Zinc deficiency decreased cell viability both in endothelial EA.hy926 cells and mouse aortic culture ex vivo and its implication for anti-atherosclerosis

Zinc Action in Vascular Calcification

Although zinc's involvement in bone calcification is well-established, its role in vascular calcification, characterized by abnormal calcium and phosphorus deposition in soft tissues and a key aspect of various vascular diseases, including atherosclerosis, remains unclear. This review focuses on zinc's action in vascular smooth muscle cell (VSMC) calcification, including the vascular calcification mechanism. Accumulated research has indicated that zinc deficiency induces calcification in VSMCs and the aorta, primarily through apoptosis accompanied by a downregulation of smooth muscle cell markers. Moreover, zinc deficiency-induced vascular calcification operates independently of the action of alkaline phosphatase (ALP) activity, typically associated with osteogenic processes, but is partly regulated via inorganic phosphate transporter-1 (Pit-1). To date, research has shown that zinc regulates vascular calcification through a mechanism distinct from that of osteogenic calcification, providing insight into its dual effects on physiological and pathological calcification and thereby explaining the "zinc paradox," wherein zinc simultaneously increases osteoblastic calcification and decreases VSMC calcification.

The association between zinc and endothelial adhesion molecules ICAMs and VCAM-1 and nuclear receptors PPAR-ɑ and PPAR-γ: A systematic review on cell culture, animal and human studies

BACKGROUND

Cardiovascular health is strongly influenced by diet. The levels of inflammatory factors like ICAM-1 and VCAM-1 are high in patients with atherosclerosis or predisposing factor for heart disease. Antioxidant and anti-inflammatory functions are attributed to zinc. We systematically reviewed cell culture, human or animal studies for determining the relationship between zinc status and ICAMs or VCAM-1 levels.

METHODS

PubMed, Google Scholar, Scopus, and Cochrane databases from database inception till 30th August 2020 were systematically searched to obtain any possible article for inclusion.

RESULTS

After screening and removing unrelated or duplicate articles by the title and abstract by two independent reviewers, 15 articles were included. Results indicating an inverse relationship between zinc status with ICAM-1 or VCAM-1 levels and the development of endothelial inflammation, plaque formation, or atherosclerosis. A direct relationship between zinc status and PPAR-α or γ levels was also observed. Zinc oxide (ZnO), zinc nanoparticles, or ions can cause endothelial activation and increased levels of ICAM-1 and VCAM-1.

CONCLUSION

Normal function of the endothelium is linked with zinc level. Zinc deficiency causes atherosclerosis, most probably via increased production of ICAM-1 and VCAM-1; and decreased expression of PPAR-ɑ and PPAR-γ receptors. Contrarily, endothelial activation and increased ICAM-1 and VCAM-1 levels can be caused by ZnO, zinc nanoparticles, or zinc ions.

Ex vivo culture of human atherosclerotic plaques: A model to study immune cells in atherogenesis

BACKGROUND AND AIMS

The mechanisms that drive atherosclerotic plaque progression and destabilization in humans remain largely unknown. Laboratory models are needed to study these mechanisms under controlled conditions. The aim of this study was to establish a new ex vivo model of human atherosclerotic plaques that preserves the main cell types in plaques and the extracellular components in the context of native cytoarchitecture.

METHODS

Atherosclerotic plaques from carotid arteries of 28 patients undergoing carotid endarterectomy were dissected and cultured. At various time-points, samples were collected and analysed histologically. After enzymatic digestion, single cells were analysed with flow cytometry. Moreover, tissue cytokine production was evaluated.

RESULTS

We optimised the plaque dissection protocol by cutting plaques into circular segments that we cultured on collagen rafts at the medium-air interface, thus keeping them well oxygenated. With this technique, the relative presence of T and B lymphocytes did not change significantly during culture, and the sizes of lymphocyte subsets remained stable after day 4 of culture. Macrophages, smooth muscle cells, and fibroblasts with collagen fibres, as well as T and B lymphocyte subsets and CD16 natural killer cells, remained largely preserved for 19 days of culture, with a continuous production of inflammatory cytokines and chemokines.

CONCLUSIONS

Our new model of ex vivo human atherosclerotic plaques, which preserves the main subsets of immune cells in the context of tissue cytoarchitecture, may be used to investigate important aspects of atherogenesis, in particular, the functions of immune cells under controlled laboratory conditions.

From the Cover: Zinc Deficiency Worsens and Supplementation Prevents High-Fat Diet Induced Vascular Inflammation, Oxidative Stress, and Pathological Remodeling

Obesity has become a common public health problem in the world and raises the risk of various cardiovascular diseases. Zinc is essential for multiple organs in terms of normal structure and function. The present study investigated the effects of high fat diet (HFD) induced obesity on the aorta in mice, and evaluated whether it can be affected by zinc deficiency or supplementation. Four-week-old male C57BL/6J mice were fed HFD with varied amounts of zinc (deficiency, adequate and supplementation) for 3 and 6 months. Results showed that HFD feeding induced a time-dependent aortic remodeling, demonstrated by increased vessel wall thickness, tunica cell proliferation and fibrotic responses, and inflammatory response, reflected by increased expression of inflammatory cytokines (tumor necrosis factor-α and vascular cell adhesion molecule 1). HFD feeding also caused aortic oxidative damage, reflected by 3-nitrotyrosine and 4-hydroxy-2-nonenal accumulation, and down-regulated nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression and function, shown by down-regulation of its downstream antioxidants, catalase, NAD(P)H dehydrogenase (quinone 1), and metallothionein expression. The vascular effects of obesity-induced by HFD was exacerbated by zinc deficiency but significantly improved by zinc supplementation. In addition, down-regulation of Nrf2 function and associated antioxidants expression were also worsened by zinc deficiency but improved by zinc supplementation. These results suggest that HFD induces aortic remodeling, which can be exacerbated by zinc deficiency and improved by zinc supplementation.