230 research outputs found
Comparing Mutuality and Solidarity in Its Application to Disaster Ethics
Often it has been observed that in disaster situations, people (including victims) become altruistic and are very willing to listen, obey and act in a manner that would help bring an end to the situation. In this chapter, linking disaster ethics and human rights, it is argued that this indeed is how it should be, disaster or otherwise, and that we have moral duties to oneself and to others. An individual exhibiting solidarity, comradery and altruism during a disaster is indeed behaving as a reasonable Self, and exercising ethical individualism as per Gewirthian philosophy. It is the duty of the State and society to act as a supportive State and a caring society. In order to do this, we need to be conditioned for ethical rationality before any whiff of disaster arises, i.e. in our day-to-day conduct and decision-making, at a personal, institutional and transnational level. Our ethical resilience during disasters can only be as robust as our rational moral compass during βpeace-timeβ. This chapter argues that Gewirthian solidarity ethics (GSE) should play a role in European policy and action in order to provide a system that conditions ethical rationality and in order to fulfil human rights. This involves addressing our current understanding of human rights as distinct categories of civil, political, economic, social and cultural rights and to effect a shift towards a more holistic understanding of human rights, whereby the hierarchy of fulfilment does not always prioritise civil and political rights.Peer reviewe
Cutting Edge: TRAIL Deficiency Accelerates Hematological Malignancies
Abstract
TNF apoptosis-inducing ligand is attracting considerable interest as a potential extrinsic tumor suppressor mechanism, although previous reports have conveyed somewhat contrasting views regarding the likely importance of this pathway. In this study, we provide the first evaluation of spontaneous tumor formation over the life span of TRAIL-deficient mice. Interestingly, >25% of these mice do develop lymphoid malignancies after 500 days of life. TRAIL suppressed the initiation and development of both tumors of lymphoid and stromal origin in the context of the loss of at least one p53 allele. Specific examination of the role of TRAIL in Her2/neu oncogene-driven mammary epithelial cancer revealed no critical role for TRAIL despite the inherent TRAIL sensitivity of such mammary carcinomas. Overall, the data indicate an important function of TRAIL in controlling carcinogenesis, but suggest that further examination of this pathway in epithelial malignancies is warranted
The Functional Basis for Hemophagocytic Lymphohistiocytosis in a Patient with Co-inherited Missense Mutations in the Perforin (PFN1) Gene
About 30% of cases of the autosomal recessive immunodeficiency disorder hemophagocytic lymphohistiocytosis are believed to be caused by inactivating mutations of the perforin gene. We expressed perforin in rat basophil leukemia cells to define the basis of perforin dysfunction associated with two mutations, R225W and G429E, inherited by a compound heterozygote patient. Whereas RBL cells expressing wild-type perforin (67 kD) efficiently killed Jurkat target cells to which they were conjugated, the substitution to tryptophan at position 225 resulted in expression of a truncated (βΌ45 kD) form of the protein, complete loss of cytotoxicity, and failure to traffic to rat basophil leukemia secretory granules. By contrast, G429E perforin was correctly processed, stored, and released, but the rat basophil leukemia cells possessed reduced cytotoxicity. The defective function of G429E perforin mapped downstream of exocytosis and was due to its reduced ability to bind lipid membranes in a calcium-dependent manner. This study elucidates the cellular basis for perforin dysfunctions in hemophagocytic lymphohistiocytosis and provides the means for studying structureβfunction relationships for lymphocyte perforin
TRAIL Receptor Signaling Regulation of Chemosensitivity In Vivo but Not In Vitro
Background: Signaling by Tumor Necrosis Factor-Related Apoptosis Inducing Ligand (TRAIL) and Fas ligand (FasL) has been proposed to contribute to the chemosensitivity of tumor cells treated with various other anti-cancer agents. However, the importance of these effects and whether there are differences in vitro and in vivo is unclear. Methodology/Principal Findings: To assess the relative contribution of death receptor pathways to this sensitivity and to determine whether these effects are intrinsic to the tumor cells, we compared the chemosensitivity of isogenic BJAB human lymphoma cells where Fas and TRAIL receptors or just TRAIL receptors were inhibited using mutants of the adaptor protein FADD or by altering the expression of the homeobox transcription factor Six1. Inhibition of TRAIL receptors did not affect in vitro tumor cell killing by various anti-cancer agents indicating that chemosensitivity is not significantly affected by the tumor cell-intrinsic activation of death receptor signaling. However, selective inhibition of TRAIL receptor signaling caused reduced tumor regression and clearance in vivo when tested in a NOD/SCID mouse model. Conclusions: These data show that TRAIL receptor signaling in tumor cells can determine chemosensitivity in vivo but not in vitro and thus imply that TRAIL resistance makes tumors less susceptible to conventional cytotoxic anti-cancer drugs a
Activation of the Hippo pathway by CTLA-4 regulates the expression of Blimp-1 in the CD8+ T cell
During the primary response, the commitment of the CD8(+) T cell to Blimp-1 expression and the terminal differentiation that Blimp-1 induces must be timed so as not to impair the process of clonal expansion. We determined whether the Hippo pathway, which links cell-cell contact to differentiation in other cell lineages, controls Blimp-1 expression. Activating the CD8(+) T cell with antigen and IL-2 causes expression of the core Hippo pathway components, including the pivotal transcriptional cofactor Yap. Contact between activated CD8(+) T cells induces Hippo pathway-mediated Yap degradation and Blimp-1 expression; a Hippo-resistant, stable form of Yap suppresses Blimp-1 expression. Cytotoxic T lymphocyte antigen 4 (CTLA-4) and CD80 comprise the receptor-ligand pair that mediates contact-dependent Hippo pathway activation. In vivo, CD8(+) T cells expressing Hippo resistant-Yap or lacking CTLA-4 have diminished expression of the senescence marker, KLRG1, during a viral infection. The CTLA-4/Hippo pathway/Blimp-1 system may couple terminal differentiation of CD8(+) T cell with the magnitude of clonal expansion
Cyclophosphamide Chemotherapy Sensitizes Tumor Cells to TRAIL-Dependent CD8 T Cell-Mediated Immune Attack Resulting in Suppression of Tumor Growth
Background: Anti-cancer chemotherapy can be simultaneously lymphodepleting and immunostimulatory. Pre-clinical models clearly demonstrate that chemotherapy can synergize with immunotherapy, raising the question how the immune system can be mobilized to generate anti-tumor immune responses in the context of chemotherapy. Methods and Findings: We used a mouse model of malignant mesothelioma, AB1-HA, to investigate T cell-dependent tumor resolution after chemotherapy. Established AB1-HA tumors were cured by a single dose of cyclophosphamide in a CD8 T cell- and NK cell-dependent manner. This treatment was associated with an IFN-Ξ±/Ξ² response and a profound negative impact on the anti-tumor and total CD8 T cell responses. Despite this negative effect, CD8 T cells were essential for curative responses. The important effector molecules used by the anti-tumor immune response included IFN-Ξ³ and TRAIL. The importance of TRAIL was supported by experiments in nude mice where the lack of functional T cells could be compensated by agonistic anti-TRAIL-receptor (DR5) antibodies. Conclusion: The data support a model in which chemotherapy sensitizes tumor cells for T cell-, and possibly NK cell-, mediated apoptosis. A key role of tumor cell sensitization to immune attack is supported by the role of TRAIL in tumor resolution and explains the paradox of successful CD8 T cell-dependent anti-tumor responses in the absence of CD8 T cell expansion
Bcl-2-regulated cell death signalling in the prevention of autoimmunity
Cell death mediated through the intrinsic, Bcl-2-regulated mitochondrial apoptosis signalling pathway is critical for lymphocyte development and the establishment of central and maintenance of peripheral tolerance. Defects in Bcl-2-regulated cell death signalling have been reported to cause or correlate with autoimmunity in mice and men. This review focuses on the role of Bcl-2 family proteins implicated in the development of autoimmune disorders and their potential as targets for therapeutic intervention
Differential tumor surveillance by natural killer (NK) and NKT cells
Natural tumor surveillance capabilities of the host were investigated in six different mouse tumor models where endogenous interleukin (IL)-12. does or does not dictate the efficiency of the innate immune response. Gene-targeted and lymphocyte subset-depleted mice were used to establish the relative importance of natural killer (NK) and NK1.1(+) T (NKT) cells in protection from tumor initiation and metastasis. In the models examined, CD3(-) NK cells were responsible for tumor rejection and protection from metastasis in models where control of major histocompatibility complex class I-deficient tumors was independent of IL-12, A protective role for NKT cells was only observed when tumor rejection required endogenous IL-12 activity. In particular, T cell receptor J alpha 281 gene-targeted mice confirmed a critical function for NKT cells in protection from spontaneous tumors initiated by the chemical carcinogen, methylcholanthrene. This is the first description of an antitumor function for NKT cells in the absence of exogenously administered potent stimulators such as IL-12 or alpha-galactosylceramide
Implication of 4E-BP1 protein dephosphorylation and accumulation in pancreatic cancer cell death induced by combined gemcitabine and TRAIL
Pancreatic cancer cells show varying sensitivity to the anticancer effects of gemcitabine. However, as a chemotherapeutic agent, gemcitabine can cause intolerably high levels of toxicity and patients often develop resistance to the beneficial effects of this drug. Combination studies show that use of gemcitabine with the pro-apoptotic cytokine TRAIL can enhance the inhibition of survival and induction of apoptosis of pancreatic cancer cells. Additionally, following combination treatment there is a dramatic increase in the level of the hypophosphorylated form of the tumour suppressor protein 4E-BP1. This is associated with inhibition of mTOR activity, resulting from caspase-mediated cleavage of the Raptor and Rictor components of mTOR. Use of the pan-caspase inhibitor Z-VAD-FMK indicates that the increase in level of 4E-BP1 is also caspase-mediated. ShRNA-silencing of 4E-BP1 expression renders cells more resistant to cell death induced by the combination treatment. Since the levels of 4E-BP1 are relatively low in untreated pancreatic cancer cells these results suggest that combined therapy with gemcitabine and TRAIL could improve the responsiveness of tumours to treatment by elevating the expression of 4E-BP1
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