IDH-mutant myeloid neoplasms are associated with seronegative rheumatoid arthritis and innate immune activation.

ABSTRACT: High prevalence of IDH mutations in seronegative rheumatoid arthritis (RA) with myeloid neoplasm, elevated 2-hydroxyglutarate, dysregulated innate immunity, and proinflammatory microenvironment suggests causative association between IDH mutations and seronegative RA. Our findings merit investigation of IDH inhibitors as therapeutics for seronegative IDH-mutated RA.

IDH1-Mutant Preleukemic Hematopoietic Stem Cells Can Be Eliminated by Inhibition of Oxidative Phosphorylation.

Rare preleukemic hematopoietic stem cells (pHSC) harboring only the initiating mutations can be detected at the time of acute myeloid leukemia (AML) diagnosis. pHSCs are the origin of leukemia and a potential reservoir for relapse. Using primary human samples and gene editing to model isocitrate dehydrogenase 1 (IDH1) mutant pHSCs, we show epigenetic, transcriptional, and metabolic differences between pHSCs and healthy hematopoietic stem cells (HSC). We confirm that IDH1-driven clonal hematopoiesis is associated with cytopenia, suggesting an inherent defect to fully reconstitute hematopoiesis. Despite giving rise to multilineage engraftment, IDH1-mutant pHSCs exhibited reduced proliferation, blocked differentiation, downregulation of MHC class II genes, and reprogramming of oxidative phosphorylation metabolism. Critically, inhibition of oxidative phosphorylation resulted in the complete eradication of IDH1-mutant pHSCs but not IDH2-mutant pHSCs or wild-type HSCs. Our results indicate that IDH1-mutant preleukemic clones can be targeted with complex I inhibitors, offering a potential strategy to prevent the development and relapse of leukemia. SIGNIFICANCE: A high burden of pHSCs is associated with worse overall survival in AML. Using single-cell sequencing, metabolic assessment, and gene-edited human models, we find human pHSCs with IDH1 mutations to be metabolically vulnerable and sensitive to eradication by complex I inhibition. See related commentary by Steensma.

Thrombospondin-1 associated with carotid intima-media thickness among individuals with hypertension.

In vivo and in vitro studies have demonstrated that thrombospondin-1 (TSP-1) is involved in atherosclerotic pathogenesis. However, the role of TSP-1 in clinical atherosclerosis remains unknown. This cross-sectional study investigated the relationship between TSP-1 and carotid intima-media thickness (IMT) and examined whether it interacts with conventional cardiovascular risk factors. A total of 587 participants were enrolled from February 2018 to December 2021. TSP-1 was dichotomized based on median value. Carotid IMT was measured bilaterally in each segment, and the average value was taken as the overall IMT variable. Analysis of covariance models were used to ascertain the main and interaction effects of cardiovascular risk factors and circulating TSP-1 levels on carotid IMT. Those with high TSP-1 (n = 294) had significantly higher carotid IMT than did those with low TSP-1 (n = 293; 0.74 ± 0.12 vs 0.72 ± 0.11 mm; p = 0.011). After the combined effects of TSP-1 and vascular risk factors on carotid IMT were evaluated, an interaction effect on IMT was observed between TSP-1 and hypertension (adjusted F = 8.760; p = 0.003). Stratification analysis revealed that individuals with hypertension and high TSP-1 had significantly higher IMT than did those with low TSP-1 (adjusted p = 0.007). However, this difference was not observed in normotensive individuals (adjusted p = 0.636). In conclusion, this is the first study to provide clinical data supporting the correlation between TSP-1 and atherosclerosis. TSP-1 may be a crucial marker of increased susceptibility to atherosclerosis in individuals with hypertension.

IDH1-mutant preleukemic hematopoietic stem cells can be eliminated by inhibition of oxidative phosphorylation.

Rare preleukemic hematopoietic stem cells (pHSCs) harboring only the initiating mutations can be detected at the time of AML diagnosis. pHSCs are the origin of leukemia and a potential reservoir for relapse. Using primary human samples and gene-editing to model isocitrate dehydrogenase 1 (IDH1) mutant pHSCs, we show epigenetic, transcriptional, and metabolic differences between pHSCs and healthy hematopoietic stem cells (HSCs). We confirm that IDH1 driven clonal hematopoiesis is associated with cytopenia, suggesting an inherent defect to fully reconstitute hematopoiesis. Despite giving rise to multilineage engraftment, IDH1-mutant pHSCs exhibited reduced proliferation, blocked differentiation, downregulation of MHC Class II genes, and reprogramming of oxidative phosphorylation metabolism. Critically, inhibition of oxidative phosphorylation resulted in complete eradication of IDH1-mutant pHSCs but not IDH2-mutant pHSCs or wildtype HSCs. Our results indicate that IDH1-mutant preleukemic clones can be targeted with complex I inhibitors, offering a potential strategy to prevent development and relapse of leukemia.

Open-Spaced Ridged Hydrogel Scaffolds Containing TiO2-Self-Assembled Monolayer of Phosphonates Promote Regeneration and Recovery Following Spinal Cord Injury.

The spinal cord has a poor ability to regenerate after an injury, which may be due to cell loss, cyst formation, inflammation, and scarring. A promising approach to treating a spinal cord injury (SCI) is the use of biomaterials. We have developed a novel hydrogel scaffold fabricated from oligo(poly(ethylene glycol) fumarate) (OPF) as a 0.08 mm thick sheet containing polymer ridges and a cell-attractive surface on the other side. When the cells are cultured on OPF via chemical patterning, the cells attach, align, and deposit ECM along the direction of the pattern. Animals implanted with the rolled scaffold sheets had greater hindlimb recovery compared to that of the multichannel scaffold control, which is likely due to the greater number of axons growing across it. The immune cell number (microglia or hemopoietic cells: 50-120 cells/mm2 in all conditions), scarring (5-10% in all conditions), and ECM deposits (Laminin or Fibronectin: approximately 10-20% in all conditions) were equal in all conditions. Overall, the results suggest that the scaffold sheets promote axon outgrowth that can be guided across the scaffold, thereby promoting hindlimb recovery. This study provides a hydrogel scaffold construct that can be used in vitro for cell characterization or in vivo for future neuroprosthetics, devices, or cell and ECM delivery.

The global impact of COVID-19 on abortion care.

Background: The COVID-19 pandemic placed unprecedented strain on healthcare globally, which exacerbated factors leading to unplanned pregnancies. Objectives: The primary objective was to analyze the effect of COVID-19 on abortion services globally. Secondary objectives were to discuss issues regarding access to safe abortion and provide recommendations on continued access during pandemics. Search strategy: A search for relevant articles was conducted by utilizing multiple databases (PubMed, Cochrane, etc.). Selection criteria: Studies on COVID-19 and abortion were included. Data collection & analysis: The legislation governing abortion services across the globe was examined, inclusive of modifications to service provision during the pandemic. Global data on abortion rates and analyses of selected articles were also included. Main results: 14 countries instituted legislative changes related to the pandemic, 11 relaxed abortion regulations, while three restricted abortion access. An increase in abortion rates was seen particularly where telemedicine was available. Where abortions were postponed, second-trimester abortions increased after services resumed. Conclusions: Legislation, risk of exposure to infection, and access to telemedicine affect access to abortion. The use of novel technologies, maintaining existing infrastructure and enhancing the roles of trained manpower for safe abortion access is recommended to avoid the marginalization of women's health and reproductive rights.

Dysregulated Lipid Synthesis by Oncogenic IDH1 Mutation Is a Targetable Synthetic Lethal Vulnerability.

Isocitrate dehydrogenase 1 and 2 (IDH) are mutated in multiple cancers and drive production of (R)-2-hydroxyglutarate (2HG). We identified a lipid synthesis enzyme [acetyl CoA carboxylase 1 (ACC1)] as a synthetic lethal target in mutant IDH1 (mIDH1), but not mIDH2, cancers. Here, we analyzed the metabolome of primary acute myeloid leukemia (AML) blasts and identified an mIDH1-specific reduction in fatty acids. mIDH1 also induced a switch to b-oxidation indicating reprogramming of metabolism toward a reliance on fatty acids. Compared with mIDH2, mIDH1 AML displayed depletion of NADPH with defective reductive carboxylation that was not rescued by the mIDH1-specific inhibitor ivosidenib. In xenograft models, a lipid-free diet markedly slowed the growth of mIDH1 AML, but not healthy CD34+ hematopoietic stem/progenitor cells or mIDH2 AML. Genetic and pharmacologic targeting of ACC1 resulted in the growth inhibition of mIDH1 cancers not reversible by ivosidenib. Critically, the pharmacologic targeting of ACC1 improved the sensitivity of mIDH1 AML to venetoclax. SIGNIFICANCE: Oncogenic mutations in both IDH1 and IDH2 produce 2-hydroxyglutarate and are generally considered equivalent in terms of pathogenesis and targeting. Using comprehensive metabolomic analysis, we demonstrate unexpected metabolic differences in fatty acid metabolism between mutant IDH1 and IDH2 in patient samples with targetable metabolic interventions. See related commentary by Robinson and Levine, p. 266. This article is highlighted in the In This Issue feature, p. 247.

A senescence stress secretome is a hallmark of therapy-related myeloid neoplasm stromal tissue occurring soon after cytotoxic exposure.

Therapy-related myeloid neoplasm (tMN) is considered a direct consequence of DNA damage in hematopoietic stem cells. Despite increasing recognition that altered stroma can also drive leukemogenesis, the functional biology of the tMN microenvironment remains unknown. We performed multiomic (transcriptome, DNA damage response, cytokine secretome and functional profiling) characterization of bone marrow stromal cells from tMN patients. Critically, we also compared (i) patients with myeloid neoplasm and another cancer but without cytotoxic exposure, (ii) typical primary myeloid neoplasm, and (iii) age-matched controls to decipher the microenvironmental changes induced by cytotoxics vs. neoplasia. Strikingly, tMN exhibited a profoundly senescent phenotype with induction of CDKN1A and ß-Galactosidase, defective phenotype, and proliferation. Moreover, tMN stroma showed delayed DNA repair and defective adipogenesis. Despite their dormant state, tMN stromal cells were metabolically highly active with a switch toward glycolysis and secreted multiple pro-inflammatory cytokines indicative of a senescent-secretory phenotype that inhibited adipogenesis. Critically, senolytics not only eliminated dormant cells, but also restored adipogenesis. Finally, sequential patient sampling showed senescence phenotypes are induced within months of cytotoxic exposure, well prior to the onset of secondary cancer. Our data underscores a role of senescence in the pathogenesis of tMN and provide a valuable resource for future therapeutics.

Germline mutations in mitochondrial complex I reveal genetic and targetable vulnerability in IDH1-mutant acute myeloid leukaemia.

The interaction of germline variation and somatic cancer driver mutations is under-investigated. Here we describe the genomic mitochondrial landscape in adult acute myeloid leukaemia (AML) and show that rare variants affecting the nuclear- and mitochondrially-encoded complex I genes show near-mutual exclusivity with somatic driver mutations affecting isocitrate dehydrogenase 1 (IDH1), but not IDH2 suggesting a unique epistatic relationship. Whereas AML cells with rare complex I variants or mutations in IDH1 or IDH2 all display attenuated mitochondrial respiration, heightened sensitivity to complex I inhibitors including the clinical-grade inhibitor, IACS-010759, is observed only for IDH1-mutant AML. Furthermore, IDH1 mutant blasts that are resistant to the IDH1-mutant inhibitor, ivosidenib, retain sensitivity to complex I inhibition. We propose that the IDH1 mutation limits the flexibility for citrate utilization in the presence of impaired complex I activity to a degree that is not apparent in IDH2 mutant cells, exposing a mutation-specific metabolic vulnerability. This reduced metabolic plasticity explains the epistatic relationship between the germline complex I variants and oncogenic IDH1 mutation underscoring the utility of genomic data in revealing metabolic vulnerabilities with implications for therapy.

Targeting human CALR-mutated MPN progenitors with a neoepitope-directed monoclonal antibody.

Calreticulin (CALR) is recurrently mutated in myelofibrosis via a frameshift that removes an endoplasmic reticulum retention signal, creating a neoepitope potentially targetable by immunotherapeutic approaches. We developed a specific rat monoclonal IgG2α antibody, 4D7, directed against the common sequence encoded by both insertion and deletion mutations. 4D7 selectively bound to cells co-expressing mutant CALR and thrombopoietin receptor (TpoR) and blocked JAK-STAT signalling, TPO-independent proliferation and megakaryocyte differentiation of mutant CALR myelofibrosis progenitors by disrupting the binding of CALR dimers to TpoR. Importantly, 4D7 inhibited proliferation of patient samples with both insertion and deletion CALR mutations but not JAK2 V617F and prolonged survival in xenografted bone marrow models of mutant CALR-dependent myeloproliferation. Together, our data demonstrate a novel therapeutic approach to target a problematic disease driven by a recurrent somatic mutation that would normally be considered undruggable.

Neonatal heel prick mass spectrometry identifies metabolic predictors of AML latency.

Ongoing research efforts that consider cancer as a disease of dramatically altered cellular metabolism have accelerated interest in snapshot metabolomics in various human tissues. In this issue of Leukemia Research, Petrick et al performed metabolomic analysis on newborn blood spots and found a number of unexpected ceramide and sphingolipid compounds that may play a role in the development and latency of pediatric acute myeloid leukemia (AML). The chemical complexity and range of cellular metabolites massively exceeds the relatively limited building blocks of the transcriptome or the proteome and has high potential to find novel leukemia-specific macromolecular synthesis pathways, metabolic vulnerabilities and biomarkers.

Adsorptive Spin Coating To Study Thin-Film Stability in Both Wetting and Nonwetting Regimes.

A new thin-film fabrication method, adsorptive spin coating, was evaluated in the preparation of poly(vinyl alcohol) (PVOH) thin films on silicon-wafer-supported poly(dimethylsiloxane) (PDMS) substrates. This method takes advantage of the rapid spontaneous adsorption of PVOH at the substrate-solution interface during the brief contact period and the directionality of drying during spinning. Similar to the results obtained using dip coating, the PVOH thin films wet the 2 kDa PDMS substrate and exhibit dewetted fractal morphologies on thicker PDMS substrates. This method generated PVOH films with thicknesses that were comparable to those prepared by dip coating except that thicker PVOH films were obtained at lower spin rates, following the Meyerhofer relationship in the wetting regime. Stepwise dewetting dynamics of confined PVOH drops were captured using high-speed photography. Drying and polymer aggregation initiate at the periphery of the drop and propagate toward the center of the drop. Each dewetted thin film adopts the footprint of the original drop and shows globally ordered patterns, which depend on both initial drop size and spin rate. The PVOH thin films have excellent stability toward water rinse if they are continuous and are given sufficient time to dry. This new adsorptive spin-coating method is not only straightforward but also unique in its ability to generate globally ordered morphologies that are the outcome of fast spontaneous adsorption, spin symmetry, and temporally and spatially adjustable drying rates. It is a valuable tool for fabricating a wide range of thin-film systems where surface adsorption/reaction is rapid, in both wetting and nonwetting regimes.

Controlling the Surface Chemistry of a Hydrogel for Spatially Defined Cell Adhesion.

A two-step synthesis is described for activating the surface of a fully hydrated hydrogel that is of interest as a possible scaffold for neural regeneration devices. The first step exploits the water content of the hydrogel and the hydrophobicity of the reaction solvent to create a thin oxide layer on the hydrogel surface using a common titanium or zirconium alkoxide. This layer serves as a reactive interface that enables rapid transformation of the hydrophilic, cell-nonadhesive hydrogel into either a highly hydrophobic surface by reaction with an alkylphosphonic acid, or into a cell-adhesive one using a (α,ω-diphosphono)alkane. Physically imprinting a mask ("debossing") into the hydrogel, followed by a two-step surface modification with a phosphonate, allows for patterning its surface to create spatially defined, cell-adhesive regions.

Perforation Does Not Compromise Patterned Two-Dimensional Substrates for Cell Attachment and Aligned Spreading.

Polymeric sheets were perforated by laser ablation and were uncompromised by a debris field when first treated with a thin layer of photoresist. Polymer sheets perforated with holes comprising 5, 10, and 20% of the nominal surface area were then patterned in stripes by photolithography, which was followed by synthesis in exposed regions of a cell-attractive zirconium oxide-1,4-butanediphosphonic acid interface. Microscopic and scanning electron microscopy analyses following removal of unexposed photoresist show well-aligned stripes for all levels of these perforations. NIH 3T3 fibroblasts plated on each of these perforated surfaces attached to the interface and spread in alignment with pattern fidelity in every case that is as high as that measured on a nonperforated, patterned substrate.

Repression of NHE1 expression by PPARgamma activation is a potential new approach for specific inhibition of the growth of tumor cells in vitro and in vivo.

Ligand-induced activation of peroxisome proliferator-activated receptor gamma (PPARgamma) inhibits proliferation in cancer cells in vitro and in vivo; however, the downstream targets remain undefined. We report the identification of a peroxisome proliferator response element in the promoter region of the Na(+)/H(+) transporter gene NHE1, the overexpression of which has been associated with carcinogenesis. Exposure of breast cancer cells expressing high levels of PPARgamma to its natural and synthetic agonists resulted in downregulation of NHE1 transcription as well as protein expression. Furthermore, the inhibitory effect of activated PPARgamma on tumor colony-forming ability was abrogated on overexpression of NHE1, whereas small interfering RNA-mediated gene silencing of NHE1 significantly increased the sensitivity of cancer cells to growth-inhibitory stimuli. Finally, histopathologic analysis of breast cancer biopsies obtained from patients with type II diabetes treated with the synthetic agonist rosiglitazone showed significant repression of NHE1 in the tumor tissue. These data provide evidence for tumor-selective downregulation of NHE1 by activated PPARgamma in vitro and in pathologic specimens from breast cancer patients and could have potential implications for the judicious use of low doses of PPARgamma ligands in combination chemotherapy regimens for an effective therapeutic response.

Preliminary evidence for a link between schizophrenia and NMDA-glycine site receptor ligand metabolic enzymes, d-amino acid oxidase (DAAO) and kynurenine aminotransferase-1 (KAT-1).

Preliminary investigations, studying gene expression and biochemical activities of enzymes d-amino acid oxidase (DAAO) and kynurenine aminotransferase-1 (KAT-1), revealed elevated cerebellar KAT-1 and DAAO activities in post-mortem brain samples from schizophrenic versus normal individuals. In addition, we have identified a transcript of DAAO, which was expressed in significantly higher quantities in the diseased cerebellum but not detected in the parietal cortex where DAAO activity is absent.