The aim of this study was to determine the effect of adoptive transfer of regulatory natural killer T (NKT) lymphocytes on the metabolic disorder in leptin-deficient ob/ob mice, which feature depletion and defective function of NKT and CD4 lymphocytes. Leptin-deficient ob/ob mice were subjected to transplantation of 1 x 10(6) of either ob/ob or wild-type-derived NKT lymphocytes, or to transplantation of either ob/ob or wild-type-derived splenocytes. The effect on hepatic fat content was measured by magnetic resonance imaging (signal intensity index) and histology, using the steatohepatitis grading scale. The degree of glucose intolerance was measured by an oral glucose tolerance test (GTT). Adoptive transfer of wild-type or ob/ob-derived regulatory NKT cells led to a 12% decrease in hepatic fat content. A significant histological shift from macrosteatosis to microsteatosis was observed. Marked improvement in the GTT was noted in wild-type or ob/ob-derived NKT recipients. Metabolic effects were associated with a significant decrease in peripheral and intrahepatic CD4/CD8 lymphocyte ratios. Intrahepatic CD8 trapping was observed in all responders. Serum interleukin 10 levels decreased significantly. In conclusion, adoptive transfer of a relatively small number of regulatory NKT lymphocytes into ob/ob mice results in a significant reduction in hepatic fat content, a shift from macro to microsteatosis, and significant improvement in glucose intolerance. These effects were associated with decreased peripheral and intrahepatic CD4/CD8 ratios and decreased interleukin 10 levels. The results further support a role for regulatory NKT lymphocytes in the pathogenesis of non-alcoholic steatohepatitis in the leptin-deficient murine model.

Glucocerebroside (GC) is a naturally occurring glycolipid that may alter natural killer T (NKT) cell function. To determine the effect of GC on the metabolic derangements and immune profile in leptin-deficient mice, Ob/Ob mice were treated by daily injections of GC for 8 weeks and followed for various metabolic and immunological parameters. Marked amelioration of the metabolic alterations characteristic of leptin-deficient mice was observed in GC-treated animals compared with controls. A significant decrease in liver size and hepatic fat content were observed in GC-treated mice. Near-normalization of glucose tolerance and decreased serum triglyceride levels were observed. Fluorescence-activated cell sorting analysis of peripheral and intrahepatic lymphocytes revealed a 1.6-fold increase of the peripheral/intrahepatic NKT lymphocyte ratio. A 33% decrease of serum interferon-␥ level and a 2.6-fold increase of serum interleukin 10 level were noted in GC-treated mice. Immune modulation by GC may have a role in the treatment of nonalcoholic steatohepatitis and other immune-mediated disorders.

The particle-bound RNA polymerase activity of vesicular stomatitis virus (VSV) can be demonstrated in vivo. Linear synthesis of viral RNA persists for 5 to 6 hours at 34 degrees C in infected monolayers of chick embryo cells treated with cycloheximide and actinomycin D to block synthesis of protein and cell-specific RNA. At least 55 percent of the RNA made under these conditions is complementary to virion RNA. RNA synthesis mediated by VSV polymerase activity is inhibited in cells first treated with chick-derived interferon or polyriboinosinate* polyribocytidylate, but not by mouse interferon. The RNA product of VSV polymerase activity is present throughout the cytoplasm, and its synthesis is inhibited by the interferon system, as judged by autoradiographs that show the physical distribution, in cells, of RNA produced by virion polymerase in the absence of translation-a demonstration of the transcription product of the viral genome.

Concanavalin A (ConA) induces natural killer T (NKT) cell-mediated liver damage. Glucocerebroside (GC) is a naturally occurring glycolipid. Our aims were to determine the effect of GC in a murine model of ConA-induced hepatitis. Mice in groups A and B were treated with GC 2 h before and 2 h following administration of ConA, respectively; group C mice were treated with ConA; group D mice was treated with GC; group E mice did not receive any treatment. Liver damage was evaluated by serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and liver histology. The immune effect of GC was determined by fluorescence-activated cell sorter analysis of intrahepatic and intrasplenic NKT lymphocytes, measurement of cytokine levels, and Western blot analysis for STAT 1, 4, 6, and NF-kappaB expression. The effect of GC on NKT cell proliferation was assessed in vitro. Serum AST and ALT levels were markedly reduced in GC-treated group A mice compared with nontreated group C animals, and histological damage was markedly attenuated in group A. The beneficial effect of GC was associated with a 20% decrease of intrahepatic NKT lymphocytes, significant lowering of serum IFN-gamma levels, and decreased STAT1 and STAT6 expression. In vitro administration of GC led to a 42% decrease of NKT cell proliferation in the presence of dendritic cells but not in their absence. Intraperitoneally administered radioactive GC was detected in the liver and bowel. Administration of GC led to amelioration of ConA hepatitis associated with an inhibitory effect on NKT lymphocytes. GC holds promise as a new immune-modulatory agent.

Development of new therapies for human hepatitis B virus infection (HBVHepatitis B virus (HBV) is a major cause of morbidity, that affects as many as 350 million people worldwide, resulting in an estimated 2 million deaths per year. 1,2 Currently available therapies for HBV-related hepatitis have limited success. 3 Therefore, new antiviral therapies that inhibit HBV replication or gene expression are being developed. Severe adverse reactions to nucleoside analogues in recent clinical trials 4,5 underscore the need for a small animal model to screen the safety and efficacy of new therapeutic modalities. Because of the narrow host range of HBV, existing animal models are limited to chimpanzees 6 and the recently reported tupaia, 7-10 which are expensive and in short supply. Related hepadnaviridae, duck HBV, 11 and woodchuck HBV, 12 infect their respective natural hosts; however, these viruses are of limited relevance to human HBV infection because of significant structural divergence among the viruses. 13,14 For these reasons, it would be advantageous to have a small animal model for human HBV.In efforts to produce murine models of HBV viremia, other investigators have transferred HBV to mice as a transgene, or by ectopic transplantation of human tumor cell lines producing HBV. HBV transgenic mice produce virus from HBV DNA, which is integrated into mouse chromosomes of all mouse cells. 15 Viral replication and production of all viral antigens have been shown in this model. Disadvantages of transgenic mice include the production of HBV in mouse hepatocytes but not in human hepatocytes, the absense of covalently closed circular DNA (CCC) viral transcription templates, and vertical rather than horizontal transmission of the virus. The other available murine model is the immunodeficient mouse with ectopically transplanted human tumor cell lines containing or producing HBV. 16,17 BALB/c nude mice injected with PLC/PRF/5 tumor cells subcutaneously were shown 2 decades ago to produce tumors, secrete HBsAg, and contain HBV DNA, however their life span and usefulness are restricted by the tumor growth. HepG2.2.15 tumor cell lines subcutaneously injected in SCID mice 17 replicate HBV and secrete viral markers. This model is limited by the ectopic location of the human tumor cells and by their transformed phenotype, both of which prevent normal interactions of engrafted cells with host hepatocytes. Furthermore, human tumor growth in the host mice limits their survival to only a few weeks. 17,18 We developed an immortalized, but nontumorigenic human hepatocyte clone by stable transfection of the HBV genome, which expresses HBV antigens and replicates virus.