Protection of tissue physicochemical properties using polyfunctional crosslinkers

Quantitative gradient recalled echo (qGRE) MRI enables in vivo measurement of pre-atrophic neurodegeneration in a mouse model of Alzheimer's disease

Robust methods are needed for preclinical evaluation of novel Alzheimer Disease (AD) therapies to accelerate drug discovery. Quantitative Gradient Recalled Echo (qGRE) MRI has shown promise to provide insight into neurodegeneration in AD prior to atrophy development in humans, highlighting areas of low neuronal density. In this study a novel qGRE method (20 echoes, TE=2-40ms) is shown to non-invasively measure the longitudinal neuronal loss in the hippocampus of a mouse model of AD tauopathy Tg4510. Tg4510 (n=10) and wild type (WT, n=6) mice underwent MRI (7T field strength) at 3-7 months old. 3D qGRE approach was used to generate brain-specific R2* maps free of magnetic field inhomogeneity artifacts. Light-sheet microscopy of the brains stained with NeuN and MBP served to visualize neuronal nuclei and myelin content respectively. Significant decrease in NeuN staining between 3mo and 5mo was observed in the hippocampus of Tg4510, validating the mouse AD model. Longitudinal analysis showed clear decreases in R2* metric of qGRE signal in the Tg4510 mice hippocampus undergoing neurodegeneration between 3 and 5 months old. Histogram analysis revealed an upward trend in patterns of low R2* value (Dark Matter, DM), and broadening of R2* distribution. These were quantified as significant increase in both DM Volume Fraction (DMVF) and R2* Standard Deviation (SD) in Tg4510 mice (p=0.004/p=0.016 DMVF/SD) but not in WT controls (p>0.25). Further monotonical increase was also observed in both metrics in time. A significant negative correlation was observed between the DMVF and myelin content (p=0.01, r=-0.76), suggesting sensitivity of the technique to the loss of myelinated axons. The presented qGRE technique, validated by histological measurements, can be readily applied as in vivo tool in preclinical models of neurodegeneration for pharmacodynamics and mechanism of action assessment.

Customized Hydrogel Films for MicroRNA Super-Resolution Imaging in Liquid Biopsies

Tissue biopsy for early diagnosis and monitoring comes with several challenges, such as its invasiveness, and issues related to tissue heterogeneity in sampling. To address these issues, researchers have proposed a noninvasive approach called liquid biopsy, which uses blood samples to detect specific noncoding RNA (microRNA, miRNA). However, the current process of isolating and amplifying miRNA can be time-consuming and yield nonspecific results. In this study, a new super-resolution imaging tool is introduced that utilizes a thin, hydrogel-based liquid view (LV) film. This film can undergo a ninefold expansion and allows the analysis of cells obtained from liquid biopsy. The potential of the LV film is validated as a tool for early diagnosis and prognosis by testing biofluids derived from a variety of diseases. This method is confirmed to accurately analyze a greater number of miRNAs with higher sensitivity in a shorter time compared to other analytical methods. These findings suggest that the LV film provides high specificity, and multiplexing in detecting small amounts of miRNAs within cells, making it suitable for 3D implementation. It is proposed that liquid biopsy with LV films can be a solution to limitations related to the invasiveness, cost, and time-consuming nature of molecular analysis.

Reconfigurable Hanging Drop Microarray Platform for On-Demand Preparation and Analysis of Spheroid Array

In response to the increasing demand for spheroid-based cancer research, the importance of developing integrated platforms that can simultaneously facilitate high-throughput spheroid production and multiplexed analysis is emphasized. In addition, the understanding of how the size and cellular composition of tumors directly influence their internal structures and functionalities underlines the critical need to produce spheroids of diverse sizes and compositions on a large scale. To address this rising demand, this work presents a configurable and linkable in vitro three-dimensional (3D) cell culture kit (CLiCK) for spheroids, termed CLiCK-Spheroid. This platform consists of three primary components: a hanging drop microarray (HDMA), a concave pillar microarray (CPMA), and gradient blocks. The HDMA alone produces a homogeneous spheroid array, while its combination with the gradient block enables one-step generation of a size-gradient spheroid array. Using the size-gradient spheroid arrays, the occurrence of necrotic cores based on spheroid size is demonstrated. Additionally, spheroids in a single batch can be conveniently compartmentalized and regrouped using a CPMA, enhancing the versatility of spheroid arrays and enabling multiplexed drug treatments. By combining the different assembly methods, this work has achieved high-throughput production of cell composition-gradient spheroid arrays, with noticeable variations in morphology and vascularization based on cell compositions.

Sex differences in nucleus accumbens core circuitry engaged by binge-like ethanol drinking

Growing parity in Alcohol Use Disorder (AUD) diagnoses in men and women necessitates consideration of sex as a biological variable. In humans and rodents, the nucleus accumbens core (NAcc) regulates alcohol binge drinking, a risk factor for developing AUD. We labeled NAcc inputs with a viral retrograde tracer and quantified whole-brain c-Fos to determine the regions and NAcc inputs differentially engaged in male and female mice during binge-like ethanol drinking. We found that binge-like ethanol drinking females had 129 brain areas with greater c-Fos than males. Moreover, ethanol engaged more NAcc inputs in binge-like ethanol drinking females (as compared with males), including GABAergic and glutamatergic inputs. Relative to water controls, ethanol increased network modularity and decreased connectivity in both sexes and did so more dramatically in males. These results demonstrate that early-stage binge-like ethanol drinking engages brain regions and NAcc-inputs and alters network dynamics in a sex-specific manner.

Endothelial β1 Integrins are Necessary for Microvascular Function and Glucose Uptake

Microvascular insulin delivery to myocytes is rate limiting for the onset of insulin-stimulated muscle glucose uptake. The structural integrity of capillaries of the microvasculature is regulated, in part, by a family of transmembrane adhesion receptors known as integrins, which are composed of an α and β subunit. The integrin β1 (itgβ1) subunit is highly expressed in endothelial cells (EC). EC itgβ1 is necessary for the formation of capillary networks during embryonic during development and its knockdown in adult mice blunts the reactive hyperemia that manifests during ischemia reperfusion. In this study we investigated the contribution of skeletal muscle EC itgβ1 in microcirculatory function and glucose uptake. We hypothesized that loss of EC itgβ1 would impair microvascular hemodynamics and glucose uptake during insulin stimulation, creating 'delivery'-mediated insulin resistance. An itgβ1 knockdown mouse model was developed to avoid lethality of embryonic gene knockout and the deteriorating health resulting from early post-natal inducible gene deletion. We found that mice with (itgβ1 fl/fl SCLcre) and without (itgβ1 fl/fl ) inducible stem cell leukemia cre recombinase (SLCcre) expression at 10 days post cre induction have comparable exercise tolerance and pulmonary and cardiac functions. We quantified microcirculatory hemodynamics using intravital microscopy and the ability of mice to respond to the high metabolic demands of insulin-stimulated muscle using a hyperinsulinemic-euglycemia clamp. We show that itgβ1 fl/fl SCLcre mice compared to itgβ1 fl/fl littermates have, i) deficits in capillary flow rate, flow heterogeneity, and capillary density; ii) impaired insulin-stimulated glucose uptake despite sufficient transcapillary insulin efflux; and iii) reduced insulin-stimulated glucose uptake due to perfusion-limited glucose delivery. Thus, EC itgβ1 is necessary for microcirculatory function and to meet the metabolic challenge of insulin stimulation.

Early life psychosocial stress increases binge-like ethanol consumption and CSF1R inhibition prevents stress-induced alterations in microglia and brain macrophage population density

Early life stress (ELS) has lasting consequences on microglia and brain macrophage function. During ELS, microglia and brain macrophages alter their engagement with synapses leading to changes in neuronal excitability. Further, ELS can induce innate immune memory formation in microglia and brain macrophages resulting in altered responsivity to future environmental stimuli. These alterations can result in lasting adaptations in circuit function and may mediate the relationship between ELS and the risk to develop alcohol use disorder (AUD). Whether microglia and brain macrophages truly mediate this relationship remains elusive. Here, we report: 1) an ELS model, psychosocial stress (PSS), increases binge-like ethanol consumption in early adulthood. 2) Repeated binge-like ethanol consumption increases microglia and brain macrophage population densities across the brain. 3) PSS may elicit innate immune memory formation in microglia and brain macrophages leading to altered population densities following repeated binge-like ethanol consumption. 4) Microglia and brain macrophage inhibition trended towards preventing PSS-evoked changes in binge-like ethanol consumption and normalized microglia and brain macrophage population densities. Therefore, our study suggests that acutely inhibiting microglia and brain macrophage function during periods of early life PSS may prevent innate immune memory formation and assist in reducing the risk to develop AUD.

Highlights

An early life psychosocial stress (PSS) exposure increases ethanol consumptionMicroglial inhibition during PSS trends towards reducing ethanol consumptionBinge ethanol consumption increases microglial count and alters cell proximityEarly life PSS alters microglial responsivity to binge ethanol consumptionMicroglial inhibition may prevent microglial innate immune memory formation.

An arginine-rich nuclear localization signal (ArgiNLS) strategy for streamlined image segmentation of single cells

High-throughput volumetric fluorescent microscopy pipelines can spatially integrate whole-brain structure and function at the foundational level of single cells. However, conventional fluorescent protein (FP) modifications used to discriminate single cells possess limited efficacy or are detrimental to cellular health. Here, we introduce a synthetic and nondeleterious nuclear localization signal (NLS) tag strategy, called "Arginine-rich NLS" (ArgiNLS), that optimizes genetic labeling and downstream image segmentation of single cells by restricting FP localization near-exclusively in the nucleus through a poly-arginine mechanism. A single N-terminal ArgiNLS tag provides modular nuclear restriction consistently across spectrally separate FP variants. ArgiNLS performance in vivo displays functional conservation across major cortical cell classes and in response to both local and systemic brain-wide AAV administration. Crucially, the high signal-to-noise ratio afforded by ArgiNLS enhances machine learning-automated segmentation of single cells due to rapid classifier training and enrichment of labeled cell detection within 2D brain sections or 3D volumetric whole-brain image datasets, derived from both staining-amplified and native signal. This genetic strategy provides a simple and flexible basis for precise image segmentation of genetically labeled single cells at scale and paired with behavioral procedures.

Microglial heterogeneity in the ischemic stroke mouse brain of both sexes

BACKGROUND

Ischemic stroke elicits a complex and sustained immune response in the brain. Immunomodulatory treatments have long held promise for improving stroke outcomes, yet none have succeeded in the clinical setting. This lack of success is largely due to our incomplete understanding of how immune cells respond to stroke. The objective of the current study was to dissect the effect of permanent stroke on microglia, the resident immune cells within the brain parenchyma.

METHODS

A permanent middle cerebral artery occlusion (pMCAO) model was used to induce ischemic stroke in young male and female mice. Microglia were sorted from fluorescence reporter mice after pMCAO or sham surgery and then subjected to single-cell RNA sequencing analysis. Various methods, including flow cytometry, RNA in situ hybridization, immunohistochemistry, whole-brain imaging, and bone marrow transplantation, were also employed to dissect the microglial response to stroke. Stroke outcomes were evaluated by infarct size and behavioral tests.

RESULTS

First, we showed the morphologic and spatial changes in microglia after stroke. We then performed single-cell RNA sequencing analysis on microglia isolated from sham and stroke mice of both sexes. The data indicate no major sexual dimorphism in the microglial response to permanent stroke. Notably, we identified seven potential stroke-associated microglial clusters, including four major clusters characterized by a disease-associated microglia-like signature, a highly proliferative state, a macrophage-like profile, and an interferon (IFN) response signature, respectively. Importantly, we provided evidence that the macrophage-like cluster may represent the long-sought stroke-induced microglia subpopulation with increased CD45 expression. Lastly, given that the IFN-responsive subset constitutes the most prominent microglial population in the stroke brain, we used fludarabine to pharmacologically target STAT1 signaling and found that fludarabine treatment improved long-term stroke outcome.

CONCLUSIONS

Our findings shed new light on microglia heterogeneity in stroke pathology and underscore the potential of targeting specific microglial populations for effective stroke therapies.

Enhancer AAVs for targeting spinal motor neurons and descending motor pathways in rodents and macaque

Experimental access to cell types within the mammalian spinal cord is severely limited by the availability of genetic tools. To enable access to lower motor neurons (LMNs) and LMN subtypes, which function to integrate information from the brain and control movement through direct innervation of effector muscles, we generated single cell multiome datasets from mouse and macaque spinal cords and discovered putative enhancers for each neuronal population. We cloned these enhancers into adeno-associated viral vectors (AAVs) driving a reporter fluorophore and functionally screened them in mouse. The most promising candidate enhancers were then extensively characterized using imaging and molecular techniques and further tested in rat and macaque to show conservation of LMN labeling. Additionally, we combined enhancer elements into a single vector to achieve simultaneous labeling of upper motor neurons (UMNs) and LMNs. This unprecedented LMN toolkit will enable future investigations of cell type function across species and potential therapeutic interventions for human neurodegenerative diseases.

Three Dimensional Multiscalar Neurovascular Nephron Connectivity Map of the Human Kidney Across the Lifespan

The human kidney is a vital organ with a remarkable ability to coordinate the activity of up to a million nephrons, its main functional tissue unit (FTU), and maintain homeostasis. We developed tissue processing and analytical methods to construct a 3D map of neurovascular nephron connectivity of the human kidney and glean insights into how this structural organization enables coordination of various functions of the nephron, such as glomerular filtration, solute and water absorption, secretion by the tubules, and regulation of blood flow and pressure by the juxtaglomerular apparatus, in addition to how these functions change across disease and lifespans. Using light sheet fluorescence microscopy (LSFM) and morphometric analysis we discovered changes in anatomical orientation of the vascular pole, glomerular density, volume, and innervation through postnatal development and ageing. The extensive nerve network exists from cortex FTUs to medullary loop of Henle, providing connectivity within segments of the same nephron, and between separate nephrons. The nerves organize glomeruli into discreet communities (in the same network of nerves). Adjacent glomerular communities are connected to intercommunal "mother glomeruli" by nerves, a pattern repeating throughout the cortex. These neuro-nephron networks are not developed in postnatal kidneys and are disrupted in diseased kidneys (diabetic or hydronephrosis). This structural organization likely poises the entire glomerular and juxtaglomerular FTUs to synchronize responses to perturbations in fluid homeostasis, utilizing mother glomeruli as network control centers.

A Soft-Fiber Bioelectronic Device with Axon-Like Architecture Enables Reliable Neural Recording In Vivo under Vigorous Activities

Implantable neural devices that record neurons in various states, including static states, light activities such as walking, and vigorous activities such as running, offer opportunities for understanding brain functions and dysfunctions. However, recording neurons under vigorous activities remains a long-standing challenge because it leads to intense brain deformation. Thus, three key requirements are needed simultaneously for neural devices, that is, low modulus, low specific interfacial impedance, and high electrical conductivity, to realize stable device/brain interfaces and high-quality transmission of neural signals. However, they always contradict each other in current material strategies. Here, a soft fiber neural device capable of stably tracking individual neurons in the deep brain of medium-sized animals under vigorous activity is reported. Inspired by the axon architecture, this fiber neural device is constructed with a conductive gel fiber possessing a network-in-liquid structure using conjugated polymers and liquid matrices and then insulated with soft fluorine rubber. This strategy reconciles the contradictions and simultaneously confers the fiber neural device with low modulus (300 kPa), low specific impedance (579 kΩ µm2), and high electrical conductivity (32 700 S m-1) - ≈1-3 times higher than hydrogels. Stable single-unit spike tracking in running cats, which promises new opportunities for neuroscience is demonstrated.

A SMARTR workflow for multi-ensemble atlas mapping and brain-wide network analysis

In the last decade, activity-dependent strategies for labelling multiple immediate early gene (IEG) ensembles in mice have generated unprecedented insight into the mechanisms of memory encoding, storage, and retrieval. However, few strategies exist for brain-wide mapping of multiple ensembles, including their overlapping population, and none incorporate capabilities for downstream network analysis. Here, we introduce a scalable workflow to analyze traditionally coronally-sectioned datasets produced by activity-dependent tagging systems. Intrinsic to this pipeline is simple multi-ensemble atlas registration and statistical testing in R (SMARTR), an R package which wraps mapping capabilities with functions for statistical analysis and network visualization. We demonstrate the versatility of SMARTR by mapping the ensembles underlying the acquisition and expression of learned helplessness (LH), a robust stress model. Applying network analysis, we find that exposure to inescapable shock (IS), compared to context training (CT), results in decreased centrality of regions engaged in spatial and contextual processing and higher influence of regions involved in somatosensory and affective processing. During LH expression, the substantia nigra emerges as a highly influential region which shows a functional reversal following IS, indicating a possible regulatory function of motor activity during helplessness. We also report that IS results in a robust decrease in reactivation activity across a number of cortical, hippocampal, and amygdalar regions, indicating suppression of ensemble reactivation may be a neurobiological signature of LH. These results highlight the emergent insights uniquely garnered by applying our analysis approach to multiple ensemble datasets and demonstrate the strength of our workflow as a hypothesis-generating toolkit.

Serine racemase deletion alters adolescent social behavior and whole-brain cFos activation

Background

Neurodevelopmental disorders (NDDs) can cause debilitating impairments in social cognition and aberrant functional connectivity in large-scale brain networks, leading to social isolation and diminished everyday functioning. To facilitate the treatment of social impairments, animal models of NDDs that link N- methyl-D-aspartate receptor (NMDAR) hypofunction to social deficits in adulthood have been used. However, understanding the etiology of social impairments in NDDs requires investigating social changes during sensitive windows during development.

Methods

We examine social behavior during adolescence using a translational mouse model of NMDAR hypofunction (SR-/-) caused by knocking out serine racemase (SR), the enzyme needed to make D-serine, a key NMDAR coagonist. Species-typical social interactions are maintained through brain-wide neural activation patterns; therefore, we employed whole-brain cFos activity mapping to examine network-level connectivity changes caused by SR deletion.

Results

In adolescent SR-/- mice, we observed disinhibited social behavior toward a novel conspecific and rapid social habituation toward familiar social partners. SR-/- mice also spent more time in the open arm of the elevated plus maze which classically points to an anxiolytic behavioral phenotype. These behavioral findings point to a generalized reduction in anxiety-like behavior in both social and non-social contexts in SR-/- mice; importantly, these findings were not associated with diminished working memory. Inter-regional patterns of cFos activation revealed greater connectivity and network density in SR-/- mice compared to controls.

Discussion

These results suggest that NMDAR hypofunction - a potential biomarker for NDDs - can lead to generalized behavioral disinhibition in adolescence, potentially arising from disrupted communication between and within salience and default mode networks.

Integrated platform for multiscale molecular imaging and phenotyping of the human brain

Understanding cellular architectures and their connectivity is essential for interrogating system function and dysfunction. However, we lack technologies for mapping the multiscale details of individual cells and their connectivity in the human organ-scale system. We developed a platform that simultaneously extracts spatial, molecular, morphological, and connectivity information of individual cells from the same human brain. The platform includes three core elements: a vibrating microtome for ultraprecision slicing of large-scale tissues without losing cellular connectivity (MEGAtome), a polymer hydrogel-based tissue processing technology for multiplexed multiscale imaging of human organ-scale tissues (mELAST), and a computational pipeline for reconstructing three-dimensional connectivity across multiple brain slabs (UNSLICE). We applied this platform for analyzing human Alzheimer's disease pathology at multiple scales and demonstrating scalable neural connectivity mapping in the human brain.

descSPIM: an affordable and easy-to-build light-sheet microscope optimized for tissue clearing techniques

Despite widespread adoption of tissue clearing techniques in recent years, poor access to suitable light-sheet fluorescence microscopes remains a major obstacle for biomedical end-users. Here, we present descSPIM (desktop-equipped SPIM for cleared specimens), a low-cost ($20,000-50,000), low-expertise (one-day installation by a non-expert), yet practical do-it-yourself light-sheet microscope as a solution for this bottleneck. Even the most fundamental configuration of descSPIM enables multi-color imaging of whole mouse brains and a cancer cell line-derived xenograft tumor mass for the visualization of neurocircuitry, assessment of drug distribution, and pathological examination by false-colored hematoxylin and eosin staining in a three-dimensional manner. Academically open-sourced ( https://github.com/dbsb-juntendo/descSPIM ), descSPIM allows routine three-dimensional imaging of cleared samples in minutes. Thus, the dissemination of descSPIM will accelerate biomedical discoveries driven by tissue clearing technologies.

Cosmic kidney disease: an integrated pan-omic, physiological and morphological study into spaceflight-induced renal dysfunction

Missions into Deep Space are planned this decade. Yet the health consequences of exposure to microgravity and galactic cosmic radiation (GCR) over years-long missions on indispensable visceral organs such as the kidney are largely unexplored. We performed biomolecular (epigenomic, transcriptomic, proteomic, epiproteomic, metabolomic, metagenomic), clinical chemistry (electrolytes, endocrinology, biochemistry) and morphometry (histology, 3D imaging, miRNA-ISH, tissue weights) analyses using samples and datasets available from 11 spaceflight-exposed mouse and 5 human, 1 simulated microgravity rat and 4 simulated GCR-exposed mouse missions. We found that spaceflight induces: 1) renal transporter dephosphorylation which may indicate astronauts' increased risk of nephrolithiasis is in part a primary renal phenomenon rather than solely a secondary consequence of bone loss; 2) remodelling of the nephron that results in expansion of distal convoluted tubule size but loss of overall tubule density; 3) renal damage and dysfunction when exposed to a Mars roundtrip dose-equivalent of simulated GCR.

ARX regulates cortical interneuron differentiation and migration

Mutations in aristaless-related homeobox ( ARX ) are associated with neurodevelopmental disorders including developmental epilepsies, intellectual disabilities, and autism spectrum disorders, with or without brain malformations. Aspects of these disorders have been linked to abnormal cortical interneuron (cIN) development and function. To further understand ARX's role in cIN development, multiple Arx mutant mouse lines were interrogated. We found that ARX is critical for controlling cIN numbers and distribution, especially, in the developing marginal zone (MZ). Single cell transcriptomics and ChIP-seq, combined with functional studies, revealed ARX directly or indirectly regulates genes involved in proliferation and the cell cycle (e.g., Bub3 , Cspr3 ), fate specification (e.g., Nkx2.1 , Maf , Mef2c ), and migration (e.g., Nkx2.1 , Lmo1 , Cxcr4 , Nrg1 , ErbB4 ). Our data suggest that the MZ stream defects primarily result from disordered cell-cell communication. Together our findings provide new insights into the mechanisms underlying cIN development and migration and how they are disrupted in several disorders.

Glutamatergic supramammillary nucleus neurons respond to threatening stressors and promote active coping

Threat-response neural circuits are conserved across species and play roles in normal behavior and psychiatric diseases. Maladaptive changes in these neural circuits contribute to stress, mood, and anxiety disorders. Active coping in response to stressors is a psychosocial factor associated with resilience against stress-induced mood and anxiety disorders. The neural circuitry underlying active coping is poorly understood, but the functioning of these circuits could be key for overcoming anxiety and related disorders. The supramammillary nucleus (SuM) has been suggested to be engaged by threat. SuM has many projections and a poorly understood diversity of neural populations. In studies using mice, we identified a unique population of glutamatergic SuM neurons (SuMVGLUT2+::POA) based on projection to the preoptic area of the hypothalamus (POA) and found SuMVGLUT2+::POA neurons have extensive arborizations. SuMVGLUT2+::POA neurons project to brain areas that mediate features of the stress and threat responses including the paraventricular nucleus thalamus (PVT), periaqueductal gray (PAG), and habenula (Hb). Thus, SuMVGLUT2+::POA neurons are positioned as a hub, connecting to areas implicated in regulating stress responses. Here we report SuMVGLUT2+::POA neurons are recruited by diverse threatening stressors, and recruitment correlated with active coping behaviors. We found that selective photoactivation of the SuMVGLUT2+::POA population drove aversion but not anxiety like behaviors. Activation of SuMVGLUT2+::POA neurons in the absence of acute stressors evoked active coping like behaviors and drove instrumental behavior. Also, activation of SuMVGLUT2+::POA neurons was sufficient to convert passive coping strategies to active behaviors during acute stress. In contrast, we found activation of GABAergic (VGAT+) SuM neurons (SuMVGAT+) neurons did not alter drive aversion or active coping, but termination of photostimulation was followed by increased mobility in the forced swim test. These findings establish a new node in stress response circuitry that has projections to many brain areas and evokes flexible active coping behaviors.

TSWIFT, a novel method for iterative staining of embedded and mounted human brain sections

Comprehensive characterization of protein networks in mounted brain tissue represents a major challenge in brain and neurodegenerative disease research. In this study, we develop a simple staining method, called TSWIFT, to iteratively stain pre-mounted formalin fixed, paraffin embedded (FFPE) brain sections, thus enabling high-dimensional sample phenotyping. We show that TSWIFT conserves tissue architecture and allows for relabeling a single mounted FFPE sample more than 10 times, even after prolonged storage at 4 °C. Our results establish TSWIFT as an efficient method to obtain integrated high-dimensional knowledge of cellular proteomes by analyzing mounted FFPE human brain tissue.

Revealing intact neuronal circuitry in centimeter-sized formalin-fixed paraffin-embedded brain

Tissue-clearing and labeling techniques have revolutionized brain-wide imaging and analysis, yet their application to clinical formalin-fixed paraffin-embedded (FFPE) blocks remains challenging. We introduce HIF-Clear, a novel method for efficiently clearing and labeling centimeter-thick FFPE specimens using elevated temperature and concentrated detergents. HIF-Clear with multi-round immunolabeling reveals neuron circuitry regulating multiple neurotransmitter systems in a whole FFPE mouse brain and is able to be used as the evaluation of disease treatment efficiency. HIF-Clear also supports expansion microscopy and can be performed on a non-sectioned 15-year-old FFPE specimen, as well as a 3-month formalin-fixed mouse brain. Thus, HIF-Clear represents a feasible approach for researching archived FFPE specimens for future neuroscientific and 3D neuropathological analyses.

Regulatory T cell-derived enkephalin imparts pregnancy-induced analgesia

T cells have emerged as sex-dependent orchestrators of pain chronification but the sexually dimorphic mechanisms by which T cells control pain sensitivity is not resolved. Here, we demonstrate an influence of regulatory T cells (Tregs) on pain processing that is distinct from their canonical functions of immune regulation and tissue repair. Specifically, meningeal Tregs (mTregs) express the endogenous opioid, enkephalin, and mTreg-derived enkephalin exerts an antinociceptive action through a presynaptic opioid receptor signaling mechanism that is dispensable for immunosuppression. mTregs are both necessary and sufficient for suppressing mechanical pain sensitivity in female but not male mice. Notably, the mTreg modulation of pain thresholds depends on sex-hormones and expansion of enkephalinergic mTregs during gestation imparts a remarkable pregnancy-induced analgesia in a pre-existing, chronic, unremitting neuropathic pain model. These results uncover a fundamental sex-specific, pregnancy-pronounced, and immunologically-derived endogenous opioid circuit for nociceptive regulation with critical implications for pain biology and maternal health.

Applications of Tissue Clearing in Central and Peripheral Nerves

The techniques of tissue clearing have been proposed and applied in anatomical and biomedical research since the 19th century. As we all know, the original study of the nervous system relied on serial ultrathin sections and stereoscopic techniques. The 3D visualization of the nervous system was established by software splicing and reconstruction. With the development of science and technology, microscope equipment had constantly been upgraded. Despite the great progress that has been made in this field, the workload is too complex, and it needs high technical requirements. Abundant mistakes due to manual sections were inescapable and structural integrity remained questionable. According to the classification of tissue transparency methods, we introduced the latest application of transparency methods in central and peripheral nerve research from optical imaging, molecular markers and data analysis. This review summarizes the application of transparent technology in neural pathways. We hope to provide some inspiration for the continuous optimization of tissue clearing methods.

Identification of a myofibroblast differentiation program during neonatal lung development

Alveologenesis is the final stage of lung development in which the internal surface area of the lung is increased to facilitate efficient gas exchange in the mature organism. The first phase of alveologenesis involves the formation of septal ridges (secondary septae) and the second phase involves thinning of the alveolar septa. Within secondary septa, mesenchymal cells include a transient population of alveolar myofibroblasts (MyoFBs) and a stable but poorly described population of lipid-rich cells that have been referred to as lipofibroblasts or matrix fibroblasts (MatFBs). Using a unique Fgf18CreER lineage trace mouse line, cell sorting, single-cell RNA sequencing and primary cell culture, we have identified multiple subtypes of mesenchymal cells in the neonatal lung, including an immature progenitor cell that gives rise to mature MyoFB. We also show that the endogenous and targeted ROSA26 locus serves as a sensitive reporter for MyoFB maturation. These studies identify a MyoFB differentiation program that is distinct from other mesenchymal cell types and increases the known repertoire of mesenchymal cell types in the neonatal lung.

Potentiation of the M 1 muscarinic acetylcholine receptor normalizes neuronal activation patterns and improves apnea severity in Mecp2+/- mice

Rett syndrome (RTT) is a neurodevelopmental disorder that is caused by loss-of-function mutations in the methyl-CpG binding protein 2 ( MeCP2 ) gene. RTT patients experience a myriad of debilitating symptoms, which include respiratory phenotypes that are often associated with lethality. Our previous work established that expression of the M 1 muscarinic acetylcholine receptor (mAchR) is decreased in RTT autopsy samples, and that potentiation of the M 1 receptor improves apneas in a mouse model of RTT; however, the population of neurons driving this rescue is unclear. Loss of Mecp2 correlates with excessive neuronal activity in cardiorespiratory nuclei. Since M 1 is found on cholinergic interneurons, we hypothesized that M 1 -potentiating compounds decrease apnea frequency by tempering brainstem hyperactivity. To test this, Mecp2 +/- and Mecp2 +/+ mice were screened for apneas before and after administration of the M 1 positive allosteric modulator (PAM) VU0453595 (VU595). Brains from the same mice were then imaged for c-Fos, ChAT, and Syto16 using whole-brain light-sheet microscopy to establish genotype and drug-dependent activation patterns that could be correlated with VU595's efficacy on apneas. The vehicle-treated Mecp2 +/- brain exhibited broad hyperactivity when coupled with the phenotypic prescreen, which was significantly decreased by administration of VU595, particularly in regions known to modulate the activity of respiratory nuclei (i.e. hippocampus and striatum). Further, the extent of apnea rescue in each mouse showed a significant positive correlation with c-Fos expression in non-cholinergic neurons in the striatum, thalamus, dentate gyrus, and within the cholinergic neurons of the brainstem. These results indicate that Mecp2 +/- mice are prone to hyperactivity in brain regions that regulate respiration, which can be normalized through M 1 potentiation.

Tissue clearing method in visualization of cancer progression and metastasis

Since various imaging modalities have been developed, cancer metastasis can be detected from an early stage. However, limitations still exist, especially in terms of spatial resolution. Tissue-clearing technology has emerged as a new imaging modality in cancer research, which has been developed and utilized for a long time mainly in neuroscience field. This method enables us to detect cancer metastatic foci with single-cell resolution at whole mouse body/organ level. On top of that, 3D images of cancer metastasis of whole mouse organs make it easy to understand their characteristics. Recently, further applications of tissue clearing methods were reported in combination with reporter systems, labeling, and machine learning. In this review, we would like to provide an overview of this technique and current applications in cancer research and discuss their potentials and limitations.

An end-to-end workflow for nondestructive 3D pathology

Recent advances in 3D pathology offer the ability to image orders of magnitude more tissue than conventional pathology methods while also providing a volumetric context that is not achievable with 2D tissue sections, and all without requiring destructive tissue sectioning. Generating high-quality 3D pathology datasets on a consistent basis, however, is not trivial and requires careful attention to a series of details during tissue preparation, imaging and initial data processing, as well as iterative optimization of the entire process. Here, we provide an end-to-end procedure covering all aspects of a 3D pathology workflow (using light-sheet microscopy as an illustrative imaging platform) with sufficient detail to perform well-controlled preclinical and clinical studies. Although 3D pathology is compatible with diverse staining protocols and computationally generated color palettes for visual analysis, this protocol focuses on the use of a fluorescent analog of hematoxylin and eosin, which remains the most common stain used for gold-standard pathological reports. We present our guidelines for a broad range of end users (e.g., biologists, clinical researchers and engineers) in a simple format. The end-to-end workflow requires 3-6 d to complete, bearing in mind that data analysis may take longer.

Whole-body cellular mapping in mouse using standard IgG antibodies

Whole-body imaging techniques play a vital role in exploring the interplay of physiological systems in maintaining health and driving disease. We introduce wildDISCO, a new approach for whole-body immunolabeling, optical clearing and imaging in mice, circumventing the need for transgenic reporter animals or nanobody labeling and so overcoming existing technical limitations. We identified heptakis(2,6-di-O-methyl)-β-cyclodextrin as a potent enhancer of cholesterol extraction and membrane permeabilization, enabling deep, homogeneous penetration of standard antibodies without aggregation. WildDISCO facilitates imaging of peripheral nervous systems, lymphatic vessels and immune cells in whole mice at cellular resolution by labeling diverse endogenous proteins. Additionally, we examined rare proliferating cells and the effects of biological perturbations, as demonstrated in germ-free mice. We applied wildDISCO to map tertiary lymphoid structures in the context of breast cancer, considering both primary tumor and metastases throughout the mouse body. An atlas of high-resolution images showcasing mouse nervous, lymphatic and vascular systems is accessible at http://discotechnologies.org/wildDISCO/atlas/index.php .

An Open Resource: MR and light sheet microscopy stereotaxic atlas of the mouse brain

We have combined MR histology and light sheet microscopy (LSM) of five postmortem C57BL/6J mouse brains in a stereotaxic space based on micro-CT yielding a multimodal 3D atlas with the highest spatial and contrast resolution yet reported. Brains were imaged in situ with multi gradient echo (mGRE) and diffusion tensor imaging (DTI) at 15 μm resolution (∼ 2.4 million times that of clinical MRI). Scalar images derived from the average DTI and mGRE provide unprecedented contrast in 14 complementary 3D volumes, each highlighting distinct histologic features. The same tissues scanned with LSM and registered into the stereotaxic space provide 17 different molecular cell type stains. The common coordinate framework labels (CCFv3) complete the multimodal atlas. The atlas has been used to correct distortions in the Allen Brain Atlas and harmonize it with Franklin Paxinos. It provides a unique resource for stereotaxic labeling of mouse brain images from many sources.

The functional and anatomical characterization of three spinal output pathways of the anterolateral tract

The nature of spinal output pathways that convey nociceptive information to the brain has been the subject of controversy. Here, we provide anatomical, molecular, and functional characterizations of two distinct anterolateral pathways: one, ascending in the lateral spinal cord, triggers nociceptive behaviors, and the other one, ascending in the ventral spinal cord, when inhibited, leads to sensorimotor deficits. Moreover, the lateral pathway consists of at least two subtypes. The first is a contralateral pathway that extends to the periaqueductal gray (PAG) and thalamus; the second is a bilateral pathway that projects to the bilateral parabrachial nucleus (PBN). Finally, we present evidence showing that activation of the contralateral pathway is sufficient for defensive behaviors such as running and freezing, whereas the bilateral pathway is sufficient for attending behaviors such as licking and guarding. This work offers insight into the complex organizational logic of the anterolateral system in the mouse.

β-amyloid accumulation enhances microtubule associated protein tau pathology in an APPNL-G-F/MAPTP301S mouse model of Alzheimer's disease

Introduction

The study of the pathophysiology study of Alzheimer's disease (AD) has been hampered by lack animal models that recapitulate the major AD pathologies, including extracellular -amyloid (A) deposition, intracellular aggregation of microtubule associated protein tau (MAPT), inflammation and neurodegeneration.

Methods

The humanized APPNL-G-F knock-in mouse line was crossed to the PS19 MAPTP301S, over-expression mouse line to create the dual APPNL-G-F/PS19 MAPTP301S line. The resulting pathologies were characterized by immunochemical methods and PCR.

Results

We now report on a double transgenic APPNL-G-F/PS19 MAPTP301S mouse that at 6 months of age exhibits robust A plaque accumulation, intense MAPT pathology, strong inflammation and extensive neurodegeneration. The presence of A pathology potentiated the other major pathologies, including MAPT pathology, inflammation and neurodegeneration. MAPT pathology neither changed levels of amyloid precursor protein nor potentiated A accumulation. Interestingly, study of immunofluorescence in cleared brains indicates that microglial inflammation was generally stronger in the hippocampus, dentate gyrus and entorhinal cortex, which are regions with predominant MAPT pathology. The APPNL-G-F/MAPTP301S mouse model also showed strong accumulation of N6-methyladenosine (m6A), which was recently shown to be elevated in the AD brain. m6A primarily accumulated in neuronal soma, but also co-localized with a subset of astrocytes and microglia. The accumulation of m6A corresponded with increases in METTL3 and decreases in ALKBH5, which are enzymes that add or remove m6A from mRNA, respectively.

Discussion

Our understanding of the pathophysiology of Alzheimer's disease (AD) has been hampered by lack animal models that recapitulate the major AD pathologies, including extracellular -amyloid (A) deposition, intracellular aggregation of microtubule associated protein tau (MAPT), inflammation and neurodegeneration. The APPNL-G-F/MAPTP301S mouse recapitulates many features of AD pathology beginning at 6 months of aging, and thus represents a useful new mouse model for the field.

Phosphorylation of pyruvate dehydrogenase inversely associates with neuronal activity

For decades, the expression of immediate early genes (IEGs) such as FOS has been the most widely used molecular marker representing neuronal activation. However, to date, there is no equivalent surrogate available for the decrease of neuronal activity. Here, we developed an optogenetic-based biochemical screen in which population neural activities can be controlled by light with single action potential precision, followed by unbiased phosphoproteomic profiling. We identified that the phosphorylation of pyruvate dehydrogenase (pPDH) inversely correlated with the intensity of action potential firing in primary neurons. In in vivo mouse models, monoclonal antibody-based pPDH immunostaining detected activity decreases across the brain, which were induced by a wide range of factors including general anesthesia, chemogenetic inhibition, sensory experiences, and natural behaviors. Thus, as an inverse activity marker (IAM) in vivo, pPDH can be used together with IEGs or other cell-type markers to profile and identify bi-directional neural dynamics induced by experiences or behaviors.

A topographical atlas of α-synuclein dosage and cell type-specific expression in adult mouse brain and peripheral organs

Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide and presents pathologically with Lewy pathology and dopaminergic neurodegeneration. Lewy pathology contains aggregated α-synuclein (αSyn), a protein encoded by the SNCA gene which is also mutated or duplicated in a subset of familial PD cases. Due to its predominant presynaptic localization, immunostaining for the protein results in a diffuse reactivity pattern, providing little insight into the types of cells expressing αSyn. As a result, insight into αSyn expression-driven cellular vulnerability has been difficult to ascertain. Using a combination of knock-in mice that target αSyn to the nucleus (SncaNLS) and in situ hybridization of Snca in wild-type mice, we systematically mapped the topography and cell types expressing αSyn in the mouse brain, spinal cord, retina, and gut. We find a high degree of correlation between αSyn protein and RNA levels and further identify cell types with low and high αSyn content. We also find high αSyn expression in neurons, particularly those involved in PD, and to a lower extent in non-neuronal cell types, notably those of oligodendrocyte lineage, which are relevant to multiple system atrophy pathogenesis. Surprisingly, we also found that αSyn is relatively absent from select neuron types, e.g., ChAT-positive motor neurons, whereas enteric neurons universally express some degree of αSyn. Together, this integrated atlas provides insight into the cellular topography of αSyn, and provides a quantitative map to test hypotheses about the role of αSyn in network vulnerability, and thus serves investigations into PD pathogenesis and other α-synucleinopathies.

Expansion and Light-Sheet Microscopy for Nanoscale 3D Imaging

Expansion Microscopy (ExM) and Light-Sheet Fluorescence Microscopy (LSFM) are forefront imaging techniques that enable high-resolution visualization of biological specimens. ExM enhances nanoscale investigation using conventional fluorescence microscopes, while LSFM offers rapid, minimally invasive imaging over large volumes. This review explores the joint advancements of ExM and LSFM, focusing on the excellent performance of the integrated modality obtained from the combination of the two, which is refer to as ExLSFM. In doing so, the chemical processes required for ExM, the tailored optical setup of LSFM for examining expanded samples, and the adjustments in sample preparation for accurate data collection are emphasized. It is delve into various specimen types studied using this integrated method and assess its potential for future applications. The goal of this literature review is to enrich the comprehension of ExM and LSFM, encouraging their wider use and ongoing development, looking forward to the upcoming challenges, and anticipating innovations in these imaging techniques.

In-vivo integration of soft neural probes through high-resolution printing of liquid electronics on the cranium

Current soft neural probes are still operated by bulky, rigid electronics mounted to a body, which deteriorate the integrity of the device to biological systems and restrict the free behavior of a subject. We report a soft, conformable neural interface system that can monitor the single-unit activities of neurons with long-term stability. The system implements soft neural probes in the brain, and their subsidiary electronics which are directly printed on the cranial surface. The high-resolution printing of liquid metals forms soft neural probes with a cellular-scale diameter and adaptable lengths. Also, the printing of liquid metal-based circuits and interconnections along the curvature of the cranium enables the conformal integration of electronics to the body, and the cranial circuit delivers neural signals to a smartphone wirelessly. In the in-vivo studies using mice, the system demonstrates long-term recording (33 weeks) of neural activities in arbitrary brain regions. In T-maze behavioral tests, the system shows the behavior-induced activation of neurons in multiple brain regions.

MarShie: a clearing protocol for 3D analysis of single cells throughout the bone marrow at subcellular resolution

Analyzing immune cell interactions in the bone marrow is vital for understanding hematopoiesis and bone homeostasis. Three-dimensional analysis of the complete, intact bone marrow within the cortex of whole long bones remains a challenge, especially at subcellular resolution. We present a method that stabilizes the marrow and provides subcellular resolution of fluorescent signals throughout the murine femur, enabling identification and spatial characterization of hematopoietic and stromal cell subsets. By combining a pre-processing algorithm for stripe artifact removal with a machine-learning approach, we demonstrate reliable cell segmentation down to the deepest bone marrow regions. This reveals age-related changes in the marrow. It highlights the interaction between CX3CR1+ cells and the vascular system in homeostasis, in contrast to other myeloid cell types, and reveals their spatial characteristics after injury. The broad applicability of this method will contribute to a better understanding of bone marrow biology.

Improved immunostaining of nanostructures and cells in human brain specimens through expansion-mediated protein decrowding

Proteins are densely packed in cells and tissues, where they form complex nanostructures. Expansion microscopy (ExM) variants have been used to separate proteins from each other in preserved biospecimens, improving antibody access to epitopes. Here, we present an ExM variant, decrowding expansion pathology (dExPath), that can expand proteins away from each other in human brain pathology specimens, including formalin-fixed paraffin-embedded (FFPE) clinical specimens. Immunostaining of dExPath-expanded specimens reveals, with nanoscale precision, previously unobserved cellular structures, as well as more continuous patterns of staining. This enhanced molecular staining results in observation of previously invisible disease marker-positive cell populations in human glioma specimens, with potential implications for tumor aggressiveness. dExPath results in improved fluorescence signals even as it eliminates lipofuscin-associated autofluorescence. Thus, this form of expansion-mediated protein decrowding may, through improved epitope access for antibodies, render immunohistochemistry more powerful in clinical science and, perhaps, diagnosis.

Hippocampal Engrams Generate Variable Behavioral Responses and Brain-Wide Network States

Freezing is a defensive behavior commonly examined during hippocampal-mediated fear engram reactivation. How these cellular populations engage the brain and modulate freezing across varying environmental demands is unclear. To address this, we optogenetically reactivated a fear engram in the dentate gyrus subregion of the hippocampus across three distinct contexts in male mice. We found that there were differential amounts of light-induced freezing depending on the size of the context in which reactivation occurred: mice demonstrated robust light-induced freezing in the most spatially restricted of the three contexts but not in the largest. We then utilized graph theoretical analyses to identify brain-wide alterations in cFos expression during engram reactivation across the smallest and largest contexts. Our manipulations induced positive interregional cFos correlations that were not observed in control conditions. Additionally, regions spanning putative "fear" and "defense" systems were recruited as hub regions in engram reactivation networks. Lastly, we compared the network generated from engram reactivation in the small context with a natural fear memory retrieval network. Here, we found shared characteristics such as modular composition and hub regions. By identifying and manipulating the circuits supporting memory function, as well as their corresponding brain-wide activity patterns, it is thereby possible to resolve systems-level biological mechanisms mediating memory's capacity to modulate behavioral states.

Memory Storage in Distributed Engram Cell Ensembles

One of the most fascinating aspects of the brain is its ability to acquire new information from experience and retain it over time as memory. The search for physical correlates of memory, the memory engram, has been a longstanding priority in modern neurobiology. Advanced genetic approaches have led to the localization of engram cells in a few brain regions, including the hippocampus and cortex. Additionally, engram cells exhibit learning-induced, persistent modifications and have at least two states, active and silent. However, it has been hypothesized that engrams for a specific memory are distributed among multiple brain regions that are functionally connected, referred to as a unified engram complex. Recent tissue-clearing techniques have permitted high-throughput analyses of intact brain samples, which have been used to obtain a map of the engram complex for a contextual fear memory. Careful examination of these engram complex maps has revealed a potentially underappreciated contribution of subcortical regions, specifically thalamic nuclei, to memory function. These more holistic studies support the unified engram complex hypothesis for memory storage and have important implications for understanding dysfunctional engrams in the context of human disease.

Label-Retention Expansion Microscopy (LR-ExM) for Enhanced Fluorescent Signals using Trifunctional Probes

Expansion microscopy (ExM) is a super-resolution imaging technique that bypasses the diffraction limit of conventional optical microscopy (∼250 nm) by enlarging samples with a swellable hydrogel. Combined with various light microscopes, ExM enables an effective resolution ranging from 5 to 70 nm. ExM has now been successfully applied to cell, tissue, and whole-organism samples, providing biologists with a low-cost strategy to visualize samples at the molecular level. However, fluorescence signal loss easily happens for beginners and with early versions of ExM protocols. Here, we describe a protocol called label-retention expansion microscopy (LR-ExM), which can preserve and enhance the signal of ExM imaging via a series of trifunctional probes. These trifunctional probes are antibody-based and easy to prepare, and thus suit the needs of most laboratories. © 2024 Wiley Periodicals LLC. Basic Protocol: LR-ExM using trifunctional probes for enhanced fluorescent signals.

Identification of a myofibroblast differentiation program during neonatal lung development

Alveologenesis is the final stage of lung development in which the internal surface area of the lung is increased to facilitate efficient gas exchange in the mature organism. The first phase of alveologenesis involves the formation of septal ridges (secondary septae) and the second phase involves thinning of the alveolar septa. Within secondary septa, mesenchymal cells include a transient population of alveolar myofibroblasts (MyoFB) and a stable but poorly described population of lipid rich cells that have been referred to as lipofibroblasts or matrix fibroblasts (MatFB). Using a unique Fgf18CreER lineage trace mouse line, cell sorting, single cell RNA sequencing, and primary cell culture, we have identified multiple subtypes of mesenchymal cells in the neonatal lung, including an immature progenitor cell that gives rise to mature MyoFB. We also show that the endogenous and targeted ROSA26 locus serves as a sensitive reporter for MyoFB maturation. These studies identify a myofibroblast differentiation program that is distinct form other mesenchymal cells types and increases the known repertoire of mesenchymal cell types in the neonatal lung.

An arginine-rich nuclear localization signal (ArgiNLS) strategy for streamlined image segmentation of single-cells

High-throughput volumetric fluorescent microscopy pipelines can spatially integrate whole-brain structure and function at the foundational level of single-cells. However, conventional fluorescent protein (FP) modifications used to discriminate single-cells possess limited efficacy or are detrimental to cellular health. Here, we introduce a synthetic and non-deleterious nuclear localization signal (NLS) tag strategy, called 'Arginine-rich NLS' (ArgiNLS), that optimizes genetic labeling and downstream image segmentation of single-cells by restricting FP localization near-exclusively in the nucleus through a poly-arginine mechanism. A single N-terminal ArgiNLS tag provides modular nuclear restriction consistently across spectrally separate FP variants. ArgiNLS performance in vivo displays functional conservation across major cortical cell classes, and in response to both local and systemic brain wide AAV administration. Crucially, the high signal-to-noise ratio afforded by ArgiNLS enhances ML-automated segmentation of single-cells due to rapid classifier training and enrichment of labeled cell detection within 2D brain sections or 3D volumetric whole-brain image datasets, derived from both staining-amplified and native signal. This genetic strategy provides a simple and flexible basis for precise image segmentation of genetically labeled single-cells at scale and paired with behavioral procedures.

The Development of Human Ex Vivo Models of Inflammatory Skin Conditions

Traditional research in inflammatory dermatoses has relied on animal models and reconstructed human epidermis to study these conditions. However, these models are limited in replicating the complexity of real human skin and reproducing the intricate pathological changes in skin barrier components and lipid profiles. To address this gap, we developed experimental models that mimic various human inflammatory skin phenotypes. Human ex vivo skins were stimulated with various triggers, creating models for inflammation-induced angiogenesis, irritation response, and chronic T-cell activation. We assessed the alterations in skin morphology, cellular infiltrates, cytokine production, and epidermal lipidomic profiles. In the pro-angiogenesis model, we observed increased mast cell degranulation and elevated levels of angiogenic growth factors. Both the irritant and chronic inflammation models exhibited severe epidermal disruption, along with macrophage infiltration, leukocyte exocytosis, and heightened cytokine levels. Lipidomic analysis revealed minor changes in the pro-angiogenesis model, whereas the chronic inflammation and irritant models exhibited significant decreases in barrier essential ceramide subclasses and a shift toward shorter acyl chain lengths ( Collapse

Key Words

• ex vivo model
• skin barrier
• skin inflammation

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MESH Headings

• Animals
• Humans
• Irritants/pharmacology
• Skin/metabolism
• Epidermis/metabolism
• Skin Diseases/metabolism
• Inflammation/metabolism
• Cytokines/metabolism

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Grants Collapse

Affiliation(s)

Eddy Hsi Chun Wang L’Oreal Research and Innovation, Clark, NJ 07066, USA
Rebecca Barresi-Thornton L’Oreal Research and Innovation, Clark, NJ 07066, USA
Li-Chi Chen Harvard Medical School, Boston & Beth Israel Lahey Health, Burlington, MA 01805, USA
Maryanne Makredes Senna Harvard Medical School, Boston & Beth Israel Lahey Health, Burlington, MA 01805, USA
I-Chien Liao L’Oreal Research and Innovation, Clark, NJ 07066, USA
Ying Chen L’Oreal Research and Innovation, Clark, NJ 07066, USA
Qian Zheng L’Oreal Research and Innovation, Clark, NJ 07066, USA
Charbel Bouez L’Oreal Research and Innovation, Clark, NJ 07066, USA

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Whole-brain Optical Imaging: A Powerful Tool for Precise Brain Mapping at the Mesoscopic Level

The mammalian brain is a highly complex network that consists of millions to billions of densely-interconnected neurons. Precise dissection of neural circuits at the mesoscopic level can provide important structural information for understanding the brain. Optical approaches can achieve submicron lateral resolution and achieve "optical sectioning" by a variety of means, which has the natural advantage of allowing the observation of neural circuits at the mesoscopic level. Automated whole-brain optical imaging methods based on tissue clearing or histological sectioning surpass the limitation of optical imaging depth in biological tissues and can provide delicate structural information in a large volume of tissues. Combined with various fluorescent labeling techniques, whole-brain optical imaging methods have shown great potential in the brain-wide quantitative profiling of cells, circuits, and blood vessels. In this review, we summarize the principles and implementations of various whole-brain optical imaging methods and provide some concepts regarding their future development.

epDevAtlas: Mapping GABAergic cells and microglia in postnatal mouse brains

During development, brain regions follow encoded growth trajectories. Compared to classical brain growth charts, high-definition growth charts could quantify regional volumetric growth and constituent cell types, improving our understanding of typical and pathological brain development. Here, we create high-resolution 3D atlases of the early postnatal mouse brain, using Allen CCFv3 anatomical labels, at postnatal days (P) 4, 6, 8, 10, 12, and 14, and determine the volumetric growth of different brain regions. We utilize 11 different cell type-specific transgenic animals to validate and refine anatomical labels. Moreover, we reveal region-specific density changes in γ-aminobutyric acid-producing (GABAergic), cortical layer-specific cell types, and microglia as key players in shaping early postnatal brain development. We find contrasting changes in GABAergic neuronal densities between cortical and striatal areas, stabilizing at P12. Moreover, somatostatin-expressing cortical interneurons undergo regionally distinct density reductions, while vasoactive intestinal peptide-expressing interneurons show no significant changes. Remarkably, microglia transition from high density in white matter tracks to gray matter at P10, and show selective density increases in sensory processing areas that correlate with the emergence of individual sensory modalities. Lastly, we create an open-access web-visualization ( https://kimlab.io/brain-map/epDevAtlas ) for cell-type growth charts and developmental atlases for all postnatal time points.

Enablers and challenges of spatial omics, a melting pot of technologies

Spatial omics has emerged as a rapidly growing and fruitful field with hundreds of publications presenting novel methods for obtaining spatially resolved information for any omics data type on spatial scales ranging from subcellular to organismal. From a technology development perspective, spatial omics is a highly interdisciplinary field that integrates imaging and omics, spatial and molecular analyses, sequencing and mass spectrometry, and image analysis and bioinformatics. The emergence of this field has not only opened a window into spatial biology, but also created multiple novel opportunities, questions, and challenges for method developers. Here, we provide the perspective of technology developers on what makes the spatial omics field unique. After providing a brief overview of the state of the art, we discuss technological enablers and challenges and present our vision about the future applications and impact of this melting pot.

Loss of TREM2 exacerbates parenchymal amyloid pathology but diminishes CAA in Tg-SwDI mice

Alzheimer's disease (AD) is a progressive neurodegenerative disease, and it is the most common cause of dementia worldwide. Recent genome-wide association studies (GWAS) identified TREM2 (triggering receptor expressed on myeloid cells 2) as one of the major risk factors for AD. TREM2 is a surface receptor expressed on microglia and largely mediates microglial functions and immune homeostasis in the brain. The functions of TREM2 in AD pathogenesis, including in the formation of the key pathology parenchymal amyloid-β (Aβ) plaques, have been investigated by introducing Trem2 deficiency in AD mouse models. However, the role of TREM2 in cerebrovascular amyloidosis, in particular cerebral amyloid angiopathy (CAA) remains unexplored. CAA features Aβ deposition along the cerebral vessels, signifying an intersection between AD and vascular dysfunction. Using a well-characterized CAA-prone, transgenic mouse model of AD, Tg-SwDI (SwDI), we found that loss of TREM2 led to a marked increase in overall Aβ load in the brain, but a dramatic decrease in CAA in microvessel-rich regions, along with reduced microglial association with CAA. Transcriptomic analysis revealed that in the absence of Trem2 , microglia were activated but trapped in transition to the fully reactive state. Like microglia, perivascular macrophages were activated with upregulation of cell junction related pathways in Trem2 -deficient SwDI mice. In addition, vascular mural cells and astrocytes exhibited distinct responses to Trem2 deficiency, contributing to the pathological changes in the brain of Trem2 -null SwDI mice. Our study provides the first evidence that TREM2 differentially modulates parenchymal and vascular Aβ pathologies, which may have significant implications for both TREM2- and Aβ-targeting therapies for AD.

In Situ Forming of Nitric Oxide and Electric Stimulus for Nerve Therapy by Wireless Chargeable Gold Yarn-Dynamos

Endogenous signals, namely nitric oxide (NO) and electrons, play a crucial role in regulating cell fate as well as the vascular and neuronal systems. Unfortunately, utilizing NO and electrical stimulation in clinical settings can be challenging due to NO's short half-life and the invasive electrodes required for electrical stimulation. Additionally, there is a lack of tools to spatiotemporally control gas release and electrical stimulation. To address these issues, an "electromagnetic messenger" approach that employs on-demand high-frequency magnetic field (HFMF) to trigger NO release and electrical stimulation for restoring brain function in cases of traumatic brain injury is introduced. The system comprises a NO donor (poly(S-nitrosoglutathione), pGSNO)-conjugated on a gold yarn-dynamos (GY) and embedded in an implantable silk in a microneedle. When subjected to HFMF, conductive GY induces eddy currents that stimulate the release of NO from pGSNO. This process significantly enhances neural stem cell (NSC) synapses' differentiation and growth. The combined strategy of using NO and electrical stimulation to inhibit inflammation, angiogenesis, and neuronal interrogation in traumatic brain injury is demonstrated in vivo.

Heralding a new era of oxytocinergic research: New tools, new problems?

According to classic neuroendocrinology, hypothalamic oxytocin cells can be categorized into parvo- and magnocellular neurons. However, research in the last decade provided ample evidence that this black-and-white model of oxytocin neurons is most likely oversimplified. Novel genetic, functional and morphological studies indicate that oxytocin neurons might be organized in functional modules and suggest the existence of five or more distinct oxytocinergic subpopulations. However, many of these novel, automated high-throughput techniques might be inherently biased and interpretation of acquired data needs to be approached with caution to enable drawing sound and reliable conclusions. In addition, the recent finding that astrocytes in various brain regions express functional oxytocin receptors represents a paradigm shift and challenges the view that oxytocin primarily acts as a direct peptidergic neurotransmitter. This review highlights the latest technical advances in oxytocinergic research, puts recent studies on the oxytocin system into context and formulates various provocative ideas based on novel findings that challenges various prevailing hypotheses and dogmas about oxytocinergic modulation.

Organization of orbitofrontal-auditory pathways in the Mongolian gerbil

Sound perception is highly malleable, rapidly adjusting to the acoustic environment and behavioral demands. This flexibility is the result of ongoing changes in auditory cortical activity driven by fluctuations in attention, arousal, or prior expectations. Recent work suggests that the orbitofrontal cortex (OFC) may mediate some of these rapid changes, but the anatomical connections between the OFC and the auditory system are not well characterized. Here, we used virally mediated fluorescent tracers to map the projection from OFC to the auditory midbrain, thalamus, and cortex in a classic animal model for auditory research, the Mongolian gerbil (Meriones unguiculatus). We observed no connectivity between the OFC and the auditory midbrain, and an extremely sparse connection between the dorsolateral OFC and higher order auditory thalamic regions. In contrast, we observed a robust connection between the ventral and medial subdivisions of the OFC and the auditory cortex, with a clear bias for secondary auditory cortical regions. OFC axon terminals were found in all auditory cortical lamina but were significantly more concentrated in the infragranular layers. Tissue-clearing and lightsheet microscopy further revealed that auditory cortical-projecting OFC neurons send extensive axon collaterals throughout the brain, targeting both sensory and non-sensory regions involved in learning, decision-making, and memory. These findings provide a more detailed map of orbitofrontal-auditory connections and shed light on the possible role of the OFC in supporting auditory cognition.

Multiplex imaging in immuno-oncology

Multiplex imaging has emerged as an invaluable tool for immune-oncologists and translational researchers, enabling them to examine intricate interactions among immune cells, stroma, matrix, and malignant cells within the tumor microenvironment (TME). It holds significant promise in the quest to discover improved biomarkers for treatment stratification and identify novel therapeutic targets. Nonetheless, several challenges exist in the realms of study design, experiment optimization, and data analysis. In this review, our aim is to present an overview of the utilization of multiplex imaging in immuno-oncology studies and inform novice researchers about the fundamental principles at each stage of the imaging and analysis process.