Elsevier

Surgery

Volume 139, Issue 1, January 2006, Pages 61-72
Surgery

Original communication
Attenuation of proinflammatory gene expression and microcirculatory disturbances by endothelinA receptor blockade after orthotopic liver transplantation in pigs

https://doi.org/10.1016/j.surg.2005.07.006Get rights and content

Background

Endothelin-1 (ET-1), a very potent mediator of vasoconstriction, leads to microcirculatory disturbances and release of proinflammatory cytokines under pathophysiologic conditions. Our aim was to evaluate the effect of a selective ETA-receptor antagonist (ETA-RA) on cold ischemia/reperfusion (I/R) injury in a pig model.

Methods

Twenty pigs revealed orthotopic liver transplantation. The animals were randomized into 2 groups: control pigs received isotonic saline; the treated group received the selective ETA-RA BSF 208075 at the beginning of reperfusion. On postoperative days 4 and 7, animals were re-laparotomized to obtain tissue specimens. Liver tissue samples were collected and quantitative mRNA expression for prepro–ET-1, ETA receptor, pro–IL-1β, pro–IL-6, pro–TNF-α, and endothelial nitric oxide synthase was analyzed using the TaqMan system. Additionally, immunohistochemical analysis for ET-1 was performed. Hepatic microcirculation was evaluated by laser Doppler flow measurement and partial pressure of oxygen and carbon dioxide measurements with the Paratrend sensor. Postischemic liver damage was monitored by measurement of liver enzymes and by histologic analysis using a semiquantitative scoring classification.

Results

Treatment with the ETA-RA significantly reduced the severity of I/R injury evidenced by lower serum AST, ALT and GLDH. Analysis of partial pressure of oxygen and blood flow revealed a significant improvement of capillary perfusion and blood flow in the treated group and was associated with a relevant reduction of tissue injury. One hour after reperfusion, quantitative RT-PCR revealed significantly lower expression of prepro–ET-1, ETA receptor, endothelial nitric oxide synthase, pro–TNF-α, pro–IL-1β and pro–IL-6 in the therapy group. Immunohistochemical analysis demonstrated significantly reduced ET-1 immunostaining after therapy. Histologic investigation suggested less tissue damage in treated animals.

Conclusions

Treatment with the selective ETA-RA BSF 208075 has protective effects on microcirculation after liver transplantation. ETA-RA not only affects the expression of vasoactive genes, but also decreases gene expression of proinflammatory cytokines such as TNF-α, IL-1β and IL-6.

Section snippets

Material and methods

The investigation was performed in accordance with the German legislation on protection of animals, and the experiments were approved by the Committee on Animal Care (Regierungspräsidium Leipzig, Germany; No. 02/00). Orthotopic liver transplantation was performed in female German Landrace pigs (20-25 kg). The control group (n = 10) received 50 mL of isotonic saline solution, and the therapy group (n = 10) received intravenously 5 mg/kg of body weight of the specific ETA-RA BSF 208075 (Knoll AG,

Survival

Pigs surviving to postoperative day 7 were killed. The number of survivors at postoperative 7 was 7 of 10 in the control group and 9 of 10 in the therapy group. In the control and therapy group, 1 of 10 pigs, respectively, died within the first 2 days because of cardiopulmonary complications. In the control group, 2 of 10 pigs died because of liver failure.

Macrohemodynamic and blood gas changes

Before operation, there were no differences in mean arterial blood pressure between the control and therapy groups under isoflurane

Discussion

In hepatic I/R, dysfunction of the microcirculation appears to be the primary process that triggers the final manifestation of tissue injury. Postischemic microcirculatory dysfunction includes failure of sinusoidal perfusion (ie, the no-reflow), which is caused by endothelial swelling, intravascular hemoconcentration, and a dysbalance between the vasoactive mediators endothelin and nitric oxide. Apart from perfusion failure, I/R further promotes a microcirculation-associated inflammatory

Conclusion

Our results indicate that ETA-receptor antagonism has beneficial effects on the outcome after cold I/R injury of the porcine liver by improving microcirculation and decreasing histologic damages. Furthermore, findings from the present study suggest that selective antagonism of the ETA receptor also may have anti-inflammatory potential through suppression of the mRNA expression of the genes of proinflammatory cytokines such as TNFα, IL-1β, and IL-6. This study was designed as a pilot project to

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    Supported by a grant from the Else Kröner-Fresenius Stiftung, a junior research fund of the Medical Faculty at the University of Leipzig, and a grant from Fujisawa, Germany.

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