An immune cell atlas reveals the dynamics of human macrophage specification during prenatal development.

Macrophages are heterogeneous and play critical roles in development and disease, but their diversity, function, and specification remain inadequately understood during human development. We generated a single-cell RNA sequencing map of the dynamics of human macrophage specification from PCW 4-26 across 19 tissues. We identified a microglia-like population and a proangiogenic population in 15 macrophage subtypes. Microglia-like cells, molecularly and morphologically similar to microglia in the CNS, are present in the fetal epidermis, testicle, and heart. They are the major immune population in the early epidermis, exhibit a polarized distribution along the dorsal-lateral-ventral axis, and interact with neural crest cells, modulating their differentiation along the melanocyte lineage. Through spatial and differentiation trajectory analysis, we also showed that proangiogenic macrophages are perivascular across fetal organs and likely yolk-sac-derived as microglia. Our study provides a comprehensive map of the heterogeneity and developmental dynamics of human macrophages and unravels their diverse functions during development.

LGR5 expressing skin fibroblasts define a major cellular hub perturbed in scleroderma.

Systemic sclerosis (scleroderma, SSc) is an incurable autoimmune disease with high morbidity and mortality rates. Here, we conducted a population-scale single-cell genomic analysis of skin and blood samples of 56 healthy controls and 97 SSc patients at different stages of the disease. We found immune compartment dysfunction only in a specific subtype of diffuse SSc patients but global dysregulation of the stromal compartment, particularly in a previously undefined subset of LGR5+-scleroderma-associated fibroblasts (ScAFs). ScAFs are perturbed morphologically and molecularly in SSc patients. Single-cell multiome profiling of stromal cells revealed ScAF-specific markers, pathways, regulatory elements, and transcription factors underlining disease development. Systematic analysis of these molecular features with clinical metadata associates specific ScAF targets with disease pathogenesis and SSc clinical traits. Our high-resolution atlas of the sclerodermatous skin spectrum will enable a paradigm shift in the understanding of SSc disease and facilitate the development of biomarkers and therapeutic strategies.

Coupled scRNA-Seq and Intracellular Protein Activity Reveal an Immunosuppressive Role of TREM2 in Cancer.

Cell function and activity are regulated through integration of signaling, epigenetic, transcriptional, and metabolic pathways. Here, we introduce INs-seq, an integrated technology for massively parallel recording of single-cell RNA sequencing (scRNA-seq) and intracellular protein activity. We demonstrate the broad utility of INs-seq for discovering new immune subsets by profiling different intracellular signatures of immune signaling, transcription factor combinations, and metabolic activity. Comprehensive mapping of Arginase 1-expressing cells within tumor models, a metabolic immune signature of suppressive activity, discovers novel Arg1+ Trem2+ regulatory myeloid (Mreg) cells and identifies markers, metabolic activity, and pathways associated with these cells. Genetic ablation of Trem2 in mice inhibits accumulation of intra-tumoral Mreg cells, leading to a marked decrease in dysfunctional CD8+ T cells and reduced tumor growth. This study establishes INs-seq as a broadly applicable technology for elucidating integrated transcriptional and intra-cellular maps and identifies the molecular signature of myeloid suppressive cells in tumors.

ß-Glucan Reverses the Epigenetic State of LPS-Induced Immunological Tolerance.

Innate immune memory is the phenomenon whereby innate immune cells such as monocytes or macrophages undergo functional reprogramming after exposure to microbial components such as lipopolysaccharide (LPS). We apply an integrated epigenomic approach to characterize the molecular events involved in LPS-induced tolerance in a time-dependent manner. Mechanistically, LPS-treated monocytes fail to accumulate active histone marks at promoter and enhancers of genes in the lipid metabolism and phagocytic pathways. Transcriptional inactivity in response to a second LPS exposure in tolerized macrophages is accompanied by failure to deposit active histone marks at promoters of tolerized genes. In contrast, ß-glucan partially reverses the LPS-induced tolerance in vitro. Importantly, ex vivo ß-glucan treatment of monocytes from volunteers with experimental endotoxemia re-instates their capacity for cytokine production. Tolerance is reversed at the level of distal element histone modification and transcriptional reactivation of otherwise unresponsive genes. VIDEO ABSTRACT.

The Allelic Landscape of Human Blood Cell Trait Variation and Links to Common Complex Disease.

Many common variants have been associated with hematological traits, but identification of causal genes and pathways has proven challenging. We performed a genome-wide association analysis in the UK Biobank and INTERVAL studies, testing 29.5 million genetic variants for association with 36 red cell, white cell, and platelet properties in 173,480 European-ancestry participants. This effort yielded hundreds of low frequency (<5%) and rare (<1%) variants with a strong impact on blood cell phenotypes. Our data highlight general properties of the allelic architecture of complex traits, including the proportion of the heritable component of each blood trait explained by the polygenic signal across different genome regulatory domains. Finally, through Mendelian randomization, we provide evidence of shared genetic pathways linking blood cell indices with complex pathologies, including autoimmune diseases, schizophrenia, and coronary heart disease and evidence suggesting previously reported population associations between blood cell indices and cardiovascular disease may be non-causal.

Multi-tissue single-cell analysis deconstructs the complex programs of mouse natural killer and type 1 innate lymphoid cells in tissues and circulation.

Natural killer (NK) cells and type 1 innate lymphoid cells (ILC1s) are heterogenous innate lymphocytes broadly defined in mice as Lin-NK1.1+NKp46+ cells that express the transcription factor T-BET and produce interferon-γ. The ILC1 definition primarily stems from studies on liver and small intestinal populations. However, NK1.1+NKp46+ cells in the salivary glands, uterus, adipose, and other tissues exhibit nonuniform programs that differ from those of liver or intestinal ILC1s or NK cells. Here, we performed single-cell RNA sequencing on murine NK1.1+NKp46+ cells from blood, spleen, various tissues, and solid tumors. We identified gene expression programs of tissue-specific ILC1s, tissue-specific NK cells, and non-tissue-specific populations in blood, spleen, and other tissues largely corresponding to circulating cells. Moreover, we found that circulating NK cell programs were reshaped in tumor-bearing mice. Core programs of circulating and tumor NK cells paralleled conserved human NK cells signatures, advancing our understanding of the human NK-ILC1 spectrum.

Enhanced charge-carrier dynamics and efficient solar-to-urea conversion on Si-based photocathodes.

Photoelectrochemical (PEC) coupling of CO2 and nitrate can provide a useful and green source of urea, but the process is affected by the photocathodes with poor charge-carrier dynamics and low conversion efficiency. Here, a NiFe diatomic catalysts/TiO2 layer/nanostructured n+p-Si photocathode is rationally designed, achieving a good charge-separation efficiency of 78.8% and charge-injection efficiency of 56.9% in the process of PEC urea synthesis. Compared with the electrocatalytic urea synthesis by using the same catalysts, the Si-based photocathode shows a similar urea yield rate (81.1 mg·h-1·cm-2) with a higher faradic efficiency (24.2%, almost twice than the electrocatalysis) at a lower applied potential under 1 sun illumination, meaning that a lower energy-consumption method acquires more aimed productions. Integrating the PEC measurements and characterization results, the synergistic effect of hierarchical structure is the dominating factor for enhancing the charge-carrier separation, transfer, and injection by the matched band structure and favorable electron-migration channels. This work provides a direct and efficient route of solar-to-urea conversion.

Spatially Confined Microcells: A Path toward TMD Catalyst Design.

With the ability to maximize the exposure of nearly all active sites to reactions, two-dimensional transition metal dichalcogenide (TMD) has become a fascinating new class of materials for electrocatalysis. Recently, electrochemical microcells have been developed, and their unique spatial-confined capability enables understanding of catalytic behaviors at a single material level, significantly promoting this field. This Review provides an overview of the recent progress in microcell-based TMD electrocatalyst studies. We first introduced the structural characteristics of TMD materials and discussed their site engineering strategies for electrocatalysis. Later, we comprehensively described two distinct types of microcells: the window-confined on-chip electrochemical microcell (OCEM) and the droplet-confined scanning electrochemical cell microscopy (SECCM). Their setups, working principles, and instrumentation were elucidated in detail, respectively. Furthermore, we summarized recent advances of OCEM and SECCM obtained in TMD catalysts, such as active site identification and imaging, site monitoring, modulation of charge injection and transport, and electrostatic field gating. Finally, we discussed the current challenges and provided personal perspectives on electrochemical microcell research.

Promoted hydrogen and acetaldehyde production from alcohol dehydrogenation enabled by electrochemical hydrogen pumps.

The dehydrogenation reaction of bioderived ethanol is of particular interest for the synthesis of fuels and value-added chemicals. However, this reaction historically suffered from high energy consumption (>260 °C or >0.8 V) and low efficiency. Herein, the efficient conversion of alcohol to hydrogen and aldehyde is achieved by integrating the thermal dehydrogenation reaction with electrochemical hydrogen transfer at low temperature (120 °C) and low voltage (0.06 V), utilizing a bifunctional catalyst (Ru/C) with both thermal-catalytic and electrocatalytic activities. Specifically, the coupled electrochemical hydrogen separation procedure can serve as electrochemical hydrogen pumps, which effectively promote the equilibrium of ethanol dehydrogenation toward hydrogen and acetaldehyde production and simultaneously purifies hydrogen at the cathode. By utilizing this strategy, we achieved boosted hydrogen and acetaldehyde yields of 1,020 mmol g-1 h-1 and 1,185 mmol g-1 h-1, respectively, which are threefold higher than the exclusive ethanol thermal dehydrogenation. This work opens up a prospective route for the high-efficiency production of hydrogen and acetaldehyde via coupled thermal-electrocatalysis.

Electrocatalytic Urea Synthesis via C-N Coupling from CO2 and Nitrogenous Species.

ConspectusIndustrial urea synthesis consists of the Haber-Bosch process to produce ammonia and the subsequent Bosch-Meiser process to produce urea. Compared to the conventional energy-intensive urea synthetic protocol, electrocatalytic C-N coupling from CO2 and nitrogenous species emerges as a promising alternative to construct a C-N bond under ambient conditions and to realize the direct synthesis of high-value urea products via skipping the intermediate step of ammonia production. The main challenges for electrocatalytic C-N coupling lie in the intrinsic inertness of molecules and the competition with parallel side reactions. In this Account, we give an overview of our recent progress toward electrocatalytic C-N coupling from CO2 and nitrogenous species toward urea synthesis.To begin, we present the direct transformation of dinitrogen (N2) to the C-N bond by coelectrolysis, verifying the feasibility of direct urea synthesis from N2 and CO2 under ambient conditions. In contrast to the highly endothermic step of proton coupling in conventional N2 reduction, the N2 activation and construction of the C-N bond arise from a thermodynamic spontaneous reaction between CO (derived from CO2 reduction) and *N═N* (the asterisks represent the adsorption sites), and the crucial *NCON* species mediates the interconversion of N2, CO2, and urea. Based on theoretical guidance, the effect of N2 adsorption configurations on C-N coupling is investigated on the model catalysts with defined active site structure, revealing that the side-on adsorption rather than the end-on one favors C-N coupling and urea synthesis.Electrocatalytic C-N coupling of CO2 and nitrate (NO3-) is also an effective pathway to achieve direct urea synthesis. We summarize our progress in the C-N coupling of CO2 and NO3-, from the aspects of modulating intermediate species adsorption and reaction paths, monitoring irreversible and reversible reconstruction of active sites, and precisely constructing active sites to match activities and to boost the electrocatalytic urea synthesis. In each case, in situ electrochemical technologies and density functional theory (DFT) calculations are carried out to unveil the microscopic mechanisms for the promotion of C-N coupling and the enhancement of urea synthesis activity. In the last section, we put forward the limitations, challenges, and perspectives in these two coupling systems for further development of electrocatalytic urea synthesis.

Electrocatalytic Coupling of Nitrate and Formaldehyde for Hexamethylenetetramine Synthesis via C-N Bond Construction and Ring Formation.

Hexamethylenetetramine (HMTA) is extensively used in the defense industry, medicines, food, plastics, rubber, and other applications. Traditional organic synthesis of HMTA relies on ammonia derived from the Haber process at high temperatures and pressures. In contrast, electrochemical methods enable a safe and green one-pot synthesis of HMTA from waste NO3-. However, HMTA synthesis through the electrochemical method is challenging owing to the complex reaction pathways involving C-N bond construction and ring formation. In this study, HMTA was efficiently synthesized over electrochemical oxidation-derived copper (e-OD-Cu), with a yield of 76.8% and a Faradaic efficiency of 74.9% at -0.30 VRHE. The catalytic mechanism and reaction pathway of HMTA synthesis on e-OD-Cu were investigated through a series of in situ characterization methods and density-functional theory calculations. The results demonstrated that the electrocatalytic synthesis of HMTA involved a tandem electrochemical-chemical reaction. Additionally, the results indicated that the presence of Cu vacancies enhanced substrate adsorption and inhibited the further hydrogenation of C═N. Overall, this study provides an electrocatalytic method for HMTA synthesis and an electrochemical strategy for constructing multiple C-N bonds.

Electrocatalysis Boosts the Methanol Thermocatalytic Dehydrogenation for High-Purity H2 and CO Production.

Hydrogen production from methanol represents an energy-sustainable way to produce ethanol, but it normally results in heavy CO2 emissions. The selective conversion of methanol into H2 and valuable chemical feedstocks offers a promising strategy; however, it is limited by the harsh operating conditions and low conversion efficiency. Herein, we realize efficient high-purity H2 and CO production from methanol by coupling the thermocatalytic methanol dehydrogenation with electrocatalytic hydrogen oxidation on a bifunctional Ru/C catalyst. Electrocatalysis enables the acceleration of C-H cleavage and reduces the partial pressure of hydrogen at the anode, which drives the chemical equilibrium and significantly enhances methanol dehydrogenation. Furthermore, a bilayer Ru/C + Pd/C electrode is designed to mitigate CO poisoning and facilitate hydrogen oxidation. As a result, a high yield of H2 (558.54 mmol h-1 g-1) with high purity (99.9%) was achieved by integrating an applied cell voltage of 0.4 V at 200 °C, superior to the conventional thermal and electrocatalytic processes, and CO is the main product at the anode. This work presents a new avenue for efficient H2 production together with valuable chemical synthesis from methanol.

Catalyst Selection over an Electrochemical Reductive Coupling Reaction toward Direct Electrosynthesis of Oxime from NOx and Aldehyde.

Aqueous electrochemical coupling reactions, which enable the green synthesis of complex organic compounds, will be a crucial tool in synthetic chemistry. However, a lack of informed approaches for screening suitable catalysts is a major obstacle to its development. Here, we propose a pioneering electrochemical reductive coupling reaction toward direct electrosynthesis of oxime from NOx and aldehyde. Through integrating experimental and theoretical methods, we screen out the optimal catalyst, i.e., metal Fe catalyst, that facilitates the enrichment and C-N coupling of key reaction intermediates, all leading to high yields (e.g., ∼99% yield of benzaldoxime) for the direct electrosynthesis of oxime over Fe. With a divided flow reactor, we achieve a high benzaldoxime production of 22.8 g h-1 gcat-1 in ∼94% isolated yield. This work not only paves the way to the industrial mass production of oxime via electrosynthesis but also offers references for the catalyst selection of other electrochemical coupling reactions.

Interfacial Micro-Environment of Electrocatalysis and Its Applications for Organic Electro-Oxidation Reaction.

Conventional designing principal of electrocatalyst is focused on the electronic structure tuning, on which effectively promotes the electrocatalysis. However, as a typical kind of electrode-electrolyte interface reaction, the electrocatalysis performance is also closely dependent on the electrocatalyst interfacial micro-environment (IME), including pH, reactant concentration, electric field, surface geometry structure, hydrophilicity/hydrophobicity, etc. Recently, organic electro-oxidation reaction (OEOR), which simultaneously reduces the anodic polarization potential and produces value-added chemicals, has emerged as a competitive alternative to oxygen evolution reaction, and the role IME played in OEOR is receiving great interest. Thus, this article provides a timely review on IME and its applications toward OEOR. In this review, the IME for conventional gas-involving reactions, as a contrast, is first presented, and then the recent progresses of IME toward diverse typical OEOR are summarized; especially, some representative works are thoroughly discussed. Additionally, cutting-edge analytical methods and characterization techniques are introduced to comprehensively understand the role IME played in OEOR. In the last section, perspectives and challenges of IME regulation for OEOR are shared.

Tip-like Fe-N4 Sites Induced Surface Microenvironments Regulation Boosts the Oxygen Reduction Reaction.

Single atom catalysts with defined local structures and favorable surface microenvironments are significant for overcoming slow kinetics and accelerating O2 electroreduction. Here, enriched tip-like FeN4 sites (T-Fe SAC) on spherical carbon surfaces were developed to investigate the change in surface microenvironments and catalysis behavior. Finite element method (FEM) simulations, together with experiments, indicate the strong local electric field of the tip-like FeN4 and the more denser interfacial water layer, thereby enhancing the kinetics of the proton-coupled electron transfer process. In situ spectroelectrochemical studies and the density functional theory (DFT) calculation results indicate the pathway transition on the tip-like FeN4 sites, promoting the dissociation of O-O bond via side-on adsorption model. The adsorbed OH* can be facilely released on the curved surface and accelerate the oxygen reduction reaction (ORR) kinetics. The obtained T-Fe SAC nanoreactor exhibits excellent ORR activities (E1/2 =0.91 V vs. RHE) and remarkable stability, exceeding those of flat FeN4 and Pt/C. This work clarified the in-depth insights into the origin of catalytic activity of tip-like FeN4 sites and held great promise in industrial catalysis, electrochemical energy storage, and many other fields.

Vacancy-induced catalytic mechanism for alcohol electrooxidation on nickel-based electrocatalyst.

Owing to outstanding performances, nickel-based electrocatalysts are commonly used in electrochemical alcohol oxidation reactions (AORs), and the active phase is usually vacancy-rich nickel oxide/hydroxide (NiOx Hy ) species. However, researchers are not aware of the catalytic role of atom vacancy in AORs. Here, we study vacancy-induced catalytic mechanisms for AORs on NiOx Hy species. As to AORs on oxygen-vacancy-poor ß-Ni(OH)2 , the only redox mediator is electrooxidation-induced electrophilic lattice oxygen species, which can only catalyze the dehydrogenation process (e.g., the electrooxidation of primary alcohol to carboxylic acid) instead of the C-C bond cleavage. Hence, vicinal diol electrooxidation reaction involving the C-C bond cleavage is not feasible with oxygen-vacancy-poor ß-Ni(OH)2 . Only through oxygen vacancy-induced adsorbed oxygen-mediated mechanism, can oxygen-vacancy-rich NiOx Hy species catalyze the electrooxidation of vicinal diol to carboxylic acid and formic acid accompanied with the C-C bond cleavage. Crucially, we examine how vacancies and vacancy-induced catalytic mechanisms work during AORs on NiOx Hy species.

A Universal Approach for Sustainable Urea Synthesis via Intermediate Assembly at the Electrode/Electrolyte Interface.

Electrocatalytic C-N coupling process is indeed a sustainable alternative for direct urea synthesis and co-upgrading of carbon dioxide and nitrate wastes. However, the main challenge lies in the unactivated C-N coupling process. Here, we proposed a strategy of intermediate assembly with alkali metal cations to activate C-N coupling at the electrode/electrolyte interface. Urea synthesis activity follows the trend of Li+

Efficient Low-temperature Hydrogen Production by Electrochemical-assisted Methanol Steam Reforming.

Methanol steam reforming (MSR) provides an alternative way for efficient production and safe transportation of hydrogen but requires harsh conditions and complicated purification processes. In this work, an efficient electrochemical-assisted MSR reaction for pure H2 production at lower temperature (~140 °C) is developed by coupling the electrocatalysis reaction into the MSR in a polymer electrolyte membrane electrolysis reactor. By electrochemically assisted, the two critical steps including the methanol dehydrogenation and water-gas shift reaction are accelerated, which is attributed to decreasing the methanol dehydrogenation energy and promoting the dissociation of H2 O to OH* by the applied potential. Furthermore, the reduced H2 partial pressure by the hydrogen oxidation and reduction process further promotes MSR. The combination of these advantages not only efficiently decreases the MSR temperature but also achieves the high rate of hydrogen production of 505 mmol H2 g Pt -1 h-1 with exceptionally high H2 selectivity (99 %) at 180 °C and a low voltage (0.4 V), and the productivity is about 30-fold than that of traditional MSR. This study opens up a new avenue to design novel electrolysis cells for hydrogen production.

Ultra-Low-Potential Methanol Oxidation on Single-Ir-Atom Catalyst.

Methanol oxidation plays a central role to implement sustainable energy economy, which is restricted by the sluggish reaction kinetics due to the multi-electron transfer process accompanied by numerous sequential intermediate. In this study, an efficient cascade methanol oxidation reaction is catalyzed by single-Ir-atom catalyst at ultra-low potential (<0.1 V) with the promotion of the thermal and electrochemical integration in a high temperature polymer electrolyte membrane electrolyzer. At the elevated temperature, the electron deficient Ir site with higher methanol affinity could spontaneous catalyze the CH3OH dehydrogenation to CO under the voltage, then the generated CO and H2 was electrochemically oxidized to CO2 and proton. However, the methanol cannot thermally decompose with the voltage absence, which confirm the indispensable of the coupling of thermal and electrochemical integration for the methanol oxidation. By assembling the methanol oxidation reaction with hydrogen evolution reaction with single-Ir-atom catalysts in the anode chamber, a max hydrogen production rate reaches 18 mol gIr -1 h-1, which is much greater than that of Ir nanoparticles and commercial Pt/C. This study also demonstrated the electrochemical methanol oxidation activity of the single atom catalysts, which broadens the renewable energy devices and the catalyst design by an integration concept.

Rewiring of 3D Chromatin Topology Orchestrates Transcriptional Reprogramming and the Development of Human Dilated Cardiomyopathy.

BACKGROUND: Transcriptional reconfiguration is central to heart failure, the most common cause of which is dilated cardiomyopathy (DCM). The effect of 3-dimensional chromatin topology on transcriptional dysregulation and pathogenesis in human DCM remains elusive. METHODS: We generated a compendium of 3-dimensional epigenome and transcriptome maps from 101 biobanked human DCM and nonfailing heart tissues through highly integrative chromatin immunoprecipitation (H3K27ac [acetylation of lysine 27 on histone H3]), in situ high-throughput chromosome conformation capture, chromatin immunoprecipitation sequencing, assay for transposase-accessible chromatin using sequencing, and RNA sequencing. We used human induced pluripotent stem cell-derived cardiomyocytes and mouse models to interrogate the key transcription factor implicated in 3-dimensional chromatin organization and transcriptional regulation in DCM pathogenesis. RESULTS: We discovered that the active regulatory elements (H3K27ac peaks) and their connectome (H3K27ac loops) were extensively reprogrammed in DCM hearts and contributed to transcriptional dysregulation implicated in DCM development. For example, we identified that nontranscribing NPPA-AS1 (natriuretic peptide A antisense RNA 1) promoter functions as an enhancer and physically interacts with the NPPA (natriuretic peptide A) and NPPB (natriuretic peptide B) promoters, leading to the cotranscription of NPPA and NPPB in DCM hearts. We revealed that DCM-enriched H3K27ac loops largely resided in conserved high-order chromatin architectures (compartments, topologically associating domains) and their anchors unexpectedly had equivalent chromatin accessibility. We discovered that the DCM-enriched H3K27ac loop anchors exhibited a strong enrichment for HAND1 (heart and neural crest derivatives expressed 1), a key transcription factor involved in early cardiogenesis. In line with this, its protein expression was upregulated in human DCM and mouse failing hearts. To further validate whether HAND1 is a causal driver for the reprogramming of enhancer-promoter connectome in DCM hearts, we performed comprehensive 3-dimensional epigenome mappings in human induced pluripotent stem cell-derived cardiomyocytes. We found that forced overexpression of HAND1 in human induced pluripotent stem cell-derived cardiomyocytes induced a distinct gain of enhancer-promoter connectivity and correspondingly increased the expression of their connected genes implicated in DCM pathogenesis, thus recapitulating the transcriptional signature in human DCM hearts. Electrophysiology analysis demonstrated that forced overexpression of HAND1 in human induced pluripotent stem cell-derived cardiomyocytes induced abnormal calcium handling. Furthermore, cardiomyocyte-specific overexpression of Hand1 in the mouse hearts resulted in dilated cardiac remodeling with impaired contractility/Ca2+ handling in cardiomyocytes, increased ratio of heart weight/body weight, and compromised cardiac function, which were ascribed to recapitulation of transcriptional reprogramming in DCM. CONCLUSIONS: This study provided novel chromatin topology insights into DCM pathogenesis and illustrated a model whereby a single transcription factor (HAND1) reprograms the genome-wide enhancer-promoter connectome to drive DCM pathogenesis.