The histone methyltransferase SETD2 drives cardiometabolic heart failure with preserved ejection fraction

Background

Heart failure with preserved ejection fraction (HFpEF) is highly prevalent in patients with cardiometabolic disorders and associates with a poor outcome. Pathological gene expression in heart failure is accompanied by changes in active histone marks without major alterations in DNA methylation. Histone 3 trimethylation at lysine 36 (H3k36me3) – an active chromatin mark induced by the methyltransferase SETD2 – was recently found among the top epigenetic signatures in failing human hearts. Yet, the role of SETD2/H3k36me3 in heart failure is poorly understood.

Purpose

To investigate whether SETD2 participates in the transcriptional regulation of cardiometabolic HFpEF.

Methods

Mice with cardiomyocyte-specific deletion of SETD2 (c-SETD2−/−) and control littermates (SETD2fl/fl) were generated and subjected to high fat diet feeding and L-NAME treatment for 15 weeks to induce cardiometabolic HFpEF. Histology, mouse echocardiography (Vevo3100) and Treadmill exhaustion test were performed. ChIP-Seq datasets were employed to determine the biological pathways regulated by H3k36me3, whereas chromatin immunoprecipitation assays (ChIP) were performed to investigate SETD2/H3k36me3 enrichment on gene promoters. SETD2 gain- and loss-of-function experiments were performed in cultured cardiomyocytes (CMs) exposed to palmitic acid. Lipotoxic injury was assessed by mass spectrometry (MS)-based quantification of lipid species, autophagic flux (by Western blot) and apoptosis (by Caspase-3 activity assay). SETD2/H3k36me3 were also investigated in left ventricular myocardial specimens from patients with HFpEF and were correlated to passive stiffness.

Results

ChIP-Seq in mouse CMs showed a strong enrichment of SETD2/H3k36me3 in pathways underpinning triglyceride synthesis. SETD2 and H3k36me3 were upregulated in HFpEF vs. control mouse hearts and were highly enriched on the promoter of sterol regulatory element-binding transcription factor 1 (SREBF1) gene. These changes were associated with SREBF1 upregulation, myocardial triglyceride accumulation and lipotoxic damage. In HFpEF mice, cardiomyocyte-specific deletion of SETD2 prevented hypertrophic remodeling, diastolic dysfunction and lung congestion while improving exercise tolerance. Moreover, SETD2 deletion blunted H3K36me3 enrichment on SREBF1 promoter thus preventing SREBF1-related lipid accumulation, impaired autophagic flux and apoptosis. In cultured CMs exposed to palmitic acid, SETD2 depletion prevented H3k36me3-driven SREBF1 upregulation, whereas SETD2 overexpression recapitulated lipotoxic damage. SREBF1 knockdown prevented lipotoxic injury in SETD2-overexpressing CMs, suggesting its direct role in SETD2 signalling. Finally, SETD2 was upregulated in myocardial samples from obese patients with HFpEF and positively correlated with cardiomyocyte stiffness, a major feature of HFpEF.

Conclusions

SETD2 may represent an attractive molecular target for the prevention of cardiometabolic HFpEF.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): University of Zürich

A methylation-dependent checkpoint by SETD7 promotes myocardial ischemic injury in mice and men

Background

Despite appropriate revascularization strategies, a significant number of patients with myocardial infarction (MI) develop ischemic heart failure suggesting that breakthrough therapies are yet to be approved in this setting. Methylation of non-histone proteins is emerging as a central regulatory mechanism in health and disease. The methyltransferase SETD7 has been shown to methylate and alter the function of a variety of proteins in vitro, however, its function in the heart is poorly understood.

Purpose

To determine the role of SETD7 in myocardial ischemic injury.

Methods

Neonatal rat ventricular myocytes (NRVM) were exposed to normal glucose levels or glucose deprivation (GD) for 15 h, in the presence of the selective SETD7 inhibitor (R)-PFI-2 or its inactive enantiomer (S)-PFI-2. Western blot and real-time PCR were employed to investigate the effects of energy stress on SETD7 and the Hippo pathway, while apoptosis and oxidative stress were assessed by Caspase-3 activity assay and mitoSOX staining. YAP transcriptional activity was assessed by chromatin immunoprecipitation assay (ChIP) while its localization and methylation were examined by confocal microscopy and immunoblotting, respectively. SETD7 knockout (SETD7−/−) mice and wild-type (WT) littermates underwent myocardial ischemia-reperfusion (I/R) injury (1h coronary ligation /24 h of reperfusion) followed by assessment of cardiac function by echocardiography. Left ventricular (LV) myocardial samples were collected from I/R mice and patients with ischemic cardiomyopathy (ICM), and isolated cardiomyocytes were treated with (R)-PFI-2. Finally, SETD7 expression was also assessed in peripheral blood mononuclear cells (PBMCs) from patients with ST-elevation MI (STEMI).

Results

SETD7 was activated upon energy deprivation in cultured NRVMs and methylated YAP, leading to its cytosolic retention and impaired transcription of antioxidant genes MnSOD and CAT. Pharmacological inhibition of SETD7 by (R)-PFI-2 restored YAP nuclear localization thus preventing mitochondrial reactive oxygen species (mtROS) and apoptosis. SETD7 deletion in mice attenuated I/R injury, mtROS and LV dysfunction by restoring YAP-dependent transcriptional programs. SETD7/YAP dysregulation was also observed in LV specimens from ICM patients. Moreover, in cardiomyocytes isolated from I/R mice and ICM patients, (R)-PFI-2 restored YAP nuclear localization, prevented mtROS accumulation while improving myofibrillar protein contractility and Ca2+ sensitivity. Finally, SETD7 was upregulated in PBMCs from STEMI patients and negatively correlated with the expression of MnSOD and CAT.

Conclusions

SETD7-dependent methylation of YAP is an important mechanism underpinning myocardial oxidative stress and apoptosis during ischemia. Pharmacological modulation of SETD7 by (R)-PFI-2 may represent a potential therapeutic approach to prevent myocardial ischemic damage through modulation of the Hippo pathway.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): University of Zurich

Targeting Neurofibromin 2 (NF2) prevents endothelial dysfunction in obesity: a study in mice and humans

Introduction

The mechanisms underlying endothelial dysfunction (ED) in obesity are poorly understood. Neurofibromin 2 (NF2) is a scaffold-like protein involved in cell growth and survival. However, its role in the vascular endothelium is unknown.

Purpose

To investigate NF2 function in obesity-related ED.

Methods

Human aortic endothelial cells (HAECs) were exposed to palmitic acid (PA, 200 uM) or vehicle for 48 hours. Gene silencing of NF2 was performed by small interfering RNA (siRNA). Gene and protein expression were assessed by real time PCR and Western blot, respectively. The interaction of NF2 with endothelial proteins was investigated by co-immunoprecipitation. A constitutive active mutant form of NF2 (Ala518) was employed to study the effects of NF2 gain-of-function. To specifically investigate NF2 role in the vascular endothelium, we generated mice with endothelium-specific deletion of NF2 (NF2 ECKO) by crossing NF2flox/flox mice with tamoxifen-inducible endothelial-specific Cre mice [Cdh5(PAC)-CreERT2]. Endothelium-dependent relaxations to acetylcholine (Ach) were assessed in aortas from NF2 ECKO and wild type (WT) littermates, fed a control and a high fat diet (60 kcal% fat) for 20 weeks. NF2 signalling and endothelial function were also assessed in small visceral fat arteries (VFA) isolated from 18 obese and 18 age-matched healthy subjects undergoing bariatric surgery and cholecystectomy, respectively. Gene in silencing of NF2 by siRNA was performed in VFA from obese patients.

Results

In HAECs, PA promoted NF2 activation by decreasing its phosphorylation at Ser518. Akt and MYPT-1 were responsible for NF2 dephosphorylation. In PA-treated HAECs, NF2 was mainly found in the plasma membrane as compared to other cell fractions. Among different membrane proteins implicated in endothelial homeostasis, NF2 binds and activates Caveolin 1 (Cav-1), a pivotal repressor of endothelial NO synthase (eNOS). NF2 knockdown in PA-treated HAECs prevented eNOS–Cav-1 interaction, thus preserving eNOS activity and NO levels. By contrast, HAECs expressing the constitutive active mutant form of NF2 displayed reduced eNOS activity. In aortas from obese mice, we found that NF2-Cav-1 interaction was responsible for impaired eNOS activity and ED. Cav-1 gene silencing in NF2-overexpressing aortas prevented ED, thus confirming the direct involvement of Cav-1 in NF2-induced ED. Interestingly, Ach-dependent vasorelaxation was preserved in obese NF2 ECKO mice as compared to WT littermates. Moreover, NO bioavailability was preserved in aortas from NF2 ECKO mice. In VFA from obese patients, NF2 was upregulated, and its activity negatively correlated with Ach-dependent vasorelaxation. Of note, NF2 gene silencing in VFA from obese patients rescued ED.

Conclusions

In human endothelial cells, mice with endothelium-specific deletion of NF2 and VFA from obese patients, we show that NF2 drives ED by repressing Cav-1. Targeting NF2 may prevent ED in obese patients.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Holcim Stiftung

Increased Tenascin-C expression contributes to cardiac dysfunction and fibrosis in Duchenne muscular dystrophy

Introduction and aims

Cardiac fibrosis is characterized by the net accumulation of extracellular matrix (ECM) proteins in the cardiac interstitium and contributes to cardiac contractile dysfunction. In Duchenne muscular dystrophy (DMD), cardiomyopathy develops as a result of a dystrophin deficiency causing fibrofatty replacement of the myocardium, however the underlying mechanisms are not fully understood. There is a growing collection of evidence that ECM proteins, including Tenascin C (TN-C), plays a maladaptive role in left ventricular (LV) remodelling and cardiac fibrosis in ischemic heart disease. The aims of our study were 1) to assess TN-C levels, fibrosis and cardiac dysfunction in DMD patients, and 2) to clarify the role of TN-C in cardiovascular dysfunction and fibrosis using male mdx (n=10) and mdx TN-C KO mice (n=8).

Results

In male patients with DMD (n=18) and age matched controls (n=12) undergoing cardiac MRI, we detected greater myocardial fibrosis than in control hearts. In addition, we observed an elevation of TN-C plasma levels [median concentration (3.55); interquartile range (0.61–7.43) ng/mL] in DMD patients, and its expression negatively correlated to LV ejection fraction (EF) [median LVEF (45); interquartile range (37.5–51.5) %]. Male wt, mdx and mdx TN-C KO age-matched (10 months) mice were used. Transthoracic echocardiography was performed and fibrosis was assessed on cardiac tissue sections. Wire myography was used to assess vascular endothelial function. To explore the signalling pathways contributing to cardiac fibrosis, human cardiac fibroblasts (hCFs) were treated with recombinant human TN-C or TGF-β and gene expression and epigenetic regulation of NF-kB/p65 were assessed. Mdx mice showed significantly increased cardiac fibrosis which was accompanied with markedly elevated TN-C level in cardiac tissue and plasma compared to wt animals (p<0.05, respectively). Moreover, TN-C level in plasma correlated positively with the degree of cardiac dilation in dystrophic mice. In addition, vascular endothelial function was notably impaired in mdx mice. In contrast, we observed preserved vascular function in mdx- TN-C KO mice, this was accompanied by a significant reduction in cardiac fibrosis in compared to age-matched mdx mice (p<0.05, respectively). hCFs treated with TN-C or TGF-β showed increased collagen and α-SMA expressions which could be prevented by application of siRNA against TN-C. In addition, both TN-C and TGF-β caused p65/NF-κB promoter demethylation and subsequently triggered pro-inflammatory and pro-fibrotic signalling, which could be reversed by applying p38 MAPK inhibitor in hCFs.

Conclusion

TN-C is a critical component of cardiac fibrosis and cardiac dysfunction in DMD. The activation of NF-κB p65 signalling pathway may play a role in TN-C induced fibrosis. Thus, TN-C may be a mediator and potential target for therapy in DMD-associated cardiovascular complications.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Österreichische MuskelforschungFWF - Austrian Science Found P 35878

A chromatin signature by the methyltransferase SETD7 orchestrates angiogenic response in diabetic limb ischemia

Background

Peripheral artery disease (PAD) is highly prevalent in patients with diabetes (DM) and associates with a high rate of limb amputation and poor prognosis. Surgical and catheter-based revascularization have failed to improve outcome in DM patients with PAD. Hence, a need exists to develop new treatment strategies able to promote blood vessel growth in this setting. Mono-methylation of histone 3 at lysine 4 (H3K4me1) – a specific epigenetic signature induced by the histone methyltransferase SETD7 – favours an open chromatin thus enabling gene transcription.

Purpose

To investigate whether SETD7-dependent epigenetic changes modulate angiogenic response in diabetes.

Methodology

Primary human aortic endothelial cells (HAECs) were exposed to normal glucose (NG, 5 mM) or high glucose (HG, 25 mM) concentrations for 48 hours. Unbiased gene expression profiling was performed by RNA sequencing (RNA-seq) followed by Ingenuity Pathway Analysis (IPA). In vitro assays, namely cell migration and tube formation were employed to study angiogenic properties in HAECs. SETD7 and H3K4me1 levels were investigated by Western blot and Chromatin immunoprecipitation (ChIP). Pharmacological blockade of SETD7 was achieved by using the highly selective inhibitor (R)-PFI-2. Mice with streptozotocin-induced diabetes were orally treated with (R)-PFI-2 or vehicle and underwent hindlimb ischemia by femoral artery ligation for 14 days. Blood flow recovery was analysed at 30 minutes, 7 and 14 days by laser Doppler imaging. Our experimental findings were also translated in gastrocnemius muscle samples from patients with and without diabetes.

Results

RNA-seq in HG-treated HAECs revealed a profound upregulation of the methyltransferase SETD7, an enzyme involved in mono-methylation of lysine 4 at histone 3 (H3K4me1). SETD7 upregulation in HG-treated HAECs was associated with increased H3K4me1 levels as well as with impaired endothelial cell migration and tube formation. Both SETD7 gene silencing and pharmacological inhibition by (R)PFI-2 rescued hyperglycemia-induced impairment of HAECs migration and tube formation, while SETD7 overexpression blunted the angiogenic response. RNA-seq and ChIP assays showed that SETD7-dependent H3K4me1 regulates the transcription of the angiogenesis inhibitor semaphorin-3G (SEMA-3G). Moreover, SEMA-3G overexpression blunted migration and tube formation in SETD7-depleted HAECs. In diabetic mice with hindlimb ischemia, treatment with (R)-PFI-2 improved limb vascularization and perfusion as compared to vehicle. Finally, SETD7/SEMA3G axis was upregulated in muscle specimens from T2D patients as compared to controls.

Conclusion

Targeting SETD7 represents a novel epigenetic-based therapy to boost neovascularization in diabetic patients with PAD.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): University of Zurich - Forshungskredit candoc grant

A chromatin mark by SETD7 regulates myocardial inflammation in obesity-related heart failure with preserved ejection fraction

Background

Obesity is a major risk factor for heart failure with preserved ejection fraction (HFpEF). Post-translational modification of histones by chromatin modifying enzymes (CMEs) are emerging as pivotal regulators of gene transcription in cardiovascular disease.

Purpose

To investigate the role of chromatin remodelling in obese HFpEF (obHFpEF).

Methods

Gene expression profiling of CMEs (PCR array) was performed in left ventricular (LV) myocardial specimens from obHFpEF patients and age-matched control donors (n=8/group). Among myocardial CMEs, the methyltransferase SETD7 showed the highest variation in gene expression. Hence, we investigated the role of SETD7 and its chromatin mark H3K4me1 in a murine model of obHFpEF. Mice with cardiomyocyte-specific deletion of SETD7 (c-SETD7−/−) and control littermates (SETD7fl/fl) were subjected to high fat diet feeding and L-NAME treatment for 15 weeks to induce obHFpEF. Echocardiography and Treadmill exhaustion test were performed. ChIP-Seq datasets were employed to determine the biological pathways regulated by SETD7, whereas chromatin immunoprecipitation assays (ChIP) were performed to investigate SETD7/H3k4me1 enrichment on target gene promoters. SETD7 gain- and loss-of-function experiments were performed in cultured neonatal rat ventricular myocytes (NRVMs) exposed to palmitic acid (200μM) for 48h. Selective inhibition of SETD7 by (R)-PFI-2 was performed in skinned cardiomyocytes isolated from left ventricular specimens of obHFpEF patients. Passive stiffness, a main feature of HFpEF, was assessed before and after (R)-PFI-2 treatment.

Results

CMEs profiling showed SETD7 as the top-ranking transcript (fold change, 7.36, P<0.01) in myocardial specimens from obHFpEF patients as compared to controls. ChIP-Seq in CMs showed a strong enrichment of SETD7 and H3k4me1 on the promoter of NF-kB p65 gene, a master regulator of inflammation. SETD7 and H3k4me1 were upregulated in HFpEF vs. control mouse hearts, showed enrichment on NF-kB p65 promoter and were associated with IL-1β and IL-6 upregulation. In HFpEF mice, cardiomyocyte-specific deletion of SETD7 protected against LV hypertrophy, diastolic dysfunction (assessed by E/E' ratio) and lung congestion while improving exercise tolerance. At the molecular level, SETD7 deletion blunted H3K4me1 enrichment on p65 promoter thus preventing the upregulation of inflammatory genes and myocardial apoptosis. In cultured CMs exposed to PA, SETD7 inhibition by (R)-PFI-2 prevented H3k4me1-driven p65 upregulation, whereas SETD7 overexpression mimicked HFpEF features. Moreover, knockdown of NF-kB p65 prevented IL-1β/IL-6 transcription in SETD7-overexpressing CMs. Of clinical relevance, (R)-PFI-2 reduced passive stiffness in skinned CMs isolated from obHFpEF patients.

Conclusions

Our results unveil a new epigenetic mechanism underpinning inflammation in obHFpEF. Targeting SETD7 may represent a novel therapeutic approach to prevent HFpEF in obesity.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swiss National Science Foundation

Tenascin-C provokes cardiac fibrosis and endothelial impairment in Duchenne Muscular Dystrophy

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): FWF Austrian Science Fund

Cardiac fibrosis and dilated cardiomyopathy are major contributors to mortality in Duchenne muscular dystrophy (DMD) patients. There is a growing collection of evidence that Tenascin C (TN-C) plays a maladaptive role in cardiac remodelling and fibrosis.

Our aims were to 1) assess the vascular dysfunction and cardiac fibrosis and its link to TN-C in a mouse model of DMD and 2) explore the effect of knocking out TN-C in dystrophic mice.

Male wt, mdx and mdx TN-C KO age-matched mice were used. Cardiac fibrosis was assessed on tissue sections. Wire myography was used to test the vascular reactivity and endothelial cells (ECs) were isolated from mouse lung tissues to characterize the oxidative stress and inflammatory marker expression. To study the signalling pathways contributing to cardiac fibrosis, human cardiac fibroblasts (hCFs) were treated with TN-C or TGF-β and gene expression and epigenetic regulation of p65 were assessed.

Cardiac fibrosis was markedly increased in mdx mice which was accompanied with elevated TN-C level in cardiac tissue and plasma compared to wt animals. In addition, endothelial cells isolated from mdx mice also showed a marked upregulation of oxidative stress and inflammatory markers and in line with that vascular endothelial function was impaired in mdx mice. Interestingly, mdx- TN-C KO mice showed preserved vascular function as well as reduced cardiac fibrosis compared to age-matched mdx mice. hCFs treated with TN-C or TGF-β showed increased collagen and α-SMA expressions which could be reduced by TN-C siRNA. In addition, both TN-C and TGF-β promote p65/NF-κB promoter demethylation and subsequently stimulate pro-inflammatory and pro-fibrotic signalling, which could be reversed by applying p38 MAPK inhibitor in hCFs.

TN-C promotes oxidative stress and inflammation in ECs and fibroblasts, contributing to severe endothelial dysfunction and cardiac fibrosis. In addition, activation of NF-κB p65 signalling pathway may play a role in TN-C induced fibrosis. Thus, TN-C may be a critical mediator and potential target for therapy in DMD.

Access site bleeding complications comparing oral anticoagulation therapy with NOACs and VKAs in patients with atrial fibrillation undergoing cardiac implantable device intervention

Funding Acknowledgements

Type of funding sources: None.

Background

Atrial fibrillation is frequent in patients undergoing cardiac implantable electronic device (CIED) intervention. Such population require oral anticoagulation therapy, which increases risk of procedure related bleeding. There is a lack on data on procedure-related bleeding outcome with non-vitamin K antagonist anticoagulants (NOACs) vs vitamin K antagonist anticoagulants (VKAs) in patients with AF undergoing CIED intervention.

Study purpose

Aim of the present stud was to evaluate whether NOACs have a safety benefit compared to VKAs in terms of fewer hemorrhagic complications at the site of CIED implant.

Methods

Consecutive AF patients receiving NOACs or VKAs at the time of CIED procedure were included in this observational, retrospective, monocentric investigation. Primary endpoint was the incidence of post-intervention clinically significant pocket hematoma. Multivariate analysis was performed to investigate the association between covariates and the primary endpoint.

Results

A total of 311 patients were enrolled, 146 on NOACs and 165 on VKAs. The incidence of pocket hematoma was 3.4% in the NOAC vs 13.3% in the VKA group (p=0.002) (Figure 1). Primary outcome-free survival at 30-days was 96.6 % in patients on NOACs and 86.0% in those on VKAs (p=0.019) (Figure 2). Multivariate analysis, adjusted by propensity-score calculation of inverse-probability-weighting, showed a significantly lower occurrence of pocket hematoma in patients receiving NOACs vs VKAs (HR 0.35, 95% CI 0.13-0.96, p=0.042). Such NOACs benefit was confirmed vs patients on VKAs without peri-procedural bridging with low-molecular weight heparin (HR 0.34, 95% CI 0.11-0.99, p=0.048). The incidence of pocket infection, surgical pocket evacuation, ischemic events and major bleeding complications at 30 days (secondary endpoints) was similar in the two groups.

Conclusion

Among patients with AF undergoing implantable cardiac defibrillator or pace-maker intervention, the use of NOACs vs VKAs is associated with significant reduction of post-procedural pocket hematoma, regardless of bridging with low molecular-weight heparin in the VKA group.

Targeting the methyltransferase setd7 prevents myocardial ischemic injury: a translational study

Background

Despite appropriate revascularization strategies, a significant number of patients with myocardial infarction (MI) develop ischemic heart failure suggesting that breakthrough therapies are yet to be approved in this setting. Methylation of non-histone proteins is emerging as a central regulatory mechanism in health and disease. The methyltransferase SETD7 has shown to methylate and alter the function of a variety of proteins in vitro, however its function in the heart is poorly understood.

Purpose

In the present study we sought to determine the role of SETD7 in myocardial ischemic injury.

Methods

Neonatal rat ventricular myocytes (NRVM) were exposed to glucose deprivation (GD) for 15 h, in the presence of the selective SETD7 inhibitor [(R)-PFI-2] or its inactive enantiomer [(S)-PFI-2]. Western blot and real time PCR were employed to investigate the effects of energy stress on SETD7 and the Hippo pathway, while apoptosis and oxidative stress were assessed by Caspase-3 activity assay and mitochondrial swelling. YAP activity was assessed through chromatin immunoprecipitation assay (ChIP), its localization was examined by confocal microscopy while mono-methylation was assessed by immunoblotting. Expression of YAP-dependent antioxidant genes was assessed by western blot. SETD7 knockout (SETD7−/−) mice and wild-type (WT) littermates underwent ischemia/reperfusion (I/R) injury. Rats underwent permanent ligation of left anterior descending coronary artery (MI). Left ventricular (LV) myocardial samples were collected from mice undergoing I/R injury and patients with ischemic cardiomyopathy (ICM) and treated ex-vivo with (R)-PFI-2. SETD7 and antioxidant genes expression was assessed in peripheral blood mononuclear cells (PBMCs) from patients with ST-elevation MI (STEMI).

Results

We show that SETD7 is activated upon energy deprivation in cultured NRVMs and methylates the Hippo pathway effector YAP, leading to its cytosolic retention and impaired transcription of antioxidant genes. Pharmacological inhibition of SETD7 by (R)-PFI-2 restored YAP nuclear localization thus preventing mitochondrial reactive oxygen species (mtROS) and apoptosis. SETD7 deletion in mice attenuated I/R injury, mtROS and LV dysfunction by restoring YAP-dependent transcriptional programs. SETD7/YAP dysregulation was also observed in rats with MI and LV specimens from ICM patients. Of note, (R)-PFI-2 treatment prevented titin oxidation and myofilament stiffness in cardiomyocytes isolated from I/R mice and patients with ICM. Finally, SETD7 was upregulated in STEMI patients and its expression negatively correlated with antioxidant genes.

Conclusions

Targeting SETD7 may represent a valid therapeutic strategy to protect the heart during ischemia.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): University of Zurich

Abstract SP112: Spatial variance signatures/Intra-tumor zonation in TNBC

It is increasingly clear that triple negative breast cancer (TNBC) is a heterogeneous disease with variable clinical presentation, histological features and response to therapy. While these differences have been partially explained by inter- and intra-tumoral heterogeneity, spatial heterogeneity represented by the tumor architecture plays a critical role in clonal evolution and displays a landscape for different compartment-specific processes and cell-to-cell specific interactions. To better understand the impact of spatial heterogeneity on gene-expression-defined cell populations, we have coupled single-cell RNA sequencing with multiplex immunofluorescence (IF). Multiplex immunofluorescence using specific markers for each cell cluster, integrated with computational image analyses and neighborhood maps, has revealed spatial zonation of single cell subpopulations. Zonation of single cell populations was coupled to hypoxia and overlayed distinct metabolic tumor zones and defined areas of differential stress and cell plasticity that give rise to tumor cells with enhanced fitness and aggressivity.

Citation Format: M Park, C Martínez Ramirez, Y Yang, A Blanchet-Cohen, H Kuasne, A Fortier, J Ragoussis, P Savage, A Omeroglou, S Meterissian, S Costantino, C Kleinman. Spatial variance signatures/Intra-tumor zonation in TNBC [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr SP112.

A chromatin signature by the methyltransferase SETD7 regulates semaphorin-3G transcription and angiogenic response in diabetes: insights for personalized epigenetic therapies

Background

Despite advances in revascularization strategies, type 2 diabetic (T2D) patients with peripheral artery disease (PAD) continue to have a high risk of limb amputation. Modulation of blood vessel growth holds great promise for the treatment of PAD patients. Epigenetic modifications, namely histone post-translational modifications, have shown to regulate transcriptional programs implicated in the pathogenesis of cardiovascular disease.

Aim

To investigate the role of chromatin changes in regulating post-ischemic vascularization in experimental diabetes as well as in patients with T2D.

Methods

Experiments were performed in primary human aortic endothelial cells (HAECs), double-mutant leptin deficient mice (Lepdb/db) carrying a genetic deletion of the methyltransferase SETD7 (Setd7−/−Lepdb/db) as well as in gastrocnemius muscle samples from T2D patients with PAD and age-matched non-diabetic controls. Unbiased gene expression profiling was performed by RNA sequencing (RNA-seq) followed by Ingenuity Pathway Analysis (IPA). Pharmacological blockade of SETD7 was performed by using the selective inhibitor (R)-PFI-2. Scratch and tube formation assays were performed to investigate the impact of SETD7 on angiogenic response.

Results

RNA-seq in high glucose-treated HAECs revealed a profound upregulation of the methyltransferase SETD7 (fold change 2.8, p<0.001), an enzyme involved in mono-methylation of lysine 4 at histone 3 (H3K4me1). Both SETD7 gene silencing and pharmacological inhibition by (R)PFI-2 rescued hyperglycemia-induced impairment of HAECs migration and tube formation, while SETD7 overexpression blunted the angiogenic response. RNA-seq and Chromatin Immunoprecipitation (ChIP) assays showed that SETD7-dependent H3K4me1 regulates the transcription of the angiogenesis inhibitor semaphorin-3G (SEMA-3G). Increased SEMA-3G transcript was associated with enhanced secretion from HAECs. Co-immunofluorescence experiments showed that SEMA-3G blunts the angiogenic response by competing with VEGF receptors VEGFR/Neuropillin2. Moreover, SEMA-3G overexpression blunted migration and tube formation in SETD7-depleted HAECs. SETD7 and SEMA-3G were significantly upregulated in endothelial cells from Lepdb/db mice, whereas SEMA-3G transcription was blunted in Setd7−/−Lepdb/db animals. Consistently, endothelial sprouting was defective in aortas from Lepdb/db as compared to WT mice, whereas Setd7−/−Lepdb/db mice displayed a preserved angiogenic response. Of clinical relevance, SETD7/SEMA-3G axis was upregulated in gastrocnemius muscle specimens from T2D patients with PAD as compared with non-diabetic controls.

Conclusion

In HAECs, genetically modified mice and T2D patients we show that SETD7-dependent chromatin changes regulate SEMA-3G transcription and angiogenic response. Pharmacological inhibition of SETD7 may represent a novel epigenetic therapy to boost neovascularization in T2D patients with PAD.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): University of Zurich/Universitätsspital Zürich

miR-673/menin/JunD axis modulates hyperglycemia-induced oxidative stress and inflammation in the diabetic heart

Background

Hyperglycemia-induced reactive oxygen species generation in diabetic heart contributes to myocardial dysfunction. JunD, a member of the activated protein 1 (AP-1) family of transcription factors, is emerging as a major gatekeeper against oxidative stress. Previous studies have shown that downregulation of AP-1 transcription factor JunD is involved in vascular aging and heart failure. However, the role of JunD in diabetes-induced myocardial dysfunction is unknown.

Purpose

The present study was designed to investigate whether hyperglycemia-driven epigenetic regulation of JunD contributes to oxidative stress, inflammation and myocardial dysfunction in the diabetic heart.

Methods

Diabetes (DB) was induced in C57BL/6 wild-type (WT) mice by streptozotocin. After four weeks of DB, left ventricular (LV) function was assessed by standard and 2D speckle-tracking echocardiography in both groups (n=10). Then, the animals were euthanized and LV specimens were collected to determine JunD mRNA and protein expression as well as superoxide anion production by ESR spectroscopy. Chromatin modifications of JunD gene promoter were assessed by chromatin immunoprecipitation. Isolated DNA was analyzed for promoter methylation following Methylminer kit. Cardiac biopsies were collected from age-matched patients with and without diabetes.

Results

DB mice showed LV dysfunction with reduced ejection fraction and fractional shortening. JunD mRNA and protein expression were reduced in the myocardium of DB as compared to control mice. JunD downregulation was associated with oxidative stress, increased NF-kB binding activity and expression of inflammatory mediators. Accordingly, expression of free radical scavenger superoxide dismutase 1 and aldehyde dehydrogenase 2 was reduced, whereas nicotinamide adenine dinucleotide phosphate oxidase subunits NOX2 and NOX4 were upregulated in DB. A reduction of JunD mRNA and protein expression was confirmed in LV specimens obtained from patients with diabetes. The downregulation of JunD was epigenetically regulated by promoter hypermethylation and histone modifications. Post-translational repression by tumor suppressor menin also contributed to JunD downregulation. Indeed, menin was significantly upregulated in DB hearts and co-immunoprecipitation experiments confirmed the binding of menin to JunD. Furthermore, rat ventricular myocytes exposed to high glucose (HG) showed increased menin expression. We found that miR-673 targeting menin was downregulated in hearts of DB mice. Reprogramming miR-673 in HG-treated myocytes was able to restore both menin and JunD expression to control levels.

Conclusions

Our findings show that downregulation of AP-1 transcription factor JunD contributes to diabetes-induced myocardial dysfunction and miR-673/menin/JunD represents a novel molecular axis involved in hyperglycemia-induced ROS-driven cardiac damage.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): European Society of Cardiology (ESC) Research Grant 2017

Methylation of the hippo signalling effector YAP by SETD7 drives myocardial ischemic injury

Introduction

Myocardial ischemia/reperfusion (I/R) injury is one of the most deleterious cardiovascular conditions and a leading cause of mortality. The Hippo pathway effector YAP critically regulates cardiomyocyte proliferation and survival during myocardial I/R injury. However, the mechanisms regulating YAP activation in this setting remain poorly understood. Post-translational modifications of proteins, namely methylation, modulate pathways implicated in myocardial I/R injury. The methyltransferase SETD7 is emerging as a regulator of cell survival via methylation of histone and non-histone proteins. Whether SETD7 participates to myocardial I/R injury remains elusive.

Purpose

To investigate the role of SETD7 in regulating Hippo signaling during myocardial I/R injury.

Methods

Neonatal rat ventricular myocytes (NRVM) were exposed to normal glucose levels or glucose deprivation (GD) for 15 h, in the presence of the selective SETD7 inhibitor [(R)-PFI-2] or its inactive enantiomer [(S)-PFI-2]. Western blot and real time PCR were employed to investigate the effects of energy stress on SETD7 and the Hippo pathway, while apoptosis was assessed by Caspase-3 activity assay. YAP activity was assessed through chromatin immunoprecipitation assay (ChIP), its localization was examined by confocal microscopy while mono-methylation was assessed by immunoblotting. SETD7 knockout (SETD7−/−) mice and wild-type (WT) littermates (male, 8–12 weeks old) underwent 1 h of left anterior descending (LAD) coronary artery ligation followed by 24 h of reperfusion. Infarct size was assessed by TTC staining and shown as infarct size per ventricle surface (I/V). Cardiac function was investigated at 24h by conventional and Tissue Doppler Imaging (TDI) echocardiography.

Results

GD in NRVMs led to upregulation of SETD7 and physical interaction with the pro-survival transcriptional cofactor YAP, resulting in its direct mono-methylation. Furthermore SETD7-dependent methylation of YAP led to its cytosolic retention and subsequent reduction of YAP binding to the promoter of pro-survival genes. Of note, pharmacological inhibition of SETD7 by (R)-PFI-2 blunted YAP mono-methylation while restoring its nuclear retention. Mechanistically, SETD7 inhibition promoted YAP binding to catalase and superoxide dismutase (SOD) gene promoters, thus preventing GD-induced mitochondrial oxidative stress and apoptosis. In line with our in vitro findings, SETD7−/− mice showed decreased infarct size as compared to WT littermates and preserved cardiac systolic (ejection fraction, fractional shortening) and diastolic function, as assessed by both conventional and TDI echocardiography.

Conclusions

We show that SETD7-dependent methylation of YAP is required for its inactivation, thus leading to myocyte oxidative stress and apoptosis. Pharmacological modulation of SETD7 by (R)-PFI-2 may represent a new therapeutic approach to prevent myocardial ischemic damage through modulation of the Hippo pathway.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Swiss Heart Foundation

Baseline interleukin1beta expression in peripheral blood monocytes predicts the extent of weight loss and nonalcoholic fatty liver improvement in obese subjects with prediabetes or type 2 diabetes

Background

Non-alcoholic fatty liver disease (NAFLD) represents a hallmark of metabolic syndrome. Interleukin-1β (IL-1β), a well-studied cytokine involved in obesity-related systemic inflammation as well as in the pathogenesis of type 2 diabetes (T2D), promotes hepatic steatosis by stimulating triglycerides and cholesterol accumulation in primary liver hepatocytes and lipid droplets formation. The most compelling evidence for a major role for IL-1β in metabolic imbalance and inflammation comes from the recent Canakinumab Anti-inflammatory Thrombosis Outcome (CANTOs)trial, where inhibition of IL-1β pathway was associated with a reduction of cardiovascular events in high-risk patients.

Purpose

The present study was designed to determine: i)whether an equal degree of weight loss by liraglutide or lifestyle changes has a different impact on NAFLD extent and IL-1β expression in peripheral blood mononuclear cells from obese subjects with prediabetes or early T2D; ii)whether baseline IL-1β levels may predict the extent of weight loss and related metabolic changes.

Methods

Thirty-two metformin-treated obese subjects with prediabetes [impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) or both (n=16)] or newly diagnosed T2D (n=16), were randomized to the glucagon-like peptide receptor agonist (GLP-RA) liraglutide (1.8 mg/d) or lifestyle counselling until achieving a modest and comparable weight loss (−7% of initial body weight). Visceral (VAT) and adipose tissue distribution were assessed by magnetic resonance. Gene expression of IL-1β in peripheral blood mononuclear cells was assessed by real time PCR.

Results

At baseline, IL-1β positively correlated to body mass index (BMI) (rho=0.421, p=0.016), fasting plasma glucose (rho=0.415, p=0.018), HbA1c (rho=0.349, p=0.050), VAT (rho=0.388, p=0.028), NAFLD (rho=0.454, p=0.009), platelet count (rho=0.510, p=0.003), chemerin (rho=0.455, p=0.009) and interleukin-1 receptor agonist (IL1-RA) (rho=0.519, p=0.002). After achievement of the weight loss target in the two groups, a comparable reduction of IL-1 β (p<0.001 lifestyle changes; p=0.029 liraglutide treatment) was observed in both arms, in parallel with a comparable improvement in glycaemic control, C-reactive protein (CRP),BMI and NAFLD. Furthermore, basal levels of IL-1β correlated directly with delta BMI (p=0.015) and delta NAFLD (p=0.002) (Figure 1).

Conclusion

In obese patients with initial impairment of glucose metabolism, IL-β-driven inflammation correlates with glycaemic control, adipose tissue distribution and platelet count. Successful weight loss, achieved with either lifestyle changes or an incretin-based therapy, is associated with a significant reduction of both IL-1β levels and NAFLD degree. Of interest, basal levels of IL-1β predicts the extent of weight loss and NAFLD improvement, regardless of the intervention. Our results may set the stage for ad-hoc studies investigating the usefulness of baseline IL-1β a levels as a drug-response biomarker.

Figure 1

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): This study was supported by a grant from the Italian Ministry of University and Research (PRIN no. 2010JS3PMZ to F.S.).

IL-23 promotes T-cell mediated cardiac inflammation but protects the heart from fibrosis

Introduction

Cardiac inflammation varies widely and, in some cases, triggers autoimmune myocarditis and further inflammatory dilated cardiomyopathy (iDCM) and heart failure. In children, myocarditis leads to cardiomyopathy in almost half of affected individuals and up to 20% of sudden death cases in young adults have been reported to be due to myocarditis. IL-12 and IL-23 belong to the same family of cytokines known to mediate inflammatory conditions. Both regulate the differentiation of T cells: IL-12 promotes towards IFN-gamma-producing Th-1 cells, while IL-23 induces IL-17-producing Th-17 cells. Heart-reactive CD4+Th17 cells play a leading role in the development of myocarditis, however, literature reports excessiveness of IL-23 in Th17-derived IL-17 production. Therapeutic strategies blocking IL-23 were suggested as a promising approach, though the specific role of IL-23 in pathogenesis is unclear and the long-term perspectives stay elusive.

Purpose

We aim to explore the role IL-23 compared to IL-12 in the manifestation of cardiac autoimmune myocarditis.

Methodology

We use dendritic cell (DC) model of experimental autoimmune myocarditis in IL-12 and IL-23-deficient mice. Mice were injected with bone marrow-derived in vitro activated and loaded with cardiac-specific peptide DCs. This model mimics natural processes taking place during heart inflammation and provides a unique method to address the role of DCs-derived cytokines. Cardiac inflammation, as well as remodeling and heart function, were analysed at the acute and chronic stages of the disease.

Results

Surprisingly, all mice developed acute myocarditis, though wt receiving IL-23−/−bmDCs showed a twofold decrease in heart-infiltrating T cells and lower numbers of Th17 population. Further decrease of heart-infiltrating T cells appeared upon total systemic IL-23 deficiency. In comparison to IL-12, directly inducing differentiation of IFN-gamma–producing Th1, IL-23 cannot induce Th17 differentiation. None of the two cytokines affect proliferation, though, IL-23 activates T cell migratory potential and increases T cell migration by twofold. At the same time, deficiency of IL-23-production by bmDCs leads to lower migration of T cells. We also show an involvement of RhoA, and the other Rho GTPases, in the mechanism of migration as blocking revoke the IL-23 effect on T cells. Moreover, we further observed more fibrosis and worse heart functioning in IL-23−/−, but not IL-12−/− mice at the chronic stage what underlines the importance of IL-23-dependent T cell trafficking in the resolution of the acute stage of autoimmune myocarditis.

Conclusion

Our observations underline IL-23 as an important cytokine responsible for T cell trafficking and resolution of the inflammation in autoimmune myocarditis. Therapeutic approaches involving inflammatory cytokine targeting are a promising clinical perspective though IL-23 deficiency might lead to increased cardiac remodeling and iDCM progression.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): The Swiss National Science Foundation

P736Histone marks induced by the methyltransferase SETD7 modulate angiogenic response in diabetes

Introduction

Despite advances in revascularization strategies, type 2 diabetic (T2D) patients with peripheral artery disease (PAD) continue to have a high risk of limb amputation. Hence, strategies that promote vascularization can be considered as a novel therapeutic option in T2D patients with PAD. Epigenetic modifications of histones and DNA have emerged as key modulators of gene expression. Mono-methylation of histone 3 at lysine 4 (H3K4m1) – a specific epigenetic signature induced by the methyltransferase SETD7 – favours a chromatin conformation enabling the transcription of genes involved in inflammation and oxidative stress.

Purpose

To investigate whether SETD7 modulates angiogenesis in experimental diabetes.

Methods

Human aortic endothelial cells (HAECs) were cultured in growth factor-free medium and exposed either to normal glucose (NG, 5 mM) or high glucose (HG, 25 mM) for 48 hours. SETD7 protein and H3K4me1 levels were investigated by Western blot and chromatin immunoprecipitation (ChIP). Knockdown of SETD7 was achieved by small interfering RNA (siRNA). Pharmacological blockade of SETD7 was performed by using the highly selective inhibitor (R)-PFI-2, while its inactive enantiomer, (S)-PFI-2, was used as a control. Scratch and tube formation assays were performed to investigate the impact of SETD7 on angiogenic properties of HAECs. RNA sequencing (RNA-seq) and Ingenuity Pathway Analysis (IPA) were employed to unveil putative genes regulated by SETD7 in HG-treated HAECs. SETD7 expression was also investigated in muscular specimens isolated from type 2 diabetic (db/db) mice and non-diabetic mice undergoing hindlimb ischemia for 21 days.

Results

HG exposure in HAECs led to a time-dependent increase of both SETD7 gene and protein expression, as compared to NG. SETD7 upregulation in HG-treated HAECs was associated with an increase of H3K4me1 levels as well as with impaired endothelial cell migration and tube formation. Of interest, both gene silencing and pharmacological blockade of SETD7 rescued hyperglycemia-induced impairment of angiogenic properties in HAECs. RNA-seq in HG-treated HAECs with and without SETD7 depletion unveiled an array of differentially expressed genes, which were mainly involved in blood vessel growth and angiogenic response, as assessed by IPA analysis. Among dysregulated genes, ChIP assays showed that SETD7-dependent chromatin changes enabled the transcription of Semaphorin 3G (SEMA-3G), a negative regulator of endothelial cell migration. Indeed, gene silencing of SETD7 blunted SEMA-3G expression in HAECs exposed to HG. Consistent with our in vitro observations, SETD7 was upregulated in adductor muscle specimens from db/db mice undergoing hindlimb ischemia as compared to non-diabetic animals.

Conclusions

Pharmacological blockade of SETD7 by (R)-PFI-2 may represent a potential therapeutic approach to boost post-ischemic vascularization in T2D patients with PAD.

2162Neurofibromin 2 (NF2) drives obesity-related endothelial dysfunction by targeting Caveolin-1: a study in mice and humans

Introduction

Endothelial dysfunction (ED) is a key underpinning of cardiovascular disease in obesity, but the underlying molecular mechanisms remain elusive. Neurofibromin 2 (NF2) is a scaffold-like protein implicated in various cellular processes, namely growth, differentiation and survival. NF2 is inactivated by Akt-dependent phosphorylation at Ser518, whereas its dephosphorylation by the myosin phosphatase target subunit 1 (MYPT-1) leads to an active conformation. The role of NF2 in obesity-related alterations of endothelial phenotype remains elusive.

Purpose

To investigate whether NF2 participates to ED in obesity.

Methods

Human aortic endothelial cells (HAECs) were exposed to palmitic acid (PA, 200 uM) or vehicle for 48 hours. Gene silencing of NF2 was performed by small interfering RNA (siRNA). Protein expression was assessed by Western blot. Nitric oxide (NO) levels were measured by using a colorimetric assay. The interaction of NF2 with endothelial proteins was investigated by co-immunoprecipitation. To specifically determine NF2 role in the endothelium, we generated mice with endothelium-specific deletion of NF2 (NF2 ECKO) by crossing NF2flox/flox mice with tamoxifen-inducible endothelial-specific cre mice [Cdh5(PAC)-CreERT2]. Endothelium-dependent relaxations to acetylcholine (Ach, 10–9 to 10–5 mol/L) were assessed in aortas isolated from male NF2 ECKO and wild type littermates, fed a control (10 kcal% fat) and a high fat diet (60 kcal% fat) for 20 weeks. NF2 signalling and endothelial function were also assessed in small visceral fat arteries (VFA) isolated from 18 obese and 18 age-matched healthy subjects undergoing bariatric surgery and cholecystectomy, respectively.

Results

Exposure of HAECs to PA decreased NF2 phosphorylation at Ser518, thus leading to an active protein conformation. Blunted NF2 phosphorylation was explained by a reduction of Akt phosphorylation at Ser473 and a concomitant increase of MYPT-1 phosphorylation at Thr696. Pull-down experiments revealed that NF2 binds and activates Caveolin 1 (Cav-1), a pivotal repressor of endothelial NO synthase (eNOS). NF2 knockdown in PA-treated HAECs prevented eNOS–Cav-1 interaction, thus preserving eNOS activity and NO levels. In aortas from obese mice, we found that NF2-Cav-1 interaction was responsible for impaired eNOS activity, reduced NO levels and endothelial dysfunction. By contrast, Ach-dependent vasorelaxation were preserved in obese mice with endothelium-specific deletion of NF2. Moreover, we found that NF2 is activated in VFA from obese patients as compared to healthy controls, and its activity negatively correlated with Ach-dependent vasorelaxation of isolated VFA, as assessed by organ chamber experiments.

Conclusions

The present findings – obtained in human endothelial cells, conditional mouse models and visceral fat arteries from obese patients – suggest that targeting NF2 may represent a potential therapeutic strategy to prevent ED in patients with obesity.

P5378The methyltransferase SETD7 promotes myocardial ischemic injury by activating Hippo signalling

Introduction

Despite significant advances in coronary revascularization, acute myocardial infarction remains the leading cause of heart failure and death worldwide. The Hippo pathway is a master regulator of cell survival during myocardial ischemia. Upon cellular stress, activation of Hippo signaling leads to cytosolic retention and degradation of the pro-survival transcription factor YAP. Post-translational modifications, namely methylation, critically affect protein functionality in conditions of cellular stress. The SET domain-containing lysine methyltransferase 7 (SETD7) - which induces a specific mono-methylation of both histone and non-histone proteins - has recently emerged as key player in the pathogenesis of vascular disease. However, the role of SETD7 in the heart is largely unknown.

Purpose

The present study investigates whether SETD7 regulates the Hippo pathway during myocardial ischemia.

Methods

Neonatal rat ventricular myocytes (NRVM) were exposed to normal glucose levels or glucose deprivation (GD) for 15 h, in the presence of the selective SETD7 inhibitor [(R)-PFI-2] or its inactive enantiomer [(S)-PFI-2]. Western blot and real time PCR were employed to investigate the effects of energy stress on SETD7 and the Hippo pathway, while apoptosis was assessed by Caspase-3 activity assay. YAP localization was examined by confocal microscopy while its mono-methylation was assessed by immunoblotting. SETD7 knockout (SETD7−/−) mice and wild-type (WT) littermates (male, 8–12 weeks old) underwent 1 h of left anterior descending (LAD) coronary artery ligation followed by 24 h of reperfusion. Infarct size was assessed by TTC staining and shown as infarct size per ventricle surface (I/V). Cardiac function was investigated at 24h by conventional and Tissue Doppler Imaging echocardiography (Vevo 3100, Visualsonics).

Results

GD for 15h in NRVMs led to both YAP phosphorylation and mono-methylation, and subsequent cytosolic retention, as assessed by confocal microscopy. Reduced nuclear content of YAP was confirmed by downregulation of YAP-dependent pro-survival genes, namely Ctgf and Fgf2. GD-induced YAP inactivation was associated with an increase in SETD7 expression. Interestingly, pharmacological inhibition of SETD7 by (R)-PFI-2 blunted YAP mono-methylation, thus restoring nuclear retention of YAP and transcription of pro-survival genes in GD-treated NRVMs. Moreover, (R)-PFI-2 prevented NRVMs apoptosis. In line with our in vitro findings, SETD7−/− mice showed decreased infarct size as compared to WT littermates (I/V: 16.27%±2 vs. 20.54%±3, p<0.005, respectively). Consistently, cardiac function, as assessed by ejection fraction (EF: 46%±2 vs. 38%±5, p<0.001), fractional shortening (FS: 22%±1 vs. 18%±3, p<0.001) as well as by TDI, was preserved in mice lacking SETD7 as compared to WT animals.

Conclusions

Pharmacological modulation of SETD7 by (R)-PFI-2 may represent a novel therapeutic approach to prevent myocardial ischemic damage.

2287Endothelial SIRT6 exerts a beneficial role in cerebral ischemia/reperfusion injury by preserving blood-brain barrier integrity

Introduction

Stroke is a major cause of mortality and morbidity worldwide. Yet, therapeutic strategies are limited to the early reperfusion which can, on the other hand, worsen the brain damage trough ischemia/reperfusion (I/R) injury. Post-stroke blood-brain barrier (BBB) impairment is associated with worsened outcome. Aging is a major risk factor for stroke and genes regulating lifespan also contribute to the determination of cerebral damage during I/R injury.

Purpose

Given the pivotal role of endothelial cells in BBB, we hypothesized that the endothelial-specific expression of the longevity gene SIRT6 may protect the BBB from ischemia/reperfusion damage thus having a beneficial role on stroke outcome.

Methods

Endothelial-specific SIRT6 knockout (eSIRT6−/−) mice and control littermates (CTRL) underwent transient middle cerebral artery occlusion (tMCAO) for 45 min followed by 48 hours of reperfusion. Immunohistochemistry (IHC) was used to investigate BBB permeability by IgG extravasation and molecular mechanisms. Primary human brain microvascular endothelial cells (HBMVECs) transfected with either SIRT6 (siSIRT6) or scrambled (siSCR) small interfering RNA were subjected to hypoxia/reoxygenation (H/R). An in vitro BBB model consisting of a monolayer of siRNA-treated HBMVECs was established and barrier function was assessed by 48 h-lasting transendothelial electrical resistance measurement. SIRT6 expression in monocytes from stroke patients was correlated with the short-term neurological outcome [ΔNIHSS% = (NIHSS discharge-NIHSS admission)/ NIHSS admission*100].

Results

eSIRT6−/− displayed higher infarct volumes and lower survival rate compared to WT mice 48 h after tMCAO. The increased infarct volume was functionally relevant as eSIRT6−/− also showed worse post-stroke neurological impairment. Analysis of brain sections revealed increased BBB damage and increased endothelial expression of cleaved caspase-3 in eSIRT6−/− as compared to control littermates. In vitro, H/R reduced SIRT6 expression in HBMVECs. Mirroring the animal results, SIRT6 silencing impaired the barrier function of HBMVECs 48 h after exposure to H/R. In line with this, SIRT6-silenced HBMVECs showed reduced viability, increased cleaved caspase-3 expression and reduced activation of the anti-apoptotic survival pathway Akt as compared to control cells after H/R. The direct interaction between SIRT6 and Akt was confirmed by co-immunoprecipitation. In ischemic stroke patients, SIRT6 expression was higher in those with short-term neurological improvement (ΔNIHSS% >0) and negatively correlated with ΔNIHSS%.

Conclusion

Endothelial SIRT6 exerts a beneficial role in ischemic stroke by blunting I/R-mediated BBB damage. Specifically, SIRT6 reduces endothelial I/R-induced apoptotic death through activation of the protective Akt pathway. The longevity gene SIRT6 may represent a novel therapeutic target for the treatment of ischemic stroke.

Acknowledgement/Funding

Swiss National Science Foundation

The epigenetic landscape in the cardiovascular complications of diabetes

A growing body of evidence suggests that epigenetic modifications-changes to the genome that do not involve changes in DNA sequence-may significantly derail transcriptional programs implicated in angiogenesis, oxidative stress and inflammation, thus fostering cardiovascular damage in patients with diabetes. Notably, adverse epigenetic signals acquired over the life course can be transmitted to the offspring, and may contribute to early cardiovascular phenotypes in the young generations. Hyperglycaemia and insulin resistance-key hallmarks of diabetes-induce an array of epigenetic modifications (i.e., DNA methylation, histone marks, and non-coding RNAs) which are responsible for a long-lasting impairment of vascular and cardiac function, even after intensive glycemic control. Hence, unveiling the "epigenetic landscape" in patients with diabetes may provide a post-genomic snapshot of global cardiovascular risk, and may furnish the tools to design personalized, epigenetic-based therapies to alleviate the burden of cardiovascular disease in diabetic patients. The present review aims to acquaint the scientific community with the rapidly advancing field of epigenetics and its implications in the cardiovascular complications of diabetes.

Validation of a method for measuring (226)Ra in drinking waters by LSC

A simple method for measuring (226)Ra in drinking waters has been validated and validation parameters are provided. It is based on the measurement by LSC of (222)Rn, at equilibrium with (226)Ra, which is absorbed into a water immiscible scintillation cocktail (Ultima Gold F) inside the counting vial. The validated application field ranges between the detection limit (2·10(-3) Bq/kg) to 150 Bq/kg. The method has proven to be reliable, effective and suitable for wide-range measuring campaigns. A summary of results obtained in recent years is also given.

Non-invasive measurement of choroidal volume change and ocular rigidity through automated segmentation of high-speed OCT imaging

We have developed a novel optical approach to determine pulsatile ocular volume changes using automated segmentation of the choroid, which, together with Dynamic Contour Tonometry (DCT) measurements of intraocular pressure (IOP), allows estimation of the ocular rigidity (OR) coefficient. Spectral Domain Optical Coherence Tomography (OCT) videos were acquired with Enhanced Depth Imaging (EDI) at 7Hz during ~50 seconds at the fundus. A novel segmentation algorithm based on graph search with an edge-probability weighting scheme was developed to measure choroidal thickness (CT) at each frame. Global ocular volume fluctuations were derived from frame-to-frame CT variations using an approximate eye model. Immediately after imaging, IOP and ocular pulse amplitude (OPA) were measured using DCT. OR was calculated from these peak pressure and volume changes. Our automated segmentation algorithm provides the first non-invasive method for determining ocular volume change due to pulsatile choroidal filling, and the estimation of the OR constant. Future applications of this method offer an important avenue to understanding the biomechanical basis of ocular pathophysiology.

Guidelines and management of hospitalized patients with community-acquired pneumonia: the Italian experience of the FASTCAP study

BACKGROUND Nowadays few data are available addressing the validation of guidelines concerning diagnosis and treatment of Community-Acquired Pneumonia (CAP) in clinical practice. AIM OF THE STUDY To evaluate the impact of compliance to the recommendations issued by the Italian Federation of Internal Medicine (FADOI) in 2002 on the management of hospitalised CAP. METHODS National, multicentre, interventional, “before-after” survey, performed in 31 hospitals in Italy. All patients with CAP of Fine class IV or V (excluding those who were directly admitted to intensive care units) were included. The study was composed of three consecutive periods: 1) a retrospective phase (RP); 2) guideline implementation; 3) a prospective phase (PP). Results were expressed as Odds Ratios (OR) with 95% confidence intervals (95% CI) adjusted for risk factors and corrected for multiple comparisons in subgroups. RESULTS A significant increase in use of combinations was observed in the PP (p = 0.006). Moreover, a shift of prescription from β-lactams to fluoroquinolones as initial monotherapy was recorded. Therapies adherent to FADOI recommendations increased by 10.9% in the PP (p < 0.001). Therapeutic success improved after implementation of recommendations (73.9 vs 71.5%; OR = 0.83; 95% CI = 0.69-1.00; p = 0.049). The difference was particularly evident in Fine class V (58.0 vs 52.5%; OR = 0.71; 95% CI = 0.51-0.98; p = 0.036), where a trend towards a lower mortality occurred (23.1 vs 26.3%; OR = 0.71; 95% CI = 0.48-1.05; p = 0.090). Therapies compliant with FADOI recommendations showed a higher success rate in both study phases (76.6% vs 70.3%; OR = 0.74; 95% CI = 0.60-0.90; p = 0.004). Levofloxacin was the most clinically effective first-cycle therapy with 79.1% of success, the least effective being an antipneumococcal cephalosporin alone with 68.6% (OR = 0.72; 95% CI = 0.51-1.01; p = 0.053). Etiologic diagnosis was obtained in less than 12% of patients in both study phases. Mean lengths of hospital stay were 12.2 and 11.9 days in the RP and PP, respectively. CONCLUSIONS Implementation of FADOI therapeutic recommendations led to a significantly better outcome in terms of clinical success, especially in more severe cases of CAP. Possibly, more “aggressive” approaches towards implementation may result in further improvement in the overall management of CAP.

Automatic 3D reconstruction of quasi-planar stereo Scanning Electron Microscopy (SEM) images

Scanning Electron Microscopy (SEM) is widely used in science to characterize the surface roughness of materials. Three-dimensional information can be obtained with SEM based on stereovision techniques. A stereo pair is typically obtained by tilting the sample by a few degrees. In this paper we present a fully automated method for 3D reconstruction from a SEM stereo pair without any particular constraint. Results are presented for corneal stromal surfaces.

Analyzing speckle contrast for HiLo microscopy optimization

HiLo microscopy is a recently developed technique that provides both optical sectioning and fast imaging with a simple implementation and at a very low cost. The methodology combines widefield and speckled illumination images to obtain one optically sectioned image. Hence, the characteristics of such speckle illumination ultimately determine the quality of HiLo images and the overall performance of the method. In this work, we study how speckle contrast influence local variations of fluorescence intensity and brightness profiles of thick samples. We present this article as a guide to adjust the parameters of the system for optimizing the capabilities of this novel technology.

Spectral-domain phase microscopy with improved sensitivity using two-dimensional detector arrays

In this work we demonstrate the use of two-dimensional detectors to improve the signal-to-noise ratio (SNR) and sensitivity in spectral-domain phase microscopy for subnanometer accuracy measurements. We show that an increase in SNR can be obtained, from 82 dB to 105 dB, using 150 pixel lines of a low-cost CCD camera as compared to a single line, to compute an averaged axial scan. In optimal mechanical conditions, phase stability as small as 92 μrad, corresponding to 6 pm displacement accuracy, could be obtained. We also experimentally demonstrate the benefit of spatial-averaging in terms of the reduction of signal fading due to an axially moving sample. The applications of the improved system are illustrated by imaging live cells in culture.

Patient and operator exposure during percutaneous vertebroplasty

PURPOSE

The purpose of this study was to compare exposure of patient and operator to ionising radiation during percutaneous vertebroplasty performed under combined computed tomography (CT) and fluoroscopic guidance or fluoroscopic guidance alone.

MATERIALS AND METHODS

With the collaboration of our physics department, we measured exposure on ten patients undergoing vertebroplasty with combined CT and fluoroscopic guidance and on ten undergoing vertebroplasty with fluoroscopic guidance alone.

RESULTS

Mean operator dose was approximately 0.8 microSv during vertebroplasty done with combined CT and fluoroscopic guidance and 5.8 microSv in procedures with fluoroscopic guidance alone. Mean patient dose was approximately 6 mSv for combined guidance and 8 mSv for fluoroscopic guidance, a difference that was not found to be statistically significant.

CONCLUSIONS

Although combined CT and fluoroscopic guidance is normally preferred for difficult areas such as the cervical and upper thoracic vertebrae, to ensure operator radiation protection, the technique should also be considered for areas normally treated under fluoroscopic guidance alone. However, a larger patient series is needed to correctly evaluate the real contribution of low-dose CT to patient exposure.

[A rare case of esophageal atresia type I]

An extremely rare case of type A esophageal atresia is reported. The baby girl patient born spontaneously after a 38-week pregnancy, was diagnosed prenatally with suspected type A esophageal atresia. Diagnosis was confirmed at birth by chest and abdominal X-ray. As per protocol, a naso-esophageal tube was positioned in aspiration and a Stamm gastrostomy made for nutritional purposes. Evaluation of the distance between blind pouches at one month of life showed they were overlapping. At intervention the pouches were found to be united by a fibrous bridge about 1.5 cm long. Anastomosis was carried out with ease. The postoperative course was trouble-free. On the X day the baby girl was being fed completely per os. Histolo-gical examination of the fibrous residue excluded the presence of a mucosa-lined lumen. X-ray examination of the esophageal-gastric passage, one month after the operation, showed the smooth transit of the contrast medium and an adequate anastomotic lumen. At follow-up, at the age of 9 months, the baby was growing normally and being fed per os with a diet appropriate for her age; no oesophageal dilatation was necessary. Type A oesophageal atresias are long-gap forms: they are treated with direct anastomosis after the blind pouches come together spontaneously in the first four months of life. Stress is laid on the rarity of the case. According to Kluth's classification of 1976, this form was described by Mason in 1855 and Jlott in 1905 on the basis of autopsy findings. A review of the literature did not show any similar clinical cases.

Can CAP guideline adherence improve patient outcome in internal medicine departments?

The impact of compliance with Italian guidelines on the outcome of hospitalised community-acquired pneumonia (CAP) in internal medicine departments was evaluated. All Fine class IV or V CAP patients were included in this multicentre, interventional, before-and-after study, composed of three phases: 1) a retrospective phase (RP; 1,443 patients); 2) a guideline implementation phase; and 3) a prospective phase (PP; 1,404 patients). Antibiotic prescription according to the guidelines increased significantly in the PP. The risk of failure at the end of the firstline therapy was significantly lower in the PP versus the RP (odds ratio (OR) 0.83, 95% confidence interval (CI) 0.69-1.00), particularly in Fine class V patients (OR 0.71, 95% CI 0.51-0.98). Analysis of outcome in the overall population (2,847 patients) showed a statistically significant advantage for compliant versus noncompliant therapies in terms of failure rate (OR 0.74, 95% CI 0.60-0.90) and an advantage in terms of mortality (OR 0.77, 95% CI 0.58-1.04). Antipneumococcal cephalosporin monotherapy was associated with a low success rate (68.6%) and the highest mortality (16.2%); levofloxacin alone and the combination of cephalosporin and macrolide resulted in higher success rates (79.1 and 76.7%, respectively) and significantly lower mortalities (9.1 and 5.7%, respectively). Overall, a low compliance with guidelines in the prospective phase (44%) was obtained, indicating the need for future more aggressive and proactive approaches.

Context-dependent regulation of embryonic stem cell differentiation by mGlu4 metabotropic glutamate receptors

The mGlu5 receptor is the only metabotropic glutamate receptor subtype expressed by mouse embryonic stem (ES) cells grown under non-differentiating conditions [Cappuccio, I., Spinanti, P. Porcellini, A., Desiderati, F., De Vita, T., Storto, M., Capobianco, L., Battaglia, G., Nicoletti, F., Melchiorri, D., 2005. Endogenous activation of mGlu5 metabotropic glutamate receptors supports self-renewal of cultured mouse embryonic stem cells. Neuropharmacology 1, 196-205]. We now report that ES cells differentiating into embryoid bodies (EBs) progressively lose mGlu5 receptors and begin to express mGlu4 receptors at both mRNA and proteinc level. A 4-day treatment of EBs with the mGlu4 receptor agonist, L-2-amino-4-phosphonobutanoate (L-AP4), increased mRNA levels of the mesoderm marker, brachyury and the endoderm marker, H19, and decreased the expression of the transcript for the primitive ectoderm marker, fibroblast-growth factor-5 (FGF-5). These effects were prevented by the mGlu4 receptor antagonists, alpha-methylserine-O-phosphate (MSOP). Plating of EBs for 4 days in vitro in ITSFn medium induced cell differentiation towards a neural lineage, as reflected by the expression of the intermediate filament protein, nestin, and the homeobox protein, Dlx-2. Pharmacological activation of mGlu4 receptors during cell incubation in ITSFn medium increased the expression of both neural markers. Similar results were obtained when neural differentiation was induced by exposure of EBs to retinoic acid. These data suggest that differentiation of cultured ES cells is associated with changes in the expression pattern of mGlu receptors and that activation of mGlu4 receptors affects cell differentiation in a context-dependent manner.

Oral Manifestations of Langerhans Cell Histiocytosis in a Pediatric Population

Langerhans Cell Histiocytosis is a rare and protean disease of unknown etiology, clinically characterized by single or multiple osteolytic and/or soft tissue lesions. Oral involvement may predate systemic manifestations or mimic infectious/inflammatory disorders. In the present series, oral involvement characterized eight cases of pediatric Langerhans Cell Histiocytosis and oral symptoms represented a very early sign of this disease in four patients. A careful clinical investigation and a proper histologic analysis were required for achieving a definite diagnosis and for confirming clinical suspicion of disease relapse. Immunohistochemistry, that nowadays represents a reliable and accessible ancillary histological technique, allowed the definite diagnosis in all cases of our series.

Amino acid levels in some lethargic mouse brain areas before and after pentylenetetrazole kindling

Genetic animal models have contributed significantly to our understanding of epilepsy causes. Lethargic mice are considered a valid model of absence epilepsy, which have been shown to possess behavioral, electrographic and pharmacological profiles similar to those of humans with absence epilepsies. Single gene mutations that comprise the beta4 subunit of voltage-sensitive Ca2+ channels underlie the spontaneous discharges of the absence, non-convulsive seizures of lethargic mice. There are no available data concerning how the mutant channels actually behave at terminals in response to chemical activation by subconvulsant stimulation with pentylenetetrazole. In this study, we found no significant difference in the convulsive dose 50 between lethargic and control mice. Lethargic mice showed a more rapid development of kindling to pentylenetetrazole than control animals. No significant differences were observed between the groups of mice rechallenged with pentylenetetrazole 30 or 60 days after the end of the chronic treatment. Marked differences in brain amino acid levels were found between the two strains of mice in basal conditions and after kindling. In conclusion, our results indicate that lethargic mice show a range of biochemical and behavioral changes, correlated in particular with a higher susceptibility to develop kindled seizures.