Publications by authors named "Adam C Straub"

64 Publications

A primer for measuring cGMP signaling and cGMP-mediated vascular relaxation.

Nitric Oxide 2021 Sep 30;117:40-45. Epub 2021 Sep 30.

Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, 185 South Orange Ave., MSBI655, 07103, Newark, NJ, USA. Electronic address:

Soluble guanylyl cyclase (sGC, also called GC1) is the main receptor for nitric oxide (NO) that catalyzes the production of the second messenger molecule, 3'5' cyclic guanosine monophosphate (cGMP) leading to vasorelaxation, and inhibition of leukocyte recruitment and platelet aggregation. Enhancing cGMP levels, through sGC agonism or inhibition of cGMP breakdown via phosphodiesterase inhibition, has yielded FDA approval for several cGMP modifier therapies for treatment of cardiovascular and pulmonary diseases. While basic research continues to improve our understanding of cGMP signaling and as new therapies evolve to elevate cGMP levels, we provide a short methodological primer for measuring cGMP and cGMP-mediated vascular relaxation for investigators.
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http://dx.doi.org/10.1016/j.niox.2021.09.008DOI Listing
September 2021

H3K4 di-methylation governs smooth muscle lineage identity and promotes vascular homeostasis by restraining plasticity.

Dev Cell 2021 Oct 27;56(19):2765-2782.e10. Epub 2021 Sep 27.

Pittsburgh Heart, Lung, Blood, and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA; Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address:

Epigenetic mechanisms contribute to the regulation of cell differentiation and function. Vascular smooth muscle cells (SMCs) are specialized contractile cells that retain phenotypic plasticity even after differentiation. Here, by performing selective demethylation of histone H3 lysine 4 di-methylation (H3K4me2) at SMC-specific genes, we uncovered that H3K4me2 governs SMC lineage identity. Removal of H3K4me2 via selective editing in cultured vascular SMCs and in murine arterial vasculature led to loss of differentiation and reduced contractility due to impaired recruitment of the DNA methylcytosine dioxygenase TET2. H3K4me2 editing altered SMC adaptative capacities during vascular remodeling due to loss of miR-145 expression. Finally, H3K4me2 editing induced a profound alteration of SMC lineage identity by redistributing H3K4me2 toward genes associated with stemness and developmental programs, thus exacerbating plasticity. Our studies identify the H3K4me2-TET2-miR145 axis as a central epigenetic memory mechanism controlling cell identity and function, whose alteration could contribute to various pathophysiological processes.
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http://dx.doi.org/10.1016/j.devcel.2021.09.001DOI Listing
October 2021

Smooth muscle cell CYB5R3 preserves cardiac and vascular function under chronic hypoxic stress.

J Mol Cell Cardiol 2021 Sep 15;162:72-80. Epub 2021 Sep 15.

Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, United States of America; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, United States of America; Center for Microvascular Research, University of Pittsburgh, Pittsburgh, PA, United States of America. Electronic address:

Chronic hypoxia is a major driver of cardiovascular complications, including heart failure. The nitric oxide (NO) - soluble guanylyl cyclase (sGC) - cyclic guanosine monophosphate (cGMP) pathway is integral to vascular tone maintenance. Specifically, NO binds its receptor sGC within vascular smooth muscle cells (SMC) in its reduced heme (Fe) form to increase intracellular cGMP production, activate protein kinase G (PKG) signaling, and induce vessel relaxation. Under chronic hypoxia, oxidative stress drives oxidation of sGC heme (Fe→Fe), rendering it NO-insensitive. We previously showed that cytochrome b5 reductase 3 (CYB5R3) in SMC is a sGC reductase important for maintaining NO-dependent vasodilation and conferring resilience to systemic hypertension and sickle cell disease-associated pulmonary hypertension. To test whether CYB5R3 may be protective in the context of chronic hypoxia, we subjected SMC-specific CYB5R3 knockout mice (SMC CYB5R3 KO) to 3 weeks hypoxia and assessed vascular and cardiac function using echocardiography, pressure volume loops and wire myography. Hypoxic stress caused 1) biventricular hypertrophy in both WT and SMC CYB5R3 KO, but to a larger degree in KO mice, 2) blunted vasodilation to NO-dependent activation of sGC in coronary and pulmonary arteries of KO mice, and 3) decreased, albeit still normal, cardiac function in KO mice. Overall, these data indicate that SMC CYB5R3 deficiency potentiates bilateral ventricular hypertrophy and blunts NO-dependent vasodilation under chronic hypoxia conditions. This implicates that SMC CYB5R3 KO mice post 3-week hypoxia have early stages of cardiac remodeling and functional changes that could foretell significantly impaired cardiac function with longer exposure to hypoxia.
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http://dx.doi.org/10.1016/j.yjmcc.2021.09.005DOI Listing
September 2021

Redox Switches Controlling Nitric Oxide Signaling in the Resistance Vasculature and Implications for Blood Pressure Regulation: Mid-Career Award for Research Excellence 2020.

Hypertension 2021 Sep 23;78(4):912-926. Epub 2021 Aug 23.

Heart, Lung, Blood and Vascular Medicine Institute (A.A.M.D.-O., J.C.G., S.Y., H.M.S., K.C.W., A.C.S.), University of Pittsburgh, PA.

The arterial resistance vasculature modulates blood pressure and flow to match oxygen delivery to tissue metabolic demand. As such, resistance arteries and arterioles have evolved a series of highly orchestrated cell-cell communication mechanisms between endothelial cells and vascular smooth muscle cells to regulate vascular tone. In response to neurohormonal agonists, release of several intracellular molecules, including nitric oxide, evokes changes in vascular tone. We and others have uncovered novel redox switches in the walls of resistance arteries that govern nitric oxide compartmentalization and diffusion. In this review, we discuss our current understanding of redox switches controlling nitric oxide signaling in endothelial and vascular smooth muscle cells, focusing on new mechanistic insights, physiological and pathophysiological implications, and advances in therapeutic strategies for hypertension and other diseases.
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http://dx.doi.org/10.1161/HYPERTENSIONAHA.121.16493DOI Listing
September 2021

Notch2 suppression mimicking changes in human pulmonary hypertension modulates Notch1 and promotes endothelial cell proliferation.

Am J Physiol Heart Circ Physiol 2021 09 23;321(3):H542-H557. Epub 2021 Jul 23.

Heart, Lung, Blood, and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania.

Pulmonary arterial hypertension (PAH) is a fatal cardiopulmonary disease characterized by increased vascular cell proliferation with apoptosis resistance and occlusive remodeling of the small pulmonary arteries. The Notch family of proteins subserves proximal signaling of an evolutionarily conserved pathway that effects cell proliferation, fate determination, and development. In endothelial cells (ECs), Notch receptor 2 (Notch2) was shown to promote endothelial apoptosis. However, a pro- or antiproliferative role for Notch2 in pulmonary endothelial proliferation and ensuing PAH is unknown. We postulated that suppressed Notch2 signaling drives pulmonary endothelial proliferation in the context of PAH. We observed that levels of Notch2 are ablated in lungs from PAH subjects compared with non-PAH controls. Notch2 expression was attenuated in human pulmonary artery endothelial cells (hPAECs) exposed to vasoactive stimuli including hypoxia, TGF-β, ET-1, and IGF-1. Notch2-deficient hPAECs activated Akt, Erk1/2, and antiapoptotic protein Bcl-2 and reduced levels of p21 and Bax associated with increased EC proliferation and reduced apoptosis. In addition, Notch2 suppression elicited a paradoxical activation of Notch1 and canonical Notch target gene Hes1, Hey1, and Hey2 transcription. Furthermore, reduction in Rb and increased E2F1 binding to the Notch1 promoter appear to explain the Notch1 upregulation. Yet, when Notch1 was decreased in Notch2-suppressed cells, the wound injury response was augmented. In aggregate, our results demonstrate that loss of Notch2 in hPAECs derepresses Notch1 and elicits EC hallmarks of PAH. Augmented EC proliferation upon Notch1 knockdown points to a context-dependent role for Notch1 and 2 in endothelial cell homeostasis. This study demonstrates a previously unidentified role for Notch2 in the maintenance of lung vascular endothelial cell quiescence and pulmonary artery hypertension (PAH). A key novel finding is that Notch2 suppression activates Notch1 via Rb-E2F1-mediated signaling and induces proliferation and apoptosis resistance in human pulmonary artery endothelial cells. Notably, PAH patients show reduced levels of endothelial Notch2 in their pulmonary arteries, supporting Notch2 as a fundamental driver of PAH pathogenesis.
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http://dx.doi.org/10.1152/ajpheart.00125.2021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8461839PMC
September 2021

Human and rodent red blood cells do not demonstrate xanthine oxidase activity or XO-catalyzed nitrite reduction to NO.

Free Radic Biol Med 2021 10 15;174:84-88. Epub 2021 Jul 15.

West Virginia University Departments of Physiology and Pharmacology, USA. Electronic address:

A number of molybdopterin enzymes, including xanthine oxidoreductase (XOR), aldehyde oxidase (AO), sulfite oxidase (SO), and mitochondrial amidoxime reducing component (mARC), have been identified as nitrate and nitrite reductases. Of these enzymes, XOR has been the most extensively studied and reported to be a substantive source of nitric oxide (NO) under inflammatory/hypoxic conditions that limit the catalytic activity of the canonical NOS pathway. It has also been postulated that XOR nitrite reductase activity extends to red blood cell (RBCs) membranes where it has been immunohistochemically identified. These findings, when combined with countervailing reports of XOR activity in RBCs, incentivized our current study to critically evaluate XOR protein abundance/enzymatic activity in/on RBCs from human, mouse, and rat sources. Using various protein concentrations of RBC homogenates for both human and rodent samples, neither XOR protein nor enzymatic activity (xanthine → uric acid) was detectable. In addition, potential loading of RBC-associated glycosaminoglycans (GAGs) by exposing RBC preparations to purified XO before washing did not solicit detectable enzymatic activity (xanthine → uric acid) or alter NO generation profiles. To ensure these observations extended to absence of XOR-mediated contributions to overall RBC-associated nitrite reduction, we examined the nitrite reductase activity of washed and lysed RBC preparations via enhanced chemiluminescence in the presence or absence of the XOR-specific inhibitor febuxostat (Uloric®). Neither addition of inhibitor nor the presence of the XOR substrate xanthine significantly altered the rates of nitrite reduction to NO by RBC preparations from either human or rodent sources confirming the absence of XO enzymatic activity. Furthermore, examination of the influence of the age (young cells vs. old cells) of human RBCs on XO activity also failed to demonstrate detectable XO protein. Combined, these data suggest: 1) that XO does not contribute to nitrite reduction in/on human and rodent erythrocytes, 2) care should be taken to validate immuno-detectable XO by demonstrating enzymatic activity, and 3) XO does not associate with human erythrocytic glycosaminoglycans or participate in nonspecific binding.
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http://dx.doi.org/10.1016/j.freeradbiomed.2021.07.012DOI Listing
October 2021

Metabolic Syndrome Mediates ROS-miR-193b-NFYA-Dependent Downregulation of Soluble Guanylate Cyclase and Contributes to Exercise-Induced Pulmonary Hypertension in Heart Failure With Preserved Ejection Fraction.

Circulation 2021 Aug 23;144(8):615-637. Epub 2021 Jun 23.

Pittsburgh Heart, Lung and Blood Vascular Medicine Institute (T.S., L.W., C.E.-D., S.A.H., E.R.R., M.R.D., J.J.B., Y.T., M.R., S.S., C.S.H., D.G., D.A.G., E.A.G., S.Y.C., A.C.S., C.F.M., M.T.G.), University of Pittsburgh School of Medicine, PA.

Background: Many patients with heart failure with preserved ejection fraction have metabolic syndrome and develop exercise-induced pulmonary hypertension (EIPH). Increases in pulmonary vascular resistance in patients with heart failure with preserved ejection fraction portend a poor prognosis; this phenotype is referred to as combined precapillary and postcapillary pulmonary hypertension (CpcPH). Therapeutic trials for EIPH and CpcPH have been disappointing, suggesting the need for strategies that target upstream mechanisms of disease. This work reports novel rat EIPH models and mechanisms of pulmonary vascular dysfunction centered around the transcriptional repression of the soluble guanylate cyclase (sGC) enzyme in pulmonary artery (PA) smooth muscle cells.

Methods: We used obese ZSF-1 leptin-receptor knockout rats (heart failure with preserved ejection fraction model), obese ZSF-1 rats treated with SU5416 to stimulate resting pulmonary hypertension (obese+sugen, CpcPH model), and lean ZSF-1 rats (controls). Right and left ventricular hemodynamics were evaluated using implanted catheters during treadmill exercise. PA function was evaluated with magnetic resonance imaging and myography. Overexpression of nuclear factor Y α subunit (NFYA), a transcriptional enhancer of sGC β1 subunit (sGCβ1), was performed by PA delivery of adeno-associated virus 6. Treatment groups received the SGLT2 inhibitor empagliflozin in drinking water. PA smooth muscle cells from rats and humans were cultured with palmitic acid, glucose, and insulin to induce metabolic stress.

Results: Obese rats showed normal resting right ventricular systolic pressures, which significantly increased during exercise, modeling EIPH. Obese+sugen rats showed anatomic PA remodeling and developed elevated right ventricular systolic pressure at rest, which was exacerbated with exercise, modeling CpcPH. Myography and magnetic resonance imaging during dobutamine challenge revealed PA functional impairment of both obese groups. PAs of obese rats produced reactive oxygen species and decreased sGCβ1 expression. Mechanistically, cultured PA smooth muscle cells from obese rats and humans with diabetes or treated with palmitic acid, glucose, and insulin showed increased mitochondrial reactive oxygen species, which enhanced miR-193b-dependent RNA degradation of nuclear factor Y α subunit (NFYA), resulting in decreased sGCβ1-cGMP signaling. Forced NYFA expression by adeno-associated virus 6 delivery increased sGCβ1 levels and improved exercise pulmonary hypertension in obese+sugen rats. Treatment of obese+sugen rats with empagliflozin improved metabolic syndrome, reduced mitochondrial reactive oxygen species and miR-193b levels, restored NFYA/sGC activity, and prevented EIPH.

Conclusions: In heart failure with preserved ejection fraction and CpcPH models, metabolic syndrome contributes to pulmonary vascular dysfunction and EIPH through enhanced reactive oxygen species and miR-193b expression, which downregulates NFYA-dependent sGCβ1 expression. Adeno-associated virus-mediated NFYA overexpression and SGLT2 inhibition restore NFYA-sGCβ1-cGMP signaling and ameliorate EIPH.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.121.053889DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8384699PMC
August 2021

Angiotensin II augments renal vascular smooth muscle soluble GC expression via an AT receptor-forkhead box subclass O transcription factor signalling axis.

Br J Pharmacol 2021 May 7. Epub 2021 May 7.

Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.

Background And Purpose: Reduced renal blood flow triggers activation of the renin-angiotensin-aldosterone system (RAAS) leading to renovascular hypertension. Renal vascular smooth muscle expression of the NO receptor, soluble GC (sGC), modulates the vasodilator response needed to control renal vascular tone and blood flow. Here, we tested if angiotensin II (Ang II) affects sGC expression via an AT receptor-forkhead box subclass O (FoxO) transcription factor dependent mechanism.

Experimental Approach: Using a murine two-kidney-one-clip (2K1C) renovascular hypertension model, we measured renal artery vasodilatory function and sGC expression. Additionally, we conducted cell culture studies using rat renal pre-glomerular smooth muscle cells (RPGSMCs) to test the in vitro mechanistic effects of Ang II treatment on sGC expression and downstream function.

Key Results: Contralateral, unclipped renal arteries in 2K1C mice showed increased NO-dependent vasorelaxation compared to sham control mice. Immunofluorescence studies revealed increased sGC protein expression in 2K1C contralateral renal arteries over sham controls. RPGSMCs treated with Ang II caused a significant up-regulation of sGC mRNA and protein expression as well as downstream sGC-dependent signalling. Ang II signalling effects on sGC expression occurred through an AT receptor and FoxO transcription factor-dependent mechanism at both the mRNA and protein expression levels.

Conclusion And Implications: Renal artery smooth muscle, in vivo and in vitro, up-regulates expression of sGC following RAAS activity. In both cases, up-regulation of sGC leads to increased downstream cGMP signalling, suggesting a previously unrecognized protective mechanism to improve renal blood flow in the uninjured contralateral renal artery.
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http://dx.doi.org/10.1111/bph.15522DOI Listing
May 2021

CoenzymeQ in cellular redox regulation and clinical heart failure.

Free Radic Biol Med 2021 05 20;167:321-334. Epub 2021 Mar 20.

Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address:

Coenzyme Q (CoQ) is ubiquitously embedded in lipid bilayers of various cellular organelles. As a redox cycler, CoQ shuttles electrons between mitochondrial complexes and extramitochondrial reductases and oxidases. In this way, CoQ is crucial for maintaining the mitochondrial function, ATP synthesis, and redox homeostasis. Cardiomyocytes have a high metabolic rate and rely heavily on mitochondria to provide energy. CoQ levels, in both plasma and the heart, correlate with heart failure in patients, indicating that CoQ is critical for cardiac function. Moreover, CoQ supplementation in clinics showed promising results for treating heart failure. This review provides a comprehensive view of CoQ metabolism and its interaction with redox enzymes and reactive species. We summarize the clinical trials and applications of CoQ in heart failure and discuss the caveats and future directions to improve CoQ therapeutics.
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http://dx.doi.org/10.1016/j.freeradbiomed.2021.03.011DOI Listing
May 2021

Xanthine Oxidase Drives Hemolysis and Vascular Malfunction in Sickle Cell Disease.

Arterioscler Thromb Vasc Biol 2021 02 3;41(2):769-782. Epub 2020 Dec 3.

Department of Pharmacology and Chemical Biology (H.M.S., D.A.V., A.C.S.), University of Pittsburgh, PA.

Objective: Chronic hemolysis is a hallmark of sickle cell disease (SCD) and a driver of vasculopathy; however, the mechanisms contributing to hemolysis remain incompletely understood. Although XO (xanthine oxidase) activity has been shown to be elevated in SCD, its role remains unknown. XO binds endothelium and generates oxidants as a byproduct of hypoxanthine and xanthine catabolism. We hypothesized that XO inhibition decreases oxidant production leading to less hemolysis. Approach and Results: Wild-type mice were bone marrow transplanted with control (AA) or sickle (SS) Townes bone marrow. After 12 weeks, mice were treated with 10 mg/kg per day of febuxostat (Uloric), Food and Drug Administration-approved XO inhibitor, for 10 weeks. Hematologic analysis demonstrated increased hematocrit, cellular hemoglobin, and red blood cells, with no change in reticulocyte percentage. Significant decreases in cell-free hemoglobin and increases in haptoglobin suggest XO inhibition decreased hemolysis. Myographic studies demonstrated improved pulmonary vascular dilation and blunted constriction, indicating improved pulmonary vasoreactivity, whereas pulmonary pressure and cardiac function were unaffected. The role of hepatic XO in SCD was evaluated by bone marrow transplanting hepatocyte-specific XO knockout mice with SS Townes bone marrow. However, hepatocyte-specific XO knockout, which results in >50% diminution in circulating XO, did not affect hemolysis levels or vascular function, suggesting hepatocyte-derived elevation of circulating XO is not the driver of hemolysis in SCD.

Conclusions: Ten weeks of febuxostat treatment significantly decreased hemolysis and improved pulmonary vasoreactivity in a mouse model of SCD. Although hepatic XO accounts for >50% of circulating XO, it is not the source of XO driving hemolysis in SCD.
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http://dx.doi.org/10.1161/ATVBAHA.120.315081DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8185582PMC
February 2021

CD47 Promotes Age-Associated Deterioration in Angiogenesis, Blood Flow and Glucose Homeostasis.

Cells 2020 07 15;9(7). Epub 2020 Jul 15.

Centre for Transplant and Renal Research, Westmead Institute for Medical Research, University of Sydney, 176 Hawkesbury Rd, Sydney 2145, NSW, Australia.

The aged population is currently at its highest level in human history and is expected to increase further in the coming years. In humans, aging is accompanied by impaired angiogenesis, diminished blood flow and altered metabolism, among others. A cellular mechanism that impinges upon these manifestations of aging can be a suitable target for therapeutic intervention. Here we identify cell surface receptor CD47 as a novel age-sensitive driver of vascular and metabolic dysfunction. With the natural aging process, CD47 and its ligand thrombospondin-1 were increased, concurrent with a reduction of self-renewal transcription factors OCT4, SOX2, KLF4 and cMYC (OSKM) in arteries from aged wild-type mice and older human subjects compared to younger controls. These perturbations were prevented in arteries from aged CD47-null mice. Arterial endothelial cells isolated from aged wild-type mice displayed cellular exhaustion with decreased proliferation, migration and tube formation compared to cells from aged CD47-null mice. CD47 suppressed ex vivo sprouting, in vivo angiogenesis and skeletal muscle blood flow in aged wild-type mice. Treatment of arteries from older humans with a CD47 blocking antibody mitigated the age-related deterioration in angiogenesis. Finally, aged CD47-null mice were resistant to age- and diet-associated weight gain, glucose intolerance and insulin desensitization. These results indicate that the CD47-mediated signaling maladapts during aging to broadly impair endothelial self-renewal, angiogenesis, perfusion and glucose homeostasis. Our findings provide a strong rationale for therapeutically targeting CD47 to minimize these dysfunctions during aging.
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http://dx.doi.org/10.3390/cells9071695DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7407670PMC
July 2020

Excessive dietary salt promotes aortic stiffness in murine renovascular hypertension.

Am J Physiol Heart Circ Physiol 2020 05 17;318(5):H1346-H1355. Epub 2020 Apr 17.

Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.

Renovascular hypertension is characterized by activation of the renin-angiotensin-aldosterone system, blunted natriuretic responses, and elevated sympathetic nerve activity. Excess dietary salt intake exaggerates arterial blood pressure (ABP) in multiple models of experimental hypertension. The present study tested whether a high-salt diet exaggerated ABP and vascular dysfunction in a 2-kidney, 1-clip (2K1C) murine model. Male C57BL/6J mice (8-12 wk) were randomly assigned, and fed a 0.1% or 4.0% NaCl diet, and instrumented with telemetry units to measure ABP. Then, the 2K1C model was produced by placing a cuff around the right renal artery. Systolic, diastolic, and mean ABP were significantly higher in mice fed 4.0% vs. 0.1% NaCl at 1 wk but not after 3 wk. Interestingly, 2K1C hypertension progressively increased arterial pulse pressure in both groups; however, the magnitude was significantly greater in mice fed 4.0% vs. 0.1% NaCl at 3 wk. Moreover, pulse wave velocity was significantly greater in 2K1C mice fed 4.0% vs. 0.1% NaCl diet or sham-operated mice fed either diet. Histological assessment of aortas indicated no structural differences among groups. Finally, endothelium-dependent vasodilation was significantly and selectively attenuated in the aorta but not mesenteric arteries of 2K1C mice fed 4.0% NaCl vs. 0.1% NaCl or sham-operated control mice. The findings suggest that dietary salt loading transiently exaggerates 2K1C renovascular hypertension but promotes chronic aortic stiffness and selective aortic vascular dysfunction. High dietary salt exaggerates hypertension in multiple experimental models. Here we demonstrate that a high-salt diet produces a greater increase in arterial blood pressure at 1 wk after induction of 2-kidney, 1-clip (2K1C) hypertension but not at 3 wk. Interestingly, 2K1C mice fed a high-salt diet displayed an exaggerated pulse pressure, elevated pulse wave velocity, and reduced endothelium-dependent vasodilation of the aorta but not mesenteric arteries. These findings suggest that dietary salt may interact with underlying cardiovascular disease to promote selective vascular dysfunction and aortic stiffness.
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http://dx.doi.org/10.1152/ajpheart.00601.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7346535PMC
May 2020

Nitrite elicits divergent NO-dependent signaling that associates with outcome in out of hospital cardiac arrest.

Redox Biol 2020 05 14;32:101463. Epub 2020 Feb 14.

Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, USA; Department of Critical Care Medicine, Safar Center for Resuscitation Research, University of Pittsburgh, USA. Electronic address:

Brain and heart injury cause most out-of-hospital cardiac arrest deaths but limited pharmacotherapy exists to protect these tissues. Nitrite is a nitric oxide precursor that is protective in pre-clinical models of ischemic injury and safe in Phase I testing. Protection may occur by cGMP generation via the sGC pathway or through S-nitrosothiol and nitrated conjugated linoleic acid (NO-CLA) formation. We hypothesized that nitrite provided during CPR signals through multiple pathways and that activation of signals is associated with OHCA outcome. To this end, we performed a secondary analysis of a phase 1 study of intravenous nitrite administration during resuscitation in adult out-of-hospital cardiac arrest. Associations between whole blood nitrite and derived plasma signals (cGMP and NO-CLA) with patient characteristics and outcomes were defined using Chi-square or t-tests and multiple logistic regression. Whole blood nitrite levels correlated inversely with plasma NO-CLA (p = 0.039) but not with cGMP. Patients with shockable rhythms had higher cGMP (p = 0.027), NO-CLA (p < 0.0001) and trended towards lower nitrite (p = 0.077). Importantly, plasma cGMP and NO-CLA levels were higher in survivors (p = 0.033 and 0.019) and in those with good neurological outcome (p = 0.046 and 0.021). Nitrite was lower in patients with good neurologic outcome (p = 0.029). cGMP (OR 4.02; 95% CI 1.04-15.54; p = 0.044) and NO-CLA (OR 3.74; 95% CI 1.11-12.65; p = 0.034) were associated with survival. Nitrite (OR 0.20; 95% CI 0.05-0.08; p = 0.026) and NO-CLA (OR 3.96; 95% CI 1.01-15.60; p = 0.049) were associated with favorable neurologic outcome. In summary, nitrite administration was associated with increased plasma cGMP and NO-CLA formation in selected OHCA patients. Furthermore, patients with the highest levels of cGMP and NO-CLA were more likely to survive and experience better neurological outcomes.
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http://dx.doi.org/10.1016/j.redox.2020.101463DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7033352PMC
May 2020

Nrf2 activation protects against lithium-induced nephrogenic diabetes insipidus.

JCI Insight 2020 01 16;5(1). Epub 2020 Jan 16.

Department of Pharmacology and Chemical Biology.

Lithium (Li) is the mainstay pharmacotherapeutic mood stabilizer in bipolar disorder. Its efficacious use is complicated by acute and chronic renal side effects, including nephrogenic diabetes insipidus (NDI) and progression to chronic kidney disease (CKD). The nuclear factor erythroid-derived 2-related factor 2 (Nrf2) pathway senses and coordinates cellular responses to oxidative and electrophilic stress. Here, we identify that graded genetic activation of Nrf2 protects against Li-induced NDI (Li-NDI) and volume wasting via an aquaporin 2-independent mechanism. Renal Nrf2 activity is differentially expressed on functional segments of the nephron, and its activation along the distal tubule and collecting duct directly modulates ion transporter expression, mimicking paradoxical effects of diuretics in mitigating Li-NDI. In addition, Nrf2 reduces cyclooxygenase expression and vasoactive prostaglandin biosynthesis. Pharmacologic activation of Nrf2 confers protective effects, confirming this pathway as a potentially novel druggable target for the prevention of acute and chronic renal sequelae of Li therapy.
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http://dx.doi.org/10.1172/jci.insight.128578DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7030822PMC
January 2020

Sickle cell disease: at the crossroads of pulmonary hypertension and diastolic heart failure.

Heart 2020 04 10;106(8):562-568. Epub 2019 Dec 10.

Division of Pulmonary, Allergy and Critical Care Medicine in the Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.

Sickle cell disease (SCD) is caused by a single point mutation in the gene that codes for beta globin synthesis, causing haemoglobin polymerisation, red blood cell stiffening and haemolysis under low oxygen and pH conditions. Downstream effects include widespread vasculopathy due to recurring vaso-occlusive events and haemolytic anaemia, affecting all organ systems. Cardiopulmonary complications are the leading cause of death in patients with SCD, primarily resulting from diastolic heart failure (HF) and/or pulmonary hypertension (PH). HF in SCD often features biventricular cardiac hypertrophy and left ventricular (LV) diastolic dysfunction. Among HF cases in the general population, approximately half occur with preserved ejection fraction (HFpEF). The insidious evolution of HFpEF differs from the relatively acute evolution of HF with reduced ejection fraction. The PH of SCD has diverse origins, which can be pulmonary arterial (precapillary), pulmonary venous (postcapillary) or pulmonary thromboembolic. It is also appreciated that patients with SCD can develop both precapillary and postcapillary PH, with elevations in LV diastolic pressures, as well as elevations in transpulmonary pressure gradient and pulmonary vascular resistance. Regardless of the cause of PH in SCD, its presence significantly reduces functional capacity and increases mortality. PH that occurs in the presence of HFpEF is usually of postcapillary origin. This review aims to assemble what has been learnt from clinical and animal studies about the manifestation of PH-HFpEF in SCD, specifically the contributions of LV diastolic dysfunction and myocardial fibrosis, in an attempt to gain an understanding of its evolution.
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http://dx.doi.org/10.1136/heartjnl-2019-314810DOI Listing
April 2020

Smooth muscle cytochrome b5 reductase 3 deficiency accelerates pulmonary hypertension development in sickle cell mice.

Blood Adv 2019 12;3(23):4104-4116

Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, Department of Medicine.

Pulmonary and systemic vasculopathies are significant risk factors for early morbidity and death in patients with sickle cell disease (SCD). An underlying mechanism of SCD vasculopathy is vascular smooth muscle (VSM) nitric oxide (NO) resistance, which is mediated by NO scavenging reactions with plasma hemoglobin (Hb) and reactive oxygen species that can oxidize soluble guanylyl cyclase (sGC), the NO receptor. Prior studies show that cytochrome b5 reductase 3 (CYB5R3), known as methemoglobin reductase in erythrocytes, functions in VSM as an sGC heme iron reductase critical for reducing and sensitizing sGC to NO and generating cyclic guanosine monophosphate for vasodilation. Therefore, we hypothesized that VSM CYB5R3 deficiency accelerates development of pulmonary hypertension (PH) in SCD. Bone marrow transplant was used to create SCD chimeric mice with background smooth muscle cell (SMC)-specific tamoxifen-inducible Cyb5r3 knockout (SMC R3 KO) and wild-type (WT) control. Three weeks after completing tamoxifen treatment, we observed 60% knockdown of pulmonary arterial SMC CYB5R3, 5 to 6 mm Hg elevated right-ventricular (RV) maximum systolic pressure (RVmaxSP) and biventricular hypertrophy in SS chimeras with SMC R3 KO (SS/R3KD) relative to WT (SS/R3WT). RV contractility, heart rate, hematological parameters, and cell-free Hb were similar between groups. When identically generated SS/R3 chimeras were studied 12 weeks after completing tamoxifen treatment, RVmaxSP in SS/R3KD had not increased further, but RV hypertrophy relative to SS/R3WT persisted. These are the first studies to establish involvement of SMC CYB5R3 in SCD-associated development of PH, which can exist in mice by 5 weeks of SMC CYB5R3 protein deficiency.
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http://dx.doi.org/10.1182/bloodadvances.2019000621DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6963246PMC
December 2019

Ultrasound-Targeted Microbubble Cavitation with Sodium Nitrite Synergistically Enhances Nitric Oxide Production and Microvascular Perfusion.

Ultrasound Med Biol 2020 03 3;46(3):667-678. Epub 2019 Dec 3.

Center for Ultrasound and Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. Electronic address:

Microvascular obstruction is a common repercussion of percutaneous coronary intervention for distal microembolization, ischemia-reperfusion injury and inflammation, which increases post-myocardial infarction heart failure and mortality. Ultrasound-targeted microbubble cavitation (UTMC) may resolve microvascular obstruction while activating endothelial nitric oxide synthase (eNOS) and increasing endothelium-derived nitric oxide (NO) bioavailability. Nitrite, a cardioprotective agent, offers an additional source of NO and potential synergy with UTMC. UTMC and nitrite co-therapy increased microvascular perfusion and NO concentration in a rat hindlimb model. Using N-nitro-L-arginine methyl ester for eNOS blockade, we found a three-way interaction effect between nitrite, UTMC and eNOS on microvascular perfusion and NO production. Modulating ultrasound peak negative acoustic pressure (0.33-1.5 MPa) significantly affected outcomes, while microbubble dosage (2 × 10 bubbles/mL, 1.5 mL/h to 1 × 10 bubbles/mL, 3 mL/h) did not. Nitrite co-therapy also protected against oxidative stress. Comparison of nitrite to sodium nitroprusside with UTMC revealed synergistic effects were specific to nitrite. Synergy between UTMC and nitrite holds therapeutic potential for cardiovascular disease.
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http://dx.doi.org/10.1016/j.ultrasmedbio.2019.10.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7010556PMC
March 2020

Decoding the role of SOD2 in sickle cell disease.

Blood Adv 2019 09;3(17):2679-2687

Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute.

Sickle cell disease (SCD) is an inherited hemoglobinopathy caused by a single point mutation in the β-globin gene. As a consequence, deoxygenated hemoglobin polymerizes triggering red blood cell sickling and hemolysis, vaso-occlusion, and ischemia/reperfusion. Allied to these pathologies is the overproduction of reactive oxygen species driven by hemoglobin Fenton chemistry and peroxidase reactions as well as by secondary activation of vascular oxidases, including NAD(P)H oxidase and xanthine oxidase. In addition, hypoxia, produced by sickle red blood cell occlusion, disrupts mitochondrial metabolism and generates excess superoxide through electron leak from the mitochondrial respiratory chain. Superoxide dismutase 2 (SOD2) is a mitochondrial-specific antioxidant enzyme that dismutates superoxide to hydrogen peroxide, which is then converted to water by catalase and glutathione peroxidase. In SCD, the antioxidant defense system is significantly diminished through decreased expression and activity levels of antioxidant enzymes, including superoxide dismutase, catalase, and glutathione peroxidase. From a translational perspective, genetic variants including a missense variant in SOD2 (valine to alanine at position 16) are present in 45% of people with African ancestry and are associated with increased sickle complications. While it is known that there is an imbalance between oxidative species and antioxidant defenses in SCD, much more investigation is warranted. This review summarizes our current understanding of antioxidant defense systems in SCD, particularly focused on SOD2, and provides insight into challenges and opportunities as the field moves forward.
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http://dx.doi.org/10.1182/bloodadvances.2019000527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6737422PMC
September 2019

Loss of smooth muscle CYB5R3 amplifies angiotensin II-induced hypertension by increasing sGC heme oxidation.

JCI Insight 2019 10 3;4(19). Epub 2019 Oct 3.

Heart, Lung, Blood and Vascular Medicine Institute, and.

Nitric oxide regulates BP by binding the reduced heme iron (Fe2+) in soluble guanylyl cyclase (sGC) and relaxing vascular smooth muscle cells (SMCs). We previously showed that sGC heme iron reduction (Fe3+ → Fe2+) is modulated by cytochrome b5 reductase 3 (CYB5R3). However, the in vivo role of SMC CYB5R3 in BP regulation remains elusive. Here, we generated conditional smooth muscle cell-specific Cyb5r3 KO mice (SMC CYB5R3-KO) to test if SMC CYB5R3 loss affects systemic BP in normotension and hypertension via regulation of the sGC redox state. SMC CYB5R3-KO mice exhibited a 5.84-mmHg increase in BP and impaired acetylcholine-induced vasodilation in mesenteric arteries compared with controls. To drive sGC oxidation and elevate BP, we infused mice with angiotensin II. We found that SMC CYB5R3-KO mice exhibited a 14.75-mmHg BP increase, and mesenteric arteries had diminished nitric oxide-dependent vasodilation but increased responsiveness to sGC heme-independent activator BAY 58-2667 over controls. Furthermore, acute injection of BAY 58-2667 in angiotensin II-treated SMC CYB5R3-KO mice showed greater BP reduction compared with controls. Together, these data provide the first in vivo evidence to our knowledge that SMC CYB5R3 is an sGC heme reductase in resistance arteries and provides resilience against systemic hypertension development.
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http://dx.doi.org/10.1172/jci.insight.129183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6795404PMC
October 2019

Antagonism of Forkhead Box Subclass O Transcription Factors Elicits Loss of Soluble Guanylyl Cyclase Expression.

Mol Pharmacol 2019 06 15;95(6):629-637. Epub 2019 Apr 15.

Heart, Lung, Blood and Vascular Medicine Institute (J.C.G., B.G.D., M.P.M., S.A.H., S.Y., K.C.W., A.C.S.) and Department of Pharmacology and Chemical Biology (J.C.G., A.C.S.), University of Pittsburgh, Pittsburgh, Pennsylvania

Nitric oxide (NO) stimulates soluble guanylyl cyclase (sGC) activity, leading to elevated intracellular cyclic guanosine 3',5'-monophosphate (cGMP) and subsequent vascular smooth muscle relaxation. It is known that downregulation of sGC expression attenuates vascular dilation and contributes to the pathogenesis of cardiovascular disease. However, it is not well understood how sGC transcription is regulated. Here, we demonstrate that pharmacological inhibition of Forkhead box subclass O (FoxO) transcription factors using the small-molecule inhibitor AS1842856 significantly blunts sGC and mRNA expression by more than 90%. These effects are concentration-dependent and concomitant with greater than 90% reduced expression of the known FoxO transcriptional targets, glucose-6-phosphatase and growth arrest and DNA damage protein 45 (Gadd45). Similarly, sGC and sGC protein expression showed a concentration-dependent downregulation. Consistent with the loss of sGC and mRNA and protein expression, pretreatment of vascular smooth muscle cells with the FoxO inhibitor decreased sGC activity measured by cGMP production following stimulation with an NO donor. To determine if FoxO inhibition resulted in a functional impairment in vascular relaxation, we cultured mouse thoracic aortas with the FoxO inhibitor and conducted ex vivo two-pin myography studies. Results showed that aortas have significantly blunted sodium nitroprusside-induced (NO-dependent) vasorelaxation and a 42% decrease in sGC expression after 48-hour FoxO inhibitor treatment. Taken together, these data are the first to identify that FoxO transcription factor activity is necessary for sGC expression and NO-dependent relaxation.
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http://dx.doi.org/10.1124/mol.118.115386DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6527398PMC
June 2019

Lipidomics Detection of Brain Cardiolipins in Plasma Is Associated With Outcome After Cardiac Arrest.

Crit Care Med 2019 04;47(4):e292-e300

Safar Center for Resuscitation Research, Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA.

Objectives: Brain mitochondrial dysfunction limits neurologic recovery after cardiac arrest. Brain polyunsaturated cardiolipins, mitochondria-unique and functionally essential phospholipids, have unprecedented diversification. Since brain cardiolipins are not present in plasma normally, we hypothesized their appearance would correlate with brain injury severity early after cardiac arrest and return of spontaneous circulation.

Design: Observational case-control study.

Setting: Two medical centers within one city.

Participants (subjects): We enrolled 41 adult cardiac arrest patients in whom blood could be obtained within 6 hours of resuscitation. Two subjects were excluded following outlier analysis. Ten healthy subjects were controls. Sprague-Dawley rats were used in asphyxial cardiac arrest studies.

Interventions: None.

Measurements And Main Results: We developed a high-resolution liquid chromatography/mass spectrometry method and determined cardiolipins speciation in human brain, heart, and plasma within 6 hours of (return of spontaneous circulation) from 39 patients with cardiac arrest, 5 with myocardial infarction, and 10 healthy controls. Cerebral score was derived from brain-specific cardiolipins identified in plasma of patients with varying neurologic injury and outcome. Using a rat model of cardiac arrest, cardiolipins were quantified in plasma, brain, and heart. Human brain exhibited a highly diverse cardiolipinome compared with heart that allowed the identification of brain-specific cardiolipins. Nine of 26 brain-specific cardiolipins were detected in plasma and correlated with brain injury. The cerebral score correlated with early neurologic injury and predicted discharge neurologic/functional outcome. Cardiolipin (70:5) emerged as a potential point-of-care marker predicting injury severity and outcome. In rat cardiac arrest, a significant reduction in hippocampal cardiolipins corresponded to their release from the brain into systemic circulation. Cerebral score was significantly increased in 10 minutes versus 5 minutes no-flow cardiac arrest and naïve controls.

Conclusions: Brain-specific cardiolipins accumulate in plasma early after return of spontaneous circulation and proportional to neurologic injury representing a promising novel biomarker.
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http://dx.doi.org/10.1097/CCM.0000000000003636DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6622168PMC
April 2019

The impact of xanthine oxidase (XO) on hemolytic diseases.

Redox Biol 2019 02 10;21:101072. Epub 2018 Dec 10.

Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, United States; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, United States. Electronic address:

Hemolytic diseases are associated with elevated levels of circulating free heme that can mediate endothelial dysfunction directly via redox reactions with biomolecules or indirectly by upregulating enzymatic sources of reactive species. A key enzymatic source of these reactive species is the purine catabolizing enzyme, xanthine oxidase (XO) as the oxidation of hypoxanthine to xanthine and subsequent oxidation of xanthine to uric acid generates superoxide (O) and hydrogen peroxide (HO). While XO has been studied for over 120 years, much remains unknown regarding specific mechanistic roles for this enzyme in pathologic processes. This gap in knowledge stems from several interrelated issues including: 1) lethality of global XO deletion and the absence of tissue-specific XO knockout models have coalesced to relegate proof-of-principle experimentation to pharmacology; 2) XO is mobile and thus when upregulated locally can be secreted into the circulation and impact distal vascular beds by high-affinity association to the glycocalyx on the endothelium; and 3) endothelial-bound XO is significantly resistant (> 50%) to inhibition by allopurinol, the principle compound used for XO inhibition in the clinic as well as the laboratory. While it is known that circulating XO is elevated in hemolytic diseases including sickle cell, malaria and sepsis, little is understood regarding its role in these pathologies. As such, the aim of this review is to define our current understanding regarding the effect of hemolysis (free heme) on circulating XO levels as well as the subsequent impact of XO-derived oxidants in hemolytic disease processes.
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http://dx.doi.org/10.1016/j.redox.2018.101072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6305892PMC
February 2019

Highlights From Vascular Discovery: From Genes to Medicine Scientific Sessions 2018.

J Am Heart Assoc 2018 08;7(15):e009470

3 Heart, Lung Blood and Vascular Medicine Institute University of Pittsburgh School of Medline Pittsburgh PA.

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http://dx.doi.org/10.1161/JAHA.118.009470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6201448PMC
August 2018

Escorting α-globin to eNOS: α-globin-stabilizing protein paves the way.

J Clin Invest 2018 11 8;128(11):4755-4757. Epub 2018 Oct 8.

Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute.

In the vascular wall, endothelial nitric oxide synthase (eNOS) produces NO to regulate peripheral vascular resistance, tissue perfusion, and blood pressure. In resistance arteries, eNOS couples with α-globin and, through chemical reactions, modulates NO diffusion needed for vascular smooth muscle relaxation. While α-globin protein alone is known to be unstable, the mechanisms that enable α-globin protein expression remain elusive. Here, Lechauve et al. report that arterial endothelium expresses α hemoglobin-stabilizing protein, which acts as a critical chaperone protein for α-globin expression and vascular function.
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http://dx.doi.org/10.1172/JCI124302DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6205368PMC
November 2018

Redox regulation of soluble guanylyl cyclase.

Nitric Oxide 2018 06 22;76:97-104. Epub 2018 Mar 22.

Pittsburgh Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA; Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address:

The nitric oxide/soluble guanylyl cyclase (NO-sGC) signaling pathway regulates the cardiovascular, neuronal, and gastrointestinal systems. Impaired sGC signaling can result in disease and system-wide organ failure. This review seeks to examine the redox control of sGC through heme and cysteine regulation while discussing therapeutic drugs that target various conditions. Heme regulation involves mechanisms of insertion of the heme moiety into the sGC protein, the molecules and proteins that control switching between the oxidized (Fe) and reduced states (Fe), and the activity of heme degradation. Modifications to cysteine residues by S-nitrosation on the α1 and β1 subunits of sGC have been shown to be important in sGC signaling. Moreover, redox balance and localization of sGC is thought to control downstream effects. In response to altered sGC activity due to changes in the redox state, many therapeutic drugs have been developed to target decreased NO-sGC signaling. The importance and relevance of sGC continues to grow as sGC dysregulation leads to numerous disease conditions.
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http://dx.doi.org/10.1016/j.niox.2018.03.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5916318PMC
June 2018

Redox control of vascular smooth muscle cell function and plasticity.

Lab Invest 2018 10 20;98(10):1254-1262. Epub 2018 Feb 20.

Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA.

Vascular smooth muscle cells (SMC) play a major role in vascular diseases, such as atherosclerosis and hypertension. It has long been established in vitro that contractile SMC can phenotypically switch to function as proliferative and/or migratory cells in response to stimulation by oxidative stress, growth factors, and inflammatory cytokines. Reactive oxygen species (ROS) are oxidative stressors implicated in driving vascular diseases, shifting cell bioenergetics, and increasing SMC proliferation, migration, and apoptosis. In this review, we summarize our current knowledge of how disruptions to redox balance can functionally change SMC and how this may influence vascular disease pathogenesis. Specifically, we focus on our current understanding of the role of vascular nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) 1, 4, and 5 in SMC function. We also review the evidence implicating mitochondrial fission in SMC phenotypic transitions and mitochondrial fusion in maintenance of SMC homeostasis. Finally, we discuss the importance of the redox regulation of the soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) pathway as a potential oxidative and therapeutic target for regulating SMC function.
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http://dx.doi.org/10.1038/s41374-018-0032-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6102093PMC
October 2018

Nitric Oxide-Independent Soluble Guanylate Cyclase Activation Improves Vascular Function and Cardiac Remodeling in Sickle Cell Disease.

Am J Respir Cell Mol Biol 2018 05;58(5):636-647

2 Heart, Lung, Blood, and Vascular Medicine Institute, Department of Medicine.

Sickle cell disease (SCD) is associated with intravascular hemolysis and oxidative inhibition of nitric oxide (NO) signaling. BAY 54-6544 is a small-molecule activator of oxidized soluble guanylate cyclase (sGC), which, unlike endogenous NO and the sGC stimulator, BAY 41-8543, preferentially binds and activates heme-free, NO-insensitive sGC to restore enzymatic cGMP production. We tested orally delivered sGC activator, BAY 54-6544 (17 mg/kg/d), sGC stimulator, BAY 41-8543, sildenafil, and placebo for 4-12 weeks in the Berkeley transgenic mouse model of SCD (BERK-SCD) and their hemizygous (Hemi) littermate controls (BERK-Hemi). Right ventricular (RV) maximum systolic pressure (RVmaxSP) was measured using micro right-heart catheterization. RV hypertrophy (RVH) was determined using Fulton's index and RV corrected weight (ratio of RV to tibia). Pulmonary artery vasoreactivity was tested for endothelium-dependent and -independent vessel relaxation. Right-heart catheterization revealed higher RVmaxSP and RVH in BERK-SCD versus BERK-Hemi, which worsened with age. Treatment with the sGC activator more effectively lowered RVmaxSP and RVH, with 90-day treatment delivering superior results, when compared with other treatments and placebo groups. In myography experiments, acetylcholine-induced (endothelium-dependent) and sodium-nitroprusside-induced (endothelium-independent NO donor) relaxation of the pulmonary artery harvested from placebo-treated BERK-SCD was impaired relative to BERK-Hemi but improved after therapy with sGC activator. By contrast, no significant effect for sGC stimulator or sildenafil was observed in BERK-SCD. These findings suggest that sGC is oxidized in the pulmonary arteries of transgenic SCD mice, leading to blunted responses to NO, and that the sGC activator, BAY 54-6544, may represent a novel therapy for SCD-associated pulmonary arterial hypertension and cardiac remodeling.
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http://dx.doi.org/10.1165/rcmb.2017-0292OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5946331PMC
May 2018

Redox Control of Vascular Function.

Arterioscler Thromb Vasc Biol 2017 12;37(12):e178-e184

From the Heart, Lung, Blood and Vascular Medicine Institute (J.C.G., A.C.S.) and Department of Pharmacology and Chemical Biology (J.C.G., A.C.S.), University of Pittsburgh, PA.

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http://dx.doi.org/10.1161/ATVBAHA.117.309945DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5751756PMC
December 2017

The Role of Nitric Oxide during Sonoreperfusion of Microvascular Obstruction.

Theranostics 2017 18;7(14):3527-3538. Epub 2017 Aug 18.

Center for Ultrasound and Molecular Imaging and Therapeutics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.

Microembolization during PCI for acute myocardial infarction can cause microvascular obstruction . MVO severely limits the success of reperfusion therapies, is associated with additional myonecrosis, and is linked to worse prognosis, including death. We have shown, both in and models, that ultrasound and microbubble therapy (termed "sonoreperfusion" or "") is a theranostic approach that relieves MVO and restores perfusion, but the underlying mechanisms remain to be established. In this study, we investigated the role of nitric oxide () during SRP. We first demonstrated in plated cells that US-stimulated MB oscillations induced a 6-fold increase in endothelial nitric oxide synthase phosphorylation We then monitored the kinetics of intramuscular NO and perfusion flow rate responses following 2-min of SRP therapy in the rat hindlimb muscle, with and without blockade of eNOS with LNAME. Following SRP, we found that starting at 6 minutes, intramuscular NO increased significantly over 30 min and was higher than baseline after 13 min. Concomitant contrast enhanced burst reperfusion imaging confirmed that there was a marked increase in perfusion flow rate at 6 and 10 min post SRP compared to baseline (>2.5 fold). The increases in intramuscular NO and perfusion rate were blunted with LNAME. Finally, we tested the hypothesis that NO plays a role in SRP by assessing reperfusion efficacy in a previously described rat hindlimb model of MVO during blockade of eNOS. After US treatment 1, microvascular blood volume was restored to baseline in the MB+US group, but remained low in the LNAME group. Perfusion rates increased in the MB+US group after US treatment 2 but not in the MB+US+LNAME group. These data strongly support that MB oscillations can activate the eNOS pathway leading to increased blood perfusion and that NO plays a significant role in SRP efficacy.
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http://dx.doi.org/10.7150/thno.19422DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5596441PMC
July 2018
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