Activation of microglia depends on Na+/H+ exchange-mediated H+ homeostasis.
H(+) extrusion is important for sustained NADPH oxidase activation after "respiratory" burst in macrophage/microglia activation. In this study, we investigated the role of Na(+)/H(+) exchanger isoform 1 (NHE-1) in activation of microglia after lipopolysaccharide (LPS) or oxygen and glucose deprivation and reoxygenation (OGD/REOX) exposure. NHE-1 functioned in maintaining basal pH(i) of immortalized M4T.4 microglia or mouse primary microglia. Pharmacological inhibition of NHE-1 activity with the potent inhibitor cariporide [HOE 642 (4-isopropyl-3-methylsulfonyl-benzoyl-guanidine-methanesulfonate)] abolished pH(i) regulation in microglia under basal conditions. Activation of microglia either by LPS, phorbol myristate acetate, or OGD/REOX accelerated pH(i) regulation and caused pH(i) elevation, which was accompanied with an increase in [Na(+)](i) and [Ca(2+)](i) as well as production of superoxide anion and cytokines. Interestingly, inhibition of NHE-1 not only abolished pH(i) regulation but also reduced production of superoxide anion as well as expression of cytokines and inducible nitric oxide synthase. Together, these results reveal that there was a concurrent activation of NHE-1 in microglia in response to proinflammatory stimuli. The study suggests that NHE-1 functions to maintain microglial pH(i) homeostasis allowing for sustained NADPH oxidase function and "respiratory" burst.
Department of Biological Sciences and Biotechnology, School of Medicine, Tsinghua University, Beijing 100084, China.
Yan
Y
Liu
Douglas B
DB
Kintner
Vishal
V
Chanana
Jehad
J
Algharabli
Xinzhi
X
Chen
Yanqin
Y
Gao
Jun
J
Chen
Peter
P
Ferrazzano
Julie K
JK
Olson
Dandan
D
Sun
D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D005947:Glucose / Q000172:deficiency; D006146:Guanidines / Q000494:pharmacology; D006706:Homeostasis / Q000502:physiology*; D000860:Hypoxia / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D017628:Microglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D016897:Respiratory Burst / Q000502:physiology; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D013450:Sulfones / Q000494:pharmacology
D006146:Guanidines; D008070:Lipopolysaccharides; D017923:Sodium-Hydrogen Exchangers; D013450:Sulfones; C069139:growth factor-activatable Na-H exchanger NHE-1; C093373:cariporide; D052247:Nitric Oxide Synthase Type II; D019255:NADPH Oxidases; D005947:Glucose; D002118:Calcium