Inhibition of LPS-induced NF kappa B activation by a glucan ligand involves down-regulation of IKK beta kinase activity and altered phosphorylation and degradation of I kappa B alpha

Growing evidence supports the role of transcription factor activation in th e pathophysiology of inflammatory disorders, sepsis, ARDS, SIRS, and shock. Kinase mediated phosphorylation of I kappa B alpha is a crucial step in th e NF kappa B activation pathway. We investigated I kappa B alpha phosphoryl ation in murine liver and lung extracts after cecal ligation and puncture ( CLP) in the presence and absence of a glucan ligand. ICR mice were subjecte d to CLP. Unoperated and sham-operated mice served as the controls. Glucan phosphate (50 mg/kg) was administered 1 h before or 15 min after CLP. CLP i ncreased hepatic and pulmonary levels of phospho-I kappa B alpha by 48-192% . Pre- or post-treatment with glucan phosphate decreased (P < 0.05) tissue phospho-I kappa B alpha levels in CLP mice. Phospho-I kappa B alpha in the glucan-CLP group were not significantly different from the unoperated contr ols. To investigate mechanisms we examined IKK beta kinase activity, I kapp a B alpha phosphorylation and degradation, and NF kappa B activity in a mur ine macrophage cell line, J774a.1, treated with LPS (1 mu g/mL) and/or gluc an phosphate (1 mu g/mL) for up to 120 min. The glucan ligand blunted LPS-i nduced IKK beta kinase activity, phosphorylation and degradation of I kappa B alpha, and NF kappa B nuclear binding activity. The data indicate that o ne mechanism by which (1-->3)-beta-D-glucan may alter the response to endot oxin or polymicrobial sepsis involves modulation of IKK beta kinase activit y with subsequent decreases in IKB alpha phosphorylation and NF kappa B act ivation.