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Engineering viral vectors to produce liver-specific protein expression may help advance understanding of hepatic regeneration and disease states. In addition to introducing genes of interest to the liver, these vectors can be adapted for gene deletion when designed to express Cre recombinase. The ability to use this system requires high, liverrestricted expression, low toxicity, and no effect on the process of interest. We developed an adeno-associated virus 8 (AAV8) with a codon-optimized Cre recombinase under a hepatocyte-specific major urinary protein (MUP) promoter (MUP-iCre-AAVS) that fulfills these requirements. A single intravenous injection of ROSA26R reporter mice, which express lacZ after Cre-mediated recombination, demonstrated homogeneous [beta]-galactosidase expression limited to hepatocytes after only 7 days. Cre protein expression remained strong for at least 31 days. Serum liver function tests and histology demonstrated minimal liver toxicity. The presence of MUP-iCre-AAV8 did not affect hepatocyte proliferation after partial hepatectomy as measured by Ki67 staining. Conclusion: AAV8 with the MUP promoter, by virtue of its lack of hepatic toxicity or effect on liver regeneration, may be an efficient alternative to complex transgenic methodologies for studies of the mouse liver. hepatotoxicity; Cre recombinase

Growth hormone (GH) function is mediated through multiple endocrine pathways. In the liver, GH also transcriptionally activates hepatocyte nuclear factor-6 (HNF-6; OC-1), a liver-enriched transcription factor that regulates the expression of genes essential to hepatic function. We hypothesize that GH modulates hepatic function in the normal and injured liver through HNF-6 and HNF-6 target genes. CD1 mice received PBS or GH for the 1-, 7-, and 28-day course of Sham operation or bile duct ligation (BDL). Proliferation-, metabolic-, and profibrotic-specific hepatic functions were assessed with a focus on candidate HNF-6 transcriptional target genes. Confirmation of HNF-6 regulation was done by analysis of target gene expression in liver infected with recombinant adenovirus AdHNF-6 expression vectors. GH administration upregulated HNF-6 expression throughout the course of liver injury. This was associated with increased expression of HNF-6 proliferative target genes cyclin D1 and metabolic gene Cyp7A1 and downregulation of profibrogenic TGFb2R. Hepatic function improved such as enhanced hepatocyte proliferation, higher cholesterol clearance throughout the course of injury, and attenuated fibrogenic response at day 28 of BDL. GH treatment also transcriptionally increased albumin expression in an HNF-6-independent manner. This was associated with enhanced serum albumin levels. In conclusion, the GH/HNF-6 axis is a potential in vivo mechanism underlying GH diverse function in the liver to modulate the liver repair response to BDL. bile duct ligation; liver regeneration; liver fibrosis; cholestasis; cholesterol metabolism; cyclin D1; Cyp7A1; TGFb2R

Despite efforts spanning four decades, the therapeutic potential of thyroid hormone receptor (TR) agonists as lipid-lowering and anti-obesity agents remains largely unexplored in humans because of dose-limiting cardiac effects and effects on the thyroid hormone axis (THA), muscle metabolism, and bone turnover. TR agonists selective for the TR[beta] isoform exhibit modest cardiac sparing in rodents and primates but are unable to lower lipids without inducing TR[beta]-mediated suppression of the THA. Herein, we describe a cytochrome P450-activated prodrug of a phosphonate-containing TR agonist that exhibits increased TR activation in the liver relative to extrahepatic tissues and an improved therapeutic index. Pharmacokinetic studies in rats demonstrated that the prodrug (2R,4S)-4-(3-chlorophenyl)-2-[(3, 5-dimethyl-4-(4'-hydroxy-3'-isopropylbenzyl)phenoxy)methyl]-2-oxido-[1, 3,2]-dioxaphosphonane (MB07811) undergoes first-pass hepatic extraction and that cleavage of the prodrug generates the negatively charged TR agonist (3,5-dimethyl-4-(4'-hydroxy-3'-isopropylbenzyl)phenoxy)methylphosphonic acid (MB07344), which distributes poorly into most tissues and is rapidly eliminated in the bile. Enhanced liver targeting was further demonstrated by comparing the effects of MB07811 with 3,503'-triiodo-L-thyronine ([T.sub.3]) and a non-liver-targeted TR agonist, 3,5-dichloro-4-(4-hydroxy-3-isopropylphenoxy)phenylacetic acid (KB-141) on the expression of TR agonist-responsive genes in the liver and six extrahepatic tissues. The pharmacologic effects of liver targeting were evident in the normal rat, where MB07811 exhibited increased cardiac sparing, and in the diet-induced obese mouse, where, unlike KB-141, MB07811 reduced cholesterol and both serum and hepatic triglycerides at doses devoid of effects on body weight, glycemia, and the THA. These results indicate that targeting TR agonists to the liver has the potential to lower both cholesterol and triglyceride levels with an acceptable safety profile. cardiac sparing | hepatic steatosis | hyperlipidemia | (2R,4S)-4-(3-chlorophenyl)-2-[(3,5-dimethyl-4-(4'-hydroxy-3'- isopropylbenzyl)--phenoxy)methyl]-2-oxido-[1,3,2]-dioxaphosphonane (MB07811) | thyroid hormone axis

Liver receptor homolog-1 (LRH-1) is a nuclear receptor involved in intestinal lipid homeostasis and cell proliferation. Here we show that haploinsufficiency of LRH-1 predisposes mice to the development of intestinal inflammation. Besides the increased inflammatory response, LRH-1 heterozygous mice exposed to 2,4,6-trinitrobenzene sulfonic acid show lower local corticosterone production as a result of an impaired intestinal expression of the enzymes CYP11A1 and CYP11B1, which control the local synthesis of corticosterone in the intestine. Local glucocorticoid production is strictly enterocyte-dependent because it is robustly reduced in epithelium-specific LRH-1-deficient mice. Consistent with these findings, colon biopsies of patients with Crohn's disease and ulcerative colitis show reduced expression of LRH-1 and genes involved in the production of glucocorticoids. Hence, LRH-1 regulates intestinal immunity in response to immunological stress by triggering local glucocorticoid production. These findings underscore the importance of LRH-1 in the control of intestinal inflammation and the pathogenesis of inflammatory bowel disease. Crohn's disease | inflammation | nuclear receptors | steroidogenesis | ulcerative colitis

Erythropoietic protoporphyria is a disorder of heme synthesis in which deficient ferrochelatase activity leads to excess production and biliary excretion of protoporphyrin. The main clinical features, photosensitivity and hepatobiliary disease that may progress to liver failure, are caused by the toxicity of protoporphyrin. Liver transplantation has been used to treat liver failure in erythropoietic protoporphyria, but excess production of protoporphyrin by the bone marrow continues causing recurrence of liver disease in the majority of patients. This is the first report of successful sequential liver and bone marrow transplantation in a patient with liver failure as a result of erythropoietic protoporphyria. This combination corrected the severe phenotype, resolving the severe photosensitivity and halting erythropoietic protoporphyria associated liver graft injury. Splenectomy seemed to facilitate the successful bone marrow transplant. KEY WORDS. liver transplantation, bone marrow transplantation, porphyria. PEDIATRICS 2006;118:e1896-e1899. URL: www.pediatrics.org/cgi/doi/10.1542/peds.2006-0833, Elizabeth B. Rand, MD, Nancy Bunin, MD, William Cochran, MD, Eduardo Ruchelli, MD, Kim M. Olthoff, MD, Joseph R. Bloomer, [...]

Multiple cutaneous hemangiomas can be associated with internal hemangiomas, with the liver being the most common site. Here we report a case of a premature female neonate who presented with cardiac failure at birth and had typical-appearing infantile hemangiomas on the skin in association with vascular lesions in the liver. Her clinical presentation was felt to be consistent with cutaneous and hepatic infantile hemangiomas. After failure to respond to systemic steroids and chemotherapy, she underwent liver transplantation. Histopathologic evaluation of the liver revealed a diagnosis of type 2 infantile hepatic hemangioendothelioma (regarded as synonymous with angiosarcoma) rather than benign infantile hemangioma of the liver. Subsequent skin biopsies confirmed that her multiple cutaneous lesions were infantile hemangiomas and not metastatic angiosarcoma. We report this case and a review of the literature on pediatric angiosarcoma of the liver associated with cutaneous infantile hemangiomas. KEY WORDS. hemangioma, neoplasm, liver transplantation., Kristin M. Nord, MD, Jessica Kandel, MD, Jay H. Lefkowitch, MD, Steven J. Lobritto, MD, Kimberly D. Morel, MD, Paula E. North, MD, PhD, Maria C. Garzon, [...]