PD-1 instructs a tumor-suppressive metabolic program that restricts glycolysis and restrains AP-1 activity in T cell lymphoma.

The PDCD1-encoded immune checkpoint receptor PD-1 is a key tumor suppressor in T cells that is recurrently inactivated in T cell non-Hodgkin lymphomas (T-NHLs). The highest frequencies of PDCD1 deletions are detected in advanced disease, predicting inferior prognosis. However, the tumor-suppressive mechanisms of PD-1 signaling remain unknown. Here, using tractable mouse models for T-NHL and primary patient samples, we demonstrate that PD-1 signaling suppresses T cell malignancy by restricting glycolytic energy and acetyl coenzyme A (CoA) production. In addition, PD-1 inactivation enforces ATP citrate lyase (ACLY) activity, which generates extramitochondrial acetyl-CoA for histone acetylation to enable hyperactivity of activating protein 1 (AP-1) transcription factors. Conversely, pharmacological ACLY inhibition impedes aberrant AP-1 signaling in PD-1-deficient T-NHLs and is toxic to these cancers. Our data uncover genotype-specific vulnerabilities in PDCD1-mutated T-NHL and identify PD-1 as regulator of AP-1 activity.

The role of extended coagulation screening in adult cranial neurosurgery.

Introduction: Postoperative hemorrhage after adult cranial neurosurgery is a serious complication with substantial morbidity and mortality. Research question: We investigated if an extended preoperative screening and an early treatment of previously undetected coagulopathies may decrease the risk of postoperative hemorrhage. Methods: A prospective study cohort of patients undergoing elective cranial surgery and receiving the extended coagulatory work-up were compared to a propensity matched historical control cohort. The extended work-up included a standardized questionnaire on the patient's bleeding history as well as coagulatory tests of Factor XIII, von-Willebrand-Factor and PFA-100®. Deficiencies were substituted perioperatively. The primary outcome was determined as the surgical revision rate due to postoperative hemorrhage. Results: The study cohort and the control cohort included 197 cases each, without any significant difference in the preoperative intake of anticoagulant medication (p â€‹= â€‹.546). Most common interventions were resections of malignant tumors (41%), benign tumors (27%) and neurovascular surgeries (9%) in both cohorts. Imaging revealed postoperative hemorrhage in 7 cases (3.6%) in the study cohort and 18 cases (9.1%) in the control cohort (p â€‹= â€‹.023). Of these, revision surgeries were significantly more common in the control cohort with 14 cases (9.1%) compared to 5 cases (2.5%) in the study cohort (p â€‹= â€‹.034). Differences in mean intraoperative blood loss were not significant with 528 â€‹ml in the study cohort and 486 â€‹ml in the control cohort (p â€‹= â€‹.376). Conclusion: Preoperative extended coagulatory screening may allow for revealing previously undiagnosed coagulopathies with subsequent preoperative substitution and thereby reduction of risk for postoperative hemorrhage in adult cranial neurosurgery.

MondoA drives malignancy in B-ALL through enhanced adaptation to metabolic stress.

Cancer cells are in most instances characterized by rapid proliferation and uncontrolled cell division. Hence, they must adapt to proliferation-induced metabolic stress through intrinsic or acquired antimetabolic stress responses to maintain homeostasis and survival. One mechanism to achieve this is reprogramming gene expression in a metabolism-dependent manner. MondoA (also known as Myc-associated factor X-like protein X-interacting protein [MLXIP]), a member of the MYC interactome, has been described as an example of such a metabolic sensor. However, the role of MondoA in malignancy is not fully understood and the underlying mechanism in metabolic responses remains elusive. By assessing patient data sets, we found that MondoA overexpression is associated with worse survival in pediatric common acute lymphoblastic leukemia (ALL; B-precursor ALL [B-ALL]). Using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) and RNA-interference approaches, we observed that MondoA depletion reduces the transformational capacity of B-ALL cells in vitro and dramatically inhibits malignant potential in an in vivo mouse model. Interestingly, reduced expression of MondoA in patient data sets correlated with enrichment in metabolic pathways. The loss of MondoA correlated with increased tricarboxylic acid cycle activity. Mechanistically, MondoA senses metabolic stress in B-ALL cells by restricting oxidative phosphorylation through reduced pyruvate dehydrogenase activity. Glutamine starvation conditions greatly enhance this effect and highlight the inability to mitigate metabolic stress upon loss of MondoA in B-ALL. Our findings give novel insight into the function of MondoA in pediatric B-ALL and support the notion that MondoA inhibition in this entity offers a therapeutic opportunity and should be further explored.

Autophagy in mesenchymal progenitors protects mice against bone marrow failure after severe intermittent stress.

The cellular mechanisms required to ensure homeostasis of the hematopoietic niche and the ability of this niche to support hematopoiesis upon stress remain elusive. We here identify Wnt5a in Osterix+ mesenchymal progenitor and stem cells (MSPCs) as a critical factor for niche-dependent hematopoiesis. Mice lacking Wnt5a in MSPCs suffer from stress-related bone marrow (BM) failure and increased mortality. Niche cells devoid of Wnt5a show defective actin stress fiber orientation due to an elevated activity of the small GTPase CDC42. This results in incorrect positioning of autophagosomes and lysosomes, thus reducing autophagy and increasing oxidative stress. In MSPCs from patients from BM failure states which share features of peripheral cytopenia and hypocellular BM, we find similar defects in actin stress fiber orientation, reduced and incorrect colocalization of autophagosomes and lysosomes, and CDC42 activation. Strikingly, a short pharmacological intervention to attenuate elevated CDC42 activation in vivo in mice prevents defective actin-anchored autophagy in MSPCs, salvages hematopoiesis and protects against lethal cytopenia upon stress. In summary, our study identifies Wnt5a as a restriction factor for niche homeostasis by affecting CDC42-regulated actin stress-fiber orientation and autophagy upon stress. Our data further imply a critical role for autophagy in MSPCs for adequate support of hematopoiesis by the niche upon stress and in human diseases characterized by peripheral cytopenias and hypocellular BM.

Keratinocyte-intrinsic BCL10/MALT1 activity initiates and amplifies psoriasiform skin inflammation.

Psoriasis is a chronic inflammatory skin disease arising from poorly defined pathological cross-talk between keratinocytes and the immune system. BCL10 (B cell lymphoma/leukemia 10) and MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1) are ubiquitously expressed inflammatory signaling proteins that can interact with the psoriasis susceptibility factor CARD14, but their functions in psoriasis are insufficiently understood. We report that although keratinocyte-intrinsic BCL10/MALT1 deletions completely rescue inflammatory skin pathology triggered by germline Card14 gain-of-function mutation in mice, the BCL10/MALT1 signalosome is unexpectedly not involved in the CARD14-dependent interleukin-17 receptor (IL-17R) proximal pathway. Instead, it plays a more pleiotropic role by amplifying keratinocyte responses to a series of inflammatory cytokines, including IL-17A, IL-1ß, and TNF. Moreover, selective keratinocyte-intrinsic activation of BCL10/MALT1 signaling with an artificial engager molecule is sufficient to initiate lymphocyte-mediated psoriasiform skin inflammation, and aberrant BCL10/MALT1 activity is frequently detected in the skin of human sporadic psoriasis. Together, these results establish that BCL10/MALT1 signalosomes can act as initiators and crucial amplifiers of psoriatic skin inflammation and indicate a critical function for this complex in sporadic psoriasis.

ABO subgroup incompatibility with severe hemolysis after consecutive allogeneic stem cell transplantations.

Allogeneic hematopoietic stem cell transplantations (HSCTs) represent a curative strategy for treating hematologic malignancies yet bear dangerous and frequently life-threatening complications including the development of graft-versus-host disease. Here, we present a case of a patient that suffered from relapsed/refractory multiple myeloma, a hematologic neoplasm characterized by clonal proliferation of malignant plasma cells in the bone marrow. During the course of his disease, the patient underwent consecutive allogeneic HSCTs, during which he developed a clinical meaningful and hitherto unreported ABO subgroup incompatibility, leading to persistent hemolysis. Testing for ABO subgroups during donor selection, especially after consecutive allogeneic HSCTs, may therefore aid to prevent these complications.

Erratum: PD-1 is a haploinsufficient suppressor of T cell lymphomagenesis.

This corrects the article DOI: 10.1038/nature24649.

PD-1 is a haploinsufficient suppressor of T cell lymphomagenesis.

T cell non-Hodgkin lymphomas are a heterogeneous group of highly aggressive malignancies with poor clinical outcomes. T cell lymphomas originate from peripheral T cells and are frequently characterized by genetic gain-of-function variants in T cell receptor (TCR) signalling molecules. Although these oncogenic alterations are thought to drive TCR pathways to induce chronic proliferation and cell survival programmes, it remains unclear whether T cells contain tumour suppressors that can counteract these events. Here we show that the acute enforcement of oncogenic TCR signalling in lymphocytes in a mouse model of human T cell lymphoma drives the strong expansion of these cells in vivo. However, this response is short-lived and robustly counteracted by cell-intrinsic mechanisms. A subsequent genome-wide in vivo screen using T cell-specific transposon mutagenesis identified PDCD1, which encodes the inhibitory receptor programmed death-1 (PD-1), as a master gene that suppresses oncogenic T cell signalling. Mono- and bi-allelic deletions of PDCD1 are also recurrently observed in human T cell lymphomas with frequencies that can exceed 30%, indicating high clinical relevance. Mechanistically, the activity of PD-1 enhances levels of the tumour suppressor PTEN and attenuates signalling by the kinases AKT and PKC in pre-malignant cells. By contrast, a homo- or heterozygous deletion of PD-1 allows unrestricted T cell growth after an oncogenic insult and leads to the rapid development of highly aggressive lymphomas in vivo that are readily transplantable to recipients. Thus, the inhibitory PD-1 receptor is a potent haploinsufficient tumour suppressor in T cell lymphomas that is frequently altered in human disease. These findings extend the known physiological functions of PD-1 beyond the prevention of immunopathology after antigen-induced T cell activation, and have implications for T cell lymphoma therapies and for current strategies that target PD-1 in the broader context of immuno-oncology.

Expression of the ALS-causing variant hSOD1(G93A) leads to an impaired integrity and altered regulation of claudin-5 expression in an in vitro blood-spinal cord barrier model.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive paralysis due to the loss of primary and secondary motor neurons. Mutations in the Cu/Zn-superoxide dismutase (SOD1) gene are associated with familial ALS and to date numerous hypotheses for ALS pathology exist including impairment of the blood-spinal cord barrier. In transgenic mice carrying mutated SOD1 genes, a disrupted blood-spinal cord barrier as well as decreased levels of tight junction (TJ) proteins ZO-1, occludin, and claudin-5 were detected. Here, we examined TJ protein levels and barrier function of primary blood-spinal cord barrier endothelial cells of presymptomatic hSOD1(G93A) mice and bEnd.3 cells stably expressing hSOD1(G93A). In both cellular systems, we observed reduced claudin-5 levels and a decreased transendothelial resistance (TER) as well as an increased apparent permeability. Analysis of the ß-catenin/AKT/forkhead box protein O1 (FoxO1) pathway and the FoxO1-regulated activity of the claudin-5 promoter revealed a repression of the claudin-5 gene expression in hSOD1(G93A) cells, which was depended on the phosphorylation status of FoxO1. These results strongly indicate that mutated SOD1 affects the expression and localization of TJ proteins leading to impaired integrity and breakdown of the blood-spinal cord barrier.