Rare-earth orthovanadate nanoparticles trigger Ca2+-dependent eryptosis

Introduction. Rare-earth orthovanadate nanoparticles (ReVO₄:Eu³⁺, Re = Gd, Y or La) are promising agents for photodynamic therapy of cancer due to their modifiable redox properties. However, their toxicity limits their application.Objective. The aim of this research was to elucidate pro-eryptotic effects of GdVO₄:Eu³⁺and LaVO₄:Eu³⁺nanoparticles with identification of underlying mechanisms of eryptosis induction and to determine their pharmacological potential in eryptosis-related diseases.Methods. Blood samples (n= 9) were incubated for 24 h with 0-10-20-40-80 mg l^-1GdVO₄:Eu³⁺or LaVO₄:Eu³⁺nanoparticles, washed and used to prepare erythrocyte suspensions to analyze the cell membrane scrambling (annexin-V-FITC staining), cell shrinkage (forward scatter signaling), reactive oxygen species (ROS) generation through 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) staining and intracellular Ca²⁺levels via FLUO4 AM staining by flow cytometry. Internalization of europium-enabled luminescent GdVO₄:Eu³⁺and LaVO₄:Eu³⁺nanoparticles was assessed by confocal laser scanning microscopy.Results.Both nanoparticles triggered eryptosis at concentrations of 80 mg l^-1. ROS-mediated mechanisms were not involved in rare-earth orthovanadate nanoparticles-induced eryptosis. Elevated cytosolic Ca²⁺concentrations were revealed even at subtoxic concentrations of nanoparticles. LaVO₄:Eu³⁺nanoparticles increased intracellular calcium levels in a more pronounced way compared with GdVO₄:Eu³⁺nanoparticles. Our data disclose that the small-sized (15 nm) GdVO₄:Eu³⁺nanoparticles were internalized after a 24 h incubation, while the large-sized (∼30 nm) LaVO₄:Eu³⁺nanoparticles were localized preferentially around erythrocytes.Conclusions.Both internalized GdVO₄:Eu³⁺and non-internalized LaVO₄:Eu³⁺nanoparticles (80 mg l^-1) promote eryptosis of erythrocytes after a 24 h exposurein vitrovia Ca²⁺signaling without involvement of oxidative stress. Eryptosis is a promising model for assessing nanotoxicity.

Experimental Evaluation of Food-Grade Semi-Refined Carrageenan Toxicity

The safety of food additives E407 and E407a has raised concerns in the scientific community. Thus, this study aims to assess the local and systemic toxic effects of the common food additive E407a in rats orally exposed to it for two weeks. Complex evaluations of the effects of semi-refined carrageenan (E407a) on rats upon oral exposure were performed. Local effects of E407a on the intestine were analyzed using routine histological stains and CD68 immunostaining. Furthermore, circulating levels of inflammatory markers were assessed. A fluorescent probe O1O (2- (2'-OH-phenyl)-5-phenyl-1,3-oxazole) was used for evaluating the state of leukocyte cell membranes. Cell death modes of leukocytes were analyzed by flow cytometry using Annexin V and 7-aminoactinomycin D staining. Oral administration of the common food additive E407a was found to be associated with altered small and large intestinal morphology, infiltration of the lamina propria in the small intestine with macrophages (CD68+ cells), high systemic levels of inflammation markers, and changes in the lipid order of the phospholipid bilayer in the cell membranes of leukocytes, alongside the activation of their apoptosis. Our findings suggest that oral exposure to E407a through rats results in the development of intestinal inflammation.