Biology subjects

Boesmans, W.

Publications and source records attributed to Boesmans, W..

7 recordsLinked to original sources

bioRxiv2026

Adrenergic signaling induces a pro-tumorigenic B cell state in colorectal cancer

The importance of neuron-tumor crosstalk has gained increasing attention, yet its influence on the cellular and molecular landscape of colorectal cancer (CRC) remains largely unexplored. Here, we show that colonic innervation shapes the tumor immune microenvironment in a murine model of colitis-associated CRC. Although neuronal density does not affect tumor number, size, or overall burden, transcriptomic profiling of cells isolated from the tumor of hypo-innervated mice revealed extensive differential gene expression, including genes involved in immunoglobulin (Ig) signaling and the cancer-relevant hallmark avoiding immune destruction. Flow cytometry analysis of leukocyte populations demonstrated a significant reduction of B cells in the cancerous colon of hypo-innervated mice, notably a decrease in germinal center B cells and an altered class-switching profile, characterized by reduced IgA and increased IgD expression. Fluorescence and transmission electron microscopy showed that colonic B cells are primarily localized in the submucosa near neuronal processes containing varicose release sites, suggesting direct neuron-B cell interactions. Functional assays revealed that adrenergic stimulation of B cells promotes their proliferation and maturation, enhances IL-10 secretion, and alters immunoglobulin profiles. Strikingly, the transcriptome of epinephrine-treated B cells closely mirrors that of plasma cells from human CRC tissues, and the transcriptomic signature of these epinephrine-stimulated B cells associates with poorer patient survival. Together, these findings uncover an adrenergic neuron - B cell axis in CRC, providing evidence for direct neuroimmune interactions that affect B cell maturation and may influence tumor progression and therapeutic responses.

cancer biology↗

bioRxiv2023

Human enteric glia diversity in health and disease: new avenues for the treatment of Hirschsprung disease

Hirschsprung disease (HSCR) is caused by an absence of the enteric nervous system (ENS), which is crucial for intestinal function. The ENS is composed of enteric neurons and glia, and is mostly derived from migrating vagal neural crest cells. Trunk-derived Schwann cells also play a significant role in postnatal maintenance of the ENS. However, the diversity of the ENS in health and disease remains largely unknown. Here, we performed single cell RNA sequencing on pediatric controls and HSCR individuals, and identified two major classes of enteric glia, being canonical and Schwann-like enteric glia. We show that the latter are the main contributors of enteric glia heterogeneity after birth and importantly, that they are preserved in aganglionic segments of HSCR individuals. In a zebrafish model of HSCR, which also shows preservation of Schwann-like enteric glia, enteric neurogenesis could be stimulated, demonstrating a potential novel therapy for HSCR.

pathology↗

bioRxiv2023

D-Serine agonism of GluN1-GluN3 NMDA receptors regulates the activity of enteric neurons and coordinates gut motility

The enteric nervous system (ENS) is a complex network of diverse molecularly defined classes of neurons embedded in the gastrointestinal wall and responsible for controlling the major functions of the gut. As in the central nervous system, the vast array of ENS neurons is interconnected by chemical synapses. Despite several studies reporting the expression of ionotropic glutamate receptors in the ENS, their roles in the gut remain elusive. Here, by using an array of immunohistochemistry, molecular profiling and functional assays, we uncover a new role for D-serine (D-Ser) and non-conventional GluN1-GluN3 N-methyl D-aspartate receptors (NMDARs) in regulating ENS functions. We demonstrate that D-Ser is produced by serine racemase (SR) expressed in enteric neurons. By using both in situ patch clamp recording and calcium imaging, we show that D-Ser alone acts as an excitatory neurotransmitter in the ENS independently of the conventional GluN1-GluN2 NMDARs. Instead, D-Ser directly gates the non-conventional GluN1-GluN3 NMDARs in enteric neurons from both mouse and guinea-pig. Pharmacological inhibition or potentiation of GluN1-GluN3 NMDARs had opposite effects on mouse colonic motor activities, while genetically driven loss of SR impairs gut transit and fluid content of pellet output. Our results demonstrate the existence of native GluN1-GluN3 NMDARs in enteric neurons and open new perspectives on the exploration of excitatory D-Ser receptors in gut function and diseases.

neuroscience↗

bioRxiv2021

Luminal nutrients activate distinct patterns in submucosal and myenteric neurons in the mouse small intestine

Nutrient signals sensed by enteroendocrine cells are conveyed to the enteric nervous system (ENS) to initiate intestinal reflexes. We addressed whether there are specific enteric pathways dedicated to detecting different luminal nutrients. Calcium imaging was performed on intact jejunal preparations from Wnt1-cre;R26R-GCaMP3 and Villin-cre;R26R-GCaMP3 mice which express a fluorescent calcium indicator in their ENS or intestinal epithelium, respectively. Glucose, acetate, and L-phenylalanine were perfused onto the mucosa whilst imaging underlying enteric neurons. Nutrient transport or diffusion across the mucosa was mimicked by applying nutrients onto sensory nerve endings in a villus, or onto myenteric ganglia. The nutrients perfused onto the mucosa each elicited Ca2+ transients in submucosal neurons and in distinct patterns of myenteric neurons. Notably, the neurochemical subtypes of myenteric neurons that responded differed between the nutrients, while submucosal responders were predominantly cholinergic. Nutrients applied into villi or onto ganglia did not elicit specific neuronal responses but did stimulate Ca2+ signaling in the mucosal epithelium. These data suggest that nutrients are first detected at the level of the epithelium and that the ENS is capable of discriminating between different compositions of luminal content. Furthermore, our data show that responses to mucosal stimulation are primarily in the myenteric plexus and submucosal neurons respond secondarily.

neuroscience↗

bioRxiv2020

Extracting neuronal activity signals from microscopy recordings of contractile tissue: a cell tracking approach using B-spline Explicit Active Surfaces (BEAS)

Ca2+ imaging is a widely used microscopy technique to simultaneously study cellular activity in multiple cells. The desired information consists of cell-specific time series of pixel intensity values, in which the fluorescence intensity represents cellular activity. For static scenes, cellular signal extraction is straightforward, however multiple analysis challenges are present in recordings of contractile tissues, like those of the enteric nervous system (ENS). This layer of critical neurons, embedded within the muscle layers of the gut wall, shows optical overlap between neighboring neurons, intensity changes due to cell activity, and constant movement. These challenges reduce the applicability of classical segmentation techniques and traditional stack alignment and regions-of-interest (ROIs) selection workflows. Therefore, a signal extraction method capable of dealing with moving cells and is insensitive to large intensity changes in consecutive frames is needed. Here we propose a b-spline active contour method to delineate and track neuronal cell bodies based on local and global energy terms. We develop both a single as well as a double-contour approach. The latter takes advantage of the appearance of GCaMP expressing cells, and tracks the nucleus boundaries together with the cytoplasmic contour, providing a stable delineation of neighboring, overlapping cells despite movement and intensity changes. The tracked contours can also serve as landmarks to relocate additional and manually-selected ROIs. This improves the total yield of efficacious cell tracking and allows signal extraction from other cell compartments like neuronal processes. Compared to manual delineation and other segmentation methods, the proposed method can track cells during large tissue deformations and high-intensity changes such as during neuronal firing events, while preserving the shape of the extracted Ca2+ signal. The analysis package represents a significant improvement to available Ca2+ imaging analysis workflows for ENS recordings and other systems where movement challenges traditional Ca2+ signal extraction workflows.

neuroscience↗

bioRxiv2020

Nano-positioning and tubuline conformation determine transport of mitochondria along microtubules

Correct spatiotemporal distribution of organelles and vesicles is crucial for healthy cell functioning and is regulated by intracellular transport mechanisms. Controlled transport of bulky mitochondria is especially important in polarized cells such as neurons that rely on these organelles to locally produce energy and buffer calcium. Mitochondrial transport requires and depends on microtubules which fill much of the available axonal space. How mitochondrial transport is affected by their position within the microtubule bundles is not known. Here, we found that anterograde transport, driven by kinesin motors, is susceptible to the molecular conformation of tubulin both in vitro and in vivo. Anterograde velocities negatively correlate with the density of elongated tubulin dimers, similar to GTP-tubulin, that are more straight and rigid. The impact of the tubulin conformation depends primarily on where a mitochondrion is positioned, either within or at the rim of microtubule bundle. Increasing elongated tubulin levels lowers the number of motile anterograde mitochondria within the microtubule bundle and increases anterograde transport speed at the microtubule bundle rim. We demonstrate that the increased kinesin step processivity on microtubules consisting of elongated dimers underlies increased mitochondrial dynamics. Our work indicates that the molecular conformation of tubulin controls mitochondrial motility and as such locally regulates the distribution of mitochondria along axons.

neuroscience↗

bioRxiv2019

Neuronal programming by microbiota enables environmental regulation of intestinal motility

Environmental signals modulate the activity of the nervous system and harmonize its output with the outside world. Synaptic activity is crucial for integrating sensory and effector neural pathways but the role of transcriptional mechanisms as environmental sensors in the nervous system remains unclear. By combining a novel strategy for transcriptomic profiling of enteric neurons with microbiota manipulation, we demonstrate that the transcriptional programs of intestinal neural circuits depend on their anatomical and physiological context. We also identify the ligand-dependent transcription factor Aryl hydrocarbon Receptor (AhR) is an intrinsic regulator of enteric nervous system output. AhR is instated as a neuronal biosensor in response to microbiota colonization allowing resident enteric neurons to directly monitor and respond to the intestinal microenvironment. We suggest that AhR signaling integrates neuronal activity with host defence mechanisms towards gut homeostasis and health.\n\nOne Sentence SummaryMicrobiota induce expression of AhR in enteric neurons of the distal intestine enabling them to respond to environmental signals.

neuroscience↗