β-glucan derived from zymosan acts as an adjuvant for collagen-induced arthritis

Abstract

Collagen-induced arthritis (CIA) is an experimental model of rheumatoid arthritis (RA) and has helped researchers to analyze the pathogenesis of inflammatory joint disease. In classical CIA, Freund's complete adjuvant (FCA), which contains heat-killed Mycobacterium tuberculosis, is used as an adjuvant. In our previous study, we reported that particles of β-glucan, OX-CA, derived from Candida albicans, acted as a proper adjuvant in the CIA model. In this study, to establish pure β-glucan as an adjuvant for CIA, we tested a commercially available preparation of Zymosan A (ZYM) and modified its products. β-Glucan fractions of ZYM were prepared by oxidation with various concentrations of NaClO. The oxidized ZYM (OX-ZYM) was mainly composed of β-glucan. In this study, we examined its effect as an adjuvant for CIA. DBA/1 mice injected with CII and OX-CA developed arthritis 7-10 days after receiving booster injections; the OX-ZYM fractions induced arthritis with the same time course. 0.01% OX-ZYM (oxidized with a 0.01% NaClO solution) caused arthritis faster than 0.1% OX-ZYM or 0.5% OX-ZYM. In conclusion, β-glucan derived from ZYM by brief oxidation with NaClO is a suitable adjuvant for a CIA model with anti-CII antibody production.