Analysis of host Toll-like receptor 3 and RIG-I-like receptor gene expression in patients with abdominal aortic aneurysm

Objective: Abdominal aortic aneurysm (AAA) is a vascular disease relatively common in the elderly population. Although some events that contribute to the development and progression of AAA are known, there are limited data examining the association of Toll-like receptor 3 (TLR3) and RIG-I-like receptor expression with the pathogenesis of AAAs. In this study, we investigated the gene and protein expression of TLR3 and RIG-I-like receptors (RIG-I and MDA5) in aortic wall and blood of AAA patients and examined the relationship between their expression and immune response. Methods: Total RNA was extracted from aortic wall tissues and blood samples collected from 20 patients with AAA and blood samples of 17 healthy volunteers without aortic aneurysm. To evaluate the DDX58 (RIG-I), IFIH1 (MDA5), and TLR3 gene expression level, quantitative real-time polymerase chain reaction was used. Extracellular cytokine and pattern recognition receptor levels were quantified by enzyme-linked immunosorbent assays. Results: TLR3, RIG-I, and MDA5 were constitutively expressed in both aortic tissues and blood samples from AAA patients and healthy volunteers. In patients with AAA, higher TLR3 expression in aortic tissues than in blood was found (P=.004). The DDX58 messenger RNA expression was higher in blood of patients with AAA compared with healthy subjects (P=.021). A significantly higher level of plasma interleukin 4 was noticed in patients with AAA than in healthy individuals (P=.008). Conclusions: This study suggests that RIG-I and TLR3 seem to be important factors in the pathogenesis of AAA. (J Vasc Surg 2018;68:39S-47S.) Clinical Relevance: Abdominal aortic aneurysm is a vascular disease relatively common in the elderly population. This study shows that Toll-like receptor 3 and RIG-I-like receptors may contribute to the development and progression of abdominal aortic aneurysm.