Biology subjects

O'Toole, E. A.

Publications and source records attributed to O'Toole, E. A..

3 recordsLinked to original sources

bioRxiv2024

A single cell and spatial genomics atlas of human skin fibroblasts in health and disease

Fibroblasts are critical cells that shape the architecture and cellular ecosystems in multiple tissues. Understanding fibroblast heterogeneity and their spatial context in health and disease has enormous clinical relevance. In this study, we constructed a spatially-resolved atlas of human skin fibroblasts from healthy skin and 23 skin disorders. We define 6 major skin fibroblast populations in health and a further three skin disease-specific fibroblast subtypes, and demonstrate the fibroblast composition in different types of skin disease. We characterise a human-specific fibroblastic reticular cell (FRC)-like subtype in the skin perivascular niche and postulate their origin from prenatal skin lymphoid tissue organiser (LTo)-like cells. We also show that inflammatory myofibroblasts (IL11+MMP1+CXCL5+IL7R+) are a conserved fibroblast subtype in inflammatory disorders and cancers across multiple human tissues. We provide a harmonised nomenclature for skin fibroblasts that integrates previous findings from human skin and other tissues.

cell biology↗

bioRxiv2024

Reduced Filaggrin expression induces dysregulated intracellular signalling in atopic eczema

Atopic eczema (AE) is the most common inflammatory dermatosis, affecting up to 20% of children. Loss of function mutations in the Filaggrin (FLG) gene are the most strongly implicated genetic risk factor for AE, but little is known about the signalling pathways altered in response to loss of FLG. To explore the downstream effects of loss of FLG on the cellular environment, we combined RNAseq analysis of siRNA knockdown of normal human keratinocytes and analysis of tape strip (TS) samples from AE patients who were clinically phenotyped and genotyped for FLG mutation status. RNA-seq analysis revealed an increase in BMP signalling following FLG KD, which we validated in vivo using TS samples and biopsies. Recombinant BMP2 or BMP6 increased FLG and suprabasal keratin expression in vitro. Phosphoproteomic analysis identified 237 significantly differentially phosphorylated proteins following FLG KD. Kinase enrichment analysis identified downregulation of ERK1/2 and AKT1 signalling which was confirmed in AE biopsies. cFOS was downregulated following FLG KD and correlated with FLG expression in repository datasets. cFOS was downregulated following BMP6 treatment, implying that cFOS may be an important link between FLG and BMP signalling. Finally, proteomic analysis of TS samples identified altered desmosomal expression and phosphorylation following either loss of FLG or increased BMP signalling. Therefore, we have identified a SMAD1/Filaggrin/AKT axis as a potential therapeutic avenue in AE.

cell biology↗

bioRxiv2023

Loss of cholesterol in Junctional Epidermolysis Bullosa skin identifies a key role for Laminin-332 in actomyosin mediated cholesterol transport

Individuals with Junctional Epidermolysis Bullosa (JEB), a rare genetic skin disease characterised by loss of function mutations in the Laminin332 (Lam332), do not survive beyond their first birthday. Here we report that loss of Lam332 leads to absence of cholesterol lipid from the epidermis in vitro and in vivo. Using 3D skin equivalents, a JEB mouse model and JEB patient samples we confirmed changes in epidermal lipid synthesis, which was further explored using lipidomics. Cholesterol biosynthesis genes were increased with loss of Laminin-332 in vitro, however a decrease in immunofluorescence lipid staining was observed. Cholesterol transport in Laminin-332 knockdown keratinocytes was revealed to be disrupted, which in keratinocytes is dependent on the actomyosin network. In conclusion these findings suggest a role for the basement membrane protein Laminin-332 in lipid metabolism in the skin, and a broader role for epidermal homeostasis and barrier formation. Restoration of cholesterol transport in epidermal keratinocytes of JEB patients offers the potential to improve their skin barrier.

cell biology↗