Exosomes derived from endothelial cells and Schwann cells have been employed as novel treatments of neurological diseases, including peripheral neuropathy. Exosomal cargo plays a critical role in mediating recipient cell function. In this study, we thus performed a comprehensive proteomic analysis of exosomes derived from healthy mouse dermal microvascular endothelial cells (EC-Exo) and healthy mouse Schwann cells (SC-Exo). We detected 1,817and 1,579 proteins in EC-Exo and SC-Exo, respectively. Among them, 1506 proteins were present in both EC-Exo and SC-Exo, while 311 and 73 proteins were detected only in EC-Exo and SC-Exo, respectively. Bioinformatic analysis revealed that EC-Exo enriched proteins were involved in neurovascular function, while SC-Exo enriched proteins were related to lipid metabolism. Western blot analysis of 14 enriched proteins revealed that EC-Exo contained proteins involved in mediating endothelial function such as delta-like 4 (DLL4) and endothelial NOS (NOS3), whereas SC-Exo had proteins involved in mediating glial function such as apolipoprotein A-I (APOA1) and phospholipid transfer protein (PLTP). Collectively, the present study identifies differences in the cargo protein profiles of EC-Exo and SC-Exo, thus providing new molecular insights into their biological functions for the treatment of peripheral neuropathy.

Arsenic exposure is associated with lung cancer. Angiogenesis is essential for tumor development. However, the role and mechanism of human vascular endothelial cells in tumor growth and angiogenesis induced by arsenic-transformed bronchial epithelial (As-T) cells remain to be elucidated. In this study, we found that endothelial cells significantly increased As-T cell-induced tumor growth compared to those induced by As-T cells alone. To understand the molecular mechanism, we found that endothelial cells co-cultured with As-T cells or cultured in conditioned medium (CM) prepared from As-T cells showed much higher cell migration, proliferation, and tube formation compared to those co-cultured with BEAS-2B (B2B) cells or cultured in CM from B2B. We identified that higher levels of intracellular interleukin 8 (IL-8) were secreted by As-T cells, which activated IL-8/IL-8R signaling to promote endothelial cells migration and tube formation. IL-8 silencing and knockout (KO) in As-T cells, or IL-8 neutralizing antibody dramatically suppressed endothelial cell proliferation, migration, tube formation in vitro, and tumor growth and angiogenesis in vivo, suggesting a key role of IL-8 in As-T cells to induce angiogenesis via a paracrine effect. Finally, blocking of IL-8 receptors C-X-C chemokine receptor type 1 (CXCR1) and CXCR2 with neutralizing antibodies and chemical inhibitors inhibited tube formation, indicating that IL-8Rs on endothelial cells are necessary for As-T cell-induced angiogenesis. Overall, this study reveals an important molecular mechanism of arsenic-induced carcinogenesis, and suggests a new option to prevent and treat arsenic-induced angiogenesis.

Chimeric antigen receptor (CAR) T cells hold promise for the treatment of acute myeloid leukemia (AML), but optimal targets remain to be defined. We demonstrate that CD93 CAR T cells engineered from a novel humanized CD93-specific binder potently kill AML in vitro and in vivo but spare hematopoietic stem and progenitor cells (HSPC). No toxicity is seen in murine models, but CD93 is expressed on human endothelial cells, and CD93 CAR T cells recognize and kill endothelial cell lines. We identify other AML CAR T-cell targets with overlapping expression on endothelial cells, especially in the context of proinflammatory cytokines. To address the challenge of endothelial-specific cross-reactivity, we provide proof of concept for NOT-gated CD93 CAR T cells that circumvent endothelial cell toxicity in a relevant model system. We also identify candidates for combinatorial targeting by profiling the transcriptome of AML and endothelial cells at baseline and after exposure to proinflammatory cytokines.

Normal liver sinusoidal endothelial cells (LSECs) promote quiescence of hepatic stellate cells (HSCs). Prior to fibrosis, LSECs undergo capillarization, which is permissive for HSC activation, the proximate event in hepatic fibrosis. The aims of this study were to elucidate the nature of and mechanisms leading to capillarization and to determine how LSECs promote HSC quiescence and why "capillarized LSECs" lose control of HSC activation. The contribution of bone marrow (BM) endothelial progenitor cells to capillarization was identified using rats transplanted with transgenic enhanced green fluorescent protein-positive BM. Shotgun proteomics and informatics were used to identify the LSEC mediator that maintains HSC quiescence. The study shows that capillarization is due to repair of injured LSECs by BM endothelial progenitors that engraft but fail to fully mature. Lack of maturation of BM-derived LSECs is due to cell autonomous pathways that inhibit the nitric oxide pathway. We identify heparin binding epidermal growth factor-like growth factor (HB-EGF) as the signal that maintains HSC quiescence and show that immature LSECs are unable to shed HB-EGF from the cytosolic membrane. Conclusion: Chronic liver injury can recruit BM progenitors of LSECs that engraft and fail to fully differentiate, which creates an environment that is permissive for hepatic fibrosis; elucidation of these early events in the fibrotic process will provide targets for treatment of hepatic fibrosis.

To investigate the regulation of endothelial cell (EC) microRNAs (miRNAs) altered by heat stress, miRNA microarrays and bioinformatics methods were used to determine changes in miRNA profiles and the pathophysiological characteristics of differentially expressed miRNAs. A total of 31 differentially expressed miRNAs were identified, including 20 downregulated and 11 upregulated miRNAs. Gene Ontology (GO) enrichment analysis revealed that the validated targets of the differentially expressed miRNAs were significantly enriched in gene transcription regulation. The pathways were also significantly enriched in the Kyoto Encyclopedia of Genes and Genomes analysis, and most were cancer-related, including the mitogen-activated protein kinase signaling pathway, pathways involved in cancer, the Wnt signaling pathway, the Hippo signaling pathway, proteoglycans involved in cancer and axon guidance. The miRNA-gene and miRNA‑GO network analyses revealed several hub miRNAs, genes and functions. Notably, miR‑3613-3p played a dominant role in both networks. MAP3K2, MGAT4A, TGFBR1, UBE2R2 and SMAD4 were most likely to be controlled by the altered miRNAs in the miRNA-gene network. The miRNA‑GO network analysis revealed significantly complicated associations between miRNAs and different functions, and that the significantly enriched functions targeted by the differentially expressed miRNAs were mostly involved in regulating gene transcription. The present study demonstrated that miRNAs are involved in the pathophysiology of heat-treated ECs. Understanding the functions of miRNAs may provide novel insights into the molecular mechanisms underlying the heat‑induced pathophysiology of ECs.

Background Endothelial NO synthase plays a central role in regulating vasodilation and blood pressure. Intracellular Ca2+ mobilization is a critical modulator of endothelial NO synthase function, and increased cytosolic Ca2+ concentration in endothelial cells is able to induce endothelial NO synthase phosphorylation. Ca2+ release mediated by 3 subtypes of inositol 1,4,5-trisphosphate receptors ( IP 3Rs) from the endoplasmic reticulum and subsequent Ca2+ entry after endoplasmic reticulum Ca2+ store depletion has been proposed to be the major pathway to mobilize Ca2+ in endothelial cells. However, the physiological role of IP 3Rs in regulating blood pressure remains largely unclear. Methods and Results To investigate the role of endothelial IP 3Rs in blood pressure regulation, we first generated an inducible endothelial cell-specific IP 3R1 knockout mouse model and found that deletion of IP 3R1 in adult endothelial cells did not affect vasodilation and blood pressure. Considering all 3 subtypes of IP 3Rs are expressed in mouse endothelial cells, we further generated inducible endothelial cell-specific IP 3R triple knockout mice and found that deletion of all 3 IP 3R subtypes decreased plasma NO concentration and increased basal blood pressure. Furthermore, IP 3R deficiency reduced acetylcholine-induced vasodilation and endothelial NO synthase phosphorylation at Ser1177. Conclusions Our results reveal that IP 3R-mediated Ca2+ release in vascular endothelial cells plays an important role in regulating vasodilation and physiological blood pressure.

Previous studies have identified microRNA (miRNA/miR)‑3613‑3p as a heat stress (HS)‑related miRNA in endothelial cells that can lead to apoptosis. However, the mechanism underlying the miR‑3613‑3p‑mediated apoptosis of HS‑exposed endothelial cells remains unclear. In the present study, western blot analysis and reverse transcription‑quantitative PCR were used to determine protein and miRNA expression levels, respectively. Annexin V‑fluorescein isothiocyanate/propidium iodide staining, caspase‑3 activity measurements and DNA fragmentation assays were performed to detect apoptosis. To evaluate whether mitogen‑activated protein kinase kinase kinase 2 (MAP3K2) was a direct target of miR‑3613‑3p, a luciferase reporter assay was performed. In addition, transient transfection was used to carry out loss‑ and gain‑of‑function experiments. The results revealed that miR‑3613‑3p expression was reduced in human umbilical vein endothelial cells (HUVECs) following HS, which led to apoptosis. Mechanistically, following HS, a decrease in miR‑3613‑3p binding to the 3'‑untranslated region of MAP3K2 directly upregulated its expression, and the downstream p38 and caspase‑3 pathways, thereby leading to apoptosis. Taken together, the results of the present study demonstrated that HS suppressed miR‑3613‑3p expression, which activated the MAP3K2/p38/caspase‑3 pathway, leading to the apoptosis of HUVECs. In conclusion, the miR‑3613‑3p/MAP3K2/p38/caspase‑3 pathway may serve an indispensable role in regulating the progression of apoptosis, indicating a regulatory role of miR‑3613‑3p in the pathophysiology of HS‑exposed endothelial cells.

Effects of shear stress on endotheliaxl differentiation of stem cells from human exfoliated deciduous teeth (SHEDs) were investigated. SHEDs were treated with shear stress, then reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to analyse the mRNA expression of arterial markers and western blot analysis was performed to analyse protein expression of angiogenic markers. Additionally, in vitro matrigel angiogenesis assay was performed to evaluate vascular-like structure formation. The secreted protein expression levels of the vascular endothelial growth factor (VEGF) of SHEDs after shear stress was also quantified using corresponding ELISA kits. Untreated SHEDs seeded on Matrigel cannot form vessel-like structures at any time points, whereas groups treated with shear stress formed a few vessel-like structures at 4, 8 and 12 h. When SHEDs were treated with EphrinB2-siRNA for 24, the capability of vessel-like structure formation was suppressed. After being treated with shear stress, the expression of VEGF, VEGFR2, DLL4, Notch1, EphrinB2, Hey1 and Hey2 (arterial markers) gene expression was significantly upregulated, moreover, the protein levels of VEGFR2, EphrinB2, CD31, Notch1, DLL4, Hey1, and Hey2 were also significantly up-regulated. Both the mRNA and protein expression levels of EphB4 (venous marker) were downregulated. The average VEGF protein concentration in supernatants secreted by shear stress treated SHEDs groups increased significantly. In conclusion, shear stress was able to induce arterial endothelial differentiation of stem cells from human exfoliated deciduous teeth, and VEGF-DLL4/Notch‑EphrinB2 signaling was involved in this process.

The limited efficacy of the current antitumor microenvironment strategies is due in part to the poor understanding of the roles and relative contributions of the various tumor stromal cells to tumor development. Here, we describe a versatile in vivo anthrax toxin protein delivery system allowing for the unambiguous genetic evaluation of individual tumor stromal elements in cancer. Our reengineered tumor-selective anthrax toxin exhibits potent antiproliferative activity by disrupting ERK signaling in sensitive cells. Since this activity requires the surface expression of the capillary morphogenesis protein-2 (CMG2) toxin receptor, genetic manipulation of CMG2 expression using our cell-type-specific CMG2 transgenic mice allows us to specifically define the role of individual tumor stromal cell types in tumor development. Here, we established mice with CMG2 only expressed in tumor endothelial cells (ECs) and determined the specific contribution of tumor stromal ECs to the toxin's antitumor activity. Our results demonstrate that disruption of ERK signaling only within tumor ECs is sufficient to halt tumor growth. We discovered that c-Myc is a downstream effector of ERK signaling and that the MEK-ERK-c-Myc central metabolic axis in tumor ECs is essential for tumor progression. As such, disruption of ERK-c-Myc signaling in host-derived tumor ECs by our tumor-selective anthrax toxins explains their high efficacy in solid tumor therapy.

We previously reported that a novel marine compound, xyloketal B, has strong antioxidative actions in different models of cardiovascular diseases. Induction of heme oxygenase-1 (HO-1), an important endogenous antioxidant enzyme, has been considered as a potential therapeutic strategy for cardiovascular diseases. We here investigated whether xyloketal B exhibits its antioxidant activity through induction of HO-1. In human umbilical vein endothelial cells (HUVECs), xyloketal B significantly induced HO-1 gene expression and translocation of the nuclear factor-erythroid 2-related factor 2 (Nrf-2) in a concentration- and time-dependent manner. The protection of xyloketal B against angiotensin II-induced apoptosis and reactive oxygen species (ROS) production could be abrogated by the HO-1 specific inhibitor, tin protoporphyrin-IX (SnPP). Consistently, the suppressive effects of xyloketal B on NADPH oxidase activity could be reversed by SnPP in zebrafish embryos. In addition, xyloketal B induced Akt and Erk1/2 phosphorylation in a concentration- and time-dependent manner. Furthermore, PI3K inhibitor LY294002 and Erk1/2 inhibitor U0126 suppressed the induction of HO-1 and translocation of Nrf-2 by xyloketal B, whereas P38 inhibitor SB203580 did not. In conclusion, xyloketal B can induce HO-1 expression via PI3K/Akt/Nrf-2 pathways, and the induction of HO-1 is mainly responsible for the antioxidant and antiapoptotic actions of xyloketal B.

Atherosclerosis is a complex pathological process involving macrophages, endothelial cells and vascular smooth muscle cells that can lead to ischemic heart disease; however, the mechanisms underlying cell-to-cell communication in atherosclerosis are poorly understood. In this study, we focused on the role of exosomal miRNAs in crosstalk between macrophages and endothelial cells and explored the rarely studied molecular mechanisms involved. Our in vitro result showed that macrophage-derived exosomal miR-4532 significantly disrupted human umbilical vein endothelial cells (HUVECs) function by targeting SP1 and downstream NF-κB P65 activation. In turn, increased endothelin-1 (ET-1), intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and decreased endothelial nitric oxide synthase (eNOS) expression in HUVECs increased attraction of macrophages, exacerbating foam cell formation and transfer of exosomal miR-4532 to HUVECs. MiR-4532 overexpression significantly promoted endothelial injury and pretreatment with an inhibitor of miR-4532 or GW4869 (exosome inhibitor) could reverse this injury. In conclusion, our data reveal that exosomes have a critical role in crosstalk between HUVECs and macrophages. Further, exosomal miR-4532 transferred from macrophages to HUVECs and targeting specificity protein 1 (SP1) may be a novel therapeutic target in patients with atherosclerosis.

Gene therapy is an emerging therapeutic strategy used in clinics. Ultrasound-mediated gene transfection possesses great potential as a secure and available approach for gene delivery. However, transfection efficiency and targeting ability remain challenging. In this study, we developed a kind of ultrasound-aided and targeting nanoparticles for microRNA delivery. These nanoparticles carrying nucleic acids were prepared with cationic poly-(amino acid) encapsulated with perfluoropentane. The formulated nanoparticles were stabilized with negatively charged PGA-PEG-RGD peptide coating. Ultrasound imaging and specific gene transfection using this nanocarrier could be implemented simultaneously. Upon treatment with ultrasound irradiation, phase transition was induced in the nanoparticles and they generated acoustic cavitation, resulting in enhanced gene transfection against the endothelial cells. With the overexpression of miR-181b loaded by the nanoparticles, the TNF-α-stimulated endothelial cells were effectively rescued from the inflammatory state through the protection of cell viability and suppression of cell adhesion.

Studies have reported that scorpion toxins have excellent anti-cancer effects; however, the anti-inflammatory activity of scorpion peptides has rarely been studied. Here, a series of Mesobuthus martensii Karsch peptides (MMKPs) were isolated and the amino acid sequence was identified. The MMKPs mitigated TNF-α-mediated inflammation in human umbilical vein endothelial cells (HUVECs). The results showed that MMKP-1 (His-Glu-Gly-His) treatment (43.0 μM) significantly attenuated the reactive oxygen species (ROS) generation and mitochondrial membrane potential collapse in HUVECs. Moreover, MMKP-1 down-regulated the intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expressions and blocked the NF-κB pathway to alleviate the damage caused by TNF-α. Of note, our study provides a good reference for the anti-inflammation research on scorpion oligopeptides.

Dysregulation of microRNA‑3613‑3p (miR‑3613‑3p) was previously reported in endothelial cells (ECs) during heat stress. The aim of the present study was to investigate the precise role of miR‑3613‑3p in heat stress. In the present study, potential gene targets of miR‑3613‑3p in heat‑treated ECs were assessed, and the potential effects of miR‑3613‑3p were determined using Gene Ontology enrichment analysis. Kyoto Encyclopedia of Genes and Genomes pathway analysis was used to identify signaling pathways that may be affected by miR‑3613‑3p in heat‑treated cells. Reverse transcription‑quantitative PCR, western blotting and annexin V‑FITC/propidium iodide staining were performed to detect miRNA expression, protein expression and apoptosis, respectively. Luciferase gene reporter assay was performed to evaluate the association between miR‑3613‑3p and mitogen‑activated protein kinase kinase kinase 2 (MAP3K2). Bioinformatics analysis revealed 865 potential gene targets for miR‑3613‑3p and a series of functions and pathways in heat‑treated ECs. 'Negative regulation of apoptotic process' was identified as a potential function of miR‑3613‑3p. In addition, functional analysis confirmed the downregulated expression levels of miR‑3613‑3p in ECs during heat stress, which was accompanied by an increase in apoptosis; restoration of miR‑3613‑3p expression inhibited apoptosis. MAP3K2 protein was demonstrated to be upregulated in heat‑treated ECs, and overexpression of miR‑3613‑3p reduced MAP3K2 expression levels. Additionally, MAP3K2 was targeted by miR‑3613‑3p. These results indicated that miR‑3613‑3p may have complicated roles in ECs under heat stress. miR‑3613‑3p may serve an important role in the apoptosis of heat‑treated ECs, and this effect may be partly achieved by targeting MAP3K2.

Recent studies have indicated that the inflammasome plays a critical role in the pathogenesis of vascular diseases. However, the pathological relevance of this inflammasome activation, particularly in vascular cells, remains largely unknown. Here, we investigated the role of endothelial (Nucleotide-binding Oligomerization Domain) NOD-like receptor family pyrin domain containing three (Nlrp3) inflammasomes in modulating inter-endothelial junction proteins, which are associated with endothelial barrier dysfunction, an early onset of obesity-associated endothelial injury. Our findings demonstrate that the activation of Nlrp3 inflammasome by visfatin markedly decreased the expression of inter-endothelial junction proteins including tight junction proteins ZO-1, ZO-2 and occludin, and adherens junction protein VE-cadherin in cultured mouse vascular endothelial (VE) cell monolayers. Such visfatin-induced down-regulation of junction proteins in endothelial cells was attributed to high mobility group box protein 1 (HMGB1) release derived from endothelial inflammasome-dependent caspase-1 activity. Similarly, in the coronary arteries of wild-type mice, high-fat diet (HFD) treatment caused a down-regulation of inter-endothelial junction proteins ZO-1, ZO-2, occludin and VE-cadherin, which was accompanied with enhanced inflammasome activation and HMGB1 expression in the endothelium as well as transmigration of CD43(+) T cells into the coronary arterial wall. In contrast, all these HFD-induced alterations in coronary arteries were prevented in mice with Nlrp3 gene deletion. Taken together, these data strongly suggest that the activation of endothelial Nlrp3 inflammasomes as a result of the increased actions of injurious adipokines such as visfatin produces HMGB1, which act in paracrine or autocrine fashion to disrupt inter-endothelial junctions and increase paracellular permeability of the endothelium contributing to the early onset of endothelial injury during metabolic disorders such as obesity or high-fat/cholesterol diet.

This study aims to explore the role of hyperlipidemia in the mobilization of bone marrow (BM) endothelial progenitor cells (EPCs) induced by acute myocardial ischemia (AMI). To establish the hyperlipidemia complicated with AMI (HL-AMI) model, SD rats were intragastrically administered the high-fat emulsion for 4 weeks. Then their left anterior descending arteries were ligated. Rats in each group were randomly subdivided into seven subgroups. During 1st ~ 7th day following AMI modeling, rats in 1st ~ 7th subgroups were selected to be phlebotomized from their celiac artery after being anesthetized by pentobarbitone in turn. The quantity of circulating EPCs (CEPCs) was detected by flow cytometry, the expression of VEGF, eNOS, NO, MMP-9 in myocardial tissue was analyzed by western blot, and their plasma level was assayed by ELISA. Dynamic curves were plotted using these data. Within 7 days following AMI, compared with the AMI rats, in the HL-AMI rats, the myocardial infarct size, the plasma activity of CK, CK-MB, and the collagen deposition all remained at the higher levels; meanwhile, these rats showed more significant decreases in the count of CEPCs, the plasma level of VEGF etc., and their expression in myocardial tissue (P < 0.05 or P < 0.01). Our study showed that hyperlipidemia may attenuate the mobilization of BM EPCs induced by AMI via VEGF/eNOS/NO/MMP-9 signal pathway, which might partly account for hyperlipidemia hampering the repairs of AMI-induced cardiac injury.

IL-33 may play a role in the vascular remodelling of hypoxic pulmonary hypertension (PH) but the precise mechanisms are still unclear. We hypothesized that hypoxia promotes expression of IL-33 and its receptor ST2 on vascular endothelial cells, which in turn leads to dysfunction of vascular endothelial cells and smooth muscle cells contributing to PH. Immunohistochemistry showed that immunoreactivity for IL-33 and ST2 was significantly increased in lung tissue of murine model of hypoxia-induced PH (HPH) and of subjects with bronchiectasis-PH. trans-Thoracic echocardiography showed that haemodynamic changes and right ventricular hypertrophy associated with HPH were significantly abrogated in St2-/- compared with WT mice. Administration of IL-33 further exacerbated these changes in the hypoxia-exposed WT mice. In vitro, hypoxia significantly increased IL-33/ST2 expression by human pulmonary arterial endothelial cells (HPAECs), while exogenous IL-33 enhanced proliferation, adhesiveness and spontaneous angiogenesis of HPAECs. Knockdown of endogenous Il33 or St2 using siRNA transfection significantly suppressed these effects in both normoxic and hypoxic culture-conditions. Deletion of the St2 gene attenuated hypoxia-induced, elevated lung expression of HIF-1α/VEGFA/VEGFR-2/ICAM-1, while administration of exogenous VEGFA partially reversed the attenuation of the haemodynamic indices of PH. Correspondingly, knockdown of the St2 or Hif1α genes almost completely abrogated IL-33-induced expression of HIF-1α/VEGFA/VEGFR-2 by HPAECs in vitro. Further, IL-33-induced angiogenesis by HPAECs was extensively abrogated by knockdown of the Hif1α/Vegfa or Vegfr2 genes. These data suggest that hypoxia induces elevated expression of IL-33/ST2 by HPAECs which, at least partly by increasing downstream expression of HIF-1α and VEGF initiates vascular remodelling resulting in HPH.

The probable nanotoxicity to human health and the environment is a significant challenge for the sustainable application of nanomaterials in medicine. The cytototoxical effect of succimer (meso-2,3-dimercaptosuccinic acid-DMSA) coated titanium dioxide (DMSA-TiO2) with cultured human aortic endothelial cells (HAoECs) was assessed in this investigation. Our findings have shown that DMSA-TiO2 can be accumulated in HAoECs and dispersed in a cytoplasm on the culture medium. DMSA-cytotoxicity TiO2 effects were dose-responsive, and the concentrations were of little toxicity, and MTT stain testing showed that they had only 0.02 mg ml-1. Meanwhile, the lactate dehydrogenase biomarker was not considerably more remarkable than the biomarker from untreated (control) cells (free DMSA-TiO2). Though, also without any apparent signs of cell damage, the endocrine functions for prostacyclin I-2 and endothelin-1 and the urea transporter functions were modified. In addition, in vitro endothelial tube development has been shown that HAoECs could induce angiogenesis even with small amounts of DMSA-TiO2 (0.01 and 0.02 mg ml-1). Further, we have examined the in vivo toxicity and biochemical parameter by animal model. Furthermore, in vivo assessments designated that the resulting DMSA-TiO2 presented synergistic activities of angiogenesis activity. Overall, these findings show the cytotoxicity of DMSA-TiO2 and could induce adverse effects on normal endothelial cells.

The specific pathogenesis of steroid-induced osteonecrosis of the femoral head (SONFH) is still not fully understood, and there is currently no effective early cure. Understanding the role and mechanism of long noncoding RNAs (lncRNAs) in the pathogenesis of SONFH will help reveal the pathogenesis of SONFH and provide new targets for its early prevention and treatment. In this study, we first confirmed that glucocorticoid (GC)-induced apoptosis of bone microvascular endothelial cells (BMECs) is a pre-event in the pathogenesis and progression of SONFH. Then, we identified a new lncRNA in BMECs via lncRNA/mRNA microarray, termed Fos-associated lincRNA ENSRNOT00000088059.1 (FAR591). FAR591 is highly expressed during GC-induced BMEC apoptosis and femoral head necrosis. Knockout of FAR591 effectively blocked the GC-induced apoptosis of BMECs, which then alleviated the damage of GCs to the femoral head microcirculation and inhibited the pathogenesis and progression of SONFH. In contrast, overexpression of FAR591 significantly promoted the GC-induced apoptosis of BMECs, which then aggravated the damage of GCs to the femoral head microcirculation and promoted the pathogenesis and progression of SONFH. Mechanistically, GCs activate the glucocorticoid receptor, which translocates to the nucleus and directly acts on the FAR591 gene promoter to induce FAR591 gene overexpression. Subsequently, FAR591 binds to the Fos gene promoter (-245∼-51) to form a stable RNA:DNA triplet structure and then recruits TATA-box binding protein associated factor 15 and RNA polymerase II to promote Fos expression through transcriptional activation. Fos activates the mitochondrial apoptotic pathway by regulating the expression of Bcl-2 interacting mediator of cell death (Bim) and P53 upregulated modulator of apoptosis (Puma) to mediate GC-induced apoptosis of BMECs, which leads to femoral head microcirculation dysfunction and femoral head necrosis. In conclusion, these results confirm the mechanistic link between lncRNAs and the pathogenesis of SONFH, which helps reveal the pathogenesis of SONFH and provides a new target for the early prevention and treatment of SONFH.

This study aimed to explore whether bone marrow- (BM-) derived endothelial progenitor cells (EPCs) contributing to monocrotaline- (MCT-) induced pulmonary arterial hypertension (PAH) in rats via modulating store-operated Ca2+ channels (SOC).