Liver complications in inflammatory bowel diseases.

Diseases of the liver and the biliary tract are commonly observed in patients with inflammatory bowel diseases (IBD). Besides primary sclerosing cholangitis (PSC), drug-induced hepatotoxicity and non-alcoholic fatty liver disease (NAFLD) are the most frequent liver complications in IBD. PSC is a chronic inflammatory and commonly progressive disorder of unknown etiology associated with fibrosis and stricture development in the intrahepatic and extrahepatic biliary tree. Interestingly, this form of liver disease is mainly associated with ulcerative colitis. Development of PSC is highly relevant for IBD patients as cholestasis-associated problems increase over time resulting in biliary strictures, cholangitis, cholangiocarcinoma and importantly these patients also have a higher risk to develop colon cancer. Another major aspect regarding IBD and liver disease refers to drug-induced hepatotoxicity. Clinically, most relevant is liver toxicity caused by immunosuppressants such as azathioprine. Azathioprine and its derivate 6-mercaptopurine can cause a spectrum of liver injuries ranging from asymptomatic elevated liver enzymes to cholestasis and nodular regenerative hyperplasia. The third common IBD-associated liver disease is NAFLD, and first studies suggest that NAFLD might appear in IBD patients independent of classical risk factors such as obesity or insulin resistance. Overall, liver complications are observed in 10-20% of IBD patients, and therefore physicians have to be familiar with these complications to improve and to optimize patient care.

Adiponectin: key player in the adipose tissue-liver crosstalk.

The adipose tissue has recently emerged as an important endocrine organ releasing numerous mediators including adipocytokines, classical cytokines and others. Adiponectin, one of the major products of adipocytes, is a prototypic anti-diabetic adipocytokine, the actions of which are mainly exerted by the activation of AMP-activated kinase and peroxisome proliferator-activated receptor alpha. This adipocytokine is one of the most abundant circulating (adipo)cytokines in health. Non-alcoholic fatty liver disease (NAFLD), the major reason for abnormal liver functions in the western world, is commonly associated with obesity, insulin resistance and decreased adiponectin serum levels. Adiponectin has many anti-inflammatory activities and suppresses tumour necrosis factor-alpha (TNFα), a cytokine of key importance in NAFLD. The anti-inflammatory effects of adiponectin are also exerted by induction of the anti-inflammatory cytokines interleukin-10 (IL-10) or IL-1 receptor antagonist and up-regulation of heme-oxygenase-1. Whereas the liver probably is not a relevant source of circulating adiponectin, it is a major target organ for many adiponectin effects. Adiponectin is able to regulate steatosis, insulin resistance, inflammation and fibrosis. NAFLD is also associated with decreased liver expression of the two adiponectin receptors (AdipoR1 and 2) thereby contributing to a state of hepatic adiponectin resistance. In contrast, most other liver diseases especially in advanced disease states exhibit increased adiponectin serum levels with highest levels observed in cirrhosis. Targeting adiponectin could evolve as a major treatment concept especially for fatty liver diseases in the future.

Immunogenicity and safety of defective vaccinia virus lister: comparison with modified vaccinia virus Ankara.

Potent and safe vaccinia virus vectors inducing cell-mediated immunity are needed for clinical use. Replicating vaccinia viruses generally induce strong cell-mediated immunity; however, they may have severe adverse effects. As a vector for clinical use, we assessed the defective vaccinia virus system, in which deletion of an essential gene blocks viral replication, resulting in an infectious virus that does not multiply in the host. The vaccinia virus Lister/Elstree strain, used during worldwide smallpox eradication, was chosen as the parental virus. The immunogenicity and safety of the defective vaccinia virus Lister were evaluated without and with the inserted human p53 gene as a model and compared to parallel constructs based on modified vaccinia virus Ankara (MVA), the present "gold standard" of recombinant vaccinia viruses in clinical development. The defective viruses induced an efficient Th1-type immune response. Antibody and cytotoxic-T-cell responses were comparable to those induced by MVA. Safety of the defective Lister constructs could be demonstrated in vitro in cell culture as well as in vivo in immunodeficient SCID mice. Similar to MVA, the defective viruses were tolerated at doses four orders of magnitude higher than those of the wild-type Lister strain. While current nonreplicating vectors are produced mainly in primary chicken cells, defective vaccinia virus is produced in a permanent safety-tested cell line. Vaccines based on this system have the additional advantage of enhanced product safety. Therefore, a vector system was made which promises to be a valuable tool not only for immunotherapy for diseases such as cancer, human immunodeficiency virus infection, or malaria but also as a basis for a safer smallpox vaccine.

Dominant host range selection of vaccinia recombinants by rescue of an essential gene.

We report the rescue of a defective vaccinia virus, forming the basis for a stringent selection protocol to generate replicating recombinant virus without the need for marker cassettes and selection agents. Plaques of recombinant virus could be isolated solely by their ability to grow in wild-type cells normally supporting the growth of vaccinia virus. All growth-competent clones analyzed contained the gene of interest in the intended genomic locus and displayed foreign gene expression to the same levels as was seen with classical recombinants obtained by insertion into the vaccinia virus thymidine kinase locus. The system is based on a defective vaccinia virus, expressing exclusively early genes, termed eVAC-1, and an insertion plasmid vector providing the essential function, the uracil DNA glycosylase gene. In addition, the defective virus is free of selection and color marker genes, thus also representing a basic vector for the generation of defective recombinants.