A metabolic-dysfunction associated steatotic liver acinus biomimetic induces pancreatic islet dysfunction in a coupled microphysiology system.

Preclinical and clinical studies suggest that lipid-induced hepatic insulin resistance is a primary defect that predisposes to dysfunction in pancreatic islets, implicating a perturbed liver-pancreas axis underlying the comorbidity of T2DM and MASLD. To investigate this hypothesis, we developed a human biomimetic microphysiological system (MPS) coupling our vascularized liver acinus MPS (vLAMPS) with primary islets on a chip (PANIS) enabling MASLD progression and islet dysfunction to be quantitatively assessed. The modular design of this system (vLAMPS-PANIS) allows intra-organ and inter-organ dysregulation to be deconvoluted. When compared to normal fasting (NF) conditions, under early metabolic syndrome (EMS) conditions, the standalone vLAMPS exhibited characteristics of early stage MASLD, while no significant differences were observed in the standalone PANIS. In contrast, with EMS, the coupled vLAMPS-PANIS exhibited a perturbed islet-specific secretome and a significantly dysregulated glucose stimulated insulin secretion (GSIS) response implicating direct signaling from the dysregulated liver acinus to the islets. Correlations between several pairs of a vLAMPS-derived and a PANIS-derived secreted factors were significantly altered under EMS, as compared to NF conditions, mechanistically connecting MASLD and T2DM associated hepatic factors with islet-derived GLP-1 synthesis and regulation. Since vLAMPS-PANIS is compatible with patient-specific iPSCs, this platform represents an important step towards addressing patient heterogeneity, identifying complex disease mechanisms, and advancing precision medicine.

Comparison of Wild-Type and High-risk PNPLA3 variants in a Human Biomimetic Liver Microphysiology System for Metabolic Dysfunction-associated Steatotic Liver Disease Precision Therapy.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a worldwide health epidemic with a global occurrence of approximately 30%. The pathogenesis of MASLD is a complex, multisystem disorder driven by multiple factors including genetics, lifestyle, and the environment. Patient heterogeneity presents challenges for developing MASLD therapeutics, creation of patient cohorts for clinical trials and optimization of therapeutic strategies for specific patient cohorts. Implementing pre-clinical experimental models for drug development creates a significant challenge as simple in vitro systems and animal models do not fully recapitulate critical steps in the pathogenesis and the complexity of MASLD progression. To address this, we implemented a precision medicine strategy that couples the use of our liver acinus microphysiology system (LAMPS) constructed with patient-derived primary cells. We investigated the MASLD-associated genetic variant PNPLA3 rs738409 (I148M variant) in primary hepatocytes, as it is associated with MASLD progression. We constructed LAMPS with genotyped wild type and variant PNPLA3 hepatocytes together with key non-parenchymal cells and quantified the reproducibility of the model. We altered media components to mimic blood chemistries, including insulin, glucose, free fatty acids, and immune activating molecules to reflect normal fasting (NF), early metabolic syndrome (EMS) and late metabolic syndrome (LMS) conditions. Finally, we investigated the response to treatment with resmetirom, an approved drug for metabolic syndrome-associated steatohepatitis (MASH), the progressive form of MASLD. This study using primary cells serves as a benchmark for studies using patient biomimetic twins constructed with patient iPSC-derived liver cells using a panel of reproducible metrics. We observed increased steatosis, immune activation, stellate cell activation and secretion of pro-fibrotic markers in the PNPLA3 GG variant compared to wild type CC LAMPS, consistent with the clinical characterization of this variant. We also observed greater resmetirom efficacy in PNPLA3 wild type CC LAMPS compared to the GG variant in multiple MASLD metrics including steatosis, stellate cell activation and the secretion of pro-fibrotic markers. In conclusion, our study demonstrates the capability of the LAMPS platform for the development of MASLD precision therapeutics, enrichment of patient cohorts for clinical trials, and optimization of therapeutic strategies for patient subgroups with different clinical traits and disease stages.

Modeling mechanisms underlying differential inflammatory responses to COVID-19 in type 2 diabetes using a patient-derived microphysiological organ-on-a-chip system.

Background: COVID-19 pandemic has caused more than 6 million deaths worldwide. Co-morbid conditions such as Type 2 Diabetes (T2D) have increased mortality in COVID-19. With limited translatability of in vitro and small animal models to human disease, human organ-on-a-chip models are an attractive platform to model in vivo disease conditions and test potential therapeutics. Methods: T2D or non-diabetic patient-derived macrophages and human liver sinusoidal endothelial cells were seeded, along with normal hepatocytes and stellate cells in the liver-on-a-chip (LAMPS - liver acinus micro physiological system), perfused with media mimicking non-diabetic fasting or T2D (high levels of glucose, fatty acids, insulin, glucagon) states. The macrophages and endothelial cells were transduced to overexpress the SARS-CoV2-S (spike) protein with appropriate controls before their incorporation into LAMPS. Cytokine concentrations in the efflux served as a read-out of the effects of S-protein expression in the different experimental conditions (non-diabetic-LAMPS, T2D-LAMPS), including incubation with tocilizumab, an FDA-approved drug for severe COVID-19. Findings: S-protein expression in the non-diabetic LAMPS led to increased cytokines, but in the T2D-LAMPS, this was significantly amplified both in the number and magnitude of key pro-inflammatory cytokines (IL6, CCL3, IL1ß, IL2, TNFα, etc.) involved in cytokine storm syndrome (CSS), mimicking severe COVID-19 infection in T2D patients. Compared to vehicle control, tocilizumab (IL6-receptor antagonist) decreased the pro-inflammatory cytokine secretion in T2D-COVID-19-LAMPS but not in non-diabetic-COVID-19-LAMPS. Interpretation: macrophages and endothelial cells play a synergistic role in the pathophysiology of the hyper-inflammatory response seen with COVID-19 and T2D. The effect of Tocilizumab was consistent with large clinical trials that demonstrated Tocilizumab's efficacy only in critically ill patients with severe disease, providing confirmatory evidence that the T2D-COVID-19-LAMPS is a robust platform to model human in vivo pathophysiology of COVID-19 in T2D and for screening potential therapeutics.

Plasma NT1-tau and Aß42 correlate with age and cognitive function in two large Down syndrome cohorts.

INTRODUCTION: People with Down syndrome (DS) often develop Alzheimer's disease (AD). Here, we asked whether ultrasensitive plasma immunoassays for a tau N-terminal fragment (NT1-tau) and Aß isoforms predict cognitive impairment. METHODS: Plasma NT1-tau, Aß37 , Aß40 , and Aß42 levels were measured in a longitudinal discovery cohort (N = 85 participants, 220 samples) and a cross-sectional validation cohort (N = 239). We developed linear models and predicted values in the validation cohort. RESULTS: Discovery cohort linear mixed models for NT1-tau, Aß42 , and Aß37:42 were significant for age; there was no main effect of time. In cross-sectional models, NT1-tau increased and Aß42 decreased with age. NT1-tau predicted cognitive and functional scores. The discovery cohort linear model for NT1-tau predicted levels in the validation cohort. DISCUSSION: NT1-tau correlates with age and worse cognition in DS. Further validation of NT1-tau and other plasma biomarkers of AD neuropathology in DS cohorts is important for clinical utility.

Abundant Aß fibrils in ultracentrifugal supernatants of aqueous extracts from Alzheimer's disease brains.

Soluble oligomers of amyloid ß-protein (Aß) have been defined as aggregates in supernatants following ultracentrifugation of aqueous extracts from Alzheimer's disease (AD) brains and are believed to be upstream initiators of synaptic dysfunction, but little is known about their structures. We now report the unexpected presence of Aß fibrils in synaptotoxic high-speed supernatants from AD brains extracted by soaking in an aqueous buffer. The fibrils did not appear to form during preparation, and their counts by EM correlated with Aß ELISA quantification. Cryo-EM structures of aqueous Aß fibrils were identical to those from sarkosyl-insoluble homogenates. The fibrils in aqueous extracts were labeled by lecanemab, an Aß aggregate-directed antibody reported to improve AD cognitive outcomes. Lecanemab provided protection against aqueous fibril synaptotoxicity. We conclude that fibrils are abundant in aqueous extracts from AD brains and have the same structures as those from plaques. These findings have implications for AD pathogenesis and drug design.

Plasma NT1-tau and Aß 42 correlate with age and cognitive function in two large Down syndrome cohorts.

Introduction: People with Down syndrome (DS) often develop Alzheimer disease (AD). Here we asked whether ultrasensitive plasma immunoassays for a tau N-terminal fragment (NT1-tau) and Aß isoforms predict cognitive impairment. Methods: Plasma NT1-tau, Aß 37 , Aß 40 , and Aß 42 levels were measured in a longitudinal discovery cohort (N = 85 participants, 220 samples) and a cross-sectional validation cohort (N = 239). We developed linear models and predicted values in the validation cohort. Results: Linear mixed models for NT1-tau, Aß 42, and Aß 37:42 were significant for age, there was no main effect of time in the discovery cohort. In cross-sectional models, NT1-tau and Aß 42 increased with age. NT1-tau predicted DLD scores. The discovery cohort linear model for NT1-tau predicted NT1-tau levels in the validation cohort. Discussion: NT1-tau correlates with age and worse cognition in DS. Further validation of NT1-tau and other plasma biomarkers of AD neuropathology in DS cohorts is important for clinical utility.

Unfairness to Patients With Alzheimer Disease in Medicare's Coverage of Antiamyloid Immunotherapy.

This Viewpoint discusses the US Center for Medicare and Medicaid Services' decision on aducanumab, a drug that can treat Alzheimer disease.

A Quantitative Systems Pharmacology Platform Reveals NAFLD Pathophysiological States and Targeting Strategies.

Non-alcoholic fatty liver disease (NAFLD) has a high global prevalence with a heterogeneous and complex pathophysiology that presents barriers to traditional targeted therapeutic approaches. We describe an integrated quantitative systems pharmacology (QSP) platform that comprehensively and unbiasedly defines disease states, in contrast to just individual genes or pathways, that promote NAFLD progression. The QSP platform can be used to predict drugs that normalize these disease states and experimentally test predictions in a human liver acinus microphysiology system (LAMPS) that recapitulates key aspects of NAFLD. Analysis of a 182 patient-derived hepatic RNA-sequencing dataset generated 12 gene signatures mirroring these states. Screening against the LINCS L1000 database led to the identification of drugs predicted to revert these signatures and corresponding disease states. A proof-of-concept study in LAMPS demonstrated mitigation of steatosis, inflammation, and fibrosis, especially with drug combinations. Mechanistically, several structurally diverse drugs were predicted to interact with a subnetwork of nuclear receptors, including pregnane X receptor (PXR; NR1I2), that has evolved to respond to both xenobiotic and endogenous ligands and is intrinsic to NAFLD-associated transcription dysregulation. In conjunction with iPSC-derived cells, this platform has the potential for developing personalized NAFLD therapeutic strategies, informing disease mechanisms, and defining optimal cohorts of patients for clinical trials.

Bioactive human Alzheimer brain soluble Aß: pathophysiology and therapeutic opportunities.

The accumulation of amyloid-ß protein (Aß) plays an early role in the pathogenesis of Alzheimer's disease (AD). The precise mechanism of how Aß accumulation leads to synaptic dysfunction and cognitive impairment remains unclear but is likely due to small soluble oligomers of Aß (oAß). Most studies have used chemical synthetic or cell-secreted Aß oligomers to study their pathogenic mechanisms, but the Aß derived from human AD brain tissue is less well characterized. Here we review updated knowledge on the extraction and characterization of bioactive human AD brain oAß and the mechanisms by which they cause hippocampal synaptic dysfunction. Human AD brain-derived oAß can impair hippocampal long-term potentiation (LTP) and enhance long-term depression (LTD). Many studies suggest that oAß may directly disrupt neuronal NMDA receptors, AMPA receptors and metabotropic glutamate receptors (mGluRs). oAß also impairs astrocytic synaptic functions, including glutamate uptake, D-serine release, and NMDA receptor function. We also discuss oAß-induced neuronal hyperexcitation. These results may suggest a multi-target approach for the treatment of AD, including both oAß neutralization and reversal of glutamate-mediated excitotoxicity.

A calcium-sensitive antibody isolates soluble amyloid-ß aggregates and fibrils from Alzheimer's disease brain.

Aqueously soluble oligomers of amyloid-ß peptide may be the principal neurotoxic forms of amyloid-ß in Alzheimer's disease, initiating downstream events that include tau hyperphosphorylation, neuritic/synaptic injury, microgliosis and neuron loss. Synthetic oligomeric amyloid-ß has been studied extensively, but little is known about the biochemistry of natural oligomeric amyloid-ß in human brain, even though it is more potent than simple synthetic peptides and comprises truncated and modified amyloid-ß monomers. We hypothesized that monoclonal antibodies specific to neurotoxic oligomeric amyloid-ß could be used to isolate it for further study. Here we report a unique human monoclonal antibody (B24) raised against synthetic oligomeric amyloid-ß that potently prevents Alzheimer's disease brain oligomeric amyloid-ß-induced impairment of hippocampal long-term potentiation. B24 binds natural and synthetic oligomeric amyloid-ß and a subset of amyloid plaques, but only in the presence of Ca2+. The amyloid-ß N terminus is required for B24 binding. Hydroxyapatite chromatography revealed that natural oligomeric amyloid-ß is highly avid for Ca2+. We took advantage of the reversible Ca2+-dependence of B24 binding to perform non-denaturing immunoaffinity isolation of oligomeric amyloid-ß from Alzheimer's disease brain-soluble extracts. Unexpectedly, the immunopurified material contained amyloid fibrils visualized by electron microscopy and amenable to further structural characterization. B24-purified human oligomeric amyloid-ß inhibited mouse hippocampal long-term potentiation. These findings identify a calcium-dependent method for purifying bioactive brain oligomeric amyloid-ß, at least some of which appears fibrillar.

An ultra-sensitive immunoassay detects and quantifies soluble Aß oligomers in human plasma.

INTRODUCTION: Evidence strongly suggests that soluble oligomers of amyloid beta protein (oAß) help initiate the pathogenic cascade of Alzheimer's disease (AD). To date, there have been no validated assays specific for detecting and quantifying oAß in human blood. METHODS: We developed an ultrasensitive oAß immunoassay using a novel capture antibody (71A1) with N-terminal antibody 3D6 for detection that specifically quantifies soluble oAß in the human brain, cerebrospinal fluid (CSF), and plasma. RESULTS: Two new antibodies (71A1; 1G5) are oAß-selective, label Aß plaques in non-fixed AD brain sections, and potently neutralize the synaptotoxicity of AD brain-derived oAß. The 71A1/3D6 assay showed excellent dilution linearity in CSF and plasma without matrix effects, good spike recovery, and specific immunodepletion. DISCUSSION: We have created a sensitive, high throughput, and inexpensive method to quantify synaptotoxic oAß in human plasma for analyzing large cohorts of aged and AD subjects to assess the dynamics of this key pathogenic species and response to therapy.

In situ functional cell phenotyping reveals microdomain networks in colorectal cancer recurrence.

Tumors are dynamic ecosystems comprising localized niches (microdomains), possessing distinct compositions and spatial configurations of cancer and non-cancer cell populations. Microdomain-specific network signaling coevolves with a continuum of cell states and functional plasticity associated with disease progression and therapeutic responses. We present LEAPH, an unsupervised machine learning algorithm for identifying cell phenotypes, which applies recursive steps of probabilistic clustering and spatial regularization to derive functional phenotypes (FPs) along a continuum. Combining LEAPH with pointwise mutual information and network biology analyses enables the discovery of outcome-associated microdomains visualized as distinct spatial configurations of heterogeneous FPs. Utilization of an immunofluorescence-based (51 biomarkers) image dataset of colorectal carcinoma primary tumors (n = 213) revealed microdomain-specific network dysregulation supporting cancer stem cell maintenance and immunosuppression that associated selectively with the recurrence phenotype. LEAPH enables an explainable artificial intelligence platform providing insights into pathophysiological mechanisms and novel drug targets to inform personalized therapeutic strategies.

A systems-level study reveals host-targeted repurposable drugs against SARS-CoV-2 infection.

Understanding the mechanism of SARS-CoV-2 infection and identifying potential therapeutics are global imperatives. Using a quantitative systems pharmacology approach, we identified a set of repurposable and investigational drugs as potential therapeutics against COVID-19. These were deduced from the gene expression signature of SARS-CoV-2-infected A549 cells screened against Connectivity Map and prioritized by network proximity analysis with respect to disease modules in the viral-host interactome. We also identified immuno-modulating compounds aiming at suppressing hyperinflammatory responses in severe COVID-19 patients, based on the transcriptome of ACE2-overexpressing A549 cells. Experiments with Vero-E6 cells infected by SARS-CoV-2, as well as independent syncytia formation assays for probing ACE2/SARS-CoV-2 spike protein-mediated cell fusion using HEK293T and Calu-3 cells, showed that several predicted compounds had inhibitory activities. Among them, salmeterol, rottlerin, and mTOR inhibitors exhibited antiviral activities in Vero-E6 cells; imipramine, linsitinib, hexylresorcinol, ezetimibe, and brompheniramine impaired viral entry. These novel findings provide new paths for broadening the repertoire of compounds pursued as therapeutics against COVID-19.

Quantifying the progression of non-alcoholic fatty liver disease in human biomimetic liver microphysiology systems with fluorescent protein biosensors.

Metabolic syndrome is a complex disease that involves multiple organ systems including a critical role for the liver. Non-alcoholic fatty liver disease (NAFLD) is a key component of the metabolic syndrome and fatty liver is linked to a range of metabolic dysfunctions that occur in approximately 25% of the population. A panel of experts recently agreed that the acronym, NAFLD, did not properly characterize this heterogeneous disease given the associated metabolic abnormalities such as type 2 diabetes mellitus (T2D), obesity, and hypertension. Therefore, metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed as the new term to cover the heterogeneity identified in the NAFLD patient population. Although many rodent models of NAFLD/NASH have been developed, they do not recapitulate the full disease spectrum in patients. Therefore, a platform has evolved initially focused on human biomimetic liver microphysiology systems that integrates fluorescent protein biosensors along with other key metrics, the microphysiology systems database, and quantitative systems pharmacology. Quantitative systems pharmacology is being applied to investigate the mechanisms of NAFLD/MAFLD progression to select molecular targets for fluorescent protein biosensors, to integrate computational and experimental methods to predict drugs for repurposing, and to facilitate novel drug development. Fluorescent protein biosensors are critical components of the platform since they enable monitoring of the pathophysiology of disease progression by defining and quantifying the temporal and spatial dynamics of protein functions in the biosensor cells, and serve as minimally invasive biomarkers of the physiological state of the microphysiology system experimental disease models. Here, we summarize the progress in developing human microphysiology system disease models of NAFLD/MAFLD from several laboratories, developing fluorescent protein biosensors to monitor and to measure NAFLD/MAFLD disease progression and implementation of quantitative systems pharmacology with the goal of repurposing drugs and guiding the creation of novel therapeutics.

Human biomimetic liver microphysiology systems in drug development and precision medicine.

Microphysiology systems (MPS), also called organs-on-chips and tissue chips, are miniaturized functional units of organs constructed with multiple cell types under a variety of physical and biochemical environmental cues that complement animal models as part of a new paradigm of drug discovery and development. Biomimetic human liver MPS have evolved from simpler 2D cell models, spheroids and organoids to address the increasing need to understand patient-specific mechanisms of complex and rare diseases, the response to therapeutic treatments, and the absorption, distribution, metabolism, excretion and toxicity of potential therapeutics. The parallel development and application of transdisciplinary technologies, including microfluidic devices, bioprinting, engineered matrix materials, defined physiological and pathophysiological media, patient-derived primary cells, and pluripotent stem cells as well as synthetic biology to engineer cell genes and functions, have created the potential to produce patient-specific, biomimetic MPS for detailed mechanistic studies. It is projected that success in the development and maturation of patient-derived MPS with known genotypes and fully matured adult phenotypes will lead to advanced applications in precision medicine. In this Review, we examine human biomimetic liver MPS that are designed to recapitulate the liver acinus structure and functions to enhance our knowledge of the mechanisms of disease progression and of the absorption, distribution, metabolism, excretion and toxicity of therapeutic candidates and drugs as well as to evaluate their mechanisms of action and their application in precision medicine and preclinical trials.

Spatial domain analysis predicts risk of colorectal cancer recurrence and infers associated tumor microenvironment networks.

An unmet clinical need in solid tumor cancers is the ability to harness the intrinsic spatial information in primary tumors that can be exploited to optimize prognostics, diagnostics and therapeutic strategies for precision medicine. Here, we develop a transformational spatial analytics computational and systems biology platform (SpAn) that predicts clinical outcomes and captures emergent spatial biology that can potentially inform therapeutic strategies. We apply SpAn to primary tumor tissue samples from a cohort of 432 chemo-naïve colorectal cancer (CRC) patients iteratively labeled with a highly multiplexed (hyperplexed) panel of 55 fluorescently tagged antibodies. We show that SpAn predicts the 5-year risk of CRC recurrence with a mean AUROC of 88.5% (SE of 0.1%), significantly better than current state-of-the-art methods. Additionally, SpAn infers the emergent network biology of tumor microenvironment spatial domains revealing a spatially-mediated role of CRC consensus molecular subtype features with the potential to inform precision medicine.