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Induction of cystine transport activity in mouse peritoneal macrophages by bacterial lipopolysaccharide.

ABSTRACT: The transport of cystine has been investigated in mouse peritoneal macrophages cultured in vitro. The transport activity for cystine was very low in freshly isolated macrophages but was potently induced during culture in the presence of bacterial lipopolysaccharide (LPS) at concentrations as low as 0.1 ng/ml. The transport activity for cystine was enhanced when the cells were incubated with tumour necrosis factor-alpha (TNF-alpha), but not with interferon-gamma (IFN-gamma) or interleukin-1. IFN-gamma was rather repressive in the induction of the activity by LPS or TNF-alpha. The transport activity for cystine induced by LPS has been characterized. Cystine was transported mainly by Na(+)-independent system and the uptake of cystine was inhibited by extracellular glutamate and homocysteate, but not by aspartate, indicating that the transport of cystine in macrophages treated with LPS is mediated by System xc-. Glutathione content of the macrophages increased when they were exposed to LPS, and this increase was, at least in part, attributable to the induced activity of the cystine transport.

SUBMITTER: Sato H

PROVIDER: S-EPMC1135929 | biostudies-other | 1995 Sep

REPOSITORIES: biostudies-other

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Project description:Chemokine (C-C motif) receptor 8 (CCR8), the chemokine receptor for chemokine (C-C motif) ligand 1 (CCL1), is expressed in T-helper type-2 lymphocytes and peritoneal macrophages (PM?) and is involved in various pathological conditions, including peritoneal adhesions. However, the role of CCR8 in inflammatory responses is not fully elucidated. To investigate the function of CCR8 in macrophages, we compared cytokine secretion from mouse PM? or bone marrow-derived macrophages (BMM?) stimulated with various Toll-like receptor (TLR) ligands in CCR8 deficient (CCR8-/-) and wild-type (WT) mice. We found that CCR8-/- PM? demonstrated attenuated secretion of tumor necrosis factor (TNF)-?, interleukin (IL)-6, and IL-10 when stimulated with lipopolysaccharide (LPS). In particular, LPS-induced IL-10 production absolutely required CCR8. CCR8-dependent cytokine secretion was characteristic of PM? but not BMM?. To further investigate this result, we selected the small molecule compound R243 from a library of compounds with CCR8-antagonistic effects on CCL1-induced Ca2+ flux and CCL1-driven PM? aggregation. Similar to CCR8-/- PM?, R243 attenuated secretion of TNF-?, IL-6, and most strikingly IL-10 from WT PM?, but not BMM?. CCR8-/- PM? and R243-treated WT PM? both showed suppressed c-jun N-terminal kinase activity and nuclear factor-?B signaling after LPS treatment when compared with WT PM?. A c-Jun signaling pathway inhibitor also produced an inhibitory effect on LPS-induced cytokine secretion that was similar to that of CCR8 deficiency or R243 treatment. As seen in CCR8-/- mice, administration of R243 attenuated peritoneal adhesions in vivo. R243 also prevented hapten-induced colitis. These results are indicative of cross talk between signaling pathways downstream of CCR8 and TLR-4 that induces cytokine production by PM?. Through use of CCR8-/- mice and the new CCR8 inhibitor, R243, we identified a novel macrophage innate immune response pathway that involves a chemokine receptor.

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Induction of cystine transport activity in mouse peritoneal macrophages by bacterial lipopolysaccharide.

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