Nuclear receptor co-repressor 1 regulates macrophage-driven inflammation in heart failure with preserved ejection fraction via the NLRP3-IL1b pathway: a translational study
E Gorica, L Di Venanzio, I Papadopolou, S A Mohammed, N Atzemian, H W Cheng, A Mengozzi, O Dzemali, B Ludewig, F Ruschitzka, N Hamdani, S Costantino, F PaneniAbstract
Background
Inflammatory response is a key player in heart failure with preserved ejection fraction (HFpEF) but the underlying mechanisms are poorly understood. Recent studies have shown that macrophages are active players in the myocardium and their activation may lead to pathological cardiac remodeling.
Purpose
to investigate the mechanisms underpinning macrophage inflammation in HFpEF.
Methods
FACS analysis, transcriptional profiling of immune cell populations by single nuclei RNA-seq (snRNAseq) in human and murine HFpEF hearts as well as in vitro experiments were employed. RAW-264.7 cells exposed to metabolic stress (palmitic acid, PA) and bone marrow-derived macrophages from healthy and HFpEF mice were used. The effects of macrophage secretome on cultured primary cardiomyocytes and endothelial cells were also investigated. Induction of HFpEF in mice was achieved through a validated mouse model combining metabolic (high-fat diet) and hemodynamic stress (L-NAME). Cardiac function was investigated by high resolution ultrasound imaging (Vevo3100) while Treadmill test was used to investigate exercise tolerance. Data obtained in mice were validated in left ventricular (LV) specimens from control donors and HFpEF patients. Based on scRNA-seq data showing Nuclear Receptor Co-repressor 1 (Ncor1) as a top-ranking gene in HFpEF macrophages, we generated myeloid cell-specific NCOR1 knockout (Ncor1-KO) transgenic mice to investigate the in vivo role of NCOR1 in HFpEF.
Results
snRNA-seq of human failing hearts showed an expansion of the macrophage population together with a marked upregulation of NCOR1 in the macrophage cluster. Experiments in LV specimens from HFpEF patients showed an increase in pro-inflammatory macrophage markers (M1) as compared to age-matched control donors. snRNA-seq of HFpEF vs control mouse hearts confirmed the expansion of the M1 macrophage population, the upregulation of inflammatory molecules (ICAM1, ICAM2, E-selectin) and fibrosis-related genes. Of interest, macrophage NCOR1 deletion in HFpEF mice prevented diastolic dysfunction - assessed by E/e’ ratio and isovolumic relaxation time (IVRT) - lung congestion and exercise intolerance. These findings were associated with reduced myocardial inflammation in Ncor1-KO mice as proved by sn-RNAseq. In vitro assays showed that metabolic stress by PA recapitulated NCOR1 upregulation and subsequent activation of the NLRP3-IL1b pathway; whereas NCOR1 depletion prevented macrophage inflammation. Finally, NCOR1 depletion in PA-treated macrophages prevented secretome alterations and preserved the function and viability of cardiomyocytes and endothelial cells, thus suggesting an active role of macrophage NCOR1 within the cardiac micro-environment.
Conclusion
Our findings shed light on a new molecular checkpoint of macrophage activation and set the stage for mechanism-based therapeutic strategies to prevent inflammation and cardiac dysfunction in HFpEF.Figure 2