Abstract Body (Do not enter title and authors here): Background: AZD0233 is an orally administered, selective allosteric modulator of the C-X3-C motif chemokine receptor 1 (CX3CR1). CX3CR1 is a transmembrane receptor expressed by subsets of leukocytes, including monocytes, T-cells and NK cells. Upon binding to its ligand CX3CL1, CX3CR1 facilitates immune cell adhesion and migration into inflamed tissue. Increased expression of CX3CR1 has been observed in the myocardial biopsies from dilated cardiomyopathy (DCM) patients.
Hypothesis: AZD0233 treatment will improve cardiac function by modulating cardiac inflammation in a preclinical DCM model.
Methods: We assessed the efficacy of oral administration of AZD0233 on cardiac function and immune cell modulations using the muscle LIM protein knock-out (MLP-KO) mouse model of DCM.
Results: After 4 weeks of AZD0233 treatment, a significant reduction in CD11b⁺ Ly6C^hi inflammatory monocytes was observed in the myocardial tissue by flow cytometry (0.90±0.10% at 100 mg/kg vs 1.31±0.19% in vehicle, p<0.05, n=9). Echocardiography indicated a dose-dependent improvement of systolic function as measured by an increase in left ventricular ejection fraction (percentage units 7.1 ± 1.5 higher at 100 mg/kg than vehicle treated p<0.001, n=11). After 8 weeks of treatment, histological analyses of myocardial sections showed a dose-dependent relative reduction in CX3CR1⁺ leukocytes by immunohistochemistry staining (48.6±21.3% at 100 mg/kg p<0.05 vs vehicle, n=11) and a decrease in myocardial fibrosis by Picrosirius Red staining (3.6±1.7% at 100 mg/kg vs 6.1±2.6% vehicle, p<0.01, n=11). Single nucleus RNA-seq analyses revealed a reduction in abundance of CD45⁺ leukocytes starting at 2 weeks and lasting up to 8 weeks during AZD0233 treatment. Subset-specific transcriptomic data indicated that macrophages differentially expressed genes involved in M2 polarization and inflammation resolution. Conversely, transcriptional changes in fibroblasts suggest reduced activation and fibrosis, along with increased cellular senescence.
Conclusions/Perspectives: AZD0233 treatment exhibited cardiac protective effects, improving cardiac function and promoting reverse remodeling in MLP-KO mice. Histological and transcriptomic analyses indicated AZD0233 reduced CD45⁺ immune cell populations, shifted macrophage polarization towards M2 phenotype and inflammation resolution.