Single-Cell RNA Sequencing Reveals Metabolic Stress-Dependent Activation of Cardiac Macrophages in a Model of Dyslipidemia-Induced Diastolic Dysfunction.

BACKGROUND: Metabolic distress is often associated with heart failure with preserved ejection fraction (HFpEF) and represents a therapeutic challenge. Metabolism-induced systemic inflammation links comorbidities with HFpEF. How metabolic changes affect myocardial inflammation in the context of HFpEF is not known. METHODS: We found that ApoE knockout mice fed a Western diet recapitulate many features of HFpEF. Single-cell RNA sequencing was used for expression analysis of CD45+ cardiac cells to evaluate the involvement of inflammation in diastolic dysfunction. We focused bioinformatics analysis on macrophages, obtaining high-resolution identification of subsets of these cells in the heart, enabling us to study the outcomes of metabolic distress on the cardiac macrophage infiltrate and to identify a macrophage-to-cardiomyocyte regulatory axis. To test whether a clinically relevant sodium glucose cotransporter-2 inhibitor could ameliorate the cardiac immune infiltrate profile in our model, mice were randomized to receive the sodium glucose cotransporter-2 inhibitor dapagliflozin or vehicle for 8 weeks. RESULTS: ApoE knockout mice fed a Western diet presented with reduced diastolic function, reduced exercise tolerance, and increased pulmonary congestion associated with cardiac lipid overload and reduced polyunsaturated fatty acids. The main immune cell types infiltrating the heart included 4 subpopulations of resident and monocyte-derived macrophages, determining a proinflammatory profile exclusively in ApoE knockout- Western diet mice. Lipid overload had a direct effect on inflammatory gene activation in macrophages, mediated through endoplasmic reticulum stress pathways. Investigation of the macrophage-to-cardiomyocyte regulatory axis revealed the potential effects on cardiomyocytes of multiple inflammatory cytokines secreted by macrophages, affecting pathways such as hypertrophy, fibrosis, and autophagy. Finally, we describe an anti-inflammatory effect of sodium glucose cotransporter-2 inhibitor in this model. CONCLUSIONS: Using single-cell RNA sequencing , in a model of diastolic dysfunction driven by hyperlipidemia, we have determined the effects of metabolic distress on cardiac inflammatory cells, in particular on macrophages, and suggest sodium glucose cotransporter-2 inhibitors as potential therapeutic agents for the targeting of a specific phenotype of HFpEF.

Seminal Fluid Metabolomic Markers of Oligozoospermic Infertility in Humans.

Infertility affects 12-15% of couples worldwide, and male factors are the cause of nearly half of all cases. Studying seminal fluid composition could lead to additional diagnostic accuracy and a better understanding of the pathophysiology of male factor infertility. Metabolomics offers a new opportunity to evaluate biomarkers and better understand pathological mechanisms. The aim of the study was to identify new markers or therapeutic targets to improve outcomes in male factor or idiopathic infertility patients. Semen samples were obtained from 29 men with a normal spermogram test, and from 18 oligozoospermic men. Samples were processed and analyzed by Nuclear Magnetic Resonance spectroscopy and, subsequently, multivariate and univariate statistical analyses. Receiving Operator Curves (ROC) and Spearman correlations were also performed. An Orthogonal Partial Least Square Discriminant Analysis supervised multivariate model was devised to compare the groups. The levels of fructose, myo-inositol, aspartate and choline were altered. Moreover, Spearman Correlation associated fructose, aspartate and myo-inositol with the total amount of spermatozoa, total motile spermatozoa, % of immotility and % of "in situ" spermatozoic motility respectively. NMR-based metabolomics allowed the identification of a specific metabolic fingerprint of the seminal fluids of patients affected by oligozoospermia.