Anti-inflammatory effect of selective estrogen receptor modulators (SERMs) in microglial cells.
OBJECTIVE
Our aim was to study how different SERMs modulate the inflammatory responses induced by lipopolysaccharide (LPS) or unmethylated CpG-oligonucleotides in mouse and rat microglial cells.


METHODS
Inflammatory responses of mouse N9 microglial cells and rat primary hippocampal microglia to lipopolysaccharide (LPS) exposure were recorded by the secretion of nitric oxide (NO) and cytokine IL-6 in two models where SERM was added either 24 h before LPS addition or simultaneously or even after the LPS exposure. The responses of 17beta-estradiol, tamoxifen, raloxifene and ICI 182.780 were compared. Responses were recorded by ELISA, Northern and EMSA assays.


RESULTS
SERMs but not 17beta-estradiol induced a significant, concentration-dependent anti-inflammatory response both in rat primary microglial cells and in mouse N9 microglial cells. The response was observed both in NO and IL-6 secretion as well as in total IL-6 mRNA expression. We have recently observed that histone deacetylase (HDAC) inhibitors can potentiate the LPS-induced inflammatory response. Raloxifene and tamoxifen inhibited the potentiation of LPS response induced by trichostatin A, an HDAC inhibitor, in N9 microglia. A SERM-induced anti-inflammatory response was observed in acute models where SERM was added simultaneously or even up to 6 h later than LPS exposure. In contrast, the pretreatment of N9 microglia with tamoxifen or raloxifene for 30 h before LPS exposure did not provide any protection against the LPS response. We also observed that the raloxifene-induced protection in N9 microglia was connected to a decline of LPS-induced DNA binding activity of AP-1 but not that of NF-kappaB transcription factors.


CONCLUSIONS
Our results show that tamoxifen, raloxifene and ICI 182.780 induce an anti-inflammatory response in acute models of mouse and rat microglial cells. It seems that this response is not estrogen receptor-mediated but, probably, is attributable to some SERM-induced modulation of LPS-activated pro-inflammatory signalling cascades.
Suuronen
T
T
Department of Neuroscience and Neurology, University of Kuopio, PO Box 1627, 70211 Kuopio, Finland.
Nuutinen
T
T
Huuskonen
J
J
Ojala
J
J
Thornell
A
A
Salminen
A
A
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001253:Astrocytes / Q000166:cytology; D015152:Blotting, Northern; D049109:Cell Proliferation; D002478:Cells, Cultured; D018899:CpG Islands; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004797:Enzyme-Linked Immunosorbent Assay; D004958:Estradiol / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D000077267:Fulvestrant; D006624:Hippocampus / Q000166:cytology; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000188:drug therapy*; D015850:Interleukin-6 / Q000097:blood / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism; D051379:Mice; D017628:Microglia / Q000378:metabolism / Q000473:pathology*; D009569:Nitric Oxide / Q000378:metabolism; D009841:Oligonucleotides / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D020849:Raloxifene Hydrochloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology*; D013629:Tamoxifen / Q000494:pharmacology; D013997:Time Factors
D000893:Anti-Inflammatory Agents; D056572:Histone Deacetylase Inhibitors; D015850:Interleukin-6; D008070:Lipopolysaccharides; D009841:Oligonucleotides; D012333:RNA, Messenger; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; D000077267:Fulvestrant; D009569:Nitric Oxide; D020849:Raloxifene Hydrochloride; D004958:Estradiol; D004247:DNA; D007770:L-Lactate Dehydrogenase; D006655:Histone Deacetylases