Expression of GM-CSF receptor and "in vitro" effects of GM-CSF on human fibroblasts.
In the present study the effects of Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) on fibroblast growth and activity have been studied. In this regard the AA have evaluated in primary cultures of human gengival normal fibroblasts (PG1 cells): a)-the expression of GM-CSF receptor (GM-CSFR) (alfa unit) on the cell surface; b)-the in vitro effects of different doses of GM-CSF on the GM-CSFR expression and on the proliferation and activity of fibroblasts. PG1 cells have been stimulated in vitro with different concentrations of GM-CSF (10, 50, 80, 100 and 150 ng/ml) using promonocytic cell line U937 as positive control for GM-CSFR expression. GM-CSFR was investigated by flow cytometry, with mouse monoclonal antibody (mAb) against the alfa chain of the human GM-CSFR and fluorescein-conjugated goat antimouse immunoglobulin G (IgG). At high GM-CSF concentration (80 ng/ml) the AA observed: 1)-A marked increase of GM-CSFR expression evaluated as fluorescence intensity (about three fold in respect to the controls); 2)-Maximal increase of PG1 cells proliferation. Moreover immunofluorescence on fibroblasts obtained from culture plates showed increased actin stress fibers and fibronectin production with low stimulation by GM-CSF, while higher concentration of this cytokine determined increased proliferation of cells, but a decreased formation of actine fibers and vinculin plaques. These results demonstrate: 1)-The presence of GM-CSFR on the surface of fibroblasts; 2)-The proliferation and the synthesis activity of these cells (in vitro) are modulated by different concentration of GM-CSF. We hypothesize that GM-CSF until 80 ng/ml can upregulate the expression of the receptor. Therefore, on the basis of previous findings of high serum levels of GM-CSF in course of scleroderma, a disease characterized by fibroblast hyperactivity, a possible role of this cytokine in the pathogenic process of this disease can be hypothesized.
Dip. di Biologia e Patologia Molecolare e Cellulare, Università degli Studi Federico II, Naples, Italy.
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Montagnani
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Vallefuoco
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Rossi
D000818:Animals; D000911:Antibodies, Monoclonal; D002455:Cell Division / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D005881:Gingiva / Q000166:cytology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000378:metabolism; D015854:Up-Regulation; D016596:Vinculin / Q000378:metabolism
D000911:Antibodies, Monoclonal; D005353:Fibronectins; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D011994:Recombinant Proteins; D016596:Vinculin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor