Biology subjects

Schmidt, Y.

Publications and source records attributed to Schmidt, Y..

3 recordsLinked to original sources

bioRxiv2025

The nuclear receptor NR4A1 serves as a neutrophil-intrinsic regulator mitigating stroke severity

Ischemic stroke is accompanied by recruitment and activation of immune cells which play an important role in the progression of the brain damage. The nuclear receptor NR4A1 emerged as a key regulator within the inflammatory response of several immune diseases by regulating immune cell activation. In this study, we investigated the role of NR4A1 in the activation and recruitment of brain resident and peripheral immune cells after cerebral ischemia. Here, we show that NR4A1 mediates an anti-inflammatory and damage-limiting effect after stroke. This effect is largely mediated by neutrophil recruitment and importantly, NR4A1 activation with its ligand Cytosporone B improves functional outcome and reduces brain damage. Modulation of NR4A1 is therefore a promising therapeutic target for the treatment of the nuclear receptor NR4A1 in the activation and recruitment of peripheral and brain resident immune cells after cerebral ischemia and its consequences for stroke outcome. We demonstrate that NR4A1 ablation augments neutrophil activation and CNS recruitment within days after stroke thereby increasing infarct size, CNS inflammation, neuronal damage and deteriorating functional outcome. This effect is mediated via modulation of cell-intrinsic neutrophil function and maturation as illustrated by neutrophil-specific NR4A1 ablation and mixed bone-marrow chimera experiments. Notably, the NR4A1 agonist Cytosporone B reduced CNS neutrophil infiltration, infarct size and functional outcome after stroke in a bicentric preclinical stroke trial, demonstrating that NR4A1-mediated control of neutrophil reactivity is amenable to pharmacological modulation. In humans, NR4A1 expressing neutrophils are present in the peripheral blood of stroke patients and neutrophil NR4A1 expression correlates with improved long-term outcome after 3 months. Furthermore, NR4A1 expression in brain parenchyma neutrophils is negatively correlated with neuronal cell loss, illustrating a role of NR4A1 in regulating neutrophil mediated neuronal cell death in human stroke. Together our data reveal the nuclear factor NR4A1 as a brake of intrinsic neutrophil activity controlling neutrophil-mediated brain inflammation and neurotoxicity in stroke which may serve as a novel therapeutic target to limit inflammation-associated augmentation of ischemic damage after stroke.

neuroscience↗

bioRxiv2024

The expression patterns of different cell types and their interactions in the tumor microenvironment are predictive of breast cancer patient response to neoadjuvant chemotherapy

The tumor microenvironment (TME) is a complex ecosystem of diverse cell types whose interactions govern tumor growth and clinical outcome. While multiple studies have extensively charted the TMEs impact on immunotherapy, its role in chemotherapy response remains less explored. To address this, we developed DECODEM (DEcoupling Cell-type-specific Outcomes using DEconvolution and Machine learning), a generic computational framework leveraging cellular deconvolution of bulk transcriptomics to associate gene expression of individual cell types in the TME with clinical response. Employing DECODEM to analyze gene expression of breast cancer patients treated with neoadjuvant chemotherapy across three bulk cohorts, we find that the expression of specific immune cells (myeloid, plasmablasts, B-cells) and stromal cells (endothelial, normal epithelial, CAFs) are highly predictive of chemotherapy response, achieving the same prediction levels as the expression of malignant cells. Notably, ensemble models integrating the estimated expression of different cell types perform best and outperform models built on the original tumor bulk expression. These findings and the models generalizability are further tested and validated in two single-cell (SC) cohorts of triple negative breast cancer. To investigate the possible role of immune cell-cell interactions (CCIs) in mediating chemotherapy response, we extended DECODEM to DECODEMi to identify such key functionally important CCIs, validated in SC data. Our findings highlight the importance of active pre-treatment immune infiltration for chemotherapy success. DECODEM and DECODEMi are made publicly available to facilitate studying the role of the TME in mediating response in a wide range of cancer indications and treatments.

bioinformatics↗

bioRxiv2020

The scar constituent Collagen I triggers coordinated collective migration and invasion in a 3D spheroid model of early endometriotic lesions

Endometriosis is a painful gynaecological condition characterized by ectopic growth of endometrial cells outside of the uterus. Little is known about the mechanisms by which endometrial fragments invade tissues. This is partially due to a lack of suitable experimental models. In this study, we show that a spheroid 3D model, but not single cells mimic the collective endometrial fragment-like invasion through the extracellular matrix. This model reveals that collagen I, the main constituent of surgical scars, significantly increases the rate of lesion formation by healthy endometrial stromal cells (St-T1b) in vitro compared to the basement membrane-like matrix Matrigel. Stromal cell invasion of collagen I requires MMPs, whereas collective migration of endometriotic epithelial 12Z cells involves Rac-signalling. We show that inhibiting ROCK signalling responsible for actomyosin contraction increases the lesion-size. Moreover, endometriotic epithelial 12Z cells, but not eutopic stromal cells St-T1b migrate on Matrigel. The rate of this migration is decreased by the microRNA miR-200b and increased by miR-145. Our 3D model offers a facile approach to dissect how endometrial fragments invade tissues and is an important step toward developing new personalized therapeutics for endometriosis. Moreover, our model is a suitable tool to screen small molecule drugs and microRNA-based therapeutics.

bioengineering↗