Crystallographic Fragment Screen of Coxsackievirus A16 2A Protease identifies new opportunities for the development of broad-spectrum anti-enterovirals.

Enteroviruses are the causative agents of paediatric hand-foot-and-mouth disease, and a target for pandemic preparedness due to the risk of higher order complications in a large-scale outbreak. The 2A protease of these viruses is responsible for the self-cleavage of the poly protein, allowing for correct folding and assembly of capsid proteins in the final stages of viral replication. These 2A proteases are highly conserved between Enterovirus species, such as Enterovirus A71 and Coxsackievirus A16 . Inhibition of the 2A protease deranges capsid folding and assembly, preventing formation of mature virions in host cells and making the protease a valuable target for antiviral activity. Herein, we describe a crystallographic fragment screening campaign that identified 75 fragments which bind to the 2A protease including 38 unique compounds shown to bind within the active site. These fragments reveal a path for the development of non-peptidomimetic inhibitors of the 2A protease with broad-spectrum anti-enteroviral activity.

Characterisation of a stereotypical cellular and extracellular adult liver progenitor cell niche in rodents and diseased human liver.

BACKGROUND: Stem/progenitor cell niches in tissues regulate stem/progenitor cell differentiation and proliferation through local signalling. OBJECTIVE: To examine the composition and formation of stem progenitor cell niches. METHODS: The composition of the hepatic progenitor cell niche in independent models of liver injury and hepatic progenitor cell activation in rodents and humans was studied. To identify the origin of the progenitor and niche cells, sex-mismatched bone marrow transplants in mice, who had received the choline-ethionine-deficient-diet to induce liver injury and progenitor cell activation, were used. The matrix surrounding the progenitor cells was described by immunohistochemical staining and its functional role controlling progenitor cell behaviour was studied in cell culture experiments using different matrix layers. RESULTS: The progenitor cell response in liver injury is intimately surrounded by myofibroblasts and macrophages, and to a lesser extent by endothelial cells. Hepatic progenitor cells are not of bone marrow origin; however, bone marrow-derived cells associate intimately with these cells and are macrophages. Laminin always surrounds the progenitor cells. In vitro studies showed that laminin aids maintenance of progenitor and biliary cell phenotype and promotes their gene expression (Dlk1, Aquaporin 1, gammaGT) while inhibiting hepatocyte differentiation and gene expression (CEPB/alpha). CONCLUSIONS: During liver damage in rodents and humans a stereotypical cellular and laminin niche forms around hepatic progenitor cells. Laminin helps maintenance of undifferentiated progenitor cells. The niche links the intrahepatic progenitor cells with bone marrow-derived cells and links tissue damage with progenitor cell-mediated tissue repair.

Assessment of proliferation in vivo using 2-[(11)C]thymidine positron emission tomography in advanced intra-abdominal malignancies.

The purpose of this study was to determine the relationship between 2-[(11)C]thymidine positron emission tomography (PET) in vivo-derived parameters and the ex vivo Ki-67 index of proliferation in human tumors. The study comprised 17 treatment-naïve patients with advanced intra-abdominal malignancies. Tumor thymidine kinetics were measured using 2-[(11)C]thymidine PET. Tissue data were analyzed to give the standardized uptake value, the area under the time activity curve, and the fractional retention of thymidine (FRT) obtained by kinetic modeling. For the latter, the contribution of labeled metabolites was accounted for by measuring thymidine metabolites in arterial plasma. To examine the influence of tumor blood flow on the thymidine PET data, a perfusion scan using inhaled [(15)O]CO(2) was carried out in a subset of 11 patients. Biopsies were stained with a MIB1 antibody to obtain a Ki-67 index, and correlations with the PET-derived parameters were investigated. There was no relationship between tumor blood flow and the thymidine PET data, showing that the retention of 2-[(11)C]thymidine in tumors was independent of tumor perfusion. There was no correlation between the Ki-67 index and either standard uptake value or area under the curve. There was a correlation between the Ki-67 index and FRT (r = 0.58; P = 0.01). The correlation between the Ki-67 index and FRT in this dataset was not influenced by the interval between biopsy and imaging (0.1-126 weeks), the origin of the biopsy for Ki-67 staining (primary tumor or metastasis), or whether the biopsy was from an imaged or a nonimaged tumor. This is the first report in human tumors showing that 2-[(11)C]thymidine PET-derived parameters correlate with the level of tumor proliferation measured using Ki-67 immunohistochemistry. The study shows that the in vivo measurement of 2-[(11)C]thymidine in tumors using PET can provide a surrogate marker of proliferation and supports the potential use of the technique in the early assessment of response to antiproliferative cancer treatment.