To investigate the dynamic expression of Notch1 signaling and the secretion of interleukin-6 (IL-6) and tumor necrosis factor alpha(TNF-α) from macrophage RAW264.7 cells induced by severe burn rat serum.

Twenty-four male Sprague-Dawley rats were divided into sham burn group and burn at 24 h and 7 d groups randomly, each group had eight rats. The rats of burn groups were made the third degree burns about 30% total body surface area. The serum of burn rats were collected at 24 h and 7 d after burn. The sham burn group was employed 37℃ water-bath and the serum was treated as a control. The mixed culture medium contained 20% burned serum, RAW264.7 cells were cultivated with each group of burned serum for immediate moment, 4, 8, 12, 24, 48 h. In addition, 100 ng/mL lipopolysaccharide+ 20% sham burn serum were applied to culture medium, which were employed to cultivate RAW 264.7. The Notch1 signaling of macrophages were detected after cultivation and the secretion of IL-6 and TNF-α in culture supernatants of each group was measured by enzyme linked immunosorbent assay.

(1) The expression of Notch1 protein had no obvious change at immediate moment, 4, 8, 12, 24, 48 h after stimulation of sham burn serum.(2) In burn at 24 h group, the expression of Notch 1 protein was significantly increased and as time progresses the signaling peaked. (3) In burn at 7 d group, the expression of Notch 1 protein had no obvious change, which was flat as the sham burn serum group.(4) In the mixed culture medium of lipopolysaccharide+ sham burn serum group, the level of Notch1 signaling was significantly increased after stimulation. (5) The contents of IL-6 and TNF-α in burn at 24 h group and in lipopolysaccharide+ sham burn serum group were significantly higher than those of the sham burn serum group and the burn at 7 d group.

The Notch1 signaling and the secretion of IL-6 and TNF-α of macrophage could be stimulated by burn serum and this kind of high level signaling could be imitated by lipopolysaccharide.