Submitted on February 24, 2005
Accepted on December 5, 2005
Febrile-range temperature but not heat shock augments the acute phase response to interleukin-6 in human hepatoma cells
Stephen J. Wigmore1*, Kenneth C.H. Fearon2, James A. Ross2, Stephen J. McNally2, William J. Welch3, and O James Garden2
1 Tissue Injury and Repair Group, MRC Centre for Inflammation Research, Medical School, University of Edinburgh, Edinburgh, Scotland, United Kingdom; Surgical Research Laboratory, University of California San Francisco, San Francisco General Hospital, San Francisco, California, USA
2 Tissue Injury and Repair Group, MRC Centre for Inflammation Research, Medical School, University of Edinburgh, Edinburgh, Scotland, United Kingdom
3 Surgical Research Laboratory, University of California San Francisco, San Francisco General Hospital, San Francisco, California, USA
* To whom correspondence should be addressed. E-mail: s.wigmore{at}ed.ac.uk.
The relationship between the stress protein response and the acute phase response (APPR) was studied in human hepatoma cells to investigate the hierarchy of regulation of these survival responses. Huh-7 cells were subjected to heat treatment (febrile range temperature 40°C or heat shock 43°C) followed by recovery at 37°C in the presence or absence of interleukin-6 given either before or after heat treatment. The effects on total, fractional and acute phase protein synthesis were then analyzed by metabolic labeling, ELISA, real time PCR, northern blot analysis and activation of an 
1-antitrypsin reporter plasmid. Cell energetics were studied under the same conditions using an index of mitochondrial activity and measurement of cellular ATP levels. Febrile range temperature (40°C) augmented acute phase protein production when cells had been pre-treated with interleukin-6. Pre-treatment of cells with IL-6 also prevented heat shock-induced suppression of 1-antichymotrypsin (ACT) but not transferrin (TRF). mRNA expression of ACT and 1-antitrypsin reporter activation studies were consistent with transcriptional regulation of these proteins. Expression of mRNA transcripts for transferrin was increased despite protein expression being reduced by heat shock. The effects of heat shock on acute phase protein synthesis can be modified by pre-incubation with interleukin-6 whereas addition of this ligand after heat treatment has no effect on the suppressive effect of heat on the APPR. The mechanism of this action appears to be transcriptionally regulated in the case of ACT but in the case of transferrin may be mediated by another process such as post-translational modification.
