Tumour necrosis factor-alpha gene polymorphism: implications in kidney transplantation

In this study we have analysed the TNFA biallelic polymorphism at the -308 position, in 169 kidney recipients that received the graft in a single Italian transplantation facility and we have then correlated the TNFA genotypes with the post-transplant outcome. To assess the cytokine genotypes, a polymerase chain reaction-sequence specific primer (PCR-SSP) methodology has been utilised. By the analysis of the different genotypes, the corresponding TNF-alpha phenotypes and the level of the TNF-alpha production, were deduced: the TNF(*)1/TNF(*)1 genotype gives a low TNF-alpha production level, TNF(*)1/TNF(*) 2 and TNF(*)2/TNF(*)2 genotypes give a high TNF-alpha production level. Out of the one hundred and sixty-nine patients studied, one hundred and twenty-one recipients (72%) had a low TNF-alpha producer phenotype, whereas forty-eight (28%) had a high TNF-alpha producer phenotype. These frequencies were not statistically different from those of the control group. The incidence of acute rejection episodes, vascular damage (grade III degrees of Banff classification), and serum creatinine levels at 1 month, were significantly greater in high TNF-alpha producers (P=0. 048, 0.031 and 0.007 respectively). The logistical regression model indicated that only the high producer genotype and donor age were significantly and independently correlated with acute graft failure (P=0.02 and P=0.013 respectively). This analysis shows that recipient TNFA polymorphism, previously associated with differential production TNF-alpha by in vitro studies could be related to the clinical outcome of kidney transplantation.     

Tumour necrosis factor-alpha uncouples respiration in isolated rat mitochondria

Recent studies have demonstrated the existence of an intracellular (associated with mitochondria) tumour necrosis factor-alpha (TNF) binding protein. In an attempt to elucidate if this receptor could be involved in TNF action, we have incubated liver isolated mitochondria in the presence of recombinant murine TNF. The results show that the addition of TNF at concentrations as low as 10(-6) U/microl resulted in a clear uncoupling respiration of liver isolated mitochondria, therefore suggesting that TNF can indeed exert intracellular effects, which are possibly linked with its cytotoxic mechanism.     

Tumour necrosis factor-alpha interacts with biglycan and decorin

The interaction of beta-arrestin-1 with the somatostatin receptor type 2A (sst2A) was monitored using both biochemical and confocal imaging approaches. We show that, using transient transfection of either beta-arrestin-1 or its dominant negative Delta-arrestin-1 in CHO cells stably transfected with the sst2A, beta-arrestin-1 is colocalized with the receptor in endosomal vesicles after somatostatin-induced sequestration. However, this interaction leads to a role of beta-arrestin-1 in the desensitization of the sst2A rather than in the internalization process of the receptor-ligand complex.     

Tumour necrosis factor-alpha: the role of this multifunctional cytokine in asthma

Tumour necrosis factor-alpha (TNF-alpha) is recognized as an important mediator in many cytokine- dependent inflammatory events. It is known that TNF-alpha is released in allergic responses from both mast cells and macrophages via IgE-dependent mechanisms, and elevated levels have been demonstrated in the bronchoalveolar fluid (BALF) of asthmatic subjects undergoing allergen challenge. Inhaled TNF-alpha increases airway responsiveness to methacholine in normal and asthmatic subjects associated with a sputum neutrophilia. Additional data indicate that TNF-alpha can upregulate adhesion molecules, facilitate the immigration of inflammatory cells into the airway wall and activate pro-fibrotic mechanisms in the subepithelium. These data suggest that TNF-alpha plays a role in the initiation of allergic asthmatic airway inflammation and the generation of airway hyper-reactivity. In addition, polymorphisms of the TNF-alpha gene 5' untranslated region, particularly at -308 bp, have been described as being associated with asthma. This polymorphism is associated with increased levels of TNF-alpha, but as yet, no asthma studies have demonstrated a phenotypic difference between those individuals with the polymorphism and those with the wild type gene. The TNF receptors (TNF-R p55 and p75), also known as CD120a and b, have also been shown to be present in the lung, but their functional importance is only just emerging. In asthma, TNF may function as a pro-inflammatory cytokine that causes the recruitment of neutrophils and eosinophils. Treatment directed specifically at a reduction in TNF-alpha activity may conceivably be useful as a glucocorticosteroid-sparing asthma therapy.     

Tumour necrosis factor-alpha and adenosine in endotoxin shockleading related cardiovascular symptoms

We have observed uncontrollable cardiogenic shock as a cardiovascular manifestation of systemic inflammatory response syndrome (SIRS) leading to death in a 62-year-old woman. The diagnosis of SIRS was based on the demonstration of endotoxinaemia, and highly elevated plasma levels of tumour necrosis factor (TNF)-alpha, and interleukin (IL)-10. We suggest that these cytokines may contribute to the terminal SIRS-related arrythmias, impaired myocardial contractility, as well as increased vascular permeability. In addition, the increased production of adenosine, a counter-regulatory mediator of inflammation, may also play a role in cardiodepression. We suggest a relationship between the action of TNF-alpha , IL-10 and adenosine in the pathogenesis of circulatory symptoms described above.     

Tumor necrosis factor-alpha gene promoter polymorphism in coal workers' pneumoconiosis

Tumor necrosis factor-alpha (TNF-alpha) is believed to play a central role in the pathogenesis of pneumoconiosis. TNF2, a polymorphism in the TNF-a gene promoter, has been associated with an increase in TNF-alpha production and airway inflammation. To investigate the frequency of TNF2 in patients who have coal workers' pneumoconiosis (CWP) and to determine whether it is associated with development of a large opacity in CWP, we investigated the expression ofthe TNF2 allele in 80 patients who had CWP and in 54 healthy controls using restriction fragment length polymorphism (RFLP). Compared to controls (10.2%), the frequency of the TNF2 allele was greater in the CWP patients (20.6%). Furthermore, the TNF2 allele was very common in patients who had a large opacity (28.2%) in comparison with 13.4% in those with simpleCWP. From these data, we suggest that the TNF2 allele is associated with the development of a large opacity in CWP.     

Tumour necrosis factor-alpha and interleukin-8 inhibit neutrophil migration in vitro and in vivo

Pretreatment of human neutrophils with recombinant tumour necrosis factor-alpha (rTNF-alpha) and/or interleukin-8 (rIL-8), but not with either transforming growth factor-beta, interleukin-6 or interferon-gamma, rendered these cells less responsive to FMLP, in microchemotaxis assays. This inhibitory effect was dose dependent and more powerful when neutrophils were pretreated with a mixture of both cytokines. Intravenous injection of human rIL-8 (hrIL-8) and/or murine rTNF-alpha (mrTNF-alpha) also significantly reduced in vivo neutrophil migration into peritoneal cavities of rats stimulated with carrageenan. These data suggest that the defect in neutrophil migration during septicaemia or endotoxaemia may be the result of the continuous release of IL-8 and TNF-alpha into the circulation. Thus, either the selective control or blockade of releasing of these cytokines as well as of its effects on neutrophils may be clinically useful in reestablishing the cell defence mechanisms.     

Tumour necrosis factor-alpha mediates blood-brain barrier damage in HIV-1 infection of the central nervous system

The pathogenesis of brain inflammation and damage by human immunodeficiency virus (HIV) infection is unclear. Because blood-brain barrier damage and impaired cerebral perfusion are common features of HIV-1 infection, we evaluated the role of tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in mediating disruption of the blood-brain barrier. Levels of TNF-alpha were more elevated in cerebrospinal fluid (CSF) than in serum of HIV-1 infected patients and were mainly detected in those patients who had neurologic involvement. Intrathecal TNF-alpha levels correlated with signs of blood-brain barrier damage, manifested by high CSF to serum albumin quotient, and with the degree of barrier impairment. In contrast, intrathecal IL-1beta levels did not correlate with blood-brain barrier damage in HIV-1 infected patients. TNF-alpha seems to be related to active neural inflammation and to blood-brain barrier damage. The proinflammatory effects of TNF-alpha in the nervous system are dissociated from those of IL-1beta.     

Tumour necrosis factor-alpha (TNFalpha) stimulates the growth of human bone marrow stromal cells

This study reports that TNF-alpha is a potent mitogen for human bone marrow sternal cells in vitro (assessed by [(3)H]-thymidine incorporation into DNA and cell counts). In contrast, cytokines such as IL-1alpha, IL-1beta, IL-2, IL-3, IL-4, IL-6, LIF, SCF, M-CSF, G-CSF and GM-CSF had no effect. The effect of TNF-alpha on the growth of human bone marrow stromal cells could be of importance during inflammatory processes which take place in the marrow, for example marrow fibrosis.     

Tumour necrosis factor-alpha receptor 1 polymorphisms and serum soluble TNFR1 in early spontaneous miscarriage

OBJECTIVES: The study investigated the association of TNFR1 gene polymorphism with early recurrent spontaneous miscarriage (ERSM) in Chinese women, and soluble TNFR1 (sTNFR1) expression in ERSM women. STUDY DESIGN: Two single nucleotide polymorphisms (SNPs) located at -383 (AGA to AGC) in the promoter region and +36 (CCA to CCG) in exon 1 of TNFR1 were investigated in 188 non-pregnant ERSM Chinese women. The serum sTNFR1 was measured by the ELISA method. RESULTS: Both SNPs were not associated with ERSM. The non-pregnant ERSM women had significantly higher levels of serum sTNFR1, compared with the non-pregnant, normal women (1.84+/-0.54 ng/ml versus 1.62+/-0.38 ng/ml; t=-2.053; p<0.05). CONCLUSIONS: The data do not provide evidence that TNFR1 gene polymorphism is etiologically important for ERSM in Chinese women. But, a significantly raised sTNFR1 level in non-pregnant ERSM women was recorded compared to women with normal pregnancies. The result suggests that pregnancy failure is associated with an increase of sTNFR1.     

Tumour necrosis factor-alpha and lipopolysaccharide enhance interferon-induced tryptophan degradation and pteridine synthesis in human cells

The capacity of recombinant interferon-alpha, -beta and -gamma, of bacterial lipopolysaccharide and of recombinant tumour necrosis factor-alpha to induce indoleamine 2,3-dioxygenase and synthesis of pteridines was studied in human peripheral blood mononuclear cells, human macrophages and normal dermal fibroblasts. The action of interferon-alpha and -beta on macrophages was supported by lymphocyte factors as indicated by the effect of these mediators in the absence or presence of lymphocytes. Tumour necrosis factor-alpha alone was ineffective in peripheral blood mononuclear cells and macrophages, but it significantly increased the action of all three interferon species on macrophages and fibroblasts. Lipopolysaccharide directly affected macrophages or dermal fibroblasts and enhanced the effect of interferon-gamma. However, in the presence of lymphocytes, the action of lipopolysaccharide was mediated via interferon-gamma.     

Tumour necrosis factor-alpha,interleukin-2 soluble receptor and different inflammatory parameters in patients with rheumatoid arthritis

BACKGROUND AND AIMS: Although the participation of cytokines in the pathogenesis of rheumatoid arthritis (RA) seems to be unequivocal, their relationship with current serum markers of this disease is not clear. The present study analyses whether there is any correlation between the levels of tumour necrosis factor-alpha (TNF-alpha), interleukin-2 soluble receptor (sIL-2R) and the concentrations of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and beta(2)-microglobulin in a group of 21 patients with RA, all rheumatoid factor positive. METHODS: The levels of TNF-alpha and sIL-2R were analysed in association with other parameters of inflammation (ESR, CRP and beta(2)-microglobulin). RESULTS: In comparison with the control group, RA patients presented high median levels of both cytokines, TNF-alpha (6.4 pg/ml) and sIL-2R (56 pmol/L), as well as of ESR (34 mm/h), CRP (0.9 mg/dl) and beta(2)-microglobulin (1.6 mg/dl) (p < 0.01). However, only ESR levels in the RA group significantly differ from the control group (p < 0.01). No correlation was found between the inflammatory parameters. CONCLUSIONS: These results suggested that TNF-alpha and slL-2R levels are up-regulated in RA patients but did not significantly differ from the control group. Due to the chronic course of this disease, other inflammatory markers must be identified in order to provide early therapeutic strategies to these patients.     

Tumour necrosis factor-alpha and heat-shock protein 70-2 gene polymorphisms in a family with rheumatoid arthritis

OBJECTIVES: The aim of this work was to investigate the prevalence of TNF-alpha-308 polymorphism among the 29 members of a family with RA and the association between the MHC-linked biallelic HSP70-2 gene and the TNF-alpha polymorphism. Five of the members with RA were diagnosed by using the revised 1987 ACR criteria, and 1 member suffered from SLE. METHODS: The variations in the TNF-alpha and the HSP70-2 genotypes were analyzed by PCR-RFLP, using NcoI and PstI restriction enzymes. RESULTS: Two of the 29 members were homozygotes for allele A, 18 were heterozygotes (TNF A/G) and 9 of them were homozygotes for allele G. Nineteen of the 29 were heterozygotes for HSP70-2 (A/G), 10 of them were homozygotes for the G allele, and none were homozygotes for allele A. Four of the 5 the RA patients carried the A allele for TNF-alpha all 5 were heterozygotes for HSP70-2 genotypes. CONCLUSION: The carriage of the A allele for TNF-alpha of -308 SNP in 4 of the 5 RA patients, and the high prevalence (68.0%) of TNF A allele carriers in this family confirms the important role of this candidate gene in the pathomechanism of RA, and might be of prognostic value for future clinical observations. Further, to test for association a much larger set of genetically independent patients and controls is needed.     

Tumor necrosis factor-alpha mediates one component of competitive, experience-dependent plasticity in developing visual cortex

Rapid, experience-dependent plasticity in developing visual cortex is thought to be competitive. After monocular visual deprivation, the reduction in response of binocular neurons to one eye is matched by a corresponding increase to the other. Chronic optical imaging in mice deficient in TNFalpha reveals the normal initial loss of deprived-eye responses, but the subsequent increase in response to the open eye is absent. This mutation also blocks homeostatic synaptic scaling of mEPSCs in visual cortex in vitro, without affecting LTP. In monocular cortex, thought not to be subject to competition, responses in TNFalpha mutants are as reduced as in the binocular zone. Pharmacological inhibition of endogenous TNFalpha in wild-type mice phenocopies the knockout. These findings suggest that experience-dependent competition in developing visual cortex is the outcome of two distinct, noncompetitive processes, a loss of deprived-eye responses followed by an apparently homeostatic increase in responses dependent on TNFalpha signaling.     

Activation of hepatic branched-chain alpha-keto acid dehydrogenase complex by tumor necrosis factor-alpha in rats

Tumor necrosis factor-alpha (TNFalpha) promotes oxidation of branched-chain amino acids (BCAA). BCAA catabolism is regulated by branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, which is regulated by phosphorylation-dephosphorylation of the E1alpha subunit at Ser293. BCKDH kinase is responsible for inactivation of the complex by phosphorylation. In the present study, we examined the effects of TNFalpha administration on hepatic BCKDH complex and kinase in rats. Rats were intravenously administered with 25 or 50 microg TNFalpha/kg body weight 4 h prior to sacrifice. The TNFalpha treatment at both doses elevated the activity state (percentage of the active form) of BCKDH complex from 22% to 69% and 86%, respectively, and the amount of phospho-Ser293 on the E1alpha subunit in each group of rats corresponded inversely to the activity state of BCKDH complex. The TNFalpha treatment of rats significantly decreased the activity as well as the bound form of BCKDH kinase. These results suggest that the decrease in the bound form of kinase is involved in the mechanism responsible for TNFalpha-induced activation of the BCKDH complex.