TY - JOUR
T1 - Neutrophil activation by monomeric interleukin-8
AU - Rajarathnam, Krishnakumar
AU - Sykes, Brian D.
AU - Kay, Cyril M.
AU - Dewald, Beatrice
AU - Geiser, Thomas
AU - Baggiolini, Marco
AU - Clark-Lewis, Ian
N1 - Funding Information:
Neutrophil Activation by Monomeric Interleukin-8 K. Rajarathnam, B. Sykes, C. Kay, Protein Engineering Network of Centres of Excellence, Univ. of Alberta, Edmonton, AB, Canada B. Dewald, T. Geiser, M. Eaggiolini, Theodor-Kocher Institute, University of Bern, CH-3000 Bern, Switzerland I. Clark-Lewis, Univ. of British Columbia, Protein Engineering Network of Centres of Excellence, Vancouver, BC, Canada Interleukin-8 (B-8) is an inflammatory cytokine that promotes the accumulation and activation of neutrophils and has been implicated in a number of acute and chronic inflammatory diseases. IL-8 has been shown to exist as a homodimer by both NMR and x-ray techniques. To address the importance of the dimeric state for receptor binding and function, we have chemically synthesized an IL-8 analog (L25NMe) by modifying the amide of Leu-25 into NMe. This analog displays similar functional characteristics as the native protein and was shown to be a monomer by sedimentation equilibrium and NMR studies. The NMR solution structure of the monomer was found to be essentially the same as that of the dimer. These results are consistent with our previous observations that the critical domains for neutrophil activation are the N-terminal residues (4 to 22) and the turn which is disulfide linked to the N-terminus which are located away from the dimer interface. We conclude that IL-8 has a tendency to aggregate at high concentrations which are non-physiological and the functionally relevant species is the monomer. Supported by Grants from PENCE (Canada) and the Swiss National Science Foundation POTASSIUM IODIDE (KI) AS A SPECIFIC INDUCER AND MODULATOR OF CYTOKINE PRODUCTION IN HUMAN PERIPHERAL BLOOD MONONUCLEAR CELLS (PBMC) OR HUMAN FIBROBLASTS. Leland Shapiro, Paul B. Beesont, and Charles A. Dinarello. New England Medical Center Hosoitals and Tufts Universitv School of Medicine. Boston. MA. 02111, and t21013 N.E. 122nd’St., Redmond, WA 98b53. For over 100 years, KI has been used to treat syphilis, tuberculosis, and fungal diseases; it remains the treatment of choice for cutaneous sporotrichosis. Adding KI to PBMC cultures at 6.25-100 mM for 24h caused significant IL-8 induction which was maximal at 50 mM KI (101 &ml); there was no increase in IL-la induction over baseline, excluding endotoxin contamination in the KI preparation. In human foreskin fibroblasts cultured for 24h, KI had no effect on baseline IL-8 production. However, KI added lh before stimulation with IL-la (5 pg/ml) resulted in augmentation of IL-8 induction at KI 0.8-20 mM (58% increase at KI 4 mM, PcO.05). Similar data were obtained when substituting NaI for KI, implicating the iodide atom in these effects. This co-stimulation was absent when substituting NaCl at the same concentrations, excluding an ionic effect. Measurement of IL-lu-induced II-6 in the fibroblast cultures showed similar augmentation by KI (31% increase at KI 4mM, PcO.05). These in vitro data may explain some of the beneficial effects of KI due the ability of iodide to modulate cytokine production, recruite and activate leukocytes, induce angiogenesis, or induce acute-phase proteins.
PY - 1994/4/1
Y1 - 1994/4/1
N2 - Interleukin-8 (IL-8), a pro-inflammatory protein, has been shown by nuclear magnetic resonance (NMR) and x-ray techniques to exist as a homodimer. An IL-8 analog was chemically synthesized, with the amide nitrogen of leucine-25 methylated to selectively block formation of hydrogen bonds between monomers and thereby prevent dimerization. This analog was shown to be a monomer, as assessed by analytical ultracentrifugation and NMR. Nevertheless, it was equivalent to IL-8 in assays of neutrophil activation, which indicates that the monomer is a functional form of IL-8.
AB - Interleukin-8 (IL-8), a pro-inflammatory protein, has been shown by nuclear magnetic resonance (NMR) and x-ray techniques to exist as a homodimer. An IL-8 analog was chemically synthesized, with the amide nitrogen of leucine-25 methylated to selectively block formation of hydrogen bonds between monomers and thereby prevent dimerization. This analog was shown to be a monomer, as assessed by analytical ultracentrifugation and NMR. Nevertheless, it was equivalent to IL-8 in assays of neutrophil activation, which indicates that the monomer is a functional form of IL-8.
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U2 - 10.1126/science.8140420
DO - 10.1126/science.8140420
M3 - Article
C2 - 8140420
AN - SCOPUS:0028280059
SN - 0036-8075
VL - 264
SP - 90
EP - 92
JO - Science
JF - Science
IS - 5155
ER -