Altered composition of urinary heparan sulfate in patients with COPD

In patients with emphysema the integrity of the extracellular matrix (connective tissue skeleton) is compromised. In this study we analyzed glycosaminoglycans, which are main constituents of this matrix, in urines from patients with chronic obstructive pulmonary disease (COPD)/emphysema. Glycosaminoglycans (GAGs) were purified by anion exchange chromatography and quantified using the 1,9-dimethylmethylene blue assay. Heparan sulfate (HS) was assayed using three different chemical methods: digestion with heparitinase or with nitrous acid and by use of an adapted 1,9-dimethylmethylene blue assay. A specific epitope on the HS molecule, defined by the monoclonal antibody JM403, was determined using an inhibition enzyme immunoassay. In patients with COPD total urinary glycosaminoglycan and HS content were not altered. The JM403 epitope of HS, however, was greatly decreased in patients (0.6 versus 4.1 units/mg creatinine for control subjects, p < 0.0001). A similar pattern was observed when patients with bronchial carcinoma with and without emphysema were compared (0.4 versus 2.4 units/mg creatinine respectively, p < 0.0005). Patients with sarcoidosis did not show a decreased epitope content. These results indicate a structural change or an altered processing of the HS molecule in patients with emphysema. Taking into consideration the importance of HS for the stability of the alveolar extracellular matrix, this change may be associated with the pathogenesis of emphysema.