Hemostatic changes in human adoptive immunotherapy with activated blood monocytes or derived macrophages

Comparative study of the effect of rivaroxaban and fondaparinux on monocyte's coagulant activity and cytokine release

OBJECTIVES

Tissue factor (TF) exposed on activated monocytes and macrophages is involved in thrombosis through activation of factor X and cytokine release, responsible for inflammation and thrombosis. We investigated the effect of two anti-factor Xa drugs: rivaroxaban, a direct anti-Xa inhibitor, and fondaparinux, an antithrombin dependent anti-Xa inhibitor, on monocyte/macrophage procoagulant activity and cytokine release.

METHODS

Rivaroxaban and fondaparinux were tested at pharmacological concentrations on LPS-activated monocytes and on THP-1 cells, a human monocytic cell line, to assess 1) TF expression by flow cytometry 2) prothrombinase activity by its coagulant activity and 3) cytokine release in cell supernatants by antibody based cytokine array and ELISA for IL-8 and TNFα.

RESULTS AND CONCLUSION

Rivaroxaban and fondaparinux did not modify TF expression level on activated cells. In contrast procoagulant activity associated to monocytes and macrophages was dose dependently inhibited by rivaroxaban, but not significantly by fondaparinux. These results could explain why patients undergoing major orthopedic surgery with rivaroxaban prophylaxis were able to achieve significant reductions in venous thromboembolism, compared with drugs commonly used, i.e. fondaparinux and low molecular weight heparin. In addition, rivaroxaban and fondaparinux suppressed some chemokine secretion produced by activated macrophages. This may also contribute to their antithrombotic effect in clinic.

Regional muramyl tripeptide phosphatidylethanolamine administration enhances hepatic immune function and tumor surveillance

BACKGROUND

Immune status of the liver may affect growth of liver metastases. We analyzed the ability of muramyl tripeptide phosphatidylethanolamine (MTP-PE), an immunomodulatory bacterial cell wall analog, to stimulate Kupffer cells (KCs) and protect against tumor growth, with or without an immunosuppressive partial hepatectomy (PH). Impact of MTP-PE's route of administration on KC function was assessed.

METHODS

Buffalo rats (n = 7 to 12/group) were treated with saline, 40 microg MTP-PE intraportally (portal) or intravenously (IV) and challenged with 5 x 10(5) hepatoma cells, and tumors counted on day 21. To assess MTP-PE's impact on KC stimulation in animals undergoing PH, a known stimulant of tumor cell growth, groups were treated with saline or MTP-PE and challenged with tumor and underwent 30% PH. KCs were harvested and analyzed for superoxide production. Statistical analysis was performed with Mann-Whitney U test or chi-square test.

RESULTS

MTP-PE-treated animals had fewer tumor nodules than control animals (19 vs 184, P <.005). MTP-PE-portal animals had fewer nodules than MTP-PE-IV (2 vs 36, P <.05). MTP-PE treatment before PH resulted in fewer tumor nodules compared with control animals (192 vs 276, P <. 05). MTP-PE administration increased macrophage superoxide production (20.6 +/- 2 vs 11.9 +/- 1.1 nmol/10(6) cells, P <.005).

CONCLUSIONS

MTP-PE improved KC function and decreased growth of microscopic tumor cells. MTP-PE's effects persist after an immunosuppressive hepatectomy. Portal administration was the most effective. MTP-PE administration may be useful as a neoadjuvant therapy for patients undergoing resection of liver malignancies.