The pathophysiology of human obstructive cholestasis is mimicked in cholestatic Gold Syrian hamsters.

Obstructive cholestasis causes liver injury via accumulation of toxic bile acids (BAs). Therapeutic options for cholestatic liver disease are limited, partially because the available murine disease models lack translational value. Profiling of time-related changes following bile duct ligation (BDL) in Gold Syrian hamsters revealed a biochemical response similar to cholestatic patients in terms of BA pool composition, alterations in hepatocyte BA transport and signaling, suppression of BA production, and adapted BA metabolism. Hamsters tolerated cholestasis well for up to 28days and progressed relatively slowly to fibrotic liver injury. Hepatocellular necrosis was absent, which coincided with preserved intrahepatic energy levels and only mild oxidative stress. The histological response to cholestasis in hamsters was similar to the changes seen in 17 patients with prolonged obstructive cholestasis caused by cholangiocarcinoma. Hamsters moreover upregulated hepatic fibroblast growth factor 15 (Fgf15) expression in response to BDL, which is a cytoprotective adaptation to cholestasis that hitherto had only been documented in cholestatic human livers. Hamster models should therefore be added to the repertoire of animal models used to study the pathophysiology of cholestatic liver disease.

Fluid restriction reduces pulmonary edema in a model of acute lung injury in mechanically ventilated rats.

Experimental acute lung injury models are often used to increase our knowledge on the acute respiratory distress syndrome (ARDS), however, existing animal models often do not take into account the impact of specific fluid strategies on the development of lung injury. In contrast, the current literature strongly suggests that fluid management strategies have a significant impact on clinical outcome of patients with ARDS. Thus, it is important to characterize the role of fluid management strategies in experimental models of lung injury. In this study we investigated the effect of two different fluid strategies on commonly used outcome variables in a short-term model of acute lung injury, in relation to age. Infant (2-3 weeks) and adult (3-4 months) Wistar rats received intratracheal instillations of lipopolysaccharide and 24 hours later were mechanically ventilated for 6 hours. During mechanical ventilation, rats from both age groups were randomized to either a standard or conservative intravenous fluid strategy. We found that the hemodynamic response in infant and adult rats was similar in both fluid strategies. Lung wet-to-dry ratios were lower in adult, but not in infant rats receiving the conservative fluid strategy as compared to the standard fluid strategy. There were age-related differences in markers of alveolar capillary barrier disruption and alveolar fluid clearance, yet these were unaffected by fluid strategy. Finally, we found significantly higher IL-1ß and TNF-α concentrations in the adult rats treated with the conservative as compared to the standard fluid regimen. In conclusion, the choice of fluid strategy in mechanically ventilated rats with experimental LPS-induced acute lung injury has a significant effect on pulmonary extravascular water, an important and well-recognized lung injury marker, and on the local pro-inflammatory cytokine profiles. We advocate the use of a more uniform, conservative, fluid strategy regimen in experimental models of acute lung injury.

The damage-associated molecular pattern HMGB1 is released early after clinical hepatic ischemia/reperfusion.

OBJECTIVE AND BACKGROUND: Activation of sterile inflammation after hepatic ischemia/reperfusion (I/R) culminates in liver injury. The route to liver damage starts with mitochondrial oxidative stress and cell death during early reperfusion. The link between mitochondrial oxidative stress, damage-associate molecular pattern (DAMP) release, and sterile immune signaling is incompletely understood and lacks clinical validation. The aim of the study was to validate this relation in a clinical liver I/R cohort and to limit DAMP release using a mitochondria-targeted antioxidant in I/R-subjected mice. METHODS: Plasma levels of the DAMPs high-mobility group box 1 (HMGB1), mitochondrial DNA, and nucleosomes were measured in 39 patients enrolled in an observational study who underwent a major liver resection with (N = 29) or without (N = 13) intraoperative liver ischemia. Circulating cytokine and neutrophil activation markers were also determined. In mice, the mitochondria-targeted antioxidant MitoQ was intravenously infused in an attempt to limit DAMP release, reduce sterile inflammation, and suppress I/R injury. RESULTS: In patients, HMGB1 was elevated following liver resection with I/R compared to liver resection without I/R. HMGB1 levels correlated positively with ischemia duration and peak post-operative transaminase (ALT) levels. There were no differences in mitochondrial DNA, nucleosome, or cytokine levels between the two groups. In mice, MitoQ neutralized hepatic oxidative stress and decreased HMGB1 release by ±50%. MitoQ suppressed transaminase release, hepatocellular necrosis, and cytokine production. Reconstituting disulfide HMGB1 during reperfusion reversed these protective effects. CONCLUSION: HMGB1 seems the most pertinent DAMP in clinical hepatic I/R injury. Neutralizing mitochondrial oxidative stress may limit DAMP release after hepatic I/R and reduce liver damage.

IL-23 and IL-17A are not involved in hepatic/ischemia reperfusion injury in mouse and man.

BACKGROUND: Hepatic ischemia and reperfusion (I/R) is common in liver surgery and transplantation and compromises postoperative liver function. Hepatic I/R injury is characterized by sterile inflammation that contributes to hepatocellular necrosis. Many immune cells and cytokines have been implicated in hepatic I/R injury. However, the role and relevance of IL-23 and IL-17A remains controversial in literature. Aim: To determine whether the IL-23/IL-17A signaling axis is activated in hepatic I/R using a triple-level experimental approach (in vitro, in vivo, and clinical). METHODS: IL-23 and IL-17A were assayed by ELISA in the supernatant fractions of cultured murine (RAW 264.7) macrophages that were activated by supernatant fractions of necrotic cultured mouse (AML12) hepatocytes. Similarly, levels of these cytokines were determined in plasma samples and liver tissue of mice (N = 85) subjected to partial (70%) liver I/R. Finally, IL-23 and IL-17A were assayed in plasma samples obtained from a controlled cohort of liver resection patients who were either subjected to I/R (N = 27) or not (N = 13). RESULTS: Activated macrophages did not produce IL-23 in response to supernatant of necrotic AML12 hepatocytes. IL-23 and IL-17A were not elevated in mice subjected hepatic I/R and were not elevated in serum from patients subjected to I/R during liver resection. CONCLUSION: IL-23 and IL-17A are not involved in hepatic I/R injury in mouse and man. RELEVANCE FOR PATIENTS: If IL-23 and IL-17A were to mediate hepatocellular injury following I/R, these cytokines would constitute potential therapeutic targets. Since this study has revealed that IL-23 and IL-17A do not play a role in hepatic I/R, other pathways and therapeutic targets should be considered when developing modalities aimed at reducing hepatic I/R injury.

Liver progenitor cell line HepaRG differentiated in a bioartificial liver effectively supplies liver support to rats with acute liver failure.

A major roadblock to the application of bioartificial livers is the need for a human liver cell line that displays a high and broad level of hepatic functionality. The human bipotent liver progenitor cell line HepaRG is a promising candidate in this respect, for its potential to differentiate into hepatocytes and bile duct cells. Metabolism and synthesis of HepaRG monolayer cultures is relatively high and their drug metabolism can be enhanced upon treatment with 2% dimethyl sulfoxide (DMSO). However, their potential for bioartificial liver application has not been assessed so far. Therefore, HepaRG cells were cultured in the Academic Medical Center bioartificial liver (AMC-BAL) with and without DMSO and assessed for their hepatic functionality in vitro and in a rat model of acute liver failure. HepaRG-AMC-BALs cultured without DMSO eliminated ammonia and lactate, and produced apolipoprotein A-1 at rates comparable to freshly isolated hepatocytes. Cytochrome P450 3A4 transcript levels and activity were high with 88% and 37%, respectively, of the level of hepatocytes. DMSO treatment of HepaRG-AMC-BALs reduced the cell population and the abovementioned functions drastically. Therefore, solely HepaRG-AMC-BALs cultured without DMSO were tested for efficacy in rats with acute liver failure (n = 6). HepaRG-AMC-BAL treatment increased survival time of acute liver failure rats ∼50% compared to acellular-BAL treatment. Moreover, HepaRG-AMC-BAL treatment decreased the progression of hepatic encephalopathy, kidney failure, and ammonia accumulation. These results demonstrate that the HepaRG-AMC-BAL is a promising bioartificial liver for clinical application.

Portal vein embolization induces more liver regeneration than portal vein ligation in a standardized rabbit model.

BACKGROUND: Portal vein ligation (PVL) and portal vein embolization (PVE) are used to induce hypertrophy of the future remnant liver before major liver resection. The aim of our study was to compare the hypertrophy response of the liver after PVL versus PVE in a rabbit model. METHODS: Twenty rabbits were divided into an embolization group (n = 10) and a ligation group (n = 10). Both groups were divided in 2 subgroups of 5 rabbits that were humanely killed after days 7 and 14. The portal vein branches to the 3 cranial liver lobes (80% of the liver) were occluded. Regeneration of the caudal liver lobe was measured using volumetry based on computed tomography on days 3, 7, 10, and 14. Immunohistochemistry for Ki-67 and RAM11 was performed to quantify proliferating cells and macrophages. In addition, tissue tumor necrosis factor-α and interleukin-6 were assessed. RESULTS: The caudal liver volume increased over time in both groups (P < .001), but this increase was greater after PVE than after PVL (P = .001) with a mean degree of hypertrophy of 15% ± 4% and 20% ± 2%, respectively. When comparing the groups on the separate time points, a difference was found on days 10 and 14 (P = .008 and P = .016, respectively). These data were confirmed by Ki-67 staining, which showed a greater number of proliferating hepatocytes on day 7 after embolization (P = .016). Cytokine analysis of liver tissue did not show significant differences between the ligation and embolization groups on days 7 and 14. CONCLUSION: PVE is superior to PVL in terms of the extent of the hypertrophy response in this rabbit model.