Effects of intracellular ions on interleukin-1 beta production by lipopolysaccharide-activated human monocytes.
Following the observation that interleukin 1 beta (IL-1 beta) production in lipopolysaccharide (LPS)activated monocytes increases in concert with a rise in intracellular pH (pHi), the role of ion transport in IL-1 beta production was investigated. The amiloride analogue 5-(N-ethyl-N-isopropyl)amiloride (EIPA), an inhibitor of the Na(+)-H+ antiporter, inhibited extracellular IL-1 beta. The replacement of Na+ in the culture medium with sucrose or choline chloride also prevented monocyte activation. The sodium ionophore monensin, in doses from 100 pM to 1 microM, potentiated LPS-stimulated extracellular IL-1 beta when compared with LPS alone. In the absence of LPS activation, monensin by itself at 10 nM stimulated IL-1 beta production to 63%. EIPA at 10 microM inhibited the Na+ influx, the rise in pHi, and intra- and extracellular IL-1 beta production in activated monocytes; this inhibition was reversed by 10 nM monensin. In the absence of bicarbonate, or in the presence of 10 microM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, the pHi of activated monocytes and the total protein synthesis did not change, but the production of IL-1 beta was inhibited. The data suggest that the stimulated influx of Na+ via the Na(+)-H+ antiporter regulates both pHi and IL-1 beta production in LPS-activated monocytes. The requirement for bicarbonate indicates an additional mechanism(s), separate from the modulation of pHi and intracellular Na+.
Orlinska
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Du Pont Merck Pharmaceutical, Inflammatory Diseases Research, Glenolden, Pennsylvania 19036.
Newton
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D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism* / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D003470:Culture Media; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D007425:Intracellular Membranes / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008985:Monensin / Q000494:pharmacology; D009000:Monocytes / Q000378:metabolism*; D014176:Protein Biosynthesis; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology
D001639:Bicarbonates; D002712:Chlorides; D003470:Culture Media; D007375:Interleukin-1; D008070:Lipopolysaccharides; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D000584:Amiloride; D008985:Monensin; D012964:Sodium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; C039614:ethylisopropylamiloride