I. Suppression by compound 48/80 of bacterial endotoxin-inducible monocytic tissue factor activity: direct blockade of factor VII binding to THP-1 monocytes.
Hypercoagulation with upregulated monocytic tissue factor (TF) activity often occurs under a variety of inflammatory conditions including endotoxemia. The antagonism to bacterial endotoxin (LPS) signaling often results in the depression in TF upregulation. We herein report that compound 48/80 (48/80) significantly depressed LPS-induced TF activity in human and cebus monkey peripheral blood monocytes. Employing a model monocyte-like cell line (THP-1), we explored the regulatory mechanism to identify the inhibitory site(s) of 48/80. We determine whether the inhibition results from the blockade of LPS signaling. 48/80 dose-dependently inhibited LPS-induced TF activity. Chase of LPS-challenged cells with 48/80 also significantly offset TF upregulation. In immunofluorescent approaches, FACScan analysis revealed that 48/80 had no effect on either LPS recognition or the expression of its receptors (CD14 and CD11b). Moreover, LPS-induced TF expression as well as synthesis remained unaffected in the presence of 48/80. Consistent with the independence of LPS action, 48/80 was also able to inhibit TF activity induced by A23187, ionomycin, or Quin-2 AM. Interestingly, 48/80 significantly decreased the FVII binding to either resting or LPS-challenged cells. In conclusion, our results elucidate that the inhibitory action of 48/80 was independent of LPS signaling including recognition, receptor expression, and the induced TF expression/ synthesis. However, 48/80 was able to directly block FVII binding to monocytic TF, thereby resulting in such antagonism to LPS-induced TF-initiated extrinsic coagulation.
Chu
A J
AJ
Department of Surgery, School of Medicine, Wayne State University, Detroit, MI 48201, USA. ad5742@wayne.edu
Walton
M A
MA
Seto
A
A
Fox
M J
MJ
Prasad
J K
JK
Wang
Z G
ZG
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D004731:Endotoxins / Q000494:pharmacology*; D005167:Factor VII / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D000882:Haplorhini; D006801:Humans; D008297:Male; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D013925:Thromboplastin / Q000037:antagonists & inhibitors*; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology*
D004731:Endotoxins; D003189:p-Methoxy-N-methylphenethylamine; D005167:Factor VII; D013925:Thromboplastin