Biotinylation of reactive amino groups in native recombinant human interleukin-1 beta

Recombinant human interleukin-1 beta (rIL-1 beta) was chemically modified by a 10-fold molar excess (reagent:protein) of sulfosuccinimidyl 6-(biotinamido) hexanoate (sulfo-NHS-LC-biotin) or sulfosuccinimidobiotin (sulfo-NHS-biotin) under mild conditions. The primary product was purified in each case by cation exchange high performance liquid chromatography (HPLC) and digested with endoproteinase Lys C. Peptide mapping by C18 reverse phase HPLC permitted identification of three sites of biotinylation using both reagents; N-terminal alanine, lysine 93, and lysine 94. Few additional singly modified rIL-1 beta products were obtained under these conditions, despite the presence of 15 lysine residues in this protein. These data support the view that the N terminus as well as the trilysine sequence (residues 92-94) are readily susceptible to chemical modification and are exposed on the surface of the protein. Chromatography of intact biotinylated rIL-1 beta by C4 reverse phase HPLC resolved a protein modified exclusively at the N-terminal alanine from two proteins modified singly at either lysine 93 or lysine 94. In addition, a protein product modified at lysine 103 was also obtained when rIL-1 beta was similarly modified with sulfo-NHS-biotin. Since the only difference between the two biotinylation reagents relates to spacer length and its associated hydrophobicity, these data suggest that lysine 103 is not as accessible to surface modification reagents as are lysine 93, lysine 94, or alanine 1. Initial experiments indicate that none of the modifications described above decrease thymocyte proliferation by more than one order of magnitude. Therefore, these amino acid residues are not crucial for bioactivity, and we anticipate the use of these monobiotinylated proteins in structure/function analysis of IL-1 beta.

Effect of interleukin-1 on the size distribution of cartilage proteoglycans as determined by sedimentation field flow fractionation

The effect of interleukin-1 (IL-1) on the size distribution of cartilage proteoglycans was studied using sedimentation field flow fractionation (SdFFF), a rapid, high-resolution technique for the separation of proteoglycan monomers and aggregates. During incubation of cartilage in control media, 35S-prelabeled proteoglycan was lost primarily from proteoglycan present in the monomer form; aggregates were conserved. In the presence of IL-1, both 35S-proteoglycan monomers and aggregates were lost, suggesting that IL-1 increases the susceptibility of aggregates to loss from the cartilage matrix. Evaluation of uronic acid as a measure of net change in proteoglycan content indicated that IL-1 causes a net decrease in both monomers and aggregates. Kinetic studies suggested that aggregates are degraded to monomers which then diffuse out of the matrix. Incorporation of [35S]sulfate into cartilage proteoglycans following exposure to IL-1 showed that synthesis of monomers and aggregates is inhibited similarly. SdFFF is a valuable technique for studying proteoglycan metabolism. With its use, changes in proteoglycan monomer and aggregate populations can be detected in response to cytokines such as IL-1.

One-step immunoaffinity purification of bioactive human recombinant IL-1 beta with a monoclonal antibody directed to a well-exposed domain of the protein

A monoclonal antibody (mAb) specific for human recombinant IL-1 beta (hu rIL-1 beta) was produced by immunizing BALB/c mice with hu rIL-1 beta purified with classical methods. This mAb recognizes an epitope within the highly hydrophylic fragment spanning amino acid 133-147. The affinity constant of this mAb towards IL-1 beta was determined by RIA. An affinity column was prepared by covalent binding of the mAb to Sepharose CL-4B. The column was capable of selectively binding hu rIL-1 beta produced in Escherichia coli directly from crude homogenates. The IL-1 beta protein yield was higher than 90% with a very good recovery of IL-1 beta biological activity. Moreover, the immunosorbent retained at least two thirds of its IL-1 beta-binding capacity after 20 cycles of purification.

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.

Production of cytokines by bone marrow cells obtained from patients with multiple myeloma

Previous work with continuously cultured multiple myeloma lines suggested that cytokine production by tumor cells may mediate some of the medical complications of this disease. To further investigate this issue, we assayed freshly obtained bone marrow (BM) cells from myeloma patients for the in vitro production of cytokines and the presence of cytokine RNA. Production of cytokine protein was assessed by bioassays with the aid of specific neutralizing anticytokine antibodies. These assays detected interleukin-1 (IL-1) and tumor necrosis factor (TNF) secretion by myeloma BM cells, which was significantly greater than secretion from similarly processed BM cells of control individuals. In contrast, lymphotoxin and interleukin-2 (IL-2) production could not be detected. The levels of IL-1 and TNF produced in vitro peaked at 24 hours of culture and correlated with stage and the presence (or absence) of extensive osteolytic bone disease. Northern blot analysis demonstrated the presence of IL-1 beta and TNF RNA in uncultured myeloma BM cells but no detectable IL-1 alpha or lymphotoxin RNA. In addition, the amount of cytokine RNA correlated with protein production, being significantly greater in patients' BM cells than in control marrow. These data suggest a role for IL-1 beta and/or TNF in the pathophysiology of multiple myeloma and argue against a role for lymphotoxin or IL-2.

Chlamydia trachomatis-induced production of interleukin-1 by human monocytes

Human diseases caused by the intracellular bacterium Chlamydia trachomatis include genital tract infections and blinding trachoma. Chlamydial infections are characterized by chronic inflammation and scarring, and development of such complications is thought to be immunologically mediated. In this study, we show that coculture of C. trachomatis (serovar L2) with human blood monocytes induced the production of interleukin-1 (IL-1), an important mediator of inflammation, tissue remodeling, and scarring. IL-1 was produced in response to UV-inactivated elementary bodies containing from 0.1 to 50 micrograms of protein per ml, with a maximal response at 5 to 10 micrograms/ml. IL-1 activity was detected by 6 h of incubation and was maximal by 24 h. Peak levels were maintained throughout 96 h of incubation. Rabbit antibody to human IL-1(alpha + beta) effectively neutralized the thymocyte-stimulating activity of the supernatants. The apparent molecular weight of chlamydia-induced IL-1 was 16,000, as determined by gel filtration on a Bio-Gel P-60 column. Isoelectric focusing yielded two peaks of activity, with pIs of 5.5 and 6.9. Neutralization studies with antisera against human IL-1 alpha and IL-1 beta showed that the acidic and neutral peaks corresponded to IL-1 alpha and IL-1 beta, respectively, with IL-1 beta predominating. Heat-killed chlamydiae, which are not internalized by monocytes, were effective IL-1 inducers, indicating that phagocytosis was not required for IL-1 induction. Purified C. trachomatis lipopolysaccharide was also an effective IL-1 inducer, suggesting that the response to intact organisms may be largely a response to chlamydial lipopolysaccharide. Finally, purified chlamydial major outer membrane protein induced low but detectable IL-1 activity.

Membrane IL-1: IL-1 alpha precursor binds to the plasma membrane via a lectin-like interaction

Although biologically active IL-1 associated with plasma membrane has been demonstrated in both mouse and man, a biochemical mechanism for membrane anchoring has not been described. We have analyzed the nature of membrane IL-1 in stimulated murine macrophages. We show that it consists of an IL-1 alpha precursor bound to the plasma membrane via a lectin-like interaction that is specifically dissociated with D-mannose. The dissociated IL-1 was detected as both a biological activity and, by immunoprecipitation and SDS-PAGE, as a 33 kDa IL-1 alpha precursor. Treatment of macrophages with D-mannose before fixation depleted detectable IL-1 biological activity associated with the membrane. Pro-IL-1 alpha was glycosylated in these cells, as shown by incorporation of D-[14C]mannose; thus it is likely that a cell surface lectin binds pro-IL-1 via these carbohydrate residues. In addition to anchoring IL-1 precursor to the plasma membrane, this lectin-like interaction may also be important in the overall regulation of IL-1 release.

The biological activities of interleukin-1

Interleukin-1 (IL-1) refers to a hormone-like polypeptide that mediates a broad spectrum of activities in host defence as well as a variety of disease processes. Originally described as a substance produced by activated macrophages, IL-1 is now recognized as a polypeptide produced by many other cell types. Two distinct genes have been identified that code for two structurally related forms of the molecule, termed IL-1 alpha and beta. IL-1 is the primary mediator of the acute phase response and is responsible for many of the changes associated with the onset of infection. It is involved in the immune response to antigenic challenge. IL-1 induces fever and has profound endocrinologic, neurologic, metabolic and hematologic effects. Both forms of IL-1 bind to a common receptor that has been identified on a variety of cell types including lymphocytes, hepatocytes, endothelial cells and fibroblasts. Many of the activities of IL-1 are mediated by the induction of other cytokines like IL-2, IL-6, interferons, tumor necrosis factor, and colony-stimulating factors. In animals IL-1 protects against the effects of radiation, it enhances natural resistance of infection, and it stimulates bone marrow recovery after myelosuppression. These studies suggest that IL-1 may be used as a therapeutic agent.

Inhibitory effect of TNF alpha antibodies on synovial cell interleukin-1 production in rheumatoid arthritis

The effect of tumour necrosis factor (TNF alpha) antibodies on synovial cell interleukin-1 (IL-1) production was investigated in 7 patients with rheumatoid arthritis and in 7 with osteoarthritis. Synovial cell IL-1 production was significantly reduced by anti-TNF alpha antibody in cultures from patients with rheumatoid arthritis, but antilymphotoxin antibody did not have this effect (except in 1 culture). In cultures from patients with osteoarthritis spontaneous IL-1 production was low, despite high concentrations of TNF alpha, and IL-1 production was not inhibited by anti-TNF alpha antibody. In rheumatoid arthritis, TNF alpha may be the main inducer of IL-1, and anti-TNF alpha agents may be useful in treatment.

Different conformation of purified human recombinant interleukin 1 beta from Escherichia coli and Saccharomyces cerevisiae is related to different level of biological activity

Human recombinant interleukin 1 beta produced in Escherichia coli and in Saccharomyces cerevisiae was purified to homogeneity by a combination of ion exchange, gel filtration and hydroxylapatite column chromatography. The two proteins, both expressed in the mature form, differ in that the protein secreted from yeast is glycosylated and lacks the first four amino acids. The biological activity of IL-1 obtained from E. coli is comparable to that of the natural protein, while the protein produced from yeast showed very low specific activity. The analysis of the state of oxidation of the two cysteine residues present in the IL-1 molecule and the evaluation of the immunoreactivity of the two proteins have proved that a different conformation is at the basis of the different biological activity of the two proteins.

Identification of a monocyte specific pre-interleukin 1 beta convertase activity

Interleukin 1 (IL-1) is a lymphokine secreted by monocytes in response to a variety of inflammatory stimuli. IL-1 beta, the predominant form of IL-1 produced by human monocytes, is synthesized as an inactive precursor of 31 kDa and is cleaved at Asp116-Ala117 to yield a 17.5-kDa extracellular form. The exact cellular site of cleavage and mechanism of secretion is at present unknown. We have prepared cell-free postnuclear extracts from freshly isolated human monocytes as well as THP.1 cells, a human monocyte-like cell line, and various blood lymphocytes and fibroblast cell lines. Using pre-IL-1 beta synthesized by in vitro transcription and translation, we have shown that only extracts derived from human monocytes and THP.1 cells were capable of cleaving precursor IL-1 beta to authentic mature IL-1 beta. Subcellular fractionation of the extracts suggested that the processing activity is found in the cytosol of monocytes or monocyte-like cell lines. The cleavage product of this protease is identical to authentic IL-1 beta as shown by mobility on SDS/PAGE and amino acid sequence analysis of the [3H]leucine-labeled product. The cleavage product is also capable of binding to the IL-1 receptor found on fibroblast membranes. Finally, mutation of Asp116----Ala116 rendered the IL-1 beta precursor resistant to cleavage by the processing activity. We conclude that a protease activity found only in monocytes will specifically process IL-1 beta to an active form.

Two peaks of interleukin 1 expression in human leukocytes cultured with tobacco glycoprotein

We have previously shown that tobacco glycoprotein (TGP), a polyphenol-rich glycoprotein isolated from tobacco or from cigarette smoke, affects the immune system. In this study we show that TGP induces human PBL and adherent cells to produce IL-1 alpha and IL-1 beta. Two peaks of IL-1 activity were observed; one at 18-24 h, the second at 4-6 d after initiation of culture. A similar pattern was observed for the steady state level of IL-1 mRNA. These data suggest that the production of IL-1 by cells stimulated with TGP might be a factor in cardiovascular disease associated with cigarette smoking.

A sensitive IL-1 thymocyte co-stimulator assay using a novel beta-D-galactoside specific lectin from the beetle, Allomyrina dichotoma

A sensitive thymocyte co-stimulator assay of IL-1 using a beta-D-galactoside specific lectin (allo A) obtained from the beetle (Allomyrina dichotoma) is reported here. Allo A stimulated [3H]thymidine uptake of mouse thymocytes in the presence of IL-1. The allo A assay was more sensitive than the PHA or PNA- thymocyte assay, especially at low doses of IL-1. Optimal conditions for the allo A assay were as follows: allo A, 2.5-5.0 micrograms/ml; whole thymocytes, 0.5-1.0 x 10(6) cells/well; incubation time, 72-96 hr. The assay is sensitive and convenient and can easily be performed in any laboratory.

An Epstein-Barr virus-transformed B cell line produces autoregulatory interleukin-1 that regulates bone remodeling

In this study, we demonstrate that an Epstein-Barr virus-transformed B cell line, A-11, produced interleukin-1 (IL-1), a cytokine that regulates bone remodeling. A-11 cells produce IL-1 in a cell dose- and culture time-related manner. The IL-1 activity was neutralized by recombinant human IL-1 (rhIL-1) alpha antiserum, but not by rhIL-1 beta antiserum. The IL-1 was semi-purified by (NH4)2SO4 precipitation, Superose prep 12 gel filtration, and anion-exchange chromatography strongly stimulated in vitro bone resorption. The stimulatory effect of the purified IL-1 on bone resorption was prostaglandin independent. Purified IL-1 inhibited DNA and collagen synthesis in the osteoblastic cell line MC3T3-E1. However, it enhanced significantly the cellular activity of alkaline phosphatase (EC 3.1.3.1), a marker enzyme for differentiation of osteoblasts. On the other hand, A-11 cell proliferation was inhibited by addition of rhIL-1 alpha antiserum, but not by rhIL-1 beta antiserum. And cell proliferation was stimulated by exogenous rhIL-1 alpha and -beta.

Purification and characterization of tumor inhibitory factor-2: its identity to interleukin 1

The tumor inhibitory factor-2 from the conditioned medium of the human rhabdomyosarcoma cell line A673 was purified and sequenced. The 19 N-terminal amino acid residues were identical to those of human interleukin 1 (IL-1), corresponding to the residues 119-137 of the IL-1 alpha precursor. The purified material had an apparent molecular weight similar to that of the mature secreted form of IL-1 alpha (Mr 17,400). In addition, similarly to IL-1, it induced the production of IL-2 by T-cells. The purified protein inhibited the growth of the A673 cells from which it was derived, suggesting that it may act as an autocrine growth inhibitor. It also inhibited the growth of a human adenocarcinoma of the lung and three human mammary carcinomas, but not of two human melanoma cell lines. In contrast, it stimulated the proliferation of normal human fibroblasts. These biological activities, previously assigned to a putative tumor inhibitory factor molecule, are apparently due to the production by the tumor cells of IL-1 alpha.

Presence of the inflammatory cytokines IL-1, TNF, and IL-6 in preparations of monoclonal antibodies

We have detected significant levels of IL-1, TNF and IL-6 in ascitic fluid from mice injected with different hybridomas. Each of these murine cytokines is active on a wide range of both human and murine target cells, and all are involved in inflammatory responses in vivo. We could not detect TNF or IL-1 in culture supernatant from the hybridoma line, used to generate the ascites; however, one out of ten did produce high levels of IL-6. These cytokines can interfere in many in vitro systems where monoclonal antibodies are used as diluted ascitic fluid to inhibit their ligands. A potentially more serious problem could arise with monoclonal antibodies used for therapy, in vivo diagnosis, or as ex vivo reagents. The use of monoclonal antibodies derived from culture supernatants is, therefore, obviously preferable to use of ascitic fluid for clinical applications, however, even with supernatant it cannot be assumed that cytokines are not present. Cytokine levels should, therefore, be monitored in all starting solutions and if present, their clearance during purification should be determined.

Isolation of interleukin 1 from joint fluids of patients with Lyme disease

To investigate the role of interleukin 1 (IL-1) in Lyme arthritis we assayed synovial fluids (SF) for the presence of IL-1 activity. Crude SF from patients with Lyme disease showed IL-1-like activity. Chromatography of joint fluids revealed activity at 15-20,000 daltons. Two populations of cells were grown, which produced significant IL-1 activity when stimulated with the Lyme disease spirochete or its lipopolysaccharide. IL-1 activity from SF or stimulated cells was neutralized with an antihuman IL-1 antibody. Our results suggest IL-1 is important in the pathogenesis of Lyme arthritis, and is similar to other arthritides.

Isolation and bioactivities of three IL-1 beta N-terminal variants

Three distinct N-terminal variants of rhIL-1 beta can be generated by expression of the IL-1 beta gene in E. coli; the naturally occurring Ala1 species, Met0-Ala1 and des-Ala1 proteins. Since most studies with rhIL-1 beta have used a mixture of two or more variants, we have evaluated their individual bioactivities. The variants were resolved by cation exchange HPLC. Bioactivity measurement on murine thymocytes gave a potency order of Ala1 greater than des-Ala1 greater than Met0-IL-1 beta. Analysis using human T-cells co-stimulated with PMA showed a potency order of Ala1 greater than des-Ala1 greater than Met0-IL-1 beta. Thus changes in the N-terminal amino acid of IL-1 beta changes the activity of the protein. Since murine and human T-cells respond similarly, the interactions between the N-terminus of rhIL-1 beta and their receptors probably occur through comparable mechanisms.

IL-1 induction-capacity of defined lipopolysaccharide partial structures

Natural and synthetic lipid A as well as natural and synthetic oligosaccharide partial structures of LPS were examined in dose-response experiments to define the minimal structure necessary for IL-1 induction and release in cultures of human mononuclear cells. Wild type LPS (S. abortus equi) and rough mutant LPS was active in minimal-doses of 1 to 100 pg/ml, whereas synthetic heptaacyl and hexaacyl lipid A (Salmonella minnesota and Escherichia coli lipid A, respectively) induced IL-1 in minimal-doses of 100 to 1,000 pg/ml and 10 to 1,000 pg/ml, respectively. Nanogram amounts (0.1 to 10 ng/ml) of synthetic monodephospho partial structures of E. coli lipid A were necessary for IL-1 induction. Synthetic pentaacyl partial structures induced IL-1 very weakly. Synthetic tetraacyl and bisacyl partial structures lacking non-hydroxylated fatty acids were not active. Compared to LPS million-fold higher doses of natural and synthetic 3-deoxy-D-manno-octulosonic acid containing core oligosaccharides were necessary for IL-1 induction. Dose-response investigations with LPS and natural or synthetic partial structures established the following hierarchy in IL-1 induction-capacity: LPS greater than lipid A much greater than lipid A partial structures greater than core oligosaccharides greater than oligoacyl lipid A. Lipid A was shown here to be the portion of LPS mainly responsible for induction of IL-1 activity. The high potency of lipid A in inducing IL-1 release and the failure of the precursor Ia of lipid A to induce IL-1 production and release was also observed measuring intracellular IL-1 activity after freeze-thawing the cells. Levels of IL-1 beta mRNA in extracts of mononuclear cells correlated with biologic activity. In co-incubation experiments, precursor Ia of lipid A produced dose-dependent inhibition of production and release of IL-1 activity induced by lipid A or LPS, but not by Staphylococcus epidermidis or PHA. Incubation of cells with precursor Ia for 1h, followed by a medium change and further incubation of stimulus without precursor Ia of lipid A also resulted in inhibition. We conclude that lipid A is the main portion of LPS responsible for induction of IL-1, and that specific activation- and/or binding-mechanisms are involved in stimulation of cells with LPS and/or lipid A.

Chondrocyte activation by a putative interleukin-1 derived from lapine polymorphonuclear leukocytes

Polymorphonuclear leukocytes (PMNs) recovered from 4-h lapine peritoneal exudates contained factors which provoked the synthesis of collagenase, gelatinase, caseinase, and prostaglandin E2 by lapine articular chondrocytes. Rapid secretion of these factors occurred after exposing the polymorphs to phorbol myristate acetate or formyl-Met-Leu-Phe. Fractionation of polymorph lysates by HPLC size exclusion chromatography provided a molecular weight of approximately 14,000 for the active principle. Examination of the most active fraction by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by silver staining, confirmed the presence of a single band with this apparent molecular weight. Isoelectric focusing of this fraction revealed the presence of four distinct bands with the pI values 6.90, 7.05, 7.45, and 7.55. This fraction tested positive in a bioassay for interleukin-1. We were unable to activate chondrocytes by exposure to extracts of human PMNs from either peripheral blood or inflammatory synovial fluid.

Differential production of tumor necrosis factor, macrophage colony stimulating factor, and interleukin 1 by human alveolar macrophages

Human alveolar macrophages (AMO) have been investigated for their ability to produce three monokines, tumor necrosis factor-alpha (TNF), macrophage colony stimulating factor (CSF-1), and interleukin 1-beta (IL-1). No TNF activity was found in supernatants of unstimulated AMO cultured for 20 h, although TNF mRNA was detected in the cells by Northern blot analysis. Stimulation of the cells with lipopolysaccharide (LPS) induced production and release of high levels of TNF into the culture supernatant. Increased levels of TNF mRNA were detectable at 90 min after LPS stimulation by dot blot analysis, reaching maximum expression between 4 and 8 h and declining thereafter. TNF activity peaked at approximately 8 h in the AMO supernatants. After 24 h TNF production had ended. Compared to autologous monocytes the AMO produced 5.7 times more TNF on a per cell basis (activity accumulated in 20 h supernatants). Uncultured AMO expressed CSF-1 mRNA which was translated into active protein recovered in supernatants upon culture in the absence of stimulus. The addition of LPS to AMO slightly reduced both mRNA levels and amount of factor in the supernatants. In contrast to the AMO, monocyte production of CSF-1 was enhanced by LPS. CSF-1 production by AMO continued for at least 48 h of culture. Spontaneous production of low amounts of IL-1 was found in one-third of the AMO samples, while low levels of IL-1 mRNA were present in all tested preparations. LPS stimulation induced increase in IL-1 mRNA within 90 min; mRNA levels peaked between 12 and 20 h and stayed high for at least 42 h. However, while all LPS-stimulated AMO expressed high levels of IL-1 mRNA biologically active IL-1 was again detected only in a fraction of the AMO supernatants. These results show that the production of monokines CSF-1, TNF, and IL-1 is differentially regulated by LPS in alveolar macrophages and has different responses as compared to monocytes. The longevity of the messages for each of the factors is possible indicators of the relative contribution of these factors to the response to endotoxin-induced injury and repair processes in the lung.

Natural human IL-1 beta exhibits regulatory actions on human bone-derived cells in vitro

We have shown that natural homogenous IL-1 beta exhibits regulatory activities on human bone-derived osteoblast-like cells in vitro. IL-1 beta stimulated cellular proliferation and the synthesis of prostaglandin E2 and plasminogen activator activity by the cultured human osteoblast-like cells. In contrast to these stimulatory actions, IL-1 beta antagonised the stimulatory effects of 1.25(OH)2 D3 on the production of alkaline phosphatase and osteocalcin, two markers of the osteoblast phenotype. These studies indicate that this cytokine may therefore have potential physiological and pathological effects on bone metabolism.

Preliminary X-ray crystallography studies of recombinant human interleukin-1 alpha. Purification and structural characterization

Human interleukin-1 alpha, cloned and expressed in E. coli, has been purified and structurally characterized by various physiochemical methods, including mass spectrometry. The recombinant protein has been crystallized by the hanging drop vapor diffusion method using dimethyl sulfoxide as the precipitating agent. The space group is P2(1)2(1)2(1). Unit cell dimensions are a = 44.1, b = 57.1, and c = 61.7 A and alpha = beta = gamma = 90 degrees. The crystals diffract to beyond 1.7 A and are suitable for high resolution data collection. Native diffraction data were collected. Screens for heavy atom derivatives have been initiated.

Schistosomal egg granuloma-derived fibroblast-stimulating factor is apparently distinct from interleukin-1

We have previously reported that egg granulomas isolated from livers of Schistosoma mansoni-infected euthymic mice in vitro elaborate a factor(s) that stimulates a variety of fibroblast responses including fibroblast proliferation and enhanced synthesis of extracellular matrix proteins. We have postulated that these factors play a role in the pathogenesis of hepatic fibrosis in schistosomiasis mansoni. Serum-free supernatants from egg granuloma cultures also stimulate thymocyte proliferation in an assay that defects interleukin-1 (IL-1). Thymocytes and fibroblasts are stimulated to proliferate by the same fractions of egg granuloma culture supernatant separated by gel filtration, isoelectric focusing, and ion-exchange chromatography. This suggested that granuloma-derived IL-1 is responsible for the observed fibroblast stimulation. Here we report that the ability of granuloma culture supernatants to stimulate the IL-1-sensitive D10.G4.1 cells but not fibroblasts is removed by treatment with immobilized anti-IL-1 antibody. We also observed that dialyzed culture supernatants from egg granulomas obtained from infected congenitally athymic (nude) mice also stimulate fibroblast proliferation. Treatment with anti-IL-1 antibody did not abrogate this response. In contrast to our experience with egg granulomas isolated from euthymic mice, IL-1- and fibroblast-stimulating activity could be separated by gel filtration and isoelectric focusing. We conclude that the fibroblast growth-stimulating activities elaborated by egg granulomas from S. mansoni-infected euthymic and athymic mice may be different but both appear to be distinct from IL-1.

Partial purification and characterization of a factor produced by mitogen-stimulated sheep mononuclear cells with thymocyte-activating and cartilage-degrading properties

Ovine peripheral blood mononuclear cells stimulated with concanavalin A released a soluble factor capable of inducing cartilage resorption and thymocyte activation in vitro, but not lysis of the murine L929 cell line. The active moiety has a molecular mass of around 15-20 kDa on gel filtration columns, and can be separated into two molecular species with isoelectric points of 6.3 and 4.6 respectively. These two species were partially purified by gel filtration, chromatofocusing, high performance liquid chromatography on hydroxylapatite and anion exchange columns, and SDS-polyacrylamide gel electrophoresis. Both partially purified species showed a major band on gels at 16 kDa. When the band from the acidic factor was excised and eluted from gels it was found to retain some cartilage-degrading and thymocyte-activating properties. The biochemical and biological characteristics of the two factors is consistent with their being members of the interleukin-1 family of cytokines.