Lipopolysaccharide appears to activate human endometrial endothelial cells through TLR-4-dependent and TLR-4-independent mechanisms.
OBJECTIVE
Uterine innate immunity remains poorly characterized, and while endometrial endothelial cells are known to express Toll-like receptors (TLRs), little is known about their function in these cells. The present study evaluated the effect of Gram-negative bacterial lipopolysaccharide (LPS) on human endometrial endothelial cell (HEECs) cytokine secretion and tissue factor expression, and the role of TLR-4 in these responses.


METHODS
Human endometrial endothelial cells were treated with or without LPS ± LPS-RS, a TLR-4 antagonist, via the binding of MD-2. After 24 hr, cell-free supernatants were evaluated for cytokines by multiplex analysis and cell lysates were analyzed for tissue factor expression by Western blot.


RESULTS
Treatment of HEECs with LPS significantly upregulated the secretion of IL-6, IL-8, and G-CSF, and this was prevented by LPS-RS. LPS also induced tissue factor expression by the HEECs; however, this was unaffected by LPS-RS.


CONCLUSIONS
These findings suggest that TLR-4 is functional in HEECs and its activation by bacterial LPS induces a specific cytokine/chemokine response. However, bacterial LPS also induced tissue factor expression in what seemed to be a TLR-4-independent fashion, suggesting that this bacterial component can act on the HEECs through TLR-4-dependent and TLR-4-independent pathways. These findings indicate that endometrial endothelial cells may play an active role in uterine innate immunity.
Department of Obstetrics, Gynecology & Reproductive Sciences, Yale University School of Medicine, New Haven, CT 06510, USA. graciela.krikun@yale.edu
Graciela
G
Krikun
Jordan
J
Trezza
Jeff
J
Shaw
Mizan
M
Rahman
Seth
S
Guller
Vikki M
VM
Abrahams
Charles J
CJ
Lockwood
D002478:Cells, Cultured; D004717:Endometrium / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000235:genetics / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects*; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology; D016209:Interleukin-8 / Q000235:genetics / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051218:Lymphocyte Antigen 96 / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D013925:Thromboplastin / Q000235:genetics / Q000276:immunology; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology*; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
C508606:CXCL8 protein, human; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; C495377:LY96 protein, human; D008070:Lipopolysaccharides; D051218:Lymphocyte Antigen 96; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D016179:Granulocyte Colony-Stimulating Factor; D013925:Thromboplastin