Recombinant Tumor Necrosis Factor Receptor Research Articles

TNF Receptor: Fc Fusion Protein Downregulates RANKL/OPG Ratio by Inhibiting CXCL16/CXCR6 in Active Ankylosing Spondylitis.

Clinical studies indicate that recombinant tumor necrosis factor receptor:Fc fusion protein (rhTNFR:Fc) quickly alleviates symptoms and physical signs of active Ankylosing Spondylitis (AS), improving the manifestation of spinal inflammation on radiological imaging. However, the regulatory mechanism of rhTNFR:Fc in the chemokine pathway is unclear. Thus we study the mechanism of phlogogenic activity of CXCL16/CXCR6 in AS and the related mechanism of rhTNFR: Fc treatment. Thirty-two cases of active AS were treated with rhTNFR:Fc for 3 consecutive months. Clinical response was evaluated at baseline and after treatment. CXCL16/CXCR6 expression as well as Receptor Activator Of Nuclear Factor-Κb Ligand (RANKL)/Osteoprotegerin (OPG), essential molecules for osteoclast differentiation, were studied in AS before and after treatment. Further, the proliferation of lymphocytes and the RANKL level stimulated by recombinant human CXCL16 (rhCXCL16) were measured in vitro. Thirty cases responded to rhTNFR:Fc treatment. The RANKL level, RANKL/OPG ratio, CXCLl6 level in serum, and CXCLl6 and CXCR6 mRNA levels in active AS were higher than those in controls and treated patients (P<0.001). rhCXCL16 treatment increased lymphocyte proliferation and RANKL level in active AS (P<0.001), but not in controls or treated patients (P>0.05). A positive linear correlation was noted between CXCL16 serum levels and RANKL/OPG ratio and between CXCL16 levels and C-reactive protein results (P<0.001). Our findings suggest that rhTNFR:Fc suppresses inflammation and bone destruction of AS by reducing the RANKL/OPG ratio through inhibition of the CXCL16/CXCR6 pathway.

Immediate Neurological Recovery Following Perispinal Etanercept Years After Brain Injury

Positron emission tomographic brain imaging and pathological examination have revealed that a chronic, intracerebral neuroinflammatory response lasting for years after a single brain injury may occur in humans. Evidence suggests the immune signaling molecule, tumor necrosis factor (TNF), is centrally involved in this pathology through its modulation of microglial activation, role in synaptic dysfunction, and induction of depressive symptoms and neuropathic pain. Etanercept is a recombinant TNF receptor fusion protein and potent TNF inhibitor that has been found to reduce microglial activation and neuropathic pain in multiple experimental models. We report that a single dose of perispinal etanercept produced an immediate, profound, and sustained improvement in expressive aphasia, speech apraxia, and left hemiparesis in a patient with chronic, intractable, debilitating neurological dysfunction present for more than 3 years after acute brain injury. These results indicate that acute brain injury-induced pathologic levels of TNF may provide a therapeutic target that can be addressed years after injury. Perispinal administration of etanercept is capable of producing immediate relief from brain injury-mediated neurological dysfunction.

THU0208 Comparative, Randomized, Simple Blind to Evaluate Efficacy and Safety of Infinitam® (Etanercept), Associated with Methotrexate Compared with Enbrel® (Etanercept) Associated with Methotrexate in Patients with Modeate and Severe Rheumatoid Arthritis

BackgroundTumor necrosis factor alpha (TNFa) is a proinflammatory cytokine than its synthesis increases in patients with Rheumatoid Arthritis, promoting other proinflammatories cytokines and is associated with tenderness and swelling of...

Blocking of tumor necrosis factor activity promotes natural repair of osteochondral defects in rabbit knee

Background and purpose Osteochondral defects have a limited capacity for repair. We therefore investigated the effects of tumor necrosis factor (TNF) signal blockade by etanercept (human recombinant soluble TNF receptor) on the repair of osteochondral defects in rabbit knees.Material and methods Osteochondral defects (5 mm in diameter) were created in the femoral patellar groove in rabbits. Soon after the procedure, a first subcutaneous injection of etanercept was performed. This single injection or, alternatively, 4 injections in total (twice a week for 2 weeks) were given. Each of these 2 groups was divided further into 3 subgroups: a low-dose group (0.05 μg/kg), an intermediate-dose group (0.4 μ g/kg), and a high-dose group (1.6 μ g /kg) with 19 rabbits in each. As a control, 19 rabbits were injected with water alone. The rabbits in each subgroup were killed 4 weeks (6 rabbits), 8 weeks (6 rabbits), or 24 weeks (7 rabbits) after surgery and repair was assessed histologically.Results Histological examination revealed that the natural process of repair of the osteochondral defects was promoted by 4 subcutaneous injections of intermediate-dose etanercept and by 1 or 4 injections of high-dose etanercept at the various time points examined postoperatively (4, 8, and 24 weeks). Western blot showed that rabbit TNFα had a high affinity for etanercept.Interpretation Blocking of TNF by etanercept enabled repair of osteochondral defects in rabbit knee. Anti-TNF therapy could be a strategy for the use of tissue engineering for bone and cartilage repair.

A comparison study of a recombinant tumor necrosis factor receptor:Fc fusion protein (rhTNFR:Fc) and methotrexate in treatment of patients with active rheumatoid arthritis in China

The objective of this study is to evaluate the efficacy and safety of rhTNFR:Fc: a recombinant tumor necrosis factor receptor:Fc fusion protein compared with methotrexate (MTX) in patients with rheumatoid arthritis in China. We treated 238 patients with active rheumatoid arthritis with either twice weekly subcutaneous injection rhTNFR:Fc (25 mg) or weekly oral MTX (mean 15 mg per week) for 24 weeks (registration number: 2003L01264). Clinical responses were defined as the percent improvement in disease activity according to the criteria of the American College of Rheumatology (ACR-N). As compared with MTX-treated patients, more patients who received rhTNFR:Fc had ACR20 improvement in disease activity during the first 2 weeks (P < 0.05). Similarly, more patients treated with rhTNFR:Fc having ACR20, ACR50, ACR70 improvement in disease activity during 8 weeks (P < 0.05). At the end of 12-week treatment, patients received rhTNFR:Fc also had significant improvement at ACR20 (P < 0.05). Compared with oral MTX, patients received rhTNFR:Fc also had significant improvement at ACR70 at the end of 24 weeks treatment (P < 0.05). In conclusion, compared with oral MTX subcutaneous injection, rhTNFR:Fc acted more rapidly to release symptoms and signs of active RA in Chinese patients, and well tolerated in patients with rheumatoid arthritis in China.

Tumor necrosis factor blockade in the management of children with orphan diseases

Tumor necrosis factor (TNF) blockade has been used successfully to treat a number of rheumatic disorders that have a substantial burden of illness. In children, the TNF antagonists are used mainly for the treatment of juvenile idiopathic arthritis (JIA). There are, however, a variety of rare systemic inflammatory diseases, in which TNF blockade appears promising. Preliminary data in adults suggest that several forms of vasculitis appear to be responsive to TNF antagonists-Behcet's disease, polyarteritis nodosa, Wegener granulomatosis, among others. Some of them respond better to infliximab, a chimeric monoclonal anti-TNF antibody, than to etanercept, a recombinant p75 TNF receptor. We describe our limited experience with infliximab in the treatment of three children with rare vasculitic conditions.

Clinical Pharmacokinetics of Etanercept: A Fully Humanized Soluble Recombinant Tumor Necrosis Factor Receptor Fusion Protein

Etanercept, a fully humanized soluble recombinant tumor necrosis factor receptor fusion protein, is an approved treatment for rheumatoid arthritis, juvenile rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and psoriasis. Etanercept is absorbed slowly from the site of subcutaneous injection, with time to peak concentration at approximately 48 to 60 hours, and is cleared slowly from the body with a t(1/2) of 70 to 100 hours. The absolute bioavailability of etanercept was 58% in healthy subjects following subcutaneous administration. The 25-mg twice-weekly dosage regimen generates systemic exposures comparable to 50 mg once weekly, as predicted by pharmacokinetic modeling and simulation and later confirmed by clinical studies. The pharmacokinetics of etanercept in patients with rheumatoid arthritis are comparable to those in healthy individuals and patients with ankylosing spondylitis, congestive heart failure, and psoriasis. In children with polyarticular-course juvenile rheumatoid arthritis, after subcutaneous doses of 0.4 mg/kg twice weekly, the clearance of etanercept may be slightly reduced in children aged 4 to 8 years. Pharmacokinetic simulation predicts that a dose of 0.8 mg/kg once weekly generates comparable systemic exposure as 0.4 mg/kg twice weekly. No requirement for etanercept dosage adjustment is needed when etanercept is coadministered with warfarin, digoxin, or methotrexate.

Etanercept or intravenous immunoglobulin attenuates expression of genes involved in post-myocardial infarction remodeling

Persistently elevated levels of inflammatory cytokines such as tumor necrosis factor (TNF)alpha after acute myocardial infarction (MI) may contribute to maladaptive ventricular remodeling. The aim of the present study was to examine the effects of immunomodulatory therapy with recombinant soluble TNF receptor (TNFR:Fc) or intravenous immunoglobulin (IVIg) on left and right ventricular post-MI remodeling in rats. Adult male Sprague-Dawley rats were subjected to MI by left coronary artery ligation and randomized to treatment with vehicle, TNFR:Fc, or IVIg and sacrificed after 7 days. The main findings were that: (i) TNFR:Fc- and IVIg-treated rats developed less right ventricular (RV) hypertrophy compared to vehicle-treated controls. (ii) LV and arterial pressures in post-MI rats were not affected by the TNFR:Fc or IVIg treatment. (iii) As determined by real-time RT-PCR, both treatments reduced the expression of the hypertrophy-related genes, atrial natriuretic peptide and the ratio of beta/alpha-myosin heavy chains, and genes related to extracellular matrix remodeling (i.e., collagens I and III, matrix metalloproteinase [MMP]-2 and its tissue inhibitor TIMP-1) in the non-ischemic segment of LV and, in particular, in the RV. (iv) Treatment with IVIg, but not TNFR:Fc, reduced MMP-2 zymographic activity in the RV and the expression of genes for TNFalpha and monocyte chemoattractant protein-1. Therapy targeted directly against TNFalpha (i.e., TNFR:Fc) and a more general immunomodulatory approach (i.e., IVIg) in the acute phase of MI attenuates the cardiac remodeling process and expression of genes that are involved. These findings raise the possibility that initiation of immunomodulatory therapy post-MI could be beneficial in preventing the later development of heart failure.

Exacerbation of mycobacterium tuberculosis enteritis masquerading as crohn’s disease after treatment with a tumor necrosis factor-α inhibitor

Infliximab (Remicade; Centocor, Inc, Malvern, Pennsylvania), a chimeric monoclonal antibody to tumor necrosis factor-α (TNF-α), and etanercept (Enbrel; Immunex Corporation, Seattle, Washington), a recombinant tumor necrosis factor receptor fusion protein, are new immunomodulating agents used in the treatment of patients with rheumatoid arthritis. Infliximab has also been approved for the management of moderate-to-severe Crohn’s disease. Both agents block the action of TNF-α, a cytokine that has proinflammatory effects and modulates the cellular immune response. Thus, TNF-α inhibition may increase the risk of infection. Postmarketing reports of adverse effects associated with infliximab and etanercept have prompted the Food and Drug Administration (FDA) to announce the risk of serious infections and sepsis associated with the use of these agents. We describe a patient who was treated with infliximab for what was thought to be Crohn’s disease, who became systemically ill with Mycobacterium tuberculosis enteritis.

Tumor Necrosis Factor Antagonism With Etanercept Improves Systemic Endothelial Vasoreactivity in Patients With Advanced Heart Failure

Anti-tumor necrosis factor (TNF)-alpha therapy with etanercept, a recombinant TNF receptor that binds to and functionally inactivates TNF-alpha, was shown to improve the functional status of patients with congestive heart failure (CHF). Because administration of TNF-alpha has been shown experimentally to depress endothelium-dependent relaxation, we hypothesized that TNF-alpha antagonism with etanercept might improve the depressed systemic endothelial vasodilator function, which importantly contributes to increased peripheral vascular resistance in patients with advanced CHF. Endothelium-dependent (acetylcholine, ACH; 10 to 50 microgram/min) and endothelium-independent (sodium nitroprusside, SNP; 2 to 8 microgram/min) forearm blood flow (FBF) responses were measured by venous occlusion plethysmography in 13 patients with documented CHF (New York Heart Association class III) before, 6 hours after, and 7 days after subcutaneous injection of a single dose of 25 mg etanercept. Maximum ACH-induced FBF increased significantly from 6.9+/-1.0 to 13.0+/-1.6 mL/min per 100 mL of forearm tissue (P<0.05) 6 hours after administration of etanercept and returned to 7.0+/-1.1 mL/min per 100 mL of forearm tissue after 7 days (P=NS), whereas SNP-induced FBF responses were not significantly affected. In contrast, FBF responses were not altered in control CHF patients, who did not receive etanercept (n=5). Etanercept-induced increases in ACH-mediated FBF were closely correlated with baseline TNF-alpha serum levels (r=0.66; P<0.02). The administration of etanercept profoundly improves systemic endothelial vasodilator capacity in patients with advanced heart failure, suggesting an important role of inflammatory mediators for impaired endothelial vasoreactivity in CHF. Improvement of systemic endothelial function might importantly contribute to the beneficial effects of etanercept on the functional status of patients with CHF.

Etanercept reduces hyperalgesia in experimental painful neuropathy

Abstract Etanercept, a recombinant tumor necrosis factor receptor (p75)‐Fc fusion protein competitively inhibits tumor necrosis factor‐alpha (TNF). Etanercept has been successfully used in patients with rheumatoid arthritis, where it reduces pain and inflammation. Because locally produced proinflammatory cytokines play a role in pain after nerve injury, we investigated whether etanercept can reduce pain and hyperalgesia in an animal model of painful neuropathy, the chronic constriction injury of the sciatic nerve. C57BL/6 mice received etanercept or sham treatment by local near‐nerve injection to the injured nerve or by systemic application. Treatment with etanercept reduced thermal hyperalgesia and mechanical allodynia significantly in both modes of application. The effect of etanercept was present in animals that were treated from the time of surgery and in those that were treated from day 6, when hyperalgesia was already present. These results suggest the potential of etanercept as a treatment option for patients with neuropathic pain.

Etanercept reduces hyperalgesia in experimental painful neuropathy.

Etanercept, a recombinant tumor necrosis factor receptor (p75)-Fc fusion protein competitively inhibits tumor necrosis factor-alpha (TNF). Etanercept has been successfully used in patients with rheumatoid arthritis, where it reduces pain and inflammation. Because locally produced proinflammatory cytokines play a role in pain after nerve injury, we investigated whether etanercept can reduce pain and hyperalgesia in an animal model of painful neuropathy, the chronic constriction injury of the sciatic nerve. C57BL/6 mice received etanercept or sham treatment by local near-nerve injection to the injured nerve or by systemic application. Treatment with etanercept reduced thermal hyperalgesia and mechanical allodynia significantly in both modes of application. The effect of etanercept was present in animals that were treated from the time of surgery and in those that were treated from day 6, when hyperalgesia was already present. These results suggest the potential of etanercept as a treatment option for patients with neuropathic pain.

Human Immunodeficiency Virus Type 1 Nef Mediates Sustained Membrane Expression of Tumor Necrosis Factor and the Related Cytokine LIGHT on Activated T Cells

Human immunodeficiency virus (HIV) Nef downregulates the antigen recognition molecules major histocompatibility complex class I and CD4. Downregulation of surface CD4 by Nef relies on the ability of this viral protein to redirect the endocytic machinery to CD4. However, by redirecting the endocytic machinery, Nef may affect the internalization rates of other proteins. Here we show that Nef simultaneously enhances surface expression of the effector cytokines tumor necrosis factor (TNF) and LIGHT, leading to enhanced cytokine activity. A dileucine motif in Nef, which is essential for CD4 downregulation and is involved in the recruitment of adapter protein complexes by Nef, was required to increase surface levels of both cytokines. The physiological impact of the Nef-mediated interference with endocytosis was demonstrated by the fact that a TNF-responsive T-cell line chronically infected with HIV produced higher levels of p24 viral protein following expression of a Nef-green fluorescent protein (GFP) fusion protein. This enhancement was dependent on the levels of membrane-bound TNF, since it was abrogated by a recombinant soluble TNF receptor. Expression of Nef-GFP in human 293T cells reduced the endocytosis of LIGHT, whereas at the same time CD4 internalization was accelerated. Taken together, these results suggest that in infected cells Nef interferes with the internalization of these effector cytokines. By increasing TNF expression, Nef could accelerate disease progression in infected individuals. These findings may help explain the pleiotropic functions that Nef plays during infection and disease.

Detection of membrane-bound tumor necrosis factor (TNF): an analysis of TNF-specific reagents.

Tumor necrosis factor (TNF) exists in two bioactive forms, the membrane integrated form and the proteolytically derived soluble cytokine. Both forms of TNF are involved in a variety of different physiological and pathophysiological situations. Here we analyzed different human and mouse TNF-specific reagents for their ability to determine the expression of membrane-expressed TNF. The data prove some antibodies to be very useful for the analysis of transmembrane TNF expression because these antibodies distinguish between the transmembrane form of TNF and soluble TNF bound to cellular TNF receptors. In addition, we found that recombinant human TNF receptor fusion proteins are advantageous tools to analyze both human and mouse transmembrane TNF expression.

Therapy of rheumatoid arthritis: new developments and trends.

The medical therapy of rheumatoid arthritis (RA) has been influenced strongly during the past decade by the recognition that many patients develop joint damage within the first year of disease. This observation has motivated rheumatologists to initiate disease-modifying antirheumatic drugs (DMARDs) early in the disease course. This trend has been matched by the increased use of combination DMARD therapy, with the aim to maximize control of the signs and symptoms of RA and limit the development of joint damage. The results from controlled clinical trials generally have supported the concept that early, aggressive treatment with DMARDs is superior to less intensive strategies. In addition, certain DMARD combinations are more effective than the individual components of these regimens, but the evidence is strong for only a few DMARD combinations such as methotrexate and cyclosporine A. Three new drugs have been recently approved for the treatment of RA. Celecoxib, a selective cyclooxygenase-2 inhibitor, has similar clinical efficacy as conventional nonsteroidal anti-inflammatory drugs, and in short-term studies causes no more gastric and duodenal ulcers and erosions than patients treated with placebo. Treatment with leflunomide, an inhibitor of pyrimidine synthesis, has been shown in controlled clinical trials to produce significant clinical improvement in 50% to 60% of patients with RA and delay radiologic progression of disease. The era of biologic therapy has dawned with the apparent success of tumor necrosis factor (TNF)-alpha blockade using etanercept, a recombinant TNF receptor:Fc fusion protein, and infliximab, a chimeric anti-TNF monoclonal antibody. These new agents expand our treatment options in RA and should lead to innovative and more effective treatment approaches.

TNF neutralization in MS

<b><i>Objective:</i></b> A double-blind, placebo-controlled phase II study was conducted in 168 patients, most with relapsing-remitting MS, to evaluate whether lenercept would reduce new lesions on MRI. <b><i>Background:</i></b> Tumor necrosis factor (TNF) has been implicated in MS pathogenesis, has been identified in active MS lesions, is toxic to oligodendrocytes in vitro, and worsens the severity of experimental allergic encephalomyelitis (EAE) in animals. Lenercept, a recombinant TNF receptor p55 immunoglobulin fusion protein (sTNFR-IgG p55), protects against EAE. <b><i>Methods:</i></b> Patients received 10, 50, or 100 mg of lenercept or placebo IV every 4 weeks for up to 48 weeks. MRI scans and clinical evaluations were performed at screening, at baseline, and then every 4 weeks (immediately before dosing) through study week 24. <b><i>Results:</i></b> There were no significant differences between groups on any MRI study measure, but the number of lenercept-treated patients experiencing exacerbations was significantly increased compared with patients receiving placebo (<i>p</i> = 0.007) and their exacerbations occurred earlier (<i>p</i> = 0.006). Neurologic deficits tended to be more severe in the lenercept treatment groups, although this did not affect Expanded Disability Status Scale scores. Anti-lenercept antibodies were present in a substantial number of treated patients; serum lenercept trough concentrations were detectable in only a third. Adverse events that increased in frequency in treated patients included headache, nausea, abdominal pain, and hot flushes. <b><i>Conclusions:</i></b> Lenercept failed to be beneficial, but insight into the role of TNF in MS exacerbations was gained.

Recombinant Tumor Necrosis Factor Receptor p75 Fusion Protein (TNFR:Fc) Alters Endotoxin-Induced Activation of the Kinin, Fibrinolytic, and Coagulation Systems in Normal Humans

The effects of inhibition of tumor necrosis factor (TNF) on cell and protease activation were evaluated in 18 normal volunteers given endotoxin (4 ng/kg, i.v.) after an infusion of low (10 mg/m2 i.v., n = 6) or high dose (60 mg/m2 i.v., n = 6) recombinant human dimeric TNF receptor protein (TNFR:Fc) or its vehicle (placebo n = 6). Activation of the coagulation system occurred by 2 h in the TNFR:Fc vehicle-placebo group manifested by decreased prekallikrein functional levels and increased levels of prothrombin F1+2 fragments (p < 0.0001). High or low dose TNFR:Fc delayed the fall in prekallikrein functional levels by 1 h and 4 h, respectively (p < 0.0002), but did not inhibit the increase in circulating levels of prothrombin F1+2 fragments. In contrast, endothelium activation, characterized by increased levels of tissue plasminogen activator, plasminogen activator inhibitor-1, and von Willebrand Factor antigen was blunted by both low and high dose TNFR:Fc (p < 0.001). While the endotoxin-associated decrease in platelet number was not altered, platelet-derived beta-thromboglobulin peak levels were blunted and delayed by TNFR:Fc (p < 0.02). Increased levels of neutrophil elastase were attenuated by low and high dose TNFR:Fc (p < 0.001). These results suggest that although TNF is functionally linked to the activation of endothelium, neutrophils, coagulation, and fibrinolysis, alternative pathways are present in vivo that result in activation of the kallikrein-kinin system after endotoxin-induced TNF release. These alternative pathways may limit some of the anti-inflammatory effects of TNFR:Fc.

Recombinant human tumor necrosis factor receptor (p75) Fc fusion protein (TNFR:Fc) in rheumatoid arthritis.

Tumor necrosis factor (TNF) is the dominant mediator of the cytokine cascade that causes inflammation and joint destruction in rheumatoid arthritis. A new class of agents under investigation, the biologic TNF inhibitors, inhibits the activity of TNF. Recombinant human TNF receptor p75 Fc fusion protein (TNFR:Fc; Enbrel) blocks the activity of the cytokine TNF. The preclinical, Phase I, and Phase II data of TNFR:Fc in rheumatoid arthritis are reviewed in this article. All available data on TNFR:Fc in rheumatoid arthritis were reviewed. These data included published literature and data on file at the manufacturer. TNFR:Fc has been effective in many models of inflammation, including animal models of rheumatoid arthritis and in clinical rheumatoid arthritis trials. Conclusions from a study with TNFR "knockout" mice (genetically altered mice incapable of producing TNFR proteins) demonstrated that p75 TNFR is a natural antagonist of TNF-mediated inflammation. A placebo-controlled, dose-escalation, Phase I trial evaluated the safety and efficacy of TNFR:Fc in patients with rheumatoid arthritis. There were no serious adverse effects reported. A Phase II, randomized, double-blind, placebo-controlled trial evaluated 180 patients with active rheumatoid arthritis whose previous therapy had failed. A dose-response relationship was observed in the number of tender and swollen joints; patients who received the highest dose (16 mg/m2) of TNFR:Fc had the greatest improvement. Treatment was generally well tolerated. TNFR:Fc is nonimmunogenic; no antibodies to TNFR:Fc have been detected thus far in human studies. Preliminary data indicate that TNFR:Fc is an excellent candidate for future long-term studies in the treatment of rheumatoid arthritis.

Preclinical Safety Assessment of the Recombinant TNF Receptor–Immunoglobulin Fusion Protein

The tumor necrosis factor (TNF) is now recognized as one of the most pleiotropic mediators of host defense, immune regulation, and inflammatory response. Due to its broad spectrum of effects, TNF has been implicated as a key mediator in the pathogenesis of acute and chronic inflammatory conditions. The inhibition of bioactive TNF could therefore provide a substantial therapeutic benefit. One approach to a potent TNF antagonist is to use recombinant protein technology in the design of a molecule in which the heavy-chain sequences of an immunoglobulin are fused with the ligand-binding region of the TNF receptor. This paper describes some aspects of the preclinical safety evaluation of the recombinant human TNF receptor–immunoglobulin fusion protein (TENEFUSE). Specific emphasis was placed on transgenic and gene-deleted mice models as central sources of information in the safety evaluation of this TNF antagonist.

Soluble tumor necrosis factor receptors inhibit phorbol myristate acetate and cytokine-induced HIV-1 expression chronically infected U1 cells.

Recombinant human tumor necrosis factor (TNF) binding protein-1 (r-h TBP-1) and recombinant human soluble dimeric TNF receptor (rhu TNFR:Fc) were used to determine the relative contributions of TNF to phorbol myristate acetate (PMA) and cytokine-induced human immunodeficiency virus type 1 (HIV-1) replication in chronically infected cell lines. Treatment of HIV-1-infected promonocytic U1 cells with r-h-TBP-1 or rhu TNFR:Fc reduced PMA-induced HIV-1 p24 antigen production in a concentration-dependent manner, with a maximal inhibition of approximately 90%. Maximal inhibition of p24 antigen production in T-lymphocytic ACH-2 cells was 47% with r-hTBP-1 and 42% with rhu TNFR:Fc. r-hTBP-1 and rhu TNFR:Fc also decreased p24 antigen synthesized by U1 cells in response to other stimuli, including phytohemagglutinin (PHA)-induced supernatant, granulocyte-macrophage colony-stimulating factor, interleukin-6, and TNF. Addition of r-hTBP-1 to U1 cells during the last 4 h of a 24 h incubation with PMA still inhibited p24 antigen production by 15%. U1 cells stimulated with 10(-7) M PMA released approximately 1 ng/ml endogenous TBP-1 with an initial peak observed at 1 h and a second peak at 24 h after PMA stimulation. r-hTBP-1 also partially reversed inhibition of U1 cellular proliferation caused by PMA. Both r-hTBP-1 and rhu TNFR:Fc blocked PMA induction of nuclear factor (NK)- kappa B DNA-binding activity in U1 cells in association with decreases in HIV-1 replication. We conclude that soluble TNF receptors can inhibit stimuli-induced HIV-1 expression and NK- kappa B DNA-binding activity in chronically infected U1 cells.