Water-soluble chitosan inhibits the production of pro-inflammatory cytokine in human astrocytoma cells activated by amyloid beta peptide and interleukin-1beta.

A chronic inflammatory response associated with beta-amyloid (Abeta) and interleukin-1beta (IL-1beta) is responsible for the pathology of Alzheimer's disease (AD). Astrocytes are predominant neuroglial cells of the central nervous system and are actively involved in cytokine-mediated events in AD. To investigate the biological effect of water-soluble chitosan (WSC), we examined cytotoxicity, production of pro-inflammatory cytokines and inducible nitric-oxide synthase (iNOS) on human astrocytoma cell line CCF-STTG1 stimulated with IL-1beta and Abeta fragment 25-35 (Abeta[25-35]). In 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide colorimetric assay, WSC by itself had no effect on cell viability on human astrocytoma cells. The effects of WSC on tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were evaluated with enzyme-linked immunosorbent assay and Western blotting. The production of TNF-alpha and IL-6 was induced by IL-1beta and Abeta[25-35] and synergistically amplified by the co-stimulation of IL-1beta and Abeta[25-35]. The secretion and expression of pro-inflammatory cytokines, TNF-alpha and IL-6, was significantly inhibited by pretreatment with WSC in human astrocytoma cells. The expression of iNOS was induced by IL-1beta and Abeta[25-35] and was partially inhibited by treatment with WSC. We demonstrate the regulatory effects of WSC in human astrocytes for the first time and suggest the anti-inflammatory effect of WSC may reduce and delay AD pathologic events.