Programmed death 1 signaling on chronic myeloid leukemia-specific T cells results in T-cell exhaustion and disease progression

Chronic myeloid leukemia (CML) is a malignant myeloproliferative disease with a characteristic chronic phase (cp) of several years before progression to blast crisis (bc). The immune system may contribute to disease control in CML. We analyzed leukemia-specific immune responses in cpCML and bcCML in a retroviral-induced murine CML model. In the presence of cpCML and bcCML expressing the glycoprotein of lymphocytic choriomeningitis virus as a model leukemia antigen, leukemia-specific cytotoxic T lymphocytes (CTLs) became exhausted. They maintained only limited cytotoxic activity, and did not produce interferon-gamma or tumor necrosis factor-alpha or expand after restimulation. CML-specific CTLs were characterized by high expression of programmed death 1 (PD-1), whereas CML cells expressed PD-ligand 1 (PD-L1). Blocking the PD-1/PD-L1 interaction by generating bcCML in PD-1-deficient mice or by repetitive administration of alphaPD-L1 antibody prolonged survival. In addition, we found that PD-1 is up-regulated on CD8(+) T cells from CML patients. Taken together, our results suggest that blocking the PD-1/PD-L1 interaction may restore the function of CML-specific CTLs and may represent a novel therapeutic approach for CML.

Clinical impact of programmed cell death ligand 1 expression in colorectal cancer

BACKGROUND Programmed cell death 1 (PD-1) receptor triggering by PD ligand 1 (PD-L1) inhibits T cell activation. PD-L1 expression was detected in different malignancies and associated with poor prognosis. Therapeutic antibodies inhibiting PD-1/PD-L1 interaction have been developed. MATERIALS AND METHODS A tissue microarray (n=1491) including healthy colon mucosa and clinically annotated colorectal cancer (CRC) specimens was stained with two PD-L1 specific antibody preparations. Surgically excised CRC specimens were enzymatically digested and analysed for cluster of differentiation 8 (CD8) and PD-1 expression. RESULTS Strong PD-L1 expression was observed in 37% of mismatch repair (MMR)-proficient and in 29% of MMR-deficient CRC. In MMR-proficient CRC strong PD-L1 expression correlated with infiltration by CD8(+) lymphocytes (P=0.0001) which did not express PD-1. In univariate analysis, strong PD-L1 expression in MMR-proficient CRC was significantly associated with early T stage, absence of lymph node metastases, lower tumour grade, absence of vascular invasion and significantly improved survival in training (P=0.0001) and validation (P=0.03) sets. A similar trend (P=0.052) was also detectable in multivariate analysis including age, sex, T stage, N stage, tumour grade, vascular invasion, invasive margin and MMR status. Interestingly, programmed death receptor ligand 1 (PDL-1) and interferon (IFN)-γ gene expression, as detected by quantitative reverse transcriptase polymerase chain reaction (RT-PCR) in fresh frozen CRC specimens (n=42) were found to be significantly associated (r=0.33, P=0.03). CONCLUSION PD-L1 expression is paradoxically associated with improved survival in MMR-proficient CRC.

Life and death partners: apoptosis, autophagy and the cross-talk between them

It is not surprising that the demise of a cell is a complex well-controlled process. Apoptosis, the first genetically programmed death process identified, has been extensively studied and its contribution to the pathogenesis of disease well documented. Yet, apoptosis does not function alone to determine a cell's fate. More recently, autophagy, a process in which de novo-formed membrane-enclosed vesicles engulf and consume cellular components, has been shown to engage in a complex interplay with apoptosis. In some cellular settings, it can serve as a cell survival pathway, suppressing apoptosis, and in others, it can lead to death itself, either in collaboration with apoptosis or as a back-up mechanism when the former is defective. The molecular regulators of both pathways are inter-connected; numerous death stimuli are capable of activating either pathway, and both pathways share several genes that are critical for their respective execution. The cross-talk between apoptosis and autophagy is therefore quite complex, and sometimes contradictory, but surely critical to the overall fate of the cell. Furthermore, the cross-talk is a key factor in the outcome of death-related pathologies such as cancer, its development and treatment.

The additional facet of immunoscore: immunoprofiling as a possible predictive tool for cancer treatment

Recent investigations of the tumor microenvironment have shown that many tumors are infiltrated by inflammatory and lymphocytic cells. Increasing evidence suggests that the number, type and location of these tumor-infiltrating lymphocytes in primary tumors has prognostic value, and this has led to the development of an 'immunoscore. As well as providing useful prognostic information, the immunoscore concept also has the potential to help predict response to treatment, thereby improving decision- making with regard to choice of therapy. This predictive aspect of the tumor microenvironment forms the basis for the concept of immunoprofiling, which can be described as 'using an individual's immune system signature (or profile) to predict that patient's response to therapy' The immunoprofile of an individual can be genetically determined or tumor-induced (and therefore dynamic). Ipilimumab is the first in a series of immunomodulating antibodies and has been shown to be associated with improved overall survival in patients with advanced melanoma. Other immunotherapies in development include anti-programmed death 1 protein (nivolumab), anti-PD-ligand 1, anti-CD137 (urelumab), and anti-OX40. Biomarkers that can be used as predictive factors for these treatments have not yet been clinically validated. However, there is already evidence that the tumor microenvironment can have a predictive role, with clinical activity of ipilimumab related to high baseline expression of the immune-related genes FoxP3 and indoleamine 2,3-dioxygenase and an increase in tumor-infiltrating lymphocytes. These biomarkers could represent the first potential proposal for an immunoprofiling panel in patients for whom anti-CTLA-4 therapy is being considered, although prospective data are required. In conclusion, the evaluation of systemic and local immunological biomarkers could offer useful prognostic information and facilitate clinical decision making. The challenge will be to identify the individual immunoprofile of each patient and the consequent choice of optimal therapy or combination of therapies to be used.

Inflammation-associated autophagy-related programmed necrotic death of human neutrophils characterized by organelle fusion events

The most common form of neutrophil death, under both physiological and inflammatory conditions, is apoptosis. In this study, we report a novel form of programmed necrotic cell death, associated with cytoplasmic organelle fusion events, that occurs in neutrophils exposed to GM-CSF and other inflammatory cytokines upon ligation of CD44. Strikingly, this type of neutrophil death requires PI3K activation, a signaling event usually involved in cellular survival pathways. In the death pathway reported in this study, PI3K is required for the generation of reactive oxygen species, which somehow trigger the generation of large cytoplasmic vacuoles, generated by the fusion of CD44-containing endosomes with autophagosomes and secondary, but not primary, granules. Neutrophils demonstrating vacuolization undergo rapid cell death that depends on receptor-interacting protein 1 kinase activity and papain family protease(s), but not caspases, that are most likely activated and released, respectively, during or as a consequence of organelle fusion. Vacuolized neutrophils are present in infectious and autoimmune diseases under in vivo conditions. Moreover, isolated neutrophils from such patients are highly sensitive toward CD44-mediated PI3K activation, reactive oxygen species production, and cell death, suggesting that the newly described autophagy-related form of programmed neutrophil necrosis plays an important role in inflammatory responses.

Suppression of cell proliferation and programmed cell death by dexamethasone during postnatal lung development

Prematurely born babies are often treated with glucocorticoids. We studied the consequences of an early postnatal and short dexamethasone treatment (0.1-0.01 microg/g, days 1-4) on lung development in rats, focusing on its influence on peaks of cell proliferation around day 4 and of programmed cell death at days 19-21. By morphological criteria, we observed a dexamethasone-induced premature maturation of the septa (day 4), followed by a transient septal immatureness and delayed alveolarization leading to complete rescue of the structural changes. The numbers of proliferating (anti-Ki67) and dying cells (TdT-mediated dUTP nick end labeling) were determined and compared with controls. In dexamethasone-treated animals, both the peak of cell proliferation and the peak of programmed cell death were reduced to baseline, whereas the expression of tissue transglutaminase (transglutaminase-C), another marker for postnatal lung maturation, was not significantly altered. We hypothesize that a short neonatal course of dexamethasone leads to severe but transient structural changes of the lung parenchyma and influences the balance between cell proliferation and cell death even in later stages of lung maturation.

Programmed cell death contributes to postnatal lung development

The rat lung undergoes the phase of maturation of the alveolar septa and of the parenchymal microvascular network mainly during the third postnatal week. Speculating that programmed cell death may contribute to the thinning of the alveolar septa, we searched for the presence of DNA fragmentation in rat lungs between postnatal days 6 and 36 using the TUNEL procedure. The number of positive nuclei was compared at different days. We observed an 8-fold increase of programmed cell death toward the end of the third week as compared to the days before and after this time point. The precise timing of the appearance of the peak depended on the size of the litter. Double-labeling for DNA fragmentation (TUNEL) and for type I and type II epithelial cells (antibodies E11 and MNF-116), as well as morphologic studies at electron microscopic level, revealed that during the peak of programmed cell death mainly fibroblasts and type II epithelial cells were dying. While both dying cell types were TUNEL-positive, nuclear fragments and apoptotic bodies were exclusively observed in the dying fibroblasts. We conclude that programmed cell death is involved in the structural maturation of the lung by reducing the number of fibroblasts and type II epithelial cells in the third postnatal week. We observed that the dying fibroblasts are cleared by neighboring fibroblasts in a later stage of apoptosis, and we hypothesize that type II epithelial cells are cleared by alveolar macrophages in early stages of the programmed cell death process.

Multiple programmed cell death pathways are involved in N-methyl-N-nitrosourea-induced photoreceptor degeneration.

PURPOSE: To identify programmed cell death (PCD) pathways involved in N-methyl-N-nitrosourea (MNU)-induced photoreceptor (PR) degeneration. METHODS: Adult C57BL/6 mice received a single MNU i.p. injection (60 mg/kg bodyweight), and were observed over a period of 7 days. Degeneration was visualized by H&E overview staining and electron microscopy. PR cell death was measured by quantifying TUNEL-positive cells in the outer nuclear layer (ONL). Activity measurements of key PCD enzymes (calpain, caspases) were used to identify the involved cell death pathways. Furthermore, the expression level of C/EBP homologous protein (CHOP) and glucose-regulated protein 78 (GRP78), key players in endoplasmic reticulum (ER) stress-induced apoptosis, was analyzed using quantitative real-time PCR. RESULTS: A decrease in ONL thickness and the appearance of apoptotic PR nuclei could be detected beginning 3 days post-injection (PI). This was accompanied by an increase of TUNEL-positive cells. Significant upregulation of activated caspases (3, 9, 12) was found at different time periods after MNU injection. Additionally, several other players of nonconventional PCD pathways were also upregulated. Consequently, calpain activity increased in the ONL, with a maximum on day 7 PI and an upregulation of CHOP and GRP78 expression beginning on day 1 PI was found. CONCLUSIONS: The data indicate that regular apoptosis is the major cause of MNU-induced PR cell death. However, alternative PCD pathways, including ER stress and calpain activation, are also involved. Knowledge about the mechanisms involved in this mouse model of PR degeneration could facilitate the design of putative combinatory therapeutic approaches.

In vitro differentiation of mouse granulocytes. Programmed Cell Death: Methods and Protocols

Granulocytes are central players of the immune system and, once activated, a tightly controlled balance between effector functions and cell removal by apoptosis guarantees maximal host benefit with least possible collateral damage to healthy tissue. Granulocytes are end-differentiated cells that cannot be maintained in culture for prolonged times. Isolating primary granulocytes is inefficient and challenging when working with mice, and especially so for the lowly abundant eosinophil and basophils subtypes. Here we describe an in vitro protocol to massively expand mouse derived myeloid progenitors and to differentiate them ‘on demand’ and in large numbers into mature neutrophils or basophils.

Granulocyte death regulation by naturally occurring autoantibodies

Programmed cell death (PCD) plays a central role in the regulation of granulocytes that are key effector cells of the innate immune system. Granulocytes are produced in high amounts in the bone marrow. A safe elimination of granulocytes by cell death (apoptosis) is essential to maintain the numbers of these cells balanced. In many acute and chronic inflammatory diseases, delayed apoptosis is one mechanism that contributes to accumulation of neutrophil and eosinophil granulocytes at the site of inflammation. On the other hand, a safe elimination of granulocytes by cell death is required to avoid unwanted tissue damage for instance by secretion of toxic products from these cells. Recent evidence shows that humans produce an array of naturally occurring autoantibodies (NAbs) with the capacity to regulate granulocyte death, including agonistic and antagonistic NAbs that bind to the receptors Fas, Siglec-8, and Siglec-9. Together with other factors, these various NAbs exhibit different properties in terms of the form of cell death they induce, the molecular signaling pathways they engage, as well as the efficacy or potency by which they induce cell death. Moreover, several regulatory mechanisms seem to exist that control their biological activity. Novel insights support the concept of granulocyte death regulation by NAbs, which might have important implications for our understanding of the pathogenesis and treatment of inflammatory diseases, including many autoimmune and allergic disorders.

Cell death in immune thrombocytopenia: novel insights and perspectives

Immune thrombocytopenia (ITP) is a complex disease. The pathogenic and clinical heterogeneity of ITP is reflected by reports on variability in patient history and treatment response, in concert with recent evidence from mechanistic studies. Programmed cell death (PCD) pathways are thought to play a peculiar role in the megakaryocyte lineage in terms of hemostasis and the generation and function of megakaryocytes and platelets; unbalanced genetic or environmental disturbances of these tightly regulated pathways may cause thrombocytopenia. Dysregulated PCD has also been linked to peripheral platelet destruction, intramedullary apoptosis, and inefficient thrombopoiesis in ITP. In this article, we discuss novel and controversial findings on the role of PCD in the megakaryocyte lineage and their potential implications in terms of pathogenesis, diagnosis, and treatment of ITP.

International palliative care experts' view on phenomena indicating the last hours and days of life

BACKGROUND Providing the highest quality care for dying patients should be a core clinical proficiency and an integral part of comprehensive management, as fundamental as diagnosis and treatment. The aim of this study was to provide expert consensus on phenomena for identification and prediction of the last hours or days of a patient's life. This study is part of the OPCARE9 project, funded by the European Commission's Seventh Framework Programme. METHOD The phenomena associated with approaching death were generated using Delphi technique. The Delphi process was set up in three cycles to collate a set of useful and relevant phenomena that identify and predict the last hours and days of life. Each cycle included: (1) development of the questionnaire, (2) distribution of the Delphi questionnaire and (3) review and synthesis of findings. RESULTS The first Delphi cycle of 252 participants (health care professionals, volunteers, public) generated 194 different phenomena, perceptions and observations. In the second cycle, these phenomena were checked for their specific ability to diagnose the last hours/days of life. Fifty-eight phenomena achieved more than 80% expert consensus and were grouped into nine categories. In the third cycle, these 58 phenomena were ranked by a group of palliative care experts (78 professionals, including physicians, nurses, psycho-social-spiritual support; response rate 72%, see Table 1) in terms of clinical relevance to the prediction that a person will die within the next few hours/days. Twenty-one phenomena were determined to have "high relevance" by more than 50% of the experts. Based on these findings, the changes in the following categories (each consisting of up to three phenomena) were considered highly relevant to clinicians in identifying and predicting a patient's last hours/days of life: "breathing", "general deterioration", "consciousness/cognition", "skin", "intake of fluid, food, others", "emotional state" and "non-observations/expressed opinions/other". CONCLUSION Experts from different professional backgrounds identified a set of categories describing a structure within which clinical phenomena can be clinically assessed, in order to more accurately predict whether someone will die within the next days or hours. However, these phenomena need further specification for clinical use.

Identification of Novel Death-Associated Protein Kinase 2 Interaction Partners by Proteomic Screening Coupled with Bimolecular Fluorescence Complementation.

Death-associated protein kinase 2 (DAPK2) is a Ca(2+)/calmodulin-dependent Ser/Thr kinase that possesses tumor-suppressive functions and regulates programmed cell death, autophagy, oxidative stress, hematopoiesis, and motility. As only few binding partners of DAPK2 have been determined, the molecular mechanisms governing these biological functions are largely unknown. We report the identification of 180 potential DAPK2 interaction partners by affinity purification-coupled mass spectrometry, 12 of which are known DAPK binding proteins. A small subset of established and potential binding proteins detected in this screen was further investigated by bimolecular fluorescence complementation (BiFC) assays, a method to visualize protein interactions in living cells. These experiments revealed that α-actinin-1 and 14-3-3-β are novel DAPK2 binding partners. The interaction of DAPK2 with α-actinin-1 was localized at the plasma membrane, resulting in massive membrane blebbing and reduced cellular motility, whereas the interaction of DAPK2 with 14-3-3-β was localized to the cytoplasm, with no impact on blebbing, motility, or viability. Our results therefore suggest that DAPK2 effector functions are influenced by the protein's subcellular localization and highlight the utility of combining mass spectrometry screening with bimolecular fluorescence complementation to identify and characterize novel protein-protein interactions.