TNF-alpha Antibody Research Articles

Suboptimal Clinical Response to Anti-tumor Necrosis Factor alpha (TNFa) Antibody Therapy in a Patient with Severe Rheumatoid Arthritis and Lymphadenopathy: CASE REPORT

This concerns a patient with severe rheumatoid arthritis (RA) and lymphadenopathy (LA) who showed suboptimal clinical response to antitumor necrosis factor alpha (TNFalpha) antibody (Ab), cA2 therapy. The assessment of TNFalpha and IL-6 mRNA expression in the swollen lymph-node (LN) of the patient by reverse transcription, polymerase chain reaction (RT-PCR) before cA2 treatment, showed only enhanced IL-6 production, but not TNFalpha. Moreover, cA2 failed to inhibit in-vitro spontaneous IL-6 production in the LN block culture from the patient. Taken together, these results indicate that IL-6 production in the swollen LNs of the patient might not depend on TNFalpha. This might partly cause suboptimal clinical response to anti-TNFalpha Ab therapy in the patient.

Production of Recombinant Porcine Tumor Necrosis Factor Alpha in a Baculovirus Expression System.

Porcine tumor necrosis factor alpha (TNF-alpha) was produced using a baculovirus system in Spodoptera frugiperda (SF21AE) cells. Cytotoxic activity was detected in supernatant of sonicated SF21AE cells infected with recombinant viruses. The recombinant protein was also demonstrated to be functionally active by its ability to cause apoptosis in Wehi 164 cells. Three distinct bands of 26, 17 and 14 kDa were revealed by Western blot analysis using anti-human TNF-alpha antibody. Moreover, the anti-human TNF-alpha antiserum significantly neutralized the cytotoxic activity of the supernatant of sonicated SF21AE cells infected with recombinant viruses.

Contribution of cytokines on the suppression of lung metastasis.

Weekly injection of a protein-bound polysaccharide PSK in mice with Lewis Lung Cancer (LLC) significantly decreased the number of lung metastatic foci concomitant with enhancement of cytostatic activity in the bronchoalveolar lavage (BAL) cells. These effects were more marked when the agent was given intratracheally, inducing a larger number of pulmonary macrophages, lymphocytes and neutrophils concomitant with increases in BAL tumor necrosis factor-alpha (TNF-alpha), mouse inflammatory protein-alpha (MIP-1alpha), mouse inflammatory protein-beta (MIP-1beta), interleukin-1alpha (IL-1alpha) and interleukin-6 (IL-6), but not interleukin-2 (IL-2) and interleukin-4 (IL-4). Pre-treatment with anti TNF-alpha antibody reduced these effects. The time course and production of PSK-induced cytokines were similar between the tumor-bearing mice and control mice. BAL neutrophils in mice with LLC showed a tendency toward acceleration of O2- production compared with circulating neutrophils. Pulmonary macrophage phagocytosis was also significantly higher in the LLC mice. These results suggest that enhancement of cytostasis appears to be induced by activation and/or improvement of function in inflammatory and immune cells through cytokines under immunomodulator treatment in lung metastasis, possibly via a TNF-alpha-dependent mechanism.

Anti–Tumor Necrosis Factor-Alpha Improves Myocardial Recovery After Ischemia and Reperfusion

Objectives. This study sought to assess the importance of locally released or paracrine myocardial tumor necrosis factor-alpha (TNF-alpha) in the evolution of postischemic myocardial dysfunction and to use immunohistochemical studies to localize TNF-alpha within the myocardium.Background. TNF-alpha is implicated as a systemic mediator in the development of myocardial ischemia–reperfusion injury by promoting leukocyte myocardial infiltration, and it has been shown to originate from noncardiac peripheral mononuclear cells. We have recently documented in a blood-free environment the release of TNF-alpha from the ischemic-reperfused myocardium.Methods. Isolated rat hearts undergoing 1 h of global cardioplegia-induced ischemia and 30 min of reperfusion were investigated with use of the modified Langendorff model. Hearts were randomly divided into three subgroups: group A, control group; and groups B and C, isolated hearts receiving cardioplegic solution containing monoclonal hamster antimurine TNF-alpha antibodies (group B) or hamster IgG (group C).Results. Significant amounts of TNF-alpha were detected in group A and group C effluent on 1 min of reperfusion (752 ± 212 and 958 ± 409 pmol/ml, respectively). However, in group B, TNF-alpha was below detectable levels. In this group, postischemic left ventricular peak systolic pressures, first derivative of the rise in left ventricular pressure (dP/dtmax), pressure-time integral, coronary flow and O2consumption improved (analysis of variance [ANOVA] p < 0.0001 for all variables) compared with values in groups A and C; creatine kinase levels decreased (p < 0.005); and myocardial structure was preserved. Immunohistochemical staining localized TNF-alpha to cardiac myocytes and to endothelial cells.Conclusions. Anti–TNF-alpha neutralizes local TNF-alpha release from cardiac myocytes after ischemia and improves myocardial recovery during reperfusion, indicating that postischemic paracrine TNF-alpha release plays an active role in myocardial dysfunction.

Dissociation of TNF-alpha from endotoxin-induced nitric oxide and acute-phase hypotension.

We tested the concept that tumor necrosis factor-alpha (TNF-alpha) or platelet-activating factor (PAF) mediated Escherichia coli endotoxin lipopolysaccharide (LPS)-induced upregulation of nitric oxide (NO) and acute-phase hypotension (APH) in the rat. LPS (0.5 mg/kg i.v.) given to rats treated with saline or nonimmune goat-derived gamma-globulin (immunoglobulin G, 22 mg/kg i.m.) produced APH and increased plasma concentrations of TNF-alpha and nitrate and nitrite anions (reactive nitrogen intermediates; RNI) and NO in ex vivo incubates of polymorphonuclear neutrophils (PMN) and inducible NO synthase (iNOS) mRNA in PMN. Pretreatment of rats with a polyclonal TNF-alpha antibody (TNF-Ab, 22 mg/kg i.m.) abolished LPS-mediated increases in plasma TNF-alpha but failed to inhibit APH or the NO system. TNF-alpha (8.2 micrograms/kg i.v.) produced transient hypertension and sustained tachycardia and increased plasma TNF-alpha and PMN iNOS mRNA but not RNI. LPS and TNF-alpha decreased spontaneous and calcimycin (Ca2+ ionophore, 1 microM)- and PAF (1 microM)-mediated increases in head-space NO production by rings of mesenteric artery incubated ex vivo. TNF-Ab abolished all effects of TNF-alpha. PAF (25, 50, and 100 ng/kg) produced APH without increasing plasma TNF-alpha, RNI, or PMN iNOS mRNA. The PAF receptor antagonist BN-50730 (80 micrograms/kg i.v.) abolished PAF-induced APH and attenuated LPS-induced increases in RNI. We conclude that 1) LPS produces parallel but unrelated changes in TNF-alpha and RNI in plasma and PMN during the APH of endotoxemia; and 2) endogenous TNF-alpha is not required for LPS-mediated induction of iNOS mRNA, and PAF mediates LPS-induced APH.

Nonenzymatically glycated albumin (Amadori adducts) enhances nitric oxide synthase activity and gene expression in endothelial cells

Hyperglycemia is considered to induce diabetic nephropathy through nonenzymatic glycation of proteins. Since hyperfiltration is likely to be the mechanism initiating the glomerular lesions, we investigated the effects of Amadori glucose adducts in serum albumin on the production of vasoactive mediators, including nitric oxide (NO) and eicosanoids, by endothelial cells (EC). Amadori adducts of glycated albumin induced a dose-response increase in NO synthase activity of murine endothelioma cells, up to 16.4 +/- 2.1-fold increase of basal values (P < 0.0001) at concentrations of 35 mg/ml mimicking physiological serum albumin concentration, and 4.6 +/- 0.8-fold increase at 17 mg/ml (P < 0.001). The effect was still detectable with glycated albumin 1.7 mg/ml, which approaches its estimated concentration in diabetic serum (1.6 +/- 0.3-fold increase, P < 0.05) The phenomenon was reproducible in human umbilical vein endothelial cells, though to a lesser extent, and further studies on murine EC were employed. The mRNA encoding for inducible NO synthase was overexpressed in EC incubated with Amadori adducts of glycated albumin in comparison to native albumin. Glycated albumin induced increased mRNA expression and synthesis of TNF-alpha. The stimulatory effect induced by glycated albumin on NO synthase activity was almost completely inhibited by anti TNF alpha antibodies. 3H-thymidine incorporation by EC was significantly inhibited when cells were grown in presence of glycated albumin (P < 0.001), and the phenomenon was abolished by the coincubation of the NO competitive inhibitor L-NAME. The early glycosylation products increased thromboxane production (P < 0.001), while prostaglandin E2 synthesis was unaffected. These data indicate that Amadori products of glycated albumin modulate NO synthase activity and eicosanoid balance in EC. These effects may be relevant to the hemodynamic changes in the early phases of diabetic nephropathy and in the lasting progression to sclerosis.

Lipid hydroperoxide-induced tumor necrosis factor (TNF)-alpha, vascular endothelial growth factor and neovascularization in the rabbit cornea: effect of TNF inhibition.

Lipid hydroperoxides (LHP) at high concentrations are cytotoxic, but at sublethal concentration, they induce synthesis of cytokine vascular growth factors. Intracorneal injections of 30 μg LHP placed 5 mm from the superior limbus stimulated early vasodilation of limbal vasculature and a rapidly developing, sustained neovascularization. Under these conditions, vessels grew at the rate of 0.3 mm/day to a total length of 7.5 mm, 25 days after injection. Cholesterol peroxides were less effective. Developing vessels were oriented towards the stimulus. Around the developing vessel there was dissolution of the stromal extracellular matrix. The most distal endothelial cells displayed prominent endoplasmic reticulum, a lack of basement membrane or tight junction complexes and leakage of fluorescein dye. Both the injection site and superior quadrant showed increased levels of tumor necrosis factor (TNF)-alpha and vascular endothelial growth factor after exposure to LHP. The neovascular response was inhibited by simultaneous administration of TNF-alpha antibody or pentoxifylline, an inhibitor of TNF-alpha synthesis. This corneal model of peroxide-induced neovascularization should prove useful for temporal studies of events in the initiation and propagation of signals leading to neovascularization, and for evaluating effects of treatment on neovascular growth.

Induction of tumor necrosis factor alpha (TNF alpha) and enhancement of HIV-1 replication in the J22HL60 cell line by Mycoplasma penetrans.

Mycoplasma penetrans isolated from clinical specimens of AIDS patients showed potent activity in tumor necrosis factor alpha (TNF alpha) production in THP-1, U937 and J22HL60 cell lines, and in the enhancement of HIV-1 replication in a dormantly-infected J22HL60 cell line as compared with the activities of other mycoplasmas. Both activities were found in the methanol layer but not in the chloroform layer of the membrane extracted by the Bligh-Dyer method. TNF alpha production was observed in the peritoneal macrophages from both lipopolysaccharide-responsive and -unresponsive mouse strains, and was not inhibited by polymyxin B. The induction of TNF alpha production and enhancement of HIV-1 replication were strongly inhibited by Concanavalin A-Sepharose. The inhibitory effect of Concanavalin A-Sepharose was partially prevented by sugars in the order methyl-alpha-D-mannopyranoside and methyl-alpha-D-glucopyranoside but not methyl-alpha-D-galactopyranoside. Anti-human TNF alpha antibody, however, did not reduce the activity of the methanol layer to enhance HIV-1 replication, suggesting that the methanol layer could enhance HIV-1 replication directly. These results suggest that the carbohydrate derived from M. penetrans might be responsible for the progression of HIV-1 infection.

Interleukin-7 induces anti-Mycobacterium avium activity in human monocyte-derived macrophages.

To examine the modulatory role of interleukin (IL)-7 on intracellular growth of Mycobacterium avium complex (MAC), human macrophages were treated either before or after MAC infection with different concentrations of IL-7. At 100 pg/mL, 1 ng/mL, and 10 ng/mL, treatment with IL-7 before infection stimulated secretion of tumor necrosis factor-alpha (TNF-alpha) from MAC-infected macrophages (increase up to 40%) and resulted in dose-dependent reduction in the number of intracellular bacteria. Pretreatment with IL-7 did not inhibit the secretion of transforming growth factor-beta1 (TGF-beta1). IL-7 added to the macrophage monolayer 4 h after infection resulted in both the secretion of TNF-alpha from MAC-infected macrophages (up to 90% increase, P < .05) and antimycobacterial activity (up to 50% reduction in bacteria, P <.05); however, TGF-beta1 production was not inhibited. IL-7-dependent anti-MAC activity of macrophages was inhibited by anti-human TNF-alpha antibody. These results suggest that IL-7 may contribute to the regulation of the immune response against MAC.

Guinea pig Kurloff (NK-like) cells mediate TNF-dependent cytotoxic activity: analogy with NC effector cells.

Kurloff cells are mononuclear cells possessing a large cytoplasmic inclusion body specific to the guinea pig. In this report, we present strong evidence that Kurloff cells can mediate NC activity against tumor cells in addition to their previously reported NK activity. Using an 18 h 51Cr-release assay we have shown that Kurloff cells were highly effective in killing the TNF-sensitive WEHI 164 target cell line. Lower but significant cytotoxic activity was also observed after only 4 h. However, our results suggest a different mechanism of lysis in the 4 h and 18 h assay. Lysis of WEHI 164 target cells by Kurloff cells in the 4 h assay could be strongly increased in the presence of TPA alone or in combination with ionomycin whereas ionomycin alone was uneffective. In contrast, stimulation of Kurloff cells for 18 h with ionomycin alone or in combination with TPA could induce the release of TNF-like factor(s) as observed by the TNF bioassay using L-929 TNF-sensitive target cells. Release of TNF-like factor(s) could also be induced by stimulation with WEHI 164 target cells. Supernatants of Kurloff cells stimulated for 18 h with TPA + ionomycin were also highly cytotoxic against WEHI 164 target cells, but not against the TNF-resistant P815 target cell line. Pretreatment of these supernatants with antimurine TNF alpha antibodies could almost completely inhibit their cytotoxic activity against WEHI 164 target cells. In contrast, supernatants of Kurloff cells stimulated for only 4 h did not show any TNF-like activity against the L-929 target cell line and were not cytotoxic against WEHI 164 target cells even after 18 h. Taken together, these results suggest that Kurloff cells can mediate NC activity against tumor cells in addition to their previously reported NK activity. By using multiple lytic pathways, these cells may play a crucial role in anti-tumor surveillance and defenses.

Protective Role of TNF-?? in Respiratory Syncytial Virus Infection In Vitro and In Vivo

Respiratory syncytial virus (RSV) infection causes substantial morbidity in young children and immunocompromised adults, yet its pathogenesis is poorly understood. Because the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) may be important in host response to viral infection, HEp-2 cells were treated with TNF-alpha and mice were given TNF-alpha antibody before RSV infection. Pretreatment of HEp-2 cells with TNF-alpha inhibited RSV replication as determined by cytopathic effect. Respiratory syncytial virus-infected BALB/c mice treated with antibody to TNF-alpha had greater maximal weight loss and slower recovery time than control mice. These results suggest a protective role for TNF-alpha in RSV infection.

Effect of cyclo‐oxygenase inhibitors and modulators of cyclic AMP formation on lipopolysaccharide‐induced neutrophil infiltration in mouse lung

1. The adult respiratory distress syndrome (ARDS) is an acute lung inflammation developed after direct or indirect contact with pathogenic agents. In the present study, a mouse model was developed to mimic this condition using aerosolized bacterial lipopolysaccharide (LPS) and to investigate the mechanisms involved in the lung inflammatory response. 2. Inhalation of LPS led to a time and dose-dependent increase in tumour necrosis factor-alpha (TNF-alpha) production and neutrophil recruitment into the bronchoalveolar lavage fluid (BALF) of Balb/c mice. Under the same conditions, neutrophil infiltration was also found in the BALF of the LPS-sensitive mouse strain C3H/HeN, but was absent in the LPS-resistant strain C3H/HeJ. Intranasal administration of murine recombinant TNF-alpha also triggered neutrophil recruitment. 3. One hour after inhalation of LPS, half of the maximal level of TNF-alpha was measured in the BALF, but only a few neutrophils were detected at this time. The peak TNF-alpha concentration was reached at 3 h, when the neutrophil amount started to increase. At 24 h, maximal neutrophil number was found in the BALF and TNF-alpha was no longer present. 4. Pretreatment of mice under different experimental conditions demonstrated that: (a) cycloheximide almost completely blocks both neutrophil recruitment and TNF-alpha production; (b) anti TNF-alpha antibodies block neutrophil recruitment; (c) indomethacin or aspirin enhance by two fold neutrophil recruitment; (d) indomethacin significantly increases TNF-alpha production 1 h after inhalation of LPS; (e) dibutyryl cyclic AMP and prostaglandin E2 (PGE2) block both neutrophil recruitment and TNF-alpha production. 5. It is concluded that aerosolized LPS in mice triggers an acute lung inflammation which can be used as a potential model of inhalational ARDS and that, strategies leading to the elevation of cyclic AMP levels in vivo can be effective in modulating LPS-induced TNF-alpha synthesis and neutrophil recruitment.

In vivo blockade of TNF-alpha by intravenous infusion of a chimeric monoclonal TNF-alpha antibody in patients with rheumatoid arthritis. Short term cellular and molecular effects.

Due to the unknown etiology of RA, specific treatment is not available. Recently, in a double-blinded, placebo-controlled clinical trial, in vivo blockade of TNF-alpha by a single infusion of a chimeric TNF-alpha-blocking mAb, cA2, has proven to be highly effective in the treatment of RA. In parallel to this trial, we tested the consequences of cA2 infusion in ex vivo and in vitro experiments. In this paper, we describe an increase in CD4+ and CD8+ T lymphocyte counts on day 1 and a marked decrease in monocyte counts preferentially on day 7 after cA2 treatment, without major changes in B lymphocyte or NK cell counts. In addition, we found an increased responsiveness of PBMC to CD28 mAb/PMA, but not to CD3 mAb, superantigen staphylococcus enterotoxin B, or PHA on day 1 after infusion. The increase in DNA synthesis of PBMC was paralleled by increased IL-2 mRNA and IL-4 mRNA expression and IL-2 protein secretion in culture supernatants after in vitro stimulation of PBMC with CD28 mAb/PMA. In PBMC, we did not find any significant changes in mRNA or protein expression of CD28 Ag or CD28 ligands, B7-1 and B7-2. Serum concentrations of IL-1 beta, IL-6, and soluble CD14 were significantly diminished after in vivo TNF-alpha blockade. We did not see relevant changes in granulocyte function in vitro after cA2 infusion. Finally, we observed a statistically significant decrease in slCAM-1 molecules in the serum of patients treated with verum compared with that in the serum of subjects given placebo. This change in slCAM-1 concentration was evident on days 1 and 7 after the infusion of 10 mg/kg cA2, whereas it occurred only on day 7 in the serum of patients treated with the low dose (1 mg/kg) of cA2.

Cytoskeletal protein modulation in pulmonary alveolar myofibroblasts during idiopathic pulmonary fibrosis. Possible role of transforming growth factor beta and tumor necrosis factor alpha.

Pulmonary biopsy specimens from ten cases of idiopathic pulmonary fibrosis (IPF) were examined using routine histological stains, including toluidine blue, and immunohistochemistry by means of specific antibodies against alpha-smooth muscle (alpha-SM) actin, desmin, keratin, TGF beta 1, and TNF alpha. The sections were compared with two cases of normal lung. As shown previously, normal alveolar interstitium did not contain alpha-SM actin positive myofibroblasts nor did the alveolar lining contain any significant number of TGF beta 1 or TNF alpha laden epithelial cells. In IPF, during the inflammatory stage, the alveolar myofibroblasts expressed alpha-SM actin and the regenerating type II alveolar epithelium staining strongly with TGF beta 1 and TNF alpha antibodies. The former cytokine was also detected in the interstitial matrix and fibroblastic cells as well as in the wall of vessels. At this stage, a manifest mast cell infiltration was noted. In very fibrotic and cystic alveolar tissue, i.e., at end stage fibrosis, the number of alpha-SM actin positive myofibroblasts as well as that of TNF alpha laden type II epithelial cells diminished, while TGF beta 1 positive cells persisted. Our findings demonstrate that during IPF alveolar type II epithelium constitutes, if not the site of synthesis, at least the main reservoir for TGF beta 1 and TNF alpha. These cytokines, besides their involvement in fibrogenesis, play probably an important role in the expression of alpha-SM actin by alveolar myofibroblasts. Our study suggests the possibility of an interaction between interstitial cells and alveolar epithelium, during IPF.

Tumor necrosis factor-alpha induces substance P in sympathetic ganglia through sequential induction of interleukin-1 and leukemia inhibitory factor.

The present study establishes that tumor necrosis factor-alpha (TNF-alpha) induction of sympathetic substance P (SP) requires sequential induction of both interleukin (IL-1) and leukemia inhibitory factor (LIF). TNF-alpha dose-dependently induces SP, an induction that is secondary to an increase in the SP precursor, preprotachykinin (PPT), mRNA. Since TNF-alpha conditioned medium (CM) mimics the effect of TNF-alpha by raising SP, actions that are not antagonized by a neutralizing TNF-alpha antibody, TNF-alpha induction of SP is mediated by a soluble intermediate or intermediates. The blockade of TNF-alpha action by a specific IL-1 receptor antagonist and the induction of IL-1 mRNA by TNF-alpha suggest that IL-1 is one of the intermediates. Moreover, because immunoprecipitation with LIF antibodies decreases SP-inducing activity of TNF-alpha CM, and because LIF mRNA is also induced by TNF-alpha, LIF is a second intermediate. Furthermore, TNF-alpha-induced LIF mRNA is blocked by the IL-1 receptor antagonist, whereas IL-1-induced LIF mRNA is not affected by TNF-alpha antibodies, suggesting that TNF-alpha first induces IL-1, and IL-1 subsequently induces LIF. These data suggest that TNF-alpha induces SP in sympathetic ganglia through the sequential inductions of IL-1 and LIF.

The effect of conditioned medium from cultured human bronchial epithelial cells on eosinophil and neutrophil chemotaxis and adherence in vitro.

Several studies have demonstrated that bronchial epithelial cells are capable of synthesizing proinflammatory cytokines that may influence eosinophil and neutrophil activity. We have cultured human bronchial epithelial cells to confluence, as explant cultures, and investigated the effect of conditioned medium from these cells on (1) the chemotaxis of eosinophils and neutrophils and (2) the adherence of these cells to cultured human endothelial cells. Analysis of cytokines, namely interleukin-1 beta (IL-1 beta), interleukin-8 (IL-8), tumor necrosis factor alpha (TNF alpha), granulocyte/macrophage colony-stimulating factor (GM-CSF), and RANTES, which are thought to be involved in these processes, demonstrated that all these cytokines were synthesized and released constitutively from the bronchial epithelial cell cultures. Conditioned medium obtained after 24 h of incubation significantly increased the chemotaxis of eosinophils and neutrophils, from median values of 4.0 cells/per high power field (hpf) (range, 3.0 to 7.0) and 17 cells/hpf (range, 13.0 to 25.0), respectively, for medium 199, to median values of 11.0 cells/hpf (range, 9 to 12; P = 0.005) and 30 cells/hpf (range, 19 to 33; p = 0.01). Whereas anti-GM-CSF and anti-IL-8 neutralizing monoclonal antibodies significantly attenuated the conditioned medium-induced chemotaxis of eosinophils and neutrophils, anti-RANTES neutralizing antibody significantly attenuated the chemotaxis of only eosinophils. Conditioned medium also significantly increased the percentage of eosinophils and neutrophils adhering to endothelial cells in a dose-dependent manner. Both anti-human TNF alpha and anti-human IL-1 beta neutralizing antibodies significantly attenuated the conditioned medium-induced adherence of eosinophils and neutrophils to the endothelial cells and were found to have an additive effect when studied together. Similarly, treatment of endothelial cells with either anti-ICAM-1 or anti-E-selectin, for 1 h before co-culture with eosinophils and neutrophils, significantly attenuated the conditioned medium-induced adherence of both eosinophils and neutrophils to endothelial cells. Treatment of endothelial cells with anti-VCAM-1 attenuated the adherence of eosinophils but not neutrophils. These results suggest that human bronchial epithelial cells, through their ability to generate proinflammatory mediators, are likely to play a role in the pathogenesis of airway disease by influencing chemotaxis and adherence of eosinophils and neutrophils.

Spontaneous inflammatory demyelinating disease in transgenic mice showing central nervous system-specific expression of tumor necrosis factor alpha.

Cytokines are now recognized to play important roles in the physiology of the central nervous system (CNS) during health and disease. Tumor necrosis factor alpha (TNF-alpha) has been implicated in the pathogenesis of several human CNS disorders including multiple sclerosis, AIDS dementia, and cerebral malaria. We have generated transgenic mice that constitutively express a murine TNF-alpha transgene, under the control of its own promoter, specifically in their CNS and that spontaneously develop a chronic inflammatory demyelinating disease with 100% penetrance from around 3-8 weeks of age. High-level expression of the transgene was seen in neurons distributed throughout the brain. Disease is manifested by ataxia, seizures, and paresis and leads to early death. Histopathological analysis revealed infiltration of the meninges and CNS parenchyma by CD4+ and CD8+ T lymphocytes, widespread reactive astrocytosis and microgliosis, and focal demyelination. The direct action of TNF-alpha in the pathogenesis of this disease was confirmed by peripheral administration of a neutralizing anti-murine TNF-alpha antibody. This treatment completely prevented the development of neurological symptoms, T-cell infiltration into the CNS parenchyma, astrocytosis, and demyelination, and greatly reduced the severity of reactive microgliosis. These results demonstrate that overexpression of TNF-alpha in the CNS can cause abnormalities in nervous system structure and function. The disease induced in TNF-alpha transgenic mice shows clinical and histopathological features characteristic of inflammatory demyelinating CNS disorders in humans, and these mice represent a relevant in vivo model for their further study.

TNF-alpha mRNA expression in diaphragm muscle after endotoxin administration.

We studied gene expression and production of TNF-alpha in the diaphragm tissue and changes of muscle contractile properties after endotoxin injection (Escherichia coli, 20 mg/kg) in 88 rats. We assessed the muscle contractile properties by force-frequency curves and twitch kinetics using dissected diaphragm muscle strips. The peak tensions of force-frequency curves decreased from control values (2.15 +/- 0.2 kg/cm2) up to 4 h (0.81 +/- 0.17, p < 0.001), and then increased at 6 h (1.36 +/- 0.19, p < 0.05) after endotoxin injection. The cytotoxic activity on L929 cells in arterial blood samples maximally increased at 2 h (p < 0.001), then decreased to 6 h (p < 0.05). TNF-alpha mRNA in diaphragm tissue was detected by Northern blot method at 1 and 1.5 h, and the immunolocalization of TNF-alpha was evaluated at 2 and 4 h by immunohistochemistry in the muscle tissues. Furthermore, preinjection with anti-m TNF-alpha antibody prevented the decrement of force-frequency curves after endotoxin injection of 10 microliters/kg. From this evidence that TNF-alpha gene expression and production occurred in the diaphragm tissue, but anti-m TNF-alpha antibody preinjection prevented the deterioration of diaphragm muscle contractile properties, we suggest that TNF-alpha may act on muscle cells extracellularly.

Effects of Tumor Necrosis Factor-α on Antimitogenicity and Cell Cycle-related Proteins in MCF-7 Cells

Tumor necrosis factor-alpha (TNF-alpha) demonstrated antimitogenic activity in MCF-7 cells (estrogen receptor-positive human breast cancer cells) in a dose- and time-dependent manner (EC-50 of 2.5 ng/ml). This antimitogenic effect of TNF-alpha was accompanied by a decreased number of cells in S phase in a dose- and time-dependent manner. Based on growth arrest experiments using aphidicolin, it is apparent that TNF-alpha acted in early G1 phase. It did not show antimitogenic effects once cells reentered the S phase based on [3H]thymidine incorporation into DNA and cell cycle analysis. Specificity of TNF-alpha was established by using monoclonal anti-human TNF-alpha antibody. On the basis of Western immunoblot analysis of Rb, p53 and cell cycle inhibitory protein (Cip1) (p21) proteins, TNF-alpha decreased Rb protein expression in a dose- and time-dependent manner whereas it increased the expression level of tumor suppressor p53 protein. TNF-alpha also increased the expression level of Cip1 (p21) protein in a dose-dependent manner. This induction of Cip1 (p21) protein was preceded by the induction of p53 protein in MCF-7 cells. Cip1 (p21) protein associated with cyclin D was also increased. Tumor suppressor Rb protein expression was increased during G1 to S phase progression. Cyclin D protein expression levels were not changed in response to TNF-alpha treatment, although serine/threonine kinase inhibitors such as H7 and the protein kinase C inhibitor staurosporine decreased cyclin D expression levels in MCF-7 cells. Based on experiments with staurosporine, it appears that TNF-alpha does not utilize a protein kinase C pathway in MCF-7 cells. Other cell cycle-related proteins such as Cdk2, Cdc2, and Cdk4 did not show any change in response to TNF-alpha. TNF-alpha did not affect complexes between cyclin D and Cdk2, Cdk4, and Rb proteins in MCF-7 cells. Taken together these results suggest that Rb, p53, and Cip1 (p21) proteins mediate TNF-alpha antimitogenic activity, and TNF-alpha induces growth arrest in the G1 phase in MCF-7 cells.

Reciprocal induction of tumor necrosis factor‐α and interleukin‐β activity mediates fibronectin synthesis in coronary artery smooth muscle cells

We previously demonstrated an immune-inflammatory response associated with increased expression of interleukin (IL)-1 beta and fibronectin in graft coronary arteriopathy in piglets following heterotopic heart transplant. Further studies showed that increased endogenously produced IL-1 beta was upregulating fibronectin production by donor coronary artery (CA) smooth muscle cells (SMC). Since co-induction of IL-1 beta and tumor necrosis factor (TNF)-alpha has been shown in other systems, we investigated the possible interaction between these cytokines in regulating fibronectin production in CA SMC. First, we documented increased TNF-alpha expression in vivo in donor compared to host CA. Next, synthesis of fibronectin was measured in host and donor CA SMC following [35S]-methionine radiolabeling and gelatin-sepharose extraction. As previously shown with IL-1 beta, increased donor CA SMC fibronectin synthesis was reduced to host levels in the presence of TNF-alpha antibodies, and exogenous TNF-alpha upregulated fibronectin synthesis in host CA SMC to levels in donor cells. In normal CA SMC, TNF-alpha-stimulated fibronectin production was downregulated to or below control levels in the presence of IL-1 beta antibodies. Likewise, IL-1 beta-stimulated fibronectin synthesis was downregulated to control levels when TNF-alpha neutralizing antibodies were added. Combining TNF-alpha and IL-1 beta enhanced fibronectin production over that observed with either cytokine alone, but was not additive. Thus, our studies suggest that vascular SMC fibronectin synthesis is regulated by reciprocal induction of IL-1 beta and TNF-alpha activity and provide the first demonstration of a 'cytokine loop' modulating matrix production.