Imaging Mass Spectrometry Reveals a Unique Distribution of Triglycerides in the Abdominal Aortic Aneurysmal Wall

Abstract

The pathophysiology underlying abdominal aortic aneurysms (AAAs) remains unknown. In this study, we applied imaging mass spectrometry (IMS) to analyze the pathophysiology of the aneurysmal wall. Comparisons were performed between the tissue samples from the neck and the sac of the AAA, at a single time point, in 30 patients who underwent elective surgery of their AAAs. The localization of each lipid molecule in the aortic wall was assessed by IMS. Histopathological examination and IMS revealed a characteristic distribution of triglycerides (TGs) specifically in the aneurismal adventitia of the sac. This characteristic TG distribution was derived from an ectopic appearance of adipocytes in the adventitia. Furthermore, ectopic adipocyte accumulation in the aortic wall leads to the loss of the collagen fiber network subsequent to the wall rupture. The underlying mechanism of adipocyte accumulation involves the presence of adipose-derived stem cells (ADSCs) in the aneurismal adventitia and the expression of peroxisome proliferator-activated receptor gamma 2, a master regulator of adipocyte differentiation by some ADSCs. This study reveals new, previously overlooked aspects of AAA pathology.

Lysophosphatidylcholine Acyltransferase-3 Expression Is Associated with Atherosclerosis Progression

“…Here, we observed increased LPC levels in human atherosclerotic tissues undergoing chronic inflammation (Fig. 2), indicating that our results corresponded with previous reports [18,19]. Therefore, LPC accumulation associated with inflammation should be considered as one of the mechanisms involved in the occurrence of atherosclerosis.…”

Pathological Analysis of the Ruptured Vascular Wall of Hypoperfusion-induced Abdominal Aortic Aneurysm Animal Model

“…7 . The abnormal appearance of adipocytes was predominantly observed in the adventitia in humans 9 , which suggests that the abnormal appearance of adipocytes in the vascular wall during AAA is associated with AAA rupture in humans, as well as in animal models. Appropriate control of adipocytes in the vascular wall may be an important strategy to prevent AAA rupture.…”

“…Histological analysis of the AAA-ruptured vascular walls in the animal model also demonstrated that the abnormal appearance of adipocytes in the vascular wall is associated with AAA rupture 8 . The abnormal appearance of adipocytes was observed and the number of adipocytes in the vascular wall correlated with AAA diameter in humans 8,9 .…”

Higher Mass Accuracy MALDI‐TOF/TOF Lipid Imaging of Human Brain Tissue in Alzheimer's Disease

“…It describes a flexible method that can be easily modified by other research teams to suit their needs with no individual step requiring specialized equipment or instrumentation, thereby keeping costs to a minimum. Lipid-rich tissues such as the brain are particularly amenable to MALDI-IMS, but it is also amenable in organs where there is a pathological buildup of lipid such as atherosclerosis (Martin-Lorenzo, Alvarez-Llamas, McDonnell, & Vivanco, 2016), aneurysms (Tanaka et al, 2015), colon cancer (Hiraide et al, 2016), and nonalcoholic fatty liver disease (Alamri et al, 2018).…”