P-selectin mediates reperfusion injury through neutrophil and platelet sequestration in the warm ischemic mouse liver

Abstract

Hepatic damage following ischemia-reperfusion injury involves polymorphonuclear leukocytes (PMN) and platelet sequestration, however the mechanisms of adhesion remain elusive. In this study, using gene-targeted deficient mice, we evaluated P-selectin and its contribution to PMN and platelet adhesion in hepatic damage. In an in vivo warm ischemia model, hepatic injury was assessed by serum transaminase levels, survival, PMN adhesion by histological analysis, and platelet sequestration by immunostaining. Serum transaminase levels were strikingly reduced (by up to threefold) in the P-selectin deficient mice, particularly at 90 minutes of ischemia, when compared with wild-type controls. PMN adhesion and platelet sequestration was also significantly decreased in P-selectin deficient mice following 90 minutes of partial ischemia. Animal survival was significantly improved after 75 minutes of total hepatic ischemia in P-selectin deficient mice when compared with wild-type mice. Survival was also achieved after 90 minutes of ischemia in the mutant mice whereas none of the wild-type animals survived. These data show that P-selectin plays a critical role in PMN and platelet adhesion following ischemia-reperfusion injury to the liver. (HEPATOLOGY 1999; 29:1494-1502.)The pathogenesis of cell damage following reperfusion of ischemic tissue is an incompletely understood series of events. 1,2 Various mechanisms have been proposed including enhanced production of inflammatory mediators, 3-5 recruitment of polymorphonuclear leukocytes (PMN), 6,7 and blockage of blood flow. 7-9 The leukocyte-endothelial interaction that occurs following ischemia/reperfusion (I/Rp) injury has been shown to be important for microvascular dysfunction and release of cytotoxic mediators such as reactive oxygen intermediates and a variety of proteases. 10-12 We 13 and others 5,6,9,14,15 have shown leukocyte accumulation to be a critical determinant of hepatic I/Rp injury. Other blood elements including platelets adhere to the hepatic sinusoids in conditions of ischemia, 16,17 but little is known about their contribution to the injury.The adhesion of PMN and platelets to the vascular endothelium involves a variety of adhesion receptors. [18][19][20][21] The selectin family (P-, E-, and L-selectin) are the first to be engaged in the process, 19 with P-selectin acting at the earliest stage of interaction between PMN and the endothelium. P-selectin is found in the ␣ granules of resting platelets and Weibel-Palade bodies of endothelial cells, 18 and expression of P-selectin on the cell surface can occur within minutes under stimulation by mediators of inflammation such as thrombin, histamine, complement, and peroxide. 22 P-selectin is able to tether leukocytes to the endothelial surface through its ligand P-selectin glycoprotein ligand-1 (PSGL-1), which leads to their activation. 23 Once leukocytes attach, they can interact with flowing PMN and platelets through the action of P-and L-selectin, 23 which may lead to further adhesion of PMN and platelets as we...

Vascular endothelial growth factor production by isolated rat hepatocytes after cold ischemia—warm reoxygenation

“…[19][20][21]28 These are signs of the highly adhesive phenotype of SECs and leukocytes, shown by the increased presence of different molecules, such as P-, E-, and L-selectins and integrins, in the transplantation setting. 19,29 These events are believed to be related to activation of an inflammatory response by SECs in reaction to the transplantation process, although the exact mechanisms remain unclear. Although preservationreperfusion injury appears to primarily affect SECs, 1 damage to several key hepatocellular functions also is clearly present 6,10 and probably participates in the primary dysfunction of several liver grafts.…”

“…18 Furthermore, elevated Ca 2ϩ levels in stimulated endothelial cells leads to the translocation of such adhesion molecules as P-selectins 18 to the plasma membrane, which in turn causes leukocyte rolling on the surface of these cells. 19,20 This is the first step to leukocyte activation and inflammation. 20,21 As mentioned, inflammatory processes at the level of SECs and the ensuing microvascular disturbances are frequently observed in liver transplantation injury.…”

N-acetylcysteine induces shedding of selectins from liver and intestine during orthotopic liver transplantation

“…A study on rat liver microvasculature could not demonstrate an involvement of endothelial selectins in the recruitment of leucocytes [31]. However, a clear dependency of leucocyte±endothelial interaction on functioning P-selectin molecules has been proven in murine hepatic [32,33] and splanchnic [34] I/R models. Similarly, in a murine renal I/R model, P-selectin deficiency as well as blocking P-selectin by antibodies resulted in less neutrophil infiltration and in better organ function [35].…”

Cold preservation–warm reperfusion perturbs cytosolic calcium ion homeostasis in rat liver sinusoidal endothelial cells

“…9 The appearance of P-selectin and platelet-activating factor on the SEC surface can mediate the interaction between hepatic microvasculature and circulating blood cells and platelets. [14][15][16][17] For instance, such an inflammatory process causes an accumulation of white blood cells at the site of injury 14,16,18 and may induce the occlusion of microvessels, causing areas of no reflow during reperfusion, as observed in myocardial ischemia. 19,20 In the liver, it appears that platelets are more involved in this phenomenon at intrahepatic sites.…”

“…19,20 In the liver, it appears that platelets are more involved in this phenomenon at intrahepatic sites. 14 Finally, release of such cytotoxic mediators as reactive oxygen intermediates at the site of inflammation can be harmful for surrounding cells, 1 even leading to the detachment of SECs from the extracellular matrix. 1,4,7 Together, these effects may participate in graft dysfunction; however, the exact role of Ca 2ϩ has not yet been elucidated.…”