[Effects and mechanism of astragalus polysaccharide on wound healing of deep partial-thickness burns in rats]

Objective: To investigate the effects and mechanism of astragalus polysaccharide (APS) on wound healing of deep partial-thickness burns in rats. Methods: The experimental study method was used. Fifty 7-week-old male Sprague-Dawley rats were divided into normal group, simple burn group, APS group, inhibitor group, and inhibitor+APS group according to the random number table, with 10 rats in each group. Except for normal group, rats in the other 4 groups were inflicted with a deep partial-thickness burn wound on the back. Rats in normal group and simple burn group were intraperitoneally injected with normal saline, and rats in the other three groups were injected with APS and/or integrin-linked kinase (ILK) inhibitor, respectively. After 7 days of injection, the wound healing rate of rats with burns in the four groups was calculated, and the serum content of interferon-γ, interleukin-2 (IL-2), and tumor necrosis factor α (TNF-α) in rats in 5 groups was determined by enzyme-linked immunosorbent assay (ELISA). The normal skin tissue of rats in normal group and wound tissue of rats with burns in the four groups were taken, the water content was determined and the water ratio was calculated, the content of interferon-γ, IL-2, and TNF-α was detected by ELISA, the mRNA expressions of epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and ILK were detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction, and the protein expressions of ILK, protein kinase B (Akt), phosphorylated Akt (p-Akt), glycogen synthetic kinase-3β (GSK-3β), and phosphorylated GSK-3β (p-GSK-3β) were detected by Western blotting. Data were statistically analyzed with one-way analysis of variance and least significant difference test. Results: After 7 days of injection, the wound healing rate of rats in APS group was (67±5)%, which was significantly higher than (52±4)% in simple burn group and (59±5)% in inhibitor+APS group (with all the P values <0.05). The wound healing rate of rats in inhibitor+APS group was significantly higher than (48±4)% in inhibitor group (P<0.05). After 7 days of injection, compared with those in serum or normal skin tissue of rats in normal group, the serum content of interferon-γ, TNF-α, IL-2 and the water ratio of wound tissue of rats in simple burn group were significantly increased (P<0.05); compared with those in APS group, the serum content of interferon-γ, TNF-α, IL-2 and the water ratio of wound tissue of rats in simple burn group and inhibitor+APS group were significantly increased (P<0.05); compared with those in inhibitor group, the serum content of interferon-γ, TNF-α, IL-2 and the water ratio of wound tissue of rats in inhibitor+APS group were significantly decreased (P<0.05). After 7 days of injection, compared with that in normal skin tissue of rats in normal group, the content of interferon-γ, TNF-α, and IL-2 in wound tissue of rats in simple burn group was significantly increased (P<0.05); compared with that in APS group, the content of interferon-γ, TNF-α, and IL-2 in wound tissue of rats in simple burn group and inhibitor+APS group was significantly increased (P<0.05); compared with that in inhibitor group, the content of interferon-γ, TNF-α, and IL-2 in wound tissue of rats in inhibitor+APS group was significantly decreased (P<0.05). After 7 days of injection, compared with those in normal skin tissue of rats in normal group, the mRNA expressions of EGF, bFGF, ILK and protein expressions of ILK, p-Akt, p-GSK-3β in wound tissue of rats in simple burn group were significantly increased (P<0.05); compared with those in APS group, the mRNA expressions of EGF, bFGF, ILK and protein expressions of ILK, p-Akt, p-GSK-3β in wound tissue of rats in simple burn group and inhibitor+APS group were significantly decreased (P<0.05); compared with those in inhibitor group, the mRNA expressions of EGF, bFGF, ILK and protein expressions of ILK, p-Akt, p-GSK-3β in wound tissue of rats in inhibitor+APS group were significantly increased (P<0.05). There were no statistically significant differences in the protein expressions of Akt and GSK-3β in normal skin tissue of rats in normal group and wound tissue of rats with burns in the four groups (P>0.05). Conclusions: APS can alleviate systemic and local inflammation, alleviate tissue edema, and promote the expressions of healing factors in rats with deep partial-thickness burns, thus to promote the wound healing, possibly by activating ILK/Akt/GSK-3β signaling pathway.