Pulmonary Vascular Injury In Rats Research Articles

Antithrombin III (AT III) prevents LPS-induced pulmonary vascular injury: novel biological activity of AT III.

Acute respiratory distress syndrome (ARDS) adversely affects the outcome of patients with disseminated intravascular coagulation (DIC) associated with sepsis. To determine whether antithrombin III (AT III) is useful for the treatment of ARDS in sepsis, we evaluated the effect of AT III on lipopolysaccharide (LPS)-induced pulmonary vascular injury in rats. Although the intravenous administration of AT III (250 U/kg) prevented LPS-induced pulmonary accumulation of leukocytes, increases in pulmonary vascular permeability, and coagulation abnormalities, inactivated factor Xa, a selective inhibitor of thrombin generation, did not prevent such events other than the coagulation abnormalities. AT III promotes the endothelial release of prostacyclin by interacting with cell surface glycosaminoglycans in vivo. Trp49-modified AT III, which lacks affinity for heparin, did not prevent LPS-induced pulmonary vascular injury. Plasma levels of 6-keto-prostaglandin F1alpha were markedly increased in rats after the administration of LPS and significantly decreased in the LPS-treated rats administered Trp49-modified AT III, but not altered in those LPS-treated rats receiving AT III. Preventive effects of AT III were not observed in rats pretreated with indomethacin, which inhibits prostacyclin biosynthesis. Prostacyclin prevents LPS-induced pulmonary vascular injury by inhibiting leukocyte accumulation in the lungs. These observations strongly suggest that AT III prevents pulmonary vascular injury induced by LPS by promoting the endothelial release of prostacyclin, a potent inhibitor of leukocyte activation.

Effect of human urinary thrombomodulin on endotoxin-induced intravascular coagulation and pulmonary vascular injury in rats.

Adult respiratory distress syndrome (ARDS) and disseminated intravascular coagulation (DIC) are serious complications of sepsis. Thrombomodulin, an important endothelial anticoagulant, binds thrombin to generate activated protein C (APC). To determine whether thrombomodulin purified from human urine (urinary thrombomodulin, UTM) is useful for the treatment of DIC and ARDS in sepsis, we examined the effect of UTM on endotoxin (ET)-induced coagulation abnormalities and pulmonary vascular injury in rats. Intravenous administration of UTM prevented the ET-induced pulmonary accumulation of leukocytes and the increase in pulmonary vascular permeability, as well as ET-induced histological changes such as leukocyte infiltration and pulmonary interstitial edema. On the other hand, dansyl-Glu-Gly-Arg-chloromethyl ketone-treated factor Xa (DEGR-Xa), a selective inhibitor of thrombin generation, did not prevent these effects of ET. UTM did not prevent ET-induced pulmonary accumulation of leukocytes and pulmonary vascular injury in rats pretreated with DEGR-Xa. Our findings suggest that UTM attenuates ET-induced coagulation abnormalities and pulmonary vascular injury. Furthermore, the latter effect may be dependent on the capacity of UTM to activate protein C.

Effect of human urinary thrombomodulin on endotoxin-induced intravascular coagulation and pulmonary vascular injury in rats

Effect of human urinary thrombomodulin on endotoxin-induced intravascular coagulation and pulmonary vascular injury in rats

Effect of nafamostat mesilate on pulmonary vascular injury induced by lipopolysaccharide in rats.

Nafamostat mesilate (NM) is a synthetic protease inhibitor that is capable of inhibiting the various coagulation factors such as factor VIIa and thrombin. To determine whether NM may also be useful in treating adult respiratory distress syndrome (ARDS) related in sepsis, we investigated the effect of NM on lipopolysaccharide (LPS)-induced pulmonary vascular injury in rats. The intraperitoneal administration of NM prevented the pulmonary vascular injury and coagulation abnormalities induced by LPS. DEGR-factor VIIa, a selective inhibitor of factor VIIa, prevented the coagulation abnormalities, but not the pulmonary vascular injury, induced by LPS. NM did not reduce LPS-induced increase in pulmonary accumulation of leukocytes. NM did not inhibit the increase in the plasma concentration of tumor necrosis factor-alpha (TNF-alpha) observed after administration of LPS. NM did not inhibit the function of activated neutrophils in vitro. Plasma values of total serum hemolytic complement (CH50) were markedly decreased after the administration of LPS. NM inhibited the LPS-induced decrease in plasma CH50 values. Findings suggest that NM may reduce the pulmonary vascular injury as well as the coagulation abnormalities induced by LPS. The former effect may be independent of the anticoagulant effect but dependent on the inhibitory effect of the activation of the complement system in rats administered LPS.

Recombinant thrombomodulin prevents endotoxin-induced lung injury in rats by inhibiting leukocyte activation

Acute respiratory distress syndrome (ARDS) is a serious complication of sepsis. Thrombomodulin, an important endothelial anticoagulant, binds thrombin to generate activated protein C (APC). We have previously demonstrated that APC prevents endotoxin (ET)-induced pulmonary vascular injury by inhibiting activated leukocytes. We therefore examined whether recombinant human soluble thrombomodulin (rhs-TM) prevents activated leukocyte-induced pulmonary vascular injury in rats receiving ET. Intravenous administration of rhs-TM prevented ET-induced pulmonary accumulation of leukocytes and increase in pulmonary vascular permeability, as well as ET-induced histological changes, such as leukocyte infiltration and pulmonary interstitial edema. Dansyl-Glu-Gly-Arg-chloromethyl ketone-treated factor Xa (DEGR-Xa), a selective inhibitor of thrombin generation, did not prevent these effects of ET. rhs-TM did not prevent ET-induced pulmonary accumulation of leukocytes and pulmonary vascular injury in rats pretreated with DEGR-Xa. These results suggest that rhs-TM prevents ET-induced pulmonary vascular injury by inhibiting pulmonary accumulation of leukocytes and that this effect may be mediated primarily by APC generation.

Activated Protein C Attenuates Endotoxin-Induced Pulmonary Vascular Injury by Inhibiting Activated Leukocytes in Rats

We investigated the effect of activated protein C (APC) on lipopolysaccharide (LPS)-induced pulmonary vascular injury in rats to investigate the possible usefulness of APC as a treatment for adult respiratory distress syndrome. Intravenously administered LPS (5 mg/kg) significantly increased pulmonary vascular permeability. APC prevented the LPS-induced increase in pulmonary vascular permeability observed at 6 hours. Heparin plus antithrombin III (ATIII) and active site-blocked factor Xa (DEGR-Xa), a selective inhibitor of thrombin generation, inhibited LPS-induced coagulopathy but did not prevent LPS-induced pulmonary vascular injury. LPS-induced pulmonary vascular injury was significantly attenuated in rats with nitrogen mustard-induced leukocytopenia and in rats treated with ONO-5046, a potent granulocyte elastase inhibitor. Administration of LPS also increased pulmonary accumulation of leukocytes, as evaluated by measurement of myeloperoxidase activity in the lungs. APC significantly reduced LPS-induced increases in pulmonary accumulation of leukocytes at 1 hour. Neither ATIII plus heparin nor DEGR-Xa inhibited leukocyte accumulation. Active site-blocked APC (DIP-APC) prevented neither the LPS-induced pulmonary accumulation of leukocytes nor the LPS-induced increase in pulmonary vascular permeability. These results suggest that the mechanism of APC inhibition of LPS-induced pulmonary vascular injury was independent of its anticoagulant activity and was related to its ability to inhibit accumulation of leukocytes. In addition, these findings suggest that the serine protease activity of APC may be essential to its inhibitory effect on LPS-induced pulmonary accumulation of leukocytes and subsequent pulmonary vascular injury.

Recombinant Human Soluble Thrombomodulin Reduces Endotoxin-Induced Pulmonary Vascular Injury Via Protein C Activation in Rats

Adult respiratory distress syndrome (ARDS) is a serious complication of disseminated intravascular coagulation (DIC) or multiple organ failure. To determine whether recombinant soluble human thrombomodulin (rsTM) may be useful in treating ARDS due to sepsis, we investigated the effect of rsTM on lipopolysaccharide (LPS)-induced pulmonary vascular injury in rats. The intravenous administration of rsTM prevented the increase in pulmonary vascular permeability induced by LPS. Neither heparin plus antithrombin III (AT III) nor dansyl Glu Gly Arg chloromethyl ketone-treated factor Xa (DEGR-Xa), a selective inhibitor of thrombin generation, prevented LPS-induced vascular injury. The agents rsTM, heparin plus AT III, and DEGR-Xa all significantly inhibited the LPS-induced intravascular coagulation. Recombinant soluble TM pretreated with a monoclonal antibody (moAb) that inhibits protein C activation by rsTM did not prevent the LPS-induced vascular injury; in contrast, rsTM pretreated with a moAb that does not affect thrombin binding or protein C activation by rsTM prevented vascular injury. Administration of activated protein C (APC) also prevented vascular injury. LPS-induced pulmonary vascular injury was significantly reduced in rats with leukopenia induced by nitrogen mustard and by ONO-5046, a potent inhibitor of granulocyte elastase. Results suggest that rsTM prevents LPS-induced pulmonary vascular injury via protein C activation and that the APC-induced prevention of vascular injury is independent of its anticoagulant activity, but dependent on its ability to inhibit leukocyte activation.