Molecular cloning of a human monocyte-derived neutrophil chemotactic factor (MDNCF) and the induction of MDNCF mRNA by interleukin 1 and tumor necrosis factor

Recombinant human monocyte IL-8 primes NADPH-oxidase and phospholipase A2 activation in human neutrophils

We demonstrate for the first time that recombinant human monocyte interleukin-8 (rhMIL-8) primes human neutrophil responses to fMLP. Human neutrophils preincubated for 10 min with 10(-8) M rhMIL-8 and then stimulated with micromolar fMLP show enhanced release of superoxide anions, platelet-activating factor (PAF) and arachidonic acid compared with cells which are not initially exposed to rhMIL-8. We also demonstrate that this enhancement of the neutrophil response is dependent on the dose of rhMIL-8 with the greatest enhancement corresponding with IL-8 levels which cause maximum shape change of neutrophils. Priming of neutrophils occurred after only 30 seconds preincubation with rhMIL-8 indicating that the mechanism of IL-8 priming is extremely rapid as was stimulation of neutrophil shape change by rhMIL-8. Priming of neutrophils with rhMIL-8 did not increase sensitivity to fMLP but enhanced responsiveness to activating concentrations. rhMIL-8 alone at levels used for priming caused no release of superoxide anions, arachidonic acid or PAF. These results suggest that IL-8 primes neutrophil phospholipase A2 and NADPH-oxidase activation in response to fMLP.

Effect of picibanil (OK432) on neutrophil-mediated antitumor activity: implication of monocyte-derived neutrophil-activating factors

Picibanil (OK432), an extract from streptococci, has been widely utilized to treat malignant ascites and pleural effusions. The antitumor mechanism is believed to include complement-mediated neutrophil activation. Employing a flow-cytometric analysis of actin polymerization as an indicator of cell activation as well as a tumor proliferation assay, we have found that monocyte-derived neutrophil-activating factors were involved in OK432-induced neutrophil activation as well as antitumor activity. OK432-stimulated (0.1 KE/ml; 0.01 mg/ml) monocyte supernatants (OKMS) induced neutrophil actin polymerization and chemotaxis. OKMS were responsible for neutrophil-mediated inhibition of human leukemic (CEM) cell proliferation and stimulated neutrophils to produce superoxide in the presence of CEM leukemic cells at an effector/target ratio higher than 20/1. In contrast, OK432 alone, OK432-stimulated lymphocyte supernatants, or OK432-stimulated neutrophil supernatants had no effect on neutrophil activation or suppression of tumor cell proliferation. OK432 in combination with mononuclear cells also had no effect on the inhibition of CEM cell proliferation. Pretreatment of OKMS at 56 degrees C for 30 min did not affect its ability to activate neutrophils, implying that complement activation is not responsible for the neutrophil activation. Supernatants from OK432-stimulated mononuclear cells, as determined by enzyme-linked immunosorbent assays and radioimmunoassays, contained high levels of interleukin-8 (IL-8; 1567 +/- 145 pg/ml) and tumor necrosis factor (TNF alpha; 2105 +/- 152 pg/ml), low levels of leukotriene B4 (800 +/- 45 pg/ml) and IL-1 beta (180 +/- 22 pg/ml), but interferon gamma was not detectable. IL-1 beta, IL-8, and TNF alpha transcripts, undetectable in untreated monocytes, increased significantly after 30-60 min exposure to OK432. These results suggest that neutrophil-activating factors from monocytes or resident macrophages may play an important role in the OK432-induced neutrophil activation and antitumor activity.

Interleukin-8 gene expression from human alveolar macrophages: the role of adherence

The human alveolar macrophage (AM) is an important immune effector cell of the lung, as this cell possesses potent antimicrobial activities and has the ability to present antigen. In addition, the Am can secrete a number of regulatory and chemotactic cytokines in response to both endogenous and exogenous stimuli. In this study, we demonstrate that the adherence of AM to plastic or cellular substrates is an important activation event leading to the gene expression of novel chemotactic cytokine interleukin (IL)-8. The culturing of AM on plastic induced the time-dependent accumulation of IL-8 mRNA. In addition, adherence of these cells induced the gene expression of the proinflammatory cytokines tumor necrosis factor-alpha and IL-1 beta. This adherence phenomenon was not specific to plastic, as AM cultured on collagen- or fibronectin-coated plates also expressed IL-8 mRNA upon adherence. The adherence of Am resulted in the induction of de novo IL-8 mRNA synthesis, as this mRNA accumulation was completely abrogated by actinomycin D. Adherence-induced IL-8 mRNA expression was not altered by cycloheximide, suggesting that de novo or ongoing protein synthesis was not required for induction of IL-8 message. Adherence of AM to plastic not only upregulated IL-8 mRNA levels but also induced the production of extracellular IL-8 immunoreactive protein. Both adherent and nonadherent AM treated with lipopolysaccharide generated substantial amounts of IL-8 mRNA. Adherence and lipopolysaccharide, however, acted in a synergistic fashion to dramatically augment the production of extracellular IL-8 from these cells. Our findings would suggest that AM adherence is an important macrophage-activating event that may play a critical role in the modulation of lung inflammatory responses.

Increased expression of the interleukin-8 gene by alveolar macrophages in idiopathic pulmonary fibrosis. A potential mechanism for the recruitment and activation of neutrophils in lung fibrosis

Neutrophil migration into the airspaces of the lung is thought to contribute to the alveolar damage and subsequent fibrosis in idiopathic pulmonary fibrosis (IPF). Interleukin 8 (IL-8), a monocyte- and macrophage-derived cytokine, displays potent chemotactic and activating properties towards neutrophils and thus may contribute to the pathogenesis of IPF. The objective of this investigation was to quantify the spontaneous expression of IL-8 transcripts by alveolar macrophages from normal healthy volunteers and individuals with IPF. A quantitative assay employing reverse transcription of mRNA and the polymerase chain reaction was utilized. The level of IL-8 mRNA in alveolar macrophages was found to be significantly elevated in individuals with lone IPF or with lung fibrosis associated with connective tissue disorders compared to normal healthy controls. Moreover, the level of IL-8 mRNA in the 23 individuals with IPF correlated with the number of neutrophils per milliliter in their bronchoalveolar lavage (BAL) and with the degree of disease severity. In addition, the level of IL-8 protein in BAL was found to reflect the pattern of IL-8 mRNA expression by alveolar macrophages. These data suggest that IL-8 derived from alveolar macrophages may significantly contribute to neutrophil involvement in the pathogenesis of IPF.

Human corneal interleukin-8. IL-1 and TNF-induced gene expression and secretion

Corneal leukocytic infiltration is an important component of numerous ocular diseases, but specific corneal-derived leukocyte chemotaxins have not been identified. In this study, the authors identified interleukin-8 (IL-8), a known neutrophil and lymphocyte chemotaxin, to be an important chemotaxin produced by human corneal tissue. In situ hybridization and immunohistochemistry of corneas exposed to human recombinant (r) interleukin-1-beta (rIL-1 beta) or tumor necrosis factor-alpha (rTNF-alpha) revealed significant increases in corneal endothelial and stromal cell IL-8 mRNA (P less than 0.001) and marked increases in cell-associated immunoreactive IL-8 compared with unstimulated controls. ELISA assays revealed four- to eight-fold increases in corneal IL-8 secretion after 24-hour exposures to either cytokine over that obtained with unstimulated corneas (P = 0.01). In neutrophil chemotactic bioassays, significant increases in functional IL-8 were detected in media conditioned by corneas exposed to rIL-1 beta or rTNF-alpha for 24 hours (P less than 0.001). Preincubation of these corneal media with anti-IL-8 antibody significantly reduced neutrophil chemotaxis by more than 80%. These results suggest that the cornea is an active participant in ocular inflammation and raise the possibility that agents used in experimental corneal pocket models may produce indirect effects by inducing corneal secretion of other factors, such as IL-8.

Neutrophil chemotactic factor produced by Japanese encephalitis virus stimulated macrophages

The mechanism of neutrophil leucocytosis in cases of Japanese encephalitis is not known. We here report that during Japanese encephalitis virus (JEV) infection in mice the splenic macrophages secrete a chemotactic factor that attracts the neutrophils. The peak activity of macrophage derived factor (MDF) was observed on day 7 following infection. The MDF acted in a dose-dependent manner. This chemoattractant was purified by low pressure liquid chromatography and gave a single band of 10 kD on silver stained polyacrylamide gel. The MDF was found to be heat resistant and sensitive to prolonged incubation with proteases.

Pulmonary fibroblast expression of interleukin-8: a model for alveolar macrophage-derived cytokine networking

The pulmonary fibroblast's (PF) unique location allows it to communicate in a bidirectional fashion between the vascular compartment and alveolar airspace, placing it in a strategic position for the elicitation of inflammatory leukocytes into the lung. In this study, we demonstrate that PF may contribute to pulmonary inflammation through the production of a potent neutrophil chemotactic factor, interleukin (IL)-8. PF-derived IL-8 expression was dependent upon stimulation by either tumor necrosis factor (TNF) or IL-1 but not lipopolysaccharide (LPS). Both TNF and IL-1 stimulation of PF resulted in a time- and dose-dependent expression of steady-state levels of mRNA, antigen, and specific chemotactic activity consistent with IL-8. Because it was apparent that cytokine networking may exist in the lung between alveolar macrophage (AM)-derived cytokines and the production of PF-derived IL-8, we next examined an in vitro model of cellular communication within the lung. We determined that LPS-stimulated AM-conditioned media induced significant levels of PF-derived IL-8 mRNA, which was inhibited by preincubation with specific neutralizing TNF and IL-1 beta antibodies. Furthermore, when AM were directly co-cultured with PF and stimulated with LPS, the kinetic analysis of PF-derived antigenic expression of IL-8 was shifted toward the right. This suggested that PF-derived IL-8 expression in co-culture was first dependent upon activation of the AM by LPS and subsequent elaboration of macrophage inflammatory mediators. These data provide evidence that cytokine networking between AM and PF may be operative in the lung, culminating in the generation of IL-8 and elicitation of inflammatory leukocytes.

Cytokine-associated tissue injury and lethality in mice: a comparative study

A comparative study was performed to examine the lethal effects of several cytokines injected into mice sensitized with actinomycin D (Act-D). Consistent with published data, human tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) (0.2-5 micrograms) caused the death of the animals within 8-12 hr after injection. Human interleukin-6 (IL-6) and interleukin-8 (IL-8) (0.6-6 micrograms) known to be induced by TNF-alpha did not show any lethal effects, indicating that TNF-alpha-associated lethality is not mediated by IL-6 or IL-8. Human tumor necrosis factor-beta (TNF-beta) (also called lymphotoxin), which shares structural and functional properties with TNF-alpha, was as potent as TNF-alpha in its lethal effects. Murine interferon-gamma (IFN-gamma) (0.04-5 micrograms) was also tested and showed no lethal effects in this model. In addition, a synthetic peptide corresponding to amino acid residues 163-171 of IL-1 beta, and which has been shown to lack the inflammatory effects of IL-1 beta, also caused no lethality among Act-D sensitized mice. The pretreatment of mice with IL-6, IL-8, or IFN-gamma had no protective effects on TNF-alpha or IL-1 beta-induced lethality in contrast to the protection observed by a pretreatment with TNF-alpha/IL-1 beta themselves or with endotoxin. Histopathologic data showed that severe tissue injury in vital organs is associated with the rapid lethality among sensitized mice.

Expression and secretion of leukocyte chemotactic cytokines by normal human melanocytes and melanoma cells

The capacity of human melanocytes and melanoma cells to produce IL-8 and monocyte chemotactic and activating factor (MCAF) was investigated. Melanocytes expressed mRNA for IL-8 and MCAF, when stimulated with either IL-1 alpha or TNF alpha, but not when stimulated with IL-6, IFN gamma, or LPS alone. IL-8 and MCAF could be induced in a dose-dependent fashion with doses as low as 0.1 ng/ml TNF alpha and 0.5 ng/ml IL-1 alpha. IL-8 and MCAF mRNA were rapidly expressed and peaked between 2 and 4 h for IL-8 and between 4 and 8 h for MCAF. This correlated well with the accumulation of IL-8 antigen as measured by a radioimmunoassay. Supernatants from melanocyte cultures stimulated with either IL-1 alpha or TNF alpha and separated on a heparin-Sepharose column became positive for neutrophil and monocyte chemotactic activity in a dose- and time-dependent fashion. When IFN gamma was added to melanocyte cultures stimulated with suboptimal doses of TNF alpha there was a synergistic increase in secreted IL-8 protein and monocyte chemotactic activity. These data provide further evidence for the possible role of melanocytes in the initiation of an inflammatory reaction. Three different malignant melanoma cell lines stimulated with either TNF alpha or IL-1 alpha expressed IL-8 mRNA, but not mRNA for MCAF. The IL-8 mRNA signal corresponded well with the amount of secreted IL-8 protein. These data suggest that IL-8 and MCAF may play a role in growth regulation and spreading of melanomas.

Regulation of alveolar macrophage production of chemoattractants by leukotriene B4 and prostaglandin E2

Alveolar macrophages (AM) appear to influence the recruitment of neutrophils into the lung by the elaboration of both lipid and peptide chemotactic molecules for neutrophils. Little is known about the mechanisms that regulate production or release of chemotactic molecules by AM or the interaction between these classes of chemotactic molecules. We investigated the hypothesis that the lipid mediator leukotriene B4 (LTB4) has an in vitro regulatory action on the production of chemotactic proteins by AM. In these experiments, the chemotactic activity in AM culture supernatants was measured in a modified Boyden chamber. LTB4 treatment increased AM production of chemotactic activity in excess of what might be attributed to the amount of LTB4 measured in the culture supernatant after the incubation period. This effect was magnified by in vivo administration of endotoxin prior to AM harvesting. Pretreatment with LTB4 caused a sustained 250% increase in AM production of chemotactic activity, yet only negligible amounts of LTB4 were measured by gas chromatography/mass spectrometry in the LTB4-pretreated AM culture supernatants, indicating that LTB4 alone did not account for the chemotactic activity observed in our studies. A chemotactic peptide in LTB4-treated AM culture supernatant could be isolated and separated from LTB4 by molecular sieve chromatography. Purified column fractions contained 80% of the chemotactic activity of endotoxin-stimulated AM culture supernatant and had a molecular mass of 10,000 D. In contrast to LTB4, prostaglandin E2 (PGE2) suppressed chemotactic activity production by endotoxin-stimulated AM by 70%. Pretreatment with PGE2 was not effective; PGE2 had to be present in the AM culture medium during endotoxin exposure in order to exert a suppressive effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukins: biological properties and therapeutic potential

Interleukins are biologically active glycoproteins derived primarily from activated lymphocytes and macrophages. Tremendous insight into the biochemical and biological properties of interleukins has been gained with advances in recombinant DNA technology, protein purification, and cell-culture techniques. The biological properties of interleukins include induction of T-lymphocyte activation and proliferation, augmentation of neutrophil, macrophage, and T-lymphocyte cytotoxicity, and promotion of B lymphocyte and multilineage bone marrow stem-cell precursor growth and differentiation. Interleukins may play a role in the pathogenesis of several important diseases. Interleukin therapy is likely to play an important role in the treatment of cancer, infectious diseases, and immunodeficiency syndromes.

Anti-IL-1 alpha autoantibodies in patients with rheumatic diseases and in healthy subjects

We have developed a quantitative assay for IgG autoantibodies against IL-1 alpha using protein A-Sepharose CL-4B. We examined the autoantibodies in sera from 107 healthy subjects, 151 patients with rheumatoid arthritis (RA), 64 patients with systemic lupus erythematosus (SLE) and 16 patients with systemic sclerosis. The frequency of positive sera for the autoantibodies in patients with RA was 16.6%, which was about three times more frequent (P less than 0.01) than that in healthy subjects (5.6%) or that in patients with SLE (4.7%). Only one serum of 16 patients with systemic sclerosis was positive for the autoantibodies. Neutralizing activity of the autoantibodies was demonstrated by murine thymocyte proliferation assay. The concentrations of IgG at 50% inhibition of IL-1 alpha (15 pM) induced thymocyte proliferation ranged between 0.1 and 0.5 mg/ml. A time-course study showed fluctuations of the titres of the autoantibodies in parallel with the disease activity of RA. These results suggest that the anti-IL-1 alpha autoantibodies present in the sera and possibly some other body fluids may be involved in the regulation of IL-1 activity in vivo.

IL-1 and TNF-alpha induction of IL-8 and monocyte chemotactic and activating factor (MCAF) mRNA expression in a human astrocytoma cell line

In order to elucidate the role of inflammatory cytokines in the central nervous system (CNS), we examined whether IL and TNF-alpha induce cells in the CNS to produce two newly identified leucocyte chemo-attractants, IL-8 and monocyte chemotactic and activating factor (MCAF). Several human astrocytoma and glioblastoma cell lines expressed high levels of IL-8 and MCAF mRNA in vitro upon stimulation with IL-1 and TNF-alpha. In particular, an astrocytoma cell line U373MG subclone responded markedly to IL-1 with high expression levels of IL-8 and MCAF mRNA as well as IL-6 mRNA. Both IL-8 and MCAF mRNA expression depended on the dose of IL-1 and appeared as early as 30 min to 1 hr after IL-1 stimulation, confirming that these are early inducible genes. The production of IL-8 and MCAF in the U373MG cell culture supernatants was confirmed by a competitive radioimmunoassay (RIA) as well as chemotactic activities on human neutrophils and monocytes. IL-1-induced IL-8 and MCAF mRNA expression appeared to occur at least at the transcriptional level as revealed by a nuclear run-off assay. Moreover, IL-1 treatment increased the half-life of IL-8 and MCAF mRNA markedly, suggesting that increased mRNA stability was also responsible for the enhanced gene transcription. These data suggest that IL-1 and TNF-alpha induce astrocytes to produce IL-8 and MCAF transcriptionally and post-transcriptionally, both of which may be responsible for leucocytosis seen in inflammation of the CNS.

Quantitative determination of IL-1 alpha-induced IL-8 mRNA levels in cultured human keratinocytes, dermal fibroblasts, endothelial cells, and monocytes

The presence of the leukocyte chemotactic cytokine interleukin 8 (IL-8) in psoriatic scales and in epidermal tissue overlying allergic patch test reactions suggests a role for this cytokine in certain inflammatory skin diseases. IL-8 can be produced by several cell types present in the skin. Their relative potentials for IL-8 expression has, however, not yet been studied, due to the lack of convenient methods for quantitative comparison of specific mRNA amounts in different cell types. Using a new method for quantification, we compared specific IL-8 mRNA amounts in cultures of keratinocytes, dermal fibroblasts, endothelial cells, and monocytes, stimulated with interleukin 1 alpha (IL-1 alpha). Endothelial cells produced very high, fibroblasts and monocytes intermediate, and keratinocytes low amounts of IL-8 mRNA. We also studied the time course of IL-8 mRNA levels in the four cell types following IL-1 alpha stimulation, and found a clear difference both in onset and stability of the response. We discuss the different strength of the response at different time points in the cell types analyzed in relation to their possible role in regulation of the normal response to stimulation.

Expression of monocyte chemotactic protein and interleukin-8 by cytokine-activated human vascular smooth muscle cells

The present study was designed to investigate the capacity of human vascular smooth muscle cells (SMCs) to produce a cytokine chemotactic for monocytes (monocyte chemotactic protein [MCP]) and by way of comparison, a related polypeptide activator of neutrophils (known as interleukin-8 [IL-8] or neutrophil activating protein-1 [NAP-1]. On exposure to IL-1, SMCs released high levels of chemotactic activity for monocytes, which could be removed by absorption with anti-MCP antibodies. MCP production by activated SMCs was comparable to that of IL-1-stimulated umbilical vein endothelial cells. Activated SMCs released appreciable levels of IL-8, as determined by a specific enzyme-linked immunosorbent assay, but little chemotactic activity for neutrophils. IL-1-treated SMCs expressed high levels of both MCP and IL-8 mRNA transcripts, as assessed by Northern blot analysis. Tumor necrosis factor and bacterial lipopolysaccharide but not IL-6 also induced MCP and IL-8 gene expression in SMCs. Nuclear runoff analysis revealed that IL-1 augmented transcription of the MCP and IL-8 genes. The capacity of SMCs to produce a cytokine (MCP) that recruits and activates circulating mononuclear phagocytes may be of considerable importance in the pathogenesis of vascular diseases (e.g., vasculitis and atherosclerosis) that are characterized by monocyte infiltration of the vessel wall.

IL-8 causes in vivo neutrophil migration by a cell-dependent mechanism

A dose-dependent neutrophil migration was observed following the injection of recombinant interleukin-8 (rIL-8) into rat peritoneal cavities. This finding contrasts with the inability of rIL-8 to induce neutrophil emigration into subcutaneous air-pouches. Pre-treatment of the animals with dexamethasone (0.5 mg/kg, s.c.) or depletion of the peritoneal resident cell population abolished the neutrophil migration induced by rIL-8 and by recombinant interleukin-1 beta (rIL-1 beta). Different from that which occurs with rIL-1 beta, neutrophil migration induced by rIL-8 was not enhanced by an increase in the peritoneal macrophage population. Transference of homologous total resident peritoneal cells to the air-pouch rendered this cavity responsive to the chemotactic effect of rIL-8 and potentiated the neutrophil migration induced by rIL-1. Our results show that both rIL-8 and rIL-1 beta are able to induce in vivo neutrophil migration by an indirect mechanism, dependent on resident cells. Neither macrophages nor lymphocytes seem to be involved in the rIL-8 chemotactic effect. However, peritoneal resident mast cells may be implicated in this mechanism. These cells, when stimulated in vitro by rIL-8, released a factor that when injected into peritoneal and air-pouch cavities induced neutrophil migration.

Chemotactic cytokine (IL-8 and MCP-1) gene expression by human whole blood

The salient features of systemic or local inflammation are the myriad of cellular and humoral interactions that result in elicitation of inflammatory leukocytes. In this study using specialized connective tissue, intact whole blood, we demonstrate the gene expression of two novel chemotactic factors. The buffy-coat cellular expression of neutrophil chemotactic/activating factor/interleukin 8 (IL-8) and monocyte chemotactic/activating protein (MCP-1) mRNA were time and dose-dependent in response to either lipopolysaccharide or zymosan stimulation. This system with the complexity of tissue provides a unique model for the determination of chemotactic cytokine gene expression.

Cytokine-activated human mesangial cells generate the neutrophil chemoattractant, interleukin 8

Human mesangial cells (MC) in culture, when stimulated by interleukin 1 alpha(IL-1 alpha) or tumour necrosis factor (TNF alpha), but not with lipopolysaccharide (LPS), express interleukin 8 (IL-8) mRNA, and both cell associated and extracellular IL-8. Dexamethasone treatment of mesangial cells induced partial inhibition of the release of extracellular IL-8, while cell-associated IL-8 and IL-8 mRNA were not significantly altered. We propose that the mesangial cell has a direct role in the initiation and propagation of inflammatory events within the glomerulus via the generation of the chemotactic cytokine IL-8.

Increased IL-6 production by monocytes and keratinocytes in patients with psoriasis

Interleukin-6 (IL-6) is a multifunctional inflammatory cytokine that is produced by monocytes and keratinocytes upon stimulation. Because psoriasis is a skin disease characterized by a hyperproliferative activity of keratinocytes and an inflammatory infiltrate, in the present study IL-6 production of monocytes and keratinocytes of patients with psoriasis was investigated. Peripheral blood mononuclear cells (PBMC) derived from psoriatics, atopics, and healthy controls were incubated for 24 h and, subsequently, supernatant IL-6 activity was measured using an IL-6-dependent hybridoma cell line (B9). Compared to controls and atopics, PBMC of psoriatics produced significantly increased amounts of biologically active IL-6. These findings were also confirmed by Western blot analysis using a specific antiserum directed against IL-6. Moreover, when the sera of the same patients were tested for IL-6 activity, sera of psoriatics contained significantly elevated amounts of circulating IL-6 in comparison to samples from atopics and healthy controls. In contrast to normal or uninvolved skin, keratinocytes in psoriatic lesions were remarkably positive for IL-6 as detected by immunohistochemistry and in situ hybridization. In addition, IL-6 also was found to induce its own synthesis and release by monocytes. These findings indicate that keratinocytes and monocytes in psoriasis are activated to produce increased amounts of IL-6, which may be one of the mediators involved in the regulation of both local and systemic inflammatory reactions occurring in skin diseases such as psoriasis.

Monocyte-derived neutrophil chemotactic factor/interleukin-8 is a potential mediator of crystal-induced inflammation

The physical interaction of particulates with resident mononuclear phagocytes is a consistent feature in certain forms of crystal-induced inflammation. In this study, we observed that monosodium urate crystals stimulated the rapid release of neutrophil chemotactic activity from monocytes, and that this activity steadily increased over 24 hours. Because the release of monocyte-derived neutrophil chemotactic activity was markedly diminished by pretreatment of the monocytes with cycloheximide, and was completely removed from conditioned media by adsorption to heparin-agarose, we addressed the possibility that monocyte-derived neutrophil chemotactic factor/interleukin-8 (IL-8), a heparin-binding neutrophil-activating polypeptide, might modulate these activities. Urate crystal-induced IL-8 secretion from monocytes was verified by radioimmunoassay. In addition, an IL-8-specific antibody markedly inhibited the neutrophil-activating capacity of the conditioned media from monocytes activated by urate crystals, as well as by inflammatory silica crystals. Last, IL-8 was significantly increased in gouty synovial fluids (range 3.0-16.8 ng/ml, mean 8.4 ng/ml, n = 6) relative to osteoarthritic synovial fluids (range 1.1-1.7 ng/ml, mean 1.5 ng/ml, n = 6) (P = 0.006). We conclude that microcrystal-induced secretion of IL-8 by mononuclear phagocytes may mediate a number of forms of crystal-induced inflammation.

Rabbit alveolar macrophages stimulated with endotoxin and lung fragments from endotoxemic rabbits produce a leukocyte infiltration-inducing factor that lacks IL-1, TNF alpha, or chemotactic activity

We reported previously that rabbit pleural and peritoneal macrophages (Møs) and human Mø stimulated with endotoxin (LPS) release a protein factor of 45 to 60 kd that induces local polymorphonuclear leukocyte (PMNL) infiltration upon intradermal injection in rabbits. In the case of the human Mø product, it was shown to be distinct from interleukin-1 (IL-1), tumor necrosis factors (TNF alpha), granulocyte macrophage colony stimulating factor (GMCSF), IL-6, and lower molecular weight PMNL chemotactic factors. Here, we examined resident rabbit alveolar Møs to determine if they produce a similar factor following in vitro or in vivo exposure to LPS. Following LPS exposure (0.3 to 30 ng/ml), alveolar Møs obtained from normal rabbits by bronchoalveolar lavage released PMNL recruiting activity within 3 h, as measured by the accumulation of 51Cr labeled blood PMNL at injected skin sites. Production of this activity was blocked by cycloheximide; it was heat labile and not affected by polymyxin B, which neutralized the LPS. On gel filtration chromatography, a major peak of activity was eluted at 45 to 60 kd and was free of IL-1 but partially overlapped with rabbit TNF alpha. Although active in vivo in PMNL recruitment into the tissues, these fractions did not induce PMNL migration in vitro in a filter chemotaxis assay. After sodium dodecyl sulfate (SDS), polyacrylamide gel electrophoresis (PAGE) the predominant PMNL recruiting factor (PRF) eluted from gel slices corresponded to 22 to 32 kd, suggesting that this protein is a dimer under gel filtration conditions. These gel eluates did not contain TNF alpha activity. Following iv administration of sublethal doses of LPS (3 micrograms/kg) or of antibiotic killed Escherichi coli (10(9)/kg), peripheral lung fragments from perfused lungs spontaneously produced this PRF during ex vivo culture without further LPS stimulation. Lung tissue from normal rabbits did not release PRF spontaneously. We conclude that resident alveolar Møs produce a PRF protein in response to LPS that is distinct from IL-1, TNF alpha, and chemotactic factors and that the production of a similar protein by lung cells (probably Møs) is probably induced in vivo during endotoxemia or bacteremia. This factor may contribute to PMNL accumulation in the lung during pathologic processes.

Neutrophil-activating peptide 1/interleukin 8 mRNA expression and protein secretion by human monocytes: effect of cyclosporin A

Neutrophil-activating peptide 1/interleukin 8 (NAP-1/IL-8) is a recently described cytokine with potent chemotactic activity for human neutrophil granulocytes (PMN) and T cells. In psoriasis, a chronic hyperproliferative and inflammatory skin disorder, PMN and T cells are found as prominent cells in the inflammatory infiltrate of the lesions; however, monocytes were shown to be the first cells invading a newly formed plaque. NAP-1/IL-8 was found to be present in high amounts in the skin and in scale material of psoriatic patients. Psoriasis responds well to systemic treatment with cyclosporin A (CsA), an immunosuppressive peptide. Therefore, we addressed the question of whether the clinical improvement of psoriatic patients during CsA therapy may be due to an inhibition of NAP-1/IL-8 production and secretion from monocytes. Purified human monocytes were stimulated by lipopolysaccharide in the presence or absence of various concentrations of CsA. Production of NAP-1/IL-8 was determined as expression of specific mRNA by fluorescent in situ hybridization. Secreted peptide was measured by bioassay (PMN chemotaxis) and enzyme-linked immunosorbent assay (ELISA) using specific monoclonal antibodies. The results show that CsA neither inhibited mRNA expression for NAP-1/IL-8 nor secretion of the peptide. These findings support the hypothesis that the pharmacological effect of CsA may be restricted to the inhibition of T-cell activation and proliferation.

1,25(OH)2-D3 is a potent regulator of interleukin-1 induced interleukin-8 expression and production

Interleukin 8 (IL-8) is a potent leukocyte chemotactic and activating cytokine produced by keratinocytes, fibroblasts, peripheral blood monocytes (PBMC) and endothelial cells. IL-8 is believed to play an important role in the development of inflammation and is thus an obvious target for therapeutical modulation. We studied the possible effect of an endogenous immune modulator 1,25(OH)2-cholecalciferol (1,25(OH)2-D3) on the IL-1-induced IL-8-production by several types of cells. 1,25(OH)2-D3 inhibited the IL-1-alpha induced IL-8 production and mRNA expression in keratinocytes, fibroblasts and PBMC, but not in endothelial cells. Optimal vitamin concentrations varied between 10(-10) and 10(-11) M. These results suggest a potential role of this hormone in the regulation of chemotactic cytokine production.

Adenovirus E3 14.7K protein functions in the absence of other adenovirus proteins to protect transfected cells from tumor necrosis factor cytolysis

A 14,700-kDa protein (14.7K) encoded by the E3 region of adenovirus has been shown to protect adenovirus-infected mouse C3HA cells from lysis by tumor necrosis factor (TNF) (L. R. Gooding, L. W. Elmore, A. E. Tollefson, H. A. Brady, and W. S. M. Wold, Cell 53:341-346, 1988). These infected cells are sensitized to TNF by expression of the adenovirus E1A proteins (P. Duerksen-Hughes, W. S. M. Wold, and L. R. Gooding, J. Immunol. 143:4193-4200, 1989). In this study we show that 14.7K suppresses TNF cytolysis independently of adenovirus infection. Mouse C3HA and C127 cells were transfected with the 14.7K gene controlled by the mouse metallothionein promoter, and permanent 14.7K-expressing cell lines were tested for sensitivity to TNF cytolysis. Transfected cells which were sensitized to TNF either by inhibitors of protein synthesis, microfilament-destabilizing agents, or adenovirus infection were found to be resistant to TNF cytolysis. Two monoclonal antibodies were isolated and used to quantitate 14.7K in transfected and infected cells. Enzyme-linked immunosorbent assay (ELISA) analysis with these monoclonal antibodies and 14.7K immunoblots showed that 14.7K expression can be induced with cadmium in C3HA and C127 transfectants. The 14.7K induction correlated with a dose-dependent decrease in sensitivity to TNF cytotoxicity. The 14.7K protein does not substantially alter cell surface TNF receptor numbers or affinity on C3HA mouse fibroblasts, as determined by Scatchard analysis of 125I-TNF binding. The 14.7K protein also does not alter TNF signal transduction in general, because TNF induction of cell surface class I major histocompatibility complex molecules on 14.7K transfectants was unmodified. Our findings indicate that the adenovirus 14.7K protein functions as a specific inhibitor of TNF cytolysis in the absence of other adenovirus proteins and thus is a unique tool to study the mechanism of TNF cytotoxicity.

Neutrophil recruitment by intradermally injected neutrophil attractant/activation protein-1

Neutrophil attractant/activation protein-1 (NAP-1) is a recently described cytokine that attracts neutrophils, but not monocytes or eosinophils. This leukocyte specificity is not absolute, in that NAP-1 attracts basophils and small numbers of lymphocytes. Our purpose was to determine in vivo effects of NAP-1, and to compare them to the reported action of the complement attractant, C5a. Intradermal injection into normal human subjects of 40 microliters of NAP-1, over a concentration range of 4 x 10(-8) M to 10(-6) M, caused no symptoms or signs such as wheal-and-flare, itching, induration, or tenderness. However, biopsies of injection sites showed perivascular neutrophil infiltration as early as 30 min, which increased at 1 and 3 h. The mean number of neutrophils per mm2 of dermis for 15 biopsies taken 3 h after intradermal injection of 2 x 10(-7) M or 10(-6) M NAP-1 was 164 +/- 41; the response to saline or a NAP-1 inactive fragment was 5 or less. Intradermal NAP-1 did not cause basophil or lymphocyte infiltration. Consistent with the absence of a wheal-and-flare, acid toluidine blue-stained sections showed no evidence of mast cell degranulation, in contrast to previously reported results with C5a. Thus, the predominant response by human subjects to intradermal NAP-1 was neutrophil accumulation in proximity to dermal blood vessels.

Genetic control of cell-mediated immunity in chickens

The present review briefly outlines the effector cells and molecules influencing cell-mediated immunity. Emphasis is placed on the genes determining these molecules in mammals and in the chicken, including genes for cytokines and cytokine receptors. The review concludes with a tabular presentation containing examples of specific genetic influences on cell-mediated immunity in chickens and mammals.

Inhibition of interleukin 1 (IL-1) binding and bioactivity in vitro and modulation of acute inflammation in vivo by IL-1 receptor antagonist and anti-IL-1 receptor monoclonal antibody

Recombinant human interleukin 1 receptor antagonist (IL-1ra) and 35F5, a neutralizing monoclonal antibody (mAb) to the type I mouse IL-1 receptor, were examined for their ability to bind to IL-1 receptors (IL-1Rs) on various types of mouse cells and to block immune and inflammatory responses to IL-1 in vitro and in mice. IL-1ra competed for binding of 125I-IL-1 alpha to type I IL-1R present on EL-4 thymoma cells, 3T3 fibroblasts, hepatocytes, and Chinese hamster ovary cells expressing recombinant mouse type I IL-1R. The IC50 values for IL-1ra binding (ranging from 2 to 4 ng/ml) were similar to those of IL-1 alpha. In contrast, IL-1ra bound with very low affinity (IC50 values ranging from 10 to 200 micrograms/ml) to cells expressing type II IL-1R, i.e., 70Z/3 pre-B cell line and polymorphonuclear leukocytes (PMN) derived from bone marrow and acute inflammatory exudates. The mAb 35F5 bound specifically to type I IL-1R; no inhibition of 125I-IL-1 alpha binding to cells having type II IL-1R was observed with very high concentrations of antibody. While neither IL-1ra nor 35F5 had intrinsic activity in bioassays using T helper D10.G4.1 cells and mouse thymocytes, both agents blocked the ability of IL-1 to stimulate proliferation of these cells. The effects of IL-1ra and 35F5 on acute inflammatory responses in mice were also evaluated. IL-1ra and 35F5 blocked the local accumulation of PMN after intraperitoneal injection of rIL-1 alpha. The response to IL-1 was inhibited when IL-1ra or 35F5 was administered simultaneously with or before administration of IL-1. IL-1ra and 35F5 also blocked PMN accumulation after intraperitoneal injection of lipopolysaccharide or proteose peptone, suggesting IL-1 is important in mediating responses to these agents. In addition, IL-1ra and 35F5 significantly blocked the ability of IL-1 to stimulate egress of PMN from bone marrow, to induce a transient neutrophilia, and to elevate serum levels of hepatic acute phase proteins, IL-6, and corticosterone. Thus, IL-1ra and 35F5 competitively inhibit the binding of IL-1 to the IL-1R on certain cell types. These two IL-1 receptor antagonists act to inhibit biological responses induced by IL-1 and other inflammatory agents.

Urate crystals stimulate production of tumor necrosis factor alpha from human blood monocytes and synovial cells. Cytokine mRNA and protein kinetics, and cellular distribution

Crystals of monosodium urate (MSU) provide a dose-dependent stimulus for the production by human blood monocytes of tumor necrosis factor (TNF), a cytokine with proinflammatory properties; TNF activity was inhibited selectively by monoclonal antibody to TNF alpha. Biologically active cell-associated TNF activity peaked at 3 h and was exceeded at 6 h by extracellular activity, which peaked at 12-18 h. Comparable kinetics were observed with immunoreactive TNF alpha. TNF alpha mRNA accumulation in monocytes stimulated with MSU crystals appeared as a single peak at 2-4 h, kinetics compatible with rapid production of a short half-life transcript. In contrast, crystals of calcium pyrophosphate or of hydroxyapatite did not stimulate significant production of TNF or of message. Fresh tophaceous material from a patient with gout contained significant levels of TNF alpha and cells cultured from the tophus produced TNF alpha in vitro. In rheumatoid synovial cells, spontaneous release of TNF alpha was increased by in vitro exposure to MSU crystals. Taken together with earlier work, these results support an expanded view of gouty inflammation in which the crystal-stimulated production of cytokines provides a crucial link between crystal deposition and many of the clinical and pathological facts of both acute and chronic gouty arthritis.

Cytokines: an overview

Cytokines are a broad, heterogeneous group of proteins and polypeptides that regulate intercellular communication. Examples of cytokines include interleukins, interferons, colony-stimulating factors, and a variety of growth factors. The preparation of large quantities of highly purified recombinant cytokines has provided a basis for their biological and physicochemical characterization. The pleiotropic biological effects of these factors are expressed through binding to specific, high-affinity cell-surface receptors. Although they are different in amino acid sequence, cytokines have a number of biological and physicochemical properties in common.

Interleukin-1 beta and tumor necrosis factor-alpha induce gene expression and production of leukocyte chemotactic factors, colony-stimulating factors, and interleukin-6 in human mesangial cells

The capacity of human cultured mesangial cells to produce soluble factors potentially relevant for mechanisms of inflammation and immunity at the glomerular site was analyzed. The nature of the secreted factors initially was investigated by Northern blot analysis using total cellular RNAs isolated from resting and activated mesangial cells. On exposure of mesangial cells to human recombinant interleukin-1 beta (IL-1 beta), high levels of interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) mRNAs were detected. Similar transcripts were found after stimulation with human recombinant tumor necrosis factor-alpha (TNF-alpha). Active secretion of IL-8 was documented by radioimmunoassay in supernatants of mesangial cells activated by either IL-1 beta or TNF-alpha. Using an in vitro migration assay, supernatants from resting mesangial cells were found to be devoid of any chemotactic activity for granulocytes or monocytes. On stimulation with IL-1 beta, however, mesangial cell supernatants expressed MCP-1 biologic activity detected as induction of a strong migratory response for human monocytes but not for granulocytes. In addition, IL-1 beta and TNF-alpha induced high levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) mRNAs. Similarly IL-1 beta and TNF-alpha induced the interleukin-6 (IL-6) gene and active secretion of its mature protein. These data strongly support an effector role for mesangial cells in modulating immune-inflammatory responses in glomeruli. Release of cytokines may activate not only infiltrating inflammatory cells through short paracrine pathways, but also mesangial cells themselves through an autocrine pathway.

Retinoic acid receptor gene expression in human skin

Human skin exhibits a characteristic, pleiotypic response to topical retinoic acid. In attempting to understand this response at the molecular level, we have used fast protein liquid chromatography (FPLC) and RNA blot hybridization to characterize the expression of the nuclear retinoic acid receptor (RAR) alpha, beta, and gamma genes in adult human epidermis. Size exclusion FPLC of 0.6 M NaCl nuclear extracts prepared from keratome biopsies revealed two peaks of specific [3H] retinoic acid (RA) binding at Mr 45 and 18 kDa, in agreement with the expected sizes of RAR and cellular RA binding protein. Blot hybridization analysis of total RNA extracted from keratome biopsies revealed that RAR-gamma was the predominant RAR species expressed in human epidermis, as RAR-alpha transcripts were detectable only at low levels and RAR-beta transcripts were undetectable. RAR transcripts were not induced by topical treatment with 0.1% RA cream under occlusion for 4 h or 4 d. Moreover, there was no significant difference in RAR-gamma transcript levels in normal and psoriatic epidermis. RAR-gamma transcripts were constitutively expressed not only in cultured human keratinocytes, but also in human dermal and lung fibroblasts. RAR-beta was induced by RA in dermal fibroblasts, but not in keratinocytes. RA induced IL-1 beta transcripts in keratinocytes rapidly (2 to 4 h) and at low concentrations (3 x 10(-10) M), consistent with activation of the IL-1 beta gene via RAR. These results demonstrate constitutive expression of RAR-gamma in human epidermis, and suggest that RAR-gamma is a molecular target of RA action in adult human skin.

Induction of neutrophil-mediated cartilage degradation by interleukin-8

Neutrophil influx into the inflamed joint is a characteristic feature of disease flares in patients with rheumatoid arthritis. Recently, a protein produced by monocytes and fibroblasts that has chemoattractive/activating properties for neutrophils has been identified and characterized. This protein has been called interleukin-8 (IL-8). In this study, we cocultured neutrophils with 35S-sulfate-labeled cartilage and found that the addition of recombinant human IL-8 (rHuIL-8) caused rapid, neutrophil-mediated cartilage degradation that was the result of induction of neutrophil degranulation by the cytokine. With 10(-7)M rHuIL-8, 23% of the radiolabel was released into the culture medium in 4 hours, compared with a 9% release without the factor. At concentrations of up to 10(-6)M, rHuIL-8 had no direct effect upon cartilage breakdown. These findings indicate that IL-8 may participate in the pathogenesis of rheumatoid arthritis through the induction of neutrophil-mediated cartilage damage.

Monocyte-macrophage differentiation induced by human upper airway epithelial cells

We examined the ability of conditioned medium (CM) generated by human upper airway epithelial (Ep) cells from normal (NN) and inflamed, allergic rhinitis (AR) and nasal polyp (NP) tissues to induce monocytic differentiation of hemopoietic progenitors of the HL-60 myeloid leukemia cell line in vitro. In HL-60 cells cultured in RPMI with 10% FBS, there was differentiation to 0.4 +/- 0.4% monocytic cells. NN-, AR-, and NP-EpCM induced differentiation to 23 +/- 6%, 42 +/- 11%, and 71 +/- 10% monocytic cells, respectively. EpCM also induced isolated peripheral blood nonadherent mononuclear cells to express monocyte/macrophage-specific antigens as detected by immunohistochemistry using FMC-32 monoclonal antibodies (anti-CD14). We also examined the cytokine content of these EpCMs and found that they contained granulocyte/macrophage colony-stimulating factor (GM-CSF): 126 +/- 35, 198 +/- 22, and 489 +/- 118 pg/ml for NN-, AR-, and NP-EpCM, respectively. These CMs also contained granulocyte-CSF (G-CSF) and interleukin-6 (IL-6), but there were no significant differences between normal and inflamed tissue-derived cell supernatants. No macrophage-CSF (M-CSF) was detected in these EpCMs. Recombinant human GM-CSF, G-CSF, and IL-6, alone and in combinations, at doses similar to or greater than those found in the EpCMs, did not induce comparable monocytic differentiation of HL-60 cells. Preincubation of the EpCM with neutralizing anti-GM-CSF, anti-G-CSF, or anti-IL-6 antibodies did not significantly inhibit the monocytic differentiation induced by the EpCM.(ABSTRACT TRUNCATED AT 250 WORDS)

Post-transcriptional regulation of gro alpha, beta, gamma, and IL-8 mRNAs by IL-1 beta

Expression of the cytokine gene gro, also known as melanoma growth stimulatory activity, is induced by inflammatory stimuli, including IL-1. To determine whether gro expression is regulated at a post-transcriptional level, the effect of IL-1 on gro mRNA stability was examined. Treatment of fibroblasts with IL-1 beta caused a dose-dependent induction of gro mRNA. When IL-1 was withdrawn, gro mRNA decayed rapidly with a half life of 1 hour. This decay occurred whether or not actinomycin D was added to block new transcription. In contrast, when IL-1 was present in the medium, the level of gro mRNA was stable over 8 hours following addition of actinomycin D. In addition, the stability of a related mRNA, IL-8, was found to be regulated by IL-1. To examine whether Northern results reflected expression of gro alpha, or of the closely related genes, gro beta and gro gamma, RNA samples were analyzed by PCR. All three genes were found to be induced by IL-1 and all mRNAs were stabilized in the presence of IL-1. Northern analysis revealed a minor species of gro mRNA which lacked poly(A). The pattern of expression of this RNA suggested that it was a decay intermediate of one or more of the gro mRNAs. The findings indicate that mRNA stabilization is an important component of IL-1 induced gene expression.

The priming effects of the products of stimulated mononuclear cells on the response of neutrophils to C5a des arg

Certain recombinant human cytokines have been shown to enhance polymorphonuclear leucocyte (PMN) responses to subsequent stimulation. Mononuclear cells (MNC) from normal healthy individuals were stimulated for 5 h with 1 micrograms/ml bacterial lipopolysaccharide (LPS) in order to induce production and secretion of inflammatory cytokines into the surrounding medium. These mononuclear cell conditioned media (MNCM) were then used to prime PMN isolated from healthy volunteers. Preincubating the PMN with MNCM for 15 min at 4 degrees C followed by washing and warming to 37 degrees C caused a 344% increase (n = 26) in the rate of superoxide anion production in response to zymosan-activated serum (ZAS), a source of C5a des arg. This effect could not be reproduced with recombinant human forms of interleukin 1 beta (Il-1 beta) or granulocyte-macrophage-colony stimulating factor (GM-CSF), although, with the latter, there was some effect when the preincubation stage was carried out for 60 min at 37 degrees C. Only recombinant human tumour necrosis factor-alpha (rh-TNF-alpha) gave a similar PMN priming effect to that seen with MNCM. This effect could not be reversed by washing away either the MNCM or rh-TNF-alpha. The priming effect could be markedly reduced (74.8%, n = 6) by employing the use of polyclonal antibody to TNF-alpha in the preincubation step; assaying for TNF-alpha in these MNCMs showed that the degree of priming corresponded to the amount of TNF-alpha present. Rh-TNF-alpha alone appeared to have very little direct stimulatory effect on respiratory burst activity. The results show that TNF-alpha produced by LPS stimulated MNC after 5 h binds to a PMN surface receptor in the cold and warming of the cells to 37 degrees C allows for an immediate and dramatic response to ZAS stimulation. This suggests that TNF-alpha is the important cytokine upregulating PMN responses to other physiological mediators, including C5a des arg during the early phases of an inflammatory reaction.

Recombinant human interleukin-8 is a potent activator of canine neutrophil aggregation, migration, and leukotriene B4 biosynthesis

Interleukin-8 (IL-8), formerly known as NAP-1, is formed by a variety of cells upon stimulation with IL-1 or tumor necrosis factor (TNF). The biologic activity of the cytokine involves activation of almost every neutrophil function studied so far in different species. In the present study, we compared the effects of recombinant human IL-8 (rIL-8) and the lipid mediators, leukotriene B4 (LTB4) and platelet-activating factor (PAF), on neutrophil functions in dogs. All three chemotactic factors induced neutrophil aggregation and chemotaxis, with rIL-8 being far more potent than LTB4 and PAF. The migration induced by rIL-8 was significantly greater than that observed towards LTB4 and PAF. In the aggregation assay, rIL-8 was shown for the first time to be a potent stimulant. The aggregation response was more persistent than that obtained with LTB4 and PAF and the potency of rIL-8 was greater. An intradermal dose-response study showed that rIL-8 is an extremely potent inducer of selective neutrophil infiltration in canine skin. The infiltration was more pronounced than following injection of LTB4 or PAF. It was proposed that the superior effect of rIL-8 was caused by a synergistic effect between injected rIL-8 and LTB4, which was shown to be produced in biologically active amounts by canine neutrophils stimulated with rIL-8. From a therapeutic point of view, the simultaneous presence of rIL-8 and LTB4 in inflammatory skin diseases highlights the need to develop drugs that inhibit the production and/or effect of both mediators.