Fast skeletal myosin binding protein-C expression exacerbates dysfunction in heart failure.

During heart failure, gene and protein expression profiles undergo extensive compensatory and pathological remodeling. We previously observed that fast skeletal myosin binding protein-C (fMyBP-C) is upregulated in diseased mouse hearts. While fMyBP-C shares significant homology with its cardiac paralog, cardiac myosin binding protein-C (cMyBP-C), there are key differences that may affect cardiac function. However, it is unknown if the expression of fMyBP-C expression in the heart is a pathological or compensatory response. We aim to elucidate the cardiac consequence of either increased or knockout of fMyBP-C expression. To determine the sufficiency of fMyBP-C to cause cardiac dysfunction, we generated cardiac-specific fMyBP-C over-expression mice. These mice were further crossed into a cMyBP-C null model to assess the effect of fMyBP-C in the heart in the complete absence of cMyBP-C. Finally, fMyBP-C null mice underwent transverse aortic constriction (TAC) to define the requirement of fMyBP-C during heart failure development. We confirmed the upregulation of fMyBP-C in several models of cardiac disease, including the use of lineage tracing. Low levels of fMyBP-C caused mild cardiac remodeling and sarcomere dysfunction. Exclusive expression of fMyBP-C in a heart failure model further exacerbated cardiac pathology. Following 8 weeks of TAC, fMyBP-C null mice demonstrated greater protection against heart failure development. Mechanistically, this may be due to the differential regulation of the myosin super-relaxed state. These findings suggest that the elevated expression of fMyBP-C in diseased hearts is a pathological response. Targeted therapies to prevent upregulation of fMyBP-C may prove beneficial in the treatment of heart failure. Significance Statement: Recently, the sarcomere - the machinery that controls heart and muscle contraction - has emerged as a central target for development of cardiac therapeutics. However, there remains much to understand about how the sarcomere is modified in response to disease. We recently discovered that a protein normally expressed in skeletal muscle, is present in the heart in certain settings of heart disease. How this skeletal muscle protein affects the function of the heart remained unknown. Using genetically engineered mouse models to modulate expression of this skeletal muscle protein, we determined that expression of this skeletal muscle protein in the heart negatively affects cardiac performance. Importantly, deletion of this protein from the heart could improve heart function suggesting a possible therapeutic avenue.

Sex Differences in Cardiovascular Outcomes in Patients With Kidney Failure.

BACKGROUND: Cardiovascular disease is the leading cause of mortality in patients with kidney failure, and their risk of cardiovascular events is 10 to 20 times higher as compared with the general population. METHODS AND RESULTS: We evaluated 508 822 patients who initiated dialysis between January 1, 2005 and December 31, 2014 using the United States Renal Data System with linked Medicare claims. We determined hospitalization rates for cardiovascular events, defined by acute coronary syndrome, heart failure, and stroke. We examined the association of sex with outcome of cardiovascular events, cardiovascular death, and all-cause death using adjusted time-to-event models. The mean age was 70±12 years and 44.7% were women. The cardiovascular event rate was 232 per thousand person-years (95% CI, 231-233), with a higher rate in women than in men (248 per thousand person-years [95% CI, 247-250] versus 219 per thousand person-years [95% CI, 217-220]). Women had a 14% higher risk of cardiovascular events than men (hazard ratio [HR], 1.14 [95% CI, 1.13-1.16]). Women had a 16% higher risk of heart failure (HR, 1.16 [95% CI, 1.15-1.18]), a 31% higher risk of stroke (HR, 1.31 [95% CI, 1.28-1.34]), and no difference in risk of acute coronary syndrome (HR, 1.01 [95% CI, 0.99-1.03]). Women had a lower risk of cardiovascular death (HR, 0.89 [95% CI, 0.88-0.90]) and a lower risk of all-cause death than men (HR, 0.96 [95% CI, 0.95-0.97]). CONCLUSIONS: Among patients undergoing dialysis, women have a higher risk of cardiovascular events of heart failure and stroke than men. Women have a lower adjusted risk of cardiovascular mortality and all-cause mortality.

Research Initiative Supporting Excellence at the University of Cincinnati (RISE-UC): A Program to Develop and Support Research-Active Faculty Members.

A combination of forces have markedly increased challenges to research-active faculty achieving sustained success. This article describes how one department at the University of Cincinnati College of Medicine (UCCOM) implemented a strategic plan, the Research Initiative Supporting Excellence at the University of Cincinnati (RISE-UC), to promote the research activity of its research-active faculty, fiscal year (FY) 2011-FY 2021. RISE-UC was implemented and regularly updated to address evolving needs. RISE-UC supported faculty members pursuing research via fiscal and administrative services to grow a critical mass of investigators; establish a shared governance model; create pathways for developing physician-scientists; develop discrete and targeted internal research funding; establish an Academic Research Service (ARS) unit (as infrastructure to support research); enhance faculty member mentorship; and recognize, celebrate, and reward research success. RISE-UC was informed by shared governance and resulted in substantial increases in total size of the faculty and external funding. More than 50% of Physician-Scientist Training Program graduates are active researchers at UCCOM. The internal awards program realized a return on investment of ~16.4-fold, and total external direct cost research funds increased from ~$55,400,000 (FY 2015) to ~$114,500,000 (FY 2021). The ARS assisted in the submission of 57 grant proposals and provided services faculty members generally found very helpful or helpful. The peer-mentoring group for early-career faculty members resulted in 12 of 23 participants receiving major grant funding (≥ $100,000; spring 2017-spring 2021) from sources including National Institutes of Health awards, Department of Defense funding, Veterans Affairs funding, and foundation awards. Research recognition included ~$77,000/year in incentive payments to faculty members for grant submissions and grants awarded. RISE-UC is an example of a comprehensive approach to promote research faculty member success and may serve as a model for other institutions with similar aspirations.

Pragmatic evaluation of events and benefits of lipid lowering in older adults (PREVENTABLE): Trial design and rationale.

Whether initiation of statins could increase survival free of dementia and disability in adults aged ≥75 years is unknown. PREVENTABLE, a double-blind, placebo-controlled randomized pragmatic clinical trial, will compare high-intensity statin therapy (atorvastatin 40 mg) with placebo in 20,000 community-dwelling adults aged ≥75 years without cardiovascular disease, disability, or dementia at baseline. Exclusion criteria include statin use in the prior year or for >5 years and inability to take a statin. Potential participants are identified using computable phenotypes derived from the electronic health record and local referrals from the community. Participants will undergo baseline cognitive testing, with physical testing and a blinded lipid panel if feasible. Cognitive testing and disability screening will be conducted annually. Multiple data sources will be queried for cardiovascular events, dementia, and disability; survival is site-reported and supplemented by a National Death Index search. The primary outcome is survival free of new dementia or persisting disability. Co-secondary outcomes are a composite of cardiovascular death, hospitalization for unstable angina or myocardial infarction, heart failure, stroke, or coronary revascularization; and a composite of mild cognitive impairment or dementia. Ancillary studies will offer mechanistic insights into the effects of statins on key outcomes. Biorepository samples are obtained and stored for future study. These results will inform the benefit of statins for increasing survival free of dementia and disability among older adults. This is a pioneering pragmatic study testing important questions with low participant burden to align with the needs of the growing population of older adults.

Myofilament Alterations Associated with Human R14del-Phospholamban Cardiomyopathy.

Phospholamban (PLN) is a major regulator of cardiac contractility, and human mutations in this gene give rise to inherited cardiomyopathies. The deletion of Arginine 14 is the most-prevalent cardiomyopathy-related mutation, and it has been linked to arrhythmogenesis and early death. Studies in PLN-humanized mutant mice indicated an increased propensity to arrhythmias, but the underlying cellular mechanisms associated with R14del-PLN cardiac dysfunction in the absence of any apparent structural remodeling remain unclear. The present study addressed the specific role of myofilaments in the setting of R14del-PLN and the long-term effects of R14del-PLN in the heart. Maximal force was depressed in skinned cardiomyocytes from both left and right ventricles, but this effect was more pronounced in the right ventricle of R14del-PLN mice. In addition, the Ca2+ sensitivity of myofilaments was increased in both ventricles of mutant mice. However, the depressive effects of R14del-PLN on contractile parameters could be reversed with the positive inotropic drug omecamtiv mecarbil, a myosin activator. At 12 months of age, corresponding to the mean symptomatic age of R14del-PLN patients, contractile parameters and Ca2+ transients were significantly depressed in the right ventricular R14del-PLN cardiomyocytes. Echocardiography did not reveal any alterations in cardiac function or remodeling, although histological and electron microscopy analyses indicated subtle alterations in mutant hearts. These findings suggest that both aberrant myocyte calcium cycling and aberrant contractility remain specific to the right ventricle in the long term. In addition, altered myofilament activity is an early characteristic of R14del-PLN mutant hearts and the positive inotropic drug omecamtiv mecarbil may be beneficial in treating R14del-PLN cardiomyopathy.

A humanized anti-cocaine mAb antagonizes the cardiovascular effects of cocaine in rats.

The recombinant monoclonal anti-cocaine antibody, h2E2, sequesters cocaine in plasma increasing concentrations more than 10-fold. The increased levels of cocaine in the plasma could have detrimental peripheral effects, particularly on the cardiovascular system. We investigated the duration and magnitude of the effect of cocaine on the rat heart, and if h2E2 could antagonize that effect. Echocardiography was used to evaluate cardiac function under isoflurane anesthesia, while a tail-cuff was used to measure blood pressure. Cocaine was delivered intravenously and the rats were continuously monitored for a total of 45 min. Echocardiography measurements were recorded every 5 min and blood pressure measurements were recorded throughout the duration of the experiment using 30-s cycles. ECG recordings were taken simultaneously with the echocardiography measurements. An increase in ejection fraction was seen after the cocaine push with the maximum change occurring at 25 min. Treatment with h2E2 1 h before the cocaine push did not have any effect on cardiac parameters. Subsequent cocaine treatment had no effect on the ejection fraction, indicating that the antibody-bound cocaine does not affect the heart. This antagonism of cocaine's effects was greatly decreased after 1 week and entirely absent after 1 month. Cocaine in the presence of h2E2 is pharmacologically inert and h2E2 may have additional clinical utility for reversing cocaine effects on the cardiovascular system.

Tefillin use induces preconditioning associated changes in heart rate variability.

Short bouts of occlusion of blood flow can induce a preconditioning response that reduces subsequent damage from longer periods of ischemia. It has been shown that ischemic preconditioning (IPC) can be elicited remotely (RIPC) through limitation of blood flow and as recently described via only pain sensation. Non-obstructive banding (NOB) through the donning of tefillin (a box with sacred texts attached to a leather strap that is traditionally bound to the non-dominant arm of Jewish adults during morning prayers) has been shown to elicit an RIPC response at least partially through pain sensation. This study evaluated the effects of NOB on heart rate variability (HRV) dependent factors that are known to be affected by various RIPC stimuli. We recruited 30 healthy subjects and subjected them to NOB versus control and found various HRV markers associated with RIPC to be changed in the NOB group. This finding provides further evidence that tefillin, likely through NOB induced RIPC changes, may still be a viable clinical pathway to prevent and decrease the morbidity associated with ischemic events.

Drug repurposing for cardiovascular diseases: New targets and indications for probenecid.

The available pharmacological options in the management of cardiovascular diseases such as ischaemic heart disease and subsequent heart failure are effective in slowing the progression of this condition. However, the long-term prognosis is still poor, raising the demand for new therapeutic strategies. Drug repurposing is a time- and cost-effective drug development strategy that offers approved and abandoned drugs a new chance for new indications. Recently, drugs used for the management of gout-related inflammation such as canakinumab or colchicine have been considered for drug repurposing in cardiovascular indications. The old uricosuric drug, probenecid, has been identified as a novel therapeutic option in the management of specific cardiac diseases as well. Probenecid can modulate myocardial contractility and vascular tone and exerts anti-inflammatory properties. The mechanisms behind these beneficial effects might be related inhibition of inflammasomes, and to modulation purinergic-pannexin-1 signalling and TRPV2 channels, which are recently identified molecular targets of probenecid. In this review, we provide an overview on repurposing probenecid for ischaemic heart disease and subsequent heart failure by summarizing the related experimental and clinical data and propose its potential repurposing to treat cardiovascular diseases.

Review of the Cardiovascular Implications of the Social and Religious Practices Associated with Donning Phylacteries.

We previously published a manuscript suggesting that use of phylacteries, ritual straps worn during Jewish prayer services, affects cardiovascular and inflammatory function (Owens et al., Am J Physiol-Heart Circ Physiol, 315(6):H1748-H1758, 2018). Observed physiologic changes were associated with improved cardiac outcomes, though a direct link between phylactery use and improved cardiovascular outcomes is difficult to prove as there are a number of associated religious and spiritual practices that may confound the observed effects. In this review, we assess the scientific literature regarding religious and spiritual practices associated with phylactery in order to better understand the cardiovascular implications of the practice of donning phylacteries. We focus on key aspects traditionally associated with donning phylacteries including gathering in groups, meditation and prayer.

Repurposing Probenecid for the Treatment of Heart Failure (Re-Prosper-HF): a study protocol for a randomized placebo-controlled clinical trial.

BACKGROUND: Improving contractility in heart failure with reduced ejection fraction (HFrEF) has resurfaced as a potential treatment goal. Inotropic therapy is now better understood through its underlying mechanism as opposed to the observed effect of increasing contractility. Calcitropes are a subgroup of inotropes that largely depend on the stimulation of adenylyl cyclase to transform ATP into cyclic adenosine monophosphate (cAMP). At least two clinically relevant calcitropes-istaroxime and probenecid-improve contractility through an increase in systolic intracellular calcium without activating cAMP production. Probenecid, which has been safely used clinically for decades in non-cardiac conditions, has recently been identified as an agonist of the transient receptor potential vanilloid 2 channel. Translational studies have shown that it improves calcium cycling and contractility without activating noxious pathways associated with cAMP-dependent calcitropes and can improve cardiac function in patients with HFrEF. METHODS: The Re-Prosper-HF study (Repurposing Probenecid for the Treatment of Heart Failure with Reduced Ejection Fraction) is a three-site double-blinded randomized-controlled trial that will test the hypothesis that probenecid can improve cardiac function in patients with HFrEF. Up to 120 patients will be randomized in this double-blind, placebo-controlled study that will assess whether oral probenecid administered at 1 g orally twice per day for 180 days in patients with NYHA II-III HFrEF improves systolic function (aim 1), functional status (aim 2), and self-reported health status (aim 3). DISCUSSION: Findings from this study will provide data informing its use for improving symptomatology in patients with HFrEF as well as exploratory data for outcomes such as hospital admission rates. TRIAL TEGISTRATION: The Re-Prosper HF Study (Re-Prosper HF) is registered on ClinicalTrials.gov with the identifier as NCT04551222. Registered on 9 September 2020.

Role of Known Transient Receptor Potential Vanilloid Channels in Modulating Cardiac Mechanobiology.

The transient receptor potential (TRP) channels have been described in almost every mammalian cell type. Several members of the Vanilloid (TRPV) subtype have been found to play important roles in modulating cardiac structure and function through Ca2+ handling in response to systemic and local mechanobiological cues. In this review, we will consider the most studied TRPV channels in the cardiovascular field; transient receptor potential vanilloid 1 as a modulator of cardiac hypertrophy; transient receptor potential vanilloid 2 as a structural and functional protein; transient receptor potential vanilloid 3 in the development of hypertrophy and myocardial fibrosis; and transient receptor potential vanilloid 4 in its roles modulating the fibrotic and functional responses of the heart to pressure overload. Lastly, we will also review the potential overlapping roles of these channels with other TRP proteins as well as the advances in translational and clinical arenas associated with TRPV channels.

Impaired Right Ventricular Calcium Cycling Is an Early Risk Factor in R14del-Phospholamban Arrhythmias.

The inherited mutation (R14del) in the calcium regulatory protein phospholamban (PLN) is linked to malignant ventricular arrhythmia with poor prognosis starting at adolescence. However, the underlying early mechanisms that may serve as prognostic factors remain elusive. This study generated humanized mice in which the endogenous gene was replaced with either human wild type or R14del-PLN and addressed the early molecular and cellular pathogenic mechanisms. R14del-PLN mice exhibited stress-induced impairment of atrioventricular conduction, and prolongation of both ventricular activation and repolarization times in association with ventricular tachyarrhythmia, originating from the right ventricle (RV). Most of these distinct electrocardiographic features were remarkably similar to those in R14del-PLN patients. Studies in isolated cardiomyocytes revealed RV-specific calcium defects, including prolonged action potential duration, depressed calcium kinetics and contractile parameters, and elevated diastolic Ca-levels. Ca-sparks were also higher although SR Ca-load was reduced. Accordingly, stress conditions induced after contractions, and inclusion of the CaMKII inhibitor KN93 reversed this proarrhythmic parameter. Compensatory responses included altered expression of key genes associated with Ca-cycling. These data suggest that R14del-PLN cardiomyopathy originates with RV-specific impairment of Ca-cycling and point to the urgent need to improve risk stratification in asymptomatic carriers to prevent fatal arrhythmias and delay cardiomyopathy onset.

Pharmacologic Inhibition of Pain Response to Incomplete Vascular Occlusion Blunts Cardiovascular Preconditioning Response.

Complete vascular occlusion to distant tissue prior to an ischemic cardiac event can provide significant cardioprotection via remote ischemic preconditioning (RIPC). Despite understanding its mechanistic basis, its translation to clinical practice has been unsuccessful, likely secondary to the inherent impossibility of predicting (and therefore preconditioning) an ischemic event, as well as the discomfort that is associated with traditional, fully occlusive RIPC stimuli. Our laboratory has previously shown that non-occlusive banding (NOB) via wrapping of a leather band (similar to a traditional Jewish ritual) can elicit an RIPC response in healthy human subjects. This study sought to further the pain-mediated aspect of this observation in a mouse model of NOB with healthy mice that were exposed to treatment with and without lidocaine to inhibit pain sensation prior to ischemia/reperfusion injury. We demonstrated that NOB downregulates key inflammatory markers resulting in a preconditioning response that is partially mediated via pain sensation.

Developmental and lifelong dioxin exposure induces measurable changes in cardiac structure and function in adulthood.

Congenital heart disease (CHD) is the most common congenital abnormality. A precise etiology for CHD remains elusive, but likely results from interactions between genetic and environmental factors during development, when the heart adapts to physiological and pathophysiological conditions. Further, it has become clearer that early exposure to toxins that do not result in overt CHD may be associated with adverse cardiac outcomes that are not manifested until later life. Previously, interference with endogenous developmental functions of the aryl hydrocarbon receptor (AHR), either by gene ablation or by in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent AHR ligand, was shown to cause structural, molecular and functional cardiac abnormalities and altered heart physiology in mouse embryos. Here, we show that continuous exposure to TCDD from fertilization throughout adulthood caused male mice to underperform at exercise tolerance tests compared to their control and female counterparts, confirming previous observations of a sexually dimorphic phenotype. Renin-angiotensin stimulation by angiotensin II (Ang II) caused measurable increases in blood pressure and left ventricle mass, along with decreased end diastolic volume and preserved ejection fraction. Interestingly, TCDD exposure caused measurable reductions in the myocardial hypertrophic effects of Ang II, suggesting that endogenous AHR signaling present in adulthood may play a role in the pathogenesis of hypertrophy. Overall, the findings reported in this pilot study highlight the complex systems underlying TCDD exposure in the development of cardiac dysfunction in later life.

Clinical Characteristics, Respiratory Mechanics, and Outcomes in Critically Ill Individuals With COVID-19 Infection in an Underserved Urban Population.

BACKGROUND: The COVID-19 outbreak in the United States has disproportionately affected Black individuals, but little is known about the factors that underlie this observation. Herein, we describe these associations with mortality in a largely minority underserved population. METHODS: This single-center retrospective observational study included all adult subjects with laboratory-confirmed SARS-Cov-2 treated in our ICU between March 15 and May 10, 2020. RESULTS: 128 critically ill adult subjects were included in the study (median age 68 y [interquartile range 61-76], 45% female, and 64% Black); 124 (97%) required intubation. Eighty (63%) subjects died during their in-patient stay, which did not differ by race/ethnicity. Compared with other racial/ethnic groups, Blacks had a greater proportion of women (52% vs 30%, P = .02) and subjects with hypertension (91% vs 78%, P = .035). Asthma (P = .03) was associated with lower in-patient death, primarily among Black subjects (P = .02). Among Black subjects, increased age (odds ratio 1.06 [95% CI 1.05-1.22] per year), positive fluid balance (odds ratio 1.06 [95% CI 1.01-1.11] per 100 mL), and treatment with tocilizumab (odds ratio 25.0 [95% CI 3.5-180]) were independently associated with in-patient death, while higher platelets (odds ratio 0.65 [95% CI 0.47-0.89] per 50 × 103/mL) and treatment with intermediate dose anticoagulants (odds ratio 0.08 [95% CI 0.02-0.43]) were protective. Among other race/ethnic groups, higher total bilirubin (odds ratio 1.75 [95% CI 0.94-3.25] per 0.2 mg/dL) and higher maximum lactate (odds ratio 1.43 [95% CI 0.96-2.13] per mmol/L) were marginally associated with increased death, while tocilizumab treatment was marginally protective (odds ratio 0.24 [95% CI 0.05-1.25]). During first 72 h of ventilation, those who died had less increase in [Formula: see text] (P = .046) and less reduction in PEEP (P = .01) and [Formula: see text] requirement (P = .002); these patterns did not differ by race/ethnicity. CONCLUSIONS: Black and other race/ethnicity subjects had similar mortality rates due to COVID-19 but differed in factors that were associated with increased risk of death. In both groups, subjects who died were older, had a positive fluid balance, and less improvement in [Formula: see text], PEEP, and [Formula: see text] requirement on ventilation.

South Asian-Specific MYBPC3 Δ25bp Deletion Carriers Display Hypercontraction and Impaired Diastolic Function Under Exercise Stress.

Background: A 25-base pair (25bp) intronic deletion in the MYBPC3 gene enriched in South Asians (SAs) is a risk allele for late-onset left ventricular (LV) dysfunction, hypertrophy, and heart failure (HF) with several forms of cardiomyopathy. However, the effect of this variant on exercise parameters has not been evaluated. Methods: As a pilot study, 10 asymptomatic SA carriers of the MYBPC3 Δ25bp variant (52.9 ± 2.14 years) and 10 age- and gender-matched non-carriers (NCs) (50.1 ± 2.7 years) were evaluated at baseline and under exercise stress conditions using bicycle exercise echocardiography and continuous cardiac monitoring. Results: Baseline echocardiography parameters were not different between the two groups. However, in response to exercise stress, the carriers of Δ25bp had significantly higher LV ejection fraction (%) (CI: 4.57 ± 1.93; p < 0.0001), LV outflow tract peak velocity (m/s) (CI: 0.19 ± 0.07; p < 0.0001), and higher aortic valve (AV) peak velocity (m/s) (CI: 0.103 ± 0.08; p = 0.01) in comparison to NCs, and E/A ratio, a marker of diastolic compliance, was significantly lower in Δ25bp carriers (CI: 0.107 ± 0.102; p = 0.038). Interestingly, LV end-diastolic diameter (LVIDdia) was augmented in NCs in response to stress, while it did not increase in Δ25bp carriers (CI: 0.239 ± 0.125; p = 0.0002). Further, stress-induced right ventricular systolic excursion velocity s' (m/s), as a marker of right ventricle function, increased similarly in both groups, but tricuspid annular plane systolic excursion increased more in carriers (slope: 0.008; p = 0.0001), suggesting right ventricle functional differences between the two groups. Conclusions: These data support that MYBPC3 Δ25bp is associated with LV hypercontraction under stress conditions with evidence of diastolic impairment.

Barriers and Solutions to Passing State Legislation to Protect the Rights of Parents With Disabilities: Lessons From Interviews With Advocates, Attorneys, and Legislators.

Parents with disabilities experience discrimination within the child welfare, family law, and adoption and foster care systems. In response, there have been increasing calls for states to pass legislation prohibiting discrimination against parents with disabilities, and as of 2020, 28 states have passed or are considering such legislation. This qualitative study explored the perspectives of 19 advocates, attorneys, and legislators on barriers and solutions for passing legislation to protect the rights of parents with disabilities. Participants identified three barriers: (a) legislators' pejorative attitudes toward parents with disabilities, (b) external opposition, and (c) legislative barriers. Participants also identified eight solutions: (a) cross-disability advocacy, (b) education, (c) relationship-building, (d) bipartisanship, (e) support from state and national organizations, (f) strong sponsors, (g) incrementalism, and (h) model legislation. Study findings should help to inform ongoing legislative advocacy to protect the rights of parents with disabilities.

Sectm1a deficiency aggravates inflammation-triggered cardiac dysfunction through disruption of LXRα signalling in macrophages.

AIMS: Cardiac dysfunction is a prevalent comorbidity of disrupted inflammatory homeostasis observed in conditions such as sepsis (acute) or obesity (chronic). Secreted and transmembrane protein 1a (Sectm1a) has previously been implicated to regulate inflammatory responses, yet its role in inflammation-associated cardiac dysfunction is virtually unknown. METHODS AND RESULTS: Using the CRISPR/Cas9 system, we generated a global Sectm1a-knockout (KO) mouse model and observed significantly increased mortality and cardiac injury after lipopolysaccharide (LPS) injection, when compared with wild-type (WT) control. Further analysis revealed significantly increased accumulation of inflammatory macrophages in hearts of LPS-treated KO mice. Accordingly, ablation of Sectm1a remarkably increased inflammatory cytokines levels both in vitro [from bone marrow-derived macrophages (BMDMs)] and in vivo (in serum and myocardium) after LPS challenge. RNA-sequencing results and bioinformatics analyses showed that the most significantly down-regulated genes in KO-BMDMs were modulated by LXRα, a nuclear receptor with robust anti-inflammatory activity in macrophages. Indeed, we identified that the nuclear translocation of LXRα was disrupted in KO-BMDMs when treated with GW3965 (LXR agonist), resulting in higher levels of inflammatory cytokines, compared to GW3965-treated WT-cells. Furthermore, using chronic inflammation model of high-fat diet (HFD) feeding, we observed that infiltration of inflammatory monocytes/macrophages into KO-hearts were greatly increased and accordingly, worsened cardiac function, compared to WT-HFD controls. CONCLUSION: This study defines Sectm1a as a new regulator of inflammatory-induced cardiac dysfunction through modulation of LXRα signalling in macrophages. Our data suggest that augmenting Sectm1a activity may be a potential therapeutic approach to resolve inflammation and associated cardiac dysfunction.

TRPV2 channel-based therapies in the cardiovascular field. Molecular underpinnings of clinically relevant therapies.

The transient receptor potential (TRP) ion channel family is composed of twenty-seven channel proteins that are ubiquitously expressed in the human body. The TRPV (vanilloid) subfamily has been a recent target of investigation within the cardiovascular field. TRPV1, which is sensitive to heat as well as vanilloids, is the best characterized TRPV channel and is the namesake for the subfamily that includes six members. Research into the function of TRPV2 has suggested that it plays an important role in cardiovascular function. Over the last twenty years a greater understanding of the differences among the TRPV channels has allowed for more precise experimentation and has opened various translational opportunities. TRPV2 has been found to be a both a mechanosensor and a mediator of calcium handling and has been found to play important roles in healthy and diseased cardiomyocytes. These roles have been translated into clinical studies in patients with muscular dystrophy (both agonism and antagonism) as well as in patients with cardiomyopathy and heart failure with reduced ejection fraction. Its role as a structural protein has also been elucidated, though the clinical significance of this finding has yet to be established. Despite the clinical progress that has been made there is still a need for large, prospective randomized studies with TRPV2 channel agonists and antagonists in order to bring these basic and translational science findings to the bedside.

Dioxin Disrupts Dynamic DNA Methylation Patterns in Genes That Govern Cardiomyocyte Maturation.

Congenital heart disease (CHD), the leading birth defect worldwide, has a largely unknown etiology, likely to result from complex interactions between genetic and environmental factors during heart development, at a time when the heart adapts to diverse physiological and pathophysiological conditions. Crucial among these is the regulation of cardiomyocyte development and postnatal maturation, governed by dynamic changes in DNA methylation. Previous work from our laboratory has shown that exposure to the environmental toxicant tetrachlorodibenzo-p-dioxin (TCDD) disrupts several molecular networks responsible for heart development and function. To test the hypothesis that the disruption caused by TCDD in the heart results from changes in DNA methylation and gene expression patterns of cardiomyocytes, we established a stable mouse embryonic stem cell line expressing a puromycin resistance selectable marker under control of the cardiomyocyte-specific Nkx2-5 promoter. Differentiation of these cells in the presence of puromycin induces the expression of a large suite of cardiomyocyte-specific markers. To assess the consequences of TCDD treatment on gene expression and DNA methylation in these cardiomyocytes, we subjected them to transcriptome and methylome analyses in the presence of TCDD. Unlike control cardiomyocytes maintained in vehicle, the TCDD-treated cardiomyocytes showed extensive gene expression changes, with a significant correlation between differential RNA expression and DNA methylation in 111 genes, many of which are key elements of pathways that regulate cardiovascular development and function. Our findings provide an important clue toward the elucidation of the complex interactions between genetic and epigenetic mechanisms after developmental TCDD exposure that may contribute to CHD.