Endothelial and Smooth Muscle Cells from Abdominal Aortic Aneurysm Have Increased Oxidative Stress and Telomere Attrition

Abstract

Background Abdominal aortic aneurysm (AAA) is a complex multi-factorial disease with life-threatening complications. AAA is typically asymptomatic and its rupture is associated with high mortality rate. Both environmental and genetic risk factors are involved in AAA pathogenesis. Aim of this study was to investigate telomere length (TL) and oxidative DNA damage in paired blood lymphocytes, aortic endothelial cells (EC), vascular smooth muscle cells (VSMC), and epidermal cells from patients with AAA in comparison with matched controls.MethodsTL was assessed using a modification of quantitative (Q)-FISH in combination with immunofluorescence for CD31 or α-smooth muscle actin to detect EC and VSMC, respectively. Oxidative DNA damage was investigated by immunofluorescence staining for 7, 8-dihydro-8-oxo-2′-deoxyguanosine (8-oxo-dG).Results and ConclusionsTelomeres were found to be significantly shortened in EC, VSMC, keratinocytes and blood lymphocytes from AAA patients compared to matched controls. 8-oxo-dG immunoreactivity, indicative of oxidative DNA damage, was detected at higher levels in all of the above cell types from AAA patients compared to matched controls. Increased DNA double strand breaks were detected in AAA patients vs controls by nuclear staining for γ-H2AX histone. There was statistically significant inverse correlation between TL and accumulation of oxidative DNA damage in blood lymphocytes from AAA patients. This study shows for the first time that EC and VSMC from AAA have shortened telomeres and oxidative DNA damage. Similar findings were obtained with circulating lymphocytes and keratinocytes, indicating the systemic nature of the disease. Potential translational implications of these findings are discussed.

Progressive Development of Aberrant Smooth Muscle Cell Phenotype in Abdominal Aortic Aneurysm Disease

“…Our results show unequivocally that human AAA-SMC exhibit a greater extent of DNA damage than non-aneurysmal SMC, in agreement with a previous study that also examined γH2AX and 8-dihydro-8-oxo-2′-deoxyguanosine as a marker of oxidative DNA damage [26]. However, in that study AAA-SMC were explored in situ in tissue sections or isolated as primary cells by a cytospin method without culturing [26]. It is notable that in early-stage PCA-SMC the presence of multi-nucleation was high in both VEH- and CCE-SMC alike.…”

“…We examined multi-nucleation (a feature of senescent and damaged cells [33,34]), deformation of normal ovoid nuclear morphology (more common in aged and DNA damaged cells [35,13]), and the presence of γH2AX (an early event in double-stranded DNA damage [36]). Our results show unequivocally that human AAA-SMC exhibit a greater extent of DNA damage than non-aneurysmal SMC, in agreement with a previous study that also examined γH2AX and 8-dihydro-8-oxo-2′-deoxyguanosine as a marker of oxidative DNA damage [26]. However, in that study AAA-SMC were explored in situ in tissue sections or isolated as primary cells by a cytospin method without culturing [26].…”

“…These secreted factors can induce senescence in neighbouring cells via paracrine/autocrine mechanisms, a phenomenon known as a “bystander effect” [25]. AAA-SMC exhibit telomere attrition [26] and we previously demonstrated that aneurysmal SMC exhibit a greater degree of senescence, indicated by β-galactosidase staining [9]. We therefore examined the expression of sirtuins, longevity proteins whose expression is inversely correlated with cell age [27].…”

Smooth Muscle Cells Isolated from Thoracic Aortic Aneurysms Exhibit Increased Genomic Damage, but Similar Tendency for Apoptosis

“…It is really hard to extrapolate an answer based on our current data, yet, it could be speculated that at least some of the changes involving either down or upregulation of genes can be explained by gross chromosomal changes that can be caused by MN and/or BN. In accordance with our findings, previous findings have indicated elevated oxidative DNA damage in other cardiovascular diseases, such as in the vessel wall of atherosclerotic plaques (Martinet et al, 2002), as well as in the endothelial cells and SMCs from AAAs (Cafueri et al, 2012). Hence, elevated genomic damage can be a common denominator in cardiovascular diseases and ROS appears to be a strong candidate responsible of this damage.…”

Meglumine Antimoniate (Glucantime) Causes Oxidative Stress-Derived DNA Damage in BALB/c Mice Infected by Leishmania (Leishmania) infantum

“…Endo III recognizes oxidized pyrimidines, including thymine glycol and uracil glycol. Consequently, both enzymes have been used as biomarkers of DNA damage caused by oxidative stress (21)(22)(23)(24). Our results showed that enzymatic digestion further increased genomic lesions caused by meglumine antimoniate, suggesting that DNA damage was induced by the oxidation of the nitrogenous bases of DNA.…”