G-protein receptor kinases 2, 5 and 6 redundantly modulate Smoothened-GATA transcriptional crosstalk in fetal mouse hearts

G-protein receptor kinases (GRKs) regulate adult hearts by modulating inotropic, chronotropic and hypertrophic signaling of 7-transmembrane spanning neurohormone receptors. GRK-mediated desensitization and downregulation of β-adrenergic receptors has been implicated in adult heart failure; GRKs are therefore a promising therapeutic target. However, germ-line (but not cardiomyocyte-specific) GRK2 deletion provoked lethal fetal heart defects, suggesting an unexplained role for GRKs in heart development. Here we undertook to better understand the consequences of GRK deficiency on fetal heart development by creating mice and cultured murine embryonic fibroblasts (MEFs) having floxed GRK2 and GRK5 alleles on the GRK6 null background; simultaneous conditional deletion of these 3 GRK genes was achieved using Nkx2-5 Cre or adenoviral Cre, respectively. Phenotypes were related to GRK-modulated gene expression using whole-transcriptome RNA sequencing, RT-qPCR, and luciferase reporter assays. In cultured MEFs the atypical 7-transmembrane spanning protein and GRK2 substrate Smoothened (Smo) stimulated Gli-mediated transcriptional activity, which was interrupted by deleting GRK2/5/6. Mice with Nkx2-5 Cre mediated GRK2/5/6 ablation died between E15.5 and E16.5, whereas mice expressing any one of these 3 GRKs (i.e. GRK2/5, GRK2/6 or GRK5/6 deleted) were developmentally normal. GRK2/5/6 triple null mice at E14.5 exhibited left and right heart blood intermixing through single atrioventricular valves or large membranous ventricular septal defects. Hedgehog and GATA pathway gene expression promoted by Smo/Gli was suppressed in GRK2/5/6 deficient fetal hearts and MEFs. These data indicate that GRK2, GRK5 and GRK6 redundantly modulate Smo-GATA crosstalk in fetal mouse hearts, orchestrating transcriptional pathways previously linked to clinical and experimental atrioventricular canal defects. GRK modulation of Smo reflects convergence of conventional neurohormonal signaling and transcriptional regulation pathways, comprising an unanticipated mechanism for spatiotemporal orchestration of developmental gene expression in the heart.

Modulation of subsets of cardiac B lymphocytes improves cardiac function after acute injury

Despite the long-standing recognition that the immune response to acute myocardial injury contributes to adverse left ventricular (LV) remodeling, it has not been possible to effectively target this clinically. Using 2 different in vivo models of acute myocardial injury, we show that pirfenidone confers beneficial effects in the murine heart through an unexpected mechanism that depends on cardiac B lymphocytes. Naive hearts contained a large population of CD19+CD11b-CD23-CD21-IgD+IgMlo lymphocytes, and 2 smaller populations of CD19+CD11b+ B1a and B1b cells. In response to tissue injury, there was an increase in neutrophils, monocytes, macrophages, as well as an increase in CD19+ CD11b- B lymphocytes. Treatment with pirfenidone had no effect on the number of neutrophils, monocytes, or macrophages, but decreased CD19+CD11b- lymphocytes. B cell depletion abrogated the beneficial effects of pirfenidone. In vitro studies demonstrated that stimulation with lipopolysaccharide and extracts from necrotic cells activated CD19+ lymphocytes through a TIRAP-dependent pathway. Treatment with pirfenidone attenuated this activation of B cells. These findings reveal a previously unappreciated complexity of myocardial B lymphocytes within the inflammatory infiltrate triggered by cardiac injury and suggest that pirfenidone exerts beneficial effects in the heart through a unique mechanism that involves modulation of cardiac B lymphocytes.

Rationale and design of the BUDAPEST-CRT Upgrade Study: a prospective, randomized, multicentre clinical trial

Aims

There is lack of conclusive evidence from randomized clinical trials on the efficacy and safety of upgrade to cardiac resynchronization therapy (CRT) in patients with implanted pacemakers (PM) or defibrillators (ICD) with reduced left ventricular ejection fraction (LVEF) and chronic heart failure (HF). The BUDAPEST-CRT Upgrade Study was designed to compare the efficacy and safety of CRT upgrade from conventional PM or ICD therapy in patients with intermittent or permanent right ventricular (RV) septal/apical pacing, reduced LVEF, and symptomatic HF.

Methods and results

The BUDAPEST-CRT study is a prospective, randomized, multicentre, investigator-sponsored clinical trial. A total of 360 subjects will be enrolled with LVEF ≤ 35%, NYHA functional classes II–IVa, paced QRS ≥ 150 ms, and a RV pacing ≥ 20%. Patients will be followed for 12 months. Randomization is performed in a 3:2 ratio (CRT-D vs. ICD). The primary composite endpoint is all-cause mortality, a first HF event, or less than 15% reduction in left ventricular (LV) end-systolic volume at 12 months. Secondary endpoints are all-cause mortality, all-cause mortality or HF event, and LV volume reduction at 12 months. Tertiary endpoints include changes in quality of life, NYHA functional class, 6 min walk test, natriuretic peptides, and safety outcomes.

Conclusion

The results of our prospective, randomized, multicentre clinical trial will provide important information on the role of cardiac resynchronization therapy with defibrillator (CRT-D) upgrade in patients with symptomatic HF, reduced LVEF, and wide-paced QRS with intermittent or permanent RV pacing.

Clinical trials.gov identifier

NCT02270840.

Abstract 011: Cardiovascular Consequences of Cantu Syndrome and Response to Glibenclamide Treatment in Two Novel KATP Channel Mutant Mouse Models

The rare heritable disorder Cantů syndrome (CS) arises from gain-of-function mutations in the genes encoding the cardiovascular KATP channel subunits Kir6.1 and SUR2 ( KCNJ8 and ABCC9 , respectively). CS is characterized by diverse features including hypertrichosis, osteochondrodysplasia and craniofacial dysmorphology. Multiple cardiovascular abnormalities are also reported in CS including vascular dilation and tortuosity, dramatic cardiomegaly, pulmonary hypertension and low systemic blood pressure. We have developed and characterized two novel mouse models of Cantu Syndrome in which disease causing amino acid substitutions have been engineered into either Kir6.1 (p.V65M) or SUR2 (p.A478V) using CRISPR/Cas9 genome editing. Electrophysiological assessment of isolated vascular smooth muscle cells (VSMCs) showed that both mutations result in increased basal activity of VSM KATP channels. Mutant mice also exhibit vascular dilation, low blood pressure, and pulmonary hypertension. In addition, mutant mice exhibited hypertrophic, hyper-contractile hearts. The latter findings are not trivially predictable as a consequence of KATP gain-of-function, but also recapitulates key clinical features of CS. The severity of pathophysiological remodeling correlated with the molecular effects of the substitution. These models provide novel insights to the cardiovascular consequences of KATP over-activity. Little is known about the long-term effects of human CS, nor reversibility of pathophysiological consequences. Chronic administration of the sulfonylurea KATP inhibitor glibenclamide (glyburide) by slow-release pellets implanted under the skin resulted in normalization of vascular consequences and reversal of cardiac hypertrophy in SUR2(A478V) mice over 3 weeks. Kir6.1(V65M) mice are less sensitive to glibenclamide treatment, as predicted from studies of recombinant channels. These results suggest that glibenclamide represents a promising pharmacotherapy for CS (but that sensitivity may be patient- and mutation-dependent), and perhaps for diverse cardiovascular conditions arising from decreased smooth muscle excitability in general.

Metabolic and Cardiac Adaptation to Chronic Pharmacologic Blockade of Facilitative Glucose Transport in Murine Dilated Cardiomyopathy and Myocardial Ischemia

GLUT transgenic and knockout mice have provided valuable insight into the role of facilitative glucose transporters (GLUTs) in cardiovascular and metabolic disease, but compensatory physiological changes can hinder interpretation of these models. To determine whether adaptations occur in response to GLUT inhibition in the failing adult heart, we chronically treated TG9 mice, a transgenic model of dilated cardiomyopathy and heart failure, with the GLUT inhibitor ritonavir. Glucose tolerance was significantly improved with chronic treatment and correlated with decreased adipose tissue retinol binding protein 4 (RBP4) and resistin. A modest improvement in lifespan was associated with decreased cardiomyocyte brain natriuretic peptide (BNP) expression, a marker of heart failure severity. GLUT1 and -12 protein expression was significantly increased in left ventricular (LV) myocardium in ritonavir-treated animals. Supporting a switch from fatty acid to glucose utilization in these tissues, fatty acid transporter CD36 and fatty acid transcriptional regulator peroxisome proliferator-activated receptor α (PPARα) mRNA were also decreased in LV and soleus muscle. Chronic ritonavir also increased cardiac output and dV/dt-d in C57Bl/6 mice following ischemia-reperfusion injury. Taken together, these data demonstrate compensatory metabolic adaptation in response to chronic GLUT blockade as a means to evade deleterious changes in the failing heart.

Minoxidil improves vascular compliance, restores cerebral blood flow, and alters extracellular matrix gene expression in a model of chronic vascular stiffness

Increased vascular stiffness correlates with a higher risk of cardiovascular complications in aging adults. Elastin (ELN) insufficiency, as observed in patients with Williams-Beuren syndrome or with familial supravalvular aortic stenosis, also increases vascular stiffness and leads to arterial narrowing. We used Eln^+/- mice to test the hypothesis that pathologically increased vascular stiffness with concomitant arterial narrowing leads to decreased blood flow to end organs such as the brain. We also hypothesized that drugs that remodel arteries and increase lumen diameter would improve flow. To test these hypotheses, we compared carotid blood flow using ultrasound and cerebral blood flow using MRI-based arterial spin labeling in wild-type (WT) and Eln^+/- mice. We then studied how minoxidil, an ATP-sensitive K⁺ channel opener and vasodilator, affects vessel mechanics, blood flow, and gene expression. Both carotid and cerebral blood flows were lower in Eln^+/- mice than in WT mice. Treatment of Eln^+/- mice with minoxidil lowered blood pressure and reduced functional arterial stiffness to WT levels. Minoxidil also improved arterial diameter and restored carotid and cerebral blood flows in Eln^+/- mice. The beneficial effects persisted for weeks after drug removal. RNA-Seq analysis revealed differential expression of 127 extracellular matrix-related genes among the treatment groups. These results indicate that ELN insufficiency impairs end-organ perfusion, which may contribute to the increased cardiovascular risk. Minoxidil, despite lowering blood pressure, improves end-organ perfusion. Changes in matrix gene expression and persistence of treatment effects after drug withdrawal suggest arterial remodeling. Such remodeling may benefit patients with genetic or age-dependent ELN insufficiency. NEW & NOTEWORTHY Our work with a model of chronic vascular stiffness, the elastin ( Eln)^+/- mouse, shows reduced brain perfusion as measured by carotid ultrasound and MRI arterial spin labeling. Vessel caliber, functional stiffness, and blood flow improved with minoxidil. The ATP-sensitive K⁺ channel opener increased Eln gene expression and altered 126 other matrix-associated genes.

Abstract P1-01-04: Mutational profiling of breast cancer brain metastases – matched pair analysis of next generation sequencing between primary breast cancer and later developed brain metastases

Background: Despite increased survival in patients with advanced breast cancer, breast cancer brain metastases (BCBM), remains a final frontier with a mean survival of 3-12 months. The biology facilitating BCBM is not fully understood.

Aims: To compare gene expression profiles in primary BC, and later diagnosed, surgically removed BCBM.

Material and Methods: A total of 58 BCBM and 46 breast tumors were analyzed with next generation sequencing (NGS). DNA was isolated from FFPE sectionsand then the Cancer Hotspot Panel v2 (ThermoFisher Scientific) covering 207-targeted regions in 50 cancer related genes was used. Template preparation and enrichment were performed with the IonChefTM Instrument (ThermoFisher Scientific). Eight barcoded samples were pooled per Ion 318 TM v2 BC chip and sequenced on the Ion PGMTM System (ThermoFisher Scientific).Alignment to the hg19 human reference genome and variant calling was performed by the Torrent Suite Software v5.2.0 (ThermoFisher Scientific) also IonReporterTM System (ThermoFisher Scientific) was used.

Results: 46 of the BCBM were matched with a primary breast cancer tumor. All but 12 tumors had the same IHC characteristic in the matched pairs. The most common transformation was Luminal A to Luminal B in 8 tumors. The other changes were triple negative subtype (TNBC) to Luminal B, HER2+ to Luminal B, Luminal A to TNBC and Luminal A to HER2+ with one case respectively. The BCBM had the following IHC profile: one tumor was luminal A (1%), 15 tumors were Luminal B (25%), 29 were TNBC (50%) and 14 HER2 overexpressing (24%). The preliminary NGS data shows that the most common mutation in BCBM was found in the tumor suppressor gene p53 (22/58, 38 %). Other common mutations were PIK3CA (17/58, 29%); KDR (16/58, 28%), KIT (9/58, 16%) and PTEN (2/58, 3%). The corresponding figures in the primary BC were p53 (15/46, 33%), PIK3CA (16/46, 35%), KDR (17/46, 37%), KIT (7/46, 15%) and no tumors with PTEN. The mutational spectra in the 50 cancer related genes were similar in the primary BC as in the BCBM with 1-5 different driver mutations but additional mutations were registered in 6/46 matched cases (13%). We fail to identify any specific differences in mutations between the different morphological subtypes (LumA/LumB/TNBC/HER2+) in the metastatic sample. In the NGS analysis of the metastases and primary tumors 3 different variations of p53 was detected.

Conclusions: In this large matched pairs of primary breast tumors and BCBM we show that the majority of BCBM have a similar gene profile as the primary BC. The most common aberrations were found in TP53, PIK3CA and KDR. Additional post analyses are under investigation and will be added to the results. It appears that brain metastases are not different from other metastases in that they remain fairly stable in their driver mutational profile. When the mutational profile changes there is addition of mutation rather than deletion. A clinical implication of these results could be to treat BCBM according to the mutational profile of the primary tumor which decreases the need for sampling of BCBM; something that if the patient is not eligible for surgery might otherwise prove complex.

Citation Format: Thulin A, Andersson C, Werner Rönnerman E, De Lara S, Chamalidou C, Schoenfeld A, Kovacs A, Enlund F, Linderholm BK. Mutational profiling of breast cancer brain metastases – matched pair analysis of next generation sequencing between primary breast cancer and later developed brain metastases [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-01-04.

TNF receptor-activated factor 2 mediates cardiac protection through noncanonical NF-κB signaling

To elucidate the mechanisms responsible for cytoprotective effects of TNF receptor-activated factor 2 (TRAF2) in the heart, we employed genetic gain- and loss-of-function studies ex vivo and in vivo in mice with cardiac-restricted overexpression of TRAF2 (Myh6-TRAF2LC). Crossing Myh6-TRAF2LC mice with mice lacking canonical signaling (Myh6-TRAF2LC/Myh6-IκBαΔN) abrogated the cytoprotective effects of TRAF2 ex vivo. In contrast, inhibiting the JAK/STAT pathway did not abrogate the cytoprotective effects of TRAF2. Transcriptional profiling of WT, Myh6-TRAF2LC, and Myh6-TRAF2LC/Myh6-IκBαΔN mouse hearts suggested that the noncanonical NF-κB signaling pathway was upregulated in the Myh6-TRAF2LC mouse hearts. Western blotting and ELISA for the NF-κB family proteins p50, p65, p52, and RelB on nuclear and cytoplasmic extracts from naive 12-week-old WT, Myh6-TRAF2LC, and Myh6-TRAF2LC/Myh6-IκBαΔN mouse hearts showed increased expression levels and increased DNA binding of p52 and RelB, whereas there was no increase in expression or DNA binding of the p50 and p65 subunits. Crossing Myh6-TRAF2LC mice with RelB-/+ mice (Myh6-TRAF2LC/RelB-/+) attenuated the cytoprotective effects of TRAF2 ex vivo and in vivo. Viewed together, these results suggest that crosstalk between the canonical and noncanonical NF-κB signaling pathways is required for mediating the cytoprotective effects of TRAF2.

De novo implantation vs. upgrade cardiac resynchronization therapy: a systematic review and meta-analysis

Patients with conventional pacemakers or implanted defibrillators are often considered for cardiac resynchronization therapy (CRT). Our aim was to summarize the available evidences regarding the clinical benefits of upgrade procedures. A systematic literature search was performed from studies published between 2006 and 2017 in order to compare the outcome of CRT upgrade vs. de novo implantations. Outcome data on all-cause mortality, heart failure events, New York Heart Association (NYHA) Class, QRS narrowing and echocardiographic parameters were analysed. A total of 16 reports were analysed comprising 489,568 CRT recipients, of whom 468,205 patients underwent de novo and 21,363 upgrade procedures. All-cause mortality was similar after CRT upgrade compared to de novo implantations (RR 1.19, 95% CI 0.88-1.60, p = 0.27). The risk of heart failure was also similar in both groups (RR 0.96, 95% CI 0.70-1.32, p = 0.81). There was no significant difference in clinical response after CRT upgrade compared to de novo implantations in terms of improvement in left ventricular ejection fraction (ΔEF de novo - 6.85% vs. upgrade - 9.35%; p = 0.235), NYHA class (ΔNYHA de novo - 0.74 vs. upgrade - 0.70; p = 0.737) and QRS narrowing (ΔQRS de novo - 9.6 ms vs. upgrade - 29.5 ms; p = 0.485). Our systematic review and meta-analysis of currently available studies reports that CRT upgrade is associated with similar risk for all-cause mortality compared to de novo resynchronization therapy. Benefits on reverse remodelling and functional capacity improved similarly in both groups suggesting that CRT upgrade may be safely and effectively offered in routine practice.

CLINICAL TRIAL REGISTRATION

Prospero Database-CRD42016043747.

Disturbed spermatogenic signaling in pituitary adenylate cyclase activating polypeptide-deficient mice

PACAP is a neuropeptide with diverse functions in various organs, including reproductive system. It is present in the testis in high concentrations, and in addition to the stage-specific expression within the seminiferous tubules, PACAP affects spermatogenesis and the functions of Leydig and Sertoli cells. Mice lacking endogenous PACAP show reduced fertility, but the possibility of abnormalities in spermatogenic signaling has not yet been investigated. Therefore, we performed a detailed morphological analysis of spermatozoa, sperm motility and investigated signaling pathways that play a role during spermatogenesis in knockout mice. No significant alterations were found in testicular morphology or motility of sperm in homozygous and heterozygous PACAP-deficient mice in spite of the moderately increased number of severely damaged sperms. However, we found robust changes in mRNA and/or protein expression of several factors that play an important role in spermatogenesis. Protein kinase A expression was markedly reduced, while downstream phospho-ERK and p38 were elevated in knockout animals. Expression of major transcription factors, such as Sox9 and phospho-Sox9, was decreased, while that of Sox10, as a redundant factor, was increased in PACAP-deficient mice. The reduced phospho-Sox9 expression was partly due to increased expression and activity of phosphatase PP2A in knockout mice. Targets of Sox transcription factors, such as collagen type IV, were reduced in knockout mice. In summary, our results show that lack of PACAP leads to disturbed signaling in spermatogenesis, which could be a factor responsible for reduced fertility in PACAP knockout mice, and further support the role of PACAP in reproduction.

Gestational Stage and IFN-λ Signaling Regulate ZIKV Infection In Utero

Although Zika virus (ZIKV)-induced congenital disease occurs more frequently during early stages of pregnancy, its basis remains undefined. Using established type I interferon (IFN)-deficient mouse models of ZIKV transmission in utero, we found that the placenta and fetus were more susceptible to ZIKV infection at earlier gestational stages. Whereas ZIKV infection at embryonic day 6 (E6) resulted in placental insufficiency and fetal demise, infections at midstage (E9) resulted in reduced cranial dimensions, and infection later in pregnancy (E12) caused no apparent fetal disease. In addition, we found that fetuses lacking type III IFN-λ signaling had increased ZIKV replication in the placenta and fetus when infected at E12, and reciprocally, treatment of pregnant mice with IFN-λ2 reduced ZIKV infection. IFN-λ treatment analogously diminished ZIKV infection in human midgestation fetal- and maternal-derived tissue explants. Our data establish a model of gestational stage dependence of ZIKV pathogenesis and IFN-λ-mediated immunity at the maternal-fetal interface.