Modulation of IL-1 receptor antagonist and TNF-soluble receptors produced by alveolar macrophages and blood monocytes.
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Animals↗
Biomedical subjects
J M Dayer
Publications and source records attributed to J M Dayer.
Interaction of Staphylococcus aureus with human neutrophils and the down-regulation of TNF receptors.
We have shown previously that pre-exposure of neutrophils to TNF significantly enhanced their killing of opsonized Staphylococcus aureus. We now demonstrate that the ability of TNF to enhance the bactericidal activity is dependent on preincubation time; enhancement was still evident when TNF and bacteria were added simultaneously to neutrophils but if TNF addition was delayed by 5 min, no enhancement was seen. Evidence is presented that suggests that this could be related to a down-regulation of TNF receptors by the bacteria, but in addition, the release of TNF receptor fragments may contribute to the inhibition observed. Scatchard analyses demonstrated a decrease from approximately 3000 TNF receptor (receptor binding) sites per cell to 450 following treatment with S. aureus, but essentially no change in receptor affinity. Using mAb directed against the type A (75 kDa) receptor (utr-1) and the type B (55 kDa) receptor (htr-9), it was found that the expression of both receptors was decreased following treatment with the bacteria. The time course of loss of these receptors showed that the surface expression of both molecules was markedly decreased by 5 min which correlated with the loss in ability of TNF to enhance the bactericidal activity. In contrast to changes seen in the binding of TNF, similarly treated neutrophils showed essentially no change in the binding of radiolabeled tripeptide FMLP and, if anything, an increase in the expression of the CD11b Ag (CR3 receptor). When another phagocytic stimulus was used, opsonized fungi (Torulopsis glabrata), a similar depression of TNF binding was also found, but opsonized sheep erythrocytes had no effect on the TNF binding, suggesting that the effects on the TNF receptor cannot be explained simply on the basis of particle phagocytosis.
Down-Regulation↗
1,25-dihydroxyvitamin D3 dissociates production of interstitial collagenase and 92-kDa gelatinase in human mononuclear phagocytes.
To study the effect of mononuclear cell differentiation on metalloproteinase production, the human monocytic cell lines U937 and THP-1 were exposed to two well known differentiating agents, the phorbol esters (phorbol myristate acetate (PMA)) and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3). With U937 cells, PMA-induced differentiation increased the production of both interstitial collagenase and 92-kDa gelatinase, whereas exposure to 1,25-(OH)2D3 induced full interstitial collagenase expression in the absence of any detectable 92-kDa gelatinase production. In fact, when U937 cells were differentiated with PMA and then exposed to vitamin D3, the hormone actually suppressed phorbol-induced 92-kDa gelatinase biosynthesis. With THP-1 cells, PMA also induced the production of 92-kDa gelatinase fully, but unlike U937 cells, the combination of PMA and 1,25-(OH)2D3 was required for substantial interstitial collagenase biosynthesis. As with U937 cells, the addition of 1,25-(OH)2D3 to PMA-differentiated THP-1 cells caused a dose-dependent inhibition of 92-kDa gelatinase production. Northern hybridizations demonstrated that both phorbol esters and vitamin D3 act on monocytic cell lines at a pretranslational level. To determine whether metalloproteinase biosynthesis in normal differentiated mononuclear phagocytes was also modified by 1,25-(OH)2D3, human blood monocytes and alveolar macrophages were exposed to this hormone. In both cell types, basal and Staphylococcal-stimulated 92-kDa gelatinase production was markedly inhibited by 1,25-(OH)2D3. In contrast, interstitial collagenase production was completely unaffected by the hormone. In summary, the two major metalloproteinases produced by monocytic cells are regulated via distinct molecular pathways by the action of PMA and 1,25-(OH)2D3. Furthermore, vitamin D3 completely dissociates the production of 92-kDa gelatinase and interstitial collagenase in human mononuclear phagocytes.
Calcifediol↗
Elevated serum levels of interleukin-1 receptor antagonist in polymyositis/dermatomyositis. A biologic marker of disease activity with a possible role in the lack of acute-phase protein response.
OBJECTIVE: To determine whether the lack of acute-phase protein (APP) response in numerous patients with polymyositis/dermatomyositis (PM/DM) is related to an imbalance between cytokines and cytokine inhibitors. METHODS: Levels of C-reactive protein (CRP), interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF alpha), IL-6, IL-1 receptor antagonist (IL-1ra), TNF soluble receptor 55 kd (sTNFR 55 kd), and sTNFR 75 kd were tested in the serum of 15 patients with PM/DM, 14 patients with spondylarthropathies (SPA), and 12 healthy blood donors. Serum IL-1 beta, TNF alpha, IL-6, IL-1ra, sTNFR were measured by specific immunoassays. RESULTS: Serum levels of CRP were lower in PM/DM patients than in SPA patients. Normal or slightly elevated CRP values were found in 10 of the 15 PM/DM patients, 7 of whom had active myositis. Serum IL-6 levels were significantly higher in SPA patients than in PM/DM patients, whereas serum IL-1ra and sTNFR levels were significantly higher in PM/DM than in SPA patients. IL-1ra levels were particularly elevated in patients with active myositis and decreased in response to treatment. CONCLUSION: These differences in cytokine levels, particularly IL-1ra, between PM/DM and SPA patients are indicative of distinct pathogenic mechanisms. High levels of IL-1ra may account for the weak APP response in some PM/DM patients. Our results suggest that measurement of IL-1ra, together with clinical examination, may provide useful information for the followup of PM/DM patients.
Adult↗
Human monoclonal antibody as an interleukin-10-specific antagonist.
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Antibodies, Monoclonal↗
Elevated serum levels of TNF soluble receptors in patients with positive anti-neutrophil cytoplasmic antibodies.
ANCA are found in various systemic vasculitis and are supposed to play a role in the pathogenesis of the disease, in co-operation with other factors such as cytokines. A total of 36 ANCA-positive and 10 ANCA-negative serum samples were analysed for the presence of TNF soluble receptors (TNF-sR), which are shed from the surface of activated cells and may act as TNF inhibitors. Of the ANCA-positive samples, 67% had elevated TNF-sR75 and 72% had elevated TNF-sR55 compared to ANCA-negative specimens (mean [S.E.] 18.7 [17.3] vs 3.6 [1.5] and 10.5 [9.7] vs 1.9 [0.7] ng/ml, P < 0.01). Elevation of TNF-sR in patients with ANCA suggests that cytokines and their inhibitors are involved in the pathogenesis of ANCA-associated autoimmune diseases.
Analysis of Variance↗
Soluble TNF receptors (TNF-sR55 and TNF-sR75) in lung allograft recipients displaying cytomegalovirus pneumonitis.
Two distinct types of tumor necrosis factor receptors (TNF-R) have been identified (TNF-R55 and TNF-R75). Both TNF-R also exist in soluble forms (TNF-sR), resulting from the release of the extracellular domains (TNF-sR55 and TNF-sR75). TNF-sR may play an important role in vivo as they can bind to TNF alpha and prevent ligand binding to the cellular TNF-R, thus acting as naturally occurring inhibitors of TNF alpha. Sera from lung allograft recipients with cytomegalovirus (CMV) pneumonitis (12 patients) were assayed for TNF-sR55 and TNF-sR75. The concentrations were compared with those from either control lung recipients displaying neither rejection nor infection (12 patients), or lung recipients with allograft rejection (12 patients). Serum TNF-sR55 and TNF-sR75 concentrations were measured by enzyme-linked immunologic binding assay. Serum TNF-sR55 and TNF-sR75 concentrations were significantly higher during CMV pneumonitis (mean +/- SEM: 13.7 +/- 4.7 ng/ml, and 11.7 +/- 2.7 ng/ml, respectively) than during allograft rejection (3.7 +/- 0.3 ng/ml, p < 0.001, and 2.6 +/- 0.6 ng/ml, p < 0.001, respectively). They were also higher than in control subjects (3.6 +/- 0.3 ng/ml, p < 0.001, and 1.9 +/- 0.5 ng/ml, p < 0.001, respectively). Serum TNF alpha concentration was low in case of rejection or in control subjects (< 20 pg/ml). Conversely increased levels of TNF alpha were detected in the serum of six out of the 12 patients with CMV pneumonitis (p < 0.03 versus rejection and control subjects). Ganciclovir treatment of CMV pneumonitis led to a dramatic decrease of TNF alpha, TNF-sR55, and TNF-sR75 serum levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Malignant histiocytosis in the leukaemic stage: a new entity (M5c-AML) in the FAB classification?
Malignant histiocytosis (MH) is a rare, rapidly fatal disorder, characterized by systemic proliferation of abnormal histiocytes. Most patients present with pancytopenia. We report the case of a patient with MH in the leukaemic stage, who presented extremely pronounced general symptoms and multisystemic involvement. Determination of serum cytokines showed high levels of tumor necrosis factor (TNF), interleukin 6 (IL-6) and interleukin 1 receptor antagonist (IL-1ra). Cytogenetic studies proved the monoclonality of the histiocytic proliferation. These findings strongly suggest that we are dealing with a proliferation of activated macrophages (= histiocytes). By analogy with the monoblastic (M5a) and monocytic (M5b) acute leukaemia of the French-American-British (FAB) classification, we propose a new entity, 'M5c', designating acute histiocytic leukaemia.
Bone Marrow↗
Killing of Staphylococcus aureus by tumor necrosis factor-alpha-activated neutrophils. The role of serum opsonins, integrin receptors, respiratory burst, and degranulation.
We have examined the effects of TNF priming on the killing of Staphylococcus aureus by human neutrophils. In the absence of serum opsonins, neutrophils failed to kill S. aureus, and TNF priming did not induce the cells to become bactericidal. Normal human serum, containing complement activity, promoted the killing of the bacteria by neutrophils. Pretreatment of neutrophils for 30 min with TNF significantly enhanced their bactericidal activity. The effects of TNF on neutrophil bactericidal activity was dependent on serum concentration and the degree of enhancement induced increased up to a concentration of 1%. The kinetics of bacterial killing showed that TNF-only enhanced the initial rate of killing, over the first 30 min. Little killing of bacteria occurred in the presence of complement-inactivated serum, and TNF did not stimulate this killing. These results suggest that TNF enhances the neutrophil complement-dependent killing of S. aureus. TNF increased the expression of CR3 (CD11b/CD18) and CR4 (P150, 95; CD11c/CD18) adhesion receptors but not LFA-1 (CD11a/CD18); and mAb against the alpha-chain of either CR3 or CR4 but not LFA-1 prevented the enhancing effects of TNF on the neutrophil bactericidal activity.
Animals↗
[Cytokines and antagonists in septic shock].
During septic shock, cytokines produced by host cells play an important role in the pathogenesis of hemodynamic involvement and cellular lesions. Recently, natural inhibitory substances able to neutralize the biological activity of tumor necrosis factor alpha (TNF alpha) and interleukin-1 (IL-1) were described. These inhibitory molecules are involved in the regulation of the production of these cytokines. Thus, an understanding of these mechanisms could lead to new treatments for septic shock. A review of the interactions of TNF alpha with macrophages, neutrophils and endothelium underlines the key role of TNF alpha in 3 important events of septic shock: neutrophil adherence to endothelium, capillary leak syndrome, and development of disseminated intravascular coagulopathy. In clinical studies, circulating TNF alpha concentrations were elevated and correlated with the severity of the disease. Soluble TNF receptors (TNF-sRI and TNF-sRII) neutralize the biological effect of TNF alpha. Their circulating levels are also increased in meningococcemia, but an imbalance between TNF alpha and TNF-sR was found at the beginning of the disease which could determine the severity of the shock in these patients. The IL-1 system is composed of IL-1 alpha and IL-1 beta, two forms of precursors, two distinct receptors, two soluble fragments of the extramembranous regions of these receptors, and a natural antagonist of IL-1 receptors (IL-1 ra) which could be secreted or remain intracellular. IL-1 ra improved the outcome in some experimental diseases (endotoxemic shock, cerebral malaria arthritis, graft-versus-host reaction). The treatment of septic shock with IL-1 ra is currently being assessed in phase I and II clinical studies. Blockade of cytokines by antibodies or naturally occurring inhibitory molecules could lead to new therapies for septic shock.
Cytokines↗
Soluble tumor necrosis factor receptors in human inflammatory synovial fluids.
OBJECTIVE: To test synovial fluid (SF) for the presence of soluble fragments originating from distinct tumor necrosis factor receptors (TNF-sR55 and TNF-sR75) which bind to TNF and inhibit its biologic activity. METHODS: TNF-sR55 and TNF-sR75 were measured in 62 SF samples by specific immunoassays using monoclonal antibodies. RESULTS: Both TNF-sR were present in all of the SF tested. Their concentrations were higher in SF from patients with seropositive rheumatoid arthritis than in patients with other inflammatory arthritides. The relative amount of TNF-sR75, as compared with TNF-sR55, was higher in seropositive RA SF than in other SF. CONCLUSION: The balance between TNF and its specific inhibitors may be critical to the biologic outcome mediated by this cytokine.
Humans↗
Stimulation by interleukin-1 of renal calcium reabsorption in thyroparathyroidectomized rats.
Recombinant human interleukin-1 (rhIL-1) can induce an elevation in calcium that has been ascribed exclusively to the stimulation of bone resorption. In the present study, we investigated whether rhIL-1 could also enhance the renal tubular reabsorption of calcium. The chronic influence of recombinant human rhIL-1 on renal calcium transport was investigated in thyroparathyroidectomized rats. Administration of rhIL-1 at the dose of 1.5 micrograms/day sc for 6 days induced a significant elevation in plasma calcium that was associated with a slight but significant decrease in the urinary excretion of calcium. Recording of the urinary calcium excretion expressed per ml glomerular filtrate at various plasma calcium levels, as achieved by acutely infusing calcium gluconate, indicates that rhIL-1 enhanced the tubular reabsorption of calcium. The calculated index of the tubular reabsorption of calcium (TRCal) was significantly increased by rhIL-1 (2.18 +/- 0.14 versus 1.79 +/- 0.07 mmol/l GFR, p < 0.05, in vehicle-treated rats). The change in the renal handling of calcium was not associated with stimulation of the tubular reabsorption of magnesium. Acute administration of a large dose (24 micrograms given in a bolus IV injection) of rhIL-1 enhanced within minutes the urinary excretion of prostaglandin E2. This effect was followed by a significant increase in urinary cAMP excretion and associated with a lower urinary calcium excretion. In conclusion, the results presented in this study indicate that rhIL-1 administered chronically selectively stimulated the tubular reabsorption of calcium. Experimental evidence suggests that this effect is mediated by prostaglandin-induced cAMP generation. These data strongly suggest that changes in the tubular handling of calcium could contribute to rhIL-1-induced hypercalcemia.
Absorption↗
C-reactive protein increases production of IL-1 alpha, IL-1 beta, and TNF-alpha, and expression of mRNA by human alveolar macrophages.
The concentration of C-reactive protein (CRP) increases in human plasma up to a thousandfold during inflammatory states. Because tissue macrophages have been shown to have receptors for CRP, the question arises of whether these cells may respond to increased local concentrations of CRP by producing cytokines capable of participating in the inflammatory response. Accordingly, we examined the capacity of alveolar macrophages--relatively accessible human macrophages--to produce interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF-alpha) in response to CRP. We found that production of IL-1 alpha, IL-1 beta, and TNF-alpha, as measured by bioassay and immunoassay, increased in a dose-dependent manner after stimulation by CRP and that the levels of the respective mRNAs analyzed by Northern blot increased proportionally. These findings suggest that one of the functions of CRP may be to stimulate the production of IL-1 and TNF by macrophages at inflammatory sites where alterations of capillary permeability combined with an increased serum level lead to enhanced local concentrations of this acute-phase protein.
Actins↗
Could natural inhibitors of tumor necrosis factor-alpha modify the clinical course of fulminant meningococcemia?
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Adrenal Cortex Hormones↗
Tumour necrosis factor soluble receptors behave as acute phase reactants following surgery in patients with rheumatoid arthritis, chronic osteomyelitis and osteoarthritis.
Tumour necrosis factor-alpha (TNF-alpha) is involved in diverse biological processes including immune and inflammatory reactions and the response to surgical stress. Two soluble TNF receptor protein fragments, TNF-sR55 (from the p55 kD TNF receptor) and TNF-sR75 (from the p75 kD TNF receptor), are released by cells during inflammation and may modulate the e effects of TNF-alpha. We have studied the kinetics of secretion of TNF-alpha, TNF-sR55 and TNF-sR75 in the sera of patients with rheumatoid arthritis (RA) and control subjects with osteoarthritis (OA) or chronic osteomyelitis (OM) before and after major surgery. Significantly higher pre-operative levels of TNF-sR55 and TNF-sR75 were found in RA and OM as compared with OA (P < 0.02). Following surgery, TNF-sR55 increased within 24 h in RA, OM and OA (P < 0.05), whereas TNF-sR75 increased significantly only in OM and OA patients (P < 0.05). By contrast, no TNF-alpha was detectable before and after surgery in any of the subjects, but this may have been due to impaired detection (by ELISA) of TNF-alpha when it is bound to TNF-sR. These findings suggest that TNF-sR55 and TNF-sR75 may be further markers of the host's reaction to inflammatory insults. They may also play a role in modulating the immune and inflammatory reactions by inhibiting the systemic effects of TNF-alpha.
Acute-Phase Reaction↗
Adhesion molecules and cytokine production.
The exchange of cross-talks between cells relies on soluble factors or direct cell-cell contact. Soluble factors increase the expression of cell surface molecules that activate adjacent cells by direct contact to produce cytokines. In the lung, dendritic cells are potent inducers of T-cell proliferation, and the interaction between the two leads to the production of high amounts of TNF alpha and TNF beta. Of the molecules involved in these biologic functions, LFA-3, CD11c, and the combination of beta 1 and beta 2 integrins are the most efficient. However, blocking TNF alpha or TNF beta production does not affect the alloreaction. The interaction between activated T cells and monocytes resulted in a large production of IL-1 beta. In this reaction, CD69, CD2, and the beta 2 integrins (CD11a, b, c, and CD18) and also other molecules such as a 25- to 35-kD glycoprotein play an important part. Finally, interaction between monocytes and fibroblasts leads to the production of large amounts of collagenase and PGE2 by fibroblasts. Cell-associated IL-1, particularly IL-1 alpha and membrane-bound TNF alpha, can also play a crucial role in the process of cell-cell interaction. This interaction may be controlled by inhibitors to IL-1 and TNF.
Animals↗
Regulation of interleukin-1ra, interleukin-1 alpha, and interleukin-1 beta production by human alveolar macrophages with phorbol myristate acetate, lipopolysaccharide, and interleukin-4.
Human alveolar macrophages (AM) are antigen-presenting cells that have an important immune effector function in the lung. We have previously shown that AM produce a specific interleukin-1 (IL-1) inhibitor of 20 to 25 kD that blocks biologic activities of IL-1 alpha and IL-1 beta such as prostaglandin E2 production by fibroblasts. This inhibitor acts as a receptor antagonist (IL-1ra) by binding to the IL-1 receptor. We are now presenting evidence that the natural AM-derived IL-1ra is immunologically identical to IL-1ra cloned from human peripheral blood monocytes and shows a band at 20 kD compatible with the natural glycosylated IL-1ra. No constitutive expression of IL-1 mRNA was detected when analyzed by Northern blot immediately after bronchoalveolar lavage from six control patients. Comparison of in vitro kinetics of IL-1ra, IL-1 alpha, and IL-1 beta analyzed during culture in the presence or absence of phorbol myristate acetate revealed that their mRNA expression was asynchronous. IL-1 alpha and IL-1 beta mRNA were expressed after as little as 15 min, whereas IL-1ra mRNA was detectable only after 3 h in culture. The production of IL-1ra was measured by enzyme-linked immunosorbent assay and compared with that of IL-1 alpha and IL-1 beta. In freshly isolated AM (10(6)/ml), cell-associated IL-1ra was present in an average amount of 2.0 +/- 0.5 ng/ml, i.e., 25 and 100 times more than IL-1 alpha and IL-1 beta, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Blotting, Western↗
Membrane expression and shedding of tumour necrosis factor receptors during activation of human blood monocytes: regulation by desferrioxamine.
Previous studies have shown that desferrioxamine (DFX), an iron chelator preventing the synthesis of hydroxyl radical (OH.), up-regulates the cell-surface expression of tumour necrosis factor-alpha (TNF-alpha) receptors on unactivated human blood monocytes. In the present study, we investigated the regulatory action of DFX on 125I-TNF-alpha binding to monocytes upon exposure to bacterial lipopolysaccharide (LPS). Exposure to LPS (1 microgram/ml) resulted in almost complete loss of 125I-TNF-alpha binding to the surface of monocytes. This down-regulation was reversible and the recovery observed after 18 hr was enhanced by addition of DFX (5 mM). However, binding studies on monocytes pre-exposed to low pH suggested that the DFX-induced increase of 125I-TNF-alpha binding was not due to differences in the number of receptors available but was probably due to a reduction of receptor occupancy by endogenously generated TNF-alpha. Time-course studies of TNF-alpha release from monocytes confirmed the ability of DFX to reduce the extracellular concentration of bioactive TNF-alpha through a decrease of its synthesis and an increase of its inactivation. The latter process was associated with an increased expression of the soluble form of TNF-alpha receptor type II. These results indicate that, in the presence of LPS, DFX increases the release of soluble TNF-alpha receptors from monocytes. Thus, conversely, OH. generated in situ could reduce the shedding of soluble TNF-alpha receptors and, hence, increase the widespread release of bioactive TNF-alpha.
Cell Membrane↗