Microvascular Paradigm in Heart Failure With Preserved Ejection Fraction: A Quest for Proof of Concept

Benzene metabolites increase vascular permeability by activating heat shock proteins and Rho GTPases

Benzene is a ubiquitous environmental and occupational pollutant abundant in household products, petrochemicals, and cigarette smoke. It is also a well-known carcinogen and hematopoietic toxin. Population-based studies indicate an increased risk of heart failure in subjects exposed to inhaled benzene, which coincides with the infiltration of immune cells into the myocardium. However, the mechanisms of benzene-induced cardiovascular disease remain unknown. Our data suggests that benzene metabolites trans,trans-muconaldehyde (MA), and hydroquinone (HQ) propagate endothelial activation and apoptosis analyzed by endothelial-specific microparticles in C57BL/6J mice plasma. Subcutaneous injections of MA and HQ increased vascular permeability by 1.54 fold and 1.27 fold correspondingly. In addition, the exposure of primary cardiac microvascular endothelial cells to MA increased vascular permeability detected by transendothelial monolayer resistance and by fluorescently labeled dextrans diffusion. The bulk RNA sequencing of endothelial cells exposed to MA for 2, 6, and 24 hours showed MA-dependent upregulation of heat shock-related pathways at 2 and 6 hours, dysregulation of GTPases at 6 hours, and altered cytoskeleton organization at 24 hours of exposure. We found that the HSP70 protein induced by MA in endothelial cells is colocalized with F-actin foci. HSP70 inhibitor 17AAG and HSP90 inhibitor JG98 attenuated MA-induced endothelial permeability, while HSP activator TRC enhanced endothelial leakage. Moreover, MA induced Rac1 GTPase activity, while Rho GTPase inhibitor Y-27632 attenuated MA-induced endothelial permeability. We showed that benzene metabolites compromised the endothelial barrier by altering HSP- and GTPase-related signaling pathways.

Multi-omics approach for identification of molecular alterations of QiShenYiQi dripping pills in heart failure with preserved ejection fraction

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine theory believes that qi deficiency and blood stasis are the key pathogenesis of heart failure with preserved ejection fraction (HFpEF). As a representative prescription for replenishing qi and activating blood, QiShenYiQi dripping pills (QSYQ) has been used for treating heart diseases. However, the pharmacological mechanism of QSYQ in improving HFpEF is not well understood.

AIM OF THE STUDY

The objective of the study is to investigate the cardioprotective effect and mechanism of QSYQ in HFpEF using the phenotypic dataset of HFpEF.

MATERIALS AND METHODS

HFpEF mouse models established by feeding mice combined high-fat diet and N^ω-nitro-L-arginine methyl ester drinking water were treated with QSYQ. To reveal causal genes, we performed a multi-omics study, including integrative analysis of transcriptomics, proteomics, and metabolomics data. Moreover, adeno-associated virus (AAV)-based PKG inhibition confirmed that QSYQ mediated myocardial remodeling through PKG.

RESULTS

Computational systems pharmacological analysis based on human transcriptome data for HFpEF showed that QSYQ could potentially treat HFpEF through multiple signaling pathways. Subsequently, integrative analysis of transcriptome and proteome showed alterations in gene expression in HFpEF. QSYQ regulated genes involved in inflammation, energy metabolism, myocardial hypertrophy, myocardial fibrosis, and cGMP-PKG signaling pathway, confirming its function in the pathogenesis of HFpEF. Metabolomics analysis revealed fatty acid metabolism as the main mechanism by which QSYQ regulates HFpEF myocardial energy metabolism. Importantly, we found that the myocardial protective effect of QSYQ on HFpEF mice was attenuated after RNA interference-mediated knock-down of myocardial PKG.

CONCLUSION

This study provides mechanistic insights into the pathogenesis of HFpEF and molecular mechanisms of QSYQ in HFpEF. We also identified the regulatory role of PKG in myocardial stiffness, making it an ideal therapeutic target for myocardial remodeling.

Increased Capillary Permeability in Heart Induces Diastolic Dysfunction Independently of Inflammation, Fibrosis, or Cardiomyocyte Dysfunction

BACKGROUND

While endothelial dysfunction is suggested to contribute to heart failure with preserved ejection fraction pathophysiology, understanding the importance of the endothelium alone, in the pathogenesis of diastolic abnormalities has not yet been fully elucidated. Here, we investigated the consequences of specific endothelial dysfunction on cardiac function, independently of any comorbidity or risk factor (diabetes or obesity) and their potential effect on cardiomyocyte.

METHODS

The ubiquitine ligase Pdzrn3, expressed in endothelial cells (ECs), was shown to destabilize tight junction. A genetic mouse model in which Pdzrn3 is overexpressed in EC (iEC-Pdzrn3) in adults was developed.

RESULTS

EC-specific Pdzrn3 expression increased cardiac leakage of IgG and fibrinogen blood-born molecules. The induced edema demonstrated features of diastolic dysfunction, with increased end-diastolic pressure, alteration of dP/dt min, increased natriuretic peptides, in addition to limited exercise capacity, without major signs of cardiac fibrosis and inflammation. Electron microscopic images showed edema with disrupted EC-cardiomyocyte interactions. RNA sequencing analysis of gene expression in cardiac EC demonstrated a decrease in genes coding for endothelial extracellular matrix proteins, which could be related to the fragile blood vessel phenotype. Irregularly shaped capillaries with hemorrhages were found in heart sections of iEC-Pdzrn3 mice. We also found that a high-fat diet was not sufficient to provoke diastolic dysfunction; high-fat diet aggravated cardiac inflammation, associated with an altered cardiac metabolic signature in EC-Pdzrn3 mice, reminiscent of heart failure with preserved ejection fraction features.

CONCLUSIONS

An increase of endothelial permeability is responsible for mediating diastolic dysfunction pathophysiology and for aggravating detrimental effects of a high-fat diet on cardiac inflammation and metabolism.

Exercise Intolerance in Older Adults With Heart Failure With Preserved Ejection Fraction: JACC State-of-the-Art Review

Exercise intolerance (EI) is the primary manifestation of chronic heart failure with preserved ejection fraction (HFpEF), the most common form of heart failure among older individuals. The recent recognition that HFpEF is likely a systemic, multiorgan disorder that shares characteristics with other common, difficult-to-treat, aging-related disorders suggests that novel insights may be gained from combining knowledge and concepts from aging and cardiovascular disease disciplines. This state-of-the-art review is based on the outcomes of a National Institute of Aging-sponsored working group meeting on aging and EI in HFpEF. We discuss aging-related and extracardiac contributors to EI in HFpEF and provide the rationale for a transdisciplinary, "gero-centric" approach to advance our understanding of EI in HFpEF and identify promising new therapeutic targets. We also provide a framework for prioritizing future research, including developing a uniform, comprehensive approach to phenotypic characterization of HFpEF, elucidating key geroscience targets for treatment, and conducting proof-of-concept trials to modify these targets.

Myocardial ischemia and coronary disease in heart failure

Heart failure is a complex clinical syndrome and represents the final path of numerous heart diseases. Coronary artery disease is recognized as the primary risk factor for heart failure development, being the main etiological factor in more than 50% of heart failure patients in North America and Europe. Regardless of overt coronary artery disease, myocardial ischemia is a common finding in failing hearts, likely due to structural or functional coronary circulation alterations. Ischemia is a self-propagating process which irreversibly impairs the cardiac function and negatively impacts prognosis. Thus, a better and thorough understanding of myocardial ischemia pathophysiology in heart failure would likely lead to significantly improved outcomes in these patients. This review aims to describe the mechanisms of myocardial ischemia and coronary artery disease in heart failure, focusing on coronary circulation dysfunctions due to increased parietal stress or non-obstructive coronary disease, and discussing the association and management of coronary artery disease in patients with heart failure.

Heart Failure With Preserved Ejection Fraction: Is Ischemia Due to Coronary Microvascular Dysfunction a Mechanistic Factor?

Heart failure with preserved ejection fraction (HFpEF) is increasing in prevalence and has no guideline-recommended therapy, related in part to a lack of mechanism. Traditionally, HFpEF was thought to be secondary to afterload overload due to systemic hypertension; however, accumulating evidence suggests that HFpEF continues to worsen despite adequate control of blood pressure. Emerging data support the suggestion that myocardial ischemia secondary to coronary microvascular dysfunction could be the new paradigm pathophysiology. Several prospective, observational cohort studies indicate that the outcomes of patients with microvascular dysfunction, after an interval of several years, are dominated by HFpEF hospitalizations. Further, the most prevalent clinical phenotype (eg older women with multiple comorbidities) of patients with HFpEF resembles those with coronary microvascular dysfunction, albeit older. In this review, we provide in-depth insight about this emerging HFpEF paradigm, discuss potential therapeutic implications of this pathophysiology, and summarize some important knowledge gaps.

Microvascular dysfunction in ankylosing spondylitis is associated with disease activity and is improved by anti-TNF treatment

Ankylosing spondylitis (AS) is associated with high cardiovascular morbidity and mortality. Recent studies indicate that microvascular dysfunction may underlie cardiovascular risk in AS. We hypothesized, that microvascular morphology and dysfunction is linked to AS activity and is modifiable by TNF-α inhibitor (TNFi) treatment. Functional Laser Doppler Flowmetry with post-occlusive reactive hyperemia, and structural nailfold capillaroscopy were performed in 54 patients with AS and 28 matched controls. Active AS was diagnosed based on BASDAI ≥ 4 (n = 37). Effects of 3-month TNFi on microcirculation in active AS were studied. AS was associated with prolonged time to peak hyperemia compared to healthy controls. High disease activity was associated with increased time to peak hyperemia and decreased peak hyperemia when compared to patients with inactive AS. In capillaroscopy, AS was associated with morphological abnormalities indicating increased neoangiogenesis and pericapillary edema compared to controls. Microvascular function improved following 3 months of TNFi in reference to basal flow as well as post-occlusive parameters. TNFi reduced pericapillary edema, while other parameters of capillary morphology remained unchanged. Microvascular dysfunction and capillary neovascular formation are associated with disease activity of AS. Anti-TNF-α treatment may restore microcirculation function and capillary edema but does not modify microvascular structural parameters.

Microvascular complications in diabetes patients with heart failure and reduced ejection fraction-insights from the Beta-blocker Evaluation of Survival Trial

AIMS

The role of microvascular complications in the risk conferred by diabetes in heart failure with reduced ejection fraction (HFrEF) is unknown.

METHODS AND RESULTS

We studied 2707 HFrEF patients in the Beta-blocker Evaluation of Survival Trial (BEST), stratified into three groups: no diabetes and diabetes without or with microvascular complications (neuropathy, nephropathy, or retinopathy). The risks of the composite of cardiovascular death or heart failure hospitalization, and all-cause death, were studied using Cox regression analyses adjusted for other prognostic variables. Overall, 964 (36%) patients had diabetes, of which 313 (32%) had microvascular complications. Patients with microvascular complications had more severe symptoms (New York Heart Association class IV 12% vs. 9% diabetes with no complications and 7% no diabetes), and worse quality of life (Minnesota Living with Heart Failure median score 60 vs. 54 and 51 points). In patients with diabetes and complications, the rate of the composite outcome was 50 per 100 person-years of follow-up (compared with 34 and 29 in those with diabetes and no microvascular complications and participants without diabetes, respectively). Compared to patients without diabetes, the adjusted hazard ratio (HR) for the composite outcome was 1.44 [95% confidence interval (CI) 1.22-1.70] and 1.18 (95% CI 1.03-1.35) for patients with diabetes with and without complications, respectively. The risk of all-cause mortality was similarly elevated: adjusted HR 1.42 (95% CI 1.16-1.74) and 1.20 (95% CI 1.01-1.42), respectively.

CONCLUSION

In HFrEF, diabetes with microvascular complications is associated with worse symptoms and outcomes than diabetes without microvascular complications. Prevention of microvascular complications has the potential to improve HFrEF outcomes.