Beneficial effects of extracts from Lucilia sericata maggots on burn wounds in rats - PubMed (original) (raw)

Beneficial effects of extracts from Lucilia sericata maggots on burn wounds in rats

Haixu Bian et al. Mol Med Rep. 2017 Nov.

Abstract

Lucilia sericata maggots have beneficial properties; however, their protective effects on burn wounds have yet to be fully elucidated. In the present study, a deep second‑degree burn rat model was used to investigate the burn wound healing properties of aqueous extract of maggots (MAE). The anti‑inflammatory, antioxidative and antibacterial activities were examined. In addition, the protein expression levels of Akt, vascular endothelial growth factor A (VEGFA) and nuclear factor‑κB (NF‑κB) were detected by western blotting. The findings of the present study revealed that MAE treatment increased burn wound healing and hydroxyproline content in the burn‑treated rats. A total of seven compounds (MAE‑P1‑P7) were separated from MAE and a comparative study was performed to identify the major active component. The results demonstrated that MAE‑P6 exerted greater antibacterial activity compared with the other compounds. MAE‑P6 treatment reduced tissue levels of malondialdehyde, tumor necrosis factor‑α and interleukin‑6, and increased superoxide dismutase activity. Furthermore, MAE‑P6 increased the expression levels of VEGFA and reduced NF‑κB expression through Akt, which was verified by treatment with the Akt‑specific inhibitor, LY294002. In conclusion, the present study demonstrated that the beneficial effects of MAE on burn wound healing were due to its antibacterial, antioxidative and anti‑inflammatory activities. MAE‑P6 reduced the release of inflammatory cytokines via the Akt/NF‑κB signaling pathway, and regulated angiogenesis and vasopermeability via the Akt/VEGFA pathway.

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Figures

Figure 1.

Figure 1.

MAE exerted a burn wound healing effect. (A) Wound appearance following 14 days of treatment with MAE. MAE increased wound healing compared with the model group. (B) Effects of MAE on hydroxyproline levels in the burn wound model. Data are expressed as the mean ± standard deviation. ##P<0.05 vs. the control group, **P<0.05 vs. the model group. MAE, aqueous extract of maggots; JWH, Jingwanhong ointment.

Figure 2.

Figure 2.

Partial purification and characterization of antibacterial components of MAE. (A) UV absorption characteristics of the various components. (B) Antibacterial tests. Various components (P1-P7) were tested on Escherichia coli (dose, 50 µg/ml). The antibacterial activity of P2 and P6 is presented. (C) SDS-PAGE analysis of the different components. Lane 1, P1; lane 2, P2; lane 3, P3; lane 4, P4; lane 5, P5; lane 6, P6; lane 7, P7. (D) Effects of MAE P1-P7 on hydroxyproline levels in the burn wound model. Data are expressed as the mean ± standard deviation. ##P<0.05 vs. the control group, **P<0.05 vs. the model group. MAE, aqueous extract of maggots.

Figure 3.

Figure 3.

Effects of MAE-P6 on oxidative damage and inflammation. The levels of (A) MDA, (B) TNF-α and (C) IL-6 were increased, whereas the levels of (D) SOD were decreased in the burn model. Application of MAE-P6 following burn treatment led to a significant increase in the activity of SOD and a reduction in the levels of MDA, TNF-α and IL-6 after 14 days of treatment. Data are expressed as the mean ± standard deviation. ##P<0.05 vs. the control group, **P<0.05 vs. the model group. MDA, malondialdehyde; MAE-P6, aqueous extract of maggots-compound 6; JWH, Jingwanhong ointment; TNF-α, tumor necrosis factor-α; IL-6, interleukin-6; SOD, superoxide dismutase.

Figure 4.

Figure 4.

Effects of MAE-P6 on MVD and VEGFA expression in the wound tissues. Wound tissue sections were collected 14 days after burning. (A) MVD and (B) VEGFA were detected using anti-rat cluster of differentiation 31 monoclonal antibody and mouse anti-rat VEGFA monoclonal antibody, respectively. The number of microvessels counted per mm2 was considered MVD. For VEGFA, the images were analyzed using Image Pro Plus version 6.0. Data are expressed as the mean ± standard deviation. ##P<0.05 vs. the control group, **P<0.05 vs. the model group. MVD, microvessel density; MAE-P6, aqueous extract of maggots-compound 6; JWH, Jingwanhong ointment; VEGFA, vascular endothelial growth factor A.

Figure 5.

Figure 5.

Effects of MAE-P6 on the expression of Akt, NF-κB and VEGFA. Rats were sacrificed 14 days after the burn treatment and tissue lysates were prepared to determine the protein expression levels of Akt, p-Akt, NF-κB and VEGFA using western blot analysis. Data are expressed as the mean ± standard deviation. ##P<0.05 vs. the control group, **P<0.05 vs. the model group, &&P<0.05 vs. the MAE-P6 group. p-Akt, phosphorylated-Akt; NF-κB, nuclear factor-κB; VEGFA, vascular endothelial growth factor A; MAE-P6, aqueous extract of maggots-compound 6.

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