Key result
Rugocrixan cuts macrophage recruitment ~27% and improves diastolic function in HFpEF mice.
Why the study?
The role of cardiac macrophages and their contribution to pathological remodeling in HFpEF is incompletely understood, and there is an urgent need for novel treatment options.
Does pharmacological inhibition of Cx3cr1 with rugocrixan improve diastolic dysfunction, macrophage recruitment, and cardiac fibrosis in a mouse model of HFpEF?
Does pharmacological inhibition of Cx3cr1 with rugocrixan improve diastolic dysfunction, macrophage recruitment, and cardiac fibrosis in a mouse model of HFpEF?
Blocking CX3CR1+ macrophage recruitment and signaling with rugocrixan reduces cardiac inflammation, fibrosis, and diastolic dysfunction in experimental HFpEF, identifying CX3CR1 as a promising therapeutic target.
CX3CR1+ macrophage targeting merits clinical investigation in HFpEF; hypothesis-generating from preclinical data and should not yet change practice.
Background and research question Heart failure with preserved ejection fraction (HFpEF) is characterized by impaired relaxation of the left ventricle during diastole (diastolic dysfunction) caused by cardiac hypertrophy, fibrosis, and inflammation. The role of cardiac macrophages and their contribution to pathological remodeling in HFpEF is incompletely understood. In addition, there is an urgent need for novel treatment options for HFpEF, and cardiac macrophages represent a promising target. Methods and results RNA-sequencing of human HFpEF endomyocardial biopsies revealed an upregulation of genes associated with myeloid cell recruitment, including CX3CR1, in patients with HFpEF. This upregulation was more pronounced in HFpEF than in heart failure with reduced ejection fraction (HFrEF), while genes linked to resident macrophages were downregulated. Correspondingly, we found an increased number of proinflammatory CX3CR1+ intermediate monocytes in the blood of patients with HFpEF. In a mouse model of HFpEF, using single-cell RNA sequencing (scRNA-seq) and flow-cytometry, we identified an increase in Cx3cr1+ myeloid cells with a proinflammatory and profibrotic phenotype (65,5 vs. 244,4 cells/mg cardiac tissue) . Respectively, protective yolk-sack-derived resident macrophages (TIM4+, MHC-II-, CCR2-) were reduced in HFpEF hearts (50,7 vs. 30,4 cells/mg cardiac tissue). Cx3cr1 was expressed in antigen-presenting and recruited macrophages, but not in yolk-sack-derived resident macrophages. Pharmacological inhibition of Cx3cr1 with Rugocrixan attenuated Cx3cr1+ macrophage recruitment (257,3 vs. 187,8 cells/mg cardiac tissue), diastolic dysfunction (E/E’: 39,3 vs. 32,5, left atrial size: 4,5 vs. 3,9 mm2), reduced fibrosis (1,6 vs. 1,2%), and reduced inflammatory and fibrotic cardiac gene expression (MHC-II, CCL11, Pdgfc, Ig1, Pgf) in HFpEF mice. Mechanistically, we found that CX3CR1+ macrophages activate fibroblasts via platelet-derived growth factors (PDGF-B and PDGF-C) by using in-silico ligand-receptor analysis of scRNA data and in vitro cellular communication assays. In addition, CX3CR1 blockade reduced inflammatory and hypertrophic gene expression in cardiac organoids under metabolic stress, suggesting a dual protective function of CX3CR1 inhibition: reducing macrophage recruitment and ameliorating inflammatory signaling in CX3CR1+ macrophages. Conclusion HFpEF is characterized by an expansion of CX3CR1+ macrophages and intermediate monocytes. Blocking Cx3cr1+ macrophage recruitment and signaling improves cardiac function in experimental HFpEF. Mechanistically, Cx3cr1 inhibition reduced cardiac macrophage recruitment, inflammation, and fibrosis in vivo.
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Leberzammer et al. (2026) studied Heart failure with preserved ejection fraction (HFpEF). Rugocrixan (pharmacological inhibition of Cx3cr1) vs. Untreated / vehicle control HFpEF mice was evaluated on Cx3cr1+ macrophage recruitment, diastolic dysfunction (E/E'), and cardiac fibrosis. Pharmacological Cx3cr1 inhibition with Rugocrixan reduced macrophage recruitment (187.8 vs 257.3 cells/mg), diastolic dysfunction (E/E' 32.5 vs 39.3), and fibrosis (1.2% vs 1.6%) in HFpEF mice.
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