Evidence from normal human arteries: IRF7 triggers atherosclerosis by enhancing vascular smooth muscle cells inflammation

Abstract Background Atherosclerosis is the leading cause of mortality worldwide. The pro-atherogenic factors embedded in the intrinsic cells of arteries in a physiological state remains problematic. Mouse-based research demonstrated that in normal arteries with different susceptibilities to atherosclerosis, the expression of transcription-related factors in vascular smooth muscle cells (vSMCs) exhibit significant variations. These transcription factors were shown to play a crucial role in the initiation of atherosclerotic lesions in subsequent studies. However, in human, the research paradigm that exploring early interventional targets for atherosclerosis from normal arteries remained lacking. Purpose Our objective is to recognize the risk factors that promote plaque formation by revealing single-cell gene expression patterns between different athero-susceptible arteries in human, with the aim of identifying potential targets for the early prevention of atherosclerosis. Methods 100 patients with triple coronary lesions were evaluated using doppler ultrasound to explore the peripheral arteries with different plaque susceptibilities. Single-cell RNA sequencing of athero-susceptible arteries (posterior tibial arteries) and athero-resistant arteries (radial arteries) were performed to investigate the cellular heterogeneity. A mouse line with vSMCs-specific deletion of Irf7 on an Ldlr-/- background was used to investigate its relationship to atherogenesis. And the potential role of IRF7 in transcriptional regulation in vSMCs inflammation and plaque formation was elucidated in vivo and in vitro. Results Doppler ultrasonography showed that the posterior tibial arteries have a higher susceptibility to atherosclerosis than the radial arteries, evidenced by a higher plaque burden with no significant difference in hemodynamic parameters. Single-cell sequencing from normal arteries revealed that, compared to radial arteries, a population of pro-inflammatory vSMCs (vSMC5) characterized by the high expression of CCL19 and CCL21 was prominent in posterior tibial arteries. Among the differentially expressed genes in vSMC5 cluster, IRF7 was identified as a key transcription factor regulating the expression of CCL19 and CCL21. In vitro experiments on cultured human VSMCs confirmed that IRF7 transcriptionally activates CCL19 and CCL21. Specific deletion of Irf7 in vSMCs attenuated arterial inflammation and alleviated the initiation of atherosclerosis. In addition, CT angiography and immunohistochemistry in APOE-/- canine models further validated that IRF7, CCL19, and CCL21 had a higher expression level in athero-susceptible hindlimbs arteries. Conclusions Our cross-species study demonstrates that IRF7 in vSMCs increases arterial inflammation and atherosclerotic susceptibility by transcriptionally activating CCL19 and CCL21. Inhibiting IRF7 in vSMCs represents a potential strategy for the early prevention of atherosclerosis.The research paradigm of human arteries