α2-macroglobulin expression during the acute-phase response in malnourished rats

Abstract

During the acute-phase (AP) response, the synthesis rate and serum concentration of the AP protein a 2-macroglobulin (MG) increases in the rat. MG gene transcription is mainly controlled by the inflammatory cytokine IL-6 and related trans- factors, the Signal Transducers and Activators of Transcription (STAT) and CCAAT/Enhancer Binding Protein (C/EBP) . Nearly every aspect of the body's defense system· is changed in malnutrition (MN). We examined whether MN affected rat MG synthesis and STAT3 and C/EBP expression. MN was induced in male Wistar rats .by 50% food restriction during six weeks. The AP response was induced by turpentine oil injection (1 µl/g body weight). Using "rocket" immuno electrophoresis we observed that, compared to the well-nourished (WN) control, MN was associated wit increased serum MG. The AP response promoted a further rise in se rum MG. The STAT3 and C/EBP levels in the nuclear extract were examined by immunoblote analysis. In rats with MN, STAT3 was elevated and during the AP response, increased STAT3 levels were observed in both WN and MN rats. The C/EBP levels were similar in MN and WN rats however the AP response induced its significants, increase in rats with MN. Obtained results suggested that malnutrition contribute to an increased MG expression by influencing IL-6 signal transduction pathway. Malnutrition-related increased of MG synthesis could be connected with positive regulatory role of STAT3 , while the additional AP-related MG increased synthesis in malnourished rats require activit y of C/EBP .

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