Effects of copper sulfate-oxidized or myeloperoxidase-modified LDL on lipid loading and programmed cell death in macrophages under hypoxia

Development of a Method for Producing oxLDL: Characterization of Their Effects on HPV-Positive Head and Neck Cancer Cells

Cardiovascular diseases (CVD) and cancers are the two main causes of death worldwide. The initiation and progression of atherosclerosis is, in large part, caused by oxidized low-density lipoproteins (oxLDL); interestingly, oxLDL may also play a role in cancer cell metabolism and migration. As oxLDL are generally obtained by tedious ultracentrifugation procedures, “home-made” oxLDL were obtained by (i) applying a purification kit to isolate LDL and VLDL from human plasma; (ii) isolating LDL from VLDL by gel permeation chromatography (GPC); and (iii) oxidating LDL through CuSO₄ incubation. On three HPV-positive head and neck cancer cells (HNCC) (93VU-147T, UM-SCC47, and UPCI-SCC154), cell migration was assessed using Boyden chambers, the Wnt/ß-catenin pathway was analyzed by Western Blotting, and the expression of two oxLDL receptors, LOX-1 and CD36, in response to oxLDL exposure, was analysed by immunofluorescence. Our data indicate: (a) a non-significant difference between reference and “home-made” oxLDL; (b) a decreased migration, parallel to an inhibition of the ß-catenin pathway; and (c) an increase of CD36 and LOX-1 expression in all HNCC. In conclusion, we successfully produced oxLDL. Our results demonstrate a decrease in HNCC migration after oxLDL exposure, and an increased expression of LOX-1 and CD36 associated with lipid uptake.

Role of myeloperoxidase in inflammation and atherosclerosis (Review)

Myeloperoxidase (MPO) belongs to the heme peroxidase family, which includes a set of enzymes with potent oxidoreductase activity. MPO is considered an important part of the innate immune system's microbicidal arm and is secreted by neutrophils and macrophages. Interestingly, this enzyme has been implicated in the pathogenesis of several diseases including atherosclerosis. MPO is ubiquitous in atherosclerotic lesions and contributes to the initiation and progression of the disease primarily by oxidizing low-density lipoprotein (LDL) particles. MPO is the only human enzyme with the ability to produce hypochlorous acid (HOCl) at physiological chloride concentrations and HOCl-LDL epitopes were shown to be present inside atheromatous lesions making it a physiologically relevant model for the oxidation of LDL. It has been shown that MPO modified LDL is not able to bind to the native LDL receptor and is recognized instead by scavenger receptors on both endothelial cells and macrophages, which can lead to endothelial dysfunction and foam cell formation, respectively; both of which are instrumental in the progression of the disease. Meanwhile, several studies have proposed MPO as a biomarker for cardiovascular diseases where high levels of this enzyme were linked to an increased risk of developing coronary artery disease. Overall, there is sufficient evidence supporting the value of MPO as a crucial player in health and disease. Thus, future research should be directed towards investigating the still unknown processes associated with this enzyme. This may assist in better understanding the pathophysiological role of MPO, as well in the development of therapeutic strategies for protecting against the deleterious effects of MPO in numerous pathologies such as atherosclerosis.