Ischemia-reperfusion of rat liver modulates hepcidin in vivo expression.

The recently identified acute-phase response antimicrobial peptide hepcidin has been postulated to maintain iron homeostasis by modulating iron absorption at both the intestinal and macrophage levels. Hepcidin has also been reported to be responsible for anemia associated with chronic inflammatory diseases, and in anemia in patients with hepatic adenomas. Since Kupffer cells are known to be the primary contributor to early-phase ischemia-reperfusion injury in the liver and iron is known to modulate Kupffer cell production of proinflammatory cytokine and reactive oxygen species, we investigated hepcidin in vivo expression in the well-established rat partial-liver ischemia-reperfusion model. We found that both liver ischemia alone and liver ischemia-reperfusion significantly induced serum and liver hepcidin levels. Furthermore, currently proposed mediators of in vivo hepcidin expression, such as interleukin-6, signal transducers and activators of transcription-family transducers, and CCAAT/enhancing binding protein-alpha do not appear to modulate hepcidin expression in the liver ischemia-reperfusion acute inflammatory model. In this study we report the first in vivo evidence of liver ischemia and liver ischemia-reperfusion modulation of hepcidin expression. In conclusion, in the well-characterized liver ischemia-reperfusion model of acute inflammation, mechanism(s) other than interleukin-6 signal transduction via signal transducers and activators of transcription-3 may be responsible for hepcidin induction.

Use of RNA interference to target cyclin E-overexpressing hepatocellular carcinoma.

RNA interference is the process by which double-stranded RNA directs sequence-specific degradation of mRNA. It has recently been shown that RNA interference can be triggered by 21-nucleotide duplexes of small interfering RNAs (siRNAs) in both cultured mammalian cells and adult mice. We hypothesize that siRNA can be used to specifically target oncogene overexpression in a therapeutic manner. Here, we show that overexpression of the oncogene cyclin E can be suppressed by up to 90% in hepatocellular carcinoma (HCC) cell lines by siRNA targeted on the coding region of cyclin E. We also find that depletion of cyclin E in this manner promotes apoptosis of HCC cells and blocks cell proliferation. Finally, we show that the siRNA oligos inhibits HCC tumor growth in nude mice. Thus, this study demonstrates the therapeutic potential of siRNA on the treatment of HCC by targeting overexpressed oncogenes such as cyclin E. Our results also indicate that cyclin E, which is overexpressed in 70% of HCCs, may serve as a novel therapeutic target.

Deregulation of iron homeostasis and cold-preservation injury to rat liver stored in University of Wisconsin solution.

Very little is known about iron metabolism and the mediators of iron metabolism in liver subjected to cold storage before transplantation. Therefore, in this study, we investigated the effect of cold storage on iron homeostasis in the rat liver. When livers were stored at 4 degrees C in University of Wisconsin solution for up to 6 and 24 hours, significant increases occurred in the labile iron pool, ferritin protein, and heme oxygenase activity. Significant decreases in heme content and iron regulatory protein 1 and 2 binding activities occurred by 24 hours. Liver injury indicated by significant increases in University of Wisconsin solution transaminase activity and liver lipid hydroperoxide levels occurred by 6 and 24 hours. Taken together, these results suggest that during pretransplantation cold storage of the liver, an aberrant iron homeostasis develops that contributes to preservation injury, and predisposes the liver to reperfusion injury by iron-dependent reactive oxygen species/Fenton reaction.

Recombinant human interleukin-11 improves thrombocytopenia in patients with cirrhosis.

To elucidate the hematopoietic activity of recombinant human interleukin-11 (rhIL-11, [Neumega, Cambridge, MA]) in patients with cirrhosis and thrombocytopenia, we administered rhIL-11 at 50 microg/kg/d subcutaneously to 10 patients for 10 days with a 30-day follow-up period. All treated patients (n = 9) experienced a gradual, yet significant increase in their platelet count above the baseline value (P < or =.01) reaching the peak value (median, 93,000/microL; range, 60,000-206,000/microL) at a median of 13 days (range, 6-23 days). Eight patients (89%) had a significant increase of > or =50% over the baseline value (P <.05). Moreover, further increases to > or =60,000/microL, > or =80,000/microL, and > or =100,000/microL were observed in 100%, 78%, and 33% of the patients, respectively. A subsequent decline in platelet count was observed at a median of 19 days (range, 7-26 days) after the occurrence of peak concentration. A significant increase in neutrophil count was also demonstrated starting on the third day of treatment (P < or =.01). Concurrent with an increase in the serum level of fibrinogen, transaminase levels declined significantly during treatment period, while bilirubin levels continued to drop for up to 20 days after the initiation of treatment (P <.05). The most frequent effects were due to plasma volume expansion, including conjunctival redness and edema. In conclusion, rhIL-11 can improve platelet counts in patients with early cirrhosis and these patients could benefit from rhIL-11 treatment. However, given the high frequency of regimen-related toxicity, the use of rhIL-11 in patients with cirrhosis should be administered with caution.

Disruption of the Nramp1 (also known as Slc11a1) gene in Kupffer cells attenuates early-phase, warm ischemia-reperfusion injury in the mouse liver.

As the natural resistance-associated macrophage protein 1 Nramp1 (also known as Slc11a1) modulates Kupffer cell (KC) activation, and KC are responsible for the early phase of warm ischemia/reperfusion (I/R) to the liver, we hypothesized that livers of Nramp1(-/-) mice will be protected from early-phase I/R injury compared with livers of Nramp1(+/+) mice. To test our hypothesis, we induced partial warm ischemia to the livers of Nramp1(+/+) and Nramp1(-/-) mice for 45 min of by clamping the hilum of the median and left lateral lobes, followed by 30 or 60 min of reperfusion. Plasma glutamate oxaloacetate transaminase (pGOT) activity and tumor necrosis factor alpha (TNF-alpha) levels were measured, and liver sections were stained for polymorphonuclear leukocyte (PMN) accumulation. After 45 min of ischemia and 30/60 min of reperfusion of Nramp1(+/+) and Nramp1(-/-) mice livers, we found significant increases in plasma pGOT activity and TNF-alpha levels in Nramp1(+/+) mice at 30 and 60 min of reperfusion, respectively, compared with sham controls and all Nramp1(-/-) mice. A significant accumulation of PMNs was also found in livers of Nramp1(+/+) mice at 60 min of reperfusion compared with all other groups. We have shown that disruption of the Nramp1 gene attenuates I/R injury to the mouse liver during the early phase of warm I/R injury. An increased understanding of the role played by Nramp1 is particularly important in the liver, as this organ is subjected to a wide variety of injuries during hemorrhagic shock, partial resections, and transplantation.

Intravenous Cidofovir therapy for disseminated adenovirus in a pediatric liver transplant recipient.

BACKGROUND: No definitive antiviral therapy exists for adenovirus (ADV) in immunosuppressed hosts. Cidofovir (CDV), a broad spectrum anti-DNA viral agent, has previously been shown to be of therapeutic benefit in life-threatening adenoviral disease in bone marrow stem-cell recipients. METHODS: A 71/2-month-old girl with a history of biliary atresia developed fevers, hematochezia, tachypnea, and laboratory evidence of hepatitis and pancreatitis 12 days after liver transplantation. A stool culture, oropharyngeal culture, blood viral culture, and blood polymerase chain reaction (PCR) confirmed ADV. Cidofovir 1 mg/kg intravenously three times per week was initiated. The patient received intravenous hydration and probenecid with the infusions to reduce the nephrotoxicity of CDV. Immunosuppression was reduced to achieve tacrolimus trough levels of approximately 8 ng/mL and prednisone at 0.1 mg/kg per day. Complete blood cell count, urinalysis, and viral studies were obtained weekly. RESULTS: Detection of ADV DNA by PCR made a transition from positive to negative during CDV therapy. Blood viral cultures became negative after two CDV doses. Alanine aminotransferase normalized by 5 weeks of therapy. CDV was discontinued after 7 weeks secondary to transient acidosis and proteinuria. The patient never developed azotemia, neutropenia, or ocular abnormalities. CONCLUSIONS: CDV was associated with improved clinical status, viral clearance, and minimal transient side effects in a pediatric liver transplant recipient with disseminated adenoviral disease. The current report documents clearance of disseminated ADV infection in a liver transplant recipient receiving CDV infusions.

Maintenance of the celiac trunk with the left-sided liver allograft for in situ split-liver transplantation.

BACKGROUND: It has been shown that in situ split-liver transplantation (SLT) expands the cadaveric donor pool, decreases recipient waiting time, and decreases pretransplant morbidity. However, the technique as previously described requires a microvascular left hepatic artery anastomosis. In an attempt to decrease the incidence of hepatic artery thrombosis and to increase collaboration among transplant teams, in the current report, we describe a modification of the in situ SLT technique that maintains the celiac trunk with the left-sided liver allograft. METHODS: Twelve in situ split-liver procurements resulted in 24 segmental liver allografts; 11 right trisegments, 11 left lateral segments, 1 right lobe, and 1 left lobe. The common bile duct and main portal vein were maintained with the right-sided liver allograft in all cases. The right hepatic artery was divided, and the celiac trunk was maintained with the left-sided liver allograft in nine cases. In one case the left hepatic artery was divided and the celiac trunk was maintained with the right-sided allograft. Two of the 12 donors had a completely replaced left hepatic artery originating from the left gastric artery, which was divided at its origin from the celiac trunk. When the celiac trunk was maintained with the left-sided allografts, arterial reconstruction of the right-sided allograft was performed with an external iliac arterial interposition graft. Nineteen of the 24 split-liver allografts were transplanted at our center. The remaining five liver allografts were shared with regional liver transplant centers. RESULTS: In this series, 1-year actuarial patient and allograft survival rates are 100% and 96%, respectively. Hepatic artery thrombosis (HAT) did not occur in any patient receiving a left-sided split allograft in which the celiac trunk or left gastric artery was maintained; in addition, HAT did not occur in any of the right-sided allografts. HAT did occur immediately after transplantation in the one patient who was transplanted with a left lateral segment without the celiac trunk. This allograft was salvaged by early thrombectomy and interposition grafting. One patient required retransplantation, owing to portal vein thrombosis. Hepatic venous outflow obstruction did not occur in any of the patients. Two patients required reexploration in the posttransplant period because of arterial anastomotic site bleeding, and one of the left lateral segment allograft recipients had a cut-surface bile leak, which was managed nonoperatively. All of the patients are alive and well, including the five patients who received their transplants at other centers, with a median follow-up of 10 months (range, 1-27 months). CONCLUSIONS: In summary, our data demonstrate that maintaining the celiac trunk with the left-sided allograft in SLT provides excellent early survival results with low complication rates. This technical modification obviates the need for a left hepatic artery microvascular anastomosis and should lower the incidence of hepatic artery thrombosis in the small-caliber left hepatic artery. We have also shown that this technique allows sharing among liver transplant centers without compromise in patient or allograft survival rates. It is hoped that this modification in SLT will increase the number of livers split, and will promote sharing among transplant centers to truly optimize the number of liver allografts available from the cadaveric pool.

The natural resistance-associated macrophage protein 1 Slc11a1 (formerly Nramp1) and iron metabolism in macrophages.

Slc11a1 (solute carrier family 11 member 1) (formerly Nramp1) modulation of iron metabolism in macrophages plays an important role in early phase macrophage activation, and therefore host innate immunity. This review focuses on the role of Nramp1 in intramacrophage iron metabolism, with emphasis on the two prevailing mechanisms of Nramp1 modulation of iron metabolism in macrophages.