Biology subjects

Hardman, M. J.

Publications and source records attributed to Hardman, M. J..

4 recordsLinked to original sources

bioRxiv2025

High-resolution Staphylococcus profiling reveals intra-species diversity in a single skin niche

The skin microbiome is dominated by a few key genera, among which Staphylococcus is one of the most well-characterised. Recent studies have examined the roles of various Staphylococcus species such as S. epidermidis and S. hominis within broader skin microbial communities. However, these investigations often rely on isolates from multiple individuals and hence, limiting their ability to capture intra-community interactions. In this study, we focused on the axillary microbiome of a single healthy individual to characterise the genetic and functional diversity of resident Staphylococcus isolates. Using a low-cost, high-throughput DNA extraction and long-read whole genome sequencing pipeline, we generated complete genomes for 93 isolates spanning seven genetically distinct lineages across three major skin species. These comprised of one dominant with three additional lineages of S. epidermidis, two of S. hominis and one of S. capitis. Functional and metabolic analyses revealed species- and strain-specific features, suggesting potential metabolic cross-feeding and specialisation within this community, including within strains of S. epidermidis. These findings highlight the metabolic complexity and potential interdependence of staphylococci inhabiting a single skin site and the need for strain-level resolution of the community. The strains form part of the York Skin Microbiome (YSM) collection, a growing open biobank of genetically diverse skin isolates from matched individuals.

microbiology↗

bioRxiv2021

Dexamethasone induces senescence of lung epithelial cells and augments TGF-β1-mediated production of the fibrosis mediator serpin E1 (plasminogen activator inhibitor-1)

BackgroundIdiopathic pulmonary fibrosis (IPF) is a progressive, incurable scarring disease of the lungs with a prognosis worse than most cancers. Pathologically, IPF is characterised by upregulation of the pro-fibrotic cytokine transforming growth factor-{beta}1 (TGF-{beta}1), activation of fibroblasts, and deposition of collagen in the alveolar interstitium. Recent evidence has highlighted the role of senescent type 2 alveolar epithelial cells in the pathogenesis of IPF. In a clinical trial, a treatment regimen containing a corticosteroid drug accelerated pulmonary fibrosis leading to more hospitalizations and deaths, particularly in patients with telomere shortening which drives cellular senescence. AimTo investigate the potential pro-fibrotic actions of corticosteroids on lung epithelial cells in vitro, including effects on cellular senescence and interactions with TGF-{beta}1. MethodsThe synthetic glucocorticoid dexamethasone (DEX) was incubated with A549 and BEAS-2B human lung epithelial cells in the presence or absence of TGF-{beta}1. Cellular senescence was assessed by morphology, senescence-associated beta-galactosidase (SA {beta}-Gal) expression, and qPCR for transcription of senescence-associated molecular markers. Conditioned media were screened for growth factors and cytokines and cultured with human lung fibroblasts. An IPF lung tissue RNA array dataset was re-analysed with a focus on senescence markers. ResultsDEX induced senescence in lung epithelial cells associated with increased p21 (CDKN1A) expression independently of p16 (CDKN2A) or p53 (TP53). DEX amplified upregulation of the pro-fibrotic mediator serpin E1/plasminogen activator inhibitor-1 (PAI-1) in the presence of TGF-{beta}1. The senescence-associated secretory phenotype from lung epithelial cells treated with DEX plus TGF-{beta}1-treated contained increased concentrations of GM-CSF and IL-6 and when incubated with primary human lung fibroblasts there were trends to increased senescence and production of fibrosis markers. Upregulation of senescence markers was demonstrated by analysis of an IPF transcriptomic dataset. DiscussionDEX induces senescence in lung epithelial cell lines in vitro and interacts with TGF-{beta}1 to amplify production of the pro-fibrotic mediator serpin E1 (PAI-1). This may be a mechanism by which corticosteroids promote pulmonary fibrosis in susceptible individuals. Serpin E1/PAI-1 is a potential druggable target in pulmonary fibrosis.

cell biology↗

bioRxiv2019

Estrogen mediates acute elastic fibre homeostasis in skin

Remodelling of the dermal extracellular matrix makes a major contribution to skin fragility in the elderly. The peri-menopausal period in females is also associated with an age-like phenotype which can be reversed by hormone replacement therapy. This suggests a direct link between circulating hormone levels and tissue ageing. Despite work investigating the role of estrogen as a regulator of collagen fibril abundance and structure, the influence of estrogen on the elastic fibre system remains poorly defined. Here we used an ovariectomised (Ovx) mouse surgical menopause model to show that just 7 weeks of acute hormone deficiency significantly decreased skin tensile strength and elasticity. Systemic replacement of 17{beta}-estradiol to physiological levels protected against these changes to the skin mechanical properties. Moreover, acute hormone deficiency differentially influenced dermal structural networks, significantly decreasing dermal elastic fibre abundance without discernible effect on collagen fibril organisation or abundance. We suggest that this specific elastic fibre proteolysis may be driven by extracellular protease activity, or be a consequence of significant adipocyte hypertrophy. 17{beta}-estradiol supplementation in Ovx mice in vivo protected the elastic fibre system. Treatment of human dermal fibroblasts with 17{beta}-estradiol in vitro induced the selective upregulation of tropoelastin, fibrillin-1 and associated elastic fibre-associated proteins (including EMILINs and fibulins). In summary, these data show that the elastic fibre system is significantly perturbed by estrogen deprivation. Thus, pharmacological intervention may slow the acute effects of menopause and potentially the chronic effects of ageing in skin.

biophysics↗

bioRxiv2019

Distinct matrix composition and mechanics in aged and estrogen-deficient mouse skin

Hormone deficiency has been widely linked to accelerated tissue ageing, and increased incidence of chronic degenerative disease. Furthermore, age-associated hormonal dysregulation is thought to be a major contributing factor to the increased fragility of aged skin. The ageing process is driven by an aggregation of damage to cells and extracellular matrix, which can directly influence the mechanical properties of the tissue. Here we report on the correlation between mechanical properties and composition of skin from ovariectomised and aged mice, to assess the extent to which estrogen deprivation drives dermal ageing. We found that age and estrogen abrogation affected skin mechanical properties in contrasting ways: ageing led to increased tensile strength and stiffness while estrogen deprivation had the opposite effect. Mass spectrometry proteomics showed that the quantity of extractable fibrillar collagen-I decreased with ageing, but no change was observed in ovariectomised mice. This observation, in combination with measurements of tensile strength, was interpreted to reflect changes to the extent of extracellular matrix crosslinking, supported by a significant increase in the staining of advanced glycation endpoints in aged skin. Loss of mechanical strength in the skin following ovariectomy was consistent with a loss of elastic fibres. Other changes in extracellular matrix composition broadly correlated between aged and ovariectomised mice, confirming the important role of estrogen-related pathways in ageing. This study offers new insight into the relationship between tissue composition and mechanics, and suggests that the deleterious effects of intrinsic skin ageing are compounded by factors beyond hormonal dysregulation.

biophysics↗