Biology subjects

Schreiner, J.

Publications and source records attributed to Schreiner, J..

6 recordsLinked to original sources

bioRxiv2024

Predicting nanocarrier permeation across the human intestine in vitro: Model matters

For clinical translation of oral nanocarriers, simulation of the complex intestinal microenvironment is crucial to evaluate interactions and transport across the intestinal mucosa for predicting the drugs bioavailability. However, permeation studies are often conducted using simplistic cell culture models, overlooking key physiological factors such as tissue composition, morphology, and additional diffusion barriers as constituted by mucus. This oversight may potentially lead to an incomplete evaluation of the nanocarrier-tissue interactions and an overestimation of permeation. In this study, we systematically investigated different 3D tissue models of the human intestine under static cultivation and dynamic flow conditions with respect to tissue morphology, mucus production, and their impact on nanocarrier permeation. Our results revealed that the cell ratio between the different cell types (enterocytes and goblet cells), as well as the choice of culture conditions, had a notable impact on tissue layer thickness, mucus secretion, and barrier impairment, all of which were increased under dynamic flow conditions. Permeation studies with polymeric nanocarriers (PLGA and PEG-PLGA) elucidated that the amount of mucus present in the respective model was the limiting factor for the permeation of PLGA nanocarriers, while tissue topography represented the key factor influencing PEG-PLGA nanocarrier permeation. Furthermore, both nanocarriers exhibited diametrically opposite permeation kinetics in a direct comparison to soluble compounds. In summary, these findings reveal the critical role of the implemented test systems on permeation assessment and emphasize that, in the context of preclinical nanocarrier testing, the choice of in vitro model matters.

pharmacology and toxicology↗

bioRxiv2023

Enhancer-driven regulatory network of forebrain human development provides insights into autism

Cell differentiation is orchestrated by transcription factors (TFs) binding to enhancers, shaping gene regulatory networks that drive neuronal lineage specification. Deciphering these enhancer-driven networks in human forebrain development is essential for understanding the genetic basis of neurodevelopmental disorders. Through integrative epigenomic and transcriptomic analyses of human forebrain organoids derived from 10 individuals with autism spectrum disorder (ASD) and their neurotypical fathers, we constructed a comprehensive enhancer-driven gene regulatory network (GRN) of early neurodevelopment. This GRN revealed hierarchical regulatory transitions guiding neuronal differentiation and was experimentally validated via CRISPR interference (CRISPRi) and loss-of-function analyses. A subnetwork linked ASD-associated transcriptomic alterations to dysregulated TF activity, implicating FOXG1, BHLHE22, EOMES, and NEUROD2 as key regulators of excitatory neuron specification in macrocephalic ASD. These findings suggest that ASD disrupts enhancer-driven regulatory frameworks, altering neuronal cell fate decisions in the developing fetal brain.

genomics↗

bioRxiv2022

ASD modelling in organoids reveals imbalance of excitatory cortical neuron subtypes during early neurogenesis

There is no clear genetic etiology or convergent pathophysiology for autism spectrum disorders (ASD). Using cortical organoids and single-cell transcriptomics, we modeled alterations in the formation of the forebrain between sons with idiopathic ASD and their unaffected fathers in thirteen families. Alterations in the transcriptome suggest that ASD pathogenesis in macrocephalic and normocephalic probands involves an opposite disruption of the balance between the excitatory neurons of the dorsal cortical plate and other lineages such as the early-generated neurons from the putative preplate. The imbalance stemmed from a divergent expression of transcription factors driving cell fate during early cortical development. While we did not find probands genomic variants explaining the observed transcriptomic alterations, a significant overlap between altered transcripts and reported ASD risk genes affected by rare variants suggests a degree of gene convergence between rare forms of ASD and developmental transcriptome in idiopathic ASD.

neuroscience↗

bioRxiv2020

Early developmental asymmetries in cell lineage trees in living individuals

Post-zygotic mosaic mutations can be used to track cell lineages in humans. By using cell cloning and induced pluripotent cell lines, we analyzed early cell lineages in two living individuals (a patient and a control), and a postmortem human specimen. Of ten reconstructed post-zygotic divisions, none resulted in balanced contributions of daughter lineages to tissues. In both living individuals one of two lineages from the first cleavage was dominant across tissues, with 90% frequency in blood. We propose that the efficiency of DNA repair contributes to lineage imbalance. Allocation of lineages in postmortem brain correlated with anterior-posterior axis, associating lineage history with cell fate choices in embryos. Recurrence of germline variants as mosaic suggested that certain loci may be particularly susceptible to mutagenesis. We establish a minimally invasive framework for defining cell lineages in any living individual, which paves the way for studying their relevance in health and disease.

genomics↗

bioRxiv2020

Systemic and mucosal antibody secretion specific to SARS-CoV-2 during mild versus severe COVID-19

BackgroundInfection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes an acute illness termed coronavirus disease 2019 (COVID-19). Humoral immune responses likely play an important role in containing SARS-CoV-2, however, the determinants of SARS-CoV-2-specific antibody responses are unclear. MethodsUsing immunoassays specific for the SARS-CoV-2 spike protein, we determined SARS-CoV-2-specific immunoglobulin A (IgA) and immunoglobulin G (IgG) in sera and mucosal fluids of two cohorts, including patients with quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR)-confirmed SARS-CoV-2 infection (n = 56; median age 61 years) with mild versus severe COVID-19, and SARS-CoV-2-exposed healthcare workers (n = 109; median age 36 years) with or without symptoms and tested negative or positive by RT-qPCR. FindingsOn average, SARS-CoV-2-specific serum IgA titers in mild COVID-19 cases became positive eight days after symptom onset and were often transient, whereas serum IgG levels remained negative or reached positive values 9-10 days after symptom onset. Conversely, patients with severe COVID-19 showed a highly significant increase of SARS-CoV-2-specific serum IgA and IgG titers as a function of duration since symptom onset, independent of patient age and comorbidities. Very high levels of SARS-CoV-2-specific serum IgA correlated with severe acute respiratory distress syndrome (ARDS). Interestingly, some of the SARS-CoV-2-exposed healthcare workers with negative SARS-CoV-2-specific IgA and IgG serum titers had detectable SARS-CoV-2-specific IgA antibodies in their nasal fluids and tears. Moreover, SARS-CoV-2-specific IgA levels in nasal fluids of these healthcare workers were inversely correlated with patient age. InterpretationThese data show that systemic IgA and IgG production against SARS-CoV-2 develops mainly in severe COVID-19, with very high IgA levels seen in patients with severe ARDS, whereas mild disease may be associated with transient serum titers of SARS-CoV-2-specific antibodies but stimulate mucosal SARS-CoV-2-specific IgA secretion. The findings suggest four grades of antibody responses dependent on COVID-19 severity.

immunology↗

bioRxiv2018

Walking along chromosomes with super-resolution imaging, contact maps, and integrative modeling

Chromosome structure is thought to be crucial for proper functioning of the nucleus. Here, we present a method for visualizing chromosomal DNA at super-resolution and then integrating Hi-C data to produce three-dimensional models of chromosome organization. We begin by applying Oligopaint probes and the single-molecule localization microscopy methods of OligoSTORM and OligoDNA-PAINT to image 8 megabases of human chromosome 19, discovering that chromosomal regions contributing to compartments can form distinct structures. Intriguingly, our data also suggest that homologous maternal and paternal regions may be differentially organized. Finally, we integrate imaging data with Hi-C and restraint-based modeling using a method called integrative modeling of genomic regions (IMGR) to increase the genomic resolution of our traces to 10 kb.\n\nOne Sentence SummarySuper-resolution genome tracing, contact maps, and integrative modeling enable 10 kb resolution glimpses of chromosome folding.

genetics↗