Oxidant/Antioxidant Profile in the Thoracic Aneurysm of Patients with the Loeys-Dietz Syndrome

Abstract

Patients with the Loeys-Dietz syndrome (LDS) have mutations in the TGF-βR1, TGF-βR2, and SMAD3 genes. However, little is known about the redox homeostasis in the thoracic aortic aneurysms (TAA) they develop. Here, we evaluate the oxidant/antioxidant profile in the TAA tissue from LDS patients and compare it with that in nondamaged aortic tissue from control (C) subjects. We evaluate the enzymatic activities of glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD) isoforms, and thioredoxin reductase (TrxR). We also analyze some antioxidants from a nonenzymatic system such as selenium (Se), glutathione (GSH), and total antioxidant capacity (TAC). Oxidative stress markers such as lipid peroxidation and carbonylation, as well as xanthine oxidase (ORX) and nuclear factor erythroid 2-related factor 2 (Nrf2) expressions, were also evaluated. TAA from LDS patients showed a decrease in GSH, Se, TAC, GPx, GST, CAT, and TrxR. The SOD activity and ORX expressions were increased, but the Nrf2 expression was decreased. The results suggest that the redox homeostasis is altered in the TAA from LDS patients, favoring ROS overproduction that contributes to the decrease in GSH and TAC and leads to LPO and carbonylation. The decrease in Se and Nrf2 alters the activity and/or expression of some antioxidant enzymes, thus favoring a positive feedback oxidative background that contributes to the TAA formation.

Figure 1

(a) Average activity of the Mn-SOD and (b) average activity of the Cu/Zn-SOD in LDS patients (n = 10) and C subjects (n = 9). Values expressed represent the median and Min–Max range. The image of the center is a representative gel of the electrophoresis of the SOD isoforms. Abbreviations: LDS = Loeys-Dietz syndrome; C = control subjects.

Figure 2

(a) Average activity of CAT. The image below the graph is a representative native gel of the electrophoresis. (b) GPx activity, (c) GST activity, and (d) TrxR activity in LDS patients (n = 10) and C subjects (n = 9). Values are expressed as the median and Min–Max range. Abbreviations: LDS = Loeys-Dietz syndrome; C = control subjects.

Figure 3

Average activity of GR in LDS patients (n = 10) and C subjects (n = 9). Values are expressed as the median and Min–Max range. Abbreviations: LDS = Loeys-Dietz syndrome; C = control subjects.

Figure 4

(a) Representative histograms of eNOS/α-actin expression. (b) Cu/Zn-SOD/α-actin expression, (c) ORX/α-actin expression, and (d) Nrf2/α-actin expression in LDS patients (n = 10) vs. C subjects (n = 9). Values are expressed as the median and Min–Max range. Abbreviations: LDS = Loeys-Dietz syndrome; C = control subjects.

Figure 5

(a) Representative photomicrograph at 40x with hematoxylin-eosin staining of the aortic middle wall of a control subject. (A) Elastic fibers in deep pink. (B) Dark-colored fibrocyte nucleus. (b) Representative photomicrograph of the aortic middle wall of an LDS patient. (A) Cystic necrosis, with accumulation of amorphous material. (B) Elastic and collagen fibers in reddish and deep pink. (C) Blue-stained fibrocyte nucleus.

Figure 6

(a) Representative photomicrograph at 40x with Masson's trichrome staining of the aortic wall of a control subject. (A) Elastic fibers in red. (B) Collagen fibers in blue. (b) Representative photomicrograph of the aortic middle wall of an LDS patient. (A) Collagen fibers in deep blue color. (B) Cystic necrosis with the presence of amorphous material in faint blue color. (C) Elastic fibers in red color.

Figure 7

(a) Representative photomicrograph at 40x with Weigert's staining of the aortic wall of a control subject. (A) Elastic fibers in black color. (B) Collagen and elastic fibers in pink and light brown color. (b) Representative photomicrograph of the aortic wall of an LDS patient. (A) Elastic fibers. (B) Cystic necrosis. (C) Collagen fibers.