and several cancers. Like EGFR, VEGFR2 is activated spontaneously at high receptor concentrations. VEGFR1, on the other hand, remains constitutively inactive in the unligated state, making it an exception among VEGFRs. Ligand stimulation transiently phosphorylates VEGFR1 and induces weak kinase activation in endothelial cells. Recent studies, however, suggest that VEGFR1 signaling is indispensable in regulating various physiological or pathological events. The reason why VEGFR1 is regulated differently from other VEGFRs remains unknown. Here, we elucidate a mechanism of juxtamembrane inhibition that shifts the equilibrium of VEGFR1 towards the inactive state, rendering it an inefficient kinase. The juxtamembrane inhibition of VEGFR1 suppresses its basal phosphorylation even at high receptor concentrations and transiently stabilizes tyrosine phosphorylation after ligand stimulation. We conclude that a subtle imbalance in phosphatase activation or removing juxtamembrane inhibition is sufficient to induce ligand-independent activation of VEGFR1 and sustain tyrosine phosphorylation.

Gasdermin D regulates soluble fms-like tyrosine kinase 1 release in macrophages.

Preeclampsia (PE) is a serious complication, and soluble fms-like tyrosine kinase (sFLT1) released from the placenta is one of the causes of PE pathology. Trophoblasts are the primary source of sFLT1; however, monocytes/macrophages exist enough in the placenta can also secrete sFLT1. Sterile inflammatory responses, especially NLRP3 inflammasome and its downstream gasdermin D (GSDMD)-regulated pyroptosis, may be involved in the development of PE pathology. In this study, we investigated whether human monocyte/macrophage cell line THP-1 cells secrete sFLT1 depending on the NLRP3 inflammasome and GSDMD. To differentiate THP-1 monocytes into macrophages, treatment with phorbol 12-myristate 13-acetate (PMA) induced sFLT1 with interleukin (IL)- 1ß, but did not induce cell lytic death. IL-1ß secretion induced by PMA inhibited by deletion of NLRP3 and inhibitors of NLRP3 and caspase-1, but deletion of NLRP3 and these inhibitors did not affect sFLT1 secretion in THP-1 cells. Both gene deletion and inhibition of GSDMD dramatically decreased IL-1ß and sFLT1 secretion from THP-1 cells. Treatment with CA074-ME (a cathepsin B inhibitor) also reduced the secretion of both sFLT1 and IL-1ß in THP-1 cells. In conclusion, THP-1 macrophages release sFLT1 in a GSDMD-dependent manner, but not in the NLRP3 inflammasome-dependent manner, and this sFLT1 release may be associated with the non-lytic role of GSDMD. In addition, sFLT1 levels induced by PMA are associated with lysosomal cathepsin B in THP-1 macrophages. We suggest that sFLT1 synthesis regulated by GSDMD are involved in the pathology of PE.

Morphological evaluation of the feline placenta correlates with gene expression of vascular growth factors and receptors†.

Placental angiogenesis is critical for normal development. Angiogenic factors and their receptors are key regulators of this process. Dysregulated placental vascular development is associated with pregnancy complications. Despite their importance, vascular growth factor expression has not been thoroughly correlated with placental morphologic development across gestation in cats. We postulate that changes in placental vessel morphology can be appreciated as consequences of dynamic expression of angiogenic signaling agents. Here, we characterized changes in placental morphology alongside expression analysis of angiogenic factor splice variants and receptors throughout pregnancy in domestic shorthair cats. We observed increased vascular and lamellar density in the lamellar zone during mid-pregnancy. Immunohistochemical analysis localized the vascular endothelial growth factor A (VEGF-A) receptor KDR to endothelial cells of the maternal and fetal microvasculatures. PlGF and its principal receptor Flt-1 were localized to the trophoblasts and fetal vasculature. VEGF-A was found in trophoblast cells and associated with endothelial cells. We detected expression of two Plgf splice variants and four Vegf-a variants. Quantitative real-time polymerase chain reaction analysis showed upregulation of mRNAs encoding pan Vegf-a and all Vegf-a splice forms at gestational days 30-35. Vegf-A showed a marked relative increase in expression during mid-pregnancy, consistent with the pro-angiogenic changes seen in the lamellar zone at days 30-35. Flt-1 was upregulated during late pregnancy. Plgf variants showed stable expression during the first two-thirds of pregnancy, followed by a marked increase toward term. These findings revealed specific spatiotemporal expression patterns of VEGF-A family members consistent with pivotal roles during normal placental development.

Expression and Function of VEGFRs in Normal Epidermis and Psoriatic Lesional Keratinocytes.

The study aimed to explore the expression and function of VEGFRs in normal epidermis and keratinocytes of psoriatic lesions. In this study, the expression and role of VEGFRs in keratinocytes were examined using examples from psoriatic and healthy individuals. The experiment was completed by immunofluorescence analysis, reverse transcription polymerase chain reaction, Western blot, and real-time quantitative RT-PCR after the skin of nonlesional, adjacent, and lesional skin was excised. Observations indicated that in non-lesional psoriatic areas and adjacent lesional areas of the skin of psoriasis patients, the fluorescent signals of VEGFR-1 and VEGFR-2 were strongly labelled with keratinocytes, and in psoriatic lesions, keratinocytes were present throughout the entire thickness of the epidermis, with the exception of the stratum corneum. The distribution of VEGFR-3 in psoriatic nonlesional and adjacent lesional skin was consistent with that in normal epidermis, whereas all layers of the epidermis of psoriatic lesions expressed VEGFR-3. The mRNA expression levels of VEGFR-1,2,3 steadily increased from the normal epidermis to the psoriatic nonlesional, adjacent lesional, and perilesional areas, with the lesional epidermis' keratinocytes exhibiting the greatest levels of mRNA expression. Ca ions upregulate VEGFR-1,2,3 mRNA and protein expression in keratinocytes of nonlesional areas of psoriasis. VEGFRs protein expression and cortical IOD values of psoriatic and normal population cells showed a positive correlation. Hence, in comparison to normal epidermal keratinocytes, psoriatic lesional regions' keratinocytes considerably enhanced their expression of VEGFR-1,2,3 mRNA and protein. The overexpression of VEGFR-1,2,3 in psoriatic lesions may be encouraged by VEGF and Ca þ ions.

The role of genetics in maternal susceptibility to preeclampsia in women of African ancestry.

Racial disparities exist in the prevalence of preeclampsia (PE), with women of African ancestry suffering the highest rates of morbidity and mortality. Genetic changes may play a role in the preponderance of PE among women of African ancestry. This review discusses 30 genes with variants that have been studied in PE in women of African ancestry. These studies found that a single gene is not responsible for PE susceptibility as 13 genes have been implicated. These genes subserve endothelial, immune, hemodynamic, homeostatic, thrombophilic, oxidative stress, and lipid metabolic pathways. Notably, maternal-fetal gene interactions also contribute to the susceptibility of the disease. For instance, the maternal KIR AA genotype and paternally inherited fetal HLA-C2 genotype confer risk for developing PE. Additionally, genetic changes such as epigenetic modulation of expression of the MTHFR gene through DNA methylation is also associated with the occurrence of PE. In contrast, some genes such as the KIR B centromeric region protect against development of PE in some women. The soluble fms-like tyrosine kinase 1 (sFlt-1) contributes to the development of PE and is a potential novel therapeutic option for targeted gene silencing of anti-angiogenic sFLT-1 gene. Additionally, NOS3 gene is an important target for pharmacogenomics because it is responsible for the production of endothelial nitric oxide. In conclusion, maternal genetic and epigenetic variants confer susceptibility to PE, indicating the need for further studies to develop a screening tool incorporating maternal genetic variants to identify women at high risk for PE and offer them a preventive therapy.

Human umbilical cord mesenchymal stem cell derived exosomes (HUCMSC-exos) recovery soluble fms-like tyrosine kinase-1 (sFlt-1)-induced endothelial dysfunction in preeclampsia.

BACKGROUND: Preeclampsia is a unique multisystem disorder that affects 5-8% of pregnancies. A high level of soluble fms-like tyrosine kinase-1 (sFlt-1) is a hallmark of preeclampsia that causes endothelial dysfunction. Exosomes derived from mesenchymal stem cells (MSCs) have been indicated to improve endothelial performances by transporting signals to target cells. We hypothesized that exosomes derived from MSCs have potential effects against preeclampsia. METHODS: We collected human umbilical cord MSC-derived exosomes (HUCMSC-exos) by ultracentrifugation. The size and morphology of the exosomes were examined using a transmission electron microscope and nanoparticle tracking analysis. Pregnant mice were injected with murine sFlt-1 adenovirus to build the preeclampsia-like mouse model and then treated with HUCMSC-exos. Human umbilical vein endothelial cells (HUVECs) were infected with lentiviruses expressing tet-on-sFlt-1 to obtain cells overexpressing sFlt-1. Cell proliferation and migration assays were used to measure the endothelial functions. The exosomes enriched proteins underlying mechanisms were explored by proteomic analysis. RESULTS: In the current study, we successfully collected the cup-shaped HUCMSC-exos with diameters of 30-150 nm. In the sFlt-1-induced preeclampsia mouse model, HUCMSC-exos exhibited beneficial effects on adverse birth events by decreasing blood pressure and improving fetal birth weight. In addition, preeclamptic dams that were injected with HUCMSC-exos had rebuilt dense placental vascular networks. Furthermore, we observed that HUCMSC-exos partially rescued sFlt-1-induced HUVECs dysfunction in vitro. Proteomics analysis of HUCMSC-exos displayed functional enrichment in biological processes related to vesicle-mediated transport, cell communication, cell migration, and angiogenesis. CONCLUSION: We propose that exosomes derived from HUCMSCs contain abundant Versican and play beneficial roles in the birth outcomes of sFlt-1-induced preeclamptic mice by promoting angiogenesis.

Flt1 produced by lung endothelial cells impairs ATII cell transdifferentiation and repair in pulmonary fibrosis.

Pulmonary fibrosis is a devastating disease, in which fibrotic tissue progressively replaces lung alveolar structure, resulting in chronic respiratory failure. Alveolar type II cells act as epithelial stem cells, being able to transdifferentiate into alveolar type I cells, which mediate gas exchange, thus contributing to lung homeostasis and repair after damage. Impaired epithelial transdifferentiation is emerging as a major pathogenetic mechanism driving both onset and progression of fibrosis in the lung. Here, we show that lung endothelial cells secrete angiocrine factors that regulate alveolar cell differentiation. Specifically, we build on our previous data on the anti-fibrotic microRNA-200c and identify the Vascular Endothelial Growth Factor receptor 1, also named Flt1, as its main functional target in endothelial cells. Endothelial-specific knockout of Flt1 reproduces the anti-fibrotic effect of microRNA-200c against pulmonary fibrosis and results in the secretion of a pool of soluble factors and matrix components able to promote epithelial transdifferentiation in a paracrine manner. Collectively, these data indicate the existence of a complex endothelial-epithelial paracrine crosstalk in vitro and in vivo and position lung endothelial cells as a relevant therapeutic target in the fight against pulmonary fibrosis.

Vascular Endothelial Growth Factor Receptor 1 Targeting Fusion Polypeptides with Stimuli-Responsiveness for Anti-angiogenesis.

Genetically engineered fusion polypeptides have been investigated to introduce unique bio-functionality and improve some therapeutic activity for anti-angiogenesis. We report herein that stimuli-responsive, vascular endothelial growth factor receptor 1 (VEGFR1) targeting fusion polypeptides composed of a VEGFR1 (fms-like tyrosine kinase-1 (Flt1)) antagonist, an anti-Flt1 peptide, and a thermally responsive elastin-based polypeptide (EBP) were rationally designed at the genetic level, biosynthesized, and purified by inverse transition cycling to develop potential anti-angiogenic fusion polypeptides to treat neovascular diseases. A series of hydrophilic EBPs with different block lengths were fused with an anti-Flt1 peptide, forming anti-Flt1-EBPs, and the effect of EBP block length on their physicochemical properties was examined. While the anti-Flt1 peptide decreased phase-transition temperatures of anti-Flt1-EBPs, compared with EBP blocks, anti-Flt1-EBPs were soluble under physiological conditions. The anti-Flt1-EBPs dose dependently inhibited the binding of VEGFR1 against vascular endothelial growth factor (VEGF) as well as tube-like network formation of human umbilical vein endothelial cells under VEGF-triggered angiogenesis in vitro because of the specific binding between anti-Flt1-EBPs and VEGFR1. Furthermore, the anti-Flt1-EBPs suppressed laser-induced choroidal neovascularization in a wet age-related macular degeneration mouse model in vivo. Our results indicate that anti-Flt1-EBPs as VEGFR1-targeting fusion polypeptides have great potential for efficacious anti-angiogenesis to treat retinal-, corneal-, and choroidal neovascularization.

MIF Increases sFLT1 Expression in Early Uncomplicated Pregnancy and Preeclampsia.

Insufficient immune tolerance during pregnancy is associated with pathological conditions such as preeclampsia (PE). Soluble fms-like tyrosine kinase-1 (sFLT1), which exerts a role in the late stage of PE, has shown its beneficial anti-inflammatory effects in inflammation-associated diseases. Macrophage migration inhibitory factor (MIF) was reported to upregulate sFLT1 production in experimental congenital diaphragmatic hernia. However, the placental sFLT1 expression in early uncomplicated pregnancy and whether MIF can regulate sFLT1 expression in uncomplicated and preeclamptic pregnancy are unclear. We collected first-trimester placentas and term placentas from uncomplicated and preeclamptic pregnancies to investigate sFLT1 and MIF expression in vivo. Primary cytotrophoblasts (CTBs) and a human trophoblast cell line (Bewo) were used to study the regulation of MIF on sFLT1 expression in vitro. In placentas from first-trimester pregnancy, we observed a high expression of sFLT1, specifically in extravillous trophoblasts (EVTs) and syncytiotrophoblast (STB) cells. MIF mRNA levels strongly correlated with sFLT1 expression in term placentas from preeclamptic pregnancies. In in vitro experiments, sFLT1 and MIF levels increased significantly in CTBs during their differentiation to EVTs and STBs, and MIF inhibitor (ISO-1) significantly reduced sFLT1 expression in a dose-dependent manner during this process. sFLT1 showed significant upregulation with increasing doses of MIF in Bewo cells. Our results show that sFLT1 is highly expressed at the maternal-fetal interface during early pregnancy and that MIF can increase sFLT1 expression in early uncomplicated pregnancy and PE, which suggests that sFLT1 plays an essential role in the modulation of inflammation in pregnancy.