Mapping sympathetic neuroimmune interactions in atherosclerosis

Introduction Atherosclerosis is recognized as a complex disorder involving interactions among the vascular, the immune, and the nervous systems. Earlier, we had identified a neuroimmune cardiovascular interface in the adventitia of diseased arteries that initiates the formation of artery-brain circuits. Although it is known that the sympathetic nervous system regulates cardiovascular disease, how its structure and molecular changes emerge during atherosclerosis remain unclear. Purpose This project aims to characterize the cellular and molecular mechanisms by which the peripheral sympathetic nervous system controls atherosclerosis. Methods Integrated single-cell RNA sequencing, spatial transcriptomic sequencing, immunofluorescence analyses, 3-catecholamine ELISA, and histological analyses were performed on superior cervical ganglia, stellate ganglia, and celiac-superior mesenteric ganglia complexes using C57BL/6J and hyperlipidemic apolipoprotein E knockout mice. Results Extensive infiltration of myeloid cells, mast cells, and T cells was observed across sympathetic ganglia. A relative decrease in neuron density/mm2 and marked fibrosis were observed in aged mice during disease progression in sympathetic ganglia. Transcriptomes showed multiple alterations between neurons, immune cells, and fibroblasts during aging. Collagen type XV alpha-1 (Col15a1)-high fibroblasts were prevalent in sympathetic ganglia, with a notable decrease in matrix metalloproteinase-2 expression and an increase in its inhibitor, tissue inhibitor of metalloproteinase-3. Moreover, Col15a1high fibroblasts adopted a complement-associated phenotype in aged Apoe-/- ganglia, reflecting an altered functional state. Notably, the proportion of Cd209high resident macrophages was four-fold higher in aged Apoe-/- mice than in aged Wt mice, suggesting a pathological expansion in response to the synergistic effects of aging and atherosclerosis. The cluster of Sall1 (spalt-like transcription factor 1)-high microglia-like macrophages was found in sympathetic ganglia. Functional enrichment analysis indicated that Sall1high macrophages may orchestrate leukocyte dynamics and cellular crosstalk to maintain the neuro-inflammatory equilibrium. Transcript profiling showed noradrenergic neurons reprogrammed from low tyrosine hydroxylase and neuropeptide Y to an activated state, indicating heightened catecholamine and neuropeptide signaling, reflecting a pathological response to systemic stress in sympathetic ganglia during atherosclerosis. Conclusions Our findings demonstrate that the atherosclerosis progression parallels significant concurrent remodeling within the peripheral sympathetic nervous system during aging. The sympathetic ganglia show hyperactivation, fibrosis, and immune cell infiltration. These results define new aspects of the peripheral sympathetic nervous system-atherosclerosis axis and may suggest a novel therapeutic approach for advanced cardiovascular disease.