Biology subjects

Bain, C.

Publications and source records attributed to Bain, C..

6 recordsLinked to original sources

bioRxiv2025

TWEAK is increased in ulcerative colitis and contributes to fibroblast-mediated monocyte activation via heterologous non-canonical NF-kB/STAT3 signalling

Background and AimsInteractions between fibroblasts and monocytes have emerged as a contributing factor in IBD pathogenesis and therapy resistance, owing to the ability of both cell types to participate in tissue inflammation and repair. We have previously shown that the TNF superfamily factor TWEAK (TNFSF12) can induce a UC-like inflammatory profile in colonic fibroblasts in vitro, in turn promoting monocyte adhesion and activation. However, the mechanisms underlying fibroblast-monocyte communication and its dysregulation in colitis are incompletely understood. MethodsHere we use co-culture models, human biopsies from ulcerative colitis (UC) patients and healthy donors, and public single-cell transcriptomics to characterise the mechanisms underlying fibroblast-mediated monocyte activation. ResultsWe show that TWEAK-treated inflammatory fibroblasts induce a transcriptional programme that resembles early monocyte/macrophage intermediates in UC and is enriched for genes associated with resistance to anti-TNF (TREM1, OSM, IL1B) and susceptibility to IBD (NOD2, ATG16L1). We find that conditioned media from TWEAK-treated fibroblast causes a sustained activation of STAT3 phosphorylation in monocytes, and that inhibition of the NF-{kappa}B Inducing Kinase (NIK) impairs the ability of inflammatory fibroblasts to activate STAT3 phosphorylation in monocytes, resulting in reduced expression of inflammatory mediators. Using tissues from UC patients, we show that the expansion of CD90+/PDPN+ inflammatory fibroblasts in UC correlates with the accumulation of TWEAK+ myeloid cells in the colonic mucosa, and that these fibroblasts co-localise with infiltrating monocytes in sites of active inflammation. ConclusionTogether, our findings suggest that the TWEAK/NF-{kappa}B/STAT3 axis represents an attractive target to tune inflammatory stroma/monocyte crosstalk.

immunology↗

bioRxiv2025

The synovial lining macrophage layer develops in the first weeks of life in a CSF1- and TGFβ- dependent but monocyte-independent process.

Synovial joints harbor a protective lining layer, consisting of fibroblasts and macrophages, which form an epithelial-like barrier. In inflamed joints, lining macrophages regulate both early inflammatory cell influx and resolution. Despite these critical functions, it is currently unknown at what stage during development the synovial macrophage lining is established, and which signals drive this process. Here, we use a combination of genetic models and in vivo perturbations, single cell transcriptomics and imaging to delineate the process of lining formation in mice. We find that the synovial lining is immature at birth and becomes established within the first 3 weeks of life. In this window, the lining is gradually populated with macrophages that originate from fetal sources, proliferate and acquire the lining-specific transcriptional identity. In contrast, monocytes contribute only minimally to the developing lining, and their input remains limited in healthy adulthood. We identify CSF1 and TGF{beta} as key signals in this process, which also involves mechanosensing through PIEZO1. Our study thus identifies the early postnatal window as a critical period for lining macrophage development, with potential lifelong impact on joint health and disease.

immunology↗

bioRxiv2024

Laminin 111 triggers cell quiescence and long-term survival by inducing IQGAP1-mediated cytosolic scaffolding of ERK and BAD inactivation

In an adult human body, only a minority ([~]1%) of cells are dividing; all others are either quiescent, senescent or terminally differentiated. Cellular quiescence, also called G0, is a reversible non-proliferative state in which cells, such as adult stem cells, exist until stimuli trigger their re-entry into the cell cycle. Quiescent cells are known to reside within microenvironment niches of specific extracellular matrix (ECM) composition, but the molecular mechanisms that control their entry and maintenance into G0 and their long-term survival are poorly understood. Here, using a reproducible and homogenous in vitro model of quiescence, ex vivo tissue histology, phosphoproteomics, and molecular cell biological assays, we revealed that Laminin 111 was sufficient to trigger i) reversible cell cycle exit into G0; ii) sustained and elevated MAPK/ERK signaling; and iii) long-term survival. We found that ERK was activated through the Rap1-BRAF-MEK arm underneath Laminin-binding Integrin 3{beta}1. Activated pERK was scaffolded into the cytoplasm by IQGAP1, thereby blocking its translocation into the nucleus and the activation of proliferative transcription factors. Instead, cytoplasmic pERK inhibited pro-apoptotic protein BAD, which mediated the survival of quiescent cells even in absence of mitogen stimuli. Importantly, we confirmed that pERK was elevated and retained in the cytoplasm of Lgr5+ stem cells when they were located within Laminin 1-positive niches in porcine intestine. These findings uncovered a molecular mechanism that may explain how quiescent cell pools, such as dormant adult stem cells, can survive many years despite low mitogen stimuli and be resistant to apoptotic challenges, including chemotherapy. HIGHLIGHTSO_LILaminin 111 is sufficient to induce cellular quiescence (G0) and long-term survival. C_LIO_LILaminin 111 triggers the sustained and elevated activation of ERK during G0. C_LIO_LIERK is activated not by growth factor receptors but through the Rap1-BRAF-MEK arm underneath Laminin-binding Integrin 3{beta}1. C_LIO_LIActive, phosphorylated ERK (pERK) is scaffolded by IQGAP1, which prevents it from translocating into the nucleus and activating proliferative transcription factors. C_LIO_LIInstead, cytoplasmic pERK mediates the phosphorylation, and thus inhibition, of BAD, thereby raising the threshold at which G0 cells enter apoptosis. C_LI

cell biology↗

bioRxiv2022

MC1R drives cutaneous repair by promoting angiogenesis and lymphangiogenesis

Cutaneous healing results in scarring with significant functional and psychological sequelae, while chronic non-healing wounds represent repair failure often with devastating consequences, including amputation and death. Due to a lack of effective therapies, novel interventions addressing scarring and chronic wounds are urgently needed. Here, we demonstrate that harnessing melanocortin 1 receptor with a selective agonist (MC1R-Ag) confers multifaceted benefits to wound repair. MC1R-Ag accelerates wound closure and re-epithelialization while improving wound bed perfusion and lymphatic drainage by promoting angiogenesis and lymphangiogenesis. Concomitant reductions in oxidative stress, inflammation and scarring were also observed. To evaluate the therapeutic potential of targeting MC1R in pathological healing, we established a novel murine model that recapitulates the hallmarks of human non-healing wounds. This model combines advanced age and locally elevated oxidative stress. Remarkably, topical application of MC1R-Ag restored repair, whereas disrupting MC1R signalling exacerbated the chronic wound phenotype. Our study highlights MC1R agonism as a promising therapeutic approach for scarring and non-healing wound pathologies, and our chronic wound model as a valuable tool for elucidating ulcer development mechanisms.

pathology↗

bioRxiv2020

No Relationship Between Perceived Health Anomalies and Perceived Experimental Success in Retired Breeder Male Hartley Albino Guinea Pigs

Guinea pigs used in our laboratory for cardiac research sometimes exhibit physical abnormalities. These issues may abate or intensify during the time they are housed in our facility. After using a guinea pig for research, experimentalists note the apparent health of an animal based on visible features and/or abnormal electrophysiology of the heart. There was an existing anecdotal observation that the health of the Guinea Pigs, and subsequently the experimental success rate, had a seasonal variation; therefore we sought to determine if there is a time of year in which our guinea pigs are more likely to be perceived as unhealthy, and whether any determined monthly pattern correlates with an experimentalists ability to complete an experimental protocol. An electronic log was created to record the perceived health of the animal and the ability to complete the experiment successfully. Irregular symptoms included, but were not limited to, severe weight or hair loss and irregularities with the heart found post thoracotomy or during baseline electrophysiological recordings of whole-heart preparations. Animals that did not exhibit significant weight or hair loss, or other ailments were considered "healthy". Overall, our results indicate that there are no monthly variations in perceived Hartley Albino guinea pig health or correlations with experimental completion rates, suggesting mild hair or weight loss that is common when shipping animals may not significantly affect the ability to conduct ex vivo whole-heart electrophysiological studies.

scientific communication and education↗

bioRxiv2018

Dissection of complex, fitness-related traits in multiple Drosophila mapping populations offers insight into the genetic control of stress resistance

We leverage two complementary Drosophila melanogaster mapping panels to genetically dissect starvation resistance, an important fitness trait. Using >1600 genotypes of the multiparental Drosophila Synthetic Population Resource (DSPR) we map numerous starvation stress QTL that collectively explain a substantial fraction of trait heritability. QTL effects further allowed us to estimate DSPR founder phenotypes, predictions that were correlated with the actual founder phenotypes. Starvation resistance has been linked to triglyceride level, and while we observe a modest phenotypic correlation between the traits in the DSPR, overlap among the QTL identified for each trait is low. Since we show that DSPR strains with extreme starvation phenotypes also differ in desiccation resistance and activity level, our data imply that multiple physiological mechanisms contribute to starvation variability. We also exploit the Drosophila Genetic Reference Panel (DGRP), identifying a number of sequence variants associated with starvation resistance. Consistent with prior work these sites rarely fall within QTL intervals mapped in the DSPR. Two other groups previously measured starvation resistance in the DGRP, offering a unique opportunity to directly compare mapping results across labs. We found strong phenotypic correlations among studies, but extremely low overlap in the sets of genomewide significant sites. Despite this, our analyses revealed that the most highly-associated variants from each study typically showed the same additive effect sign in independent studies, in contrast to otherwise equivalent sets of random variants. This consistency provides evidence for reproducible trait-associated sites in a widely-used mapping panel, and highlights the polygenic nature of starvation resistance.

genetics↗