Guidelines for Assessing Maternal Cardiovascular Physiology During Pregnancy and Postpartum

Maternal mortality rates are at an all-time high across the world and are set to increase in subsequent years. Cardiovascular disease is the leading cause of death during pregnancy and postpartum, especially in the US. Therefore, understanding the physiological changes in the cardiovascular system during normal pregnancy is necessary to understand disease-related pathology. Significant systemic and cardiovascular physiological changes occur during pregnancy that are essential for supporting the maternal-fetal dyad. The physiological impact of pregnancy on the cardiovascular system has been examined in both experimental animal models and in humans. However, there is a continued need in this field of study to provide increased rigor and reproducibility. Therefore, these guidelines aim to provide information regarding best practices and recommendations to accurately and rigorously measure cardiovascular physiology during normal and cardiovascular-disease-complicated pregnancies in human and animal models.

Functions of RNA-Binding Proteins in Cardiovascular Disease

Gene expression is under tight regulation from the chromatin structure that regulates gene accessibility by the transcription machinery to protein degradation. At the transcript level, this regulation falls on RNA-binding proteins (RBPs). RBPs are a large and diverse class of proteins involved in all aspects of a transcript's lifecycle: splicing and maturation, localization, stability, and translation. In the past few years, our understanding of the role of RBPs in cardiovascular diseases has expanded. Here, we discuss the general structure and function of RBPs and the latest discoveries of their role in pulmonary and systemic cardiovascular diseases.

Amnion responses to intrauterine inflammation and effects of inhibition of TNF signaling in preterm Rhesus macaque

Intrauterine infection/inflammation (IUI) is a frequent complication of pregnancy leading to preterm labor and fetal inflammation. How inflammation is modulated at the maternal-fetal interface is unresolved. We compared transcriptomics of amnion (a fetal tissue in contact with amniotic fluid) in a preterm Rhesus macaque model of IUI induced by lipopolysaccharide with human cohorts of chorioamnionitis. Bulk RNA sequencing (RNA-seq) amnion transcriptomic profiles were remarkably similar in both Rhesus and human subjects and revealed that induction of key labor-mediating genes such as IL1 and IL6 was dependent on nuclear factor κB (NF-κB) signaling and reversed by the anti-tumor necrosis factor (TNF) antibody Adalimumab. Inhibition of collagen biosynthesis by IUI was partially restored by Adalimumab. Interestingly, single-cell transcriptomics, flow cytometry, and immunohistology demonstrated that a subset of amnion mesenchymal cells (AMCs) increase CD14 and other myeloid cell markers during IUI both in the human and Rhesus macaque. Our data suggest that CD14+ AMCs represent activated AMCs at the maternal-fetal interface.

17 β-Estradiol Impedes Aortic Root Dilation and Rupture in Male Marfan Mice

Marfan syndrome causes a hereditary form of thoracic aortic aneurysms with worse outcomes in male compared to female patients. In this study, we examine the effects of 17 β-estradiol on aortic dilation and rupture in a Marfan mouse model. Marfan male mice were administered 17 β-estradiol, and the growth in the aortic root, along with the risk of aortic rupture, was measured. Transcriptomic profiling was used to identify enriched pathways from 17 β-estradiol treatments. Aortic smooth muscle cells were then treated with cytokines to validate functional mechanisms. We show that 17 β-estradiol decreased the size and rate of aortic root dilation and improved survival from rupture. The Marfan transcriptome was enriched in inflammatory genes, and the addition of 17 β-estradiol modulated a set of genes that function through TNFα mediated NF-κB signaling. In addition, 17 β-estradiol suppressed the induction of these TNFα induced genes in aortic smooth muscle cells in vitro in an NF-κB dependent manner, and 17 β-estradiol decreased the formation of adventitial inflammatory foci in aortic roots in vivo. In conclusion, 17 β-estradiol protects against the dilation and rupture of aortic roots in Marfan male mice through the inhibition of TNFα-NF-κB signaling.

Sex Differences in Therapies against Myocardial Ischemia-Reperfusion Injury: From Basic Science to Clinical Perspectives

Mortality from myocardial infarction (MI) has declined over recent decades, which could be attributed in large part to improved treatment methods. Early reperfusion is the cornerstone of current MI treatment. However, reoxygenation via restored blood flow induces further damage to the myocardium, leading to ischemia-reperfusion injury (IRI). While experimental studies overwhelmingly demonstrate that females experience greater functional recovery from MI and decreased severity in the underlying pathophysiological mechanisms, the outcomes of MI with subsequent reperfusion therapy, which is the clinical correlate of myocardial IRI, are generally poorer for women compared with men. Distressingly, women are also reported to benefit less from current guideline-based therapies compared with men. These seemingly contradicting outcomes between experimental and clinical studies show a need for further investigation of sex-based differences in disease pathophysiology, treatment response, and a sex-specific approach in the development of novel therapeutic methods against myocardial IRI. In this literature review, we summarize the current knowledge on sex differences in the underlying pathophysiological mechanisms of myocardial IRI, including the roles of sex hormones and sex chromosomes. Furthermore, we address sex differences in pharmacokinetics, pharmacodynamics, and pharmacogenetics of current drugs prescribed to limit myocardial IRI. Lastly, we highlight ongoing clinical trials assessing novel pharmacological treatments against myocardial IRI and sex differences that may underlie the efficacy of these new therapeutic approaches.

Myocardial fibrosis and calcification are attenuated by microRNA-129-5p targeting Asporin and Sox9 in cardiac fibroblasts

Myocardial fibrosis and calcification associate with adverse outcomes in nonischemic heart failure. Cardiac fibroblasts (CF) transition into myofibroblasts (MF) and osteogenic fibroblasts (OF) to promote myocardial fibrosis and calcification. However, common upstream mechanisms regulating both CF-to-MF transition and CF-to-OF transition remain unknown. microRNAs are promising targets to modulate CF plasticity. Our bioinformatics revealed downregulation of miR-129-5p and upregulation of its targets small leucine-rich proteoglycan Asporin (ASPN) and transcription factor SOX9 as common in mouse and human heart failure (HF). We experimentally confirmed decreased miR-129-5p and enhanced SOX9 and ASPN expression in CF in human hearts with myocardial fibrosis and calcification. miR-129-5p repressed both CF-to-MF and CF-to-OF transition in primary CF, as did knockdown of SOX9 and ASPN. Sox9 and Aspn are direct targets of miR-129-5p that inhibit downstream β-catenin expression. Chronic Angiotensin II infusion downregulated miR-129-5p in CF in WT and TCF21-lineage CF reporter mice, and it was restored by miR-129-5p mimic. Importantly, miR-129-5p mimic not only attenuated progression of myocardial fibrosis, calcification marker expression, and SOX9 and ASPN expression in CF but also restored diastolic and systolic function. Together, we demonstrate miR-129-5p/ASPN and miR-129-5p/SOX9 as potentially novel dysregulated axes in CF-to-MF and CF-to-OF transition in myocardial fibrosis and calcification and the therapeutic relevance of miR-129-5p.

Tm4sf1-marked Endothelial Subpopulation Is Dysregulated in Pulmonary Arterial Hypertension

The identification and role of endothelial progenitor cells in pulmonary arterial hypertension (PAH) remain controversial. Single-cell omics analysis can shed light on endothelial progenitor cells and their potential contribution to PAH pathobiology. We aim to identify endothelial cells that may have stem/progenitor potential in rat lungs and assess their relevance to PAH. Differential expression, gene set enrichment, cell-cell communication, and trajectory reconstruction analyses were performed on lung endothelial cells from single-cell RNA sequencing of Sugen-hypoxia, monocrotaline, and control rats. Relevance to human PAH was assessed in multiple independent blood and lung transcriptomic data sets. Rat lung endothelial cells were visualized by immunofluorescence in situ, analyzed by flow cytometry, and assessed for tubulogenesis in vitro. A subpopulation of endothelial cells (endothelial arterial type 2 [EA2]) marked by Tm4sf1 (transmembrane 4 L six family member 1), a gene strongly implicated in cancer, harbored a distinct transcriptomic signature enriched for angiogenesis and CXCL12 signaling. Trajectory analysis predicted that EA2 has a less differentiated state compared with other endothelial subpopulations. Analysis of independent data sets revealed that TM4SF1 is downregulated in lungs and endothelial cells from patients and PAH models, is a marker for hematopoietic stem cells, and is upregulated in PAH circulation. TM4SF1+CD31+ rat lung endothelial cells were visualized in distal pulmonary arteries, expressed hematopoietic marker CD45, and formed tubules in coculture with lung fibroblasts. Our study uncovered a novel Tm4sf1-marked subpopulation of rat lung endothelial cells that may have stem/progenitor potential and demonstrated its relevance to PAH. Future studies are warranted to further elucidate the role of EA2 and Tm4sf1 in PAH.

Integrative Multiomics to Dissect the Lung Transcriptional Landscape of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) remains an incurable and often fatal disease despite currently available therapies. Multiomics systems biology analysis can shed new light on PAH pathobiology and inform translational research efforts. Using RNA sequencing on the largest PAH lung biobank to date (96 disease and 52 control), we aim to identify gene co-expression network modules associated with PAH and potential therapeutic targets. Co-expression network analysis was performed to identify modules of co-expressed genes which were then assessed for and prioritized by importance in PAH, regulatory role, and therapeutic potential via integration with clinicopathologic data, human genome-wide association studies (GWAS) of PAH, lung Bayesian regulatory networks, single-cell RNA-sequencing data, and pharmacotranscriptomic profiles. We identified a co-expression module of 266 genes, called the pink module, which may be a response to the underlying disease process to counteract disease progression in PAH. This module was associated not only with PAH severity such as increased PVR and intimal thickness, but also with compensated PAH such as lower number of hospitalizations, WHO functional class and NT-proBNP. GWAS integration demonstrated the pink module is enriched for PAH-associated genetic variation in multiple cohorts. Regulatory network analysis revealed that BMPR2 regulates the main target of FDA-approved riociguat, GUCY1A2, in the pink module. Analysis of pathway enrichment and pink hub genes (i.e. ANTXR1 and SFRP4) suggests the pink module inhibits Wnt signaling and epithelial-mesenchymal transition. Cell type deconvolution showed the pink module correlates with higher vascular cell fractions (i.e. myofibroblasts). A pharmacotranscriptomic screen discovered ubiquitin-specific peptidases (USPs) as potential therapeutic targets to mimic the pink module signature. Our multiomics integrative study uncovered a novel gene subnetwork associated with clinicopathologic severity, genetic risk, specific vascular cell types, and new therapeutic targets in PAH. Future studies are warranted to investigate the role and therapeutic potential of the pink module and targeting USPs in PAH.

HNRNPA2B1: RNA-Binding Protein That Orchestrates Smooth Muscle Cell Phenotype in Pulmonary Arterial Hypertension

BACKGROUND

RNA-binding proteins are master orchestrators of gene expression regulation. They regulate hundreds of transcripts at once by recognizing specific motifs. Thus, characterizing RNA-binding proteins targets is critical to harvest their full therapeutic potential. However, such investigation has often been restricted to a few RNA-binding protein targets, limiting our understanding of their function. In cancer, the RNA-binding protein HNRNPA2B1 (heterogeneous nuclear ribonucleoprotein A2B1; A2B1) promotes the pro-proliferative/anti-apoptotic phenotype. The same phenotype in pulmonary arterial smooth muscle cells (PASMCs) is responsible for the development of pulmonary arterial hypertension (PAH). However, A2B1 function has never been investigated in PAH.

METHOD

Through the integration of computational and experimental biology, the authors investigated the role of A2B1 in human PAH-PASMC. Bioinformatics and RNA sequencing allowed them to investigate the transcriptome-wide function of A2B1, and RNA immunoprecipitation and A2B1 silencing experiments allowed them to decipher the intricate molecular mechanism at play. In addition, they performed a preclinical trial in the monocrotaline-induced pulmonary hypertension rat model to investigate the relevance of A2B1 inhibition in mitigating pulmonary hypertension severity.

RESULTS

They found that A2B1 expression and its nuclear localization are increased in human PAH-PASMC. Using bioinformatics, they identified 3 known motifs of A2B1 and all mRNAs carrying them. In PAH-PASMC, they demonstrated the complementary nonredundant function of A2B1 motifs because all motifs are implicated in different aspects of the cell cycle. In addition, they showed that in PAH-PASMC, A2B1 promotes the expression of its targets. A2B1 silencing in PAH-PASMC led to a decrease of all tested mRNAs carrying an A2B1 motif and a concomitant decrease in proliferation and resistance to apoptosis. Last, in vivo A2B1 inhibition in the lungs rescued pulmonary hypertension in rats.

CONCLUSIONS

Through the integration of computational and experimental biology, the study revealed the role of A2B1 as a master orchestrator of the PAH-PASMC phenotype and its relevance as a therapeutic target in PAH.

Intralipid fails to rescue bupivacaine-induced cardiotoxicity in late-pregnant rats

Background

Females routinely receive bupivacaine for obstetric and regional anesthesia. An accidental overdose of bupivacaine can result in cardiotoxicity and cardiac arrest. Intralipid (ILP) rescues bupivacaine-induced cardiotoxicity in male rats. However, bupivacaine cardiotoxicity and ILP rescue have not been studied in non-pregnant and late-pregnant female rats. Here, we tested the hypothesis that an appropriate dose of ILP would rescue non-pregnant and late-pregnant rats from bupivacaine-induced cardiotoxicity.

Methods

Non-pregnant (n = 6) and late-pregnant (n = 7) female rats received intravenous bupivacaine (10-mg/kg bolus) to induce asystole. Resuscitation with 20% ILP (5-ml/kg actual body weight, single bolus, and 0.5-ml/kg/min maintenance) and chest compressions were continued for 10-min. Serial heart rate (HR), left ventricular ejection-fraction (LVEF%), and LV-fractional shortening (LVFS%) were recorded at baseline and 10-min after bupivacaine-induced cardiac arrest. Data are mean ± SD followed by 95% CI. P-values < 0.05 were considered statistically significant.

Results

All rats developed cardiac arrest within a few seconds after bupivacaine. All non-pregnant rats were successfully rescued by ILP, with a HR of 280 ± 32 bpm at baseline vs. 212 ± 18 bpm at 10-min post ILP (p < 0.01), LVEF of 70 ± 6% vs. 68 ± 5% (p = ns), and LVFS of 41 ± 5% vs. 39 ± 4% (p = ns). Interestingly, 6 out of 7 late-pregnant rats did not recover with ILP. Baseline HR, LVEF and LVFS for late-pregnant rats were 330 ± 40 bpm, 66 ± 5% and 38 ± 4%, respectively. At 10-min post ILP, the HR, LVEF, and LVFS were 39 ± 102 bpm (p < 0.0001), 8 ± 22% (p < 0.0001), and 5 ± 12% (p < 0.001), respectively.

Conclusions

ILP successfully rescued bupivacaine-induced cardiac arrest in non-pregnant rats, but failed to rescue late-pregnant rats.

Abstract P3004: Small Leucine-Rich Proteoglycan Asporin Represses Smooth Muscle Cell Proliferation And Regulates Pulmonary Hypertension Development

Pulmonary arterial hypertension (PAH) is a devastating pulmonary vascular lung disease characterized by increased pressure in the pulmonary arteries leading to cardiac right ventricular (RV) hypertrophy, RV failure, and ultimately death. Current PAH therapies merely improve symptoms temporarily and patients often need lung and heart transplantation. As such, there is dire need for new insights into PAH pathophysiology to find novel therapeutic approaches. A key mechanism driving PAH is medial hyperplasia resulting from enhanced pulmonary arterial smooth muscle cell (PASMC) proliferation. Using an unbiased bioinformatics approach in an online-available microarray expression dataset of dissected pulmonary arteries (PA) from PAH patients, we discovered a novel gene, small leucine-rich proteoglycan Asporin (Aspn), which is highly and significantly upregulated in PAH compared to otherwise-healthy donor PA. Further bioinformatic analysis at a single-cell level in an online human lung dataset revealed that Aspn is most highly expressed in pulmonary SMC. We validated higher Aspn mRNA expression in human lungs and PASMC from PAH patients compared to controls, supporting our bioinformatics approach. Moreover, Aspn protein expression is elevated in PASMC in lung tissue sections from PAH patients compared to donors . Functionally, silencing Aspn in PASMC from PAH patients promoted proliferation. To find potential downstream mediators of Aspn, STRING database analysis revealed that Aspn binds to the pro-proliferative mediator TGFβ1. Accordingly, TGFβ1 downstream mediator p-SMAD2 is enhanced upon Aspn silencing in PASMC. In vivo , intratracheal delivery of Aspn siRNA in rats aggravated Sugen/Hypoxia-induced PH, as assessed by RV systolic pressure, echocardiography, and pulmonary vascular remodeling. Taken together, we hypothesize that elevated Aspn expression in PAH is a compensatory mechanism that inhibits PASMC proliferation, leading to decreased PA vascular remodeling, and that Aspn may be a novel therapeutic target against PAH.

Abstract P3001: Hnrnpa2b1 An Rna-binding Protein That Orchestrates Smooth Muscle Cell Phenotype In Pulmonary Arterial Hypertension

Background: RNA-binding proteins (RPBs) are master orchestrators of gene expression regulation. RBPs regulate hundreds of transcripts at once by recognizing specific motifs. Characterizing RBP targets is critical to harvest their full therapeutic potential. However, such investigation has often been restricted to a few RBP targets, limiting our understanding of their function. In cancer, the RBP HNRNPA2B1 (A2B1) promotes the pro-proliferative / anti-apoptotic phenotype. The same phenotype in pulmonary arterial smooth muscle cells (PASMC) is responsible for the development of pulmonary arterial hypertension (PAH). However, A2B1 function has never been investigated in PAH.

Methods: Through the integration of computational and experimental biology, we investigated the role of A2B1 in human PAH-PASMC. Bioinformatics and RNA-sequencing allowed us to investigate the transcriptome-wide function of A2B1, while RNA immunoprecipitation and A2B1 silencing experiments in vitro allowed us to decipher the intricate molecular mechanism at play. In addition, we performed a pre-clinical trial in the monocrotaline-induced pulmonary hypertension rat model to investigate the relevance of A2B1 inhibition in mitigating pulmonary hypertension severity.

Results: In the present study, we found that A2B1 is up-regulated in human PAH-PASMC. We also show that A2B1 localization shifts in PAH-PASMC from cytoplasmic to nuclear mainly due to significantly higher expression of B1 isoform compared to A2 isoform of A2B1. Using bio-informatics, we identified three known motifs of A2B1 and all mRNAs carrying them. In PAH-PASMC, we demonstrated the complementary non-redundant function of A2B1 motifs as all motifs are implicated in different aspect of the cell cycle. In addition, we showed that in PAH-PASMC, A2B1 promotes the expression of its targets. A2B1 silencing in PAH-PASMC lead to a decrease of all tested mRNAs carrying an A2B1 motif, and an according decrease in proliferation and resistance to apoptosis. Finally, in vivo A2B1 inhibition in the lungs rescued pulmonary hypertension in rats.

Conclusion: Through the integration of computational and experimental biology, our study revealed the role of A2B1 as a master orchestrator of the PAH-PASMC phenotype and its relevance as a therapeutic target in PAH.

Y-Chromosome Gene, Uty, Protects Against Pulmonary Hypertension by Reducing Proinflammatory Chemokines

Rationale: Idiopathic pulmonary arterial hypertension (PAH) is a terminal pulmonary vascular disease characterized by increased pressure, right ventricular failure, and death. PAH exhibits a striking sex bias and is up to four times more prevalent in females. Understanding the molecular basis behind sex differences could help uncover novel therapies. Objectives: We previously discovered that the Y chromosome is protective against hypoxia-induced experimental pulmonary hypertension (PH), which may contribute to sex differences in PAH. Here, we identify the gene responsible for Y-chromosome protection, investigate key downstream autosomal genes, and demonstrate a novel preclinical therapy. Methods: To test the effect of Y-chromosome genes on PH development, we knocked down each Y-chromosome gene expressed in the lung by means of intratracheal instillation of siRNA in gonadectomized male mice exposed to hypoxia and monitored changes in right ventricular and pulmonary artery hemodynamics. We compared the lung transcriptome of Uty knockdown mouse lungs to those of male and female PAH patient lungs to identify common downstream pathogenic chemokines and tested the effects of these chemokines on human pulmonary artery endothelial cells. We further inhibited the activity of these chemokines in two preclinical pulmonary hypertension models to test the therapeutic efficacy. Measurements and Main Results: Knockdown of the Y-chromosome gene Uty resulted in more severe PH measured by increased right ventricular pressure and decreased pulmonary artery acceleration time. RNA sequencing revealed an increase in proinflammatory chemokines Cxcl9 and Cxcl10 as a result of Uty knockdown. We found CXCL9 and CXCL10 significantly upregulated in human PAH lungs, with more robust upregulation in females with PAH. Treatment of human pulmonary artery endothelial cells with CXCL9 and CXCL10 triggered apoptosis. Inhibition of Cxcl9 and Cxcl10 expression in male Uty knockout mice and CXCL9 and CXCL10 activity in female rats significantly reduced PH severity. Conclusions:Uty is protective against PH. Reduction of Uty expression results in increased expression of proinflammatory chemokines Cxcl9 and Cxcl10, which trigger endothelial cell death and PH. Inhibition of CLXC9 and CXLC10 rescues PH development in multiple experimental models.

Milk feeding level and starter protein content: Effects on growth performance, blood metabolites, and urinary purine derivatives of Holstein dairy calves

The objective of this study was to investigate the effects of milk allowances equal to 526 g/d as moderate (MOD) versus 790 g/d of milk dry matter as high (HI), and starter diets containing 18% or 23% crude protein (CP), on growth performance, blood metabolites, and purine derivative (PD) excretion in the urine of dairy calves. A total of 52 female Holstein dairy calves (40.8 kg of body weight) were randomly assigned to the experimental diets. The treatments were (1) moderate milk and 18% CP starter diet (MOD-18CP); (2) MOD and 23% CP starter diet (MOD-23CP); (3) high milk and 18% CP starter diet (HI-18CP); and (4) HI and 23% CP starter diet (HI-23CP). Calves had free access to a starter feed and water and were weaned on d 53 but remained in the study until d 73. Urine samples were collected during the preweaning period (for 6 consecutive days between d 35 and 40) and postweaning period (for 6 consecutive days between d 65 and 70) to investigate urinary excretion of PD. Starter feed intake, β-hydroxybutyrate (BHB), and blood urea concentrations were reduced; however, average daily gain (ADG) and blood glucose levels increased in calves fed HI before weaning compared with MOD. During the preweaning period, high milk feeding increased total urinary PD excretion but decreased it after weaning. The 23CP diet resulted in higher feed intake and ADG before weaning and higher excretion of allantoin and total excretion of PD compared with the 18CP diet. The HI-23CP treatment resulted in the greatest withers and hip heights at weaning and final measurement, as well as the highest preweaning blood insulin concentrations. In terms of rumen development, MOD-23CP showed the greatest benefits based on starter intake, blood BHB concentration, and urinary excretion of PD. Based on the higher urinary excretion of PD found in HI-fed calves before weaning, it is possible that milk feeding overestimates estimated microbial yield. The results suggest that feeding starters with a higher proportion of CP may help maintain a more balanced ratio of CP to ME during high milk feeding, to avoid protein deficiency due to low starter intake. When calves are fed a high milk allowance, urine excretion of PD may be misinterpreted as a measure of estimated microbial growth and rumen development; this should be considered during calculations of estimated microbial yield in milk-fed calves.

Role of miRNA-1 and miRNA-21 in Acute Myocardial Ischemia-Reperfusion Injury and Their Potential as Therapeutic Strategy

Coronary artery disease remains the leading cause of death. Acute myocardial infarction (MI) is characterized by decreased blood flow to the coronary arteries, resulting in cardiomyocytes death. The most effective strategy for treating an MI is early and rapid myocardial reperfusion, but restoring blood flow to the ischemic myocardium can induce further damage, known as ischemia-reperfusion (IR) injury. Novel therapeutic strategies are critical to limit myocardial IR injury and improve patient outcomes following reperfusion intervention. miRNAs are small non-coding RNA molecules that have been implicated in attenuating IR injury pathology in pre-clinical rodent models. In this review, we discuss the role of miR-1 and miR-21 in regulating myocardial apoptosis in ischemia-reperfusion injury in the whole heart as well as in different cardiac cell types with special emphasis on cardiomyocytes, fibroblasts, and immune cells. We also examine therapeutic potential of miR-1 and miR-21 in preclinical studies. More research is necessary to understand the cell-specific molecular principles of miRNAs in cardioprotection and application to acute myocardial IR injury.

Radiosensitizing Pancreatic Cancer via Effective Autophagy Inhibition

Despite aggressive treatments, pancreatic ductal adenocarcinoma (PDAC) remains an intractable disease, largely because it is refractory to therapeutic interventions. To overcome its nutrient-poor microenvironment, PDAC heavily relies on autophagy for metabolic needs to promote tumor growth and survival. Here, we explore autophagy inhibition as a method to enhance the effects of radiotherapy on PDAC tumors. Hydroxychloroquine is an autophagy inhibitor at the focus of many PDAC clinical trials, including in combination with radiotherapy. However, its acid-labile properties likely reduce its intratumoral efficacy. Here, we demonstrate that EAD1, a synthesized analogue of HCQ, is a more effective therapeutic for sensitizing PDAC tumors of various KRAS mutations to radiotherapy. Specifically, in vitro models show that EAD1 is an effective inhibitor of autophagic flux in PDAC cells, accompanied by a potent inhibition of proliferation. When combined with radiotherapy, EAD1 is consistently superior to HCQ not only as a single agent, but also in radiosensitizing PDAC cells, and perhaps most importantly, in decreasing the self-renewal capacity of PDAC cancer stem cells (PCSC). The more pronounced sensitizing effects of autophagy inhibitors on pancreatic stem over differentiated cells points to a new understanding that PCSCs may be more dependent on autophagy to counter the effects of radiation toxicity, a potential mechanism explaining the resistance of PCSCs to radiotherapy. Finally, in vivo subcutaneous tumor models demonstrate that combination of radiotherapy and EAD1 is the most successful at controlling tumor growth. The models also confirmed a similar toxicity profile between EAD1 and Hydroxychloroquine.

Abstract P475: Microrna-129-5p Rescues Myocardial Fibrosis And Calcification By Targeting Asporin And Sox9 In Cardiac Fibroblasts

Myocardial fibrosis promotes heart failure (HF) progression by impairing myocardial compliance, but also may predispose to myocardial calcification, further impairing cardiac function. Transition of resident cardiac fibroblast (CF) to pro-fibrotic myofibroblasts (MF) and osteogenic cell fates (OF) are key events which are partially controlled by microRNAs (miRs). To discover novel miRs involved in myocardial fibrosis and calcification, we compared online-available microarray datasets of left ventricles (LV) from failing human and mouse hearts. Assessing differentially-expressed miRs known to regulate fibrosis and calcification genes revealed that miR-129-5p is significantly downregulated in HF LV. Bioinformatic target analysis revealed small leucin-rich proteoglycan Asporin (Aspn) and SRY-Box Transcription Factor 9 (Sox9) as two novel miR-129-5p targets upregulated in both mouse and human diseased LV. Thus far, nothing is known about miR-129-5p in cardiac fibrosis and calcification. Additionally, the role of Asporin in myocardial fibrosis and the roles of either Asporin or Sox9 in myocardial calcification remain undiscovered. We show that miR-129-5p is expressed in CF in mouse and human hearts and is downregulated in CF of both HF patients and Angiotensin II (AngII)-injured mice, while Asporin and Sox9 are upregulated in CF of HF LV. In vitro , AngII or transforming growth factor-β downregulated miR-129-5p expression in primary adult mouse CF. Overexpression of miR-129-5p in CF inhibited expression of MF and OF transition markers, reduced migration, collagen production and calcium deposition. We validated Asporin and Sox9 as direct targets of miR-129-5p. Accordingly, silencing of Asporin and Sox9 in CF attenuated molecular and functional characteristics of MF and OF transition. Strikingly, systemic delivery of miR-129-5p mimics in mice directly targets CF and is sufficient to rescue preexisting AngII-induced myocardial fibrosis, calcification, diastolic- and systolic dysfunction. In conclusion, miR-129-5p rescues myocardial fibrosis and calcification by attenuating MF and OF transition via inhibition of Asporin and Sox9 in CF and is a promising therapeutic target.

A novel miRNA biomarker panel associated with mortality in pediatric patients with ARDS

We identified a novel microRNA biomarker panel consisting of 6 microRNAs predicting mortality in pediatric acute respiratory distress syndrome patients. Each of the identified mRNA have potential mechanistic importance in acute respiratory distress syndrome and may lead to the development of pharmacologic targets.

Single-Cell Study of Two Rat Models of Pulmonary Arterial Hypertension Reveals Connections to Human Pathobiology and Drug Repositioning

Rationale: The cellular and molecular landscape and translational value of commonly used models of pulmonary arterial hypertension (PAH) are poorly understood. Single-cell transcriptomics can enhance molecular understanding of preclinical models and facilitate their rational use and interpretation.Objectives: To determine and prioritize dysregulated genes, pathways, and cell types in lungs of PAH rat models to assess relevance to human PAH and identify drug repositioning candidates.Methods: Single-cell RNA sequencing was performed on the lungs of monocrotaline (MCT), Sugen-hypoxia (SuHx), and control rats to identify altered genes and cell types, followed by validation using flow-sorted cells, RNA in situ hybridization, and immunofluorescence. Relevance to human PAH was assessed by histology of lungs from patients and via integration with human PAH genetic loci and known disease genes. Candidate drugs were predicted using Connectivity Map.Measurements and Main Results: Distinct changes in genes and pathways in numerous cell types were identified in SuHx and MCT lungs. Widespread upregulation of NF-κB signaling and downregulation of IFN signaling was observed across cell types. SuHx nonclassical monocytes and MCT conventional dendritic cells showed particularly strong NF-κB pathway activation. Genes altered in SuHx nonclassical monocytes were significantly enriched for PAH-associated genes and genetic variants, and candidate drugs predicted to reverse the changes were identified. An open-access online platform was developed to share single-cell data and drug candidates (http://mergeomics.research.idre.ucla.edu/PVDSingleCell/).Conclusions: Our study revealed the distinct and shared dysregulation of genes and pathways in two commonly used PAH models for the first time at single-cell resolution and demonstrated their relevance to human PAH and utility for drug repositioning.

Pulmonary hypertension secondary to pulmonary fibrosis: clinical data, histopathology and molecular insights

Pulmonary hypertension (PH) developing secondarily in pulmonary fibrosis (PF) patients (PF-PH) is a frequent co-morbidity. The high prevalence of PH in PF patients is very concerning since the presence of PH is a strong predictor of mortality in PF patients. Until recently, PH was thought to arise solely from fibrotic destruction of the lung parenchyma, leading to hypoxic vasoconstriction and loss of vascular bed density. Thus, potential cellular and molecular dysregulation of vascular remodeling as a driver of PF-PH has been under-investigated. The recent demonstrations that there is no correlation between the severity of the fibrosis and development of PH, along with the finding that significant vascular histological and molecular differences exist between patients with and without PH have shifted the etiological paradigm of PF-PH. This review aims to provide a comprehensive translational overview of PH in PF patients from clinical diagnosis and outcome to the latest understanding of the histology and molecular pathophysiology of PF-PH.

The Role of MicroRNAs in Acute Respiratory Distress Syndrome and Sepsis, From Targets to Therapies: A Narrative Review

Acute respiratory distress syndrome (ARDS) is a significant cause of morbidity and mortality in the intensive care unit (ICU) and is characterized by lung epithelial and endothelial cell injury, with increased permeability of the alveolar-capillary membrane, leading to pulmonary edema, severe hypoxia, and difficulty with ventilation. The most common cause of ARDS is sepsis, and currently, treatment of ARDS and sepsis has consisted mostly of supportive care because targeted therapies have largely been unsuccessful. The molecular mechanisms behind ARDS remain elusive. Recently, a number of microRNAs (miRNAs) identified through high-throughput screening studies in ARDS patients and preclinical animal models have suggested a role for miRNA in the pathophysiology of ARDS. miRNAs are small noncoding RNAs ranging from 18 to 24 nucleotides that regulate gene expression via inhibition of the target mRNA translation or by targeting complementary mRNA for early degradation. Unsurprisingly, some miRNAs that are differentially expressed in ARDS overlap with those important in sepsis. In addition, circulatory miRNA may be useful as biomarkers or as targets for pharmacologic therapy. This can be revolutionary in a syndrome that has neither a measurable indicator of the disease nor a targeted therapy. While there are currently no miRNA-based therapies targeted for ARDS, therapies targeting miRNA have reached phase II clinical trials for the treatment of a wide range of diseases. Further studies may yield a unique miRNA profile pattern that serves as a biomarker or as targets for miRNA-based pharmacologic therapy. In this review, we discuss miRNAs that have been found to play a role in ARDS and sepsis, the potential mechanism of how particular miRNAs may contribute to the pathophysiology of ARDS, and strategies for pharmacologically targeting miRNA as therapy.

Sex differences underlying preexisting cardiovascular disease and cardiovascular injury in COVID-19

The novel 2019 coronavirus disease (COVID-19), resulting from severe acute respiratory syndrome coronarvirus-2 (SARS-CoV-2) infection, typically leads to respiratory failure in severe cases; however, cardiovascular injury is reported to contribute to a substantial proportion of COVID-19 deaths. Preexisting cardiovascular disease (CVD) is among the most common risk factors for hospitalization and death in COVID-19 patients, and the pathogenic mechanisms of COVID-19 disease progression itself may promote the development of cardiovascular injury, increasing risk of in-hospital death. Sex differences in COVID-19 are becoming more apparent as mounting data indicate that males seem to be disproportionately at risk of severe COVID-19 outcome due to preexisting CVD and COVID-19-related cardiovascular injury. In this review, we will provide a basic science perspective on current clinical observations in this rapidly evolving field and discuss the interplay sex differences, preexisting CVD and COVID-19-related cardiac injury.

Abstract 415: Asporin Contributes to Reactive Interstitial Cardiac Fibrosis by Regulating Cardiac Fibroblast Activation

Cardiac fibrosis critically contributes to heart failure progression. Depending on the pathological insult, cardiac fibrosis either replaces necrotic cardiomyocytes or is reactive to cardiac fibroblast (CF) activation. The extracellular matrix (ECM) consists of various proteins and the role of fibrillar collagen has been well studied. However, the role of non-fibrillar ECM proteins in cardiac fibrosis is less clear. To explore the role of ECM in reactive cardiac fibrosis, we performed bioinformatic analysis on online available microarray GEO datasets from hearts of human hypertrophic cardiomyopathy patients and two mouse models of transverse aortic constriction and Angiotensin II (AngII) infusion. We found that 27 differentially expressed genes were common between the three datasets. Among these genes was the small leucine-rich proteoglycan Asporin (ASPN). ASPN was previously shown to be upregulated in the ECM of replacement fibrosis in porcine ischemia/reperfusion injury. However, not much is known about the role of ASPN in reactive interstitial fibrosis. We show that cardiac ASPN expression is enhanced in mice after short- and long-term AngII infusion compared to saline infusion. In resident CF isolated from adult mice, ASPN expression is upregulated by both AngII and TGF-β stimulation. Here, ASPN expression correlates with a gene signature of activated CFs including periostin ( postn ), α-smooth muscle actin ( acta2 ) and collagens I and III ( col1a1, col3a1 ), and with functional characteristics of activated CFs including proliferation, migration and collagen production. Modulating ASPN via siRNA in mouse resident CFs inhibits postn, acta2, col1a1 and col3a1 expression and total collagen production, indicating repressed CF activation upon ASPN knockdown. Taken together, ASPN may be an attractive novel target against reactive interstitial fibrosis.

Abstract MP172: Y-chromosome Gene, Uty, Confers Male Protection Against Pulmonary Hypertension by Mediating Pro-inflammatory Chemokine Effects

Background: Idiopathic pulmonary arterial hypertension (PAH) is a terminal vascular lung disease characterized by increased PA pressure resulting in right ventricular (RV) failure and death. For reasons largely unknown, PAH is up to 4x more prevalent in females. We published that the Y-Chromosome (Chrm) is protective against hypoxia (Hx)-induced pulmonary hypertension (PH) in mice and identified four Y-Chrm genes expressed in the lung. Here, we identify the protective Y-Chrm gene, investigate its mechanism and demonstrate a novel therapeutic approach.

Methods and Results: To test the effect of Y-Chrm candidate genes on PH development, we knocked down (KD) each Y-Chrm gene via sequential intratracheal instillation of siRNA in the lungs of male mice exposed to Hx. KD of Y-Chrm gene Uty, but none of the other genes, resulted in more severe PH measured by increased RV systolic pressure (RVSP) and decreased pulmonary arterial acceleration time (PAAT) compared to control (n=4/group; RVSP: Uty-KD= 48.93mmHg, Control= 37.33mmHg, p=0.04; PAAT: Uty-KD= 11.88ms, Control= 14.43ms, p=0.01). RNAseq analysis (Uty-KD vs Control) revealed an increase in pro-inflammatory cytokines Cxcl9 (Log2FC: 1.3, p-adjusted=0.05) and Cxcl10 (Log2FC: 0.9, p-adjusted=0.002). We found Cxcl9/10 significantly upregulated in human PAH lungs vs healthy and female PAH lungs vs male (RT-qPCR). Fluorescent in-situ hybridization revealed Uty and Cxcl9/10 expression co-localized in CD68 + macrophages within the lung. Treatment of human pulmonary artery endothelial cells (PAEC) with Cxcl9/10 resulted in significantly increased apoptosis. We inhibited Cxcl9/10 activity in female rats 14 days post monocrotaline (MCT) injection by treating them with a small molecular inhibitor. Treated rats (n=6) had less severe PH than vehicle-treated controls (n=5) when measured 28-days post MCT (RVSP: Treated= 36.75mmHg, Vehicle=43.62 mmHg, p=0.03; PAAT: Treated= 26.7ms, Vehicle=20 ms, p=0.01; RV hypertrophy index (RV/(LV+IVS)): Treated= 0.48, Vehicle= 0.35, p=0.01).

Conclusion: Y-Chrm gene, Uty, is protective against PH. Uty inhibition increases pro-inflammatory cytokines Cxcl9/10 which contribute to PAEC death. Inhibition of Cxcl9/10 activity may provide a novel therapy for the treatment of PH.

Abstract MP155: Oxidized Lipids Diet Causes Pulmonary Hypertension Through T-cell Dependent Endothelial Cell Apoptosis

Background: Pulmonary hypertension (PH) is a fatal disease characterized by an increased mean pulmonary arterial pressure above 25mmHg. This increased pressure is, at least in part, due to thickening of the distal pulmonary arteries. Recently, numerous studies demonstrated an increased plasma concentration of oxidized lipids in PH and in diseases where secondary PH developed. Furthermore, 15-hydroxyeicosatetraenoic acid (15-HETE) an oxidized lipid and a major metabolite of arachidonic acid in the lung, has been implicated in dysregulation of major biological pathways in PH. However, the mechanisms involved in the causal role of 15-HETE in pulmonary hypertension development are not known.

Methods and Results: To study the role of 15-HETE in PH development, we fed C57BL6/J mice a diet supplemented with 15-HETE for 3 weeks with no other insults. After 3 weeks on the diet with added 15-HETE, C57BL6/J mice had increased concentrations of not only 15-HETE but also of other oxidized lipids (5-, 11- and 12-HETE) in plasma and lung, and they developed PH. RNA-seq analysis revealed the activation of pathways involved in antigen processing and presentation, and with evidence of T cell mediated cytotoxicity in lungs of mice fed 15-HETE. Transcriptomic profiling of lung tissues obtained from patients with pulmonary arterial hypertension (PAH) demonstrated activation of pathways similar to those seen mice. In mice fed a 15-HETE diet, there was an increase in the number of CD8/CD69 double positive cells, as well as an increase in pulmonary arterial endothelial cell (PAEC) apoptosis. Furthermore, PAEC exposed to 15-HETE were more prone to apoptosis when exposed to CD8 cells. Adding Tg6F, an apoA-I mimetic peptide to the 15-HETE diet prevented and rescued PH in C57BL6/J mice, in part, by inhibiting PAEC apoptosis.

Conclusions: 15-HETE diet induced PH in C57Bl6/J mice by triggering PAEC death in a T-cell dependent mechanism. The apoA-I mimetic peptide Tg6F was able to prevent and rescue PH induced by 15-HETE.

Oral 15-Hydroxyeicosatetraenoic Acid Induces Pulmonary Hypertension in Mice by Triggering T Cell-Dependent Endothelial Cell Apoptosis

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by increased mean pulmonary arterial pressure. Elevated plasma and lung concentrations of oxidized lipids, including 15-hydroxyeicosatetraenoic acid (15-HETE), have been demonstrated in patients with PAH and animal models. We previously demonstrated that feeding mice with 15-HETE is sufficient to induce pulmonary hypertension, but the mechanisms remain unknown. RNA sequencing data from the mouse lungs on 15-HETE diet revealed significant activation of pathways involved in both antigen processing and presentation and T cell-mediated cytotoxicity. Analysis of human microarray from patients with PAH also identified activation of identical pathways compared with controls. We show that in both 15-HETE-fed mice and patients with PAH, expression of the immunoproteasome subunit 5 is significantly increased, which was concomitant with an increase in the number of CD8/CD69 (cluster of differentiation 8 / cluster of differentiation 69) double-positive cells, as well as pulmonary arterial endothelial cell apoptosis in mice. Human pulmonary arterial endothelial cells cultured with 15-HETE were more prone to apoptosis when exposed to CD8 cells. Cultured intestinal epithelial cells secreted more oxidized lipids in response to 15-HETE, which is consistent with accumulation of circulating oxidized lipids in 15-HETE-fed mice. Administration of an apoA-I (apolipoprotein A-I) mimetic peptide, Tg6F (transgenic 6F), which is known to prevent accumulation of circulating oxidized lipids, not only inhibited pulmonary arterial endothelial cell apoptosis but also prevented and rescued 15-HETE-induced pulmonary hypertension in mice. In conclusion, our results suggest that (1) 15-HETE diet induces pulmonary hypertension by a mechanism that involves oxidized lipid-mediated T cell-dependent pulmonary arterial endothelial cell apoptosis and (2) Tg6F administration may be a novel therapy for treating PAH.

The Role of Estrogen Receptors in Cardiovascular Disease

Cardiovascular Diseases (CVDs) are the leading cause of death globally. More than 17 million people die worldwide from CVD per year. There is considerable evidence suggesting that estrogen modulates cardiovascular physiology and function in both health and disease, and that it could potentially serve as a cardioprotective agent. The effects of estrogen on cardiovascular function are mediated by nuclear and membrane estrogen receptors (ERs), including estrogen receptor alpha (ERα), estrogen receptor beta (ERβ), and G-protein-coupled ER (GPR30 or GPER). Receptor binding in turn confers pleiotropic effects through both genomic and non-genomic signaling to maintain cardiovascular homeostasis. Each ER has been implicated in multiple pre-clinical cardiovascular disease models. This review will discuss current reports on the underlying molecular mechanisms of the ERs in regulating vascular pathology, with a special emphasis on hypertension, pulmonary hypertension, and atherosclerosis, as well as in regulating cardiac pathology, with a particular emphasis on ischemia/reperfusion injury, heart failure with reduced ejection fraction, and heart failure with preserved ejection fraction.

Pregnancy-associated cardiac dysfunction and the regulatory role of microRNAs

Many crucial cardiovascular adaptations occur in the body during pregnancy to ensure successful gestation. Maladaptation of the cardiovascular system during pregnancy can lead to complications that promote cardiac dysfunction and may lead to heart failure (HF). About 12% of pregnancy-related deaths in the USA have been attributed to HF and the detrimental effects of cardiovascular complications on the heart can be long-lasting, pre-disposing the mother to HF later in life. Indeed, cardiovascular complications such as gestational diabetes mellitus, preeclampsia, gestational hypertension, and peripartum cardiomyopathy have been shown to induce cardiac metabolic dysfunction, oxidative stress, fibrosis, apoptosis, and diastolic and systolic dysfunction in the hearts of pregnant women, all of which are hallmarks of HF. The exact etiology and cardiac pathophysiology of pregnancy-related complications is not yet fully deciphered. Furthermore, diagnosis of cardiac dysfunction in pregnancy is often made only after clinical symptoms are already present, thus necessitating the need for novel diagnostic and prognostic biomarkers. Mounting data demonstrates an altered expression of maternal circulating miRNAs during pregnancy affected by cardiovascular complications. Throughout the past decade, miRNAs have become of growing interest as modulators and biomarkers of pathophysiology, diagnosis, and prognosis in cardiac dysfunction. While the association between pregnancy-related cardiovascular complications and cardiac dysfunction or HF is becoming increasingly evident, the roles of miRNA-mediated regulation herein remain poorly understood. Therefore, this review will summarize current reports on pregnancy-related cardiovascular complications that may lead to cardiac dysfunction and HF during and after pregnancy in previously healthy women, with a focus on the pathophysiological role of miRNAs.

Involvement of Low-Density Lipoprotein Receptor in the Pathogenesis of Pulmonary Hypertension

Background

Recently, we and others have reported a causal role for oxidized lipids in the pathogenesis of pulmonary hypertension (PH). However, the role of low‐density lipoprotein receptor (LDL‐R) in PH is not known.

Methods and Results

We examined the role of LDL‐R in the development of PH and determined the efficacy of high‐density lipoprotein mimetic peptide 4F in mitigating PH. Explanted human lungs and plasma from patients with PH and control subjects were analyzed for gene expression, histological characteristics, and lipoprotein oxidation. Male LDL‐R null (LDL‐R knockout) mice (12–15 months old) were fed chow, Western diet (WD), WD with 4F, and WD with scramble peptide for 12 weeks. Serial echocardiography, cardiac catheterization, oxidized LDL assay, real‐time quantitative reverse transcription–polymerase chain reaction, and histological analysis were performed. The effect of LDL‐R knockdown and oxidized LDL on human pulmonary artery smooth muscle cell proliferation was assessed in vitro. LDL‐R and CD36 expression levels were significantly downregulated in the lungs of patients with PH. Patients with PH also had increased lung lipid deposits, oxidized LDL, E06 immunoreactivity, and plasma oxidized LDL/LDL ratio. LDL‐R knockout mice on WD developed PH, right ventricular hypertrophy, right ventricular dysfunction, pulmonary vascular remodeling, fibrosis, and lipid deposition in lungs, aortic atherosclerosis, and left ventricular dysfunction, which were prevented by 4F. Interestingly, PH in WD group preceded left ventricular dysfunction. Oxidized LDL or LDL‐R knockdown significantly increased proliferation of human pulmonary artery smooth muscle cells in vitro.

Conclusions

Human PH is associated with decreased LDL‐R in lungs and increased oxidized LDL in lungs and plasma. WD‐fed LDL‐R knockout mice develop PH and right ventricular dysfunction, implicating a role for LDL‐R and oxidized lipids in PH.

Oxidative Stress and Its Implications in the Right Ventricular Remodeling Secondary to Pulmonary Hypertension

Pulmonary hypertension (PH) is a pulmonary vascular disease characterized by increased pulmonary artery pressures. Long standing pulmonary arterial pressure overload leads to right ventricular (RV) hypertrophy, RV failure, and death. RV failure is a major determinant of survival in PH. Oxidative stress has been associated with the development of RV failure secondary to PH. Here we summarize the structural and functional changes in the RV in response to sustained pulmonary arterial pressure overload. Furthermore, we review the pre-clinical and clinical studies highlighting the association of oxidative stress with pulmonary vasculature and RV remodeling in chronic PH. Targeting oxidative stress promises to be an effective therapeutic strategy for the treatment of RV failure.

Histological hallmarks and role of Slug/PIP axis in pulmonary hypertension secondary to pulmonary fibrosis

Pulmonary hypertension secondary to pulmonary fibrosis (PF-PH) is one of the most common causes of PH, and there is no approved therapy. The molecular signature of PF-PH and underlying mechanism of why pulmonary hypertension (PH) develops in PF patients remains understudied and poorly understood. We observed significantly increased vascular wall thickness in both fibrotic and non-fibrotic areas of PF-PH patient lungs compared to PF patients. The increased vascular wall thickness in PF-PH patients is concomitant with a significantly increased expression of the transcription factor Slug within the macrophages and its target prolactin-induced protein (PIP), an extracellular matrix protein that induces pulmonary arterial smooth muscle cell proliferation. We developed a novel translational rat model of combined PF-PH that is reproducible and shares similar histological features (fibrosis, pulmonary vascular remodeling) and molecular features (Slug and PIP upregulation) with human PF-PH. We found Slug inhibition decreases PH severity in our animal model of PF-PH. Our study highlights the role of Slug/PIP axis in PF-PH.

Radiation mitigation of the intestinal acute radiation injury in mice by 1-[(4-nitrophenyl)sulfonyl]-4-phenylpiperazine

The objective of the study was to identify the mechanism of action for a radiation mitigator of the gastrointestinal (GI) acute radiation syndrome (ARS), identified in an unbiased high‐throughput screen. We used mice irradiated with a lethal dose of radiation and treated with daily injections of the radiation mitigator 1‐[(4‐nitrophenyl)sulfonyl]‐4‐phenylpiperazine to study its effects on key pathways involved in intestinal stem cell (ISC) maintenance. RNASeq, quantitative reverse transcriptase‐polymerase chain reaction, and immunohistochemistry were performed to identify pathways engaged after drug treatment. Target validation was performed with competition assays, reporter cells, and in silico docking. 1‐[(4‐Nitrophenyl)sulfonyl]‐4‐phenylpiperazine activates Hedgehog signaling by binding to the transmembrane domain of Smoothened, thereby expanding the ISC pool, increasing the number of regenerating crypts and preventing the GI‐ARS. We conclude that Smoothened is a target for radiation mitigation in the small intestine that could be explored for use in radiation accidents as well as to mitigate normal tissue toxicity during and after radiotherapy of the abdomen.

Connecting sex differences, estrogen signaling, and microRNAs in cardiac fibrosis

Sex differences are evident in the pathophysiology of heart failure (HF). Progression of HF is promoted by cardiac fibrosis and no fibrosis-specific therapies are currently available. The fibrotic response is mediated by cardiac fibroblasts (CFs), and a central event is their phenotypic transition to pro-fibrotic myofibroblasts. These myofibroblasts may arise from various cellular origins including resident CFs and epicardial and endothelial cells. Both female subjects in clinical studies and female animals in experimental studies generally present less cardiac fibrosis compared with males. This difference is at least partially considered attributable to the ovarian hormone 17β-estradiol (E2). E2 signals via estrogen receptors to regulate genes are involved in the fibrotic response and myofibroblast transition. Besides protein-coding genes, E2 also regulates transcription of microRNA that modulate cardiac fibrosis. Sex dimorphism, E2, and miRNAs form multi-level regulatory networks in the pathophysiology of cardiac fibrosis, and the mechanism of these networks is not yet fully deciphered. Therefore, this review is aimed at summarizing current knowledge on sex differences, E2, and estrogen receptors in cardiac fibrosis, emphasizing on microRNAs and myofibroblast origins. KEY MESSAGES: • E2 and ERs regulate cardiac fibroblast function. • E2 and ERs may distinctly affect male and female cardiac fibrosis pathophysiology. • Sex, E2, and miRNAs form multi-level regulatory networks in cardiac fibrosis. • Sex-dimorphic and E2-regulated miRNAs affect mesenchymal transition.

Abstract 226: Apoai Mimetic Peptide 6f Prevent Pulmonary Hypertension Induced by Oxidized Lipids

Introduction: Pulmonary arterial hypertension (PAH) is characterized by pulmonary arterial occlusion leading to increased pulmonary arterial pressure. Recently, a growing body of evidence demonstrated a robust increase in oxidized lipids, including 15-hydroxyeicosatetraenoic acids (15HETE), in the lungs and plasma of PAH patients and animal models of pulmonary hypertension (PH). Nonetheless, the the causal role of 15HETE in promoting PH development remains elusive. In order to investigate this mechanism, we fed wild type mice with a diet rich in 15HETE and examine whether ApoA-I mimetic peptide can rescue PH induced by 15HETE.

Methods: Wild type male mice (C57BL/6) were fed for 3 weeks with regular chow (n=16-21 mice/group), 15HETE (5μg/day), 15HETE diet supplemented with either empty vector or 6F for the last week of 15HETE diet. PH development was assessed every week via serial echocardiography. Right ventricular systolic pressure (RVSP) was measured via heart catheterization. RV hypertrophy index (RV/[IVS+LV]) was measured. Lung morphology and lipid accumulation were assessed using H&E and Oil red O staining.

Results: Echocardiography revealed the first sign of PH as early as one week after starting 15HETE diet and a significant decrease in the pulmonary arterial acceleration time (PAAT) after 2 weeks of treatment (16.6±1.9 vs. 20.6±1.4 msec, p<0.05). At the end of three weeks, mice on 15HETE diet had significantly higher RVSP (31.3±1.1 vs. 38.4±2.3 mmHg, p<0.05) and RV hypertrophy index (0.26 ± 0.02 vs. 0.33 ±0.02, p<0.05). This increased pressure was concomitant with a significant increase in pulmonary arteriolar thickness in mice on 15-HETE diet compared to regular diet (35.1±0.8 vs 53.4±1, p<0.05). At the end of three weeks mice treated with 6F showed a PAAT similar to control value(19±0.5 msec) concomitant with a significantly lower RVSP than mice fed with 15HETE+empty vector (33.6 ±5.7 vs 40.3±4.6, p<0.05).

Conclusion: Our data demonstrates that APOA-I mimetic peptide 6F is able to rescue pre-exisiting PH induced by 15-HETE diet in wild type mice.

Abstract 494: Role of Slug / PIP Axis in Pulmonary Hypertension Secondary to Pulmonary Fibrosis

Pulmonary hypertension (PH) secondary to pulmonary fibrosis (PF-PH) is the second most common cause of PH. While never studied in detail, pathology reports suggest that vascular remodeling (VR) differs between PF and PF-PH. In PF, VR is mainly limited to fibrotic areas, whereas in PF-PH, it also exist in non-fibrotic areas. These histological differences suggest potential molecular differences. To better understand this mechanism, we investigated the expression of the transcription factor Slug which is known to play a role in PH and PF.

Using explanted rat (n=7/group) and human (n=7-14/group) lungs, we compared lung fibrosis, VR and Slug expression between non-fibrotic and fibrotic areas in PF and PF-PH. Online microarray data (GSE24988) were used to find the targets of Slug that are implicated in VR. A new animal model recapitulating our findings in patients was used to test the therapeutic potential of Slug inhibition (n=10/group). This model is based on intra-tracheal instillation of bleomycin (2.5mg/Kg) at day 0 and 2weeks later, an injection of monocrotaline (60mg/kg). PH was assessed by right ventricular systolic pressure (RVSP). P<0.05 are considered significant.

In both PF and PF-PH patients, fibrotic areas (PF29±4; PF-PH37±3) exhibit significantly increased VR when compared to non-fibrotic areas of the lung (PF 22±1; PF-PH 31±6). PF-PH patients have increased pulmonary vascular thickening in both areas vs PF patients. This is concomitant with an increased number of Ki67+ vascular cells in PF-PH (12±2%) vs PF (8±1%) as well as an upregulation of Slug in PF-PH patients (2.3±0.5) vs PF (1±0.1). Co-immunolabeling with CD68 demonstrate that macrophages are the main cell type responsible for Slug up-regulation in PF-PH. Human microarray data reveal an up-regulation of the Prolactin-induced protein (PIP) in PF-PH vs PF (9±3 vs 1±0.4). PIP is an extracellular transcriptional target of Slug, known to promote cell proliferation. In-vitro, PIP significantly increases pulmonary arterial smooth muscle cell proliferation in a dose dependent manner. Finally, Slug inhibition decreases RVSP (47±3 vs 62±3mmHg) in an animal model of PF-PH.

There are histological differences between PF-PH and PF lungs that are at least in part mediated by a Slug/PIP axis leading to VR.

Abstract 225: Evaluating Pro-Inflammatory and Pro-Resolving Lipid Modulations in an Oral 15-HETE Model of Pulmonary Hypertension

Pulmonary arterial hypertension (PH) is a chronic lung disease with a mortality rate of 50% at 5 years after diagnosis. PH is characterized by progressive increase in pulmonary arterial pressure leading to right ventricular (RV) increase in afterload, hypertrophy, and failure. Despite the availability of multiple animal models of PH, finding relief or cure for PH patients has been elusive to date. Recent studies in our laboratory have shown that levels of hydroxyeicosatetraenoic acids (HETEs) and hydroxyoctadecadienoic acids (HODEs) are elevated in the lungs and plasma of patients with PH as well as in animal models of PH. In testing for causality, we showed that administration of 5 μg of 15-HETE/day to wild type male mice for 3 weeks was sufficient to cause increase in pulmonary pressure, vascular resistance, plasma levels of HETEs and HODEs, right ventricle hypertrophy, and right ventricle systolic pressure (RVSP), consistent with PH. We set out to utilize this new mouse model of PH to understand the mechanisms in PH pathology by first examining the role of lipid mediators of inflammation in the development of PH. Our lab has developed a mass spectrometry method for measuring the levels of 39 inflammatory pathway lipid mediators from the cyclooxygenase (COX) and lipoxygenase (LOX) pathways that has been validated for use in tissue, plasma, and cell supernatant. Utilizing this panel with samples from mice fed 15-HETE and supernatant from an intestinal epithelial cell line; IEC-6 cells treated with 15-HETE, we have observed significant changes in multiple lipid mediators of inflammation. In addition to seeing increases in HETEs and HODEs with 15-HETE treatment, we observed significant increases in leukotriene C4 (LTC4) and 14(S)-hydroxy docosahexaenoic acid (14S-HDHA) and trending increases in thromboxane B2 (TXB2), and leukotriene E4 (LTE4) in the plasma, significant increases in 20 different lipids in lung tissue, including LTC4, TXB2, and LTE4, and significant increases in LTC4 and 5-oxo-eicosatetraenoic acid (5-oxoETE) in the supernatant of IEC-6 cells incubated with 15-HETE for 12 hours. These results indicate that novel inflammatory lipids and pathways may play an important in the development of hypertension and help identify new targets for therapies.

Progression of myocardial ischemia leads to unique changes in immediate-early gene expression in the spinal cord dorsal horn

The pathological consequences of ischemic heart disease involve signaling through the autonomic nervous system. Although early activation may serve to maintain hemodynamic stability, persistent aberrant sympathoexcitation contributes to the development of lethal arrhythmias and heart failure. We hypothesized that as the myocardium reacts and remodels to ischemic injury over time, there is an analogous sequence of gene expression changes in the thoracic spinal cord dorsal horn, the processing center for incoming afferent fibers from the heart to the central nervous system. Acute and chronic myocardial ischemia (MI) was induced in a large animal model of Yorkshire pigs, and the thoracic dorsal horn of treated pigs, along with control nonischemic pigs, was harvested for transcriptome analysis. We identified 32 differentially expressed genes between healthy and acute ischemia cohorts and 46 differentially expressed genes between healthy and chronic ischemia cohorts. The canonical immediate-early gene c-fos was upregulated after acute MI, along with fosB, dual specificity phosphatase 1 and 2 ( dusp1 and dusp2), and early growth response 2 (egr2). After chronic MI, there was a persistent yet unique activation of immediate-early genes, including fosB, nuclear receptor subfamily 4 group A members 1-3 ( nr4a1, nr4a2, and nr4a3), egr3, and TNF-α-induced protein 3 ( tnfaip3). In addition, differentially expressed genes from the chronic MI signature were enriched in pathways linked to apoptosis, immune regulation, and the stress response. These findings support a dynamic progression of gene expression changes in the dorsal horn with maturation of myocardial injury, and they may explain how early adaptive autonomic nervous system responses can maintain hemodynamic stability, whereas prolonged maladaptive signals can predispose patients to arrhythmias and heart failure. NEW & NOTEWORTHY Activation of the autonomic nervous system after myocardial injury can provide early cardiovascular support or prolonged aberrant sympathoexcitation. The later response can lead to lethal arrhythmias and heart failure. This study provides evidence of ongoing changes in the gene expression signature of the spinal cord dorsal horn as myocardial injury progresses over time. These changes could help explain how an adaptive nervous system response can become maladaptive over time.

Estrogen rescues heart failure through estrogen receptor Beta activation

Background

Recently, we showed that exogenous treatment with estrogen (E2) rescues pre-existing advanced heart failure (HF) in mice. Since most of the biological actions of E2 are mediated through the classical estrogen receptors alpha (ERα) and/or beta (ERβ), and both these receptors are present in the heart, we examined the role of ERα and ERβ in the rescue action of E2 against HF.

Methods

Severe HF was induced in male mice by transverse aortic constriction-induced pressure overload. Once the ejection fraction (EF) reached ~ 35%, mice were treated with selective agonists for ERα (PPT, 850 μg/kg/day), ERβ (DPN, 850 μg/kg/day), or E2 (30 μg/kg/day) together with an ERβ-antagonist (PHTPP, 850 μg/kg/day) for 10 days.

Results

EF of HF mice was significantly improved to 45.3 ± 2.1% with diarylpropionitrile (DPN) treatment, but not with PPT (31.1 ± 2.3%). E2 failed to rescue HF in the presence of PHTPP, as there was no significant improvement in the EF at the end of the 10-day treatment (32.5 ± 5.2%). The improvement of heart function in HF mice treated with ERβ agonist DPN was also associated with reduced cardiac fibrosis and increased cardiac angiogenesis, while the ERα agonist PPT had no significant effect on either cardiac fibrosis or angiogenesis. Furthermore, DPN improved hemodynamic parameters in HF mice, whereas PPT had no significant effect.

Conclusions

E2 treatment rescues pre-existing severe HF mainly through ERβ. Rescue of HF by ERβ activation is also associated with stimulation of cardiac angiogenesis, suppression of fibrosis, and restoration of hemodynamic parameters.

The heart of an acrobatic bird

The courtship behavior of some species of birds can be energetically demanding, but it is unknown if cardiovascular specializations enable such behaviors. While performing a highly acrobatic courtship dance, heart rate in male golden-collared manakins increases briefly to 1300 beats per minute, among the highest heart rates recorded in any bird or mammal. We hypothesize that male manakins have enhanced cardiovascular capabilities to meet these demands on the heart. Using histological and molecular techniques, we examined manakin heart structure as well as expression of genes involved in Ca²⁺ handling, action potential duration, steroidal signaling and cardiac growth. These measures were also made on the hearts of zebra finches, a similar-sized bird with limited cardiovascular demands. Compared to the zebra finch, the manakin had a significantly thicker left ventricular (LV) muscle (cross-sectional thickness of the free LV wall and septum) with a smaller LV chamber. In addition, compared to zebra finches, manakin hearts had significantly greater gene expression of ryanodine receptors as well as androgen receptors. Testosterone (T) treatment of non-breeding manakins (with low T) increased gene expression of the Ca²⁺ pump SERCA. These observations suggest that hearts of breeding male manakins require specialized Ca²⁺ handling and androgens may facilitate manakin cardiovascular function.

Abstract 250: Pulmonary Hypertension Induced by 15-HETE is Reverse by Apoai Mimetic Peptide 6f Administration

Pulmonary arterial hypertension (PAH) is characterized by pulmonary arterial occlusion leading to increased pulmonary arterial pressure. Recently, a growing body of evidence demonstrated a robust increase in oxidized lipids, including 15-hydroxyeicosatetraenoic acids (15HETE), in the lungs and plasma of PAH patients and animal models of pulmonary hypertension (PH). Recently, our group demonstrated that 15HETE induce PH. Nonetheless, the precise mechanism by which 15HETE participates in PH development remains elusive. In order to investigate this mechanism, we fed wild type mice with a diet rich in 15HETE and examine whether ApoA-I mimetic peptide can rescue PH induced by 15HETE.

Methods: Wild type male mice (C57BL/6) were fed for 3 weeks for 3 weeks with regular chow (n=16-21 mice/group), 15HETE (5μg/day), 15HETE diet supplemented with either empty vector or 6F for the last week of 15HETE diet. PH development was assessed every week via serial echocardiography. Right ventricular systolic pressure (RVSP) was measured via heart catheterization. RV hypertrophy index (RV/[IVS+LV]) was measured. Lung morphology and lipid accumulation were assessed using H&E and Oil red O staining.

Results: Echocardiography revealed the first sign of PH as early as one week after starting 15HETE diet and a significant decrease in the pulmonary arterial acceleration time (PAAT) after 2 weeks of treatment (16.6±1.9 vs. 20.6±1.4 msec, p<0.05). At the end of three weeks, mice on 15HETE diet had significantly higher RVSP (31.3±1.1 vs. 38.4±2.3 mmHg, p<0.05) and RV hypertrophy index (0.26 ± 0.02 vs. 0.33 ±0.02, p<0.05). This increased pressure was concomitant with a significant increase in pulmonary arteriolar thickness in mice on 15-HETE diet compared to regular diet (35.1±0.8 vs 53.4±1, p<0.05). Furthermore, these WT mice did not develop atherosclerosis as there was no detectable plaque in aorta of the mice on 15HETE diet. At the end of three weeks mice treated with 6F showed a PAAT similar to control value(19±0.5 msec) concomitant with a significantly lower RVSP than mice fed with 15HETE +empty vector (33.6 ±5.7 vs 40.3±4.6, p<0.05).

Conclusion: Our data demonstrates that APOA-I mimetic peptide 6F is able to rescue pre-exisiting PH induced by 15-HETE diet in wild type mice.

An Introduction to Epigenetics in Cardiovascular Development, Disease, and Sexualization

Epigenetic regulation of gene expression is integral to cell differentiation, development, and disease. Modes of epigenetic regulation-including DNA methylation, histone modifications, and ncRNA-based regulation-alter chromatin structure, promotor accessibility, and contribute to posttranscriptional modifications. In the cardiovascular system, epigenetic regulation is necessary for proper cardiovascular development and homeostasis, while epigenetic dysfunction is associated with improper cardiac development and disease.Early sexualization of tissues, including X-inactivation in females and maternal and paternal imprinting, is also orchestrated through epigenetic mechanisms. Furthermore, sex chromosomes encode various sex-specific genes involved in epigenetic regulation, while sex hormones can act as regulatory cofactors that may predispose or protect males and females against developing diseases with a marked sex bias.The following book chapter summarizes the field of epigenetics in the context of cardiovascular development and disease while also highlighting the role of epigenetic regulation as a powerful source of sex differences within the cardiovascular system.

Autonomic nervous system involvement in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic pulmonary vascular disease characterized by increased pulmonary vascular resistance (PVR) leading to right ventricular (RV) failure. Autonomic nervous system involvement in the pathogenesis of PAH has been demonstrated several years ago, however the extent of this involvement is not fully understood. PAH is associated with increased sympathetic nervous system (SNS) activation, decreased heart rate variability, and presence of cardiac arrhythmias. There is also evidence for increased renin-angiotensin-aldosterone system (RAAS) activation in PAH patients associated with clinical worsening. Reduction of neurohormonal activation could be an effective therapeutic strategy for PAH. Although therapies targeting adrenergic receptors or RAAS signaling pathways have been shown to reverse cardiac remodeling and improve outcomes in experimental pulmonary hypertension (PH)-models, the effectiveness and safety of such treatments in clinical settings have been uncertain. Recently, novel direct methods such as cervical ganglion block, pulmonary artery denervation (PADN), and renal denervation have been employed to attenuate SNS activation in PAH. In this review, we intend to summarize the multiple aspects of autonomic nervous system involvement in PAH and overview the different pharmacological and invasive strategies used to target autonomic nervous system for the treatment of PAH.

The protective role of estrogen and estrogen receptors in cardiovascular disease and the controversial use of estrogen therapy

Epidemiologic studies have previously suggested that premenopausal females have reduced incidence of cardiovascular disease (CVD) when compared to age-matched males, and the incidence and severity of CVD increases postmenopause. The lower incidence of cardiovascular disease in women during reproductive age is attributed at least in part to estrogen (E2). E2 binds to the traditional E2 receptors (ERs), estrogen receptor alpha (ERα), and estrogen receptor beta (ERβ), as well as the more recently identified G-protein-coupled ER (GPR30), and can exert both genomic and non-genomic actions. This review summarizes the protective role of E2 and its receptors in the cardiovascular system and discusses its underlying mechanisms with an emphasis on oxidative stress, fibrosis, angiogenesis, and vascular function. This review also presents the sexual dimorphic role of ERs in modulating E2 action in cardiovascular disease. The controversies surrounding the clinical use of exogenous E2 as a therapeutic agent for cardiovascular disease in women due to the possible risks of thrombotic events, cancers, and arrhythmia are also discussed. Endogenous local E2 biosynthesis from the conversion of testosterone to E2 via aromatase enzyme offers a novel therapeutic paradigm. Targeting specific ERs in the cardiovascular system may result in novel and possibly safer therapeutic options for cardiovascular protection.

Abstract 321: Protein Tyrosine Phosphatase 1B: a Novel Regulator of Proliferation and Apoptosis in the Development of Pulmonary Arterial Hypertension

Background: Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling that leads to an increase in pulmonary arterial pressure resulting in right ventricle failure and death. PAH is driven by pulmonary artery smooth muscle cell (PASMC) proliferation and resistance to apoptosis. Protein Tyrosine Phosphatase 1B (PTP1B), a negative regulator for platelet-derived growth factor (PDGF) and BCL-2, has recently been implicated in PAH in humans. While PDGF and BCL-2 are increased in PAH patients, the pathway for regulating BCL-2 and PDGF is poorly understood. We aim to investigate if PTP1B has a role in proliferation and resistance to apoptosis in PAH in human PACMCs and in the Sugen/Hypoxia/Normoxia (Su/Hx/Nx) PH rat model.

Method: Adult male Sprague-Dawley rats were treated with single intraperitoneal dose of SU5416 (20 mg/kg) and kept in Hx for 3 weeks followed by Nx for 2 weeks. Saline treated rats kept in Nx for 5 weeks served as control (n=4/group). RV catheterization was performed terminally for recording RV systolic pressure (RVSP). RV, LV, and interventricular septum (IVS) were isolated for Fulton index (FI, RV/IVS+LV). We analyzed gene expression in lungs via qPCR. Healthy hPASMCs were incubated with a PTP1B inhibitor (Ethyl-3,4-dephostatin) at IC50=0.58ug/ml for 24hrs under Nx conditions and cells were stained with Ki67 to assess proliferation.

Results: Su/Hx/Nx rats had severe PH evidenced by a significantly elevated RVSP compared to control (88.97+/- 13.67 vs 28.47+/- 2.22 mmHg, p<0.05). PH rats also showed severely reduced RV function and increased RV hypertrophy (FI= 0.7+/- 0.063 vs 0.274 +/-0.01, p<0.05). PH lungs exhibited severe pulmonary vascular remodeling with excessive growth of the PASMCs. PTP1B was significantly decreased in PH lungs compared to controls (0.158+/-0.0647 vs 1+/-0.06, P<0.05). BCL-2 expression was significantly increased in PAH compared to control (2.01+/-0.162 vs 1 +/-0.1, P<0.01). Inhibition of PTP1B in cultured hPASMCs increased proliferation by ~2 fold as assessed by Ki67 positive cells (n=3).

Conclusion: Severe angioproliferative PH in rats is associated with a downregulation of PTP1B and increased expression of BCL-2 and PASMC proliferation.