Stimulator of Interferon Genes (STING) Regulates Endothelial Healing and Reendothelialization Following Angioplasty‐Mediated Vascular Injury

Abstract

Angioplasty and stent implantation are common clinical interventions to improve blood flow in Peripheral Artery Disease, which is rising in prevalence in America. However, these interventions result in vascular endothelial damage, leading to the activation of signaling pathways that can have a major effect on short‐ and long‐term vessel health. We hypothesized that endothelial cell‐intrinsic Stimulator of Interferon Genes (STING), a crucial regulator of immune responses triggered by pathogen or self‐derived DNA, regulates reendothelialization and healing in response to vascular injury. To study whether STING‐mediated reendothelialization was an endothelial cell specific effect, in vitro wound healing assay was performed on WT and STING deficient primary mouse heart endothelial cells (MHEC) using live imaging and quantification with Cytation and IncuCyte. We found that, while WT MHEC completely covered the scratch area within 24 hours of initial scratch, only 75.59% ± 5.8 of the initial wound was healed in STING deficient MHEC monolayers. Furthermore, our in vivo experiments using the wire injury‐mediated experimental model of angioplasty in mice followed by Evans Blue Dye staining to distinguish the areas with denuded endothelium, demonstrate a decrease in reendothelialization in injured carotid arteries in STING deficient mice as compared to WT mice five days post injury (43.57% ± 9.79 area reendothelialized vs 95.16% ± 2.77, respectively). Seven days post wire injury, WT carotid arteries were completely healed, in contrast to those of STING deficient mice that remained unhealed (67.74% ± 5.80 of reendothelialized vessel area). Additionally, multi‐parameter flow cytometry analysis of the enzymatically digested arteries from the seven days post wire injury group demonstrated an increase in myeloid cell infiltration in WT mice, which was not observed in either the injured STING deficient arteries or in the uninjured contralateral WT carotid arteries, indicating an early localized and differential immune response likely affecting long term vascular remodeling. Our results support that endothelial STING contributes to endothelial healing in vitro and in vivo, and that myeloid cell infiltration in the carotid arteries is required for reendothelialization and may be responsible for lack of healing in STING deficient mice. Ongoing experiments aim to definitively quantify temporal recruitment of immune cells over the course of reendothelialization and chronic vascular remodeling following wire injury and the mechanisms involved in short‐ and long‐term vascular health.Support or Funding InformationThis work was supported by the NIH‐RO1‐HL123658