title: Modulation of cytokine production in activated human monocytes by somatostatin.
abstract: The immunosuppressor effects of the widely distributed neuropeptide somatostatin were examined on purified peripheral blood human monocytes. Somatostatin, at concentrations thought to be physiologic (10(-10)-10(-7) M), regulated monocyte/macrophage responses to (LPS) stimulation, as reflected by interleukin production. In particular, somatostatin had direct inhibitory effects on TNF-alpha, IL-1 beta, and IL-6 secretion by LPS-activated monocytes, while the decrease on IL-8 synthesis was modulated mainly by the action of somatostatin on TNF-alpha and IL-1 beta. In fact, the addition of these two inflammatory cytokines to the monocyte culture medium was able to induce IL-8 expression, as demonstrated by mRNA analysis, also in presence of the neuropeptide. Although somatostatin affected IL-8 production in an indirect way, it suppressed directly the chemotactic response of neutrophils to IL-8. Finally, somatostatin downregulation of monocyte activation was confirmed by the decrease of HLA-DR expression on cell plasma membranes (52% versus 33%). Our results confirm that somatostatin exerts preferential effects on the suppression of immunoreactions by modulating cytokine production and activity.
authors.affiliation: Institute of Protein Biochemistry and Enzymology, Naples, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Peluso
authors.forename: O
authors.initials: O
authors.lastname: Petillo
authors.forename: M A
authors.initials: MA
authors.lastname: Melone
authors.forename: G
authors.initials: G
authors.lastname: Mazzarella
authors.forename: M
authors.initials: M
authors.lastname: Ranieri
authors.forename: G F
authors.initials: GF
authors.lastname: Tajana
mesh_terms: D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006684:HLA-DR Antigens / Q000096:biosynthesis; D006801:Humans; D007165:Immunosuppression Therapy; D007375:Interleukin-1 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology; D013004:Somatostatin / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016207:Cytokines; D006684:HLA-DR Antigens; D007375:Interleukin-1; D015850:Interleukin-6; D016209:Interleukin-8; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D013004:Somatostatin