Contribution Of Tumor Necrosis Factor Research Articles

TNF receptors orchestrate differential neutrophil responses critical to immunity against Staphylococcus aureusskin infection

Abstract As the leading cause of skin and soft tissue infections, Staphylococcus aureus is a major health burden and a continued threat to human health due to the emergence of antibiotic-resistance. Through this current study, we aimed to better characterize the protective immune mechanisms against S. aureus skin infection to identify novel targets for the development of host-directed immunotherapeutics as alternatives to antibiotics. Tumor necrosis factor (TNF) is a master regulatory cytokine whose inhibition is associated with the increased risk of S. aureus skin colonization and infection in humans. Despite the clinical implications, the contribution of TNF and its cognate receptors, TNFR1 and TNFR2, to immunity against S. aureus skin infection is unclear. Utilizing an in vivo mouse model of S. aureus intradermal infection, we determined that immune cell-derived TNF engages with both TNFR1 and TNFR2 to promote protection against S. aureus in the skin. Neutrophil-intrinsic TNFR1 and TNFR2 signaling directed differential antimicrobial mechanisms against S. aureus skin infections. Mechanistically, TNFR1 mediated neutrophil recruitment to the skin, whereas TNFR2 directed neutrophil activation (e.g.-NOX2 activation, ROS production, and PAD4-dependent neutrophil extracellular trap (NET) formation) and prevented systemic dissemination of skin infection. Collectively, our findings revealed non-redundant functions and cellular mechanisms mediated by TNFR1 and TNFR2 in neutrophils for immunity against S. aureus. This study was funded in part by grants R01AR073665 (NKA), R01AR069502 (NKA), R01AI111205 (NKA), and R01AI146177 (NKA) and from the United States National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and National Institute of Allergy and Infectious Diseases (NIAID).

537 Neutrophil-intrinsic TNF receptor signaling directs immunity against staphylococcus aureus

Staphylococcus aureus is the leading cause of skin and soft tissue infections and has become a major health burden due to the emergence of antibiotic-resistant strains. Tumor necrosis factor (TNF) is a proinflammatory cytokine that is rapidly induced upon S. aureus exposure and whose inhibition is associated with increased risk of S. aureus infections in humans. However, the contribution of TNF and cognate receptors, TNFR1 and TNFR2, to host defense against S. aureus skin infections is unclear. Therefore, to determine the host defense role of TNF signaling, we used an in vivo mouse model of S.

198 TNF directs protective neutrophil and IL-17+ γδ T cell responses against Staphylococcus aureus skin infections

Staphylococcus aureus is the leading cause of skin and soft tissue infections and has become a major health burden due to the emergence of antibiotic-resistant strains. To develop alternative therapies to antibiotics, we sought to understand the protective immune mechanisms against S. aureus skin infections mediated by tumor necrosis factor (TNF). TNF is a proinflammatory cytokine that is rapidly induced upon S. aureus exposure and whose inhibition is associated with increased risk of S. aureus infections in humans. However, the contribution of TNF or the cognate receptors, TNFR1 and TNFR2, to host defense against S. aureus skin infections is unclear. Therefore, to determine the host defense role of TNF, we used an in vivo mouse model of S. aureus skin infection whereby TNF, TNFR1, or TNFR2 deficient mice and wildtype (wt) mice were intradermally injected with bioluminescent S. aureus and monitored for 14 days. TNF, TNFR1, and TNFR2 deficient mice exhibited increased lesion sizes and bacterial burden compared to wt mice, suggesting TNF is important against S. aureus skin infections and TNFR1 and TNFR2 have non-redundant roles in TNF-mediated immunity. Since TNF has been reported to contribute to neutrophil trafficking and IL-17 expression, we hypothesized that TNF promotes the previously identified protective neutrophil abscess formation and IL-17+ γδ T cell responses against S. aureus skin infection. In fact, TNF deficient mice had significantly impaired neutrophil recruitment, abscess formation, and diminished skin-infiltrating IL-17+ γδ T cells compared to wt mice. Taken together, these findings indicated that differential TNF signaling by TNFR1 and TNFR2 directs protective neutrophil and IL-17+ γδ T cell responses during S. aureus skin infections, which has implications in the development of novel immune-based therapies as alternatives to antibiotic treatment against S. aureus and potentially other bacterial infections.

Complete ablation of tumor necrosis factor decreases the production of IgA, IgG, and IgM in experimental central nervous system tuberculosis.

Objective(s):This study aimed to explore the contribution of tumor necrosis factor (TNF) in the recruitment of B-cell and secretion of immunoglobulins (Igs) during cerebral tuberculosis (TB).Materials and Methods:In this work, the contributing role of TNF in regulating Ig secretions was investigated by comparing wild type TNF (TNFf/f), B-cell-derived TNF (BTNF-/-), and complete TNF ablation (TNF-/-) in a mouse cerebral Mycobacterium tuberculosis infection. Using flow cytometry and ELISA, we were able to examine the recruitment of B-cell subsets, and the production of Igs; also assessed the expression of surface markers on B cell subsets. Results:Here, we found that TNF-/- mice showed defective expression of IgA, IgG, and IgM antibodies compared with TNFf/f and BTNF-/- mice, which was significantly decreased in the expression of surface markers and co-stimulatory molecules. Moreover, mice that produced low antibody levels were not able to control infection, therefore progressed to disease; providing direct evidence for the TNF gene-regulating humoral immunity during central nervous system (CNS) M. tuberculosis infection. In contrast, BTNF-/- mice controlled the infection and had levels of IgA, IgG, and IgM comparable to TNFf/f mice.Conclusion:Together, our results demonstrate that TNF may serve as an essential regulator of antibody-mediated immune responses in CNS TB. However, the protective level exhibited by TNF-producing B cells could be defined as baseline protection that could be used in the development of new therapeutic targets or designing new vaccines.

288 Anti-TNF Withdrawal in IBD: Relapse and Recapture Rates and Predictive Factors From 160 Patients in a Pan-UK Study

Introduction The mechanisms behind primary non-response (PNR) to infliximab (IFX) in IBD are still incompletely understood. The role of IFX trough levels (TL) and early antibody formation (ATI) during the induction phase (0-2-6 weeks) are contradicting. Furthermore, the evolution of serum tumor necrosis factor (TNF) during IFX induction has been sparsely studied. Aim We investigated if serum markers of inflammation or drug exposure help in understanding what is driving PNR. Methods In this retrospective single-center study, we identified a cohort of 201 anti-TNF naive Crohn's disease (CD) patients who received IFX induction and had serum samples drawn at weeks 0, 2, 6 and 14. In all samples CRP, albumin, TNF (Prometheus Laboratories Inc.), ATI (measured with drug tolerant homogeneous mobility shift assay, Prometheus Laboratories Inc.) and TL (in-house-developed ELISA) were assessed. PNR was defined as complete absence of clinical improvement at week 14 (physician global assessment). All measurements were compared between responders and those with PNR. Results The incidence of PNR was 8% (n=16). In univariate analysis, low albumin at w6 was associated with PNR (P=0.01, Mann Whitney test). We observed a significant increase of serum TNF after each IFX infusion with medians at w0 and w14 of 1.6 pg/ml (IQR 0.9-2.7) and 7.7 pg/ml (IQR 4.5-11.5) respectively (P<0.0001, KruskalWallis test) (see figure 1). In patients with PNR, this rise in TNF (w14-w0) was significantly lower than in responders (P=0.03, Mann Whitney test). In an attempt to classify inflammation driven by TNF relative to the overall inflammation, we compared TNF/CRP ratio between both groups. A stepwise multiple logistic regression model identified albumin at w6 and TNF/CRP at w0 to be independent significant predictors (P<0.01) of PNR to infliximab at w14, with OR (95% CI) of 0.08 (0.02-0.37) and 3.10 (1.54-6.25) respectively. Conclusions A high disease burden (represented by low albumin, high CRP and serum TNF) and not IFX TL or ATI (detectable in 21% of patients at w14) are the most important factors driving PNR to IFX. TNF and CRP separately did not predict primary response but a higher TNF/ CRP ratio before start of IFX was predictive for PNR, contradicting the theorem that PNR might be due to 'non-TNF-driven' disease. Although the median TL at w14 between both groups did not differ significantly (P=0.48), this ratio indicates that the contribution of TNF in inflammation might even be higher in PNR before IFX start, and possibly demanding a higher loading dose. We further observed an increase of serum TNF after each IFX infusion and this was less in PNR. The mechanism behind this increase remains unclear. These results warrant further investigation for the role of disease burden in PNR to IFX.

286 Drug Concentrations and Antibodies to Infliximab Are Inferior to the Impact of Disease Burden in Primary Non-Response to Infliximab in Crohn's Disease Patients

Introduction The mechanisms behind primary non-response (PNR) to infliximab (IFX) in IBD are still incompletely understood. The role of IFX trough levels (TL) and early antibody formation (ATI) during the induction phase (0-2-6 weeks) are contradicting. Furthermore, the evolution of serum tumor necrosis factor (TNF) during IFX induction has been sparsely studied. Aim We investigated if serum markers of inflammation or drug exposure help in understanding what is driving PNR. Methods In this retrospective single-center study, we identified a cohort of 201 anti-TNF naive Crohn's disease (CD) patients who received IFX induction and had serum samples drawn at weeks 0, 2, 6 and 14. In all samples CRP, albumin, TNF (Prometheus Laboratories Inc.), ATI (measured with drug tolerant homogeneous mobility shift assay, Prometheus Laboratories Inc.) and TL (in-house-developed ELISA) were assessed. PNR was defined as complete absence of clinical improvement at week 14 (physician global assessment). All measurements were compared between responders and those with PNR. Results The incidence of PNR was 8% (n=16). In univariate analysis, low albumin at w6 was associated with PNR (P=0.01, Mann Whitney test). We observed a significant increase of serum TNF after each IFX infusion with medians at w0 and w14 of 1.6 pg/ml (IQR 0.9-2.7) and 7.7 pg/ml (IQR 4.5-11.5) respectively (P<0.0001, KruskalWallis test) (see figure 1). In patients with PNR, this rise in TNF (w14-w0) was significantly lower than in responders (P=0.03, Mann Whitney test). In an attempt to classify inflammation driven by TNF relative to the overall inflammation, we compared TNF/CRP ratio between both groups. A stepwise multiple logistic regression model identified albumin at w6 and TNF/CRP at w0 to be independent significant predictors (P<0.01) of PNR to infliximab at w14, with OR (95% CI) of 0.08 (0.02-0.37) and 3.10 (1.54-6.25) respectively. Conclusions A high disease burden (represented by low albumin, high CRP and serum TNF) and not IFX TL or ATI (detectable in 21% of patients at w14) are the most important factors driving PNR to IFX. TNF and CRP separately did not predict primary response but a higher TNF/ CRP ratio before start of IFX was predictive for PNR, contradicting the theorem that PNR might be due to 'non-TNF-driven' disease. Although the median TL at w14 between both groups did not differ significantly (P=0.48), this ratio indicates that the contribution of TNF in inflammation might even be higher in PNR before IFX start, and possibly demanding a higher loading dose. We further observed an increase of serum TNF after each IFX infusion and this was less in PNR. The mechanism behind this increase remains unclear. These results warrant further investigation for the role of disease burden in PNR to IFX.

Independent and additive interaction between tumor necrosis factor β +252 polymorphisms and chronic hepatitis B and C virus infection on risk and prognosis of hepatocellular carcinoma: a case-control study.

To assess the contribution of tumor necrosis factor (TNF)β +252 polymorphisms to risk and prognosis of hepatocellular carcinoma (HCC), we enrolled 150 pairs of sex- and age-matched patients with HCC, patients with cirrhosis alone, and unrelated healthy controls. TNFβ +252 genotypes were determined by polymerase chain reaction with restriction fragment length polymorphism. Multivariate analysis indicated that TNFβ G/G genotype [odds ratio (OR), 3.64; 95%CI, 1.49-8.91], hepatitis B surface antigen (OR, 16.38; 95%CI, 8.30-32.33), and antibodies to hepatitis C virus (HCV) (OR, 39.11; 95%CI, 14.83-103.14) were independent risk factors for HCC. There was an additive interaction between TNFβ G/G genotype and chronic hepatitis B virus (HBV)/HCV infection (synergy index=1.15). Multivariate analysis indicated that factors associated with TNFβ G/G genotype included cirrhosis with Child-Pugh C (OR, 4.06; 95%CI, 1.34-12.29), thrombocytopenia (OR, 6.55; 95%CI, 1.46-29.43), and higher serum α-fetoprotein concentration (OR, 2.53; 95%CI, 1.14-5.62). Patients with TNFβ G/G genotype had poor cumulative survival (p=0.005). Cox proportional hazard model indicated that TNFβ G/G genotype was a biomarker for poor HCC survival (hazard ratio, 1.70; 95%CI, 1.07-2.69). In conclusion, there are independent and additive effects between TNFβ G/G genotype and chronic HBV/HCV infection on risk for HCC. It is a biomarker for poor HCC survival. Carriage of this genotype correlates with disease severity and advanced hepatic fibrosis, which may contribute to a higher risk and poor survival of HCC. Chronic HBV/HCV infected subjects with this genotype should receive more intensive surveillance for early detection of HCC.

Reduced inflammation and lymphoid tissue immunopathology in rhesus macaques receiving anti-tumor necrosis factor treatment during primary simian immunodeficiency virus infection.

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections induce robust, generalized inflammatory responses that begin during acute infection and lead to pathological systemic immune activation, fibrotic damage of lymphoid tissues, and CD4⁺ T-cell loss, pathogenic processes that contribute to disease progression. To better understand the contribution of tumor necrosis factor (TNF), a key regulator of acute inflammation, to lentiviral pathogenesis, rhesus macaques newly infected with SIVmac239 were treated for 12 weeks in a pilot study with adalimumab (Humira), a human anti-TNF monoclonal antibody. Adalimumab did not affect plasma SIV RNA levels or measures of T-cell immune activation (CD38 or Ki67) in peripheral blood or lymph node T cells. However, compared with untreated rhesus macaques, adalimumab-treated rhesus macaques showed attenuated expression of proinflammatory genes, decreased infiltration of polymorphonuclear cells into the T-cell zone of lymphoid tissues, and weaker antiinflammatory regulatory responses to SIV infection (ie, fewer presumed alternatively activated [ie, CD163⁺] macrophages, interleukin 10-producing cells, and transforming growth factor β-producing cells), along with reduced lymphoid tissue fibrosis and better preservation of CD4⁺ T cells. While HIV/SIV replication drives pathogenesis, these data emphasize the contribution of the inflammatory response to lentiviral infection to overall pathogenesis, and they suggest that early modulation of the inflammatory response may help attenuate disease progression.

Time-dependent effects of Klebsiella pneumoniae endotoxin on hepatic drug-metabolizing enzyme activity in rats.

The time-dependent effects of Klebsiella pneumoniae endotoxin on hepatic cytochrome P450-dependent drug-metabolizing capacity (cytochrome P450 and b5 content, activity of aminopyrine N-demethylase, p-nitroanisole O-demethylase, aniline hydroxylase and benzphetamine N-demethylase) and on the pharmacokinetics of antipyrine have been determined in rats. Measurement of enzyme activity and antipyrine (after intravenous injection of 20 mg kg(-1)) were performed 2, 24 and 96 h after a single intraperitoneal injection of endotoxin (1 mg kg(-1)) and after repeated doses (once daily for 4 days). The contribution of tumour necrosis factor alpha (TNFalpha) to the endotoxin-induced changes was also examined in rats pretreated with granulocyte colony-stimulating factor (G-CSF). The systemic clearance of antipyrine and the activity of hepatic cytochrome P450-dependent drug-metabolizing enzymes were dramatically reduced 24 h after a single injection of endotoxin, but had returned to control levels by 96h. The magnitudes of these decreases in these measurements after repeated doses of endotoxin were similar to those seen 24h after the single dose. The systemic clearance of antipyrine correlated significantly with cytochrome P450 content and aminopyrine N-demethylase activity. In histopathological experiments, moderate hypertrophy of Kupffer cells was observed, with no evidence of severe liver-tissue damage. G-CSF pretreatment suppressed the increased plasma concentrations of TNFalpha produced 2 h after single endotoxin injection, but did not eliminate the endotoxin-induced decrease in the systemic clearance of antipyrine, suggesting that TNFalpha is not the sole component responsible for the reduction of cytochrome P450-mediated drug-metabolizing enzyme activity. These results provide evidence that a single intraperitoneal injection of 1.0 mgkg(-1)K. pneumoniae endotoxin in rats reduces hepatic P450 and b5 levels, and reduces the activity of various cytochrome P450-mediated drug-metabolizing enzymes without causing severe liver-tissue damage. This suggests that the effect of endotoxin on hepatic cytochrome P450-mediated drug-metabolizing isozymes is non-selective.

Cooperative role of tumour necrosis factor‐α, interleukin‐1β and neutrophils in a novel behavioural model that concomitantly demonstrates articular inflammation and hypernociception in mice

BACKGROUND AND PURPOSE; Chronic joint inflammation and pain are the hallmarks of disease in patients with inflammatory arthritis, notably rheumatoid arthritis. The aim of the present study was to investigate the relative contribution of tumour necrosis factor (TNF)-α, interleukin (IL)-1β and neutrophil influx for joint inflammation and nociception in a novel murine model of antigen-induced arthritis (AIA). AIA was induced by administration of antigen into knee joint of previously immunized mice. Neutrophil accumulation was determined by counting neutrophils in the joints and assessing myeloperoxidase activity in tissues surrounding the joints. TNF-α, IL-1β and CXCL-1 were measured by elisa. Mechanical hypernociception was assessed in parallel, using an electronic pressure meter. Hypernociception was dependent on antigen dose and the time after its administration; it was prevented by treatment with morphine and associated with neutrophil infiltration and local production of TNF-α, IL-1β and CXCL-1. Administration of a chimeric monoclonal antibody to TNF-α (infliximab) or IL-1receptor antagonist prevented neutrophil influx and hypernociception, and this was comparable to the effects of dexamethasone. Treatment with fucoidin (a leucocyte adhesion inhibitor) greatly suppressed neutrophil influx and local production of TNF-α and IL-1β, and hypernociception. In conclusion, the present study describes a new model that allows for the concomitant evaluation of articular hypernociception and inflammation. Using this system, we demonstrated that a positive feedback loop involving neutrophil influx and the pro-inflammatory cytokines TNF-α and IL-1β is necessary for articular hypernociception after antigen challenge of immunized mice.

TNF-α −308G > A and IL-6 −174G > C polymorphisms in Tunisian patients with coronary artery disease

Objective Our aim was to evaluate the contribution of tumor necrosis factor (TNF)-α −308G > A and interleukin (IL)-6 −174G > C gene promoter variants to the presence of coronary artery disease (CAD) in Tunisians. Design and methods Study subjects comprised 418 angiographically proven CAD patients and 406 age-, gender-, and ethnic origin-matched controls. Genotyping was performed using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis. Results There were no significant differences in the allelic distribution of TNF-α −308A (19.6% vs. 19.0%, P = 0.73), and IL-6 −174C (15.6% vs. 14.3%, P = 0.47) promoter polymorphisms between CAD patients and control subjects, respectively. In addition, single locus analysis revealed no differences in genotype frequencies between the two study groups, and the combined distribution of both genotypes did not differ significantly between controls and CAD patients ( P > 0.05). Conclusion There is no allelic or genotypic association of TNF-α −308G > A and IL-6 −174G > C promoter polymorphisms with CAD in Tunisians, thereby confirming an ethnic-selective contribution of both gene variants to CAD presence.

Evidence for the contribution of tumour necrosis factor in oedema formation induced by histamine in the hind paw of the rat

There is mounting evidence that tumour necrosis factor (TNF) is involved in the early phase of inflammatory response, but its relation to histamine action is unclear. In this study we examined the effect of drugs interfering with TNF expression (thalidomide) and activity (infliximab) and compared it to that of a H(1)R histamine receptor antagonist (loratadine) in a model of histamine-induced rat hind-paw oedema formation. Systemic administration of all three drugs effectively reduced the oedema formed by the subsequent transplantar administration of histamine into the rat paw, in a dose-dependent manner. The time-dependence of the effect exerted by thalidomide and infliximab was very similar to that of loratadine. Moreover, there appears no significant synergistic effect between infliximab and loratadine, suggesting that TNF is either a major modulator or a direct mediator of oedema formation induced by histamine, in the rat paw.

Effects of Etanercept and Minocycline in a rat model of spinal cord injury

Loss of function is usually considered the major consequence of spinal cord injury (SCI). However, pain severely compromises the quality of life in nearly 70% of SCI patients. The principal aim of this study was to assess the contribution of Tumor necrosis factor α (TNF-α) to SCI pain. TNF-α blockers have already been successfully used to treat inflammatory disorders but there are few studies on its effect on neuropathic pain, especially following SCI. Following T13 spinal cord hemisection, we examined the effects on mechanical allodynia and microglial activation of immediate and delayed chronic intrathecal treatment with etanercept, a fusion protein blocker of TNF-α. Immediate treatment (starting at the time of injury) with etanercept resulted in markedly reduced mechanical allodynia 1, 2, 3 and 4 weeks after SCI. Delayed treatment had no effect. Immediate etanercept treatment also reduced spinal microglial activation assessed by OX-42 immunostaining, a putative marker of activated microglia. To assess whether the effects of etanercept were mediated via decreased microglial activation, we examined the effects of the microglial inhibitor, minocycline which significantly reduced the development of pain behaviours at 1 and 2 weeks after SCI compared to saline treatment. Minocycline also significantly reduced microglial OX-42 expression. Furthermore, minocycline decreased the expression of noxious-stimulation-induced c-Fos, suggesting an effect on evoked neuronal activity. This study demonstrates that TNF-α plays an important role in the establishment of neuropathic pain following SCI, seemingly dependent on microglial activation. Pharmacological targeting of TNF-α may offer therapeutic opportunities for treating SCI pain.

Extended haplotype analysis reveals an association of TNF polymorphisms with susceptibility to systemic lupus erythematosus beyond HLA‐DR3

Objective: To study the relative contribution of tumour necrosis factor (TNF) and HLA‐DRB1 polymorphisms to the genetic susceptibility to systemic lupus erythematosus (SLE) via an extended haplotype analysis.Methods: We performed an association study in 205 unrelated German Caucasian patients with SLE fulfilling the 1997 revised American College of Rheumatology (ACR) criteria. Healthy age‐, ethnically‐ and sex‐matched individuals (n = 157) served as controls. HLA‐DRB1 typing was performed by a sequence‐specific oligonucleotide hybridisation assay. Two TNF single nucleotide polymorphisms (SNPs) and two multiallelic microsatellites were analysed by mutagenically separated polymerase chain reaction (PCR) or fragment length analysis, respectively. Extended haplotypes were reconstructed with the PHASE software.Results: Alleles for all polymorphic loci studied and the most frequent haplotypes showed a significantly different distribution between SLE patients and controls. The alleles HLA‐DR2, DR3, TNFd1, TNF2, TNFB*1, and TNFa2, designated as risk alleles, and the extended haplotypes DR3‐TNFd1‐TNF2‐TNFB*1‐TNFa2 and DR2‐TNFd3‐TNF1‐TNFB*2‐TNFa11 prevailed in SLE patients. TNF risk alleles were strongly positively linked with HLA‐DR3 and negatively linked with HLA‐DR2. Thus, in HLA‐DR3 haplotypes individual effects of TNF polymorphisms could not be resolved. By contrast, HLA‐DR2 showed an association with SLE independently of TNF risk alleles, while the risk increased further when they were present. In haplotypes lacking HLA‐DR2 and DR3, the alleles TNFd1 and TNF2 contributed independently to SLE susceptibility.Conclusion: Extended haplotype analysis revealed HLA‐DR3 independent associations of TNF polymorphisms with susceptibility to SLE. Haplotypes that have been shown to be associated with different TNF‐α production capacity may prevail in different disease subgroups.

The differential contribution of tumour necrosis factor to thermal and mechanical hyperalgesia during chronic inflammation

Therapies directed against tumour necrosis factor (TNF) are effective for the treatment of rheumatoid arthritis and reduce pain scores in this condition. In this study, we sought to explore mechanisms by which TNF contributes to inflammatory pain in an experimental model of arthritis. The effects of an anti-TNF agent, etanercept, on behavioural pain responses arising from rat monoarthritis induced by complete Freund's adjuvant were assessed and compared with expression of TNF receptors (TNFRs) by dorsal root ganglion (DRG) cells at corresponding time points. Etanercept had no effect on evoked pain responses in normal animals but exerted a differential effect on the thermal and mechanical hyperalgesia associated with rat arthritis induced by complete Freund's adjuvant (CFA). Joint inflammation was associated with increased TNFR1 and TNFR2 expression on DRG cells, which was maintained throughout the time course of the model. TNFR1 expression was increased in neuronal cells of the DRG bilaterally after arthritis induction. In contrast, TNFR2 expression occurred exclusively on non-neuronal cells of the macrophage–monocyte lineage, with cell numbers increasing in a TNF-dependent fashion during CFA-induced arthritis. A strong correlation was observed between numbers of macrophages and the development of mechanical hyperalgesia in CFA-induced arthritis. These results highlight the potential for TNF to play a vital role in inflammatory hyperalgesia, both by a direct action on neurons via TNFR1 and by facilitating the accumulation of macrophages in the DRG via a TNFR2-mediated pathway.

Genetic contribution of tumor necrosis factor (TNF)-alpha gene promoter (-1031, -863 and -857) and TNF receptor 2 gene polymorphisms in endometriosis susceptibility.

Tumor necrosis factor (TNF)-alpha is a major cytokine involved in inflammatory and immune function. The aim of this study was to investigate whether polymorphisms at positions -1031, -863 and -857 in the TNF gene promoter region (TNFA) and TNF receptor type 2 gene (TNFR2) are responsible in part for genetic susceptibility to endometriosis. TNFA and TNFR2 polymorphisms were determined in 123 patients with endometriosis and 165 fertile healthy women by the polymerase chain reaction (PCR) - preferential homoduplex formation assay and PCR-restriction fragment length polymorphism, respectively. The frequency of the TNFA-U01 haplotype was increased significantly in patients with endometriosis compared with controls (P = 0.045, OR = 1.45). The TNFA-U01 haplotype was strongly associated with HLA-B*0702. No difference was found in TNFR2 polymorphism between patients and controls. Our results indicated that TNFA promoter polymorphism was associated with susceptibility to endometriosis. However, this association was not independent of HLA-class I polymorphisms.

Both the Fas ligand and inducible nitric oxide synthase are needed for control of parasite replication within lesions in mice infected with Leishmania major whereas the contribution of tumor necrosis factor is minimal.

Following infection with the protozoan parasite Leishmania major, C57BL/6 mice develop a small lesion that heals spontaneously. Resistance to infection is associated with the development of CD4(+) Th1 cells producing gamma interferon (IFN-gamma) and tumor necrosis factor (TNF), which synergize in activating macrophages to their microbicidal state. We show here that C57BL/6 mice lacking both TNF and Fas ligand (FasL) (gld TNF(-/-) mice) infected with L. major neither resolved their lesions nor controlled Leishmania replication despite the development of a strong Th1 response. Comparable inducible nitric oxide synthase (iNOS) activities were detected in lesions of TNF(-/-), gld TNF(-/-), and gld mice, but only gld and gld TNF(-/-) mice failed to control parasite replication. Parasite numbers were high in gld mice and even more elevated in gld TNF(-/-) mice, suggesting that, in addition to iNOS, the Fas/FasL pathway is required for successful control of parasite replication and that TNF contributes only a small part to this process. Furthermore, FasL was shown to synergize with IFN-gamma for the induction of leishmanicidal activity within macrophages infected with L. major in vitro. Interestingly, TNF(-/-) mice maintained large lesion size throughout infection, despite being able to largely control parasite numbers. Thus, IFN-gamma, FasL, and iNOS appear to be essential for the complete control of parasite replication, while the contribution of TNF is more important in controlling inflammation at the site of parasite inoculation.

Polymorphisms of the tumor necrosis factor receptors: no association with narcolepsy in German patients.

Narcolepsy is a debilitating sleep disorder characterized by daytime sleepiness and cataplexy. The strong association of narcolepsy with the HLA system suggests an autoimmune cause. Tumor necrosis factor is a cytokine involved in both regulation of immune mechanisms and sleep. Several studies were undertaken to determine a contribution of tumor necrosis factor and its receptors to the pathogenesis of narcolepsy. A significant increase in the 196R allele, a functionally relevant polymorphism in the TNFR2 gene, has been found in Japanese patients, indicating altered transduction of tumor necrosis factor signals. Here we explore polymorphisms in both tumor necrosis factor receptor genes as risk factors in a German population sample. Neither the polymorphism in the TNFR1 nor that in the TNFR2 gene was associated with narcolepsy. Our findings contrast to those previously published and thus provide evidence for genetic heterogeneity between different narcolepsy populations.

Contribution of tumor necrosis factor α and interleukin‐1 α on the production of macrophage inflammatory protein‐2 in response to respiratory syncytial virus infection in a murine macrophage cell line, RAW264.7

Contribution of tumor necrosis factor α and interleukin‐1 α on the production of macrophage inflammatory protein‐2 in response to respiratory syncytial virus infection in a murine macrophage cell line, RAW264.7

Contribution of tumor necrosis factor α and interleukin-1 α on the production of macrophage inflammatory protein-2 in response to respiratory syncytial virus infection in a murine macrophage cell line, RAW264.7

The production of several inflammatory cytokines, such as murine macrophage inflammatory protein-2 (MIP-2), tumor necrosis factor (TNF), and interleukin (IL)-1, was investigated in response to respiratory syncytial virus (RSV) infection in a murine macrophage cell line, RAW264.7, with special reference to mutual relation of their productions. The kinetics of MIP-2 production showed a trend for a biphasic pattern, that is, MIP-2 levels became detectable from 2 h postinfection (p.i.) and increased markedly until 8 h p.i. Thereafter, this level fell to the same level until 16 h p.i. and then increased again. TNF alpha was also detectable at 2 h p.i. and then increased sharply until 8 h p.i., when the peak level attained. Compared with the levels of MIP-2 and TNF alpha, that of IL-1 alpha/beta, especially IL-1 beta, was lower (ng versus pg/ml order). The presence of anti-TNF alpha or anti-IL-1 alpha antibody did not influence the early phase of MIP-2 production but significantly inhibited the late phase, suggesting that MIP-2 is induced by the combined effects of RSV infection via direct induction and indirectly after initial induction of TNF alpha and IL-1 alpha productions. Although RSV-infected RAW264.7 cells had no alteration in viability compared with mock-infected control, these data demonstrate that RSV is a potent inducer of inflammatory cytokines by direct induction and indirectly via the initial production of other cytokines.