Increased Cell Surface Expression Research Articles

Glial cholesterol redistribution in hypoxic injury in vitro influences oligodendrocyte maturation and myelination

Hypoxic insult to the fetal brain causes loss of vulnerable premyelinating oligodendrocytes and arrested oligodendrocyte differentiation. Astrocytes influence oligodendrocyte differentiation and the astrocytic response to hypoxia could affect oligodendrocyte maturation under hypoxia. To identify pathways by which astrocytes influence oligodendroglial maturation in hypoxic injury, human fetal neural stem cell-derived astrocytes were exposed to 0.2 % oxygen for 48 hours. Transcriptomic analysis revealed the upregulation of the cholesterol-biosynthesis pathway in hypoxia-exposed astrocytes. Hypoxia-exposed primary astrocytes and astrocytic cell line (SVG) showed increased expression of hydroxy-methyl-glutaryl-CoA reductase (HMGCR), squalene epoxidase (SQLE), apolipoprotein E (apoE) and ATP-binding cassette transporter 1 (ABCA1) on qPCR and Western blot. Hypoxic SVG also showed increased cholesterol content in cells and culture supernatants and increased cell surface expression of ABCA1. Interestingly hypoxia-exposed premyelinating oligodendrocytes (Mo3.13) showed reduced cholesterol along with decreased expression of HMGCR and SQLE on qPCR and Western blot. Exogenous cholesterol increased the differentiation of Mo3.13 as measured by increased expression of myelin basic protein (MBP) on flow cytometry. Hypoxia exposure resulted in increased cholesterol transport from astrocytes to oligodendrocytes in cocultures with BODIPY-cholesterol labelled SVG and membrane-labelled Mo3.13. As exogenous cholesterol enhanced oligodendrocyte differentiation, our findings indicate that increased cholesterol synthesis by astrocytes and transport to oligodendrocytes could supplement oligodendroglial maturation in conditions of hypoxic brain injury in neonates.

Parainfluenza Virus 5 V Protein Blocks Interferon Gamma-Mediated Upregulation of NK Cell Inhibitory Ligands and Improves NK Cell Killing of Neuroblastoma Cells.

Natural killer (NK) cells can be effective immunotherapeutic anti-cancer agents due to their ability to selectively target and kill tumor cells. This activity is modulated by the interaction of NK cell receptors with inhibitory ligands on the surface of target cells. NK cell inhibitory ligands can be upregulated on tumor cell surfaces in response to interferon-gamma (IFN-γ), a cytokine which is produced by activated NK cells. We hypothesized that the resistance of tumor cells to NK cell killing could be overcome by expression of the parainfluenza virus 5 (PIV5) V protein, which has known roles in blocking IFN-γ signaling. This was tested with human PM21-NK cells produced through a previously developed particle-based method which yields superior NK cells for immunotherapeutic applications. Infection of human SK-N-SH neuroblastoma cells with PIV5 blocked IFN-γ-mediated upregulation of three NK cell inhibitory ligands and enhanced in vitro killing of these tumor cells by PM21-NK cells. SK-N-SH cells transduced to constitutively express the V protein alone were resistant to IFN-γ-mediated increases in cell surface expression of NK cell inhibitory ligands. Real-time in vitro cell viability assays demonstrated that V protein expression in SK-N-SH cells was sufficient to increase PM21-NK cell-mediated killing. Toward a potential therapeutic application, transient lentiviral delivery of the V gene also enhanced PM21-NK cell killing in vitro. Our results provide the foundation for novel therapeutic applications of V protein expression in combination with ex vivo NK cell therapy to effectively increase the killing of tumor cells.

A Conserved Intramolecular Ion-Pair Plays a Critical but Divergent Role in Regulation of Dimerization and Transport Function among the Monoamine Transporters.

The monoamine transporters, including the serotonin transporter (SERT), dopamine transporter (DAT), and norepinephrine transporter (NET), are the therapeutic targets for the treatment of many neuropsychiatric disorders. Despite significant progress in characterizing the structures and transport mechanisms of these transporters, the regulation of their transport functions through dimerization or oligomerization remains to be understood. In the present study, we identified a conserved intramolecular ion-pair at the third extracellular loop (EL3) connecting TM5 and TM6 that plays a critical but divergent role in the modulation of dimerization and transport functions among the monoamine transporters. The disruption of the ion-pair interactions by mutations induced a significant spontaneous cross-linking of a cysteine mutant of SERT and an increase in cell surface expression but with an impaired specific transport activity. On the other hand, similar mutations of the corresponding ion-pair residues in both DAT and NET resulted in an opposite effect on their oxidation-induced dimerization, cell surface expression, and transport function. Reversible biotinylation experiments indicated that the ion-pair mutations slowed down the internalization of SERT but stimulated the internalization of DAT. In addition, cysteine accessibility measurements for monitoring SERT conformational changes indicated that substitution of the ion-pair residues resulted in profound effects on the rate constants for cysteine modification in both the extracellular and cytoplasmatic substrate permeation pathways. Furthermore, molecular dynamics simulations showed that the ion-pair mutations increased the interfacial interactions in a SERT dimer but decreased it in a DAT dimer. Taken together, we propose that the transport function is modulated by the equilibrium between monomers and dimers on the cell surface, which is regulated by a potential compensatory mechanism but with different molecular solutions among the monoamine transporters. The present study provided new insights into the structural elements regulating the transport function of the monoamine transporters through their dimerization.

Disulfiram Reduces Atherosclerosis and Enhances Efferocytosis, Autophagy, and Atheroprotective Gut Microbiota in Hyperlipidemic Mice.

Pyroptosis executor GsdmD (gasdermin D) promotes atherosclerosis in mice and humans. Disulfiram was recently shown to potently inhibit GsdmD, but the invivo efficacy and mechanism of disulfiram's antiatherosclerotic activity is yet to be explored. We used human/mouse macrophages, endothelial cells, and smooth muscle cells and a hyperlipidemic mouse model of atherosclerosis to determine disulfiram antiatherosclerotic efficacy and mechanism. The effects of disulfiram on several atheroprotective pathways such as autophagy, efferocytosis, phagocytosis, and gut microbiota were determined. Atomic force microscopy was used to determine the effects of disulfiram on the biophysical properties of the plasma membrane of macrophages. Disulfiram-fed hyperlipidemic apolipoprotein E-/- mice showed significantly reduced interleukin-1β release upon invivo Nlrp3 (NLR family pyrin domain containing 3) inflammasome activation. Disulfiram-fed mice showed smaller atherosclerotic lesions (~27% and 29% reduction in males and females, respectively) and necrotic core areas (~50% and 46% reduction in males and females, respectively). Disulfiram induced autophagy in macrophages, smooth muscle cells, endothelial cells, hepatocytes/liver, and atherosclerotic plaques. Disulfiram modulated other atheroprotective pathways (eg,efferocytosis, phagocytosis) and gut microbiota. Disulfiram-treated macrophages showed enhanced phagocytosis/efferocytosis, with the mechanism being a marked increase in cell-surface expression of efferocytic receptor MerTK. Atomic force microscopy analysis revealed altered biophysical properties of disulfiram-treated macrophages, showing increased order-state of plasma membrane and increased adhesion strength. Furthermore, 16sRNA sequencing of disulfiram-fed hyperlipidemic mice showed highly significant enrichment in atheroprotective gut microbiota Akkermansia and a reduction in atherogenic Romboutsia species. Taken together, our data show that disulfiram can simultaneously modulate several atheroprotective pathways in a GsdmD-dependent as well as GsdmD-independent manner.

Combining CRISPR-Cas9 and TCR exchange to generate a safe and efficient cord blood-derived T cell product for pediatric relapsed AML

BackgroundHematopoietic cell transplantation (HCT) is an effective treatment for pediatric patients with high-risk, refractory, or relapsed acute myeloid leukemia (AML). However, a large proportion of transplanted patients eventually die due...

Abstract 1958: EGFR and mTOR signaling facilitate RET-independent resistance to selective RET-TKIs

Abstract RET fusions are an oncogenic driver mutation occurring in 1-2% non-small cell lung cancer (NSCLC). Currently, RET-selective tyrosine kinase inhibitors (TKIs) selpercatinib and pralsetinib are approved for this patient population, demonstrating favorable antitumor activity and safety profiles in advanced RET fusion-positive NSCLC. However, tumors eventually become refractory to selective RET inhibitor monotherapy. We sought to identify signaling pathways which mediate RET-independent acquired resistance to RET inhibitors and effective therapeutic combinations to overcome resistance. Using LC-2/ad (CCDC6-RET) NSCLC cells, we assessed the expression and activation of critical signaling pathways at a proteomic level following RET knockdown using reverse-phase protein array. RET knockdown resulted in rapidly increased adaptive upregulation of EGFR, HER2, MET, mTOR and MEK pathway signaling; observations were confirmed by Western Blotting. To determine whether EGFR or MET signaling facilitate RET inhibitor resistance, LC-2/ad and NCCE-TH1101 (KIF5B-RET) NSCLC cells were treated with increasing concentrations of selpercatinib or pralsetinib with or without ligands for these receptors, EGF or HGF respectively, and after five days cell viability was measured by CellTiter Glo. EGFR and MET signaling promoted RET TKI resistance in both cell lines. Next, to evaluate whether blockade of EGFR or MET signaling could enhance the activity of RET inhibitors, we treated LC-2/ad and NCCE-TH1101 cells with RET TKIs alone or in combination with the EGFR TKI erlotinib or poziotinib, or the MET inhibitor SU11274. We observed an additive effect with EGFR but not MET inhibitors when combined with RET TKIs. Western blot analysis revealed that EGFR signaling could reactivate mTOR and MAPK signaling after RET TKI treatment. Therefore, we next tested whether inhibition of these downstream pathways might enhance RET TKI sensitivity. We observed that treatment of LC-2/ad and NCCE-TH1101 cells with an mTOR inhibitor (everolimus) or a MEK inhibitor (trametinib) in combination with RET TKIs increased the anti-tumor activity or RET inhibitors. Finally, we established cells with acquired resistance to selpercatinib and pralsetinib. RET TKI resistant cells did not harbor secondary RET fusion mutations but underwent epithelial to mesenchymal transition and exhibited pan-RET inhibitor resistance. Moreover, RET TKI resistant cells showed increased cell surface expression of EGFR and MET by flow cytometry. RET TKI resistant cells were sensitive to mTOR or MEK inhibitors in combination with RET TKIs. Collectively, our findings indicate that in RET-fusion positive NSCLC tumor cells, activation of bypass pathways including the EGFR, MAPK, mTOR pathways may facilitate RET inhibitor resistance and that blockade of bypass pathways may enhance the efficacy of selective RET inhibitors and overcome acquired RET TKI resistance. Citation Format: Tomohiro Takehara, Monique B. Nilsson, Ximeng Liu, Hibiki Udagawa, Naoto Morikawa, Alissa Poteete, Junqin He, Xiaoxing Yu, Thiru Arumugam, Koichi Goto, John V. Heymach. EGFR and mTOR signaling facilitate RET-independent resistance to selective RET-TKIs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1958.

Enhancement of Haloperidol-Induced Catalepsy by GPR143, an L-Dopa Receptor, in Striatal Cholinergic Interneurons.

Dopamine neurons play crucial roles in pleasure, reward, memory, learning, and fine motor skills and their dysfunction is associated with various neuropsychiatric diseases. Dopamine receptors are the main target of treatment for neurologic and psychiatric disorders. Antipsychotics that antagonize the dopamine D2 receptor (DRD2) are used to alleviate the symptoms of these disorders but may also sometimes cause disabling side effects such as parkinsonism (catalepsy in rodents). Here we show that GPR143, a G-protein-coupled receptor for L-3,4-dihydroxyphenylalanine (L-DOPA), expressed in striatal cholinergic interneurons enhances the DRD2-mediated side effects of haloperidol, an antipsychotic agent. Haloperidol-induced catalepsy was attenuated in male Gpr143 gene-deficient (Gpr143-/y ) mice compared with wild-type (Wt) mice. Reducing the endogenous release of L-DOPA and preventing interactions between GPR143 and DRD2 suppressed the haloperidol-induced catalepsy in Wt mice but not Gpr143-/y mice. The phenotypic defect in Gpr143-/y mice was mimicked in cholinergic interneuron-specific Gpr143-/y (Chat-cre;Gpr143flox/y ) mice. Administration of haloperidol increased the phosphorylation of ribosomal protein S6 at Ser240/244 in the dorsolateral striatum of Wt mice but not Chat-cre;Gpr143flox/y mice. In Chinese hamster ovary cells stably expressing DRD2, co-expression of GPR143 increased cell surface expression level of DRD2, and L-DOPA application further enhanced the DRD2 surface expression. Shorter pauses in cholinergic interneuron firing activity were observed after intrastriatal stimulation in striatal slice preparations from Chat-cre;Gpr143flox/y mice compared with those from Wt mice. Together, these findings provide evidence that GPR143 regulates DRD2 function in cholinergic interneurons and may be involved in parkinsonism induced by antipsychotic drugs.

Anti-PD-L1 therapy altered inflammation but not survival in a lethal murine hepatitis virus-1 pneumonia model.

Because prior immune checkpoint inhibitor (ICI) therapy in cancer patients presenting with COVID-19 may affect outcomes, we investigated the beta-coronavirus, murine hepatitis virus (MHV)-1, in a lethal pneumonia model in the absence (Study 1) or presence of prior programmed cell death ligand-1 (PD-L1) antibody (PD-L1mAb) treatment (Study 2). In Study 1, animals were inoculated intratracheally with MHV-1 or vehicle and evaluated at day 2, 5, and 10 after infection. In Study 2, uninfected or MHV-1-infected animals were pretreated intraperitoneally with control or PD-L1-blocking antibodies (PD-L1mAb) and evaluated at day 2 and 5 after infection. Each study examined survival, physiologic and histologic parameters, viral titers, lung immunophenotypes, and mediator production. Study 1 results recapitulated the pathogenesis of COVID-19 and revealed increased cell surface expression of checkpoint molecules (PD-L1, PD-1), higher expression of the immune activation marker angiotensin converting enzyme (ACE), but reduced detection of the MHV-1 receptor CD66a on immune cells in the lung, liver, and spleen. In addition to reduced detection of PD-L1 on all immune cells assayed, PD-L1 blockade was associated with increased cell surface expression of PD-1 and ACE, decreased cell surface detection of CD66a, and improved oxygen saturation despite reduced blood glucose levels and increased signs of tissue hypoxia. In the lung, PD-L1mAb promoted S100A9 but inhibited ACE2 production concomitantly with pAKT activation and reduced FOXO1 levels. PD-L1mAb promoted interferon-γ but inhibited IL-5 and granulocyte-macrophagecolony-stimulating factor (GM-CSF) production, contributing to reduced bronchoalveolar lavage levels of eosinophils and neutrophils. In the liver, PD-L1mAb increased viral clearance in association with increased macrophage and lymphocyte recruitment and liver injury. PD-L1mAb increased the production of virally induced mediators of injury, angiogenesis, and neuronal activity that may play role in COVID-19 and ICI-related neurotoxicity. PD-L1mAb did not affect survival in this murine model. In Study 1 and Study 2, ACE was upregulated and CD66a and ACE2 were downregulated by either MHV-1 or PD-L1mAb. CD66a is not only the MHV-1 receptor but also an identified immune checkpoint and a negative regulator of ACE. Crosstalk between CD66a and PD-L1 or ACE/ACE2 may provide insight into ICI therapies. These networks may also play role in the increased production of S100A9 and neurological mediators in response to MHV-1 and/or PD-L1mAb, which warrant further study. Overall, these findings support observational data suggesting that prior ICI treatment does not alter survival in patients presenting with COVID-19.

Circulating IL-17F, but not IL-17A, is elevated in severe COVID-19 and leads to an ERK1/2 and p38 MAPK-dependent increase in ICAM-1 cell surface expression and neutrophil adhesion on endothelial cells.

Severe COVID-19 is associated with neutrophilic inflammation and immunothrombosis. Several members of the IL-17 cytokine family have been associated with neutrophilic inflammation and activation of the endothelium. Therefore, we investigated whether these cytokines were associated with COVID-19. We investigated the association between COVID-19 and circulating plasma levels of IL-17 cytokine family members in participants to the Biobanque québécoise de la COVID-19 (BQC19), a prospective observational cohort and an independent cohort from Western University (London, Ontario). We measured the in vitro impact of IL-17F on intercellular adhesion molecule 1 (ICAM-1) cell surface expression and neutrophil adhesion on endothelial cells in culture. The contribution of two Mitogen Activated Protein Kinase (MAPK) pathways was determined using small molecule inhibitors PD184352 (a MKK1/MKK2 inhibitor) and BIRB0796 (a p38 MAPK inhibitor). We found increased IL-17D and IL-17F plasma levels when comparing SARS-CoV-2-positive vs negative hospitalized participants. Moreover, increased plasma levels of IL-17D, IL-17E and IL-17F were noted when comparing severe versus mild COVID-19. IL-17F, but not IL-17A, was significantly elevated in people with COVID-19 compared to healthy controls and with more severe disease. In vitro work on endothelial cells treated with IL-17F for 24h showed an increase cell surface expression of ICAM-1 accompanied by neutrophil adhesion. The introduction of two MAPK inhibitors significantly reduced the binding of neutrophils while also reducing ICAM-1 expression at the surface level of endothelial cells, but not its intracellular expression. Overall, these results have identified an association between two cytokines of the IL-17 family (IL-17D and IL-17F) with COVID-19 and disease severity. Considering that IL-17F stimulation promotes neutrophil adhesion to the endothelium in a MAPK-dependent manner, it is attractive to speculate that this pathway may contribute to pathogenic immunothrombosis in concert with other molecular effectors.

UBE3C Facilitates the ER-Associated and Peripheral Degradation of Misfolded CFTR.

The ubiquitin E3 ligase UBE3C promotes the proteasomal degradation of cytosolic proteins and endoplasmic reticulum (ER) membrane proteins. UBE3C is proposed to function downstream of the RNF185/MBRL ER-associated degradation (ERAD) branch, contributing to the ERAD of select membrane proteins. Here, we report that UBE3C facilitates the ERAD of misfolded CFTR, even in the absence of both RNF185 and its functional ortholog RNF5 (RNF5/185). Unlike RNF5/185, UBE3C had a limited impact on the ubiquitination of misfolded CFTR. UBE3C knockdown (KD) resulted in an additional increase in the functional ∆F508-CFTR channels on the plasma membrane when combined with the RNF5/185 ablation, particularly in the presence of clinically used CFTR modulators. Interestingly, although UBE3C KD failed to attenuate the ERAD of insig-1, it reduced the ERAD of misfolded ∆Y490-ABCB1 and increased cell surface expression. UBE3C KD also stabilized the mature form of ∆F508-CFTR and increased the cell surface level of T70-CFTR, a class VI CFTR mutant. These results suggest that UBE3C plays a vital role in the ERAD of misfolded CFTR and ABCB1, even within the RNF5/185-independent ERAD pathway, and it may also be involved in maintaining the peripheral quality control of CFTR.

CTIM-10. A SURGICAL WINDOW-OF-OPPORTUNITY CLINICAL TRIAL EVALUATING THE PCSK9 INHIBITOR EVOLOCUMAB IN PATIENTS WITH GLIOMA

Abstract Gliomas evade the immune system by downregulating cell surface expression of major histocompatibility class (MHC)-I. Antagonism of proprotein convertase subtilisin/kexin type 9 (PCSK9) increases MHC-I expression and can enhance checkpoint inhibition in vivo. Evolocumab is an FDA approved monoclonal antibody (mAb) for hyperlipidemia that inhibits PCSK9. However, large constructs such as mAbs typically have limited penetrance across the blood-brain-barrier. We report the preliminary results of a surgical window-of-opportunity study evaluating if Evolocumab administered subcutaneously pre-preoperatively is detectable in tumor tissue from patients with newly diagnosed or recurrent glioma (PESKe; NCT04937413). Twenty contemporaneous control samples are prospectively collected from patients undergoing craniotomy without receiving Evolocumab. Although non-randomized, these specimens provide valuable information for exploratory comparison of the treated and untreated specimens in terms of drug penetrance and MHC-I expression. To date, 24 patients have been enrolled (M: 14, F: 10) with a median age of 46.5. Of these, 5 received pre-procedure subcutaneous Evolocumab (420mg), while the remaining 19 were analyzed as controls. In treated patients, Evolocumab was detectable via mass spectroscopy (LC-MS/MS) in all analyzed cases, including in tumor tissue from both contrast-enhancing and non-contrast-enhancing regions. Ratios of drug in tumor relative to intra-operative blood were markedly higher in samples from contrast-enhancing regions compared to non-contrast enhancing regions (median ratio of tumor to blood of 0.1503 vs 0.0248 respectively). The tumor proteome was also analyzed using LC-MS/MS to quantitate MHC-I and MHC-II proteins. Initial analysis found increased MHC-I (HLA-A, HLA-B, HLA-C) quantitation via mass spectroscopic analysis of the tumor proteome in treated samples compared to contemporaneous untreated controls. No significant adverse events have been reported in those who received pre-procedure Evolocumab. Ongoing analyses will seek to determine whether increased MHC-I quantities in tumor correspond with increased cell surface expression via immunofluorescence and immunohistochemistry.

Potent in Vitro and In Vivo Efficacy of BYON4413, a Duba-Based Antibody-Drug Conjugate Targeting CD123 in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) and myelodysplasia (MDS) result from a differentiation impairment driving an accumulation of immature myeloid cells in the bone marrow and peripheral blood. A widely reported feature of these neoplastic myeloid cells is an increased cell surface expression of CD123, the IL3 receptor α subunit. This observation has established CD123 as an attractive target for precision therapy. Here, we describe BYON4413, a novel antibody-drug conjugate (ADC) that binds with high affinity to CD123. BYON4413 comprises a humanized IgG1 antibody directed at CD123 that is site-specifically conjugated to Byondis' proprietary duocarmazine linker-drug (LD) technology, ByonZine® and ByonShieLD®. This LD, when cleaved upon internalization and lysosomal routing, releases a potent duocarmycin payload that alkylates DNA, generating damage that results in replication stress and cell death. In vitro studies with AML cell lines demonstrate that BYON4413 is highly effective in eradicating CD123-positive cells while having little impact on CD123-negative cells. Similar results are observed when we test BYON4413 on AML patient-derived BMMCs/PBMCs in ex vivo assays (n=50), indicating that the specificity of BYON4413 cytotoxicity is largely limited to CD123-positive cells. Ex vivo experiments also reveal a stronger potency of BYON4413 in AML patient-derived blasts compared to healthy CD34 + hematopoietic stem/progenitor cells. In vivo PK/PD studies demonstrate that BYON4413 is remarkably efficient at reducing the tumor burden in multiple AML patient- and cell line-derived xenograft models. Studies in non-human primates suggest that BYON4413 has a favorable toxicity profile and a high maximum tolerable dose, features that should enable combination strategies with other oncolytics. In sum, BYON4413 shows great potential to be an effective targeted therapy against AML, MDS, and other CD123 + hematological malignancies such as blastic plasmacytoid dendritic cell neoplasm (BPDCN). Readied with these promising pre-clinical results, we have designed a first-in-human dose-escalation and expansion trial enrolling AML and high-risk MDS patients scheduled to begin in Q12024.

Microglial P2X4 receptors are essential for spinal neurons hyperexcitability and tactile allodynia in male and female neuropathic mice

In neuropathic pain, recent evidence has highlighted a sex-dependent role of the P2X4 receptor in spinal microglia in the development of tactile allodynia following nerve injury. Here, using internalization-defective P2X4mCherryIN knockin mice (P2X4KI), we demonstrate that increased cell surface expression of P2X4 induces hypersensitivity to mechanical stimulations and hyperexcitability in spinal cord neurons of both male and female naive mice. During neuropathy, both wild-type (WT) and P2X4KI mice of both sexes develop tactile allodynia accompanied by spinal neuron hyperexcitability. These responses are selectively associated with P2X4, as they are absent in global P2X4KO or myeloid-specific P2X4KO mice. We show that P2X4 is de novo expressed in reactive microglia in neuropathic WT and P2X4KI mice of both sexes and that tactile allodynia is relieved by pharmacological blockade of P2X4 or TrkB. These results show that the upregulation of P2X4 in microglia is crucial for neuropathic pain, regardless of sex.

The formin DAAM1 regulates the deubiquitinase activity of USP10 and integrin homeostasis

The differentiation of fibroblasts into pathological myofibroblasts during wound healing is characterized by increased cell surface expression of αv-integrins. Our previous studies found that the deubiquitinase (DUB) USP10 removes ubiquitin from αv-integrins, leading to cell surface integrin accumulation, subsequent TGFβ1 activation, and pathological myofibroblast differentiation. In this study, a yeast two-hybrid screen revealed a novel binding partner for USP10, the formin, DAAM1. We found that DAAM1 binds to and inhibits USP10’s DUB activity through the FH2 domain of DAAM1 independent of its actin functions. The USP10/DAAM1 interaction was also supported by proximity ligation assay (PLA) in primary human corneal fibroblasts. Treatment with TGFβ1 significantly increased USP10 and DAAM1 protein expression, PLA signal, and co-localization to actin stress fibers. DAAM1 siRNA knockdown significantly reduced co-precipitation of USP10 and DAAM1 on purified actin stress fibers, and β1- and β5-integrin ubiquitination. This resulted in increased αv-, β1-, and β5-integrin total protein levels, αv-integrin recycling, and extracellular fibronectin (FN) deposition. Together, our data demonstrate that DAAM1 inhibits USP10’s DUB activity on integrins subsequently regulating cell surface αv-integrin localization and FN accumulation.

A “bulldozer” driven by anoxic bacteria for pancreatic cancer chemo-immunotherapy

Immune evasion is a major obstacle for pancreatic ductal adenocarcinoma (PDAC) therapy. Inhibition of autophagy can improve antigen presentation and enlarge immunogenic cell death (ICD) effect to generate a strong anti-tumor immune response. However, abundant extracellular matrix dominated by hyaluronic acid (HA) hinders the deep penetration of autophagy inhibitors and ICD inducers. Herein, an intelligent autophagy inhibitor hydroxychloroquine (HCQ) and chemotherapeutic drug doxorubicin (DOX) co-loaded “bulldozer” (HD@HH/EcN) driven by anoxic bacteria was constructed for PDAC chemo-immunotherapy. Results demonstrated that probiotic Escherichia coli 1917 (EcN) could carry hyaluronidases (HAases)-hybrided albumin nanoparticles (HD@HH) to reach PDAC tumor tissue quickly and accurately. Thereafter, HAases can efficiently cleave the tumor matrix barrier and promote HD@HH/EcN to accumulate at tumor hypoxic core significantly. After that, high level of glutathione (GSH) in tumor microenvironment (TME) induces intermolecular disulfide bond in HD@HH nanoparticles breakage, to precisely release HCQ and DOX. DOX can induce ICD effect. Meanwhile, HCQ can amplify DOX induced ICD effect by inhibiting tumor autophagy, which further increase cell surface expression of major histocompatibility complex class I (MHC-I) and augment recruitment of CD8+ T cell to improve immunosuppressive TME. This study provides a new strategy for PDAC chemo-immunotherapy.

Characterization of expanded γδ T cells from patient with atypical X-linked severe combined immunodeficiency reveals preserved function and IL2RG-mediated signaling

Abnormally high γδ T cell numbers are common among atypical severe combined immunodeficiency (SCID) patients but detailed immunophenotyping and functional characterization of these expanded γδ T cells are limited. We have previously reported atypical SCID phenotype caused by hypomorphic IL2RG c.172C > T;p.(Pro58Ser) variant causing failure in IL2RG (CD132) plasma membrane targeting leading to impaired IL-2 responses in CD4 and CD8 T cells. Our aim was to investigate the phenotype and function of the index patient's abnormally large peripheral γδ T cell population.We found that in contrast to his αβ T cells, the patient's γδ T cells showed normal IL2RG cell surface expression and normal or enhanced IL2RG-mediated signaling. Vδ2+ population was proportionally increased with a preponderance of memory phenotypes and high overall tendency towards perforin expression. The patient's γδ T cells showed enhanced cytotoxicity towards A549 cancer cells. TCRvγ repertoire was versatile but sequencing of IL2RG revealed a novel c.534C>A; p.(Phe178Leu) somatic missense variant restricted to γδ T cells. Over time this variant became predominant in patient's γδ T cells and was enriched during in vitro expansion of patient's γδ T cells, indicating that the clones with this somatic variant may have growth or survival advantage. In silico analysis with DynaMut2 tool indicated that the overall effect of Phe178Leu substitution for IL2RG was predicted to be stabilizing and IL2RG-Pro58Ser/Phe178Leu to be more stable than IL2RG-Pro58Ser variant alone. Furthermore, IL2RG-Pro58Ser/Phe178Leu showed significantly increased cell surface expression when compared to IL2RG-Pro58Ser variant in stable HEK293 cell lines, suggesting that somatic IL2RG p.(Phe178Leu) variant may at least partially rescue the pathogenic effect of germline IL2RG p.(Pro58Ser) variant.In conclusion, our results indicate that expansion of γδ T cells associated with atypical SCID needs further studying and cannot exclusively be deemed as a homeostatic response to low numbers of conventional T cells. (Tuovinen et al., Journal of Clinical Immunology 2022)

Characterization of dominant-negative growth hormone receptor variants reveals a potential therapeutic target for short stature.

Growth hormone insensitivity (GHI) encompasses growth restriction, normal/elevated growth hormone (GH), and low insulin-like growth factor I (IGF1). "Nonclassical" GHI is poorly characterized and is rarely caused by heterozygous dominant-negative (DN) variants located in the intracellular or transmembrane domains of the GH receptor (GHR). We sought to determine the molecular mechanisms underpinning the growth restriction in 2 GHI cases. A custom-made genetic investigative pipeline was exploited to identify the genetic cause of growth restriction in patients with GHI. Nanoluc binary technology (NanoBiT), in vitro splicing assays, western blotting, and flow cytometry, characterized the novel GHR variants. Novel heterozygous GHR variants were identified in 2 unrelated patients with GHI. In vitro splicing assays indicated both variants activated the same alternative splice acceptor site resulting in aberrant splicing and exclusion of 26 base pairs of GHR exon 9. The GHR variants produced truncated receptors and impaired GH-induced GHR signaling. NanoBiT complementation and flow cytometry showed increased cell surface expression of variant GHR homo/heterodimers compared to wild-type (WT) homodimers and increased recombinant human GH binding to variant GHR homo/heterodimers and GH binding protein (GHBP) cleaved from the variant GHRs. The findings demonstrated increased variant GHR dimers and GHBP with resultant GH sequestration. We identified and characterized 2 novel, naturally occurring truncated GHR gene variants. Intriguingly, these DN GHR variants act via the same cryptic splice acceptor site, highlighting impairing GH binding to excess GHBP as a potential therapeutic approach.

Cytoplasmic Tail Truncation Stabilizes S1-S2 Association and Enhances S Protein Incorporation into SARS-CoV-2 Pseudovirions.

Truncations of the cytoplasmic tail (CT) of entry proteins of enveloped viruses dramatically increase the infectivity of pseudoviruses (PVs) bearing these proteins. Several mechanisms have been proposed to explain this enhanced entry, including an increase in cell surface expression. However, alternative explanations have also been forwarded, and the underlying mechanisms for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S protein remain undetermined. Here, we show that the partial or complete deletion of the CT (residues 19 to 35) does not modify SARS-CoV-2 S protein expression on the cell surface when the S2 subunit is measured, whereas it is significantly increased when the S1 subunit is measured. We also show that the higher level of S1 in these CT-truncated S proteins reflects the decreased dissociation of the S1 subunit from the S2 subunit. In addition, we demonstrate that CT truncation further promotes S protein incorporation into PV particles, as indicated by biochemical analyses and cryo-electron microscopy. Thus, our data show that two distinct mechanisms contribute to the markedly increased infectivity of PVs carrying CT-truncated SARS-CoV-2 S proteins and help clarify the interpretation of the results of studies employing such PVs. IMPORTANCE Various forms of PVs have been used as tools to evaluate vaccine efficacy and study virus entry steps. When PV infectivity is inherently low, such as that of SARS-CoV-2, a CT-truncated version of the viral entry glycoprotein is widely used to enhance PV infectivity, but the mechanism underlying this enhanced PV infectivity has been unclear. Here, our study identified two mechanisms by which the CT truncation of the SARS-CoV-2 S protein dramatically increases PV infectivity: a reduction of S1 shedding and an increase in S protein incorporation into PV particles. An understanding of these mechanisms can clarify the mechanistic bases for the differences observed among various assays employing such PVs.

Putative Predictors of Response to WU-NK-101, an Allogeneic, Enhanced Memory (ML) Natural Killer (NK) Cell Therapy Product, for Relapsed/Refractory (R/R) Acute Myeloid Leukemia (AML)

Strategies to enhance NK-cell activity prior to adoptive transfer into patients with AML have yielded inconsistent clinical benefit. Immune cells in the AML tumor microenvironment (TME) are dysfunctional, in part due to enhanced interferon-γ signaling and acquisition of a senescent-like T/NK phenotype (Vadakekolathu, et al. Sci. Transl. Med. 2020). Cytokine-induced memory-like (CIML) NK cells are more potent for anti-tumor responses than conventional NK (cNK) cells, are well tolerated, and active in patients with R/R AML (NCT#01898793) with complete response (CR)/CR with partial/incomplete hematologic recovery rate of 47% and a median DOR of 9.4 months after a single infusion (Berrien-Elliott, et al. Cancer Discov. 2020). WU-NK-101 is a cell therapy derived from healthy donor NK cells, which are activated to induce a ML-NK cell program, expanded, and frozen to create an off-the-shelf cell therapy. This abstract 1) describes the approach for treatment of R/R AML with WU-NK-101, built upon prior clinical experience with CIML-NKs; 2) characterizes TME gene expression (GE) signatures associated with outcome after the infusion of CIML-NK in R/R AML and 3) functionally characterizes WU-NK-101. Bone marrow (BM) aspirates and trephine biopsies for immune GE profiling and spatially resolved proteomics (IO360® panel, n = 740 genes, and GeoMx® DSP; NanoString Technologies) were collected at baseline (BL) and on treatment (OT) from 15 patients receiving CIML-NK cells on study NCT #01898793. ssGSEA-based scores were computed using the IOBR package in R. Machine learning was used to select features that correlated with response. Cell phenotypes were evaluated by mass cytometry. NK cell function was assayed in either conventional (N-; 20% IMDM) or TME-aligned media. Multi-omics studies were performed by mass spectrometry. Cell trafficking to TME was measured in NSG mouse tumors by tracking fluorescent-labeled WU-NK-101. Correlative studies showed that BL GE signatures reflecting heightened neutrophil infiltration, chemokine receptor expression, and cancer antigen presentation predicted response to CIML-NKs (AUROC = 0.875, 0.875 and 0.850, respectively). We computed an 8-gene signature score (RPTOR, IRF9, TLR1, NLRP3, CD7, IL6R, FUT4, IL1RN) that was significantly higher at BL in responders and that correlated with response duration (Fig. 1A). Immune deconvolution of GE data with CIBERSORT highlighted critical differences in TME cellular composition at BL in responders to CIML-NKs, including a higher inferred abundance of macrophages, gamma/delta T cells and activated dendritic cells (Fig. 1B). In OT samples from responders, glycolytic GE programs as well as purine/pyrimidine and amino acid (AA) metabolism were upregulated compared with BL; no TME modulation was observed in non-responders (Fig. 1C). Analysis of WU-NK-101 cells revealed a unique phenotype compared with cNK cells, including higher expression of activating receptors, CD25, CD69, and GZMB, which positions WU-NK-101 for rapid activation and improved cytotoxicity. The latter hypothesis was confirmed by in vitro assays, with higher half maximal effective concentration (mEC50) for cNK vs WU-NK-101 (mEC50 = 5.2 vs 1.7; P = 0.032; Fig. 1D). The adverse impact of immunosuppressive TME-aligned media on cytotoxicity was evident on cNK but negligible to WU-NK-101 (mEC50 = 16.3 vs 2.0; P = 0.018; Fig. 1D). In N-media, WU-NK-101 used glucose as its main nutritional source; in hypoglycemic TME-aligned media, AA metabolic pathways were upregulated, indicating metabolic adaptability. This was supported by increased cell surface expression of AA transporters. WU-NK-101's homing to the BM averaged 16.5 ± 2.4%, which is 5.5-fold higher than previously reported for feeder-cell+IL-2-expanded NK cells (~3%; Sato et al. Clin. Cancer Res. 2020). In summary, an 8-gene TME signature showed excellent predictive ability for response to ML-NKs. In responders, ML-NK infusion was associated with TME modulation and with metabolic re-programming. Compared to cNK cells, WU-NK-101 had enhanced trafficking to the BM, anti-tumor activity, and a metabolic profile consistent with aerobic glycolysis, potentially contributing to mitigating TME adversity. Due to their resilience to an immunosuppressive TME, WU-NK-101 cells may represent an effective treatment modality for R/R AML; a phase 1 study of WU-NK-101 in R/R AML is in development (NCT #05470140). Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The High Mobility Group A1 Chromatin Regulator Drives Immune Evasion during MPN Progression By Repressing Genes Involved in Antigen Presentation

Introduction: Myeloproliferative Neoplasms (MPN) are blood diseases caused by mutations activating JAK2 in hematopoietic stem cells (HSCs) which lead to clonal expansion and overproduction of myeloid lineages. MPN patients are at increased risk for transformation to bone marrow fibrosis (myelofibrosis) and acute myeloid leukemia (AML), both of which are associated with poor clinical outcomes. Importantly, targetable mechanisms to prevent progression remain elusive. The High Mobility Group A1 (HMGA1) gene encodes chromatin regulators which are enriched in hematopoietic stem cells and aberrantly overexpressed in MPN with highest levels after transformation to myelofibrosis and acute leukemia (Li & Kim et al Blood 2022, Xian et al Nature Commun 2017). We recently discovered that HMGA1 is required for progression to leukemia in murine models of JAK2V617F MPN leukemia. Further, loss of just a single Hmga1 allele prevents progression to myelofibrosis in JAK2V617F transgenic mice. Emerging evidence suggests that immune escape represents a fundamental pathway involved in progression in diverse tumors. We therefore sought to: 1) test the hypothesis that HMGA1 drives MPN progression by dysregulating gene networks involved in immune evasion, and, 2) identify mediators of immune escape that could be disrupted in therapy. Methods: To identify gene networks regulated by HMGA1 in JAK2V617F MPN, we performed multi-omics sequencing analyses, including RNAseq, chromatin immunoprecipitation (ChIPseq), and assays of chromatin accessibility (ATACseq) from JAK2V617Fmutant AML cell lines (DAMI, SET-2) + HMGA1 depletion. HMGA1 gene expression was inactivated using CRISPR/Cas9 or short hairpin RNAs (shRNA) targeting 2 different sequences. We used gene set enrichment analysis to dissect molecular mechanisms underlying HMGA1. Transcriptional networks were validated at the level of mRNA and protein via quantitative RT-PCR and flow cytometry. To identify drugs to disrupt HMGA1 immune evasion networks, we applied the Broad Institute Connectivity Map (CMAP) and cytotoxicity assays. To validate these pathways in human MPN, we assessed gene expression in independent MPN patient cohorts. Results: To elucidate transcriptional networks governed by HMGA1 during MPN progression to leukemia, we integrated RNAseq, ChIPseq, and ATACseq in JAK2V617F mutant AML cells (DAMI, SET-2) which revealed that HMGA1 represses genes involved in antigen presentation (Interferon γ response networks), including genes encoding major histocompatibility complex (MHC) class I and II antigens. Silencing HMGA1 via CRISPR or shRNA results in up-regulation of MHC class I and II antigen genes, with greatest induction of MHC class II genes HLA-DRA/DRB1. Similarly, HMGA1 depletion increases cell surface expression of HLA-DR antigens by flow cytometry. Further, inhibiting HMGA1 in JAK2V617Fmutant AML cells results in up-regulating the class II major histocompatibility complex transactivator (CIITA) and invariant chain (CD74), which function in inducing MHC class II gene expression and chaperoning structure assembly, respectively. To identify underlying mechanisms, we intersected ChIPseq with ATACseq, which revealed HMGA1 occupancy downstream of the HLA-DRB1 locus, including regions at +6.27kb, +6.7kb, +14kb, and +15kb from the transcription start site. Further, preliminary results suggest that HMGA1 recruits repressive histone marks to repress HLA-DRB1 at these sites. To target HMGA1 networks, we queried CMAP, which identified the histone deacytelyase inhibitor (HDACi), entinostat. Strikingly, entinostat not only up-regulates MHC class II genes and antigens, but is also cytotoxic in JAK2V617F mutant AML cells. Finally, HMGA1 depletion enhances sensitivity to entinostat, which synergizes with JAK inhibitor, Ruxolitinib, to further induce MHC gene expression. Conclusions: We discovered a novel epigenetic program whereby HMGA1 drives immune evasion during MPN progression by binding to chromatin and modulating transcriptional networks to repress MHC antigen presentation. Most importantly, HMGA1 immune evasion networks are dysregulated in human MPN after progression to AML. Together, our studies reveal a new paradigm whereby HMGA1 down-regulates MHC antigens during MPN progression, suggesting that targeting HMGA1 networks with entinostat could activate an immune attack and prevent MPN progression. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal