Premium
Insulin inhibits tissue factor expression in monocytes
Author(s) -
GERRITS A. J.,
KOEKMAN C. A.,
YILDIRIM C.,
NIEUWLAND R.,
AKKERMAN J. W. N.
Publication year - 2009
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/j.1538-7836.2008.03206.x
Subject(s) - downregulation and upregulation , insulin , forskolin , medicine , endocrinology , tissue factor , monocyte , platelet , chemistry , receptor , biochemistry , coagulation , gene
Summary. Objectives: Platelets from healthy subjects are inhibited by insulin but type 2 diabetes mellitus (T2DM) platelets have become insulin‐resistant, which might explain their hyperactivity. In the present study we investigated whether monocytes are responsive to insulin. Methods and results: LPS‐induced tissue factor (TF) upregulation was measured in human monocytes and monocytic THP‐1 cells in a factor Xa generation assay. Insulin (0.1–100 nmol L −1 ) induced a dose‐dependent inhibition in both cell types and in monocytes 100 nmol L −1 insulin inhibited cytosolic, membrane‐bound and microparticle TF by 32 ± 2, 27 ± 3 and 52 ± 4% ( n = 3). Insulin induced Tyr phosphorylation of the insulin receptor (INS‐R) and formation of an INS‐R – G i α 2 complex, suggesting interference with LPS‐induced cAMP control. Indeed, insulin interfered with LPS‐induced cAMP decrease and TF upregulation in a manner similar to an inhibitor of G i (pertussis toxin) and agents that raise cAMP (iloprost, forskolin, IBMX) reduced TF upregulation. Although LPS failed to raise cytosolic Ca 2+ , quenching of Ca 2+ increases (BAPTA‐AM) reduced and induction of Ca 2+ entry (ionophore, P2X7 activation) enhanced upregulation of TF mRNA and procoagulant activity. Insulin interfered with MCP‐1‐induced Ca 2+ mobilization but not with ATP‐induced Ca 2+ rises. Conclusions: Insulin inhibits TF expression in monocytes and monocyte‐derived microparticles through interference with G i α 2 ‐mediated cAMP suppression, which attenuates Ca 2+ ‐mediated TF synthesis.