Circulating Proteome Analysis Identifies Reduced Inflammation After Initiation of Hemodynamic Support with Either Veno-Arterial Extracorporeal Membrane Oxygenation or Impella in Patients with Cardiogenic Shock.

In-hospital mortality associated with cardiogenic shock (CS) remains high despite the use of percutaneous assist devices. We sought to determine whether support with VA-ECMO or Impella in patients with CS alters specific components of the plasma proteome. Plasma samples were collected before device implantation and 72 h after initiation of support in 11 CS patients receiving ECMO or Impella. SOMAscan was used to detect 1305 circulating proteins. Sixty-seven proteins were changed after ECMO (18 upregulated and 49 downregulated, p < 0.05), 38 after Impella (10 upregulated and 28 downregulated, p < 0.05), and only eight proteins were commonly affected. Despite minimal protein overlap, both devices were associated with markers of reduced inflammation and increased apoptosis of inflammatory cells. In summary, ECMO and Impella are associated with reduced expression of inflammatory markers and increased markers of inflammatory cell death. These circulating proteins may serve as novel targets of therapy or biomarkers to tailor AMCS use.

Novel Role for Cardiolipin as a Target of Therapy to Mitigate Myocardial Injury Caused by Venoarterial Extracorporeal Membrane Oxygenation.

BACKGROUND: Cardiolipin is a mitochondrial-specific phospholipid that maintains integrity of the electron transport chain (ETC) and plays a central role in myocardial ischemia/reperfusion injury. Tafazzin is an enzyme that is required for cardiolipin maturation. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) use to provide hemodynamic support for acute myocardial infarction has grown exponentially, is associated with poor outcomes, and is under active clinical investigation, yet the mechanistic effect of VA-ECMO on myocardial damage in acute myocardial infarction remains poorly understood. We hypothesized that VA-ECMO acutely depletes myocardial cardiolipin and exacerbates myocardial injury in acute myocardial infarction. METHODS: We examined cardiolipin and tafazzin levels in human subjects with heart failure and healthy swine exposed to VA-ECMO and used a swine model of closed-chest myocardial ischemia/reperfusion injury to evaluate the effect of VA-ECMO on cardiolipin expression, myocardial injury, and mitochondrial function. RESULTS: Cardiolipin and tafazzin levels are significantly reduced in the left ventricles of individuals requiring VA-ECMO compared with individuals without VA-ECMO before heart transplantation. Six hours of exposure to VA-ECMO also decreased left ventricular levels of cardiolipin and tafazzin in healthy swine compared with sham controls. To explore whether cardiolipin depletion by VA-ECMO increases infarct size, we performed left anterior descending artery occlusion for a total of 120 minutes followed by 180 minutes of reperfusion in adult swine in the presence and absence of MTP-131, an amphipathic molecule that interacts with cardiolipin to stabilize the inner mitochondrial membrane. Compared with reperfusion alone, VA-ECMO activation beginning after 90 minutes of left anterior descending artery occlusion increased infarct size (36±8% versus 48±7%; P<0.001). VA-ECMO also decreased cardiolipin and tafazzin levels, disrupted mitochondrial integrity, reduced electron transport chain function, and promoted oxidative stress. Compared with reperfusion alone or VA-ECMO before reperfusion, delivery of MTP-131 before VA-ECMO activation reduced infarct size (22±8%; P=0.03 versus reperfusion alone and P<0.001 versus VA-ECMO alone). MTP-131 restored cardiolipin and tafazzin levels, stabilized mitochondrial function, and reduced oxidative stress in the left ventricle. CONCLUSIONS: We identified a novel mechanism by which VA-ECMO promotes myocardial injury and further identify cardiolipin as an important target of therapy to reduce infarct size and to preserve mitochondrial function in the setting of VA-ECMO for acute myocardial infarction.

Loss of Bone Morphogenetic Protein-9 Reduces Survival and Increases MMP Activity After Myocardial Infarction.

No studies have explored a functional role for bone morphogenetic protein (BMP)-9, a transforming growth factor-ß superfamily ligand, in cardiac remodeling after myocardial infarction (MI). Using BMP-9 null mice, we observed that loss of BMP-9 decreases survival and increases cardiac rupture after MI. We further observed that loss of BMP-9 not only increases collagen abundance, but also promotes matrix metalloproteinase-9 activity and collagen degradation after MI. These findings identify BMP-9 as a necessary component of cardiac remodeling after MI and a potentially important target of therapy to improve outcomes after MI.

ALK1 Deficiency Impairs the Wound-Healing Process and Increases Mortality in Murine Model of Myocardial Infarction.

The functional role of TGFß type I receptor, activin-like kinase (ALK)-1 in post-myocardial infarction (MI) cardiac remodeling is unknown. We hypothesize that reduced ALK1 activity reduces survival and promotes cardiac fibrosis after MI. MI was induced in wild-type (WT), and ALK+/- mice by left coronary ligation. After 14 days ALK1+/- mice had reduced survival with a higher rate of cardiac rupture compared to WT mice. ALK1+/- left ventricles (LVs) had increased volumes at the end of systole and at the end of diastole. After MI ALK1+/- LVs had increased profibrotic SMAD3 signaling, type 1 collagen, and fibrosis as well as increased levels of TGFß1 co-receptor, endoglin, VEGF, and ALK1 ligands BMP9 and BMP10. ALK1+/- LVs had decreased levels of stromal-derived factor 1α. These data identify the critical role of ALK1 in post-MI survival and cardiac remodeling and implicate ALK1 as a potential therapeutic target to improve survival after MI.

Transvalvular Unloading Mitigates Ventricular Injury Due to Venoarterial Extracorporeal Membrane Oxygenation in Acute Myocardial Infarction.

Whether extracorporeal membrane oxygenation (ECMO) with Impella, known as EC-Pella, limits cardiac damage in acute myocardial infarction remains unknown. The authors now report that the combination of transvalvular unloading and ECMO (EC-Pella) initiated before reperfusion reduced infarct size compared with ECMO alone before reperfusion in a preclinical model of acute myocardial infarction. EC-Pella also reduced left ventricular pressure-volume area when transvalvular unloading was applied before, not after, activation of ECMO. The authors further observed that EC-Pella increased cardioprotective signaling but failed to rescue mitochondrial dysfunction compared with ECMO alone. These findings suggest that ECMO can increase infarct size in acute myocardial infarction and that EC-Pella can mitigate this effect but also suggest that left ventricular unloading and myocardial salvage may be uncoupled in the presence of ECMO in acute myocardial infarction. These observations implicate mechanisms beyond hemodynamic load as part of the injury cascade associated with ECMO in acute myocardial infarction.

Safety and efficacy of fecal microbiota transplantation in the treatment of graft-versus-host disease.

This article evaluates the efficacy and safety of FMT in the treatment of GVHD after HSCT using a systematic literature search to conduct a meta-analysis constructed of studies involving GVHD patients treated with FMT. 23 studies were included, among which 2 prospective cohort studies, 10 prospective single arm studies, 2 retrospective single arm studies, 2 case series and 7 case reports, comprise a total of 242 patients with steroid-resistant or steroid-dependent GVHD secondary to HSCT who were treated with FMT. 100 cases achieved complete responses, while 61 cases showed partial responses, and 81 cases presented no effect after FMT treatment. The estimate of clinical remission odds ratio was 5.51 (95% CI 1.49-20.35) in cohort studies, and the pooled clinical remission rate is 64% (51-77%) in prospective single arm studies and 81% (62-95%) in retrospective studies, case series and case reports. Five (2.1%) patients had FMT-related infection events, but all recovered after treatment. Other adverse effects were mild and acceptable. Microbiota diversity and composition, donor type, and other related issues were also analyzed. The data proves that FMT is a promising treatment modality of GVHD, but further validation of its safety and efficacy is still needed with prospective control studies.Clinical trial registration: Registered in https://www.crd.york.ac.uk/PROSPERO/ CRD42022296288.

Myocardial Injury Promotes Matrix Metalloproteinase-9 Activity in the Renal Cortex in Preclinical Models of Acute Myocardial Infarction.

New mechanistic insight into how the kidney responds to cardiac injury during acute myocardial infarction (AMI) is required. We hypothesized that AMI promotes inflammation and matrix metalloproteinase-9 (MMP9) activity in the kidney and studied the effect of initiating an Impella CP or veno-arterial extracorporeal membrane oxygenation (VA-ECMO) before coronary reperfusion during AMI. Adult male swine were subjected to coronary occlusion and either reperfusion (ischemia-reperfusion; IR) or support with either Impella or VA-ECMO before reperfusion. IR and ECMO increased while Impella reduced levels of MMP-9 in the myocardial infarct zone, circulation, and renal cortex. Compared to IR, Impella reduced myocardial infarct size and urinary KIM-1 levels, but VA-ECMO did not. IR and VA-ECMO increased pro-fibrogenic signaling via transforming growth factor-beta and endoglin in the renal cortex, but Impella did not. These findings identify that AMI increases inflammatory activity in the kidney, which may be attenuated by Impella support.

Long-term outcomes of infantile spasms in children treated with ketogenic diet therapy in combination with anti-seizure medications in a resource-limited region.

Objective: Despite numerous guidelines, the overall outcome of infantile spasms is poor, with only a small number of patients being able to attend school. The purpose of this study was to investigate long-term outcomes. Patients had poor access to the recommended first-line anti-seizure medications (ASMs), such as hormones (corticotropin or prednisolone/prednisone) and vigabatrin, and their alternative treatment was other ASMs and a ketogenic diet. Methods: Patients suffering from infantile spasms who had at least 2 years of medical records in the electronic medical record system between January 2014 and August 2022 were included in this study. Patient information was retrospectively reviewed. All patients had received ketogenic diet therapy (mainly classical ketogenic diet therapy). The ketogenic diet therapy was combined with ASMs not used as first-line therapies. The primary endpoint outcome measure was the number of patients with seizure freedom. The secondary measures included the duration of ketogenic diet therapy, choice of ASMs, and patient development at the last visit. Results: A total of 177 patients with infantile spasms were included, and 152 (86%) of them had seizure freedom. The median duration from the first to the last hospital visit was 53.27 months, and the number of visits was 47.00. The median age at the initial hospital visit was 8.00 months, and the median age at initiation of the ketogenic diet was 17.73 months. At the last visit, the proportions of patients with neurodevelopmental delay, developmental epileptic encephalopathy, drug-resistant epilepsy, and generalized seizures increased significantly. The frequently used ASMs were topiramate, valproic acid, levetiracetam, nitrazepam, and vitamin B6 injection, while the recommended first-line drugs corticotropin and vigabatrin were rarely selected. The study duration of 9.5 years was divided into three periods but the prescription of ASMs did not change significantly between these periods. Conclusions: Although the seizure freedom rate was high with ketogenic diet therapy combined with non-standard ASMs, the patients had a significant neurodevelopmental delay at the last visit, which was, however, similar to that of standard treatment. To improve the outcomes of infantile spasms, multicenter clinical trials of the ketogenic diet as a first-line treatment in combination with non-standard ASMs are needed.

Transvalvular Ventricular Unloading Before Reperfusion in Acute Myocardial Infarction.

BACKGROUND: Myocardial damage due to acute ST-segment elevation myocardial infarction (STEMI) remains a significant global health problem. New approaches to limit myocardial infarct size and reduce progression to heart failure after STEMI are needed. Mechanically reducing left ventricular (LV) workload (LV unloading) before coronary reperfusion is emerging as a potential approach to reduce infarct size. OBJECTIVES: Given the central importance of mitochondria in reperfusion injury, we hypothesized that compared with immediate reperfusion (IR), LV unloading before reperfusion improves myocardial energy substrate use and preserves mitochondrial structure and function. METHODS: To explore the effect of LV unloading duration on infarct size, we analyzed data from the STEMI-Door to Unload (STEMI-DTU) trial and then tested the effect of LV unloading on ischemia and reperfusion injury, cardiac metabolism, and mitochondrial function in swine models of acute myocardial infarction. RESULTS: The duration of LV unloading before reperfusion was inversely associated with infarct size in patients with large anterior STEMI. In preclinical models, LV unloading reduced the expression of hypoxia-sensitive proteins and myocardial damage due to ischemia alone. LV unloading with a transvalvular pump (TV-P) but not with venoarterial extracorporeal membrane oxygenation (ECMO) reduced infarct size. Using unbiased and blinded metabolic profiling, TV-P improved myocardial energy substrate use and preserved mitochondrial structure including cardiolipin content after reperfusion compared with IR or ECMO. Functional testing in mitochondria isolated from the infarct zone showed an intact mitochondrial structure including cardiolipin content, preserved activity of the electron transport chain including mitochondrial complex I, and reduced oxidative stress with TV-P-supported reperfusion but not with IR or ECMO. CONCLUSIONS: These novel findings identify that transvalvular unloading limits ischemic injury before reperfusion, improves myocardial energy substrate use, and preserves mitochondrial structure and function after reperfusion.

Left Ventricular Unloading Increases the Coronary Collateral Flow Index Before Reperfusion and Reduces Infarct Size in a Swine Model of Acute Myocardial Infarction.

Background Unloading the left ventricle and delaying reperfusion reduces infarct size in preclinical models of acute myocardial infarction. We hypothesized that a potential explanation for this effect is that left ventricular (LV) unloading before reperfusion increases collateral blood flow to ischemic myocardium. Methods and Results Acute myocardial infarction was induced by balloon occlusion of the left anterior descending artery for 120 minutes in adult swine, followed by reperfusion for 180 minutes. After 90 minutes of occlusion, animals were assigned to 30 minutes of continued occlusion (n=6) or to 30 minutes of support with either an Impella CP (n=4) or venoarterial extracorporeal membrane oxygenation (n=5) with persistent occlusion. The primary end point was measures of microcirculatory blood flow including the collateral flow index (CFI) during left anterior descending artery occlusion as (Pw-RA)/(Pa-RA), where Pa, Pw, and RA are aortic, coronary wedge, and right atrial pressure, respectively. Infarct size was quantified using triphenyltetrazolium chloride. Compared with continued occlusion, Impella, not venoarterial extracorporeal membrane oxygenation, reduced infarct size relative to the area at risk. Before reperfusion, Impella reduced LV stroke work by 25% and increased the CFI by 75%, but venoarterial extracorporeal membrane oxygenation did not. Among all groups, the change in CFI between 90 and 120 minutes correlated inversely with the change in LV stroke work (r2=0.44, P=0.01) and infarct size (r2=0.41, P=0.02). Conclusions We report for the first time that 30 minutes of LV unloading during coronary occlusion increases the CFI, which correlates inversely with LV stroke work and infarct size. Venoarterial extracorporeal membrane oxygenation failed to increase the CFI and did not reduce infarct size.

Mechanical Left Ventricular Unloading to Reduce Infarct Size During Acute Myocardial Infarction: Insight from Preclinical and Clinical Studies.

Acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality. Pioneering preclinical work reported by Peter Maroko and Eugene Braunwald in 1971 identified oxygen supply and demand are primary determinants of myocardial infarct size in the setting of a heart attack. Since the 1950s, advances in mechanical engineering led to the development of short-term circulatory support devices that range from pulsatile to continuous flow pumps. The primary objective of these pumps is to reduce native heart work, enhance coronary blood flow, and sustain systemic perfusion. Whether these pumps could reduce myocardial infarct size in the setting of AMI became an intense focus for preclinical investigation with variable animal models, experimental algorithms, and pump platforms being tested. In this review, we discuss the design of these preclinical studies and the evolution of mechanical support platforms and attempt to translate these experimental methods into clinical trials.

Mixed lineage kinase-3 prevents cardiac dysfunction and structural remodeling with pressure overload.

Myocardial hypertrophy is an independent risk factor for heart failure (HF), yet the mechanisms underlying pathological cardiomyocyte growth are incompletely understood. The c-Jun NH2-terminal kinase (JNK) signaling cascade modulates cardiac hypertrophic remodeling, but the upstream factors regulating myocardial JNK activity remain unclear. In this study, we sought to identify JNK-activating molecules as novel regulators of cardiac remodeling in HF. We investigated mixed lineage kinase-3 (MLK3), a master regulator of upstream JNK-activating kinases, whose role in the remodeling process had not previously been studied. We observed increased MLK3 protein expression in myocardium from patients with nonischemic and hypertrophic cardiomyopathy and in hearts of mice subjected to transverse aortic constriction (TAC). Mice with genetic deletion of MLK3 (MLK3-/-) exhibited baseline cardiac hypertrophy with preserved cardiac function. MLK3-/- mice subjected to chronic left ventricular (LV) pressure overload (TAC, 4 wk) developed worsened cardiac dysfunction and increased LV chamber size compared with MLK3+/+ littermates ( n = 8). LV mass, pathological markers of hypertrophy ( Nppa, Nppb), and cardiomyocyte size were elevated in MLK3-/- TAC hearts. Phosphorylation of JNK, but not other MAPK pathways, was selectively impaired in MLK3-/- TAC hearts. In adult rat cardiomyocytes, pharmacological MLK3 kinase inhibition using URMC-099 blocked JNK phosphorylation induced by neurohormonal agents and oxidants. Sustained URMC-099 exposure induced cardiomyocyte hypertrophy. These data demonstrate that MLK3 prevents adverse cardiac remodeling in the setting of pressure overload. Mechanistically, MLK3 activates JNK, which in turn opposes cardiomyocyte hypertrophy. These results support modulation of MLK3 as a potential therapeutic approach in HF. NEW & NOTEWORTHY Here, we identified a role for mixed lineage kinase-3 (MLK3) as a novel antihypertrophic and antiremodeling molecule in response to cardiac pressure overload. MLK3 regulates phosphorylation of the stress-responsive JNK kinase in response to pressure overload and in cultured cardiomyocytes stimulated with hypertrophic agonists and oxidants. This study reveals MLK3-JNK signaling as a novel cardioprotective signaling axis in the setting of pressure overload.

Preparation of Parabolic Superhydrophobic Material for Oil-Water Separation.

In order to prepare parabolic superhydrophobic materials, copper meshes were used as the substrate and ultrasonic etching and oxidative corrosion were carried out with FeCl3 solution and H2O2 solution, respectively, and then the surface was modified with stearic acid (SA). The topological structure and surface wettability of the prepared mesh were characterized by fluorescence microscope, scanning electron microscopy and contact angle measurement. Finally, the as-prepared copper meshes were applied to oil-water separation. The results showed that the micro-nano-mastoid structure on the surface of the copper mesh was flaky bulges, forming a rough structure similar to a paraboloid. When the oxidative corrosion time of H2O2 was 1 min, it is more beneficial to increase the hydrophobicity of the surface of the copper mesh and increase the contact angle of water droplets on the surface of the membrane. Additionally, based on superhydrophobic materials of the parabolic copper mesh, the static contact angles of the water droplets, engine oil and carbon tetrachloride with the surface were approximately 153.6°, 5° and 0.1°, respectively and the sliding angle of the water droplets with the surface were approximately 4.9°. The parabolic membrane was applied to discuss the separation efficiency of different oils with deionized water and the separation efficiency was obtained as benzene > carbon tetrachloride > oil > machine oil. Therefore, based on the research, the parabolic superhydrophobic material has good efficiency of oil-water separation.

Left Ventricular Unloading Before Reperfusion Promotes Functional Recovery After Acute Myocardial Infarction.

BACKGROUND: Heart failure after an acute myocardial infarction (AMI) is a major cause of morbidity and mortality worldwide. We recently reported that activation of a transvalvular axial-flow pump in the left ventricle and delaying myocardial reperfusion, known as primary unloading, limits infarct size after AMI. The mechanisms underlying the cardioprotective benefit of primary unloading and whether the acute decrease in infarct size results in a durable reduction in LV scar and improves cardiac function remain unknown. OBJECTIVES: This study tested the importance of LV unloading before reperfusion, explored cardioprotective mechanisms, and determined the late-term impact of primary unloading on myocardial function. METHODS: Adult male swine were subjected to primary reperfusion or primary unloading after 90 min of percutaneous left anterior descending artery occlusion. RESULTS: Compared with primary reperfusion, 30 min of LV unloading was necessary and sufficient before reperfusion to limit infarct size 28 days after AMI. Compared with primary reperfusion, primary unloading increased expression of genes associated with cellular respiration and mitochondrial integrity within the infarct zone. Primary unloading for 30 min further reduced activity levels of proteases known to degrade the cardioprotective cytokine, stromal-derived factor (SDF)-1α, thereby increasing SDF-1α signaling via reperfusion injury salvage kinases, which limits apoptosis within the infarct zone. Inhibiting SDF-1α activity attenuated the cardioprotective effect of primary unloading. Twenty-eight days after AMI, primary unloading reduced LV scar size, improved cardiac function, and limited expression of biomarkers associated with heart failure and maladaptive remodeling. CONCLUSIONS: The authors report for the first time that first mechanically reducing LV work before coronary reperfusion with a transvalvular pump is necessary and sufficient to reduce infarct size and to activate a cardioprotective program that includes enhanced SDF-1α activity. Primary unloading further improved LV scar size and cardiac function 28 days after AMI.

Bone Morphogenetic Protein 9 Reduces Cardiac Fibrosis and Improves Cardiac Function in Heart Failure.

BACKGROUND: Heart failure is a growing cause of morbidity and mortality worldwide. Transforming growth factor beta (TGF-ß1) promotes cardiac fibrosis, but also activates counterregulatory pathways that serve to regulate TGF-ß1 activity in heart failure. Bone morphogenetic protein 9 (BMP9) is a member of the TGFß family of cytokines and signals via the downstream effector protein Smad1. Endoglin is a TGFß coreceptor that promotes TGF-ß1 signaling via Smad3 and binds BMP9 with high affinity. We hypothesized that BMP9 limits cardiac fibrosis by activating Smad1 and attenuating Smad3, and, furthermore, that neutralizing endoglin activity promotes BMP9 activity. METHODS: We examined BMP9 expression and signaling in human cardiac fibroblasts and human subjects with heart failure. We used the transverse aortic constriction-induced model of heart failure to evaluate the functional effect of BMP9 signaling on cardiac remodeling. RESULTS: BMP9 expression is increased in the circulation and left ventricle (LV) of human subjects with heart failure and is expressed by cardiac fibroblasts. Next, we observed that BMP9 attenuates type I collagen synthesis in human cardiac fibroblasts using recombinant human BMP9 and a small interfering RNA approach. In BMP9-/- mice subjected to transverse aortic constriction, loss of BMP9 activity promotes cardiac fibrosis, impairs LV function, and increases LV levels of phosphorylated Smad3 (pSmad3), not pSmad1. In contrast, treatment of wild-type mice subjected to transverse aortic constriction with recombinant BMP9 limits progression of cardiac fibrosis, improves LV function, enhances myocardial capillary density, and increases LV levels of pSmad1, not pSmad3 in comparison with vehicle-treated controls. Because endoglin binds BMP9 with high affinity, we explored the effect of reduced endoglin activity on BMP9 activity. Neutralizing endoglin activity in human cardiac fibroblasts or in wild-type mice subjected to transverse aortic constriction-induced heart failure limits collagen production, increases BMP9 protein levels, and increases levels of pSmad1, not pSmad3. CONCLUSIONS: Our results identify a novel functional role for BMP9 as an endogenous inhibitor of cardiac fibrosis attributable to LV pressure overload and further show that treatment with either recombinant BMP9 or disruption of endoglin activity promotes BMP9 activity and limits cardiac fibrosis in heart failure, thereby providing potentially novel therapeutic approaches for patients with heart failure.

Reduced activin receptor-like kinase 1 activity promotes cardiac fibrosis in heart failure.

INTRODUCTION: Activin receptor-like kinase 1 (ALK1) mediates signaling via the transforming growth factor beta-1 (TGFß1), a pro-fibrogenic cytokine. No studies have defined a role for ALK1 in heart failure. HYPOTHESIS: We tested the hypothesis that reduced ALK1 expression promotes maladaptive cardiac remodeling in heart failure. METHODS AND RESULTS: In patients with advanced heart failure referred for left ventricular (LV) assist device implantation, LV Alk1 mRNA and protein levels were lower than control LV obtained from patients without heart failure. To investigate the role of ALK1 in heart failure, Alk1 haploinsufficient (Alk1+/-) and wild-type (WT) mice were studied 2 weeks after severe transverse aortic constriction (TAC). LV and lung weights were higher in Alk1+/- mice after TAC. Cardiomyocyte area and LV mRNA levels of brain natriuretic peptide and ß-myosin heavy chain were increased similarly in Alk1+/- and WT mice after TAC. Alk-1 mice exhibited reduced Smad 1 phosphorylation and signaling compared to WT mice after TAC. Compared to WT, LV fibrosis and Type 1 collagen mRNA and protein levels were higher in Alk1+/- mice. LV fractional shortening was lower in Alk1+/- mice after TAC. CONCLUSIONS: Reduced expression of ALK1 promotes cardiac fibrosis and impaired LV function in a murine model of heart failure. Further studies examining the role of ALK1 and ALK1 inhibitors on cardiac remodeling are required.

Conditional knockout of activin like kinase-1 (ALK-1) leads to heart failure without maladaptive remodeling.

Activin like kinase-1 (AlK-1) mediates signaling via the transforming growth factor beta (TGFß) family of ligands. AlK-1 activity promotes endothelial proliferation and migration. Reduced AlK-1 activity is associated with arteriovenous malformations. No studies have examined the effect of global AlK-1 deletion on indices of cardiac remodeling. We hypothesized that reduced levels of AlK-1 promote maladaptive cardiac remodeling. To test this hypothesis, we employed AlK-1 conditional knockout mice (cKO) harboring the ROSA26-CreER knock-in allele, whereby a single dose of intraperitoneal tamoxifen triggered ubiquitous Cre recombinase-mediated excision of floxed AlK-1 alleles. Tamoxifen treated wild-type (WT-TAM; n = 5) and vehicle treated AlK-1-cKO mice (cKO-CON; n = 5) served as controls for tamoxifen treated AlK-1-cKO mice (cKO-TAM; n = 15). AlK-1 cKO-TAM mice demonstrated reduced 14-day survival compared to cKO-CON controls (13 vs 100%, respectively, p < 0.01). Seven days after treatment, cKO-TAM mice exhibited reduced left ventricular (LV) fractional shortening, progressive LV dilation, and gastrointestinal bleeding. After 14 days total body mass was reduced, but LV and lung mass increased in cKO-TAM not cKO-CON mice. Peak LV systolic pressure, contractility, and arterial elastance were reduced, but LV end-diastolic pressure and stroke volume were increased in cKO-TAM, not cKO-CON mice. LV AlK-1 mRNA levels were reduced in cKO-TAM, not cKO-CON mice. LV levels of other TGFß-family ligands and receptors (AlK5, TBRII, BMPRII, Endoglin, BMP7, BMP9, and TGFß1) were unchanged between groups. Cardiomyocyte area and LV levels of BNP were increased in cKO-TAM mice, but LV levels of ß-MHC and SERCA were unchanged. No increase in markers of cardiac fibrosis, Type I collagen, CTGF, or PAI-1, were observed between groups. No differences were observed for any variable studied between cKO-CON and WT-TAM mice. Global deletion of AlK-1 is associated with the development of high output heart failure without maladaptive remodeling. Future studies exploring the functional role of AlK-1 in cardiac remodeling independent of systemic AVMs are required.

Endoglin selectively modulates transient receptor potential channel expression in left and right heart failure.

INTRODUCTION: Transient receptor potential (TRP) channels are broadly expressed cation channels that mediate diverse physiological stimuli and include canonical (TRPC), melastatin (TRPM), and vanilloid (TRPV) subtypes. Recent studies have implicated a role for TRPC6 channels as an important component of signaling via the cytokine, transforming growth factor beta 1 (TGFß1) in right (RV) or left ventricular (LV) failure. Endoglin (Eng) is a transmembrane glycoprotein that promotes TRPC6 expression and TGFß1 activity. No studies have defined biventricular expression of all TRP channel family members in heart failure. HYPOTHESIS: We hypothesized that heart failure is associated with distinct patterns of TRP channel expression in the LV and RV. METHODS: Paired viable LV and RV free wall tissue was obtained from human subjects with end-stage heart failure (n=12) referred for cardiac transplantation or biventricular assist device implantation. Paired LV and RV samples from human subjects without heart failure served as controls (n=3). To explore a functional role for Eng as a regulator of TRP expression in response to RV or LV pressure overload, wild-type (Eng+/+) and Eng haploinsufficient (Eng+/-) mice were exposed to thoracic aortic (TAC) or pulmonary arterial (PAC) constriction for 8weeks. Biventricular tissue was analyzed by real-time polymerase chain reaction. RESULTS: Compared to nonfailing human LV and RV samples, mRNA levels of TRPC1, 3, 4, 6, and TRPV-2 were increased and TRPM2, 3, and 8 were decreased in failing LV and RV samples. TRPC1 and 6 levels were higher in failing RV compared to failing LV samples. After TAC, murine LV levels of TPRC1 and 6 were increased in both Eng+/+ and Eng+/- mice compared to sham controls. LV levels of TRPC4, TRPM3 and 7, TRPV2 and 4 were increased in Eng+/+, not in Eng+/- mice after TAC. After PAC, all TRP channel family members were increased in the RV, but not LV, of Eng+/+ compared to sham controls. In contrast to Eng+/+, PAC did not increase RV or LV levels of TRP channels in Eng+/- mice. CONCLUSIONS: This is the first study to demonstrate that TRP channels exhibit distinct profiles of expression in the LV and RV of patients with heart failure and in murine models of univentricular pressure overload. We further introduce that the TGFß1 coreceptor Eng selectively regulates expression of multiple TRP channels in the setting of LV or RV pressure overload.