Ye-Dong Fan

Increased Glucocorticoid Receptor Expression and Activity Mediate the LPS Resistance of SPRET/EI Mice

SPRET/Ei mice are extremely resistant to acute LPS-induced lethal inflammation when compared with C57BL/6. We found that in vivo SPRET/Ei mice exhibit strongly reduced expression levels of cytokines and chemokines. To investigate the role of the potent anti-inflammatory glucocorticoid receptor (GR) in the SPRET/Ei phenotype, mice were treated with the GR antagonist RU486 or bilateral adrenalectomy. Under such conditions, both C57BL/6 and SPRET/Ei mice were strongly sensitized to LPS, and the differences in LPS response between SPRET/Ei and C57BL/6 mice were completely gone. These results underscore the central role of GR in the LPS hyporesponsiveness of SPRET/Ei mice. Compared with C57BL/6, SPRET/Ei mice were found to express higher GR levels, which were reflected in increased GR transactivation. Using a backcross mapping strategy, we demonstrate that the high GR transcription levels are linked to the Nr3c1 (GR) locus on chromosome 18 itself. Unexpectedly, SPRET/Ei mice exhibit a basal overactivation of the hypothalamic-pituitary-adrenal axis, namely strongly increased corticosterone levels, ACTH levels, and adrenocortical size. As a consequence of the excess of circulating glucocorticoids (GCs), levels of hepatic gluconeogenic enzymes are increased, and insulin secretion from pancreatic β-cells is impaired, both of which result in hyperglycemia and glucose intolerance in SPRET/Ei mice. We conclude that SPRET/Ei mice are unique as they display an unusual combination of elevated GR expression and increased endogenous GC levels. Hence, these mice provide a new and powerful tool for the study of GR- and GC-mediated mechanisms, including immune repressive functions, neuroendocrine regulation, insulin secretion, and carbohydrate metabolism.

Alteration of N -glycome in diethylnitrosamine-induced hepatocellular carcinoma mice: a non-invasive monitoring tool for liver cancer

Background and aims: There is a demand for serum markers that can routinely assess the progression of liver cancer. DENA (diethylnitrosamine), a hepatocarcinogen, is commonly used in an experimental mouse model to induce liver cancer that closely mimics a subclass of human hepatocellular carcinoma (HCC). However, blood monitoring of the progression of HCC in mouse model has not yet been achieved. In this report, we studied glycomics during the development of mouse HCC induced by DENA.

Expression of placental growth factor in regenerating livers after partial hepatectomy in the rat.

Background/aims Placental growth factor (PlGF) is known for its role in pathological conditions to protect parenchymal cells of different organs from injury, whereas its presence in the liver and its potential importance in stimulating liver regeneration has never been described. This was investigated in this study using a rat model of partial hepatectomy (PH). Methods The rat model of 70, 80, and 90% PH was used. Liver samples were taken peroperatively, 1 h, 1, 2, 3, and 7 days after surgery. Liver regeneration was evaluated by liver weight/body weight ratio, liver regeneration rate (%), and proliferating cell marker Ki67. The expression of PlGF, vascular endothelial growth factor (VEGF), VEGF receptor 1 (Flt-1), VEGF receptor 2 (Flk-1), and hypoxia inducible factor-1&agr; mRNA was measured by quantitative real-time PCR and localized by immunohistochemistry. Results The mRNA expression of PlGF was upregulated immediately after PH. Compared with 70 and 80% PH groups, the 90% PH group had a significantly lower PlGF and hypoxia inducible factor-1&agr; mRNA expression, in parallel to a delayed liver weight/body weight ratio recovery. Only little differences were observed in VEGF, Flt-1, and Flk-1 mRNA expression among the PH groups. Conclusion This study shows for the first time the PlGF upregulation in regenerating livers, which is related to hypoxia stimulation and liver growth. The swift PlGF upregulation immediately after PH may indicate an important role for the PlGF/Flt-1 pathway in the early stage of liver regeneration.

Over-expression of heat shock protein 70 in mice is associated with growth retardation, tumor formation, and early death

Experiments in lower organisms, such as worms and flies, indicate that the molecular chaperone protein heat shock protein 70 (HSP70) is a longevity factor. In contrast, we demonstrate here that mice overexpressing HSP70 display growth retardation and early death. HSP70 transgenic mice displayed increased levels of serum corticosterone and weaker expression and activity of the glucocorticoid receptor in the liver. Serum insulin-like growth factor-1 (IGF-1) concentrations in the transgenic mice were 50% lower than in the control mice, leading to growth retardation. HSP70 transgenic mice showed decreased expression of Casp9, which encodes caspase-9, and increased expression of the anti-apoptotic Bcl-2 gene, indicating that apoptosis is suppressed. Consequently, most of the transgenic animals died before the age of 18 months from tumors in their lungs and lymph nodes. We suggest that the proinflammatory and antiapoptotic effects of HSP70 might be responsible for the growth retardation, tumor formation, and early death observed in the HSP70 transgenic mice.

Rating of CCl4‐induced rat liver fibrosis by blood serum glycomics

Background:  Non‐invasive staging of human liver fibrosis is a desirable objective that remains under extensive evaluation. Animal model systems are often used for studying human liver disease and screening antifibrotic compounds. The aim of the present study was to investigate the potential use of serum N‐glycan profiles to evaluate liver fibrosis in a rat model.

Effects of Re-Arterialization on Early Graft Function and Regeneration in the Rat Model of Heterotopic Auxiliary Liver Transplantation

In the rat model of heterotopic auxiliary liver transplantation, graft re-arterialization may influence the outcome of inter-liver competition. This was investigated in the current study using two transplanted groups with or without graft re-arterialization. Immediately after reperfusion, the re-arterialized grafts showed significantly higher bile flow rate and bilirubin excretion than the grafts without re-arterialization. DNA synthesis rate was also increased more drastically in the re-arterialized group following the transplantation. Without re-arterialization, the rats developed more pronounced cytolysis and cholestasis. Among the long-term survivors, all healthy re-arterialized grafts regenerated, whereas 5/6 non-re-arterialized grafts atrophied. These data demonstrate that the re-arterialization increases graft survival by improving early hepatic function, enhancing regenerative response and preventing post-transplant biliary complications in this rat model.

The need to handicap the recipient's native liver in the rat model of heterotopic auxiliary liver transplantation.

In the rat model of heterotopic auxiliary liver transplantation (HALTx), the opinion varies on whether and how the recipients native liver should be handicapped. To avoid atrophy of the transplanted organ, in this study, two different handicaps were evaluated and their effects on post-operative animal survival and liver biology are described. With a sole portacaval shunt (group 1) all rats survived longer than 3 months. An additional handicap of the liver with either a 68% partial hepatectomy (68% PH) (group 2), or both a 68% PH and a common bile duct ligation (CBDL) (group 3) led to a 100% mortality within 2 days after surgery. When an auxiliary liver was transplanted to the rats handicapped with a 68% PH (group 4), serum Bilirubin and ALAT values were significantly lower than those handicapped with both a 68% PH and a CBDL (group 5). Autopsy and histology of the long-term survivors revealed the atrophy of the engrafted livers and the regeneration of the native livers in group 4, whereas it showed the opposite in group 5. Thus the various manipulations of the native liver do influence differently the post-transplant animal survival, serum liver biochemistry and the outcome of the engrafted liver in this rat model of HALTx.

Evaluation of graft viability in heterotopic auxiliary liver transplantation in the rat.

In the rat model of heterotopic auxiliary liver transplantation, the coexistence of the engrafted liver and the recipients native liver makes it difficult to evaluate the posttransplant graft viability. In this study, auxiliary liver transplantation was performed in Wistar rats, in which the recipients native liver was handicapped with a 68% partial hepatectomy and a common bile duct ligation. Serum biochemistry of the liver was analyzed and compared with that of the selected control group. The surgical handicap of the liver showed severe damaging effects: the handicapped native livers appeared atrophic at autopsy, and no long-term animal survival could be achieved without an auxiliary liver transplantation. As the engrafted liver corrected the cholestasis of the handicapped native liver, significant differences of serum biochemistry were found between the transplanted group and the control group: for bilirubin concentration and gamma glutamyl transferase activity from postoperative day 3 to 28 (p < .05); for alkaline phosphatase on days 3, 7, 14, and 28 (p < .05); for alanine aminotransferase activity on days 3 and 14 (p < .05); and for aspartate aminotransferase activity on day 14 (p < .05). The efficiency to induce hepatic failure and to hamper its regeneration capacity in the native liver makes animal survival and liver biology as reliable parameters to evaluate the posttransplant graft viability in this rat model.