Intravital Dynamic and Correlative Imaging of Mouse Livers Reveals Diffusion-Dominated Canalicular and Flow-Augmented Ductular Bile Flux.

BACKGROUND AND AIMS: Small-molecule flux in tissue microdomains is essential for organ function, but knowledge of this process is scant due to the lack of suitable methods. We developed two independent techniques that allow the quantification of advection (flow) and diffusion in individual bile canaliculi and in interlobular bile ducts of intact livers in living mice, namely fluorescence loss after photoactivation and intravital arbitrary region image correlation spectroscopy. APPROACH AND RESULTS: The results challenge the prevailing "mechano-osmotic" theory of canalicular bile flow. After active transport across hepatocyte membranes, bile acids are transported in the canaliculi primarily by diffusion. Only in the interlobular ducts is diffusion augmented by regulatable advection. Photoactivation of fluorescein bis-(5-carboxymethoxy-2-nitrobenzyl)-ether in entire lobules demonstrated the establishment of diffusive gradients in the bile canalicular network and the sink function of interlobular ducts. In contrast to the bile canalicular network, vectorial transport was detected and quantified in the mesh of interlobular bile ducts. CONCLUSIONS: The liver consists of a diffusion-dominated canalicular domain, where hepatocytes secrete small molecules and generate a concentration gradient and a flow-augmented ductular domain, where regulated water influx creates unidirectional advection that augments the diffusive flux.

Association of Plasmodium berghei With the Apical Domain of Hepatocytes Is Necessary for the Parasite's Liver Stage Development.

Plasmodium parasites undergo a dramatic transformation during the liver stage of their life cycle, amplifying over 10,000-fold inside infected hepatocytes within a few days. Such a rapid growth requires large-scale interactions with, and manipulations of, host cell functions. Whereas hepatocyte polarity is well-known to be critical for liver function, little is presently known about its involvement during the liver stage of Plasmodium development. Apical domains of hepatocytes are critical components of their polarity machinery and constitute the bile canalicular network, which is central to liver function. Here, we employed high resolution 3-D imaging and advanced image analysis of Plasmodium-infected liver tissues to show that the parasite associates preferentially with the apical domain of hepatocytes and induces alterations in the organization of these regions, resulting in localized changes in the bile canalicular architecture in the liver tissue. Pharmacological perturbation of the bile canalicular network by modulation of AMPK activity reduces the parasite's association with bile canaliculi and arrests the parasite development. Our findings using Plasmodium-infected liver tissues reveal a host-Plasmodium interaction at the level of liver tissue organization. We demonstrate for the first time a role for bile canaliculi, a central component of the hepatocyte polarity machinery, during the liver stage of Plasmodium development.

Isolated cholangiolitis revealed by 18F-FDG-PET/CT in a patient with fever of unknown origin.

Cholangiolitis, inflammation of the cholangioles, is difficult to diagnose by conventional imaging modalities. We report a case of cholangiolitis revealed by fluorine-18 fluoro desoxyglucose positron emission tomography-computerized tomography ((18)F-FDG-PET/CT) after about 9 months of recurrent fevers. A 20 years old girl with a history of recurrent fevers and repeated workups at different hospitals, which didn't diagnosed the source of fever, was admitted with a recent episode of fever. An (18)F-FDG-PET/CT was requested, which demonstrated focal hypermetabolic activity in the lateral segment of the left lobe of the liver. A liver biopsy showed inflammation of small biliary ducts consistent of cholangiolitis. Enterococcus casseliflavus was found on performed cultures. This represents the first case of cholangiolitis revealed by (18)F-FDG-PET/CT imaging.

Effects of ethanol on intercellular communications and polarization of hepatocytes in short-term culture.

The formation of intracellular lumina with apical differentiation is observed in several cancerous epithelial cell lines including human hepatocarcinoma. This disorder of cell polarization can be induced by the inhibition of cell-cell communication, a known factor of carcinogenesis. This work was designed to study the effects of ethanol on the differentiation of hepatocytes in short-term culture. Isolated hepatocytes were plated on plastic culture dishes that were 35 mm in diameter (10(6) cells/dish). Three hours after plating, the hepatocytes were incubated in the presence of 20 mmol/L ethanol for 1 hr. Treated cells were compared with controls using morphometric methods after conventional treatment for ultramicroscopy and by measuring cellular dye coupling by the fluorescent Lucifer Yellow CH transfer method. Bile canaliculi formation decreased in alcohol-treated cells (6.5% vs. 9.9%, 2p less than 0.05), whereas intracellular lumina incidence increased (3.1% vs. 0.5%, 2p less than 0.01). In parallel, the dye-coupling capacity decreased significantly when hepatocytes were treated with alcohol (2p less than 0.01). This work shows that short-term ethanol treatment induces significant disturbances of cell polarization and inhibits the reestablishment of cell-cell communication in cultured hepatocytes. These disorders could, at least in part, explain the carcinogenic effects of ethanol.