Biology subjects

Beltran, E.

Publications and source records attributed to Beltran, E..

11 recordsLinked to original sources

bioRxiv2026

A reproducible human brain tissue model to study physiological and disease-associated microglia phenotypes

Stem-cell-based in vitro models offer promising potential to elucidate human brain cell functions and interactions under physiological and pathological conditions. However, harnessing this potential is impaired by low reproducibility, maturity, or cell-type diversity of existing models. Especially, prolonged incorporation of mature microglia and studies of neuroinflammation have proven challenging. Here, we developed a 3D cortical brain tissue model (3BTM) containing neurons, astrocytes, and microglia with high reproducibility, maturity, and viability. 3BTMs show morphological, functional, and proteomic maturation of all cell types, leading to high similarity to their in vivo counterparts. Incorporated microglia survive for over 6 months and display mature morphology, functions, and gene expression. Importantly, when engineered to model Alzheimers disease pathology, 3BTMs recapitulate key disease hallmarks including amyloid deposition, increased phospho-Tau levels, and neuroinflammation, with microglia shifting their transcriptional landscape to disease-relevant signatures. Together, our model offers unprecedented possibilities for studying physiological and pathological states of human brain tissue and translational applications.

neuroscience↗

bioRxiv2026

Brain Region-Specific Oligodendrocyte States Highlight Mitochondrial Gene Upregulation and Loss of Canonical Identity Signatures in Alzheimers Disease

Oligodendrocyte dysfunction and heterogeneity are emerging as key contributors to Alzheimers disease (AD) pathology, though cellular mechanisms remain unclear. Using single-nucleus RNA sequencing across three cortical regions from the same individuals, we identified region- and disease-specific transcriptomic changes, including increased mitochondrial genes and loss of cell type signatures. These results highlight the importance of biologically-informed quality control and underscore the value of multi-regional analysis for understanding AD pathogenesis and progression.

bioinformatics↗

bioRxiv2024

Fusarium graminearum copper amine-oxidases redundantly increase virulence by converting tryptamine from hydrolyzed plant defense compounds into auxin

Plant pathogenic fungi have evolved different strategies to interfere with plant defense mechanisms. The well described fungal plant pathogen Fusarium graminearum is not only able to produce trichothecene toxins like deoxynivalenol, but also the plant hormone auxin. Highly elevated levels of auxin and auxin derivatives such as IAA-glucoside or IAA amino-acid conjugates were observed in wheat cultivar Apogee infected with F. graminearum. We report that F. graminearum is able to cleave tryptamine-derived hydroxycinnamic acid amides, e.g. the defense compound coumaroyl-tryptamine. In this study we investigated copper amine-oxidases, candidate genes for auxin biosynthesis converting tryptamine into the IAA precursor indole-3-acetyldehyde. After consecutive knock outs of all seven copper amine oxidases the resulting septuple knock out strain had strongly reduced ability to produce auxin. Virulence of the septuple mutant was significantly impaired while DON production in planta was comparable to the wild type. We conclude that F. graminearum, often presumed to be a simple nectrotroph, has a biotrophic phase and is able to employ plant defense compounds by converting them into defense suppressing auxin.

molecular biology↗

bioRxiv2023

Innate immune memory after brain injury drives inflammatory cardiac dysfunction

The enormous medical burden of stroke is not only due to the brain injury itself and the acute systemic effects, but is largely determined by chronic comorbidities that develop secondarily after stroke. We hypothesized that the high rate of comorbidity developing after a stroke might have a shared immunological cause, however, the chronic effects of brain injury on systemic immunity have so far been barely investigated. Here, we identified myeloid innate immune memory as a cause of remote organ dysfunction after stroke. Using single-cell sequencing, we identified persistent pro-inflammatory transcriptomic changes in resident monocytes/macrophages in multiple organs one month after experimental ischemic brain injury, which was particularly abundant in the heart and associated with the development of cardiac fibrosis and diastolic dysfunction. A similar phenotype was seen in myocardial autopsy samples from stroke versus control patients. We observed chronic functional changes in myeloid hematopoiesis driven by post-stroke IL-1{beta}-mediated epigenetic changes. These alterations could be transplanted to naive recipient mice and were sufficient to induce cardiac dysfunction. By effectively blocking the trafficking of pro-inflammatory monocytes from the bone marrow to the heart using a dual CCR2/5 inhibitor, we successfully prevented post-stroke cardiac dysfunction. This approach holds promising potential as a novel immune-targeted secondary prevention therapy. We anticipate that the epigenetic immune reprogramming mechanisms detailed here for the brain-heart axis could be generalized to provide a novel framework for explaining the development of various comorbidities after acute tissue injury in remote organs.

immunology↗

bioRxiv2023

T:B cell communication in ectopic lymphoid follicles in CNS autoimmunity

Meningeal ectopic lymphoid follicle-like structures (eLFs) have been described in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), but their role in CNS autoimmunity is unclear. To analyze the cellular phenotypes and interactions within these structures, we employed a Th17 adoptive transfer EAE model featuring formation of large, numerous eLFs. Single-cell transcriptomic analysis revealed that clusters of activated B cells and B1/Marginal Zone-like B cells are overrepresented in the CNS and identified B cells poised for undergoing antigen-driven germinal center (GC) reactions and clonal expansion in the CNS. Furthermore, CNS B cells showed enhanced capacity for antigen presentation and immunological synapse formation compared to peripheral B cells. To directly visualize Th17:B cell cooperation in eLFs, we labeled Th17 cells with a ratiometric calcium sensor, and tracked their interactions with tdTomato-labeled B cells in real-time. Thereby, we demonstrated for the first time that T and B cells form long-lasting antigen-specific contacts in meningeal eLFs that result in reactivation of autoreactive T cells. Consistent with these findings, autoreactive T cells depended on CNS B cells to maintain a pro-inflammatory cytokine profile in the CNS. Collectively, our study reveals that extensive T:B cell cooperation occurs in meningeal eLFs in our model promoting differentiation and clonal expansion of B cells, as well as reactivation of CNS T cells and thereby supporting smoldering inflammatory processes within the CNS compartment. Our results provide valuable insights into the function of eLFs and may provide a direction for future research in MS.

immunology↗

bioRxiv2022

High-resolution profiling of neoantigen-specific T cell receptor activation signatures links moderate stimulation patterns to resilience and sustained tumor control

Neoantigen-specific T cell receptors (neoTCRs) promise a safe, highly personalized therapeutic approach in anti-tumor immunotherapy. Substantial progress has been made regarding their identification whereas detailed functional assessment of single TCR characteristics impacting therapeutic efficacy is lacking. We previously identified and functionally characterized neoTCRs specific for neoepitopes derived from KIF2C and SYTL4 demonstrating differences in functional avidity in a patient with metastatic melanoma. In this work, we now combined single-cell TCR- and RNA-sequencing using stimulated peripheral blood derived CD8+ T cells of this patient and thereby identified two new neoTCRs recognizing the previously identified mutated epitope KIF2CP13L. Analyzing patient-derived neoTCR expressing T cells, we detected distinct activation patterns as a measure for substantial heterogeneity within oligoclonal T cell responses towards neoantigens upon specific ex vivo-restimulation. Moreover, neoTCR-transgenic T cells from healthy donors were employed for detailed in vitro and in vivo fine-characterization focusing on TCR-intrinsic functional patterns. Most importantly, in a xenogeneic mouse model experimentally simulating rechallenge of tumor infiltrating lymphocytes (TILs) after adoptive T cell transfer, we found that T cells expressing neoTCRs with a moderate activation profile provide a stable and more sustained anti-tumor response upon repeated in vivo tumor challenge as compared to neoTCRs with a stronger, burst-like reactivity. These insights have significant implications for engineering TCR-transgenic T cells for therapeutic purposes. One Sentence SummaryCombining TCR specificity linked single-cell transcriptomics with in vitro and in vivo characterization of transgenic T cells helps to decipher functional potential and persistence of neoantigen-specific T cell receptors (TCRs) for TCR-transgenic T cell-based adoptive cellular anti-tumor immunotherapy.

immunology↗

bioRxiv2022

Persistent virus-specific and clonally expanded antibody secreting cells respond to induced self antigen in the CNS

B cells contribute to the pathogenesis of both cellular- and humoral-mediated central nervous system (CNS) inflammatory diseases through a variety of mechanisms. In such conditions, B cells may enter the CNS parenchyma and contribute to local tissue destruction. It remains unexplored, however, how infection and autoimmunity drive transcriptional phenotypes, repertoire features, and antibody functionality. Here, we profiled B cells from the CNS of murine models of intracranial (i.c.) viral infections and autoimmunity. We identified a population of clonally expanded, antibody secreting cells (ASCs) that had undergone class-switch recombination and extensive somatic hypermutation following i.c. infection with attenuated lymphocytic choriomeningitis virus (rLCMV). Recombinant expression and characterisation of these antibodies revealed specificity to viral antigens (LCMV glycoprotein GP), correlating with ASC persistence in the brain weeks after resolved infection. Furthermore, these virus-specific ASCs upregulated proliferation and expansion programs in response to the conditional and transient induction of the LCMV GP as a neo-self antigen by astrocytes. This class-switched, clonally expanded, and mutated population persisted and was even more pronounced when peripheral B cells were depleted prior to autoantigen induction in the CNS. In contrast, the most expanded B cell clones in mice with persistent expression of LCMV GP in the CNS did not exhibit neo-self antigen specificity, potentially a consequence of local tolerance induction. Finally, a comparable population of clonally expanded, class-switched, proliferating ASCs was detected in the cerebrospinal fluid of multiple sclerosis patients. Taken together, our findings support the existence of B cells that populate the CNS and are capable of responding to locally encountered autoantigens. Graphical abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

immunology↗

bioRxiv2022

Identification of essential modules regulating T cell migration to the central nervous system in multiple sclerosis

Multiple sclerosis (MS) is a neuroinflammatory disease initiated by the infiltration of autoreactive T cells into the central nervous system (CNS). Several molecules that modulate T cell CNS infiltration in MS have been identified, but how the components of cell adhesion, migration and signalling pathways interact to execute this fundamental step in MS pathogenesis is unknown. We conducted a genome-wide in vivo CRISPR screen in an experimental autoimmune encephalomyelitis model of MS and identified 18 essential facilitators of T cell migration that include known targets of MS therapies. Combining in vitro studies with in vivo cell transfer and multiphoton microscopy enabled us to reveal three functional modules, centred around the adhesion molecule 4-integrin, the chemokine receptor CXCR3, and the GRK2 kinase, that are required for the migration of autoreactive CD4+ T cells into the CNS. Single-cell analysis of T cells from patients with MS confirmed that the expression of the essential regulators correlates with the propensity of CD4+ T cells to reach the CNS. Taken together, our data reveal the identity and functions of key modules that govern the critical step in the induction of MS lesions.

immunology↗

bioRxiv2019

Localized calcium accumulations prime synapses for phagocyte removal in cortical neuroinflammation

Cortical pathology contributes to chronic cognitive impairment of patients suffering from the neuroinflammatory disease multiple sclerosis (MS). How such gray matter inflammation affects neuronal structure and function is not well understood. Here we use functional and structural in vivo imaging in a mouse model of cortical MS to demonstrate that bouts of cortical inflammation disrupt cortical circuit activity coincident with a widespread but transient loss of dendritic spines. Spines destined for removal show a local calcium accumulation and are subsequently removed by invading macrophages and activated microglia. Targeting phagocyte activation with a new antagonist of the colony-stimulating factor 1 receptor prevents cortical synapse loss. Overall, our study identifies synapse loss as a key pathological feature of inflammatory gray matter lesions that is amenable to immunomodulatory therapy.\n\nHIGHLIGHTSO_LIWidespread, but transient loss of synapses in inflammatory lesions and beyond\nC_LIO_LIReversible impairment of neuronal firing and circuit function in the inflamed cortex\nC_LIO_LICalcium dyshomeostasis of single spines precedes swift synapse loss\nC_LIO_LIPhagocyte-mediated spine pruning as targetable mechanism of synapse loss\nC_LI

neuroscience↗

bioRxiv2018

Phenotypic and genotypic resistance to commonly used insecticides in Aedes aegypti among four cities in southern Ecuador

Insecticide resistance (IR) can undermine efforts to control vector species of public health importance. Aedes aegypti is the main vector of resurging diseases in the Americas such as yellow fever and dengue, as well as recently emerging chikungunya and Zika viruses, which have caused unprecedented epidemics in the region. Vector control remains the primary public health intervention to prevent outbreaks of Aedes transmitted diseases. In many high-risk regions, like southern Ecuador, we have limited information on IR in Ae. aegypti. In this study, IR status in Ae. aegypti was measured across four cities in El Oro Province in Ecuador using phenotypic assays and genetic screening for alleles associated with resistance to pyrethroid insecticides. Bottle bioassays showed significant inter-seasonal variation in resistance to deltamethrin, a pyrethroid insecticide commonly used by the Ministry of Health, and alpha cypermethrin, as well as differences in deltamethrin resistance between cities. There was also a significant difference in phenotypic response to the organophosphate, Malathion, between two of the cities during the second sampling season. Genotyping showed moderate to high frequencies of the V1016I and F1534C resistance alleles in all four cites. Frequency of resistance genotypes varied significantly between cities in the first sampling season, and not in the later seasons, suggesting a possible selective response to vector control activity. Overall, resistance levels were highest in Machala, a city where dengue is hyperendemic and where insecticide use has historically been more intense than in the other cities included in the study. Despite statistically significant evidence that resistance alleles conferred phenotypic resistance, there was not precise correspondence between these indicators. We found that 17.6% of F1534C and 45.6% of V1016I mutant mosquitoes were susceptible in the bottle bioassays. This study shows there is spatiotemporal variability in IR in southern Ecuador, and serves as an initial examination of the genotypic and phenotypic indicators of IR in this region, providing important information to guide the vector control interventions by the public health sector.

epidemiology↗

bioRxiv2018

DNA methylation signatures of a large cohort monozygotic twins clinically discordant for multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system with a modest concordance rate in monozygotic twins that strongly argues for involvement of epigenetic factors. We observe in 45 MS discordant monozygotic twins highly similar peripheral blood mononuclear cell-based methylomes. However, a few MS-associated differentially methylated positions (DMP) were identified and validated, including a region in the TMEM232 promoter and ZBTB16 enhancer. In CD4+ T cells we observed an MS-associated differentially methylated region in FIRRE. In addition, many regions showed large methylation differences in individual pairs, but were not clearly associated with MS. Furthermore, epigenetic biomarkers for current interferon-beta treatment were identified, and extensive validation revealed the ZBTB16 DMP as a signature of prior glucocorticoid treatment. Altogether, our study represents an important reference for epigenomic MS studies. It identifies new candidate epigenetic markers, highlights treatment effects and genetic background as major confounders, and argues against some previously reported MS-associated epigenetic candidates.

genomics↗