Sepsis is characterized by a systemic inflammation and microvascular thrombosis induced by infection. NLRP6 possesses both pro- and anti-inflammatory effects with cell-type- or tissue-specific functions. However, the role of cell-type-specific NLRP6 in sepsis remains poorly understood. In the present study, we detected NLRP6 expression in platelets. By using platelet-specific NLRP6 knockout mice and the cecal ligation and puncture model of sepsis, we demonstrated that deletion of platelet NLRP6 increased the mortality, enhanced microvascular thrombosis in the lung and liver, and promoted platelet activation, platelet-neutrophil interactions as well as the neutrophil extracellular traps (NETs) formation following sepsis. Platelet function analysis in vitro showed that deletion of NLRP6 enhanced platelet aggregation, activation, and granules release. In addition, NLRP6 deletion promoted platelet NF-κB signaling via sustaining TAB1 expression independent of the inflammasome. Moreover, inhibition of NF-κB signaling abolished the aggravated effects of the absence of platelet NLRP6 on the intravascular microthrombosis and NETs formation in sepsis and increased the overall survival. Mechanistically, NLRP6 facilitated the interaction between TRIM21 and TAB1 in activated platelets, resulting in K48-linked polyubiquitination of TAB1 and subsequent degradation. Finally, sepsis plasma triggered TAB1 degradation mediated by NLRP6/TRIM21 in normal healthy platelets through TLR4/MyD88. Our study identifies a novel protective role of platelet NLRP6 in the microvascular thrombosis during sepsis, implying it as a novel target for the treatment of sepsis.

While the majority of patients with follicular lymphoma (FL) follow an indolent disease course, some patients experience a critical inflection point when FL transforms into an aggressive lymphoma. Historically, FL transformation (tFL) is marked by poor outcomes, particularly for patients with prior FL-directed treatment. Compared to FL, tFL is marked by numerous additional genetic changes, upregulates novel signaling pathways and arises from an ancestral FL clone with shared FL-initiating mutations. Prediction of tFL risk remains a high-priority area of disease research, with recent work highlighting memory-like B cell phenotypes associated with transformation risk and implicating critical tumor-immune interactions at transformation emergence. Mechanistic studies provide insight into the role of genetic drivers in determining malignant B cell phenotypes or reducing microenvironmental dependencies. In parallel, a shifting therapeutic landscape marked by novel immune-based therapeutics is improving outcomes for patients, yet further clinical outcome data in tFL are greatly needed. This review summarizes recent scientific and clinical studies in tFL and provides an updated understanding of the biological basis, diagnosis and clinical management of tFL. We conclude with a proposed plan of future research aimed at the goal of increasing tFL biologic knowledge and improving outcomes for patients with tFL.

VEXAS (Vacuoles, E1 Enzyme, X-Linked, Autoinflammatory, Somatic) syndrome is a severe monogenic disorder caused by somatic UBA1 mutations, characterized by inflammation, cytopenias and frequent association with myelodysplastic neoplasms (MDS). Steroid dependence is common, and targeted therapies have demonstrated limited efficacy. Azacitidine (AZA), a hypomethylating agent used in MDS, has shown potential in VEXAS but data remain limited. This multicenter retrospective study assessed AZA efficacy and safety in 88 genetically confirmed VEXAS patients from the FRENVEX (French VEXAS) group, 80% meeting WHO 2022 MDS criteria. Inflammatory response rates were 41% at 6 months and 54% at 12 months, regardless of MDS status. A total of 50 (61%) patients achieved inflammatory response, with 70% occurring at 6 months, suggesting a delayed median response. Among responders, relapse-free survival on AZA was 90% at 1 year and 85% at 5 years. Of the 12 responders who discontinued AZA, 9 relapsed after a median of 3.1 years (range: 0.4-5.6), with effective re-exposure in 4 of 5 patients. Hematological responses included red blood cell transfusion independence in 65% and platelet improvement in 77% of patients. Molecular response, defined as a ≥25% reduction in UBA1 variant allele frequency (VAF), was observed in 65% of patients, all of whom achieved inflammatory and hematological responses; and VAF dropped below 2% in 43% of cases. Infections (34%) and cytopenias (36%) were common, particularly during the first three cycles. This study establishes AZA as an effective therapy for VEXAS, improving inflammation, cytopenias, and UBA1 clonal burden, warranting larger prospective trials.

Hemophagocytic Lymphohistiocytosis (HLH) is a life-threatening systemic hyperinflammatory syndrome arising in many contexts. Its underlying mechanisms are often unclear, but defective granule-mediated cytotoxicity (familial HLH) and excess IL-18 (Macrophage Activation Syndrome, MAS) provide clues. Mounting evidence suggests the causes of HLH converge on cytotoxic T lymphocyte (CTL) hyperactivation and overproduction of IFNγ. We refined an in vitro system to simultaneously quantify multiple parameters of the murine CTL immune synapse (IS). Even in haploinsufficiency, perforin deficiency prolonged IS duration and increased IFNγ/TNF production. Similarly, both target cell immortalization and inhibition of apoptotic caspases impaired IS termination and increased cytokine production. Strong CTL activation, through T-cell receptor or IL-18 signaling, also increased IFNγ secretion but accelerated target cell death. Impaired IS termination synergized with strong CTL activation in driving IFNγ production. Visually, both typical and Prf1-/- CTL-IS terminated with apoptotic contraction. We serendipitously observed many IL-18 exposed CTL-IS terminated by target cell ballooning. Both IL-18-activated CTL and IFNγ pretreatment caused up to half of target cells to die by RIPK1-dependent necroptosis. In vivo, RIPK1 inhibition ameliorated virus-triggered HLH in Il18tg more than Prf1-/- mice. By quantifying CTL-IS duration, cytokine production, and mode of cell death, we modeled multiple HLH contributors and their interactions, and identified three HLH mechanistic categories: impaired IS termination, intense CTL cytokine production, and inflammatory target cell death. Integrating the inputs and outcomes of a hyperinflammatory CTL-IS may provide a useful framework for understanding, predicting, or treating HLH in its many forms.

Despite the success of BCMA-targeting CAR-Ts in multiple myeloma, patients with high-risk cytogenetic features still relapse most quickly and are in urgent need of additional therapeutic options. Here, we identify CD70, widely recognized as a favorable immunotherapy target in other cancers, as a specifically upregulated cell surface antigen in high-risk myeloma tumors. We use a structure-guided design to define a CD27-based anti-CD70 CAR-T design that outperforms all tested scFv-based CARs, leading to >80-fold improved CAR-T expansion in vivo. Epigenetic analysis via machine learning predicts key transcription factors and transcriptional networks driving CD70 upregulation in high-risk myeloma. Dual-targeting CAR-Ts against either CD70 or BCMA demonstrate a potential strategy to avoid antigen escape-mediated resistance. Together, these findings support the promise of targeting CD70 with optimized CAR-Ts in myeloma as well as future clinical translation of this approach.

Immunotherapy has become standard of care in the treatment of diffuse large B-cell lymphoma (DLBCL). Changes in immunophenotypes observed at first diagnosis predict therapy outcome but little is known about the resolution of these alterations in remission. Comprehensive characterization of immune changes from fresh, peripheral whole blood revealed a functionally relevant increase of myeloid-derived suppressor cells, reduced naïve T-cells, and an increase of activated and terminally differentiated T-cells before treatment which aggravated after therapy. Suggesting causal relation, injection of lymphoma in mice induced similar changes in the murine T cells. Distinct immune imprints were found in breast cancer and AML survivors. Identified alterations persisted beyond five years of ongoing complete remission and in DLBCL correlated with increased pro-inflammatory markers such as IL-6, B2M, or sCD14. The chronic inflammation was associated with functionally blunted T-cell immunity against SARS-CoV-2-specific peptides and reduced responses correlated with reduced Tn-cells. Persisting inflammation was confirmed by deep sequencing and by cytokine profiles, together pointing towards a compensatory activation of innate immunity. The persisting, lymphoma-induced immune alterations in remission may explain long-term complications, have implications for vaccine strategies, and are likely relevant for immunotherapies.

This study analyzed the genetics of classical Hodgkin lymphoma (cHL) by using circulating tumor DNA (ctDNA). Two genetic subtypes were identified, differing in genetic instability mechanisms: one subtype (64% of cases) showed a higher mutation load and a higher fraction of mutations associated with activation-induced cytidine deaminase and microsatellite instability signatures, while the other subtype (36% of cases) exhibited chromosomal instability with more somatic copy number alterations. Whole-genome duplication was more common in cHL compared to other B-cell tumors and emerged as a prognostic biomarker for patients undergoing ABVD-based therapy. Non-coding regulatory mutations, similar to those in diffuse large B-cell lymphoma, were highly prevalent in 86% of cHL. A recurrent somatic expression quantitative trait locus (seQTL) involving the BCL6 gene was found in 30% of cases. The seQTL of BCL6 aligned with accessible chromatin and increased H3K27 acetylation in cHL, disrupted PRDM1 binding, and co-occurred with BCL6 expression in cHL cells. Weak to strong expression of BCL6 was observed in 68% of cases and BCL6 expression associated with gene repression similarly in cHL and germinal center B cells. After BCL6 degradation, the core set of genes directly bound and regulated by BCL6 was derepressed in cHL and proliferation was impaired. The number and clonality of neoantigens was associated with tumor microenvironment type and response to checkpoint blockade. Finally, ctDNA analysis was suggested as a tool to distinguish ambiguous PET/CT-positive lesions post-treatment.

Coagulation factor V (FV) is a key protein in maintaining the hemostatic balance, with abnormal plasma levels associated with both thrombotic and hemorrhagic conditions. We propose a comprehensive bioinformatic analysis integrating large scale proteogenomics and transcriptomic data from original and public datasets. We identify a biological fingerprint of 26 new proteins and loci involved in the regulation of plasma FV levels. Furthermore, the mRNA expression levels of 10 of these components show strong correlation in liver. In addition, we provide experimental evidence for the involvement of one of the newly identified players (CLEC4M) in the clearance of FV. This work opens new avenues for a better understanding of the physiological processes involved in thrombotic and bleeding disorders.

Rare thrombotic events associated with ChAdOx1 nCoV-19 (ChAdOx1) vaccination have raised concerns; however, the underlying mechanisms remain elusive. Here we report a novel biophysical mechanism by which ChAdOx1 directly interacts with platelets under arterial shear conditions, potentially contributing to post-vaccination arterial thrombosis. Using microfluidic post assays, we demonstrate that ChAdOx1 induces shear-dependent platelet aggregation, distinct from conventional von Willebrand factor-mediated adhesion. This interaction is mediated by platelet integrin αIIbβ3 and requires biomechanical activation, explaining the absence of significant binding under static conditions. Molecular dynamics simulations and docking studies reveal preferential binding of ChAdOx1's penton RGD motif to the activated conformation of αIIbβ3. Inhibiting integrin αIIbβ3 completely abolishes ChAdOx1-induced platelet aggregation, whereas blocking GPIb has minimal effect, confirming a mechanism that bypasses the conventional GPIb-dependent platelet adhesion pathway. Mutagenesis of the RGD motif to AAA eliminates platelet binding, verifying the specificity of this interaction. These findings provide a potential explanation for the association between ChAdOx1 vaccination and arterial thrombotic events, distinct from vaccine-induced immune thrombotic thrombocytopenia (VITT). Our results highlight the importance of considering biomechanical factors in vaccine-related thrombotic complications and suggest that shear-dependent integrin activation may be another determinant in the pathogenesis of these rare adverse events.

Insufficient eradication of cancer cells and survival of drug tolerant clones are major relapse driving forces. Underlying molecular mechanisms comprise activated pro-survival and anti-apoptotic signaling leading to insufficient apoptosis and drug resistance. The identification of programmed cell death pathways alternative to apoptosis opens up for possibilities to antagonize apoptosis escape routes. We have earlier shown that acute lymphoblastic leukemia (ALL) harbours a distinct propensity to undergo cell death by RIPK1-dependent necroptosis, activated by small molecule second mitochondria-derived activators of caspase (SMAC) mimetics. Despite demonstrated safety and tolerability of SMAC mimetics in clinical trials, their efficacy as single agent appears still limited, highlighting the need for combinatorial treatments. Here, we investigate so far unexplored regulatory mechanisms of necroptosis and identify targets for interference to augment the necroptotic anti-leukemia response. Ex vivo drug response profiling in a model of the bone marrow microenvironment reveals powerful synergy of necroptosis induction with histone deacetylase inhibition. Subsequent transcriptome analysis and functional in vivo CRISPR screening identify gene regulatory circuitries through the master transcription regulators SP1, p300 and HDAC2 to drive necroptosis. While deletion of SP1 or p300 confers resistance to necroptosis, loss of HDAC2 sensitizes to RIPK1-dependent cell death by SMAC mimetics. Consequently, our data inform strong in vivo anti-leukemic activity of combinatorial necroptosis induction and HDAC inhibition in patient-derived human leukemia models. Thus, transcriptional dependency of necroptosis activation is a key regulatory mechanism that identifies novel targets for interference, pointing out a strategy to exploit alternative non-apoptotic cell death pathways to eradicate resistant disease.

Following the introduction of tyrosine kinase inhibitors (TKI), the number of patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) for chronic phase chronic myeloid leukemia (CP-CML) has dramatically decreased. Imatinib was the 1st TKI introduced into the clinical arena, predominantly utilized in the 1st line setting. In cases of insufficient response, resistance, or intolerance, CML patients can subsequently be treated with a 2nd, 3rdor 4th generation TKI. However, despite the approval of 1st, 2nd, 3rd, 4th generation TKI allo-HSCT still remains indicated for a minority of CML patients. Here, we discuss the indications in the era of TKI through different cases representing the clinical situations for which allo-HSCT remains the best option. We also propose our transplant strategy to decrease transplant-related morbidity, particularly graft-versus-host disease (GvHD), and mortality in the particular context of CML, a disease that is one of the most sensitive to immune cellular therapy, allowing the use of a combination of donor lymphocyte infusion (DLI) and TKI for post-transplant molecular progression.