Biology subjects

Mackenzie, C.

Publications and source records attributed to Mackenzie, C..

3 recordsLinked to original sources

bioRxiv2026

ACTIVATION OF THE ARYL HYDROCARBON RECEPTOR REDUCES VISCERAL HYPERSENSITIVITY IN A MOUSE MODEL OF COLITIS IN REMISSION

The aryl hydrocarbon receptor (AhR) is expressed on gut-projecting transient receptor potential vanilloid-1 (TRPV1)+ nociceptors, but whether it has a role in regulating abdominal pain remains to be determined. Approximately 50% of inflammatory bowel disease (IBD) patients experience chronic abdominal pain, even when their inflammatory disease is in remission. Previous work has shown that tryptophan metabolism to indole derivatives is reduced in IBD patients. Since microbial tryptophan metabolites (indole derivatives) serve as ligands for AhR, we hypothesized that reduced AhR activation contributes to enhanced pain sensitivity. We used a post-colitis mouse model of visceral hypersensitivity to examine the role of AhR as a mediator of nociception. AhR activation using both natural and synthetic agonists reduced visceral hypersensitivity in both male and female post-colitis mice. Conversely, pharmacological inhibition of AhR blocked the antinociceptive effects of indoles. Mechanistically, AhR activation by indole-3-pyruvic acid (IPyA) increased the transcription of the inward rectifying potassium channel Kir2.2, in TRPV1+ neurons and markedly reduced neuronal activation within the dorsal horn of the spinal cord. Metagenomic analysis revealed sex differences in indole-producing bacteria, with control males exhibiting enriched abundance of Akkermansia muciniphila and Alistipes compared to post-colitis males and female controls. These findings demonstrate that oral IPyA supplementation in post-colitis mice attenuates visceral hypersensitivity in part through activation of nociceptor AhR, providing insights that support the therapeutic targeting of AhR to treat abdominal pain in IBD patients in remission.

neuroscience↗

bioRxiv2025

SAMP-Score: A morphology-based machine learning classification method for screening pro-senescence compounds in p16 positive cancer cells

BackgroundSenescence identification is rendered challenging due to a lack of universally available biomarkers. This represents a bottleneck in efforts to develop pro-senescence therapeutics - agents designed to induce the arrest of cellular proliferation associated with a senescence response in cancer cells for therapeutic gain. This is particularly true in contexts such as basal-like breast cancer (BLBC), which often express high levels of widely reported senescence hallmarks, which has led to the designation of these subtypes as senescence marker positive (Sen-Mark+). Unfortunately, these are often cancers with the most limited treatment options, where novel pro-senescence compounds would be of potential clinical utility. ResultsTo address these challenges, we have developed SAMP-Score, a machine learning classification tool for identifying senescence induction in Sen-Mark+ cancers. This technique builds upon our previous observation that senescent cells develop distinct senescence-associated morphological profiles (SAMPs), which can be assessed readily in traditionally challenging contexts for senescence identification, including high-throughput screens. ConclusionsThrough application of SAMP-Score, we have identified QM5928, a novel pro-senescence compound, that is able to induce senescence in a variety of Sen-Mark+ cancers and has potential utility as a tool molecule to explore the mechanisms and pathways through which senescence induction occurs in these cells.

cancer biology↗

bioRxiv2025

Early-life gut microbiome and stress-axis perturbations dysregulate systemic, mucosal, and brain immunity

BackgroundEarly-life disruptions to the gut microbiome and stress-axis significantly influence the development of immune, neuroendocrine, and other physiological systems. However, the precise microbial species and pathways mediating these effects remain poorly characterized. Using a murine model, we investigated the individual and combined effects of early-life antibiotic exposure and chronic stress on gut microbiota composition, short-chain fatty acid (SCFA) production, hypothalamic-pituitary-adrenal (HPA) axis activity, and systemic, mucosal, and neuroimmune responses. ResultsBroad-spectrum antibiotic treatments severely reduced microbial diversity and SCFA concentrations, with changes persisting into adulthood. Chronic early-life stress exerted more modest but notable effects, reducing key SCFA-producing taxa and impacting microbiome metabolic output. Combined disruptions led to altered microglial active phenotype and cytokine profiles, impaired immune cell populations, and suppressed HPA axis activity. Multi-omic correlational analyses revealed strong associations between SCFAs, specific gut microbes, and immune responses, implicating SCFAs as critical mediators of gut-brain communication. Notably, antibiotic exposure exacerbated susceptibility to allergic airway inflammation, highlighting the systemic consequences of early-life microbiome disturbances. ConclusionsThese findings demonstrate that early microbial perturbations impair neuroimmune maturation, HPA axis regulation, and host resilience to inflammatory diseases. Our study underscores the importance of preserving the early-life microbiome to support long-term immune and neurodevelopmental health, offering insights into potential therapeutic interventions for mitigating the impact of early-life microbiota disruptions.

microbiology↗