The contribution of interleukin-10 (IL-10), secreted by tumoral B cells, to the progression and shaping of the microenvironment in diffuse large B-cell lymphoma (DLBCL) with activated B-cell-like (ABC) phenotype is not yet completely understood. To shed light on this issue, we generated an immunocompetent mouse model of ABC-DLBCL with conditional knockout of IL-10 specifically in malignant B cells. Paradoxically, these mice had significantly worse overall survival when left untreated but experienced increased sensitivity to conventional anti-CD20 immunotherapy or regulatory T-cell depletion. We identified various immunomodulatory mechanisms involved in this behavior. In particular, we show that IL-10-deficient lymphomas acquire a highly immunosuppressed and T-cell-exhausted microenvironment with increased angiogenesis that results in a more aggressive phenotype, which is refractory to PD-1 immune checkpoint blockade. However, the response of IL-10-deficient mice to anti-CD20 immunotherapy was greatly enhanced by upregulation of calcium channels in B cells. In general, IL-10 autocrine signaling promotes the survival of malignant B cells, whereas the paracrine action of B-cell-derived IL-10 maintains an immunoreactive microenvironment that influences the efficacy of emerging immunotherapy strategies targeting the lymphoma microenvironment. Furthermore, IL-10-associated transcriptional signatures derived from our studies may correctly predict clinical outcomes of patients with DLBCL treated with R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone). Thus, our work provides important functional and mechanistic insights into the role of B-cell-derived IL-10 in the biology of ABC-DLBCL.

The phase 2 CLL2-BZAG trial tested a measurable residual disease (MRD)-guided combination treatment of zanubrutinib, venetoclax, and obinutuzumab after an optional bendamustine debulking in patients with relapsed/refractory chronic lymphocytic leukemia (CLL). In total, 42 patients were enrolled and 2 patients with ≤2 induction cycles were excluded from the analysis population per protocol. Patients had a median of 1 prior therapy (range, 1-5); 18 patients (45%) had already received a Bruton tyrosine kinase (BTK) inhibitor (BTKi); 7 patients (17.5%) venetoclax; and, of these, 5 (12.5%) had received both. Fifteen patients (37.5%) had a TP53 mutation/deletion, and 31 (77.5%) had unmutated immunoglobulin heavy chain variable region gene. With a median observation time of 21.5 months (range, 8.0-35.3) the most common adverse events were COVID-19 (n = 26 patients), diarrhea (n = 15), infusion-related reactions (n = 15), thrombocytopenia (n = 14), nausea (n = 12), fatigue (n = 12), and neutropenia (n = 12). Two patients had fatal adverse events (COVID-19, and fungal pneumonia secondary to COVID-19). After 6 months of the triple combination, all patients responded, and 21 (52.5%; 95% confidence interval, 36.1-68.5) showed undetectable MRD (uMRD) in the peripheral blood. In many patients, remissions deepened over time, with a best uMRD rate of 85%. The estimated progression-free and overall survival rates at 18 months were 96% and 96.8%, respectively. No patient has yet required a subsequent treatment. In summary, the MRD-guided triple combination of zanubrutinib, venetoclax, and obinutuzumab induced deep remissions in a relapsed CLL population enriched for patients previously treated with a BTKi/venetoclax. This trial was registered at www.clinicaltrials.gov as #NCT04515238.

Globally, an estimated 300 million individuals have sickle cell trait (SCT), the carrier state for sickle cell disease (SCD). Although SCD is associated with increased morbidity and shortened life span, SCT has a life span comparable with that of the general population. However, "sickle cell crisis" has been used as a cause of death for decedents with SCT in reports of exertion-related death in athletes, military personnel, and individuals in police custody. To appraise this practice, the American Society of Hematology convened an expert panel of hematologists and forensic pathologists to conduct a systematic review of the literature relating to the occurrence of sickle cell pain crises and exertion-related mortality in people with SCT. Multiple bibliographic databases were searched with controlled vocabulary and keywords related to "sickle cell trait," "vaso-occlusive pain," and "death," yielding 18 of 1474 citations. Independent pairs of reviewers selected studies and extracted data. We found no studies comparing uncomplicated acute pain crises in individuals with SCT and SCD. Additionally, no study was identified to support the occurrence of acute vaso-occlusive pain crises in individuals with SCT. Furthermore, this systematic review did not identify any evidence to support an association between SCT and sudden unexplained death in the absence of exertion-related rhabdomyolysis. We conclude that there are no data to support the diagnosis of acute vaso-occlusive sickle cell crisis as a cause of death in SCT, nor does the available evidence support the use of SCT as a cause of exertion-related death without rhabdomyolysis.

In thrombosis and hemostasis, the formation of a platelet-fibrin thrombus or clot is a highly controlled process that varies, depending on the pathological context. Major signaling pathways in platelets are well established. However, studies with genetically modified mice have identified the contribution of hundreds of additional platelet-expressed proteins in arterial thrombus formation and bleeding. Using phenotype information of 540 mouse genes, involved in arterial thrombosis and hemostasis, we review current insights into established and novel platelet signaling mechanisms. We discuss pathways involved in platelet adhesion, shape change, integrin activation, intracellular vesicle trafficking and protein processing, granule secretion, aggregate formation, and procoagulant activity. Specific attention is paid to the signaling routes used by immunoreceptor tyrosine-based activation motif linked, immunoreceptor tyrosine-based inhibitory motif linked, and G protein-coupled receptors, as well as downstream events feeding into GTPase regulation and protein kinase activation. We further summarize known alterations in platelet responses under conditions of venous, inflammatory, and infection-dependent thrombosis, taking into account interactions of platelets with the endothelium, leukocytes, and red blood cells. Understanding the genes and proteins involved in platelet signaling in the context of hemostasis, thrombosis, and inflammation may lead to improved therapies to prevent and treat thrombotic disorders.

Adenosine-to-inosine (A-to-I) RNA editing is a prevalent RNA modification essential for cell survival. The process is catalyzed by the adenosine deaminase acting on RNA (ADAR) enzyme family that converts adenosines in double-stranded RNAs (dsRNAs) into inosines, which are read as guanosines during translation. Deep sequencing has helped to reveal that A-to-I editing occurs across various types of RNAs, affecting their functions. RNA editing detection is now so sophisticated that we can achieve a high level of accuracy and sensitivity to identify low-abundance edited events. Consequently, A-to-I editing has been implicated in various biological processes, including immune and stress responses, cancer progression, and stem cell fate determination. In particular, a crucial role for this process has been recently reported in hematopoietic cell development and hematologic malignancy progression. Results from genetic mouse models have demonstrated the impact of ADARs' catalytic activity on hematopoietic cells, complemented by insights from human cell studies. Meanwhile, clinical studies have implicated ADAR enzymes and RNA editing events in hematologic malignancies and highlighted their potential as prognostic indicators. In this review, we outline the regulatory mechanisms of RNA editing in both normal hematopoiesis and hematologic malignancies. We then speculate on how targeting ADAR expression and site-specific RNA substrates might serve as a therapeutic avenue for affected patients.

Most patients with diffuse large B-cell lymphoma (DLBCL) treated with immunotherapies such as bispecific antibodies (BsAbs) or chimeric antigen receptor (CAR) T cells fail to achieve durable treatment responses, underscoring the need for a deeper understanding of mechanisms that regulate the immune environment and response to treatment. Here, an integrative multiomics approach was applied to multiple large independent data sets to characterize DLBCL immune environments and to define their association with tumor cell-intrinsic genomic alterations and outcomes to CD19-directed CAR T-cell and CD20 × CD3 BsAb therapies. This approach effectively segregated DLBCLs into 4 immune quadrants (IQs) defined by cell-of-origin and immune-related gene set expression scores. These quadrants consisted of activated B cell-like (ABC) hot, ABC cold, germinal center B cell-like (GCB) hot, and GCB cold DLBCLs. Recurrent genomic alterations were enriched in each IQ, suggesting that lymphoma cell-intrinsic alterations contribute significantly to orchestrating unique DLBCL immune environments. For instance, SOCS1 loss-of-function mutations were significantly enriched among GCB hot DLBCLs, identifying a putative subset of inflamed DLBCLs that may be inherently susceptible to immunotherapy. In patients with relapsed/refractory DLBCL, DLBCL-IQ assignment correlated significantly with clinical benefit with a CD20 × CD3 BsAb (N = 74), but not with CD19-directed CAR T cells (Stanford, N = 51; Memorial Sloan Kettering Cancer Center, N = 69). Thus, DLBCL-IQ provides a new framework to conceptualize the DLBCL immune landscape and suggests the endogenous immune environment has a more significant impact on outcomes to BsAb than CAR T-cell treatment.

Antibodies to β2-glycoprotein I (β2GPI) cause thrombosis in antiphospholipid syndrome; however, the role of β2GPI in coagulation in vivo is not understood. To address this issue, we developed β2GPI-deficient mice (Apoh-/-) by deleting exons 2 and 3 of Apoh using CRISPR/Cas9 and compared the development of thrombosis in wild-type (WT) and Apoh-/- mice using rose bengal- and FeCl3-induced carotid thrombosis, laser-induced cremaster arteriolar injury, and inferior vena cava (IVC) stasis models. We also compared tail bleeding times and activation of platelets from WT and Apoh-/- mice in the absence and presence of β2GPI. Apoh-/- mice demonstrated prolonged time to occlusion of the carotid after exposure to rose bengal or FeCl3 and reduced platelet and fibrin accumulation in cremasteric arterioles after laser injury. Significantly smaller thrombi formed in the IVC of Apoh-/- mice 48 hours after IVC occlusion. The activated partial thromboplastin time and prothrombin time, as well as activated partial thromboplastin time reagent and tissue factor-induced thrombin generation times, of Apoh-/- and WT plasma revealed no differences. However, we observed significant prolongation of tail bleeding in Apoh-/- mice and reduced P-selectin expression and fibrinogen binding to activated α2bβ3 on platelets from these mice after stimulation with thrombin; these changes were reversed by β2GPI. A protease activated receptor 3 (PAR3) antibody blocked thrombin-induced activation of WT platelets and the ability of β2GPI to restore thrombin-induced activation of Apoh-/- platelets. These studies demonstrate that β2GPI may promote platelet activation by enhancing the ability of PAR3 to present thrombin to PAR4.

Babesiosis in sickle cell disease (SCD) is marked by severe anemia but the underlying red blood cell (RBC) rheologic parameters remain largely undefined. Here, we describe altered RBC deformability from both primary (host RBC sickle hemoglobin mediated) and secondary changes (Babesia parasite infection mediated) to the RBC membrane using wild-type AA, sickle trait AS, and sickle SS RBCs. Our ektacytometry analysis demonstrates that the changes in the host RBC biomechanical properties, before and after Babesia infection, reside on a spectrum of severity, with wild-type infected AA cells, despite showing a significant reduction of deformability under both shear and osmolarity gradients, exhibiting only a mild phenotype, compared with infected AS RBCs that show median changes in deformability and infected SS RBCs that exhibit the most dramatic impact of infection on cellular rheology, including an increase in point of sickling values. Furthermore, using ImageStream cytometric technology to quantify changes in cellular shape and area along with a tunable resistive pulse sensor to measure release of extracellular vesicles from these host RBCs, before and after infection, we offer a potential mechanistic basis for this extreme SS RBC rheologic profile, which include enhanced sickling rates and altered osmotic fragility, loss of RBC surface area, and hypervesiculation in infected SS host RBCs. These results underline the importance of understanding the impact of intraerythrocytic parasitic infections of SCD RBCs, especially on their cellular membranes and studying the mechanisms that lead to hyperhemolysis and extreme anemia in patients with SCD.

Follicular lymphoma is the most common subtype of indolent lymphoma. Despite multiple trials over the past decades showing improved progression-free survival with new first-line therapeutic strategies, such as anti-CD20 maintenance therapy and new glycoengineered anti-CD20 antibodies, no standardized approach has been widely adopted in routine clinical practice. Several factors may explain this, including the increased incidence of infectious adverse events associated with these therapies, particularly during the COVID-19 pandemic, and the lack of overall survival benefit despite long-term follow-up. A consensus has emerged acknowledging the high prognostic variability of follicular lymphoma, which complicates the adoption of a one-size-fits-all first-line treatment strategy. A plethora of prognostic scores (Follicular Lymphoma International Prognostic Index [FLIPI], FLIPI2, PRIMA-Prognostic Index, m7-FLIPI, FLEX [Follicular Lymphoma Evaluation Index], 23-gene score, etc) has been proposed but none can reliably identify the ∼20% of patients who will die within 10 years of first-line immunochemotherapy and for whom a critical medical need remains despite recent therapeutic improvements. Consequently, current prognostic models mainly serve as tools to cross-compare and stratify clinical trials. In this review, we highlight current and future strategies aimed at reshaping frontline treatment paradigms to improve outcomes, including tailored approaches based on risk- or response-adapted designs, development of new predictive, rather than prognostic, tools, approaches to reduce adverse events to enhance health-related quality of life, and the potential use of T-cell-engaging therapies to improve survival in the highest risk patients.

Blood clots are complex structures composed of blood cells and proteins held together by a structural framework provided by an insoluble fibrin network. Factor (F)XIII is a protransglutaminase essential for stabilizing the fibrin network. Activated FXIII(a) introduces novel covalent cross-links within and between fibrin and other plasma and cellular proteins and thereby promotes fibrin biochemical and mechanical integrity. These irreversible modifications are also major determinants of clot composition and functional properties. As such, FXIII has central roles in hemostasis and wound healing, thrombosis, and many proinflammatory diseases associated with coagulation activation. The biochemical properties of FXIII are as interesting as its biology is unusual, giving rise to unique and still undefined mechanisms. Here, we review features underlying FXIII biology, biochemical function, biophysical impact, and (patho)physiologic implications in hemostasis, thrombosis, and disease.

T-cell prolymphocytic leukemia (T-PLL) is an aggressive lymphoid malignancy with limited treatment options. To discover new treatment targets for T-PLL, we performed high-throughput drug sensitivity screening on 30 primary patient samples ex vivo. After screening >2800 unique compounds, we found T-PLL to be more resistant to most drug classes, including chemotherapeutics, than other blood cancers. Furthermore, we discovered previously unreported vulnerabilities of T-PLL. T-PLL cells exhibited a particular sensitivity to drugs targeting autophagy (thapsigargin and bafilomycin A1), nuclear export (selinexor), and inhibitor of apoptosis proteins (IAPs; birinapant), sensitivities that were also shared by other T-cell malignancies. Through bulk and single-cell RNA sequencing, we found these compounds to activate the Toll-like receptor (bafilomycin A1), p53 (selinexor), and tumor necrosis factor α (TNF-α)/NF-κB signaling pathways (birinapant) in T-PLL cells. Focusing on birinapant for its potential in drug repurposing, we uncovered that IAP inhibitor-induced cell death was primarily necroptotic and dependent on TNF-α. Through spectral flow cytometry, we confirmed the absence of cleaved caspase-3 in IAP inhibitor-treated T-PLL cells and show that IAP inhibition reduces the proliferation of T-PLL cells stimulated ex vivo, while showing only a limited effect on nonmalignant T-cells. In summary, our study maps the drug sensitivity of T-PLL across a broad range of targets and identifies new therapeutic approaches for T-PLL by targeting IAPs, exportin 1, and autophagy, highlighting potential candidates for drug repurposing and novel treatment strategies.

Recent advances in acute myeloid leukemia (AML) come from studies investigating older adults aged <60 years, those aged ≥75 years, or less fit adults. Uncertainty exists for the management of otherwise healthy adults with AML in their 60s and 70s, which also represents a significant proportion of AML cases. We discuss current considerations in older, fit adults with AML, including determination of fitness, factors beyond fitness that should be assessed, and challenges and innovations to improve patient outcomes.