Features and functions of human microglia cells.
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Humans↗
Biomedical subjects
T Persichini
Publications and source records attributed to T Persichini.
Modulation of the alpha 2 macroglobulin receptor/low density lipoprotein receptor related protein by interferon-gamma in human astroglial cells.
Alpha 2 macroglobulin receptor/low density lipoprotein receptor-related protein (alpha 2 Mr/LRP) is a multi-functional cell surface receptor that has been implicated in important processes, such as atherogenesis, cellular migration, immune response and degenerative diseases. Its expression increases in human brain during Alzheimer's disease, tissue injury and neoplastic transformation. In the present paper we studied the regulation of alpha 2 Mr expression by interferon-gamma (IFN gamma) in human astrocytoma cell lines and in fetal astrocytes. Western blots demonstrated an increase of the alpha 2 Mr expression after 24 h of IFN gamma treatment. This effect paralleled the up-regulation of alpha 2 Mr mRNA, as detected by PCR. By prolonging incubation with IFN gamma, we observed a decrement of alpha 2 Mr in IFN gamma treated cells, both by western blot and cytometric analysis. Since in the same cells IFN gamma also up-regulates alpha 2 macroglobulin, this effect may be due to an augmented degradation of the receptor during its recycling.
Antibodies, Monoclonal↗
Human ramified microglial cells produce nitric oxide upon Escherichia coli lipopolysaccharide and tumor necrosis factor alpha stimulation.
This study shows that human ramified microglial cells derived from fetal brain primary cultures, are able to produce nitric oxide (NO). In fact, stimulation with Escherichia coli lipopolysaccharide (LPS) (1 microgram ml-1) or tumor necrosis factor alpha (TNF alpha) (500 U ml-1) enhances nitrite release in cell supernatants, as determined by the Griess reaction. A synergistic effect is achieved following treatment with LPS plus TNF alpha, this effect being inhibited by pretreating cells with NOS inhibitor N omega-nitro-L-arginine methyl ester (L-NAME). Using reverse transcriptase-polymerase chain reaction (RT-PCR) and Southern blot analysis, we also found that LPS/TNF alpha produce an increase of inducible NO synthase (iNOS) mRNA expression.
Base Sequence↗
Induction of nitric oxide synthase mRNA expression. Suppression by exogenous nitric oxide.
The reactive nitrogen species, nitric oxide (NO), plays an important role in the pathogenesis of neurodegenerative diseases. The suppression of NO production may be fundamental for survival of neurons. Here, we report that pretreatment of human ramified microglial cells with nearly physiological levels of exogenous NO prevents lipopolysaccharide (LPS)/tumor necrosis factor alpha (TNF alpha)-inducible NO synthesis, because by affecting NF-kappa B activation it inhibits inducible Ca(2+)-independent NO synthase isoform (iNOS) mRNA expression. Using reverse transcriptase polymerase chain reaction, we have found that both NO donor sodium nitroprusside (SNP) and authentic NO solution are able to inhibit LPS/TNF alpha-inducible iNOS gene expression; this effect was reversed by reduced hemoglobin, a trapping agent for NO. The early presence of SNP during LPS/TNF alpha induction is essential for inhibition of iNOS mRNA expression. Furthermore, SNP is capable of inhibiting LPS/TNF alpha-inducible nitrite release, as determined by Griess reaction. Finally, using electrophoretic mobility shift assay, we have shown that SNP inhibits LPS/TNF alpha-elicited NF-kappa B activation. This suggests that inhibition of iNOS gene expression by exogenous NO may be ascribed to a decreased NF-kappa B availability.
Base Sequence↗
Inhibition of inducible nitric oxide synthase mRNA expression by basic fibroblast growth factor in human microglial cells.
The effect of basic fibroblast growth factor (bFGF) on inducible nitric oxide synthase (iNOS) mRNA expression in human cultured ramified microglial cells was investigated. Using RT-PCR and Southern blot analysis, we found that bFGF prevented the iNOS gene expression as induced by LPS/TNF alpha. Also, bFGF dose-dependently inhibited nitrite levels in treated cell supernatants. That the early presence of bFGF during LPS/TNF alpha induction was essential indicates that iNOS gene expression can be transcriptionally regulated.
Blotting, Southern↗
NMDA-dependent NGF mRNA expression by human astrocytoma cells is mediated by nitric oxide.
The aim of this study was to investigate the role of NO-cGMP pathway in NMDA-induced NGF mRNA expression by T67 astrocytoma cells. Levels of nitrite, a breakdown product of NO, in supernatants of NMDA-treated astrocytoma cells were significantly higher compared with control cells, this effect being reversed by the specific NO synthase inhibitor L-NAME. Furthermore, NGF mRNA expression was induced by NMDA treatment, this effect being inhibited by pretreating cells with L-NAME. Moreover, methylene blue, an inhibitor of NO biological activity at guanylate cyclase level, inhibited NMDA-induced NGF mRNA expression and this effect was reversed by dbt2-cGMP. These findings suggest that NO-cGMP pathway mediates the synthesis of NGF mRNA.
Astrocytoma↗
Interferon gamma up-regulates alpha 2 macroglobulin expression in human astrocytoma cells.
An established human astrocytoma cell line (T67) was shown to constitutively produce the proteinase inhibitor alpha 2 macroglobulin (alpha 2M). Interferon gamma (IFN gamma), a potent immunoregulatory lymphokine, was able to increase the synthesis of alpha 2M by these cells, as measured by ELISA on cell supernatants. The alpha 2M induction was also observed in other human glioma cell lines (T70 and ADF) and in human fetal astrocyte cultures following IFN gamma treatment. In T67 cells this effect was dose-dependent and the maximum (2.7-fold increase) was obtained with 2000 U/ml of IFN gamma. A corresponding enhanced alpha 2M mRNA accumulation was demonstrated by PCR and Northern blot techniques. Our results suggest an important role of alpha 2M during inflammatory and immune processes in the CNS. An increased release of alpha 2M following IFN gamma stimulation may allow the removal of the bulk of proteases released at the site of inflammation, strengthening at the same time the antigen presentation processes.
Astrocytoma↗
HIV gp120 glycoprotein stimulates the inducible isoform of no synthase in human cultured astrocytoma cells.
The effect of the HIV coating glycoprotein gp 120 on the generation of NO by human cultured T67 astrocytoma cells was investigated. Preincubation of astrocytoma cells with gp 120 (10 pM, 100 and 500 nM) produced a significant, dose-dependent increase of nitrite levels in supernatant of pretreated cells which was higher when compared to untreated cells. This effect was prevented by coincubation of cells with monoclonal antibodies directed against gp 120, or by pretreatment of cells with the selective NO synthase inhibitor L-NAME (100 microM). The rise of nitrite following pretreatment of astrocytoma cells with gp 120 was accompanied by an increase in NO synthase activity which was mainly Ca(++)-independent. Also this effect was inhibited by antibodies against gp 120, showing the specificity of the activation of the L-Arg-NO pathway subsequent to incubation of astrocytoma cells with the HIV coating protein. In conclusion, the present results are consistent with an activation of the inducible, Ca(++)-independent isoform of NO synthase in cultured astrocytoma cells following coincubation with gp 120. This may contribute to explain some of the neuropathological changes accompanying HIV-related cognitive disorders.
Amino Acid Oxidoreductases↗