Interleukin-1 up-regulates the expression and activity of 26S proteasome in burned rat

Expression of IL-1 and proteasome are elevated in burned animals and patients. However, whether the increased level of IL-1 correlates with the increased activity and expression of 26S proteasome after burn has not been studied. In the present study, we investigated the role of single IL-1 factor on activation of the 26S proteasome first by injection of recombinant IL-1 into the normal rats. Results indicated that proteolytic activity and the expression of the 26S proteasome increased remarkably 24 and 48 h after-IL-1 injection, respectively. We then studied the potential role of IL-1 on activity and expression of the proteasome in the burned rat by using neutralizing monoclonal antibody against IL-1. Results demonstrated that activity and the expression of 26S proteasome were decreased partially but significantly 48 h after-burn when circulating IL-1 in injured animals was neutralized. These results indicate that IL-1 may play a key role on the activity and expression of 26S proteasome following burn. The proteasome has been verified as being deeply involved in the mechanism of accelerated muscle protein breakdown after burn, these results imply that IL-1 might be involved in the protein metabolism after-burn by activating the proteasome pathway, though protein metabolism directly affected by IL-1 had not been assessed in this study.