TY - JOUR
T1 - Regulation of interleukin-8 binding and function by heparin and alpha2-macroglobulin
AU - Ramdin, L.
AU - Perks, B.
AU - Sheron, N.
AU - Shute, Jan
PY - 1998/5
Y1 - 1998/5
N2 - Background
Increased expression of interleukin-8 (IL-8), a potent neutrophil chemoattractant, is associated with a number of inflammatory diseases. Interleukin-8 binds to the glycosaminoglycan (GAG) heparin and the protease inhibitor α2-macroglobulin, molecules which regulate the function of a number of cytokines. Heparan sulphate was previously shown to enhance neutrophil chemotactic responses to IL-8.
Objective
The purpose of this study was to investigate the effect of heparin, heparan sulphate and α2-macroglobulin on IL-8 binding to neutrophils and subsequent functional effects in vitro.
Methods
The binding of 125I-IL-8 to normal neutrophils at 4 °C was studied and the IL-8 induced neutrophil chemotactic response was investigated using micro-Boyden chambers. Complexation of IL-8 with α2-macroglobulin was confirmed using gel filtration chromatography.
Results
Heparin, but not heparan sulphate, inhibited the binding of 125I-IL-8 to neutrophils (IC50 = 26 μg/mL) and IL-8 induced neutrophil chemotactic responses (IC50 = 4 μg/mL). The specific inhibitory effect of heparin was apparently due to an interaction with IL-8 which was charge-dependent, since dextran sulphate had a greater inhibitory effect on chemotactic responses (IC50 = 2 μg/mL) and FITC-heparin did not bind to neutrophils. The heparin-induced inhibition of IL-8 binding and chemotactic responses was reversed in a dose-dependent manner in the presence of α2-macroglobulin. The binding of 125I-IL-8 to neutrophils in the presence of α2-macroglobulin appears to be, in part, through the specific IL-8 receptor.
Conclusion
These results point to an anti-inflammatory role for heparin and a novel, potentially, pro-inflammatory role for α2-macroglobulin which together indicate the importance of cytokine-binding macromolecules in determining net cytokine function.
AB - Background
Increased expression of interleukin-8 (IL-8), a potent neutrophil chemoattractant, is associated with a number of inflammatory diseases. Interleukin-8 binds to the glycosaminoglycan (GAG) heparin and the protease inhibitor α2-macroglobulin, molecules which regulate the function of a number of cytokines. Heparan sulphate was previously shown to enhance neutrophil chemotactic responses to IL-8.
Objective
The purpose of this study was to investigate the effect of heparin, heparan sulphate and α2-macroglobulin on IL-8 binding to neutrophils and subsequent functional effects in vitro.
Methods
The binding of 125I-IL-8 to normal neutrophils at 4 °C was studied and the IL-8 induced neutrophil chemotactic response was investigated using micro-Boyden chambers. Complexation of IL-8 with α2-macroglobulin was confirmed using gel filtration chromatography.
Results
Heparin, but not heparan sulphate, inhibited the binding of 125I-IL-8 to neutrophils (IC50 = 26 μg/mL) and IL-8 induced neutrophil chemotactic responses (IC50 = 4 μg/mL). The specific inhibitory effect of heparin was apparently due to an interaction with IL-8 which was charge-dependent, since dextran sulphate had a greater inhibitory effect on chemotactic responses (IC50 = 2 μg/mL) and FITC-heparin did not bind to neutrophils. The heparin-induced inhibition of IL-8 binding and chemotactic responses was reversed in a dose-dependent manner in the presence of α2-macroglobulin. The binding of 125I-IL-8 to neutrophils in the presence of α2-macroglobulin appears to be, in part, through the specific IL-8 receptor.
Conclusion
These results point to an anti-inflammatory role for heparin and a novel, potentially, pro-inflammatory role for α2-macroglobulin which together indicate the importance of cytokine-binding macromolecules in determining net cytokine function.
U2 - 10.1046/j.1365-2222.1998.00283.x
DO - 10.1046/j.1365-2222.1998.00283.x
M3 - Article
SN - 0954-7894
VL - 28
SP - 616
EP - 624
JO - Clinical & Experimental Allergy
JF - Clinical & Experimental Allergy
IS - 5
ER -