TY - JOUR
T1 - Interleukin-10-mediated inhibition of free radical generation in macrophages
AU - Dokka, Sujatha
AU - Shi, Xianglin
AU - Leonard, Stephen
AU - Wang, Liying
AU - Castranova, Vincent
AU - Rojanasakul, Yon
PY - 2001
Y1 - 2001
N2 - Interleukin-10 (IL-10) is a pleiotropic cytokine that controls inflammatory processes by suppressing the production of proinflammatory cytokines that are known to be transcriptionally regulated by nuclear factor-κB (NF-κB). Although still controversial, IL-10 has been shown to inhibit NF-κB activation through a process that involves proteolytic degradation of inhibitory subunit IκB-α. What is not known, however, is the mechanism by which IL-10 exerts its effect on IκB-α degradation. The present study investigates the possible role of reactive oxygen species (ROS) and their inhibition by IL-10 in NF-κB activation and IκB-α degradation in macrophages. Treatment of the cells with lipopolysaccharide (LPS) caused activation of NF-κB and rapid proteolysis of IκB-α as determined by the electrophoretic mobility shift assay, gene transfection, and Western blot. IL-10 pretreatment inhibited both NF-κB activation and IκB-α degradation. Both of these processes were also inhibited by ROS scavengers, catalase (H2O2 scavenger), and sodium formate (·OH scavenger) but were minimally affected by superoxide dismutase (O-2 scavenger). These results suggests that ·OH radicals, formed by an H2O2-dependent, metal-catalyzed Fenton reaction, play a major role in this process. Electron spin resonance studies confirmed the formation of ·OH radicals in LPS-treated cells. Addition of IL-10 inhibited both IκB-α degradation and generation of ·OH radicals in response to LPS stimulation. These results demonstrate, for the first time, direct evidence for the role of IL-10 in ROS-dependent NF-κB activation.
AB - Interleukin-10 (IL-10) is a pleiotropic cytokine that controls inflammatory processes by suppressing the production of proinflammatory cytokines that are known to be transcriptionally regulated by nuclear factor-κB (NF-κB). Although still controversial, IL-10 has been shown to inhibit NF-κB activation through a process that involves proteolytic degradation of inhibitory subunit IκB-α. What is not known, however, is the mechanism by which IL-10 exerts its effect on IκB-α degradation. The present study investigates the possible role of reactive oxygen species (ROS) and their inhibition by IL-10 in NF-κB activation and IκB-α degradation in macrophages. Treatment of the cells with lipopolysaccharide (LPS) caused activation of NF-κB and rapid proteolysis of IκB-α as determined by the electrophoretic mobility shift assay, gene transfection, and Western blot. IL-10 pretreatment inhibited both NF-κB activation and IκB-α degradation. Both of these processes were also inhibited by ROS scavengers, catalase (H2O2 scavenger), and sodium formate (·OH scavenger) but were minimally affected by superoxide dismutase (O-2 scavenger). These results suggests that ·OH radicals, formed by an H2O2-dependent, metal-catalyzed Fenton reaction, play a major role in this process. Electron spin resonance studies confirmed the formation of ·OH radicals in LPS-treated cells. Addition of IL-10 inhibited both IκB-α degradation and generation of ·OH radicals in response to LPS stimulation. These results demonstrate, for the first time, direct evidence for the role of IL-10 in ROS-dependent NF-κB activation.
KW - Nuclear factor-κB
KW - Oxygen free radicals
KW - Tumor necrosis factor-α
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U2 - 10.1152/ajplung.2001.280.6.l1196
DO - 10.1152/ajplung.2001.280.6.l1196
M3 - Article
C2 - 11350798
AN - SCOPUS:0034989573
SN - 1040-0605
VL - 280
SP - L1196-L1202
JO - American Journal of Physiology - Lung Cellular and Molecular Physiology
JF - American Journal of Physiology - Lung Cellular and Molecular Physiology
IS - 6 24-6
ER -