Primary and malignant cholangiocytes undergo CD40 mediated Fas dependent Apoptosis, but are insensitive to direct activation with exogenous fas ligand

Introduction Cholangiocarcinoma is a rare malignancy of the biliary tract, the incidence of which is rising, but the pathogenesis of which remains uncertain. No common genetic defects have been described but it is accepted that chronic inflammation is an important contributing factor. We have shown that primary human cholangiocyte and hepatocyte survival is tightly regulated via co-operative interactions between two tumour necrosis family (TNF) receptor family members; CD40 and Fas (CD95). Functional deficiency of CD154, the ligand for CD40, leads to a failure of clearance of biliary tract infections and a predisposition to cholangiocarcinoma implying a direct link between TNF receptor-mediated apoptosis and the development of cholangiocarcinoma. Aims To determine whether malignant cholangiocytes display defects in CD40 mediated apoptosis. By comparing CD40 and Fas-mediated apoptosis and intracellular signalling in primary human cholangiocytes and three cholangiocyte cell lines. Results Primary cholangiocytes and cholangiocyte cell lines were relatively insensitive to direct Fas-mediated killing with exogenous FasL when compared with Jurkat cells, which readily underwent Fas-mediated apoptosis, but were extremely sensitive to CD154 stimulation. The sensitivity of cells to CD40 activation was similar in magnitude in both primary and malignant cells and was STAT-3 and AP-1 dependent in both. Conclusions 1) Both primary and malignant cholangiocytes are relatively resistant to Fas–mediated killing but show exquisite sensitivity to CD154, suggesting that the CD40 pathway is intact and fully functional in both primary and malignant cholangiocytes 2) The relative insensitivity of cholangiocytes to Fas activation demonstrates the importance of CD40 augmentation of Fas dependent death in these cells. Agonistic therapies which target CD40 and associated intracellular signalling pathways may be effective in promoting apoptosis of malignant cholangiocytes

CD40 Activation Induces Apoptosis in Cultured Human Hepatocytes via Induction of Cell Surface Fas Ligand Expression and Amplifies Fas-mediated Hepatocyte Death during Allograft Rejection

We propose that a novel mechanism of hepatocyte apoptosis, involving a cooperative interaction between CD40 and Fas, is involved in the hepatocyte loss of chronic liver allograft rejection. We detected increased hepatocyte expression of Fas, Fas ligand (FasL), and CD40 associated with dropout of centrilobular (acinar zone 3) hepatocytes in chronic allograft rejection. Expression of CD40 ligand (CD40L) was also increased but was largely restricted to CD68+ macrophages. A functional role for CD40 and Fas in hepatocyte apoptosis was demonstrated in vitro using primary human hepatocytes and the HepG2 cell line in both of which apoptosis was induced, not only by cross-linking Fas directly but also via CD40 activation. Our data suggest that CD40 activation induces apoptosis via Fas because (a) ligation of CD40 upregulated hepatocyte FasL expression, and (b) apoptosis induced via activation of CD40 was prevented by a neutralizing monoclonal antibody to FasL. Thus, CD40 engagement triggers apoptosis of human hepatocytes and might amplify Fas-dependent hepatocyte apoptosis in chronic rejection and other inflammatory liver diseases in which Fas-mediated apoptosis is involved

Manipulating Kondo Temperature via Single Molecule Switching

Two conformations of isolated single TBrPP-Co molecules on a Cu(111) surface are switched by applying +2.2 V voltage pulses from a scanning tunneling microscope tip at 4.6 K. The TBrPP-Co has a spin-active cobalt atom caged at its center and the interaction between the spin of this cobalt atom and free electrons from the Cu(111) substrate can cause a Kondo resonance. Tunneling spectroscopy data reveal that switching from the saddle to a planar molecular conformation enhances spin-electron coupling, which increases the associated Kondo temperature from 130 K to 170 K. This result demonstrates that the Kondo temperature can be manipulated just by changing molecular conformation without altering chemical composition of the molecule.Comment: To appear in Nano Lett (2006

C4b Binding Protein Binds to CD154 Preventing CD40 Mediated Cholangiocyte Apoptosis: A Novel Link between Complement and Epithelial Cell Survival

Activation of CD40 on hepatocytes and cholangiocytes is critical for amplifying Fas-mediated apoptosis in the human liver. C4b-Binding Protein (C4BP) has been reported to act as a potential surrogate ligand for CD40, suggesting that it could be involved in modulating liver epithelial cell survival. Using surface plasmon resonance (BiaCore) analysis supported by gel filtration we have shown that C4BP does not bind CD40, but it forms stable high molecular weight complexes with soluble CD40 ligand (sCD154). These C4BP/sCD154 complexes bound efficiently to immobilised CD40, but when applied to cholangiocytes they failed to induce apoptosis or proliferation or to activate NFkB, AP-1 or STAT 3, which are activated by sCD154 alone. Thus C4BP can modulate CD40/sCD154 interactions by presenting a high molecular weight multimeric sCD154/C4BP complex that suppresses critical intracellular signalling pathways, permitting cell survival without inducing proliferation. Immunohistochemistry demonstrated co-localisation and enhanced expression of C4BP and CD40 in human liver cancers. These findings suggest a novel pathway whereby components of the complement system and TNF ligands and receptors might be involved in modulating epithelial cell survival in chronic inflammation and malignant disease

A runaway PRH/HHEX-Notch3 positive feedback loop drives cholangiocarcinoma and determines response to CDK4/6 inhibition

This is the author accepted manuscript. The final version is available from the American Association for Cancer Research via the DOI in this recordAberrant Notch and Wnt signalling are known drivers of cholangiocarcinoma (CCA) but the underlying factors that initiate and maintain these pathways are not known. Here we show that the PRH/HHEX transcription factor forms a positive transcriptional feedback loop with Notch3 that is critical in CCA. PRH/HHEX expression was elevated in CCA and depletion of PRH reduced CCA tumour growth in a xenograft model. Overexpression of PRH in primary human biliary epithelial cells was sufficient to increase cell proliferation and produce an invasive phenotype. Interrogation of the gene networks regulated by PRH and Notch3 revealed that unlike Notch3, PRH directly activated canonical Wnt signalling. These data indicate that hyperactivation of Notch and Wnt signalling is independent of the underlying mutational landscape and has a common origin in dysregulation of PRH. Moreover, they suggest new therapeutic options based on the dependence of specific Wnt, Notch, and CDK4/6 inhibitors on PRH activity.Medical Research Council (MRC)Thailand Research Fund (TRF

Upgrade of the MARI spectrometer at ISIS

The MARI direct geometry time-of-flight neutron spectrometer at ISIS has been upgraded with an m = 3 supermirror guide and new detector electronics. This has resulted in a flux gain of approximate to 6x at lambda = 1.8 angstrom, and improvements on discriminating electrical noise, allowing MARI to continue to deliver a high quality science program well into its fourth decade of life

Human resource management in the Georgian National Immunization Program: a baseline assessment

Background: Georgia's health care system underwent dramatic reform after gaining independence in 1991. The decentralization of the health care system was one of the core elements of health care reform but reports suggest that human resource management issues were overlooked. The Georgian national immunization program was affected by these reforms and is not functioning at optimum levels. This paper describes the state of human resource management practices within the Georgian national immunization program in late 2004. Methods: Thirty districts were selected for the study. Within these districts, 392 providers and thirty immunization managers participated in the study. Survey questionnaires were administered through face-to-face interviews to immunization managers and a mail survey was administered to immunization providers. Qualitative data collection involved four focus groups. Analysis of variance (ANOVA) and Chi-square tests were used to test for differences between groups for continuous and categorical variables. Content analysis identified main themes within the focus groups. Results: Weak administrative links exist between the Centres of Public Health (CPH) and Primary Health Care (PHC) health facilities. There is a lack of clear management guidelines and only 49.6% of all health providers had written job descriptions. A common concern among all respondents was the extremely inadequate salary. Managers cited lack of authority and poor knowledge and skills in human resource management. Lack of resources and infrastructure were identified as major barriers to improving immunization. Conclusion: Our study found that the National Immunization Program in Georgia was characterized by weak organizational structure and processes and a lack of knowledge and skills in management and supervision, especially at peripheral levels. The development of the skills and processes of a well-managed workforce may help improve immunization rates, facilitate successful implementation of remaining health care reforms and is an overall, wise investment. However, reforms at strategic policy levels and across sectors will be necessary to address the systemic financial and health system constraints impeding the performance of the immunization program and the health care system as a whole

Biliary epithelial senescence and plasticity in acute cellular rejection

Biliary epithelial cells (BEC) are important targets in some liver diseases, including acute allograft rejection. Although some injured BEC die, many can survive in function compromised states of senescence or phenotypic de-differentiation. This study was performed to examine changes in the phenotype of BEC during acute liver allograft rejection and the mechanism driving these changes. Liver allograft sections showed a positive correlation (p < 0.0013) between increasing T cell mediated acute rejection and the number of BEC expressing the senescence marker p21(WAF1/Cip) or the mesenchymal marker S100A4. This was modeled in vitro by examination of primary or immortalized BEC after acute oxidative stress. During the first 48 h, the expression of p21(WAF1/Cip) was increased transiently before returning to baseline. After this time BEC showed increased expression of mesenchymal proteins with a decrease in epithelial markers. Analysis of TGF-β expression at mRNA and protein levels also showed a rapid increase in TGF-β2 (p < 0.006) following oxidative stress. The epithelial de-differentiation observed in vitro was abrogated by pharmacological blockade of the ALK-5 component of the TGF-β receptor. These data suggest that stress induced production of TGF-β2 by BEC can modify liver allograft function by enhancing the de-differentiation of local epithelial cells.J.G. Brain, H. Robertson, E. Thompson, E.H. Humphreys, A. Gardner, T.A. Booth, D.E J. Jones, S.C. Afford, T. von Zglinick, A.D. Burt and J.A. Kirb

Lactoferrin is a survival factor for neutrophils in rheumatoid synovial fluid

Objectives. Lactoferrin is an iron-binding protein that is released from activated neutrophils at sites of inflammation and has anti-microbial as well as anti-inflammatory properties. This study set out to determine whether lactoferrin can delay neutrophil apoptosis and could act as a survival factor for neutrophils in SF