Attenuation of proinflammatory gene expression and microcirculatory disturbances by endothelin A receptor blockade after orthotopic liver transplantation in pigs.
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 ET(A)-receptor antagonist (ET(A)-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 ET(A)-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, ET(A) receptor, pro-IL-1beta, pro-IL-6, pro-TNF-alpha, 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 ET(A)-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, ET(A) receptor, endothelial nitric oxide synthase, pro-TNF-alpha, pro-IL-1beta 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 ET(A)-RA BSF 208075 has protective effects on microcirculation after liver transplantation. ET(A)-RA not only affects the expression of vasoactive genes, but also decreases gene expression of proinflammatory cytokines such as TNF-alpha, IL-1beta and IL-6.
Uhlmann
Dirk
D
Department of Abdominal, Transplantation, Thoracic and Vascular Surgery, University of Leipzig, Liebigstrasse 20, 04103 Leipzig, Germany. uhld@medizin.uni-leipzig.de
Gaebel
Gabor
G
Armann
Barbara
B
Ludwig
Stefan
S
Hess
Jochen
J
Pietsch
Uta-Carolin
UC
Fiedler
Martin
M
Tannapfel
Andrea
A
Hauss
Johann
J
Witzigmann
Helmut
H
D000818:Animals; D002317:Cardiovascular Agents / Q000378:metabolism; D065130:Endothelin A Receptor Antagonists; D019332:Endothelin-1 / Q000097:blood / Q000378:metabolism; D005260:Female; D005740:Gases / Q000097:blood; D015870:Gene Expression / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D007150:Immunohistochemistry; D018836:Inflammation Mediators / Q000378:metabolism*; D017078:Laser-Doppler Flowmetry; D008099:Liver / Q000473:pathology; D008102:Liver Circulation / Q000187:drug effects*; D016031:Liver Transplantation / Q000401:mortality; D008833:Microcirculation / Q000187:drug effects; D010666:Phenylpropionates / Q000494:pharmacology*; D011184:Postoperative Period; D011724:Pyridazines; D016019:Survival Analysis; D013552:Swine
D002317:Cardiovascular Agents; D065130:Endothelin A Receptor Antagonists; D019332:Endothelin-1; D005740:Gases; D018836:Inflammation Mediators; D010666:Phenylpropionates; D011724:Pyridazines; C467894:ambrisentan