Heparan sulphate (HS) binds and regulates the distribution and activity of a number of growth factors and chemokines, including interleukin-8 (1L-8). IL-8 is a primary stimulus for neutrophil recruitment in the CF airways, and in its active form is bound by HS-containing proteoglycans of the endothelial glycocalyx and presented to circulating neutrophils. However, neutrophils are a source of proteoglycan-degrading enzymes including neutrophil elastase and heparanase. that cleave HS and solubilise IL-8, potentially limiting further transendothelial migration. The aim of this study was therefore to investigate whether there was evidence of increased expression of HS, and''or its degradation in CF tissues. Airway tissue samples were obtained from CF patients at transplant (n=6), fixed in ethanol and processed into paraffin blocks. Normal tissue (n=6) was obtained post-mortem. Immuno-histochemical staining as carried out on 4um sections. HS in intact and cleaved forms were stained using monoclonal antibodies from AMS Biotechnology, IL8 w-as stained using a monoclonal antibody from Bender Medsystems. Strong immunostaining for intact HS was detected in endothelial and epithelial basement membranes in ail CF tissues, and also in smooth muscle bundles. IL-8 was abundant in the epithelium, endothelium and in inflammatory cells in CF. and was detected in the epithelium, but not endothelium, in normal tissue. In parallel with the increased expression of IL-8, semi-quantitative analysis showed that HS was significantly more abundant in CF than normal tissue. The cleaved form of HS was not detected in normal tissue, but was detected in CF basement membranes and in inflammatory cells in 5-'6 samples, as ell as in smooth muscle bundles 14-6). and was significantly more abundant in CF tissue than normal. The results suggest that increased expression of HS supports the continued IL-8 dependent recruitment of neutrophils in CF. Evidence of proteoglycan cleavage in the most inflamed tissue suggests activation of growth factors involved in tissue repair that may have important consequences, such as smooth muscle hypertrophv in CF.
|Issue number||SUPPL. 1|
|Publication status||Published - 1 Dec 2001|