Colchicine Blocks Abdominal Aortic Aneurysm Development by Maintaining Vascular Smooth Muscle Cell Homeostasis

Development of non-surgical treatment of human abdominal aortic aneurysm (AAA) has clinical significance. Colchicine emerges as an effective therapeutic regimen in cardiovascular diseases. Yet, whether colchicine slows AAA growth remain controversy. Here, we demonstrated that daily intragastric administration of low-dose colchicine blocked AAA formation, prevented vascular smooth muscle cell (SMC) phenotype switching and apoptosis, and vascular inflammation in both peri-aortic CaPO4 injury and subcutaneous angiotensin-II infusion induced experimental AAA mice models. Mechanistically, colchicine increased global mRNA stability by inhibiting the METTL14/YTHDC1-mediated m6A modification, resulting in increased sclerostin (SOST) expression and consequent inactivation of the WNT/β-catenin signaling pathway in vascular SMCs from mouse AAA lesions and in cultured human aortic SMCs. Moreover, human and mouse AAA lesions all showed increased m6A methylation, decreased SOST expression, and skewed synthetic SMC de-differentiation phenotype, compared to those without AAA. This study uncovers a novel mechanism of colchicine in slowing AAA development by using the METTL14/SOST/WNT/β-catenin axis to control vascular SMC homeostasis in mouse aortic vessels and in human aortic SMCs. Therefore, use of colchicine may benefit AAA patients in clinical practice.


Figure S3 .
Figure S3.Colchicine does not affect body weight gain, systolic and diastolic blood pressure in Ang-II infusion mice.A) Body weight gain before and after AAA induction.B) Systolic blood pressure before and after AAA induction.C) Diastolic blood pressure before and after AAA induction.Data are mean ± SEM, n=11-15 per group.

Figure S4 .
Figure S4.Colchicine does not affect lipid metabolism, liver and kidney function in CaPO 4injure-and Ang-II infusion-induced AAA in mice.A) ELISA analysis of plasma total cholesterol (TCHO), triglyceride (TG), high-density lipoprotein cholesterol (HDL-c) and low-density lipoprotein cholesterol (LDL-c) levels in Ang-II infusion-induced AAA mice received saline or colchicine.B/C) ELISA analysis of plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT) and creatinine (Cr) levels in CaPO 4 injury-induced (B) or Ang-II infusion-induced (C) AAA mice received saline or colchicine.Data are mean ± SEM, n=11-15 per group.

Figure S6 .
Figure S6.Colchicine does not affect AAA lesion P-selectin and L-selection expression in CaPO 4 -injury-and Ang-II infusion-induced AAA lesions.A/B) RT-PCR analysis of AAA lesion P-selectin and L-selectin expression from CaPO 4 -injury-induced AAA (A) or Ang-II infusioninduced AAA (B) in mice treated with saline or colchicine.Data are mean ± SEM, n=11-15 mice per group.

Figure S14 .
Figure S14.Proposed mechanism of colchicine activity in preventing AAA development via maintaining vascular SMC homeostasis.

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Baseline characteristics of control subjects and AAA patients.Values are mean ± SEM or number (percentage).SBP, systolic blood pressure; DBP, diastolic blood pressure; PAD, peripheral arterial disease.Statistical analyses were performed using Student's t test (age, body mass index, SBP, DBP) or χ 2 test (sex, smoking and hypertension).