Induction of allospecific tolerance by immature dendritic cells genetically modified to express soluble TNF receptor

The ability of dendritic cells (DC) to initiate immune responses or induce immune tolerance is strictly dependent on their maturation state. TNF-alpha plays a pivotal role in the differentiation and maturation of DC. Blockade of TNF-alpha action may arrest DC in an immature state, prolonging their window of tolerogenic opportunity. Immature DC (imDC) were transfected with recombinant adenovirus to express soluble TNF-alpha receptor type I (sTNFRI), a specific inhibitor of TNF-alpha. The capacity of sTNFRI gene-modified imDC (DC-sTNFRI) to induce immune tolerance was analyzed. sTNFRI expression renders imDC resistant to maturation induction and impairs their capacity to migrate or present Ag. This process leads to induction of allogeneic T cell hyporesponsiveness and the generation of IL-10-producing T regulatory-like cells. In vivo pretreatment of transplant recipients with DC-sTNFRI induces long-term survival of cardiac allografts in 50% of cases, and leads to a substantial increase in the generation of microchimerism and T regulatory cell numbers. Thus, blockade of TNF-alpha action by sTNFRI genetic modification can inhibit the maturation of DC and potentiate the in vivo capacity of imDC to induce donor-specific immune tolerance and prolong allograft survival.

Adenovirus RIDalphabeta complex inhibits lipopolysaccharide signaling without altering TLR4 cell surface expression

The transmembrane heterotrimer complex 10.4K/14.5K, also known as RID (for "receptor internalization and degradation"), is encoded by the adenovirus E3 region, and it down-regulates the cell surface expression of several unrelated receptors. We recently showed that RID expression correlates with down-regulation of the cell surface expression of the tumor necrosis factor (TNF) receptor 1 in several human cells. This observation provided the first mechanistic explanation for the inhibition of TNF alpha-induced chemokines by RID. Here we analyze the immunoregulatory activities of RID on lipopolysaccharide (LPS) and interleukin-1 beta (IL-1beta)-mediated responses. Although both signaling pathways are strongly inhibited by RID, the chemokines up-regulated by IL-1beta stimulation are only marginally inhibited. In addition, RID inhibits signaling induced by LPS without affecting the expression of the LPS receptor Toll-like receptor 4, demonstrating that RID need not target degradation of the receptor to alter signal transduction. Taken together, our data demonstrate the inhibitory effect of RID on two additional cell surface receptor-mediated signaling pathways involved in inflammatory processes. The data suggest that RID has intracellular targets that impair signal transduction and chemokine expression without evidence of receptor down-regulation.

Tumor necrosis factor-alpha and CD40L modulate cell surface morphology and induce aggregation in Ramos Burkitt's lymphoma cells

Interaction of CD40L and its cognate receptor is an essential component of B-lymphocyte signaling, affecting various aspects of B-cell differentiation pathways and immunoglobulin gene expression. However, much less is known about the biological consequences of B-cell signaling through tumor necrosis factor (TNF)-alpha and its cognate receptors TNF-R1 and 2. We used Ramos Burkitt's lymphoma cell line as a model system to study the direct effects of these cytokines on B cells. Treatment of Ramos cells with either TNF-alpha or CD40L, but not with interleukin (IL)- 4, interferon (IFN)-gamma and transforming growth factor (TGF)-beta, resulted in enhanced cell aggregation and enhancement of adherence to glass cover-slips. Scanning electron microscopy showed that Ramos cells have a polarized cell surface morphology and exhibit at least 3 cell surface morphological domains: microvilli, filopodia and ruffled membranes. The cells adhered to the glass matrix through multiple filopodia/podopodia-like cell processes and demonstrated distinct ruffled-like membrane projections on their opposite pole. Induction by TNF-alpha or CD40L, but not with IL-4, IFN-gamma and TGF-beta, resulted in increased number and complexity of both types of membrane projections. TNF-alpha and CD40L upregulated the expression of the adhesion molecule intercellular adhesion molecule-1 and the Fas receptor on Ramos cells, without affecting the expression levels of membrane immunoglobulin M or its secretion rate. Reverse transcriptase-polymerase chain reaction, and flow cytometry demonstrated that Ramos cells expressed TNF-R1 but very little if any TNF-R2, indicating that TNF-alpha exerted its effects on Ramos cells through the former receptor.

Luteolin promotes degradation in signal transducer and activator of transcription 3 in human hepatoma cells: an implication for the antitumor potential of flavonoids

In this study, we have investigated the underlying molecular mechanism for the potent proapoptotic effect of luteolin on human hepatoma cells both in vitro and in vivo, focusing on the signal transducer and activator of transcription 3 (STAT3)/Fas signaling. A clear apoptosis was found in the luteolin-treated HLF hepatoma cells in a time- and dosage-dependent manner. In concert with the caspase-8 activation by luteolin, an enhanced expression in functional Fas/CD95 was identified. Consistent with the increased Fas/CD95 expression, a drastic decrease in the Tyr(705) phosphorylation of STAT3, a known negative regulator of Fas/CD95 transcription, was found within 20 minutes in the luteolin-treated cells, leading to down-regulation in the target gene products of STAT3, such as cyclin D1, survivin, Bcl-xL, and vascular endothelial growth factor. Of interest, the rapid down-regulation in STAT3 was consistent with an accelerated ubiquitin-dependent degradation in the Tyr(705)-phosphorylated STAT3, but not the Ser(727)-phosphorylated one, another regulator of STAT3 activity. The expression level of Ser(727)-phosphorylated STAT3 was gradually decreased by the luteolin treatment, followed by a fast and clear down-regulation in the active forms of CDK5, which can phosphorylate STAT3 at Ser(727). An overexpression in STAT3 led to resistance to luteolin, suggesting that STAT3 was a critical target of luteolin. In nude mice with xenografted tumors using HAK-1B hepatoma cells, luteolin significantly inhibited the growth of the tumors in a dosage-dependent manner. These data suggested that luteolin targeted STAT3 through dual pathways-the ubiquitin-dependent degradation in Tyr(705)-phosphorylated STAT3 and the gradual down-regulation in Ser(727)-phosphorylated STAT3 through inactivation of CDK5, thereby triggering apoptosis via up-regulation in Fas/CD95.

[Comparative study of that synergistic effect of cisplatin combined with compound herbal medicinal prescription for tonic quality and activating blood circulation is on SKOV3 cell proliferation and apoptosis]

OBJECTIVE

To investigate the synergistic effects on cell apoptosis and growing restriction of SKOV3 cells by the combination of compound herbal medicinal prescription (CHMP) with cisplatin (DDP).

METHODS

Cisplatin and two CHMP for tonic quality(CHMP1) and activating blood circulation (CHMP2), which was medicated serum, were prepared and used to treat the human ovarian carcinoma cell line SKOV3. By serum pharmacologic method, the growth and apoptosis of SKOV3 cell were observed at different time points(24,48,72, 96 h) with different concentrations of medicated serum. Coefficient of drug interaction (CDI) between CHMP, and CHMP2 was studied by MTT method. The effects of control group(A group),CHMP1 group(B group),CHMP2 group (C group), DDP group(D group), CHMP1 + DDP group(E group), CHMP2 + DDP group(Fgroup)to SKOV3 cell were studied by flow cytometry; and the cell apoptosis was observed by agarose electrophoresis; the expressions of TNFR1, caspase-8 on each group were analyzed by Western blot method.

RESULTS

Synergistic effects were found between herbal medicinal mixtures and DDP, Restraining rate of SKOV3 and CHMP serum concentration was not in a dose-dependent manner as DDP was. CDI between CHMPI and CHMPS was found to be significant difference (CDI of CHMP1, CHMP2 and DDPwas 0.66, 0.58 respectively). It showed that the combined treatment was able to get better effect than single drug treatment. The performed agarose electrophoresis revealed the extracted DNA to show a typical ladder patterns for cell apoptosis. The analysis results of western blot showed the increased expressions of TNFR1 and caspase-8 after combined using of medicine, which were accord to the rates of apoptosis.

CONCLUSIONS

CHMP drug granules show the synergistic effects with DDP, and the suppressing functions in the course of cell proliferation, and the inducing effect on apoptosis of human ovarian carcinoma cell line SKOV3 in vitro. And this mechanism is showed to be sponsored by the activation of TNFR1 and Caspase-8.

Histone Deacetylase Inhibitors Suppress the Inducibility of Nuclear Factor-κB by Tumor Necrosis Factor-α Receptor-1 Down-regulation

Recently, the inhibition of histone deacetylase (HDAC) enzymes has attracted attention in the oncologic community as a new therapeutic opportunity for hematologic and solid tumors including non-small cell lung cancer (NSCLC). In hematologic malignancies, such as diffuse large B-cell lymphoma, the HDAC inhibitor (HDI), suberoylanilide hydroxamic acid (SAHA), has recently entered phase II and III clinical trials. To further advance our understanding of their action on tumor cells, we investigated the possible effect of HDI treatment on the functionality of the nuclear factor-kappaB (NF-kappaB) pathway in NSCLC. We found that in the NSCLC cell lines, A549 and NCI-H460, the NF-kappaB pathway was strongly inducible, for example, by stimulation with tumor necrosis factor-alpha (TNF-alpha). Incubation of several NSCLC cell lines with HDIs resulted in greatly reduced gene expression of TNF-alpha receptor-1. HDI-treated A549 and NCI-H460 cells down-regulated TNF-alpha receptor-1 mRNA and protein levels as well as surface exposure, and consequently responded to TNF-alpha treatment with reduced IKK phosphorylation and activation, delayed IkappaB-alpha phosphorylation, and attenuated NF-kappaB nuclear translocation and DNA binding. Accordingly, stimulation of NF-kappaB target gene expression by TNF-alpha was strongly decreased. In addition, we observed that SAHA displayed antitumor efficacy in vivo against A549 xenografts grown on nude mice. HDIs, therefore, might beneficially contribute to tumor treatment, possibly by reducing the responsiveness of tumor cells to the TNF-alpha-mediated activation of the NF-kappaB pathway. These findings also hint at a possible use of HDIs in inflammatory diseases, which are associated with the overproduction of TNF-alpha, such as rheumatoid arthritis or Crohn's disease.

Alterations in mesenteric lymph node T cell phenotype and cytokine secretion are associated with changes in thymocyte phenotype after LP-BM5 retrovirus infection

In this study, mouse MLN cells and thymocytes from advanced stages of LP-BM5 retrovirus infection were studied. A decrease in the percentage of IL-7(+) cells and an increase in the percentage of IL-16(+) cells in the MLN indicated that secretion of these cytokines was also altered after LP-BM5 infection. The percentage of MLN T cells expressing IL-7 receptors was significantly reduced, while the percentage of MLN T cells expressing TNFR-p75 and of B cells expressing TNFR-p55 increased. Simultaneous analysis of surface markers and cytokine secretion was done in an attempt to understand whether the deregulation of IFN-gamma secretion could be ascribed to a defined cell phenotype, concluding that all T cell subsets studied increased IFN-gamma secretion after retrovirus infection. Finally, thymocyte phenotype was further analyzed trying to correlate changes in thymocyte phenotype with MLN cell phenotype. The results indicated that the increase in single positive either CD4(+)CD8(-) or CD4(-)CD8(+) cells was due to accumulation of both immature (CD3(-)) and mature (CD3(+)) single positive thymocytes. Moreover, single positive mature thymocytes presented a phenotype similar to the phenotype previously seen on MLN T cells. In summary, we can conclude that LP-BM5 uses the immune system to reach the thymus where it interferes with the generation of functionally mature T cells, favoring the development of T cells with an abnormal phenotype. These new T cells are activated to secrete several cytokines that in turn will favor retrovirus replication and inhibit any attempt of the immune system to control infection.

Evidence of a role of tumor necrosis factor alpha in refractory asthma

BACKGROUND

The development of tumor necrosis factor alpha (TNF-alpha) antagonists has made it feasible to investigate the role of this cytokine in refractory asthma.

METHODS

We measured markers of TNF-alpha activity on peripheral-blood monocytes in 10 patients with refractory asthma, 10 patients with mild-to-moderate asthma, and 10 control subjects. We also investigated the effects of treatment with the soluble TNF-alpha receptor etanercept (25 mg twice weekly) in the patients with refractory asthma in a placebo-controlled, double-blind, crossover pilot study.

RESULTS

As compared with patients with mild-to-moderate asthma and controls, patients with refractory asthma had increased expression of membrane-bound TNF-alpha, TNF-alpha receptor 1, and TNF-alpha-converting enzyme by peripheral-blood monocytes. In the clinical trial, as compared with placebo, 10 weeks of treatment with etanercept was associated with a significant increase in the concentration of methacholine required to provoke a 20 percent decrease in the forced expiratory volume in one second (FEV1) (mean difference in doubling concentration changes between etanercept and placebo, 3.5; 95 percent confidence interval, 0.07 to 7.0; P=0.05), an improvement in the asthma-related quality-of-life score (by 0.85 point; 95 percent confidence interval, 0.16 to 1.54 on a 7-point scale; P=0.02), and a 0.32-liter increase in post-bronchodilator FEV1 (95 percent confidence interval, 0.08 to 0.55; P=0.01).

CONCLUSIONS

Patients with refractory asthma have evidence of up-regulation of the TNF-alpha axis. (ClinicalTrials.gov number, NCT00276029.).

Expression of TNFalpha and its receptors R1 and R2 in human alveolar epithelial cells exposed to organic dust and the effects of 8-bromo-cAMP and protein kinase A modulation

OBJECTIVE

Expression of tumor necrosis factor alpha (TNF), TNF receptors 1 and 2 and TNFalpha converting enzyme (TACE) was studied in A549 human alveolar epithelial cells exposed to organic dust from a swine barn. Additional objectives were to elucidate whether 8-bromocAMP affected TNF and TNF receptor mRNA expression by activation of protein kinase A (PKA) and whether it increased phosphorylation of cAMP-responsive element-binding protein (CREB).

MATERIALS AND METHODS

Reverse transcriptase- (RT-) PCR was performed on unexposed cells and cells exposed to a dust-suspension, with and without 8-bromo-cAMP (1 mM). H-89 was used to inhibit PKA. To further investigate mRNA expression of TNF, staurosporine was used. Immunolabeling was applied for detection of TNF, TNFR1, TNFR2 and phosphorylation of CREB.

RESULTS

TNF mRNA and protein was expressed after 1-3 h in dust-exposed cells. TNFR2 mRNA and protein expression was induced by dust-exposure, whereas expression of TNFR1 and TACE was constitutive. After 1-1.5 h incubation, mRNA expression of TNF was (PKA-independently) attenuated by 8-bromo-cAMP (p < 0.05), whereas that of TNFR1 was PKA-dependently stimulated (p < 0.05). Staurosporine attenuated mRNA expression of TNF (p < 0.05), but not interleukin (IL)-6, which was detected prior to TNF.

CONCLUSION

Expression of TNF and its receptors in alveolar epithelial cells may contribute to the response to organic dust. 8-bromo-cAMP, which increased the number of cells exhibiting phosphorylation of CREB exerted opposite effects on TNF and TNFR1 mRNA expression. The mechanism by which cAMP attenuates TNF mRNA expression remains to be established. Dust-induced expression of IL-6 precedes that of TNF and the induction pathways differ with regard to staurosporine sensitivity.

Effects of the active metabolite of leflunomide, A77 1726, on cytokine release and the MAPK signalling pathway in human rheumatoid arthritis synoviocytes

Inflammatory cytokines or soluble factors are essential in the pathogenesis of rheumatoid arthritis (RA). Leflunomide is an effective disease modifying antirheumatic drug (DMARD) in RA. The objective of the present study was to evaluate for the first time the effects of A77 1726 on cytokine (interleukin (IL)-8, IL-10, IL-11 secretion and tumor necrosis factor-alpha soluble receptor I (sTNFRI)) shedding in human RA fibroblast-like synoviocytes (FLS). At 100 microM, we observed an increase in IL-10 secretion, a decrease in IL-11 release and no effect on sTNFRI shedding and IL-8 secretion in IL-1beta-stimulated human RA FLS. Furthermore, at this dose, our results also confirmed that A77 1726 decreased IL-6 and prostaglandin E2 (PGE2) synthesis while it increased IL-1 receptor antagonist secretion (IL-1Ra). The mitogen-activated protein kinases (MAPKs) represent an attractive target for RA because they can regulate cytokine expression. At 100 microM, the effect of A77 1726 on IL-10 and IL-11 secretion seemed to be associated with the status of p38 MAPK activation. Our results confirmed the immunoregulatory action of leflunomide in the cytokine network involved in RA pathogenesis. It could shift the balance from cytokine mediated inflammation to cytokine directed inhibition of the inflammatory process.

Myocardial Expression of Fas and Recovery of Left Ventricular Function in Patients With Recent-Onset Cardiomyopathy

OBJECTIVES

This study aimed to evaluate the role of gene expression for predicting myocardial recovery in recent-onset cardiomyopathy.

BACKGROUND

Apoptosis may limit ventricular recovery. We examined the myocardial expression of Fas, Fas ligand (FasL), tumor necrosis factor (TNF)-alpha, and TNF receptor 1 (TNFR1), and myocardial recovery in patients from the multicenter Intervention in Myocarditis and Acute Cardiomyopathy (IMAC) study.

METHODS

Endomyocardial biopsy samples were obtained in 20 patients with recent-onset (<6 months) idiopathic dilated cardiomyopathy (left ventricular ejection fraction [LVEF] < or =0.40). The LVEF was assessed at baseline and at 6 and 12 months by nuclear scans. Myocardial expression was assessed by ribonuclease (RNase) protection, normalized to a constitutively active gene (glyceraldehydes 3-phosphate dehydrogenase [GAPDH]) and reported as percent GAPDH expression. The change in LVEF at 6 and 12 months was compared by tertiles of expression.

RESULTS

For all patients (14 men, 6 women; age 46.5 +/- 10.7 years), the mean LVEF was 0.28 +/- 0.05 at baseline and 0.40 +/- 0.14 at six months. Patients in the highest tertile of Fas expression had minimal improvement at six months (DeltaEF = 0.03 +/- 0.05) when compared with the intermediate (DeltaEF = 0.10 +/- 0.13) and lowest tertiles (DeltaEF = 0.21 +/- 0.11, change in LVEF by tertile, p = 0.006). A similar relationship was seen with TNFR1 expression (highest tertile, DeltaEF = 0.06 +/- 0.07; lowest tertile, DeltaEF = 0.21 +/- 0.11, p = 0.02). In contrast with Fas and TNFR1, expression of TNF-alpha and FasL did not predict recovery of LV function.

CONCLUSIONS

In cardiomyopathy of recent onset, increased expression of Fas and TNFR1 was associated with minimal recovery of LV function. Apoptosis limits myocardial recovery, and represents a potential target for therapeutic intervention.

[Expressions of tumor necrosis factor receptor I and II in human gastric carcinoma]

OBJECTIVE

To study the clinical significance of expressions of tumor necrosis factor receptor I and II(TNFR I and II) and their relationship with clinical pathology in human gastric carcinoma.

METHODS

SABC immunohistochemical method was used to examine the expressions of TNFR I and II in 51 cases of gastric carcinoma, 41 adjacent mucosal and 15 normal gastric mucosa tissues.

RESULTS

The positivity rates of TNFR I and II expressions in human gastric carcinoma were significantly higher than those in the adjacent mucosal and normal mucosal tissues, and their expressions were significantly higher in the surrounding mucosa than in the normal tissues. In gastric carcinoma tissues, no correlations of TNFR I and II expressions with serous membrane invasion or lymph node metastasis were found, but the differentiation grade was positively correlated with TNFR expressions (r=-0.3111, P=0.035; r=-0.5952, P=0.000, respectively).

CONCLUSION

TNFR I and II expressions are valuable indicators for determining the malignancy and predicting the differentiation grade of gastric carcinoma.

Endogenous oxidative stress induces distinct redox forms of tumor necrosis factor receptor-1 in melanoma cells

Receptors of the TNFR superfamily possess abundant thiols in their extracellular domains, which makes them susceptible to redox modulation by prooxidant agents and processes. Previous studies from our laboratory have documented that membrane gamma-glutamyltransferase (GGT) activity can originate reactive oxygen species in the extracellular milieu, during the GGT-mediated metabolism of extracellular glutathione. The present study was aimed thus to verify a possible redox-modulating effect of GGT activity on TNFR1 receptors. The thiol-specific probe maleimide-polyethylene glycol was used to selectively label the reduced thiol groups in proteins of cell lysates; fractions corresponding to TNFR1 were then identified by immunoblot. In human melanoma Me665/2 cells, expressing varying GGT levels, at least five distinct forms of TNFR1 have been thus identified. The more oxidized forms appear to be prevalent in the 2/60 clone, expressing higher GGT levels, as compared to clone 2/21. Stimulation of GGT activity in the latter induced an increase of the oxidized TNFR1 forms. It is conceivable that different redox states of TNFR1 may correspond to different binding affinity and/or changes in the transducing function of the receptor. As GGT is frequently expressed by malignant tumors, the described phenomena might concur to alter the sensitivity of cancer cells to agents targeted on activation of TNF-alpha-dependent signaling pathways.

Cell-specific expression and lipopolysaccharide-induced regulation of tumor necrosis factor alpha (TNFalpha) and TNF receptors in rat dorsal root ganglion

The proinflammatory and lipopolysaccharide (LPS)-inducible cytokine tumor necrosis factor alpha (TNFalpha) has been shown to enhance primary sensory nociceptive signaling. However, the precise cellular sites of TNFalpha and TNF receptor synthesis are still a matter of controversy. Therefore, we differentiated the neuronal and non-neuronal sites of TNFalpha, TNFR1, and TNFR2 mRNA synthesis in dorsal root ganglion (DRG) of control rats and evaluated how their expression is altered under systemic challenge with LPS. In situ hybridization (ISH), RT-PCR analysis of laser-microdissected cells, and immunocytochemistry revealed absence of TNFalpha from DRG neurons and LPS-induced expression of TNFalpha exclusively in a subpopulation of non-neuronal DRG cells. Using RT-PCR and Northern blotting TNFR1 and TNFR2 mRNAs were found to be constitutively expressed and increased after LPS. TNFR1 mRNA was expressed in virtually all neurons and in non-neuronal cells with increased levels after LPS in both. TNFR2 was exclusively expressed and regulated in non-neuronal cells. RT-PCR analysis of microdissected DRG neurons and of the sensory neuronal cell line F11 confirmed the neuronal expression of TNFR1 and excluded that of TNFR2. Double ISH revealed varying levels of TNFR1 mRNA in virtually all DRG neurons including putative nociceptive neurons coding for calcitonin gene-related peptide, substance P, or vanilloid receptor 1. Taken together, we provide evidence that non-neuronally synthesized TNFalpha may directly act on primary afferent neurons via TNFR1 but not TNFR2. This is likely to be relevant under conditions of inflammatory pain and infections accompanied by widespread TNFalpha synthesis and release and may drive sickness behavior.

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.

IG20 (MADD splice variant-5), a proapoptotic protein, interacts with DR4/DR5 and enhances TRAIL-induced apoptosis by increasing recruitment of FADD and caspase-8 to the DISC

Recently, we identified Insulinoma-Glucagonoma clone 20 (IG20) that can render cells more susceptible to tumor necrosis factor-alpha (TNF-alpha)-induced apoptosis. In addition, it can slow cell proliferation, and enhance drug- and radiation-induced cell death. TNF-related apoptosis-inducing ligand (TRAIL) can selectively induce apoptosis in some cancer cells and render others susceptible to cotreatment with drugs and irradiation, with little or no effect on most normal cells. In this study, we investigated the potential of IG20 to enhance TRAIL-induced apoptosis and found that it can render cells more susceptible to TRAIL treatment through enhanced activation of caspases. Further, we showed that this effect can be suppressed by caspase inhibitors, p35 and CrmA, and a dominant-negative Fas-associated death domain-containing protein (DN-FADD). Results from colocalization and immunoprecipitation studies showed that IG20 can interact with TRAIL death receptors (DR), DR4 and DR5 and increase recruitment of FADD and caspase-8 into the TRAIL death-inducing signaling complex (DISC). These results indicate that IG20 is a novel protein that can enhance TRAIL-induced apoptosis by facilitating DISC formation.

A chemotactic peptide from laminin alpha 5 functions as a regulator of inflammatory immune responses via TNF alpha-mediated signaling

Tissue injury triggers inflammatory responses that may result in release of degradation products or exposure of cryptic domains of extracellular matrix components. Previously, we have shown that a cryptic peptide (AQARSAASKVKVSMKF) in the alpha-chain of laminin-10 (alpha5beta1gamma1), a prominent basement membrane component, is chemotactic for both neutrophils (PMNs) and macrophages (Mphis) and induces matrix metalloproteinase-9 (MMP-9) production. To determine whether AQARSAASKVKVSMKF has additional effects on inflammatory cells, we performed microarray analysis of RNA from RAW264.7 Mphis stimulated with AQARSAASKVKVSMKF. Several cytokines and cytokine receptors were increased >3-fold in response to the laminin alpha5 peptide. Among these were TNF-alpha and one of its receptors, the p75 TNFR (TNFR-II), increasing 3.5- and 5.7-fold, respectively. However, the peptide had no effect on p55 TNFR (TNFR-I) expression. Corroborating the microarray data, the protein levels of TNF-alpha and TNFR-II were increased following stimulation of RAW264.7 cells with AQARSAASKVKVSMKF. In addition, we determined that the production of TNF-alpha and TNFR-II in response to AQARSAASKVKVSMKF preceded the production of MMP-9. Furthermore, using primary Mphis from mice deficient in TNFR-I, TNFR-II, or both TNF-alpha receptors (TNFRs), we determined that AQARSAASKVKVSMKF induces MMP-9 expression by Mphis through a pathway triggered by TNFR-II. However, TNF-alpha signaling is not required for AQARSAASKVKVSMKF-induced PMN release of MMP-9 or PMN emigration. These data suggest that interactions of inflammatory cells with basement membrane components may orchestrate immune responses by inducing expression of cytokines, recruitment of inflammatory cells, and release of proteinases.

Ethanol increases tumor necrosis factor-alpha receptor-1 (TNF-R1) levels in hepatic, intestinal, and cardiac cells

Chronic ethanol consumption leads to cell injury in virtually every tissue. Tumor necrosis factor-alpha (TNF-alpha) constitutes a major factor in the development of alcohol-induced liver injury. In alcohol-dependent subjects, elevated levels of plasma TNF-alpha are strongly predictive of mortality. Binding of TNF-alpha to TNF-alpha receptor-1 (TNF-R1) activates death domain pathways, leading to necrosis and apoptosis in most tissues, and it also increases the expression of intercellular adhesion molecules (i.e., ICAM-1), which promote inflammation. We determined whether ethanol exposure leads to increases in cellular TNF-R1. We incubated HepG2 human hepatoma cells and H4-II-E-C3 rat hepatoma cells with 25, 50, and 100 mM ethanol for various intervals of time up to 48 h. Human colonic adenocarcinoma cells (Caco-2 cells) and neonatal rat primary cardiomyocytes were also incubated with different concentrations of ethanol. Levels of TNF-R1 were measured either by a sandwich enzyme-linked immunosorbent assay (ELISA) method or by determining the extracellular transmembrane domain of TNF-R1 by an intact-cell ELISA method. Ethanol exposure for 48 h increased TNF-R1 levels in human hepatoma cells in a dose-dependent manner. Levels increased significantly by 164% at 50 mM and by 240% at 100 mM ethanol. Effects were time dependent and did not reach a plateau at 48 h. Similar increases in TNF-R1 were also observed in rat hepatoma cells (90% at 50 mM and 230% at 100 mM ethanol). Under similar conditions, Caco-2 cells showed a significant 80% increase in TNF-R1 levels at 200 mM ethanol, a concentration found in intestine. Neonatal rat primary cardiomyocytes showed TNF-R1 increases of 36% at 50 mM and 44% at 100 mM ethanol. These results indicate that exposure of different cell types to pharmacologic concentrations of ethanol increases TNF-R1 levels and may augment TNF-alpha-mediated cell injury in different tissues.

Immunocytochemical localization of TNF type 1 and type 2 receptors in the rat spinal cord

Tumor necrosis factor-alpha (TNF-alpha) is secreted in numerous pathophysiological situations by a variety of cell types. Tactile hypersensitivity (allodynia) is one component of a constellation of "illness behaviors" triggered by TNF-alpha. TNF-alpha is also implicated in neuropathic pain after peripheral nerve injury and apoptosis after spinal cord injury (SCI). It is possible that SCI, illness- and peripheral injury-induced hypersensitivity may share a similar spinal mediated etiology. These studies identify the locus of type-1 TNF (TNFR1 or p55) and type-2 TNF (TNFR2 or p75) receptors within the spinal cord. At all spinal levels, TNFR1 receptor immunoreactivity (TNFR1-ir) was constitutively expressed on cells and afferent fibers within the dorsal root ganglia, afferent fibers of the dorsal root, dorsal root entry zone (REZ) and within lamina I and II of the dorsal horn. Unilateral dorsal rhizotomy eliminated the characteristic pattern of TNFR1-ir at the rhizotomized REZ. In contrast, TNFR2-ir was consistently absent from dorsal root fibers and the region of the root entry zone. Consistent with our previous report, medullary afferent fibers in the solitary tract and spinal trigeminal tract labelled for TNF1-ir, but did not express TNFR2-ir. The presence TNFR1-ir on dorsal horn afferents, suggests that TNF-alpha may be a mechanism responsible for tactile hypersensitivity during illness. The presence of TNFR1 receptors, and perhaps their long-term activation or plasticity, may also play a critical role in the chronic allodynia and hyperreflexia observed after SCI or peripheral nerve damage.

[Intracellular and intercellular signal transduction pathways and age alterations of proliferative activity and apoptosis intensity in cells of immune system]

The paper considers age-associated alterations of intracellular and intercellular cascades of transduction of proliferative, differentiating, pro- and antiapoptotic signals, their interaction and influence on proliferative activity, differentiation and apoptosis of the immune system cells. One of initial causes of these alterations is accumulation with age of a growing number of antigens exposed on the surface of antigen-presenting cells. As a result of chronic antigenic stimulation, caused by this factor, an insufficient quantity or a slowed down appearance of growth factor receptors (in particular, IL-2 receptor) and costimulation molecules, primarily CD28, on T-cells membrane is observed. Because of this proliferative and antiapoptotic signals, received by T-cells, have a smaller intensity that predetermine reduction of their proliferative activity, and also activity of telomerase, and a greater susceptibility to apoptosis. Permanent activation of immune system is also reflected in age-related increase of expression of CD95 and type I tumour necrosis factor receptor by lymphocytes (that aggravates their susceptibility to apoptosis), and in intensification of proinflammatory cytokine synthesis. The second main cause of alterations in the immune system is an age-related decrease in the synthesis of growth factors that are necessary for cell survival and proliferation. In particular, because of the lack of IL-7, apoptosis intensity of maturing T-cells increases in thymus. Thymic stromal cells remain without contact signals and growth factors generated by lymphocytes, and also undergo apoptosis that causes further reduction of T-lymphopoiesis. Similar events also occur in bone marrow that predetermines age-related decrease in B-lymphopoiesis and in telomerase activity of haemopoietic stem cells, and also their proliferative potential reduction.

Cytokines and soluble tumour necrosis factor I receptor levels during pretransplant conditioning in allogeneic stem-cell transplantation

The inflammatory response induced by the conditioning regime may be related to the outcome in allogeneic stem-cell transplantation (SCT). However, previous statements concerning the prognostic significance of cytokine measurements during conditioning have not been conclusive. We investigated a broad range of cytokines in plasma samples drawn daily immediately before start of pretransplant conditioning and during the conditioning. The presented data indicate that single-day measurements of inflammatory cytokines during conditioning may lead to unreliable conclusions concerning their prognostic significance. However, serial quantitation of soluble tumour necrosis factor receptor I (sTNFRI) is more likely to reflect the degree of inflammatory activation induced by pretransplant conditioning.

Mechanisms of tumor vascular shutdown induced by 5,6-dimethylxanthenone-4-acetic acid (DMXAA): Increased tumor vascular permeability

The novel vascular targeting agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) has completed phase 1 clinical trial and has shown tumor antivascular activity in both mice and humans. We have investigated its ability to change tumor vascular permeability, relating it to tumor vascular perfusion and other responses. The murine colon 38 adenocarcinoma was grown in C57Bl wild-type mice and mice lacking expression of either tumor necrosis factor receptor-1 (TNFR1(-/-)) or TNF (TNF-/-). Tumor vascular permeability, as measured by extravasation of albumin-Evans Blue complexes 4 hr after DMXAA treatment, was significantly increased in tumor tissue in C57Bl, TNFR1-/- and TNF-/- mice but not in normal (skin) tissue. Significant linear relationships were found between increased tumor vascular permeability, decreased functioning tumor blood vessels (measured by Hoechst 33342 staining at 4 hr), increased plasma 5-hydroxyindole-3-acetic acid concentrations (as a measure of serotonin release by platelets) and the degree of induced tumor hemorrhagic necrosis. The results support the hypothesis that DMXAA increases tumor vascular permeability both directly and through the induction of other vasoactive mediators, including TNF. DMXAA might be useful clinically to potentiate the vascular permeability of other anticancer modalities such as cytotoxic drugs, antibodies, drug conjugates and gene therapy.

Cultured alveolar macrophages from patients with idiopathic pulmonary fibrosis (IPF) show dysregulation of lipopolysaccharide-induced tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) inductions

Regulation of the pulmonary host defence mechanism is crucial for protection of the lung without pathological consequences. This is exemplified in the normal lung by the induction of both the pro-inflammatory cytokine TNF-alpha, its receptors and the anti-inflammatory cytokine IL-10 by bacterial lipopolysaccharide (LPS). We have evaluated this mechanism in patients with idiopathic pulmonary fibrosis (IPF). Alveolar macrophages (AM) were obtained by bronchoalveolar lavage from 21 subjects with IPF and 12 healthy volunteers. Constitutive and LPS-stimulated AM production of TNF-alpha, TNF soluble receptors CD120a and CD120b, and IL-10 at the protein and mRNA level were measured by bioassay, ELISA and competitive PCR respectively. AM from IPF subjects were more susceptible to LPS induction of TNF-alpha protein (P = 0.03) and transcription of IL-10 mRNA (P = 0.01) and IL-10R1 (P = 0.01) expression in comparison to controls. In contrast, increased CD120b was present as protein and mRNA compared to controls (P = 0.02). AM from IPF subjects were at least as susceptible to down-regulation of LPS-induced TNF-alpha levels by exogenous IL-10 as normal controls (94% versus 63%). These data suggest that there is dysregulation of LPS-induced TNF-alpha and IL-10 in AM from IPF subjects. Further studies are required to elucidate these observations, which may, in turn, give additional insight into the pathogenesis of this disease.

[Production of soluble form of human TNF-alpha ligand-binding domain type 1 receptor by expression in Drosophila cells]

5His-tagged human TNFalpha type I receptor (TNFR1) ligand-binding domain was produced in Drosophila cells under control of metallothionein Cu-inducible promoter and purified by Ni-NTA affinity chromatography to homogeneity. TNFR1 gene fragment was cloned by PCR from CD8+ in vitro cultured T-killer normal linage cDNA. In despite of three disulfide bonds, the recombinant protein was correctly folded which was conformed by TNFalpha ligand binding assay in ELISA variant.

TNF receptor 1 is involved in the induction of apoptosis by the cyclin dependent kinase inhibitor p27Kip1 in the prostate cancer cell line PC-3

Loss of p27Kip1, a cyclin-dependent kinase inhibitor, is observed in aggressive prostate cancers. We demonstrated that intratumoral injections of recombinant adenovirus overexpressing p27Kip1 (Adp27) reduced the growth of prostate cancer xenografts in nude mice. Presently, we studied the mechanism(s) of cell death induced by Adp27 in prostate cancer cell line PC-3. Cells were infected with Adp27 and compared with those infected by empty virus or were non-infected. Cell cycle and typical markers of apoptosis were analyzed by flow cytometry in the presence of the following reagents: cycloheximide, pan-caspase inhibitor ZVAD-fmk, neutralizing anti-TNFR1, and anti-TNFR2. Overexpression of p27Kip1 protein and cell cycle arrest were noted within 24 h after Adp27-infection. Sub-G1 fraction, chromatin margination, and phosphatidylserine exposure were evident by the third day of treatment. Cycloheximide elevated sub-G1 fraction in Adp27-infected cells by threefold, while ZVAD-fmk reduced sub-G1 to control levels. Caspase-dependent apoptosis occurred in a third of the population, while two-thirds were ZVAD-fmk insensitive but TUNEL-positive. Flow cytometry showed increased expression of TNFR1 and TNFR2 in Adp27-infected cells. Neutralizing anti-TNFR1 decreased TUNEL-positive score, while anti-TNFR2 did not affect p27Kip1-induced apoptosis. This is the first report showing that p27Kip1 induces caspase-dependent and -independent stages of cell death that may involve TNF-signaling through TNFR1.