Journal of Clinical Investigation

Management of peripheral nervous system (PNS) neuropathies, such as traumatic peripheral nerve injury (PNI), relies on accurate assessment of muscle denervation and recovery. Yet, the current gold-standard clinical test, needle electromyography (EMG), has multiple shortcomings that can complicate surgical treatment. Here, we introduce a noninvasive method for holistic evaluation of muscle denervation by utilizing positron emission tomography (PET) to quantify expression of prostate-specific membrane antigen (PSMA), also known as glutamate carboxypeptidase II (GCPII), within muscles. We identified that GCPII is persistently over-expressed in denervated muscles and that expression normalizes with muscle reinnervation. Leveraging this phenomenon, we used two PSMA/GCPII-PET agents that are FDA-approved for prostate cancer imaging, [18F]DCFPyL and [68Ga]PSMA-11, to detect muscle denervation and subsequent reinnervation in experimental models of PNI. We found that denervated muscle had approximately twice the uptake as innervated muscle on GCPII-PET/magnetic resonance (MR) imaging and GCPII-PET/computed tomography (CT), which persisted for at least 16 weeks after nerve injury without repair in rats and swine. GCPII-targeted uptake also declined to near baseline levels with muscle reinnervation after nerve repair. To assess clinical feasibility, we performed [18F]DCFPyL PET/CT in a patient who had sustained a unilateral radial nerve injury 15 weeks prior, and we observed elevations in denervated muscle uptake that mirrored our preclinical findings. Our consistent findings across species of increased GCPII-PET uptake in chronically denervated muscle and its decline with muscle reinnervation, along with the established safety profile of available GCPII-PET agents, support the promise of GCPII-PET as a rapidly translatable strategy for characterization and longitudinal monitoring of PNIs and non-traumatic PNS neuropathies.

PNPLA8, one of the calcium-independent phospholipase A2 enzymes, is involved in various physiological processes through the maintenance of membrane phospholipids. However, little is known about its role in brain development. Here, we report 12 individuals from 10 unrelated families with biallelic ultra-rare variants in PNPLA8 presenting with a wide spectrum of clinical features ranging from developmental and epileptic-dyskinetic encephalopathy (DEDE) to progressive movement disorders. Complete loss of PNPLA8 was associated with the severe end of the spectrum, showing DEDE manifestations and congenital or progressive microcephaly. Using cerebral organoids generated from human induced pluripotent stem cells, we found that loss of PNPLA8 reduced the number of basal radial glial cells (bRGCs) and upper-layer neurons. By spatial transcriptomic analysis targeting apical radial glial cells (aRGCs), we found the downregulation of bRGC-related gene sets in patient-derived cerebral organoids. Lipidomic analysis revealed a decrease in the amount of lysophosphatidic acid, lysophosphatidylethanolamine, and phosphatidic acid, indicative of the disturbed phospholipid metabolism in PNPLA8 knockout neural progenitor cells. Our data suggest that PNPLA8 has a critical role in the bRGC-mediated expansion of the developing human cortex by regulating the fate commitment of aRGCs.

Symmetric, progressive, necrotizing lesions in the brainstem are a defining feature of Leigh syndrome (LS). A mechanistic understanding of the pathogenesis of these lesions has been elusive. Here, we report that leukocyte proliferation is causally involved in the pathogenesis of Leigh syndrome. Directly depleting leukocytes with a colony-stimulating factor 1 receptor (CSF1R) inhibitor dramatically attenuates disease, including complete prevention of CNS lesion formation and substantial extension of survival. Leukocyte depletion rescues a range of symptoms including hyperlactemia, seizures, respiratory function, and neurologic symptoms. These data provide a mechanistic explanation for the beneficial effects of mTOR inhibition. More importantly, these findings dramatically alter our understanding of the pathogenesis of LS, demonstrating that immune involvement directly drives disease. These findings have significant implication for the mechanisms of disease resulting from mitochondrial dysfunction, and may lead to novel therapeutic strategies. One-Sentence SummaryPharmacologic targeting of leukocytes prevents CNS lesions, neurological disease, and metabolic dysfunction in the Ndufs4(KO) mouse model of Leigh syndrome.

Immune related adverse events (irAEs) after immune checkpoint blockade (ICB) therapy occur in a significant proportion of cancer patients. To date, the circulating mediators of ICB-irAEs remain poorly understood. Using non-targeted mass spectrometry, here we identify the circulating bio-active lipid linoleoyl-lysophosphatidylcholine (LPC 18:2) as a modulator of ICB-irAEs. In three independent human studies of ICB treatment for solid tumor, loss of circulating LPC 18:2 preceded the development of severe irAEs across multiple organ systems. In both healthy humans and severe ICB-irAE patients, low LPC 18:2 was found to correlate with high blood neutrophilia. Reduced LPC 18:2 biosynthesis was confirmed in preclinical ICB-irAE models, and LPC 18:2 supplementation in vivo suppressed neutrophilia and tissue inflammation without impacting ICB anti-tumor response. Results indicate that circulating LPC 18:2 suppresses human ICB-irAEs, and LPC 18:2 supplementation may improve ICB outcomes by preventing severe inflammation while maintaining anti-tumor immunity.

Humans and mice with mutations in COL4A1 and COL4A2 manifest hallmarks of cerebral small vessel disease (cSVD), but the pathogenic mechanisms are largely unknown. Mice with a missense mutation in Col4a1 at amino acid 1344 (Col4a1+/G1344D) exhibited age-dependent intracerebral hemorrhage (ICH) and brain lesions. Here we report that this pathology was associated with the loss of myogenic vasoconstriction, an intrinsic vascular response essential for the autoregulation of cerebral blood flow. Electrophysiological analyses showed that the loss of myogenic constriction resulted from blunted pressure-induced smooth muscle cell (SMC) membrane depolarization. Further, we found that dysregulation of membrane potential was associated with impaired Ca2+-dependent activation of large-conductance Ca2+-activated K+ (BK) and transient receptor potential melastatin 4 (TRPM4) cation channels linked to disruptions in sarcoplasmic reticulum (SR) Ca2+ signaling. Treating Col4a1+/G1344D mice with 4-phenylbutyrate, a compound that promotes the trafficking of misfolded proteins and alleviates SR stress, restored SR Ca2+ signaling, BK and TRPM4 channel activity, prevented loss of myogenic tone, and reduced ICH. We conclude that alterations in SR Ca2+ handling that impair membrane potential regulating ion channel activity result in dysregulation of SMC membrane potential and loss of myogenic tone contributing to age-related cSVD in Col4a1+/G1344D mice. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=85 SRC="FIGDIR/small/505186v3_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@11a8cb9org.highwire.dtl.DTLVardef@d00b8org.highwire.dtl.DTLVardef@1aa5b24org.highwire.dtl.DTLVardef@145a9c0_HPS_FORMAT_FIGEXP M_FIG C_FIG

Multiple sclerosis (MS) therapies primarily rely on lymphocyte depletion or trafficking blockade, carrying risks of systemic immunosuppression; however, such treatments have limited efficacy in secondary progressive multiple sclerosis (SPMS). Thus, drugs that target stage-specific inflammation without broad immunosuppression are an unmet clinical need. In this double-blind, placebo-controlled phase II trial, 30 patients with relapsing MS received weekly oral OCH or placebo for 24 weeks. In the pre-specified SPMS subgroup (n=12), OCH achieved complete relapse prevention (p=0.0003), prolonged relapse-free survival (p=0.0079), no new lesions (0/6), with no evidence of disease activity (NEDA-3) in 5/6 patients. In comparison, for the placebo-treated group, 5/6 patients suffered relapses, 2/6 patients developed new lesions, and no placebo-treated SPMS achieved NEDA-3. Invariant natural killer T (iNKT) cells, a regulatory lymphocyte population that is numerically and functionally impaired in MS, are a potential target for MS therapy. Glycolipid OCH is a selective iNKT cell stimulator, skewing the cytokine environment towards Th2. OCH treatment resulted in increased IL-4-producing Th cells in patient peripheral blood while decreasing pathogenic GM-CSF-producing Th cells. Parallel studies in mouse models of MS (EAE) corroborated this mechanism and further revealed that OCH activated gut iNKT cells. Disease amelioration by OCH depended on IL-4 and its efficacy was further enhanced by depletion of B cells. These data revealed the gut-brain axis mediation of progressive-stage pathology distinct from relapsing-remitting MS. Findings from this bidirectional translational study uncover mechanistic differences between SPMS and other types of MS and highlight divergent roles for B cells and Th cells. Furthermore, OCH exerts its therapeutic benefit via targeting mechanisms that are distinct from currently available drugs; exploiting iNKT cell regulatory potential to reprogram pathogenic T helper responses without lymphocyte depletion. The unique yet effective nature of OCH treatment positions it as an attractive future oral therapy for SPMS. One Sentence SummaryThe iNKT cell activating ligand OCH suppresses disease activity selectively in secondary progressive MS in a phase II clinical trial, revealing stage-specific IL-4-mediated immune cell interactions in MS pathology.

Sphingosine-1-phosphate lyase insufficiency syndrome (SPLIS), also known as nephrotic syndrome type 14 (NPHS14), is an autosomal recessive disorder characterized by renal, neurological, dermatological, endocrine, and immunological symptoms. This condition is caused by loss-of-function mutations in the SGPL1 gene, which encodes sphingosine-1-phosphate lyase (SGPL1p/SPL), the enzyme responsible for the terminal degradation of sphingosine-1-phosphate (S1P) in sphingolipid catabolism. We investigated a novel case of SPLIS associated with a recently reported SGPL1 mutation (c.1084T>A; p.Ser362Thr). Using stable isotope flux analyses, we demonstrated in patient-derived fibroblasts and HEK293T SGPL1 knockout models that SGPL1p deficiency does not consistently result in pathological S1P accumulation. Instead, SPL-deficient cells are able to maintain steady-state S1P levels through two compensatory mechanisms: O_LIRegulation of de novo sphingolipid synthesis via the ORMDL-ceramide axis. C_LIO_LIIncreased conversion of excess ceramides into glycosphingolipids. C_LI However, when steady-state conditions are disrupted--either by external sphingolipid supplementation or by impairing homeostatic control--a pathological increase in intracellular S1P occurs in SPL-deficient cells. In vivo, Sgpl1-/-mice exhibited significant urinary excretion of S1P and marked S1P enrichment in the kidneys. This pathological accumulation of S1P dysregulates cytoskeletal homeostasis, impairing renal epithelial formation. Based on these findings, we hypothesize that the reabsorption of urinary S1P contributes to toxic renal accumulation, providing an explanation for the nephrotoxicity observed in SPLIS and its association with nephrotic syndrome. Importantly, we found that the cytoskeletal disruptions could be mitigated by inhibiting the Rho-ROCK signaling pathway using the clinically approved inhibitor Fasudil. These findings illuminate the pathophysiological basis of SPLIS nephrotoxicity and propose a promising pharmacological intervention strategy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=144 SRC="FIGDIR/small/634100v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@e70e68org.highwire.dtl.DTLVardef@1630198org.highwire.dtl.DTLVardef@fde277org.highwire.dtl.DTLVardef@1f2b8e_HPS_FORMAT_FIGEXP M_FIG C_FIG

Human cytomegalovirus (HCMV) is the most common vertically transmitted infection worldwide, yet there are no licensed vaccines or therapeutics to prevent congenital HCMV (cCMV) infection. Emerging evidence from studies of natural infection and HCMV vaccine trials indicates that antibody Fc effector functions may defend against HCMV infection. We previously reported that antibody-dependent cellular phagocytosis (ADCP) and IgG activation of Fc{gamma}RI/Fc{gamma}RII were associated with reduced risk of cCMV transmission, leading us to hypothesize that other Fc-mediated antibody functions may also contribute to protection. In this same cohort of HCMV transmitting (n = 41) and non-transmitting (n = 40) mother-infant dyads, we found that higher maternal sera antibody-dependent cellular cytotoxicity (ADCC) activation was also associated with decreased risk of cCMV infection. We determined that NK cell-mediated ADCC responses correlated strongly with anti-HCMV IgG Fc{gamma}RIII/CD16 activation and IgG binding to the HCMV immunoevasin protein UL16. Notably, anti-UL16 IgG binding and engagement of Fc{gamma}RIII/CD16 were higher in non-transmitting versus transmitting dyads and interacted significantly with ADCC responses. These findings indicate that ADCC-activating antibodies against novel targets such as UL16 may represent an important protective maternal immune response against cCMV infection, which can guide future HCMV correlates studies and vaccine development.

PurposeThis research investigates the association between benzodiazepines (BZDs) and cancer patient survival outcomes. Due to the high prevalence of BZD use in pancreatic cancer patients, we evaluated the effect of commonly prescribed BZDs on the pancreatic cancer tumor microenvironment and cancer-associated fibroblast (CAF) signaling. Experimental DesignMultivariate Cox regression modeling was used to retrospectively measure associations between Roswell Park cancer patient survival outcomes and BZD prescription records. Immunohistochemistry, H&E, Massons trichrome, in situ hybridization, and RNA sequencing were used to evaluate the impact of lorazepam (LOR) on the PDAC tumor microenvironment, using murine pancreatic cancer models. ELISA and qPCR were used to determine the impact of BZDs on IL-6 expression/secretion by human immortalized pancreatic CAFs. PRESTO-Tango assays, reanalysis of PDAC single cell sequencing/TCGA datasets, and GPR68 CRISPRi knockdown CAF cells were used to mechanistically determine the impact of BZDs on CAF-specific GPR68 signaling. ResultsLOR is associated with worse progression-free survival (PFS) while alprazolam (ALP) is associated with improved PFS, in pancreatic cancer patients receiving chemotherapy. LOR promotes desmoplasia (fibrosis and extracellular matrix protein deposition), inflammatory signaling, IL-6 expression/secretion in CAFs, and ischemic necrosis. LOR promotes inflammatory signaling and IL-6 secretion by CAFs through activation of GPR68. GPR68 is preferentially expressed on human PDAC CAFs, and n-unsubstituted BZDs significantly increase GPR68 activation under acidic conditions. LOR increases IL-6 expression and secretion in CAFs in a pH and GPR68-dependent manner. Conversely, ALP, and other GPR68 non-activator BZDs decrease IL-6 in human CAFs in a pH and GPR68-independent manner. Across many cancer types, LOR is associated with worse survival outcomes relative to ALP and patients not receiving BZDs. ConclusionWe demonstrate that LOR stimulates fibrosis and inflammatory signaling, promotes ischemic necrosis, and is associated with decreased pancreatic cancer patient survival.

Classical and basal-like transcriptional subtypes of pancreatic ductal adenocarcinoma (PDAC) are prognostic and may predict response to different chemotherapy regimens and RAS inhibitors. Current subtyping methods rely on tissue biopsies and remain challenging to integrate into clinical workflows. Herein, we present a novel approach for non-invasive subtyping of PDAC based on epigenomic profiling of circulating tumor DNA (ctDNA). In a multi-omics cohort of patient-derived xenografts, we identify highly recurrent regulatory elements associated with classical and basal-like PDAC. We then demonstrate that these epigenomic signatures can identify PDAC subtype from plasma epigenomic profiling in a multi-institutional cohort of patients with metastatic PDAC and integrate information from circulating histone modifications and DNA methylation to develop the Pancreatic Integrated Epigenomic Score (PIES). PIES is concordant with tissue-based labels and captures transcriptional subtype heterogeneity observed within biopsies. Furthermore, it improves prognostication over tissue-based subtyping suggestive of the recovery of ground truth tumor biology from plasma ctDNA. Our work provides a proof-of-concept for a circulating biomarker that enables transcriptional subtyping and informs therapeutic decisions in pancreatic cancer.

Post-infection inflammatory syndromes have been increasingly recognized as a cause of host damage in a variety of infectious diseases including tuberculosis, bacterial meningitis, and COVID-19. Recently, a post-infectious inflammatory response syndrome (PIIRS) was described in non-HIV-infected cryptococcal fungal meningoencephalitis (CM) as a major cause of mortality. Inflammatory syndromes are particularly severe in neurological infections due to the skulls rigid structure which limits unchecked tissue expansion from inflammatory-induced edema. In the present studies, neurologic transcriptional pathway analysis utilizing a murine PIIRS model demonstrated a predominance of Janus kinase/signal transducer and activator of transcription (JAK/STAT) activation. JAK/STAT inhibitor treatment resulted in improvements in CNS damage markers, reductions in intrathecal CD44hiCD62lo CD4+ effector CD4+ T-cells and MHC II+ inflammatory myeloid cells, and weight gains in mice, the latter after treatment with antifungals. Based on these data, pathway-driven steroid-sparing human treatment for steroid-refractory PIIRS was initiated using short courses of the JAK/STAT inhibitor ruxolitinib. These were well tolerated and reduced activated HLA-DR+ CD4+ and CD8+ cells and inflammatory monocytes as well as improved brain imaging. Together, these findings support the role of JAK/STAT in PIIRS as well as further study of JAK/STAT inhibitors as potential adjunctive therapy for PIRS and other neural inflammatory syndromes.

Impaired cellular differentiation is a defining characteristic of myeloid malignancies and remains a major therapeutic challenge. The BRG1/Brahma-associated factor (BAF) chromatin remodeling complex, through the ATPases SMARCA4 and SMARCA2, maintains the stemness of leukemic blasts and thus represents a promising target for novel differentiation-based therapies. In a phase 1 study in advanced myeloid malignancies, the first-in-class dual SMARCA4/2 inhibitor FHD-286 combined with decitabine (DAC) was tolerated and produced an objective response rate of 12.8% (6/47) compared with no responses with FHD-286 monotherapy. To understand the basis of this activity, we integrated high-dimensional flow cytometry and single-cell genomic analyses of longitudinal bone marrow samples from responders and nonresponders. While FHD-286 monotherapy was predominantly associated with myeloid differentiation, responders to FHD-286+DAC combination therapy exhibited a range of myeloid and erythroid differentiation trajectories. FHD-286 potentiated the transcriptional impact of DAC, driving tumor clones to fully differentiate out of the immunophenotypically and transcriptionally defined blast compartment. Responders had a baseline transcriptional profile similar to that of CEBPA-mutant acute myeloid leukemia and showed further downregulation of CEBPA upon treatment. These findings reinforce tumor cell differentiation as a mechanism of response to pharmacologic SMARCA4/2 inhibition and support further evaluation of FHD-286+DAC in molecularly defined patient subsets.

Heart failure with preserved ejection fraction (HFpEF) is a rapidly growing public health concern and an emerging contributor to dementia, yet the mechanisms linking cardiometabolic dysfunction to neurodegeneration remain poorly understood. Here, we demonstrate that HFpEF drives a sustained neuroinflammatory state through microglial metabolic reprogramming. Using a clinically relevant murine model of HFpEF, we identified robust induction of HIF-1 signaling in microglia via integrated transcriptomics and metabolomics, coupled with increased glycolytic metabolism revealed by extracellular flux analysis. Conditional deletion of Hif1a in microglia during HFpEF attenuated neuroinflammation, preserved white matter integrity, and rescued cognitive performance. We further identify Sema4D as a HIF-1-dependent, microglia-derived effector linking metabolic stress to white matter injury. These findings establish a mechanistic bridge between cardiovascular disease and cognitive dysfunction and reveal microglial HIF-1 signaling as a tractable therapeutic strategy for preventing cognitive decline in cardiometabolic disease.

Myasthenia gravis, an autoimmune disease characterized by muscle weakness that can manifest in bulbar dysfunction and respiratory distress, is driven in a subset of patients by autoantibodies against muscle-specific receptor tyrosine kinase (MuSK MG). MuSK MG and other autoantibody mediated disorders are generally treated with broad immunosuppressive approaches such as corticosteroids, plasmapheresis, B cell depletion, or FcRn inhibition, which can impact patient care via systemic side effects, variable responsiveness, and increased susceptibility to infection. We developed a lysosomal targeting chimera (LYTAC) therapeutic (MuSK LYTAC) that combines a MuSK antigen "Bait" capable of selectively binding to the disease-driving antibodies with asialoglycoprotein receptor (ASGPR) ligands that target the resulting immune complexes for degradation by ASGPR-expressing hepatocytes. Our optimized MuSK Bait effectively depleted pathogenic antibodies from the serum of 10 donors with MuSK MG, supporting broad applicability across the patient population. In vitro assays using both Hep G2 cells and primary human hepatocytes demonstrated that MuSK LYTAC is pharmacologically active, promoting uptake and lysosomal degradation of autoantibodies through an ASGPR-dependent mechanism. Mouse pharmacodynamic and passive immunization disease models showed that MuSK LYTAC rapidly eliminates autoantibodies from the serum and alleviates related disease symptoms, without impacting circulating IgG levels. These results support the promise of Autoantibody Bait LYTACs (ABLates) as precision treatments for MuSK MG and other autoantibody-driven diseases that avoid generalized immunosuppression.

Elucidating the molecular basis of immunodeficiency diseases is a powerful approach to discovering new immunoregulatory pathways in humans. Here we report 10 affected individuals from 4 families with a new immunodeficiency disease comprising of severe progressive lymphopenia, autoimmunity, immunodeficiency, and liver disease due to recessive loss of function variants in "GTPase of immunity-associated proteins" protein 5 (GIMAP5). We show that the disease involves the progressive loss of naive T lymphocytes and a corresponding increase in antigen-experienced, but poorly functional and replicatively senescent T cells. In vivo treatment of Gimap5-deficient mice with rapamycin (an inhibitor of mTORC1) significantly restores the fraction of naive T lymphocytes. Furthermore, a GIMAP5-deficient human patient who was treated with rapamycin (sirolimus) showed a remarkable reduction in spleen/lymph node size. Together, these observations reveal that GIMAP5 plays a critical role in lymphocyte metabolism which is essential for senescence prevention and immune competence, suggesting that an inhibitor of mTORC1 could be a valuable clinical intervention in treating patients deficient for GIMAP5.

The mitochondrial contact site and cristae organizing system (MICOS) is important for cristae junctions (CJ) formation and for maintaining inner mitochondrial membrane (IMM) architecture. As the largest member, MIC60 is the primary scaffold protein for this complex. While MIC60 has been well studied in yeast and cell culture models, its function in mammals is poorly understood. To address this, we developed a mouse model conditionally deleting Immt (which encodes MIC60) and found that global Immt deletion disrupted the MICOS complex and resulted in lethality within 9 days of tamoxifen treatment. Pathologically, these mice display intestinal defects consistent with paralytic ileus, resulting in dehydration. We also identified bone marrow hypocellularity in tamoxifen-treated mice. However, bone marrow transplants from ImmtWT mice failed to rescue survival. Altogether, this novel mouse model demonstrates the importance of MIC60 in vivo, in both hematopoietic and non-hematopoietic tissues, and provides a valuable resource for future mechanistic investigations into the MICOS complex. Such investigations could include an in vivo structure-function analysis of MIC60 functional domains, with characterizations that are relevant to human diseases.

RationaleSodium-glucose co-transporter inhibitors (SGLT2i) are under active clinical investigation in patients with acute inflammatory conditions, based on their clinical cardio-and nephroprotective effects, and a pre-clinical study that demonstrated SGLT2i improve renal outcomes and survival in a lipopolysaccharide (LPS) model. However, a unified mechanism that explains how SGLT2i could prevent hemodynamic consequences of inflammatory conditions has not been described. Apolipoprotein M (ApoM) is inversely associated with mortality in inflammatory conditions and improves cardiac function in endotoxin-treated mice via sphingosine-1-phosphate (S1P) signaling. ObjectiveTest the hypothesis that pre-treatment with SGLT2i dapagliflozin (Dapa) improves hemodynamics in endotoxin-treated mice via the ApoM/S1P pathway. Methods and ResultsMice with diet-induced obesity were gavaged with vehicle or Dapa for 4 days prior to LPS (10 mg/kg, IP). We found that mice receiving Dapa restored circulating ApoM levels, likely by increasing expression of the multi-ligand protein receptor megalin in the proximal tubules. Dapa attenuated LPS-induced reductions in cardiac dysfunction including reductions in ejection fraction, cardiac index, and coronary sinus area as well as vascular permeability as ascertained by intravital microscopy. Using both ApoM transgenic and knockout mice and S1P receptor inhibitors, we show that the ApoM/S1P pathway is important for the beneficial effects of Dapa in the LPS model. ConclusionsIn the setting of acute inflammation, our data suggest that SGLT2i maintains levels of megalin, leading to preservation of ApoM, which in turn promotes endothelial barrier integrity and improves hemodynamics. Our studies suggest a novel mechanism by which SGLT2i can preserve intravascular volume in the acute inflammatory setting.

Infants depend on passive immunity to safeguard them against infections during the first months of life. Maternal immunoglobulin G (IgG) antibodies are actively transported across the placenta and confer this protection. In this study, we discovered common, but previously unrecognized, naturally occurring gene fusions between loci encoding IgG1 and IgG4 subclasses that impair the transplacental IgG transport. These gene fusions result from gene duplications combining regulatory elements of the Immunoglobulin Heavy Constant Gamma (IGHG1) gene with IGHG4-like constant regions. Mothers with these duplications generate antibodies that are less efficiently transferred to the fetus, resulting in lower antibody levels in newborns and a higher risk of respiratory infections during infancy. Our insights warrant consideration in the development of personalized vaccination strategies during pregnancy to better protect infants against infectious diseases.

Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive brain tumor with rare survival beyond two years. This poor prognosis is largely due to the tumors highly infiltrative and invasive nature. Previous reports demonstrate upregulation of the transcription factor ID1 with H3K27M and ACVR1 mutations, but this has not been confirmed in human tumors or therapeutically targeted. We developed an in utero electroporation (IUE) murine H3K27M-driven tumor model, which demonstrates increased ID1 expression in H3K27M- and ACVR1-mutated tumor cells. In human tumors, elevated ID1 expression is associated with H3K27M/ACVR1-mutation, brainstem location, and reduced survival. The ID1 promoter demonstrates a similar active epigenetic state in H3K27M tumor cells and murine prenatal hindbrain cells. In the developing human brain, ID1 is expressed highest in oligo/astrocyte-precursor cells (OAPCs). These ID1+/SPARCL1+ cells share a transcriptional program with astrocyte-like (AC-like) DIPG cells, and demonstrate upregulation of gene sets involved with regulation of cell migration. Both genetic and pharmacologic [cannabidiol (CBD)] suppression of ID1 results in decreased DIPG cell invasion/migration in vitro and invasion/tumor growth in multiple in vivo models. CBD reduces proliferation through reactive oxygen species (ROS) production at low micromolar concentrations, which we found to be achievable in the murine brainstem. Further, pediatric high-grade glioma patients treated off-trial with CBD (n=15) demonstrate tumor ID1 reduction and improved overall survival compared to historical controls. Our study identifies that ID1 is upregulated in DIPG through reactivation of a developmental OAPC transcriptional state, and ID1-driven invasiveness of DIPG is therapeutically targetable with CBD. One Sentence SummaryThe transcription factor ID1 is upregulated in a subset of DIPG tumor cells, and ID1-driven invasiveness is therapeutically targetable with CBD.

Supraphysiological androgen (SPA) treatment can paradoxically restrict growth of castration-resistant prostate cancer with high androgen receptor (AR) activity, which is the basis for use of Bipolar Androgen Therapy (BAT) for patients with this disease. While androgens are widely appreciated to enhance anabolic metabolism, how SPA-mediated metabolic changes alter prostate cancer progression and therapy response is unknown. Here, we report that SPA markedly increased intracellular and secreted polyamines in prostate cancer models. This occurred through AR binding at enhancer sites upstream of the ODC1 promoter to increase abundance of ornithine decarboxylase (ODC), a rate-limiting enzyme of polyamine synthesis, and de novo synthesis of polyamines from arginine. SPA-stimulated polyamines enhance prostate cancer fitness, as dCas9-KRAB-mediated inhibition of AR regulation of ODC1 or direct ODC inhibition by difluoromethylornithine (DFMO) increased efficacy of SPA. Mechanistically, this occurred in part due to increased activity of S-adenosylmethionine decarboxylase 1 (AMD1), which was stimulated both by AR and by loss of negative feedback by polyamines, leading to depletion of its substrate S-adenosylmethionine and global protein methylation. These data provided the rationale for a clinical trial testing the safety and efficacy of BAT in combination with DFMO for patients with metastatic castration-resistant prostate cancer. Pharmacodynamic studies of this drug combination in the first five patients on trial indicated that the drug combination resulted in effective polyamine depletion in plasma. Thus, the AR potently stimulates polyamine synthesis, which constitutes a vulnerability in prostate cancer treated with SPA that can be targeted therapeutically.