Our aim was to evaluate the effect of hyperlipidemia on the activation of endogenous alarmin, the high mobility group box 1 (HMGB1) protein, related to systemic inflammation associated with the progression of experimental atherosclerosis and to establish whether statin treatment regulates the HMGB1 signaling pathway. Hyperlipidemia was induced in vivo in golden Syrian hamsters and in monocyte cell culture (U937) by feeding the animals with a high-fat Western diet and by exposing the cells to hyperlipidemic serum. Blood samples, heart, lung and cells were harvested for biochemical, morphological, Western blot, quantitative polymerase chain reaction and enzyme-linked immunosorbent assay analyses. The data revealed that, in the atherosclerotic animal model, the protein HMGB1 and its gene expression were increased and that fluvastatin treatment significantly reduced the release of HMGB1 into the extracellular space. The cell culture experiments demonstrated the relocation of HMGB1 protein from the nucleus to cytoplasm under hyperlipidemic stress. The high level of detected HMGB1 correlated positively with the up-regulation of the advanced glycation end product receptors (RAGE) in the lung tissue from hyperlipidemic animals. During hyperlipidemic stress, the AKT signaling pathway could be activated by HMGB1-RAGE interaction. These results support the existence of a direct correlation between experimentally induced hyperlipidemia and the extracellular release of HMGB1 protein; this might be controlled by statin treatment. Moreover, the data suggest new potentials for statin therapy, with improved effects on patients with systemic inflammation induced by hyperlipidemia.
Our study focused on the long-term degradation under simulated conditions of coatings based on different compositions of polycaprolactone-polyethylene glycol blends (PCL-blend-PEG), fabricated for titanium implants by a dip-coating technique. The degradation behavior of polymeric coatings was evaluated by polymer mass loss measurements of the PCL-blend-PEG during immersion in SBF up to 16 weeks and correlated with those yielded from electrochemical experiments. The results are thoroughly supported by extensive compositional and surface analyses (FTIR, GIXRD, SEM, and wettability investigations). We found that the degradation behavior of PCL-blend-PEG coatings is governed by the properties of the main polymer constituents: the PEG solubilizes fast, immediately after the immersion, while the PCL degrades slowly over the whole period of time. Furthermore, the results evidence that the alteration of blend coatings is strongly enhanced by the increase in PEG content. The biological assessment unveiled the beneficial influence of PCL-blend-PEG coatings for the adhesion and spreading of both human-derived mesenchymal stem cells and endothelial cells.
A high-lipid diet is one of the main risk factors in atherosclerosis and can induce changes in the composition of plasma membrane microdomains. In response, important functions such as vesicle trafficking, protein docking, signaling and receptor recognition are significantly altered. In particular, interactions of heat-shock proteins (Hsps), acting as danger signals, with components of the membrane microdomains can influence signaling pathways and the inflammatory response of cells. Our study focuses on the composition of detergent-resistant membrane (DRM) isolated from ApoE-/- mice fed a standard or high-fat diet with and without fluvastatin treatment versus appropriate controls. Biochemical studies, immunoblotting and liquid chromatography mass spectrometric analysis were performed to investigate whether the structural components (such as caveolin and cavin) of the detergent-resistant microdomains were correlated with the expression and secretion of stress-inducible Hsps (Hsp70 and Hsp90) and AKT phosphorylation in experimental atherosclerosis. ApoE-/- mice challenged with a high-fat diet developed extensive atherosclerotic plaques in lesion-prone areas. DRM harvested from hyperlipidemic animals showed a modified biochemical composition with cholesterol, glycerolipids, caveolin-1 and phospho-AKT being up-regulated, whereas cavin-1 and dynamin were down-regulated. The data also demonstrated the co-fractionation of Hsps with caveolin-1 in isolated DRM, expression being positively correlated with their secretion into blood serum. Statin therapy significantly attenuated the processes induced by the development of atherosclerosis in ApoE-/- mice under a high-fat diet. Thus, high-lipid stress induces profound changes in DRM biochemistry and modifies the cellular response, supporting the systemic inflammatory onset of atherosclerosis.
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