Ambient Ultra Fine Particle Impair Vascular Repair via Notch Signaling

Epidemiologic studies have consistently supported the link between air pollution exposure and cardiopulmonary diseases. Ultrafine particles (UFP, d < 0.1 μm), are the major component of particular matter (PM) in air pollution, harboring higher oxidant capacity, have pro‐inflammatory potential, and are more harmful to human health than the larger PM. UFP have been reported to induce vascular oxidative stress and endothelial cell dysfunction, leading to accelerated atherosclerosis. Here, we hypothesized that UFPs impair vascular repair by modulating Notch signaling. UFP exposure to human aortic endothelial cells (HAEC) impaired vascular repair as assessed by Matrigel tubular formation & Migration assay ( Fig 1). UFP significantly inhibited Notch signaling in HAEC reduced by Notch reporter activity and down‐regulation of Notch signaling‐related gene, including Notch ligands, JAG1 and JAG2, Notch receptor Notch1b, and the Notch target HEY2 ( Fig 2). In corollary, UFP and Adam 10 inhibitor reduced levels of Notch intracellular Domain (NICD). Over‐expression of NICD attenuated whereas Adam10 inhibitor (GI254023X) aggravated the effects of UFP. Next, we assessed the effect of UFP on vascular development and repair with zebrafish amputation model. Tg(fli‐1:EGFP) transgenic zebrafish tails were amputated at three days post fertilization (dpf). The fishes were then treated with or without 25 μg/mL UFP, or 5 μM of Adam10‐inhibitor (GI254023X) in E3 solution supplemented with 0.05% methylene blue. Both UFP and Adam 10 inhibitor impaired zebrafish tail regeneration resulting in disrupted intersegmental vessel (ISV) and incomplete loop formation at the tip of the tail ( Fig 3). NICD mRNA injection significantly activated Notch signaling and restored UFP impaired tail regeneration and ISV formation. Thus, we demonstrate Notch signaling underlying UFP‐mediated impairment of vascular regeneration with a translational implication in air pollution exposure and congenital cardiovascular diseases. Support or Funding Information National Institute of Health(NIH) UCLA Geffen School of Medicine UCLA Department of Bioengineering VA Greater Los Angeles Healthcare 1UFP inhibited HAEC migration and tube formation. (A)–(C) Cell migration assay at 8 hour post scratch. Bar graph shows the summarized migration assay data. (D)–(F) Tubular formation after 8hrs of treatment. Inhibition of Notch signaling prevents tube formation and branching (G)–(I) Magnified view at each point2UFP inhibited Notch signaling pathway. (A) Dose dependent inhibition of notch signaling (B) HAEC transfected with Notch reporter plasmid pJH26 were treated for 12 hrs with 25 μg/mL and 50 μg/mL of UFP. Data displays dose‐dependent reduction of Notch reporter activity (C) UFP down regulated expression of Notch signaling‐related genes (D) Decrease in level of NICD in the presence of UFP and Adam 10 inhibitor3Vascular developments and repair after UFP and GI254023X exposure. (A) Tg(fli‐1:EGFP) transgenic zebrafish model. (B) Amputated tails at 0 dpa. (C) Normal vessel regeneration in control fish 3 dpa (D) Aberrant tail regeneration treated with 25 μg/mL UFP (E) Incomplete tail regeneration with 5 μM GI254023X treatment (F) Normal vessel regeneration in NICD injected fish at 3 dpa (G) & (H) Rescues of vessel regeneration with NICD injection in UFP or GI254023X treated fish at 3 dpa