The lectin‐like domain of thrombomodulin is a drug candidate for both prophylaxis and treatment of liver ischemia and reperfusion injury in mice

Ischemia and reperfusion injury (IRI) can occur in any tissue or organ. With respect to liver transplantation, the liver grafts from donors by definition experience transient ischemia and subsequent blood reflow. IRI is a problem not only in organ transplantation but also in cases of thrombosis or circulatory disorders such as mesenteric ischemia, myocardial, or cerebral infarction. We have reported that recombinant human soluble thrombomodulin (rTM), which is currently used in Japan to treat disseminated intravascular coagulation (DIC), has a protective effect and suppresses liver IRI in mice. However, rTM may not be fully safe to use in humans because of its inherent anticoagulant activity. In the present study, we used a mouse liver IRI model to explore the possibility that the isolated lectin-like domain of rTM (rTMD1), which has no anticoagulant activity, could be effective as a therapeutic modality for IRI. Our results indicated that rTMD1 could suppress ischemia and reperfusion-induced liver damage in a dose-dependent manner without concern of associated hemorrhage. Surprisingly, rTMD1 suppressed the liver damage even after IR insult had occurred. Taken together, we conclude that rTMD1 may be a candidate drug for prevention of and therapy for human liver IRI without the possible risk of hemorrhage

Characterization of the Terephthalate Degradation Genes of Comamonas sp. Strain E6

We isolated Comamonas sp. strain E6, which utilizes terephthalate (TPA) as the sole carbon and energy source via the protocatechuate (PCA) 4,5-cleavage pathway. Two almost identical TPA degradation gene clusters, tphR(I)C(I)A2(I)A3(I)B(I)A1(I) and tphR(II)C(II)A2(II)A3(II)B(II)A1(II), were isolated from this strain. Based on amino acid sequence similarity, the genes tphR, tphC, tphA2, tphA3, tphB, and tphA1 were predicted to code, respectively, for an IclR-type transcriptional regulator, a periplasmic TPA binding receptor, the large subunit of the oxygenase component of TPA 1,2-dioxygenase (TPADO), the small subunit of the oxygenase component of TPADO, a 1,2-dihydroxy-3,5-cyclohexadiene-1,4-dicarboxylate (DCD) dehydrogenase, and a reductase component of TPADO. The growth of E6 on TPA was not affected by disruption of either tphA2(I) or tphA2(II) singly; however, the tphA2(I) tphA2(II) double mutant no longer grew on TPA, suggesting that both TPADO genes are involved in TPA degradation. Introduction of a plasmid carrying tphR(II)C(II)A2(II)A3(II)B(II)A1(II) conferred the TPA utilization phenotype on Comamonas testosteroni IAM 1152, which is able to grow on PCA but not on TPA. Disruption of either tphR(II) or tphC(II) on this plasmid resulted in the loss of the growth of IAM 1152 on TPA, suggesting that these genes are essential to convert TPA to PCA in E6. The genes tphA1(II), tphA2(II), tphA3(II), and tphB(II) were expressed in Escherichia coli, and the resultant cell extracts containing TphA1(II), TphA2(II), and TphA3(II) converted TPA in the presence of NADPH into a product which was transformed to PCA by TphB(II). On the basis of these results, TPADO was strongly suggested to be a two-component dioxygenase which consists of the terminal oxygenase component (TphA2 and TphA3) and the reductase (TphA1), and tphB codes for the DCD dehydrogenase