β-Carotene Attenuates Angiotensin II-Induced Aortic Aneurysm by Alleviating Macrophage Recruitment in Apoe(-/-) Mice

Bridging the gap: Navigating the impact of dietary supplements on abdominal aortic aneurysm progression- A systematic review

BACKGROUND

Vitamins D, E, A, B, C, and Omega-3 play crucial roles in modulating inflammatory and oxidative stress pathways, both implicated in abdominal aortic aneurysm (AAA) development. Recent research has explored the potential impact of dietary supplements on AAA progression. The systematic review aims to assess interventional studies investigating the effects of various dietary supplements on the development and severity of abdominal aortic aneurysms.

METHOD

A systematic search using relevant keywords related to abdominal aortic aneurysm and dietary supplements was conducted across four databases (PubMed, Embase, Scopus, and Web of Science). Quality assessment for animal studies employed SYRCLE and the Cochrane Collaboration Risk of Bias Tool for randomized control trials. The study protocol is registered in PROSPERO under the registry code CRD42023455958.

RESULTS

Supplementation with Omega-3, Vitamins A, C, D, E, and the Vitamin B family exhibited positive effects in AAA progression. These supplements contributed to a reduction in AAA diameter, elastin degradation, inflammatory responses, and reactive oxygen species. Additional supplements such as Zinc, methionine, and phytoestrogen also played roles in mitigating AAA progression.

CONCLUSION

The findings of this study underscore the potential role of dietary supplements in the progression of AAA. Predominantly based on animal studies, the results indicate that these supplements can limit AAA progression, primarily evidenced by their ability to mitigate inflammatory processes and oxidative stress pathways.

Systematic Review and Meta-Analysis of Interventions to Slow Progression of Abdominal Aortic Aneurysm in Mouse Models

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All-trans retinoic acid attenuates the progression of Ang II-induced abdominal aortic aneurysms in ApoE-/-mice

Background

To determine whether all-trans retinoic acid (ATRA) can influence the development of Angiotensin II (Ang II) induced experimental abdominal aortic aneurysms (AAAs).

Methods

Apolipoprotein E knock-out (ApoE^−/−) mice were randomly assigned to 4 groups. Mice in the AAA and ATRA groups underwent continuous subcutaneous Ang II infusion for 28 days to induce AAA, while the Sham and Control groups were infused with saline. Systolic blood pressure was measured by the tail-cuff technique. The Control and ATRA groups received ATRA treatment. Aortic tissue samples were obtained at 28 days after surgery and evaluated by aortic diameter measurement, Western blotting, immunohistochemistry, and hematoxylin-eosin (H&E) and Verhoeff-Van Gieson (EVG) staining.

Results

The abdominal aortic diameter was significantly reduced in the ATRA group compared with the AAA group (3 of 12 (25%) vs 9 of 12 (75%), P < 0.05), and the ATRA group exhibited reduced blood pressure on days 7, 14, and 28. Low expression of angiotensin II receptor type 1 (AT1), matrix metalloproteinase 2 (MMP2), and matrix metalloproteinase 9 (MMP9) and EVG staining revealed a significant reduction in the disruption of elastic fibers in the abdominal aortic tissue of the ATRA group compared to the AAA group. Western blot analysis indicated that protein levels of retinoic acid receptor α (RARα), MMP2, MMP9, and AT1 were dramatically affected by ATRA treatment.

Conclusions

In conclusion, ATRA attenuates the progression of Ang II-induced AAAs, possibly by downregulating MMP2, MMP9, and AT-1 expression.

Ginkgo biloba extracts prevent aortic rupture in angiotensin II-infused hypercholesterolemic mice

Abdominal aortic aneurysms (AAAs) are a chronic vascular disease characterized by pathological luminal dilation. Aortic rupture is the fatal consequence of AAAs. Ginkgo biloba extracts (GBEs), a natural herb extract widely used as food supplements, drugs, and cosmetics, has been reported to suppress development of calcium chloride-induced AAAs in mice. Calcium chloride-induced AAAs do not rupture, while angiotensin II (AngII)-induced AAAs in mice have high rate of aortic rupture, implicating potentially different mechanisms from calcium chloride-induced AAAs. This study aimed to determine whether GBE would improve aortic dilation and rupture rate of AngII-induced AAAs. Male apolipoprotein E (apoE) -/- mice were infused with AngII and administered either GBE or its major active ingredients, flavonoids and ginkgolides, individually or in combination. To determine the effects of GBE in mice with established AAAs, male apoE-/- mice were firstly infused with AngII for 28 days to develop AAAs, and then administered either GBE or vehicle in mice with established AAAs, which were continuously infused with AngII for another 56 days. GBE, but not the two major active components separately or synergistically, prevented aortic rupture, but not aortic dilation. The protection of GBE from aortic rupture was independent of systolic blood pressure, lipid, and inflammation. GBE also did not attenuate either aortic rupture or progressive aortic dilation in mice with established AAAs. GBE did not reduce the atherosclerotic lesion areas, either. In conclusion, GBE prevents aortic rupture in AngII-infused hypercholesterolemic mice, but only in the early phase of the disease development.

Potential Medication Treatment According to Pathological Mechanisms in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a vascular disease with high mortality. Because of the lack of effective medications to stop or reverse the progression of AAA, surgical operation has become the most predominant recommendation of treatment for patients. There are many potential mechanisms, including inflammation, smooth muscle cell apoptosis, extracellular matrix degradation, oxidative stress, and so on, involving in AAA pathogenesis. According to those mechanisms, some potential therapeutic drugs have been proposed and tested in animal models and even in clinical trials. This review focuses on recent advances in both pathogenic mechanisms and potential pharmacologic therapies of AAA.

Regulation of Kruppel-like factor 2 (KLF2) in the pathogenesis of intracranial aneurysm induced by hemodynamics

Kruppel-like factor 2 (KLF2) has been found to regulate the reconstruction of vascular wall tissue and participate in the pathogenic mechanism of intracranial aneurysms. However, there is a paucity of research in this area. The present study aimed to investigate the regulatory effect of KLF2 on intracranial aneurysm (IA) and explore novel therapeutic strategies for treating IA. Experimental animal models were established with SPF New Zealand rabbits by bilateral carotid artery ligation (BCAL). Morphology of basilar artery bifurcation was detected using HE, EVG, Masson and immunohistochemical (IHC) staining. Vascular smooth muscle cells were harvested from basilar artery and cultured to establish KLF2 up-regulated and down-regulated cell models. The mRNA expression of KLF2, eNOS, ICAM-1 and MMP-9 were detected using real-time quantitate PCR (RT-qPCR). Protein expression of KLF2 and MAPKs pathway were measured using western blot. IA models were successfully established by bilateral carotid artery ligation. KLF2 expression was inconsistent with the variation of hemodynamics. In the KLF2 overexpression group, the mRNA expression of eNOS was increased, while that of ICAM-1 and MMP-9 was decreased. When KLF2 was up-regulated, the phosphorylation activity of p38 pathway was increased. In conclusion, results reveal that KLF2 is up-regulated in the vascular wall of basilar artery, and its overexpression regulates the pathogenesis of IA, which may be a self-protection mechanism of the arterial wall, providing a novel insight for therapy of IA.

9-cis β-Carotene Increased Cholesterol Efflux to HDL in Macrophages

Cholesterol efflux from macrophages is a key process in reverse cholesterol transport and, therefore, might inhibit atherogenesis. 9-cis-β-carotene (9-cis-βc) is a precursor for 9-cis-retinoic-acid (9-cis-RA), which regulates macrophage cholesterol efflux. Our objective was to assess whether 9-cis-βc increases macrophage cholesterol efflux and induces the expression of cholesterol transporters. Enrichment of a mouse diet with βc from the alga Dunaliella led to βc accumulation in peritoneal macrophages. 9-cis-βc increased the mRNA levels of CYP26B1, an enzyme that regulates RA cellular levels, indicating the formation of RA from βc in RAW264.7 macrophages. Furthermore, 9-cis-βc, as well as all-trans-βc, significantly increased cholesterol efflux to high-density lipoprotein (HDL) by 50% in RAW264.7 macrophages. Likewise, food fortification with 9-cis-βc augmented cholesterol efflux from macrophages ex vivo. 9-cis-βc increased both the mRNA and protein levels of ABCA1 and apolipoprotein E (APOE) and the mRNA level of ABCG1. Our study shows, for the first time, that 9-cis-βc from the diet accumulates in peritoneal macrophages and increases cholesterol efflux to HDL. These effects might be ascribed to transcriptional induction of ABCA1, ABCG1, and APOE. These results highlight the beneficial effect of βc in inhibition of atherosclerosis by improving cholesterol efflux from macrophages.

Oxidative stress and abdominal aortic aneurysm: potential treatment targets

Abdominal aortic aneurysm (AAA) is a significant cause of mortality in older adults. A key mechanism implicated in AAA pathogenesis is inflammation and the associated production of reactive oxygen species (ROS) and oxidative stress. These have been suggested to promote degradation of the extracellular matrix (ECM) and vascular smooth muscle apoptosis. Experimental and human association studies suggest that ROS can be favourably modified to limit AAA formation and progression. In the present review, we discuss mechanisms potentially linking ROS to AAA pathogenesis and highlight potential treatment strategies targeting ROS. Currently, none of these strategies has been shown to be effective in clinical practice.

Mitochondria-targeted esculetin alleviates mitochondrial dysfunction by AMPK-mediated nitric oxide and SIRT3 regulation in endothelial cells: potential implications in atherosclerosis

Mitochondria-targeted compounds are emerging as a new class of drugs that can potentially alter the pathophysiology of those diseases where mitochondrial dysfunction plays a critical role. We have synthesized a novel mitochondria-targeted esculetin (Mito-Esc) with an aim to investigate its effect during oxidative stress-induced endothelial cell death and angiotensin (Ang)-II-induced atherosclerosis in ApoE^−/− mice. Mito-Esc but not natural esculetin treatment significantly inhibited H2O2- and Ang-II-induced cell death in human aortic endothelial cells by enhancing NO production via AMPK-mediated eNOS phosphorylation. While L-NAME (NOS inhibitor) significantly abrogated Mito-Esc-mediated protective effects, Compound c (inhibitor of AMPK) significantly decreased Mito-Esc-mediated increase in NO production. Notably, Mito-Esc promoted mitochondrial biogenesis by enhancing SIRT3 expression through AMPK activation; and restored H2O2-induced inhibition of mitochondrial respiration. siSIRT3 treatment not only completely reversed Mito-Esc-mediated mitochondrial biogenetic marker expressions but also caused endothelial cell death. Furthermore, Mito-Esc administration to ApoE^−/− mice greatly alleviated Ang-II-induced atheromatous plaque formation, monocyte infiltration and serum pro-inflammatory cytokines levels. We conclude that Mito-Esc is preferentially taken up by the mitochondria and preserves endothelial cell survival during oxidative stress by modulating NO generation via AMPK. Also, Mito-Esc-induced SIRT3 plays a pivotal role in mediating mitochondrial biogenesis and perhaps contributes to its anti-atherogenic effects.

Angiotensin II is related to the acute aortic dissection complicated with lung injury through mediating the release of MMP9 from macrophages

BACKGROUND

Acute aortic dissection (AAD) patients usually show concurrent lung injury mainly featured by hyoxemia. To date, no effective treatment method has been established for the AAD complicated with acute lung injury (ALI). Matrix metalloproteinases (MMPs), especially MMP2 and MMP9, have been considered to be closely related to the onset of aortic disease including AAD. To investigate the roles of MMP in the pathogenesis of AAD complicated with ALI, we determined the expression of MMP2 and MMP9 in serum and lung tissues of AAD patients. In addition, a new rat model of AAD complicated with ALI was established to investigate the pathogenesis of such complicated conditions.

METHODS AND RESULTS

Angiotensin II (Ang II) and MMP9 were up-regulated in the AAD complicated with ALI patients compared to those of the AAD without ALI patients, normal individuals and the patients with non-ruptured aneurysm. Besides, massive macrophages with MMP9 expression was noticed in the lung tissues in the AAD complicated with ALI patients. On this basis, AAD complicated with ALI rat model was established based on BAPN feeding and infusion of Ang II. Obvious lung injury was observed in the BAPN+Ang II group compared to that of the BAPN group, together with macrophage accumulation in lung tissues, as well as over-expression of MMP9 in lung tissues. After interference of MMP antagonist, a large number of macrophages were still accumulated in the lung tissues, but the lung injury was obviously attenuated. After the interference of AT1 receptor, the number of macrophages in the lung tissues was obviously decreased and the lung injury was obviously relieved.

CONCLUSIONS

Ang II is closely related to the lung injury at the early stage of AAD through mediating the release of MMP9 in the macrophages in the lung tissues.

Attrition of Hepatic Damage Inflicted by Angiotensin II with α-Tocopherol and β-Carotene in Experimental Apolipoprotein E Knock-out Mice

Angiotensin II is one of the key regulatory peptides implicated in the pathogenesis of liver disease. The mechanisms underlying the salubrious role of α-tocopherol and β-carotene on liver pathology have not been comprehensively assessed. Here, we investigated the mechanisms underlying the role of Angiotensin II on hepatic damage and if α-tocopherol and β-carotene supplementation attenuates hepatic damage. Hepatic damage was induced in Apoe(-/-)mice by infusion of Angiotensin II followed by oral administration with α-tocopherol and β-carotene-enriched diet for 60 days. Investigations showed fibrosis, kupffer cell hyperplasia, hepatocyte degeneration and hepatic cell apoptosis; sinusoidal dilatation along with haemorrhages; evidence of fluid accumulation; increased ROS level and increased AST and ALT activities. In addition, tPA and uPA were down-regulated due to 42-fold up-regulation of PAI-1. MMP-2, MMP-9, MMP-12, and M-CSF were down-regulated in Angiotensin II-treated animals. Notably, α-tocopherol and β-carotene treatment controlled ROS, fibrosis, hepatocyte degeneration, kupffer cell hyperplasia, hepatocyte apoptosis, sinusoidal dilatation and fluid accumulation in the liver sinusoids, and liver enzyme levels. In addition, PAI-1, tPA and uPA expressions were markedly controlled by β-carotene treatment. Thus, Angiotensin II markedly influenced hepatic damage possibly by restraining fibrinolytic system. We concluded that α-tocopherol and β-carotene treatment has salubrious role in repairing hepatic pathology.

Metformin inhibits monocyte-to-macrophage differentiation via AMPK-mediated inhibition of STAT3 activation: potential role in atherosclerosis

Monocyte-to-macrophage differentiation is a critical event that accentuates atherosclerosis by promoting an inflammatory environment within the vessel wall. In this study, we investigated the molecular mechanisms responsible for monocyte-to-macrophage differentiation and, subsequently, the effect of metformin in regressing angiotensin II (Ang-II)-mediated atheromatous plaque formation in ApoE(-/-) mice. AMPK activity was dose and time dependently downregulated during phorbol myristate acetate (PMA)-induced monocyte-to-macrophage differentiation, which was accompanied by an upregulation of proinflammatory cytokine production. Of note, AMPK activators metformin and AICAR significantly attenuated PMA-induced monocyte-to-macrophage differentiation and proinflammatory cytokine production. However, inhibition of AMPK activity alone by compound C was ineffective in promoting monocyte-to-macrophage differentiation in the absence of PMA. On the other hand, inhibition of c-Jun N-terminal kinase activity inhibited PMA-induced inflammation but not differentiation, suggesting that inflammation and differentiation are independent events. In contrast, inhibition of STAT3 activity inhibited both inflammation and monocyte-to-macrophage differentiation. By decreasing STAT3 phosphorylation, metformin and AICAR through increased AMPK activation caused inhibition of monocyte-to-macrophage differentiation. Metformin attenuated Ang-II-induced atheromatous plaque formation and aortic aneurysm in ApoE(-/-) mice partly by reducing monocyte infiltration. We conclude that the AMPK-STAT3 axis plays a pivotal role in regulating monocyte-to-macrophage differentiation and that by decreasing STAT3 phosphorylation through increased AMPK activity, AMPK activators inhibit monocyte-to-macrophage differentiation.

High-fat diet- and angiotensin II-induced aneurysm concurrently elicits splenic hypertrophy

BACKGROUND

Angiotensin II (Ang II) and high-fat diet are implicated in causing pathological changes in the vascular endothelium, brain, kidney and liver. The association of aneurysm leading to histopathological changes in the splenic compartment remains elusive. Further, the salubrious credentials of antioxidants, especially α-tocopherol and β-carotene in the resolution of splenic pathology have not been investigated.

METHODS

Four-month-old Apoe(-/-) mice were used in the induction of aneurysm by infusing Ang II, and subsequently were orally administered with α-tocopherol and β-carotene-enriched diet for 60 days.

RESULTS

We observed splenomegaly in Ang II-infused aneurysm and high-fat diet-supplemented mice as compared to normal mice. These observations were further confirmed through histopathological investigations, demonstrating splenic follicular hypertrophy. We observed a remarkable decrease in the size of spleen in α-tocopherol and β-carotene-treated Apoe(-/-) mice as compared with Ang II-treated animals. Furthermore, no marked changes in the histopathological splenic sections were seen in the β-carotene-treated group. However, hyperplasia and proliferation of immature lymphocytes in the follicles were observed in the α-tocopherol-treated animals. We found that CD4+ T-cell levels were increased in the high-fat diet group relative to the control group and were decreased in the β-carotene-treated animals.

CONCLUSIONS

Our study provides evidence that Ang II infusion and high-fat supplementation induces abdominal aortic aneurysm that has pathological implications to the spleen. The use of β-carotene but not α-tocopherol as an antioxidant markedly ameliorates the pathological changes in spleen.

Protective effect of beta-carotene against titanium dioxide nanoparticles induced apoptosis in mouse testicular tissue

In this study, the effects of beta-carotene (BC) on testicular germ cell apoptosis arising from titanium dioxide nanoparticles (NTiO2 ) have been evaluated. In NTiO2 -treated mice, expression of apoptotic related genes including Bid, FasL, caspase-3 and p38MAPK was significantly increased. Measurement apoptosis using TUNEL method showed significant increase in apoptotic index of germ cells in NTiO2 -treated mice (P < 0.05). TUNEL assessments showed that the increase of apoptotic index of testicular germ cells in NTiO2 -treated mice was reversed by BC. Beta-carotene pre-treatment could also effectively attenuate the expression of apoptotic related genes. The application of BC may serve as a beneficial medication to protect germ cells against apoptosis induced by nanoparticles and be helpful for male fertility.

Effect of finishing period length with α-tocopherol supplementation on the expression of vitamin E-related genes in the muscle and subcutaneous fat of light lambs

The aim of this study was to investigate how different finishing period lengths with α-tocopherol supplementation or alfalfa grazing affect mRNA expression levels of genes related to vitamin E metabolism in L. thoracis (LT) muscle and subcutaneous fat (SF) from lambs of the Rasa Aragonesa breed. Indoors, concentrate-fed light lambs (n=48) were supplemented with 500 dl-α-tocopheryl acetate/kg concentrate for an average finishing period length of 0 (C), 10.7 (VE10d), 21.2 (VE20d) and, 32.3 (VE30d) days before slaughtering. Simultaneously, 8 lambs with their dams were alfalfa-grazed. The α-tocopherol affected in a short-term the expression of genes in LT muscle (ABCA1, LPL, APOE, and SREBP1) and SF (ABCA1, SCARB1, LPL, and PPARG). On the contrary, PPARA gene expression showed a long-term α-tocopherol effect because the highest levels of PPARA mRNA were found in the VE30d.

Effect of beta-carotene on titanium oxide nanoparticles-induced testicular toxicity in mice

OBJECTIVE

This study evaluated the protective effect of beta-carotene (BC) on titanium oxide nanoparticle (TNP) induced spermatogenesis defects in mice.

MATERIALS AND METHODS

Thirty-two NMRI mice were randomly divided into four groups. BC group received 10 mg/kg of BC for 35 days. TNP group received 300 mg/kg TNP for 35 days. TNP+BC group initially received 10 mg/kg BC for 10 days and was followed by concomitant administration of 300 mg/kg TNP for 35 days. Control group received only normal saline for 35 days. Epididymal sperm parameters, testicular histopathology, spermatogenesis assessments and testosterone assay were performed for evaluation of the TNP and BC effects on testis.

RESULTS

Serum testosterone levels were markedly decreased in TNP-intoxicated mice. Epididymal sperm parameters including sperm number, motility and percentage of abnormality were significantly changed in TNP-intoxicated mice (p < 0.01). Histopathological criteria such as epithelial vacuolization, sloughing of germ cells and detachment were significantly increased in TNP-intoxicated mice (p < 0.001). BC+TNP treatment significantly prevented these changes (p < 0.05). BC also significantly elevates testosterone levels in BC+TNP group compared to TNP-treated mice (p < 0.01).

DISCUSSION AND CONCLUSION

The results of this study demonstrated that BC improved the spermatogenesis defects in TNP-treated mice. BC had a potent protective effect against the testicular toxicity and might be clinically useful.