Wolbachia heat shock protein 60 induces pro-inflammatory cytokines and apoptosis in monocytes in vitro

Recombinant Wolbachia heat shock protein 60 (rWmhsp60) induces gene expression of pro-inflammatory cytokines IL-1β, IL-6 and TNF-α in human monocytic cell line THP-1. In addition, it inhibits the phagocytic activity and does not alter the nitric oxide production by differentiated THP-1 macrophages, which corroborates with no significant change in inducible nitric oxide synthase gene expression in rWmhsp60 treated THP-1 monocytes. Further, 24 h stimulation of peripheral blood mononuclear cells from normal individuals by rWmhsp60 reveals that monocytes enter the late apoptotic stage, while lymphocytes do not show apoptosis. Thus these findings suggest that rWmhsp60 may contribute to inflammation mediated monocyte dysfunction in filarial pathogenesis.     

Constitutive and PMA-induced interleukin-1 production by the human astrocytoma cell line T24

Astrocytes and glial cells of different species produce interleukin-1 (IL-1) in vitro. In all cases, however, the evidence relied on the detection of IL-1 activity in biological assays. In this report we describe a human astrocytoma cell line (T24) which produces IL-1 constitutively and upon induction with phorbol myristate acetate in vitro. The IL-1 activity was detected in the culture supernatant by a modified assay measuring IL-1-dependent induction of IL-2 production by EL-4 cells. The active molecule had a molecular weight of 17 kDa on gel filtration and an isoelectric point of 5.2. The activity was not neutralized by a goat antibody reacting against pI 7 IL-1. In contrast, rabbit antibody reacting against pI 5 and pI 7 IL-1 neutralized all the IL-1 activity. Cell-associated IL-1 activity was detected in the supernatant of freeze-thawed cell lysates. Serological evidence as well as isoelectric point determination further supported that the predominant form of IL-1 synthesized was of the pI 5 type, and immunoprecipitation of 35S-labeled cell lysate with monospecific polyclonal antibody to IL-1 alpha or IL-1 beta detected only IL-1 alpha precursor. However, Northern blot analysis of astrocytoma cells indicated that mRNA encoding for both IL-1 species were present. These results, therefore, provide unequivocal evidence that human astrocytoma cells synthesize both forms of IL-1 message and yet only activity corresponding to the pI 5 form is detectable inside and outside these cells, suggesting that the inactive pI 7 IL-1 precursor, if made, is not processed to the mature active 17-kDa form.     

Cultured human monocytes, granulocytes and a monoblastoid cell line (THP-1) synthesize and secrete immunosuppressive acidic protein (a type of alpha 1-acid glycoprotein)

Immunosuppressive acidic protein (IAP, pI 3.0) is a type of alpha 1-acid glycoprotein (alpha 1-AG). The secretion of IAP into the culture fluids of different subpopulations of human peripheral blood leukocytes was examined by a newly devised passive hemagglutination (PHA)-inhibition test. Human peripheral monocytes, an established monoblastoid cell line (THP-1) and peripheral granulocytes produced IAP. However, neither T nor B lymphocytes, nor lymphoblastoid cell lines induced by TCGF or EB virus respectively, produced IAP. The IAP concentration reached a maximum (215 ng/ml) in the culture fluids of peripheral monocytes (1 X 10(6)/ml) when monocytes were stimulated by the addition of either immune complex, carrageenan or endotoxin. The synthesis de novo and shedding of IAP by THP-1 were demonstrated by the immunoprecipitation of radioactive IAP in the culture fluids of [3H]leucine-labeled cells. SDS-polyacrylamide gel electrophoresis of the immunoprecipitates showed two peaks of radioactivity, one comigrated with authentic IAP at 50,000 daltons, and the other at 38,000 daltons, suggesting that two different forms of IAP (and/or alpha 1-AG) are produced from human monocytes.     

Induction of an interleukin-1 receptor (IL-1R) on monocytic cells. Evidence that the receptor is not encoded by a T cell-type IL-1R mRNA

Primary human monocytes and the human monocytic cell line THP-1 were induced to express receptors for interleukin-1 alpha (IL-1 alpha) and IL-1 beta. Treatment of primary monocytes with dexamethasone resulted in a 10-fold increase in receptor number over untreated cells, to approximately 2,000 receptors/cell. Treatment of THP-1 cells with phorbol ester followed by prostaglandin E2 and dexamethasone resulted in the expression of approximately 30,000 receptors/cell. Competitive binding assays on THP-1 cells showed that both IL-1 alpha and IL-1 beta bind to the same receptor. The monocyte IL-1R is significantly smaller (63 kDa) than the T cell IL-1R (80 kDa) and is immunologically distinct. However, induction of monocytes and monocytic cell lines leads to the appearance of an abundant mRNA of approximately 5,000 bases which hybridizes to a cDNA probe from the T cell-type IL-1R. Sequence data obtained from a cDNA clone of this mRNA indicate that the message is identical to the T cell IL-1R mRNA throughout the coding region. A smaller mRNA, also homologous to the T cell IL-1R mRNA, accumulated in induced THP-1 cells and has a shorter 3'-untranslated region than the larger. Data are presented which suggest that neither form of this message encodes the 63-kDa IL-1R, but rather that this protein is the product of a separate nonhomologous mRNA.     

Herbal melanin modulates tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6) and vascular endothelial growth factor (VEGF) production.

Recent studies have indicated that cytokines can enhance immunogenicity and promote tumor regression. However, the means for modulating cytokine production are not yet fully investigated. In this study we report the effects of a herbal melanin, extracted from Nigella sativa L., on the production of three cytokines [tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6) and vascular endothelial growth factor (VEGF)], by human monocytes, total peripheral blood mononuclear cells (PBMC) and THP-1 cell line. Cells were treated with variable concentrations of melanin and the expression of TNF-alpha, IL-6 and VEGF mRNA in cell lysates and secretion of proteins in the supernatants were detected by RT-PCR and ELISA. Melanin induced TNF-alpha, IL-6 and VEGF mRNA expression by the monocytes, PBMC and THP-1 cell line. On the protein level, melanin significantly induced TNF-alpha and IL-6 protein production and inhibited VEGF production by monocytes and PBMC. In the THP-1 cell line melanin induced production of all three cytokine proteins. These observations raise the prospects of using N. sativa L. melanin for treatment of diseases associated with imbalanced cytokine production and for enhancing cancer and other immunotherapies.     

Purification and characterization of the immunostimulatory properties of recombinant human interleukin-1 beta

In this study we have used a new method for human recombinant IL-1 beta (rIL-1 beta) purification and investigated its immunostimulatory biological activity. The IL-1 beta gene was cloned using a novel mRNA preparation from activated human blood monocytes. The purification protocol consists of extraction and two chromatographic steps using the new Soloza cation exchange resin. The purified protein was characterized electrophoretically, by amino acid analysis and reverse phase chromatography. The protein migrated on SDS-PAGE with a molecular weight of 18.200 but demonstrated the minor presence of aggregates (dimers and trimers). Specific activity of purified rIL-1 beta in comitogenic assay on mouse thymocytes was 10(8) U/mg protein. rIL-1 beta increased in a dose dependent manner proliferation of Con A-stimulated murine thymocytes, splenocytes, PHA-stimulated human peripheral blood lymphocytes and transformed B-cell lines. Comitogenic activity depended on the degree of lymphocyte preactivation and was similar to that of natural human IL-1 beta. rIL-1 beta enhanced IL-2 production by murine spleen cells and EL-4 cell line and IL-2 receptor expression by human peripheral blood mononuclear cells. It induced PGE2 release from human blood monocytes but had no effect on human neutrophil chemotaxis, phagocytosis and respiratory burst.     

Synergistic increases in IL-1 synthesis by the human monocytic cell line THP-1 treated with PAF and endotoxin

The capacity to stimulate cytokine release may be important to the long-term effects of platelet-activating factor (PAF), which has a very short half-life. Previous studies have shown that PAF stimulates interleukin 1 (IL-1) release by human monocytes. IL-1 and other cytokines produced in response to PAF may be important to the long-term effects of this short-lived lipid. The THP-1 human monocytic leukemia cell line, was used to study the mechanism by which PAF stimulates IL-1 release. PAF stimulates the release of IL-1 beta activity into THP-1 cell supernatants with a multiphasic dose-response curve very similar to that for monocytes. When THP-1 cells are treated with PAF and LPS in combination, these two stimuli interact synergistically to greatly increase the release of IL-1 activity. To assess the effect of PAF on IL-1 beta synthesis, THP-1 cell pellet proteins were separated by SDS-PAGE, blotted, and immunostained to detect IL-1 beta. Immunostaining revealed that PAF increases intracellular IL-1 beta precursor and that the combination of PAF and LPS increases IL-1 beta precursor synergistically. PAF increases IL-1 beta release mainly by increasing IL-1 beta synthesis.     

Purification and biochemical characteristics of two distinct human interleukins 1 from the myelomonocytic THP-1 cell line

An effective induction protocol for the production of interleukin 1 (IL 1) by human myelomonocytic cell line (THP-1) cells was developed, and two biochemically distinct human IL 1 peptides were purified. Lipopolysaccharide, silica, and hydroxyurea by themselves did not induce IL 1 production, but these three stimulants in combination had a synergistic effect on the production of IL 1 by THP-1 cells. A 17-kilodalton (kDa) form of human IL 1 with a pI of 7.0 (IL 1-beta) was purified to homogeneity by sequential chromatography on DEAE-Sephacel, Sephacryl S-200, CM high-performance liquid chromatography (HPLC), and hydroxyapatite HPLC. The recovery of IL 1-beta activity was 45%, and the specific activity was 2.3 X 10(7) units/mg. Both IL 1-beta and a second 17-kDa IL 1 moiety with a pI of 5.0 (IL 1-alpha) were also extracted from stimulated THP-1 cells and purified to homogeneity by sequential chromatography on Sephacryl S-200, ion exchange HPLC, and hydroxyapatite HPLC. The recovery of IL 1-beta from cell extracts was 5.6%, and the specific activity was 3 X 10(7) units/mg. In contrast, only 0.85% of IL 1-alpha was recovered with a specific activity of 5.3 X 10(7) units/mg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Involvement of a calpain-like protease in the processing of the murine interleukin 1 alpha precursor

Interleukin (IL) 1 alpha is synthesized as a 33-kDa precursor that is enzymatically cleaved to the 15-17-kDa forms that are found in the culture supernatants of activated macrophages. We have explored the possibility that calcium might enhance IL-1 processing and secretion via the stimulation of a calcium-dependent protease. We have found that lysates prepared from human peripheral blood monocytes, the human histiocytic lymphoma cell line U937, and the murine macrophage cell line P388D1 contain a calcium-dependent IL-1 alpha processing activity that cleaves the IL-1 alpha precursor to its mature form. Although NIH 3T3 mouse fibroblast cell lysates also contain IL-1 processing activity, lysates from the murine thymoma EL-4, the human epidermoid cell line HEp-2, and the human foreskin fibroblast line FS-4 lack this activity. IL-1 processing activity is inhibited by leupeptin and exhibits a molecular mass of 80-110 kDa. The processing activity is also inhibited by a monoclonal antibody directed against calpain type I. These results indicate that the processing of the IL-1 alpha precursor is mediated, at least in part, by a member of the calpain family of proteases. Mixing experiments revealed that lysates from EL-4 or HEp-2 cells contain an inhibitor(s) of the calpain-like protease in macrophage extracts. It is, therefore, likely that many non-macrophage cell types are unable to process the IL-1 alpha precursor because the calpain present in these cells is only weakly active due to the presence of a specific inhibitor(s) such as calpastatin.     

Purification and characterization of interleukin 1 receptor level antagonist proteins from THP-1 cells

Culture medium conditioned by phorbol 12-myristate 13-acetate-differentiated THP-1 cells contained interleukin 1 (IL-1) antagonist activity as measured by inhibition of both IL-1 beta binding to receptors on YT cells and inhibition of IL-1/phytohemagglutinin-stimulated IL-2 synthesis by LBRM-33-1A5 T cells. Based on their ability to compete for 125I-IL-1 beta binding to receptors on YT cells, four distinct antagonist proteins were purified from THP-1 cell conditioned medium using a combination of ion-exchange, hydrophobic interaction, and size exclusion chromatographies. The four proteins had different isoelectric points with molecular masses in the range 22-26 kDa and had similar specific activities for inhibition of IL-1 beta binding to cell surface receptors (Ki values 0.33-0.64 nM) and for inhibition of IL-1/phytohemagglutinin-stimulated IL-2 synthesis by 1A5 cells (IC50 values 25-100 pM). Amino-terminal sequence analysis of the two major forms (25 kDa/pI 5.1 and 22 kDa/pI 5.8) revealed complete identity for the first 27 residues in both forms. Based on the results of peptide mapping, amino acid compositional analysis and immune blotting, all of the forms were deduced to be variants of a common protein. Deglycosylation of the antagonist proteins with N-glycanase converted them to a common form (22 kDa/pI 5.8), indicating that the four isoforms represent glycosylation variants of a common protein and that asparagine-linked oligosaccharides are responsible for the observed size and charge heterogeneity.     

Th2 cell membrane factors in association with IL-4 enhance matrix metalloproteinase-1 (MMP-1) while decreasing MMP-9 production by granulocyte-macrophage colony-stimulating factor-differentiated human monocytes

Monocytes/macrophages are directly involved in tissue remodeling and tissue destruction through the release of matrix metalloproteinases (MMP). In the present study, we examined the effect mediated by contact of polarized Th cells with mononuclear phagocytes on the production of MMP-1, MMP-9, and their inhibitor. Plasma cell membranes from Ag-activated Th1 and Th2 cells were potent inducers of MMP-1 production by THP-1 cells. Cell membrane-associated TNF was found to be only partially involved in MMP-1 induction by both Th1 and Th2 cells. In Th2 cells exclusively, membrane-associated IL-4 induced MMP-1 production by THP-1 cells. This membrane-associated IL-4 effect was additive to that of TNF and was specifically observed on MMP-1 as MMP-9 production was concomitantly inhibited. Similarly, soluble IL-4 induced THP-1 cells to produce MMP-1, its effect proving additive to that of soluble TNF and to that of cell membranes of mitogen-activated HUT-78 cells. Its activity was blocked by IL-4 neutralization, and was unaffected by the presence of indomethacin. These effects on THP-1 cells were observed at protein and mRNA levels. Although inhibitory on freshly isolated peripheral blood monocytes, soluble IL-4 enhanced T cell-induced MMP-1 and inhibited MMP-9 production both at protein and mRNA levels in monocytes cultured for 7 days in the presence of GM-CSF. Thus, in contrast with previously reported effects, Th2 and IL-4 specifically induce MMP-1 production by mononuclear phagocytes at various stages of differentiation. This IL-4 activity may be relevant to pathological conditions dominated by Th2 inflammatory responses, resulting in tissue remodeling and destruction.     

Effect of a hot water-soluble extraction from Grifola frondosa on the viability of a human monocyte cell line exposed to mitomycin C

The effects of a hot water-soluble extract of Grifola frondosa on the viability of multiple immune cell lines were examined in vitro. The extract and the 1000-cut extract, a low molecular weight fraction, improved the viability of a human monocyte cell line, THP-1, treated by the anticancer drug mitomycin C. DNA microarray and immunoassay results revealed increases in interleukin (IL)-8 expression by THP-1 cells in response to the 1000-cut extract. These data suggest that the extract would enhance the immune system through induction of IL-8 production by human blood monocytes, which leads to activated neutrophils.     

Direct and monocyte-induced innate immune response of human lung epithelial cells to Brucella abortus infection

Although Brucella frequently infects humans through inhalation, its interaction with pulmonary cells has been overlooked. We examined whether human lung epithelial cells produce proinflammatory mediators in response to Brucella infection. Infection with smooth or rough strains of Brucella abortus induced the secretion of IL-8 and GM-CSF by the bronchial epithelial cell lines Calu-6 and 16HBE14o-, but not by the alveolar epithelial cell line A549. Infected Calu-6 cells also produced low levels of MCP-1. Since monocyte-derived cytokines may induce chemokine secretion in epithelial cells, cocultures of human monocytes (THP-1 cell line) and respiratory epithelial cells were used to study such interaction. IL-8 and MCP-1 levels in B. abortus-infected THP-1:A549 and THP-1:Calu-6 cocultures, and MCP-1 levels in THP-1:16HBE14o- cocultures, were higher than those detected in infected epithelial monocultures. Conditioned medium from infected monocytes induced the secretion of IL-8 and/or MCP-1 by A549 and Calu-6 cells, and these effects were mainly mediated by IL-1 (in A549 cells) or TNF-α (in Calu-6 cells). Conversely, culture supernatants from Brucella-infected bronchial epithelial cells induced MCP-1 production by monocytes, an effect largely mediated by GM-CSF. This study shows that human lung epithelial cells mount a proinflammatory response to Brucella, either directly or after interaction with Brucella-infected monocytes.     

Effect of the mitogen-activated kinase inhibitors on monocyte protein-1-stimulated chemotaxis of cells

Monocyte chemoattractant protein (MCP-1) is a major chemoattractant for monocytes and T-lymphocytes although it can cause migration of the HUVECs. We used monocytic cell line THP-1, monocytes of human peripheral blood, and HUVECs to study MCP-1 receptor-mediated cell migration. We showed that THP-1 and the monocytes chemotaxis was decreased in presence of specific inhibitors of p 38 MAP-kinase. Furthermore, it was almost completely diminished by inhibitor of tyrosine kinases. In contrast, MCP-1-stimulated migration of HUVECs was abrogated by specific inhibitor of ERK1/2 MAP-kinases and, to a lesser extent, by blocking tyrosine kinases. These results suggest that intracellular signal pathways activated by MCP-1 in monocytes and HUVECs, are distinct.     

Isolation and properties of interleukin 1 from human blood monocytes

Among different tested substances LPS-containing preparations were found to be most effective inducers of secretory interleukin-1 in human peripheral blood monocytes in vitro. IL-1 from supernatant of prodigiozan- + con A-stimulated monocytes had a MM of 18-20 KD and pI of 5.2-5.4 and 6.8 revealing an equal comitogenic activity and of 6.0 (minor peak).     

Lipopolysaccharide and interleukin 1 inhibit interferon-gamma-induced Fc receptor expression on human monocytes

The objectives of these studies were to study the effects of bacterial lipopolysaccharide (LPS) on interferon-gamma (IFN-gamma)-induced Fc receptor expression on human monocytes and to examine whether these effects were mediated through stimulation of interleukin 1 (IL-1) production. Fc receptor expression was determined by binding of monomeric monoclonal murine immunoglobulin (Ig)G2a and cytofluorographic analysis. IL-1 activity in monocyte supernatants and lysates was assayed by augmentation of mitogen-induced murine thymocyte proliferation. IFN-gamma induced the expression of Fc receptors on human monocytes that were specific for murine IgG2a. This induction was inhibited by the addition of LPS in amounts as low as 2 to 8 pg/ml. LPS inhibition of IFN-gamma-induced Fc receptor expression was paralleled by the appearance of IL-1 in monocyte lysates and supernatants. The addition of purified human or recombinant IL-1 beta at the initiation of culture similarly inhibited the expression of IFN-gamma-induced Fc receptors on the monocytes. LPS also inhibited Fc receptor expression on the human myelomonocytic cell line THP-1 after induction with IFN-gamma or phorbol myristate acetate alone or with both agents together. This inhibition also was paralleled by the production of IL-1 but the addition of exogenous IL-1 to the THP-1 cells had no effect on IFN-gamma-induced Fc receptor expression. Tumor necrosis factor (TNF) inhibited IFN-gamma-induced Fc receptor expression on human monocytes but was much less potent than comparable amounts of IL-1. TNF also did not inhibit Fc receptor expression on THP-1 cells. In fact, IL-1 or TNF led to an enhancement in IFN-gamma-induced Fc receptor expression on THP-1 cells. These results indicate that LPS can inhibit IFN-gamma-induced Fc receptor expression on human monocytes and that IL-1 and TNF may mediate these effects of LPS. Thus, an autocrine or paracrine role is suggested for these cytokines. The possibility exists that intracellular IL-1 resulting from LPS stimulation may be at least in part responsible for inhibition of Fc receptor expression.     

Production and characterization of a monoclonal antibody (A1-3) that binds selectively to activated monocytes and inhibits monocyte procoagulant activity

We describe the generation and characterization of a new monoclonal antibody, A1-3, which possesses two unique properties. First, A1-3 binds selectively to stimulated human monocytes. Secondly, A1-3 inhibits the procoagulant activity expressed by stimulated monocytes and by human brain tissue factor. Unstimulated human peripheral blood cells (granulocytes, lymphocytes, monocytes, red blood cells, and platelets), prepared in the absence of detectable endotoxin, express no procoagulant activity and fail to bind A1-3. Stimulation of peripheral blood monocytes. alveolar macrophages, or the monocyte-like cell line U937, however, results in the expression of procoagulant activity and the binding of A1-3. The surface antigen recognized by A1-3 was recovered from endotoxin-stimulated human monocyte vesicles by immune precipitation and demonstrated an apparent m.w. of approximately 52,000. It is proposed that the monoclonal antibody A1-3 detects a differentiation antigen on human monocytes that is expressed in response to stimuli for monocyte activation.