Nuclear GAPDH in cortical microglia mediates cellular stress-induced cognitive inflexibility

We report a mechanism that underlies stress-induced cognitive inflexibility at the molecular level. In a mouse model under subacute cellular stress in which deficits in rule shifting tasks were elicited, the nuclear glyceraldehyde dehydrogenase (N-GAPDH) cascade was activated specifically in microglia in the prelimbic cortex. The cognitive deficits were normalized with a pharmacological intervention with a compound (the RR compound) that selectively blocked the initiation of N-GAPDH cascade without affecting glycolytic activity. The normalization was also observed with a microglia-specific genetic intervention targeting the N-GAPDH cascade. At the mechanistic levels, the microglial secretion of High-Mobility Group Box (HMGB), which is known to bind with and regulate the NMDA-type glutamate receptors, was elevated. Consequently, the hyperactivation of the prelimbic layer 5 excitatory neurons, a neural substrate for cognitive inflexibility, was also observed. The upregulation of the microglial HMGB signaling and neuronal hyperactivation were normalized by the pharmacological and microglia-specific genetic interventions. Taken together, we show a pivotal role of cortical microglia and microglia-neuron interaction in stress-induced cognitive inflexibility. We underscore the N-GAPDH cascade in microglia, which causally mediates stress-induced cognitive alteration.

Inhibitory effects of naringenin on estrogen deficiency-induced obesity via regulation of mitochondrial dynamics and AMPK activation associated with white adipose tissue browning

AIMS

Post-ovariectomy (OVX) changes in hormones induce obesity and white adipose tissue (WAT) inflammation. Increased energy expenditure via WAT browning is a novel therapeutic strategy for treating obesity. Naringenin (NAR) reduces inflammation and lipogenesis in obesity and attenuates estrogen deficiency-associated metabolic disorders; however, its role in WAT browning remains unclear.

MATERIALS AND METHODS

We investigated NAR ability to inhibit estrogen deficiency-associated obesity in vivo using a rat model and in vitro using 3T3-L1 adipocytes.

KEY FINDINGS

NAR significantly decreased the body weight and WAT mass of rats. O2 consumption, CO2 production, and energy expenditure were significantly lower in the OVX group than in the sham group, but NAR treatment reversed these effects of OVX. NAR treatment markedly improved glucose intolerance and lipid profiles as well as leptin, adiponectin, and irisin levels. NAR upregulated markers of browning and mitochondrial biogenesis in inguinal WAT. Moreover, it enhanced markers of mitochondrial fusion and inhibited fission via activating the AMP-activated protein kinase pathway. Similar results were observed in 3T3-L1 adipocytes. Moreover, NAR-induced mitochondrial biogenesis and fusion were suppressed by dorsomorphin (an AMP-activated protein kinase inhibitor).

SIGNIFICANCE

NAR alleviates obesity and metabolic dysfunction through the induction of WAT browning achieved via the modulation of AMP-activated protein kinase-regulated mitochondrial dynamics in WATs. NAR supplementation may therefore represent a potential intervention for preventing postmenopausal adipose tissue dysregulation.

PGC-1α-mediated angiogenesis prevents pulmonary hypertension in mice

Pulmonary hypertension (PH) is a life-threatening disease characterized by a progressive narrowing of pulmonary arterioles. Although VEGF is highly expressed in lung of patients with PH and in animal PH models, the involvement of angiogenesis remains elusive. To clarify the pathophysiological function of angiogenesis in PH, we compared the angiogenic response in hypoxia (Hx) and SU5416 (a VEGFR2 inhibitor) plus Hx (SuHx) mouse PH models using 3D imaging. The 3D imaging analysis revealed an angiogenic response in the lung of the Hx-PH, but not of the severer SuHx-PH model. Selective VEGFR2 inhibition with cabozantinib plus Hx in mice also suppressed angiogenic response and exacerbated Hx-PH to the same extent as SuHx. Expression of endothelial proliferator-activated receptor γ coactivator 1α (PGC-1α) increased along with angiogenesis in lung of Hx-PH but not SuHx mice. In pulmonary endothelial cell-specific Ppargc1a-KO mice, the Hx-induced angiogenesis was suppressed, and PH was exacerbated along with increased oxidative stress, cellular senescence, and DNA damage. By contrast, treatment with baicalin, a flavonoid enhancing PGC-1α activity in endothelial cells, ameliorated Hx-PH with increased Vegfa expression and angiogenesis. Pulmonary endothelial PGC-1α-mediated angiogenesis is essential for adaptive responses to Hx and might represent a potential therapeutic target for PH.

A Pacing-Controlled Procedure for the Assessment of Heart Rate-Dependent Diastolic Functions in Murine Heart Failure Models

Heart failure with preserved ejection fraction (HFpEF) is a condition characterized by diastolic dysfunction and exercise intolerance. While exercise-stressed hemodynamic tests or MRI can be used to detect diastolic dysfunction and diagnose HFpEF in humans, such modalities are limited in basic research using mouse models. A treadmill exercise test is commonly used for this purpose in mice, but its results can be influenced by body weight, skeletal muscle strength, and mental state. Here, we describe an atrial-pacing protocol to detect heart rate (HR)-dependent changes in diastolic performance and validate its usefulness in a mouse model of HFpEF. The method involves anesthetizing, intubating, and performing pressure-volume (PV) loop analysis concomitant with atrial pacing. In this work, a conductance catheter was inserted via a left ventricular apical approach, and an atrial pacing catheter was placed in the esophagus. Baseline PV loops were collected before the HR was slowed with ivabradine. PV loops were collected and analyzed at HR increments ranging from 400 bpm to 700 bpm via atrial pacing. Using this protocol, we clearly demonstrated HR-dependent diastolic impairment in a metabolically induced HFpEF model. Both the relaxation time constant (Tau) and the end-diastolic pressure-volume relationship (EDPVR) worsened as the HR increased compared to control mice. In conclusion, this atrial pacing-controlled protocol is useful for detecting HR-dependent cardiac dysfunctions. It provides a new way to study the underlying mechanisms of diastolic dysfunction in HFpEF mouse models and may help develop new treatments for this condition.

Perivascular adipose tissue in vascular pathologies-a novel therapeutic target for atherosclerotic disease?

Most blood vessels are surrounded by adipose tissues known as perivascular adipose tissue (PVAT). Emerging experimental data have implicated the potential involvement of PVAT in the pathogenesis of cardiovascular disease: PVAT might be a source of inflammatory mediators under pathological conditions such as metabolic disorders, chronic inflammation, and aging, leading to vascular pathologies, while having vasculo-protective roles in a healthy state. PVAT has been also gaining attention in human disease conditions. Recent integrative omics approaches have greatly enhanced our understanding of the molecular mechanisms underlying the diverse functions of PVAT. This review summarizes recent progress in PVAT research and discusses the potential of PVAT as a target for the treatment of atherosclerosis.

Low-carbohydrate diets containing plant-derived fat but not animal-derived fat ameliorate heart failure

Cardiovascular disease (CVD) is a global health burden in the world. Although low-carbohydrate diets (LCDs) have beneficial effects on CVD risk, their preventive effects remain elusive. We investigated whether LCDs ameliorate heart failure (HF) using a murine model of pressure overload. LCD with plant-derived fat (LCD-P) ameliorated HF progression, whereas LCD with animal-derived fat (LCD-A) aggravated inflammation and cardiac dysfunction. In the hearts of LCD-P-fed mice but not LCD-A, fatty acid oxidation-related genes were highly expressed, and peroxisome proliferator-activated receptor α (PPARα), which regulates lipid metabolism and inflammation, was activated. Loss- and gain-of-function experiments indicated the critical roles of PPARα in preventing HF progression. Stearic acid, which was more abundant in the serum and heart of LCD-P-fed mice, activated PPARα in cultured cardiomyocytes. We highlight the importance of fat sources substituted for reduced carbohydrates in LCDs and suggest that the LCD-P-stearic acid-PPARα pathway as a therapeutic target for HF.

NLRP3 Inflammasome Activation Through Heart-Brain Interaction Initiates Cardiac Inflammation and Hypertrophy During Pressure Overload

BACKGROUND

Mechanical stress on the heart, such as high blood pressure, initiates inflammation and causes hypertrophic heart disease. However, the regulatory mechanism of inflammation and its role in the stressed heart remain unclear. IL-1β (interleukin-1β) is a proinflammatory cytokine that causes cardiac hypertrophy and heart failure. Here, we show that neural signals activate the NLRP3 (nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing 3) inflammasome for IL-1β production to induce adaptive hypertrophy in the stressed heart.

METHODS

C57BL/6 mice, knockout mouse strains for NLRP3 and P2RX7 (P2X purinoceptor 7), and adrenergic neuron-specific knockout mice for SLC17A9, a secretory vesicle protein responsible for the storage and release of ATP, were used for analysis. Pressure overload was induced by transverse aortic constriction. Various animal models were used, including pharmacological treatment with apyrase, lipopolysaccharide, 2'(3')-O-(4-benzoylbenzoyl)-ATP, MCC950, anti-IL-1β antibodies, clonidine, pseudoephedrine, isoproterenol, and bisoprolol, left stellate ganglionectomy, and ablation of cardiac afferent nerves with capsaicin. Cardiac function and morphology, gene expression, myocardial IL-1β and caspase-1 activity, and extracellular ATP level were assessed. In vitro experiments were performed using primary cardiomyocytes and fibroblasts from rat neonates and human microvascular endothelial cell line. Cell surface area and proliferation were assessed.

RESULTS

Genetic disruption of NLRP3 resulted in significant loss of IL-1β production, cardiac hypertrophy, and contractile function during pressure overload. A bone marrow transplantation experiment revealed an essential role of NLRP3 in cardiac nonimmune cells in myocardial IL-1β production and cardiac phenotype. Pharmacological depletion of extracellular ATP or genetic disruption of the P2X7 receptor suppressed myocardial NLRP3 inflammasome activity during pressure overload, indicating an important role of ATP/P2X7 axis in cardiac inflammation and hypertrophy. Extracellular ATP induced hypertrophic changes of cardiac cells in an NLRP3- and IL-1β-dependent manner in vitro. Manipulation of the sympathetic nervous system suggested sympathetic efferent nerves as the main source of extracellular ATP. Depletion of ATP release from sympathetic efferent nerves, ablation of cardiac afferent nerves, or a lipophilic β-blocker reduced cardiac extracellular ATP level, and inhibited NLRP3 inflammasome activation, IL-1β production, and adaptive cardiac hypertrophy during pressure overload.

CONCLUSIONS

Cardiac inflammation and hypertrophy are regulated by heart-brain interaction. Controlling neural signals might be important for the treatment of hypertensive heart disease.

The emerging role of estrogen's non-nuclear signaling in the cardiovascular disease

Sexual dimorphism exists in the epidemiology of cardiovascular disease (CVD), which indicates the involvement of sexual hormones in the pathophysiology of CVD. In particular, ample evidence has demonstrated estrogen's protective effect on the cardiovascular system. While estrogen receptors, bound to estrogen, act as a transcription factor which regulates gene expressions by binding to the specific DNA sequence, a subpopulation of estrogen receptors localized at the plasma membrane induces activation of intracellular signaling, called "non-nuclear signaling" or "membrane-initiated steroid signaling of estrogen". Although the precise molecular mechanism of non-nuclear signaling as well as its physiological impact was unclear for a long time, recent development of genetically modified animal models and pathway-selective estrogen receptor stimulant bring new insights into this pathway. We review the published experimental studies on non-nuclear signaling of estrogen, and summarize its role in cardiovascular system, especially focusing on: (1) the molecular mechanism of non-nuclear signaling; (2) the design of genetically modified animals and pathway-selective stimulant of estrogen receptor.

Tie2-Cre-Induced Inactivation of Non-Nuclear Estrogen Receptor-α Signaling Abrogates Estrogen Protection Against Vascular Injury

Using the Cre-loxP system, we generated the first mouse model in which estrogen receptor-α non-nuclear signaling was inactivated in endothelial cells. Estrogen protection against mechanical vascular injury was impaired in this model. This result indicates the pivotal role of endothelial estrogen receptor-α non-nuclear signaling in the vasculoprotective effects of estrogen.

A Pacing-Controlled Protocol for Frequency-Diastolic Relations Distinguishes Diastolic Dysfunction Specific to A Mouse HFpEF Model

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is characterized as an insufficient exercise capacity and is a growing health problem worldwide. One major difficulty with experimental research of HFpEF is the lack of methods to consistently detect diastolic dysfunction in mouse models. We focus on the exercise intolerance and developed a pacing-controlled PV loop protocol for the assessment of diastolic function at different heart rates in mouse cardiac disease models, including a HFpEF model and a pressure-overload hypertrophy model (PO).

METHODS

A HFpEF model was generated by high-fat diet (HFD)-feeding with concomitant L-NAME administration, and a PO model was produced by surgical constriction of transverse aorta (TAC). HR was slowed (lower than 400 bpm) by i.p. injection of ivabradine. PV loop data were acquired at HR incrementing by 100 bpm from 400 to 700 bpm via atrial pacing.

RESULTS

At baseline without pacing, no significant difference was detected between groups. Frequency-diastolic pacing, however, distinguished HFpEF from other two groups in diastolic parameters like tau or stiffness-coefficient of end-diastolic pressure volume relationship. No remarkable difference was observed with systolic parameters.

CONCLUSIONS

Frequency-dependent pressure-volume analysis could detect and characterize diastolic dysfunction specific to the HFpEF, though no significant difference between HFpEF and pressure overload models could be detected at baseline analysis. One of characteristic of HFpEF is exercise intolerance, but no physiological analysis or modality associated with exercise capacity was available in analyzing cardiac functions of murine models. This protocol would significantly contribute to the basic research for HFpEF.

Abstract 354: Beiging Of Perivascular Adipose Tissue Regulates Its Inflammation And Vascular Remodeling

Background: Inflammation plays a primordial role in atherosclerosis. Perivascular adipose tissue (PVAT) that surrounds the vasculature has been reported to undergo phenotypic changes in response to vascular inflammation. However, regulatory roles of PVAT in vascular inflammation and subsequent pathological remodeling remain unclear.

Methods and Results: Endovascular injury was generated by wire insertion into the mice femoral artery. Here, we showed that vascular injury induced the beiging (brown adipose tissue-like phenotype change) of PVAT, which fine-tunes inflammatory response and thus vascular remodeling as a protective mechanism. In a mouse model of endovascular injury, macrophages accumulated in PVAT, causing beiging phenotype change. Inhibition of PVAT beiging by adipose tissue-specific genetic ablation of PRDM16, a key regulator to beiging, exacerbated inflammation and vascular remodeling following injury. Local knockdown of Prdm16 in perivascular tissues of wild-type mice using small interfering RNA similarly exacerbated inflammation and vascular remodeling. Conversely, activation of PVAT beiging attenuated inflammation and pathological vascular remodeling. Single-cell RNA sequencing revealed that beige adipocytes abundantly expressed neuregulin 4 ( Nrg4 ) which critically regulated alternative macrophage activation. Furthermore, Nrg4 knockdown abolished the PVAT-mediated anti-inflammatory effects on macrophages. Importantly, significant beiging was observed in the diseased aortic PVAT in patients with acute aortic dissection.

Conclusions: Endovascular injury induced the beiging of adjacent PVAT with macrophage accumulation, where NRG4 secreted from the beige PVAT facilitated alternative activation of macrophages, leading to the resolution of vascular inflammation. Our study demonstrated the pivotal roles of PVAT in vascular inflammation and remodeling and will open a new avenue for treating atherosclerosis.

Cyclic GMP and PKG Signaling in Heart Failure

Cyclic guanosine monophosphate (cGMP), produced by guanylate cyclase (GC), activates protein kinase G (PKG) and regulates cardiac remodeling. cGMP/PKG signal is activated by two intrinsic pathways: nitric oxide (NO)-soluble GC and natriuretic peptide (NP)-particulate GC (pGC) pathways. Activation of these pathways has emerged as a potent therapeutic strategy to treat patients with heart failure, given cGMP-PKG signaling is impaired in heart failure with reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF). Large scale clinical trials in patients with HFrEF have shown positive results with agents that activate cGMP-PKG pathways. In patients with HFpEF, however, benefits were observed only in a subgroup of patients. Further investigation for cGMP-PKG pathway is needed to develop better targeting strategies for HFpEF. This review outlines cGMP-PKG pathway and its modulation in heart failure.

The mitochondrial regulator PGC1α is induced by cGMP-PKG signaling and mediates the protective effects of phosphodiesterase 5 inhibition in heart failure

Phosphodiesterase 5 inhibition (PDE5i) activates cGMP-dependent protein kinase (PKG) and ameliorates heart failure; however, its impact on cardiac mitochondrial regulation has not been fully determined. Here, we investigated the role of the mitochondrial regulator peroxisome proliferator-activated receptor γ co-activator-1α (PGC1α) in the PDE5i-conferred cardioprotection, utilizing PGC1α null mice. In PGC1α^+/+ hearts exposed to 7 weeks of pressure overload by transverse aortic constriction, chronic treatment with the PDE5 inhibitor sildenafil improved cardiac function and remodeling, with improved mitochondrial respiration and upregulation of PGC1α mRNA in the myocardium. By contrast, PDE5i-elicited benefits were abrogated in PGC1α^-/- hearts. In cultured cardiomyocytes, PKG overexpression induced PGC1α, while inhibition of the transcription factor CREB abrogated the PGC1α induction. Together, these results suggest that the PKG-PGC1α axis plays a pivotal role in the therapeutic efficacy of PDE5i in heart failure.

Sex Differences and Regulatory Actions of Estrogen in Cardiovascular System

Great progress has been made in the understanding of the pathophysiology of cardiovascular diseases (CVDs), and this has improved the prevention and prognosis of CVDs. However, while sex differences in CVDs have been well documented and studied for decades, their full extent remains unclear. Results of the latest clinical studies provide strong evidence of sex differences in the efficacy of drug treatment for heart failure, thereby possibly providing new mechanistic insights into sex differences in CVDs. In this review, we discuss the significance of sex differences, as rediscovered by recent studies, in the pathogenesis of CVDs. First, we provide an overview of the results of clinical trials to date regarding sex differences and hormone replacement therapy. Then, we discuss the role of sex differences in the maintenance and disruption of cardiovascular tissue homeostasis.

Preexisting heart failure with reduced ejection fraction attenuates renal fibrosis after ischemia reperfusion via sympathetic activation

Although chronic heart failure is clinically associated with acute kidney injury (AKI), the precise mechanism that connects kidney and heart remains unknown. Here, we elucidate the effect of pre-existing heart failure with reduced ejection fraction (HFrEF) on kidney via sympathetic activity, using the combining models of transverse aortic constriction (TAC) and unilateral renal ischemia reperfusion (IR). The evaluation of acute (24 h) and chronic (2 weeks) phases of renal injury following IR 8 weeks after TAC in C57BL/6 mice revealed that the development of renal fibrosis in chronic phase was significantly attenuated in TAC mice, but not in non-TAC mice, whereas no impact of pre-existing heart failure was observed in acute phase of renal IR. Expression of transforming growth factor-β, monocyte chemoattractant protein-1, and macrophage infiltration were significantly reduced in TAC mice. Lastly, to investigate the effect of sympathetic nerve activity, we performed renal sympathetic denervation two days prior to renal IR, which abrogated attenuation of renal fibrosis in TAC mice. Collectively, we demonstrate the protective effect of pre-existing HFrEF on long-term renal ischemic injury. Renal sympathetic nerve may contribute to this protection; however, further studies are needed to fully clarify the comprehensive mechanisms associated with attenuated renal fibrosis and pre-existing HFrEF.

Factors associated with left ventricular reverse remodelling after percutaneous coronary intervention in patients with left ventricular systolic dysfunction

Percutaneous coronary intervention (PCI) is sometimes considered as an alternative therapeutic strategy to surgical revascularization in patients with coronary artery disease (CAD) and reduced left ventricular ejection fraction (LVEF). However, the types or conditions of patients that receive the clinical benefit of left ventricular reverse remodelling (LVRR) remain unknown. The purpose of this study was to investigate the determinants of LVRR following PCI in CAD patients with reduced LVEF. From 4394 consecutive patients who underwent PCI, a total of 286 patients with reduced LV systolic function (LVEF < 50% at initial left ventriculography) were included in the analysis. LVRR was defined as LV end-systolic volume reduction ≥ 15% and improvement of LVEF ≥ 10% at 6 months follow-up left ventriculography. Patients were divided into LVRR (n = 63) and non-LVRR (n = 223) groups. Multivariate logistic regression analysis revealed that unprotected left main coronary artery (LMCA) intervention was significantly associated with LVRR (P = 0.007, odds ratios [OR] 4.70, 95% confidence interval [CI] 1.54-14.38), while prior PCI (P = 0.001, OR 0.35, 95% CI 0.19-0.66), presence of in-stent restenosis (P = 0.016, OR 0.32, 95% CI 0.12-0.81), and presence of de-novo stenosis (P = 0.038, OR 0.36, 95% CI 0.14-0.95) were negatively associated with LVRR. These data suggest the potential prognostic benefit of unprotected LMCA intervention for LVRR and importance of angiographic follow-up in patients with CAD and LV systolic dysfunction.

Sex Differences in the Mortality Risk of Elderly Patients with Systolic Heart Failure in Taiwan

Background

Sex differences in heart failure mortality might be affected by age, race, and treatment response. Many large studies in Western countries have shown conflicting results, however few studies have been conducted in Asian patients.

Objectives

We prospectively investigated the mortality risk in a multicenter cohort of 1,093 male and 416 female heart failure patients with reduced ejection fraction (HFrEF) hospitalized for worsening symptoms in Taiwan between 2013 and 2015.

Methods

Kaplan-Meier curve and Cox proportional regression analyses were used to determine the one-year mortality risk by sex.

Results

There were no significant differences in major adverse cardiovascular events, re-admission rate, and mortality between sexes in the overall cohort and the young subgroup during one-year of follow-up. In the elderly subgroup, the overall and cardiac mortality rate of the male patients were higher than those of the female patients (p = 0.035, p = 0.049, respectively). We found that the prognostic effect of old age on overall mortality rate appeared to be stronger in the male patients (p < 0.0001) than in the female patients (p = 0.69) in Cox regression analysis and Kaplan-Meier survival curves. Male sex was a risk factor for all-cause mortality in the elderly (hazard ratio: 1.50, 95% confidence interval 1.02-2.25) independently of systolic blood pressure, diabetes mellitus, hemoglobin concentration, kidney function, and medications.

Conclusions

In the Taiwan HFrEF registry, the highest mortality risk was observed in male patients aged 65 years or more. Clinicians need to pay more attention to these patients.

Inhibition of transforming growth factor-β signaling in myeloid cells ameliorates aortic aneurysmal formation in Marfan syndrome

Increased transforming growth factor-β (TGF-β) signaling contributes to the pathophysiology of aortic aneurysm in Marfan syndrome (MFS). Recent reports indicate that a small but significant number of inflammatory cells are infiltrated into the aortic media and adventitia in MFS. However, little is known about the contribution of myeloid cells to aortic aneurysmal formation. In this study, we ablated the TGF-β type II receptor gene Tgfbr2 in myeloid cells of Fbn1^C1039G/+ MFS mice (Fbn1^C1039G/+;LysM-Cre/+;Tgfbr2^fl/fl mice, hereinafter called Fbn1^C1039G/+;Tgfbr2^MyeKO) and evaluated macrophage infiltration and TGF-β signaling in the aorta. Aneurysmal formation with fragmentation and disarray of medial elastic fibers observed in MFS mice was significantly ameliorated in Fbn1^C1039G/+;Tgfbr2^MyeKO mice. In the aorta of Fbn1^C1039G/+;Tgfbr2^MyeKO mice, both canonical and noncanonical TGF-β signals were attenuated and the number of infiltrated F4/80-positive macrophages was significantly reduced. In vitro, TGF-β enhanced the migration capacity of RAW264.7 macrophages. These findings suggest that TGF-β signaling in myeloid cells promotes aortic aneurysmal formation and its inhibition might be a novel therapeutic target in MFS.

Endothelial-specific Ablation of Non-nuclear Estrogen Receptor alpha Signaling Deteriorates Vascular Remodelling Response

Background and introduction

The difference in cardiovascular disease risk between age-matched women and men narrows as transition through menopause in observational studies. Estrogen exerts complex physiological effects via its non-nuclear and nuclear actions. Experimental studies have shown that endothelial estrogen receptors mediate vasoprotection via endothelial nitric oxide production, reendothelialization, and atherosclerosis. Prior studies in vitro addressed estrogen's effects on endothelial cells and vascular smooth muscle cells, leading to vasoprotection. However, the in vivo evidences are lacking for beneficial effects of endothelium non-nuclear ERα signaling on vascular remodelling in response to injury.

Purpose

This study aims to clarify the impact of endothelial ERα non-nuclear signaling in the vasoprotection, using a novel mouse model lacking tissue-specific ERα non-nuclear signaling.

Methods

We identified the amino acids of ERα which were responsible for its binding to p85α subunit of phosphatidylinositol 3-kinase in vitro. We generated a novel mouse model in which non-nuclear signaling of ERα was ablated in endothelial cells by crossing Tie2-Cre transgenic mice with floxed ERα mutants (RR259/260AA) in which p85α and ERα interaction was disrupted.

Results

In endothelial cells isolated from ERαKI/KITie2 cre/+ animals, E2 failed to induce phosphorylation of Akt, confirming the absence of ERα non-nuclear signaling. Baseline characteristics at 8 to 12 weeks of age were undistinguishable between the genotypes, including body weight, systolic blood pressure, uterine weight and echocardiographic fractional shortening. We then assessed how vascular remodelling process was impacted in a carotid artery wire injury model. Histological analyses with Elastica van Gieson staining two weeks after injury revealed that estrogen dependent suppression of remodelling response (intima to medial ratio) was abolished in ERαki/kiTie2cre/+mice (P=0.0004). Masson's Trichrome staining showed that in the presence of E2 fibrosis was significantly higher in ERαki/kiTie2cre/+ mice than ERαki/kiTie2cre/− mice (P=0.0015).

Conclusions

We generated a novel mouse model for tissue-specific ablation of ERα non-nuclear signaling by interfering ERα-PI3K interaction. Our results demonstrate that the pivotal role for ERα non-nuclear signaling of endothelial cells in carotid arterial protection following injury with its minimal impact on baseline cardiovascular phenotype.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Japan Heart Foundation Research Grant, SENSHIN Medical Research Foundation

Novel procedural method for balloon pulmonary angioplasty to treat chronic thromboembolic pulmonary hypertension

Background

The current strategy of balloon pulmonary angioplasty (BPA) for chronic thromboembolic pulmonary hypertension (CTEPH) is to dilate branches as many as possible without lung injury to normalize mean pulmonary artery pressure and oxygenation. The shape of guiding catheter is one of the important factors to achieve this strategy. However, conventional guiding catheters which are typically used for BPA are difficult to introduce into particular branches. The Ikari-curve left (IL) guiding catheter may be suitable for this purpose by adjusting its curves (Figure 1); however, its utility and effectiveness for lung injury are unclear.

Purpose

The aim of this study is to clarify utility and safety of IL guiding catheter for BPA.

Methods

We retrospectively analyzed 202 consecutive BPA sessions of 40 patients with CTEPH from November 2016 to October 2019 and divided them into two groups; IL group, in which we used IL guiding catheter; and non-IL group in which we used others. IL guiding catheter was used for branches of left lung which are difficult to introduce by conventional catheter prior Nov. 2018. After Nov.2018, we also used it for the same type branches of right lung. The occurrence of lung injury was determined by the presence of bloody sputum during the perioperative period. We compared success rate of introduction into target vessels and of occurrence of lung injury.

Results

The average age of enrolled patients was 60.3±14.4 year-old and female was 65%. There were 99 sessions in IL group. The median treated branches significantly differed between groups (IL group: 15 vs. non-IL group: 10, p&lt;0.05). The lung injury rate tended to low in the IL group (4.0% vs. 11.7%, p=0.07). The IL group had more successful insertions into branches than did the non-IL group (right lung: middle lobe*, 84.4% vs. 57.5%; medial basal branch*, 46.9% vs. 7.5%; left lung: anterior ascending and descending branches, 82.9% vs. 70.8%; lingular branches*, 90.0% vs. 62.5%; anterior basal branch, 75.7% vs. 62.5%, * p&lt;0.05).

Conclusion

IL guiding catheter can be introduced into branches that cannot be accessed via conventional guiding catheters and has potential to reduce the occurrence of lung injury. 2228 characters including space

Figure1

Funding Acknowledgement

Type of funding source: None

Novel Balloon Pulmonary Angioplasty Technique for Chronic Thromboembolic Pulmonary Hypertension

This study aimed to clarify the usefulness of the Ikari-curve left (IL) guiding catheter for balloon pulmonary angioplasty (BPA).The current BPA strategy for chronic thromboembolic pulmonary hypertension is dilation of as many branches as possible to normalize hemodynamics and oxygenation. The shape of the guiding catheter is a major factor in achieving this. However, conventional guiding catheters are difficult to introduce into particular branches. The IL guiding catheter may be suitable; however, its utility remains unclear.We retrospectively analyzed 202 consecutive BPA sessions of 40 patients from November 2016 to October 2019 and divided these sessions into two groups: the IL group where the IL guiding catheter was used and the non-IL group where other catheters were utilized. The occurrence of lung injury was determined by the presence of bloody sputum. We compared the rates of successful introduction into target vessels and assessed for the occurrence of lung injury.The average age of enrolled patients was 60.3 ± 14.4 years, with females comprising 65%. There were 99 sessions in the IL group. The median treated branches per session differed between the 2 groups (IL group: 15 versus non-IL group: 10, P < 0.05). The occurrence of lung injury was lower in the IL group (4.0% versus 11.7%, P = 0.07). The IL group had more successful vessel insertions than the non-IL group (78.8% versus 42.7%, P < 0.01).The IL guiding catheter may be introduced into branches that cannot be accessed by conventional guiding catheters.

Erratum: Diagnosing Heart Failure from Chest X-Ray Images Using Deep Learning

An error appeared in the article entitled "Diagnosing Heart Failure from Chest X-Ray Images Using Deep Learning" by Takuya Matsumoto, Satoshi Kodera, Hiroki Shinohara, Hirotaka Ieki, Toshihiro Yamaguchi, Yasutomi Higashikuni, Arihiro Kiyosue, Kaoru Ito, Jiro Ando, Eiki Takimoto, Hiroshi Akazawa, Hiroyuki Morita, Issei Komuro (Vol. 61, No. 4, 781-786, 2020). The Figure 5on page 784 should be replaced by the following figure.

Omega-3 fatty acid prevents the development of heart failure by changing fatty acid composition in the heart

Some clinical trials showed that omega-3 fatty acid (FA) reduced cardiovascular events, but it remains unknown whether omega-3 FA supplementation changes the composition of FAs and their metabolites in the heart and how the changes, if any, exert beneficial effects on cardiac structure and function. To clarify these issues, we supplied omega-3 FA to mice exposed to pressure overload, and examined cardiac structure and function by echocardiography and a proportion of FAs and their metabolites by gas chromatography and liquid chromatography-tandem mass spectrometry, respectively. Pressure overload induced cardiac hypertrophy and dysfunction, and reduced concentration of all FAs’ components and increased free form arachidonic acid and its metabolites, precursors of pro-inflammatory mediators in the heart. Omega-3 FA supplementation increased both total and free form of eicosapentaenoic acid, a precursor of pro-resolution mediators and reduced free form arachidonic acid in the heart. Omega-3 FA supplementation suppressed expressions of pro-inflammatory cytokines and the infiltration of inflammatory cells into the heart and ameliorated cardiac dysfunction and fibrosis. These results suggest that omega-3 FA-induced changes of FAs composition in the heart have beneficial effects on cardiac function via regulating inflammation.

Diagnosing Heart Failure from Chest X-Ray Images Using Deep Learning

The development of deep learning technology has enabled machines to achieve high-level accuracy in interpreting medical images. While many previous studies have examined the detection of pulmonary nodules in chest X-rays using deep learning, the application of this technology to heart failure remains rare. In this paper, we investigated the performance of a deep learning algorithm in terms of diagnosing heart failure using images obtained from chest X-rays. We used 952 chest X-ray images from a labeled database published by the National Institutes of Health. Two cardiologists verified and relabeled a total of 260 "normal" and 378 "heart failure" images, with the remainder being discarded because they had been incorrectly labeled. Data augmentation and transfer learning were used to obtain an accuracy of 82% in diagnosing heart failure using the chest X-ray images. Furthermore, heatmap imaging allowed us to visualize decisions made by the machine. Deep learning can thus help support the diagnosis of heart failure using chest X-ray images.

Estrogen Receptor-α Non-Nuclear Signaling Confers Cardioprotection and Is Essential to cGMP-PDE5 Inhibition Efficacy

Using genetically engineered mice lacking estrogen receptor-α non-nuclear signaling, this study demonstrated that estrogen receptor-α non-nuclear signaling activated myocardial cyclic guanosine monophosphate-dependent protein kinase G and conferred protection against cardiac remodeling induced by pressure overload. This pathway was indispensable to the therapeutic efficacy of cyclic guanosine monophosphate-phosphodiesterase 5 inhibition but not to that of soluble guanylate cyclase stimulation. These results might partially explain the equivocal results of phosphodiesterase 5 inhibitor efficacy and also provide the molecular basis for the advantage of using a soluble guanylate cyclase simulator as a new therapeutic option in post-menopausal women. This study also highlighted the need for female-specific therapeutic strategies for heart failure.

Overview of the 83rd Annual Scientific Meeting of the Japanese Circulation Society - Renaissance of Cardiology for the Creation of Future Medicine

The 83^rdAnnual Scientific Meeting of the Japanese Circulation Society was held in Yokohama, Japan, on March 29-31, 2019, just as the cherry blossoms came into full bloom. Because the environment around cardiovascular healthcare is rapidly changing, it becomes highly important to make a breakthrough at the dawn of a new era. The main theme of this meeting was "Renaissance of Cardiology for the Creation of Future Medicine". The meeting benefited from the participation of 18,825 people, and there were in-depth and extensive discussions at every session, focusing on topics covering clinical and basic research, medical care provision system, human resource development, and public awareness in cardiovascular medicine. The meeting was completed with great success, and we greatly appreciate the tremendous cooperation and support from all affiliates.

Effectiveness of balloon pulmonary angioplasty in patients with inoperable chronic thromboembolic pulmonary hypertension despite having lesion types suitable for surgical treatment

BACKGROUND

Balloon pulmonary angioplasty (BPA) has been performed in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH). However, some patients have inoperable CTEPH despite having lesions suitable for surgical treatment. The effectiveness of BPA in such cases is unclear. The aim of this study was to clarify the effectiveness of BPA in these cases.

METHODS

We retrospectively investigated patients with inoperable CTEPH and divided them into two groups: BPA-suitable and BPA-unsuitable groups based on the findings of pulmonary angiography, computed tomography, and perfusion scintigraphy. The BPA-unsuitable group included patients whose lesions are suitable for surgical treatment but who did not undergo the procedure for any specified reason. We analyzed the hemodynamic, respiratory, and functional status of the patients before and after BPA.

RESULTS

Forty-three consecutive patients with inoperable CTEPH (age, 62.6 ± 13.5 years; 31 women) were included; all of them underwent BPA. There were 10 patients in the BPA-unsuitable group. In all patients, the mean pulmonary artery pressure, pulmonary vascular resistance, arterial oxygen saturation level, and 6-min walking distance significantly improved after BPA (mean pulmonary artery pressure, from 43.3 ± 7.8 mmHg to 23.9 ± 4.7 mmHg; pulmonary vascular resistance, from 924.1 ± 462.2 dynes/s/cm^-5 to 319.7 ± 163.8 dynes/s/cm^-5; arterial oxygen saturation level, from 89.3 ± 4.3% to 93.4 ± 3.3%; 6-min walking distance, from 370.0 ± 107.4 m to 443.8 ± 101.4 m). Notably, none of the parameters significantly differed between the groups after BPA. Importantly, the amount of lung bleeding did not differ between them. However, several sessions were required in the BPA-unsuitable group (BPA-unsuitable group: six sessions vs. BPA-suitable group: four sessions).

CONCLUSIONS

BPA safely improved the hemodynamic and functional statuses of the patients with CTEPH who are judged as inoperable for any reason despite lesion being suitable for surgical treatment. However, numerous BPA sessions were required in these patients.

Abstract 829: Endothelial Estrogen Non-nuclear Signaling Plays a Key Role in Anti-remodeling Effects via cGMP Signaling in Failing Heart

Background: Estrogen plays a significant role in cardiovascular benefits. As one of its beneficial pathways, ERα non-nuclear signaling is known to be protective for the vascular system, but its role for cardiac remodeling is unknown thus far. We previously reported cGMP pathways are one of the critical therapeutic targets for heart failure and ERα non-nuclear signaling played a pivotal role in cardioprotection and was indispensable to the therapeutic efficacy of cGMP-PDE5 inhibition. However, it is still remaining undetermined which cells are playing the key role in cardioprotective effects via ERα non-nuclear signaling.

Methods: We generated genetically modified mouse lacking ERα in cardiomyocytes (ERα f/f /αMHC Cre/+ ) or endothelial cells (ERα f/f /Tie2 Cre/+ ) and assessed the effects of chronic pressure-overload (TAC) and the efficacy of PDE5 inhibitor (PDE5i) sildenafil after TAC. In addition, for the first time we generated endothelial cell specific genet-modified mouse lacking interactions between p85α and ERα which are critical for non-nuclear signaling (ERα KI/KI /Tie2 Cre/+ ). Cardiac functions were assessed for evaluating the effects of endothelial ERα non-nuclear singlaing to failing hearts.

Results: Under physiological E2 status, PDE5i’s anti-remodeling effects after TAC were abrogated in ERα f/f /Tie2 Cre/+ (FS(%) ± SEM with vs without PDE5i 28.16 ± 3.43 vs 31.87 ± 2.30) but not in ERα f/f /αMHC Cre/+ (FS(%) ± SEM with PDE5i vs without PDE5i 54.57 ± 3.418 vs 43.3 ± 1.21) consistent with hemodynamic analysis. Assessment with ERα KI/KI /Tie2 Cre/+ showed decreased cardiac functions even with physiological E2. Hemodynamic analysis also supported the cardioprotective effects of ERα non-nuclear signaling in endothelial cells.

Conclusion: ERα non-nuclear reaction in endothelial cells plays an important role in cardio-protective mechanism, and endothelial estrogen signals are indispensable to the therapeutic efficacy of cGMP-PDE5 inhibition. Our results clarified one of the cardioprotective signals of estrogen and highlighted the new strategy for heart failure treatment.

Abstract 218: Pathophysiological Significance of Browning of Perivascular Adipose Tissue in the Development of Atherosclerosis

Background: Perivascular adipose tissue (PVAT) possibly plays a pivotal role in the development of atherosclerosis through its direct local action to the vessels. However, its physiological and molecular mechanisms are less understood. Visceral and subcutaneous white adipose tissues exert a brown adipose tissue-like phenotype under specific conditions such as cold exposure, i.e. browning. We here investigated the pathophysiological role of browning of PVAT against the development of atherosclerosis after endovascular injury.

Methods and Results: Endovascular injury was generated by wire insertion into the femoral artery of C57BL/6 female mice. Transcriptome analysis revealed robust upregulation of brown adipose tissue markers such as Ucp1 , Elovl3 , Cox8b and Cidea in injured arteries. Notably, administration of an atheroprotective agent, 17-beta estradiol, significantly inhibited these changes; Ucp1 was the most down-regulated gene by 17-beta estradiol administration in the entire gene set (log2-fold change = -6.58, false discovery rate = 0.003). Consistently, the upregulation of browning markers after endovascular injury and these inhibitions by 17-beta estradiol were confirmed in PVAT by quantitative real-time PCR, western blot and immunohistochemical staining. The present study also demonstrated that vascular injury promotes macrophage infiltration in PVAT accompanied with upregulation of inflammatory cytokine production. Furthermore, we confirmed spatiotemporal synchronicity between browning and inflammation in PVAT by immunohistochemical staining.

Conclusions: We observed that endovascular injury elicits browning in PVAT accompanied with exacerbated inflammation, and that atheroprotective 17-beta estradiol strongly inhibits this phenomenon. These findings may provide novel insights into pathogenesis of the atherosclerosis.

Emergency percutaneous coronary intervention for left main trunk thrombus following orthotopic heart transplantation

Heart transplantation (HTx) is the gold standard therapy to improve quality and quantity of life in end‐stage heart failure patients. However, recipients are at risk of experiencing allograft rejection and post‐transplant complications, in the acute as well as chronic phase. A 43‐year‐old man with a history of left ventricular non‐compaction underwent orthotopic HTx. On Day 7, transthoracic echocardiography showed a sudden decrease in cardiac function with hypokinesis in a left ventricular anterior wall distribution. Coronary angiography revealed a large thrombus in the left main trunk. With intra‐aortic balloon pump support, emergency percutaneous coronary intervention was performed. Endomyocardial biopsy showed no rejection. A left main trunk thrombus is rare in the early phase after HTx, but it can be a life‐threatening complication. Transthoracic echocardiography is well known to be important in the management of heart transplant recipients, and coronary angiography as well as myocardial biopsy should be considered when left ventricular wall motion is impaired.

High-throughput single-molecule RNA imaging analysis reveals heterogeneous responses of cardiomyocytes to hemodynamic overload

BACKGROUND

The heart responds to hemodynamic overload through cardiac hypertrophy and activation of the fetal gene program. However, these changes have not been thoroughly examined in individual cardiomyocytes, and the relation between cardiomyocyte size and fetal gene expression remains elusive. We established a method of high-throughput single-molecule RNA imaging analysis of in vivo cardiomyocytes and determined spatial and temporal changes during the development of heart failure.

METHODS AND RESULTS

We applied three novel single-cell analysis methods, namely, single-cell quantitative PCR (sc-qPCR), single-cell RNA sequencing (scRNA-seq), and single-molecule fluorescence in situ hybridization (smFISH). Isolated cardiomyocytes and cross sections from pressure overloaded murine hearts after transverse aortic constriction (TAC) were analyzed at an early hypertrophy stage (2 weeks, TAC2W) and at a late heart failure stage (8 weeks, TAC8W). Expression of myosin heavy chain β (Myh7), a representative fetal gene, was induced in some cardiomyocytes in TAC2W hearts and in more cardiomyocytes in TAC8W hearts. Expression levels of Myh7 varied considerably among cardiomyocytes. Myh7-expressing cardiomyocytes were significantly more abundant in the middle layer, compared with the inner or outer layers of TAC2W hearts, while such spatial differences were not observed in TAC8W hearts. Expression levels of Myh7 were inversely correlated with cardiomyocyte size and expression levels of mitochondria-related genes.

CONCLUSIONS

We developed a new image-analysis pipeline to allow automated and unbiased quantification of gene expression at the single-cell level and determined the spatial and temporal regulation of heterogenous Myh7 expression in cardiomyocytes after pressure overload.

Regulatory Actions of Estrogen Receptor Signaling in the Cardiovascular System

Premenopausal females have a lower incidence of death from cardiovascular disease (CVD) than male counterparts, supporting the notion that estrogen is protective against the development and progression of CVD. Although large-scale randomized trials of postmenopausal hormone replacement therapy failed to show cardiovascular benefits, recent ELITE study demonstrated anti-atherosclerotic benefits of exogenous estrogen depending on the initiation timing of the therapy. These results have urged us to better understand the mechanisms for actions of estrogens on CVD. Here, we review experimental and human studies, highlighting the emerging role of estrogen's non-nuclear actions linking to NO-cGMP signaling pathways.

Cardiomyocyte gene programs encoding morphological and functional signatures in cardiac hypertrophy and failure

Pressure overload induces a transition from cardiac hypertrophy to heart failure, but its underlying mechanisms remain elusive. Here we reconstruct a trajectory of cardiomyocyte remodeling and clarify distinct cardiomyocyte gene programs encoding morphological and functional signatures in cardiac hypertrophy and failure, by integrating single-cardiomyocyte transcriptome with cell morphology, epigenomic state and heart function. During early hypertrophy, cardiomyocytes activate mitochondrial translation/metabolism genes, whose expression is correlated with cell size and linked to ERK1/2 and NRF1/2 transcriptional networks. Persistent overload leads to a bifurcation into adaptive and failing cardiomyocytes, and p53 signaling is specifically activated in late hypertrophy. Cardiomyocyte-specific p53 deletion shows that cardiomyocyte remodeling is initiated by p53-independent mitochondrial activation and morphological hypertrophy, followed by p53-dependent mitochondrial inhibition, morphological elongation, and heart failure gene program activation. Human single-cardiomyocyte analysis validates the conservation of the pathogenic transcriptional signatures. Collectively, cardiomyocyte identity is encoded in transcriptional programs that orchestrate morphological and functional phenotypes.

Membrane-Initiated Estrogen Receptor Signaling Mediates Metabolic Homeostasis via Central Activation of Protein Phosphatase 2A

Women gain weight and their diabetes risk increases as they transition through menopause; these changes can be partly reversed by hormone therapy. However, the underlying molecular mechanisms mediating these effects are unknown. A novel knock-in mouse line with the selective blockade of the membrane-initiated estrogen receptor (ER) pathway was used, and we found that the lack of this pathway precipitated excessive weight gain and glucose intolerance independent of food intake and that this was accompanied by impaired adaptive thermogenesis and reduced physical activity. Notably, the central activation of protein phosphatase (PP) 2A improved metabolic disorders induced by the lack of membrane-initiated ER signaling. Furthermore, the antiobesity effect of estrogen replacement in a murine menopause model was abolished by central PP2A inactivation. These findings define a critical role for membrane-initiated ER signaling in metabolic homeostasis via the central action of PP2A.

Sildenafil ameliorates right ventricular early molecular derangement during left ventricular pressure overload

Right ventricular (RV) dysfunction following left ventricular (LV) failure is associated with poor prognosis. RV remodeling is thought initiated by the increase in the afterload of RV due to secondary pulmonary hypertension (PH) to impaired LV function; however, RV molecular changes might occur in earlier stages of the disease. cGMP (cyclic guanosine monophosphate)-phosphodiesterase 5 (PDE5) inhibitors, widely used to treat PH through their pulmonary vasorelaxation properties, have shown direct cardiac benefits, but their impacts on the RV in LV diseases are not fully determined. Here we show that RV molecular alterations occur early in the absence of RV hemodynamic changes during LV pressure-overload and are ameliorated by PDE5 inhibition. Two-day moderate LV pressure-overload (transverse aortic constriction) neither altered RV pressure/ function nor RV weight in mice, while it induced only mild LV hypertrophy. Importantly, pathological molecular features were already induced in the RV free wall myocardium, including up-regulation of gene markers for hypertrophy and inflammation, and activation of extracellular signal-regulated kinase (ERK) and calcineurin. Concomitant PDE5 inhibition (sildenafil) prevented induction of such pathological genes and activation of ERK and calcineurin in the RV as well as in the LV. Importantly, dexamethasone also prevented these RV molecular changes, similarly to sildenafil treatment. These results suggest the contributory role of inflammation to the early pathological interventricular interaction between RV and LV. The current study provides the first evidence for the novel early molecular cross-talk between RV and LV, preceding RV hemodynamic changes in LV disease, and supports the therapeutic strategy of enhancing cGMP signaling pathway to treat heart diseases.

Genetic basis of cardiomyopathy and the genotypes involved in prognosis and left ventricular reverse remodeling

Dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM) are genetically and phenotypically heterogeneous. Cardiac function is improved after treatment in some cardiomyopathy patients, but little is known about genetic predictors of long-term outcomes and myocardial recovery following medical treatment. To elucidate the genetic basis of cardiomyopathy in Japan and the genotypes involved in prognosis and left ventricular reverse remodeling (LVRR), we performed targeted sequencing on 120 DCM (70 sporadic and 50 familial) and 52 HCM (15 sporadic and 37 familial) patients and integrated their genotypes with clinical phenotypes. Among the 120 DCM patients, 20 (16.7%) had TTN truncating variants and 13 (10.8%) had LMNA variants. TTN truncating variants were the major cause of sporadic DCM (21.4% of sporadic cases) as with Caucasians, whereas LMNA variants, which include a novel recurrent LMNA E115M variant, were the most frequent in familial DCM (24.0% of familial cases) unlike Caucasians. Of the 52 HCM patients, MYH7 and MYBPC3 variants were the most common (12 (23.1%) had MYH7 variants and 11 (21.2%) had MYBPC3 variants) as with Caucasians. DCM patients harboring TTN truncating variants had better prognosis than those with LMNA variants. Most patients with TTN truncating variants achieved LVRR, unlike most patients with LMNA variants.

Usefulness of central venous saturation as a predictor of thiamine deficiency in critically ill patients: a case report

Background

Central venous oxygen saturation (ScvO₂) reflects the balance of oxygen delivery and consumption. Low ScvO₂ indicates the presence of inadequate oxygen delivery, while high ScvO₂ indicates reduced oxygen consumption and is sometimes associated with a high mortality rate in critically ill patients from dysoxia. Thiamine is an essential cofactor in cellular aerobic metabolism. Thiamine deficiency is more prevalent than was previously thought, and underlies severe conditions in critically ill patients. However, currently, there is no rapid diagnostic test for thiamine deficiency. Considering oxygen flux, high ScvO₂ might be associated with thiamine deficiency.

Case presentation

A 70-year-old man admitted to the hospital with chief complaint of malaise and edema. He was diagnosed with heart failure with preserved ejection function and was treated with loop diuretics, which resulted in shock. Venoarterial extracorporeal membrane oxygenation and intra-aortic balloon pumping was indicated. The right heart catheter showed high ScvO₂, normal cardiac output, and low systemic vascular resistance. Thiamine deficiency was suspected and we started the thiamine infusion. His hemodynamic status improved after thiamine replacement. After his recovery, it was discovered that he had a 1-month history of anorexia and thiamine deficiency. His final diagnosis was beriberi.

Conclusions

The current case showed the relation between thiamine deficiency and high ScvO₂. A literature review also suggested that thiamine deficiency is associated with high ScvO₂. Thiamine deficiency causes impaired tissue oxygen extraction, which could lead to high ScvO₂. In this context, high ScvO₂ might serve as a predictor of thiamine deficiency in critically ill patients.

Successful bridge to recovery in fulminant myocarditis using a biventricular assist device: a case report

Background

Fulminant myocarditis is a life-threatening disease, and myocardial damage expands the right ventricle as well as the left ventricle in some cases. There is a mortality rate of over 40% in patients with fulminant myocarditis who need mechanical circulatory support by peripheral venoarterial extracorporeal membrane oxygenation.

Case presentation

We report a case of a 27-year-old Japanese woman who was successfully bridged to recovery by using a biventricular assist device. She was diagnosed with fulminant myocarditis, and peripheral venoarterial extracorporeal membrane oxygenation was established on the same day. Her left ventricular ejection fraction rapidly decreased from 40% to 5% in 3 days and weaning from venoarterial extracorporeal membrane oxygenation was deemed difficult. Therefore, we performed a ventricular assist device implantation on day 4. A left ventricular assist device was implanted first. However, adequate blood flow did not circulate to the left side of her heart because of right-sided heart failure. Thus, an additional implant of a right ventricular assist device was performed during the operation. Her left ventricular ejection fraction recovered to 50% on day 10. The biventricular assist device was successfully removed on day 14. She has not experienced worsening of biventricular function during her follow-ups for 4 years.

Conclusions

Ventricular assist device therapy should be considered if there is no improvement in cardiac function in patients with fulminant myocarditis regardless of several days of support by venoarterial extracorporeal membrane oxygenation. A right ventricular assist device should always be implemented when necessary because biventricular involvement is not uncommon in fulminant myocarditis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13256-017-1466-1) contains supplementary material, which is available to authorized users.

Nonmyocyte ERK1/2 signaling contributes to load-induced cardiomyopathy in Marfan mice

Among children with the most severe presentation of Marfan syndrome (MFS), an inherited disorder of connective tissue caused by a deficiency of extracellular fibrillin-1, heart failure is the leading cause of death. Here, we show that, while MFS mice (Fbn1C1039G/+ mice) typically have normal cardiac function, pressure overload (PO) induces an acute and severe dilated cardiomyopathy in association with fibrosis and myocyte enlargement. Failing MFS hearts show high expression of TGF-β ligands, with increased TGF-β signaling in both nonmyocytes and myocytes; pathologic ERK activation is restricted to the nonmyocyte compartment. Informatively, TGF-β, angiotensin II type 1 receptor (AT1R), or ERK antagonism (with neutralizing antibody, losartan, or MEK inhibitor, respectively) prevents load-induced cardiac decompensation in MFS mice, despite persistent PO. In situ analyses revealed an unanticipated axis of activation in nonmyocytes, with AT1R-dependent ERK activation driving TGF-β ligand expression that culminates in both autocrine and paracrine overdrive of TGF-β signaling. The full compensation seen in wild-type mice exposed to mild PO correlates with enhanced deposition of extracellular fibrillin-1. Taken together, these data suggest that fibrillin-1 contributes to cardiac reserve in the face of hemodynamic stress, critically implicate nonmyocytes in disease pathogenesis, and validate ERK as a therapeutic target in MFS-related cardiac decompensation.

Aggregation of scaffolding protein DISC1 dysregulates phosphodiesterase 4 in Huntington's disease

Huntington's disease (HD) is a polyglutamine (polyQ) disease caused by aberrant expansion of the polyQ tract in Huntingtin (HTT). While motor impairment mediated by polyQ-expanded HTT has been intensively studied, molecular mechanisms for nonmotor symptoms in HD, such as psychiatric manifestations, remain elusive. Here we have demonstrated that HTT forms a ternary protein complex with the scaffolding protein DISC1 and cAMP-degrading phosphodiesterase 4 (PDE4) to regulate PDE4 activity. We observed pathological cross-seeding between DISC1 and mutant HTT aggregates in the brains of HD patients as well as in a murine model that recapitulates the polyQ pathology of HD (R6/2 mice). In R6/2 mice, consequent reductions in soluble DISC1 led to dysregulation of DISC1-PDE4 complexes, aberrantly increasing the activity of PDE4. Importantly, exogenous expression of a modified DISC1, which binds to PDE4 but not mutant HTT, normalized PDE4 activity and ameliorated anhedonia in the R6/2 mice. We propose that cross-seeding of mutant HTT and DISC1 and the resultant changes in PDE4 activity may underlie the pathology of a specific subset of mental manifestations of HD, which may provide an insight into molecular signaling in mental illness in general.

Hypoxia-Inducible Factor 1α Is a Critical Downstream Mediator for Hypoxia-Induced Mitogenic Factor (FIZZ1/RELMα)-Induced Pulmonary Hypertension

OBJECTIVE

Pulmonary hypertension (PH) is characterized by progressive elevation of pulmonary vascular resistance, right ventricular failure, and ultimately death. We have shown that in rodents, hypoxia-induced mitogenic factor (HIMF; also known as FIZZ1 or resistin-like molecule-β) causes PH by initiating lung vascular inflammation. We hypothesized that hypoxia-inducible factor-1 (HIF-1) is a critical downstream signal mediator of HIMF during PH development.

APPROACH AND RESULTS

In this study, we compared the degree of HIMF-induced pulmonary vascular remodeling and PH development in wild-type (HIF-1α(+/+)) and HIF-1α heterozygous null (HIF-1α(+/-)) mice. HIMF-induced PH was significantly diminished in HIF-1α(+/-) mice and was accompanied by a dysregulated vascular endothelial growth factor-A-vascular endothelial growth factor receptor 2 pathway. HIF-1α was critical for bone marrow-derived cell migration and vascular tube formation in response to HIMF. Furthermore, HIMF and its human homolog, resistin-like molecule-β, significantly increased interleukin (IL)-6 in macrophages and lung resident cells through a mechanism dependent on HIF-1α and, at least to some extent, on nuclear factor κB.

CONCLUSIONS

Our results suggest that HIF-1α is a critical downstream transcription factor for HIMF-induced pulmonary vascular remodeling and PH development. Importantly, both HIMF and human resistin-like molecule-β significantly increased IL-6 in lung resident cells and increased perivascular accumulation of IL-6-expressing macrophages in the lungs of mice. These data suggest that HIMF can induce HIF-1, vascular endothelial growth factor-A, and interleukin-6, which are critical mediators of both hypoxic inflammation and PH pathophysiology.

Molecular Screen Identifies Cardiac Myosin-Binding Protein-C as a Protein Kinase G-Iα Substrate

BACKGROUND

Pharmacological activation of cGMP-dependent protein kinase G I (PKGI) has emerged as a therapeutic strategy for humans with heart failure. However, PKG-activating drugs have been limited by hypotension arising from PKG-induced vasodilation. PKGIα antiremodeling substrates specific to the myocardium might provide targets to circumvent this limitation, but currently remain poorly understood.

METHODS AND RESULTS

We performed a screen for myocardial proteins interacting with the PKGIα leucine zipper (LZ)-binding domain to identify myocardial-specific PKGI antiremodeling substrates. Our screen identified cardiac myosin-binding protein-C (cMyBP-C), a cardiac myocyte-specific protein, which has been demonstrated to inhibit cardiac remodeling in the phosphorylated state, and when mutated leads to hypertrophic cardiomyopathy in humans. GST pulldowns and precipitations with cGMP-conjugated beads confirmed the PKGIα-cMyBP-C interaction in myocardial lysates. In vitro studies demonstrated that purified PKGIα phosphorylates the cMyBP-C M-domain at Ser-273, Ser-282, and Ser-302. cGMP induced cMyBP-C phosphorylation at these residues in COS cells transfected with PKGIα, but not in cells transfected with LZ mutant PKGIα, containing mutations to disrupt LZ substrate binding. In mice subjected to left ventricular pressure overload, PKGI activation with sildenafil increased cMyBP-C phosphorylation at Ser-273 compared with untreated mice. cGMP also induced cMyBP-C phosphorylation in isolated cardiac myocytes.

CONCLUSIONS

Taken together, these data support that PKGIα and cMyBP-C interact in the heart and that cMyBP-C is an anti remodeling PKGIα kinase substrate. This study provides the first identification of a myocardial-specific PKGIα LZ-dependent antiremodeling substrate and supports further exploration of PKGIα myocardial LZ substrates as potential therapeutic targets for heart failure.