cytochalasin-d and laminaran

The main cytokine induced by the interaction of oral epithelial cells with C. glabrata is granulocyte monocyte colony-stimulating factor (GM-CSF); however, the mechanisms regulating this response are unknown. Based on previously published information on the interactions of C. albicans with oral epithelial cells, we hypothesized that interaction with viable C. glabrata triggers GM-CSF synthesis via NF-kappaB activation. We found that C. glabrata-induced GM-CSF synthesis was adhesion-dependent, enhanced by endocytosis, and required fungal viability. NF-kappaB activation was noted during interaction of epithelial cells with C. glabrata, and pre-treatment with an NF-kappaB inhibitor partly inhibited GM-CSF synthesis. Blocking TLR4 with anti-TLR4 antibody did not inhibit GM-CSF production. In contrast, an anti-CDw17 antibody triggered significant inhibition of NF-kappaB activation and GM-CSF synthesis. beta-glucans did not stimulate GM-CSF synthesis, suggesting that the CDw17/NF-kappaB/GM-CSF pathway may be beta-glucan-independent. This study provides new insights into the mechanism of GM-CSF induction by C. glabrata.

Topics: Antibodies; Antigens, CD; beta-Glucans; Candida glabrata; Cell Line; Cell Line, Tumor; Cytochalasin D; Endocytosis; Epithelial Cells; Glucans; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Lactosylceramides; Mouth Mucosa; NF-kappa B; Nucleic Acid Synthesis Inhibitors; Polysaccharides; Polysaccharides, Bacterial; Toll-Like Receptor 4; Zymosan

Previous studies showed that mouse spleen cells produced IL-12, TNF-alpha, and IFN-gamma when stimulated with phagocytosable-size chitin particles (N-acetyl-D-glucosamine polymers). To dissect the mechanisms of the cytokine production in this study, spleen cells from BALB/c mice were cultured with 1 to 10 microm chitin particles, heat-killed Corynebacterium parvum vaccine, zymosan, and mannan (a mannose polymer)-coated latex beads (1 microm) at 1, 10, or 100 microg/ml. We found that these particles induced IL-12, TNF-alpha, and IFN-gamma. However, these cytokines were not produced when spleen cells were cultured with soluble chitin, mannan, or laminarin (a polymer of beta-glucan), 1 to 10 microm beta-glucan particles, laminarin-coated latex beads, 1 microm latex beads, 50 to 100 microm chitin particles, or 50 to 100 microm mannan-coated beads. Soluble mannan, but not soluble laminarin, inhibited cytokine production following stimulation with 1 to 10 microm chitin particles, zymosan, or heat-killed C. parvum. In addition, cytochalasin D also inhibited cytokine production. The treatments with soluble mannan or with cytochalasin D, in sharp contrast, did not inhibit LPS-induced IL-12/IFN-gamma production or exogenous IL-12-induced IFN-gamma production. Finally, spleen cells from C3H/HeJ mice also showed comparable levels of IL-12/TNF-alpha/IFN-gamma production when induced by 1 to 10 microm chitin particles. Taken together, our results indicate that mannose receptor-mediated phagocytosis, but not the receptor-mediated pinocytosis, is highly associated with the production of IFN-gamma-inducing extracellular signaling factors such as IL-12 and TNF-alpha. The novel mechanism of phagocytosis-dependent IL-12 production appears to be distinct from that of LPS-induced cytokine production.

Topics: Actins; Animals; Chitin; Cytochalasin D; Female; Gene Expression Regulation; Glucans; Immunity, Cellular; Interferon-gamma; Interleukin-12; Lectins, C-Type; Lymphocyte Activation; Lymphocyte Subsets; Macrophages; Mannans; Mannose Receptor; Mannose-Binding Lectins; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Microspheres; Phagocytosis; Pinocytosis; Polysaccharides; Receptors, Cell Surface; Solubility; Spleen; Tumor Necrosis Factor-alpha; Zymosan