Abstract 256: Decreased Serum MiR-155 Expression is Associated with Increased Tumor Necrosis Factor-Alpha Levels in Patients with Abdominal Aortic Aneurysm

Abstract

Introduction: The inflammatory response plays a crucial role in abdominal aortic aneurysm (AAA) pathogenesis and expansion. The cytokine tumor necrosis factor-alpha (TNF-α) and MicroRNA-155 (miR-155) are implicated in inflammatory diseases. Previous studies have found miR-155 regulates TNF-α expression in cardiovascular disease. However, the relationship between TNF-α expression and miR-155 in AAA disease is not fully understood. This study examines the relationship between serum TNF-α levels and miR-155 expression in AAA patients. Methods: MicroRNA’s were isolated from patient serum and quantified using Agilent BioAnalyzer 2100. MiR-155 levels were assessed using qPCR with Exiqon LNA primers and normalized using the 2-ΔΔCT method. Media was collected from the co-culture of control or AAA monocytes with endothelial cells. The supernatant was analyzed for the presence of TNF-α via Luminex ® 200 TM analyzer. AAA is defined as ≥3.0 cm in maximum aortic diameter and measurement was obtained from abdominal ultrasound. Student’s t-test was used to compare AAA and control groups for statistical analysis. Results: Average aortic diameter for AAA group was 5.1±0.7 cm and 2.4±0.4 cm for controls. Q-PCR results showed miR-155 was significantly down-regulated in serum (p=0.03) in AAA subjects (n=5) versus non-AAA controls (n=4) (Figure 1A). Serum TNF-α levels from Luminex assays trended towards greater levels in AAA patients (n=4) vs. controls (n=3) (920.1±591.1 vs. 294.8±102.2 pg/mL, p=0.14) (Figure 1B). Conclusion: Patients with AAA may have more unregulated TNF-α activity due to decreased miR-155 expression compared to controls. Serum miR-155 may serve as a potential biomarker for patients at risk for aortic expansion leading to AAA disease.