Showing papers in "Nature Medicine in 1998"
TL;DR: It is demonstrated that new neurons, as defined by these markers, are generated from dividing progenitor cells in the dentate gyrus of adult humans, indicating that the human hippocampus retains its ability to generate neurons throughout life.
Abstract: The genesis of new cells, including neurons, in the adult human brain has not yet been demonstrated. This study was undertaken to investigate whether neurogenesis occurs in the adult human brain, in regions previously identified as neurogenic in adult rodents and monkeys. Human brain tissue was obtained postmortem from patients who had been treated with the thymidine analog, bromodeoxyuridine (BrdU), that labels DNA during the S phase. Using immunofluorescent labeling for BrdU and for one of the neuronal markers, NeuN, calbindin or neuron specific enolase (NSE), we demonstrate that new neurons, as defined by these markers, are generated from dividing progenitor cells in the dentate gyrus of adult humans. Our results further indicate that the human hippocampus retains its ability to generate neurons throughout life.
6,220 citations
TL;DR: In this paper, an array-based high-throughput technique that facilitates gene expression and copy number surveys of very large numbers of tumors is presented. But, it is limited to a single tumor tissue microarray.
Abstract: Many genes and signalling pathways controlling cell proliferation, death and differentiation, as well as genomic integrity, are involved in cancer development. New techniques, such as serial analysis of gene expression and cDNA microarrays, have enabled measurement of the expression of thousands of genes in a single experiment, revealing many new, potentially important cancer genes. These genome screening tools can comprehensively survey one tumor at a time; however, analysis of hundreds of specimens from patients in different stages of disease is needed to establish the diagnostic, prognostic and therapeutic importance of each of the emerging cancer gene candidates. Here we have developed an array-based high-throughput technique that facilitates gene expression and copy number surveys of very large numbers of tumors. As many as 1000 cylindrical tissue biopsies from individual tumors can be distributed in a single tumor tissue microarray. Sections of the microarray provide targets for parallel in situ detection of DNA, RNA and protein targets in each specimen on the array, and consecutive sections allow the rapid analysis of hundreds of molecular markers in the same set of specimens. Our detection of six gene amplifications as well as p53 and estrogen receptor expression in breast cancer demonstrates the power of this technique for defining new subgroups of tumors.
4,164 citations
TL;DR: Vaccination with autologous DCs generated from peripheral blood is a safe and promising approach in the treatment of metastatic melanoma and antigen-specific immunity was induced during DC vaccination.
Abstract: Melanoma is the main cause of death in patients with skin cancer1. Cytotoxic T lymphocytes (CTLs) attack melanoma cells in an HLA-restricted and tumor antigen-specific manner. Several melanoma-associated tumor antigens have been identified2. These antigens are suitable candidates for a vaccination therapy of melanoma. Dendritic cells (DCs) are antigen-presenting cells (APCs) specialized for the induction of a primary T-cell response3. Mouse studies have demonstrated the potent capacity of DCs to induce antitu-mor immunity4–11. In the present clinical pilot study, DCs were generated in the presence of granulocyte/macrophage-colony stimulating factor (GM-CSF) and interleukin 4 (IL-4) and were pulsed with tumor lysate or a cocktail of peptides known to be recognized by CTLs, depending on the patient's HLA haplotype. Keyhole limpet hemocyanin (KLH) was added as a CD4 helper antigen and immunological tracer molecule. Sixteen patients with advanced melanoma were immunized on an outpatient basis. Vaccination was well tolerated. No physical sign of autoimmunity was detected in any of the patients. DC vaccination induced de-layed-type hypersensitivity (DTH) reactivity toward KLH in all patients, as well as a positive DTH reaction to peptide-pulsed DCs in 11 patients. Recruitment of peptide-specific CTLs to the DTH challenge site was also demonstrated. Therefore, antigen-specific immunity was induced during DC vaccination. Objective responses were evident in 5 out of 16 evaluated patients (two complete responses, three partial responses) with regression of metastases in various organs (skin, soft tissue, lung, pancreas) and one additional minor response. These data indicate that vaccination with autologous DCs generated from peripheral blood is a safe and promising approach in the treatment of metastatic melanoma. Further studies are necessary to demonstrate clinical effectiveness and impact on the survival of melanoma patients.
2,993 citations
TL;DR: Dendritic cells are shown to secrete antigen presenting vesicles, called exosomes, which express functional Major Histocompatibility Complex class I and class II, and T-cell costimulatory molecules, which prime specific cytotoxic T lymphocytes in vivo.
Abstract: Dendritic cells (DCs) are professional antigen presenting cells with the unique capacity to induce primary and secondary immune responses in vivo. Here, we show that DCs secrete antigen presenting vesicles, called exosomes, which express functional Major Histocompatibility Complex class I and class II, and T-cell costimulatory molecules. Tumor peptide-pulsed DC-derived exosomes prime specific cytotoxic T lymphocytes in vivo and eradicate or suppress growth of established murine tumors in a T cell-dependent manner. Exosome-based cell-free vaccines represent an alternative to DC adoptive therapy for suppressing tumor growth.
2,012 citations
TL;DR: A synthetic peptide, designed to increase binding to HLA-A2 molecules, was used as a cancer vaccine to treat patients with metastatic melanoma and, on the basis of immunologic assays, 91% of patients could be successfully immunized with this peptide.
Abstract: The cloning of the genes encoding cancer antigens has opened new possibilities for the treatment of patients with cancer. In this study, immunodominant peptides from the gp100 melanoma-associated antigen were identified, and a synthetic peptide, designed to increase binding to HLA-A2 molecules, was used as a cancer vaccine to treat patients with metastatic melanoma. On the basis of immunologic assays, 91% of patients could be successfully immunized with this synthetic peptide, and 13 of 31 patients (42%) receiving the peptide vaccine plus IL-2 had objective cancer responses, and four additional patients had mixed or minor responses. Synthetic peptide vaccines based on the genes encoding cancer antigens hold promise for the development of novel cancer immunotherapies.
1,842 citations
TL;DR: The authors discuss the Global Burden of Disease Study and its role in setting priorities for improving international public health into the next century*, as well as highlighting the need to understand more fully the determinants of death and disease.
Abstract: The authors discuss the Global Burden of Disease Study and its role in setting priorities for improving international public health into the next century
*
.
1,555 citations
TL;DR: It is demonstrated that at higher concentrations, Lewy body-like fibrils and discrete spherical assemblies are formed; most rapidly by A53T, suggesting mutation-induced acceleration of α-synuclein fibril formation may contribute to the early onset of familial PD.
Abstract: Accelerated in vitro fibril formation by a mutant α-synuclein
linked to early-onset Parkinson disease
1,488 citations
TL;DR: The development of AD-like pathology is substantially enhanced when a P51 mutation, which causes a modest increase in Aβ42(43), is introduced into Tg2576-derived mice, and both doubly and singly transgenic mice showed reduced spontaneous alternation performance in a “Y” maze before substantial Aβ deposition was apparent.
Abstract: Genetic causes of Alzheimer's disease (AD) include mutations in the amyloid precursor protein (APP), presenilin 1 (PS1), and presenilin 2 (P52) genes1. The mutant APPK670N,M67M transgenic line, Tg2576, shows markedly elevated amyloid β-protein (AP) levels at an early age and, by 9–12 months, develops extracellular AD-type Ap deposits in the cortex and hippocampus2. Mutant PS1 transgenic mice do not show abnormal pathology, but do display subtly elevated levels of the highly amyloidogenic 42- or 43-amino acid peptide Aβ342(43) (ref. 3). Here we demonstrate that the doubly transgenic progeny from a cross between line Tg2576 and a mutant PS1M46L transgenic line develop large numbers of fibrillar Aβ deposits in cerebral cortex and hippocampus far earlier than their singly transgenic Tg2576 litter-mates. In the period preceding overt Aβ deposition, the doubly transgenic mice show a selective 41% increase in Aβ42(43) in their brains. Thus, the development of AD-like pathology is substantially enhanced when a P51 mutation, which causes a modest increase in Aβ42(43), is introduced into Tg2576-derived mice. Remarkably, both doubly and singly transgenic mice showed reduced spontaneous alternation performance in a “Y” maze before substantial Aβ deposition was apparent. This suggests that some aspects of the behavioral phenotype in these mice may be related to an event that precedes plaque formation.
1,410 citations
TL;DR: It is indicated that each of the eight prion strains has a PrP sc molecule with a unique conformation and that the variation in incubation times is related to the relative protease sensitivity of PrPSc in each strain.
Abstract: Variations in prions, which cause different incubation times and deposition patterns of the prion protein isoform called PrP
Sc
, are often referred to as 'strains'. We report here a highly sensitive, conformation-dependent immunoassay that discriminates PrP
Sc
molecules among eight different prion strains propagated in Syrian hamsters. This immunoassay quantifies PrP isoforms by simultaneously following antibody binding to the denatured and native forms of a protein. In a plot of the ratio of antibody binding to denatured/native PrP graphed as a function of the concentration of PrP
Sc
, each strain occupies a unique position, indicative of a particular PrP
Sc
conformation. This conclusion is supported by a unique pattern of equilibrium unfolding of PrP
Sc
found with each strain. Our findings indicate that each of the eight prion strains has a PrP
Sc
molecule with a unique conformation and, in accordance with earlier results, indicate the biological properties of prion strains are 'enciphered' in the conformation of PrP
Sc
and that the variation in incubation times is related to the relative protease sensitivity of PrP
Sc
in each strain.
1,265 citations
TL;DR: It is indicated that the HCV core protein has a chief role in the development of HCC, and that these transgenic mice provide good animal models for determining the molecular events in hepatocarcinogenesis with HCV infection.
Abstract: Hepatitis C virus (HCV) is the main cause of chronic hepatitis worldwide Chronic hepatitis ultimately results in the development of hepatocellular carcinoma (HCC) However, the mechanism of hepatocarcinogenesis in chronic HCV infection is still unclear The ability of the core protein of HCV to modulate gene transcription, cell proliferation and cell death may be involved in the pathogenesis of HCC Here, we report the development of HCC in two independent lines of mice transgenic for the HCV core gene, which develop hepatic steatosis early in life as a histological feature characteristic of chronic hepatitis C After the age of 16 months, mice of both lines developed hepatic tumors that first appeared as adenomas containing fat droplets in the cytoplasm Then HCC, a more poorly-differentiated neoplasia, developed from within the adenomas, presenting in a 'nodule-in-nodule' manner without cytoplasmic fat droplets; this closely resembled the histopathological characteristics of the early stage of HCC in patients with chronic hepatitis C These results indicate that the HCV core protein has a chief role in the development of HCC, and that these transgenic mice provide good animal models for determining the molecular events in hepatocarcinogenesis with HCV infection
1,199 citations
TL;DR: [F-18]FLT (3'-deoxy-3'-fluorothymidine) is developed and tested; it is resistant to degradation, is retained in proliferating tissues by the action of thymidine kinase 1 (TK), and produces high-contrast images of normal marrow and tumors in canine and human subjects.
Abstract: Positron emission tomography (PET) is now regularly used in the diagnosis and staging of cancer. These uses and its ability to monitor treatment response would be aided by the development of imaging agents that can be used to measure tissue and tumor proliferation. We have developed and tested [F-18]FLT (3'-deoxy-3'-fluorothymidine); it is resistant to degradation, is retained in proliferating tissues by the action of thymidine kinase 1 (TK), and produces high-contrast images of normal marrow and tumors in canine and human subjects.
TL;DR: In rabbits in which myoblasts were incorporated, myocardial performance was improved and the ability to regeneratefunctioning muscle after autologous myoblast transplantation could have a important effect on patients after acuteMyocardial infarction.
Abstract: The adult heart lacks reserve cardiocytes and cannot regenerate. Therefore, a large acute myocardial infarction often develops into congestive heart failure. To attempt to prevent this progression, we transplanted skeletal myoblasts into cryoinfarcted myocardium of the same rabbits (autologous transfer), monitored cardiac function in vivo for two to six weeks and examined serial sections of the hearts by light and electron microscopy. Islands of different sizes comprising elongated, striated cells that retained characteristics of both skeletal and cardiac cells were found in the cryoinfarct. In rabbits in which myoblasts were incorporated, myocardial performance was improved. The ability to regenerate functioning muscle after autologous myoblast transplantation could have a important effect on patients after acute myocardial infarction.
TL;DR: Evidence is provided for a new role of Transglutaminase in the common, HLA-DQ2 (and DQ8) associated celiac disease and it is demonstrated that TGase mediates its effect through an ordered and specific deamidation of gliadins.
Abstract: The action of tissue Transglutaminase (TGase) on specific protein-bound glutamine residues plays a critical role in numerous biological processes. Here we provide evidence for a new role of this enzyme in the common, HLA-DQ2 (and DQ8) associated enteropathy, celiac disease (CD). The intestinal inflammation in CD is precipitated by exposure to wheat gliadin in the diet and is associated with increased mucosal activity of TGase. This enzyme has also been identified as the main target for CD-associated anti-endomysium autoantibodies, and is known to accept gliadin as one of its few substrates. We have examined the possibility that TGase could be involved in modulating the reactivity of gliadin specific T cells. This could establish a link between previous reports of the role of TGase in CD and the prevailing view of CD as a T-cell mediated disorder. We found a specific effect of TGase on T-cell recognition of gliadin. This effect was limited to gliadin-specific T cells isolated from intestinal CD lesions. We demonstrate that TGase mediates its effect through an ordered and specific deamidation of gliadins. This deamidation creates an epitope that binds efficiently to DQ2 and is recognized by gut-derived T cells. Generation of epitopes by enzymatic modification is a new mechanism that may be relevant for breaking of tolerance and initiation of autoimmune disease.
TL;DR: Findings indicate interaction between the advanced glycation endproducts and their receptor is involved in the development of accelerated atherosclerosis in diabetes, and identify this receptor as a new therapeutic target in diabetic macrovascular disease.
Abstract: Accelerated atherosclerosis in patients with diabetes is a major cause of their morbidity and mortality, and it is unresponsive to therapy aimed at restoring relative euglycemia. In hyperglycemia, nonenzymatic glycation and oxidation of proteins and lipids results in the accumulation of irreversibly formed advanced glycation endproducts. These advanced glycation endproducts engage their receptor in cells of the blood vessel wall, thereby activating mechanisms linked to the development of vascular lesions. We report here a model of accelerated and advanced atherosclerosis in diabetic mice deficient for apolipoprotein E. Treatment of these mice with the soluble extracellular domain of the receptor for advanced glycation endproducts completely suppressed diabetic atherosclerosis in a glycemia- and lipid-independent manner. These findings indicate interaction between the advanced glycation endproducts and their receptor is involved in the development of accelerated atherosclerosis in diabetes, and identify this receptor as a new therapeutic target in diabetic macrovascular disease.
TL;DR: Proof-of-concept that viral entry can be successfully blocked in vivo is provided, and short-term administration of T-20 seems safe and provides potent inhibition of HIV replication comparable to anti-retroviral regimens approved at present.
Abstract: T-20, a synthetic peptide corresponding to a region of the transmembrane subunit of the HIV-1 envelope protein, blocks cell fusion and viral entry at concentrations of less than 2 ng/ml in vitro. We administered intravenous T-20 (monotherapy) for 14 days to sixteen HIV-infected adults in four dose groups (3, 10, 30 and 100 mg twice daily). There were significant, dose-related declines in plasma HIV RNA in all subjects who received higher dose levels. All four subjects receiving 100 mg twice daily had a decline in plasma HIV RNA to less than 500 copies/ml, by bDNA assay. A sensitive RT-PCR assay (detection threshold 40 copies/ml) demonstrated that, although undetectable levels were not achieved in the 14-day dosing period, there was a 1.96 log10 median decline in plasma HIV RNA in these subjects. This study provides proof-of-concept that viral entry can be successfully blocked in vivo. Short-term administration of T-20 seems safe and provides potent inhibition of HIV replication comparable to anti-retroviral regimens approved at present.
TL;DR: Transduction of full-length TAT fusion proteins into mammalian cells: TAT-p27 Kip1 induces cell migration and promotes cell migration in mice.
Abstract: Transduction of full-length TAT fusion proteins into mammalian cells:
TAT-p27 Kip1 induces cell migration
TL;DR: It is shown that PPARγ is expressed at high levels in both well- and poorly-differentiated adenocarcinomas, in normal colonic mucosa and in human colon cancer cell lines, indicating that the growth and differentiation of colon cancer cells can be modulated through PPARβ.
Abstract: PPARgamma is a nuclear receptor that has a dominant regulatory role in differentiation of cells of the adipose lineage, and has recently been shown to be expressed in the colon. We show here that PPARgamma is expressed at high levels in both well- and poorly-differentiated adenocarcinomas, in normal colonic mucosa and in human colon cancer cell lines. Ligand activation of this receptor in colon cancer cells causes a considerable reduction in linear and clonogenic growth, increased expression of carcinoembryonic antigen and the reversal of many gene expression events specifically associated with colon cancer. Transplantable tumors derived from human colon cancer cells show a significant reduction of growth when mice are treated with troglitazone, a PPARgamma ligand. These results indicate that the growth and differentiation of colon cancer cells can be modulated through PPARgamma.
TL;DR: A 5-residue peptide is demonstrated that inhibits amyloid βprotein fibrillogenesis, disassembles preformed fibrils in vitro and prevents neuronal death induced by fibrILS in cell culture and may provide the basis for a new therapeutic approach to prevent amyloidsosis in Alzheimer's disease.
Abstract: Inhibition of cerebral amyloid beta-protein deposition seems to be an important target for Alzheimer's disease therapy. Amyloidogenesis could be inhibited by short synthetic peptides designed as beta-sheet breakers. Here we demonstrate a 5-residue peptide that inhibits amyloid beta-protein fibrillogenesis, disassembles preformed fibrils in vitro and prevents neuronal death induced by fibrils in cell culture. In addition, the beta-sheet breaker peptide significantly reduces amyloid beta-protein deposition in vivo and completely blocks the formation of amyloid fibrils in a rat brain model of amyloidosis. These findings may provide the basis for a new therapeutic approach to prevent amyloidosis in Alzheimer's disease.
TL;DR: A novel approach to detecting angiogenesis in vivo using magnetic resonance imaging (MRI) and a paramagnetic contrast agent targeted to endothelial αvβ3 via the LM609 monoclonal antibody is described.
Abstract: Angiogenesis, the formation of new blood vessels, is a requirement for malignant tumor growth and metastasis. In the absence of angiogenesis, local tumor expansion is suppressed at a few millimeters and cells lack routes for distant hematogenous spread. Clinical studies have demonstrated that the degree of angiogenesis is correlated with the malignant potential of several cancers, including breast cancer and malignant melanoma. Moreover, the expression of a specific angiogenesis marker, the endothelial integrin alphaVbeta3, has been shown to correlate with tumor grade. However, studies of tumor angiogenesis such as these have generally relied on invasive procedures, adequate tissue sampling and meticulous estimation of histologic microvessel density. In the present report, we describe a novel approach to detecting angiogenesis in vivo using magnetic resonance imaging (MRI) and a paramagnetic contrast agent targeted to endothelial alphaVbeta3 via the LM609 monoclonal antibody. This approach provided enhanced and detailed imaging of rabbit carcinomas by directly targeting paramagnetic agents to the angiogenic vasculature. In addition, angiogenic 'hot spots' not seen by standard MRI were detected. Our strategy for MR imaging of alphaVbeta3 thus represents a non-invasive means to assess the growth and malignant phenotype of tumors.
TL;DR: In recovered rats, re-transection of the cord above the primary transection site led to loss of recovery, indicating the involvement of long descending spinal tracts, and injection of macrophages into the site of injury is relatively non-invasive and, as the cells are autologous, it may be developed into a clinical therapy.
Abstract: Postinjury recovery in most tissues requires an effective dialog with macrophages; however, in the mammalian central nervous system, this dialog may be restricted (possibly due to its immune-privileged status), which probably contributes to its regeneration failure We circumvented this by implanting macrophages, pre-exposed ex vivo to peripheral nerve segments, into transected rat spinal cord This stimulated tissue repair and partial recovery of motor function, manifested behaviorally by movement of hind limbs, plantar placement of the paws and weight support, and electrophysiologically by cortically evoked hind-limb muscle response We substantiated these findings immunohistochemically by demonstrating continuity of labeled nerve fibers across the transected site, and by tracing descending fibers distally to it by anterograde labeling In recovered rats, re-transection of the cord above the primary transection site led to loss of recovery, indicating the involvement of long descending spinal tracts Injection of macrophages into the site of injury is relatively non-invasive and, as the cells are autologous, it may be developed into a clinical therapy
TL;DR: The bicyclam AMD3100 blocks HIV-1 entry and membrane fusion via the CXCR4 co-receptor, but not via CCR5, and development of small molecule inhibitors of HIV- 1 entry is feasible.
Abstract: The bicyclam AMD3100 (formula weight 830) blocks HIV-1 entry and membrane fusion via the CXCR4 co-receptor, but not via CCR5. AMD3100 prevents monoclonal antibody 12G5 from binding to CXCR4, but has no effect on binding of monoclonal antibody 2D7 to CCR5. It also inhibits binding of the CXC-chemokine, SDF-1alpha, to CXCR4 and subsequent signal transduction, but does not itself cause signaling and has no effect on RANTES signaling via CCR5. Thus, AMD3100 prevents CXCR4 functioning as both a HIV-1 co-receptor and a CXC-chemokine receptor. Development of small molecule inhibitors of HIV-1 entry is feasible.
TL;DR: Combining patch-clamp recording and single-cell mRNA amplification (aRNA) techniques in single dentate granule cells, it is demonstrated that expression of GABAA receptor subunit mRNAs is substantially altered in neurons from epileptic rats, indicating that aberrant GAB AA receptor expression and function has an essential role in the process of epileptogenesis.
Abstract: Temporal lobe epilepsy is the most prevalent seizure disorder in adults. Compromised inhibitory neurotransmitter function in the hippocampus contributes to the hyperexcitability generating this condition, but the underlying molecular mechanisms are unknown. Combining patch-clamp recording and single-cell mRNA amplification (aRNA) techniques in single dentate granule cells, we demonstrate that expression of GABAA receptor subunit mRNAs is substantially altered in neurons from epileptic rats. These changes in gene expression precede epilepsy onset by weeks and correlate with profound alterations in receptor function, indicating that aberrant GABAA re- ceptor expression and function has an essential role in the process of epileptogenesis.
TL;DR: It is shown, using mathematical modeling, that redistribution of T cells to the blood can explain the striking correlation between the initial CD4+ and CD8+ memory T-cell repopulation and the observation that 3 weeks after the start of treatment memory CD4-cell numbers reach a plateau.
Abstract: The origin of CD4+ T cells reappearing in the blood following antiretroviral therapy in human immunodeficiency virus type-1 (HIV-1) infection is still controversial. Here we show, using mathematical modeling, that redistribution of T cells to the blood can explain the striking correlation between the initial CD4+ and CD8+ memory T-cell repopulation and the observation that 3 weeks after the start of treatment memory CD4+ T-cell numbers reach a plateau. The increase in CD4+ T cells following therapy most likely is a composite of initial redistribution, accompanied by a continuous slow repopulation with newly produced naive T cells.
TL;DR: It is reported here that deficient PAI1 expression in host mice prevented local invasion and tumor vascularization of transplanted malignant keratinocytes and this experimental evidence demonstrates that host-produced PAI is essential for cancer cell invasion and angiogenesis.
Abstract: Acquisition of invasive/metastatic potential through protease expression is an essential event in tumor progression. High levels of components of the plasminogen activation system, including urokinase, but paradoxically also its inhibitor, plasminogen activator inhibitor 1 (PAI1), have been correlated with a poor prognosis for some cancers. We report here that deficient PAI1 expression in host mice prevented local invasion and tumor vascularization of transplanted malignant keratinocytes. When this PAI1 deficiency was circumvented by intravenous injection of a replication-defective adenoviral vector expressing human PAI1, invasion and associated angiogenesis were restored. This experimental evidence demonstrates that host-produced PAI is essential for cancer cell invasion and angiogenesis.
TL;DR: The described method permits the direct confirmation of drug targets and recognition of drug-dependent changes in gene expression that are modulated through pathways distinct from the drug's intended target.
Abstract: We describe here a method for drug target validation and identification of secondary drug target effects based on genome-wide gene expression patterns. The method is demonstrated by several experiments, including treatment of yeast mutant strains defective in calcineurin, immunophilins or other genes with the immunosuppressants cyclosporin A or FK506. Presence or absence of the characteristic drug 'signature' pattern of altered gene expression in drug-treated cells with a mutation in the gene encoding a putative target established whether that target was required to generate the drug signature. Drug dependent effects were seen in 'targetless' cells, showing that FK506 affects additional pathways independent of calcineurin and the immunophilins. The described method permits the direct confirmation of drug targets and recognition of drug-dependent changes in gene expression that are modulated through pathways distinct from the drug's intended target. Such a method may prove useful in improving the efficiency of drug development programs.
TL;DR: Results indicate that the membrane-bound form of FasL is the functional form and suggest that shedding of Fas L is to prevent the killing of the healthy bystander cells by cytotoxic T cells.
Abstract: Apoptosis-inducing Fas ligand (FasL) is a type II membrane protein, predominantly expressed in the activated T cells. FasL is cleaved by a putative metalloproteinase to produce a soluble form. Here, we blocked the shedding of human FasL by deleting its cleavage site. Although human Jurkat cells and mouse primary hepatocytes that express a low level of Fas were resistant to the soluble form of FasL, they were efficiently killed by membrane-bound FasL. Furthermore, soluble FasL inhibited cytotoxicity of the membrane-bound FasL. These results indicate that the membrane-bound form of FasL is the functional form and suggest that shedding of FasL is to prevent the killing of the healthy bystander cells by cytotoxic T cells.
TL;DR: DNA priming followed by MVA boosting may provide a general immunization regime for induction of high levels of CD8+ T cells and was abrogated when the order of immunization was reversed.
Abstract: Immunization with irradiated sporozoites can protect against malaria infection and intensive efforts are aimed at reproducing this effect with subunit vaccines. A particular sequence of subunit immunization with pre-erythrocytic antigens of Plasmodium berghei, consisting of single dose priming with plasmid DNA followed by a single boost with a recombinant modified vaccinia virus Ankara (MVA) expressing the same antigen, induced unprecedented complete protection against P. berghei sporozoite challenge in two strains of mice. Protection was associated with very high levels of splenic peptide-specific interferon-γ-secreting CD8+ T cells and was abrogated when the order of immunization was reversed. DNA priming followed by MVA boosting may provide a general immunization regime for induction of high levels of CD8+ T cells.
TL;DR: Results show that diabetes induced by Coxsackie virus infection is a direct result of local infection leading to inflammation, tissue damage, and the release of sequestered islet antigen resulting in the re-stimulation of resting autoreactive T cells, further indicating that the is let antigen sensitization is an indirect consequence of the viral infection.
Abstract: Viral induction of autoimmunity is thought to occur by either bystander T-cell activation or molecular mimicry. Coxsackie B4 virus is strongly associated with the development of insulin-dependent diabetes mellitus in humans and shares sequence similarity with the islet autoantigen glutamic acid decarboxylase. We infected different strains of mice with Coxsackie B4 virus to discriminate between the two possible induction mechanisms, and found that mice with susceptible MHC alleles had no viral acceleration of diabetes, but mice with a T cell receptor transgene specific for a different islet autoantigen rapidly developed diabetes. These results show that diabetes induced by Coxsackie virus infection is a direct result of local infection leading to inflammation, tissue damage, and the release of sequestered islet antigen resulting in the re-stimulation of resting autoreactive T cells, further indicating that the islet antigen sensitization is an indirect consequence of the viral infection.
TL;DR: It is shown that the PfEMPI variants expressed during episodes of clinical malaria were less likely to be recognized by the corresponding child's own preexisting antibody response than by that of children of the same age from the same community.
Abstract: The feasibility of a malaria vaccine is supported by the fact that children in endemic areas develop naturally acquired immunity to disease. Development of disease immunity is characterized by a decrease in the frequency and severity of disease episodes over several years despite almost continuous infection, suggesting that immunity may develop through the acquisition of a repertoire of specific, protective antibodies directed against polymorphic target antigens. Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a potentially important family of target antigens, because these proteins are inserted into the red cell surface and are prominently exposed and because they are highly polymorphic and undergo clonal antigenic variation, a mechanism of immune evasion maintained by a large family of var genes. In a large prospective study of Kenyan children, we have used the fact that anti-PfEMP1 antibodies agglutinate infected erythrocytes in a variant-specific manner, to show that the PfEMP1 variants expressed during episodes of clinical malaria were less likely to be recognized by the corresponding child's own preexisting antibody response than by that of children of the same age from the same community. In contrast, a heterologous parasite isolate was just as likely to be recognized. The apparent selective pressure exerted by established anti-PfEMP1 antibodies on infecting parasites supports the idea that such responses provide variant-specific protection against disease.