Background: Emergency care planning is an important component of healthcare transition, particularly for patients with medical complexity. Duchenne muscular dystrophy (DMD) is a complex, progressive pediatric-onset disease affecting multiple organ systems including impairment of cardiac and pulmonary function, high risk for fractures, fat embolism, adrenal crisis and malignant hyperthermia. Appropriate interdisciplinary emergency management is critical for survival for these patients.
View Article and Find Full Text PDFUnlabelled: Peribiliary glands (PBGs) are clusters of epithelial cells residing in the submucosal compartment of extrahepatic bile ducts (EHBDs). Though their function is largely undefined, they may represent a stem cell niche. Here, we hypothesized that PBGs are populated by mature and undifferentiated cells capable of proliferation in pathological states.
View Article and Find Full Text PDFBiliary atresia is the most common cholangiopathy of childhood. During infancy, an idiopathic activation of the neonatal immune system targets the biliary epithelium, obstructs bile ducts, and disrupts the anatomic continuity between the liver and the intestine. Here, we use a model of virus-induced biliary atresia in newborn mice to trace the initiating pathogenic disease mechanisms to resident plasmacytoid (pDCs) and conventional (cDCs) dendritic cells.
View Article and Find Full Text PDFBackground & Aims: Although recent studies have identified important roles for T and NK cells in the pathogenesis of biliary atresia (BA), the mechanisms by which susceptibility to bile duct injury is restricted to the neonatal period are unknown.
Methods: We characterised hepatic regulatory T cells (Tregs) by flow cytometry in two groups of neonatal mice challenged with rhesus rotavirus (RRV) at day 7 (no ductal injury) or day 1 of life (resulting in BA), determined the functional interaction with effector cells in co-culture assays, and examined the effect of adoptive transfer of CD4+ cells on the BA phenotype.
Results: While day 7 RRV infection increased hepatic Tregs (Foxp3+ CD4+ CD25+) by 10-fold within 3 days, no increase in Tregs occurred at this time point following infection on day 1.
Biliary atresia is a neonatal obstructive cholangiopathy that progresses to end-stage liver disease. Although the etiology is unknown, a neonatal adaptive immune signature has been mechanistically linked to obstruction of the extrahepatic bile ducts. Here, we investigated the role of the innate immune response in the pathogenesis of biliary atresia.
View Article and Find Full Text PDFUnlabelled: Biliary atresia is a fibro-inflammatory cholangiopathy that obstructs the extrahepatic bile ducts in young infants. Although the pathogenesis of the disease is undefined, studies in livers from affected children and neonatal mice with experimental biliary atresia have shown increased expression of proapoptosis molecules. Therefore, we hypothesized that apoptosis is a significant mechanism of injury to duct epithelium.
View Article and Find Full Text PDFBackground & Aims: Lymphocytes populate the livers of infants with biliary atresia, but it is unknown whether neonatal lymphocytes regulate pathogenesis of disease. Here, we investigate this question by examining the role of T lymphocytes in the destruction of extrahepatic bile ducts of neonatal mice using an experimental model of biliary atresia.
Methods: Inoculation of neonatal mice with rhesus rotavirus followed by multistaining flow cytometry to quantify expression of interferon-gamma by hepatic lymphocytes, and real-time polymerase chain reaction for mRNA expression of pro-inflammatory cytokines.
Background: The urokinase-type (uPA) and tissue-type (tPA) plasminogen activators regulate liver matrix remodelling through the conversion of plasminogen (Plg) to the active protease plasmin. Based on the efficient activation of plasminogen when uPA is bound to its receptor (uPAR) and on the role of uPA in plasmin-mediated liver repair, we hypothesized that uPA requires uPAR for efficient liver repair.
Methods: To test this hypothesis, we administered one dose of carbon tetrachloride (CCl4) to mice with single or combined deficiencies of uPA, uPAR and tPA, and examined hepatic morphology, cellular proliferation, fibrin clearance, and hepatic proteolysis 2-14 days later.
Background: Livers of infants with biliary atresia and of neonatal mice infected with rotavirus (RRV) have increased expression of interferon-gamma (IFNgamma) and interleukin (IL)-12. While the expression of IFNgamma regulates the obstruction of extrahepatic bile ducts by lymphocytes, the role of IL-12 in the pathogenesis of biliary obstruction is unknown. Based on the role of IL-12 as a key proinflammatory cytokine, we hypothesized that loss of IL-12 prevents the obstruction of extrahepatic bile ducts.
View Article and Find Full Text PDFBackground & Aims: Discovery of the pathogenic mechanisms of biliary atresia has been limited by the inability to study extrahepatic biliary tissues from patients at early phases of disease. Here, we used a rotavirus-induced model of biliary atresia to investigate the entire biliary transcriptome for molecular networks activated at the onset and different phases of progression to duct obstruction.
Methods: We injected Balb/c mice with saline or rotavirus intraperitoneally within 24 hours of birth, microdissected the gallbladder and extrahepatic bile ducts en bloc 3, 7, and 14 days later, generated biotinylated RNA pools, and hybridized them against microarrays containing 45,101 gene products.
In multiple systems, impaired proteolysis associated with the loss of the hemostatic factor plasminogen (Plg) results in fibrin-dependent defects in tissue repair. However, repair within the liver is known to be defective in Plg-deficient (Plg(o)) mice independent of fibrin clearance and appears to be compromised in part by the poor clearance of necrotic cells. Based on these findings, we examined the hepatic transcriptome after injury in search of transcriptional programs that are sensitive to the Plg/fibrinogen system.
View Article and Find Full Text PDFThe etiology and pathogenesis of bile duct obstruction in children with biliary atresia are largely unknown. We have previously reported that, despite phenotypic heterogeneity, genomic signatures of livers from patients display a proinflammatory phenotype. Here, we address the hypothesis that production of IFN-gamma is a key pathogenic mechanism of disease using a mouse model of rotavirus-induced biliary atresia.
View Article and Find Full Text PDFThe molecular basis for the embryonic and perinatal clinical forms of biliary atresia is largely undefined. In this study, we aimed to: 1) determine if the clinical forms can be differentiated at the transcriptional level, and 2) search for molecular mechanisms underlying phenotypic differences. To this end, we generated biotinylated cRNA probes from livers of age-matched infants with the embryonic (n = 5) and perinatal (n = 6) forms of biliary atresia at the time of diagnosis and hybridized them against the Affymetrix human HG-U133 A and B microarrays containing 44,760 gene products.
View Article and Find Full Text PDFBackground/aims: While the metabolic and histological responses to cholestasis are recognized, the consequences of impaired biliary flow on liver gene expression are largely undefined. We hypothesized that biliary obstruction results in transcriptional reprogramming that dictates the physiologic response.
Methods: We determined global gene expression in murine livers 1-21 days following bile duct ligation.
Background: Biliary atresia is the commonest cause of pathological jaundice in infants and the leading indication for liver transplantation in children worldwide. The cause and pathogenesis remain largely unknown. Because of clinical heterogeneity and experimental difficulties in addressing molecular mechanisms underlying multifactorial disorders in human beings, we searched for genomic signatures of biliary atresia in affected infants.
View Article and Find Full Text PDFAm J Physiol Gastrointest Liver Physiol
March 2003
The urokinase-type plasminogen activator (uPA) plays a central role in liver repair. Nevertheless, the hepatic overexpression of uPA results in panlobular injury and neonatal mortality. Here, we define the molecular mechanisms of liver injury and explore whether uPA can regulate liver repair independently of plasminogen.
View Article and Find Full Text PDFLiver development and regeneration share the requirement for simultaneous proliferation and acquisition of highly specialized cellular functions. However, little is known about molecules with regulatory roles in both processes. We hypothesized that transcriptional reprogramming induced by regeneration recapitulates that of developing liver.
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