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Increased superoxide anion production and glutathione peroxidase activity in peritoneal macrophages from
K Rokutan1, T Hosokawa, K Nakamura
1Department of Preventive Medicine, Kyoto Prefectural University of Medicine, Japan.
Abstract:
We studied the release of superoxide anion (O-2) in peritoneal macrophages from autoimmuneprone MRL/Mp-lpr/lpr (MRL/l) mice. Compared to resident peritoneal macrophages from control MRL/Mp-+/+ (MRL/n) mice, macrophages from MRL/l mice exhibited an age-related increase of spontaneous and PMA-induced O-2 secretion in association with the development of the autoimmune process. Analysis of the kinetic parameters of NADPH oxidase in macrophages revealed that MRL/l macrophages were in a primed state, as shown by the decreased Km value of the oxidase for NADPH. Furthermore, we studied several key enzymes for their ability to scavenge the oxygen radicals in the macrophages. Among the enzymes studied, only glutathione peroxidase (GSH Px) activity was increased in peritoneal macrophages from MRL/l mice and this change was closely correlated with the increase in O-2 production. Thus, GSH Px activity in macrophages seems to play an important role in macrophage functions under increased oxidative stress.
Insights
Autoimmune-prone mice show increased superoxide anion (O-2) release from macrophages. This is linked to higher glutathione peroxidase (GSH Px) activity, suggesting its role in managing oxidative stress during autoimmune disease.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Autoimmune diseases are often associated with chronic inflammation and oxidative stress.
- Macrophages play a critical role in both innate and adaptive immunity, and their function can be altered during autoimmune conditions.
Purpose of the Study:
- To investigate the release of superoxide anion (O-2) in peritoneal macrophages from autoimmune-prone MRL/Mp-lpr/lpr (MRL/l) mice.
- To analyze the activity of NADPH oxidase and key oxygen radical scavenging enzymes in these macrophages.
Main Methods:
- Peritoneal macrophages were isolated from MRL/l mice and control MRL/Mp-+/+ (MRL/n) mice.
- Superoxide anion secretion was measured, along with kinetic parameters of NADPH oxidase.
- Activity of enzymes involved in oxygen radical scavenging, including glutathione peroxidase (GSH Px), was assessed.
Main Results:
- Macrophages from MRL/l mice exhibited an age-related increase in spontaneous and PMA-induced O-2 secretion compared to MRL/n mice.
- MRL/l macrophages showed a primed state of NADPH oxidase, indicated by a decreased Km for NADPH.
- Glutathione peroxidase (GSH Px) activity was significantly increased in MRL/l macrophages and correlated with O-2 production.
Conclusions:
- Macrophages from autoimmune-prone MRL/l mice display heightened O-2 production linked to an activated NADPH oxidase.
- Increased GSH Px activity in MRL/l macrophages appears to be a compensatory mechanism to manage elevated oxidative stress.
- GSH Px plays a crucial role in macrophage function under conditions of increased oxidative stress in autoimmune settings.