EF6265, a novel plasma carboxypeptidase B inhibitor, protects against renal dysfunction in rat thrombotic glomerulonephritis through enhancing fibrinolysis

Proteomics reveals specific biological changes induced by the normothermic machine perfusion of donor kidneys with a significant up-regulation of Latexin

Renal normothermic machine perfusion (NMP) is an organ preservation method based on the circulation of a warm (35-37 °C) perfusion solution through the renal vasculature to deliver oxygen and nutrients. However, its biological effects on marginal kidneys are unclear. We therefore used mass spectrometry to determine the proteomic profile of kidney tissue and urine from eight organs reconditioned for 120 min using a Kidney Assist device. Biopsies were taken during the pre-implantation histological evaluation (T-1), at the start of back table preparation (T0), and after 60 and 120 min of perfusion (T60, T120). Urine samples were collected at T0 (urine produced in the first 15 min after the beginning of normothermic reperfusion), T30, T60 and T120. Multiple algorithms, support vector machine learning and partial least squares discriminant analysis were used to select the most discriminative proteins during NMP. Statistical analysis revealed the upregulation of 169 proteins and the downregulation of 196 during NMP. Machine learning algorithms identified the top 50 most discriminative proteins, five of which were concomitantly upregulated (LXN, ETFB, NUDT3, CYCS and UQCRC1) and six downregulated (CFHR3, C1S, CFI, KNG1, SERPINC1 and F9) in the kidney and urine after NMP. Latexin (LXN), an endogenous carboxypeptidase inhibitor, resulted the most-upregulated protein at T120, and this result was confirmed by ELISA. In addition, functional analysis revealed that the most strongly upregulated proteins were involved in the oxidative phosphorylation system and ATP synthesis, whereas the downregulated proteins represented the complement system and coagulation cascade. Our proteomic analysis demonstrated that even brief periods of NMP induce remarkable metabolic and biochemical changes in marginal organs, which supports the use of this promising technique in the clinic.

Phosphinic Peptides as Tool Compounds for the Study of Pharmacologically Relevant Zn-Metalloproteases

Phosphinic peptides constitute an important class of bioactive compounds that have found a wide range of applications in the field of biology and pharmacology of Zn-metalloproteases, the largest family of proteases in humans. They are designed to mimic the structure of natural substrates during their proteolysis, thus acting as mechanism-based, transition state analogue inhibitors. A combination of electrostatic interactions between the phosphinic acid group and the Zn cation as well as optimal noncovalent enzyme-ligand interactions can result in both high binding affinity for the desired target and selectivity against other proteases. Due to these unique properties, phosphinic peptides have been mainly employed as tool compounds for (a) the purposes of rational drug design by serving as ligands in X-ray crystal structures of target enzymes and allowing the identification of crucial interactions that govern optimal molecular recognition, and (b) the delineation of biological pathways where Zn-metalloproteases are key regulators. For the latter objective, inhibitors of the phosphinopeptidic type have been used either unmodified or after being transformed to probes of various types, thus expanding the arsenal of functional tools available to researchers. The aim of this review is to summarize all recent research achievements in which phosphinic peptides have played a central role as tool compounds in the understanding of the mechanism and biological functions of Zn-metalloproteases in both health and disease.

The emerging role of coagulation proteases in kidney disease

A role of coagulation proteases in kidney disease beyond their function in normal haemostasis and thrombosis has long been suspected, and studies performed in the past 15 years have provided novel insights into the mechanisms involved. The expression of protease-activated receptors (PARs) in renal cells provides a molecular link between coagulation proteases and renal cell function and revitalizes research evaluating the role of haemostasis regulators in renal disease. Renal cell-specific expression and activity of coagulation proteases, their regulators and their receptors are dynamically altered during disease processes. Furthermore, renal inflammation and tissue remodelling are not only associated, but are causally linked with altered coagulation activation and protease-dependent signalling. Intriguingly, coagulation proteases signal through more than one receptor or induce formation of receptor complexes in a cell-specific manner, emphasizing context specificity. Understanding these cell-specific signalosomes and their regulation in kidney disease is crucial to unravelling the pathophysiological relevance of coagulation regulators in renal disease. In addition, the clinical availability of small molecule targeted anticoagulants as well as the development of PAR antagonists increases the need for in-depth knowledge of the mechanisms through which coagulation proteases might regulate renal physiology.

EF6265, a novel inhibitor of activated thrombin-activatable fibrinolysis inhibitor, protects against sepsis-induced organ dysfunction in rats

OBJECTIVE

Although thrombin-activatable fibrinolysis inhibitor (TAFI) has been implicated as a negative regulator of fibrinolysis, its pathophysiological significance remains to be unveiled. We performed the pharmacologic study to assess the effect of EF6265, a specific inhibitor of activated form of TAFI (TAFIa) on sepsis-induced organ dysfunction models.

DESIGN

A controlled, in vivo laboratory study.

SETTING

Company research laboratory.

SUBJECTS

Wistar and Sprague-Dawley rats.

INTERVENTIONS

Endotoxemia and sepsis models were induced by intravenous injection of lipopolysaccharide and Pseudomonas aeruginosa, respectively.

MEASUREMENTS AND MAIN RESULTS

In the endotoxemia model, posttreatment (1 hour) with EF6265 reduced fibrin deposits in the kidney and liver accompanied by no significant changes in platelet count and fibrinogen concentration in plasma. This compound also significantly decreased levels of plasma lactate dehydrogenase and aspartate aminotransferase, markers of organ dysfunction. In the sepsis model, EF6265, simultaneously administered with ceftazidime (CAZ) 2 hours after Pseudomonas aeruginosa injection, showed no influence on the antibiotic activity of CAZ. Meanwhile, it dramatically potentiated the interleukin-6-reducing effect of CAZ in plasma, suggesting that inhibition of TAFIa leads to the reduction in systemic inflammatory response associated with bacterial infection. This combined treatment also lowered plasma lactate dehydrogenase and blood urea nitrogen more potently than single treatment with CAZ.

CONCLUSIONS

These results clearly suggest that TAFI plays an important role in the deterioration of organ dysfunction in sepsis and the inhibitor of TAFIa protects against sepsis-induced tissue damage through regulation of fibrinolysis and inflammation.