Metabolic activation of TM5441 in vitro and in vivo: Formation of reactive metabolites and human enzymes involved

Role of plasminogen activated inhibitor-1 in the pathogenesis of anticoagulant related nephropathy

Anticoagulant related nephropathy (ARN) is the result of glomerular hemorrhage in patients on systemic anticoagulation therapy or underlying coagulopathy. Red blood cells (RBC) that passed through the glomerular filtration barrier form RBC casts in the tubules, increase oxidative stress and result in acute tubular necrosis (ATN). The mechanisms of ARN still not completely discovered. Plasminogen activator inhibitor-1 (PAI-1) plays a significant role in the maintenance of coagulation homeostasis. We developed an animal model to study ARN in 5/6 nephrectomy (5/6NE) rats. The aim of this study was to elucidate the role of PAI-1 in the ARN pathogenesis. 5/6NE rats were treated per os with warfarin (0.75 mg/kg/day) or dabigatran (150 mg/kg/day) alone or in combination with PAI-1 antagonist TM5441 (2.5, 5.0 and 10 mg/kg/day). TM5441 in a dose dependent manner ameliorated anticoagulant-induced increase in serum creatinine in 5/6NE rats. Anticoagulant-associated increase in hematuria was no affected by TM5441. The levels of reactive oxygen species (ROS) in the kidneys were in a dose-dependent manner decreased in 5/6NE rats treated with an anticoagulant and TM5441. Our data demonstrates that PAI-1 may reduce ARN by decreasing ROS in the kidneys. Glomerular hemorrhage is not affected by anti-PAI-1 treatment. These findings indicate that while symptoms of ARN can be reduced by PAI-1 inhibition, the main pathogenesis of ARN - glomerular hemorrhage - cannot be prevented.

Exosomal Plasminogen Activator Inhibitor-1 Induces Ionizing Radiation-Adaptive Glioblastoma Cachexia

Cancer cachexia is a muscle-wasting syndrome that leads to a severely compromised quality of life and increased mortality. A strong association between cachexia and poor prognosis has been demonstrated in intractable cancers, including glioblastoma (GBM). In the present study, it was demonstrated that ionizing radiation (IR), the first-line treatment for GBM, causes cancer cachexia by increasing the exosomal release of plasminogen activator inhibitor-1 (PAI-1) from glioblastoma cells. Exosomal PAI-1 delivered to the skeletal muscle is directly penetrated in the muscles and phosphorylates STAT3 to intensify muscle atrophy by activating muscle RING-finger protein-1 (MuRF1) and muscle atrophy F-box (Atrogin1); furthermore, it hampers muscle protein synthesis by inhibiting mTOR signaling. Additionally, pharmacological inhibition of PAI-1 by TM5441 inhibited muscle atrophy and rescued muscle protein synthesis, thereby providing survival benefits in a GBM orthotopic xenograft mouse model. In summary, our data delineated the role of PAI-1 in the induction of GBM cachexia associated with radiotherapy-treated GBM. Our data also indicated that targeting PAI-1 could serve as an attractive strategy for the management of GBM following radiotherapy, which would lead to a considerable improvement in the quality of life of GBM patients undergoing radiotherapy.

Small-molecule modulators of serine protease inhibitor proteins (serpins)

Serine protease inhibitors (serpins) are a large family of proteins that regulate and control crucial physiological processes, such as inflammation, coagulation, thrombosis and thrombolysis, and immune responses. The extraordinary impact that these proteins have on numerous crucial pathways makes them an attractive target for drug discovery. In this review, we discuss recent advances in research on small-molecule modulators of serpins, examine their mode of action, analyse the structural data from crystallised protein-ligand complexes, and highlight the potential obstacles and possible therapeutic perspectives. The application of in silico methods for rational drug discovery is also summarised. In addition, we stress the need for continued research in this field.

Discovery of novel (6S/12aS)-heptachpyridone capable of inhibiting thrombosis in vivo

The in vitro conversion of (1S,3S)-1-dimethoxylethyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid, (1S,3S)-DCCA, in rat plasma is monitored by HPLC-FT-ICR-MS. We show that the in vitro conversion of (1S,3S)-DCCA in rat plasma for 1 h leads to forming (6S/12aS)-bisdimethoxyethylheptachpyridone, reflecting intermolecular condensation of (1S,3S)-DCCA, and the in vitro conversion of (6S/12aS)-bisdimethoxyethylheptachpyridone in rat plasma for 1 h leads to forming (6S/12aS)-heptachpyridone, reflecting hydrolysis of (6S/12aS)-bisdimethoxyethylheptachpyridone. At a dose of 1.0 μmol/kg (6S/12aS)-heptachpyridone orally inhibits venous thrombosis and arterial thrombosis in vivo. Bleeding time, clotting time and international normalized ratio show that at this dose (6S/12aS)-heptachpyridone has no bleeding risk, does not lengthen clotting time and does not change the exogenous coagulation pathway. We also show that the reactions promoted by rat plasma are easy to practice by chemical synthesis. Thus our findings build a bridge across the in vivo conversion and the application.