Normal IgG downregulates the intracellular superoxide level and attenuates migration and permeability in human aortic endothelial cells isolated from a hypertensive patient.
The normal IgG, a circulating antibody, is maintained at a constant level in humans. However, little is known regarding whether normal IgG has effects on the function of vascular endothelial cells. The purpose of this study was to investigate whether IgG affects superoxide (O(2)(·-)) generation and cell permeability in human aortic endothelial cells (HAECs) isolated from a hypertensive patient. The effect of normal human IgG on endothelial cell function was investigated in cultured HAECs isolated from a hypertensive patient who died of stroke. The results demonstrated, for the first time, that normal IgG attenuated the intracellular O(2)(·-) level and decreased cell migration, cell permeability, and stress fiber formation in HAECs. IgG significantly decreased Rac1 activity and NADPH oxidase activity but upregulated Mn superoxide dismutase expression in HAECs, which may contribute to the IgG-induced decrease in O(2)(·-) level. It is noted that AMP-activated protein kinase (AMPK) was activated by IgG, as evidenced by increased phosphorylation of AMPK. Interestingly, inhibition of AMPK by an AMPK inhibitor abolished IgG-induced decreases in Rac1 and NADPH oxidase activities and IgG-induced increases in Mn superoxide dismutase expression, suggesting that AMPK is an important mediator of the IgG-induced regulation of these enzymes. Importantly, inhibition of AMPK activity also prevented the IgG-induced decrease in O(2)(·-) levels, cell migration, cell permeability, and stress fiber formation. Therefore, normal human IgG may protect HAECs via activation of AMPK and subsequent decreases in intracellular O(2)(·-). These findings reveal a previously unidentified role of normal IgG in regulating AMPK and endothelial cell function.
Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center, 940 SL Young Blvd, Oklahoma City, OK 73126-0901, USA.
Xiuqing
X
Wang
Qianyu
Q
Wang
Zhongjie
Z
Sun
D000091162:AMP-Activated Protein Kinase Kinases; D001011:Aorta / Q000378:metabolism / Q000473:pathology*; D015820:Cadherins / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002465:Cell Movement / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D006973:Hypertension / Q000378:metabolism / Q000473:pathology*; D007074:Immunoglobulin G / Q000494:pharmacology*; D019255:NADPH Oxidases / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D015820:Cadherins; D007074:Immunoglobulin G; C107953:RAC1 protein, human; D013481:Superoxides; D013482:Superoxide Dismutase; D019255:NADPH Oxidases; D011494:Protein Kinases; D000091162:AMP-Activated Protein Kinase Kinases; D020830:rac1 GTP-Binding Protein