Notch3 signaling activation in smooth muscle cells promotes extrauterine growth restriction-induced pulmonary hypertension

Inhibition of Notch3/Hey1 ameliorates peribiliary hypoxia by preventing hypertrophic hepatic arteriopathy in biliary atresia progression

Emerging evidence indicates the presence of vascular abnormalities and ischemia in biliary atresia (BA), although specific mechanisms remain undefined. This study examined both human and experimental BA. Structural and hemodynamic features of hepatic arteries were investigated by Doppler ultrasound, indocyanine green angiography, microscopic histology, and invasive arterial pressure measurement. Opal multiplex immunohistochemistry, western blot, and RT-PCR were applied to assess Notch3 expression and the phenotype of hepatic arterial smooth muscle cells (HASMCs). We established animal models of Notch3 inhibition, overexpression, and knockout to evaluate the differences in overall survival, hepatic artery morphology, peribiliary hypoxia, and HASMC phenotype. Hypertrophic hepatic arteriopathy was evidenced by an increased wall-to-lumen ratio and clinically manifested as hepatic arterial hypertension, decreased hepatic artery perfusion, and formation of hepatic subcapsular vascular plexuses (HSVPs). We observed a correlation between overactivation of Notch3 and phenotypic disruption of HASMCs with the exacerbation of peribiliary hypoxia. Notch3 signaling mediated the phenotype alteration of HASMCs, resulting in arterial wall thickening and impaired oxygen supply in the portal microenvironment. Inhibition of Notch3/Hey1 ameliorates portal hypoxia by restoring the balance of contractile/synthetic HASMCs, thereby preventing hypertrophic arteriopathy in BA.

Naked cuticle homolog 1 prevents mouse pulmonary arterial hypertension via inhibition of Wnt/β-catenin and oxidative stress

Pulmonary arterial hypertension (PAH) is a poorly prognostic cardiopulmonary disease characterized by abnormal contraction and remodeling of pulmonary artery (PA). Excessive proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs) are considered as the major etiology of PA remodeling. As a negative regulator of Wnt/β-catenin pathway, naked cuticle homolog 1 (NKD1) is originally involved in the tumor growth and metastasis via affecting the proliferation and migration of different types of cancer cells. However, the effect of NKD1 on PAH development has not been investigated. In the current study, downregulated NKD1 was identified in hypoxia-challenged PASMCs. NKD1 overexpression by adenovirus carrying vector encoding Nkd1 (Ad-Nkd1) repressed hypoxia-induced proliferation and migration of PASMCs. Mechanistically, upregulating NKD1 inhibited excessive reactive oxygen species (ROS) generation and β-catenin expression in PASMCs after hypoxia stimulus. Both inducing ROS and recovering β-catenin expression abolished NKD1-mediated suppression of proliferation and migration in PASMCs. In vivo, we also observed decreased expression of NKD1 in dissected PAs of monocrotaline (MCT)-induced PAH model. Upregulating NKD1 by Ad-Nkd1 transfection attenuated the increase in right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), pulmonary vascular wall thickening, and vascular β-catenin expression after MCT treatment. After recovering β-catenin expression by SKL2001, the vascular protection of external expression of NKD1 was also abolished. Taken together, our data suggest that NKD1 inhibits the proliferation, migration of PASMC, and PAH via inhibition of β-catenin and oxidative stress. Thus, targeting NKD1 may provide novel insights into the prevention and treatment of PAH.

Inhibition of PCSK9 Improves the Development of Pulmonary Arterial Hypertension Via Down-Regulating Notch3 Expression

BACKGROUND

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by continuous constriction and occlusion of small pulmonary arteries, leading to the development of right ventricular failure and death. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a kind of serine protease enzyme that increases low-density lipoprotein cholesterol (LDLC) levels through degrading low-density lipoprotein cholesterol receptors (LDLr). However, whether inhibition of PCSK9 can alleviate PAH has not been reported.

METHODS AND RESULTS

We reported that PCSK9 expression was up-regulated in lung tissues of PAH patients. In addition, we used PCSK9 monoclonal antibody subcutaneously to inhibit PCSK9 expression in mice exposed to chronic hypoxia (10%) in combination with SU5416, a VEGF receptor inhibitor. Hypoxia plus SU5416-induced PAH was attenuated in PCSK9 monoclonal antibody-treated mice compared with wild-type mice. PCSK9 inhibited pulmonary vascular remodeling in mice. Moreover, PCSK9 knockdown significantly altered the proliferation and migration of hypoxia-induced PASMCs. We also found that PCSK9 monoclonal antibody inhibited Notch3 expression in vivo and in vitro.

CONCLUSION

Our results suggest that the PCSK9-Notch3 signaling pathway is critical for the proliferation and migration of PASMCs and provides a potential drug target for the treatment of PAH.

Case report: Mild leukoencephalopathy caused by a new mutation of NOTCH3 gene

BACKGROUND

Cerebral autosomal dominant arteriosis with subcortical infarction and leukoencephalopathy (CADASIL) is a single-gene small-vessel disease of the brain characterized by migraine, recurrent ischemic stroke, psychiatric disorders, progressive cognitive decline, and occasional intracerebral hemorrhage.[1]NOTCH3 was identified as a pathogenic gene for CADASIL.[2] The NOTCH3 gene encodes a membrane-bound receptor protein, and to date, several different NOTCH3 gene mutations have been identified.[3] Here, we report a case of CADASIL with a heterozygous mutation c.931T > G (thymine > guanine) on the exon region of the NOTCH3 gene, resulting in an amino acid change p.C311G (cysteine > glycine).

CASE REPORT

We report a case of a female patient with CADASIL whose genetic sequencing revealed a mutation in the NOTCH3 gene. However, this patient did not exhibit any of the typical clinical findings of CADASIL but the patient's cerebral magnetic resonance imaging was consistent with the characteristic findings of CADASIL.

CONCLUSIONS

This case reminds us that mutations caused by different mutation sites present different clinical symptoms.

Sildenafil Improves Pulmonary Vascular Remodeling in a Rat Model of Persistent Pulmonary Hypertension of the Newborn

ABSTRACT

Persistent pulmonary hypertension of the newborn (PPHN) is characterized by pulmonary arterial remodeling mainly because of apoptosis resistance and excessive proliferation of pulmonary artery smooth muscle cells (PASMCs). Sildenafil is a phosphodiesterase-5 inhibitor. Some reports have shown that sildenafil exerts protective effects against PPHN. However, the function of sildenafil in PPHN and the underlying molecular mechanisms is not clear. Here, we revealed that sildenafil effectively suppressed hypoxia-induced PASMC proliferation and apoptosis inhibition ( P < 0.05). Also, sildenafil obviously reduced ventricular hypertrophy, and inhibited pulmonary vascular remodeling in the PPHN model ( P < 0.05). Moreover, sildenafil treatment significantly attenuated the induction of Notch3 and Hes1 induced by hypoxia treatment ( P < 0.05). Furthermore, overexpression of Notch3 abolished the reduction of PASMC proliferation and promotion of PASMC apoptosis induced by sildenafil under hypoxia ( P < 0.05), whereas knockdown of Notch3 had an opposite effect ( P < 0.05). Together, our study demonstrates that sildenafil shows a potential benefit against the development of PPHN by inhibiting Notch3 signaling, providing a strategy for treating PPHN in the future.

PVECs-Derived Exosomal microRNAs Regulate PASMCs via FoxM1 Signaling in IUGR-induced Pulmonary Hypertension

Background Intrauterine growth restriction (IUGR) is closely related to systemic or pulmonary hypertension (PH) in adulthood. Aberrant crosstalk between pulmonary vascular endothelial cells (PVECs) and pulmonary arterial smooth muscle cells (PASMCs) that is mediated by exosomes plays an essential role in the progression of PH. FoxM1 (Forkhead box M1) is a key transcription factor that governs many important biological processes. Methods and Results IUGR-induced PH rat models were established. Transwell plates were used to coculture PVECs and PASMCs. Exosomes were isolated from PVEC-derived medium, and a microRNA (miRNA) screening was proceeded to identify effects of IUGR on small RNAs enclosed within exosomes. Dual-Luciferase assay was performed to validate the predicted binding sites of miRNAs on FoxM1 3' untranslated region. FoxM1 inhibitor thiostrepton was used in IUGR-induced PH rats. In this study, we found that FoxM1 expression was remarkably increased in IUGR-induced PH, and PASMCs were regulated by PVECs through FoxM1 signaling in a non-contact way. An miRNA screening showed that miR-214-3p, miR-326-3p, and miR-125b-2-3p were downregulated in PVEC-derived exosomes of the IUGR group, which were associated with overexpression of FoxM1 and more significant proliferation and migration of PASMCs. Dual-Luciferase assay demonstrated that the 3 miRNAs directly targeted FoxM1 3' untranslated region. FoxM1 inhibition blocked the PVECs-PASMCs crosstalk and reversed the abnormal functions of PASMCs. In vivo, treatment with thiostrepton significantly reduced the severity of PH. Conclusions Transmission of exosomal miRNAs from PVECs regulated the functions of PASMCs via FoxM1 signaling, and FoxM1 may serve as a potential therapeutic target in IUGR-induced PH.

Notch signalling in healthy and diseased vasculature

Notch signalling is an evolutionarily highly conserved signalling mechanism governing differentiation and regulating homeostasis in many tissues. In this review, we discuss recent advances in our understanding of the roles that Notch signalling plays in the vasculature. We describe how Notch signalling regulates different steps during the genesis and remodelling of blood vessels (vasculogenesis and angiogenesis), including critical roles in assigning arterial and venous identities to the emerging blood vessels and regulation of their branching. We then proceed to discuss how experimental perturbation of Notch signalling in the vasculature later in development affects vascular homeostasis. In this review, we also describe how dysregulated Notch signalling, as a consequence of direct mutations of genes in the Notch pathway or aberrant Notch signalling output, contributes to various types of vascular disease, including CADASIL, Snedden syndrome and pulmonary arterial hypertension. Finally, we point out some of the current knowledge gaps and identify remaining challenges in understanding the role of Notch in the vasculature, which need to be addressed to pave the way for Notch-based therapies to cure or ameliorate vascular disease.

Intrauterine growth restriction neonates present with increased angiogenesis through the Notch1 signaling pathway

Intrauterine growth restriction (IUGR) is associated with increased perinatal mortality and morbidity, and plays an important role in the development of adult cardiovascular diseases. This study brings forward a hypothesis that Human umbilical vein endothelial cells (HUVECs) from IUGR newborns present dysfunctions and varying changes of signaling pathways as compared to the Control group. Similar pathways may also be present in pulmonary or systemic vasculatures. HUVECs were derived from newborns. There were three groups according to the different fetal origins: normal newborns (Control), IUGR from poor maternal nutrition (IUGR1), and pregnancy-induced hypertension (IUGR2). We found that IUGR-derived HUVECs showed a proliferative phenotype compared to those from normal subjects. Interestingly, two types IUGR could cause varying degrees of cellular dysfunction. Meanwhile, the Notch1 signaling pathway showed enhanced activation in the two IUGR-induced HUVECs, with subsequent activation of Akt or extracellular signal regulated protein kinases1/2 (ERK1/2). Pharmacological inhibition or gene silencing of Notch1 impeded the proliferative phenotype of IUGR-induced HUVECs and reduced the activation of ERK1/2 and AKT. In summary, elevated Notch1 levels might play a crucial role in IUGR-induced HUVECs disorders through the activation of ERK1/2 and AKT. These pathways could be potential therapeutic targets for prevention of the progression of IUGR associated diseases later in life.

Transgenerational inheritance of promoter methylation changes in extrauterine growth restriction-induced pulmonary arterial pressure disorders

Background

This study aimed to investigate the influence of extrauterine growth restriction (EUGR) on pulmonary arterial pressure (PAP) and the transgenerational inheritance of promoter methylation changes in pulmonary vascular endothelial cells (PVECs) of 2 consecutive generations under EUGR stress.

Methods

After modeling, PAP values of F1 and F2 pups were investigated at 9-week-old. The methyl-DNA immune precipitation chip was used to analyze DNA methylation profiling. Differential enrichment peaks (DEPs) and regions of interest (ROIs) were identified, based on which Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and reactome pathway enrichments were analyzed.

Results

The F1 male rats in the EUGR group had significantly increased PAP levels compared to the control group; however, this increase was not observed in female rats. Interestingly, in F2 female rats, the EUGR group had decreased PAP. In the X chromosome of the F1 males, there were 16 differential ROI genes in the F1 generation, while in F2 females, there were 86 differential ROI genes. Similarly, there were 105 DEPs in the F1 generation and 38 DEPs in the F2 generation. In combination with the 5 common ROIs and 14 common DEPs, 18 genes were regarded as the key candidate genes associated with hereditable PAP variation in the EUGR model. Enrichment analysis showed that synaptic and neurotransmitter relative pathways might be involved in the process of EUGR-induced PAH development. Among common DEPs, Smad1 and Serpine1 were also found in 102 PAH-associated genes in the MalaCards database.

Conclusions

Together, there is a transgenerational inheritance of promoter methylation changes in the X chromosome in EUGR-induced PAP disorders, which involves the participation of synaptic and neurotransmitter relative pathways. Also, attenuated methylation of Smad1 and Serpine1 in the promoter region may be a partial driver of PAH in later life.

Cellular mechanosignaling in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a vasculopathy characterized by sustained elevated pulmonary arterial pressures in which the pulmonary vasculature undergoes significant structural and functional remodeling. To better understand disease mechanisms, in this review article we highlight recent insights into the regulation of pulmonary arterial cells by mechanical cues associated with PAH. Specifically, the mechanobiology of pulmonary arterial endothelial cells (PAECs), smooth muscle cells (PASMCs) and adventitial fibroblasts (PAAFs) has been investigated in vivo, in vitro, and in silico. Increased pulmonary arterial pressure increases vessel wall stress and strain and endothelial fluid shear stress. These mechanical cues promote vasoconstriction and fibrosis that contribute further to hypertension and alter the mechanical milieu and regulation of pulmonary arterial cells.

Comparative Transcriptional Analysis of Pulmonary Arterial Hypertension Associated With Three Different Diseases

Pulmonary arterial hypertension (PAH) is a severe cardiovascular disorder with high mortality. Multiple clinical diseases can induce PAH, but the underlying molecular mechanisms shared in PAHs associated with different diseases remain unclear. The aim of this study is to explore the key candidate genes and pathways in PAH associated with congenital heart disease (CHD-PAH), PAH associated with connective tissue disease (CTD-PAH), and idiopathic PAH (IPAH). We performed differential expression analysis based on a public microarray dataset GSE113439 and identified 1,442 differentially expressed genes, of which 80.3% were upregulated. Subsequently, both pathway enrichment analysis and protein–protein interaction network analysis revealed that the “Cell cycle” and “DNA damage” processes were significantly enriched in PAH. The expression of seven upregulated candidate genes (EIF2AK2, TOPBP1, CDC5L, DHX15, and CUL1–3) and three downregulated candidate genes (DLL4, EGFL7, and ACE) were validated by qRT-PCR. Furthermore, cell cycle-related genes Cul1 and Cul2 were identified in pulmonary arterial endothelial cells (PAECs) in vitro. The result revealed an increased expression of Cul2 in PAECs after hypoxic treatment. Silencing Cul2 could inhibit overproliferation and migration of PAECs in hypoxia. Taken together, according to bioinformatic analyses, our work revealed that “Cell cycle” and “DNA damage” process-related genes and pathways were significantly dysregulated expressed in PAHs associated with three different diseases. This commonality in molecular discovery might broaden the genetic perspective and understanding of PAH. Besides, silencing Cul2 showed a protective effect in PAECs in hypoxia. The results may provide new treatment targets in multiple diseases induced by PAH.

Astragaloside IV attenuates hypoxia‑induced pulmonary vascular remodeling via the Notch signaling pathway

The Notch signaling pathway participates in pulmonary artery smooth muscle cell (PASMC) proliferation and apoptosis. Astragaloside IV (AS-IV) is an effective antiproliferative treatment for vascular diseases. The present study aimed to investigate the protective effects and mechanisms underlying AS-IV on hypoxia-induced PASMC proliferation and pulmonary vascular remodeling in pulmonary arterial hypertension (PAH) model rats. Rats were divided into the following four groups: i) normoxia; ii) hypoxia (10% O₂); iii) treatment, hypoxia + intragastrical administration of AS-IV (2 mg/kg) daily for 28 days; and iv) DAPT, hypoxia + AS-IV treatment + subcutaneous administration of DAPT (10 mg/kg) three times daily. The effects of AS-IV treatment on the development of hypoxia-induced PAH, right ventricle (RV) hypertrophy and pulmonary vascular remodeling were examined. Furthermore, PASMCs were treated with 20 µmol/l AS-IV under hypoxic conditions for 48 h. To determine the effect of Notch signaling in vascular remodeling and the potential mechanisms underlying AS-IV treatment, 5 mmol/l γ-secretase inhibitor [N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT)] was used. Cell viability and apoptosis were determined by performing the MTT assay and flow cytometry, respectively. Immunohistochemistry was conducted to detect the expression of proliferating cell nuclear antigen (PCNA). Moreover, the mRNA and protein expression levels of Notch-3, Jagged-1, hes family bHLH transcription factor 5 (Hes-5) and PCNA were measured via reverse transcription-quantitative PCR and western blotting, respectively. Compared with the normoxic group, hypoxia-induced PAH model rats displayed characteristics of PAH and RV hypertrophy, whereas AS-IV treatment alleviated PAH and prevented RV hypertrophy. AS-IV also inhibited hypoxia-induced pulmonary vascular remodeling, as indicated by reduced wall thickness and increased lumen diameter of pulmonary arterioles, and decreased muscularization of distal pulmonary vasculature in hypoxia-induced PAH model rats. Compared with normoxia, hypoxia promoted PASMC proliferation in vitro, whereas AS-IV treatment inhibited hypoxia-induced PASMC proliferation by downregulating PCNA expression in vitro and in vivo. In hypoxia-treated PAH model rats and cultured PASMCs, AS-IV treatment reduced the expression levels of Jagged-1, Notch-3 and Hes-5. Furthermore, Notch signaling inhibition via DAPT significantly inhibited the pulmonary vascular remodeling effect of AS-IV in vitro and in vivo. Collectively, the results indicated that AS-IV effectively reversed hypoxia-induced pulmonary vascular remodeling and PASMC proliferation via the Notch signaling pathway. Therefore, the present study provided novel insights into the mechanism underlying the use of AS-IV for treatment of vascular diseases, such as PAH.

Pulmonary chronic thromboembolic disease

Persistent thrombotic lesions are common in patients with pulmonary embolism. These lesions occur on a clinical spectrum, ranging from an asymptomatic course with complete functional recovery to chronic thromboembolic pulmonary hypertension. The concept of chronic thromboembolic disease has emerged in recent years to describe a subgroup of patients with persistent thrombotic lesions who have symptoms on exertion and pulmonary vascular dysfunction, but no pulmonary hypertension at rest. The prevalence of this entity is unknown and the criteria for diagnosing it are not defined. The aim of this article is to analyze post-pulmonary embolism sequelae and review existing evidence on chronic thromboembolic disease, with special emphasis on its diagnosis and therapeutic approach.

Notch3 in Development, Health and Disease

Notch3 is one of four mammalian Notch proteins, which act as signalling receptors to control cell fate in many developmental and adult tissue contexts. Notch signalling continues to be important in the adult organism for tissue maintenance and renewal and mis-regulation of Notch is involved in many diseases. Genetic studies have shown that Notch3 gene knockouts are viable and have limited developmental defects, focussed mostly on defects in the arterial smooth muscle cell lineage. Additional studies have revealed overlapping roles for Notch3 with other Notch proteins, which widen the range of developmental functions. In the adult, Notch3, in collaboration with other Notch proteins, is involved in stem cell regulation in different tissues in stem cell regulation in different tissues, and it also controls the plasticity of the vascular smooth muscle phenotype involved in arterial vessel remodelling. Overexpression, gene amplification and mis-activation of Notch3 are associated with different cancers, in particular triple negative breast cancer and ovarian cancer. Mutations of Notch3 are associated with a dominantly inherited disease CADASIL (cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy), and there is further evidence linking Notch3 misregulation to hypertensive disease. Here we discuss the distinctive roles of Notch3 in development, health and disease, different views as to the underlying mechanisms of its activation and misregulation in different contexts and potential for therapeutic intervention.

Linking lncRNAs to regulation, pathogenesis, and diagnosis of pulmonary hypertension

Pulmonary hypertension (PH) is a syndrome characterized by a persistent increase in pulmonary vascular resistance. Due to the lack of specificity in clinical manifestations, patients are usually diagnosed at the late stage of PH, which is hard to treat and often causes right heart failure and death. Furthermore, the regulation and pathogenesis of PH remain obscure. Recently, long noncoding RNAs (lncRNAs), a type of transcript longer than 200 nt that lacks protein-coding ability, have been found to substantially influence the incidence and progression of various diseases through regulating gene expression at the chromatin, transcriptional, post-transcriptional, translational, and even post-translational levels. The crucial roles of lncRNAs in PH have started to draw widespread attention. This review summarizes the regulatory, pathogenic, and diagnostic roles of lncRNAs in PH, in the hope to facilitate the search for early diagnostic markers of and effective therapeutic targets for this devastating disease.

Intrauterine Growth Restriction Programs Intergenerational Transmission of Pulmonary Arterial Hypertension and Endothelial Dysfunction via Sperm Epigenetic Modifications

Intrauterine life represents a window of phenotypic plasticity which carries consequences for later health in adulthood as well as health of subsequent generations. Intrauterine growth-restricted fetuses (intrauterine growth restriction [IUGR]) have a higher risk of pulmonary arterial hypertension in adulthood. Endothelial dysfunction, characterized by hyperproliferation, invasive migration, and disordered angiogenesis, is a hallmark of pulmonary arterial hypertension pathogenesis. Growing evidence suggests that intergenerational transmission of disease, including metabolic syndrome, can be induced by IUGR. Epigenetic modification of the paternal germline is implicated in this transmission. However, it is unclear whether offspring of individuals born with IUGR are also at risk of developing pulmonary arterial hypertension and endothelial dysfunction. Using a model of maternal caloric restriction to induce IUGR, we found that first and second generations of IUGR exhibited elevated pulmonary arterial pressure, myocardial, and vascular remodeling after prolonged exposure to hypoxia. Primary pulmonary vascular endothelial cells (PVECs) from both first and second generations of IUGR exhibited greater proliferation, migration, and angiogenesis. Moreover, in 2 generations, PVECs-derived ET-1 (endothelin-1) was activated by IUGR and hypoxia, and its knockdown mitigated PVECs dysregulation. Most interestingly, within ET-1 first intron, reduced DNA methylation and enhanced tri-methylation of lysine 4 on histone H3 were observed in PVECs and sperm of first generation of IUGR, with DNA demethylation in PVECs of second generation of IUGR. These results suggest that IUGR permanently altered epigenetic signatures of ET-1 from the sperm and PVECs in the first generation, which was subsequently transferred to PVECs of offspring. This mechanism would yield 2 generations with endothelial dysfunction and pulmonary arterial hypertension-like pathophysiological features in adulthood.

Epigenetic Modulation in the Initiation and Progression of Pulmonary Hypertension

Pulmonary hypertension (PH) is a severe disease with multiple etiologies. In addition to genetics, recent studies have revealed the epigenetic modulation in the initiation and progression of PH. In this review, we summarize the epigenetic mechanisms in the pathogenesis of PH, specifically, DNA methylation, histone modifications, and microRNAs. We further emphasize the diagnostic and therapeutic potential of these epigenetic hallmarks in PH. Finally, we highlight the developmental reprogramming in adult-onset PH because of adverse perinatal exposures such as intrauterine growth restriction and extrauterine growth restriction. Therefore, epigenetic modifications provide promise for the therapy and prevention of PH.