Heat shock inhibition of lipopolysaccharide-mediated tumor necrosis factor expression is associated with nuclear induction of MKP-1 and inhibition of mitogen-activated protein kinase activation.
OBJECTIVE
Application of heat shock before an inflammatory stimulus often results in an attenuated response to that stimulus. As a result, it has become increasingly appreciated that heat shock may induce cross-tolerance to a variety of stimuli based on in vitro and in vivo models. Circulating peripheral blood monocytes are key mediators of cytokine release following endotoxin challenge. The mitogen-activated protein kinases play a key role in the transcriptional regulation of this response including expression of tumor necrosis factor. As such, counterregulatory phosphatases that target mitogen-activated protein kinase may play a role in this heat shock-mediated effect. We hypothesized that prior heat shock to monocytes would induce a phosphatase, MKP-1, that regulated mitogen-activated protein kinase activity and subsequently conferred cross-tolerance to lipopolysaccharide stimulation.


METHODS
Experimental.


METHODS
University research foundation laboratory.


METHODS
THP-1 human monocyte cell line.


METHODS
THP-1 cells were exposed to either heat shock (43 degrees C, 1 hr) or normothermia (37 degrees C, 1 hr) and allowed to recover before stimulation with endotoxin (lipopolysaccharide).


RESULTS
Induction of a heat shock response was determined by heat shock protein-70 expression. Tumor necrosis factor and interleukin-10 were measured by enzyme-linked immunosorbent assay to assess heat shock inhibition of lipopolysaccharide-induced gene expression. The effect of heat shock on lipopolysaccharide-mediated activation of the p38 and ERK kinases was examined by measuring phospho-specific isoforms of p38 and ERK1/2 and correlated to in vitro kinase activity. Confirmatory data were generated from experiments employing either pharmacologic inhibition or genetic deletion of MKP-1. Heat shock induced the nuclear localized phosphatase, MKP-1, that attenuated p38 and ERK kinase activity resulting in significantly diminished tumor necrosis factor expression in response to lipopolysaccharide.


CONCLUSIONS
The effect of heat shock on decreasing the tumor necrosis factor response to lipopolysaccharide is conferred by induction of MKP-1, which negatively regulates p38 and ERK kinases. Modulation of phosphatase activity may be a potential strategy for attenuating acute inflammatory responses.
Sanlorenzo
Lauren
L
Division of Critical Care Medicine, Children's Hospital Medical Center, Cincinnati, OH, USA.
Zhao
Bin
B
Spight
Donn
D
Denenberg
Alvin G
AG
Page
Kristen
K
Wong
Hector R
HR
Shanley
Thomas P
TP
D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D015536:Down-Regulation / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis / Q000502:physiology; D018869:Heat-Shock Response / Q000502:physiology*; D006801:Humans; D047468:Immunoprecipitation; D007249:Inflammation; D016753:Interleukin-10 / Q000032:analysis / Q000502:physiology; D007951:Leukemia, Myeloid; D008070:Lipopolysaccharides / Q000009:adverse effects*; D048369:MAP Kinase Kinase 1 / Q000032:analysis / Q000502:physiology*; D017737:Macrophages, Peritoneal / Q000502:physiology; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000032:analysis / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000032:analysis / Q000502:physiology*; D009000:Monocytes / Q000502:physiology; D009687:Nuclear Proteins / Q000502:physiology; D018805:Sepsis / Q000150:complications / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D015533:Transcriptional Activation / Q000502:physiology; D048069:Tumor Necrosis Factors / Q000032:analysis / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases / Q000032:analysis / Q000502:physiology*
D018840:HSP70 Heat-Shock Proteins; D008070:Lipopolysaccharides; D009687:Nuclear Proteins; D048069:Tumor Necrosis Factors; D016753:Interleukin-10; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1