OBJECTIVETo investigate whether Candida albicans-native phospholipomannan (PLM) induce an inflammation response through Toll-like receptor(TLRé2 in human acute monocytic leukemia cell line (THP-1) cells.

METHODSHuman THP-1 monocytes were challenged with PLM in vitro. The mRNA expressions of TLR2, TLR4, proinflammatory cytokine [interleukin(IL)-6], and chemokine (IL-8) were assayed by real time reverse transcription polymerase chain reaction. The secretions of IL-6 and IL-8 were measured by enzyme-linked immunosorbent assay. The expression of TLR2 was analyzed with Western blot.

RESULTSPLM increased the mRNA expressions and secretions of proinflammatory cytokines (IL-6) and chemokines (IL-8) in THP-1 cells (all P=0.0000). PLM up-regulated the mRNA and protein levels of TLR2 (P=0.0000), whereas the mRNA level of TLR4 was not altered. PLM hydrolyzed with β-D-mannoside manno hydrolase failed to induce gene and protein expressions of TLR2, IL-6, and IL-8. Anti-TLRS-neutralizing antibody blocked the PLM-induced secretions of IL-6 and IL-8 in THP-1 cells (P = 0.0003, P = 0.0010).

CONCLUSIONCanidada albicans-native PLM may contribute to the inflammatory responses during Candida infection in a TLR2-dependent manner.

Candida albicans ; chemistry ; Cells, Cultured ; Glycolipids ; pharmacology ; Humans ; Interleukin-6 ; metabolism ; Interleukin-8 ; metabolism ; Monocytes ; drug effects ; immunology ; metabolism ; Toll-Like Receptor 2 ; metabolism ; Toll-Like Receptor 4 ; metabolism

Lipopolysaccharide (LPS) is a major component of the outer membrane of Gram-negative bacteria. Minute amounts of LPS released from infecting pathogens can initiate potent innate immune responses that prime the immune system against further infection. However, when the LPS response is not properly controlled it can lead to fatal septic shock syndrome. The common structural pattern of LPS in diverse bacterial species is recognized by a cascade of LPS receptors and accessory proteins, LPS binding protein (LBP), CD14 and the Toll-like receptor4 (TLR4)-MD-2 complex. The structures of these proteins account for how our immune system differentiates LPS molecules from structurally similar host molecules. They also provide insights useful for discovery of anti-sepsis drugs. In this review, we summarize these structures and describe the structural basis of LPS recognition by LPS receptors and accessory proteins.
Amino Acid Sequence ; Animals ; Binding Sites ; Carbohydrate Sequence ; Humans ; Immunity, Innate ; Lipopolysaccharides/*chemistry/immunology/pharmacology ; Molecular Sequence Data ; Toll-Like Receptor 4/*chemistry/immunology/metabolism

Microglial cells are the resident innate immune cells that sense pathogens and tissue injury in the central nervous system (CNS). Microglial activation is critical for neuroinflammatory responses. The synthetic compound 2-hydroxy-3',5,5'-trimethoxychalcone (DK-139) is a novel chalcone-derived compound. In this study, we investigated the effects of DK-139 on Toll-like receptor 4 (TLR4)-mediated inflammatory responses in BV2 microglial cells. DK-139 inhibited lipopolysaccharide (LPS)-induced TLR4 activity, as determined using a cell-based assay. DK-139 blocked LPS-induced phosphorylation of IkappaB and p65/RelA NF-kappaB, resulting in inhibition of the nuclear translocation and trans-acting activity of NF-kappaB in BV2 microglial cells. We also found that DK-139 reduced the expression of NF-kappaB target genes, such as those for COX-2, iNOS, and IL-1beta, in LPS-stimulated BV2 microglial cells. Interestingly, DK-139 blocked LPS-induced Akt phosphorylation. Inhibition of Akt abrogated LPS-induced phosphorylation of p65/RelA, while overexpression of dominant-active p110CAAX enhanced p65/RelA phosphorylation as well as iNOS and COX2 expression. These results suggest that DK-139 exerts an anti-inflammatory effect on microglial cells by inhibiting the Akt/IkappaB kinase (IKK)/NF-kappaB signaling pathway.
Animals ; Binding Sites ; Cell Line ; Chalcones/chemistry/*pharmacology ; Cyclooxygenase 2/metabolism ; I-kappa B Kinase/metabolism ; Inflammation/*drug therapy ; Interleukin-1beta/metabolism ; Lipopolysaccharides/immunology ; Microglia/*drug effects/immunology/metabolism ; Molecular Dynamics Simulation ; NF-kappa B/*antagonists & inhibitors ; Nitric Oxide Synthase Type II/metabolism ; Phosphorylation/drug effects ; Protein Binding ; Proto-Oncogene Proteins c-akt/*antagonists & inhibitors ; Rats ; Signal Transduction ; Toll-Like Receptor 4/*antagonists & inhibitors/metabolism ; Transcription Factor RelA/metabolism