表皮生长因子对小鼠创面组织过氧化物酶体增殖物激活受体β的调节作用

Regulation of peroxisome proliferator-activated receptor β by epidermal growth factor in wound tissue of mice with full-thickness skin defect

目的了解小鼠创面外用冻干鼠表皮生长因子（mEGF）后，过氧化物酶体增殖物激活受体β（PPAR—β）表达量的变化及对创面愈合的影响．方法于70只BALB／c小鼠背部脊柱两侧验组制作1个1．5cm、×0．5cm全层皮肤缺损创面，将左侧创面设为实验组、右侧创面作为对照组。实验组创面滴加mEGF溶液（5μg／mL）、对照组创而滴加生理盐水。（1）伤后7、11、16d各取20只小鼠，评估创面愈合率（2）伤后1、3、7、11、14、18d切取创缘组织（每时相点创面数为10个），采用免疫组织化学染色法检测PPAR—β蛋白表达，原位杂交法检测PPAR—β mRNA表达量，结果均用积分吸光度（IA）值表示．对实验数据行t检验。结果（1）创面愈合率：伤后7、11、16d，实验组创面愈合率均明显高于对照组（t值分别为3．03、6．05、11．90，P值均小于0．01）。（2）免疫组织化学检测：伤后早期PPAR—β蛋白主要表达于2组创面肉芽组织Fb以及创缘KC胞核中，创面上皮化后主要表达于新达于新生上皮及其下层Fb中，创面修复后表达逐渐减弱。实验组伤后各时相点PPAR-β蛋白表达量明显显高于对照组（t值为2．15～7．37，P〈0．05或P〈0．01），其中伤后3d达高峰[IA值为（3．46±1．33）×10^3]，此时对照组IA值为（2．35±1．09）×10^3。（3）原位杂交：伤后2组创D面PPAR—β mRNA表达均开始上调，主要阳性表达部化为创面Fh及创缘KC胞质，持续至创面上皮化基本完成时，表达量开始下降。实验组创面各时相点PPAR—B mRNA表达量均明显高于对照组（t值为2．35～6．64，P〈0．05或P〈0．01），其中伤后3d达峰值[1A值为（7．3±2．6）×10^6]，此时对照组IA值为（4．5±3．0）×10^6 结论外用mEGF可上调小鼠创面组织中PPAR—β表达并促进创面愈合。

Objective To study the effect of freeze-dried mouse epidermal growth factor （mEGF） on the expression of pernxismne proliferator-activated receptor β （PPAR-β） in mice during wound healing. Methods Full-thiukness skin defect with area of 1.5 cm × 1.5 cm was reproduced on both sides of the back of 70 BALB/c mice （2 wounds in each mouse）. The wound on the left side in each mouse was treated with 5 μg/ml, mEGF solutiml （experiment group） , and that on the right side in each mouse was treated with saline （cunlrul group）. On posl injury day （PID） 7, 11, and 16, 20 mice were used for determination of wound healing rate at each time point. On PID 1, 3, 7, 11, 14, and 18, specimens of wound edge were harvested for determination of protein and gene expression of PPAR-β with immunohistoehemical staining and in situ hyhridization, with 10 specimens at each time point （denoted as integral absorbance value）. Data were processed with t tesl. Results （ 1 ） Wound healing rate. The wound healing rate in experiment group u,, PID7, 11, and 16 was respectively higher than that in control group （with t value respectively 3.03, 6.05, 11.9, P values all below 0.01 ）. （ 2 ） Immunohistoehemical observation. In both groups, the PPAR-13 proleins highly expressed in fibroblasts of wound granulation tissues and nuclei of keratinucytes located in wound edge at earlv slage after injury, and lhey highly expressed in newly formed epidermis and their fibro-blasts in the lower layer after wound epithelization. The expression of PPAR-β protein was gradually de- creased after wound healing. The expression of PPAR-β protein at each time point in experiment group was respectively higher than that in control group （ with t values from 2.15 to 7.37, P 〈 0.05 or P 〈 0.01 ）. The expression of PPAR-13 protein peaked on PID 3 in experiment group [ （3.46±1.33 ） × 10^3 ], which was （2.35± 1.09） × 10^3 in control group. （3） In situ hybridization. The expression levels of PPAR-β mRNA in both groups were up-regulated after injury, which were mainly observed in fibroblasts of wound and cytoplasm of KC in wound edge, but they were down-regulated after wound epithelization. The expression of PPAR-β mRNA at each time point in experiment group was respectively higher than that in control group （ with t values from 2.35 to 6.64, P 〈 0.05 or P 〈 0.01 ）. The expression of PPAR-13 mRNA in both groups peaked on PID 3 [（7.3 ±2.6） ×10^6, （4.5 ±3.0） ×10^6, respectively]. Conclusions mEGF can upregulate the expression of PPAR-β in wound tissue of mice and promote wound healing.