Heat shock factor 1 inhibits nuclear factor-kappaB nuclear binding activity during endotoxin tolerance and heat shock.
BACKGROUND
Sepsis, endotoxin tolerance, and heat shock (HS) all display down-regulation of innate immunity. We hypothesize that HS factor 1 (HSF-1) induces competitive inhibition of nuclear factor-kappaB (NF-kappaB)-induced signal transduction in both endotoxin tolerance and HS.


OBJECTIVE
We compared endotoxin tolerance and HS in RAW 264.7 cells. We transfected cells with an HS protein 70 (HSP70) plasmid to test whether HSP70 is the mediator of HS-induced NF-kappaB inhibition. We studied the effects of endotoxin stimulation and HS, both separately and together, on "wild-type" cells, cells transfected with the HSP70 plasmid, and cells transfected with vehicle.


RESULTS
Heat shock protein 70 plasmid-transfected cells had increased HSP70 expression and demonstrated decreased nitric oxide (NO) release and inducible NO synthase messenger RNA expression in response to endotoxin compared with wild-type and empty plasmid-transfected cells. Heat shock completely abolished subsequent NO and inducible NO synthase messenger RNA expression in wild-type cells. Heat shock factor 1 reached maximum expression 60 to 90 minutes after HS. Heat shock protein 70-transfected cells still displayed endotoxin-induced NF-kappaB nuclear binding, whereas endotoxin tolerance, HS, and exposure to HSF-1, but not exposure to an unrelated promoter, inhibited NF-kappaB nuclear binding.


CONCLUSIONS
Endotoxin tolerance and HS appear to share a common immune suppressive effect, possibly through HSF-1-mediated competitive inhibition of NF-kappaB nuclear binding.
Song
Mingchen
M
The Mechanisms and Novel Therapies for Resuscitation and Acute Illness Laboratories, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
Pinsky
Michael R
MR
Kellum
John A
JA
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004731:Endotoxins / Q000494:pharmacology / Q000502:physiology*; D050884:HSP72 Heat-Shock Proteins / Q000096:biosynthesis*; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response / Q000502:physiology*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D010957:Plasmids; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
D004268:DNA-Binding Proteins; D004731:Endotoxins; D050884:HSP72 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D016328:NF-kappa B; D014157:Transcription Factors; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II