Biology subjects

McCarthy, H.

Publications and source records attributed to McCarthy, H..

5 recordsLinked to original sources

bioRxiv2026

Biological Signaling Pathways Associated with Late Tendon Development in Chicken Embryos and Their Dependence on Mechanical Stimulation

During embryonic and neonatal development, tendons exhibit rapid changes in mechanics and structure, including increases in collagen content, crosslinking, and fibril length. These functional and structural changes are partly dependent on mechanical stimulation. However, the specific mechanobiological mechanisms driving these changes remain poorly understood. The objective of this study was to identify the potential biological mechanisms and pathways driving tendon maturation into load-bearing materials using an embryonic chick model. Using bulk RNA sequencing, gene set enrichment analysis, and transcription factor analysis, we produced a transcriptomic profile of chick hindlimb tendons during late embryonic development (E16, E18, and E20) and tendons from rigid and flaccid paralysis-treated embryos. Additionally, we assessed the results from two differential expression analysis models to improve the replicability of our findings. Our results suggest that the largest transcriptomic response occurs between embryonic day 16 and 20, and that among paralysis conditions, rigid paralysis produces the greatest effect relative to controls. Across development, we found positive enrichment in processes related to mechanotransduction, extracellular matrix remodeling, cell adhesion, and contractility, and identified candidate pathways upregulated with development, including TGF-{beta}, PI3K-AKT-mTOR, Hippo, circadian rhythm, and focal adhesion signaling. In paralysis-treated embryos, our data suggest impairment in extracellular matrix remodeling and mechanotransduction events. Specifically, we found that both modes of paralysis are associated with a cellular stress response and downregulation of WNT signaling. Together, our findings identify candidate mechanotransduction pathways that are associated with late tendon maturation and altered by paralysis, which may inform tendon tissue engineering and regenerative approaches.

bioengineering↗

bioRxiv2025

Microbiota Modulation Induces Elevated Duodenal Eosinophils Upon Gluten Exposure in Mice: Implications for Non-Coeliac Gluten Sensitivity

A growing proportion of the non-celiac population experience adverse symptoms to gluten. The pathogenesis of non-coeliac gluten sensitivity (NCGS) is unclear, but elevated duodenal eosinophils and altered mucosa-associated microbiota (MAM) populations have been reported. Given the microbiomes role in gluten digestion and its susceptibility to antibiotics, we hypothesised that altering the microbiome with antibiotics would modify immune responses to gluten in mice. BALB/C mice consuming gluten-free chow received amoxicillin/clavulanate (5mg/kg) or PBS-vehicle daily for 5 days. Mice were then treated with a 3mg wheat-gluten suspension, or vehicle, on days 4 and 5 before sacrifice on day 7. Duodenal immune cells were analysed by histology and flow cytometry, while the duodenal MAM and faecal microbiome were characterised via 16S rRNA and shotgun metagenomic sequencing, respectively. Antibiotic treatment followed by gluten reintroduction significantly reduced Staphylococcus in the duodenal MAM, enriched Bacteroides in faeces, and resulted in altered microbial carbohydrate and lipid metabolism, compared to vehicle controls. Treatment with antibiotics and gluten also increased duodenal eosinophils which positively correlated with the genus Blautia. Flow cytometry revealed that antibiotics and gluten treatment resulted in a greater proportion of active eosinophils and epithelial {gamma}{delta} T-cells, compared to vehicle control mice. This study demonstrated that modulating the microbiome with antibiotics was sufficient to alter the immune response to gluten in mice. These findings suggest that the microbiome may determine the capacity for gluten to induce an immune response and offers a valuable insight into potential mechanisms underlying NCGS. New & NoteworthyA mouse model examined how microbial modulation affects immune responses to gluten. Antibiotic treatment followed by gluten reintroduction reduced duodenal Staphylococcus and altered microbial carbohydrate and lipid metabolism pathways in the faecal microbiome. Antibiotics and gluten treatment resulted in increased abundance and activation of duodenal eosinophils, and elevated {gamma}{delta} T-cells in the duodenal epithelium. These findings highlight the role the microbiome plays in gluten-induced immune responses, providing insights into mechanisms behind non-coeliac gluten sensitivity.

immunology↗

bioRxiv2024

A rational approach for the targeted discovery and characterisation of microbiome-derived therapeutics

The human gut microbiome is intrinsically involved in health and disease, representing a wealth of untapped therapeutic potential. Here, we demonstrate the utility and potential of a metagenome guided, large cohort-based approach for the rational selection of live biotherapeutics from the human gut. We applied this approach to Inflammatory Bowel Disease (IBD), identifying several lead candidates that were significantly depleted in individuals with IBD compared to healthy controls. Their therapeutic potential was assessed in preclinical models of IBD where they improved markers of disease pathology by reducing inflammation and promoting mucosal healing and wound repair. All leads had excellent safety profiles in silico and in vitro, and several additionally presented favourable manufacturing properties, supporting their progression into clinical trials. We believe that this rational approach will be generalisable to any disease state with underlying microbiome aetiology and will expedite the development of novel microbiome-derived therapeutics to improve human health.

microbiology↗

bioRxiv2024

Embryo movement is required for limb tendon maturation

Following early cell specification and tenocyte differentiation at the sites of future tendons, very little is known about how tendon maturation into robust load-bearing tissue is regulated. Between embryonic day (E)16 and E18 in the chick, there is a rapid change in mechanical properties which is dependent on normal embryo movement. However, the tissue, cellular and molecular changes that contribute to this transition are not well defined. Here we profiled aspects of late tendon development (collagen fibre alignment, cell organisation and Yap pathway activity), describing changes that coincide with tissue maturation. We compared effects of rigid (constant static loading) and flaccid (no loading) immobilisation to gain insight into developmental steps influenced by mechanical cues. We show that YAP signalling is active and responsive to movement in late tendon. Collagen fibre alignment increased over time and under static loading. Cells organise into end-to-end stacked columns with increased distance between adjacent columns, where collagen fibres are deposited; this organisation was lost following both types of immobilisation. We conclude that specific aspects of tendon maturation requires controlled levels of dynamic muscle-generated stimulation. Such a developmental approach to understanding how tendons are constructed will inform future work to engineer improved tensile load-bearing tissues.

developmental biology↗

bioRxiv2023

Structural Determinants of Tendon Function During Development and Their Sensitivity to Mechanical Stimulation

The load-bearing capabilities of tendon are acquired during neonatal stages of development, characterized by an abrupt increase in multiscale mechanical properties. While prior work has identified numerous changes within the collagenous structure during these developmental periods, the primary structural elements that give rise to this abrupt mechanical functionality, and their mechanobiological sensitivity, remains unclear. To address this gap in knowledge, we leveraged a combination of ultrastructural imaging, biochemical/thermodynamic assays, multiscale mechanical testing, and shear lag modeling to probe the dynamic structure-function relationships and establish their sensitivity to mechanical stimulation during tenogenesis. Mechanical testing and modeling suggested that the rapid increase in multiscale mechanics can be explained by a increasing fibril length and intrafibrillar crosslinking. To test this, we inhibited collagen crosslinking during development and observed a drastic reduction in multiscale mechanical capabilities that was explained by a reduction in both fibril modulus and length. Using muscle paralysis to investigate mechanosensitivity, we observed a significantly impaired multiscale mechanical response despite small changes in fibril diameter and fibril area fraction. While there was no change in crosslinking density, there was a decrease in thermal stability with flaccid paralysis, and our shear-lag model suggested that flaccid paralysis produces a reduction in fibril length and intrafibrillar crosslinking. Together, these data suggest that both intrafibrillar crosslink formation and fibril elongation are critical to the formation of load-bearing capabilities in tenogenesis and are sensitive to musculoskeletal activity. These findings provide critical insights into the biological mechanisms that give rise to load-bearing soft tissue.

bioengineering↗