Dispensable role for interferon-gamma in the burn-induced acute phase response: a proteomic analysis

We examined the role of the pleiotropic cytokine interferon-gamma (IFN-gamma) in initiating the burn injury-induced acute phase response (APR). Two-dimensional (2-D) electrophoresis was used to obtain serum protein profiles from wild-type (WT) and IFN-gamma knockout mice following sham-burn or 20% burn injury. Serum 2-D images from both groups of burn-injured mice were characterized by the upregulation of a similar panel of protein spots. These included the three major murine acute phase proteins haptoglobin, serum amyloid A, and serum amyloid P, that were identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF)-mass spectrometry. Furthermore, the changes in the levels of these protein spots were very similar between these two groups of mice, as determined by image analysis. Other features of burn-induced APR such as a decrease in total serum protein concentration, an elevated circulation level of the cytokine interleukin-6 (IL-6), and activation of the IL-6 signal transduction protein STAT3 were also evaluated and found to be similar between wild-type and IFN-gamma knockout mice. These results suggest a dispensable role of IFN-gamma in the induction of the hepatic APR in mice following burn injury.