Reviparin-sodium prevents complement-mediated myocardial injury in the isolated rabbit heart

Low Molecular Weight Heparin Improves Peritoneal Ultrafiltration and Blocks Complement and Coagulation

Objectives

Clinical studies have demonstrated that the intraperitoneal (IP) complement and coagulation systems are activated in peritoneal dialysis (PD) patients. In animal models, low molecular weight heparin (LMWH) was seen to inhibit peritoneal angiogenesis, and related compounds have increased ultrafiltration volumes after repeated administration to PD patients. The present study evaluated the effects of LMWH on ultrafiltration, coagulation, and complement activation during a single PD dwell.

Design

Rats were exposed to a single dose of 20 mL 2.5% glucose-based, filter-sterilized PD fluid, with or without supplementation with LMWH. The PD fluid was administered either as an IP injection or as an infusion through an indwelling catheter. The dwell fluid was analyzed 2 hours later concerning activation of the complement and coagulation cascades, chemotactic activity, neutrophil recruitment, ultrafiltration volume, and glucose and urea concentrations.

Results

Exposure to PD fluid induced activation of IP complement [formation of C3a(desArg) and increase of C5a-dependent chemotactic activity] and coagulation (formation of thrombin–antithrombin complex) and recruitment of neutrophils. In the case of IP injection, neutrophil recruitment and complement activation were inhibited by LMWH. In both models, LMWH inhibited thrombin formation, reduced complement-dependent chemotactic activity, and increased the IP fluid volume, indicating an improved ultrafiltration.

Conclusions

The acute inflammatory reaction to PD fluid involves the complement and coagulation cascades. Addition of LMWH to the PD fluid improves ultrafiltration, inhibits formation of thrombin, and potentially blocks C5a activity. The present results motivate further investigations of the IP cascade systems in PD.

Treatment of chronic renal allograft rejection in rats with a low-molecular-weight heparin (reviparin)

BACKGROUND

Low-molecular-weight heparin (LMWH) has been shown to prolong survival of rat cardiac allografts independently from immunosuppressive treatment. Furthermore, long-term treatment reduces the development of chronic graft vascular disease after experimental heart transplantation. The aim of the present study was to determine whether treatment with the LMWH reviparin has a beneficial effect on chronic rejection in a rat renal allograft model.

METHODS

Kidneys of Fisher (F344) rats were transplanted into unilaterally nephrectomized Lewis (LEW) recipients. LEW-->LEW isografts served as controls. Animals were treated with cyclosporine (5 mg/kg/d) for the first 10 days. Nephrectomy of the remaining kidney was performed after 10 days. Allografted animals were treated either with reviparin (2 mg/kg/d subcutaneously) for 24 weeks (Allo-24), from week 12 to 24 (Allo-12), or with vehicle for 24 weeks. Proteinuria was determined at regular intervals. Kidneys were harvested after 24 weeks for histomorphological and immunohistochemical evaluation.

RESULTS

No major bleeding complications were observed in reviparin-treated animals. Proteinuria was significantly reduced in allografted animals both by early as well as by late-onset treatment with reviparin. Transplant glomerulopathy was diminished in Allo-24 and in Allo-12 groups compared to vehicle-treated animals, whereas tubulointerstitial inflammation was influenced only in animals immediately treated with reviparin. Immunohistochemical studies demonstrated a marked reduction of renal monocyte and T-cell infiltration as well as expression of MHC II by treatment with reviparin.

CONCLUSIONS

Treatment with the LMWH reviparin significantly improved chronic renal allograft rejection in the F344-to-LEW rat model, both after early and late start of therapy. Although the exact mechanisms of this beneficial effect remain unclear, our data offer a potential new therapeutical approach for prevention of chronic allograft nephropathy.