Granulocyte colony-stimulating factor attenuates LPS-stimulated IL-1beta release via suppressed processing of proIL-1beta, whereas TNF-alpha release is inhibited on the level of proTNF-alpha formation.
In the presence of granulocyte colony-stimulating factor (G-CSF), the release of IL-1beta and TNF-alpha by LPS-stimulated human whole blood was suppressed. Via measurement of cytokine mRNA, inactive precursor and mature protein, we investigated whether this inhibition occurs at the transcriptional, translational or post-translational level of cytokine production. G-CSF inhibited IL-1beta release, but the formation of proIL-1beta was not attenuated, indicating that G-CSF interferes with the proteolytic processing of proIL-1beta. Since the release of IL-1beta in LPS-stimulated whole blood was blocked by the caspase-1 inhibitor YVAD-cmk, processing of proIL-1beta appears to depend on caspase-1 activity. The conclusion that G-CSF inhibits caspase-1 activity was supported bythe finding that the release of IL-18 was also inhibited by G-CSF, similar to IL-1beta release. Intracellular caspase-1 activity in monocytes was measured by flow cytometry with the cell-permeablecaspase substrate Asp(2)-rhodamine. In the presence of G-CSF the cleavage of this substrate was inhibited by more than 50%. G-CSF had no effect on LPS-induced doubling of caspase-1 mRNA, indicating that G-CSF affects caspase-1 activation and not its formation. For TNF-alpha another mechanism of G-CSF action was identified: TNF-alpha as well as proTNF-alpha formation were inhibited by G-CSF, butG-CSF had no influence on LPS-induced TNF-alpha mRNA level. We therefore suggest that G-CSF causes translational silencing of LPS-induced TNF-alpha mRNA.
Biochemical Pharmacology, University of Konstanz, Konstanz, Germany.
Eva-Maria
EM
Boneberg
Thomas
T
Hartung
D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000096:biosynthesis*; D020382:Interleukin-18 / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology*; D011498:Protein Precursors / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000032:analysis; D012795:Sialoglycoproteins / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000235:genetics
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D020382:Interleukin-18; D008070:Lipopolysaccharides; D011498:Protein Precursors; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D014409:Tumor Necrosis Factor-alpha; D016179:Granulocyte Colony-Stimulating Factor; C061153:tumor necrosis factor precursor