Study On Different Expression Of PPARβ In Denatured Dermis Tissues Of Human’s Deep Second-Degree Burns And Its Significance

Objective:To compare the different expressions of PPARβ between denatured dermis tissues of human’s second-degree deep burns and normal skin tissue. To observe the dynamic variation of the expression of PPARβ in denatured dermis of human’s deep second-degree burns and to explore characteristics of expressions of PPARβ to further clarify the necessity of retaining the denatured dermis for repair of deep second-degree burns.Methods:From September2013to January2014,16cases of patients with the deep second degree burns were enrolled in the test group from the Department of Burn, Xiangya Hospital, Central South University. The patients were divided into groups with4cases each group by taking tissues on the1st day,3rd day,7th day or14th day. Three specimens came from different areas in one part of wound area in each patient and there were totally48pieces of fresh tissue specimens. Each specimen was cut into1cm×1cm×1cm in size for experiment. At the same time,4cases of normal abdominal skin from plastic patients were used as contrast. HE staining was used to observe the changes of cells and the skin tissue structures. The expressions of PPARβ in five groups were detected by immunohistochemical technique. Judging the positive results were refered to semi-quantitative grading scoring. The software of SPSS18.0was used to analyze the results. Comparison in groups was conducted with analysis of variance, and the pairwise comparison was performed with Student-Newman-Keuls(SNK) test. P<0.05was the standard of statistical significance.Results:(1) HE staining results:Normal skin tissues including well-bedded epidermis, dermis were all quite visible Collagen could be seen in order. Appendages like hair follicle was also visible in skin dermis; On the1st day after burn, corneous layered most dermis tissues were destroyed and gone. Necrotic tissues are those whose surface was covered by a thin and dark red layer, and whose cell contour and nucleus disappeared. In the residual dermis, cell nuclei became smaller and were squeezed to both sides of the cells and inflammatory cell infiltration could also be observed; On the3rd day after the burn, stratum corneum was destroyed; the cells of the epidermis layer in the residual part were swelling, with wider cell gaps filled with liquid penetrants; Collagen fibers swelled and became bigger. The denatured dermis tissues were those with cytoplasm pink-dyed and hyaline degeneration. On the7th day after burn, fibroblasts proliferated and horniness cells form a thinner cortex. On the14th day after burn, a large number of fibroblasts and keratinocytes proliferated and then new epithelium thickened.(2) The result of immunohistochemical analysis indicated that PPARβprotein in normal skin tissue was shaded light yellow or a little tan, mainly in the cell nucleus of epidermal basal cells and skin appendages including hair follicles, sweat glands and sebaceous glands. Positive cell rates in normal skin tissue and wound area in the1st,3rd,7th and14th day groups were16.67%,6.67%,15.83%,62.67%,49.16%respectively. The comprehensive score of PPARβ in normal group and every burn group had significant difference (F=90.830,P<0.01). The comprehensive score of PPARβ in normal group and wound area in the1st,3rd,7th and14th day was1.88±0.36,1.10±0.32,1.87±0.40,4.17±0.51,2.81±0.51respectively. The multiple comparison result of positive rates revealed that according to the a=0.05,except the difference of population mean between normal group and3rd day group after injury which has not been statistically significant, the rest of the overall mean of two groups has all been statistically significant. The expression of PPARβ in wound area in the1st day group was lower than that of normal skin tissues and then it began to rise to the highest on the7th day and finally returned to normal level on the14th day.Conclusion:The expression of PPARβ exists in both in the denatured dermis of human’s second-degree deep burns and normal skin. The expression of PPARβ in wound area in the1st day group was lower than that of normal skin tissues and then it began to rise to the highest on the7th day and finally returned to normal level on the14th day. PPARβmay play an important role in the renaturation of denatured dermis and the cytoprotection.