Serum hyaluronate as a marker for disease severity in the Lactobacillus casei model of arthritis in the rat.

Serum concentrations of hyaluronate may provide a clinically relevant, quantitative marker of disease in patients with active rheumatoid arthritis (RA). We studied the utility of serum hyaluronate in an animal model, with features reminiscent of human RA, in which LEW/N female rats were made arthritic by intraperitoneal injection of sonicated Lactobacillus casei. When serum hyaluronate was measured by an inhibition ELISA, a dose dependent correlation was found between the amount of L. casei injected and both joint score and serum hyaluronate in the chronic phase of the disease. A linear correlation between the chronic phase joint score and serum hyaluronate was observed (r = 0.69, p less than 0.001). Two orally administered compounds, flurbiprofen (20 mg/kg) and methotrexate (0.125 mg/kg), were effective in decreasing both variables. Thus, serum hyaluronate may have utility in evaluating the therapeutic efficacy of antirheumatic/antiinflammatory agents in vivo in the chronic phase of RA-like diseases.