Biology subjects

Mostoslavsky, G.

Publications and source records attributed to Mostoslavsky, G..

8 recordsLinked to original sources

bioRxiv2026

Immunomodulatory RIG-I Agonist SLR14 Confers Protection Against a Range of Highly Pathogenic Negative Sense RNA viruses

Emerging and re-emerging zoonotic RNA viruses, including filoviruses, henipaviruses and Rift Valley Fever virus (RVFV), pose a significant threat to human health. Due to their epidemic potential and high pathogenicity, these viruses are categorized as WHO priority pathogens, yet we still lack effective medical countermeasures (MCMs) against most of these dangerous pathogens, supporting that host-directed antivirals will be advantageous for broadly acting MCMs. Here we assessed the antiviral efficacy of SLR14, an immunomodulatory stem-loop RNA that activates RIG-I, for its activity against a panel of highly pathogenic viruses. SLR14 treatment provided broad-spectrum protection, markedly reducing infection with Ebola virus (EBOV), Marburg virus, and Sudan virus in human primary monocyte-derived macrophages, and Nipah virus replication in iPSC-derived endothelial cells, whether administered prophylactically or therapeutically. In vivo, a single dose of SLR14 protected mice against lethal RVFV infection when administered prophylactically, and, notably, retained significant efficacy when administered up to two days post-infection. Therapeutic SLR14 administration also improved survival rates of EBOV-infected mice. Although EBOV infection and SLR14 treatment activated overlapping innate immune pathways in human macrophages, viral infection induced a nonprotective response, whereas SLR14 elicited a well-regulated, markedly stronger and protective interferon-stimulated and inflammatory gene signature while avoiding prolonged IFN gene upregulation. Our data identify SLR14 as a potent host-directed therapeutic with broad antiviral efficacy against some of the most lethal viral pathogens.

microbiology↗

bioRxiv2025

Generation of effector CD4+ T cells from Human iPSC

Off the shelf CD4+ T cell therapies, particularly those with immunoregulatory or cell repair functions, could be transformative in CAR therapies for cancers and treatment of chronic inflammatory diseases. However, progress is stunted in this area due to challenges generating human CD4+ T cells from induced pluripotent stem cells. Here we describe a key role for the withdrawal of Notch ligand during the final step of stimulation through the T cell receptor to prompt T cell maturation allowing access to the CD4 lineage in iPSC T cells (iCD4+ T cells). Functional analyses of iCD4+ T cells using a novel high-parameter CyTOF intracellular cytokine staining panel revealed both canonical Th1 cytokine signatures and cells producing varying combinations of other cytokines including IL-4, IL-8, and IL-13. Single cell RNA sequencing of iCD4+ T cells demonstrated a transcriptional signature similar to human blood CD4+ T cells. We believe this robust yet simple platform represents a key step towards the generation of off the shelf iCD4+ T cell therapies with utility for the treatment of a panoply of diseases including cancer and inflammatory autoimmune disorders. HIGHLIGHTST cell receptor stimulation of iPSC CD4+/CD8+ T cell progenitors on coating without Notch ligand allows access to the CD4+ T cell lineage iPSC derived CD4+ T cells express varied cytokines in response to stimulation

immunology↗

bioRxiv2024

Expression of Intron-containing HIV-1 RNA Induces NLRP1 Inflammasome Activation in Myeloid Cells

Despite the success of antiretroviral therapy (ART) in suppressing plasma viremia in people living with human immunodeficiency virus type-1 (HIV-1), persistent viral RNA expression in tissue reservoirs is observed and can contribute to HIV-1-induced immunopathology and comorbidities. Infection of long-lived innate immune cells, such as tissue-resident macrophages and microglia may contribute to persistent viral RNA production and chronic inflammation. We recently reported that de-novo cytoplasmic expression of HIV-1 intron-containing RNA (icRNA) in macrophages and microglia leads to MDA5 and MAVS-dependent innate immune sensing and induction of type I IFN responses, demonstrating that HIV icRNA is a pathogen-associated molecular pattern (PAMP). In this report, we show that cytoplasmic expression of HIV-1 icRNA also induces NLRP1 inflammasome activation and IL-1{beta} secretion in macrophages and microglia in a RLR- and endosomal TLR-independent manner. Infection of both macrophages and microglia with either replication-competent or single-cycle HIV-1 induced IL-1{beta} secretion, which was attenuated when cytoplasmic expression of viral icRNA was prevented. While IL-1{beta} secretion was blocked by treatment with caspase-1 inhibitors or knockdown of NLRP1 or caspase-1 expression in HIV- infected macrophages, overexpression of NLRP1 significantly enhanced IL-1{beta} secretion in an HIV-icRNA-dependent manner. Immunoprecipitation analysis revealed interaction of HIV-1 icRNA, but not multiply-spliced HIV-1 RNA, with NLRP1, suggesting that HIV-1 icRNA sensing by NLRP1 is sufficient to trigger inflammasome activation. Together, these findings reveal a pathway of NLRP1 inflammasome activation induced by de novo expressed HIV icRNA in HIV- infected myeloid cells.

microbiology↗

bioRxiv2022

An iPSC library from a family with Creutzfeldt-Jakob disease caused by the E200K mutation

The most common subtype of genetic prion disease is caused by the E200K mutation of the prion protein. We have obtained samples from 22 members of a multi-generational Israeli family harboring this mutation, and generated a library of induced pluripotent stem cells (iPSCs) representing nine carriers and four non-carriers. Whole-exome sequencing was performed on all individuals. A comparison of neurons derived from E200K iPSCs to those from non-carriers revealed the presence of several disease-relevant phenotypes. Neurons from E200K carriers were found to contain thioflavin S-positive accumulations of PrP in their cell bodies. In addition, these neurons displayed disruptions of NMDA receptor/PSD95 co-localization at postsynaptic sites. Our study shows that iPSC-derived neurons, which express physiologically relevant levels of mutant PrP in a human neuronal context, can model certain aspects of human prion disease, offering a powerful platform for investigating pathological mechanisms and testing potential therapeutics.

neuroscience↗

bioRxiv2022

DE-NOVO HEMATOPOIESIS FROM THE FETAL LUNG

Hemogenic endothelial cells (HECs) are specialized cells that undergo endothelial to hematopoietic transition (EHT) to give rise to hematopoietic progenitors. Though not defined as a hematopoietic organ, the lung houses many resident hematopoietic cells, aids in platelet biogenesis, and is a reservoir for hematopoietic stem and progenitor cells (HSPCs), but lung HECs have never been described. Using explant cultures of murine and human fetal lungs, we demonstrate that the fetal lung is a source of HECs that have the functional capacity to undergo EHT to produce de-novo HSPCs. Flow cytometric and functional assessment of fetal lung explants showed the production of HSPCs that expressed key EHT and pre-HSPC markers. scRNA-Seq and small molecule modulation demonstrated that fetal lung EHT is reliant on canonical EHT signaling pathways. These findings suggest that functional HECs are present in the fetal lung, thus establishing this location as a potential extramedullary site of de-novo hematopoiesis.

developmental biology↗

bioRxiv2021

A multimodal iPSC platform for cystic fibrosis drug testing

Cystic fibrosis (CF) is a monogenic lung disease caused by dysfunction of the cystic fibrosis transmembrane regulator (CFTR) anion channel, resulting in significant morbidity and mortality. The progress in elucidating the role of the CFTR channel using established animal and cell-based models led to the recent discovery of effective CFTR modulators for most individuals with CF. However, a subset of individuals with CF do not respond to these modulators and there is an urgent need to develop novel therapeutic strategies. In this study, we assembled a panel of iPSCs derived from individuals with common or rare variants representative of three distinct classes of CFTR dysfunction. To measure CFTR function in patient-specific iPSCs we adapted two established in vitro assays of CFTR function to iPSC-derived airway cells. In both a 3-D spheroid assay using forskolin-induced swelling as well as planar cultures composed of polarized mucociliary airway epithelial cells, we quantified CFTR baseline function and response to CFTR modulators and detected genotype-specific differences. Our results demonstrate the potential of the human iPSC platform as a research tool to study cystic fibrosis and in particular accelerate therapeutic development for CF caused by rare mutations.

developmental biology↗

bioRxiv2020

Human iPSC-derived alveolar and airway epithelial cells can be cultured at air-liquid interface and express SARS-CoV-2 host factors

Development of an anti-SARS-CoV-2 therapeutic is hindered by the lack of physiologically relevant model systems that can recapitulate host-viral interactions in human cell types, specifically the epithelium of the lung. Here, we compare induced pluripotent stem cell (iPSC)-derived alveolar and airway epithelial cells to primary lung epithelial cell controls, focusing on expression levels of genes relevant for COVID-19 disease modeling. iPSC-derived alveolar epithelial type II-like cells (iAT2s) and iPSC-derived airway epithelial lineages express key transcripts associated with lung identity in the majority of cells produced in culture. They express ACE2 and TMPRSS2, transcripts encoding essential host factors required for SARS-CoV-2 infection, in a minor subset of each cell sub-lineage, similar to frequencies observed in primary cells. In order to prepare human culture systems that are amenable to modeling viral infection of both the proximal and distal lung epithelium, we adapt iPSC-derived alveolar and airway epithelial cells to two-dimensional air-liquid interface cultures. These engineered human lung cell systems represent sharable, physiologically relevant platforms for SARS-CoV-2 infection modeling and may therefore expedite the development of an effective pharmacologic intervention for COVID-19.

molecular biology↗

bioRxiv2019

Single-cell time-series mapping of cell fate trajectories reveals an expanded developmental potential for human PSC-derived distal lung progenitors

Alveolar epithelial type 2 cells (AEC2s) are the facultative progenitors responsible for maintaining lung alveoli throughout life, yet are difficult to access from patients for biomedical research or lung regeneration applications. Here we engineer AEC2s from human induced pluripotent stem cells (iPSCs) in vitro and use single cell RNA sequencing (scRNA-seq) to profile the detailed kinetics of their differentiation over time. We focus on both the desired target cells as well as those that appear to diverge to alternative endodermal fates. By combining scRNA-seq with lentiviral barcoding to trace differentiating clones, we reveal the bifurcating cell fate trajectories followed as primordial lung progenitors differentiate into mature AEC2s. We define the global transcriptomic signatures of primary developing human AEC2s from fetal through adult stages in order to identify the subset of in vitro differentiating cells that appear to recapitulate the path of in vivo development. In addition, we develop computational methods based on Continuous State Hidden Markov Models (CSHMM) to identify the precise timing and type of signals, such as over-exuberant Wnt responses, that induce some early multipotent NKX2-1+ progenitors to lose lung fate as they clonally diverge into a variety of non-lung endodermal lineages. Finally, we find that this initial developmental plasticity is regulatable via Wnt modulation, and subsides over time, ultimately resulting in iPSC-derived AEC2s that exhibit a stable phenotype and nearly limitless self-renewal capacity in vitro. Our methods and computational approaches can be widely applied to study and control directed differentiation, producing an inexhaustible supply of mature lineages, exemplified here by the generation of AEC2s.

developmental biology↗