Management of cardiovascular disease by cerium oxide nanoparticles via alleviating oxidative stress and adipokine abnormalities

Abstract

The current study aimed to evaluate the role of cerium oxide nanoparticles (C-1), a potent antioxidant, in the medication of cardiovascular disease in obese animal model. C-1 was prepared using a modified sonication sol-gel method. Thirty-two adult male rats were equally divided into 4 groups (n=8/each). The first (control) and second (obese) groups are not treated while the obese rats in the third and fourth groups were given 15 and 30 mg/kg C-1(IP), respectively, for 8 weeks. Parameters of insulin resistance, adipocyte hormones, inflammatory markers, lipid profile, cardiac enzymes and cardiac iron content (C-Fe) were estimated. Moreover, histological study and immunohistochemical stain for inducible nitric oxide synthase (INOS) for cardiac and aortic tissues were performed. The XRD patterns of C-1 showed narrow symmetric diffraction peaks. The particle diameters were calculated from the TEM histogram (21.09 nm) and the Debye-Scherrer Method (20.74 nm) which were very similar. Using the most intense peak ( $28.{47}^{\circ }$ ), structural parameters were calculated including nano-crystallite size, Micro-strain, Lorentz factor, Thomson polarization parameter, and Lorentz polarization parameter. BET was used to calculate The total surface area (S $_T^{}$ ), and specific surface area (S $_{\mathrm{BET}}^{}$ ). The XPS survey spectrum of C-1 showed peaks for C-1s, O-1s and Ce-3d. The treatment of obese rats with C-1 led to a significant decrease in body weight, C-Fe , plasma leptin, tumor necrosis factor-alpha (TNF $\alpha$ ), interleukin-6 (IL6), C-reactive protein (CRP), resistin, cholesterol, triglycerides, low-density lipoprotein (LDL), Troponin, Creatinine Kinase-MB (CK-MB), lactate dehydrogenase (LDH), and malondialdehyde (MDA) in cardiac tissue or in plasma. Also, C-1 lowered plasma monocyte chemoattractant protein-1 (MCP-1), Epithelial Neutrophil-Activating Peptide (ENA-78), and insulin and glucose levels in obese rats. Furthermore, C-1 alleviated the increase of cardiac iNOS. Moreover, C-1 mitigated pathological changes of cardiac muscle and aorta observed in obese rats. On the other hand, C-1 enhanced adiponectin, cardiac glutathione (GSH) and superoxide dismutase (SOD) in obese rats. The effect of C-1 is dose-dependent ( 30 mg/kg of C-1 is more evident than 15 mg/kg). The modified synthesis method may lead to a smaller particle size than that reported in our previously reported work. The XRD patterns of C-1 indicate its cubic structure with space group F m -3 m (225) which was matched by code id 4343161 from COD. The Raman spectrum of C-1 indicates the absence of rearrangement oxygen atoms, the presence of oxygen in its fluorite lattice positions, and the oxygen vacancies in C-1 and the Ce vibration model (F_2g). The presence of ten peaks in the high-resolution Ce-3d XP spectrum indicates the existence of both Ce³⁺ and Ce⁴⁺. C-1 showed therapeutic efficacy in atherosclerosis and cardiac muscle abnormalities associated with obese rats, probably because of their antioxidant and anti-inflammatory properties, which lead to lowering oxidative stress.

Keywords: Adipokines; Aorta; Cardiac muscle; Cerium oxide nanoparticles; Insulin resistance; Obesity; Oxidative stress.

Figure 1

a: XPS spectra of C-1, b: (a) XRD diffractogram of C-1, (b) COD:1562989, (c) Expantion (20–40) of XRD diffractogram of C-1, (d) Expantion (20–40) of XRD diffractogram of (A-1), c: Raman spectrum of C-1, d: HRTEM image of C-1, e: TEM image of C-1, f: Particle diameters distributions, g: N$_2^{}$ sorption isotherms and corresponding pore size distributions of C-1.

Figure 2

Effect of C-1 on anthropometric measures and visceral adipose tissue weight of obese rats. Each bar represents the mean of 8 animals ± se. Statistical analysis was performed using one-way ANOVA followed by Tukey-Kramer multiple comparisons test. ($\star$ vs control group(group 1), @ vs obese group(group 2) ) at $p<$ 0.05.

Figure 3

Correlation between BMI and some oxidative parameters and cardiac biomarkers.

Figure 4

Effect of C-1 on plasma lipid profile and adipocyte hormones of obese rats. Each bar represents the mean of 8 animals ± se. Statistical analysis was performed using one-way ANOVA followed by Tukey-Kramer multiple comparisons test. ($\star$ vs control group(group 1), @ vs obese group(group 2) and # vs Nano cerium oxide (15 mg/kg, group 3)) at $p<0.05$.

Figure 5

Effect of C-1 on the iron content of cardiac and adipose tissue of obese rats.Each bar represents the mean of 8 animals ± se. Statistical analysis was performed using one-way ANOVA followed by Tukey-Kramer multiple comparisons test. ($\star$ vs control group(group 1), @ vs obese group(group 2) and # vs Nano cerium oxide (15 mg/kg, group 3)) at $p<0.05$.

Figure 6

Effect of C-1 on oxidative stress parameters in plasma and cardiac tissue of group 2. Each bar represents the mean of 8 animals ± se. Statistical analysis was performed using one-way ANOVA followed by Tukey-Kramer multiple comparisons test. ($\star$ vs control group(group 1), @ vs obese group(group 2) and # vs Nano cerium oxide (15 mg/kg, group 3)) at $p<0.05$.

Figure 7

Effect of C-1 on cardiac biomarker parameters in plasma of obese rats. Each bar represents the mean of 8 animals ± se. Statistical analysis was performed using one-way ANOVA followed by Tukey-Kramer multiple comparisons test. ($\star$ vs control group(group 1), @ vs obese group(group 2) and # vs Nano cerium oxide (15 mg/kg, group 3)) at $p<0.05$.

Figure 8

Effect of C-1 on insulin resistance parameters in plasma of obese rats.Each bar represents the mean of 8 animals ± se. Statistical analysis was performed using one-way ANOVA followed by Tukey-Kramer multiple comparisons test. ($\star$ vs control group(group 1), @ vs obese group(group 2) and # vs Nano cerium oxide (15 mg/kg, group 3)) at $p<0.05$.

Figure 9

Effect of C-1 on inflammatory adipokines level of obese rats.Each bar represents the mean of 8 animals ± se. Statistical analysis was performed using one-way ANOVA followed by Tukey-Kramer multiple comparisons test. ($\star$ vs control group(group 1), @ vs obese group(group 2) and # vs Nano cerium oxide (15 mg/kg, group 3)) at $p<0.05$.

Figure 10

I and II Photomicrographs of H&E-stained sections of aorta and cardiac muscles. I (a) Abdominal aorta of control rat showing normal tunica intima (arrow), media (TM) and adventitia (TA). (b–d) aorta of obese rat showing severe thickening of TM with swelling and degeneration of its muscle fibers (arrow), splitting of atherosclerotic plaque by inflammatory cells, foamy macrophages, and free RBCs, (square) with many lipophages (foam cells) (arrow) in the medial layer. (e and f) C-1 treated rats showing significant improvement in aortic histological alterations particularly at the group 4 group (f) with only few inflammatory cells infiltrating the TM with variable degree of adventitial edema. II (a) cardiac muscles of control rat showing normal cardiomyocytes (arrow). (b–d) cardiac muscles of obese rat showing (b) marked myofibers’ vacuolar degeneration (dotted arrow) and scattered hypereosinophilia (arrow), (c) apoptotic cells (arrow), and increased inter-muscular fat (dotted arrow) (d) coronary vessel showing medial thickening (dotted arrow) and vacuolization (arrow). (e and f) C-1 treated rats at low and group 4 respectively, showing significant restoration of cardiomyocytes integrity with only mild degeneration and scattered muscular eosinophilia.

Figure 11

Marked thickening of the both tunicae media and adventitial of aorta of obese rats and significant dose-related reduction in that thickening in C-1 treated rats’ groups. Each bar represents the mean ± SE of 8 rats. *vs normal control group(group 1), @vs obese group(group 2), #vs group 3 (15 mg/kg C-1) at $p<0.05$.

Figure 12

Photomicrographs of iNos immune-stained aortic and cardiac muscles of all groups. Obese rats (group 2) exhibited a significant increase in iNos expression. C-1 treated groups showing significant reduction in iNos expression. . Each bar represents the mean ± SE of 8 rats. *vs normal control group(group 1), @vs obese group(group 2), #vs C-1 ( 15 mg/kg) at $p<0.05$.