Background: Heart Failure with preserved Ejection Fraction (HFpEF) is an urgent medical challenge without proven therapy to date. A lack of understanding of the pathophysiology and heterogeneity of the HFpEF syndrome hinders translation into novel therapeutic approaches. Genome-wide gene expression analysis may provide insights into novel mechanisms, associated with disease states and may identify biomarkers for diagnosis, prognosis and therapeutic monitoring of disease activity.

The Leipzig Heart study is an observational cohort study in patients with suspected coronary artery disease (CAD), stable CAD and myocardial infarction. Patients were thoroughly characterized including echocardiography, assessment of biomarkers and gen-expression analysis in peripheral mononuclear cells (PBMC). While gene-expression profiles of multiple tissues are shared with PBMCs, these cells itself are integral to inflammatory processes thought to govern HFpEF development. 

We aimed to evaluate differential gene-expression profiles in PBMCs between HFpEF patients and patients without heart failure (controls).

Methods and Results:

Heart failure phenotypes were identified in the Leipzig Heart Study (n=6995) according the 2016 ESC definitions. After exclusion of patients with acute coronary syndromes 719 HFpEF patients and 1106 controls with interpretable data were recruited for subsequent analysis.

HFpEF patients were older, more frequently female, demonstrated higher NT-pro-BNP levels, inflammatory markers (CRP and IL-6), more CAD, hypertension and diabetes (p<0.05 for all). HFpEF patients presented with more dyspnea, less objective exertional capacity, higher mortality rates (11.4 vs. 3.4%, p<0.01 for all) as well as a higher sex and age adjusted mortality risk (HR 2.0 [1.3-3.0], p<0.01) during a median follow-up of 7.8 years.

PBMCs gene-expression was investigated using the HT-12v4 Expression BeadChip (Illumina, San Diego, CA, USA) and quantified 22,532 valid gene-expression probes, corresponding to 14,239 unique genes.

We identified 17 differentially expressed genes between HFpEF and controls at a false discovery rate of 5% using fully adjusted linear regression models. Top differentially expressed genes included genes encoding for glutathione peroxidase 3 (p<0.001), known to be involved in altered redox states in HFpEF, and potentially new targets like Ras-related GTP binding protein D (p<0.001), an mTOR pathway activator, and all three subunits of the Fc-γ-receptor (p<0.001). Differentially expressed genes were related to several canonical pathways relating to known pathomechanisms like cellular oxidant detoxification (p<0.01) and epithelial cell differentiation (p=0.02) and potentially new pathways like interferon-γ signaling (p<0.01).

Functional pathway analyses predicated increased downstream activation of mechanisms related to the maintenance of cell viability (z-score 1.3). Enriched upstream factors included the enzyme O-linked N-acetylglucosamine (p<0.001) and activated beta-estradiol (z-score 1.9).

Conclusions:

In this largest study to date differential gene-expression analysis in PBMCs confirmed several mechanisms known to be involved in the cellular HFpEF pathophysiology, validating our findings. Furthermore, we identified novel potential mechanisms and therapeutic targets that may contribute to the heterogeneity and pathophysiology of the HFpEF syndrome, which require further evaluation to develop novel therapeutic strategies.