TNF, apoptosis and autoimmunity: a common thread?

Utilizing the ABC Transporter for Growth Factor Production by fleQ Deletion Mutant of Pseudomonas fluorescens

Pseudomonas fluorescens, a gram-negative bacterium, has been proven to be a capable protein manufacturing factory (PMF). Utilizing its ATP-binding cassette (ABC) transporter, a type I secretion system, P. fluorescens has successfully produced recombinant proteins. However, besides the target proteins, P. fluorescens also secretes unnecessary background proteins that complicate protein purification and other downstream processes. One of the background proteins produced in large amounts is FliC, a flagellin protein. In this study, the master regulator of flagella gene expression, fleQ, was deleted from P. fluorescens Δtp, a lipase and protease double-deletion mutant, via targeted gene knockout. FleQ directs flagella synthesis, so the new strain, P. fluorescens ΔfleQ, does not produce flagella-related proteins. This not only simplifies purification but also makes P. fluorescens ΔfleQ an eco-friendly expression host because it will not survive outside a controlled environment. Six recombinant growth factors, namely, insulin-like growth factors I and II, beta-nerve growth factor, fibroblast growth factor 1, transforming growth factor beta, and tumor necrosis factor beta, prepared using our supercharging method, were successfully secreted by P. fluorescens ΔfleQ. Our findings demonstrate the potential of P. fluorescens ΔfleQ, combined with our supercharging process, as a PMF.

A New Method for Chromosomes Preparation by ATP-Competitive Inhibitor SP600125 via Enhancement of Endomitosis in Fish

Previous studies have suggested that 1,9-Pyrazoloanthrone, known as SP600125, can induce cell polyploidization. However, what is the phase of cell cycle arrest caused by SP600125 and the underlying regulation is still an interesting issue to be further addressed. Research in this article shows that SP600125 can block cell cycle progression at the prometaphase of mitosis and cause endomitosis. It is suggested that enhancement of the p53 signaling pathway and weakening of the spindle assembly checkpoint are associated with the SP600125-induced cell cycle arrest. Using preliminary SP600125 treatment, the samples of the cultured fish cells and the fish tissues display a great number of chromosome splitting phases. Summarily, SP600125 can provide a new protocol of chromosomes preparation for karyotype analysis owing to its interference with prometaphase of mitosis.

Effect of corticosteroid (triamcinolone acetonide) and chlorhexidin on chemotherapy- induced oxidative stress in buccal mucosa of rats

Oral mucositis (OM) refers to erythematous and ulcerative lesions of the oral mucosa. This pathology can occur by various causes. Cancer therapy is one of the well-known causes of OM such as chemotherapy and/or with radiation therapy. It has been widely mentioned that oxidative stress parameters such as lipid peroxidation (LP) levels increase during cancer process. Glutathione (GSH) is one of the major intracellular enzymes to detoxify oxidant molecules. The aim of this study was to investigate and compare the effects of Triamcinolone Acetonide (TA), a synthetic steroid chlorhexidine (CHX), a chemical antiseptic, on 5- fluorouracil (5-FU), a chemotherapeutic agent and soft abrasion induced OM in buccal mucosa of rats.OM was induced in rats through a combination of 5-FU treatment and mild abrasion of the cheek pouch with a wire brush. Buccal mucosa lipid peroxidation (LP) levels were higher (p< 0.05) in 5-FU group than in control although LP levels were lower (p<0.05) in TA group than in control group. The reduced glutathione levels were lower (p<0.05) in 5-FU group than in the control group although its level was higher (p<0.05) in TA and CHX groups than in the 5-FU group. Glutathione peroxidase activity was also higher (p<0.05) in TA group than the 5- FU group. In histopathological analyses, treatment with TA reduced 5-FU induced inflammatory cell infiltration and ulceration (p<0.001) but not with CHX.In conclusion, we observed that TA and CHX treatment modulated chemotherapy induced oxidative injury in the rat OM. However, only TA histopathologically ameliorated the 5-FU induced OM of rats. These findings suggest that TA is a useful agent for management of experimental oxidative injury and OM caused by the chemotherapy.

Association of TNF-a (rs361525 and rs1800629) with susceptibility to cervical intraepithelial lesion and cervical carcinoma in women from Republic of North Macedonia

Cervical cancer (CCa) is one of the most common malign diseases in women associated with human papillomavirus (HPV). The virus is an initiating factor, but not sufficient for the development of cervical intraepithelial lesions (CIN) and CCa. The disease might be a result of the influence of host's genetic factors and polymorphisms in inflammatory-related genes that modify the immune response to HPV and attribute to cancer susceptibility. We carried out a study to determine the association between TNF-a-238G/A and TNF-a-308 G/T polymorphisms with HPV-positive CIN and CCa in women living in the Republic of North Macedonia. Using multiplex SNaPshot analysis for single nucleotide polymorphisms (SNPs), we analysed the genotype and allele distributions of TNF-a-238G/A and TNF-a-308 G/T in 134 cases (HPV-positive and histologically confirmed CIN and CCa) and in 113 controls (cytological and HPV-negative women). For further analysis, the case group was stratified in three subgroups (all cases: CINs+ CCa- group; CIN2+ -group and CIN1- group). Data analysed using the odds ratio (OR) and chi-square test showed the frequency of AA genotypes and A alleles are not significantly higher in cases compared to the controls for both SNPs: AA of TNF-a-238 (0.7% versus 0%) and TNF-a-308 (1.5% versus 0.9%) as well as A allelic frequency (3.0% versus 1.7%) and (13.1% versus 10.6), respectively. The comparison of the case's subgroups with the control group did not show a statistically significant difference. Compared to controls, TNF-a-238G/A and TNF-a-308 G/T are not associated with the risk of HPV associated CIN or CCa in the studied women.

A case-control study of tumor necrosis factor-alpha promoter polymorphism and its serum levels in patients with chronic obstructive pulmonary disease in Kashmir, North India

Aim:

Data about polymorphism in tumor necrosis factor-alpha (TNF-α) and its serum levels in chronic obstructive pulmonary disease (COPD) are conflicting. We aimed to evaluate the association of TNF-α-308 G > A polymorphism in patients with COPD in Kashmir (North India), a high burden area and also determined the serum TNF-α levels in these patients.

Materials and Methods:

One hundred spirometrically confirmed COPD patients and 163 controls resident from Kashmir valley (North India) were recruited. Genotyping of the promoter region of TNF-α was carried out using polymerase chain reaction-restriction fragment length polymorphism. The serum TNF-α was quantified using the Cytometric Bead Array flex system by flow cytometry. Results were subjected to appropriate statistical treatment and P < 0.05 was considered statistically significant.

Results:

Ninety-one COPD patients (91%) had G/G (wild homozygous) genotype and nine patients (9%) had G/A (heterozygous) genotype. Among the control population, 150 (92%) had G/G genotype and 13 (8%) had G/A genotype. The variant allele “A” was not detected in either of the two groups. Serum levels of TNF-α were significantly higher in patients compared to control group (8.0 ± 10.1 pg/ml vs. 3.3 ± 0.42 pg/ml, respectively, P = 0.0001).

Conclusion:

While serum levels of TNF-α are higher in COPD patients compared to the controls, there was no difference in the prevalence of TNF-α-308 polymorphism in the ethnic Kashmiri population with COPD.

Effect of a corticosteroid (triamcinolone) and chlorhexidine on chemotherapy-induced oxidative stress in the buccal mucosa of rats

Oral mucositis manifests as erythematous and ulcerative lesions of the oral mucosa. Among its various causes, cancer treatment (e.g., chemotherapy with or without radiation therapy) is one of the more well known. It has been widely mentioned that oxidative stress parameters such as lipid peroxidation levels increase during the cancer process. Glutathione is one of the major intracellular enzymes used to detoxify oxidant molecules; it exists in both a reduced and oxidized state. Reduced glutathione is used as a substrate to synthesize glutathione peroxidase. We conducted a study to investigate and compare the effects of triamcinolone (a synthetic steroid) and chlorhexidine (a chemical antiseptic) on 5-fluorouracil (5-FU; a chemotherapeutic agent)-induced oral mucositis in the buccal mucosa of 36 rats. Oral mucositis was induced through a combination of 5-FU treatment and mild abrasion of the cheek pouch with a wire brush. The rats were treated with one of four regimens: saline placebo (group I), 5-FU only (group II), 5-FU plus triamcinolone (group III), and 5-FU plus chlorhexidine (group IV). Three rats in the triamcinolone group died of unknown causes on days 7 and 8, and 3 rats in the chlorhexidine group died on days 7 and 9. On day 9, the remaining 30 rats were sacrificed and examined. Buccal mucosa lipid peroxidation levels were significantly higher in the 5-FU-only group than in the control group and significantly higher in the control group than in the triamcinolone group (p < 0.05 for both). Levels of reduced glutathione were significantly lower in the 5-FU-only group than in both the triamcinolone group and the chlorhexidine group (p < 0.05). Glutathione peroxidase activity was significantly higher in the triamcinolone group than in the 5-FU-only group (p < 0.01). Histopathologic analysis revealed that treatment with triamcinolone significantly reduced 5-FU-induced inflammatory cell infiltration and ulceration (p < 0.001); no such reduction was seen with chlorhexidine. In conclusion, we observed that triamcinolone and chlorhexidine treatment modulated chemotherapy-induced oxidative injury in rat oral mucositis. However, only triamcinolone histopathologically ameliorated 5-FU-induced oral mucositis. These findings suggest that triamcinolone is a useful agent for the management of experimental oxidative injury and oral mucositis caused by 5-FU chemotherapy.

Tumor necrosis factor-α (TNF-α)-308G/A promoter polymorphism in colorectal cancer in ethnic Kashmiri population - A case control study in a detailed perspective

Background

Inflammation constitutes one of the important components of colorectal cancer (CRC) pathogenesis. Tumor necrosis factor-α (TNF-α), a cytokine and an important inflammatory mediator plays a pivotal role in the malignant cellular proliferation, angiogenesis, tissue invasion and metastasis in CRC. The studies on association of various polymorphisms in human TNF-α gene including TNF-α-308G/A single nucleotide polymorphism (SNP) are limited, mixed and inconclusive.

Materials and methods

The aim of this study was to analyze the association of TNF-α-308G/A promoter SNP with colorectal cancer (CRC) susceptibility and development risk and also to evaluate the modifying effects of possible TNF-α-308G/A genotypes on different risk factors of CRC in ethnic population of Kashmir, India through a case–control setup. The genotype frequencies of TNF-α-308G/A promoter SNP were compared between 142 CRC patients and 184 individually matched healthy controls by using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method. The associations between the TNF-α-308G/A SNP and CRC risk were examined through conditional logistic regression models adjusted for multiple possible confounding (third) variables. Further, the associations between this SNP and various clinico-pathological parameters, demographic variables and environmental factors within the case group subjects with regard to CRC risk were also evaluated.

Results

The association between the TNF-α-308G/A SNP and the modulation of risk of CRC was not found to be significant (p value = 0.156). The effect of less common TNF-α-308A allele on the risk of colorectal cancer was also not found to be significant (p value = 0.175). The variant genotype (AA) was nonexistent in the study population. Further, we found no significant effect modulation of CRC risk by wild and heterozygous TNF-α-308G/A SNP genotypes in presence of different possible risk factors (p > 0.05). We also found no significant association of TNF-α-308G/A SNP with the subsets of various characteristics of the case group subjects under study (p > 0.05).

Conclusions

This study indicates that there is no significant association between the TNF-α-308G/A promoter SNP and the risk of developing CRC in ethnic Kashmiri population. However, in order to substantiate our findings, this study needs to be replicated with bigger sample size and should involve other ethnically defined populations with high CRC risk.

Lack of Associations between TNF-αPolymorphisms and Cervical Cancer in Thai women

The risk of developing cervical cancer in women infected with human papillomavirus (HPV) may be influenced by an individual's genetic susceptibility. Published data linking single nucleotide polymorphisms (SNPs) in the tumor necrosis factor-alpha (TNF-?) promoter region at positions -308G>A (rs1800629) and -238G>A (rs361525) to cervical cancer risk have been inconclusive. In this study, we examined 251 cervical specimens and classified them into two groups according to their cytological findings: 121 cancer cases and 130 controls (low-grade squamous intraepithelial lesion and normal cytology). All specimens were typed by PCR and sequencing for TNF-αpromoter -308G>A (rs1800629) and -238G>A (rs361525). The genotype distribution of SNPs in either rs1800629 or rs361525 did not significantly demonstrate higher frequency in the cancer group (p=0.621 and p=0.68, respectively). Based on these results, neither the TNF-αpromoter -308G>A (rs1800629) nor the -238G>A (rs361525) polymorphism presents a major risk factor for cervical cancer among Thai women. Larger studies are necessary to elucidate possible genetic mechanisms influencing cervical cancer development.

TNF-α signalling and inflammation: interactions between old acquaintances

INTRODUCTION

Inflammation is a very important part of innate immunity and is regulated in many steps. One such regulating step is the cytokine network, where tumor necrosis factor α (TNF-α) plays one of the most important roles.

METHODS

A PubMed and Web of Science databases search was performed for studies providing evidences on the role of TNF-α in inflammation, apoptosis, and cancer.

RESULTS AND CONCLUSION

This review concisely summarizes the role of this pro-inflammatory cytokine during inflammation. It is focused mainly on TNF-α intracellular signaling and its influence on the typical inflammatory features in the organism. Being one of the most important pro-inflammatory cytokines, TNF-α participates in vasodilatation and edema formation, and leukocyte adhesion to epithelium through expression of adhesion molecules; it regulates blood coagulation, contributes to oxidative stress in sites of inflammation, and indirectly induces fever. The connection between TNF-α and cancer is mentioned as well.

The role of positive feedback loops involving anti-dsDNA and anti-anti-dsDNA antibodies in autoimmune glomerulonephritis

Autoimmune glomerulonephritis (GN) is a potentially life-threatening renal inflammation occurring in a significant percentage of systemic lupus erythematosus (SLE) patients. It has been suggested that GN develops and persists due to a positive feedback loop, in which inflammation is promoted by the deposition in the kidney of immune complexes (IC) containing double-stranded DNA (dsDNA) and autoantibodies specific to it, leading to cellular death, additional release to circulation of dsDNA, continuous activation of dsDNA-specific autoreactive B cells and further formation of IC. We have recently presented a generic model exploring the dynamics of IC-mediated autoimmune inflammatory diseases, applicable also to GN. Here we extend this model by incorporating into it a specific B cell response targeting anti-dsDNA antibodies-a phenomenon whose occurrence in SLE patients is well-supported empirically. We show that this model retains the main results found for the original model studied, particularly with regard to the sensitivity of the steady state properties to changes in parameter values, while capturing some disease-specific observations found in GN patients which are unaccountable using our previous model. In particular, the extended model explains the findings that this inflammation can be ameliorated by treatment without lowering the level of anti-dsDNA antibodies. Moreover, it can account for the inverse oscillations of anti-dsDNA and anti-anti-dsDNA antibodies, previously reported in lupus patients. Finally, it can be used to suggest a possible explanation to the so-called regulatory role of TLR9, found in murine models of lupus; i.e., the fact that the knockdown of this DNA-sensing receptor leads, as expected, to a decrease in the level of anti-dsDNA antibodies, but at the same time results in a counter-intuitive amplification of the autoreactive immune response and an exacerbated inflammation. Several predictions can be derived from the analysis of the presented model, allowing its experimental verification.

Tumor necrosis factor B (TNFB) genetic variants and its increased expression are associated with vitiligo susceptibility

Genetic polymorphisms in TNFB are involved in the regulation of its expression and are found to be associated with various autoimmune diseases. The aim of the present study was to determine whether TNFB +252A/G (rs909253) and exon 3 C/A (rs1041981) polymorphisms are associated with vitiligo susceptibility, and expression of TNFB and ICAM1 affects the disease onset and progression. We have earlier reported the role of TNFA in autoimmune pathogenesis of vitiligo, and we now show the involvement of TNFB in vitiligo pathogenesis. The two polymorphisms investigated in the TNFB were in strong linkage disequilibrium and significantly associated with vitiligo. TNFB and ICAM1 transcripts were significantly increased in patients compared to controls. Active vitiligo patients showed significant increase in TNFB transcripts compared to stable vitiligo. The genotype-phenotype analysis revealed that TNFB expression levels were higher in patients with GG and AA genotypes as compared to controls. Patients with the early age of onset and female patients showed higher TNFB and ICAM1 expression. Overall, our findings suggest that the increased TNFB transcript levels in vitiligo patients could result, at least in part, from variations at the genetic level which in turn leads to increased ICAM1 expression. For the first time, we show that TNFB +252A/G and exon 3 C/A polymorphisms are associated with vitiligo susceptibility and influence the TNFB and ICAM1 expression. Moreover, the study also emphasizes influence of TNFB and ICAM1 on the disease progression, onset and gender bias for developing vitiligo.

Anti-inflammatory effects of mapracorat, a novel selective glucocorticoid receptor agonist, is partially mediated by MAP kinase phosphatase-1 (MKP-1)

Mapracorat is a novel selective glucocorticoid receptor agonist (SEGRA), structurally distinct from corticosteroids. In preclinical studies, mapracorat potently inhibits the production of a variety of inflammatory mediators including cytokines and prostaglandin E2 (PGE(2)), with limited side effects associated with traditional corticosteroids. The objective of this study was to delineate the mechanisms underlying the anti-inflammatory properties of mapracorat. We found that mapracorat potently inhibited the production of GM-CSF and TNF-α in LPS-stimulated Raw 264.7 macrophages. Mapracorat also substantially attenuated the expression of COX-2 and the production of PGE(2). The inhibition of mapracorat on the inflammatory response was dose-dependent, and substantially inhibitory effects were observed at concentrations in the 10-100 nm range. Examination of the activation kinetics of p38 and its downstream target MAPK-activated protein kinase-2 (MK-2) revealed a shortened activation course after LPS stimulation in cells pretreated with mapracorat. Supporting the notion that mapracorat augments a feedback control mechanism restraining the p38 pathway, we found that mapracorat enhanced the expression of MAPK phosphatase-1 (MKP-1), a critical negative regulator of MAPKs that drive the production of cytokines and other inflammatory mediators. While mapracorat alone did not stimulate MKP-1 expression, it markedly enhanced the expression of MKP-1 in cells stimulated by LPS, in a similar manner and potency to the augmenting effect of dexamethasone. Blocking MKP-1 expression by triptolide also abolished the accelerating effects of mapracorat on p38 and MK-2 deactivation, further supporting a role of MKP-1 in the anti-inflammatory mechanism of mapracorat. Taken together, these results indicate that mapracorat exerts its anti-inflammatory effects, at least in part, by augmenting MKP-1 expression.

Antioxidant and immunity activities of Fufang Kushen Injection Liquid

We investigated the effects of Fufang Kushen Injection Liquid (FFKSIL) on gastric immunity and oxidant-antioxidant status during N-methyl-N′-nitro-N-nitroso-guanidine (MNNG)-induced gastric carcinogenesis. The extent of lipid peroxidation and the levels of reduced glutathione (GSH) and activities of the GSH-dependent enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were used to monitor the peroxidative balance. Enhanced lipid peroxidation in the gastric cancer animals was accompanied by significant decreases in the activities of GSH, GPx, GST and GR. Administration of FFKSIL significantly enhanced serum IgA, IgG, IgM, IL-2, IL-4 and IL-10 levels, decreased serum IL-6 and TNF-α levels, lowered the levels of lipid peroxides and enhanced GSH levels and activities of GSH-dependent enzymes. Our results suggest that FFKSIL blocks experimental gastric carcinogenesis by protecting against carcinogen-induced oxidative damage and improving immunity activity.

Tumour necrosis factor receptor trafficking dysfunction opens the TRAPS door to pro-inflammatory cytokine secretion

Cytokines are secreted from macrophages and other cells of the immune system in response to pathogens. Additionally, in autoinflammatory diseases cytokine secretion occurs in the absence of pathogenic stimuli. In the case of TRAPS [TNFR (tumour necrosis factor receptor)-associated periodic syndrome], inflammatory episodes result from mutations in the TNFRSF1A gene that encodes TNFR1. This work remains controversial, however, with at least three distinct separate mechanisms of receptor dysfunction having been proposed. Central to these hypotheses are the NF-κB (nuclear factor κB) and MAPK (mitogen-activated protein kinase) families of transcriptional activators that are able to up-regulate expression of a number of genes, including pro-inflammatory cytokines. The present review examines each proposed mechanism of TNFR1 dysfunction, and addresses how these processes might ultimately impact upon cytokine secretion and disease pathophysiology.

Circulating cell-derived microparticles in women with pregnancy loss

PROBLEM

To analyze cell-derived microparticles (cMP) in pregnancy loss (PL), both recurrent miscarriages (RM) and unexplained fetal loss (UFL).

METHOD OF STUDY

Non-matched case-control study was performed at Vall d'Hebron Hospital. Cell-derived microparticles of 53 PL cases, 30 with RM, 16 with UFL, and 7 (RM + UFL), were compared to 38 healthy pregnant women. Twenty healthy non-pregnant women act as controls. Cell-derived microparticles were analyzed through flow cytometry. Results are given as total annexin (A5+), endothelial-(CD144+/CD31+ CD41-), platelet-(CD41+), leukocyte-(CD45+) and CD41- c-MP/μL of plasma. Antiphospholipid antibodies (aPLA) were analyzed according to established methods.

RESULTS

Comparing PL versus healthy pregnant, we observed a significant endothelial cMP decrease in PL. When comparing RM subgroup with controls, we observed significant decreases in endothelial cMP. When comparing the PL positive for aPLA versus PL-aPLA-negative, no cMP numbering differences were seen.

CONCLUSION

Pregnancy loss seems to be related to endothelial cell activation and/or consumption. A relationship between aPLA and cMP could not be demonstrated.

Increased expression of tumor necrosis factor receptors in cryptogenic organizing pneumonia

BACKGROUND

TNF receptors (TNFR1 and TNFR2) and Fas belong to the system of apoptosis-signalling receptor molecules and may play a role in the pathogenesis of interstitial lung disease. Patients with cryptogenic organizing pneumonia (COP) usually respond well to corticosteroids, in contrast to those with idiopathic pulmonary fibrosis (IPF). This may be due to the different pathogenesis.

METHODS

The expression of TNFR1, TNFR2 and Fas on bronchoalveolar lavage (BAL) macrophages and lymphocytes was analysed in 9 patients with COP, 10 with IPF and 12 controls. The production of soluble TNFR1, 2 and TNF-α by alveolar macrophages was measured by ELISA.

RESULTS

TNFR1 and Fas expression on alveolar macrophages was significantly higher in COP than in controls and IPF. The expression of TNFR2 on alveolar macrophages was also increased in COP compared to controls. The expression of TNFR2 and Fas on lymphocytes was significantly higher in COP than in IPF and controls. In addition, the expression of TNFR1, TNFR2 and Fas on BAL cells correlated positively with BAL lymphocytes (p < 0.05 or p < 0.01). The production of sTNFR1 and 2 and TNF-α by macrophages in vitro was significantly increased in patients with COP compared to IPF and controls, spontaneously or with LPS stimulation (p < 0.05 or p < 0.01).There was a positive correlation between the spontaneous production of sTNFR2 and TNF-α (r = 0.494, p < 0.01).

CONCLUSIONS

This study showed an increased expression of TNF receptors and Fas on BAL cells in COP that may be indicative of the local inflammatory activity in the lung. The biologic effects of this expression needs further investigation.

Increased inflammation, impaired bacterial clearance, and metabolic disruption after gram-negative sepsis in Mkp-1-deficient mice

MAPKs are crucial for TNF-alpha and IL-6 production by innate immune cells in response to TLR ligands. MAPK phosphatase 1 (Mkp-1) deactivates p38 and JNK, abrogating the inflammatory response. We have previously demonstrated that Mkp-1(-/-) mice exhibit exacerbated inflammatory cytokine production and increased mortality in response to challenge with LPS and heat-killed Staphylococcus aureus. However, the function of Mkp-1 in host defense during live Gram-negative bacterial infection remains unclear. We challenged Mkp-1(+/+) and Mkp-1(-/-) mice with live Escherichia coli i.v. to examine the effects of Mkp-1 deficiency on animal survival, bacterial clearance, metabolic activity, and cytokine production. We found that Mkp-1 deficiency predisposed animals to accelerated mortality and was associated with more robust production of TNF-alpha, IL-6 and IL-10, greater bacterial burden, altered cyclooxygenase-2 and iNOS expression, and substantial changes in the mobilization of energy stores. Likewise, knockout of Mkp-1 also sensitized mice to sepsis caused by cecal ligation and puncture. IL-10 inhibition by neutralizing Ab or genetic deletion alleviated increased bacterial burden. Treatment with the bactericidal antibiotic gentamicin, given 3 h after Escherichia coli infection, protected Mkp-1(+/+) mice from septic shock but had no effect on Mkp-1(-/-) mice. Thus, during Gram-negative bacterial sepsis Mkp-1 not only plays a critical role in the regulation of cytokine production but also orchestrates the bactericidal activities of the innate immune system and controls the metabolic response to stress.

Suppressing IL-32 in monocytes impairs the induction of the proinflammatory cytokines TNFalpha and IL-1beta

Targeting major proinflammatory cytokines such as IL-1beta and TNFalpha is of great interest in patients with chronic inflammatory diseases, including rheumatoid arthritis, colitis, and psoriasis. The cytokine Interleukin (IL)-32 induces proinflammatory cytokines such as TNFalpha, IL-1beta, IL-6, and chemokines. We previously used an IL-32 ligand-affinity column to purify proteinase 3, which is abundantly expressed in neutrophil and monocytic leukocytes but not in other cell types, and found that IL-32 is mainly produced by monocytic leukocytes. This evidence suggested that silencing endogenous IL-32 by short hairpin RNA (shRNA) in monocytic cells might reveal the precise function of endogenous IL-32. Indeed, lipopolysaccharide (LPS)- or phorbol myristate acetate (PMA)-induced proinflammatory cytokine production was significantly inhibited in shRNA/IL-32 stable clones as compared to control clones. Furthermore, macrophages in PMA-differentiated shRNA/IL-32 stable clones displayed remarkably impaired LPS- and IL-1beta-induced proinflammatory cytokine production. These data suggest that IL-32 is not only involved in host defense against pathogens, but also might play a role in chronic inflammatory diseases. IL-32 production leads to major proinflammatory cytokine production during the initial immune response.

Leader sequence is required for activity of transmembrane tumor necrosis factor-alpha

Transmembrane tumor necrosis factor alpha (tmTNF-alpha) has a variety of biological activities different from soluble TNF-alpha (sTNF-alpha), but the only difference in sequence is its leader sequence (LS). To investigate the effect of the LS on tmTNF-alpha activity, single amino acid substitutions in the LS and its linked extracellular mature domain were made in an in vitro translation system and in an intact cell system. Mutations at Met(-71) and Cys(-28) in the LS obliterated cytotoxicity of tmTNF-alpha, whilst their secretory form retained full activity compared to parental sTNF-alpha. The lost cytotoxicity of Met(-71) mutant tmTNF-alpha was partly due to a reduced receptor binding activity. In spite of full receptor binding activity, Cys(-28) mutant tmTNF-alpha failed to induce NO production and iNOS mRNA transcription via forward signaling, but synergized with sTNF-alpha in IL-8 mRNA transcription via reverse signaling. The Asp(143) mutant tmTNF-alpha lost the ability to bind TNFR and to kill MCF-7 cells, whilst its secretory form retained about 60% cytotoxicity of parental sTNF-alpha. Although the mutation at Phe(87) had full activity in both forms, its membrane form induced a change in cell death mode from apoptosis to necrosis, in contrast to wild-type TNF-alpha whose membrane molecule chiefly induced apoptosis and secretory molecule mainly caused necrosis in MCF-7, respectively. The data suggest that the LS may be required for maintaining the correct structure and the bioactivity of tmTNF-alpha.

Circulating microparticles, lupus anticoagulant and recurrent miscarriages

Pregnancy is a pro-inflammatory/hypercoagulable state. Impairment of trophoblastic invasion and placental microthrombi are involved mechanisms in the pathogenesis of recurrent miscarriages (RM). Although in RM related to antiphospholipid antibodies (aPL) non-thrombotic mechanism seems to play an important role as well, we focused this review on the thrombotic mechanisms of RM related to aPL. Thus, in cases of RM related to aPL, placental injury produces inflammatory changes in endothelial cells. Endothelial dysfunction has been shown by increased plasma levels of ICAM-1/VCAM-1 and E-selectin. In RM associated with aPL, the thrombogenic mechanisms included different pathways: protein C inhibition, annexin-5 displacement, blocking of beta(2)GP1 anticoagulant activity and tissue factor upregulation. A new marker/causative agent of RM by itself or in relation to lupus anticoagulant (LA) has risen: circulating microparticles. Microparticles are a heterogeneous group of small, membrane-coated vesicles with a diameter of 0.1-1 microm. Microparticles are released from the cellular membrane during cell activation/apoptosis. Exposition of phospholipids in the outer membrane leaflet could explain the role of microparticles in the thrombotic events. Microparticles have been associated with RM. Microparticles are increased in women with RM when compared with healthy pregnant women. A relationship between aPL and activated endothelial cells (EC) occurs, as well as between EC and circulating microparticles. Interestingly, microparticles induced coagulation in vitro via tissue factor, especially in plasmas with LA. Finally, the relationship between EC, microparticles, LA and RM is revised.

Identification of the most active interleukin-32 isoform

Cytokines are crucial in host defence against pathogens such as bacteria, viruses, fungi and parasites. A newly described cytokine, interleukin-32 (IL-32), induces various proinflammatory cytokines (tumour necrosis factor-alpha, IL-1beta, IL-6) and chemokines in both human and mouse cells through the nuclear factor-kappaB and p38 mitogen-activated protein kinase inflammatory signal pathway. The IL-32 primarily acts on monocytic cells rather than T cells. In an attempt to isolate the IL-32 soluble receptor, we used an IL-32 ligand-affinity column to purify neutrophil proteinase 3, which is a serine proteinase involved in many inflammatory diseases. IL-32 has biological activity associated with Mycobacterium tuberculosis and chronic proinflammatory diseases such as rheumatoid arthritis. IL-32 is transcribed as six alternative splice variants and the biological activity of each individual isoform remains unknown. Here, we cloned the complementary DNA of the four IL-32 isoforms (alpha, beta, gamma and delta) that are the most representative IL-32 transcripts. To produce recombinant protein with a high yield, the amino acids of two cysteine residues were mutated to serine residues, because serine residues are not conserved among different species. The multi-step purified recombinant IL-32 isoform proteins were assessed for their biological activities with different cytokine assays. The gamma isoform of IL-32 was the most active, although all isoforms were biologically active. The present study will provide a specific target to neutralize endogenous IL-32, which may contribute to basic and clinical immunology.

Inhibition of tristetraprolin deadenylation by poly(A) binding protein

Tristetraprolin (TTP) is the prototype for a family of RNA binding proteins that bind the tumor necrosis factor (TNF) messenger RNA AU-rich element (ARE), causing deadenylation of the TNF poly(A) tail, RNA decay, and silencing of TNF protein production. Using mass spectrometry sequencing we identified poly(A) binding proteins-1 and -4 (PABP1 and PABP4) in high abundance and good protein coverage from TTP immunoprecipitates. PABP1 significantly enhanced TNF ARE binding by RNA EMSA and prevented TTP-initiated deadenylation in an in vitro macrophage assay of TNF poly(A) stability. Neomycin inhibited TTP-promoted deadenylation at concentrations shown to inhibit the deadenylases poly(A) ribonuclease and CCR4. Stably transfected RAW264.7 macrophages overexpressing PABP1 do not oversecrete TNF; instead they upregulate TTP protein without increasing TNF protein production. The PABP1 inhibition of deadenylation initiated by TTP does not require the poly(A) binding regions in RRM1 and RRM2, suggesting a more complicated interaction than simple masking of the poly(A) tail from a 3'-exonuclease. Like TTP, PABP1 is a substrate for p38 MAP kinase. Finally, PABP1 stabilizes cotransfected TTP in 293T cells and prevents the decrease in TTP levels seen with p38 MAP kinase inhibition. These findings suggest several levels of functional antagonism between TTP and PABP1 that have implications for regulation of unstable mRNAs like TNF.

Association of TNF-α polymorphism with susceptibility to and severity of non-small cell lung cancer

BACKGROUND

Genetic polymorphisms in the promoter region of the tumor necrosis factor-alpha (TNF-alpha) gene are involved in the regulation of expression levels and have been associated with various inflammatory and malignant conditions. We have investigated two polymorphisms in the promoter region of the TNF-alpha gene (-308 G/A and -238 G/A) for their role in the susceptibility to and severity of non-small cell lung cancer (NSCLC), by means of an allelic association study.

METHODS

Using a case-control study design, lung cancer patients (n = 202) and appropriate age- and sex-matched controls recruited from the health check-up unit (n = 205) were subjected to genotype analysis for these polymorphisms, using a high-throughput allelic discrimination method.

RESULTS

Genotype was analyzed using the polymerase chain reaction-restriction fragment length polymorphism technique with genomic DNA isolated from peripheral blood lymphocytes. Overall, the distribution of the genotype frequencies of TNF-alpha-308 A/G and -238 A/G were significantly different between the lung cancer patients and the healthy controls, and also different between patients with lung cancers of various stages (p < 0.0001). Logistic regression analysis revealed that higher odds ratios (ORs) for lung cancer were seen for individuals with TNF-alpha-308 AA/GA genotypes against GG genotype (an OR of 3.75, 95% CI 2.38-5.92, p < 0.0001), and lower ORs were seen for individuals with TNF-alpha-238 AA/GA genotypes against GG genotype (an OR of 0.26, 95% CI 0.13-0.50, p < 0.0001). The patients carrying a homologous AA or heterologous GA genotype at TNF-308 (p = 0.017), or a homologous GG genotype at TNF-238 (p = 0.001), had a tendency to advanced disease.

CONCLUSIONS

A significant association between the 308 G/A and 238 G/A polymorphisms in the promoter region of TNF-alpha and the susceptibility to lung cancer was demonstrated. Also, these two polymorphisms were associated with the severity of lung cancer. The -308 A allele has a promotive effect for lung cancer development and progression, whereas the -238 A allele has a protective function against lung cancers.

Role of glucocorticoid‐induced TNF receptor family gene (GITR) in collagen‐induced arthritis

In rheumatoid arthritis (RA), a widespread autoimmune/inflammatory joint disease, early activation of effector CD4+ T lymphocytes, and cytokine production is followed by recruitment of other inflammatory cells, production of a range of inflammation mediators, tissue damage, and disease. GITR (glucocorticoid-induced TNFR family-related gene), a costimulatory molecule for T lymphocytes, increases CD4+CD25- effector T cell activation while inhibiting suppressor activity of CD4+CD25+ T regulatory (Treg) cells. We analyzed the role of GITR in type II collagen (CII) -induced arthritis (CIA) using GITR-/- and GITR+/+ mice. Results indicate significantly less CIA induction in GITR-/- mice than in GITR+/+ mice, with marked differences in erythema, edema, neutrophil infiltration, joint injury, and bone erosion. Production of IFNgamma, IL-6, TNFalpha, MIP-1alpha, and MIP-2, inducible NOS (iNOS), COX-2, and nitrotyrosine poly-ADP-ribose (PAR) were also less in CII-treated GITR-/- mice. Although CD4+CD25+ Treg cells from GITR+/+ and GITR-/- CII-challenged mice exerted similar suppressor activity in vitro, GITR triggering abrogated GITR+/+ Treg suppressor activity and costimulated CD4+CD25- GITR+/+ effector cells. Furthermore, Treg cells from GITR-/- protected more than Treg cells from GITR+/+ mice against CIA when cotransferred with Treg-depleted splenocytes from arthritic GITR+/+ animals into severe combined immunodeficient (SCID) mice. In conclusion, GITR plays a critical role in the immunological response against CII and in the development of CIA.

Angiogenesis and stem cell transplantation as potential treatments of cerebral ischemic stroke

Ischemic stroke is a leading cause of human death and disability. Although stroke survivors may gain spontaneous partial functional recovery, they often suffer from sensory-motor dysfunctions, behavioral/neurological alterations, and various degrees of paralysis. Currently, limited clinical intervention is available to prevent ischemic damage and restore lost function in stroke victims. In addition to the extensive research on protective maneuvers against ischemia-induced cell death, increasing attention has been focused on potential strategies of promoting tissue repair and functional recovery in the damaged post-ischemic brain. Angiogenesis, or the growth of new blood vessels, may contribute to cell survival and functional recovery of the area of insult. The study of angiogenesis will increase the understanding of the mechanism underlying post-ischemia neurovascular plasticity and regeneration. Additionally, stem cell transplantation has emerged in the last few years as a potential therapy for ischemic stroke, because of their capability to differentiate into multiple cell types and the possibility that they may provide trophic support for cell survival, tissue repair, and functional recovery.

A double-blind, randomized, controlled study of oral pirfenidone for treatment of secondary progressive multiple sclerosis

Currently, there are no approved treatments for secondary progressive multiple sclerosis (MS) that stabilize or reverse the neurological disabilities associated with this disease. Oral pirfenidone was found to stabilize and overcome the disabilities in two published independent open-label studies in secondary progressive MS. This led us to study pirfenidone in a phase II double-blind, randomized and controlled, clinical trial in patients with advanced secondary progressive MS for 12 months. Forty-three patients met the eligibility criteria approved by the IRB and accepted by the FDA. Of these patients, 18 were randomly assigned to placebo and 25 patients to oral pirfenidone groups. All eligible patients were included in the statistical analysis of the data according to intention-to-treat principles. Some patients on oral pirfenidone manifested mild drug-related adverse effects, but it was well tolerated overall. By one month, pirfenidone significantly (P < 0.05) improved the Scripps Neurological Rating Scale (SNRS) scores, and scores remained significantly improved for 3, 6 and 12 months when compared to the baseline SNRS scores. In contrast, the SNRS scores of patients on oral placebo were not significantly improved at 1, 3, 6 or 12 months of the study, when compared with baseline scores. Oral pirfenidone significantly (P <0.04) reduced the incidence of relapses (27.8% on placebo versus 8.0% on pirfenidone). Furthermore, oral pirfenidone treatment was associated with a marked improvement in bladder dysfunction (40.0% on pirfenidone versus 16.7% on placebo). Expanded Disability Status Scale scores and MRI lesion count were not significantly different in the placebo and pirfenidone groups. These findings indicate a significant effect of pirfenidone on clinical disability and bladder function for secondary progressive MS patients. A major multicentre, double-blind, randomized, controlled trial is justified.

An essential role for tumor necrosis factor in the formation of experimental murine Staphylococcus aureus-induced brain abscess and clearance

Tumor necrosis factor-alpha (TNF-alpha) is a central mediator of the immune response to pathogens, but may also exert neurotoxic effects, thereby contributing to immunopathology. To define the role of TNF during the course of brain abscess, TNF-deficient (TNF(0/0) mice were stereotaxically infected with Staphylococcus (S.) aureus-laden agarose beads. In comparison to 100% survival of wild type (WT) mice, TNF(0/0) mice displayed high mortality rates (54%) in the initial phase of abscess development as well as significantly increased morbidity in the course of the disease. The worse clinical outcome was due to an increased intracerebral (i.c.) bacterial load in TNF(0/0) mice as compared to WT mice. The impaired control of S. aureus was associated with reduced inductible nitric oxide synthase (iNOS) mRNA and protein expression in TNF(0/0)mice. Similarly, numbers of inflammatory leukocytes, cytokine expression of IL-6, IL-12p40, IFNgamma IL-beta mRNA, and brain edema were significantly increased in TNF(0/0)mice as compared to WT animals. In addition, resolution of i.c. infiltrates was delayed in TNF(0/0)mice correlating with reduced apoptosis of inflammatory leukocytes and formation of a fibrous abscess capsule. Collectively, these data demonstrate that TNF is of key importance for the control of S. aureus-induced brain abscess and regulates the ensuing host immune response.

Targeted Bioactivity of Membrane-Anchored TNF by an Antibody-Derived TNF Fusion Protein

We describe the generation and characterization of a fusion protein consisting of a humanized anti-fibroblast-activating protein (anti-FAP) Ab and human TNF replacing the IgG1 CH2/CH3 Fc domain. The construct was generated by recombinant DNA technology and preserved its IgG1-derived dimeric structure with the TNF molecule linked as a dimer. Expression in CHO cells was optimized in serum-free medium under GMP conditions to achieve production levels up to 15 mg/liter. Recognition of the FAP Ag by the construct was as good as that by the parental anti-FAP Ab. TNF signaling was induce able via both TNF receptor types. When acting in solution, the Ab-linked TNF dimer exhibited a 10- to 20-fold lower activity compared with recombinant trimeric TNF. However, after binding to FAP-expressing cells, immobilized anti-FAP-TNF dimer was equivalent to membrane-anchored TNF with regard to bioactivity. Amplification of TNF-related pathways by mimicking the membrane-integrated TNF signaling was detectable in various systems, such as apoptosis induction or tissue factor production. The difference in TNF receptor type 1 and 2 signaling by the anti-FAP-TNF construct correlated well with its Ag-bound or -soluble status. Translating the approach into a xenograft animal model (BALB/c nu/nu mice), we demonstrated low toxicity with measurable antitumor efficacy for the TNF fusion protein after i.v. application. Immunohistochemical analysis of tumor sections showed restricted TNF-mediated macrophage recruitment to the targeted tissue in a time- and dose-dependent manner. These data warrant transfer of the anti-FAP-TNF immunocytokine into clinical trials for the treatment of FAP-positive tumors.

Tumor necrosis factor activates CRE-binding protein through a p38 MAPK/MSK1 signaling pathway in endothelial cells

Tumor necrosis factor (TNF) promotes immunity and modulates cell viability, in part, by promoting alterations of cellular gene expression. The mechanisms through which TNF communicates with the nucleus and alters gene expression are incompletely understood. Incubation of human umbilical vein endothelial cells (HUVEC) with TNF induces phosphorylation of the CRE-binding protein (CREB) transcription factor on serine 133 and increases CREB DNA binding and transactivation. Dominant negative CREB, an antagonist antibody directed against the type 1 TNF receptor, or pharmacological inhibition of p38 MAPK signaling blocked TNF-induced CREB activation as determined by phosphorylation and gene reporter assays. From among the kinases that can activate CREB, we found that downstream of p38 MAPK, MSK1 is activated by TNF to promote CREB activation. These observations show that CREB is activated by TNF/TNFR1 signaling through a p38MAPK/MSK1 signaling pathway.

Tumor necrosis factor alpha is not implicated in the genesis of experimental autoimmune gastritis

Experimental autoimmune gastritis (EAG) characterised by mononuclear cell infiltrate, parietal and zymogenic cell destruction and circulating autoantibodies to gastric H(+)/K(+)ATPase is an animal model for human autoimmune gastritis, that leads to pernicious anaemia. We have previously shown that Fas has a role in initiating damage to target cells in EAG. Here we used three strategies to examine the role of TNFalpha in this disease. We administered neutralising anti-TNFalpha antibody either as a single injection or as twice weekly injections for 8 weeks to mice subjected to neonatal thymectomy-induced EAG. To address the role of apoptotic signals through TNFR1, TNFR1 deficient mice were either neonatally thymectomised or crossed to PC-GMCSF transgenic mice that spontaneously develop EAG. Neonatally thymectomised mice treated with anti-TNFalpha antibody developed destructive gastritis and autoantibodies to gastric H(+)/K(+)ATPase similar to control mice. Following either neonatal thymectomy or crossing to PC-GMCSF transgenic mice, TNFR1 deficient mice developed autoantibody-positive destructive gastritis at similar frequency compared with wild type and heterozygous littermates. Our observations that neutralisation of TNFalpha and absence of TNFR1 has no discernible effect on development of EAG suggest that TNFalpha is not required for mucosal cell damage or development of autoimmune gastritis. While blocking TNFalpha activity has therapeutic benefit in certain autoimmune diseases, this is not the case for EAG.

Associations of HLA microsatellites with rheumatoid arthritis in Singaporean Chinese

Rheumatoid arthritis in Singaporean Chinese has previously been shown to be associated with the DRB1*0405, DRB1*1001 haplotypes and to the DRB1*0901 haplotype when the former two were removed. The present paper focused on eight HLA associated microsatellite markers (TNFa, TNFd, D6S273, TAP1CA, DQCAR, DQCARII, D6S2222, D6S2223) and their allelic associations with Chinese RA. 60 RA patients and 75 healthy controls were studied. It appeared that DQCARII*194/DRB1*0405/TNFa*117 was part of the extended haplotype predisposed to RA, whereas DRB1*0901/D6S273*128 contributed to susceptibility to RA to a lesser degree in Singaporean Chinese. Additionally, a negative association with DQCAR*186/DRB1*0301/D6S273*122/TNFd*124 was observed. No association with disease development was observed in this study.

Tumor necrosis factor microsatellite alleles in patients with rheumatoid arthritis in Taiwan

OBJECTIVE

To investigate the association of tumor necrosis factor (TNF) microsatellite alleles with the pathogenesis of rheumatoid arthritis (RA) in Taiwan.

METHODS

The TNF a, b, c, d, and e microsatellites were determined in 112 patients with RA and 99 healthy controls by using polymerase chain reaction (PCR) and electrophoresis with sequencing gel. All of these patients and controls had known HLA-DR genotypes and TNF-308 polymorphisms.

RESULTS

The phenotypic frequency of TNFa9 was significantly higher in DR4(-) RA patients than in DR4(-) controls. However, the phenotypic frequency of TNFb6 was significantly higher in RA patients than in controls in the presence of HLA-DR4. The phenotypic frequency of TNFa3-e1 was significantly lower in DR4(+) RA patients than in DR4(+) controls, while a negative linkage disequilibrium was noted between TNFa3-e1 and HLA-DR4. TNF microsatellite alleles were not related to the prevalences of bone erosion, rheumatoid nodule, sicca syndrome, pulmonary fibrosis, and seropositivity of rheumatoid factor (RF) in patients with RA.

CONCLUSION

The associations of TNF microsatellites with the susceptibility to RA in Taiwan are not completely independent of the HLA-DR associations. The association of TNFb6 with the susceptibility to RA depends on the presence of HLA-DR4, and the correlation of TNFa9 to RA depends on the absence of HLA-DR4. The negative association of TNFa3-e1 with RA may be secondary to the negative linkage disequilibrium between TNFa3-e1 and HLA-DR4. Moreover, TNFb6 and HLA-DR4 have a synergistic effect on the susceptibility to RA. TNFa3-e1 and TNF-308A have a synergistic effect on preventing from RA. The TNF microsatellite alleles are not related to the clinical manifestations and severity of RA patients in Taiwan.

Identification of tumor necrosis factor (TNF) amino acids crucial for binding to the murine p75 TNF receptor and construction of receptor-selective mutants

The bioactivity of tumor necrosis factor (TNF) is mediated by two TNF receptors (TNF-Rs), more particularly TNF-RI and TNF-RII. Although human TNF (hTNF) and murine TNF (mTNF) are very homologous, hTNF binds only to mTNF-RI. By measuring the binding of a panel of mTNF/hTNF chimeras to both mTNF-R, we pinpointed the TNF region that mediates the interaction with mTNF-RII. Using site-specific mutagenesis, we identified amino acids 71-73 and 89 as the main interacting residues. Mutein hTNF-S71D/T72Y/H73 Delta/T89E interacts with both types of mTNF-R and is active in CT6 cell proliferation assays mediated by mTNF-RII. Mutein mTNF-D71S/Y72T/Delta 73H/E89T binds to mTNF-RI only and is no longer active on CT6 cells. However, the L929s cytotoxicity of this mutein (an effect mediated by mTNF-RI triggering) was also 100-fold lower than that of wild-type mTNF due to enhanced dissociation during incubation at subnanomolar concentrations. The additional mutation of amino acid 102, resulting in the mutein mTNF-D71S/Y72T/Delta 73H/E89T/P102Q, restored the trimer stability, which led to an enhanced specific activity on L929s cells. Hence the specific activity of a TNF species is governed not only by its receptor binding characteristics but also by its trimer stability after incubation at subnanomolar concentrations. In conclusion, the mutation of TNF amino acids 71-73, 89, and 102 is sufficient to obtain a mTNF mutein selective for mTNF-RI and a hTNF mutein that, unlike wild-type hTNF, also acts on mTNF-RII.

Pirfenidone for chronic progressive multiple sclerosis

Current treatment of secondary progressive multiple sclerosis is unsatisfactory in stabilizing or reversing the disabilities associated with the disease. Pirfenidone is a new non-peptide drug which has been shown in vitro and in vivo to decrease synthesis of Tumor Necrosis Factor-alpha (TNF-alpha) and block receptors for TNF-alpha. Since TNF-alpha seems to be a key cytokine in demyelination, a pilot study of oral pirfenidone was undertaken in an open-label baseline vs treatment protocol over a 2-year period in 20 patients. Fourteen (14120) patients (70%) remained in the study for 2 years. Three (3/20) patients dropped out early because of gastrointestinal adverse reactions, and another three patients dropped out for personal reasons after 1 year (not because of adverse reactions). The remaining patients did not manifest any other drug-related adverse reactions and complications. Improvement or stabilization occurred in most patients at about 3 months, and it was sustained at 6, 12 and 24 months as evaluated by both primary and secondary outcome measures. Magnetic resonance imaging foiled to reveal any new lesions. Thus, pirfenidone appears to offer protection against the usual slow progression of the disease. Most patients experienced a distinct decrease in their neurological disability. These findings indicate that an extensive multi-center double blind and placebo controlled trial is warranted.

Heterotrimers Formed by Tumor Necrosis Factors of Different Species or Muteins

Incubation of murine tumor necrosis factor (mTNF) at subnanomolar concentrations results in partial dissociation of the trimers, coinciding with a decrease in bioactivity. Using size-exclusion chromatography, we observed that the conversion of labeled mTNF to monomers is not only prevented by coincubation with an excess of unlabeled mTNF but also with unlabeled human TNF (hTNF). Moreover, after coincubation of mTNF and hTNF four different TNF complexes were revealed by native polyacrylamide gel electrophoresis, viz. homotrimeric mTNF and hTNF, as well as two complexes with an intermediate migration pattern. Analytical gel filtration in combination with native polyacrylamide gel electrophoresis and Western blot immunodetection indicated that these new complexes consisted of heterotrimeric TNF molecules. We conclude that an exchange of monomers takes place during coincubation of two different species of TNF, which results in homotrimeric and heterotrimeric TNF. To assess receptor interaction in vitro, TNF heterotrimeric molecules were used as obtained after incubation of mTNF with labeled hTNF (which only binds to mTNF receptor I) or with labeled mutein mTNF75 (specific for mTNF receptor II). These heterotrimers were retained by both mTNF receptors, which means that the mTNF subunits incorporated in heterotrimeric complexes still can bind to both types of TNF receptor. In addition, the gradual decrease in mTNF bioactivity during preincubation at subnanomolar concentrations was prevented by the presence of mutein mTNF75, which is inactive in an L929 cytotoxicity assay, indicating that heterotrimerization can influence the overall bioactivity.

The PTEN tumor suppressor protein inhibits tumor necrosis factor-induced nuclear factor kappa B activity

Nuclear factor kappaB (NF-kappaB) transcriptionally activates genes that promote immunity and cell survival. Activation of NF-kappaB is induced by an IkappaB kinase (IKK) complex that phosphorylates and promotes dissociation of IkappaB from NF-kappaB, which then translocates into the nucleus. Activation of phosphatidylinositol (PI) 3-kinase/Akt signaling by tumor necrosis factor (TNF) activates IKK and NF-kappaB. The present study shows that PTEN, a tumor suppressor that inhibits PI 3-kinase function, impairs TNF activation of Akt and the IKK complex in 293 cells. Transient expression of PTEN suppressed IKK activation and TNF-induced NF-kappaB DNA binding and transactivation. Studies were conducted with PC-3 prostate cancer cells that do not express PTEN and DU145 prostate cancer cells that express PTEN. TNF activated Akt in PC-3 cells, but not in DU145 cells, and the ability of TNF to activate NF-kappaB was blocked by pharmacological inhibition of PI 3-kinase activity in PC-3 cells, but not in DU145 cells. Expression of PTEN in PC-3 cells to a level comparable with that endogenously present in DU145 cells inhibited TNF activation of NF-kappaB. The cell type-specific ability of PTEN to negatively regulate the PI 3-kinase/AKT/NF-kappaB pathway may be important to its tumor suppressor activity.

Potential biologic agents for treating rheumatoid arthritis

The encouraging clinical results observed in trials using anti-TNF therapy clearly warrant further studies to determine whether TNF inhibitors are capable of modifying the destructive component of this disease in long-term follow-up studies as well as to assess the safety of long-term use (see the article by Keystone in this issue). It is also reasonable to propose that interfering with the cytokine cascade earlier in the course of disease may be of even greater therapeutic benefit. As the pathogenetic mechanisms in RA are more clearly defined, especially in early disease and in those individuals destined to develop severe disease, the potential of other biologic agents to specifically inhibit these critical pathways may provide better treatments for our patients. Many potential targets in the immune-mediated process of RA are currently being rigorously evaluated in clinical trials. Use of combinations of biologic therapies, perhaps in human patients with RA, should be of considerable interest in future trials.

A phosphatidylinositol 3-kinase/Akt/mTOR pathway mediates and PTEN antagonizes tumor necrosis factor inhibition of insulin signaling through insulin receptor substrate-1

Tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) by the insulin receptor permits this docking protein to interact with signaling proteins that promote insulin action. Serine phosphorylation uncouples IRS-1 from the insulin receptor, thereby inhibiting its tyrosine phosphorylation and insulin signaling. For this reason, there is great interest in identifying serine/threonine kinases for which IRS-1 is a substrate. Tumor necrosis factor (TNF) inhibited insulin-promoted tyrosine phosphorylation of IRS-1 and activated the Akt/protein kinase B serine-threonine kinase, a downstream target for phosphatidylinositol 3-kinase (PI 3-kinase). The effect of TNF on insulin-promoted tyrosine phosphorylation of IRS-1 was blocked by inhibition of PI 3-kinase and the PTEN tumor suppressor, which dephosphorylates the lipids that mediate PI 3-kinase functions, whereas constitutively active Akt impaired insulin-promoted IRS-1 tyrosine phosphorylation. Conversely, TNF inhibition of IRS-1 tyrosine phosphorylation was blocked by kinase dead Akt. Inhibition of IRS-1 tyrosine phosphorylation by TNF was blocked by rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), a downstream target of Akt. mTOR induced the serine phosphorylation of IRS-1 (Ser-636/639), and such phosphorylation was inhibited by rapamycin. These results suggest that TNF impairs insulin signaling through IRS-1 by activation of a PI 3-kinase/Akt/mTOR pathway, which is antagonized by PTEN.

Overexpression of the apoptosis inhibitor FLIP in T cells correlates with disease activity in multiple sclerosis

The cellular caspase-inhibitory protein FLIP has been recently identified as a potent regulator of T lymphocyte susceptibility to Fas-mediated programmed cell death (apoptosis). Since impairment of apoptosis may be involved in multiple sclerosis (MS), we investigated the dynamics of cellular FLIP in unstimulated and activated T lymphocytes from MS patients, inflammatory and non-inflammatory neurological disorders, and healthy subjects. Cellular expression of the long and short forms of FLIP protein was similar in unstimulated T cells from MS patients and controls, but was significantly higher in activated T cells from patients with clinically active MS. This high FLIP expression in active MS correlated with cellular resistance to Fas-mediated apoptosis. In contrast, cellular expression of the anti-apoptotic protein Bcl-2 did not differ between active and stable disease, and was relatively similar between the MS group and controls. These findings suggest that cellular overexpression of the anti-apoptotic protein FLIP is a feature of clinically active multiple sclerosis.

Increased cellular expression of the caspase inhibitor FLIP in intrathecal lymphocytes from patients with multiple sclerosis

Failure of Fas-mediated apoptosis of potentially pathogenic, autoreactive T lymphocytes may be involved in the pathogenesis of multiple sclerosis. The intracellular protein FLIP, a naturally occurring caspase-antagonist, is a potent inhibitor of the Fas signalling pathway that may block Fas-mediated apoptosis of activated lymphocytes. This study reports specific overexpression of both long and short forms of FLIP in intrathecal lymphocytes from patients with multiple sclerosis. The overexpression of FLIP is independent of cellular expressions of Fas receptor or the anti-apoptotic protein Bcl-2. These results provide a better understanding of some of the intrinsic immunoregulatory mechanisms that are involved in multiple sclerosis.

TNF alpha and the TNF receptor superfamily: structure-function relationship(s)

Tumour Necrosis Factor alpha (TNF alpha), is an inflammatory cytokine produced by macrophages/monocytes during acute inflammation and is responsible for a diverse range of signalling events within cells, leading to necrosis or apoptosis. The protein is also important for resistance to infection and cancers. TNF alpha exerts many of its effects by binding, as a trimer, to either a 55 kDa cell membrane receptor termed TNFR-1 or a 75 kDa cell membrane receptor termed TNFR-2. Both these receptors belong to the so-called TNF receptor superfamily. The superfamily includes FAS, CD40, CD27, and RANK. The defining trait of these receptors is an extra cellular domain comprised of two to six repeats of cysteine rich motifs. Additionally, a number of structurally related "decoy receptors" exist that act to sequester TNF molecules, thereby rescuing cells from apoptosis. The crystal structures of TNF alpha, TNF beta, the extracellular domain of TNFR-1 (denoted sTNFR-1), and the TNF beta sTNFR-1 complex have been defined by crystallography. This article will review the structure/function relationships of the TNF alpha and the TNF receptor superfamily. It will also discuss insights as to how structural features play a role in the pleiotropic effects of TNF alpha.

Nitric oxide inhibits tumor necrosis factor-alpha-induced apoptosis by reducing the generation of ceramide

Apoptosis triggered by death receptors proceeds after defined signal-transduction pathways. Whether signaling at the receptor level is regulated by intracellular messengers is still unknown. We have investigated the role of two messengers, ceramide and nitric oxide (NO), on the apoptotic pathway activated in human monocytic U937 cells by tumor necrosis factor-alpha (TNF-alpha) working at its p55 receptor. Two transduction events, the receptor recruitment of the adapter protein, TRADD, and the activation of the initiator caspase, caspase 8, were investigated. When administered alone, neither of the messengers had any effect on these events. In combination with TNF-alpha, however, ceramide potentiated, whereas NO inhibited, TNF-alpha-induced TRADD recruitment and caspase 8 activity. The effect of NO, which was cGMP-dependent, was due to inhibition of the TNF-alpha-induced generation of ceramide. Our results identify a mechanism of regulation of a signal-transduction pathway activated by death receptors.