A correlated light and electron microscopy approach to study the subcellular localization of phosphorylated vimentin in human lung tissue.

Correlative microscopy is an important approach for bridging the resolution gap between fluorescence light and electron microscopy. Here, we describe a fast and simple method for correlative immunofluorescence and immunogold labeling on the same section to elucidate the localization of phosphorylated vimentin (P-Vim), a robust feature of pulmonary vascular remodeling in cells of human lung small arteries. The lung is a complex, soft and difficult tissue to prepare for transmission electron microscopy (TEM). Detailing the molecular composition of small pulmonary arteries (<500µm) would be of great significance for research and diagnostics. Using the classical methods of immunochemistry (either hydrophilic resin or thin cryosections), is difficult to locate small arteries for analysis by TEM. To address this problem and to observe the same structures by both light and electron microscopy, correlative microscopy is a reliable approach. Immunofluorescence enables us to know the distribution of P-Vim in cells but does not provide ultrastructural detail on its localization. Labeled structures selected by fluorescence microscope can be identified and further analyzed by TEM at high resolution. With our method, the morphology of the arteries is well preserved, enabling the localization of P-Vim inside pulmonary endothelial cells. By applying this approach, fluorescent signals can be directly correlated to the corresponding subcellular structures in areas of interest.

In Vitro Experimental Approach for Studying Human Pulmonary Artery Smooth Muscle Cells and Endothelial Cells Proliferation and Migration.

Pulmonary arterial hypertension (PAH) is a severe vascular disease characterized by persistent precapillary pulmonary hypertension, leading to right heart failure and death. Despite intense research in the last decades, PAH remains an incurable disease with high morbidity and mortality. New directions and therapies to improve understanding and treatment of PAH are desperately needed. The pathological mechanisms leading to this fatal disorder remain mostly undetermined, although structural remodeling of the pulmonary vessels is known to be an early feature of PAH. Pulmonary vascular remodeling includes proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells (PAECs). The use of in vitro approaches is useful to delineate the mechanisms involved in the pathogenesis of PAH and to identify new therapeutic strategies for PAH. In this chapter, we describe protocols for culturing and assessing proliferation and migration of human PASMCs and PAECs.

Pirfenidone and nintedanib attenuates pulmonary artery endothelial and smooth muscle cells transformations induced by IL-11.

Idiopathic pulmonary fibrosis (IPF) associated to pulmonary hypertension (PH) portends a poor prognosis, characterized by lung parenchyma fibrosis and pulmonary artery remodeling. Serum and parenchyma levels of Interleukin 11 (IL-11) are elevated in IPF-PH patients and contributes to pulmonary artery remodeling and PH. However, the effect of current approved therapies against IPF in pulmonary artery remodeling induced by IL-11 is unknown. The aim of this study is to analyze the effects of nintedanib and pirfenidone on pulmonary artery endothelial and smooth muscle cell remodeling induced by IL-11 in vitro. Our results show that nintedanib (NTD) and pirfenidone (PFD) ameliorates endothelial to mesenchymal transition (EnMT), pulmonary artery smooth muscle cell to myofibroblast-like transformation and pulmonary remodeling in precision lung cut slices. This study provided also evidence of the inhibitory effect of PFD and NTD on IL-11-induced endothelial and muscle cells proliferation and senescence. The inhibitory effect of these drugs on monocyte arrest and angiogenesis was also studied. Finally, we observed that IL-11 induced canonical signal transducer and activator of transcription 3 (STAT3) and non-canonical mitogen-activated protein kinase 1/2 (ERK1/2) phosphorylation, but, PFD and NTD only inhibited ERK1/2 phosphorylation. Therefore, this study provided evidence of the inhibitory effect of NTD and PFD on markers of pulmonary artery remodeling induced by IL-11.

Effect of RNA interference with HIF-1α on the growth of pulmonary artery endothelial cells in broiler chickens.

Pulmonary artery remodeling is a characteristic feature of broiler ascites syndrome (BAS). Pulmonary artery endothelial cells (PAECs) regulated by HIF-1α play a critical role in pulmonary artery remodeling, but the underlying mechanisms of HIF-1α in BAS remain unclear. In this experiment, primary PAECs were cultured in vitro and were identified by coagulation factor VIII. After hypoxia and RNA interference, the mRNA and protein expression levels of HIF-1α and VEGF were determined by qPCR and Western blotting. The transcriptome profiles of PAECs were obtained by RNA sequencing. Our results showed that the positive rate of PAECs was more than 90%, hypoxia-induced promoted the proliferation and apoptosis of PAECs, and RNA interference significantly downregulated the expression of HIF-1α, inhibited the proliferation of PAECs, and promoted the apoptosis of PAECs. In addition, transcriptome sequencing analysis indicated that HIF-1α may regulate broiler ascites syndrome by mediating COL4A, vitronectin, vWF, ITGα8, and MKP-5 in the ECM, CAMs and MAPK pathways in PAECs. These studies lay the foundation for further exploration of the mechanisms of pulmonary artery remodeling, and HIF-1α may be a potentially effective gene for the prevention and treatment of BAS.

NCAPG Promotes Pulmonary Artery Smooth Muscle Cell Proliferation as a Promising Therapeutic Target of Idiopathic Pulmonary Hypertension: Bioinformatics Analysis and Experiment Verification.

Idiopathic pulmonary arterial hypertension (IPAH) is a disease with complex etiology. Currently, IPAH treatment is limited, and patients' prognosis is poor. This study aimed to explore new therapeutic targets in IPAH through bioinformatics. Two data sets (GSE113439 and GSE130391) meeting the requirements were obtained from the Gene Expression Omnibus (GEO) database. Then, differentially expressed genes (DEGs) were identified and analyzed by NetworkAnalyst platform. By enriching Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG), we examined the function of DEGs. A protein-protein interaction (PPI) network was constructed to identify central genes using the CytoNCA plug-in. Finally, four central genes, ASPM, CENPE, NCAPG, and TOP2A, were screened out. We selected NCAPG for protein-level verification. We established an animal model of PAH and found that the expression of NCAPG was significantly increased in the lung tissue of PAH rats. In vitro experiments showed that the expression of NCAPG was significantly increased in proliferative pulmonary arterial smooth muscle cells (PASMCs). When NCAPG of PASMCs was knocked down, the cell proliferation was inhibited, which suggested that NCAPG was related to the proliferation of PASMCs. Therefore, these results may provide new therapeutic targets for IPAH.

Mechanosensitive cation currents through TRPC6 and Piezo1 channels in human pulmonary arterial endothelial cells.

Mechanosensitive cation channels and Ca2+ influx through these channels play an important role in the regulation of endothelial cell functions. Transient receptor potential canonical channel 6 (TRPC6) is a diacylglycerol-sensitive nonselective cation channel that forms receptor-operated Ca2+ channels in a variety of cell types. Piezo1 is a mechanosensitive cation channel activated by membrane stretch and shear stress in lung endothelial cells. In this study, we report that TRPC6 and Piezo1 channels both contribute to membrane stretch-mediated cation currents and Ca2+ influx or increase in cytosolic-free Ca2+ concentration ([Ca2+]cyt) in human pulmonary arterial endothelial cells (PAECs). The membrane stretch-mediated cation currents and increase in [Ca2+]cyt in human PAECs were significantly decreased by GsMTX4, a blocker of Piezo1 channels, and by BI-749327, a selective blocker of TRPC6 channels. Extracellular application of 1-oleoyl-2-acetyl-sn-glycerol (OAG), a membrane permeable analog of diacylglycerol, rapidly induced whole cell cation currents and increased [Ca2+]cyt in human PAECs and human embryonic kidney (HEK)-cells transiently transfected with the human TRPC6 gene. Furthermore, membrane stretch with hypo-osmotic or hypotonic solution enhances the cation currents in TRPC6-transfected HEK cells. In HEK cells transfected with the Piezo1 gene, however, OAG had little effect on the cation currents, but membrane stretch significantly enhanced the cation currents. These data indicate that, while both TRPC6 and Piezo1 are involved in generating mechanosensitive cation currents and increases in [Ca2+]cyt in human PAECs undergoing mechanical stimulation, only TRPC6 (but not Piezo1) is sensitive to the second messenger diacylglycerol. Selective blockers of these channels may help develop novel therapies for mechanotransduction-associated pulmonary vascular remodeling in patients with pulmonary arterial hypertension.

Metabolic profile in endothelial cells of chronic thromboembolic pulmonary hypertension and pulmonary arterial hypertension.

Chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH) are two forms of pulmonary hypertension (PH) characterized by obstructive vasculopathy. Endothelial dysfunction along with metabolic changes towards increased glycolysis are important in PAH pathophysiology. Less is known about such abnormalities in endothelial cells (ECs) from CTEPH patients. This study provides a systematic metabolic comparison of ECs derived from CTEPH and PAH patients. Metabolic gene expression was studied using qPCR in cultured CTEPH-EC and PAH-EC. Western blot analyses were done for HK2, LDHA, PDHA1, PDK and G6PD. Basal viability of CTEPH-EC and PAH-EC with the incubation with metabolic inhibitors was measured using colorimetric viability assays. Human pulmonary artery endothelial cells (HPAEC) were used as healthy controls. Whereas PAH-EC showed significant higher mRNA levels of GLUT1, HK2, LDHA, PDHA1 and GLUD1 metabolic enzymes compared to HPAEC, CTEPH-EC did not. Oxidative phosphorylation associated proteins had an increased expression in PAH-EC compared to CTEPH-EC and HPAEC. PAH-EC, CTEPH-EC and HPAEC presented similar HOXD macrovascular gene expression. Metabolic inhibitors showed a dose-dependent reduction in viability in all three groups, predominantly in PAH-EC. A different metabolic profile is present in CTEPH-EC compared to PAH-EC and suggests differences in molecular mechanisms important in the disease pathology and treatment.

hsa_circWDR37_016 Regulates Hypoxia-Induced Proliferation of Pulmonary Arterial Smooth Muscle Cells.

Pulmonary arterial hypertension (PAH) is characterized by abnormal remodeling of pulmonary vessel walls caused by excessive pulmonary arterial smooth muscle cell (PASMC) proliferation. Our previous clinical studies have demonstrated the importance of the downregulated circRNA in PAH. However, the role of upregulated circRNAs is still elusive. Here, we identified the upregulated circRNA in PAH patients, hsa_circWDR37_016 (circWDR37), as a key regulator of hypoxic proliferative disorder of pulmonary arterial smooth muscle cells (PASMCs). Quantitative real-time PCR (qRT-PCR) analysis validated that exposure to hypoxia markedly increased the circWDR37 level in cultured human PASMCs. As evidenced by flow cytometry, 5-ethynyl-2'-deoxyuridine (EdU) incorporation, wound healing, and Tunel assay, silencing of endogenous circWDR37 attenuated proliferation and cell-cycle progression in hypoxia-exposed human PASMCs in vitro. Furthermore, bioinformatics and Luciferase assay showed that circWDR37 directly sponged hsa-miR-138-5p (miR-138) and was involved in the immunoregulatory and inflammatory processes of PAH. Together, these studies suggested new insights into circRNA regulated the pathology of PAH, providing a new potential therapeutic target for PAH treatment.

Deep-learning-assisted Fourier transform imaging spectroscopy for hyperspectral fluorescence imaging.

Hyperspectral fluorescence imaging is widely used when multiple fluorescent probes with close emission peaks are required. In particular, Fourier transform imaging spectroscopy (FTIS) provides unrivaled spectral resolution; however, the imaging throughput is very low due to the amount of interferogram sampling required. In this work, we apply deep learning to FTIS and show that the interferogram sampling can be drastically reduced by an order of magnitude without noticeable degradation in the image quality. For the demonstration, we use bovine pulmonary artery endothelial cells stained with three fluorescent dyes and 10 types of fluorescent beads with close emission peaks. Further, we show that the deep learning approach is more robust to the translation stage error and environmental vibrations. Thereby, the He-Ne correction, which is typically required for FTIS, can be bypassed, thus reducing the cost, size, and complexity of the FTIS system. Finally, we construct neural network models using Hyperband, an automatic hyperparameter selection algorithm, and compare the performance with our manually-optimized model.

Pretreatment with the active fraction of Rhodiola tangutica (Maxim.) S.H. Fu rescues hypoxia-induced potassium channel inhibition in rat pulmonary artery smooth muscle cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Previous studies have shown that the active fraction of Rhodiola tangutica (Maxim.) S.H. Fu (ACRT) dilates pulmonary arteries and thwarts pulmonary artery remodelling. The dilatation effect of ACRT on pulmonary artery vascular rings could be reduced by potassium (K+) channel blockers. However the exact mechanisms of ACRT on ion channels are still unclear. AIM OF THE STUDY: This study aimed to investigate whether the effect of ACRT on K+ channels inhibits cell proliferation after pulmonary artery smooth muscle cells (PASMCs) are exposed to hypoxia. MATERIALS AND METHODS: The whole-cell patch-clamp method was used to clarify the effect of ACRT on the K+ current (IK) of rat PASMCs exposed to hypoxia. The mRNA and protein expression levels were detected using real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting, respectively. The intracellular calcium (Ca2+) concentration ([Ca2+]i) values in rat PASMCs were detected by laser scanning confocal microscopy. The cell cycle and cell proliferation were assessed using flow cytometry analysis and CCK-8 and EdU assays. RESULTS: ACRT pretreatment alleviated the inhibition of IK induced by hypoxia in rat PASMCs. Compared with hypoxia, ACRT upregulated voltage-dependent K+ channel (Kv) 1.5 and big-conductance calcium-activated K+ channel (BKCa) mRNA and protein expression and downregulated voltage-dependent Ca2+ channel (Cav) 1.2 mRNA and protein expression. ACRT decreased [Ca2+]i, inhibited the promotion of cyclin D1 and proliferating cell nuclear antigen (PCNA) expression, and prevented the proliferation of rat PASMCs exposed to hypoxia. CONCLUSION: In conclusion, the present study demonstrated that ACRT plays a key role in restoring ion channel function and then inhibiting the proliferation of PASMCs under hypoxia, ACRT has preventive and therapeutic potential in hypoxic pulmonary hypertension.

Protective effects of progesterone on pulmonary artery smooth muscle cells stimulated with Interleukin 6 via blocking the shuttling and transcriptional function of STAT3.

BACKGROUND: Sex hormone paradox is a crucial but unresolved issue in the field of pulmonary artery hypertension (PAH), and is thought to be related to different pathogenic factors. Inflammation is one of pathological mechanisms of PAH development. However, effects of sex hormones on the pulmonary vasculature under the condition of inflammation are still elusive. METHODS: Interleukin-6 (IL-6) was used as a representative inflammatory stimulator. Effects of 17ß-estradiol or progesterone on human pulmonary artery smooth muscle cells (PASMCs) were measured under the condition of IL-6. Cell functions of proliferation and migration were measured by Alarmar Blue, EdU assay, wound-healing assay and transwell chambers. We explored further mechanisms using western blot, immunofluorescence, co-immunoprecipitation, qPCR and chromatin immunoprecipitation. RESULTS: Our results revealed that IL-6 promoted the proliferation of PASMCs, but progesterone could reverse the adverse effect of IL-6. The protective effect was dependent on progesterone receptor (PGR). By interacting with signal transducer and activator of transcription 3 (STAT3), activated PGR could reduce the IL-6-induced nuclear translocation of STAT3 and prevent STAT3-chromatin binding in PASMCs, leading to the decreased transcription of downstream CCND1 and BCL2. Alternatively, progesterone slightly decreased the phosphorylation of pro-proliferative Erk1/2 and Akt kinases and upregulated the anti-proliferative pSmad1-Id1/2 axis in IL-6-incubated PASMCs. CONCLUSIONS: Progesterone played a protective role on PASMCs in the context of IL-6, by blocking the functions of STAT3. Our findings might assist in explaining the clinical phenomenon of better prognosis for women with PAH.

A Microfluidic System for Simultaneous Raman Spectroscopy, Patch-Clamp Electrophysiology, and Live-Cell Imaging to Study Key Cellular Events of Single Living Cells in Response to Acute Hypoxia.

The ability to sense changes in oxygen availability is fundamentally important for the survival of all aerobic organisms. However, cellular oxygen sensing mechanisms and pathologies remain incompletely understood and studies of acute oxygen sensing, in particular, have produced inconsistent results. Current methods cannot simultaneously measure the key cellular events in acute hypoxia (i.e., changes in redox state, electrophysiological properties, and mechanical responses) at controlled partial pressures of oxygen (pO2 ). The lack of such a comprehensive method essentially contributes to the discrepancies in the field. A sealed microfluidic system that combines i) Raman spectroscopy, ii) patch-clamp electrophysiology, and iii) live-cell imaging under precisely controlled pO2 have therefore been developed. Merging these modalities allows label-free and simultaneous observation of oxygen-dependent alterations in multiple cellular redox couples, membrane potential, and cellular contraction. This technique is adaptable to any cell type and allows in-depth insight into acute oxygen sensing processes underlying various physiologic and pathologic conditions.

Incremental Experience in In Vitro Primary Culture of Human Pulmonary Arterial Endothelial Cells Harvested from Swan-Ganz Pulmonary Arterial Catheters.

Pulmonary arterial hypertension (PAH) is a devastating condition affecting the pulmonary microvascular wall and endothelium, resulting in their partial or total obstruction. Despite a combination of expensive vasodilatory therapies, mortality remains high. Personalized therapeutic approaches, based on access to patient material to unravel patient specificities, could move the field forward. An innovative technique involving harvesting pulmonary arterial endothelial cells (PAECs) at the time of diagnosis was recently described. The aim of the present study was to fine-tune the initial technique and to phenotype the evolution of PAECs in vitro subcultures. PAECs were harvested from Swan-Ganz pulmonary arterial catheters during routine diagnostic or follow up right heart catheterization. Collected PAECs were phenotyped by flow cytometry and immunofluorescence focusing on endothelial-specific markers. We highlight the ability to harvest patients' PAECs and to maintain them for up to 7-12 subcultures. By tracking the endothelial phenotype, we observed that PAECs could maintain an endothelial phenotype for several weeks in culture. The present study highlights the unique opportunity to obtain homogeneous subcultures of primary PAECs from patients at diagnosis and follow-up. In addition, it opens promising perspectives regarding tailored precision medicine for patients suffering from rare pulmonary vascular diseases.

HIF-1α promotes the proliferation and migration of pulmonary arterial smooth muscle cells via activation of Cx43.

The proliferation of pulmonary artery smooth muscle cells (PASMCs) is an important cause of pulmonary vascular remodelling in hypoxia-induced pulmonary hypertension (HPH). However, its underlying mechanism has not been well elucidated. Connexin 43 (Cx43) plays crucial roles in vascular smooth muscle cell proliferation in various cardiovascular diseases. Here, the male Sprague-Dawley (SD) rats were exposed to hypoxia (10% O2 ) for 21 days to induce rat HPH model. PASMCs were treated with CoCl2 (200 µM) for 24 h to establish the HPH cell model. It was found that hypoxia up-regulated the expression of Cx43 and phosphorylation of Cx43 at Ser 368 in rat pulmonary arteries and PASMCs, and stimulated the proliferation and migration of PASMCs. HIF-1α inhibitor echinomycin attenuated the CoCl2 -induced Cx43 expression and phosphorylation of Cx43 at Ser 368 in PASMCs. The interaction between HIF-1α and Cx43 promotor was also identified using chromatin immunoprecipitation assay. Moreover, Cx43 specific blocker (37,43 Gap27) or knockdown of Cx43 efficiently alleviated the proliferation and migration of PASMCs under chemically induced hypoxia. Therefore, the results above suggest that HIF-1α, as an upstream regulator, promotes the expression of Cx43, and the HIF-1α/Cx43 axis regulates the proliferation and migration of PASMCs in HPH.

Derivation and characterisation of endothelial cells from patients with chronic thromboembolic pulmonary hypertension.

Pulmonary endarterectomy (PEA) resected material offers a unique opportunity to develop an in vitro endothelial cell model of chronic thromboembolic pulmonary hypertension (CTEPH). We aimed to comprehensively analyze the endothelial function, molecular signature, and mitochondrial profile of CTEPH-derived endothelial cells to better understand the pathophysiological mechanisms of endothelial dysfunction behind CTEPH, and to identify potential novel targets for the prevention and treatment of the disease. Isolated cells from specimens obtained at PEA (CTEPH-EC), were characterized based on morphology, phenotype, and functional analyses (in vitro and in vivo tubule formation, proliferation, apoptosis, and migration). Mitochondrial content, morphology, and dynamics, as well as high-resolution respirometry and oxidative stress, were also studied. CTEPH-EC displayed a hyperproliferative phenotype with an increase expression of adhesion molecules and a decreased apoptosis, eNOS activity, migration capacity and reduced angiogenic capacity in vitro and in vivo compared to healthy endothelial cells. CTEPH-EC presented altered mitochondrial dynamics, increased mitochondrial respiration and an unbalanced production of reactive oxygen species and antioxidants. Our study is the foremost comprehensive investigation of CTEPH-EC. Modulation of redox, mitochondrial homeostasis and adhesion molecule overexpression arise as novel targets and biomarkers in CTEPH.

Prenatal hypoxia induced ETBR activation and abnormal ROS signalling in pulmonary artery cells of rat offspring.

Pulmonary arterial hypertension is a progressive disorder characterized by remodeling and increased small pulmonary arteries resistance. Endothelin-1 (ET-1) was related to PAH and ET-1 receptors were up-regulated selectively in the lung when exposed to toxic factor hypoxia. However, the role of ET-1 signaling in the pathogenesis of prenatal hypoxia-induced pulmonary abnormalities remains to be elucidated. Pregnant rats were divided into prenatal hypoxia (10.5 % O2 from gestational day 4-21) and control group. Their three-month-old offspring male rats were tested for vascular functions and molecular analysis, DNA methylation was assessed for cellular hypoxia. Functional testing showed that ET-1-mediated vasoconstriction was enhanced, and the expressions of endothelin A receptor/B receptor (ETAR/ETBR), inositol 1,4,5-trisphosphate receptor, type 1, and the sensitivity of calcium channels were increased in the small pulmonary arteries following prenatal hypoxia. q-PCR and DHE staining showed that the expressions of NADPH oxidase 1/4 (Nox1/4) were up-regulated, along with the increased production of superoxide anion. Furthermore, superoxide anion promoted ET-1-mediated pulmonary artery contraction. In the pulmonary artery smooth muscle cell experiments, q-PCR, Western Blot, CCK8 and DHE staining showed that the expressions of ETBR, Nox1/4, and superoxide anion were increased by hypoxia, along with promoted cell proliferation. 2,2,6,6-Tetramethyl-1-piperidinyloxy reversed hypoxia-induced cell proliferation. ETBR antagonist BQ788 inhibited hypoxia-increased expressions of Nox1/4, superoxide anion production, and proliferation of cells. Moreover, methylation analysis indicated that hypoxia decreased the methylation levels of the ETBR promoter in the pulmonary artery smooth muscle cells. The results indicated that prenatal toxic factor hypoxia resulted in abnormal ETBR activation, which enhanced ET-1-mediated vasoconstriction of pulmonary arteries and pulmonary artery smooth muscle cell proliferation through ETBR/Nox1/4-derived ROS pathway.

Small-molecule inhibitor LF3 restrains the development of pulmonary hypertension through the Wnt/ß-catenin pathway.

Pulmonary hypertension (PH) associated with congenital heart disease is a progressive hemodynamic disease that can lead to increased pulmonary vascular resistance, vascular remodeling, and even right heart failure and death. LF3 is a novel inhibitor of the reporter gene activity of ß-catenin/TCF4 interaction in the Wnt/ß-catenin signal pathway. However, whether this action of LF3 can prevent PH development remains unclear. In this study, we investigated the therapeutic effect of LF3 in rat primary pulmonary artery smooth muscle cells (PASMCs) of the PH model. We found that LF3 inhibited the decrease in pulmonary artery acceleration time and ejection time by ultra-high-resolution ultrasound imaging and blocked the increase of pulmonary artery systolic pressure by using the BL420 biological function experimental system and right ventricular hypertrophy index by the electronic scales. Simultaneously, it prevented the increase of α-smooth muscle actin and fibronectin and the decrease of elastin in pulmonary arteries of rats in the PH group, as revealed by an immunohistochemical analysis. Moreover, cell proliferation and migration assays showed that LF3 significantly reduced the proliferation and migration of PASMCs. Western blotting and quantitative real-time polymerase chain reaction analyses revealed that LF3 suppressed the expression of proliferating cell nuclear antigens and Bcl-2 and increased the expression of Bax but did not alter the expressions of ß-catenin and TCF4. Taken together, LF3 can reduce the migration and proliferation of PASMCs and induce their apoptosis to prevent the development of PH. It would be worthwhile to explore the potential use of LF3 in the treatment of PH.

Cell-Free Hemoglobin Does Not Attenuate the Effects of SARS-CoV-2 Spike Protein S1 Subunit in Pulmonary Endothelial Cells.

SARS-CoV-2 primarily infects epithelial airway cells that express the host entry receptor angiotensin-converting enzyme 2 (ACE2), which binds to the S1 spike protein on the surface of the virus. To delineate the impact of S1 spike protein interaction with the ACE2 receptor, we incubated the S1 spike protein with human pulmonary arterial endothelial cells (HPAEC). HPAEC treatment with the S1 spike protein caused disruption of endothelial barrier function, increased levels of numerous inflammatory molecules (VCAM-1, ICAM-1, IL-1ß, CCL5, CXCL10), elevated mitochondrial reactive oxygen species (ROS), and a mild rise in glycolytic reserve capacity. Because low oxygen tension (hypoxia) is associated with severe cases of COVID-19, we also evaluated treatment with hemoglobin (HbA) as a potential countermeasure in hypoxic and normal oxygen environments in analyses with the S1 spike protein. We found hypoxia downregulated the expression of the ACE2 receptor and increased the critical oxygen homeostatic signaling protein, hypoxia-inducible factor (HIF-1α); however, treatment of the cells with HbA yielded no apparent change in the levels of ACE2 or HIF-1α. Use of quantitative proteomics revealed that S1 spike protein-treated cells have few differentially regulated proteins in hypoxic conditions, consistent with the finding that ACE2 serves as the host viral receptor and is reduced in hypoxia. However, in normoxic conditions, we found perturbed abundance of proteins in signaling pathways related to lysosomes, extracellular matrix receptor interaction, focal adhesion, and pyrimidine metabolism. We conclude that the spike protein alone without the rest of the viral components is sufficient to elicit cell signaling in HPAEC, and that treatment with HbA failed to reverse the vast majority of these spike protein-induced changes.

Suppression of reactive oxygen species in endothelial cells by an antagonist of growth hormone-releasing hormone.

Growth hormone-releasing hormone (GHRH) is a hypothalamic hormone, which regulates the secretion of growth hormone (GH) from the anterior pituitary gland. The effects of GHRH extend beyond the GH-insulin-like growth factor I axis, and that neuropeptide has been involved in the potentiation of several malignancies and other inflammatory disorders. The development of GHRH antagonists (GHRHAnt) delivers an exciting possibility to counteract the pathogenesis of the GHRH-related effects in human pathophysiology, especially when considered that GHRHAnt support endothelial barrier integrity. Those GHRHAnt-mediated effects are exerted at least in part due to the suppression of major inflammatory pathways, and the modulation of major cytoskeletal components. In the present study, we measured the production of reactive oxygen species (ROS) in bovine pulmonary artery endothelial cells, human cerebral microvascular endothelial cells, and human lung microvascular endothelial cells exposed to GHRH or a commercially available GHRHAnt. Our findings reveal the antioxidative effects of GHRHAnt in all three cell lines, which express GHRH receptors. The redox status of NIH/3T3 cells, which do not produce GHRH receptors, was not significantly affected by GHRH or GHRHAnt. Hence, the application of GHRHAnt in pathologies related to increased ROS production should be further investigated.