Project description:Leukotriene B4 (LTB4) is a potent lipid mediator of inflammation, implicated in numerous diseases including atherosclerosis. We have used primary human monocytes, which express both receptors, to analyze transcriptional responses to LTB4. Comparisons were made between LTB4- and vehicle-treated samples at the same time point. The analysis showed that expression of 72 genes was upregulated at least two-fold at two time points. These genes include multiple chemokines as well as some genes with unknown function. Keywords: time course
Project description:Eicosanoids are potent regulators of gene expression of inflammatory cells. Pro- (leukotrienes B4 and C4) and anti-indflammatory (lipoxins A4 and B4) eicosanoids have been described in the literature but the detailed impact of these lipid mediators on the gene expression pattern of monocytic cells has not been studied in detail. We cultured the permanent monocytic cell line MonoMac 6 for 12 h in the absence (solvent control) and presence of these eicosanoids and quantified the differential gene expression patterns using the microarray technology. Experiment Overall Design: MonoMac6 cells were grown according to the recommendations of the German Tissue and Cell Culture Collection (Braunschweig) to near confluency. Then 100 nM of the eicosanoids (leukotriene B4, leukotriene C4, lipoxin A4, lipoxin B4) were added to the culture medium as DMSO stock solution and the cells were further cultured for 12 h with the stimuli. Then the cells were harvested, washed and total RNA was extracted according to the Qiagen protocol. Total RNA was used for microarray hybridization.
Project description:Background: Cysteinyl leukotrienes (cysLTs) are important mediators of innate immune responsiveness and chronic inflammatory diseases. CysLTs acting through cysteinyl leukotriene receptors may influence the migration and activity of cells such as eosinophils, monocytes and dendritic cells. Objective: To determine the gene expression signature of human monocytes in response to cysLTs and to elucidate the signaling pathways involved in monocyte activation. Methods: Gene expression was analyzed using oligonucleotide microarrays. Responsiveness to cysLTs was assessed by real-time PCR, calcium flux, kinase activation and chemotaxis assays. Results: Cysteinyl leukotriene type I receptor (CysLTR1) transcript 1 is predominantly expressed in human monocytes and cysLTs signal through CysLTR1 in these cells. Several immediate-early genes, including early growth response (Egr) -2, 3, FosB, activating transcription factor 3 and nuclear receptor subfamily 4 were significantly induced by LTD4. This effect was mediated by CysLTR1 coupled to Gαi/o, activation of phospholipase C, and inositol-1,4,5-triphosphate (IP3) and store operated calcium channels. LTD4 induced p38 MAP kinase phosphorylation, a pathway also involved in the regulation of immediate-early genes expression in monocytes. LTD4 stimulated monocyte chemotactic activity that was fully blocked by a selective CysLTR1 inhibitor MK571 and pertussis toxin, suggesting that CysLTR1 coupled to Gαi/o is a dominant functional pathway in human monocytes. Conclusion: Our data show that cysLTs acting through CysLTR1 can significantly influence the activation and migration of human monocytes and that these effects can be fully inhibited by CysLTR1 antagonists. Clinical implications: Antileukotriene therapies are likely to significantly block the proinflammatory functions of human monocytes. Experiment Overall Design: 4 control sample, 4 LTD4 stimulated samples
Project description:Gliotoxin (GT), a major secondary metabolite and virulence factor of Aspergillus fumigatus, suppresses innate immunity and supports the evasion of host immune responses. Recently, we revealed that GT blocks leukotriene (LT)B4 formation by directly inhibiting LTA4 hydrolase (LTA4H) in activated human neutrophils and monocytes. Here, we elucidated the impact of GT on LTB4 biosynthesis and the complex lipid mediator network in human M1- and M2-like monocyte-derived macrophage (MDM) subtypes and studied the respective consequences for innate immune cell functions. Notably, in resting MDMs, GT elicited prostaglandin and 12/15-lipoxygenase product formation, although less efficient than bacterial exotoxins. In activated MDM, LTB4 formation was effectively suppressed by GT, connected to impaired macrophage phagocytic activity, and detrimental consequences for neutrophil movement and migration. Conclusively, GT impairs functions of activated innate immune cells through suppression of LTB4 formation, while GT may prime the immune system by provoking prostaglandin formation and 12/15-lipoxygenase-derived LM.
Project description:total RNA from mouse (male c57BL/6) spleen labeled with Cy3 vs total RNA from mouse (male c57BL/6) B cells treated with Leukotriene B4 (LTB4) labeled with Cy5- time course with repeats Keywords: ordered
Project description:Background: Cysteinyl leukotrienes (cysLTs) are important mediators of innate immune responsiveness and chronic inflammatory diseases. CysLTs acting through cysteinyl leukotriene receptors may influence the migration and activity of cells such as eosinophils, monocytes and dendritic cells. Objective: To determine the gene expression signature of human monocytes in response to cysLTs and to elucidate the signaling pathways involved in monocyte activation. Methods: Gene expression was analyzed using oligonucleotide microarrays. Responsiveness to cysLTs was assessed by real-time PCR, calcium flux, kinase activation and chemotaxis assays. Results: Cysteinyl leukotriene type I receptor (CysLTR1) transcript 1 is predominantly expressed in human monocytes and cysLTs signal through CysLTR1 in these cells. Several immediate-early genes, including early growth response (Egr) -2, 3, FosB, activating transcription factor 3 and nuclear receptor subfamily 4 were significantly induced by LTD4. This effect was mediated by CysLTR1 coupled to Gαi/o, activation of phospholipase C, and inositol-1,4,5-triphosphate (IP3) and store operated calcium channels. LTD4 induced p38 MAP kinase phosphorylation, a pathway also involved in the regulation of immediate-early genes expression in monocytes. LTD4 stimulated monocyte chemotactic activity that was fully blocked by a selective CysLTR1 inhibitor MK571 and pertussis toxin, suggesting that CysLTR1 coupled to Gαi/o is a dominant functional pathway in human monocytes. Conclusion: Our data show that cysLTs acting through CysLTR1 can significantly influence the activation and migration of human monocytes and that these effects can be fully inhibited by CysLTR1 antagonists. Clinical implications: Antileukotriene therapies are likely to significantly block the proinflammatory functions of human monocytes. Keywords: monocytes stimulated with LTD4