formazans and Lymphoma--Large-B-Cell--Diffuse

Tyloxapol is reported to prevent macrophages from reacting to endotoxin. However, the intracellular responses that tyloxapol induces in macrophages are still not fully explored. Hence, the objective of this study was to evaluate the intracellular events in macrophages treated with tyloxapol and assess the antioxidant properties of tyloxapol in endotoxin-activated macrophages. Using flow cytometry, we examined intracellular responses in macrophages: reactive oxygen species (ROS) content, mitochondria membrane potential, and cell cycle profiles. We also assessed the antioxidant properties of tyloxapol in endotoxin-activated macrophages. Kinetic hydrogen peroxide production tended to decline with increasing doses. Tyloxapol produced a progressive increase followed by a decline in superoxide anion production in macrophages with increasing doses. Tyloxapol also caused unstable fluctuations in mitochondrial membrane potential. Apoptosis had developed at higher doses after 4h of incubation time. After 2h of tyloxapol-pretreatment, tyloxapol acted as an antioxidant only at lower doses. Most tyloxapol-pretreated cells at lower doses fully recovered from the changes in superoxide anion and hydrogen peroxide production. Our findings contribute to a better understanding of the molecular action of tyloxapol in macrophages and how it protects macrophages against endotoxin.

Topics: Antioxidants; Apoptosis; Cell Culture Techniques; Cell Cycle; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Flow Cytometry; Formazans; Humans; Hydrogen Peroxide; Indicators and Reagents; Liposomes; Lymphoma, Large B-Cell, Diffuse; Macrophage Activation; Macrophages; Membrane Potential, Mitochondrial; Mitochondria; Oxidoreductases; Polyethylene Glycols; Reactive Oxygen Species; Superoxides; Time Factors

Catanionic vesicles are considered a potential alternative to liposomes for drug delivery systems because of their greater stability and lower cost. Before using catanionic vesicles in vivo, their interactions with macrophages must be fully understood because they are primarily removed from circulation by the macrophages of the mononuclear phagocyte system. Using flow cytometry, we examined the intracellular responses-reactive oxygen species (ROS) content, mitochondrial membrane potential, cell size and complexity, and cell cycle profiles-in U-937 human macrophages treated with positively charged catanionic vesicles. Kinetic hydrogen peroxide production initially increased at lower concentrations (4-10nM) but declined at higher concentrations (40 nM and 80 nM) over the entire incubation period. Superoxide content generation, however, increased over the entire concentration range and incubation period. Catanionic vesicles decreased mitochondrial membrane potential for every concentration after 4h of incubation but caused a significant fluctuation in mitochondrial membrane potential at 6h. After 6h of incubation, catanionic vesicles produced more changes in cell size and complexity than after 4h. The increase in the subG1 population of cells treated with catanionic vesicles at higher doses indicated that apoptosis progressed. Positively charged catanionic vesicles induced different activated patterns of ROS generation and changes in mitochondrial membrane potential than did cationic liposomes. The nature of the interactions between macrophages and catanionic vesicles is of great importance for the design of safer and more effective delivery systems for macrophages. Our findings contribute to a better understanding of the molecular action of catanionic vesicles in the cellular system.

Topics: Apoptosis; Cations; Cell Culture Techniques; Cell Cycle; Cell Line, Tumor; Cell Size; Cell Survival; Dose-Response Relationship, Drug; Flow Cytometry; Fluorescent Dyes; Formazans; G1 Phase; Humans; Hydrogen Peroxide; Indicators and Reagents; Kinetics; Liposomes; Lymphoma, Large B-Cell, Diffuse; Macrophages; Membrane Potential, Mitochondrial; Mitochondria; Phenanthridines; Reactive Oxygen Species; Superoxides; Time Factors