title: Staphylococcus aureus and lipopolysaccharide induce homologous tolerance but heterologous priming: role of interferon-gamma.
abstract: Lipopolysaccharide (LPS), the gram-negative bacterial cell wall component, induces tolerance to a secondary challenge of LPS in macrophages (Mphi) as evidenced by reduced inflammatory mediator production. However, it is uncertain if heat-killed (HK) gram-positive bacteria Staphylococcus aureus (Sa) can induce a similar tolerance and alter responses to LPS. We hypothesized that HKSa induces homologous tolerance and cross tolerance to LPS stimulation in human promonocytic THP-1 cells. We measured TNF-alpha, TxB2, and IFN-gamma production and the phosphorylation of p38, JNK, and ERK-1/2 in human promonocytic THP-1 cells. HKSa (10 microg/mL) significantly stimulated naive (nonpretreated) cell TNF-alpha (P<0.05) and TxB2 production (P<0.05). However, HKSa-pretreated cells challenged secondarily with HKSa (10 microg/mL) exhibited a decrease in the production of TNF-alpha (89 +/- 5%, P<0.05) and TxB2 (85 +/- 3%, P<0.05) compared with HKSa-stimulated naive cells. By contrast, secondary LPS challenge of HKSa-pretreated cells augmented TNF-alpha (41 +/- 3%, P<0.05) and TxB2 (42 +/- 6%, P<0.05) compared with LPS-stimulated naive cells. In naive cells, HKSa and LPS stimulation also significantly phosphorylated the mitogen-activated kinases (MAPKs) p38, JNK, and ERK-1/2 (P<0.005) compared with basal levels. HKSa and LPS induced homologous tolerance as evidenced by the down-regulation of the three MAPK (P<0.05), thus paralleling data on mediator production. HKSa-pretreated cells' priming responses to LPS correlated with augmented phosphorylation of JNK and p38 (P<0.05), whereas ERK-1/2 phosphorylation remained down-regulated. In contrast to TNF-alpha and TxB2 production, HKSa-induced IFN-gamma was up-regulated (26 +/- 5%) in HKSa-pretreated cells compared with HKSa-stimulated naive cells. IFN-gamma antibody exhibited reversed priming in HKSa-pretreated cells as evidenced by a reduction in TNF-alpha. Exogenous human IFN-gamma- (1 microg/mL) and HKSa-pretreated cells secondarily stimulated with HKSa did not prevent the induction of tolerance. In contrast, exogenous IFN-gamma pretreatment prevented the induction of LPS homologous tolerance resulting in an increase in TNF-alpha production. The data demonstrate that HKSa induces homologous tolerance but causes priming to LPS.
authors.affiliation: Department of Physiology & Neuroscience, The Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors.forename: Octavia M
authors.initials: OM
authors.lastname: Peck
authors.forename: Hongkuan
authors.initials: H
authors.lastname: Fan
authors.forename: George E
authors.initials: GE
authors.lastname: Tempel
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Teti
authors.forename: Perry V
authors.initials: PV
authors.lastname: Halushka
authors.forename: James A
authors.initials: JA
authors.lastname: Cook
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases; D008070:Lipopolysaccharides / Q000378:metabolism*; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System; D008264:Macrophages / Q000378:metabolism* / Q000382:microbiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction; D013211:Staphylococcus aureus / Q000378:metabolism*; D013929:Thromboxane B2 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D013929:Thromboxane B2; D007371:Interferon-gamma; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases