Biology subjects

Wiggins, B. G.

Publications and source records attributed to Wiggins, B. G..

2 recordsLinked to original sources

bioRxiv2025

Von Willebrand Factor Deficiency Impairs Vascular Morphogenesis via Angiopoietin-2: Relevance for Gut Angiodysplasia

Management of recurrent gastrointestinal (GI) bleeding is a clinical unmet need for patients with Von Willebrand disease (VWD) and is linked to the presence of gut vascular malformations (angiodysplasia). We previously demonstrated that von Willebrand factor (VWF) regulates angiogenesis and vascular integrity, the likely mechanism underlying angiodysplasia. VWF controls the storage of the angiogenesis regulator Angiopoietin-2 (Angpt-2) in endothelial cells (EC), suggesting a candidate for the genesis of angiodysplasia; however, no direct evidence of the role of Angpt-2 in VWF-dependent angiogenesis is available. Here we use VWF-deficient HUVEC, and endothelial colony forming cells (ECFCs) from severe VWD patients and find that loss of VWF in EC results in increased Angpt-2 expression through a positive feedback loop via the Angpt-2-TIE2-AKT-FOXO1 pathway. We also show an imbalance of the Angpt/Tie2 pathway in vivo. In the gut of VWF-deficient mice, Angpt-2 expression is increased whilst Angpt-1 expression is decreased; this correlates with reduced expression of the pericyte marker NG2. These data suggest that VWF regulates the Angpt/Tie2 balance in the gut. To investigate the functional defects caused by loss of VWF, we use a fibrin bead assay and show that VWF-deficient HUVEC present increased sprouting. We develop a microfluidic model of 3D vasculogenesis/angiogenesis and find that ECFCs from VWD patients exhibit defective remodeling and abnormal lumen formation compared to healthy controls. Importantly, inhibition of Angpt-2 reduces sprouting in VWF-deficient HUVEC and normalises vascular networks in ECFCs from severe VWD, suggesting Angpt-2 inhibitors may be effective in VWD patients with GI bleeding and angiodysplasia. Key pointsO_LIEndothelial VWF regulates multiple steps of angiogenesis, including sprouting and lumen formation. C_LIO_LIVWF regulates Angpt-2 storage and expression, and Angpt-2 blockade normalises defective angiogenesis in VWD ECFCs. C_LI Visual Abstract O_FIG O_LINKSMALLFIG WIDTH=170 HEIGHT=200 SRC="FIGDIR/small/675051v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@150eb15org.highwire.dtl.DTLVardef@179e6beorg.highwire.dtl.DTLVardef@1bcadborg.highwire.dtl.DTLVardef@a30fb8_HPS_FORMAT_FIGEXP M_FIG VWF deficiency in HUVECs results in increased Angpt-2 release and expression via the Tie2-Akt-FOXO1 pathway. A. Model pathway for the regulation of Angpt-2 levels by VWF. Loss of VWF results in increased Angpt-2 release from endothelial cells; Angpt-2 binds to and inhibits the Tie2 receptor, decreasing its phosphorylation as well as the downstream phosphorylation of Akt and FOXO1; this leads to FOXO1 activation and an increase expression of Angpt-2, generating a feedback loop. B. Model for the pathogenesis of angiodysplasia in VWD. In the absence of VWF, the increase in Angpt-2 disrupts vascular morphogenesis through multiple mechanisms: increased sprouting, impaired vascular remodelling and an imbalance between Angpt-1 and Angpt-2 in the gut. Figure generated with Biorender. C_FIG

cell biology↗

bioRxiv2020

The human liver microenvironment shapes the homing and function of CD4+ T-cell populations

Background & AimsTissue-resident memory T cells (TRM) are important immune sentinels that provide efficient in situ immunity. Liver-resident CD8+ TRM have been previously described, and contribute to viral control in persistent hepatotropic infections. However, little is known regarding liver CD4+ TRM cells. Here we profiled resident and non-resident intrahepatic CD4+ T cell subsets, assessing their phenotype, function, differential generation requirements and roles in hepatotropic infection. MethodsLiver tissue was obtained from 173 subjects with (n=109) or without (n=64) hepatic pathology. Multiparametric flow cytometry and immunofluorescence imaging examined T cell phenotype, functionality and location. Liver T cell function was determined after stimulation with anti-CD3/CD28 and PMA/Ionomycin. Co-cultures of blood-derived lymphocytes with hepatocyte cell lines, primary biliary epithelial cells, and precision-cut autologous liver slices were used to investigate the acquisition of liver-resident phenotypes. ResultsCD69 expression delineated two distinct subsets in the human liver. CD69HI cells were identified as CD4+ TRM due to exclusion from the circulation, a residency-associated phenotype (CXCR6+CD49a+S1PR1-PD-1+), restriction to specific liver niches, and ability to produce robust type-1 multifunctional cytokine responses. Conversely, CD69INT were an activated T cell population also found in the peripheral circulation, with a distinct homing profile (CX3CR1+CXCR3+CXCR1+), and a bias towards IL-4 production. Frequencies of CD69INT cells correlated with the degree of fibrosis in chronic hepatitis B virus infection. Interaction with hepatic epithelia was sufficient to generate CD69INT cells, while additional signals from the liver microenvironment were required to generate liver-resident CD69HI cells. ConclusionsIntermediate and high CD69 expression demarcates two discrete intrahepatic CD4+ T cell subsets with distinct developmental and functional profiles. Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY HighlightsO_LICD69HI (CXCR6+CD49a+S1PR1-PD-1+) are the CD4+ TRM of the human liver C_LIO_LIHepatic CD69INTCD4+ T-cells are distinct, activated, and recirculation-competent C_LIO_LIStimulation evokes respective IFN-{gamma} and IL-4 responses in CD69HI and CD69INT cells C_LIO_LICD69INT cell frequencies correlate with worsening fibrosis in chronic HBV patients C_LIO_LILiver slice cultures allow differentiation of CD69INT and CD69HI cells from blood C_LI Lay summaryTissue-resident memory T cells (TRM) orchestrate regional immune responses, but much of the biology of liver-resident CD4+ TRM remains unknown. We found high expression of cell-surface protein CD69 defined hepatic CD4+ TRM, while simultaneously uncovering a distinct novel recirculatory CD69INT CD4+ T cell subset. Both subsets displayed unique immune receptor profiles, were functionally skewed towards type-1 and type-2 responses respectively, and had distinct generation requirements, highlighting the potential for differential roles in the immunopathology of chronic liver diseases.

immunology↗