Safety, immunogenicity and effect on viral rebound of HTI vaccines in early treated HIV-1 infection: a randomized, placebo-controlled phase 1 trial

HIVACAT T-cell immunogen (HTI) is a novel human immunodeficiency virus (HIV) vaccine immunogen designed to elicit cellular immune responses to HIV targets associated with viral control in humans. The AELIX-002 trial was a randomized, placebo-controlled trial to evaluate as a primary objective the safety of a combination of DNA.HTI (D), MVA.HTI (M) and ChAdOx1.HTI (C) vaccines in 45 early-antiretroviral (ART)-treated individuals (44 men, 1 woman; NCT03204617). Secondary objectives included T-cell immunogenicity, the effect on viral rebound and the safety of an antiretroviral treatment interruption (ATI). Adverse events were mostly mild and transient. No related serious adverse events were observed. We show here that HTI vaccines were able to induce strong, polyfunctional and broad CD4 and CD8 T-cell responses. All participants experienced detectable viral rebound during ATI, and resumed ART when plasma HIV-1 viral load reached either >100,000 copies ml^-1, >10,000 copies ml^-1 for eight consecutive weeks, or after 24 weeks of ATI. In post-hoc analyses, HTI vaccines were associated with a prolonged time off ART in vaccinees without beneficial HLA (human leukocyte antigen) class I alleles. Plasma viral load at the end of ATI and time off ART positively correlated with vaccine-induced HTI-specific T-cell responses at ART cessation. Despite limited efficacy of the vaccines in preventing viral rebound, their ability to elicit robust T-cell responses towards HTI may be beneficial in combination cure strategies, which are currently being tested in clinical trials.

Two death pathways induced by sorafenib in myeloma cells: Puma-mediated apoptosis and necroptosis

PURPOSE

Sorafenib is a multikinase inhibitor that targets the MAPK pathway and is currently used for the treatment of hepatocellular and renal carcinoma. Recently, it has been shown that sorafenib is also cytotoxic to multiple myeloma (MM) cells. Here, we have further analyzed the mechanism of sorafenib-induced death in MM cells.

METHODS

Cell death induced by sorafenib in MM cell lines and in plasma cells from MM patients was evaluated by analysis of gene expression by RT-MLPA and quantitative PCR, protein levels and functionality by Western blot and flow cytometry and gene silencing with siRNA.

RESULTS

Cell death was characterized by phosphatidylserine exposure, ΔΨm loss, cytochrome c release and caspase activation, hallmarks of apoptosis. DL50 at 24 h ranged from 6 to 10 µM. Ex vivo treatment with 20 µM sorafenib induced apoptosis in around 80 % myeloma cells from six multiple myeloma patients. Sorafenib induced caspase-dependent degradation of Bcl-xL and Mcl-1 proteins, destabilizing the mitochondria and speeding up the development of apoptosis. Sorafenib treatment increased levels of Puma at mRNA and protein level and gene silencing with siRNA confirmed a relevant role for Puma in the induction of apoptosis. Co-treatment with the pan-caspase inhibitor Z-VAD-fmk prevented cell death to a variable degree depending on the cell line. In RPMI 8226 cells, Z-VAD-fmk prevented most of sorafenib-induced death. However, death in MM.1S was only prevented by co-incubation with both Z-VAD-fmk and the RIP1K inhibitor necrostatin-1, indicating that under conditions of inefficient caspase activation, sorafenib induces death by necroptosis.

CONCLUSION

Our results demonstrate a key role for Puma in the triggering of sorafenib-induced apoptosis and that this drug can also induce death by necroptosis in multiple myeloma cells.

Genetic polymorphisms and skin aging: the identification of population genotypic groups holds potential for personalized treatments

Introduction

Skin changes are among the most visible signs of aging. Skin properties such as hydration, elasticity, and antioxidant capacity play a key role in the skin aging process. Skin aging is a complex process influenced by heritable and environmental factors. Recent studies on twins have revealed that up to 60% of the skin aging variation between individuals can be attributed to genetic factors, while the remaining 40% is due to non-genetic factors. Recent advances in genomics and bioinformatics approaches have led to the association of certain single nucleotide polymorphisms (SNPs) to skin properties. Our aim was to classify individuals based on an ensemble of multiple polymorphisms associated with certain properties of the skin for providing personalized skin care and anti-aging therapies.

Methods and results

We identified the key proteins and SNPs associated with certain properties of the skin that contribute to skin aging. We selected a set of 13 SNPs in gene coding for these proteins which are potentially associated with skin aging. Finally, we classified a sample of 120 female volunteers into ten clusters exhibiting different skin properties according to their genotypic signature.

Conclusion

This is the first study that describes the actual frequency of genetic polymorphisms and their distribution in clusters involved in skin aging in a Caucasian population. Individuals can be divided into genetic clusters defined by genotypic variables. These genotypic variables are linked with polymorphisms in one or more genes associated with certain properties of the skin that contribute to a person’s perceived age. Therefore, by using this classification, it is possible to characterize human skin care and anti-aging needs on the basis of an individual’s genetic signature, thus opening the door to personalized treatments addressed at specific populations. This is part of an ongoing effort towards personalized anti-aging therapies combining genetic signatures with environmental and life style evaluations.

Methods for diagnosing perceived age on the basis of an ensemble of phenotypic features

BACKGROUND

Perceived age has been defined as the age that a person is visually estimated to be on the basis of physical appearance. In a society where a youthful appearance are an object of desire for consumers, and a source of commercial profit for cosmetic companies, this concept has a prominent role. In addition, perceived age is also an indicator of overall health status in elderly people, since old-looking people tend to show higher rates of morbidity and mortality. However, there is a lack of objective methods for quantifying perceived age.

METHODS

In order to satisfy the need of objective approaches for estimating perceived age, a novel algorithm was created. The novel algorithm uses supervised mathematical learning techniques and error retropropagation for the creation of an artificial neural network able to learn biophysical and clinically assessed parameters of subjects. The algorithm provides a consistent estimation of an individual's perceived age, taking into account a defined set of facial skin phenotypic traits, such as wrinkles and roughness, number of wrinkles, depth of wrinkles, and pigmentation. A nonintervention, epidemiological cross-sectional study of cases and controls was conducted in 120 female volunteers for the diagnosis of perceived age using this novel algorithm. Data collection was performed by clinical assessment of an expert panel and biophysical assessment using the ANTERA 3D(®) device.

RESULTS AND DISCUSSION

Employing phenotype data as variables and expert assignments as objective data, the algorithm was found to correctly classify the samples with an accuracy of 92.04%. Therefore, we have developed a method for determining the perceived age of a subject in a standardized, consistent manner. Further application of this algorithm is thus a promising approach for the testing and validation of cosmetic treatments and aesthetic surgery, and it also could be used as a screening method for general health status in the population.

Revealing the molecular relationship between type 2 diabetes and the metabolic changes induced by a very-low-carbohydrate low-fat ketogenic diet

Background

The prevalence of type 2 diabetes is increasing worldwide, accounting for 85-95% of all diagnosed cases of diabetes. Clinical trials provide evidence of benefits of low-carbohydrate ketogenic diets in terms of clinical outcomes on type 2 diabetes patients. However, the molecular events responsible for these improvements still remain unclear in spite of the high amount of knowledge on the primary mechanisms of both the diabetes and the metabolic state of ketosis. Molecular network analysis of conditions, diseases and treatments might provide new insights and help build a better understanding of clinical, metabolic and molecular relationships among physiological conditions. Accordingly, our aim is to reveal such a relationship between a ketogenic diet and type 2 diabetes through systems biology approaches.

Methods

Our systemic approach is based on the creation and analyses of the cell networks representing the metabolic state in a very-low-carbohydrate low-fat ketogenic diet. This global view might help identify unnoticed relationships often overlooked in molecule or process-centered studies.

Results

A strong relationship between the insulin resistance pathway and the ketosis main pathway was identified, providing a possible explanation for the improvement observed in clinical trials. Moreover, the map analyses permit the formulation of some hypothesis on functional relationships between the molecules involved in type 2 diabetes and induced ketosis, suggesting, for instance, a direct implication of glucose transporters or inflammatory processes. The molecular network analysis performed in the ketogenic-diet map, from the diabetes perspective, has provided insights on the potential mechanism of action, but also has opened new possibilities to study the applications of the ketogenic diet in other situations such as CNS or other metabolic dysfunctions.

What Do Spanish physicians believe and expect about telemedicine? Results of a Delphi-based survey

The aim of this Delphi-based study was to evaluate the intention of Spanish physicians to accept and use telemedicine as a future useful tool in daily practice. An online Delphi questionnaire was answered by 985 physicians (966 in the second round), representatives from rural and urban areas of the entire country (generalists, internists, cardiologists, endocrinologists, and nephrologists). The participants were 65% males, with a mean age of 46.7 years old and 20.3 years in the profession, mostly coming from primary care centers (91.8%) of urban Spanish areas (72.8%). Some responders (56.4%) reported lack of Internet use at work and 80.2% never participated in a telemedicine project, but 80.9% said they would be interested in participating in the future. As for the benefits of telemedicine, the specialties perceived as the most benefited were cardiology, followed by general medicine, pediatrics, and emergency services. The main reported difficulty for telemedicine implementation was the opinion that patients prefer the physical contact with physicians (77.8% of responders). Interviewed participants expressed strong interest in future telemedicine projects related to online training, distance control of chronic diseases, online communication among specialists, and real-time transmission of images and information. Most Spanish physicians have not implemented telemedicine in clinical practice, but they would be interested in future applications such as on-line training or disease control, although they still prefer physical patient contact.

Characterization of the lipolytic pathways that mediate free fatty acid release during Fas/CD95-induced apoptosis

We have undertaken a study to characterize the lipolytic pathway responsible for the generation of free fatty acids (FFA) during Fas/CD95-induced apoptosis in Jurkat cells. It was initially shown that the cellular lipid fraction that suffered the major quantitative decrease during Fas-induced apoptosis was that of phosphatidylcholine (PC). In addition, the secretion of palmitic acid-derived FFA was largely prevented by D609, an inhibitor of PC-specific phospholipase C (PC-PLC) and also by the diacylglycerol lipase (DAGL) inhibitor RHC-80267, suggesting that the secretion of these FFA during Fas-induced apoptosis is mediated by the generation of DAG by a PC-PLC activity and, sequentially, by a 1-DAGL activity which generates the FFA from its sn-1 position. The endocannabinoid 2-arachidonoyl glycerol (2-AG) should be generated as a sub-product of this pathway, but it did not accumulate inside the cells nor was secreted into the supernatant. Interestingly, the complete inhibition of free AA secretion during Fas-induced apoptosis was only achieved by using the AA trifluoromethylketone, which not only inhibits all types of phospholipase-A(2) (PLA(2)) activities, but also the described lytic activities on 2-AG. Using a combination of RHC-80267 and the iPLA(2)-specific inhibitor bromoenol lactone, it was shown that the DAGL pathway also cooperates with iPLA(2) in the generation of free arachidonate.

Towards a molecular characterisation of pathological pathways

The dominant conceptual reductionism in drug discovery has resulted in many promising drug candidates to fail during the last clinical phases, mainly due to a lack of knowledge about the patho-physiological pathways they are acting on. Consequently, to increase the revenues of the drug discovery process, we need to improve our understanding of the molecular mechanisms underlying complex cellular processes and consider each potential drug target in its full biological context. Here, we review several strategies that combine computational and experimental techniques, and suggest a systems pathology approach that will ultimately lead to a better comprehension of the molecular bases of disease.

Generation of rabbit antibodies against death ligands by cDNA immunization

Specificity problems, especially in immunoblot analysis, have been shown for several commercial antibodies raised against the death ligand Fas ligand (FasL) using conventional protein and/or peptide immunizations. In this work, we have optimized the development of rabbit antisera and isolated pAb against the death ligands FasL, Apo2 ligand/TRAIL and Apo3 ligand/TWEAK by cDNA intramuscular immunization. This alternative approach has generated specific pAb in all three cases, which are useful for immunoblot purposes. The present data suggest that for the production of antibodies against certain glycosylated membrane proteins, cDNA immunization could be the method of choice.

[Effectiveness of an intervention to provide information to patients with hypertension as short text messages and reminders sent to their mobile phone (HTA-Alert)]

OBJECTIVE

To analyze the effect of an intervention to provide information with mobile phone text messages to patients with hypertension on compliance with therapy for hypertension.

DESIGN

Comparative, controlled, multicenter, randomized cluster study.

SETTING

26 primary care health centers in Spain.

PARTICIPANTS

26 researchers were randomized to a control group or an intervention group (52 patients each, for a total of 104 patients). All patients were receiving monotherapy for uncontrolled hypertension.

INTERVENTION

Patients in the control group received their physician's usual interventions. Patients in the intervention group received messages and reminders sent to their mobile phones 2 days per week during 4 months.

MAIN OUTCOME MEASURES

Tablets were counted and blood pressure was measured at the start of the study and 1, 3, and 6 months later. The percentage of compliers, mean percentage of compliance and degree of control of hypertension were compared. The reduction in absolute and relative risk was calculated, as was the number of individuals needed to treat to avoid noncompliance.

RESULTS

The results were evaluated for a total of 67 individuals (34 in the intervention group and 33 in the control group). The rate of compliance was 85.1% (CI, 74.9%-95.3%) overall, 85.7% (CI, 70.5%-100.9%) in the control group and 84.4% in the intervention group (CI, 70.7%-95.3%) (P=NS). Mean percentage compliance was 90.2%+/-16.3% overall, 88.1%+/-20.8% in the control group and 91.9%+/-11.6% in the intervention group (P=NS). The percentage of patients whose hypertension was controlled at the end of the study was 51.5% (CI, 34.4%-68.6%) in the control group and 64.7% (CI, 48.6%-80.8%) in the intervention group (P=NS).

CONCLUSIONS

The telephone messaging intervention with alerts and reminders sent to mobile phones did not improve compliance with therapy in patients with hypertension.

Intrauterine growth retardation: study of placental apoptosis

We studied the rate of apoptosis in the placental tissue of pregnancies complicated with intrauterine growth retardation (IUGR) and compared it with the results obtained in normal placentas. Our results clearly demonstrate a strongly increased rate of apoptosis in placentas of children born with IUGR, suggesting severe placental dysfunction. The significance of these findings needs further study.

Increased mucosal tumour necrosis factor alpha production in Crohn's disease can be downregulated ex vivo by probiotic bacteria

BACKGROUND AND AIMS

Tumour necrosis factor alpha (TNF-alpha) plays a key role in the pathogenesis of intestinal inflammation in Crohn's disease. The effect of bacteria on TNF-alpha release by intestinal mucosa was investigated.

METHODS

Ileal specimens were obtained at surgery from 10 patients with Crohn's disease (ileal stricture) and five disease controls undergoing right hemicolectomy (caecal cancer). Mucosal explants from each specimen were cultured for 24 hours with either non-pathogenic Escherichia coli, Lactobacillus casei DN-114001, L bulgaricus LB10, or L crispatus (each study contained blank wells with no bacteria). Tissue and bacterial viability was confirmed by lactate dehydrogenase (LDH) release and culture. Concentrations of TNF-alpha were measured in supernatants and the phenotype of the intestinal lymphocytes was analysed by flow cytometry.

RESULTS

Coculture of mucosa with bacteria did not modify LDH release. Release of TNF-alpha by inflamed Crohn's disease mucosa was significantly reduced by coculture with L casei or L bulgaricus; changes induced by L crispatus or E coli were not significant. The effect of L casei and L bulgaricus was not prevented by protease inhibitors. Coculture with L casei and L bulgaricus reduced the number of CD4 cells as well as TNF-alpha expression among intraepithelial lymphocytes from Crohn's disease mucosa. None of the bacteria induced changes in non-inflamed mucosa.

CONCLUSIONS

Probiotics interact with immunocompetent cells using the mucosal interface and modulate locally the production of proinflammatory cytokines.

Role of caspases and apoptosis-inducing factor (AIF) in cladribine-induced apoptosis of B cell chronic lymphocytic leukemia

We have evaluated the role of caspases and the mitochondrial apoptosis inducing-factor (AIF) in apoptosis induced by cladribine (2CdA), in vitro, in cells from patients of B-CLL and in peripheral blood lymphocytes from normal donors. In sensitive B-CLL cells, apoptosis was characterized by cell shrinking, loss of mitochondrial membrane potential (DeltaPsi(m)), phosphatidylserine exposure, activation of caspases 3, 7, 8 and 9, reduction of Mcl-1 levels, translocation of AIF from mitochondria to nucleus and chromatin condensation. No significant variations in the levels of Bcl-2, Bax and Bak proteins were noticed upon treatment with 2CdA. Co-treatment of cells with the pan-caspase inhibitor Z-VAD-fmk attenuated some morphological and biochemical characteristics of apoptosis and delayed 2CdA-induced DeltaPsi(m) loss, but did not prevent cell death. Z-VAD-fmk did not prevent 2CdA-induced AIF translocation but in this case apoptotic cells displayed only peripheral chromatin condensation, characteristic of AIF action. Reduced or negligible caspase 3 expression did not prevent 2CdA toxicity in cells from four patients. Cells from three patients that responded poorly to 2CdA lacked expression of caspases 9 or 3. Cells from another patient resistant to 2CdA expressed caspases 3, 7, 8 and 9 but they were not activated by treatment. These results indicate that execution of apoptosis is carried out independently by AIF and caspases, which are responsible for the development of apoptotic phenotype in response to 2CdA. Although caspases can also collaborate in DeltaPsi(m) loss, proapoptotic proteins from the Bcl-2 superfamily may be the key inducers of DeltaPsi(m) loss and apoptosis in B-CLL cells sensitive to 2CdA.

Differential secretion of Fas ligand- or APO2 ligand/TNF-related apoptosis-inducing ligand-carrying microvesicles during activation-induced death of human T cells

Preformed Fas ligand (FasL) and APO2 ligand (APO2L)/TNF-related apoptosis-inducing ligand (TRAIL) are stored in the cytoplasm of the human Jurkat T cell line and of normal human T cell blasts. The rapid release of these molecules in their bioactive form is involved in activation-induced cell death. In this study, we show by confocal microscopy that FasL and APO2L/TRAIL are mainly localized in lysosomal-like compartments in these cells. We show also by immunoelectron microscopy that FasL and APO2L/TRAIL are stored inside cytoplasmic compartments approximately 500 nm in diameter, with characteristics of multivesicular bodies. Most of these compartments share FasL and APO2L/TRAIL, although exclusive APO2L/TRAIL labeling can be also observed in separate compartments. Upon PHA activation, the mobilization of these compartments toward the plasma membrane is evident, resulting in the secretion of the internal microvesicles loaded with FasL and APO2L/TRAIL. In the case of activation with anti-CD59 mAb, the secretion of microvesicles labeled preferentially with APO2L/TRAIL predominates. These data provide the basis of a new and efficient mechanism for the rapid induction of autocrine or paracrine cell death during immune regulation and could modify the interpretation of the role of FasL and APO2L/TRAIL as effector mechanisms in physiological and pathological situations.

Cladribine induces apoptosis in human leukaemia cells by caspase-dependent and -independent pathways acting on mitochondria

We have studied the role of caspases and mitochondria in apoptosis induced by 2-chloro-2'-deoxyadenosine (cladribine) in several human leukaemic cell lines. Cladribine treatment induced mitochondrial transmembrane potential (DeltaPsi(m)) loss, phosphatidylserine exposure, caspase activation and development of typical apoptotic morphology in JM1 (pre-B), Jurkat (T) and U937 (promonocytic) cells. Western-blot analysis of cell extracts revealed the activation of at least caspases 3, 6, 8 and 9. Co-treatment with Z-VAD-fmk (benzyloxy-carbonyl-Val-Ala-Asp-fluoromethylketone), a general caspase inhibitor, significantly prevented cladribine-induced death in JM1 and Jurkat cells for the first approximately 40 h, but not for longer times. Z-VAD-fmk also partly prevented some morphological and biochemical features of apoptosis in U937 cells, but not cell death. Co-incubation with selective caspase inhibitors Ac-DEVD-CHO (N-acetyl-Asp-Glu-Val-Asp-aldehyde), Ac-LEHD-CHO (N-acetyl-Leu-Glu-His-Asp-aldehyde) or Z-IETD-fmk (benzyloxycarbonyl-Ile-Glu-Thr-Asp-fluoromethylketone), inhibition of protein synthesis with cycloheximide or cell-cycle arrest with aphidicolin did not prevent cell death. Overexpression of Bcl-2, but not CrmA, efficiently prevented death in Jurkat cells. In all cell lines, death was always preceded by Delta Psi(m) loss and accompanied by the translocation of the protein apoptosis-inducing factor (AIF) from mitochondria to the nucleus. These results suggest that caspases are differentially involved in induction and execution of apoptosis depending on the leukaemic cell lineage. In any case, Delta Psi(m) loss marked the point of no return in apoptosis and may be caused by two different pathways, one caspase-dependent and the other caspase-independent. Execution of apoptosis was always performed after Delta Psi(m) loss by a caspase-9-triggered caspase cascade and the action of AIF.

A role of the mitochondrial apoptosis-inducing factor in granulysin-induced apoptosis

Granulysin is a cytolytic molecule released by CTL via granule-mediated exocytosis. In a previous study we showed that granulysin induced apoptosis using both caspase- and ceramide-dependent and -independent pathways. In the present study we further characterize the biochemical mechanism for granulysin-induced apoptosis of tumor cells. Granulysin-induced death is significantly inhibited by Bcl-2 overexpression and is associated with a rapid (1-5 h) loss of mitochondrial membrane potential, which is not mediated by ceramide generation and is not inhibited by the general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone. Ceramide generation induced by granulysin is a slow event, only observable at longer incubation times (12 h). Apoptosis induced by exogenous natural (C(18)) ceramide is truly associated with mitochondrial membrane potential loss, but contrary to granulysin, this event is inhibited by benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone. Ceramide-induced apoptosis is also completely prevented by Bcl-2 overexpression. The nuclear morphology of cells dying after granulysin treatment in the presence of caspase inhibitors suggested the involvement of mitochondrial apoptosis-inducing factor (AIF) in granulysin-induced cell death. We demonstrate using confocal microscopy that AIF is translocated from mitochondria to the nucleus during granulysin-induced apoptosis. The majority of Bcl-2 transfectants are protected from granulysin-induced cell death, mitochondrial membrane potential loss, and AIF translocation, while a small percentage are not protected. In this small percentage the typical nuclear apoptotic morphology is delayed, being of the AIF type at 5 h time, while at longer times (12 h) the normal apoptotic morphology is predominant. These and previous results support a key role for the mitochondrial pathway of apoptosis, and especially for AIF, during granulysin-induced tumoral cell death.

An ORF from Bacillus licheniformis encodes a putative DNA repressor

The complete sequence of a reading frame adjacent to the endo-beta-1,3-1,4-D-glucanase gene from Bacillus licheniformis is reported. It encodes a putative 171 amino acid residues protein with either, low significant sequence similarity in data banks or the corresponding orthologue in the recently sequenced Bacillus subtilis genome. Computer analyses predict a canonical Helix-Turn-Helix motif characteristic of bacterial repressors/DNA binding proteins. A maxicells assay shows that the encoded polypeptide is expressed. A DNA-protein binding, assay performed by gel electrophoresis shows that the expressed protein specifically binds to Bacillus licheniformis DNA.

[Patient assessment of the long-term benefits of surgery in inflammatory bowel disease]

The objective of surgical treatment in ulcerative colitis (UC) and Crohn's disease (CD) differs. Surgery in UC is more aggressive and potentially curative whereas in CD it is more conservative and palliative.

OBJECTIVE

To assess the opinion of patients with inflammatory bowel disease who underwent surgery in the distant past about the results and timing of surgery.

MATERIAL AND METHODS

A total of 50 surgical patients (36 with CD and 14 with UC) who had undergone an intestinal surgical procedure at least one year before. The clinical characteristics of patients and details of surgery procedures were recorded. Also, a personal interview was conducted. Patients were asked about their current clinical status, surgical consequences and their opinion about the appropriate timing of surgery.

RESULTS

Surgery for UC was total proctocolectomy in 85% of patients and it was on an emergency basis in 43% of them. Surgery for UC was partial intestinal or colonic resection, and it was on an emergency basis in 22% of them. Postsurgical complications were more common in UC than CD patients (50% versus 20%; p < 0.05). In CD surgery, recurrence of disease occurred in 78% of patients within a 2.6 years interval. Among UC and CD patients, 71% and 50%, respectively, reported that their presurgical expectatives had been fulfilled (p = 0.17).

CONCLUSIONS

Surgery for UC is associated with an appreciable rate of complications; however, most patients had their expectatives fulfilled with surgery as long-term symptoms were controlled. As for CD, the patient's satisfaction degree was lower than or UC.

Doxorubicin treatment activates a Z-VAD-sensitive caspase, which causes deltapsim loss, caspase-9 activity, and apoptosis in Jurkat cells

Doxorubicin induces caspase-3 activation and apoptosis in Jurkat cells but inhibition of this enzyme did not prevent cell death, suggesting that another caspase(s) is critically implicated. Western blot analysis of cell extracts indicated that caspases 2, 3, 4, 6, 7, 8, 9, and 10 were activated by doxorubicin. Cotreatment of cells with the caspase inhibitors Ac-DEVD-CHO, Z-VDVAD-fmk, Z-IETD-fmk, and Z-LEHD-fmk alone or in combination, or overexpression of CrmA, prevented many morphological features of apoptosis but not loss of mitochondrial membrane potential (delta(psi)m), phospatidilserine exposure, and cell death. Western blot analysis of cells treated with doxorubicin in the presence of inhibitors allowed elucidation of the sequential order of caspase activation. Z-IETD-fmk or Z-LEHD-fmk, which inhibit caspase-9 activity, blocked the activation of all caspases studied, lamin B degradation, and the development of apoptotic morphology, but not cell death. All morphological and biochemical features of apoptosis, as well as cell death, were prevented by cotreatment of cells with the general caspase inhibitor Z-VAD-fmk or by overexpression of Bcl-2. Doxorubicin cytotoxicity was also blocked by the protein synthesis inhibitor cycloheximide. Delayed addition of Z-VAD-fmk after doxorubicin treatment, but prior to the appearance of cells displaying a low delta(psi)m, prevented cell death. These results, taken together, suggest that the key mediator of doxorubicin-induced apoptosis in Jurkat cells may be an inducible, Z-VAD-sensitive caspase (caspase-X), which would cause delta(psi)m loss, release of apoptogenic factors from mitochondria, and cell death.

Tyrosine phosphorylation of the p85 subunit of phosphatidylinositol 3-kinase correlates with high proliferation rates in sublines derived from the Jurkat leukemia

A prominent tyrosine phosphorylated protein of 85 kDa (p85) was detected in highly proliferative sublines derived from the Jurkat T cell leukemia. We undertook a study to characterize the identity of this protein and its possible role in the hyperproliferative phenotypes observed. Using immunoblot and immunoprecipitation techniques, this protein was characterized as the p85 regulatory subunit of phosphatidylinositol 3-kinase. Cell proliferation and p85 tyrosine phosphorylation was not affected by tyrphostin AG-490, an inhibitor of Jak kinases, wortmannin or LY294002, inhibitors of the activity of the catalytic phosphatidylinositol 3-kinase subunit. Herbimycin-A and PPI, inhibitors of src-like protein tyrosine kinases, and genistein, a general tyrosine kinase inhibitor, inhibited p85 tyrosine phosphorylation and induced cell death in the sublines. PD98059, an inhibitor of Mek, inhibited cell growth of the sublines, but not that of the parental cells. It was concluded that tyrosine phosphorylation of p85 is associated with highly proliferative tumoral phenotypes, at least in T cell leukemias, independent of the phosphatidylinositol 3-kinase activity of the catalytic subunit.

CD59 cross-linking induces secretion of APO2 ligand in overactivated human T cells

Jurkat cells and the derived TCR / CD3-defective subline, J.RT3.T3.5 undergo activation induced cell death (AICD) when stimulated with phytohemagglutinin (PHA). Since J.RT3.T3.5 cells do not express antigen receptor, we searched for the molecules that could be ligated by PHA and induce AICD in this cell line. We show here that the glycosylphosphatidylinositol linked CD59 molecule is expressed at the surface of Jurkat and J.RT3.T3.5 cells, and when cross-linked by specific antibodies can induce cell death. The toxicity of supernatants from PHA-stimulated Jurkat or J.RT3.T3.5 cells was prevented by a combination of the blocking anti-Fas mAb SM1 / 23 and anti-APO2L / TRAIL mAb 5C2. However, toxicity of supernatants from anti-CD59 stimulated cells was specifically prevented by the anti-APO2L blocking antibody. Anti-CD59 cross-linking induced AICD also in normal human T cell blasts, which secreted toxic molecules into the supernatant. The toxicity of these supernatants on Jurkat cells was fully prevented by the anti-APO2L blocking antibody, showing that CD59 crosslinking induces the preferential release of APO2L also in normal T cells. The possible physiological and / or pathological consequences of this observation are discussed.

Activated human T cells release bioactive Fas ligand and APO2 ligand in microvesicles

Activation-induced cell death is a process by which overactivated T cells are eliminated, thus preventing potential autoimmune attacks. Two known mediators of activation-induced cell death are Fas(CD95) ligand (FasL) and APO2 ligand (APO2L)/TNF-related apoptosis-inducing ligand (TRAIL). We show here that upon mitogenic stimulation, bioactive FasL and APO2L are released from the T cell leukemia Jurkat and from normal human T cell blasts as intact, nonproteolyzed proteins associated with a particulate, ultracentrifugable fraction. We have characterized this fraction as microvesicles of 100-200 nm in diameter. These microvesicles are released from Jurkat and T cell blasts shortly (</=1 h) after PHA stimulation, well before the cell enters apoptosis. FasL- and APO2L-containing vesicles are also present in supernatants from PHA-activated fresh human PBMC. These observations provide the basis for a new and efficient mechanism for the rapid induction of autocrine or paracrine cell death during immune regulation.

Influence of the smoking habit in the surgery of inflammatory bowel disease

The smoking habit is a key factor in the development of inflammatory bowel disease (IBD), but little information exists as to the relationship between smoking habit, the need of surgery and its complications.

OBJECTIVES

To investigate the relationship between smoking habit, the need of surgery, their complications and clinical recurrence after surgery in Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

We studied a group of 62 patients (22 with UC and 40 with CD) with previous surgery. We analyzed the clinical and surgical characteristics of the disease. Smoking habit was established by a personal interview. This group of patients was compared with another control group of 202 patients (133 with UC and 69 with CD) with IBD without previous surgery.

RESULTS

Smoking habit was similar between operated and non-operated patients for both UC (73% and 80% non-smokers) and CD (67% and 63% smokers) The number and type of complications after surgery were not related with smoking habit. In CD patients, although the recurrences did not depend on the smoking habit, they did occur earlier in smokers than in non smokers (83.6 +/- 21 vs 155 +/- 50 weeks, p = ns).

CONCLUSIONS

The smoking habit does not seem to influence significantly the need of surgery and post surgical development of IBD, although in CD the smokers seems to present recurrence before non smokers.

Loss of delta6-desaturase activity leads to impaired docosahexaenoic acid synthesis in Y-79 retinoblastoma cells

We have studied the synthesis of docosahexaenoic acid (22:6 n-3) from linolenic acid (18:3 n-3) and eicosapentaenoic acid (20:5 n-3) in Y-79 human retinoblastoma cells and in a derived cell line, Y-79a, which has lost delta6-desaturase activity. Whereas Y-79 cells efficiently converted both radiolabeled 18:3 n-3 and 20:5 n-3 to 22:6 n-3, no synthesis of this fatty acid was observed in Y-79a cells from either 18:3 n-3 or 20:5 n-3. Y-79a cells elongated 18:3 n-3 to 20:3 n-3, which was further converted to 5,11,14,17-20:4 through a delta5-desaturation, elongated 20:5 n-3 to 22:5 n-3 and 24:5 n-3, and retained the ability for retroconversion. These results underscore the key role of delta6-desaturase in the synthesis of 22:6 n-3 and stress the importance of an adequate supply of this fatty acid in situations of reduced delta6-desaturase activity, such as in perinatal period, to prevent a 22:6 n-3 deficiency status.

Involvement of APO2 ligand/TRAIL in activation-induced death of Jurkat and human peripheral blood T cells

The interaction of Fas with Fas ligand (FasL) mediates activation-induced cell death (AICD) of T hybridomas and of mature T lymphocytes. The TNF/TNF receptor system also plays a significant role in AICD of mature T cells and in the maintenance of peripheral tolerance. We previously demonstrated that in human Jurkat leukemia cells, AICD is triggered mainly by the rapid release of preformed FasL upon TCR stimulation. In the present work, we show that the cytotoxic cytokine APO2 ligand (APO2L; also known as TRAIL) is constitutively expressed as an intracytoplasmic protein in Jurkat T cells and derived sublines. APO2L is also detected in fresh human peripheral blood mononuclear cells (PBMC) from a significant number of donors, and the amount of both FasL and APO2L substantially increases upon blast generation. A neutralizing anti-APO2L monoclonal antibody (mAb) partially suppresses the cytotoxicity induced by supernatants of phytohemagglutinin (PHA)-prestimulated Jurkat or human PBMC on non-activated Jurkat cells, indicating that APO2L is released by these cells and contributes to AICD. A combination of neutralizing anti-APO2L and anti-Fas mAb blocks around 60 % of the toxicity associated with supernatants from PHA-activated human PBMC. These results show that FasL and APO2L account for the majority of cytotoxic activity released during AICD, and suggest that additional uncharacterized factors may also contribute to this process.

Involvement of APO2 ligand/TRAIL in activation-induced death of Jurkat and human peripheral blood T cells

The interaction of Fas with Fas ligand (FasL) mediates activation-induced cell death (AICD) of T hybridomas and of mature T lymphocytes. The TNF/TNF receptor system also plays a significant role in AICD of mature T cells and in the maintenance of peripheral tolerance. We previously demonstrated that in human Jurkat leukemia cells, AICD is triggered mainly by the rapid release of preformed FasL upon TCR stimulation. In the present work, we show that the cytotoxic cytokine APO2 ligand (APO2L; also known as TRAIL) is constitutively expressed as an intracytoplasmic protein in Jurkat T cells and derived sublines. APO2L is also detected in fresh human peripheral blood mononuclear cells (PBMC) from a significant number of donors, and the amount of both FasL and APO2L substantially increases upon blast generation. A neutralizing anti-APO2L monoclonal antibody (mAb) partially suppresses the cytotoxicity induced by supernatants of phytohemagglutinin (PHA)-prestimulated Jurkat or human PBMC on non-activated Jurkat cells, indicating that APO2L is released by these cells and contributes to AICD. A combination of neutralizing anti-APO2L and anti-Fas mAb blocks around 60 % of the toxicity associated with supernatants from PHA-activated human PBMC. These results show that FasL and APO2L account for the majority of cytotoxic activity released during AICD, and suggest that additional uncharacterized factors may also contribute to this process.

Involvement of APO2 ligand/TRAIL in activation-induced death of Jurkat and human peripheral blood T cells

The interaction of Fas with Fas ligand (FasL) mediates activation-induced cell death (AICD) of T hybridomas and of mature T lymphocytes. The TNF/TNF receptor system also plays a significant role in AICD of mature T cells and in the maintenance of peripheral tolerance. We previously demonstrated that in human Jurkat leukemia cells, AICD is triggered mainly by the rapid release of preformed FasL upon TCR stimulation. In the present work, we show that the cytotoxic cytokine APO2 ligand (APO2L; also known as TRAIL) is constitutively expressed as an intracytoplasmic protein in Jurkat T cells and derived sublines. APO2L is also detected in fresh human peripheral blood mononuclear cells (PBMC) from a significant number of donors, and the amount of both FasL and APO2L substantially increases upon blast generation. A neutralizing anti-APO2L monoclonal antibody (mAb) partially suppresses the cytotoxicity induced by supernatants of phytohemagglutinin (PHA)-prestimulated Jurkat or human PBMC on non-activated Jurkat cells, indicating that APO2L is released by these cells and contributes to AICD. A combination of neutralizing anti-APO2L and anti-Fas mAb blocks around 60 % of the toxicity associated with supernatants from PHA-activated human PBMC. These results show that FasL and APO2L account for the majority of cytotoxic activity released during AICD, and suggest that additional uncharacterized factors may also contribute to this process.

Granulysin-induced apoptosis. I. Involvement of at least two distinct pathways

Granulysin is a newly described cytolytic molecule released by CTL and NK cells via granule-mediated exocytosis. It shares homology with saposin-like proteins, including NK-lysin and amoebapores, and has been implicated in the lysis of tumor cells and microbes. In the present study we show that recombinant granulysin alone induces apoptosis of Jurkat cells. This apoptosis is associated with a sixfold increase in the ceramide/sphingomyelin ratio, implicating the activation of sphingomyelinases. Granulysin- and ceramide-induced apoptosis are similar in that they both are only minimally inhibited by the more selective cysteine protease p32 (caspase 3)-like caspase inhibitor N-acetyl-Asp-Glu-Val-Asp aldehyde, while they are significantly inhibited by the more general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-fmk). Nevertheless, while Z-VAD-fmk almost completely inhibits ceramide-induced apoptosis, a Z-VAD-fmk-resistant component was observed using granulysin. Granulysin also causes apoptosis in cells depleted of sphingomyelin by prolonged treatment with the ceramide synthase inhibitor fumonisin B1. These data indicate that granulysin induces target cell death by both ceramide- and caspase-dependent and -independent pathways.

Caspases are the main executioners of Fas-mediated apoptosis, irrespective of the ceramide signalling pathway

Tumor necrosis factor alpha (TNF) or cytotoxic anti-Fas antibodies lead to the activation of apoptotic proteases (caspases) and to sphingomyelinase-mediated ceramide generation. Caspases and ceramide are both known to induce apoptosis on its own, but their relative contribution to Fas- and TNF-induced cell death is not well established. We report here that rapid apoptosis induced by TNF in U937 cells or anti-Fas in Jurkat cells, in the presence of cycloheximide, induced only a very low increase (<20%) in the cell ceramide content. Neither treatment with inhibitors of sphingomyelinases nor incubation of cells with fumonisin B1, which inhibits de novo ceramide synthesis, prevented TNF and Fas-mediated apoptosis. Increasing or depleting the cell ceramide content by prolonged culture in the presence of monensin or fumonisin B1, respectively, did not prevent TNF and Fas-mediated apoptosis. Treatment of cells with sphingomyelinase inhibitors did not affect to the activation of CPP32 (caspase-3) induced by TNF or anti-Fas antibodies. Chromatin condensation and fragmentation in cells treated with anti-Fas or TNF was abrogated by peptide inhibitors of caspases, which also inhibited Fas-, but not TNF-induced cell death. These results indicate that while ceramide does not seem to act as a critical mediator of TNF and Fas-induced apoptosis, it is generated as a consequence of CPP32 activation and could contribute to the spread of the intracellular death signal.

Resistance to apoptosis correlates with a highly proliferative phenotype and loss of Fas and CPP32 (caspase-3) expression in human leukemia cells

Apoptosis induced by effector cells of the immune system or by cytotoxic drugs is a main mechanism mediating the prevention or elimination of tumoral cells. For instance, the human T-cell leukemia Jurkat is sensitive to Fas-induced apoptosis and to activation-induced cell death (AICD), and the promonocytic leukemia U937 is sensitive to Fas- and TNF-induced apoptosis. In this work, we have analyzed the mechanisms of resistance to physiological or pharmacological apoptosis in human leukemia by generating highly proliferative (hp) sub-lines derived from Jurkat and U937 cells. These hp sub-lines were resistant to Fas- and TNF-induced apoptosis, as well as to AICD. This was due to the complete loss of Fas and TNFR surface expression and, in the case of Jurkat-derived sub-lines, also of CD3, CD2 and CD59 molecules. The sub-lines also completely lacked the expression of the apoptotic protease CPP32, present in parental cells. Moreover, these sub-lines were no longer sensitive to doxorubicin-induced apoptosis, which was efficiently blocked by the general caspase inhibitor Z-VAD-fmk in the parental cell lines. These data suggest a molecular mechanism for the development of resistance of leukemic cells to physiological and pharmacological apoptosis inducers, giving rise to highly proliferative tumoral phenotypes. These results also indicate that Fas and CPP32 could be useful prognostic markers for the progression and/or therapy outcome of human leukemias.

Doxorubicin-induced apoptosis in human T-cell leukemia is mediated by caspase-3 activation in a Fas-independent way

It has recently been proposed that doxorubicin (DOX) can induce apoptosis in human T-leukemia cells via the Fas/FasL system in an autocrine/paracrine way. We show here that treatment of Jurkat cells with either anti-Fas antibodies, anthracyclin drugs or actinomycin D induces the activation of CPP32 (caspase-3) and apoptosis. However, DOX treatment did not induce the expression of membrane FasL or the release of soluble FasL and co-incubation with blocking anti-Fas antibodies prevented Fas-induced but not DOX-induced apoptosis. All the morphological and biochemical signs of apoptosis induced by anti-Fas or DOX can be prevented by Z-VAD-fmk, a general caspase inhibitor. DEVD-cho, a specific inhibitor of CPP32-like caspases which completely blocks Fas-mediated apoptosis, prevented drug-induced nuclear apoptosis but not cell death. We conclude that: (i) DOX-induced apoptosis in human T-leukemia/lymphoma is Fas-independent and (ii) caspase-3 is responsible of DOX-induced nuclear apoptosis but other Z-VAD-sensitive caspases are implicated in cell death.

Implication of mitochondrial hydrogen peroxide generation in ceramide-induced apoptosis

The key events implicated in ceramide-triggered apoptosis remain unknown. In this study we show that 25 microM C6-ceramide induced significant H2O2 production within 60 min, which increased up to 180 min in human myeloid leukemia U937 cells. Inactive analogue dihydro-C6-ceramide had no effect. Furthermore, no H2O2 production was observed in C6-ceramide-treated U937 rho degrees cells, which are mitochondrial respiration-deficient. We also present evidence that ceramide-induced activation of the transcription factors NF-kappaB and AP-1 is mediated by mitochondrial derived reactive oxygen species. Both H2O2 production, transcription factor activation as well as apoptosis could be inhibited by rotenone and thenoyltrifluoroacetone (specific mitochondrial complexes I and II inhibitors) and antioxidants, N-acetylcysteine and pyrrolidine dithiocarbamate. These effects could be potentiated by antimycin A (specific complex III mitochondrial inhibitor). H2O2 production was also inhibitable by ruthenium red, suggesting a role of mitochondrial calcium homeostasis alterations in ceramide-induced oxidative stress. Finally, C6-ceramide had no influence on mitochondrial membrane potential within the first 6 h. Altogether, our study points to reactive oxygen species, generated at the ubiquinone site of the mitochondrial respiratory chain, as an early major mediator in ceramide-induced apoptosis.

Expression in Escherichia coli and purification of soluble forms of the F protein of bovine respiratory syncytial virus

Six fragments of the F gene from bovine respiratory syncytial virus (BRSV) were engineered into the pMAL-c2 Escherichia coli expression vector and expressed as C-terminal maltose-binding protein (MBP) fusion products. The resulting polypeptides were partially soluble and single-step purified by affinity chromatography. These fusion proteins were recognized in Western blots by several MAbs directed against human respiratory syncytial virus F protein. In addition, rabbit polyclonal antisera raised against two purified MBP-derived proteins reacted with the BRSV-F protein.

Inhibition of CPP32-like proteases prevents granzyme B- and Fas-, but not granzyme A-based cytotoxicity exerted by CTL clones

The perforin-facilitated entry of granzymes in target cells is a major mechanism used by CTL to induce cell death. It has been reported that granzyme B can cleave and activate the apoptotic cysteine protease p32 (CPP32)/Yama and its homologues in vitro. However, the mechanism for granzyme-based cytolysis exerted by intact CTL remains unclear. In the present work, we have used anti-CD3 mAb-redirected lysis of Fas-negative L1210 cells by CTL clones as a model to study perforin/granzyme-based cytotoxicity separately from the contribution of the Fas/Fas ligand system. N-acetyl-Asp-Glu-Val-Asp aldehyde (Ac-DEVD-CHO), a specific inhibitor of CPP32-like proteases, completely prevented the former type of lysis in 3-h assays, but not in long-term (16-h) assays. A combination of Ac-DEVD-CHO and the granzyme A inhibitor IGA (7-(phenyl-ureido)-4-chloro-3-(2-isothioureidoethoxy)-isocoumarin) inhibited long-term cytolysis. 3,4-Dichloroisocoumarin, a serine-protease inhibitor that efficiently inhibits granzyme B and poorly inhibits granzyme A, had similar effects as Ac-DEVD-CHO on anti-CD3 mAb-redirected lysis of L1210 cells. On the other hand, Fas-based cytolysis exerted by the same CTL clones on Fas-transfected L1210 cells (L1210Fas) was inhibited completely by Ac-DEVD-CHO, irrespective of the incubation time. These results suggest that granzyme B- and Fas-based cytotoxicity exerted by CTL clones converge at the level of CPP32-like protease activation, while granzyme A acts via a different, still undefined, pathway. We also demonstrate that perforin/granzyme-based cytolysis occurs without increase in the cellular ceramide content, ruling out the contribution of the sphingomyelinase pathway to this mechanism of cell death.

Inhibition of CPP32-like proteases prevents granzyme B- and Fas-, but not granzyme A-based cytotoxicity exerted by CTL clones

The perforin-facilitated entry of granzymes in target cells is a major mechanism used by CTL to induce cell death. It has been reported that granzyme B can cleave and activate the apoptotic cysteine protease p32 (CPP32)/Yama and its homologues in vitro. However, the mechanism for granzyme-based cytolysis exerted by intact CTL remains unclear. In the present work, we have used anti-CD3 mAb-redirected lysis of Fas-negative L1210 cells by CTL clones as a model to study perforin/granzyme-based cytotoxicity separately from the contribution of the Fas/Fas ligand system. N-acetyl-Asp-Glu-Val-Asp aldehyde (Ac-DEVD-CHO), a specific inhibitor of CPP32-like proteases, completely prevented the former type of lysis in 3-h assays, but not in long-term (16-h) assays. A combination of Ac-DEVD-CHO and the granzyme A inhibitor IGA (7-(phenyl-ureido)-4-chloro-3-(2-isothioureidoethoxy)-isocoumarin) inhibited long-term cytolysis. 3,4-Dichloroisocoumarin, a serine-protease inhibitor that efficiently inhibits granzyme B and poorly inhibits granzyme A, had similar effects as Ac-DEVD-CHO on anti-CD3 mAb-redirected lysis of L1210 cells. On the other hand, Fas-based cytolysis exerted by the same CTL clones on Fas-transfected L1210 cells (L1210Fas) was inhibited completely by Ac-DEVD-CHO, irrespective of the incubation time. These results suggest that granzyme B- and Fas-based cytotoxicity exerted by CTL clones converge at the level of CPP32-like protease activation, while granzyme A acts via a different, still undefined, pathway. We also demonstrate that perforin/granzyme-based cytolysis occurs without increase in the cellular ceramide content, ruling out the contribution of the sphingomyelinase pathway to this mechanism of cell death.

Fluorouracil and high-dose leucovorin with radiotherapy as adjuvant therapy for rectal cancer. Results of a phase II study

The purpose of this phase II study was to evaluate the efficacy and toxicity of fluorouracil and high-dose leucovorin (5-FU/LV) with pelvic irradiation as adjuvant therapy for patients with macroscopical resected rectal or recto-sigmoid cancer. Following surgery for stages II-III primary (52) or recurrent rectal cancer (4), 56 patients received 8 cycles of 5-FU/LV and pelvic irradiation. 5-FU doses were 200 mgr/m2 for cycles 2-3 and 300 mgr/m2 for cycles 1 and 4-8. LV doses remained fixed at 200 mgr/m2. Pelvic radiation was started in the third week, between the first and second cycle. The total dose was 50.4 Gy. No severe complications had been recorded. The incidence of grade 3 diarrhea was 19%. Three patients presented leukopenia grade 3 (5%). In 44 patients (78%) the planned treatment could be administered. The median follow-up was 40 months (range 22-66). Seven patients had a local relapse (13%) and 6 developed distant metastasis (10%). The 3-year disease-free survival was 72% and the overall survival was 76%. These preliminary results show that combined post-operative 5-FU/LV and pelvic radiotherapy are well tolerated and present a reasonable local control and survival rates. This adjuvant treatment should be evaluated in randomized trials.

Release of preformed Fas ligand in soluble form is the major factor for activation-induced death of Jurkat T cells

Interaction of Fas/APO-1 (CD95) and its ligand (FasL) plays an important role in the activation-induced cell death (AICD) of T lymphocytes. In the present work, the contribution of soluble FasL to AICD of the human T-cell line Jurkat has been studied. Jurkat cells prestimulated with phytohaemagglutinin (PHA) induced the death of non-activated Jurkat cells, and also of L1210Fas, but not that of Fas-negative L1210 cells. Culture supernatants from prestimulated Jurkat cells were highly toxic to their non-activated counterparts. Time-course analysis revealed that PHA-stimulated Jurkat cells quickly release (less than 15 min) to the medium a toxic molecule following a biphasic pattern, with maximal cytotoxic activities at 1 hr and 7 hr after stimulation. The cytotoxic effect of those supernatants was prevented by the addition of a blocking anti-Fas monoclonal antibody, suggesting that PHA-stimulated Jurkat cells exert Fas-based cytotoxicity mainly through the release of soluble FasL. The constitutive intracellular expression of FasL in non-activated Jurkat cells and its release as a consequence of PHA activation were detected by immunostaining and immunoblotting using an anti-FasL antibody. These data indicate that, at least in Jurkat cells, AICD is mainly mediated by the rapid release of performed FasL in soluble form upon stimulation.

Glycoprotein E of bovine herpesvirus type 1 is involved in virus transmission by direct cell-to-cell spread

In order to identify the role of the bovine herpesvirus type 1 (BHV-1) glycoprotein E (gE) in the viral infection cycle, we have constructed a BHV-1 gE deletion mutant strain (BHV-1 gE-). This strain was assayed in vitro by comparing its growth kinetics with the wild type strain used as a host of the deletion. Our results indicate that those conditions which prevent the infection by direct adsorption to the cells (presence of a semi-solid medium or presence of neutralizing antibodies in the medium) selectively inhibit the growth of the gE- strain, suggesting that gE plays a central role in the BHV-1 spread by direct cell-to-cell transmission, a major mechanism of the BHV-1 in vivo virulence.

CPP32 inhibition prevents Fas-induced ceramide generation and apoptosis in human cells

Intracellular activation of sphingomyelinase, leading to ceramide generation, and ICE-like proteases have been implicated in TNF and Fas-induced apoptosis, but the links between these intracellular apoptotic mediators remain undefined. We show here that a specific peptide inhibitor of the ICE-like protease CPP32/Yama (DEVD-CHO) blocks anti-Fas-induced apoptosis in Jurkat and U937 cells, while having no effect on TNF-induced apoptosis in U937 cells. This peptide also prevents ceramide accumulation induced by Fas engagement. Jurkat and U937 cells, as well as their mtDNA-depleted derived lines (rho degree cells), were sensitive to ceramide toxicity, which was not prevented by ICE-like protease inhibitors. These results, taken together, suggest that ICE-like protease activation is a prerequisite for ceramide generation and subsequent apoptosis, at least in the case of Fas-induced cell death.

Role of oxidative damage and IL-1 beta-converting enzyme-like proteases in Fas-based cytotoxicity exerted by effector T cells

The implication of oxidative damage and/or intact mitochondrial function in physiological Fas-based cytotoxicity has been tested using the cytolytic hybridoma d11S and the CD8(+) CTL clone KB5.C20, previously stimulated to express Fas ligand (FasL) on their surface, as effectors and U937 or U937-rho0 cells (depleted of mitochondrial DNA) as targets. Immobilized anti-Fas mAb, which induced death of U937 cells, inhibited the growth of U937-rho0 cells but without inducing cell death. By contrast, FasL-expressing effectors readily killed both targets, with induction of DNA fragmentation, in 20 h assays. These results demonstrate the lack of involvement of mitochondrial-derived free radicals and/or intact mitochondrial function in physiological Fas-based cytotoxicity. Supplementation of Fas-sensitive cells (Jurkat, U937, L1210Fas) with a polyunsaturated fatty acid, which induces cell death through the generation of lipid free radicals, resulted in the potentiation of Fas-based cytotoxicity. This potentiating effect, but not Fas-based cytotoxicity itself, was eliminated by the physiological antioxidant vitamin E. On the other hand, the IL-1beta-converting enzyme (ICE)-like protease tetrapeptide inhibitor Ac-YVAD-cmk partially inhibited Fas-based cytotoxicity, while the specific inhibitor of CPP32/Yama Ac-DEVD-CHO was a much more effective inhibitor of Fas-induced apoptosis. It was concluded that Fas-induced cytotoxicity was clearly dependent on ICE-like protease activation, and especially on that of CPP32 in Fas-sensitive cells, including mitochondrial DNA-depleted ones.

Biosynthesis of docosahexaenoic acid in human cells: evidence that two different delta 6-desaturase activities may exist

It has been proposed that synthesis of docosahexaenoic acid (22:6(n-3) in rat hepatocytes occurs by a route independent of delta 4-desaturase, which involves delta 6-desaturation and retroconversion (Voss A., Reinhart M., Sankarappa S. and Sprecher H. (1991) J. Biol. Chem. 266, 19995-20000). However, most cells exhibit these enzymatic activities and nevertheless synthesize low to undectectable amounts of 22:6(n-3). Moreover, there are few data on the occurrence of this pathway in human cells. In the present work, we have analysed the biosynthetic pathway of 22:6(n-3) in human Y-79 retinoblastoma and Jurkat T-cells. Y-79 cells were supplemented with 18:3(n-3) and 20:5(n-3) or incubated with [1-14C]18:3(n-3) and [1-14C]20:5(n-3) and lipids analysed by argentation TLC, reverse-phase TLC and GLC-mass spectrometry. Pulse-chase experiments revealed that synthesis of 22:6(n-3) from 20:5(n-3) in Y-79 cells occurred through two successive elongations, followed by a delta 6-desaturation of 24:5(n-3) to 24:6(n-3) and retroconversion to 22:6(n-3). Incubation of Y-79 cells with [1-14C]18:3(n-3) in medium containing 50 microM trans-9,12-18:2, a potent inhibitor of delta 6-desaturase, caused a reduction of 22:6(n-3) synthesis mainly by interfering with the desaturation of 18:3(n-3). However, when [1-14C]20:5(n-3) was used as precursor, synthesis of 22:6(n-3) was depressed to a lesser extent and mainly by reduction of 24:6(n-3) retroconversion. Neuronal differentiation of Y-79 cells caused a great increase in delta 6-desaturase activity on 18:3(n-3), though the amount of 22:6(n-3) synthesized did not change or diminish, suggesting the existence of a particular delta 6-desaturase involved in the synthesis of 22:6(n-3). The existence of a distinctive delta 6-desaturase activity could also explain why Jurkat cells growing in serum-free medium showed a near 3-fold increase in the synthesis of pentaenes from 18:3(n-3) and, at the same time, a large decrease in the synthesis of 22:6(n-3). The verification of the involvement of two delta 6-desaturase activities in 22:6(n-3) synthesis would have important implications for the formulation of the nutritional requirements of this fatty acid during development.

Apoptosis-associated derangement of mitochondrial function in cells lacking mitochondrial DNA

U937 cells lacking mitochondrial DNA (rho [symbol: see text] cells) are auxotrophic for uridine and pyruvate, hypersensitive to hypoglycemic conditions, and resistant to antimycin A-induced apoptosis. In spite of their obvious metabolic defects, rho [symbol: see text] cells possess a normal mitochondrial transmembrane potential, as well as near-normal capacity to generate superoxide anion after menadione treatment. Similarly to rho + controls, rho [symbol: see text] cells undergo apoptosis in response to tumor necrosis factor-alpha plus cycloheximide. Detailed comparison of the apoptotic process in rho + and rho [symbol: see text] cells reveals essentially the same sequence of events. In response to tumor necrosis factor/cycloheximide, cells first lose their mitochondrial transmembrane potential (delta psi m) and then manifest late apoptotic alterations, such as generation of reactive oxygen species and DNA fragmentation. Experiments involving isolated mitochondria from rho + and rho [symbol: see text] cells confirm that rho [symbol: see text] mitochondria can be induced to undergo permeability transition, a process thought to account for the pre-apoptotic delta psi m disruption in cells. Like rho + mitochondria, rho [symbol: see text] mitochondria contain a pre-formed soluble factor that is capable of inducing chromatin condensation in isolated nuclei in vitro. This factor is released from mitochondria upon induction of permeability transition by calcium or the specific ligand of the adenine nucleotide translocator atractyloside. In conclusion, it appears that all structures involved in the maintenance and pre-apoptotic disruption of the delta psi m, as well as a mitochondrial apoptotic factor(s), are present in rho [symbol: see text] cells and thus are controlled by the nuclear rather than by the mitochondrial genome. These findings underline the contribution of mitochondria to the apoptotic process.

mtDNA-depleted U937 cells are sensitive to TNF and Fas-mediated cytotoxicity

It has been proposed that TNF cytotoxicity is mediated by reactive oxygen intermediates generated by uncoupling of mitochondrial respiration. We have compared sensitive U937 cells and derived cell lines depleted of mtDNA for their ability to undergo TNF- and Fas-induced apoptosis. Cells lacking around 98% of mtDNA were still sensitive to TNF-induced apoptosis. U937 cells devoid of mtDNA (U937-rho degree) were resistant to TNF, but this was due to the loss of its 55 kDa receptor. U937-rho degree cells were also resistant to docosahexaenoic acid, which causes U937 cell death by lipid peroxidation. These cells were sensitive to anti-Fas toxicity. The results indicate that TNF and Fas-induced toxicity occurs by a mechanism mostly independent of mitochondrial free radical generation.

Biosynthesis of unsaturated fatty acids in the main cell lineages of human leukemia and lymphoma

Unsaturated fatty acids are essential for the proliferation of many haematopoietic cells, but little is known about their biosynthetic pathways in these cells. We have studied the activity of the main desaturation-elongation enzymes in human B-(Reh-6, Raji, Ramos) and T-(CEM, Jurkat) lymphocytic, promonocytic (U937), promyelocytic (HL-60) and pluripotent myeloid (K562) cell lineages, as well as the changes induced by cell differentiation. Cells were incubated with 14C-labelled 18:0, 18:2(n - 6) and 18:3(n - 3) or supplemented with the corresponding unlabelled fatty acid and synthesis of polyunsaturated fatty acids (PUFA) was evaluated by argentation-TLC and GLC. The main activity present in most cells was delta 9-desaturase (range between 200-1000 pmol/24 h per 10(6) cells) that was regulated by the type of free fatty acids in culture media. A great variability in the activities of delta 6- and delta 5-desaturase was observed. They were virtually absent in B-cells and only one (Jurkat) T-cell line synthesized significant amounts of (n - 6) and (n - 3) PUFA. The main PUFA formed by Jurkat cells were 20:3 and 20:4(n - 6) (30 and 40%, respectively, of cell lipid radioactivity) and 20:5, 22:5 and 22:6(n - 3) (60, 20 and 10%, respectively, of cell radioactivity). Cell differentiation caused complex changes in desaturase activities. The activity of delta 9-desaturase increased with the degree of differentiation of B-cells. Differentiation of U937 cells to macrophages with PMA caused a 2-3-fold increase in the activity of (delta 6 + delta 5)- and delta 9-desaturases and no changes and a 2-fold decrease, respectively, if the inducer was DMSO. Differentiation of HL-60 cells to granulocytes with DMSO virtually abolished delta 9-desaturase activity and greatly reduced that of delta 6- and delta 5-desaturases. delta 9-Desaturase activity increased (2.5-fold) in myeloid K562 cells differentiated to erythroblasts with hemin. No induction of delta 6-desaturase, absent in K562 cells, occurred after differentiation to erythroblasts or megakaryoblasts and they synthesized alternative PUFA through sequential elongation and delta 5-desaturation of 18:2(n - 6) and 18:3(n - 3). The activities of delta 6- and delta 5-desaturase in HL-60 and U937 cells increased when differentiation also stimulated the synthesis of eicosanoids and extracellular release of PUFA.

Mapping, cloning and sequencing of a glycoprotein-encoding gene from bovine herpesvirus type 1 homologous to the gE gene from HSV-1

In order to map and identify the glycoprotein-encoding gene from bovine herpesvirus type 1 (BHV-1), homologous to the gE glycoprotein from herpes simplex virus type 1 (HSV-1), a region of the unique short sequence from the BHV-1 genome has been sequenced. The sequenced region contains an ORF coding for a polypeptide of 575 amino acids (aa). The aa sequence presents substantial similarity to that of the glycoprotein gE from HSV-1 and to homologous proteins of related viruses such as pseudorabies virus, equine herpesvirus type 1 and varicella zoster virus. The aa sequence presents additional characteristics compatible with the structure of a viral glycoprotein: signal peptide, putative glycosylation sites and a long C-terminal transmembrane alpha-helix.

Expression of alpha-fetoprotein and interleukin 2 receptors and impairment of membrane fluidity in peripheral blood mononuclear cells from AIDS and related syndromes

We have previously shown that the expression of alpha-fetoprotein (AFP) receptors is impaired in mitogen-activated peripheral blood mononuclear cells (PBMCs) from HIV+ individuals and that this novel abnormality reflects an unusual proliferation response of PBMCs to mitogenic stimuli. Here we comparatively analyze, in PBMCs from patients with AIDS and related syndromes, (1) changes in membrane fluidity, measured as the cholesterol/phospholipid ratio (CH/PL), and (2) changes in the expression of AFP receptors and of the alpha chain of IL-2 receptor (TAC antigen). Relative to normal cells, the expression of AFP and IL-2 receptors appeared considerably reduced in AIDS-related complex (ARC) and AIDS patients. In asymptomatic HIV+ individuals the amount of AFP receptors was within the normal range, whereas that of IL-2 receptors increased twice. CH/PL ratios were significantly lower in PHA-activated than in quiescent PBMCs from healthy donors, which implies a gain in membrane fluidity. For seropositive groups, no statistically significant changes in CH/PL ratios were appreciated on PHA activation. Nevertheless, in HIV+ asymptomatic individuals, the CH/PL ratio of quiescent PBMCs resembled that of PHA-activated PBMCs from healthy donors, suggesting that quiescent PBMCs are in a partially activated or "preactivated" status. With the worsening of the disease, toward ARC and AIDS stages, however, quiescent PBMCs from these groups showed a considerable loss in membrane fluidity, evidenced by elevated values of the CH/PL ratio. This radical change strongly suggest a severe alteration of the lipid metabolism in these cells.(ABSTRACT TRUNCATED AT 250 WORDS)