Durability of COVID-19 humoral immunity post infection and different SARS-COV-2 vaccines

BACKGROUND

The global challenge posed by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has been a major concern for the healthcare sector in recent years. Healthcare workers have a relatively high risk of encountering COVID-19 patients, making protective immunity against SARS-CoV-2 is a priority for them. This study aims to evaluate the longitudinal measurement of SARS-CoV-2 IgG spike protein antibodies in healthcare workers (HCWs) after COVID-19 infection and after receiving the first and second doses of SARS-CoV-2 vaccines, including Pfizer-BioNTech (BNT162b2) and Oxford-AstraZeneca (AZD1222).

METHODS

This longitudinal cohort study involved 311 healthcare workers working in two tertiary hospitals in Saudi Arabia. All participants were followed between July 2020 and July 2022 after completing the study questionnaire. A total of 3 ml of the blood samples were collected at four intervals: before/after vaccination.

RESULTS

HCWs post-infection had lower mean SARS-CoV-2 IgG levels three months post-infection than post-vaccination. 92.2% had positive IgG levels two weeks after the first dose and reached 100% after the second dose. Over 98% had positive antibodies nine months after the second dose, regardless of vaccine type. The number of neutralizing antibodies decreased and was around 50% at nine months after the second dose.

CONCLUSION

The results show different antibody patterns between infected and vaccinated HCWs. A high proportion of participants had positive antibodies after vaccination, with high levels persisting nine months after the second dose. Neutralizing antibodies decreased over time, with only about 50% of participants having positive antibodies nine months after the second dose. These results contribute to our understanding of immunity in healthcare workers and highlight the need for the continuous monitoring and possible booster strategies.

Novel Presentation of Major Histocompatibility Complex Class II Deficiency with Hemophagocytic Lymphohistiocytosis

PURPOSE

Major histocompatibility complex (MHC) class II deficiency is one of the combined immune deficiency disorders caused by defects in the MHC class II regulatory genes leading to abnormal T cells development and function. Therefore, patients mainly present with increased susceptibility to infections, diarrhea, and failure to thrive. In this report, we present one MHC class II deficient patient with a novel presentation with Hemophagocytic Lymphohistiocytosis (HLH).

METHODS

Immunophenotyping of lymphocyte subpopulations and HLA-DR expression was assess by flow cytometry. Gene mutational analysis was performed by whole exome and Sanger sequencing.

RESULTS

We reported a 7-year-old girl, who was diagnosed at age of 2 years with MHC class II deficiency by genetic testing and flow cytometry. Two years later, she developed disseminated BCGitis which was treated with proper antimicrobial agents. At the age of 7 years, she presented with clinical features fulfilling 6 diagnostic criteria of HLH including evidence of hemophagocytic activity in bone marrow aspiration. Accordingly, the diagnosis of HLH was established and the patient was started on IV Dexamethasone, Anakinra and IVIG. Eventually, patient started to improve and was discharged in good condition. Few months later, the patient was readmitted with severe pneumonia and sepsis leading to death.

CONCLUSION

Patients with MHC class II deficiency might present with disseminated BCGitis especially if the patient has severe T cell lymphopenia. Additionally, this immune defect might be added to the list of inborn errors of immunity that can be complicated with HLH.

Role of monocytes/macrophages in renin-angiotensin system-induced hypertension and end organ damage

The renin-angiotensin system (RAS) is a central modulator of cardiovascular physiology. Pathophysiology of hypertension is commonly accompanied by hyper-activation of RAS. Angiotensin II receptor blockers (ARBs) and Angiotensin-converting enzyme (ACE) inhibitors are the gold standard treatment for hypertension. Recently, several studies highlighted the crucial role of immune system in hypertension. Angiotensin-II-induced hypertension is associated with low grade inflammation characterized by innate and adaptive immune system dysfunction. Throughout the progression of hypertension, monocyte/macrophage cells appear to have a crucial role in vascular inflammation and interaction with the arterial wall. Since myelomonocytic cells potentially play a key role in angiotensin-II-induced hypertension and organ damage, pharmacological targeting of RAS components in monocyte/macrophages may possibly present an innovative strategy for treatment of hypertension and related pathology.

Angiotensin II modulates THP-1-like macrophage phenotype and inflammatory signatures via angiotensin II type 1 receptor

Angiotensin II (Ang II) is a major component of the renin-angiotensin or renin-angiotensin-aldosterone system, which is the main element found to be involved in cardiopathology. Recently, long-term metabolomics studies have linked high levels of angiotensin plasma to inflammatory conditions such as coronary heart disease, obesity, and type 2 diabetes. Monocyte/macrophage cellular function and phenotype orchestrate the inflammatory response in various pathological conditions, most notably cardiometabolic disease. An activation of the Ang II system is usually associated with inflammation and cardiovascular disease; however, the direct effect on monocyte/macrophages has still not been well elucidated. Herein, we have evaluated the cellular effects of Ang II on THP-1-derived macrophages. Ang II stimulated the expression of markers involved in monocyte/macrophage cell differentiation (e.g., CD116), as well as adhesion, cell-cell interaction, chemotaxis, and phagocytosis (CD15, CD44, CD33, and CD49F). Yet, Ang II increased the expression of proinflammatory markers (HLA-DR, TNF-α, CD64, CD11c, and CD38) and decreased CD206 (mannose receptor), an M2 marker. Moreover, Ang II induced cytosolic calcium overload, increased reactive oxygen species, and arrested cells in the G1 phase. Most of these effects were induced via the angiotensin II type 1 receptor (AT1R). Collectively, our results provide new evidence in support of the effect of Ang II in inflammation associated with cardiometabolic diseases.

Quantitative proteomics analysis of COVID-19 patients: Fetuin-A and tetranectin as potential modulators of innate immune responses

Treatment of severe cases of coronavirus disease 2019 (COVID-19) is extremely important to minimize death and end-organ damage. Here we performed a proteomic analysis of plasma samples from mild, moderate and severe COVID-19 patients. Analysis revealed differentially expressed proteins and different therapeutic potential targets related to innate immune responses such as fetuin-A, tetranectin (TN) and paraoxonase-1 (PON1). Furthermore, protein changes in plasma showed dysregulation of complement and coagulation cascades in COVID-19 patients compared to healthy controls. In conclusion, our proteomics data suggested fetuin-A and TN as potential targets that might be used for diagnosis as well as signatures for a better understanding of the pathogenesis of COVID-19 disease.

Type I interferon autoantibodies in hospitalized patients with Middle East respiratory syndrome and association with outcomes and treatment effect of interferon beta‐1b in MIRACLE clinical trial

Background

Type I interferons (IFNs) are essential antiviral cytokines induced upon respiratory exposure to coronaviruses. Defects in type I IFN signaling can result in severe disease upon exposure to respiratory viral infection and are associated with worse clinical outcomes. Neutralizing autoantibodies (auto‐Abs) to type I IFNs were reported as a risk factor for life‐threatening COVID‐19, but their presence has not been evaluated in patients with severe Middle East respiratory syndrome (MERS).

Methods

We evaluated the prevalence of type I IFN auto‐Abs in a cohort of hospitalized patients with MERS who were enrolled in a placebo‐controlled clinical trial for treatment with IFN‐β1b and lopinavir‐ritonavir (MIRACLE trial). Samples were tested for type I IFN auto‐Abs using a multiplex particle‐based assay.

Results

Among the 62 enrolled patients, 15 (24.2%) were positive for immunoglobulin G auto‐Abs for at least one subtype of type I IFNs. Auto‐Abs positive patients were not different from auto‐Abs negative patients in age, sex, or comorbidities. However, the majority (93.3%) of patients who were auto‐Abs positive were critically ill and admitted to the ICU at the time of enrollment compared to 66% in the auto‐Abs negative patients. The effect of treatment with IFN‐β1b and lopinavir‐ritonavir did not significantly differ between the two groups.

Conclusion

This study demonstrates the presence of type I IFN auto‐Abs in hospitalized patients with MERS.

Achillea fragrantissima (Forssk.) Sch.Bip Flower Dichloromethane Extract Exerts Anti-Proliferative and Pro-Apoptotic Properties in Human Triple-Negative Breast Cancer (MDA-MB-231) Cells: In Vitro and In Silico Studies

The aggressive triple-negative breast cancer (TNBC) is a challenging disease due to the absence of tailored therapy. The search for new therapies involves intensive research focusing on natural sources. Achillea fragrantissima (A. fragrantissima) is a traditional medicine from the Middle East region. Various solvent extracts from different A. fragrantissima plant parts, including flowers, leaves, and roots, were tested on TNBC MDA-MB-231 cells. Using liquid chromatography, the fingerprinting revealed rich and diverse compositions for A. fragrantissima plant parts using polar to non-polar solvent extracts indicating possible differences in bioactivities. Using the CellTiter-Glo™ viability assay, the half-maximal inhibitory concentration (IC₅₀) values were determined for each extract and ranged from 32.4 to 161.7 µg/mL. The A. fragrantissima flower dichloromethane extract had the lowest mean IC₅₀ value and was chosen for further investigation. Upon treatment with increasing A. fragrantissima flower dichloromethane extract concentrations, the MDA-MB-231 cells displayed, in a dose-dependent manner, enhanced morphological and biochemical hallmarks of apoptosis, including cell shrinkage, phosphatidylserine exposure, caspase activity, and mitochondrial outer membrane permeabilization, assessed using phase-contrast microscopy, fluorescence-activated single-cell sorting analysis, Image-iT™ live caspase, and mitochondrial transition pore opening activity, respectively. Anticancer target prediction and molecular docking studies revealed the inhibitory activity of a few A. fragrantissima flower dichloromethane extract-derived metabolites against carbonic anhydrase IX, an enzyme reported for its anti-apoptotic properties. In conclusion, these findings suggest promising therapeutic values of the A. fragrantissima flower dichloromethane extract against TNBC development.

Immunogenicity of High-Dose MVA-Based MERS Vaccine Candidate in Mice and Camels

The Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic pathogen that can transmit from dromedary camels to humans, causing severe pneumonia, with a 35% mortality rate. Vaccine candidates have been developed and tested in mice, camels, and humans. Previously, we developed a vaccine based on the modified vaccinia virus Ankara (MVA) viral vector, encoding a full-length spike protein of MERS-CoV, MVA-MERS. Here, we report the immunogenicity of high-dose MVA-MERS in prime–boost vaccinations in mice and camels. Methods: Three groups of mice were immunised with MVA wild-type (MVA-wt) and MVA-MERS (MVA-wt/MVA-MERS), MVA-MERS/MVA-wt, or MVA-MERS/MVA-MERS. Camels were immunised with two doses of PBS, MVA-wt, or MVA-MERS. Antibody (Ab) responses were evaluated using ELISA and MERS pseudovirus neutralisation assays. Results: Two high doses of MVA-MERS induced strong Ab responses in both mice and camels, including neutralising antibodies. Anti-MVA Ab responses did not affect the immune responses to the vaccine antigen (MERS-CoV spike). Conclusions: MVA-MERS vaccine, administered in a homologous prime–boost regimen, induced high levels of neutralising anti-MERS-CoV antibodies in mice and camels. This could be considered for further development and evaluation as a dromedary vaccine to reduce MERS-CoV transmission to humans.

New Born Calf Serum Can Induce Spheroid Formation in Breast Cancer KAIMRC1 Cell Line

Three-dimensional (3D) cell culture systems have become very popular in the field of drug screening and discovery. There is an immense demand for highly efficient and easy methods to produce 3D spheroids in any cell format. We have developed a novel and easy method to produce spheroids from the newly isolated KAIMRC1 cell line in vitro. It can be used as a 3D model to study proliferation, differentiation, cell death, and drug response of cancer cells. Our procedure requires growth media supplemented with 10% new born calf serum (NBCS) and regular cell culture plates to generate KAIMRC1 spheroids without the need for any specialized 3D cell culture system. This procedure generates multiple spheroids within a 12–24-h culture. KAIMRC1 spheroids are compact, homogeneous in size and morphology with a mean size of 55.8 µm (±3.5). High content imaging (HCI) of KAIMRC1 spheroids treated with a panel of 240 compounds resulted in the identification of several highly specific compounds towards spheroids. Immunophenotyping of KAIMRC1 spheroids revealed phosphorylation of FAK, cJUN, and E-cadherin, which suggests the involvement of JNK/JUN pathway in the KAIMRC1 spheroids formation. Gene expression analysis showed upregulation of cell junction genes, GJB3, DSC1, CLDN5, CLDN8, and PLAU. Furthermore, co-culture of KAIMRC1 cells with primary cancer-associated-fibroblasts (CAFs) showcased the potential of these cells in drug discovery application.

Erythritol modulates the polarization of macrophages: Potential role of tumor necrosis factor-α and Akt pathway

Low-calorie sweeteners are substitutes for sugar and frequently used by patients with cardiometabolic diseases. Erythritol, a natural low-calorie sugar alcohol, was linked to cardiometabolic diseases in several recent metabolomics studies. However, the characterization of its role in disease development is lacking. Macrophage polarization orchestrates the immune response in various inflammatory conditions, most notably cardiometabolic disease. Therefore, the physiological effects of Erythritol on THP-1 macrophages were investigated. We observed an increased cellular abundance of proinflammatory M1 macrophages, characterized by CD11c, TNF-α, CD64, CD38, and HLA-DR markers and decreased anti-inflammatory M2 macrophages, characterized by mannose receptor CD206. The, Erythritol increased ROS generation, and the activation of the AKT pathway, cytosolic calcium overload, and cell cycle arrest at the G1 phase. Concomitantly, an increased population of necroptotic macrophages was observed. In conclusion, we provide evidence that Erythritol induced the proinflammatory phenotype in THP-1 macrophages and this was associated with an increased population of necroptotic macrophages. PRACTICAL APPLICATIONS: This assessment provides evidence of the effects of Erythritol on macrophages, particularly THP-1-derived macrophages. Our results support the role of Erythritol in driving the inflammation that is associated with cardiometabolic diseases and provide insights in the role of Erythritol as an inducer of necroptosis in THP-1 derived macrophages that could be associated the disease.

SARS-CoV-2 Coronavirus Spike Protein-Induced Apoptosis, Inflammatory, and Oxidative Stress Responses in THP-1-Like-Macrophages: Potential Role of Angiotensin-Converting Enzyme Inhibitor (Perindopril)

A purified spike (S) glycoprotein of severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) coronavirus was used to study its effects on THP-1 macrophages, peripheral blood mononuclear cells (PBMCs), and HUVEC cells. The S protein mediates the entry of SARS-CoV-2 into cells through binding to the angiotensin-converting enzyme 2 (ACE2) receptors. We measured the viability, intracellular cytokine release, oxidative stress, proinflammatory markers, and THP-1-like macrophage polarization. We observed an increase in apoptosis, ROS generation, MCP-1, and intracellular calcium expression in the THP-1 macrophages. Stimulation with the S protein polarizes the THP-1 macrophages towards proinflammatory futures with an increase in the TNFα and MHC-II M1-like phenotype markers. Treating the cells with an ACE inhibitor, perindopril, at 100 µM reduced apoptosis, ROS, and MHC-II expression induced by S protein. We analyzed the sensitivity of the HUVEC cells after the exposure to a conditioned media (CM) of THP-1 macrophages stimulated with the S protein. The CM induced endothelial cell apoptosis and MCP-1 expression. Treatment with perindopril reduced these effects. However, the direct stimulation of the HUVEC cells with the S protein, slightly increased HIF1α and MCP-1 expression, which was significantly increased by the ACE inhibitor treatment. The S protein stimulation induced ROS generation and changed the mitogenic responses of the PBMCs through the upregulation of TNFα and interleukin (IL)-17 cytokine expression. These effects were reduced by the perindopril (100 µM) treatment. Proteomic analysis of the S protein stimulated THP-1 macrophages with or without perindopril (100 µM) exposed more than 400 differentially regulated proteins. Our results provide a mechanistic analysis suggesting that the blood and vascular components could be activated directly through S protein systemically present in the circulation and that the activation of the local renin angiotensin system may be partially involved in this process.

Graphical

Suggested pathways that might be involved at least in part in S protein inducing activation of inflammatory markers (red narrow) and angiotensin-converting enzyme inhibitor (ACEi) modulation of this process (green narrow).

Seroprevalence of SARS-CoV-2 among high-risk healthcare workers in a MERS-CoV endemic area

INTRODUCTION

Healthcare workers (HCWs) in Saudi Arabia are a unique population who have had exposures to the Middle East Respiratory Syndrome coronavirus (MERS-CoV) and Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). It follows that HCWs from this country could have pre-existingMERS-CoV antibodies that may either protect from coronavirus disease 2019 (COVID-19) infection or cause false SARS-CoV-2 seropositive results. In this article, we report the seroprevalence of MERS-CoV and SARS-CoV-2 among high-risk healthcare workers in Riyadh city, Saudi Arabia.

METHODS

This is a cross-sectional study enrolling 420 high-risk HCWs who are physically in contact with COVID-19 patients in three tertiary hospitals in Riyadh city. The participants were recruited between the 1st of July to the end of December 2020. A 3 ml of the venous blood samples were collected and tested for the presence of IgG antibodies against the spike proteins of SARS-CoV-2 and MERS-CoV using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The overall prevalence of SARS-CoV-2 in high-risk HCWs was 14.8% based on SARS-CoV-2 IgG testing while only 7.4% were positive by Polymerase Chain Reaction (PCR) for viral RNA. Most of the SARS-CoV-2 seropositive HCWs had symptoms and the most frequent symptoms were body aches, fever, cough, loss of smell and taste, and headache. The seroprevalence of MERS-CoV IgG was 1% (4 participants) and only one participant had dual seropositivity against MERS-CoV and SARS-CoV-2. Three MERS-CoV positive samples (75%) turned to be negative after using in-house ELISA and none of the MERS-CoV seropositive samples had detectable neutralization activity.

CONCLUSION

Our SARS-CoV-2 seroprevalence results were higher than reported regional seroprevalence studies. This finding was expected and similar to other international findings that targeted high-risk HCWs. Our results provide evidence that the SARS-CoV-2- seropositivity in Saudi Arabia similar to other countries was due to exposure to SARS-CoV-2 rather than MERS-CoV antibody.

Classical and Counter-Regulatory Renin-Angiotensin System: Potential Key Roles in COVID-19 Pathophysiology

In the current COVID-19 pandemic, severe acute respiratory syndrome coronavirus 2 uses angiotensin-converting enzyme-2 (ACE-2) receptors for cell entry, leading to ACE-2 dysfunction and downregulation, which disturb the balance between the classical and counter-regulatory renin-angiotensin system (RAS) in favor of the classical RAS. RAS dysregulation is one of the major characteristics of several cardiovascular diseases; thus, adjustment of this system is the main therapeutic target. RAS inhibitors-particularly angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II type 1 receptor blockers (ARBs)-are commonly used for treatment of hypertension and cardiovascular disease. Patients with cardiovascular diseases are the group most commonly seen among those with COVID-19 comorbidity. At the beginning of this pandemic, a dilemma occurred regarding the use of ACEIs and ARBs, potentially aggravating cardiovascular and pulmonary dysfunction in COVID-19 patients. Urgent clinical trials from different countries and hospitals reported that there is no association between RAS inhibitor treatment and COVID-19 infection or comorbidity complication. Nevertheless, the disturbance of the RAS that is associated with COVID-19 infection and the potential treatment targeting this area have yet to be resolved. In this review, the link between the dysregulation of classical RAS and counter-regulatory RAS activities in COVID-19 patients with cardiovascular metabolic diseases is investigated. In addition, the latest findings based on ACEI and ARB administration and ACE-2 availability in relation to COVID-19, which may provide a better understanding of the RAS contribution to COVID-19 pathology, are discussed, as they are of the utmost importance amid the current pandemic.

Interferon-induced transmembrane protein-3 genetic variant rs12252 is associated with COVID-19 mortality

Interferon-induced membrane proteins (IFITM) 3 gene variants are known risk factor for severe viral diseases. We examined whether IFITM3 variant may underlie the heterogeneous clinical outcomes of SARS-CoV-2 infection-induced COVID-19 in large Arab population. We genotyped 880 Saudi patients; 93.8% were PCR-confirmed SARS-CoV-2 infection, encompassing most COVID-19 phenotypes. Mortality at 90 days was 9.1%. IFITM3-SNP, rs12252-G allele was associated with hospital admission (OR = 1.65 [95% CI; 1.01-2.70], P = 0.04]) and mortality (OR = 2.2 [95% CI; 1.16-4.20], P = 0.01). Patients less than 60 years old had a lower survival probability if they harbor this allele (log-rank test P = 0.002). Plasma levels of IFNγ were significantly lower in a subset of patients with AG/GG genotypes than patients with AA genotype (P = 0.00016). Early identification of these individuals at higher risk of death may inform precision public health response.

A homozygous nonsense mutation in DCBLD2 is a candidate cause of developmental delay, dysmorphic features and restrictive cardiomyopathy

DCBLD2 encodes discodin, CUB and LCCL domain-containing protein 2, a type-I transmembrane receptor that is involved in intracellular receptor signalling pathways and the regulation of cell growth. In this report, we describe a 5-year-old female who presented severe clinical features, including restrictive cardiomyopathy, developmental delay, spasticity and dysmorphic features. Trio-whole-exome sequencing and segregation analysis were performed to identify the genetic cause of the disease within the family. A novel homozygous nonsense variant in the DCBLD2 gene (c.80G > A, p.W27*) was identified as the most likely cause of the patient's phenotype. This nonsense variant falls in the extracellular N-terminus of DCBLD2 and thus might affect proper protein function of the transmembrane receptor. A number of in vitro investigations were performed on the proband's skin fibroblasts compared to normal fibroblasts, which allowed a comprehensive assessment resulting in the functional characterization of the identified DCBLD2 nonsense variant in different cellular processes. Our data propose a significant association between the identified variant and the observed reduction in cell proliferation, cell cycle progression, intracellular ROS, and Ca2 + levels, which would likely explain the phenotypic presentation of the patient as associated with lethal restrictive cardiomyopathy.

Pancytopenia, Recurrent Infection, Poor Wound Healing, Heterotopia of the Brain Probably Associated with A Candidate Novel de Novo CDC42 Gene Defect: Expanding the Molecular and Phenotypic Spectrum

CDC42 (cell division cycle protein 42) belongs to the Rho GTPase family that is known to control the signaling axis that regulates several cellular functions, including cell cycle progression, migration, and proliferation. However, the functional characterization of the CDC42 gene in mammalian physiology remains largely unclear. Here, we report the genetic and functional characterization of a non-consanguineous Saudi family with a single affected individual. Clinical examinations revealed poor wound healing, heterotopia of the brain, pancytopenia, and recurrent infections. Whole exome sequencing revealed a de novo missense variant (c.101C > A, p.Pro34Gln) in the CDC42 gene. The functional assays revealed a substantial reduction in the growth and motility of the patient cells as compared to the normal cells control. Homology three-dimensional (3-D) modeling of CDC42 revealed that the Pro34 is important for the proper protein secondary structure. In conclusion, we report a candidate disease-causing variant, which requires further confirmation for the etiology of CDC42 pathogenesis. This represents the first case from the Saudi population. The current study adds to the spectrum of mutations in the CDC42 gene that might help in genetic counseling and contributes to the CDC42-related genetic and functional characterization. However, further studies into the molecular mechanisms that are involved are needed in order to determine the role of the CDC42 gene associated with aberrant cell migration and immune response.

The Effect of Local Renin Angiotensin System in the Common Types of Cancer

The Renin Angiotensin System (RAS) is a hormonal system that is responsible for blood pressure hemostasis and electrolyte balance. It is implicated in cancer hallmarks because it is expressed locally in almost all of the body's tissues. In this review, current knowledge on the effect of local RAS in the common types of cancer such as breast, lung, liver, prostate and skin cancer is summarised. The mechanisms by which RAS components could increase or decrease cancer activity are also discussed. In addition to the former, this review explores how the administration of AT1R blockers and ACE inhibitors drugs intervene with cancer therapy and contribute to the outcomes of cancer.

Stimulation of calcium influx and CK1α by NF-κB antagonist [6]-Gingerol reprograms red blood cell longevity

Chemotherapy-induced anemia (CIA) is a major obstacle in cancer management. Although the mechanisms governing CIA are poorly understood, recent efforts have identified suicidal erythrocyte (red blood cell, RBC) death as a possible cause of CIA. [6]-Gingerol (GNG), a polyphenol extracted from Zingiber officinale plant, exhibits a wide array of biological activities including antimicrobial, antioxidant, anti-inflammatory, immunomodulatory, and anticancer activities, in vitro and in vivo. However, the potential toxicity of GNG to human RBCs remains unexplored. RBCs from heparinized blood were isolated by centrifugation and exposed to antitumor concentrations (10-100 µM) of GNG for 24 hr at 37°C. Hemolysis was calculated from hemoglobin leakage in the supernatant (λ_max  = 405 nm), while cytofluorometric analysis of eryptosis employed Annexin-V-FITC to detect phosphatidylserine (PS) exposure, forward scatter (FSC) to estimate cell volume, Fluo4/AM to measure calcium activity, and H₂ DCFDA to assess oxidative stress. Moreover, zVAD(OMe)-FMK, SB203580, necrostatin-2, staurosporin, and D4476 were used to identify signaling pathways responsive to GNG. GNG induced significant hemolysis at 100 µM, independently of extracellular calcium, and increased Annexin-V-FITC fluorescence that was thoroughly abrogated without extracellular calcium. GNG also enhanced Fluo4 fluorescence and reduced FSC, but had no significant effect on DCF fluorescence. Importantly, the presence of D4476 significantly attenuated GNG-induced hemolysis. In conclusion, GNG stimulates premature RBC death characterized by loss of membrane asymmetry, elevated cytosolic calcium, cell shrinkage, and casein kinase 1α activation. Blocking the activity of calcium channels or CK1α may, therefore, ameliorate the toxic effects of GNG on RBCs. PRACTICAL APPLICATIONS: This report presents a safety assessment of GNG as a chemotherapeutic agent and highlights the novel toxicity of GNG to human RBCs. Our findings provide novel insights that may lead to more efficient utilization of GNG in chemotherapy. Specifically, our data revealed the involvement of calcium channels and casein kinase 1α in mediating GNG-induced premature RBC death, and, therefore, inverse agonists or inhibitors of either pathway may be used as pharmaceutical adjuvants to attenuate the toxic effects of GNG.

CD4+ Regulatory T Lymphocytes Prevent Impaired Cerebral Blood Flow in Angiotensin II-Induced Hypertension

Background

Immune cells are key regulators of the vascular inflammatory response characteristic of hypertension. In hypertensive rodents, regulatory T lymphocytes (Treg, CD4⁺CD25⁺) prevented vascular injury, cardiac damage, and endothelial dysfunction of mesenteric arteries. Whether Treg modulate the cerebrovascular damage induced by hypertension is unknown.

Methods and Results

C57BL/6 mice were perfused with angiotensin II (Ang II; 1000 ng/kg per minute) for 14 days and adoptive transfer of 3×10⁵CD4⁺CD25⁺ T cells was performed via 2 intravenous injections. Control mice received a sham surgery and PBS. Treg prevented Ang II‐induced neurovascular uncoupling (P<0.05) and endothelial impairment (P<0.05), evaluated by laser Doppler flowmetry in the somatosensory cortex. The neuroprotective effect of Treg was abolished when they were isolated from mice deficient in interleukin‐10. Administration of interleukin‐10 (60 ng/d) to hypertensive mice prevented Ang II‐induced neurovascular uncoupling (P<0.05). Treg adoptive transfer also diminished systemic inflammation induced by Ang II (P<0.05), examined with a peripheral blood cytokine array. Mice receiving Ang II + Treg exhibited reduced numbers of Iba‐1+ cells in the brain cortex (P<0.05) and hippocampus (P<0.001) compared with mice infused only with Ang II. Treg prevented the increase in cerebral superoxide radicals. Overall, these effects did not appear to be directly modulated by Treg accumulating in the brain parenchyma, because only a nonsignificant number of Treg were detected in brain. Instead, Treg penetrated peripheral tissues such as the kidney, inguinal lymph nodes, and the spleen.

Conclusions

Treg prevent impaired cerebrovascular responses in Ang II‐induced hypertension. The neuroprotective effects of Treg involve the modulation of inflammation in the brain and periphery.

miR-431-5p Knockdown Protects Against Angiotensin II-Induced Hypertension and Vascular Injury

Vascular injury is an early manifestation in hypertension and a cause of end-organ damage. MicroRNAs play an important role in cardiovascular disease, but their implication in vascular injury in hypertension remains unclear. This study revealed using an unbiased approach, microRNA and mRNA sequencing with molecular interaction analysis, a microRNA-transcription factor coregulatory network involved in vascular injury in mice made hypertensive by 14-day Ang II (angiotensin II) infusion. A candidate gene approach identified upregulated miR-431-5p encoded in the conserved 12qF1 (14q32 in humans) microRNA cluster, whose expression correlated with blood pressure, and which has been shown to be upregulated in human atherosclerosis, as a potential key regulator in Ang II-induced vascular injury. Gain- and loss-of-function in human vascular smooth muscle cells demonstrated that miR-431-5p regulates in part gene expression by targeting ETS homologous factor. In vivo miR-431-5p knockdown delayed Ang II-induced blood pressure elevation and reduced vascular injury in mice, which demonstrated its potential as a target for treatment of hypertension and vascular injury.

Delta Like-1 Gene Mutation: A Novel Cause of Congenital Vertebral Malformation

Skeletal development throughout the embryonic and postnatal phases is a dynamic process, based on bone remodeling and the balance between the activities of osteoclasts and osteoblasts modulating skeletal homeostasis. The Notch signaling pathway is a regulator of several developmental processes, and plays a crucial role in the development of the human skeleton by regulating the proliferation and differentiation of skeletal cells. The Delta Like-1 (DLL1) gene plays an important role in Notch signaling. We propose that an identified alteration in DLL1 protein may affect the downstream signaling. In this article, we present for the first time two siblings with a mutation in the DLL1 gene, presenting with congenital vertebral malformation. Using variable in silico prediction tools, it was predicted that the variant was responsible for the development of disease. Quantitative reverse-transcription polymerase chain reaction (PCR) for the Notch signaling pathway, using samples obtained from patients, showed a significant alteration in the expression of various related genes. Specifically, the expression of neurogenic locus notch homolog protein 1, SNW domain-containing protein 1, disintegrin, and metalloproteinase domain-containing proteins 10 and 17, was upregulated. In contrast, the expression of HEY1, HEY2, adenosine deaminase (ADA), and mastermind-like-1 (MAML-1) was downregulated. Furthermore, in a phosphokinase array, four kinases were significantly changed in patients, namely, p27, JANK1/2/3, mitogen- and stress-activated protein kinases 1 and 2, and focal adhesion kinase. Our results suggest an implication of a DLL1 defect related to the Notch signaling pathway, at least in part, in the morphologic abnormality observed in these patients. A limitation of our study was the low number of patients and samples. Further studies in this area are warranted to decipher the link between a DLL1 defect and skeletal abnormality.

Matrix metalloproteinase-2 knockout prevents angiotensin II-induced vascular injury

Aims

Matrix metalloproteinases (MMPs) have been implicated in the development of hypertension in animal models and humans. Mmp2 deletion did not change Ang II-induced blood pressure (BP) rise. However, whether Mmp2 knockout affects angiotensin (Ang) II-induced vascular injury has not been tested. We sought to determine whether Mmp2 knockout will prevent Ang II-induced vascular injury.

Methods and results

A fourteen-day Ang II infusion (1000 ng/kg/min, SC) increased systolic BP, decreased vasodilatory responses to acetylcholine, induced mesenteric artery (MA) hypertrophic remodelling, and enhanced MA stiffness in wild-type (WT) mice. Ang II enhanced aortic media and perivascular reactive oxygen species generation, aortic vascular cell adhesion molecule-1 and monocyte chemotactic protein-1 expression, perivascular monocyte/macrophage and T cell infiltration, and the fraction of spleen activated CD4+CD69+ and CD8+CD69+ T cells, and Ly-6Chi monocytes. Study of intracellular signalling showed that Ang II increased phosphorylation of epidermal growth factor receptor and extracellular-signal-regulated kinase 1/2 in vascular smooth muscle cells isolated from WT mice. All these effects were reduced or prevented by Mmp2 knockout, except for systolic BP elevation. Ang II increased Mmp2 expression in immune cells infiltrating the aorta and perivascular fat. Bone marrow (BM) transplantation experiments revealed that in absence of MMP2 in immune cells, Ang II-induced BP elevation was decreased, and that when MMP2 was deficient in either immune or vascular cells, Ang II-induced endothelial dysfunction was blunted.

Conclusions

Mmp2 knockout impaired Ang II-induced vascular injury but not BP elevation. BM transplantation revealed a role for immune cells in Ang II-induced BP elevation, and for both vascular and immune cell MMP2 in Ang II-induced endothelial dysfunction.

Abstract P162: In vivo miR-431 Inhibition Protects Against Vascular Damage and Hypertension

Background: Vascular injury is an early manifestation of hypertension. microRNAs (miRNAs) play an important role in cardiovascular disease, but their implication in vascular injury remains unclear. Using small and total RNA sequencing, we identified in murine mesenteric arteries (MAs) a conserved angiotensin (Ang) II-upregulated Dlk1-Dio3 miRNA miR-431 that correlated with blood pressure (BP), and an Ang II-downregulated BP-correlated conserved putative miR-431 target, the transcriptional factor ETS homologous factor ( Ehf ). miR-431 might be involved in vascular remodeling as Ehf regulates expression of extracellular matrix genes including alpha-1 type I collagen ( Col1a1 ) and of other Dlk1-Dio3 miRNAs. In this study, we proposed to validate the miR-431- Ehf - Col1a1 interaction in vitro and in vivo , and determine whether miR-431 inhibition antagonizes angiotensin (Ang) II-induced hypertension and vascular injury.

Methods and Results: Transfection of miR-431 mimics into human aortic smooth muscle cells decreased Ehf expression (0.13±0.05 fold, P <0.001) and increased Col1a1 (1.7±0.5 fold, P <0.01), whereas miR-431 inhibitors increased Ehf (1.5±0.2 fold, P <0.001) and decreased Col1a1 (0.89±0.11 fold, P <0.05). Ehf siRNA transfection increased 1.2±0.1 fold Col1a1 ( P <0.01). Co-transfection of miR-431 mimics with luciferase reporter vectors that contain the wild-type but not mutated miR-431 human EHF 3’ UTR binding site decreased 0.51±0.01 fold ( P <0.05) luciferase expression compared to scrambled mimics. miR-431 inhibitor IV injection in mice at day 0 and 7 of Ang II infusion decreased miR-431 (0.16±0.05 fold, P <0.01), Col1a1 (0.58±0.11 fold, P <0.05), increased Ehf (2.9±0.8 fold, P <0.05) in MAs, delayed BP elevation ( P <0.01), improved endothelium-dependent relaxation (33±8 vs 64±7%, P <0.05) and reduced vascular stiffness (strain at 140mmHg: 0.68±0.02 vs 0.58±0.02 ΔD/D, P <0.01) compared to scrambled mimics-injected Ang II-infused mice.

Conclusion and Perspectives: miR-431 and its target Ehf may act as master regulators in the pathophysiology of vascular damage in hypertension. miR-431 inhibition has the potential to serve as a novel therapeutic approach for treatment of vascular damage and hypertension.

Abstract 065: Induction of Human Endothelin-1 Overexpression for 3 Months Causes Blood Pressure Rise and Renal Injury

Introduction: Endothelium-derived endothelin (ET)-1 has been implicated in hypertension and renal disease but the mechanisms are complex and remain unclear. We have shown that tamoxifen-inducible endothelium-restricted human ET-1 overexpressing (ieET-1) mice exhibited BP rise after 3 weeks of induction in an ET type A receptor (ET A R)-dependent manner, in absence of renal injury. It is unknown whether long-term exposure to ET-1 overexpression results in sustained BP elevation and renal injury.

Methods: Adult male ieET-1 and control tamoxifen-inducible endothelium-restricted Cre recombinase (ieCre) mice were treated with tamoxifen (1 mg/kg/day, SC) for 5 days and 2.5 months later were treated or not with an ET A R blocker, atrasentan (10 mg/kg/day, PO) for 2 weeks. Blood pressure (BP) by telemetry, renal artery flow (RAF) by ultrasonography, immune cell infiltration by flow cytometry, kidney injury molecule (KIM)-1 expression by immunofluorescence, 24h urinary albumin by ELISA and creatinine by alkaline picrate method were determined at the end of the study.

Results: Induction of ET-1 overexpression for 3 months resulted in greater systolic BP (135±4 vs 114±2 mmHg, P <0.001) and reduced RAF (1.7±0.2 vs 3±0.3 mL/min, P <0.05). ieET-1 mice presented increased myeloid (21255±5294 vs 5146±1987 CD11b + cells/kidney, P <0.001) and myeloid-derived suppressor cells (5332±1463 vs 1126±507 CD11b + Gr-1 + cells/kidney, P <0.01) renal infiltration associated with greater frequency of CD11b + (23.2±1.8 vs 7.5±1.6 % of CD45 + cells, P <0.001) and non-immune renal cells (CD45 - , 5.7±0.8 vs 3.2±0.6 % of CD45 - cells, P <0.001) expressing a pro-inflammatory maker, CD36. Early renal injury was demonstrated in ieET-1 by increased KIM-1 expression in proximal tubules (4.0±0.7 vs 1.0±0.2 % of renal cortex, P <0.05) and unchanged albumin/creatinine ratio (327±74 vs 173±36 μg/mg, P=0.215). Atrasentan reversed or reduced all of the above except the decreased RAF ( P <0.05).

Conclusions: Long-term exposure to endothelial ET-1 overexpression caused sustained BP elevation and renal injury via ET A R.

γδ T Cells Mediate Angiotensin II-Induced Hypertension and Vascular Injury

Background:

Innate antigen-presenting cells and adaptive immune T cells have been implicated in the development of hypertension. However, the T-lymphocyte subsets involved in the pathophysiology of hypertension remain unclear. A small subset of innate-like T cells expressing the γδ T cell receptor (TCR) rather than the αβ TCR could play a role in the initiation of the immune response in hypertension. We aimed to determine whether angiotensin (Ang) II caused kinetic changes in γδ T cells; deficiency in γδ T cells blunted Ang II-induced hypertension, vascular injury, and T-cell activation; and γδ T cells are associated with human hypertension.

Methods:

Male C57BL/6 wild-type and Tcrδ −/− mice, which are devoid of γδ T cells, or wild-type mice injected IP with control isotype IgG or γδ T cell-depleting antibodies, were infused or not with Ang II for 3, 7, or 14 days. T-cell profiling was determined by flow cytometry, systolic blood pressure (SBP) by telemetry, and mesentery artery endothelial function by pressurized myography. TCR γ constant region gene expression levels and clinical data of a whole blood gene expression microarray study, including normotensive and hypertensive subjects, were used to demonstrate an association between γδ T cells and SBP.

Results:

Seven- and 14-day Ang II infusion increased γδ T-cell numbers and activation in the spleen of wild-type mice ( P <0.05). Fourteen days of Ang II infusion increased SBP ( P <0.01) and decreased mesenteric artery endothelial function ( P <0.01) in wild-type mice, both of which were abrogated in Tcrδ −/− mice ( P <0.01). Anti-TCRγδ antibody-induced γδ T-cell depletion blunted Ang II-induced SBP rise and endothelial dysfunction ( P <0.05), compared with isotype antibody-treated Ang II-infused mice. Ang II-induced T-cell activation in the spleen and perivascular adipose tissue was blunted in Tcrδ −/− mice ( P <0.01). In humans, the association between SBP and γδ T cells was demonstrated by a multiple linear regression model integrating whole blood TCR γ constant region gene expression levels and age and sex ( R 2 =0.12, P <1×10 -6 ).

Conclusions:

γδ T cells mediate Ang II-induced SBP elevation, vascular injury, and T-cell activation in mice. γδ T cells might contribute to the development of hypertension in humans.

Endothelin-1 Overexpression Exaggerates Diabetes-Induced Endothelial Dysfunction by Altering Oxidative Stress

BACKGROUND

Increased endothelin (ET)-1 expression causes endothelial dysfunction and oxidative stress. Plasma ET-1 is increased in patients with diabetes mellitus. Since endothelial dysfunction often precedes vascular complications in diabetes, we hypothesized that overexpression of ET-1 in the endothelium would exaggerate diabetes-induced endothelial dysfunction.

METHODS

Diabetes was induced by streptozotocin treatment (55mg/kg/day, i.p.) for 5 days in 6-week-old male wild type (WT) mice and in mice overexpressing human ET-1 restricted to the endothelium (eET-1). Mice were studied 14 weeks later. Small mesenteric artery (MA) endothelial function and vascular remodeling by pressurized myography, reactive oxygen species (ROS) production by dihydroethidium staining and mRNA expression by reverse transcription/quantitative PCR were determined.

RESULTS

Endothelium-dependent vasodilatory responses to acetylcholine of MA were reduced 24% by diabetes in WT ( P < 0.05), and further decreased by 12% in eET-1 ( P < 0.05). Diabetes decreased MA media/lumen in WT and eET-1 ( P < 0.05), whereas ET-1 overexpression increased MA media/lumen similarly in diabetic and nondiabetic WT mice ( P < 0.05). Vascular ROS production was increased 2-fold by diabetes in WT ( P < 0.05) and further augmented 1.7-fold in eET-1 ( P < 0.05). Diabetes reduced endothelial nitric oxide synthase (eNOS, Nos3 ) expression in eET-1 by 31% ( P < 0.05) but not in WT. Induction of diabetes caused a 52% ( P < 0.05) increase in superoxide dismutase 1 ( Sod1 ) and a 32% ( P < 0.05) increase in Sod2 expression in WT but not in eET-1.

CONCLUSIONS

Increased expression of ET-1 exaggerates diabetes-induced endothelial dysfunction. This may be caused by decrease in eNOS expression, increase in vascular oxidative stress, and decrease in antioxidant capacity.

Abstract 083: γ/δ T Cells Play a Role in Development of Hypertension

Objective: Both innate antigen-presenting cells and the adaptive immune system have been shown to play a role in the development of hypertension. Nevertheless, the T cell subsets involved in the pathophysiology of hypertension remains unclear. There is a small subset of “innate-like” T cells expressing the γ/δ T cell receptor (TCR) rather than the α/β TCR that could play a role bridging the innate and adaptive immune systems. We previously observed that angiotensin (Ang) II caused an increase in number and activation of γ/δ T cells and Ang II-induced systolic blood pressure (SBP) rise and vascular injury were blunted in Tcr δ -/- mice, which are devoid of γ/δ T cells. In order to further characterize the role of γ/δ T cells in hypertension, we determined whether Ang II-effects would be blunted by antibody-induced depletion of γ/δ T cells. In addition, we tested whether SBP in human could be predicted by combining the expression of genes encoding TCRGC (TCR gamma constant region) and pro-inflammatory markers of γ/δ T cells in peripheral blood mononuclear cells (PBMC).

Method and Results: Thirteen to 15-week old male C57BL/6 wild-type (WT) mice were infused with Ang II (490 ng/kg/min, SC) for 14 days and injected IP with anti-γ/δ TCR or control isotype antibodies 1 day before and at day 6 of Ang II infusion. Depletion of γ/δ T cells decreased SBP (147±2 vs 167 ± 3 mm Hg, P <0.05) and restored mesenteric artery relaxation responses to acetylcholine (E max : 90±4 vs 62 ± 8%, P <0.05) compared to isotype antibody-treated mice. Using the SBP data and the PBMC gene expression profile (GSE12288) of 222 human subjects, we predicted with a supervised machine learning approach SBP by combining the gene expression of TCRGC and pro-inflammatory makers including interleukin-17A, interferon-γ and their receptors (R=0.23, P <0.001).

Conclusion: Antibody-induced depletion further demonstrates the role of γ/δ T cells in Ang II-induced SBP elevation and vascular injury. Prediction of SBP using PBMC gene expression of γ/δ T cells and pro-inflammatory markers suggests that γ/δ T cells contribute to the development of human hypertension.

Abstract P224: Endothelin-1 Overexpression Preserves Endothelial Function in Mice with Vascular Smooth Muscle Cell-specific Deletion of PPAR-gamma

Objective: Peroxisome proliferator-activated receptor γ (PPARγ) agonists reduce blood pressure (BP) and vascular injury in hypertensive rodents. Pparγ inactivation in vascular smooth muscle cells (VSMC) using a tamoxifen inducible Cre-Lox system enhanced angiotensin II-induced vascular damage. Transgenic mice overexpressing endothelin (ET)-1 in the endothelium (eET-1) exhibit endothelial dysfunction, increased oxidative stress and inflammation. We hypothesized that inactivation of the Ppar gene in VSMC (sm Pparγ -/- ) would exaggerate ET-1-induced vascular damage.

Methods and Results: Eleven-week-old male control, eET-1, sm Pparγ -/- and eET-1/sm Pparγ -/- mice were treated with tamoxifen (1 mg/kg/day, s.c.) for 5 days and sacrificed 4 weeks later. Systolic BP determined by telemetry was higher in eET-1 (123±5 vs 109±2 mm Hg, P <0.05) and unaffected by sm Pparγ inactivation. Mesenteric artery (MA) vasorelaxation to acetylcholine was impaired only in sm Pparγ -/- (E max : 52.0±6.7 vs 82.2±4.9%, P <0.05). MA reactive oxygen species levels were increased 1.7±0.3-fold in sm Pparγ -/- ( P <0.05) and further increased in eET-1/sm Pparγ -/- (2.5±0.3-fold, P <0.05). MA perivascular fat monocyte/macrophage infiltration was higher in eET-1 and sm Pparγ -/- (331±34 and 326±49 vs 140±8 cells/mm 2 , P <0.05), and further increased in eET-1/sm Pparγ -/- (557±77, P <0.05). The spleen fraction of CD11b + cells was increased in sm Pparγ -/- (1.1±0.1 vs 0.47±0.1%, P <0.05) and further increased in eET-1/sm Pparγ -/- (1.8±0.2%, P <0.05). The spleen fraction of Ly-6C hi monocytes was increased in eET-1 and sm Pparγ -/- (24±3 and 27±4 vs 14±1%, P <0.05) but not in eET-1/sm Pparγ -/- . The spleen fraction of T regulatory cells was increased in sm Pparγ -/- (13±2 vs 9±1%, P <0.05) and decreased in eET-1 (7±1%, P <0.05), which was further decreased by eET-1/sm Pparγ -/- (3±1%, P <0.05).

Conclusions: These results suggest that increased ET-1 paradoxically preserves endothelial function in mice with inactivated VSMC Pparγ despite enhanced oxidative stress. Flow cytometry data indicate that infiltrating monocyte/macrophages in these mice might be anti-inflammatory.

Abstract 107: Mir-431 as a Potential Master Regulator in Angiotensin Ii-induced Vascular Injury

Objective: Vascular injury is an early manifestation and a cause of end-organ damage in hypertension. microRNAs (miRNAs) play an important role in cardiovascular disease, but their implication in vascular injury is remains unclear. We aim to use RNA sequencing (seq) and a systems biology approach to identify master regulators that mediate global gene expression changes in the course of vascular injury.

Methods and Results: Ten week-old male C57BL/6 mice were infused or not with angiotensin (Ang) II (1 μg/kg/min, SC) for 14 days. Blood pressure (BP) was measured by telemetry. Total RNA was extracted from the mesenteric vasculature for total RNA and small RNA-seq. Differentially expressed (DE) miRNAs (23 up and 12 down) and mRNAs (550 up and 256 down) were identified (1.5-fold, q <0.05). Molecular networks were constructed to integrate predicted interactions between DE miRNAs and inversely expressed DE mRNAs and between DE transcription factors (TF) and DE genes. Gene enrichment analysis revealed DE mRNAs involved in extracellular matrix (ECM) and developmental processes regulated by DE miRNAs ( q <1.5E-11). Seventeen upregulated miRNAs are located in the miRNA cluster of the Dlk1-Dio3 region that is highly conserved in humans, 9 of which had expression levels correlated with BP ( P <0.05). Among those 9, miR-431 that ranked first as DE miRNA ( q <0.0005) and is 100% conserved in humans, and a conserved putative DE target, a BP-correlated ( P <0.05) TF ETS homologous factor ( Ehf ), which regulates numerous ECM genes including collagen type I α1 ( Col1a1 ), were selected for functional studies. Transfection of a miR-431 mimic in human aortic smooth muscle cells (HASMCs) decreased Ehf (0.1±0.1-fold, P <0.001) and increased Ehf -suppressing target Col1a1 (1.7±0.5-fold, P <0.001) mRNA levels. Transfection of a miR-431 inhibitor caused reciprocal effects ( P <0.05). Ehf siRNA knockdown increased Col1a1 (1.2±0.1-fold, P <0.001) mRNA levels.

Conclusions: Ang II infusion altered expression of miRNAs in the Dlk1-Dio3 cluster and genes involved in ECM and developmental processes. miR-431 targets TF Ehf , which leads to increased Col1a1 in HASMCs. miR-431 may act as a master regulator for vascular injury and could be a potential therapeutic target.

Abstract P226: Endothelin-1 Overexpression Exaggerates Diabetes-induced Endothelial Dysfunction by Altering Oxidative Stress

Objective: Increased endothelin (ET)-1 expression has been shown to cause endothelial dysfunction and oxidative stress. Plasma ET-1 is increased in patients with diabetes mellitus. Since endothelial dysfunction often precedes vascular complications in diabetes, we sought to determine whether ET-1 contributes to diabetes-induced endothelial dysfunction. We hypothesized that overexpression of ET-1 in the endothelium will exaggerate diabetes-induced endothelial dysfunction.

Methods: Diabetes was induced by streptozotocin IP injections (STZ, 55 mg/kg/day) for 5 days in 6-week-old male wild-type (WT) mice and in mice overexpressing human ET-1 restricted to the endothelium (eET-1). Mice were studied 14 weeks later. Endothelial function and vascular remodeling using pressurized myography, reactive oxygen species (ROS) production by dihydroethidium staining and mRNA expression by reverse transcription-quantitative PCR were assessed in mesenteric arteries (MA).

Results: MA endothelium-dependent vasodilatory responses to acetylcholine were reduced 24% by diabetes in WT (E max : 61±6 vs 84±3%, P <0.05), and further decreased by 12% in eET-1 (E max : 49±5, P <0.05). Diabetes decreased MA media/lumen in WT (2.4±0.1% vs 3.3±0.2%, P <0.05) and eET-1 (2.9±0.2% vs 4.0±0.2%, P <0.05), whereas ET-1 overexpression increased MA media/lumen to a similar extent in diabetic and non-diabetic WT mice ( P <0.05). Vascular ROS production in MA was increased 2-fold by diabetes in WT (5.0±0.5 vs 2.5±0.3 relative fluorescence units [RFU]/μm 2 , P <0.05) and further augmented 1.7-fold in eET-1 (8.5±1.2 RFU/μm 2 , P <0.05). Diabetes reduced endothelial nitric oxide synthase (eNOS, Nos3) mRNA expression in eET-1 by 50% (0.7±0.1 vs 1.4±0.2, P <0.05) but not in WT. Induction of diabetes caused a 50% increase in superoxide dismutase 1 ( Sod1 , 1.5±0.2 vs 1.0±0.0, P <0.05) and a 30% increase in Sod2 (1.3±0.1 vs 1.0±0.0, P <0.05) mRNA expression in WT but not in eET-1.

Conclusions: Increased expression of ET-1 exaggerates diabetes-induced endothelial dysfunction. This may be caused by an increase in vascular oxidative stress, a decrease in eNOS expression and a decrease in antioxidant capacity.

Abstract P220: Matrix Metalloproteinase 2 Knockout Protects from Angiotensin II-induced Vascular Injury

Objective: Matrix metalloproteinase-2 (MMP2) participates in the mechanisms of vascular injury in atherosclerosis. Whether MMP2 plays a role in angiotensin (Ang) II-induced hypertension and vascular remodeling is unknown. We hypothesized that Mmp2 knockout ( Mmp2 -/- ) would prevent Ang II-induced hypertension and vascular injury.

Methods and Results: Fourteen days of Ang II infusion (1000 ng/kg/min, SC) increased systolic blood pressure (SBP, 161±9 vs 122±3 mm Hg, P <0.05) and decreased vasodilatory responses to acetylcholine (33±5 vs 83±3%, P <0.001), increased the media/lumen (4.8±0.4 vs 3.1±0.1%, P <0.001) and media cross-sectional area (7223±467 vs 5346±336 μm 2 , P <0.05) and enhanced stiffness ( P <0.05), as shown by a leftward shift of the stress/strain relationship of mesenteric arteries in wild-type mice. Ang II enhanced aortic (73±6 vs 6±1 relative fluorescence units [RFU]/μm 2 , P <0.001) and perivascular adipose tissue (PVAT) reactive oxygen species generation (76±11 vs 12±1 RFU/μm 2 , P <0.001), aortic VCAM-1 (17±3 vs 5±1 RFU/μm 2 , P <0.001) and MCP-1 expression (71±14 vs 11±3 RFU/μm 2 , P <0.001), PVAT monocyte/macrophage (1.8±0.3 vs 0.1±0.1 % of PVAT, P <0.001) and T cell infiltration (56±14 vs 16±9 cells/μm 2 , P <0.05) and the fraction of spleen activated CD4 + CD69 + (17±2 vs 10±1 % of CD4+ T cells, P <0.001), CD8 + CD69 + T cells (11±1 vs 5±1 % of CD4+ T cells, P <0.001) and Ly-6C hi monocytes (53±6 vs 25±2 % event, P <0.001). Ang II increased phosphorylation of epidermal growth factor receptor 1.9±0.2-fold and extracellular-signal-regulated kinase 1/2 1.4±0.1-fold in vascular smooth muscle cells isolated from mesenteric arteries of wild-type mice ( P <0.05). Mmp2 knockout prevented or reduced all of the above ( P <0.05) except SBP elevation. Bone marrow transplantation experiments revealed that Ang II-induced hypertension was impaired in absence of immune cell MMP2 and endothelial dysfunction was blunted or reduced in absence of immune or vascular cell MMP2 ( P <0.05).

Conclusions: Mmp2 knockout prevented Ang II-induced vascular injury but not hypertension. Bone marrow transplantation experiments revealed a complex relationship of immune and vascular cell MMP2 in the development of Ang II-induced hypertension and endothelial dysfunction.

Abstract P218: Induction of Human Endothelin-1 Overexpression for 3 Months Causes Blood Pressure Rise and Small Artery Endothelial Dysfunction and Stiffening

Background: The mechanisms of blood pressure (BP) regulation by endothelin (ET)-1 produced by endothelial cells are complex and remain unclear. Recently, we developed a transgenic mouse with tamoxifen-inducible endothelium-restricted human ET-1 overexpression (ieET-1) using Cre/loxP technology. ieET-1 mice exhibited BP rise after three weeks of induction in an ET type A (ET A ) receptor-dependent manner, in absence of vascular and kidney injury. It is unknown whether long-term exposure to ET-1 overexpression results in sustained BP elevation and vascular injury.

Design and methods: Nine to 12-week old male ieET-1 mice and control ieCre mice expressing a tamoxifen-inducible Cre recombinase under the control of endothelium-specific Tie2 promoter, were treated with tamoxifen (1 mg/kg/day, s.c.) for 5 days and studied 3 months later. ieET-1 mice were treated or not with ET A receptor blocker, atrasentan (10 mg/kg/day, PO) in the last 2 weeks of the study. BP by telemetry, endothelial function and vascular remodeling by pressurized myography and reactive oxygen species (ROS) generation using dihydroethidium staining in mesenteric artery (MA) or perivascular fat (PVAT) and renal artery flow (RAF) by ultrasonography were determined.

Results: Systolic BP was increased in ieET-1 and normalized by atrasentan compared to ieCre mice (141±0 and 124±4 vs 120±0 mm Hg, P <0.001). Endothelium-dependent relaxation responses to acetylcholine were impaired in ieET-1 and uncorrected by atrasentan compared to ieCre (35±4 and 32±4 vs 65±8%, P <0.01). Media/lumen and media cross-sectional area were unchanged, but stiffness was increased in ieET-1 and normalized by atrasentan compared to ieCre mice (strain at 140 mm Hg: 0.6±0.0 and 0.7±0.0 vs 0.7±0.0 ΔD/D, P <0.05). ROS generation was enhanced in PVAT of ieET-1 and normalized with atrasentan when compared to ieCre mice (1.4±0.1 and 0.9±0.1 and vs 1.0±0.1 relative fluorescence units/μm 2 , P <0.05). RAF was decreased in ieET-1 and unchanged by atrasentan compared with control (1.8±0.2 and 2.0±0.2 vs 3.0±0.3 mL/min, P <0.01).

Conclusions: Long-term exposure to endothelial human ET-1 overexpression caused sustained BP elevation, endothelial dysfunction and vascular stiffening and oxidative stress.

Aldosterone-Induced Vascular Remodeling and Endothelial Dysfunction Require Functional Angiotensin Type 1a Receptors

We investigated the role of angiotensin type 1a receptors (AGTR1a) in vascular injury induced by aldosterone activation of mineralocorticoid receptors in Agtr1a(-/-) and wild-type (WT) mice infused with aldosterone for 14 days while receiving 1% NaCl in drinking water. Aldosterone increased systolic blood pressure (BP) by ≈30 mm Hg in WT mice and ≈50 mm Hg in Agtr1a(-/-) mice. Aldosterone induced aortic and small artery remodeling, impaired endothelium-dependent relaxation in WT mice, and enhanced fibronectin and collagen deposition and vascular inflammation. None of these vascular effects were observed in Agtr1a(-/-) mice. Aldosterone effects were prevented by the AGTR1 antagonist losartan in WT mice. In contrast to aldosterone, norepinephrine caused similar BP increase and mesenteric artery remodeling in WT and Agtr1a(-/-) mice. Agtr1a(-/-) mice infused with aldosterone did not increase sodium excretion in response to a sodium chloride challenge, suggesting that sodium retention could contribute to the exaggerated BP rise induced by aldosterone. Agtr1a(-/-) mice had decreased mesenteric artery expression of the calcium-activated potassium channel Kcnmb1, which may enhance myogenic tone and together with sodium retention, exacerbate BP responses to aldosterone/salt in Agtr1a(-/-) mice. We conclude that although aldosterone activation of mineralocorticoid receptors raises BP more in Agtr1a(-/-) mice, AGTR1a is required for mineralocorticoid receptor stimulation to induce vascular remodeling and inflammation and endothelial dysfunction.

Abstract P601: Matrix Metalloproteinase 2 Plays An Important Role In Angiotensin Ii-induced Vascular Injury Mediated In Part Through Epidermal Growth Factor Receptor Activation In Vascular Smooth Muscle Cells

Background: Matrix metalloproteinase 2 (MMP2) is involved in cardiovascular disease. Whether MMP2 plays a role in hypertension and vascular damage is unknown. We hypothesized that Mmp2 knockout will prevent angiotensin (Ang) II-induced blood pressure (BP) rise and vascular injury.

Methods: Ten to 12-week-old male Mmp2 knockout (Mmp2-/-) and wild-type (WT) mice were infused with Ang II (1000 ng/kg/min, SC) for 14 days. Systolic BP was measured by telemetry, mesenteric arteries (MA) endothelial function and vascular remodeling by pressurized myography. In aortic wall or perivascular fat (PVAT), reactive oxygen species (ROS) generation was determined using dihydroethidium staining, and vascular cell adhesion protein 1 (VCAM-1), monocyte chemotactic protein-1 (MCP-1) expression and monocyte/macrophage infiltration by immunofluorescence. Spleen T cells and monocyte profile were assessed by flow cytometry. Vascular smooth muscle cells (VSMCs) were isolated from MA of WT and Mmp2 knockout mice, stimulated 5 min with 100 nM Ang II and epidermal growth factor receptor (EGFR) phosphorylation measured by Western-Blotting.

Results: Ang II increased Systolic BP (172±7 vs 122±3, P<0.01), decreased MA vasodilatory responses to acetylcholine (33±5% vs 83±3%, P<0.01) and increases MA media-to-lumen ratio (5±0% vs 3±0%, P<0.01), media cross-sectional area (7224±467 vs 5345±336 μm2, P<0.05), and stiffness (P<0.01), as shown by a leftward shift of the stress/strain relationship, in WT. Furthermore, Ang II enhanced aortic ROS generation (73±11 vs 6±1 RFU/μm2, P<0.01), aortic VCAM-1 (17±3 vs 5±3 RFU/μm2, P<0.01) and MCP-1 expression (71±14 vs 11±3 RFU/μm2, P<0.01) and PVAT monocyte/macrophage infiltration (32±5 vs 4±0 RFU/μm2, P<0.05), and spleen activated CD4+CD69+ and CD8+CD69+ T cells and pro-inflammatory Ly-6Chi monocytes (17±2 vs 10±1%, 11±1 vs 5±1% and 53±6 vs 25±2%, respectively, P<0.05) in WT. Ang II increased EGFR phosphorylation in VSMCs in vitro (1.91±0.19 vs 1.0±0.0%, P<0.05). Mmp2 knockout prevented or reduced all of the above except BP elevation (P<0.05).

Conclusion: MMP2 plays an important role in Ang II-induced vascular injury, which could be mediated at least in part through EFGR activation in VSMCs.

Abstract P034: Endothelin-1 Overexpression Exaggerates Diabetes-induced Endothelial Dysfunction by Altering Oxidative Stress Balance

Objective: Increased endothelin (ET)-1 expression has been shown to cause endothelial dysfunction.Plasma ET-1 is increased in patients with diabetes.Since endothelial dysfunction often precedes vascular complications in diabetes, we sought to determine whether ET-1 contributes to diabetes-induced endothelial dysfunction. We hypothesized that overexpression of ET-1 in the endotheliumwill exaggerate diabetes-induced endothelial dysfunction.

Method: Diabetes was induced by streptozotocin treatment (STZ, 55 mg/kg/day, ip) for 5 days in 6weekold male wild-type (WT) mice and in mice overexpressinghuman ET-1 restricted to the endothelium (eET-1). Mice were studied 14 weeks later. Blood glucose,plasma ET-1 levels, mesenteric artery (MA) reactivity, mitochondrial superoxide production in aorta and endothelial nitric oxide synthase (Nos3), superoxide dismutase 1 (Sod1) and 2 (Sod2) mRNA expression in MA were determined.

Results: STZ-induced diabetes was confirmed by increased glycemia in WT(27.6±1.5 vs 10.7±1.1 μM, P<0.001)and eET-1 (23.2±1.0 vs 8.4±0.3 μM, P<0.001).Plasma ET-1 was increased in vehicle- (15.9±4.6 vs 0.6±0.04pg/mL, P<0.05) and STZ-treatedeET-1 (4.9±0.6 vs 0.8±0.1 pg/mL, P<0.05) compared to respective WT controls.Diabetes caused a reduction in vasodilatory responses to acetylcholine in WT (60.9±6.4% vs 83.9±3.4%,P<0.05), which was exaggerated in eET-1(48.6±5.1% vs 81.5±5.2% P<0.05). Mitochondrial superoxide production was increased by diabetes in WT (38.0±4.3 vs 21.6±2.3 RFU/μm2,P<0.05)and further augmented in eET-1 (49.8±1.7 RFU/μm2P<0.05).Nos3 expression was increased in vehicle-treatedeET-1 compared to WT(1.43±0.19 vs 1.00±0.10, P<0.05).Diabetes reduced Nos3 expression in eET-1 (0.75±0.08, P<0.05) but not in WT(1.08±0.09).Diabetes caused an increase in Sod1(1.52±0.17 vs 1.00±0.03, P<0.05) and Sod2 (1.32±0.17 vs 1.00±0.02, P<0.05) expression in WT (P<0.05) but not in eET-1.

Conclusions: Increased levels of ET-1 exaggerate diabetes-induced endothelial dysfunction. This may be caused by a decrease in Nos3 expression, an increase in mitochondrial oxidative stress and a decrease in antioxidant capacity.

Abstract P625: Non-coding Rna Regulation Of Gene Expression In Angiotensin Ii-induced Vascular Damage

Introduction: Non-coding RNAs (ncRNAs), including long ncRNAs (lncRNAs) and microRNAs (miRs), account for ~98% of the transcribed RNAs. They have been shown to play a role in cardiovascular disease. Vascular damage is an early manifestation and a cause of end-organ damage in hypertension. However, it is unknown whether ncRNAs are involved in the development of vascular injury in hypertension. We hypothesize that ncRNA regulation participates in mechanisms of vascular remodeling and plays an important role in the pathophysiology of hypertension.

Methods and Results: Ten-week old male C57BL/6 mice were infused or not with angiotensin (Ang) II for 14 days. Systolic blood pressure (BP) determined by telemetry was increased by Ang II infusion compared to control (146±8 vs 113±5 mmHg, P<0.001). Total RNA was extracted from mesenteric arteries for total and small RNA deep sequencing using Illumina HiSeq-2500. Sequences were aligned to the mm10 genome with STAR, annotated and counted using HTSeq-count or miRDeep2. Differential expression analysis was done in R. Differentially expressed (DE) mRNAs (550 up & 266 down), lncRNAs (7 up & 42 down), miRs (23 up & 12 down) were identified in the Ang II-treated group (1.5 fold change, q<0.05). Targetscan was used to predict interactions between DE miRs and the inversely correlated DE mRNAs or DE lncRNAs. MEME Suite was used to predict DE transcription factor binding sites in the promoter region of genes encoding DE mRNAs, lncRNAs and miRs. Cytoscape was used to construct molecular networks integrating the above interactions and the gene expression profile and to perform functional enrichment analysis, which revealed enrichment of extracellular matrix and developmental processes in DE miR-targeting DE mRNAs (q<1E-20). Ten DE miRNAs whose expression levels correlated (P<0.05) with BP were identified, 9 of which are located in a single miRNA cluster that is conserved in humans.

Conclusions: We have identified a conserved miRNA cluster that may play a pivotal role in the regulation of vascular damage in hypertension. A sub-network of genes that participates in the interaction between the miRNA cluster and other BP-correlated RNAs was selected for future investigation to identify therapeutic targets.

Abstract P617: Angiotensin II-induced Hypertension And Vascular Injury Is Mediated By Gamma/delta T Cells

Objective: Both innate antigen presenting cells and the adaptive immune system have been shown to play a role in the development of hypertension. Nevertheless, the T cell subset involved in the pathophysiology of hypertension remains unclear. There is a small subset of “innate-like” T cells expressing gamma/delta T cell receptor (TCR) rather than the alpha/beta TCR that could play a role in bridging between the innate and adaptive immune systems. However, it is unknown whether gamma/delta T cells contribute to development of hypertension.

Method/Results: Thirteen to 15 week-old male C57BL/6 wild-type and Tcrd-/- mice, which are devoid of gamma/delta T cells, were infused or not with angiotensin (Ang) II (490 ng/kg/min, SC) for 7 or 14 days (n=4-9). Telemetric blood pressure, mesenteric artery endothelial function and vascular remodeling by pressurized myography and spleen T cell profile by flow cytometry were evaluated. Fourteen days of Ang II increased systolic blood pressure (167±4 vs 125±2 mmHg, P≤0.01) in wild-type compared to control mice. The frequency of gamma/delta T cells (6±1% vs 3±1%, P≤0.05) and activated (CD69+) gamma/delta T cells (11±1% vs 7±1%) was increased after 7 days of Ang II, and 7 days later were respectively unchanged or further increased (24±2% vs 10±1%) in wild-type compared to control mice. Ang II decreased mesenteric artery relaxation responses to acetylcholine (51±5% vs 88±3%, P≤0.01) and increased media/lumen (5±1 vs 3±0%, P≤0.01) in wild-type mice compare to controls. No gamma/delta T cells were detected in Tcrd-/- treated or not with Ang II. All the above Ang II effects were abrogated in Tcrd-/- mice.

Conclusion: These data suggest that gamma/delta T cells mediate Ang II-induced blood pressure rise and vascular injury. Gamma/delta T cells could be key immune cells bridging innate and adaptive immune responses during the development of hypertension.

Abstract P035: Endothelin-1 Overexpression Preserves Endothelial Function in Mice with Vascular Smooth Muscle Cell-specific Deletion of Ppar-gamma

Objective: Peroxisome proliferator-activated receptor γ (PPARγ) agonists reduce blood pressure (BP) and vascular injury in hypertensive rodents and humans. Pparγ inactivation in vascular smooth muscle cells (VSMC)using a tamoxifen inducible Cre-Lox system enhanced angiotensin II-induced vascular injury. Transgenic mice overexpressing endothelin (ET)-1selectively in the endothelium (eET-1) exhibit endothelial dysfunction, increased oxidative stress and inflammation. We hypothesized that inactivation of Pparγ in VSMC(smPparγ-/-)will exaggerate ET-1-induced vascular damage.

Methods and Results: Elevenweek-old male control, eET-1, smPparγ-/-and eET-1/smPparγ-/- mice weretreated with tamoxifen (1 mg/kg/day, s.c.) for 5 days and sacrificed 4 weeks later. Systolic BP was higher in eET-1compared to control (123±5 vs 109±2 mmHg,P<0.05)and unaffected by Pparγ inactivation.Mesenteric artery (MA) vasodilatory responses to acetylcholine were impaired only in smPparγ-/- (P<0.05) compared to control (Emax: 52.0±6.7% vs 82.2±4.9%).Reactive oxygen species levels were increased in eET-1, smPparγ-/-and eET-1/smPparγ-/-compared to control (1.7±0.2, 2.2±0.2 and 2.8±0.4 vs 1.0±0.2, P<0.05).MA monocyte chemoattractant protein-1 expression was higher in smPparγ-/-compared to control (31.0±4.4 vs 18.7±2.5, P<0.05), and unaffected by ET-1 overexpression.Perivascular fat monocyte/macrophage infiltration was higher in eET-1 and smPparγ-/- compared to control (331±34 and 326±49 vs 140±8 cells/mm2, P<0.05), and further increased in eET-1/smPparγ-/- (557±77, P<0.05). Nitric oxide synthase (Nos)3 mRNA expression was increased only in eET-1 compared to WT (1.21±0.07 vs 1.00±0.02, P<0.05). Nos2 expression was increased in eET-1 and smPparγ-/-compared to WT (3.69±0.72 and 1.96±0.16 vs 1.00±0.13, P<0.05). The Ednra/EdnrbmRNA ratio was decreased in eET-1/smPparγ-/- compared to smPparγ-/-(0.76±0.04 vs 1.07±0.10, P<0.05).

Conclusion: Increased ET-1 paradoxically preserves endothelial function in mice with smPparγinactivation, despite enhancedoxidative stress and inflammation.

Abstract 098: Foxp3+ T Regulatory Lymphocytes Counteract Angiotensin Ii-induced Vascular Injury

Objective: T effector lymphocytes contribute to vascular injury in angiotensin (Ang) II-induced hypertension, but the role of T regulatory lymphocytes (Tregs) is unclear. Ang II-induced hypertension is blunted in T and B lymphocyte-deficient (Rag1-/-) mice, and restored with reconstitution of T cells. We hypothesized that adoptive transfer of FOXP3-deficient Scurfy (Sf) vs. wild-type (WT) T cells will exacerbate Ang II-induced vascular damage in Rag1-/- mice.

Methods: Eleven-week old male Rag1-/- mice were injected IV with vehicle, 10 million WT or Sf T cells, 1 million CD4+CD25+ Tregs alone or with Sf T cells, and 2 weeks later were infused or not with Ang II (490 ng/kg/min, SC) for 14 days (n=3-8). Telemetric BP, vascular function and structure, and reactive oxygen species (ROS) production and fibronectin expression in mesenteric arteries (MA) were determined.

Results: Ang II induced a 40 mmHg systolic BP rise in all the groups, but diastolic BP rise was ~10 mmHg greater in WT and Sf T cell-injected mice than in controls (P<0.01). Treg injection alone or with Sf T cells prevented or delayed by 7 days the BP rise, respectively (P<0.05). Ang II did not induce endothelial dysfunction in vehicle or Treg only-injected mice. Adoptive transfer of WT T cells restored Ang II induced-endothelial dysfunction (60±5% vs. 83±4%, P<0.05), which was exaggerated in Sf T cell-injected mice (56±6% vs. 97±7%, P<0.01), but reduced by Treg co-injection (74±4%, P<0.05). Ang II increased ROS production in MA wall (239±32% vs. 119±20%) and perivascular fat (369±39% vs. 84±8%) in Sf T cell-injected mice (P<0.01), but not when co-injected with Tregs. Ang II induced increased vascular stiffness (P<0.01) and media/lumen (M/L, P<0.05) in vehicle (strain at 140 mmHg: 0.60±0.02 vs. 0.80±0.02; M/L: 4.1±0.2 vs. 2.9±0.2%) and Sf T cell-injected mice (strain at 140 mmHg: 0.63±0.01 vs. 0.89±0.04; M/L: 4.7±0.3 vs. 2.9±0.1%). Ang II increased MA fibronectin expression (P<0.01) in vehicle (113±12 vs. 51±14 RFU/μm2) and Sf T cell-injected mice (85±7 vs. 36±9 RFU/μm2).

Conclusion: These results demonstrate that Foxp3+ Tregs have a protective role against Ang II-induced vascular dysfunction, remodeling and oxidative stress.

Abstract 343: Endothelin-1 Overexpression Preserves Endothelial Function In Mice With Vascular Smooth Muscle Cell-specific Deletion Of Ppar-gamma

Objective: Peroxisome proliferator activated receptor γ (PPARγ) agonists reduce blood pressure (BP) and vascular injury in hypertensive rodents and humans. Pparγ inactivation in vascular smooth muscle cells (VSMC) using a tamoxifen inducible Cre-Lox system enhanced angiotensin II-induced vascular remodeling and endothelial dysfunction. Transgenic mice overexpressing endothelin (ET)-1 selectively in the endothelium (eET-1) exhibit endothelial dysfunction, increased oxidative stress and inflammation. We hypothesized that inactivation of the Ppar gene in VSMC (sm Pparγ -/- ) will exaggerate ET-1-induced vascular damage.

Methods: Eleven week-old male control, eET-1, sm Pparγ -/- and eET-1/sm Pparγ -/- mice were used. BP by telemetry, mesenteric artery (MA) reactivity and structure by pressurized myography, reactive oxygen species (ROS) by dihydroethidium (DHE) staining and fibronectin expression by immunofluorescence were determined.

Results: Systolic BP was higher in eET-1 and eET-1/sm Pparγ -/- compared to control and sm Pparγ -/- (127±3 and 124±7 vs 109±2 and 114 ± 4 mmHg, respectively, P <0.05). Endothelium-dependent relaxation (EDR) responses to acetylcholine were impaired in sm Pparγ -/- ( P <0.05) but not in eET-1 and sm Pparγ -/- /eET-1 compared with control (E max : 52.0±6.7%, 66.2±7.6 and 87.1±4.4% vs 82.2±4.9%). Endothelium-independent relaxation responses to the nitric oxide donor, sodium nitroprusside, were similar in the four groups. Media/lumen at 45 mmHg was higher only in eET-1/sm Pparγ -/- compared with control (5.5±0.21 vs 4.5±0.21, P <0.05). Increased stiffness was observed in eET-1, sm Pparγ -/- and eET-1/sm Pparγ -/- compared to control, as indicated by a leftward displacement of the stress-strain curves (strain at 140 mmHg: 0.82±0.03, 0.81±0.04, 0.80±0.03 vs 0.97±0.02, P <0.05). ROS levels were increased 1.7±0.2 fold in eET-1, 2.2±0.2 fold in sm Pparγ -/- and 2.8±0.4 fold in eET-1/sm Pparγ -/- compared with control ( P <0.05). Fibronectin staining in MA was similar in the four groups.

Conclusion: These results suggest that increased ET-1 paradoxically preserves endothelial function in mice with inactivated Pparγ in vascular smooth muscle, despite presence of enhanced oxidative stress.

Abstract 346: Subcutaneous Resistance Artery Remodeling And Function In Chronic Kidney Disease Patients

Background: Chronic kidney disease (CKD) is associated with cardiovascular (CV) complications. However, interventional trials targeting classical CV risks factors have been often unsuccessful in advanced stage CKD, which emphasizes the need to better understand CKD-associated vascular disorders. Resistance arteries are a key determinant of blood pressure (BP) and their changes in different CV conditions contribute to target organ damage. The aim of the present study was to characterize resistance artery remodeling and function in CKD patients, compared to vessels from hypertensive (HTN) subjects.

Method: Twenty-two stage 4 CKD patients (aged 63.6±3.1 years) and 16 HTN subjects (45.6±16.1 years) were included in the present study. They all underwent a subcutaneous biopsy under local anaesthesia. Small artery remodeling and function were studied on a pressurized myograph, and subcutaneous fat CD3 infiltration and media fibronectin expression by immunostaining. Vascular smooth muscle cells (VSMCs) were counted after hematoxilin-eosin staining.

Results: CKD systolic BP was similar to HTN (133±18 vs. 143±10 mmHg, respectively). Vasodilatory responses to acetylcholine were lower in CKD compared to HTN (maximal relaxation (%), 74.3±3.4 vs. 87.5±2.7, P<0.05). Media/lumen at 60 mmHg was lower in CKD than in HTN (6.7±0.5 vs 8.8±0.7, P<0.05). Resistance artery stiffness was lower in CKD compared to HTN (strain at 120 mmHg, 0.845±0.126 vs 0.585±0.099, P<0.05). Fibronectin staining in resistance arteries was lower in CKD than HTN (8.2±0.8 vs 23.3±1.7 RFU/μm2, P<0.001). Less VSMCs were present in the arterial wall of CKD compared to HTN (5.4±0.4 vs 7.2±0.5 cells/μm2, P<0.05). Subcutaneous fat presented fewer CD3+ cells in CKD than HTN (12.8±4.1 vs 23.7±12.8 cells/mm2, P<0.05).

Conclusion: Despite higher levels of BP, resistance arteries isolated from CKD patients exhibited no vascular remodeling and lower arterial stiffness compared with HTN patients. These results are in line with the maladaptive hypotrophic remodeling observed in large vessels in CKD, suggesting a generalized vascular defect in mechanotransduction in CKD.

Abstract 345: Role Of Vascular Smooth Muscle Cell PPARγ In Aldosterone-induced Vascular Injury

Background: Peroxisome proliferator activated receptor γ (PPARγ) agonists improve vascular remodeling and endothelial dysfunction in hypertensive rodents and humans. PPARγ activation in vascular smooth muscle cells (VSMC) may be responsible for the vascular protective effects of PPARγ agonists. We previously observed a protective role of VSMC PPARγ in angiotensin II-induced endothelial dysfunction and vascular remodeling. However, it is unknown whether VSMC PPAR plays a similar protective role in adverse vascular effects of aldosterone. We hypothesized that inactivation of the Ppar gene in VSMC (sm Pparγ -/- ) would exaggerate aldosterone-induced vascular injury.

Methods: Using a tamoxifen-inducible Cre/loxP system, Pparγ was ablated in VSMC of adult mice. Thirteen week-old control and sm Pparγ -/- mice were infused or not with aldosterone (400 μg/kg/d, SC) for 14 days while receiving 1% NaCl/0.3% KCl in drinking water. Endothelial function and vascular remodeling were assessed in mesenteric arteries (MA) by pressurized myography.

Results: Endothelium-dependent relaxation (EDR) responses to acetylcholine were reduced to a similar extent in sm Pparγ -/- and aldosterone-treated control and sm Pparγ -/- mice compared to control mice (E max : 62.5±8.7%, 50.8±8.6% and 56.8±7.9%, respectively, vs 86.4±3.2%, P <0.05). L-NAME, an inhibitor of nitric oxide (NO) synthase, completely blocked EDR in the four groups. Endothelium-independent relaxation response to the NO donor sodium nitroprusside and contractile responses to norepinephrine were similar in the four groups. Preliminary data indicated that aldosterone tended to increase MA stiffness in control mice, as shown by a leftward shift of the stress/strain relationship curve (strain at 140 mmHg, 0.79±0.07 vs 0.89±0.03). Furthermore, Pparγ deletion induced an increase in MA stiffness compared to control, which was not worsened by aldosterone (strain at 140 mmHg, 0.67±0.01, 0.65±0.03, vs 0.89±0.03).

Conclusion: These results indicate that either VMSC Pparγ inactivation or aldosterone treatment induce vascular remodeling and endothelial dysfunction, which are not mutually exaggerated. This suggests that PPARγ and aldosterone signal intracellularly through different pathways.

Abstract 344: Endothelin-1 Overexpression Exaggerates Diabetes-induced Endothelial Dysfunction

Objective: Vascular disease associated with endothelial dysfunction is a major cause of morbidity in patients with type-1 diabetes. Endothelin (ET)-1 plays a role in diabetes-induced vascular complications, since ET-1 type A receptor blockade reduces diabetes-induced vascular injury. However, whether ET-1 contributes to diabetes-induced endothelial dysfunction remains unproven. We hypothesized that vascular ET-1 overexpression will exaggerate diabetes-induced endothelial dysfunction.

Methods: Diabetes was induced by streptozotocin treatment (STZ, 55 mg/kg/day, ip) for 5 days in 6-week-old male wild-type (WT) mice and in mice overexpressing ET-1 restricted to the endothelium (eET-1). Mice were studied 14 weeks later. Blood was collected to determine glucose. Mesenteric artery reactivity and remodeling were evaluated using pressurized myography and aortic fibronectin expression by immnunofluorescence.

Results: STZ-induced diabetes was confirmed by a 3-fold increase in glycemia in WT and eET-1 ( P <0.001). Diabetes impaired endothelium-dependent relaxation (EDR) reponses to acetylcholine in WT (60.9±6.4% vs 83.9±3.4%, P <0.05) and eET-1 (48.6±5.1% vs 81.5±5.2%, P <0.001). EDR impairment was exaggerated in eET-1 compared to WT ( P <0.05). Meclofenamic acid, an inhibitor of cyclooxygenase, increased EDR in eET-1 compared to WT (78.4±9.4% vs 66.7±3.2%, P <0.01), which was not observed in diabetic mice. L-NAME, an inhibitor of nitric oxide (NO) synthase, completely blocked EDR in WT, eET-1 and diabetic WT, but not in diabetic eET-1 (4.1±1.6%, 6.4±5.7%, 2.2±4.6% and 26.6±4.6%, P <0.05). Apamin plus Tram34, inhibitors of endothelium-dependent hyperpolarization inhibited EDR in the four groups. Endothelium-independent relaxation to sodium nitroprusside, a NO donor, was similar in the four groups. Diabetes reduced media/lumen in WT (2.7±0.3 vs 3.6±0.3, P <0.05) and eET-1 (2.9±0.2 vs 3.8±0.3, P <0.05). Diabetes decreased aortic fibronectin expression in WT (94.0±11.0 vs. 151.9±21.8 RFU/μm 2 , P <0.05) and eET-1 (66.3±8.7 vs. 146.6±20.7 RFU/μm 2 , P <0.05).

Conclusion: ET-1 contributes to alterations in several pathways mediating endothelium-dependent relaxation in type-1 diabetes, leading to exaggerated endothelial dysfunction.