Candida soluble cell wall beta-D-glucan induces lung inflammation in mice

Bioactivity of cell wall component(s) of fungi has not been fully elucidated, especially in vivo. We isolated Candida soluble beta-D-glucan (CSBG) from Candida albicans (C. albicans). We investigated the effects of airway exposure to CSBG on the immune systems in the airways in mice. CSBG exposure induced neutrophilic and eosinophilic inflammation in the lung, which was concomitant with the increased local expression of proinflammatory cytokines including tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, macrophage inflammatory protein -1alpha, macrophage chemoattractant protein -1, RANTES (regulated on activation and normal T cells expressed and secreted), and eotaxin. The lung inflammation with enhanced expression of proinflammatory proteins caused by CSBG was directly related to its structure, since structurally degraded products of CSBG by formic acid induced negligible responses in the lung. CSBG enhanced nuclear localization of phosphorylated signal transducer and activator of transcription (STAT)-6 in the lung. These results suggest that airway exposure to CSBG induces lung inflammation, at least partly, via the enhanced expression of proinflammatory cytokines and the activation of STAT-6 pathway, and can be a proper murine model for fungal lung inflammation.