Endothelial protein disulfide isomerase A1 enhances membrane stiffness and platelet-endothelium interaction in hyperglycemia via SLC3A2 and LAMC1.

BACKGROUND: Diabetes carries an increased risk of cardiovascular disease and thromboembolic events. Upon endothelial dysfunction, platelets bind to endothelial cells to precipitate thrombus formation; however, it is unclear which surface proteins regulate platelet-endothelium interaction. We and others have shown that peri/epicellular protein disulfide isomerase A1 (pecPDI) influences the adhesion and migration of vascular cells. OBJECTIVES: We investigated whether pecPDI regulates adhesion-related molecules on the surface of endothelial cells and platelets that influence the binding of these cells in hyperglycemia. METHODS: Immunofluorescence was used to assess platelet-endothelium interaction in vitro, cytoskeleton reorganization, and focal adhesions. Hydrogen peroxide production was assessed via Amplex Red assays (ThermoFisher Scientific). Cell biophysics was assessed using atomic force microscopy. Secreted proteins of interest were identified through proteomics (secretomics), and targets were knocked down using small interfering RNA. Protein disulfide isomerase A1 (PDI) contribution was assessed using whole-cell PDI or pecPDI inhibitors or small interfering RNA. RESULTS: Platelets of healthy donors adhered more onto hyperglycemic human umbilical vein endothelial cells (HUVECs). Endothelial, but not platelet, pecPDI regulated this effect. Hyperglycemic HUVECs showed marked cytoskeleton reorganization, increased H2O2 production, and elongated focal adhesions. Indeed, hyperglycemic HUVECs were stiffer compared with normoglycemic cells. PDI and pecPDI inhibition reversed the abovementioned processes in hyperglycemic cells. A secretomics analysis revealed 8 proteins secreted in a PDI-dependent manner by hyperglycemic cells. Among these, we showed that genetic deletion of LAMC1 and SLC3A2 decreased platelet-endothelium interaction and did not potentiate the effects of PDI inhibitors. CONCLUSION: Endothelial pecPDI regulates platelet-endothelium interaction in hyperglycemia through adhesion-related proteins and alterations in endothelial membrane biophysics.

Atomic Force Microscopy Applied to the Study of Tauopathies.

Atomic force microscopy (AFM) is a scanning probe microscopy technique which has a physical principle, the measurement of interatomic forces between a very thin tip and the surface of a sample, allowing the obtaining of quantitative data at the nanoscale, contributing to the surface study and mechanical characterization. Due to its great versatility, AFM has been used to investigate the structural and nanomechanical properties of several inorganic and biological materials, including neurons affected by tauopathies. Tauopathies are neurodegenerative diseases featured by aggregation of phosphorylated tau protein inside neurons, leading to functional loss and progressive neurotoxicity. In the broad universe of neurodegenerative diseases, tauopathies comprise the most prevalent, with Alzheimer's disease as its main representative. This review highlights the use of AFM as a suitable research technique for the study of cellular damages in tauopathies, even in early stages, allowing elucidation of pathogenic mechanisms of these diseases.

Nanoceria Anti-inflammatory and Antimicrobial Nanodrug: Cellular and Molecular Mechanism of Action.

INTRODUCTION: Nanoceria is a well-known nanomaterial with various properties, including antioxidant, proangiogenic, and therapeutic effects. Despite its potential, there are still aspects that require further exploration, particularly its anti-inflammatory and antimicrobial activities. METHOD: The global demand for novel anti-inflammatory and antimicrobial drugs underscores the significance of understanding nanoceria in both contexts. In this study, we evaluated the effect of nanoceria on macrophage polarization to better understand its anti-inflammatory effects. Additionally, we investigated the mechanism of action of nanoceria against Cryptococcus neoformans (ATCC 32045), Candida parapsilosis (ATCC 22019), Candida krusei (ATCC 6258), and Candida albicans. RESULT: The results demonstrated that nanoceria can polarize macrophages toward an anti-inflammatory profile, revealing the cellular mechanisms involved in the anti-inflammatory response. Concerning the antimicrobial effect, it was observed that nanoceria have a more pronounced impact on Candida parapsilosis, leading to the formation of pronounced pores on the surface of this species. CONCLUSION: Finally, biochemical analysis revealed transitory alterations, mainly in liver enzymes. The data support the use of nanoceria as a potential anti-inflammatory and antimicrobial drug and elucidate some of the mechanisms involved, shedding light on the properties of this nanodrug.