Biology subjects

Grasso, C.

Publications and source records attributed to Grasso, C..

5 recordsLinked to original sources

bioRxiv2023

Senescence phenotype of lymph node stromal cells from patients with rheumatoid arthritis is partly restored by dasatinib treatment

ObjectiveCellular senescence is a state of proliferation arrest of cells occurring during aging. The persistence and accumulation of senescent cells has been implicated in the pathogenesis of age-related diseases like rheumatoid arthritis (RA). RA is a chronic autoimmune disease in which loss of immune tolerance and systemic autoimmunity precedes clinical onset of disease. Lymph node stromal cells (LNSCs) are important regulators of immune tolerance. Accordingly, accumulating senescent LNSCs may potentially lead to defective immune tolerance and the development of systemic autoimmune disease. MethodsHuman LNSCs were isolated and cultured from inguinal lymph node needle biopsies from individuals at risk of developing RA (RA-risk individuals), RA patients and seronegative healthy volunteers. Senescence hallmarks and the effect of dasatinib treatment were assessed using quantitative PCR, flow cytometry, microscopy and live-cell imaging. ResultsCell size, granularity and autofluorescence were significantly higher in RA LNSCs compared with control LNSCs. Stainings indicate more senescence associated {beta}-galactosidase activity, more lipofuscin positive granules and increased DNA damage in RA-risk and RA LNSCs compared with control LNSCs. Moreover, we found altered gene expression levels of senescence associated genes in LNSCs from RA patients. Strikingly, the capacity to repair irradiation induced DNA damage was significantly lower in RA-risk and RA LNSCs compared with control LNSCs. Treating LNSCs with dasatinib significantly improved cell size and DNA repair capacity of cultured LNSCs. ConclusionWe observed multiple senescent hallmarks in RA LNSCs and to lesser extent already in RA-risk LNSCs, which could partly be restored by dasatinib treatment. KEY MESSAGES What is already known on this topic?- Synovial fibroblasts from RA patients display a senescent phenotype and accumulate in inflamed synovial tissue. What does this study add?- Lymph node stromal cells (LNSCs) from RA patients, and to a lesser extent from RA-risk, display key hallmarks of senescence. - Both ex vivo and in vitro LNSCs from RA patients have an increased cell size compared with control LNSCs. - RA and RA-risk LNSCs have an impaired ability to repair DNA damage - Treating LNSCs with dasatinib significantly improved cell size and DNA repair capacity of LNSCs. How might this study impact on clinical practice or future developments?- These hallmarks of senescence in LNSCs may indicate premature aging and loss of function of the immunomodulatory lymph node stromal compartment during RA development. Dasatinib treatment of LNSCs shows that senolytics may be an effective preclinical drug to restore cell function early in disease.

cell biology↗

bioRxiv2023

SHIELD: Skull-shaped hemispheric implants enabling large-scale-electrophysiology datasets in the mouse brain

To understand the neural basis of behavior, it is essential to measure spiking dynamics across many interacting brain regions. While new technologies, such as Neuropixels probes, facilitate multi-regional recordings, significant surgical and procedural hurdles remain for these experiments to achieve their full potential. Here, we describe a novel 3D-printed cranial-replacement implant (SHIELD) enabling electrophysiological recordings from distributed areas of the mouse brain. This skull-shaped implant is designed with customizable insertion holes, allowing dozens of cortical and subcortical structures to be recorded in a single mouse using repeated multi-probe insertions over many days. We demonstrate the procedures high success rate, biocompatibility, lack of adverse effects on behavior, and compatibility with imaging and optogenetics. To showcase the scientific utility of the SHIELD implant, we use multi-probe recordings to reveal novel insights into how alpha rhythms organize spiking activity across visual and sensorimotor networks. Overall, this method enables powerful large-scale electrophysiological measurements for the study of distributed brain computation.

neuroscience↗

bioRxiv2023

Identification and mapping of human lymph node stromal cell subsets by combining single-cell RNA sequencing with spatial transcriptomics.

Lymph node stromal cells (LNSCs) have a crucial immunomodulatory function, but their heterogeneity in human is incompletely understood. Here, we report the single cell RNA sequencing (scRNA-seq) of 12000 LNSCs isolated from a human lymph node (LN). This study comprehensively defines the gene signatures of 10 fibroblast subtypes: CCL21+SC, CCL19+SC, CD34+CXCL14+SC, pericytes, DES+SC, LAMP5+SC, NR4A1+BCAM+ SC, HLA-DR+SC, SEPT4+SC and GLDN+SC. To explore the heterogeneous stromal compartment within the complex LN tissue architecture, we integrated the scRNA-seq profiles of the identified LNSC subsets with a publicly available human spatial transcriptomic LN dataset and predicted their location within the complex LN tissue architecture. Each LNSC subtype was spatially restricted to specific LN regions, indicating different LNSC-lymphocyte interactions which was further investigated using NicheNet. The positioning of distinct LNSC subtypes in different LN regions sets the stage for future research on the relationship between LNSC-specific niches and immunomodulatory function during health and disease.

cell biology↗

bioRxiv2023

Recurrent pattern completion drives the neocortical representation of sensory inference

When sensory information is incomplete or ambiguous, the brain relies on prior expectations to infer perceptual objects. Despite the centrality of this process to perception, the neural mechanism of sensory inference is not known. Illusory contours (ICs) are key tools to study sensory inference because they contain edges or objects that are implied only by their spatial context. Using cellular resolution, mesoscale two-photon calcium imaging and multi-Neuropixels recordings in the mouse visual cortex, we identified a sparse subset of neurons in the primary visual cortex (V1) and higher visual areas that respond emergently to ICs. We found that these highly selective IC-encoders mediate the neural representation of IC inference. Strikingly, selective activation of these neurons using two-photon holographic optogenetics was sufficient to recreate IC representation in the rest of the V1 network, in the absence of any visual stimulus. This outlines a model in which primary sensory cortex facilitates sensory inference by selectively strengthening input patterns that match prior expectations through local, recurrent circuitry. Our data thus suggest a clear computational purpose for recurrence in the generation of holistic percepts under sensory ambiguity. More generally, selective reinforcement of top-down predictions by pattern-completing recurrent circuits in lower sensory cortices may constitute a key step in sensory inference.

neuroscience↗

bioRxiv2023

Stimulus novelty uncovers coding diversity in visual cortical circuits

Detecting novel stimuli in the environment is critical for learning and survival, yet the neural basis of novelty processing is not understood. To characterize cell type-specific novelty processing, we surveyed the activity of [~]15,000 excitatory and inhibitory neurons in mice performing a visual task with novel and familiar stimuli. Clustering revealed a dozen functional neuron types defined by experience-dependent encoding. Vasoactive-intestinal-peptide (Vip) expressing inhibitory neurons were diverse, encoding novel stimuli, omissions of familiar stimuli, or behavioral features. Distinct Somatostatin (Sst) expressing inhibitory neurons encoded either familiar or novel stimuli. Subsets of excitatory neurons co-clustered with specific Vip or Sst subpopulations, while Sst and Vip inhibitory clusters were non-overlapping. This study establishes that novelty processing is mediated by diverse functional neuron types in the visual cortex.

neuroscience↗