Exercise Mitigates Angiotensin II-Mediated Sympathetic Nerve-Macrophage Interaction in Aortic Adventitia Leading to Vascular Remodeling

Abstract

Large artery stiffness is a significant risk factor for cardiovascular diseases. Our previous study suggested that angiotensin II (Ang II) stimulates sympathetic innervation in aortic adventitia (AA) leading to elevated mean arterial blood pressure and increased arterial fibrosis, while voluntary wheel-running (VWR) reduces them. The aim of this study is to explore mechanism under Ang II-induced the aortic remodeling through sympathetic nerves and immune cell interactions using transcriptomics. We isolated cells in AA from Ang II (1.5 mg/kg/day) vs. Vehicle (Saline) infused C57BL/6 male mice (n=3 of each group), and we performed single-cell RNA-sequencing (scRNAseq). We profiled 23,419 cells after quality control and filtering steps and annotated 9 cell types in the AA employing a uniform manifold approximation and projection (UMAP) to visualize the remaining cells and the Leiden cluster algorithm. Firstly, we identified the Adrb2 gene for β2-adrenergic receptor (β2-ADR) was predominantly expressed in macrophages/monocytes as compared to other cell types, and significantly more expressed in macrophages vs. monocytes (adjusted p-value, <0.05). We validated the transcriptomic results using immunostaining for β2-ADR and synapsin with CD68 in AA. In addition, Ang II increased AA macrophage proportion which displays M1 phenotype (pro-inflammatory) (adjusted p-value, <0.05). These findings suggest that Ang II promotes M1 like macrophages which interact with sympathetic nerves in AA. Next, we performed Gene Ontology (GO) enrichment test in macrophages and fibroblasts. Ang II Macrophages were enriched in GO terms with inflammation and cytokines, and Ang II fibroblasts were enriched in GO terms involved in extracellular matrix deposition. The GO results indicate that Ang II induced inflammatory macrophages activates fibroblasts to accumulate ECM deposition in AA. Congruent with the scRNAseq results, we found that number of macrophages, ECM accumulation, and vascular stiffness measured by pulse wave velocity were increased with Ang II vs. Vehicle (all, p <0.05), whereas interestingly VWR ameliorated the Ang II effects. This study provides the evidence that Ang II promotes aortic remodeling by interaction between sympathetic nerves and macrophage which results in ECM deposition in AA using transcriptomics approach, while VWR countermeasure to these detrimental effects. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.