The role of inositol lipids in the activation of monocytes by interleukin-1 and bacterial endotoxin

Transcriptome analysis provides insights into the effects of myo-inositol on the turbot Scophthalmus maximus

Myo-inositol is an essential vitamin for most animals, and it can modulate multiple physiological functions. In this study, we performed transcriptome gene expression profiling of gill tissue from turbot Scophthalmus maximus fed different concentrations of myo-inositol (0, 300, 600, 900, 1200 mg/kg). Results of expression tendency analysis, Weighted Gene Co-Expression Network Analysis (WGCNA), integrated transcriptome analyses, and KEGG annotation analysis of all differentially expressed genes (DEGs) demonstrated that the cytokine-cytokine receptor interaction played a core role in effects of myo-inositol on turbot, which was followed by the Jak-STAT signaling pathway. The results of qRT-PCR also showed myo-inositol mediated the gene expression of the cytokine-cytokine receptor interaction and the Jak-STAT signaling pathway in turbot. The ELISA assay indicated that myo-inositol affected the concentration change of interleukins (IL-2 and IL-10). Consequently, the interleukins associated with immune functions in the cytokine-cytokine receptor interaction played a core role in the effects of myo-inositol on turbot, which was followed by the Jak-STAT signaling pathway. Additionally, 10 hub genes associated with myo-inositol-traits were identified via WGCNA.

Prostaglandin and fatty acid modulation of Escherichia coli O157 phagocytosis by human monocytic cells

Phagocytosis by human monocytes is an important primary survival mechanism particularly during bacterial infection. However, the processes that control the events and mediators involved in the activation of monocytes and their impact on the phagocytosis of bacteria are poorly understood. The effect of bacterial endotoxin, interleukin-1 beta (IL-1 beta), fatty acids and prostaglandin E2 (PGE2) on the phagocytosis of fluoroscein isothiocyanate (FITC)-labelled Escherichia coli (O157) by human blood monocytes and U937 cells was studied by flow cytometry. Endotoxin increased the phagocytosis of labelled bacteria by both monocytes and U937 cells. IL-1 beta and the polyunsaturated fatty acids; dihomo-gamma-linolenic and arachidonic acids also increased the phagocytic activity of both monocytes and U937 cells. In contrast, PGE2 suppressed phagocytosis in a concentration-dependent manner. The cyclo-oxygenase inhibitor, ketoprofen, further enhanced the increased phagocytic activity in the presence of endotoxin and interleukin-1 (IL-1) indicating suppression by endogenous prostaglandins. This was confirmed by the data which showed that lipopolysaccharide (LPS) and IL-1 increased PGE2 release and ketoprofen inhibited release. Endotoxin and fatty acids increased IL-1 beta release also, whereas PGE2 inhibited release. The data suggest that phagocytic activity may be linked to changes in IL-1 levels. The data presented in this study also suggest that monocyte phagocytosis in the course of bacterial infection would be altered during pathophysiological events which result in elevation of extracellular fatty acids.

Pathways controlling the superoxide response during phagocyte differentiation: involvement of arachidonic acid and Ca2+ in the response to bacterial endotoxin

In contrast to the phorbol ester oxidative response, which only develops during dimethylsulphoxide (DMSO)-induced differentiation of the human leukemic myeloblast HL-60 cell-line, the endotoxin response was observed in undifferentiated and differentiated cells. The Ca2+ response to endotoxin, detected in both differentiated and undifferentiated HL-60 cells, consisted of a transient 10-50 nM increase in intracellular Ca2+. A very slow, irreversible increase in intracellular Ca2+ was detected at high 1-100 micrograms/ml endotoxin concentrations, and this effect, and the inositol phosphate response, correlated with the surfactant activities of various endotoxins and Lipid A. Arachidonic acid and sodium arachidonate 1-50 microM stimulated a large 200-500 nM and transient Ca2+ response in undifferentiated HL-60 cells, which was significantly greater than that elicited by 1-50 microM eicosapentaenoic acid, and was not observed at similar concentrations of arachidonic acid methyl ester or myristic acid. These concentrations (1-50 microM) of arachidonic acid were observed to have surfactant activities on the plasma membrane. At lower arachidonic acid concentrations a marked potentiation of both Ca2+ and oxidative responses to the chemotactic peptide fMet-Leu-Phe was detected. It is possible that the arachidonic acid released during phospholipase A2 activation of neutrophils may be involved in cellular cross-talk and, at higher concentrations, in directly activating Ca2+ and superoxide production. It is also possible that previously reported effects of endotoxin at high concentrations are an in vitro artefact of surfactant properties of endotoxin.