Lohi, J. | Search bioRxiv

bioRxiv2023

Childhood-onset asthma is characterized by airway epithelial hillock-to-squamous differentiation in early life

Childhood-onset asthma is characterized by Type 2-inflammation and airway wall remodeling, but mechanisms of asthma development in the first years of life remain unclear. Here, we investigate transcriptional changes in airway wall biopsies of 22 symptomatic one year old children and relate these to asthma at school age. We demonstrate that pre-asthmatic children (n = 10) overexpressed a gene signature characteristic for an airway epithelial differentiation trajectory via hillock cells towards squamous cells (adjusted p-value 8.06e-16), whilst there was no association with gene signatures of Type 2-inflammation or eosinophil activation. Genes expressed along this trajectory are linked to an altered epithelial barrier function, innate immune activation and extracellular matrix remodeling. Functional GWAS analysis supports a causal link between childhood-onset, but not adult-onset asthma, and the hillock-squamous cell differentiation trajectory. Next, we confirmed the presence of hillock-like cells at the RNA and protein level in pediatric upper and lower airway samples. These findings identify a novel mechanism by which an aberrant airway epithelial differentiation trajectory may contribute to a pre-asthmatic state, highlighting the difference between the early origins of childhood-onset asthma and adult asthma, and point to possible new targets for the early diagnosis and treatment of asthma in the first two years of life. One Sentence SummaryRNA sequencing in bronchial biopsies from wheezing infants and children < 2 years shows evidence for an airway epithelial hillock-to-squamous differentiation pathway that marks the development of asthma.

genomics↗

bioRxiv2022

ErbB Signalling is a Potential Therapeutic Target for Vascular Lesions with Fibrous Component

BackgroundSporadic venous malformation (VM) and angiomatosis of soft tissue (AST) are benign, congenital vascular anomalies affecting venous vasculature. Depending on the size and location of the lesion, symptoms vary from motility disturbances to pain and disfigurement. Due to high recurrence of the lesions more effective therapies are needed. MethodsAs targeting stromal cells has been an emerging concept in anti-angiogenic therapies, here, by using VM/AST patient samples, RNA-sequencing, cell culture techniques and a xenograft mouse model, we investigated the crosstalk of endothelial cells (EC) and fibroblasts and its effect on vascular lesion growth. ResultsWe report, for the first time, expression and secretion of transforming growth factor A (TGFA) in ECs or intervascular stromal cells in AST and VM lesions. TGFA induced secretion of VEGF-A paracrinally, and regulated EC proliferation. Oncogenic PIK3CA variant in p.H1047R, a common somatic mutation found in these lesions, increased TGFA expression, enrichment of hallmark hypoxia, and in a mouse xenograft model, lesion size and vascularization. Treatment with afatinib, a pan-ErbB tyrosine-kinase inhibitor, decreased vascularization and lesion size in mouse xenograft model with ECs expressing oncogenic PIK3CA p.H1047R variant and fibroblasts. ConclusionsBased on the data, we suggest that targeting of both intervascular stromal cells and ECs is a potential treatment strategy for vascular lesions having a fibrous component. FundingAcademy of Finland, Ella and Georg Ehnrooth foundation, the ERC grants, Sigrid Juselius Foundation, Finnish Foundation for Cardiovascular Research, Jane and Aatos Erkko Foundation, and Department of Musculosceletal and Plastic Surgery, Helsinki University Hospital. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=122 SRC="FIGDIR/small/509204v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@14ec94aorg.highwire.dtl.DTLVardef@1812747org.highwire.dtl.DTLVardef@39d01eorg.highwire.dtl.DTLVardef@18e9e35_HPS_FORMAT_FIGEXP M_FIG Graphical abstract. Proposed model for the paracrine signaling of TGFA/VEGF-A in vascular lesion Schematic illustration showing the general structure of venous malformation or angiomatosis of soft tissue. Pathological vasculature in the lesion (dark blue) is surrounded by disorganized extracellular matrix (ECM) and intervascular stromal cells (SCs, orange). High magnification from the area close to vessel wall demonstrates the proposed model for crosstalk between endothelial cells (ECs) and SCs. A mutation in phosphatidylinositol-4,5-biphosphate 3-kinase catalytic subunit alpha (PIK3CA) gene (1) or other processes promote ECs to express high level of transforming growth factor A (TGFA) (2). TGFA binds to epithelial growth factor receptor (EGFR) on the surface of adjacent SCs (3). Activated EGFR-downstream signaling (4) promotes elevated expression of vascular endothelial growth factor (VEGF)-A in SCs and increases the expression of TGFA (5). VEGF-A secreted from SCs (6) binds to VEGF-recetor-2 (VEGFR2) on surface of ECs (7) and together with TGFA activates angiogenic EC phenotype. TGFA secreted from the SCs (8), can further activate EGFR and its downstream signaling. C_FIG

cell biology↗