Human macrophages release higher IL-1ra over IL-1beta when stimulated by block acetylated chitosan microparticles and not by random acetylated chitosans or water-soluble oligomers

Human macrophages were previously shown to release excess IL-1ra over IL-1β when stimulated by chitosan microparticles (140 kDa, 80% glucosamine and 20% block N-acetyl glucosamine, 80% degree of deacetylation (DDA)). These data suggest the potential of using chitosan to treat knee joint inflammation by guiding the in situ release of immunomodulatory cytokines. The purpose of this study was to identify the minimal chitosan motif required to induce higher IL-1ra release, using a U937 human macrophage model and a novel chitosan library with distinct DDA, acetylation patterns, and array of 5 different number-average molecular weights (Mn).