Biology subjects

Madsen, K.

Publications and source records attributed to Madsen, K..

4 recordsLinked to original sources

bioRxiv2026

Selective targeting of the oligodendroglial GPR17 receptor improves myelin integrity and motor function in female SOD1G93A mice

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with no definitive disease-modifying therapies available, underscoring the urgent need to identify novel druggable targets. The G protein-coupled receptor GPR17 is a critical regulator of oligodendrocyte maturation and has emerged as a candidate target in ALS, yet its relevance to human disease and its therapeutic potential remain unclear. Here, we demonstrate that pathological GPR17 upregulation defines a conserved, pathologically immature oligodendroglial state in human ALS that can be pharmacologically leveraged to restore myelin integrity and improve functional outcome in vivo. Publicly available transcriptomics datasets and histological analyses revealed an increased abundance of GPR17-expressing immature oligodendrocytes in post-mortem human spinal cord tissue from ALS cases. Moreover, sustained activation of GPR17 with a selective agonist induced GPR17 internalization in heterologous expression systems and promoted the differentiation of primary oligodendrocyte precursors derived from SOD1G93A mice. Translating these findings in vivo, chronic treatment with a brain-penetrant GPR17 agonist derived from the same pharmacological class significantly extended survival, delayed body weight loss, and improved motor performance in female SOD1G93A mice, whereas male mice showed no therapeutic benefit. These effects were associated with restored oligodendrocyte maturation, preserved myelin integrity, motor neuron survival, and attenuated reactive gliosis in the spinal cord of female SOD1G93A mice, while milder effects were observed in males. Together, these findings establish oligodendroglial GPR17 as a conserved and pharmacologically actionable target in ALS and show that sustained in vivo GPR17 agonism can reprogram altered oligodendroglial states and slow disease progression in a sex-dependent manner.

pharmacology and toxicology↗

bioRxiv2026

Human airway model reveals host-pathogen co-infection dynamics of Staphylococcus aureus and Pseudomonas aeruginosa

Polymicrobial airway infections, particularly those involving Staphylococcus aureus and Pseudomonas aeruginosa, are a hallmark of severe chronic respiratory diseases such as those in people with cystic fibrosis (pwCF). Yet, the mechanisms enabling their co-existence remain poorly understood. Using a human air-liquid interface (ALI) airway model, we dissected host-pathogen and interspecies dynamics during mono- and co-infections with clinically relevant bacterial pathogens. We found that S. aureus strains exhibited distinct colonization patterns and virulence profiles, with the deletion of the agr quorum sensing locus leading to attenuated epithelial disruption. Additionally, the H1 component of P. aeruginosas type VI secretion system was critical for competitive exclusion of S. aureus, its deletion allowing for occasional co-localization of both species. Importantly, co-infection timing strongly influenced pathogen dominance and epithelial damage, with pre-colonization of ALI models with S. aureus prior to P. aeruginosa infection, mimicking clinical observations in CF. Our results reveal that strain-specific traits and secretion systems influence microbial competition and persistence in the airway and underscore the importance of physiologically relevant models for studying chronic infections. Moreover, they provide the foundation for exploring therapeutic strategies for polymicrobial infections that account for the colonization sequence and microbial evolution for treatment design.

microbiology↗

bioRxiv2023

Mouse mammary tumor virus is implicated in severity of colitis and dysbiosis in the IL-10-/- mouse model of inflammatory bowel disease

BackgroundFollowing viral infection, genetically manipulated mice lacking immunoregulatory function may develop colitis and dysbiosis in a strain specific fashion that serves as a model for inflammatory bowel disease (IBD). We found that one such model of spontaneous colitis, the interleukin (IL)-10 knockout (IL-I0-/-) model derived from the SvEv mouse, had evidence of increased mouse mammary tumor virus (MMTV) viral RNA expression compared to the SvEv wildtype. MMTV is endemic in several mouse strains as an endogenously encoded betaretrovirus that is passaged as an exogenous agent in breast milk. As MMTV requires a viral superantigen to replicate in the gut associated lymphoid tissue prior to the development of systemic infection, we evaluated whether MMTV may contribute to the development of colitis in the IL-10-/- model. ResultsViral preparations extracted from IL-10-/- weanling stomachs revealed augmented MMTV load compared to the SvEv wildtype. Illumina sequencing of the viral genome revealed that the two largest contigs shared 96.4% - 97.3% identity with the mtv-1 endogenous loci and the MMTV(HeJ) exogenous virus from the C3H mouse. The MMTV sag gene cloned from IL-10-/- spleen encoded the MTV-9 superantigen that preferentially activates T cell receptor V{beta}-12 subsets, which were expanded in the IL-10-/- versus the SvEv colon. Evidence of MMTV cellular immune responses to MMTV Gag peptides was observed in the IL-10-/- splenocytes with amplified interferon-{gamma} production versus the SvEv wildtype. To address the hypothesis that MMTV may contribute to colitis, we used HIV reverse transcriptase inhibitors, tenofovir and emtricitabine, and the HIV protease inhibitor, lopinavir boosted with ritonavir, for 12 weeks treatment versus placebo. The combination anti-retroviral therapy with known activity against MMTV was associated with reduced colonic MMTV RNA and improved histological score in IL10-/- mice, as well as diminished secretion of pro-inflammatory cytokines and modulation of the microbiome associated with colitis. ConclusionsThis study suggests that immunogenetically manipulated mice with deletion of IL-10 may have reduced capacity to contain MMTV infection in a mouse-strain specific manner, and the antiviral inflammatory responses may contribute to the complexity of IBD with the development of colitis and dysbiosis.

microbiology↗

bioRxiv2018

Reward signalling in brainstem nuclei under glycemic flux

Phasic dopamine release from mid-brain dopaminergic neurons signals errors of reward prediction (RPE). If reward maximisation is to maintain homeostasis, then the value of primary rewards should be coupled to the homeostatic errors they remediate. This leads to the prediction that RPE signals should be configured as a function of homeostatic state and thus, diminish with the attenuation of homeostatic error. To test this hypothesis, we collected a large volume of functional MRI data from five human volunteers on four separate days. After fasting for 12 hours, subjects consumed preloads that differed in glucose concentration. Participants then underwent a Pavlovian cue-conditioning paradigm in which the colour of a fixation-cross was stochastically associated with the delivery of water or glucose via a gustometer. This design afforded computation of RPE separately for better- and worse-than expected outcomes during ascending and descending trajectories of physiological serum glucose fluctuations. In the parabrachial nuclei, variations in regional activity coding positive RPEs scaled positively with serum glucose for ascending and descending glucose levels. The ventral tegmental area and substantia nigra became more sensitive to negative RPEs when glucose levels were ascending. Together, the results show that RPE signals in key brainstem structures are modulated by homeostatic trajectories of naturally occurring glycemic flux, revealing a tight interplay between homeostatic state and the neural encoding of primary reward in the human brain.

neuroscience↗