High Mobility Group Box 1 Inhibition By Antisense Oligonucleotide Attenuates Angiotensin Ii-induced Abdominal Aortic Aneurysm

Introduction: Vascular inflammation is a hallmark of abdominal aortic aneurysm (AAA). However, underlying mechanisms that initiate inflammatory pathways in the aorta are not clearly elucidated. Here, we explore the role of high-mobility group box 1 (HMGB1), a highly conserved nonhistone DNA-binding nuclear inflammatory molecule in AAA. Methods and Results: To determine the molecular signature and biological processes involved in AAA, we analyzed RNA sequencing (RNA-seq) data of patients with AAA (GSE57691) and mice with angiotensin-II (AngII) infusion (GSE17901) downloaded from the GEO database. Gene ontology analysis revealed that the major differences in enriched genes between the two groups involved inflammatory responses and cytokine-cytokine interaction. Both human and murine gene expression profiles indicated a marked upregulation of HMGB1 in the diseased abdominal aorta. AngII infusion also indicated a marked increase of HMGB1 in the abdominal aorta of male LDLr-/- mice after seven days. mRNA expression of genes related to the HMGB1 release mechanism was altered in diseased tissue relative to the control by RNA-seq. To explore the role of HMGB1 in AAA formation, we performed mouse in vivo studies with genetic manipulation in HMGB1, utilizing a novel antisense oligonucleotide (ASO) approach to inhibit HMGB1. Proprotein convertase subtilisin/kexin type 9 (PCSK9)-induced hypercholesterolemic male mice fed a Western diet were infused with AngII (1,000 ng/kg/min) for 4 weeks to induce AAA. Mice (N=15/group) were subcutaneously injected with phosphate-buffered saline (PBS) or HMGB1 ASO (50 mg/kg) at days 0 and 3 in the initial week and then once a week during the remainder of the study. There was no difference in blood pressure between the two groups in response to AngII. However, the aortic ex-vivo analysis indicated that the HMGB1 ASO profoundly attenuated AngII-induced AAA. Of note, ascending aorta area was also markedly reduced in the ASO group. Conclusion: Our data indicated the marked upregulation of HMGB1 in human and murine aneurysm. ASO-driven HMGB1 inhibition also resulted in profound attenuation of the AngII-induced AAA.