Induction of human interleukin 1 mRNA measured by collagenase- and prostaglandin E2-stimulating activity in rheumatoid synovial cells

Essential immune functions of fibroblasts in innate host defense

The term fibroblast has been used generally to describe spindle-shaped stromal cells of mesenchymal origin that produce extracellular matrix, establish tissue structure, and form scar. Current evidence has found that cells with this morphology are highly heterogeneous with some fibroblastic cells actively participating in both innate and adaptive immune defense. Detailed analysis of barrier tissues such as skin, gut, and lung now show that some fibroblasts directly sense pathogens and other danger signals to elicit host defense functions including antimicrobial activity, leukocyte recruitment, and production of cytokines and lipid mediators relevant to inflammation and immunosuppression. This review will synthesize current literature focused on the innate immune functions performed by fibroblasts at barrier tissues to highlight the previously unappreciated importance of these cells in immunity.

From supernatants to cytokines: a personal view on the early history of IL-1, IL-1Ra, TNF and its inhibitor in rheumatology

Long-term cell cultures developed early in the twentieth century allowed identification in their supernatants of biological mediators subsequently defined as migration factors, interferons, lymphokines, monokines, cytokines and interleukins. In rheumatology, early in the 1930s, synovial cell cultures revealed two major distinct populations, i.e. synovial fibroblasts and monocyte-macrophages. Discovery of the interstitial collagenase (MMP-1) and its role in tissue destruction, such as in rheumatoid arthritis (RA), raised the question of the cellular source for this enzyme. My personal interest in the field was driven by the lack of understanding for the link between tissue destruction and immunology. This triggered our seminal contribution to the field, establishing in 1976-79 at the Arthritis Unit (Massachusetts General Hospital, with SM Krane) that a mononuclear factor (MCF, around 15 kDa) produced by stimulated macrophage, under direct contact with activated T cells, induced large amounts of collagenase and prostaglandin E2 (PGE2, a bone resorbing agent) in human synovial fibroblasts from RA patients. Our original "MCF" biological observations preceded cloning, and recombinant IL-1β confirmed the biological activity of the purified natural IL-1. Following my return to Geneva in 1980 and searching for a high level of IL-1 in urine and serum of patients with high fever or Still's disease, to our surprise-"a finding of absence"-we found that IL-1 was masked by a factor of approximately 17 kDa and first presented this in 1984 at the Fourth International Lymphokine Workshop. In 1987, before IL-Ra cloning, my co-worker P Seckinger and I demonstrated first-time observation in cytokine biology that the mechanism was due to the inhibition of IL-1 binding the cell surface receptor, leading to the concept of IL-1 receptor antagonist (IL-1Ra). Having reported in 1985 that TNF/cachectin also induced collagenase and PGE2 in human synovial cells, we found that IL-1Ra did not block TNF-α but was due to another inhibitor. As other investigators, we confirmed that this inhibitory factor was a soluble TNF receptor. The years between the 1970s and 1990s were probably the most exciting period in the field of cytokines and cytokine antagonists; it gave rise to two concepts in the cytokine field-one of the receptor antagonist, and the other of soluble receptor antagonists.

The role of cytokines in cartilage matrix degeneration in osteoarthritis

Chondrocytes are the single cellular component of hyaline cartilage. Under physiologic conditions, they show steady-state equilibrium between anabolic and catabolic activities that maintains the structural and functional integrity of the cartilage extracellular matrix. Implicit in the loss of cartilage matrix that is associated with osteoarthritis is that there is a disturbance in the regulation of synthetic (anabolic) and resorptive (catabolic) activities of the resident chondrocytes that results in a net loss of cartilage matrix components and deterioration in the structural and functional properties of the cartilage. Multiple mechanisms likely are involved in the disturbance of chondrocyte remodeling activities in OA. They include the development of acquired or age-related alterations in chondrocyte function, the effects of excessive mechanical loading, and the presence of dysregulated cytokine activities. Cytokines are soluble or cell-surface molecules that play an essential role in mediating cell-cell interactions. It is possible to classify the cytokines that regulate cartilage remodeling as catabolic, acting on target cells to increase products that enhance matrix degradation; as anticatabolic, tending to inhibit or antagonize the activity of the catabolic cytokines; and as anabolic, acting on chondrocytes to increase synthetic activity. This review will focus on the role of proinflammatory cytokines and their roles in mediating the increased matrix degradation that characterizes the osteoarthritic cartilage lesion.

Science review: key inflammatory and stress pathways in critical illness - the central role of the Toll-like receptors

A pure reductionist approach can sometimes be used to solve an exceptionally complicated biologic problem, and sepsis is nothing if not complicated. A serious infection promptly leads to changes in many aspects of host physiology, including alterations in circulation, metabolism, renal, hepatic, and neuroendocrine function; all of these changes happen at once, and each influences one another. It is difficult to tease apart a problem of this sort, if only because the systems affected are so profoundly interactive. The key to understanding sepsis, insofar as we do understand it at present, was found in the use of genetic tools to study the very earliest events that take place at the interface of the pathogen and the host. The continued application of both forward and reverse genetic methods, in both mammals and insects, is steadily revealing the central biochemical events that occur during infection.

In vitro ultraviolet irradiation induces pro-inflammatory responses in cells from premorbid SLE mice

Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disease, in which sunlight (especially its ultraviolet radiation (UVR)) is known to induce exacerbation of cutaneous lesions as well as systemic manifestations of the disease. The aim of this in vitro study was to investigate whether UVR (UVA, UVB) amplifies pro-inflammatory factors in cultured dermal fibroblasts (DF) or lymph node cells derived from premorbid or morbid mice from the murine SLE strains (MRL-1pr/1pr, (NZB/NZW)F1), in comparison to cells derived from normal mice from the non-SLE strains (C57BL/6, BALB/c). Our results demonstrate the following. Dermal fibroblast of premorbid SLE mice showed increased susceptibility to UVA and UVB irradiation, determined by viability assay, in comparison to those of normal mice. UVB irradiation induced an enhanced expression of ICAM-1 in such SLE derived cells, in comparison to cells of normal mice. UVA and UVB increased functional activity of LFA-1 in lymph node cells of premorbid SLE mice and not in normal controls. UVB irradiation induced increased production and secretion of pro-inflammatory cytokines (IL-1, IL-6, TNF-alpha) in DF of premorbid SLE mice, in comparison to normal controls. The enhanced pro-inflammatory responses to UVR were also observed in experiments conducted with cells derived from morbid SLE mice. In conclusion, the pro-inflammatory proneness detected in the premorbid stage of murine SLE could be of major importance in SLE pathogenesis. Furthermore, it suggests that the autoimmune inflammatory process in vivo, triggered initially by immune complex deposition, could be further amplified by UVR.

The effect of pentoxifylline on the healing of intestinal anastomosis in rats with experimental obstructive jaundice

The aims of this study were (1) to investigate the effect of experimental obstructive jaundice on the healing of intestinal anastomosis, and (2) to investigate the effect of pentoxifylline on the healing of intestinal anastomosis in rats with obstructive jaundice. Obstructive jaundice was induced in rats by the ligation and division of the common bile duct. Four days after this operation, either pentoxifylline or isotonic saline solution was administered intraperitoneally to these jaundiced rats and controls, and then intestinal anastomosis was performed. The concentrations of serum tumor necrosis factor alpha (TNF-alpha) and serum triglyceride of jaundiced and nonjaundiced rats were measured, and the quality of healing was evaluated by measuring the bursting pressure and hydroxyproline content of the anastomoses on the fifth and tenth days of anastomotic healing. Obstructive jaundice resulted in an impaired wound healing of the intestinal anastomosis in the rats. The administration of pentoxifylline to the jaundiced rats resulted in better anastomotic wound healing. The beneficial effects of pentoxifylline on anastomotic healing in rats with obstructive jaundice was attributed to its inhibitor effect on the endotoxin-induced TNF-alpha release from macrophages and monocytes, and the stabilizing effect on the neutrophils.

Significant correlation between matrix metalloproteinase activity and tumor necrosis factor-alpha in salivary extravasation mucoceles

We examined the matrix metalloproteinase (MMP) activity and tumor necrosis factor (TNF)-alpha in luminal fluid of 18 extravasation mucoceles and in saliva from Wharton's duct of five patients by means of gelatin zymography and enzyme immunoassay, respectively. The luminal fluid showed a high level of MMP activity compared with the saliva. Quantitative determination by enzyme immunoassay revealed that the luminal fluid contained higher levels of TNF-alpha than the saliva. In addition, the amount of TNF-alpha in luminal fluid exhibited a direct correlation with MMP activity estimated by densitometric analysis of gelatin zymograms. Since TNF-alpha stimulates the production of MMPs from cells such as fibroblasts, these results suggest that TNF-alpha is one of the causal molecules that enhance the accumulation of proteolytic enzymes in luminal fluid of mucoceles.

Pathomechanism of pain-related behavior produced by allografts of intervertebral disc in the rat

STUDY DESIGN

This study was designed to evaluate whether allografts of intervertebral disc materials produce hyperalgesia in the rat and whether an immune response, pH, or chemicals correlate with the induced hyperalgesia.

OBJECTIVE

To elucidate the pathomechanisms of radicular pain secondary to lumbar disc herniation.

SUMMARY OF BACKGROUND DATA

It has been reported that a low pH, an autoimmune reaction, or chemical radiculitis is likely responsible for radicular pain associated with lumbar disc herniation. In animal studies, it has been shown that hyperalgesia (an increased sensitivity to painful stimuli) involves activation of phospholipase A2 and nitric oxide synthase.

METHODS

Fat, nucleus pulposus, and anulus fibrosus were allografted into the epidural space at L6 in the rat. Withdrawal response thresholds to mechanical stimuli and withdrawal response latencies to thermal stimuli on the tail and pH in the applied tissues were measured after surgery. Interleukin-1, phospholipase A2, and nitric oxide synthase were examined in the applied tissues using immunohistochemistry, nicotineamide adenine dinucleotide phosphate-diaphorase histochemistry, and in situ hybridization.

RESULTS

Allografted fat did not produce hyperalgesia. Allografts of nucleus pulposus and nucleus pulposus plus anulus fibrosis showed evidence of mechanical and thermal hyperalgesia, respectively. There were no observed changes in pH over time. Although interleukin-1 was demonstrated in all applied tissues, phospholipase A2 was only observed around the applied nucleus A2 was only observed around the applied nucleus pulposus and nucleus pulposus plus anulus fibrosus. Nitric oxide synthase was only markedly increased around the applied tissues.

CONCLUSION

The nucleus pulposus and anulus fibrosus produce different forms of hyperalgesia (mechanical vs. thermal) associated with different and distinct immunohistochemical changes. It is possible that radicular pain of a lumbar disc herniation results from chemicals, such as phospholipase A2 and nitric oxide.

Interleukin-1 alpha produced in human gingival fibroblasts induces several activities related to the progression of periodontitis by direct contact

Previous observations suggest that interleukin-1 (IL-1) may play an important role in the progression of periodontitis. In the present study, we investigated whether a cell-associated IL-1 alpha (CAIL-1 alpha) produced in human gingival fibroblasts (HGF) induces biological activities related to the progression of periodontitis. HGF were treated with recombinant human IL-1 beta (rhIL-1 beta) for 12 h. After that, the cell layers of HGF were washed 3 times with fresh medium and were then fixed with 1% paraformaldehyde. The fixed cell layers of HGF were used for assays for bone resorbing activity, prostaglandin E2 (PGE2) production and collagenase activity. Fixed cell layers of HGF treated with rhIL-1 beta enhanced not only calcium release from BALB/c mouse calvaria but also PGE2 production and collagenase activity in HGF and human periodontal ligament fibroblasts (HPLF) cultured on the fixed cell layers. These activities were neutralized by treatment with monoclonal mouse anti-human IL-1 alpha antibody, but monoclonal mouse anti-human IL-1 beta antibody showed no effects on these activities. The induction of these activities by fixed cell layers of HGF required direct contact between the fixed cell layers and the calvaria, HGF, or HPLF. These results suggest that CAIL-1 alpha produced in HGF treated with rhIL-1 beta induces bone resorbing activity, PGE2 production and collagenase activity in the target cells by direct contact; CAIL-1 alpha may play an important role in the progression of periodontitis.

Inflammatory cytokines in the herniated disc of the lumbar spine

STUDY DESIGN

Tissues in the area of herniated lumbar discs were examined for inflammatory cytokines to elucidate the causes of sciatic pain in lumbar disc herniation.

OBJECTIVES

To determine the role of inflammatory cytokines in the stimulation of sciatic pain in lumbar disc herniation.

SUMMARY OF BACKGROUND DATA

It is postulated that in addition to mechanical compression of lumbar nerve roots and sensory root ganglia by herniated discs, there is a chemical stimulus to the production of sciatic leg pain. The exact mechanisms of chemical stimulation are not clearly defined.

METHODS

During surgery, cases of lumbar disc herniation in 77 patients were classified macroscopically into protrusion, extrusion, and sequestration types. Tissues adjacent to nerve roots at the herniation were excised and analyzed biochemically and immunohistochemically for the presence of inflammatory cytokines and for the production of these cytokines and prostaglandin E2 in vitro.

RESULTS

The homogenates of samples were analyzed for interleukin-1 alpha, interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha, and granulocyte-macrophage colony stimulating factor, which were detectable. Most of the cytokine-producing cells were histiocytes, fibroblasts, or endothelial cells in extrusion and sequestration types, and chondrocytes in protrusion type. The secretion of these cytokines and prostaglandin E2 was decreased by the addition of betamethasone. The prostaglandin E2 production was dramatically enhanced by additional interleukin-1 alpha, but decreased by the addition of tumor necrosis factor-alpha.

CONCLUSION

The results demonstrate that at the site of lumbar disc herniation, inflammatory cytokines such as interleukin-1 alpha are produced, which increases prostaglandin E2 production. Further studies are required to elucidate the role of inflammatory cytokines in causing sciatic pain.

Cytokines

The defense of the organism against pathogens involves complex processes in which many different types of cells take part. Their functions are coordinated by polypeptide mediators collectively named cytokines. The intense research devoted to these molecules in the past has yielded an insight into their molecular characteristics, mode of action, physiological function, and their deleterious role in numerous diseases. Yet therapeutic application of that knowledge--either controlled administration of cytokines or neutralization of their negative effects in certain pathological processes--despite initial achievements has remained a major challenge.

Inhibition of interleukin-1-induced effects in synoviocytes transduced with the human IL-1 receptor antagonist cDNA using an adenoviral vector

In this report, we present data showing that a recombinant adenoviral vector (Ad.RSVIL-1ra) containing the cDNA for human interleukin-1 receptor antagonist protein (IL-1ra) can genetically modify synoviocytes both in vitro and in vivo. Human synoviocytes infected with Ad.RSVIL-1ra in vitro expressed and secreted high levels of human IL-1ra that were detected by ELISA of tissue culture supernatants. New Zealand White rabbits that received intra-articular injections of Ad.RSVIL-1ra expressed transgenic IL-1ra in synoviocytes, and secretion was detected for at least 4 weeks post-infection. Further, biological activity of the transgenic IL-1ra was demonstrated by its ability to inhibit IL-1-induced prostaglandin E2 (PGE2) synthesis in vitro and IL-1-induced glycosaminoglycan (GAG) degradation in vivo. These data demonstrate that recombinant adenoviral vectors can mediate the intra-articular expression of anti-inflammatory proteins and may be a reasonable method to deliver therapeutically relevant proteins for the regional treatment of synovial inflammation.

Inhibition of angiogenesis in rats by IL-1 receptor antagonist and selected cytokine antibodies

Daily administration of 50 ng recombinant human interleukin 1-alpha (IL-1 alpha), 25 ng IL-8, 50 ng tumor necrosis factor-alpha (TNF-alpha), or 100 ng basic fibroblast growth factor (bFGF) caused intense neovascularization in a rat sponge model. These cytokine-induced neovascular responses were inhibited by coadministration of IL-1 receptor antagonist (IL-1ra; 50 micrograms), IL-8 antiserum (IL-8-AS; 1: 1000), TNF-alpha antibody (TNF-AB; 500 ng), or a monoclonal antibody to bFGF (DG2; 1000 ng), respectively. These data suggest that it is possible to manipulate the angiogenic response elicited by a defined cytokine by its receptor antagonist or neutralizing antibody. In the absence of exogenous cytokines, the sponge-induced angiogenesis was profoundly suppressed by dexamethasone (5 micrograms/day), but not modified by IL-1ra, IL-8-AS, TNF-AB, and DG2 alone. However, the combination of these four reagents was able to inhibit the sponge-induced neovascular response almost completely. These findings provide direct evidence that IL-1 alpha, IL-8, TNF-alpha and/or bFGF have an intrinsic role in angiogenesis. Further work is necessary to characterize the profile of these cytokines during angiogenesis and to elucidate the nature of their interactions.

Interaction between oncostatin M, interleukin 1 and prostaglandin E2 in induction of IL-6 expression in human fibroblasts

The role of Oncostatin M (OM), a monocyte/macrophage and T-cell product, in regulating IL-6 expression in fibroblasts of lung or synovial origin was examined in vitro. Although by itself OM had a minimal effect on enhancing IL-6 production by fibroblasts, in combination with IL-1 alpha or PGE2, OM addition resulted in a dose-dependent synergistic enhancement of IL-6 production. This synergistic effect with either IL-1 alpha (5 ng/ml) or PGE2 (10(-7) M) was clearly evident at concentrations of OM of 10, 20 or 50 ng/ml. Levels of IL-6 resulting from OM and IL-1 alpha stimulation could be reduced by indomethacin (10(-6) M) and restored again by also adding PGE2. Northern blots probed for IL-6 mRNA showed cooperative enhancement of steady state levels at 18 hours of stimulation by OM and IL-1 alpha, or OM and PGE2. Probing for mRNA of the metalloproteinase inhibitor TIMP-1 showed that stimulation by OM, IL-1 alpha or PGE2 enhanced TIMP-1 levels. However, OM (alone) or PGE2 or both combined did not elevate the metalloproteinase stromelysin-1 mRNA signals. Analysis utilizing a rat IL-6 promoter-luciferase reporter gene construct showed that OM stimulation resulted in activation of transcription that synergistically enhanced IL-1-induced levels of reporter gene expression. These results show that although OM has minor effects on IL-6 production alone, the combination of OM and other mediators result in markedly enhanced IL-6 production by fibroblasts in vitro.

Some cellular and pathophysiological correlates of the inflammatory effects of a synthetic immunomodulatory agent, muramyl dipeptide (MDP)

Acute, fully reversible paw edema was produced in mice after systemic administration of muramyl dipeptide (MDP, i.e. N-acetylmuramyl-L-alanyl-D-isoglutamine). Its stereoisomer N-acetylmuramyl-D-alanyl-D-isoglutamine (MDP-D,D) was much less effective. The swelling of paws occurred very soon (1 h) after MDP injection, reached the maximum severity at an interval of 6 h and declined afterwards. While no substantial quantitative differences were found in the sensitivity of the various inbred strains of mice to edemagenic activity of MDP, athymic nude mice were completely resistant to the induction of edema. Formation of edema was blocked by silica, indomethacin (partially also by nordihydroguaiaretic acid), monoclonal antibodies against T-cells and their TH-subpopulation. It is suggested that the MDP-induced edema is a macrophage- and T-cell-dependent, prostaglandin- (and partially leukotriene)-mediated acute reaction associated with increased vascular permeability. Possible engagement of immune/inflammatory cytokines like IL-1 has been discussed. The data support the view that this type of edema is a consequence of changes in the activity of important cellular components of the immune system.

Differences in proinflammatory activity of several immunomodulatory derivatives of muramyl dipeptide (MDP) with special reference to the mechanism of the MDP effects

Immunomodulatory agents, muramyl dipeptide (MDP) and several of its analogues, i.e. adamantylamide dipeptide, murametide, murabutide and their glucosaminylated derivatives, were tested for edemagenic activity in rats. Given systemically in aqueous solutions, only MDP and glucosaminylated MDP, at the dose of 3 mg/kg (s.c. or p.o.), were found to produce edematous swelling of the paws. Local (intra-pad) application of MDP was more effective than the systemic one. Supernatants of macrophages, in vitro cultured in presence of MDP, caused the swelling as well. The edema was of a transient nature. After reaching the maximum severity (about 6 h after injection of MDP solution or 1 h after macrophage supernatants), it was subsiding and disappeared completely within approximately 6 days after cessation of the treatment. It was found that this type of rat paw edema is probably a prostaglandin-dependent consequence of macrophage activation. Hypotheses on the involvement of immunoregulatory cytokines, and possible chemical structure-inflammatory activity relationships have been suggested.

Interleukin-1 produced by tumorigenic fibroblasts influences tumor rejection

Oncogene-transformed BALB/c-3T3 fibroblasts which spontaneously or upon immune-activation with cytokines and lipopolysaccharide (LPS) generate IL-1 alpha, were tested for their tumorigenicity as well as their interaction with natural immune defense by NK cells and macrophages. Oncogene-transformed fibroblasts were weakly tumorigenic, since not all mice developed tumors despite application of high doses of tumor cells. This was independent of the immune status of the host. However, in the immunocompetent host those transformed fibroblast lines which spontaneously produced IL-1 alpha grew only transiently and then regressed. After induction of IL-1 alpha production, a decrease in the rate of tumor take was noted and the rate of regression of developing tumors was increased. Regression of IL-1-producing transformed fibroblasts was strongly reduced but not completely abolished in sublethally irradiated mice. This indicated that IL-1 production may predominantly influence T-cell-mediated defense, but some influence on non-adaptive immunity could not be excluded a priori. IL-1 production did not influence susceptibility of transformed fibroblasts towards NK cells and macrophages. However, IL-1-producing transformed fibroblasts were most potent stimulators of NK cells and macrophages, the stimulatory effect being locally restricted. In conclusion, IL-1 producing, oncogene-transformed fibroblasts which generated the cytokine constitutively or upon immune-activation, were rejected from the tumor-bearing host following initial growth. Fibroblast-induced local activation of NK cells and macrophages was shown to play some role in tumor graft rejection. The influence of IL-1 production of transformed fibroblasts on T-cell-mediated defense is addressed in the accompanying report.

Interleukin-1 production by transformed fibroblasts. II. Influence on antigen presentation and T-cell-mediated anti-tumor response

Oncogene-transformed fibroblasts which expressed IL-1, spontaneously or after activation with conditioned medium (CM) and lipopolysaccharide (LPS), regressed in the syngeneic host. Since regression was significantly influenced by the immune competence of the host (see companion report), we speculated that regression was T-cell-mediated. Frequencies of cytotoxic T-cell precursors (CTLp) were in the same range for activated and non-activated, transformed fibroblasts. Furthermore, it was found that lysability of transformed fibroblasts was not influenced by expression of IL-1. These findings exclude the possibility that regression of CM- and LPS-treated transformed fibroblasts may have been due to the appearance of new, strongly immunogenic epitopes. On the other hand, frequencies of CTL were significantly increased after in vivo immunization with IL-1-expressing as compared to IL-1-non-expressing transformed fibroblasts. The in vivo maturation/expansion of CTL could have been the consequence of activation of helper T cells (TH), transformed fibroblast-associated IL-1 delivering the costimulatory signal. Analysis of frequencies and proliferation rates of TH confirmed this assumption. Both parameters were significantly increased after stimulation with transformed fibroblasts expressing IL-1 in comparison to transformed fibroblasts not expressing IL-1. Furthermore, purified T cells apparently depleted of cells expressing MHC class-II antigens, i.e. antigen-presenting cells, proliferated in the presence of transformed fibroblasts expressing IL-1. Since IL-1 rather than MHC class-II antigen expression was the limiting factor, antigen presentation by IL-1-expressing transformed fibroblasts appears unlikely. Instead, maturation of antigen-presenting cells could well have been initiated by tumor-associated IL-1. We conclude that IL-1 expression of transformed fibroblasts plays an important role in the induction of a T-cell-mediated anti-tumor response. The effect is due to increased efficiency in the activation of helper T cells and may be supported by activation of antigen-presenting cells.

Release of tumor necrosis factor-alpha from bovine alveolar macrophages stimulated with bovine respiratory viruses and bacterial endotoxins

The release of tumor necrosis factor-alpha (TNF-alpha) from cultured bovine alveolar macrophages (BAM) was evaluated following stimulation of BAM with bovine herpesvirus-1 (BHV-1), parainfluenza-3 (PI-3) virus, bovine respiratory syncytial virus (BRSV), Escherichia coli 0111:B4 endotoxin, Pasteurella haemolytica type 1 endotoxin, Pasteurella multocida endotoxin, and virus/endotoxin combinations. A cytotoxic assay system using Georgia bovine kidney cells as targets was used to measure TNF-alpha activity. The cytotoxic activity was neutralized by an anti-human TNF-alpha monoclonal antibody. Stimulation of BAM with 1 median tissue culture infectious dose (TCID50) of live or ultraviolet (UV)-inactivated PI-3 virus/cell resulted in release of TNF-alpha in significantly (P less than 0.05) higher amounts than sham-induced BAM. The quantities of TNF-alpha released after live or UV-inactivated BHV-1 or BRSV induction were not significantly higher than sham-induced BAM. E. coli 0111:B4, P. haemolytica type 1 and P. multocida endotoxins stimulated TNF-alpha release in a dose-dependent manner. Sequential exposure of BAM to 1 TCID50 per cell of either live BHV-1, PI-3 virus or BRSV and then 5 micrograms ml-1 of either E. coli 0111:B4, P. haemolytica type 1 or P. multocida endotoxin caused a significant (P less than 0.05) reduction in detectable TNF-alpha in seven of nine virus/endotoxin combinations tested, when compared with 5 micrograms ml-1 of endotoxin alone. Parainfluenza-3 virus/endotoxin combinations stimulated higher TNF-alpha release when compared with other virus/endotoxin combinations. Five out of six test animals had serum-neutralizing antibodies to PI-3 virus, one out of six had serum-neutralizing antibodies to BHV-1, and two out of six had serum-neutralizing antibodies to BRSV, suggesting a possible relationship between serum neutralizing antibodies and TNF-alpha release from in vitro cultivated BAM.

Regulation of gene expression of macrophage-colony stimulating factor in human fibroblasts by the acute phase response mediators interleukin (IL)-1 beta, tumor necrosis factor-alpha and IL-6

Fibroblasts constitute a major element of the bone marrow stroma. They play a pivotal role in blood cell development by providing the scaffolding required for cellular organization and tissue cohesion and by producing soluble molecules including colony stimulating factors (CSFs) and various interleukins regulating hematopoiesis. Our data demonstrate that the acute phase response mediators interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha and IL-6 which are abundantly produced by activated monocytes, enhance levels of macrophage-colony stimulating factor (M-CSF) in fibroblasts by both transcriptional and post-transcriptional mechanisms. The action of these proteins to induce M-CSF transcript levels was dependent on synthesis of new proteins and was not mediated by protein kinase C (PKC) stimulation as depletion of cellular PKC pools by prolonged exposure of fibroblasts to phorbolester TPA did not prevent factor induced synthesis of M-CSF transcripts. However, blockade of PKC by the isoquinoline sulfonamide derivative H7 and thus inhibition of phosphorylation was associated with augmentation of the fibroblasts response to TNF-alpha and IL-6.

Collagenase synthesis of rheumatoid arthritis synoviocytes: dose-dependent stimulation by substance P and capsaicin

The synthesis and release of collagenase in the presence of the neuropeptide substance P (SP) and capsaicin, were investigated in vitro using identical synoviocyte cultures from patients with rheumatoid arthritis (RA). On average 10(-12) M SP augmented statistically significantly the collagenase production by approximately a factor of five. An increase in the concentrations up to 10(-6) M SP resulted in a decreased collagenase synthesis, which, however, was still above the level of that of the untreated synoviocytes. Capsaicin, a homovanillic acid derivative that acts as a releaser of SP from primary afferent neurons, caused a strong stimulation of collagenase production and release at 10(-8) and 10(-6) M (about 7 times the amount of the control). With increasing concentrations up to 10(-3) M capsaicin this effect diminished continuously. The experiments clearly show that in RA synoviocytes in vitro SP and capsaicin in low concentrations act as potent inducers of the synthesis and release of collagenase.

Induction of interleukin-1 and -6 in human gingival fibroblast cultures stimulated with Bacteroides lipopolysaccharides

Normal human gingival fibroblasts stimulated in vitro by lipopolysaccharides (LPS) from oral Bacteroides species produced cell-free and cell-associated thymocyte-activating factors (TAF). Neutralization assays using antisera to human interleukin-1 alpha (HuIL-1 alpha), HuIL-1 beta, and HuIL-6 revealed that cell-free TAF was attributable mainly to IL-1 beta and that IL-6 augmented the TAF activity of IL-1 beta in the culture supernatant. Another factor(s), however, may also be involved in cell-free TAF. By contrast, the active entity of cell-associated TAF was ascribed to IL-1 alpha alone. Furthermore, IL-6 was detected mainly in the supernatant of fibroblast cultures stimulated with Bacteroides LPS. Fibroblasts pretreated with natural human beta or gamma interferon, but not those pretreated with alpha interferon, synthesized higher levels of cell-associated IL-1 alpha in response to stimulation by Bacteroides LPS; however, no interferons exhibited direct IL-1-inducing activity or synergistic IL-1-inducing activity with LPS. Endogenously induced beta interferon was suggested to be necessary for fibroblasts to produce cell-associated IL-1 alpha in response to Bacteroides LPS.

Characterization of a specific 20- to 25-kD interleukin-1 inhibitor from cultured human lung macrophages

Alveolar macrophages have the ability to downregulate immune processes in vitro. We have recently suggested the presence of interleukin-1 (IL-1) inhibitors in the supernatants of human bronchoalveolar lavage cells from patients with idiopathic pulmonary fibrosis or sarcoidosis. In the present study, we further analyze the cellular origin and the biologic properties of a 20- to 25-kD IL-1 inhibitor spontaneously produced by cultured human alveolar macrophages (AM). The inhibitor blocks IL-1-induced prostaglandin E2 production by human fibroblasts and the IL-1-related increase of phytohemagglutinin-induced murine thymocyte proliferation. After rigorous IL-1 alpha and IL-1 beta depletion, supernatants of lung macrophages specifically block the binding of IL-1 to its receptor on the murine thymoma cell line EL4-6.1 in a dose-dependent manner. These results indicate that AM from both normal donors and patients produce a specific IL-1 inhibitor that may be of importance in protecting the alveolar environment from the deleterious effects of excessive IL-1 production.

Differential regulation of interleukin-6 expression in human fibroblasts by tumor necrosis factor-alpha and lymphotoxin

The treatment of human diploid fibroblasts with tumor necrosis factor (TNF)-alpha and with lymphotoxin (LT) is associated with induction of interleukin-6 (IL-6) transcripts with TNF-alpha being 10-fold more potent than LT. Here we report on the TNF-alpha/LT-induced signaling mechanisms responsible for the regulation of IL-6 gene expression in these cells. Run-on assays demonstrated that both TNF-alpha and LT increase IL-6 mRNA levels by transcriptional activation of this gene. Stability studies of IL-6 transcripts in fibroblasts showed that TNF-alpha delayed IL-6 mRNA decay but not LT. The induction of IL-6 transcripts by TNF-alpha and LT was not inhibited by the isoquinoline sulfonamide derivative H7. Similarly, depletion of protein kinase C (PKC) by 12-O-tetradecanoyl-phorbol 13-acetate (TPA) did not change the ability of TNF-alpha and LT to induce IL-6 transcripts, demonstrating that stimulation by these agents may not be mediated by activation of PKC. Stimulation of IL-6 transcripts in fibroblasts did also not require new protein synthesis as exposure to the protein synthesis inhibitor cycloheximide (CHX) enhanced accumulation of IL-6 mRNA in the presence or absence of TNF-alpha or LT.

Interleukin-4 regulates mRNA accumulation of macrophage-colony stimulating factor by fibroblasts: synergism with interleukin-1 beta

We demonstrate that macrophage-colony stimulating factor (M-CSF) is expressed in human fibroblasts at the mRNA and protein level. Following activation with both interleukin (IL)-1 beta and IL-4, fibroblasts synthesized M-CSF transcripts detectable by Northern blot analysis with peak expression occurring at 8 h and 12 h, respectively. Exposure of fibroblasts to both cytokines resulted in M-CSF protein release at 60 h of c. 500 U/ml (for IL-1 beta) and 1000 U/ml (for IL-4), relative to a control preparation of recombinant human M-CSF in a murine bone marrow colony assay. Both interleukins synergized to enhance M-CSF mRNA accumulation and their ability to induce M-CSF transcripts could be abolished by treatment with specific neutralizing antibodies. These observations provide support for the idea that fibroblasts may control monocyte/macrophage development and function, and that IL-1 beta and IL-4 are involved in the regulation of this process.

An interleukin 1 inhibitor affects both cell-associated interleukin 1-induced T cell proliferation and PGE2/collagenase production by human dermal fibroblasts and synovial cells

Lipopolysaccharide (LPS) induces cell-associated interleukin 1 (IL 1) production in the human promonocytic cell line U937. Demonstration of cell-associated IL 1 activity was based on the ability of LPS-treated U937 cells, subsequently fixed with paraformaldehyde, to stimulate thymocyte proliferation in the presence of phytohemagglutinin. Like soluble IL 1 (sIL 1), cell-associated IL 1 is capable of inducing PGE2 and/or collagenase production by dermal fibroblasts and human synovial cells in a dose-dependent manner. It is thus a mediator of the inflammatory response owing to a direct intercellular contact located at the membrane level, where bound molecules may trigger inflammation at a local site of action. We reported that the natural (approximately 23 kDa) IL 1 inhibitor (IL 1 INH) from the urine of febrile patients inhibited all the sIL-1-induced biologic activities under investigation and that it acted by binding to the IL 1 receptor, thus blocking the interaction of the monokine with the receptor. Data demonstrate that the IL 1 INH also blocks cell-associated IL 1-induced T cell proliferation and PGE2 production by both dermal fibroblasts and synovial cells as well as collagenase production by the latter cell type. Thus, as for the sIL 1, a feedback mechanism exists for cell-associated IL 1-induced bioactivities.

Tumor necrosis factor inhibitor: purification, NH2-terminal amino acid sequence and evidence for anti-inflammatory and immunomodulatory activities

The urine of some febrile patients has been shown to contain a tumor necrosis factor-alpha-inhibiting activity (TNF-alpha INH) when tested in a cytotoxicity assay using the TNF-susceptible cell line L-929. The inhibitor was purified to homogeneity using a simple three-step procedure which included a TNF-alpha affinity column, cation exchange and reverse-phase chromatography. The NH2-terminal amino acid sequence of the inhibitor showed no sequence similarity with proteins in the data bases used. Using gel filtration, it was shown that TNF-alpha and the inhibitor form a stable complex which eluted with a molecular weight of about 75,000. This value corresponds to the sum of the inhibitor (approximately 30,000) and TNF-alpha (approximately 45,000-50,000) molecular weight. The TNF-alpha INH blocked prostaglandin E2 production by dermal fibroblasts in a dose-dependent manner, providing evidence for antiinflammatory activity. TNF-alpha INH also blocked class I antigen expression in a dose-dependent manner as measured using the human Colo 205 tumor cell line. Furthermore, TNF-alpha INH affected TNF-alpha synergism with IFN-gamma-induced HLA-DR antigen expression but had no effect on IFN-gamma activity. The data presented demonstrate that TNF-alpha bioactivity can be regulated at the protein level.

Regulation of interleukin 1 generation in immune-activated fibroblasts

In the present study we have demonstrated that fibroblasts can generate the inflammatory cytokine interleukin 1 (IL 1) under conditions similar to those abundant in cellular immune responses. Thus, induction of IL 1 requires a sequential two-step protocol which consists of preactivation of mouse embryo fibroblasts (MEF) with crude preparations of T cell or macrophage-derived conditioned media (CM; 72 h), followed by a challenge with lipopolysaccharide (LPS; 24 h). Unstimulated fibroblasts or such cells activated by either CM or LPS produced only low levels of IL 1, while a synergism between both signals was observed for obtaining maximal IL 1-like activity in MEF. Each of a series of individual recombinant lymphokines and cytokines (IL 2, granulocyte/macrophage-colony-stimulating factor, tumor necrosis factor, IL 1 beta and interferons-alpha, beta and gamma) was shown to serve as an efficient priming signal for the induction of IL 1. IL 1-like activity in fibroblasts was detected in cell lysates or associated with the producing-cell membrane but not in culture fluids. Immune-stimulated fibroblasts, activated under such experimental conditions, were shown to actively transcribe mRNA of both IL 1 genes (alpha and beta). For the expression of IL 1-specific mRNA in fibroblasts a single stimulus, provided by either LPS or a lymphokine/cytokine, was sufficient; however, a more intense signal was observed when both stimuli were applied. The IL 1-like biological activity of fibroblast origin was significantly reduced by anti-IL 1 alpha antibodies. Thus, fibroblasts, when activated by immune and bacterial products, generate IL 1 which in turn possibly amplifies cellular immune responses or inflammatory processes in connective tissues.

Differential activity of interleukin 1 alpha and interleukin 1 beta in the stimulation of the immune response in vivo

The biological activities of human recombinant interleukin (IL) 1 alpha and IL 1 beta were compared in different biological systems. The two IL 1 forms were equally active in vitro in inducing proliferation of murine thymocytes and of the murine T helper clone D10.G4.1, and in triggering release of prostaglandin E2 from human skin fibroblasts. In vivo, IL 1 alpha and IL 1 beta were similarly pyrogenic both in rabbits and mice, and could equally increase the circulating levels of the acute phase protein serum amyloid A in mice. However, only IL 1 beta showed immunostimulatory activity in vivo, as it could enhance the number of specific antibody-producing cells in the spleen of mice immunized with either a T-dependent or a T-independent antigen. Although devoid of immunostimulatory activity, IL 1 alpha could efficiently compete immunostimulation induced by IL 1 beta, suggesting an effective interaction with the IL 1 receptor. Thus, IL 1 beta appears to have an important role in the positive regulation of immune responses, while IL 1 alpha may act as down-regulator of the IL 1 beta effect.

Interleukins and tumor necrosis factor in inflammation

Intense research efforts have been directed toward characterizing mediators that control the inflammatory response and regulate the growth, differentiation, and function of cells involved in inflammation. Tumor necrosis factor, or cachectin, and members of a heterogeneous group of peptides called interleukins exhibit a wide spectrum of activities, some of which appear to influence the evolution of inflammatory processes. This review outlines the observations that have led to our current understanding of the biology of tumor necrosis factor and the interleukins. Particular attention is directed toward the evidence suggesting that these cytokines function as mediators of inflammatory responses.

Collagenase gene expression in fibroblasts is regulated by a three-dimensional contact with collagen

Collagenase activity in fibroblasts is regulated by cytokines and the interaction with the extracellular matrix. In this study we demonstrate that fibroblasts cultured within a three-dimensional collagen gel show a strong induction of collagenase gene expression. In addition to increased de novo synthesis most of the secreted enzyme was found to be activated leading to a high collagenolytic activity and complete degradation of collagen matrices after removal of fetal calf serum. Collagen I gene expression was found to be reduced under these conditions. These data suggest a specific modulation of cellular metabolism in response to contact with a three-dimensional collagenous matrix resulting in the divergent regulation of collagen and collagenase.

Interleukin-1 induces interleukin-1 alpha and interleukin-1 beta gene expression in synovial fibroblasts and peripheral blood monocytes

Cellular interactions involved in the chronic inflammatory response, characteristic of those found in the joints of rheumatoid arthritis patients, were investigated by examining the effect of interleukin-1 (IL-1), tumor necrosis factor alpha, and gamma-interferon on the regulation of IL-1 gene expression and production by synovial fibroblasts. Biologically active IL-1 was detected in lysates of IL-1-treated rat and human fibroblasts that had been isolated from synovial tissue by collagenase digestion. Northern blot analysis of RNA isolated from these cells revealed the expression of IL-1 alpha and IL-1 beta transcripts. Neither the IL-1 transcripts nor the biologic activity of IL-1 was found in untreated synovial fibroblasts. The messenger RNA induction in synovial cells was followed by a time- and dose-dependent expression of intracellular IL-1 activity. Human monocytes and human skin fibroblasts also responded to IL-1 treatment by producing IL-1-specific transcripts. These observations suggest that IL-1 plays a key role in stimulating immune and inflammatory responses and in sustaining those responses through continued production at sites of inflammation.

Synovium as a source of interleukin 6 in vitro. Contribution to local and systemic manifestations of arthritis

Synovial inflammation is often associated with systemic changes, such as increased levels of acute phase proteins and hypergammaglobulinemia, which cannot be explained by the cytokines described in synovial fluids and synoviocyte secretions. Interleukin 6 (IL-6) has recently been characterized as a mediator of multiple inflammatory responses. This cytokine promotes T and B lymphocyte growth and differentiation, and acute phase protein synthesis. We therefore examined IL-6 production by human synoviocytes and its presence in synovial fluids. In vitro, synoviocytes spontaneously released IL-6, which was increased by IL-1 and tumor necrosis factor-alpha. Synoviocyte-derived IL-6 activity was able to induce hybridoma-plasmacytoma proliferation, and immunoglobulin and acute-phase protein synthesis. The synovial fluids from patients with diverse arthropathies contained IL-6 activity, but higher levels were present in inflammatory arthropathies than in osteoarthritis. These results demonstrate that synoviocytes are a potent source of IL-6, which can contribute to important manifestations of inflammatory arthropathies.

Interrelated effects of tumor necrosis factor and interleukin 1 on cell viability

Cells are sensitized to the cytolytic effect of tumor necrosis factor (TNF) by simultaneous application of inhibitors of RNA or protein synthesis. Treating cells, in the absence of such inhibitors, with cytokine preparations produced by stimulated mononuclear leukocytes may render them resistant to the cytolytic effect of TNF + the inhibitors. One of the cytokines which induces that resistance was identified as TNF itself (17). As shown in the present study, similar resistance against TNF-mediated killing can be effectively induced also with preparations of cytokines which are depleted of TNF. Fractionation of such TNF-free preparations revealed that their resistance-inducing activity is mediated by interleukin 1 (IL 1). In part of the cell lines in which IL 1 induced resistance to TNF killing, when applied without inhibitors of protein/RNA synthesis, it was found to exert cytolytic effect in the presence of such inhibitors, however, less effectively than TNF. Both TNF and IL 1 thus appear to activate in cells cytolytic mechanisms as well as antagonizing mechanisms which can protect cells from cytolysis.

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.

Effect of synthetic calcium pyrophosphate and hydroxyapatite crystals on the interaction of human blood mononuclear cells with chondrocytes, synovial cells, and fibroblasts

Synthetic calcium pyrophosphate dihydrate crystals and, to a lesser extent, synthetic hydroxyapatite crystals increased the amount of interleukin-1/mononuclear cell factor released by human blood monocytes, as measured by collagenase and prostaglandin E2 production by rabbit chondrocytes, human dermal fibroblasts, and adherent rheumatoid synovial cells. The same crystals also directly induced collagenase and prostaglandin E2 secretion by rabbit chondrocytes, and potentiated the action of interleukin-1/mononuclear cell factor on chondrocytes. These mechanisms may be important in the pathogenesis of the destructive arthropathies associated with these crystals.

The activation of human fibroblast prostaglandin E production by interleukin 1

We have examined the induction of prostaglandin E2 (PGE2) release from fibroblasts by human interleukin 1 (IL-1). A number of fibroblast cell lines appear to respond to IL-1 in a fashion similar to that seen with synovial fibroblast cultures. Using the Gin-1 primary fibroblast cell line, the earliest time where a significant increase in PGE2 release can be detected is 2 hr. Thereafter PGE2 appears to increase dramatically, with levels after 5 hr increased over 50-fold above baseline. IL-1 appears to directly induce the increase in PGE2 since removal of other proteins from culture medium does not affect induction. PGE2 induction by IL-1 also does not require cell proliferation. The induction appears to involve the synthesis of new protein since the enhanced release can be completely blocked by addition of actinomycin D or cycloheximide. Arachidonic acid mobilization in cells does not appear to be altered following IL-1 addition. However, the ability to convert arachidonic acid to PGE2 is increased following 5 hr of culture with IL-1. While increasing the release of PGE2, the addition of phorbol esters, alone or in combination with calcium ionophores, does not mimic the protein synthesis-dependent increase seen with IL-1. Taken together these results suggest that IL-1 induction of fibroblast PGE2 involves the synthesis of new protein or proteins involved in the conversion of free arachidonic acid to PGE2.

12-O-tetradecanoyl-phorbol-13-acetate induction of the human collagenase gene is mediated by an inducible enhancer element located in the 5'-flanking region

Genomic clones coding for human fibroblast collagenase were isolated. By constructing and transfecting mutants with 5' and 3' deletion mutations of the 5' control region of the gene into human or murine cells, we delimited a 32-base-pair sequence at positions -73 to -42 which is required for the induction of transcription by the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate. The DNA element behaves as a 12-O-tetradecanoyl-phorbol-13-acetate-inducible enhancer: it mediates the stimulation of transcription to the heterologous herpes simplex virus thymidine kinase promoter and acts in a position- and orientation-independent manner. Differences in enhancer efficiency in different cell lines are interpreted to indicate differences in the activity of a trans-acting factor.

12-O-tetradecanoyl-phorbol-13-acetate induction of the human collagenase gene is mediated by an inducible enhancer element located in the 5'-flanking region

Genomic clones coding for human fibroblast collagenase were isolated. By constructing and transfecting mutants with 5' and 3' deletion mutations of the 5' control region of the gene into human or murine cells, we delimited a 32-base-pair sequence at positions -73 to -42 which is required for the induction of transcription by the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate. The DNA element behaves as a 12-O-tetradecanoyl-phorbol-13-acetate-inducible enhancer: it mediates the stimulation of transcription to the heterologous herpes simplex virus thymidine kinase promoter and acts in a position- and orientation-independent manner. Differences in enhancer efficiency in different cell lines are interpreted to indicate differences in the activity of a trans-acting factor.

Prostaglandin E2 and collagenase production by fibroblasts and synovial cells is regulated by urine-derived human interleukin 1 and inhibitor(s)

Interleukin 1 (IL-1) possesses multiple biological activities that may be blocked selectively by different inhibitors. Some known inhibitors block the lymphocyte activating factor (LAF/IL-1) but not the mononuclear cell factor (MCF/IL-1) measured by its capacity to stimulate prostaglandin E2 (PGE2) and collagenase production. The presence of IL-1 in vivo may be difficult to detect due to the presence of inhibitor(s) and the level of the inhibitor(s) may vary depending upon pathological conditions. We have found that urine from three patients with monocytic leukemia (M5) contained high levels of inhibitor(s) of MCF/IL-1, whereas urine of normal subjects did not contain significant amounts. Urine from two patients with other blood neoplasic diseases also contained little inhibitory activity. The MCF/IL-1 inhibitor(s), which also acts on human recombinant IL-1 beta, is approximately 25-35 kD, is not retained on concanavalin A-Sepharose column and can be partially destroyed with urea and boiling. At this stage of the purification the fraction containing the MCF/IL-1 inhibitor(s) also inhibits the LAF/IL-1 assay. However, this inhibitor(s) is probably distinct from other inhibitors already described.

Tumor necrosis factor provokes superoxide anion generation from neutrophils

We report that tumor necrosis factor (TNF) provokes superoxide anion generation from human neutrophils. Superoxide anion generation was provoked at TNF concentration of 1 X 10(-11) M and maximal generation was attained at TNF concentration of 1 X 10(-9) M. We also show that movements of intracellular calcium may mediate the TNF-stimulated superoxide anion generation because 8-(diethylamino) octyl 3,4,5-trimethoxybenzoate hydrochloride--but not extracellular EGTA--inhibited the generation of superoxide anion. These results suggest that TNF may mediate some mechanisms of host defense by provoking superoxide anion generation from neutrophils.

Intracellular epidermal interleukin 1-like factors in the human epidermoid carcinoma cell line A431

Normal human epidermal cells produce, in primary culture, activities which stimulate the release of PGE2 and collagenase by dermal fibroblasts; this factor(s) might play an important role in epidermal-dermal interactions. Since these activities were mainly found in the cell lysates with only little being detected in the conditioned media, we investigated further the problem of cell-associated versus released activity in the model of the human epidermoid carcinoma cell line A431. The activities were consistently found in the cell lysate and in the conditioned media only when the cells were leaky. No membrane-associated activities were identified. Purification of the cytosolic activities were identified. Purification of the cytosolic activities yielded two differently charged species both with a MW of approximately 17K. The copurification of PGE2- and collagenase-stimulating activities with thymocyte comitogenic activity suggests a close physiochemical relation to IL-1. The activities described here might therefore correspond to the intracellular counterpart of epidermal IL-1 formerly described as epidermal cell-derived thymocyte activating factor (ETAF) and identified in the conditioned medium of cultured epidermal cells. These observations are of importance when studying the modulation of these activities.

Altered functions of peripheral blood monocytes in homosexual males and intravenous drug users with persistent generalized lymphadenopathy

Persistent generalized lymphadenopathy (PGL) is observed predominantly in subjects at risk of developing AIDS. Twenty-seven individuals belonging to such groups: twelve homosexual males and fifteen intravenous drug users, were investigated for immunological abnormalities with particular attention to monocyte functions. They were compared with five AIDS patients. Twenty out of twenty-two individuals had anti-LAV/HTLV-III antibodies and most had abnormalities characteristic of AIDS: polyclonal hypergammaglobulinemia, decreased cell-mediated immunity, inverted T-cell helper/suppressor ratio and histological alterations of lymph nodes. As for peripheral blood monocyte functions, phagocytic capacity and production of O2- were normal and bactericidal capacity was decreased. Monocytes cultured in the presence of concanavalin A produced less PGE2 and more IL-1/MCF than normal monocytes. Similar abnormalities were found using monocytes from AIDS patients. These data suggest that monocytes from patients with PGL have functional alterations that may be either intrinsic or secondary to lymphocyte dysfunction(s); these alterations do not account for the decreased capacity of lymphocytes to respond to mitogens but may explain the uncontrolled activation of B cells.

Type IX collagen is a potent inducer of PGE2 and interleukin 1 production by human monocyte macrophages

Type IX collagen and its collagenous fragments are potent stimulatory agents on human blood mononuclear cells for the production of prostaglandin E2 and interleukin 1/mononuclear cell factor. Type IX collagen is 2-4-fold more potent that type I and II and 1 alpha-, 2 alpha- and 3 alpha-collagens. This property may be important in the destructive process of cartilage in inflammatory diseases.

Effect of interferon-gamma and 1 alpha,25-dihydroxyvitamin D3 on superoxide anion, prostaglandins E2, and mononuclear cell factor production by U937 cells

Both interferon-gamma (IFN-gamma) and 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3) induce changes in the human monocytic cell line U937 that may reflect cellular differentiation. The effects of recombinant IFN-gamma and 1 alpha,25(OH)2D3 on U937 cells with regard to the release of superoxide anion (O2-), prostaglandin E2 (PGE2), and mononuclear cell factor (MCF) after stimulation with phorbol myristate acetate (PMA) were examined. PMA did not induce O2- production in untreated cells. A 3-day preincubation with IFN-gamma or 1 alpha,25(OH)2D3 resulted in a 5- to 10-fold increase in PMA-stimulated production of O2- as compared to cells preincubated in medium alone. The response was related to IFN-gamma and 1 alpha,25(OH)2D3 concentrations. In contrast, the PMA-induced production of PGE2 and MCF does not require preincubation with either IFN-gamma or 1 alpha,25(OH)2D3. These results suggest that O2- production and cytokine production (i.e., PGE2 and MCF) are modulated by different signals related to maturation processes.

Human recombinant interleukin 1 stimulates collagenase and prostaglandin E2 production by human synovial cells

The pathogenesis and progression of rheumatoid arthritis involves the production of biologically active lymphokines and monokines. Of these, interleukin 1 (IL-1) has been somewhat of a controversial molecule because it seems to evoke various biological responses in several different tissues. In these studies we demonstrate that three biological properties of human monocyte-derived IL-1 (T-lymphocyte activation and human synovial cell prostaglandin E2 and collagenase production) co-purify. The complementary DNA for the prominent pI 7 form of human IL-1 was expressed, purified, and tested. Any controversy now appears resolved since homogeneous recombinant human IL-1 stimulates prostaglandin E2 and collagenase from human synovial cells as well as activates T cells in vitro.

Cachectin/tumor necrosis factor stimulates collagenase and prostaglandin E2 production by human synovial cells and dermal fibroblasts

Cachectin/TNF (tumor necrosis factor), an endotoxin-induced murine macrophage hormone implicated in the pathogenesis of cachexia and shock, has been found capable of stimulating collagenase and prostaglandin E2 (PGE2) production by isolated human synovial cells and dermal fibroblasts. This bioactivity associated with cachectin is comparable to that observed with the monokine interleukin 1 (IL-1), previously suggested as the major mediator of proteolysis. The ability of cachectin/TNF to stimulate collagenase and PGE2 production suggests that it may play a role in tissue destruction and remodelling, as these processes occur in inflammatory diseases.

Stimulation of procollagenase synthesis in human rheumatoid synovial fibroblasts by mononuclear cell factor/interleukin 1

In order to define mechanisms regulating the synthesis of procollagenase in human rheumatoid synovial fibroblasts, the proteins synthesized by cultured cells were labeled with [35S]methionine. Labeled medium proteins were analyzed by SDS-PAGE directly and after immunocomplexing with a specific antibody to human fibroblast collagenase. Labeling of both the predominant form of the enzyme (Mr approximately 55 000) as well as a minor species (Mr approximately 61 000) was increased following incubation with the monokine, mononuclear cell factor/interleukin 1. The approximately 61 kDa form of the procollagenase appears to be a glycosylated form of the approximately 55 kDa precursor based on binding to Con A-Sepharose and decrease in the approximately 61 kDa form after culture in the presence of tunicamycin. Thus, mononuclear cell factor, homologous with interleukin 1, partially purified from monocyte conditioned medium increased incorporation of [35S]methionine into several medium proteins, including those complexed by the anticollagenase antibody. In the presence of mononuclear cell factor/interleukin 1, labeling of the procollagenase was increased 12-14-fold over control cultures incubated with medium alone. Therefore, one of the mechanisms involved in increase of collagenase activity in the medium of cultured synovial fibroblasts in the presence of mononuclear cell factor/interleukin 1 is a stimulation of enzyme protein synthesis.

Cultured human epidermis cells produce cell-associated interleukin 1-like prostaglandin E2- and collagenase-stimulating factors

In order to identify factors which may regulate the functions of dermal fibroblasts, cell lysates and conditioned media of cultured human epidermal cells were tested on dermal fibroblasts for the stimulation of prostaglandin E2- and collagenase-production. Both prostaglandin E2- and collagenase-stimulating activities appeared during epidermal cell culture: after 2 d they were detected in the cell lysate, and after 4 d of culture they were found also in the conditioned media. Molecular sieving chromatography of epidermal cell lysates led to the detection of two main peaks showing concomitant prostaglandin E2- and collagenase-stimulating activities at Mr approximately equal to 18 000 and Mr approximately equal to 10 000. A single peak of concomitant prostaglandin E2- and collagenase-stimulating activities were seen at Mr approximately equal to 10 000 in the epidermal cell conditioned media. This suggests that the cell-associated concomitant prostaglandin E2- and collagenase-stimulating activities are processed from a common precursor molecule and released. Collagenase-stimulating activity without accompanying prostaglandin E2 was also detected in the range of Mr approximately equal to 30 000-45 000.

Human lymphocytes induce a differential release of prostaglandin E2 and interleukin 1-like mononuclear cell factor from normal blood monocytes

Lymphocytes influence the production of both prostaglandin E2 (PGE2) and interleukin 1 (IL 1) by monocytes. We have examined whether these two products are released concomitantly or not under identical culture conditions using monocyte- and lymphocyte-enriched populations obtained on Percoll gradient. IL 1 was measured as mononuclear cell factor (IL 1/MCF). When incubated with concanavalin A, the monocyte-enriched fraction (MF; 80-91% monocytes), but not the lymphocyte-enriched fraction (LF; 95% lymphocytes) produced increasing amounts of PGE2 and MCF. However, when LF cells were added to MF cells in culture, a 40% to 60% decrease of PGE2 secretion was observed whereas the MCF production remained unchanged or increased up to 26-fold. Such a dissociation between IL 1 and PGE2 production by monocytes indicates independent regulation mechanisms in controlling the immune response under the influence of lymphocytes.