Biology subjects

Dedden, M.

Publications and source records attributed to Dedden, M..

3 recordsLinked to original sources

bioRxiv2026

Csf1r-mediated depletion of midbrain microglia prevents dopaminergic neuron loss during chronic colitis

Inflammatory bowel disease (IBD) predisposes to neuropsychiatric comorbidity and particularly increases the risk of Parkinsons Disease (PD) in later life. Although the gut-immune-brain axis was proposed as a link between IBD and PD and a driver of PD immunopathogenesis, the regional pattern and single-cell landscape of the brain immune response during colitis and its contribution to PD pathology remain poorly defined. Here, we observe a loss of dopaminergic neurons in the substantia nigra pars compacta of adult mice with chronic colitis. By confocal microscopy and integrated multi-omics, we reveal a complex midbrain-centered immune response to chronic colitis in comparison to the cortex, hippocampus, and striatum. Single-cell mapping of the midbrain immune landscape showed an inflammatory shift of microglial clusters including an expansion of interferon-response microglia, CD8+ T cell extravasation, and increased numbers of vessel-associated neutrophils. Selective myeloid cell depletion using a colony stimulating factor 1 receptor (Csf1r) inhibitor after colitis onset reduced midbrain microglia by 67% and led to a complete rescue of dopaminergic neuron loss, without affecting mucosal pathology or T cell and neutrophil migration to the midbrain. Collectively, within the complex innate and adaptive midbrain immune response to chronic colitis, we demonstrate a causal role of Csf1r-dependent microglia for dopaminergic neurodegeneration. Thus, Csf1r inhibition in IBD may not locally ameliorate colitis, but provide neuroprotection to dopaminergic neurons. These results reveal a novel cellular link between chronic gut-derived peripheral inflammation and midbrain vulnerability and thereby substantially enhance our understanding of the risk for PD related to the gut-immune-brain axis. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=174 SRC="FIGDIR/small/700559v1_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@1bf7217org.highwire.dtl.DTLVardef@1db66c0org.highwire.dtl.DTLVardef@136ef2eorg.highwire.dtl.DTLVardef@190f641_HPS_FORMAT_FIGEXP M_FIG Graphical abstract. C_FIG

neuroscience↗

bioRxiv2025

Single-cell dissection of urine-derived stem cell hierarchies reveals robust chondrogenesis and clinical scalability

Developing of models of human cartilage and bone growth is essential for the study of growth disorders and to advance towards personalized therapeutic interventions. The majority of in vitro strategies depend on the use of invasively obtained mesenchymal stem cells (MSCs) or the laborious generation of induced pluripotent stem cells (iPSCs). We have now established urine-derived stem cells (USCs) as a non-invasive stem cell source capable of osteogenic and robust chondrogenic spheroid differentiation. Single-cell RNA sequencing of USCs revealed a hierarchy originating from parietal epithelial cells of the kidney, with a proliferative TOP2A subpopulation governed by MYC and E2F4 regulatory networks. Pseudo-time analysis of chondrogenic USCs uncovered alternative chondrogenic differentiation trajectories with an ALDH1A2 intermediate state and a TIMP3-expressing chondrocyte-like subpopulation as the major endpoint, exhibiting cartilage-specific gene ontologies. In conclusion, a streamlined, xeno-free culture and differentiation protocol was developed, thereby establishing the basis for clinical-grade cell expansion and cartilage matrix formation. This positions USCs as a powerful tool for studying cartilage biology and a potential platform for development and use in regenerative therapies.

genetics↗

bioRxiv2019

CRISPR-Cas9 mediated genome editing in vancomycin resistant Enterococcus faecium

The Gram-positive bacterium Enterococcus faecium is becoming increasingly prevalent as a cause of hospital-acquired, antibiotic-resistant infections. There is thus an urgent need to mechanistically characterize the traits that contribute to the emergence of E. faecium as a multidrug resistant opportunistic pathogen. A fundamental part of research into E. faecium biology relies on the ability to generate targeted mutants, but this process is currently labour-intensive and time-consuming, taking 4 to 5 weeks per mutant. In this report we describe a method relying on the high recombination rates of E. faecium and the application of the Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-Cas9 genome editing tool to more efficiently generate targeted mutants in the E. faecium chromosome. Using this tool and the multi-drug resistant clinical E. faecium strain E745, we generated a deletion mutant in the lacL gene, which encodes the large subunit of the E. faecium {beta}-galactosidase. Blue/white screening using 5-bromo-4-chloro-3-indolyl-{beta}-D-galactopyranoside (X-gal) could be used to distinguish between the wild-type and lacL deletion mutant. We also inserted two copies of gfp into the intrinsic E. faecium macrolide resistance gene msrC to generate stable green fluorescent cells. We conclude that CRISPR-Cas9 can be used to generate targeted genome modifications in E. faecium in 3 weeks, with limited hands-on time. This method can potentially be implemented in other Gram-positive bacteria with high intrinsic recombination rates.

microbiology↗