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Simple SummaryAcute myeloid leukemia (AML) is a challenging blood cancer to treat,with only about 24% of patients surviving for 5 years after diagnosis. A key challenge is that AML cells stick to normal cells in the bone marrow (BM),and these BM cells protect them from chemotherapy. The aim of this project is to find drugs that disrupt AML cell adherence to BM cells and release them into the blood,where chemotherapy will be more effective. To achieve this,we have created a model of adhesive BM and shown that it mimics the drug resistance seen clinically. We have used the model as a testing platform for drugs that disrupt AML cell adhesion. We have shown that the combined targeting of CD44 and FAK,using anti-CD44 and the clinical-grade FAK inhibitor defactinib,inhibits the adhesion of the most primitive AML cells that are associated with drug resistance and disease relapse. AbstractBackground/Objectives: Acute myeloid leukemia (AML) is an aggressive neoplasm. Although most patients respond to induction therapy,they commonly relapse due to recurrent disease in the bone marrow microenvironment (BMME). So,the disruption of the BMME,releasing tumor cells into the peripheral circulation,has therapeutic potential. Methods: Using both primary donor AML cells and cell lines,we developed an in vitro co-culture model of the AML BMME. We used this model to identify the most effective agent(s) to block AML cell adherence and reverse adhesion-mediated treatment resistance. Results: We identified that anti-CD44 treatment significantly increased the efficacy of cytarabine. However,some AML cells remained adhered,and transcriptional analysis identified focal adhesion kinase (FAK) signaling as a contributing factor; the adhered cells showed elevated FAK phosphorylation that was reduced by the FAK inhibitor,defactinib. Importantly,we demonstrated that anti-CD44 and defactinib were highly synergistic at diminishing the adhesion of the most primitive CD34high AML cells in primary autologous co-cultures. Conclusions: Taken together,we identified anti-CD44 and defactinib as a promising therapeutic combination to release AML cells from the chemoprotective AML BMME. As anti-CD44 is already available as a recombinant humanized monoclonal antibody,the combination of this agent with defactinib could be rapidly tested in AML clinical trials. View Publication

Atherosclerosis,a major contributor to cardiovascular disease,involves lipid accumulation and inflammatory processes in arterial walls,with oxidized low-density lipoprotein (OxLDL) playing a central role. OxLDL is increased during aging and stimulates monocyte transformation into foam cells and induces metabolic reprogramming and pro-inflammatory responses,accelerating atherosclerosis progression and contributing to other age-related diseases. This study investigated the effects of Mdivi-1,a mitochondrial fission inhibitor,and S1QEL,a selective complex I-associated reactive oxygen species (ROS) inhibitor,on OxLDL-induced responses in monocytes. Healthy monocytes isolated from participants were treated with OxLDL,with or without Mdivi-1 or S1QEL,and assessed for metabolic shifts,inflammatory cytokine expression,foam cell formation,and ROS production. OxLDL treatment elevated glycolytic activity (ECAR) and expression of pro-inflammatory cytokines IL1B and CXCL8,promoting foam cell formation and mitochondrial ROS (mtROS) production. Mdivi-1 and S1QEL effectively reduced OxLDL-induced glycolytic reprogramming,inflammatory cytokine levels,and foam cell formation while limiting mtROS. These findings suggest that both Mdivi-1 and S1QEL modulate key monocyte responses to OxLDL,providing insights into potential therapeutic approaches for age-related diseases. View Publication

Chromosome instability is a prevalent vulnerability of cancer cells that has yet to be fully exploited therapeutically. To identify genes uniquely essential to chromosomally unstable cells,we mined the Cancer Dependency Map for genes essential in tumor cells with high levels of copy number aberrations. We identify and validate KIF18A,a mitotic kinesin,as a vulnerability of chromosomally unstable cancer cells. Knockdown of KIF18A leads to mitotic defects and reduction of tumor growth. Screening of a chemical library for inhibitors of KIF18A enzymatic activity identified a hit that was optimized to yield VLS-1272,which is orally bioavailable,potent,ATP non-competitive,microtubule-dependent,and highly selective for KIF18A versus other kinesins. Inhibition of KIF18A’s ATPase activity prevents KIF18A translocation across the mitotic spindle,resulting in chromosome congression defects,mitotic cell accumulation,and cell death. Profiling VLS-1272 across >100 cancer cell lines demonstrates that the specificity towards cancer cells with chromosome instability differentiates KIF18A inhibition from other clinically tested anti-mitotic drugs. Treatment of tumor xenografts with VLS-1272 results in mitotic defects leading to substantial,dose-dependent inhibition of tumor growth. The strong biological rationale,robust preclinical data,and optimized compound properties enable the clinical development of a KIF18A inhibitor in cancers with high chromosomal instability. Chromosomal instability occurs frequently in cancer,making it an attractive therapeutic target. Here,the authors identify KIF18A as a targetable vulnerability of cancer cells with chromosomal instability and target this using VLS-1272,a selective KIF18A inhibitor. View Publication

Cells die by necrosis due to excessive chemical or thermal stress,leading to plasma membrane rupture,release of intracellular components and severe inflammation. The clearance of necrotic cell debris is crucial for tissue recovery and injury resolution,however,the underlying mechanisms are still poorly understood,especially in vivo. This study examined the role of complement proteins in promoting clearance of necrotic cell debris by leukocytes and their influence on liver regeneration. We found that independently of the type of necrotic liver injury,either acetaminophen (APAP) overdose or thermal injury,complement proteins C1q and (i)C3b were deposited specifically on necrotic lesions via the activation of the classical pathway. Importantly,C3 deficiency led to a significant accumulation of necrotic debris and impairment of liver recovery in mice,which was attributed to decreased phagocytosis of debris by recruited neutrophils in vivo. Monocytes and macrophages also took part in debris clearance,although the necessity of C3 and CD11b was dependent on the specific type of necrotic liver injury. Using human neutrophils,we showed that absence of C3 or C1q caused a reduction in the volume of necrotic debris that is phagocytosed,indicating that complement promotes effective debris uptake in mice and humans. Moreover,internalization of opsonized debris induced the expression of pro-resolving genes in a C3-dependent manner,supporting the notion that debris clearance favors the resolution of inflammation. In summary,complement activation at injury sites is a pivotal event for necrotic debris clearance by phagocytes and determinant for efficient recovery from tissue injury. Graphical Abstract View Publication

IntroductionAnandamide (AEA) is an endocannabinoid that has recently been recognized as a regulator of various inflammatory diseases as well as cancer. While AEA was thought to predominantly engage cannabinoid (CB) receptors,recent findings suggest that,given its protective anti-inflammatory role in pathological conditions,anandamide may engage not only CB receptors.MethodsIn this study,we studied the role of exogenous AEA in a mouse AirPouch model of acute inflammation by examining immune cell infiltrates by flow cytometry. Human primary immune cells were used to validate findings towards immune cell activation and migration by flow cytometry and bead-based ELISA.ResultsWe found that AEA decreases the acute infiltration of myeloid cells including granulocytes and monocytes into the inflamed area,but unexpectedly increases the number of T cells at the site of inflammation. This was related to AEA signaling through nuclear receptor subfamily 4A (NR4A) transcription factors rather than CB receptors. Exploring regulatory mechanisms in the human system,we found that AEA broadly inhibits the migratory capacity of immune cells,arguing for blocked emigration of T cells from the inflamed tissue. Taking a closer look at the impact of AEA on T cells revealed that AEA profoundly alters the activation and exhaustion status of CD4+ T and CD8+ T cells,thereby strongly inhibiting TH17 responses,while not altering TH1 differentiation.DiscussionThese data suggest that AEA has the potential to block chronic inflammation without influencing crucial anti-viral and anti-microbial immune defense mechanisms,and may therefore be an attractive molecule to interfere with the establishment of chronic inflammation. View Publication

Although chimeric antigen receptor (CAR) T cells are effective against B-lineage malignancies,post-CAR relapse is common,and efficacy in other tumors is limited. These challenges may be addressed through rational manipulations to control CAR T cell function. Here we examine the impact of cognate T cell antigen experience on subsequent CD8+ CAR T cell activity. Prior antigen encounter resulted in superior effector function against leukemia expressing low target antigen density at the expense of reduced proliferative capacity and susceptibility to dysfunction at limiting CAR doses. Distinctive temporal transcriptomic and epigenetic profiles in naive-derived and memory-derived CAR T cells identified RUNX family transcription factors as potential targets to augment the function of naive-derived CD8+ CAR T cells. RUNX2 overexpression enhanced antitumor efficacy of mouse CAR T cells,dependent on prior cell state,and heightened human CAR T cell functions. Our data demonstrate that prior antigen experience of CAR T cells determines functional attributes and amenability to transcription factor-mediated functional enhancement. Here,Fry and colleagues examine the impact of antigen experience on subsequent CD8+ CAR T cell activity during the antileukemia response and show that RUNX2 overexpression enhances antitumor activity of these cells. View Publication

Donor-specific antibodies (DSAs) targeting mismatched human leukocyte antigen (HLA) molecules are one of the principal threats to long-term graft survival in solid organ transplantation. However,many patients with long-term circulating DSAs do not manifest rejection responses,suggesting a degree of heterogeneity in their pathogenicity and related functional activity. Immunologic risk stratification of transplant recipients is complicated by challenges intrinsic to defining alloantibody responses that are potentially pathogenic versus those that are not. Thus,a comprehensive understanding of how human alloantibodies target and interact with donor HLA molecules is vital for the development and evaluation of new strategies aimed at reducing antibody-mediated rejection responses. In this study,we employ hydrogen–deuterium exchange–mass spectrometry (HDX–MS),molecular dynamics (MD) simulations,and advanced biochemical and biophysical methodologies to thoroughly characterize a panel of human monoclonal alloantibodies and define the influence of Fc-region biology,antibody binding kinetics,target antigen density,and structural characteristics on their ability to potentiate the forms of immune effector mechanisms that are strongly implicated in transplant rejection. Our findings have significant implications for our understanding of the key biological determinants that underlie the pathogenicity or lack thereof of human alloantibodies. View Publication

IntroductionUpon infection,T cell-driven B cell responses in GC reactions induce memory B cells and antibody-secreting cells that secrete protective antibodies. How formation of specifically long-lived plasma cells is regulated via the interplay between specific B and CD4+ T cells is not well understood. Generally,antibody levels decline over time after clearance of the primary infection.MethodIn this study,convalescent individuals with stable RBD antibody levels (n=14,“sustainers”) were compared with donors (n=13) with the greatest antibody decline from a cohort of 132. To investigate the role of the cellular immune compartment in the maintenance of antibody levels,SARS-CoV-2-specific responses at 4 to 6 weeks post-mild COVID-19 infection were characterized using deep immune profiling.ResultsBoth groups had similar frequencies of total SARS-CoV-2-specific B and CD4+ T cells. Sustainers had fewer Spike-specific IgG+ memory B cells early after infection and increased neutralizing capacity of RBD antibodies over time,unlike the declining group. However,declining IgG titers correlated with lower frequency of Spike-specific CD4+ T cells.ConclusionThese data suggest that “sustainers” have unique dynamics of GC reactions,yield different outputs of terminally differentiating cells,and improve the quality of protective antibodies over time. This study helps identify factors controlling formation of long-lived PC and sustained antibody responses. View Publication

IntroductionSystemic lupus erythematosus (SLE) is an autoimmune disease characterized by an overactive immune response,particularly involving excessive production of type I interferons. This overproduction is driven by the phosphorylation of IRF7,a crucial factor in interferon gene activation. Current treatments for SLE are often not very effective and can have serious side effects.MethodsOur study introduces clobenpropit,a histamine analogue,as a potential new therapy targeting the CXCR4 receptor to reduce IRF7 phosphorylation and subsequent interferon production. We employed various laboratory techniques to investigate how clobenpropit interacts with CXCR4 and its effects on immune cells from healthy individuals and SLE patients.ResultsClobenpropit binds effectively to CXCR4,significantly inhibiting IRF7 phosphorylation and reducing interferon production. Additionally,clobenpropit lowered levels of pro-inflammatory cytokines in a mouse model of lupus,demonstrating efficacy comparable to the standard treatment,prednisolone.DiscussionThese results suggest that clobenpropit could be a promising new treatment for SLE,offering a targeted approach with potential advantages over current therapies. View Publication

The lungs of people with cystic fibrosis (PwCF) are characterized by recurrent bacterial infections and inflammation. Infections in cystic fibrosis (CF) are left unresolved despite excessive neutrophil infiltration. The role of CFTR in neutrophils is not fully understood. In this study,we aimed to assess which antimicrobial functions are directly impaired by loss of CFTR function in neutrophils. In order to do so,we used a specific inhibitor of CFTR ion channel activity,inh-172. CF neutrophils from PwCF harboring severe CFTR mutations were additionally isolated to further discern CFTR-specific functional defects. We evaluated phagocytosis,reactive oxygen species (ROS) production,neutrophil elastase (NE) and myeloperoxidase (MPO) exocytosis and bacterial killing. The inh-172 model identified decreased acidification of the phagosome,increased bacterial survival and decreased ROS production upon stimulation. In PwCF neutrophils,we observed reduced degranulation of both NE and MPO. When co-culturing neutrophils with CF sputum supernatant and airway epithelial cells,the extent of phagocytosis was reduced,underscoring the importance of recreating an inflammatory environment as seen in PwCF lungs to model immune responses in vitro. Despite low CFTR expression in blood neutrophils,functional defects were found in inh-172-treated and CF neutrophils. The inh-172 model disregards donor variability and allows pinpointing neutrophil functions directly impaired by dysfunctional CFTR.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-024-82535-z. View Publication

Achieving the precise targeting of lentiviral vectors (LVs) to specific cell populations is crucial for effective gene therapy,particularly in cancer treatment where the modulation of the tumor microenvironment can enhance anti-tumor immunity. Programmed cell death protein 1 (PD-1) is overexpressed on activated tumor-infiltrating T lymphocytes,including regulatory T cells that suppress immune responses via FOXP3 expression. We developed PD1-targeted LVs by incorporating the anti-PD1 nanobody nb102c3 into receptor-blinded measles virus H and VSV-Gmut glycoproteins. We assessed the retargeting potential of nb102c3 and evaluated transduction efficiency in activated T lymphocytes. FOXP3 expression was suppressed using shRNA delivered by these LVs. Our results demonstrate that PD1-targeted LVs exerted pronounced tropism towards PD1+ cells,enabling the selective transduction of activated T lymphocytes while sparing naive T cells. The suppression of FOXP3 in Tregs reduced their suppressive activity. PD1-targeted glycoprotein H provided greater specificity,whereas the VSV-Gmut,together with the anti-PD1 pseudoreceptor,achieved higher viral titers but was less selective. Our study demonstrates that PD1-targeted LVs may offer a novel strategy to modulate immune responses within the tumor microenvironment with the potential for developing new therapeutic strategies aimed at enhancing anti-tumor immunity. View Publication

Pathobionts have evolved many strategies to coexist with the host,but how immune evasion mechanisms contribute to the difficulty of developing vaccines against pathobionts is unclear. Meanwhile,Staphylococcus aureus (SA) has resisted human vaccine development to date. Here we show that prior SA exposure induces non-protective CD4+ T cell imprints,leading to the blunting of protective IsdB vaccine responses. Mechanistically,these SA-experienced CD4+ T cells express IL-10,which is further amplified by vaccination and impedes vaccine protection by binding with IL-10Rα on CD4+ T cell and inhibit IL-17A production. IL-10 also mediates cross-suppression of IsdB and sdrE multi-antigen vaccine. By contrast,the inefficiency of SA IsdB,IsdA and MntC vaccines can be overcome by co-treatment with adjuvants that promote IL-17A and IFN-γ responses. We thus propose that IL-10 secreting,SA-experienced CD4+ T cell imprints represent a staphylococcal immune escaping mechanism that needs to be taken into consideration for future vaccine development. Mechanisms of inefficient vaccine protection against pathobionts such as S. aureus (SA) are still unclear. Here the authors show that prior SA exposure induces non-protective CD4+ T cells,which impair IsdB vaccine protection by IL-10 secretion and IL-17A suppression,whereas IL-17A promoting adjuvant CAF01 overcomes this dilemma. View Publication