Lineage tracing demonstrates no evidence of cholangiocyte epithelial-to-mesenchymal transition in murine models of hepatic fibrosis.

UNLABELLED: Whether or not cholangiocytes or their hepatic progenitors undergo an epithelial-to-mesenchymal transition (EMT) to become matrix-producing myofibroblasts during biliary fibrosis is a significant ongoing controversy. To assess whether EMT is active during biliary fibrosis, we used Alfp-Cre × Rosa26-YFP mice, in which the epithelial cells of the liver (hepatocytes, cholangiocytes, and their bipotential progenitors) are heritably labeled at high efficiency with yellow fluorescent protein (YFP). Primary cholangiocytes isolated from our reporter strain were able to undergo EMT in vitro when treated with transforming growth factor-ß1 alone or in combination with tumor necrosis factor-α, as indicated by adoption of fibroblastoid morphology, intracellular relocalization of E-cadherin, and expression of α-smooth muscle actin (α-SMA). To determine whether EMT occurs in vivo, we induced liver fibrosis in Alfp-Cre × Rosa26-YFP mice using the bile duct ligation (BDL) (2, 4, and 8 weeks), carbon tetrachloride (CCl(4) ) (3 weeks), and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC; 2 and 3 weeks) models. In no case did we find evidence of colocalization of YFP with the mesenchymal markers S100A4, vimentin, α-SMA, or procollagen 1α2, although these proteins were abundant in the peribiliary regions. CONCLUSION: Hepatocytes and cholangiocytes do not undergo EMT in murine models of hepatic fibrosis.

Evidence for the epithelial to mesenchymal transition in biliary atresia fibrosis.

The epithelial to mesenchymal transition has recently been implicated as a source of fibrogenic myofibroblasts in organ fibrosis, particularly in the kidney. There is as yet minimal evidence for the epithelial to mesenchymal transition in the liver. We hypothesized that this process in biliary epithelial cells plays an important role in biliary fibrosis and might be found in patients with especially rapid forms, such as is seen in biliary atresia. We therefore obtained liver tissue from patients with biliary atresia as well as a variety of other pediatric and adult liver diseases. Tissues were immunostained with antibodies against the biliary epithelial cell marker CK19 as well as with antibodies against proteins characteristically expressed by cells undergoing the epithelial to mesenchymal transition, including fibroblast-specific protein 1, the collagen chaperone heat shock protein 47, the intermediate filament protein vimentin, and the transcription factor Snail. The degree of colocalization was quantified using a multispectral imaging system. We observed significant colocalization between CK19 and other markers of the epithelial to mesenchymal transition in biliary atresia as well as other liver diseases associated with significant bile ductular proliferation, including primary biliary cirrhosis. There was minimal colocalization seen in healthy adult and pediatric livers, or in livers not also demonstrating bile ductular proliferation. Multispectral imaging confirmed significant colocalization of the different markers in biliary atresia. In conclusion, we present significant histologic evidence suggesting that the epithelial to mesenchymal transition occurs in human liver fibrosis, particularly in diseases such as biliary atresia and primary biliary cirrhosis with prominent bile ductular proliferation.

Blood glucose is correlated with cerebrospinal fluid neurotransmitter metabolites.

Medications which influence monoaminergic neurotransmission can also have an effect on glucose regulation. In order to better understand the role of central monoaminergic neurotransmission in blood glucose homeostasis, we explored the relation between blood glucose and cerebrospinal fluid metabolite concentrations of monoaminergic neurotransmitters. Under stringently controlled resting conditions, we measured fasting blood glucose and performed lumbar punctures on 41 healthy participants. Peripheral blood glucose concentrations were significantly correlated with the cerebrospinal fluid concentrations of the dopamine metabolite, homovanillic acid and the noradrenaline metabolite, 3-methoxy-4-hydroxyphenylglycol. These correlations may represent a homeostatic relation between brain neurotransmitter activity and blood glucose.

Long-term abstinent alcoholics have a blunted blood glucose response to 2-Deoxy-d-glucose.

AIMS: In this study we explored the relationship between alcohol and carbohydrate consumption in long-term abstinent alcoholics. METHODS: We employed an established laboratory paradigm which allowed us to stimulate and measure dietary intake. 2-Deoxy-d-glucose (2-DG) is a glucose analogue that causes an intracellular energy deprivation resulting in exaggerated food consumption and a compensatory metabolic response to raise blood glucose. Using a double-blind design, we gave an infusion of 25 mg/kg 2-DG or placebo to 20 long-term abstinent alcoholics and 19 healthy volunteers. RESULTS: There were no baseline differences in any dietary, behavioural or biochemical variables. As expected, 2-DG increased caloric consumption and blood glucose levels in a time-dependent fashion. There were no differences in food consumption between the alcoholics and the healthy volunteers following the 2-DG stimulus. However, the alcoholic group had a significantly blunted response in blood glucose. CONCLUSIONS: The origin of this atypical blood glucose response may antedate the onset of alcoholism, or it may be secondary to alcohol-related damage that persists beyond 6 months. Previous accounts of increased sweet consumption in alcoholics were not substantiated, although they may be present in the peri-withdrawal period.