Serum hyaluronan levels follow disease activity in vasculitis

Hyaluronan (HA) is a high molecular weight polysaccharide present in the extracellular matrix of most tissues. It is a major component of loose connective tissues such as skin, synovial fluid and the vitreous body, and during embryonic development, tissue repair, tumor growth and at inflammatory sites. Increased serum concentrations have been reported in association with tissue damage, certain inflammatory diseases, notably rheumatoid arthritis and scleroderma, liver malfunction and in some malignancies. Currently there are no serological markers available that monitor the extent of tissue damage in vasculitis. We therefore, conducted this study to investigate the significance of serum HA in patient with systemic vasculitis (SV). Ten patients with SV and acute renal failure had elevated HA levels compared to normal age and gender matched controls (n = 31) (mean +/- SD: 673.8 +/- 495.14 micrograms/l and 90.26 +/- 37.18 micrograms/l, respectively; p < 0.001]. Eight of these patients were studied longitudinally for ten days, after pulse steroids, during which serum HA levels fell paralleling clinical improvement, despite the persistence of positive perinuclear-anti-neutrophil cytoplasmic antibody (p-ANCA) serology in three patients. In two patients, the clinical course was complicated by sepsis which was accompanied by an acute rise in serum HA. One patient suffered a relapse of vasculitis, with lung hemorrhage and a sudden rise in HA (> 2,000 micrograms/l), but c-ANCA serology remained normal. Serum HA was also measured in a further ten patients in clinical remission from SV and found to be within the normal range (82.44 +/- 39.06 micrograms/l). One patient, with equivocal clinical relapse after transplantation, exhibited high p-ANCA (404 IU) but serum HA remained normal (ten readings over six months 0-163 micrograms/l). Little change was seen in symptoms, or HA and ANCA serology, following plasma exchange. These preliminary data indicate that serum HA is raised in active vasculitis and may be a useful adjunctive marker of disease activity and extent of tissue damage.