Purification to homogeneity and amino acid sequence analysis of two anionic species of human interleukin 1

Mechanistically identified suitable biomarkers of exposure, effect, and susceptibility for silicosis and coal-worker's pneumoconiosis: a comprehensive review

Clinical detection of silicosis is currently dependent on radiological and lung function abnormalities, both late manifestations of disease. Markers of prediction and early detection of pneumoconiosis are imperative for the implementation of timely intervention strategies. Understanding the underlying mechanisms of the etiology of coal workers pneumoconiosis (CWP) and silicosis was essential in proposing numerous biomarkers that have been evaluated to assess effects following exposure to crystalline silica and/or coal mine dust. Human validation studies have substantiated some of these proposed biomarkers and argued in favor of their use as biomarkers for crystalline silica- and CWP-induced pneumoconiosis. A number of "ideal" biological markers of effect were identified, namely, Clara cell protein-16 (CC16) (serum), tumor necrosis factor-alpha (TNF-alpha) (monocyte release), interleukin-8 (IL-8) (monocyte release), reactive oxygen species (ROS) measurement by chemiluminescence (neutrophil release), 8-isoprostanes (serum), total antioxidant levels measured by total equivalent antioxidant capacity (TEAC), glutathione, glutathione peroxidase activity, glutathione S-transferase activity, and platelet-derived growth factor (PDGF) (serum). TNF-alpha polymorphism (blood cellular DNA) was identified as a biomarker of susceptibility. Further studies are planned to test the validity and feasibility of these biomarkers to detect either high exposure to crystalline silica and early silicosis or susceptibility to silicosis in gold miners in South Africa.

Generation of Biologically Active IL-1β by Matrix Metalloproteinases: A Novel Caspase-1-Independent Pathway of IL-1β Processing

Biologic activity of IL-1β requires processing of the inactive precursor, a function generally ascribed to IL-1β-converting enzyme (caspase-1). However, alternative mechanisms of IL-1β activation have been postulated in local inflammatory reactions. Expression of IL-1β and matrix metalloproteinases (MMPs) frequently occurs simultaneously at sites of inflammation. We describe here that stromelysin-1 (MMP-3), as well as the gelatinases A (MMP-2) and B (MMP-9), processes recombinant human IL-1β precursor (pIL-1β) into biologically active forms. Detection of both pIL-1β processing and biologic IL-1β activity demonstrated different processing capacities of the respective MMPs. Conversion of pIL-1β by stromelysin-1 required coincubation for at least 1 h, and biologic activity faded after 8 h to 24 h. Gelatinase A was less effective in processing pIL-1β, requiring at least 24 h of coincubation. In contrast, gelatinase B processed pIL-1β within minutes, resulting in immunoreactive products as well as biologic activity stable for 72 h. In addition, prolonged incubation of mature IL-1β with stromelysin-1, and to a lesser extent also with gelatinases, but not with interstitial collagenase, resulted in the degradation of mature IL-1β. None of the MMPs processed the second isoform of IL-1, IL-1α. The present study indicates a biphasic regulation of IL-1β activity by MMPs: a caspase-1-independent pathway of IL-1β activation and inhibition of IL-1β activity by degrading the mature cytokine. The balance of the respective MMPs and pIL-1β might regulate the long term appearance of IL-1β activity at sites of acute or chronic inflammation.

Biologically active, alternatively processed interleukin-1 beta in psoriatic scales

The aims of the present work were to elucidate the biochemical properties of interleukin-1 beta (IL-1 beta) in psoriatic scales to get information on the processing of epidermal IL-1 beta in psoriasis, and to elucidate whether the IL-1 beta in psoriatic scales possesses biological activity. By means of ion exchange chromatography, IL-1 beta in extracts of psoriatic scales was purified to a stage where it could be analyzed with electrophoretic methods and immunoblotting. Compared to mature recombinant human IL-1 beta (Ala 117 IL-1 beta), IL-1 beta in psoriatic scales had a slightly higher apparent molecular mass and a more acidic isoelectric point, as revealed by two-dimensional electrophoresis under denaturing conditions. Isoelectric focusing under non-denaturing conditions of IL-1 beta partially purified from psoriatic scales, or from non-inflamed plantar stratum corneum (Nylander Lundqvist, E., Bäck, O. and Egelrud, T., J. Immunol. 1996. 157: 1699), and of mature IL-1 beta, followed by immunoblotting with IL-1 beta-specific antibodies, showed that psoriatic scales contained two components with IL-1 beta-like immunoreactivity which were isoelectric at pH 6.1 and 6.3, respectively. These components could also be detected in extracts of plantar stratum corneum, which also contained small amounts of an IL-1 beta-like component isoelectric at pH 6.9. Mature IL-1 beta was isoelectric at pH 6.9. No IL-1 beta-like biological activity could be detected in crude extracts of psoriatic scales. These extracts also contained high amounts of IL-1 receptor antagonist. Partially purified preparations of IL-1 beta from psoriatic scales, in which an apparently total separation of IL-1 beta and IL-1 receptor antagonist had been achieved, could induce expression of E-selectin in human umbilical vein endothelial cells. This activity was inhibited by antibodies specific for IL-1 beta, but not by antibodies specific for IL-1 alpha. It is concluded that psoriatic scales contain biologically active IL-1 beta, which has been processed by a mechanism which may be similar to that present in non-inflamed plantar stratum corneum, and which does not involve IL-1 beta converting enzyme.

Role of interleukin-1 beta converting enzyme (ICE) in acute myelogenous leukemia cell proliferation and programmed cell death

The proinflammatory cytokine interleukin (IL)-1 has been shown to play a pivotal role in stimulating acute myelogenous leukemia (AML) cell proliferation. The gene for its prominent IL-1 beta form produces a 31-kDa precursor protein (pro-IL-1 beta) that is biologically inactive unless cleaved to its mature form by a cytoplasmic cysteine protease termed Il- 1 beta converting enzyme (ICE). Although ICE was first thought to be a unique enzyme with a single biologic activity, several investigators have demonstrated that ICE shares sequence homology with the protein product of ced-3, the gene for cell death of the nematode Caenorhabditis elegans, and induces apoptosis in different experimental models. It was therefore hypothesized that ICE may either augment the production of mature IL-1 beta and stimulate the proliferation of cells, in which IL-1 beta acts as an autocrine growth factor, or induce apoptosis. Recent data indicate that ICE is a member of an increasingly recognized family of cysteine proteases. Unlike ICE, the other members of this family do not cleave pro-IL-1 beta but are effective inducers of apoptotic cell death, whereas ICE acts primarily as an IL-1 beta converting enzyme. Because IL-1 beta serves as either an autocrine or paracrine growth factor in AML, we recently investigated the effect of ICE inhibition on AML colony growth and found that ICE inhibition reduced the production of mature IL-1 beta and suppressed AML progenitor proliferation. Our data suggest that ICE does not function as an apoptosis gene in AML but rather increases mature Il-1 beta production and AML cell proliferation. It is possible, therefore, that ICE inhibitors may be beneficial in AML therapy.

Structure and function of interleukin-1 beta converting enzyme

An overwhelming body of evidence has shown that IL-1 beta is a major mediator of inflammatory disease (Tocci and Schmidt, 1996). The discovery of ICE, a unique processing enzyme involved in the production of active IL-1 beta, has provided a new approach to specifically block the production of this potent cytokine. Consequently, the discovery and development of inhibitors against the enzyme could hold great promise therapeutically. Potent inhibitors of the enzyme would be useful in the treatment of a number of important inflammatory diseases and potentially in the management of leukemia (Arend, 1993b; Estrov and Talpaz, 1996). A number of key questions must be answered before the therapeutic potential of such inhibitors can be realized. The development of a pharmaceutically acceptable cysteine proteinase inhibitor will almost certainly involve new chemical strategies gauged at safely inactivating the enzyme. For such inhibitors, it will be necessary to achieve selectivity for ICE from among the growing number of ICE family members while retaining potency. It will also be important to establish the level of inhibition of IL-1 beta required to achieve therapeutic efficacy. The studies comparing IL-1 beta- and ICE-deficient mice suggest that complete abrogation of IL-1 beta is required to achieve efficacy in models of inflammation. It is not known if this is the case in humans. Understanding the source of the residual IL-1 beta produced in ICE-deficient mice will be important in order to ascertain if a similar mechanism could generate active IL-1 beta in patients receiving if a ICE inhibitor. As for ICE itself, a number of formidable questions remain regarding its regulation and mechanism of activation. Answering these questions experimentally will present a major challenge due to the extremely low levels of enzyme present in cells. Studies on other family members may provide easier access to some of these questions and provide clues that can be applied to ICE. The components of the pathway involved in IL-1 trafficking and secretion are unknown, as are the mechanisms of ICE activation and regulation. Clearly other cellular proteins that have yet to be discovered will be involved in each of these processes, opening up new avenues of research in this field.

Tissue distribution of human gliostatin/platelet-derived endothelial cell growth factor (PD-ECGF) and its drug-induced expression

Human tissue contents of gliostatin/platelet-derived endothelial cell growth factor (PD-ECGF) and its drug-induced expression in tumor cells were currently examined by a sandwich enzyme immunoassay (EIA) system and a reverse transcription-polymerase chain reaction (RT-PCR) method. Gliostatin/PD-ECGF was found to distribute in rather ubiquitous than specific human tissues and organs, with a relatively high levels in the tissues of digestive system (esophagus and rectum), brain, spleen, bladder and lung, but not in gall bladder, aorta, muscle, fat and kidney. Most of examined human tumor cell lines showed 4- or 5-fold higher contents (21.5 +/- 3.9 ng/mg protein) than normal tissue contents (4.4 +/- 1.1 ng/mg protein) on the average. While gliostatin/PD-ECGF is known to lack a signal sequence, some tumor cells (A431 and MKN74) appeared to release it into the conditioned medium. Expression of gliostatin/PD-ECGF in epidermoid carcinoma cell (A431) and stomach cancer cell (MKN45) was induced by dibutyryl cyclic AMP and phorbol ester, and uniquely in MKN45 by hydrocortisone. In particular, this hydrocortisone specifically caused an increase of the apparent secretion of MKN74 without its cytotoxic effects, suggesting a possible secretion of gliostatin/PD-ECGF in the restricted but not universal cell line. Biological significance on the chemical induction of gliostatin/PD-ECGF in tumor cells and on its extracellular secretion are discussed.

Leucocyte interleukin-1-like activity in the common seal (Phoca vitulina) and grey seal (Halichoerus grypus)

Interleukin-1 (IL-1) is an important cytokine with predominantly proinflammatory activities, which have been characterized in many mammals. This study showed the production of IL-1-like bioactivity by cultured seal leucocytes. Increasing concentrations of lipopolysaccharide (LPS) (0-1 micrograms/ml) stimulated an increase in measurable IL-1-like activity in cell culture supernates. This activity increased for the first 24 h after LPS stimulation and the substance responsible had an apparent molecular weight of 17 kDa on gel filtration, similar to that described for other species. Specificity of the bioassay used was confirmed by blocking the bioactivity with an IL-1 receptor antagonist (IL-1 ra).

Resistance to fever induction and impaired acute-phase response in interleukin-1 beta-deficient mice

We used gene targeting in embryonic stem cells to introduce an IL-1 beta null allele in mice. The IL-1 beta-deficient mice develop normally and are apparently healthy and fertile. The IL-1 beta null mice responded normally in models of contact and delayed-type hypersensitivity or following bacterial endotoxin LPS-induced inflammation. The IL-1 beta-deficient mice showed equivalent resistance to Listeria monocytogenes compared with wild-type controls. In contrast, when challenged with turpentine, which causes localized inflammation and tissue injury, the IL-1 beta mutant mice exhibited an impaired acute-phase inflammatory response and were completely resistant to fever development and anorexia. These results highlight a central role for IL-1 beta as a pyrogen and a mediator of the acute-phase response in a subset of inflammatory disease models, and support the notion that blocking the action of a single key cytokine can alter the course of specific immune and inflammatory responses.

Interleukin-1 and its inhibitors: implications for disease biology and therapy

IL-1 alpha and IL-1 beta are polypeptide hormones that exhibit a broad spectrum of beneficial and harmful biologic activities. Clinical trials designed to benefit from its stimulatory effects on human hematopoiesis and from its role in improving host defenses, are being currently conducted. Other in vivo studies, using IL-1 inhibitors with an attempts to block the detrimental effects of IL-1, are underway. Because of the multifunctional effects of IL-1 in human physiology and its pathogenetic role in several diseases, the capability to control the effects of IL-1 may prove to be a useful tool in medical practice.

Recombinant cytokines as immunological adjuvants

This paper describes the bacterial expression and purification of bioactive recombinant ovine interleukin-2 (rovIL-2), interleukin-1 alpha (rovIL-1 alpha) and tumour necrosis factor alpha. These purified proteins had specific activities in appropriate bioassays of 1 x 10(7) 1 x 10(7) and 1 x 10(5) U/mg, respectively. Recombinant ovIL-1 alpha was assessed as an immunological adjuvant for the sheep response to the model protein avidin. When delivered either intradermally or intramuscularly in conjunction with avidin in aluminium hydroxide the rovIL-1 alpha significantly enhanced the secondary humoral response. Doses of 1, 10 or 100 micrograms per sheep enhanced the humoral response to a similar extent. Recombinant ovIL-1 beta had similar adjuvant activity in that it was demonstrated to significantly enhance the sheep humoral response to an experimental H. contortus antigen. This increase in specific antibody, however, did not correlate with enhanced protection against infection with third stage H. contortus larvae. In addition incorporation of rovIL-1 beta into the formulation was shown not to alter the isotype profile of H. contortus antigen specific antibody.

Early circulating erythroid progenitors (BFU-E) in sickle cell anemia

Sickle cell anemia (SS) patients can be divided into two sub-populations according to peripheral HbF levels. Patients with low (< 9%) HbF levels (LFSS) are characterized by an increased number of circulating BFU-E in active DNA synthesis, and release of burst promoting activity (BPA) by unstimulated low density (LD) adherent cells. In contrast, circulating BFU-E from SS patients with high (> 9%) HbF levels (HFSS) are normal in number, largely in resting phase, and their LD cells do not release BPA-like activity. More recently further heterogeneity has been found among these two groups. In LFSS patients GM-CSF is constitutively produced by unstimulated monocytes. In contrast, HFSS patients' adherent cell depletion increases cycling of BFU-E in culture. CM from HFSS patients inhibits BFU-E expression in culture. Hence, LD adherent cells from HFSS patients may release an inhibitory factor(s). The nature of this factor has to be determined. In addition, there are distinct subpopulations of BFU-E responsiveness to growth factor (GM-CSF, IL-3): a) LFSS patients have a homogeneous BFU-E population, equally responsive to GM-CSF and IL-3; b) HFSS patients, in addition to this subpopulation, have a subset of BFU-E dependent exclusively on IL-3 which is 20 to 40% of the total number of circulating BFU-E. This is similar to BFU-E from normal individuals. Hence, LFSS BFU-E represent an actively proliferating population, equally responsive to GM-CSF and IL-3, controlled by at least constitutively produced GM-CSF and possibly other factors. These observations suggest a significant modification in BFU-E behavior in the subset of SS patients with low HbF levels and high hemopoietic stress. The heterogenous regulation of BFU-E in SS disease seems to be an epiphenomenon of HbF levels, and not vice-versa.

Cloning, expression and characterization of ovine interleukins 1 alpha and beta

Ovine interleukin 1 alpha (IL-1 alpha) c-DNA, obtained by polymerase chain reaction, has been cloned into pTZ18R and pTZ19R. The resulting DNA sequence shows close homology with the bovine sequence. The derived amino-acid sequence shows conserved motifs similar to those observed in all species studied so far. No signal peptide is seen. Northern blots of RNA from lipopolysaccharide (LPS)-stimulated ovine alveolar macrophages show IL-1 beta m-RNA to be produced earlier than and to be more transient than IL-1 alpha m-RNA. c-DNAs coding for the IL-1 alpha proprotein and IL-1 alpha and IL-1 beta mature proteins have been cloned and expressed in the yeast Ty-VLP system as fusion proteins. The resultant IL-1 protein preparations, cleaved from their fusion partners by the action of activated coagulation Factor Xa, are 80-95% pure and show biological activity in standard thymocyte co-mitogen and cartilage degradation assays for IL-1. Some species specificity is observed in that sheep thymocytes are more responsive to ovine rIL-1 than are mouse thymocytes. The presence of a Factor Xa cleavage site in the IL-1 alpha proprotein suggests that Factor Xa may be involved in the processing of ovine IL-1 alpha to its mature form.

Enumeration of interleukin-1 alpha and beta producing cells by flow cytometry

A technique for intracytoplasmic immunofluorescence staining to detect and quantify human interleukin-1 alpha (IL-1 alpha) and beta (IL-1 beta) in CD4, CD8, and CD14 positive lymphoid cells is described. Mononuclear cells stimulated in vitro with PHA to produce IL-1, were fixed and made permeable to antibodies by sequential exposure to paraformaldehyde and the detergent n-octyl-glucoside. Cytoplasmic and surface staining of both forms of IL-1 were demonstrated by indirect fluorescence using IL-1 beta and IL-1 alpha specific mouse monoclonal antibodies and quantified with flow cytometry.

Production, purification and characterization of canine prostromelysin

One of the best studied animal models of osteoarthritis is a dog model in which the anterior cruciate ligament of the hind limb stifle joint is transected (Pond-Nuki model). To determine whether stromelysin might play a role in this model, it was necessary to purify the enzyme for production of suitable probes. In the present study, dog synovial fibroblasts were stimulated to express a metalloproteinase that was demonstrated to be canine prostromelysin by Northern blot, protein purification and amino-terminal sequence analyses. Unlike rabbit synoviocytes, passaged dog synoviocytes did not express stromelysin mRNA in response to recombinant human IL-1, but expressed stromelysin mRNA only upon treatment with dog monocyte-conditioned medium (dMCM). The aminophenylmercuric acetate (APMA)-activatable metalloproteinase present in the culture supernatants of stimulated dog synoviocytes was purified using a combination of ion-exchange and dye matrix affinity chromatography. The purified canine metalloproteinase co-migrated on reducing SDS-PAGE with recombinant human prostromelysin-1 as a doublet with apparent molecular masses of 54 and 56 kDa. Similar to APMA-activated human prostromelysin-1, the APMA-activated canine metalloproteinase was inhibited by 1,10-phenanthroline or recombinant human tissue inhibitor of metalloproteinase (TIMP). The amino-terminal sequences of the canine pro- and APMA-activated enzymes were compared with those of human, rabbit and rat stromelysin. The striking homologies among the sequences demonstrated that the purified canine metalloproteinase was indeed canine prostromelysin. A rabbit anti-canine prostromelysin polyclonal antiserum was generated and used to localize the enzyme within cultured dog synoviocytes and articular cartilage stimulated with dMCM. The reagents developed in this study should be useful for examining the expression and distribution of prostromelysin in canine models of osteoarthritis.

Molecular cloning and characterization of ovine IL-1 alpha and IL-1 beta

Interleukin-1 (IL-1) is a cytokine with a wide range of effects on a variety of cell types. By hybridization with human IL-1 alpha and IL-1 beta cDNA probes, the corresponding ovine cDNAs were isolated from a stimulated alveolar macrophage cDNA library. The sequences of these cDNAs showed that ovine IL-1 alpha and IL-1 beta encode proteins of 268 and 266 amino acids, respectively, with both the nucleotide and amino acid sequences showing a high degree of homology with their human, mouse and bovine equivalents. In a mammalian COS cell-expression system these cDNAs produced biologically active IL-1. Further experiments demonstrated the importance of sequences within the 3' untranslated portion of the cDNAs in determining the level of expression of these molecules. The analysis of expression of IL-1 alpha- and IL-1 beta-specific mRNA in response to endotoxin, phorbol myristic acid (PMA) or PMA plus ionomycin revealed a distinct pattern of differential regulation of the two genes. From genomic analysis both IL-1 alpha and IL-1 beta appear to exist as single copies in the ovine genome.

Identification of calcium-activated neutral protease as a processing enzyme of human interleukin 1 alpha

We describe here the involvement of calcium-activated neutral protease (CANP or calpain, EC 3.4.22.17) in calcium-dependent proteolytic processing of the precursor of human interleukin 1 alpha (IL-1 alpha) into mature IL-1 alpha. Calcium ionophore ionomycin enhanced proteolytic processing of pre-IL-1 alpha and the release of mature IL-1 alpha either from lipopolysaccharide (LPS)-activated human adherent mononuclear cells or from a human bladder carcinoma cell line (HTB9 5637) that constitutively produces human IL-1 alpha and -beta. The proteolytic processing of pre-IL-1 alpha was completely inhibited by EGTA. Similar calcium-dependent proteolytic processing of pre-IL-1 alpha was also observed with lysates of either LPS-activated human adherent mononuclear cells or HTB9 5637 cells. Since the optimal pH for processing was between 7 and 8, and E-64 (a cysteine protease inhibitor) and leupeptin (a serine and cysteine protease inhibitor) both inhibited this processing by cell lysates, we hypothesized that a calcium-activated neutral protease, CANP, might be responsible for this processing. This hypothesis was supported by data showing that the specific CANP inhibitor peptide inhibited this proteolysis in cell lysates in a dose-dependent fashion (IC50 = 0.05 microM) and that treatment of pre-IL-1 alpha with purified CANP yielded the 17-kDa mature form of IL-1 alpha, which has an amino terminus identical with that reported for mature human IL-1 alpha. Taken together, these findings indicate that calcium-dependent proteolytic processing of pre-IL-1 alpha is selectively mediated by CANP.

Comparison of biological and immunological activities of human monocyte-derived interleukin 1 beta and human recombinant interleukin 1 beta

Recombinant human interleukin 1 beta (rhIL-1 beta) and supernatants of Escherichia coli lipopolysaccharides-stimulated human monocyte (Mo) cultures, containing native human IL-1 beta (nhIL-1 beta), demonstrate significant differences when tested in the mouse co-stimulatory thymocyte (lymphocyte activating factor [LAF]) assay. The aims of the present study were to investigate this characteristic difference between rhIL-1 beta and Mo culture supernatants (Mo supernatants), and to compare the biological and the immunological activity of preparations of rhIL-1 beta and nhIL-1 beta during each step of an identical purification procedure. The biological activity of rhIL-1 beta/nhIL-1 beta preparations was characterized by the use of the LAF assay and the rat islet insulin release assay. An IL-1 beta enzyme-linked immunosorbent assay (ELISA) was established in order to compare the biological and immunological responses of the IL-1 beta preparations. We report that the significant difference between rhIL-1 beta and supernatants of Mo cultures, which was only demonstrable in the LAF assay, is due to the presence of interleukin 6 (IL-6) in the Mo supernatants. We describe a simple cation exchange chromatography separating nhIL-1 beta and IL-6 of Mo supernatants. The highly purified rhIL-1 beta possessing the correct amino-terminal sequence and nhIL-1 beta have identical biological and immunological activities demonstrating a specific biological activity (SBA) of 3 x 10(2) U/ng IL-1 beta. Thus, we have no indications of secondary or tertiary structural differences between rhIL-1 beta and purified nhIL-1 beta. In contrast, both in the LAF assay and in the rat islet insulin release assay the SBA of an amino-extended rhIL-1 beta form, Met-Glu-Ala-Glu-rhIL-1 beta, was only 1-2% of the SBA of rhIL-1 beta, suggesting that structural changes were introduced into the molecule by the amino-terminal extension. In the present study we have demonstrated that systematic combined testing of IL-1 beta preparations in two different biological assays and an immunological assay is useful for the characterization and comparison of the activity of recombinant and native IL-1 beta preparations purified by the use of exactly the same procedures.

Production and purification of prostromelysin and procollagenase from IL-1 beta-stimulated human gingival fibroblasts

Conditions were established to stimulate human gingival fibroblast explant cultures to synthesize milligram quantities of the metalloproteinase proenzymes, prostromelysin and procollagenase. To stimulate enzyme production, cells were treated with 1 nM recombinant human IL-1 beta for approximately 7 days under serum free conditions. Using a combination of rapid column chromatography steps, approximately 10 milligrams of prostromelysin and 5 milligrams of procollagenase were purified from 1 liter of conditioned media. Prostromelysin electrophoresed as a doublet with molecular weights of 55,57 kD, whereas, procollagenase migrated with slightly lower molecular weights of 52, 54 kD. Both proenzymes were treated with trypsin or aminophenylmercuric acetate to generate active species. The molecular weights of the active enzymes were approximately 10 kD smaller than the proenzymes. Active enzymes were inhibited by metal chelators and the natural metalloproteinase inhibitor, tissue inhibitor of metalloproteinase (TIMP), but not by the serine protease inhibitor, phenylmethylsulfonyl fluoride (PMSF). Activated stromelysin degraded a number of substrates including transferrin, proteoglycan monomer, proteoglycan aggregated with hyaluronic acid, and substance P. By contrast, collagenase degraded interstitial type I collagen and the peptide thioester, Ac-Pro-Leu-Gly-SCH(iBu)Co-Leu-GlyOEt. Identity of both enzymes were confirmed by amino-terminal protein sequence analysis as well as by immunoblot analysis using monoclonal antibodies.

Production and purification of bovine monocyte-derived interleukin 1

Few studies have addressed the biological and molecular nature of bovine interleukin 1 (IL-1). In an effort to increase our understanding of the role of bovine IL-1 in bovine immunology, we investigated various parameters of its production by LPS-stimulated monocytes in vitro. Bovine monocytes isolated by our methods constitutively released IL-1 activity, as measured by the murine thymocyte IL-1 assay. Monocyte release of IL-1 activity was further augmented when the cells were incubated with 0.005-10 micrograms per ml of Escherichia coli lipopolysaccharide (LPS). The presence of 1, 5, or 10 percent heat-inactivated fetal bovine serum (FBS) enhanced LPS-stimulated bovine monocyte release of IL-1 activity as compared with monocytes cultured under serum-free conditions. We used a combination of size-exclusion and reverse-phase high-performance liquid chromatography (HPLC) to purify bovine IL-1 from serum-free monocyte culture supernatants. Size-exclusion HPLC resulted in a single peak of biological activity with an approximate molecular weight of 18,000 daltons. Further purification by reverse-phase HPLC demonstrated at least three major molecular species with IL-1 activity. Besides providing information about production of IL-1 by bovine monocytes in vitro, this study also describes a protocol to purify bovine IL-1 for future studies addressing its biological functions.

Species preference of bovine thymocytes and fibroblasts for bovine interleukin 1

The purpose of this study was to determine whether bovine thymocytes and fibroblasts preferentially respond to bovine IL-1 as compared with human and murine interleukin 1 (IL-1). We compared equivalents units of recombinant murine and human IL-1 alpha, and purified monocyte-derived bovine IL-1, as measured in the murine thymocyte IL-1 assay, for their ability to stimulate the proliferation of bovine thymocytes and fibroblasts. Fetal and adult bovine thymocytes responded to bovine IL-1, but in contrast, did not respond to recombinant human or murine IL-1 alpha at the concentrations tested. Both adult and neonatal murine thymocytes responded similarly to the three IL-1 preparations. Thus, we concluded that the preferential response of bovine thymocytes for bovine IL-1 was not dependent upon the age of the thymus donor. Bovine fibroblasts also preferentially responded to bovine IL-1; fibroblast proliferation was stimulated by bovine but not human or murine IL-1. Our findings, therefore, imply that although IL-1 is highly conserved among mammalian species, its ability to stimulate the proliferation of thymocytes and fibroblasts may vary from species to species.

Release of interleukin-1 beta associated with potent cytocidal action of staphylococcal alpha-toxin on human monocytes

The pathogenetic relevance of Staphylococcus aureus alpha-toxin in humans has been debated because human cells have been thought to display a natural resistance toward the cytotoxic action of this cytolysin. Following our previous demonstration that human platelets represent sensitive targets for toxin attack, we have now identified monocytes as a second, highly vulnerable human cell species that succumb to attack by low doses (20 ng/ml) of alpha-toxin. The cytotoxic action of alpha-toxin is reflected in a rapid depletion of cellular ATP that is essentially complete within 30 min. The presence of human plasma proteins affords some protection of monocytes against the action of the toxin. In 10% autologous serum, ATP depletion commences at 80 to 300 ng of toxin per ml. Subcytolytic doses stimulate the release of tumor necrosis factor alpha, a process that is slightly accentuated in the presence of 50% serum. Cytocidal toxin doses unfailingly cause the release of large amounts of interleukin-1 beta from cultured cells, with levels of this monokine generally exceeding 10 ng/ml in the cell supernatants 60 min after application of toxin. Initial evidence suggests that this is due to processing of intracellular interleukin-1 rather than to de novo synthesis of the cytokine. All noted effects are abrogated in the presence of a neutralizing monoclonal antibody against alpha-toxin. Through its capacity to provoke cytokine release from monocytes and its attack on platelets, alpha-toxin may initiate cellular events that are relevant to the pathogenesis of staphylococcal infection.

Purification of homogeneity and amino acid sequence analysis of a receptor protein for interleukin 1

The interleukin 1 (IL-1) receptor from mouse EL-4 thymoma cells was purified to homogeneity by a method which utilized ligand affinity chromatography and classical chromatographic techniques. After solubilization of the receptor from intact cells with the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate, the IL-1 binding activity was purified greater than 23,000-fold. Analysis of the purified protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot, and ligand blot demonstrated that a single protein of molecular mass of approximately 80 kDa is the IL-1 binding polypeptide. The purified protein bound IL-1 with a dissociation constant of approximately 1.1 X 10(-10) M, which is indistinguishable from the affinity of the cell-bound receptor. The amino acid composition of this protein is strikingly similar to the composition deduced from the sequence of a cDNA coding for an IL-1 receptor from EL-4 cells. Protein sequence analysis of Staphylococcus aureus V-8 protease-derived peptides yields data consistent with the sequence proposed from cloned cDNA. These studies have demonstrated that the high affinity IL-1 receptor on EL-4 cells is the 80-kDa protein.

Isolation and characterization of biologically active murine interleukin-1 alpha derived from expression of a synthetic gene in Escherichia coli

A murine interleukin-1 alpha (mIL-1 alpha) gene coding for amino acids 115 to 270 of the precursor protein (Lomedico, P.T., Gubler, U., Hellmann, C.P., Dukovich, M., Giri, J.G., Pan, Y.E., Collier, K., Semionow, R., Chua, A.O. and Mizel, S.B. (1984) Nature 312, 458-462) was chemically synthesized and expressed in Escherichia coli. mIL-1 alpha, in the form of insoluble inclusion bodies, accounted for approx. 30% of total cellular protein produced by the recombinant strain. A simple isolation protocol was developed in which inclusion body material was first solubilized in 3 M guanidine hydrochloride, and the mIL-1 alpha was then simultaneously purified and allowed to fold to its active conformation by dialysis against distilled water. This procedure yielded pure, biologically active mIL-1 alpha with 41% recovery of the mIL-1 alpha present in the guanidine hydrochloride extract. The purified preparation had the expected amino acid composition, a molar absorptivity of 28,200 M-1.cm-1 and a pI of 5.2. No methionyl-mIL-1 alpha was detected by N-terminal sequence analysis, and the endotoxin level was less than 10 pg per micrograms of mIL-1 alpha. The specific biological activity was 3.10(7) units/mg in a co-mitogenic thymocyte proliferation assay. In addition to full-length mIL-1 alpha, the preparation contained N-terminally truncated mIL-1 alpha species (mainly des-4 and des-6 amino acid forms). The truncated species were isolated and found to have the same biological activity as the complete polypeptide. Thus, the active fragment of mIL-1 alpha appears to consist of a proteinase-sensitive N-terminal region which is not essential for activity, and a proteinase-resistant core which harbors the essential determinants of its cytokine function.

Escherichia coli-derived human interferon-gamma with Cys-Tyr-Cys at the N-terminus is partially N alpha-acylated

Purified preparations of recombinant human interferon-gamma (rIFN-gamma) with Cys-Tyr-Cys at the N-terminus ([ Cys-Tyr-Cys]IFN-gamma) derived from Escherichia coli gave two closely migrating bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two peaks on reversed-phase high-performance liquid chromatography (rpHPLC). In contrast, rIFN-gamma without Cys-Tyr-Cys and rIFN-gamma in which both Cys-1 and Cys-3 were substituted with serine behaved as a single species on both SDS-PAGE and rpHPLC. These results suggest that the N-terminal portion of rIFN-gamma is heterogeneous. To elucidate the structure of the N-terminal portion, the N-terminal peptide preparation was obtained by binding rIFN-gamma to thiopropyl-Sepharose 6B gel with disulfide linkage followed by trypsin digestion and elution with 2-mercaptoethanol. The preparation gave four peaks (NT-1, NT-2, NT-3, and NT-4, in order of elution) on rpHPLC; all four were found to be Cys-1-Lys-9 by amino acid analysis after acid hydrolysis. Various analyses indicate that NT-1 is the intact nonapeptide, that NT-3 and NT-4 are N alpha-formyl and N alpha-acetyl forms of NT-1, respectively, and that NT-2 may be S-blocked at Cys-1. It is concluded that E. coli-derived [Cys-Tyr-Cys]IFN-gamma is partially N alpha-acylated. The data also suggest that N alpha-acylation does not affect the biological activity of [Cys-Tyr-Cys]IFN-gamma.

Identification of a high-affinity receptor for interleukin 1 alpha and interleukin 1 beta on cultured human rheumatoid synovial cells

In this report the binding of recombinant human interleukins 1 alpha and 1 beta (rIL-1 alpha and rIL-1 beta) to primary cultures of human rheumatoid synovial cells is measured and compared to the concentrations of these mediators required for stimulation of PGE2 production by these same cells. The average concentration of IL-1 alpha required for half-maximal stimulation of PGE2 was 4.6 +/- 1.5 pM (+/- SEM) (n = 6), whereas for IL-1 beta half-maximal stimulation was observed at a concentration of 1.3 +/- 0.24 pM (n = 6). Both direct and competitive binding experiments were performed. In direct binding experiments, IL-1 alpha bound with a Kd of 66 pM (n = 1), while IL-1 beta bound with a Kd of 4 pM (n = 2). In competitive binding experiments, IL-1 alpha inhibited binding of 125I-IL-1 alpha with a Ki of 33-36 pM (n = 2) and binding of 125I-IL-1 beta with a Ki of 51-63 pM (n = 2). IL-1 beta inhibited binding of 125I-IL-1 alpha with a Ki of 2-3 pM (n = 2) and binding of 125I-IL-1 beta with a Ki of 7 pM (n = 2). The binding data were best fit by a model specifying a single class of receptors with homogeneous affinity for either IL-1 alpha or IL-1 beta and with an abundance of 3,000-14,000 sites per cell. Autoradiography showed that the vast majority of the synoviocytes within the cultures possessed IL-1 receptors. Comparison of biological response curves with the binding curves indicates that the observed receptors exhibit sufficiently high affinity to mediate the response of human synoviocytes to low picomolar concentrations of IL-1 alpha and IL-1 beta.

Cloning, sequence and expression of bovine interleukin 1 alpha and interleukin 1 beta complementary DNAs

Interleukin 1 (IL-1) is a cytokine which mediates a variety of immunoregulatory and inflammatory activities. Using human IL-1 alpha and IL-1 beta probes, cDNAs for the corresponding bovine genes were isolated from an alveolar macrophage library. The open reading frames of the bovine IL-1 alpha and IL-1 beta cDNAs encode proteins of 268 and 266 amino acids, respectively, each with a predicted mol. wt of approx. 31,000. Both forms of bovine IL-1 exhibit a high degree of sequence homology with IL-1 gene products from other mammalian species. Based upon comparisons with human IL-1 amino acid sequences, the post-translationally processed, mature forms of bovine IL-1 would occur as 17-18,000 mol. wt proteins. Sequences encoding mature bovine IL-1 alpha and IL-1 beta were inserted into E. coli expression plasmids and biologically active proteins were synthesized as judged by the ability of the recombinant proteins to induce proliferation of bovine thymocytes. Both IL-1 alpha and IL-1 beta exist as single genomic copies. In addition, bovine IL-1 beta mRNA is approx. 10-fold more abundant than IL-1 alpha mRNA in stimulated alveolar macrophages.

Identification of different charged species of a human monocyte derived neutrophil activating peptide (MONAP)

Lipopolysaccharide-stimulated human monocytes secrete a 10 kD peptide (MONAP) of high neutrophil, not however monocyte or eosinophil stimulating activity. By reversed phase HPLC MONAP could be distinguished from Interleukin 1. Analytic isoelecto-focusing of pure MONAP (single line upon sodiumdodecylsulfate polyacrylamide gel electrophoresis, single peak after RP-18-HPLC), obtained by size exclusion HPLC followed by two different reversed phase HPLC steps revealed charge heterogeneity giving major components with isoelectric points at 4.7, 4.9, 6.4 and 6.9, all of which exhibited chemotactic activity.

The role of tumor necrosis factor and interleukin 1 in the immunoinflammatory response

Monocytes and tissue macrophages produce at least two groups of protein mediators of inflammation, interleukin 1 (IL-1) and tumor necrosis factor (TNF). Recent studies have emphasized that TNF and IL-1 modulate the inflammatory function of endothelial cells, leukocytes, and fibroblasts. Although these cytokines share a number of biologic properties, they have quite distinct gene and protein structures. It is our purpose to focus on the role of these mediators in inflammation.

Site-specific mutagenesis of the human interleukin-1 beta gene: structure-function analysis of the cysteine residues

Human interleukin-1 beta (IL-1 beta) has two cysteines located at amino acid residues 8 and 71 of the mature protein consisting 153 amino acids. To clarify the role of these characteristic cysteine residues in IL-1 beta, at first, an expression plasmid for site-specific mutagenesis has been constructed by inserting the ori and intergenic region of phage f1 into the IL-1 beta expression vector. The plasmid can be used not only for isolation of the modified IL-1 beta gene but for expression of the mutant protein in Escherichia coli. Using this plasmid, each of the cysteine codons in IL-1 beta gene was changed to serine or alanine codon, or deleted. The modified IL-1 beta showed that the two cysteine residues in IL-1 beta are not essential for biological activity but not to be eliminated for the maintenance of the functional structure of IL-1 beta.

Interleukin 1 beta is localized in the cytoplasmic ground substance but is largely absent from the Golgi apparatus and plasma membranes of stimulated human monocytes

The subcellular location of IL-1 beta was determined using a postsectioning immunoelectron microscopic method on ultrathin frozen sections of human monocytes stimulated with LPS. This methodology permits access of antibody probes to all sectioned intracellular compartments, and their visualization at high resolution. Staining was performed with a rabbit antibody that specifically recognized amino acids 197-215 in the 33-kD IL-1 beta precursor molecule, followed by affinity-purified goat anti-rabbit IgG conjugated to 10 nm colloidal gold particles. Approximately 90% of the IL-1 beta antigens were localized in the ground substance of the cytoplasm at 4 or 20 h after activation, when both intracellular and extracellular accumulation of IL-1 beta was well underway. No significant IL-1 beta staining was observed on the outer cell membrane, nor within the lumens of the endoplasmic reticulum (ER), the Golgi apparatus, or secretory vesicles. In contrast, lysozyme was localized in the ER and dense secretory granules using these methods. Our results suggest that IL-1 beta is not anchored on the plasma membrane, and that its secretion occurs by a novel mechanism that does not use a secretory leader sequence, nor the classical secretory pathway involving the ER and Golgi apparatus.

The production of myeloid blood cells and their regulation during health and disease

The regulation of myelopoiesis in vivo most likely entails a complex set of interactions between cell-derived biomolecules and their target cells: hematopoietic stem and progenitor cells and accessory cells. Stimulating and suppressing factors have been characterized through in vitro studies, and their mechanisms of action in vitro and in vivo have begun to be elucidated. Among those factors being studied are the hematopoietic colony-stimulating factors (CSF): interleukin-3 (multi-CSF), granulocyte-macrophage-CSF, granulocyte-CSF, and macrophage-CSF; other molecules include erythropoietin, B-cell-stimulating factor-1, interleukin-1, interleukin-2, prostaglandin E, leukotrienes, acidic ferritins, lactoferrin, transferrin, the interferons-gamma, -alpha, and -beta, and the tumor necrosis factors-alpha and -beta (lymphotoxin). These factors interact to modulate blood cell production in vitro and in vivo. The proposed review characterizes these biomolecules biochemically and functionally, including receptor-ligand interactions and the secondary messengers within the cell which mediate their functional activity. The production and action of the molecules are described under conditions of hematopoietic disorders, as well as under normal conditions. Studies in vitro are correlated with studies in vivo using animal models to give an overall view of what is known about these molecules and their relevance physiologically and pathologically.

Epstein-Barr virus-containing epithelial cells from nasopharyngeal carcinoma produce interleukin 1 alpha

Nasopharyngeal carcinoma (NPC) is a human epithelial cancer that is constantly associated with the Epstein-Barr virus (EBV). Investigations on this tumor have been limited so far by the difficulty of culturing NPC cells for long periods. C15 is an NPC tumor that has been successfully carried in nude mice for greater than 2 yr. C15 cells isolated from the animal were shown to produce a soluble factor with interleukin 1 (IL-1) activity. Its biochemical (Mr, approximately equal to 17,000; pI approximately equal to 5) and immunological properties are identical to those of IL-1 alpha. RNA gel blot analysis showed IL-1 alpha, but not IL-1 beta, transcripts in C15 cells, in sharp contrast to monocytes that express IL-1 beta predominantly. Media from short-term cultures of fresh NPC biopsies also contained a strong IL-1 activity. Several lymphoblastoid cell lines obtained by EBV infection of normal B lymphocytes have been shown to produce IL-1 and use it as an autocrine growth factor. The production of IL-1 by malignant EBV-containing epithelial cells indicates that different types of EBV-infected cells produce IL-1. A relationship might exist between EBV and constitutive production of IL-1. The IL-1 produced by the malignant epithelial cells in vivo could stimulate the development of the pronounced T-cell infiltrate observed in NPC tumors.

Sandwich enzyme immunoassay for human interleukin-1 beta (hIL-1 beta) in urine

A highly sensitive sandwich enzyme immunoassay for human interleukin-1 beta (hIL-1 beta) in urine is described. Rabbit anti-hIL-1 beta IgG-coated polystyrene balls were incubated with urine samples and subsequently with affinity-purified rabbit anti-hIL-1 beta Fab'-horseradish peroxidase conjugate. After washing, the peroxidase activity bound to the polystyrene ball was assayed by fluorimetry using 3-(4-hydroxyphenyl)propionic acid as a substrate. The detection limit of hIL-1 beta was 0.5 pg/tube (30 amol/tube) or 5 ng/1 of urine when 0.1 ml of urine sample was used. The molecular weight of hIL-1 beta in normal urine was shown to be 17,000 by gel filtration, and levels of urine hIL-1 beta in healthy subjects aged 19-87 yr were 0-146 ng/1 or 0-88 ng/g of creatinine.

Determination of the minimum polypeptide lengths of the functionally active sites of human interleukins 1 alpha and 1 beta

Interleukin 1 (IL-1) is a two-member family of proteins (IL-1 alpha and IL-1 beta) that mediates a diverse series of immune and inflammatory responses. These two proteins have only 26% amino acid homology yet bind to the same receptor. It is of importance to define the active sites of these molecules in order to understand their receptor interactions and the mechanisms involved in their multiple biological functions. We report here the localization of the biologically active portions within the initial polypeptide translation products. An in vitro transcription and translation system was used to generate specific fragments of each of the IL-1 molecules, which then were assayed for receptor binding capability and biological activity. Using this system, we have demonstrated that core sequences of amino acids for IL-1 beta (numbers 120-266) and 140 amino acids for IL-1 alpha (numbers 128-267) must be left intact to retain full biological activity and further that the biological activities of the IL-1 polypeptides parallel their receptor binding capabilities.

Evaluation of alveolar macrophages in normals and individuals with active pulmonary sarcoidosis for the spontaneous expression of the interleukin-1 beta gene

We have evaluated the hypothesis that the presence of large numbers of activated helper/inducer T lymphocytes in the lungs of individuals with active pulmonary sarcoidosis is associated with the exaggerated release of interleukin-1 (IL-1) by alveolar macrophages. Evaluation of media from unstimulated cultured sarcoid alveolar macrophages failed to detect IL-1 activity. When parallel cultures of sarcoid and normal alveolar macrophages were stimulated with lipopolysaccharide (LPS), they released similar amounts of IL-1 activity. Using a highly specific polyclonal anti-IL-1 beta antibody and flow cytometry to evaluate cell-associated IL-1 beta, analysis of fresh alveolar macrophages from patients with active sarcoidosis and normal individuals revealed no detectable cell-associated IL-1 beta, but IL-1 beta was present when macrophages from sarcoid patients and normals were stimulated with LPS. Similar observations were made using immunoblot analysis of cell lysates of the same unstimulated and stimulated macrophages. Finally, Northern analysis of alveolar macrophages for IL-1 beta mRNA transcripts demonstrated minimal, but equivalent, amounts of IL-1 beta in both normal and sarcoid macrophages, as compared to the much larger quantities present in LPS-stimulated alveolar macrophages. Thus, while alveolar macrophages of individuals with sarcoidosis are clearly capable of expressing the IL-1 beta gene, these findings suggest that altered expression of the IL-1 beta gene by alveolar macrophages does not play a central role in the exaggerated lung T-cell activation characteristic of sarcoidosis.

Purification and characterization of human interleukin-1 alpha produced in Escherichia coli

The production of human interleukin-1 alpha (IL-1 alpha) in Escherichia coli is described together with a method for its purification. The isolated protein was shown to be pure and physically homogeneous. The in vitro biological activity of IL-1 alpha was tested with the mononuclear-cell factor and the lymphocyte-activating factor assays. The specific activity determined with both assays was about 3 X 10(7) units mg-1 and is similar to that observed with recombinant human IL-1 beta. The purified protein was resolved by chromatofocusing into two species of isoelectric points 5.45 and 5.20 (75% and 25%, respectively, of the total protein). Both species had similar chemical properties and biological activities to the unfractionated protein. The charge difference between the species was attributed to the deamidation of a single Asn or Gln residue.

cDNA cloning of IL-1 alpha and IL-1 beta from mRNA of U937 cell line

Clones of cDNAs encoding growth inhibitory factors for human melanoma cell line A375 were isolated from cDNA library prepared by using mRNA derived from human histiocytic lymphoma cell line U937 induced with PMA and further stimulated with LPS. Cloning was achieved using Okayama-Berg cDNA expression vector system that permits expression of the inserted cDNA segments in mammalian cells. By assaying the transfected COS-1 cells supernatants and cell extracts, we isolated two distinct cDNA clones encoding growth inhibitory factors. It was determined by the nucleotide sequences of the inserts, the cDNAs corresponded to IL-1 alpha and -1 beta. Our results indicate U937 cells can be induced to produce both interleukin-1s.