Oxidative stress in vascular calcification.

Vascular calcification (VC), which is closely associated with significant mortality in cardiovascular disease, chronic kidney disease (CKD), and/or diabetes mellitus, is characterized by abnormal deposits of hydroxyapatite minerals in the arterial wall. The impact of oxidative stress (OS) on the onset and progression of VC has not been well described. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, xanthine oxidases, myeloperoxidase (MPO), nitric oxide synthases (NOSs), superoxide dismutase (SOD) and paraoxonases (PONs) are relevant factors that influence the production of reactive oxygen species (ROS). Furthermore, excess ROS-induced OS has emerged as a critical mediator promoting VC through several mechanisms, including phosphate balance, differentiation of vascular smooth muscle cells (VSMCs), inflammation, DNA damage, and extracellular matrix remodeling. Because OS is a significant regulator of VC, antioxidants may be considered as novel treatment options.

Adipokines in vascular calcification.

Adipose tissue (AT), a critical endocrine gland, is capable of producing and secreting abundant adipokines. Adipokines act on distant or adjacent organ tissues via paracrine, autocrine, and endocrine mechanism, which play attractive roles in the regulation of glycolipid metabolism and inflammatory response. Increasing evidence shows that adipokines can connect obesity with cardiovascular diseases by serving as promoters or inhibitors in vascular calcification. The chronic hypoxia in AT, caused by the adipocyte hypertrophy, is able to trigger imbalanced adipokine generation, which leads to apoptosis, osteogenic differentiation of vascular smooth muscle cells (VSMCs), vascular inflammation, and abnormal deposition of calcium and phosphorus in the vessel wall. The objectives of this review aim at providing a brief summary of the crucial influence of major adipokines on the formation and development of vascular calcification, which may contribute to better understanding these adipokines for establishing the appropriate therapeutic strategies to counteract obesity-associated vascular calcification.

S100 proteins in atherosclerosis.

Atherosclerosis is an arterial disease associated with dyslipidemia, abnormal arterial calcification and oxidative stress. It has been shown that a continued chronic inflammatory state of the arterial wall contributes to the development of atherosclerosis. The inflammatory stimulation, recruitment of inflammatory cells and production of pro-inflammatory cytokines enhances vascular inflammation. Some members of the S100 proteins family bind with their receptors, such as advanced glycation end products (RAGE), scavenger receptors (CD36) and toll-like receptor 4 (TLR-4), contributing to the cellular response in atherosclerotic progression. This review summarizes the roles of S100 proteins (S100A8, S100A9 and S100A12) in the vascular inflammation, vascular calcification and vascular oxidative stress. S100 proteins are released from monocytes, smooth muscle cells and endothelial cells in response to cellular stress stimuli, and then the binding of S100 proteins to RAGE activate downstream signaling such as transcription factor kappa B (NF-κB) translocation and reactive oxygen species (ROS) production, which act as a positive feedback loop for inducing pro-inflammatory phenotype in a wide variety of cell types including endothelial cells, vascular smooth muscle cells and leukocytes. Thus, it suggests that the inhibition of S100 proteins-mediated RAGE and TLR4 activation appears to be a promising approach to treat atherosclerosis. In addition, recent study showed that serum S100A12 can predict future cardiovascular events, highlighting that S100A12 is likely to be a potential biomarker of therapeutic efficacy and disease progression in coronary heart disease. Future studies of patients with coronary heart disease may provide more evidences supporting that S100 proteins is promising drug target in the prevention and therapy of atherosclerosis.