Effects of serine protease inhibitor, TAME, on IL-1 beta in LPS-stimulated human monocytes: relationship between synthesis and release of a 33-kDa precursor and the 17-kDa biologically active species.
LPS stimulation of human monocytes in vitro induced release of the 17-kDa mature IL-1 beta (mIL-1 beta) but did not result in release of precursor IL-1 beta (pIL-1 beta). In contrast, the presence of a serine protease inhibitor, N alpha-(p-toluene sulfonyl)-L-arginine methyl ester (TAME; 10 mM) for 6 or 18 h was associated with the LPS-stimulated release of the 33-kDa pIL-1 beta as well. These effects were initially discerned from observations that the fraction of the total IL-1 beta produced (as detected by ELISA) that was released from monocytes increased in the presence of TAME, and immunoblot assays confirmed that this fraction was predominantly 33-kDa IL-1 beta. A global decrease in monocyte protein synthesis was also observed after prolonged (18-h) exposure to TAME and was associated with a decrease in IL-1 beta synthesis, predominantly affecting 31-kDa pIL-1 beta, and a dose-dependent inhibition of TNF-alpha production. Parallel examination of lactate dehydrogenase (LDH) release indicated that pIL-1 beta release was unrelated to cell lysis. These results demonstrate that TAME-inhibitable serine proteases are probably involved in the production and eventual proteolysis of the 33-kDa pIL-1 beta in situ but are probably not mechanistically related to either maturation of the IL-1 beta molecule or signaling of IL-1 beta release. IL-1 beta release appears to be dependent on the amount of total IL-1 beta synthesized. Serine proteolysis may constitute a degradative pathway for excess precursor, which, if interfered with, could result in release of the higher-molecular-weight forms of IL-1 beta.
Jessop
J J
JJ
Laboratory of Cell Biology, U.S. Food and Drug Administration, Bethesda, Maryland 20892.
Henry
S L
SL
Hoffman
T
T
D000328:Adult; D003513:Cycloheximide / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007375:Interleukin-1 / Q000032:analysis*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008970:Molecular Weight; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000096:biosynthesis*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D013997:Time Factors; D014106:Tosylarginine Methyl Ester / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D007375:Interleukin-1; D008070:Lipopolysaccharides; D011498:Protein Precursors; D015842:Serine Proteinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; D014106:Tosylarginine Methyl Ester; D003513:Cycloheximide; D007770:L-Lactate Dehydrogenase