Biology subjects

Caldwell, A.

Publications and source records attributed to Caldwell, A..

9 recordsLinked to original sources

bioRxiv2025

Integrated multiomics reveals inflammation-driven excessive erythrocytosis in subjects with Monge's disease

Monges disease, or Chronic Mountain Sickness (CMS), is a chronic high-altitude disorder characterized by hypoxia-induced excessive erythrocytosis (EE), elevating the risk of stroke and myocardial infarction. Using RNA-seq and ATAC-seq, we profiled iPSC-derived erythroid cells from CMS and non-CMS subjects under normoxia and hypoxia to identify statistically significant, disease-associated transcriptional and chromatin accessibility changes. RNA-seq revealed induction of inflammatory, stress, and erythropoiesis programs in CMS even under normoxia, including robust activation of JAK/STAT signaling, upregulation of heme metabolism and VEGF, and accelerated erythrocyte lineage commitment alongside repression of Notch and WNT/{beta}-catenin. Hypoxia amplified this dysregulated state, and critically, activated NF{kappa}B-driven inflammatory signaling together with canonical HIF targets. ATAC-seq revealed pronounced hypoxia-induced changes, with increased accessibility within inflammatory and erythrocyte lineage genes occurring concomitantly with decreased accessibility within pluripotency and ectodermal lineage genes. Pharmacological NF{kappa}B inhibition in CMS cells significantly reduced EE (p-value <0.0001), whereas NF{kappa}B activation in non-CMS cells was sufficient to drive EE (p-value <0.01), confirming the causal role inferred by our multiomics analyses. Collectively, our multiomics and functional experiments substantiate a coordinated chromatin-transcription paradigm favoring an inflammatory axis that, through hypoxia-driven NF{kappa}B activation, accelerates stress-induced erythroid commitment and underlies EE in CMS.

genetics↗

bioRxiv2025

Cellular and Immune Adaptations at the Maternal-Fetal Interface in Bats

Bats maintain pregnancy despite extended gestation relative to other small mammals, high fetal investment, recurrent pathogen exposure, and the metabolic demands of flight. These physiological extremes likely drive unique adaptations in placental function and maternal-fetal immune regulation, yet the cellular and molecular basis of these adaptations remains largely unknown. Here, we mapped the cellular landscape of the Jamaican fruit bat (Artibeus jamaicensis) placenta using single-nucleus RNA sequencing (snRNA-seq), integrated with histological and immunohistochemical analyses. We identified diverse trophoblast, stromal, and immune populations at the maternal-fetal interface, including specialized macrophages expressing pregnancy-associated signaling molecules. Trajectory analysis revealed dynamic trophoblast differentiation through proliferative, invasive, and syncytial states. To model these processes in vitro, we derived trophoblast and decidual gland organoids from matched tissues, which recapitulated key in vivo cell types and lineage trajectories. Cross-species transcriptomic comparisons with human and mouse placentas uncovered bat-specific gene programs in trophoblasts, fibroblasts, and immune cells. Notably, bat trophoblast organoids exhibited attenuated antiviral signaling compared to their human counterparts, suggesting species-specific modulation of innate immunity at the maternal-fetal interface. These findings define cellular strategies that support pregnancy under extreme physiological conditions and establish a framework for investigating the evolution of placental adaptations across mammals. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=111 SRC="FIGDIR/small/654282v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@12e7580org.highwire.dtl.DTLVardef@1245751org.highwire.dtl.DTLVardef@e0b9b0org.highwire.dtl.DTLVardef@1bf0694_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstract:C_FLOATNO Using single-nucleus RNA sequencing (snRNA-seq) and placental organoids, we reveal unique trophoblast differentiation, immune cell specialization, and expanded stromal populations in Jamaican fruit bat placentas. Cross-species comparisons underscore bat-specific evolutionary adaptations critical for sustaining pregnancy amid extreme metabolic and immunological challenges. C_FIG SummaryPregnancy in bats occurs under a combination of physiological stressors rarely encountered in other mammals, including extended gestation relative to other small mammals, elevated metabolic load, temperature fluctuations associated with flight, and constant microbial exposure. To investigate how the placenta adapts to these challenges, we profiled Jamaican fruit bat (Artibeus jamaicensis) placenta using single-nucleus RNA sequencing and tissue-derived organoid models. This analysis revealed diverse trophoblast, stromal, and immune cell populations with bat-specific transcriptional programs. We identified dynamic trophoblast differentiation trajectories, fibroblasts with hybrid adventitial-neuronal signatures, and macrophages expressing pregnancy-associated molecules typically restricted to trophoblasts. Cross-species comparisons with human and mouse placentas uncovered both conserved cell states and lineage-specific adaptations, providing insight into the evolution of placental function and immune regulation across mammals. HighlightsO_LISingle-nucleus RNA-seq defines cell types and differentiation pathways in the bat placenta C_LIO_LIBat trophoblast and decidua gland organoids recapitulate in vivo lineage trajectories and cell signatures C_LIO_LIBat-specific transcriptional programs revealed across trophoblast, stromal, and immune lineages C_LIO_LIBat trophoblasts exhibit attenuated antiviral responses compared to human counterparts C_LI

developmental biology↗

bioRxiv2024

Tissue Context Drives Regional Differences in Trophoblast Differentiation in Fetal Membranes and Chorionic Villi

Trophoblasts within the fetal membrane primarily serve as protective barriers, shielding the developing fetus from the external environment, while those in chorionic villi facilitate interactions between the maternal and fetal compartments. Although these distinct trophoblast populations perform specialized roles based on their placental location, the mechanisms governing their development and differentiation remain largely unknown. In this study, we derived trophoblast organoids from both the smooth chorion of fetal membranes and chorionic villi from matched human placentas to create parallel in vitro models of these distinct trophoblast populations. Using comparative transcriptional profiling with both bulk and single-cell RNA sequencing, we identified subtle transcriptional variations, while overall gene expression patterns and cellular composition remained highly conserved. Comparative single-cell RNA sequencing and differentiation trajectory analysis of organoids derived from chorion and villous tissues, along with their respective tissue counterparts, revealed region-specific gene expression patterns that were only partially conserved in organoids. The similarity between these in vitro models suggests that regional differences in trophoblast expression observed in vivo are driven by environmental and regional cues. These findings highlight the critical role of local environmental factors in shaping trophoblast function and offer insights into the conserved mechanisms that support placental integrity and fetal development, while emphasizing the influence of region-specific cues in vivo.

cell biology↗

bioRxiv2024

Defining Cellular Diversity at the Swine Maternal-Fetal Interface Using Spatial Transcriptomics and Organoids

The placenta is a dynamic, embryo-derived organ essential for fetal growth and development. While all eutherian mammals have placentas composed of fetal-derived trophoblasts that mediate maternal-fetal exchange, their anatomical and histological structures vary across species due to evolutionary divergence. Despite the cellular heterogeneity of porcine trophoblasts in vivo, understanding the mechanisms driving porcine placental development has been limited by the lack of in vitro models replicating this heterogeneity. In this study, we derived swine trophoblast organoids (sTOs) from full-term porcine placentas, retaining key transcriptional signatures of in vivo trophoblasts. To identify conserved cell populations, we integrated Visium spatial transcriptomics from mid-gestation porcine placentas with single-cell transcriptomics from sTOs. Spatial transcriptomics revealed novel markers of the porcine uterus and placenta, enabling precise separation of histological structures at the maternal-fetal interface. The integration of tissue and sTO transcriptomics showed that sTOs spontaneously differentiate into distinct trophoblast populations, with conserved gene expression and cell communication programs. These findings demonstrate that sTOs recapitulate porcine placental trophoblast populations, offering a powerful model for advancing placentation research. Our work also provides a spatially resolved whole-transcriptome dataset of the porcine maternal-fetal interface, opening new avenues for discoveries in placental development, evolution, and health across mammals.

developmental biology↗

bioRxiv2024

Comparative analysis of rhesus macaque and human placental organoids highlights evolutionary differences in placentation

Throughout evolution, the placenta has diversified in structure and cellular composition while maintaining its essential role in supporting fetal development. Trophoblasts, key cells responsible for nutrient exchange and immune modulation, are a conserved feature of all placentas. Although primate placentas share broad morphological similarities, species-specific differences in gene expression remain poorly characterized, largely due to the lack of tractable in vitro models. To address this gap, we developed rhesus macaque placental organoids representing both trophoblast and maternal-derived decidual cell types and compared them with human placental organoids. Using integrated single-cell and single-nucleus RNA sequencing, we identified both shared and species-specific transcriptional programs across corresponding trophoblast lineages. We further reconstructed lineage trajectories leading to multinucleated syncytiotrophoblast and invasive extravillous trophoblast populations, revealing conserved differentiation pathways alongside divergent gene expression signatures. This work establishes new in vitro models of the nonhuman primate placenta and defines the molecular distinctions between human and rhesus trophoblasts, offering insights into the evolutionary adaptations underlying placental development.

developmental biology↗

bioRxiv2024

ACAD10 and ACAD11 enable mammalian 4-hydroxy acid lipid catabolism

Fatty acid {beta}-oxidation (FAO) is a central catabolic pathway with broad implications for organismal health. However, various fatty acids are largely incompatible with standard FAO machinery until they are modified by other enzymes. Included among these are the 4-hydroxy acids (4-HAs)--fatty acids hydroxylated at the 4 ({gamma}) position--which can be provided from dietary intake, lipid peroxidation, and certain drugs of abuse. Here, we reveal that two atypical and poorly characterized acyl-CoA dehydrogenases (ACADs), ACAD10 and ACAD11, drive 4-HA catabolism in mice. Unlike other ACADs, ACAD10 and ACAD11 feature kinase domains N-terminal to their ACAD domains that phosphorylate the 4-OH position as a requisite step in the conversion of 4-hydroxyacyl-CoAs into 2-enoyl-CoAs--conventional FAO intermediates. Our ACAD11 cryo-EM structure and molecular modeling reveal a unique binding pocket capable of accommodating this phosphorylated intermediate. We further show that ACAD10 is mitochondrial and necessary for catabolizing shorter-chain 4-HAs, whereas ACAD11 is peroxisomal and enables longer-chain 4-HA catabolism. Mice lacking ACAD11 accumulate 4-HAs in their plasma while comparable 3- and 5-hydroxy acids remain unchanged. Collectively, this work defines ACAD10 and ACAD11 as the primary gatekeepers of mammalian 4-HA catabolism and sets the stage for broader investigations into the ramifications of aberrant 4-HA metabolism in human health and disease.

biochemistry↗

bioRxiv2021

Cytotoxicity mechanisms and composition of the glyphosate formulated herbicide RangerPro

Understanding the nature of co-formulants and toxic effects of major glyphosate-based herbicide (GBH) formulations is considered a research priority. Indeed, the toxicity of the co-formulants present in GBHs have been widely discussed and the European Union recently banned the co-formulant polyoxyethylene tallow amine (POEA). We provide a foundation for the development of new environmental epidemiological studies by reporting the presence of the most commonly used POEA, known as POE-15 tallow amine, in the widely used US GBH RangerPro. In order to understand if POE-15 tallow amine is present in RangerPro at a concentration at which it can exert toxic effects, we also tested the cytotoxicity of this GBH compared to glyphosate and POE-15 tallow amine in the human epithelial cell line Caco-2, a representative of the human intestinal epithelium, and the first to be exposed from the human diet to glyphosate herbicides. The lethal concentration 50 for each of these substances was 125 g/ml, 17200 g/ml, and 5.7 g/ml, for RangerPro, glyphosate and POE-15, respectively. The Caco-2 cell cytotoxicity assay indicated that RangerPro is more cytotoxic than glyphosate, suggesting that its toxicity can be due to the presence of the POE-15 surfactant. RangerPro and POE-15 tallow amine but not glyphosate exerted cell necrotic effects, but did not induce oxidative stress. We show that RangerPro contains POE-15 tallow amine at a concentration at which it could exert toxic effects, which offers a starting point for conducting surveys of co-formulant exposure in human populations.

pharmacology and toxicology↗

bioRxiv2020

Activation of MrgprA3 and MrgprC11 on bladder-innervating afferents induces peripheral and central hypersensitivity to bladder distension

Understanding the sensory mechanisms innervating the bladder is paramount to developing efficacious treatments for chronic bladder hypersensitivity conditions. The contribution of Mas-gene-related G protein-coupled receptors (Mrgpr) to bladder signalling is currently unknown. Here we show in mice with single-cell RT-PCR that sub-populations of dorsal root ganglion (DRG) neurons innervating the mouse bladder express MrgprA3 (14%) and MrgprC11 (38%), either individually or in combination, with high levels of co-expression with Trpv1 (81-89%). Calcium imaging studies demonstrated MrgprA3 and MrgprC11 agonists (chloroquine, BAM8-22 and neuropeptide FF) activated sub-populations of bladder-innervating DRG neurons, showing functional evidence of co-expression between MrgprA3, MrgprC11 and TRPV1. In ex vivo bladder-nerve preparations chloroquine, BAM8-22 and neuropeptide FF all evoked mechanical hypersensitivity in sub-populations (20-41%) of bladder afferents. These effects were absent in recordings from Mrgpr-cluster{Delta}-/- mice. In vitro whole-cell patch clamp recordings showed that application of an MrgprA3/C11 agonist cocktail induced neuronal hyper-excitability in 44% of bladder-innervating DRG neurons. Finally, in vivo instillation of an MrgprA3/C11 agonist cocktail into the bladder of wild-type mice induced a significant activation of dorsal horn neurons within the lumbosacral spinal cord, as quantified by pERK-immunoreactivity. This MrgprA3/C11 agonist-induced activation was particularly apparent within the superficial dorsal horn and the sacral parasympathetic nuclei of wild-type, but not Mrgpr-cluster{Delta}-/- mice. This study demonstrates, for the first time, functional expression of MrgprA3 and MrgprC11 in bladder afferents. Activation of these receptors is not required for normal bladder function but does trigger hypersensitivity to distension, a critically valuable factor for therapeutic target development. Significance statementDetermining how bladder afferents become sensitized is the first step in finding effective treatments for common urological disorders such as overactive bladder and interstitial cystitis/bladder pain syndrome. Here we show that two of the key receptors, MrgprA3 and MrgprC11, that mediate itch from the skin are also expressed on afferents innervating the bladder. Activation of these receptors results in sensitization of bladder afferents, resulting in sensory signals being sent into the spinal cord that prematurely indicate bladder fullness. Targeting bladder afferents expressing MrgprA3 or MrgprC11 and preventing their sensitisation may provide a novel approach for treating overactive bladder and interstitial cystitis/bladder pain syndrome.

neuroscience↗

bioRxiv2019

Convergence of glandular trichome morphology and chemistry in two montane monkeyflower species

Two distantly-related North American montane monkeyflower species, Mimulus lewisii and Mimulus tilingii, possess glandular trichomes. In this study, we characterized the morphological and histochemical features of these glandular trichomes. For each species, we used traditional light microscopy and scanning electron microscopy (SEM) to examine morphological characteristics, and determined the main components of the secretory products using histochemical and thin layer chromatography (TLC) staining techniques. We identified type VI glandular trichomes on leaf surfaces in both species of monkeyflowers. These trichomes exhibited stalk-cell lengths and head-cell counts that varied across adaxial and abaxial leaf surfaces, stems, and sepals. Both species contained secretory products within the cuticle of the trichome head, which releases the subcuticular metabolites when ruptured. Histochemical tests in both M. lewisii and M. tilingii confirmed that secretions contained lipids and polysaccharides. TLC plate staining indicated the presence of UV active compounds with polyalcohols, lipids, and amines. The common morphology and chemistry of the glandular trichomes suggests an analogous response to similar environmental conditions in these evolutionary distant montane monkeyflowers.

plant biology↗