P55 TNF Receptor Research Articles

Etanercept induces remission of polyarteritis nodosa: a case report.

Etanercept induces remission of polyarteritis nodosa: a case report.

Impact of tumor necrosis factor receptor p55 deficiency in susceptibility of C57BL/6 mice to infection with Leishmania (Leishmania) amazonensis.

Tumor necrosis factor (TNF) is involved in host resistance to several intracellular pathogens. Although the critical role of TNF receptor (TNFR)p55 in Leishmania (Leishmania) major infection has been demonstrated, the impact of TNFRp55 deficiency on L. (L.) amazonensis infection has not been explored. L. (L.) amazonensis-infected TNFRp55(-/-) mice failed to resolve lesions, whereas C57BL/6 wild-type mice completely healed. The susceptibility of the TNFRp55(-/-) mice was characterized by higher lesion size and histopathological damage in comparison with the wild-type mice. A marked increased of the splenic index was observed in the TNFRp55(-/-) mice after 15 weeks infection. These results show that in the absence of TNFRp55, L. (L.) amazonensis-infected knockout mice fail to resolve lesions, whereas wild-type mice completely heal.

Hypothalamo–pituitary–adrenal axis, glucose metabolism and TNF‐α in narcolepsy

Narcolepsy with cataplexy is caused by a deficiency in the production of hypocretin/orexin, which regulates sleep and wakefulness, and also influences appetite, neuroendocrine functions and metabolism. In this case-control study, 11 patients with narcolepsy with cataplexy and 11 healthy adults underwent an oral glucose tolerance test, and dexamethasone suppression/corticotropin-releasing hormone stimulation test. The average age of patients and controls was 35.1 ± 13.2 and 41.0 ± 2.9 years, respectively, body mass index was 28.1 ± 6.6 and 25.5 ± 4.7 kg m(-2) . We did not find evidence of a significantly increased prevalence of disturbed glucose tolerance in patients with narcolepsy. After hypothalamo-pituitary-adrenal axis suppression, the number of non-suppressors did not differ between the groups, indicating normal negative feedback sensitivity. The level of cortisol after dexamethasone suppression was significantly lower in patients with narcolepsy, suggesting a slight basal downregulation and/or a slightly increased negative feedback sensitivity of the major endocrine stress system in narcolepsy. Following corticotropin-releasing hormone stimulation, there were no significant differences in levels of adrenocorticotropic hormone or cortisol, and in adrenocortical responsivity to adrenocorticotropic hormone. Finally, patients with narcolepsy displayed significantly higher plasma levels of tumour necrosis factor alpha, soluble tumour necrosis factor receptor p55, soluble tumour necrosis factor receptor p75 and interleukin 6 after adjustment for body mass index. The present study confirms that narcolepsy by itself is not associated with disturbances of glucose metabolism, but goes along with a subtle dysregulation of inflammatory cytokine production. We also found that dynamic hypothalamo-pituitary-adrenal system response is not altered, whereas negative feedback to dexamethasone might be slightly enhanced.

Therapeutic effects of p75 tumor necrosis factor receptor monoclonal antibody on a rat model of traumatic arthritis

BackgroundThe aim of the present study was to investigate the therapeutic effects of p75 tumor necrosis factor receptor monoclonal antibody D8F2 on a traumatic arthritis model in rats, and to explore the underlying mechanism. MethodsForty male Sprague Dawley rats were randomly divided into five groups: (A) sham operation control group, (B) traumatic arthritis model group, (C) low-dose D8F2 group (1 mg/kg), (D) medium-dose D8F2 group (3 mg/kg), and (E) high-dose D8F2 group (10 mg/kg). Joint fluid samples were collected at 72 h after surgery, and enzyme-linked immunosorbent assay was performed to measure the following inflammatory factors: tumor necrosis factor α (TNF-α) and interleukin 1β. One week after the surgery, rats were killed, and immunohistochemical staining was applied to detect the matrix metalloproteinase (MMP1 and MMP3) expression in the synovium. In cultured synovial fibroblast experiments, the D8F2-induced ubiquitination of TNF receptor–associated factor 2 (TRAF2) was examined by immunoprecipitation, and nuclear translocation of p65 nuclear factor-κB (p65NF-κB) mediated by TNF-α and D8F2 was analyzed by western blotting. ResultsIn the traumatic arthritis model group, the inflammatory factors and MMPs were significantly increased relative to the sham operation control group (P < 0.05), whereas D8F2 could downregulate these factors in a dose-dependent manner (P < 0.05). The results from in vitro studies indicated that D8F2 can induce TRAF2 ubiquitination and inhibit the nuclear translocation of p65NF-κB mediated by TNF-α. Conclusionsp75 Tumor necrosis factor receptor monoclonal antibody has a therapeutic effect on traumatic arthritis, which may occur via the downregulation of inflammatory factors and MMPs at the transcription level because of TRAF2 degradation and inhibited activation of NF-κB.

Immunohistochemical detection of intrathrombotic macrophage-derived cytokines and its application to thrombus age estimation in murine deep vein thrombosis model

We immunohistochemically examined the expression of IFNγ, TNFα, and TNF receptor p55 (TNF-Rp55) in a stasis-induced venous thrombus murine model. IFNγ(+), TNFα(+), and TNF-Rp55(+) cells could be first detected 7, 3, and 3 days after inferior vena cava (IVC) ligation. Thereafter, the numbers of these positive cells increased with time after IVC ligation. Double-color immunofluorescence analyses demonstrated that each molecule was expressed by intrathrombotic macrophages. In all samples with postligation intervals of 7 days or less, IFNγ/macrophage ratio (IFNγ/Mϕ), TNFα/macrophage ratio (TNFα/Mϕ), and TNF-Rp55/macrophage ratio (TNF-Rp55/Mϕ) were <0.2, <0.2, and <0.4, respectively. In contrast, IFNγ/Mϕ and TNFα/Mϕ were greater than 0.2 and 0.3 at ≥10 days after the IVC ligation, respectively. These observations suggested that IFNγ/Mϕ ratios of >0.2 and TNFα/Mϕ ratios of >0.3 indicated thrombus age of ≥10 days. Moreover, TNF-Rp55/Mϕ ratios of >0.7 strongly suggested thrombus age of >14 days. The present study demonstrated that the immunohistochemical detection of IFNγ, TNFα, and TNF-Rp55 was suitable to estimate the age of venous thrombi. However, the variation in TNF-Rp55/Mϕ ratios is wider than those of the other two markers. Thus, IFNγ and TNFα could be more practical markers.

Safe TNF-based antitumor therapy following p55TNFR reduction in intestinal epithelium

TNF has remarkable antitumor activities; however, therapeutic applications have not been possible because of the systemic and lethal proinflammatory effects induced by TNF. Both the antitumor and inflammatory effects of TNF are mediated by the TNF receptor p55 (p55TNFR) (encoded by the Tnfrsf1a gene). The antitumor effect stems from an induction of cell death in tumor endothelium, but the cell type that initiates the lethal inflammatory cascade has been unclear. Using conditional Tnfrsf1a knockout or reactivation mice, we found that the expression level of p55TNFR in intestinal epithelial cells (IECs) is a crucial determinant in TNF-induced lethal inflammation. Remarkably, tumor endothelium and IECs exhibited differential sensitivities to TNF when p55TNFR levels were reduced. Tumor-bearing Tnfrsf1a⁺⁺/⁻ or IEC-specific p55TNFR-deficient mice showed resistance to TNF-induced lethality, while the tumor endothelium remained fully responsive to TNF-induced apoptosis and tumors regressed. We demonstrate proof of principle for clinical application of this approach using neutralizing anti-human p55TNFR antibodies in human TNFRSF1A knockin mice. Our results uncover an important cellular basis of TNF toxicity and reveal that IEC-specific or systemic reduction of p55TNFR mitigates TNF toxicity without loss of antitumor efficacy.

In Vivo Maturation of Allo-Specific CD8 CTL and Prevention of Lupus-like Graft-versus-Host Disease Is Critically Dependent on T Cell Signaling through the TNF p75 Receptor But Not the TNF p55 Receptor

A third signal is required for maturation of effector CD8 CTL in addition to TCR and CD28 engagement. Inflammatory cytokines can provide a third signal; however, in nonpathogen settings (i.e., antitumor responses), the identity of the third signal is not clear. A useful model for in vivo CD8 CTL in the absence of exogenous pathogens is the alloantigen-driven parent-into F1 model of acute graft-versus-host disease (GVHD) characterized by a strong TNF-dependent donor antihost CD8 CTL T cell response. To determine whether TNF acts directly on donor T cells in a signal 3 manner, F1 mice received TNFR 1 (p55) knockout (KO) and/or TNFR 2 (p75) KO donor T cells. Donor p75 KO but not p55KO donor T cells failed to induce acute GVHD phenotype and instead induced a lupus-like chronic GVHD both short and long term because of quantitative and qualitative donor T cell defects, that is, reduced perforin, IFN-γ, and TNF production. Transfer of mixed or matched purified CD4 and CD8 T cells from wild type or p75KO donors demonstrated that optimal CTL maturation required p75 signaling in both CD4 and CD8 T cells. Despite defective p75KO CD4 help for CD8 CTL, p75KO CD4 help for B cells and autoimmunity was intact. These results provide a mechanism by which impaired CD8 CTL could contribute to reduced antiviral and antitumor responses and autoimmunity reported in patients receiving TNF blockers. Our results support the idea that selective p55 blockade may be beneficial by reducing inflammation without compromising CD8 CTL.

Tumor Necrosis Factor in Traumatic Brain Injury: Effects of Genetic Deletion of p55 or p75 Receptor

The role of tumor necrosis factor (TNF) and its receptors after traumatic brain injury (TBI) remains unclear. We evaluated the effects of genetic deletion of either p55 or p75 TNF receptor on neurobehavioral outcome, histopathology, DNA damage and apoptosis-related cell death/survival gene expression (bcl-2/bax), and microglia/macrophage (M/M) activation in wild-type (WT) and knockout mice after TBI. Injured p55 (-/-) mice showed a significant attenuation while p75 (-/-) mice showed a significant worsening of sensorimotor deficits compared with WT mice over 4 weeks postinjury. At the same time point, contusion volume in p55 (-/-) mice (11.1±3.3 mm(3)) was significantly reduced compared with WT (19.7±3.4 mm(3)) and p75 (-/-) mice (20.9±3.2 mm(3)). At 4 hours postinjury, bcl-2/bax ratio mRNA expression was increased in p55 (-/-) compared with p75 (-/-) mice and was associated with reduced DNA damage terminal deoxynucleotidyl transferaseYmediated dUTP nick end labeling (TUNEL-positivity), reduced CD11b expression and increased Ym1 expression at 24 hours postinjury in p55 (-/-) compared with p75 (-/-) mice, indicative of a protective M/M response. These data suggest that TNF may exacerbate neurobehavioral deficits and tissue damage via p55 TNF receptor whose inhibition may represent a specific therapeutic target after TBI.

TNF-Induced Death Signaling Triggers Alveolar Epithelial Dysfunction in Acute Lung Injury

The ability of the alveolar epithelium to prevent and resolve pulmonary edema is a crucial determinant of morbidity and mortality in acute lung injury (ALI). TNF has been implicated in ALI pathogenesis, but the precise mechanisms remain undetermined. We evaluated the role of TNF signaling in pulmonary edema formation in a clinically relevant mouse model of ALI induced by acid aspiration and investigated the effects of TNF p55 receptor deletion, caspase-8 inhibition, and alveolar macrophage depletion on alveolar epithelial function. We found that TNF plays a central role in the development of pulmonary edema in ALI through activation of p55-mediated death signaling, rather than through previously well-characterized p55-mediated proinflammatory signaling. Acid aspiration produced pulmonary edema with significant alveolar epithelial dysfunction, as determined by alveolar fluid clearance (AFC) and intra-alveolar levels of the receptor for advanced glycation end-products. The impairment of AFC was strongly correlated with lung caspase-8 activation, which was localized to type 1 alveolar epithelial cells by flow cytometric analysis. p55-deficient mice displayed markedly attenuated injury, with improved AFC and reduced caspase-8 activity but no differences in downstream cytokine/chemokine production and neutrophil recruitment. Caspase-8 inhibition significantly improved AFC and oxygenation, whereas depletion of alveolar macrophages attenuated epithelial dysfunction with reduced TNF production and caspase-8 activity. These results provide in vivo evidence for a novel role for TNF p55 receptor-mediated caspase-8 signaling, without substantial apoptotic cell death, in triggering alveolar epithelial dysfunction and determining the early pathophysiology of ALI. Blockade of TNF-induced death signaling may provide an effective early-phase strategy for ALI.

Levels of TNF‐α, soluble TNF receptors (sTNFR1, sTNFR2), and cognition in bipolar disorder

Tumor necrosis factor-alpha (TNF-α) may play an important role in bipolar disorder (BD) pathogenesis. There is only one study about a relationship between TNF-α levels and cognitive impairments in BD. The aim of the present study was to see whether TNF-α, soluble P55 TNF receptor (sTNFR1), and soluble P75 TNF receptor (sTNFR2) levels in BD patients are different from controls and to investigate the relationships between the levels of TNF-α, sTNFR1, and sTNFR2 and the cognitive functions in euthymic BD patients and controls. We assessed 54 BD type I patients and 18 controls by using a battery of neuropsychological tests. Serum TNF-α levels were measured using a commercially available enzyme-linked immunosorbent assay, whereas serum sTNFR1 and sTNFR2 levels were measured using a commercially enzyme-amplified sensitivity immunoassay kit. We found that levels of sTNFR1 and sTNFR2 in BD patients were different from controls. No difference was detected between the BD group and the control group for levels of TNF-α. TNF-α level was found to have a negative correlation with the delayed recall in RAVLT. High levels of sTNFR1 and sTNFR2 in euthymic patients showed that it may support that proinflammatory process continues in euthymic period. This is the first study which showed increased sTNFR2 levels in euthymic period, which could be interpreted as a compensatory mechanism and again the first which deals with verbal memory.

Application of Interleukin-22 Mediates Protection in Experimental Acetaminophen-Induced Acute Liver Injury

Acetaminophen (APAP, paracetamol)-induced hepatotoxicity, although treatable by timely application of N-acetylcysteine, can be fatal. Because it is among the common causes of acute liver failure in intensive care units and in light of its gradually increasing incidence, the need for novel therapeutic strategies aimed at severe intoxication is apparent. Recently, it has been shown that IL-22, a STAT3-activating cytokine, has the capability to mediate liver protection. Herein, the protective potential of IL-22 in murine APAP-induced hepatotoxicity was assessed. Intravenous administration of prophylactic IL-22 significantly reduced serum alanine aminotransferase levels and histopathologic damage in APAP-induced liver injury, a process that coincided with increased hepatocyte proliferation invivo. Concomitant gene expression analysis revealed hepatic induction of genes prototypically up-regulated by the IL-22/STAT3 axis, among others suppressor of cytokine signaling-3, lipocalin-2, and α1-antichymotrypsin. Notably, in a translational setting of therapeutic treatment 2 hours after APAP, IL-22 supported protection in the context of suboptimal N-acetylcysteine dosing. IL-22 likewise connected to augmented hepatocyte proliferation in this experimental setting. As detected by analysis of inflammatory cytokine production, systemically applied IL-22 did not display acute immunomodulation/stimulation in otherwise untreated or endotoxemic mice. Those latter observations clearly confirm acute tolerability of systemically applied IL-22. Observations presented altogether suggest that therapeutic IL-22 administration is a conceivable tissue-protective regimen aimed at hard-to-treat patients with severe APAP-induced hepatotoxicity.

Rheumatoid arthritis: still a chronic disease

For many years, few treatment options were available for patients with rheumatoid arthritis, leading to extensive joint damage and increased mortality compared with control groups. Progress in treatment of this chronic disease started in 1980 with the widespread use of methotrexate early in the disease course, followed by the first biological treatment to target the cytokine tumour necrosis factor (TNF) in 2000. 1 Klareskog L Catrina AI Paget S Rheumatoid arthritis. Lancet. 2009; 373: 659-672 Summary Full Text Full Text PDF PubMed Scopus (721) Google Scholar Presently, four anti-TNF monoclonal antibodies and one soluble receptor, etanercept, are marketed. Etanercept is a hybrid molecule composed of the soluble form of the type-2 p75 TNF receptor, which is linked to the fragment crystallisable region of IgG. Inhibition of TNF function results from the binding of TNF to etanercept. As a protein, etanercept is given systemically by subcutaneous self-administered injections of 50 mg once weekly. Methotrexate as a small chemical molecule can be taken orally, subcutaneously, or by intramuscular injection every week. Maintenance, reduction, or withdrawal of etanercept after treatment with etanercept and methotrexate in patients with moderate rheumatoid arthritis (PRESERVE): a randomised controlled trialConventional or reduced doses of etanercept with methotrexate in patients with moderately active rheumatoid arthritis more effectively maintain low disease activity than does methotrexate alone after withdrawal of etanercept. Full-Text PDF

Differences Between Tumor Necrosis Factor–α Receptors Types 1 and 2 in the Modulation of Spinal Glial Cell Activation and Mechanical Allodynia in a Rat Sciatic Nerve Injury Model

Immunohistological analysis of spinal glial cells and analysis of pain behavior in the rat neuropathic pain model were investigated to clarify the function of tumor necrosis factor (TNF)-α receptors p55 type 1 and p75 type 2. Our objective was to investigate changes in hyperalgesia and glial cell activation after injection of antibodies to each TNF receptor in a rat sciatic nerve injury model. Recent research has revealed that activation of spinal glia plays an important role in radicular and neuropathic pain. TNF-α is reportedly a modulator for glial cell activation; however, the precise relationship between TNF-α and its 2 receptors on glial cells has not been fully delineated. Chronic constriction sciatic nerve injury and sham-operated rats were used. Antibodies to p55 or p75 or saline were intrathecally injected at the L5 level into rats with chronic constriction injury. Mechanical allodynia was examined for 2 weeks. Spinal cords were removed for immunohistochemical studies of ionized calcium-binding adaptor molecule 1 or glial fibrillary acidic protein. Saline rats showed significantly more mechanical allodynia and the number of ionized calcium-binding adaptor molecule 1--immunoreactive microglia and glial fibrillary acidic protein--immunoreactive astrocytes were significantly increased in the saline rats compared with sham-operated rats during the 2 weeks. Injection of both antibodies significantly reduced pain behavior and anti-p55 caused significantly greater reduction compared with anti-p75. The numbers of microglia in both the antibodies groups were significantly decreased when compared with the saline group. In addition, the anti-p55 antibody suppressed microglial activation more than the anti-p75 antibody. These results indicate that the microglial TNF-α p55 pathway played a more important role than the TNF-α p75 pathway in the pathogenesis of peripheral nerve injury pain. This suggests that future studies seeking to clarify neuropathic pain should target TNF-α and p55 receptors in microglia.

Murine analogues of etanercept and of F8-IL10 inhibit the progression of collagen-induced arthritis in the mouse

IntroductionEtanercept is a fusion protein consisting of the soluble portion of the p75-tumor necrosis factor receptor (TNFR) and the Fc fragment of human IgG1, which is often used for the treatment of patients with rheumatoid arthritis. F8-IL10 is a human immunocytokine based on the F8 antibody and interleukin-10, which is currently being investigated in rheumatoid arthritis with promising clinical results. We have aimed at expressing murine versions of these two fusion proteins, in order to assess their pharmaceutical performance in the collagen-induced model of rheumatoid arthritis in the mouse.MethodsTwo fusion proteins (termed muTNFR-Fc and F8-muIL10) were cloned, expressed in chinese hamster ovary (CHO) cells, purified and characterized. Biological activity of muTNFR-Fc was assessed by its ability to inhibit TNF-induced killing of mouse fibroblasts, while F8-muIL10 was characterized in terms of muIL10 activity, of binding affinity to the cognate antigen of F8, the alternatively-spliced EDA domain of fibronectin, by quantitative biodistribution analysis and in vivo imaging. The therapeutic activity of both fusion proteins was investigated in a collagen-induced mouse model of arthritis. Mouse plasma was analyzed for anti-drug antibody formation and cytokine levels were determined by bead-based multiplex technology. The association of F8-IL10 proteins with blood cells was studied in a centrifugation assay with radiolabeled protein.ResultsBoth fusion proteins exhibited excellent purity and full biological activity in vitro. In addition, F8-muIL10 was able to localize on newly-formed blood vessels in vivo. When used in a murine model of arthritis, the two proteins inhibited arthritis progression. The activity of muTNFR-Fc was tested alone and in combination with F8-huIL10. The chimeric version of F8-IL10 was not better then the fully human fusion protein and showed similar generation of mouse anti-fusion protein antibodies. Incubation studies of F8-muIL10 and F8-huIL10 with blood revealed that only the fully human fusion protein is not associated with cellular components at concentrations as low as 0.2 μg/ml, thus facilitating its extravasation from blood vessels.ConclusionsThe described products may represent useful research tools for the study of the anti-arthritic properties of TNF blockade and of IL10-based immunocytokines in syngeneic immunocompetent models of arthritis.

TNFRp55 controls regulatory T cell responses in Yersinia‐induced reactive arthritis

In addition to its well-known pro-inflammatory effects, tumor necrosis factor (TNF) displays anti-inflammatory activities through mechanisms poorly understood. Previously, we reported the development of severe chronic Yersinia enterocolitica-induced reactive arthritis (ReA) in mice lacking the TNF receptor (TNFR)p55. As regulatory T (T(reg)) cells limit chronic inflammation, here we aim to investigate the expansion and function of CD4(+)CD25(+)FoxP3(+) T(reg) cells in the ReA animal model. The number of T(reg) cells as well as the FoxP3 mRNA expression and interleukin (IL)-10 levels were significantly decreased in joint regional lymph nodes (RLNs) of TNFRp55(-/-) mice vs wild-type (WT) mice at the arthritis onset. However, at chronic phase of arthritis, the number of T(reg) cell in TNFRp55(-/-) was similar to WT mice. To explore the in vivo function of T(reg) cells at this chronic phase in WT and TNFRp55-deficient mice, we adoptively transferred CD4(+) T cells from TNFRp55-deficient mice of day 21, into naïve WT or TNFRp55(-/-) mice. When knockout mice were used as recipients we observed higher delayed-type hypersensitivity (DTH) responses and joint inflammation after heat-killed Yersinia (HKY) stimulation. Accordingly, we found higher levels of IL-17, interferon (IFN)-γ, IL-6, transforming growth factor (TGF)-β1 and IL-12/23p40 and lower IL-10 levels in RLN of paws challenged with HKY in TNFRp55(-/-) recipient mice. In addition, we found that CD4(+) T cells from TNFRp55(-/-) mice controlled antigen-specific IL-12/23(p40) production in recipient WT mice. Our results show that TNFRp55 controls the induction and function of T(reg) cells through differential regulation of cytokine production, suggesting a novel molecular target for immune intervention in ReA.

3. Novel mouse models for the investigation of neuronal–glial immune interactions

Immune challenge alters central nervous system (CNS)-mediated processes and complex behaviors. Pro-inflammatory cytokines such as interleukin-1 beta (IL-1) and tumor necrosis factor alpha (TNF) are well characterized immunomodulators that mediate multiple aspects of the innate immune response. IL-1 and TNF respectively bind to IL-1 receptor 1 (IL-1R1) and TNF p55 receptor (TNFR1) present on neurons and glia. Systemic or central administration of IL-1 or TNF elicits sickness behaviors including sleep–wake behavior alterations, decreased appetite, and social withdrawal. Furthermore, neurons and glia produce cytokines in response to an immune challenge. Collectively, these observations suggest neuronal–glial interactions involving cytokines are crucial to the manifestation of sickness behavior. Nevertheless, the relative contribution of neurons and glia to the modulation of complex behavior and physiology during immune challenge is not known. To address this knowledge gap, we engineered four transgenic mouse lines that express IL-1R1 or TNFR1 only in the CNS and selectively on neurons or astrocytes. These transgenic mice express either IL-1R1 or TNFR1 cDNA under transcriptional control of neuron-specific enolase or human glial fibrillary acidic protein promoters. Our animals provide a unique tool to study CNS responses to immune challenge independent from peripheral actions of IL-1 or TNF. The systematic and selective examination of neuronal–glial cytokine interactions will further our understanding of the central response to immune activation relevant to a spectrum of pathologies characterized by inflammation.

A study on inhibition of inflammation via p75TNFR signaling pathway activation in mice with traumatic brain injury

ObjectiveTo investigate the effects of and mechanisms underlying the activation of the p75 tumor necrosis factor receptor (p75TNFR) signaling pathway in inflammatory responses in mice with traumatic brain injury. MethodsWe first generated hybridomas that produced antibodies specific for p75TNFR, by inoculating BALB/c mice with antigenic peptides derived from mouse p75TNFR, which is critical to the binding of tumor necrosis factor-alpha (TNF-α) and p75TNFR. The isotype, epitope, titer, specificity, and affinity constant of monoclonal antibodies (mAbs) were determined using commercial kits and enzyme-linked immunosorbent assay. We then screened the agonist antibody via L929 cytotoxicity assay. The levels of inflammatory factors were detected in C57BL/6 mice with traumatic brain injury and then the mice were injected with either saline (control) or p75TNFR agonist mAb. Furthermore, we investigated the effects of p75TNFR agonist mAb on p38MAPK and nuclear factor-κB signals. ResultsSeven mAbs against p75TNFR were generated. Among them, the mAb D8F2 could markedly enhance the cytotoxicity of TNF-α on L929 cells. In a traumatic brain injury model, D8F2 could inhibit the levels of inflammatory factors and downregulate RNA transcription of these factors by suppressing the activation of p38 mitogen-activated protein kinase and nuclear factor-κB. ConclusionThe mAb D8F2 could inhibit posttraumatic inflammatory responses effectively. In this study, we developed an agonist anti-mouse p75TNFR mAb, which may be used in the future to devise new strategies for the clinical treatment of inflammation after trauma.

Brucella abortus–Infected Macrophages Modulate T Lymphocytes to Promote Osteoclastogenesis via IL-17

The pathogenic mechanisms of bone loss caused by Brucella species have not been completely deciphered. Although T lymphocytes (LTs) are considered important to control infection, the mechanism of Brucella-induced T-cell responses to immunopathological features is not known. We present in vitro and in vivo evidence showing that Brucella abortus-induced inflammatory response leads to the activation of LTs, which further promote osteoclastogenesis. Pre-activated murine LTs treated with culture supernatant from macrophages infected with B. abortus induced bone marrow-derived monocytes (BMMs) to undergo osteoclastogenesis. Furthermore, osteoclastogenesis was mediated by CD4(+) T cells. Although B. abortus-activated T cells actively secreted the pro-osteoclastogenic cytokines RANKL and IL-17, osteoclastogenesis depended on IL-17, because osteoclast generation induced by Brucella-activated T cells was completely abrogated when these cells were cultured with BMMs from IL-17 receptor knockout mice. Neutralization experiments indicated that IL-6, generated by Brucella infection, induced the production of pro-osteoclastogenic IL-17 from LTs. By using BMMs from tumor necrosis factor receptor p55 knockout mice, we also demonstrated that IL-17 indirectly induced osteoclastogenesis through the induction of tumor necrosis factor-α from osteoclast precursors. Finally, extensive and widespread osteoclastogenesis was observed in the knee joints of mice injected with Brucella-activated T cells. Our results indicate that activated T cells, elicited by B. abortus-infected macrophages and influenced by the inflammatory milieu, promote the generation of osteoclasts, leading to bone loss.

Interleukin‐1 and tumor necrosis factor α blockade treatment of experimental polymyositis in mice

Histologic studies of the muscles suggest that cytokines are involved in inflammatory myopathy. The therapeutic effects of cytokine blockade are controversial, with anecdotal reports of clinical efficacy. The aim of this study was to discern the significance of interleukin-1 (IL-1) and tumor necrosis factor α (TNFα) as therapeutic targets in polymyositis (PM) by studying their involvement and the effects of their blockade in C protein-induced myositis (CIM), a murine model of PM. C57BL/6 mice were immunized with recombinant skeletal C protein fragments to induce CIM. The expression of IL-1 and TNFα in the muscles of mice with CIM was detected using immunohistochemical and real-time polymerase chain reaction analyses. After the onset of myositis, the mice with CIM were treated with recombinant IL-1 receptor antagonist (IL-1Ra), anti-IL-1R monoclonal antibody, recombinant TNF receptor (p75)-fusion protein (TNFR-Fc), or anti-TNFα monoclonal antibody. The muscles were examined histologically for the severity of myositis. IL-1α- and TNFα-positive macrophages were observed in the muscle tissue of mice with CIM as early as 7 days after immunization. IL-1α, IL-1β, and TNFα expression in the muscles increased as the severity of myositis peaked, at both the messenger RNA and protein levels. Continuous subcutaneous delivery of IL-1Ra resulted in suppression of established CIM. Intermittent delivery (1-day intervals) of anti-IL-1R monoclonal antibody suppressed myositis, while intermittent delivery of IL-1Ra did not suppress myositis. Treatment with anti-TNFα monoclonal antibody and with TNFR-Fc also reduced the severity of CIM. IL-1 and TNF blockade ameliorated CIM after disease onset and should potentially be a new strategy for the treatment of inflammatory myopathy. As IL-1 blockade, treatment with anti-IL-1R monoclonal antibody appeared more feasible than the other approaches.

Role of T cells in ovariectomy induced bone loss—revisited

Role of T cells in ovariectomy induced bone loss—revisited