Differential Effects of HDAC6 Inhibition Versus Knockout During Hepatic Ischemia-reperfusion Injury Highlight Importance of HDAC6 C-terminal Zinc-finger Ubiquitin-binding Domain.

BACKGROUND: Ischemia-reperfusion injury (IRI) causes significant morbidity in liver transplantation among other medical conditions. IRI following liver transplantation contributes to poor outcomes and early graft loss. Histone/protein deacetylases (HDACs) regulate diverse cellular processes, play a role in mediating tissue responses to IRI, and may represent a novel therapeutic target in preventing IRI in liver transplantation. METHODS: Using a previously described standardized model of murine liver warm IRI, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were assessed at 24 and 48 h after reperfusion to determine the effect of different HDAC inhibitors. RESULTS: Broad HDAC inhibition with trichostatin-A (TSA) was protective against hepatocellular damage (P < 0.01 for AST and P < 0.05 for ALT). Although HDAC class I inhibition with MS-275 provided statistically insignificant benefit, tubastatin-A (TubA), an HDAC6 inhibitor with additional activity against HDAC10, provided significant protection against liver IRI (P < 0.01 for AST and P < 0.001 for ALT). Surprisingly genetic deletion of HDAC6 or -10 did not replicate the protective effects of HDAC6 inhibition with TubA, whereas treatment with an HDAC6 BUZ-domain inhibitor, LakZnFD, eliminated the protective effect of TubA treatment in liver ischemia (P < 0.01 for AST and P < 0.01 for ALT). CONCLUSIONS: Our findings suggest TubA, a class IIb HDAC inhibitor, can mitigate hepatic IRI in a manner distinct from previously described class I HDAC inhibition and requires the HDAC6 BUZ-domain activity. Our data corroborate previous findings that HDAC targets for therapeutic intervention of IRI may be tissue-specific, and identify HDAC6 inhibition as a possible target in the treatment of liver IRI.

Titin-Truncating variants Predispose to Dilated Cardiomyopathy in Diverse Populations.

Importance: The effect of high percentage spliced in (hiPSI) TTN truncating variants (TTNtvs) on risk of dilated cardiomyopathy (DCM) has historically been studied among population subgroups defined by genetic similarity to European reference populations. This has raised questions about the effect of TTNtvs in diverse populations, especially among individuals genetically similar to African reference populations. Objective: To determine the effect of TTNtvs on risk of DCM in diverse population as measured by genetic distance (GD) in principal component (PC) space. Design: Cohort study. Setting: Penn Medicine Biobank (PMBB) is a large, diverse biobank. Participants: Participants were recruited from across the Penn Medicine healthcare system and volunteered to have their electronic health records linked to biospecimen data including DNA which has undergone whole exome sequencing. Main Outcomes and Measures: Risk of DCM among individuals carrying a hiPSI TTNtv. Results: Carrying a hiPSI TTNtv was associated with DCM among PMBB participants across a range of GD deciles from the 1000G European centroid; the effect estimates ranged from odds ratio (OR) = 3.29 (95% confidence interval [CI] 1.26 to 8.56) to OR = 9.39 (95% CI 3.82 to 23.13). When individuals were assigned to population subgroups based on genetic similarity to the 1000G reference populations, hiPSI TTNtvs conferred significant risk of DCM among those genetically similar to the 1000G European reference population (OR = 7.55, 95% CI 4.99 to 11.42, P<0.001) and individuals genetically similar to the 1000G African reference population (OR 3.50, 95% CI 1.48 to 8.24, P=0.004). Conclusions and Relevance: TTNtvs are associated with increased risk of DCM among a diverse cohort. There is no significant difference in effect of TTNtvs on DCM risk across deciles of GD from the 1000G European centroid, suggesting genetic background should not be considered when screening individuals for titin-related DCM.

Placement of Temporary Left Ventricular Assist Device Using Monitored Anesthesia Care and Regional Anesthesia.

Patients with advanced cardiogenic shock requiring mechanical circulatory support are uniquely susceptible to clinical deterioration. Limiting physiologic perturbations via avoidance of general anesthesia and endotracheal intubation by awake Impella 5.5 placement is safe and may represent a novel strategy in mechanical circulatory support initiation among patients in cardiogenic shock. (Level of Difficulty: Intermediate.).

Relationships between body fat distribution and metabolic syndrome traits and outcomes: A mendelian randomization study.

BACKGROUND: Obesity is a complex, multifactorial disease associated with substantial morbidity and mortality worldwide. Although it is frequently assessed using BMI, many epidemiological studies have shown links between body fat distribution and obesity-related outcomes. This study examined the relationships between body fat distribution and metabolic syndrome traits using Mendelian Randomization (MR). METHODS/FINDINGS: Genetic variants associated with visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue (ASAT), and gluteofemoral adipose tissue (GFAT), as well as their relative ratios, were identified from a genome wide association study (GWAS) performed with the United Kingdom BioBank. GWAS summary statistics for traits and outcomes related to metabolic syndrome were obtained from the IEU Open GWAS Project. Two-sample MR and BMI-controlled multivariable MR (MVMR) were performed to examine relationships between each body fat measure and ratio with the outcomes. Increases in absolute GFAT were associated with a protective cardiometabolic profile, including lower low density lipoprotein cholesterol (ß: -0.19, [95% CI: -0.28, -0.10], p < 0.001), higher high density lipoprotein cholesterol (ß: 0.23, [95% CI: 0.03, 0.43], p = 0.025), lower triglycerides (ß: -0.28, [95% CI: -0.45, -0.10], p = 0.0021), and decreased systolic (ß: -1.65, [95% CI: -2.69, -0.61], p = 0.0019) and diastolic blood pressures (ß: -0.95, [95% CI: -1.65, -0.25], p = 0.0075). These relationships were largely maintained in BMI-controlled MVMR analyses. Decreases in relative GFAT were linked with a worse cardiometabolic profile, with higher levels of detrimental lipids and increases in systolic and diastolic blood pressures. CONCLUSION: A MR analysis of ASAT, GFAT, and VAT depots and their relative ratios with metabolic syndrome related traits and outcomes revealed that increased absolute and relative GFAT were associated with a favorable cardiometabolic profile independently of BMI. These associations highlight the importance of body fat distribution in obesity and more precise means to categorize obesity beyond BMI.

Using a polygenic score to account for genomic risk factors in a model to detect individuals with dilated ascending thoracic aortas.

Background: Ascending thoracic aortic dilation is a complex trait that involves modifiable and non-modifiable risk factors and can lead to thoracic aortic aneurysm and dissection. Clinical risk factors have been shown to predict ascending thoracic aortic diameter. Polygenic scores (PGS) are increasingly used to assess clinical risk for multifactorial diseases. The degree to which a PGS can improve aortic diameter prediction is not known. In this study we tested the extent to which the addition of a PGS to clinical prediction algorithms improves the prediction of aortic diameter. Methods: The patient cohort comprised 6,790 Penn Medicine Biobank (PMBB) participants with available echocardiography and clinical data linked to genome-wide genotype data. Linear regression models were used to integrate PGS weights derived from a large genome wide association study of thoracic aortic diameter in the UK biobank and were compared to the performance of the standard and a reweighted variation of the recently published AORTA Score. Results: Cohort participants were 56% male, had a median age of 61 years (IQR 52-70) with a mean ascending aortic diameter of 3.4 cm (SD 0.5). Compared to the AORTA Score which explained 28.4% (95% CI 28.1% to 29.2%) of the variance in aortic diameter, AORTA Score + PGS explained 28.8%, (95% CI 28.1% to 29.6%), the reweighted AORTA score explained 30.4% (95% CI 29.6% to 31.2%), and the reweighted AORTA Score + PGS explained 31.0% (95% CI 30.2% to 31.8%). The addition of a PGS to either the AORTA Score or the reweighted AORTA Score improved model sensitivity for the identifying individuals with a thoracic aortic diameter ≥ 4 cm. The respective areas under the receiver operator characteristic curve for the AORTA Score + PGS (0.771, 95% CI 0.756 to 0.787) and reweighted AORTA Score + PGS (0.785, 95% CI 0.770 to 0.800) were greater than the standard AORTA Score (0.767, 95% CI 0.751 to 0.783) and reweighted AORTA Score (0.780 95% CI 0.765 to 0.795). Conclusions: We demonstrated that inclusion of a PGS to the AORTA Score results in a small but clinically meaningful performance enhancement. Further investigation is necessary to determine if combining genetic and clinical risk prediction improves outcomes for thoracic aortic disease.

Common- and rare-variant genetic architecture of heart failure across the allele frequency spectrum.

Heart failure (HF) is a complex trait, influenced by environmental and genetic factors, that affects over 30 million individuals worldwide. Historically, the genetics of HF have been studied in Mendelian forms of disease, where rare genetic variants have been linked to familial cardiomyopathies. More recently, genome-wide association studies (GWAS) have successfully identified common genetic variants associated with risk of HF. However, the relative importance of genetic variants across the allele-frequency spectrum remains incompletely characterized. Here, we report the results of common- and rare-variant association studies of all-cause heart failure, applying recently developed methods to quantify the heritability of HF attributable to different classes of genetic variation. We combine GWAS data across multiple populations including 207,346 individuals with HF and 2,151,210 without, identifying 176 risk loci at genome-wide significance (p < 5×10-8). Signals at newly identified common-variant loci include coding variants in Mendelian cardiomyopathy genes (MYBPC3, BAG3), as well as regulators of lipoprotein (LPL) and glucose metabolism (GIPR, GLP1R), and are enriched in cardiac, muscle, nerve, and vascular tissues, as well as myocyte and adipocyte cell types. Gene burden studies across three biobanks (PMBB, UKB, AOU) including 27,208 individuals with HF and 349,126 without uncover exome-wide significant (p < 3.15×10-6) associations for HF and rare predicted loss-of-function (pLoF) variants in TTN, MYBPC3, FLNC, and BAG3. Total burden heritability of rare coding variants (2.2%, 95% CI 0.99-3.5%) is highly concentrated in a small set of Mendelian cardiomyopathy genes, and is lower than heritability attributable to common variants (4.3%, 95% CI 3.9-4.7%) which is more diffusely spread throughout the genome. Finally, we demonstrate that common-variant background, in the form of a polygenic risk score (PRS), significantly modifies the risk of HF among carriers of pathogenic truncating variants in the Mendelian cardiomyopathy gene TTN. These findings suggest a significant polygenic component to HF exists that is not captured by current clinical genetic testing.

Relationship Between Ascending Thoracic Aortic Diameter and Blood Pressure: A Mendelian Randomization Study.

BACKGROUND: Observational studies identified elevated blood pressure (BP) as a strong risk factor for thoracic aortic dilation, and BP reduction is the primary medical intervention recommended to prevent progression of aortic aneurysms. However, although BP may impact aortic dilation, aortic size may also impact BP. The causal relationship between BP and thoracic aortic size has not been reliably established. METHODS: Genome-wide association studies summary statistics were obtained for BP and ascending thoracic aortic diameter (AscAoD). Causal effects of BP on AscAoD were estimated using 2-sample Mendelian randomization using a range of pleiotropy-robust methods. RESULTS: Genetically predicted increased systolic BP, diastolic BP, and mean arterial pressure all significantly associate with higher AscAoD (systolic BP: ß estimate, 0.0041 mm/mm Hg [95% CI, 0.0008-0.0074]; P=0.02, diastolic BP: ß estimate, 0.0272 mm/mm Hg [95% CI, 0.0224-0.0320]; P<0.001, and mean arterial pressure: ß estimate, 0.0168 mm/mm Hg [95% CI, 0.0130-0.0206]; P<0.001). Genetically predicted pulse pressure, meanwhile, had an inverse association with AscAoD (ß estimate, -0.0155 mm/mm Hg [95% CI, -0.0213 to -0.0096]; P<0.001). Multivariable Mendelian randomization analyses showed that genetically predicted increased mean arterial pressure and reduced pulse pressure were independently associated with AscAoD. Bidirectional Mendelian randomization demonstrated that genetically predicted AscAoD was inversely associated with pulse pressure (ß estimate, -2.0721 mm Hg/mm [95% CI, -3.1137 to -1.0306]; P<0.001) and systolic BP (ß estimate, -1.2878 mm Hg/mm [95% CI, -2.3533 to -0.2224]; P=0.02), while directly associated with diastolic BP (0.8203 mm Hg/mm [95% CI, 0.2735-1.3672]; P=0.004). CONCLUSIONS: BP likely contributes causally to ascending thoracic aortic dilation. Increased AscAoD likely contributes to lower systolic BP and pulse pressure, but not diastolic BP, consistent with the hemodynamic consequences of a reduced aortic diameter.

Influence of Antegrade Pulmonary Blood Flow on Outcomes of Superior Cavopulmonary Connection.

BACKGROUND: We sought to characterize short- and long-term outcomes after superior cavopulmonary connection (SCPC) in children eligible for inclusion of antegrade pulmonary blood flow (APBF) in the SCPC circuit, exploring whether maintaining APBF was associated with outcomes. METHODS: This was a retrospective cohort study of patients with single-ventricle heart disease and APBF who underwent SCPC at our center between January 1, 2000, and September 30, 2017. Patients were divided into 2 groups: APBF eliminated (APBF-), and APBF maintained (APBF+) at the time of SCPC. RESULTS: Of 149 patients, 108 (72.5%) were in APBF- and 41 (27.5%) were in APBF+. Of those in APBF+, 5 (12.2%) subsequently had APBF eliminated after SCPC. Patients in APBF+ had a higher prevalence of chest tube duration >10 days and underwent more interventions during the post-SCPC hospitalization (1.9% vs 12%; P = .008 for both) but had shorter surgical support times at SCPC (P < .0001). There were no differences in post-SCPC intensive care unit or hospital length of stay. During the study period, 82 patients (76%) in APBF- and 22 patients (54%) in APBF+ underwent Fontan completion. Patients in APBF+ had a greater weight gain from SCPC to Fontan (6.7 [1.8-22] kg vs 8.15 [4.4-20.6] kg; P = .012) and a shorter hospital length of stay after Fontan (9 [4-107] days vs 7.5 [4-14] days; P = .044). CONCLUSIONS: Short-term morbidity associated with maintaining APBF at the time of SCPC is modest, but longer term outcomes suggest potential benefits in those in whom APBF can be successfully maintained.

Raman microspectroscopy as a useful new tool in understanding thoracic aortic aneurysms.

Raman spectroscopy is a well-understood technology with novel applications in both research and clinical settings. In their article, Sugiyama and colleagues apply this technology to understand thoracic aortic aneurysm development and biomarker identification.1.

Use of carotid and axillary artery approach for stenting the patent ductus arteriosus in infants with ductal-dependent pulmonary blood flow: A multicenter study from the congenital catheterization research collaborative.

BACKGROUND: Carotid artery (CA) and axillary artery (AA) access are increasingly used for transcatheter stenting of the patent ductus arteriosus (PDA), although reports are limited. METHODS: The Congenital Catheterization Research Collaborative (CCRC) reviewed multicenter data from infants who underwent PDA stenting via the CA or AA approach from 2008 to 2017, and compared outcomes to those of infants undergoing PDA stenting via the femoral artery (FA) approach. Post-procedure ultrasound (US) imaging was reviewed. RESULTS: Forty-nine infants underwent PDA stenting from the CA (n = 43) or AA (n = 6) approach, compared with 55 infants who underwent PDA stenting from the FA approach. The PDA was the sole pulmonary blood flow (PBF) source in 61% of infants in the CA/AA cohort, compared with 33% of the FA cohort (p < .01). Ductal tortuosity for CA/AA cohort was Type I (straight) in 10 (20%), Type II (one turn) in 17 (35%), and Type III (multiple turns) in 22 (45%) infants and reflected a greater degree of tortuosity when compared to the FA cohort (p < .01). In 17 infants with CA/AA approach, the "flip technique" was used, and was associated with shorter procedure times for highly tortuous PDA (Type III) patients. Rates of procedural complications were similar across access sites. Most common complications were access site injury (thrombus or bleeding) and stent malposition. No complications were specifically related to the "flip technique." CONCLUSIONS: Use of CA and AA approach for PDA stenting was found to be more commonly employed in sole source PBF and highly tortuous PDAs. Procedural modifications such as the "flip technique" may lead to shorter procedure times. CA and AA approaches are associated with a similar burden of procedural or late complications. Post-procedural surveillance of the CA and AA is suggested, given the incidence of vascular findings on US.

Acetylation of androgen receptor by ARD1 promotes dissociation from HSP90 complex and prostate tumorigenesis.

Prostate cancer is an androgen receptor (AR)-driven disease and post-translational modification of AR is critical for AR activation. We previously reported that Arrest-defective protein 1 (ARD1) is an oncoprotein in prostate cancer. It acetylates and activates AR to promote prostate tumorigenesis. However, the ARD1-targeted residue within AR and the mechanisms of the acetylation event in prostate tumorigenesis remained unknown. In this study, we show that ARD1 acetylates AR at lysine 618 (K618) in vitro and in vivo. An AR construct with the charged lysine substitution by arginine (AR-618R) reduces RNA Pol II binding, AR transcriptional activity, prostate cancer cell growth, and xenograft tumor formation due to attenuation of AR nuclear translocation, whereas, construct mimicking neutral polar substitution acetylation at K618 by glutamine (AR-618Q) enhanced these effects beyond that of the wild-type AR. Mechanistically, ARD1 forms a ternary complex with AR and HSP90 in vitro and in vivo. Expression of ARD1 increases levels of AR acetylation and AR-HSP90 dissociation in a dose dependent manner. Moreover, the AR acetylation defective K618R mutant is unable to dissociate from HSP90 while the HSP90-dissociated AR is acetylated following ligand exposure. This work identifies a new mechanism for ligand-induced AR-HSP90 dissociation and AR activation. Targeting ARD1-mediated AR acetylation may be a potent intervention for AR-dependent prostate cancer therapy.

KIF3a promotes proliferation and invasion via Wnt signaling in advanced prostate cancer.

UNLABELLED: Aberrant activation of the Wnt/ß-catenin signaling pathway is a critical event in advanced prostate cancer, but the genetic alterations that activate the Wnt signaling pathway in many other cancers are rarely observed in prostate cancer. Other molecular mechanisms that regulate the Wnt signaling pathway in prostate cancer remain to be identified. Here, it is demonstrated that KIF3a, a subunit of kinesin-II motor protein, functions as an agonist of the Wnt signaling pathway in prostate cancer. KIF3a is upregulated in the majority of human prostate cancer cell lines and primary tumor biopsies. The expression levels of KIF3a correlate with a higher Gleason score, tumor-node-metastasis stage, and metastatic status of prostate cancer. Moreover, exogenous expression of KIF3a promoted cell growth in the benign prostate cells, whereas silencing KIF3a in cancer cells decreased cell proliferation, anchorage-independent cell growth, and cell migration/invasion. Mechanistically, KIF3a increases CK1-dependent DVL2 phosphorylation and ß-catenin activation in prostate cancer cells, leading to transactivation of the Wnt-signaling target genes such as cyclin D1, HEF1, and MMP9. These findings support the notion that upregulation of KIF3a is causal of aberrant activation of Wnt signaling in advanced prostate cancer through the KIF3a-DVL2-ß-catenin axis. IMPLICATIONS: Inactivation of KIF3a may improve survival of patients with advanced prostate cancer in which Wnt signaling is activated.

A mutation in SCARB2 is a modifier in Gaucher disease.

Lysosomal integral membrane protein type 2 (LIMP-2) is responsible for proper sorting and lysosomal targeting of glucocerebrosidase, the enzyme deficient in Gaucher disease (GD). Mutations in the gene for LIMP-2, SCARB2, are implicated in inherited forms of myoclonic epilepsy, and myoclonic epilepsy is part of the phenotypic spectrum associated with GD. We investigated whether SCARB2 mutations impact the Gaucher phenotype focusing on patients with myoclonic epilepsy, including a pair of siblings with GD who were discordant for myoclonic seizures. Sequencing of SCARB2 genomic and cDNA identified a heterozygous, maternally inherited novel mutation, c.1412A>G (p.Glu471Gly), in the brother with GD and myoclonic epilepsy, absent from his sibling and controls. Glucocerebrosidase activity, Western blots, real-time PCR, and immunofluorescence studies demonstrated markedly decreased LIMP-2 and glucocerebrosidase in cells from the sibling with (p.Glu471Gly) LIMP-2, and diminished glucocerebrosidase in lysosomes. The cells secreted highly glycosylated enzyme and showed mistrafficking of glucocerebrosidase. Sequencing of SCARB2 in 13 other subjects with GD and myoclonic epilepsy and 40 controls failed to identify additional mutations. The study provides further evidence for the association of LIMP-2 and myoclonic epilepsy, explains the drastically different phenotypes encountered in the siblings, and demonstrates that LIMP-2 can serve as a modifier in GD.

The association between mutations in the lysosomal protein glucocerebrosidase and parkinsonism.

A body of work has emerged over the past decade demonstrating a relationship between mutations in glucocerebrosidase gene (GBA), the gene implicated in Gaucher disease (GD), and the development of parkinsonism. Several different lines of research support this relationship. First, patients with GD who are homozygous for mutations in GBA have a higher than expected propensity to develop Parkinson's disease (PD). Furthermore, carriers of GBA mutations, particularly family members of patients with GD, have displayed an increased rate of parkinsonism. Subsequently, investigators from centers around the world screened cohorts of patients with parkinsonism for GBA mutations and found that overall, subjects with PD, as well as other Lewy body disorders, have at least a fivefold increase in the number of carriers of GBA mutations as compared to age-matched controls. In addition, neuropathologic studies of subjects with parkinsonism carrying GBA mutations demonstrate Lewy bodies, depletion of neurons of the substantia nigra, and involvement of hippocampal layers CA2-4. Although the basis for this association has yet to be elucidated, evidence continues to support the role of GBA as a PD risk factor across different centers, synucleinopathies, and ethnicities. Further studies of the association between GD and parkinsonism will stimulate new insights into the pathophysiology of the two disorders and will prove crucial for both genetic counseling of patients and family members and the design of relevant therapeutic strategies for specific patients with parkinsonism.