Wassermann R J, Polo M, Smith P, Wang X, Ko F, Robson M C
Division of Plastic & Reconstructive Surgery, University of South Carolina School of Medicine, Columbia 29203, USA.
J Surg Res. 1998 Feb 15;75(1):74-80. doi: 10.1006/jsre.1998.5267.
The biochemical and cellular pathways resulting in the production of proliferative scar in the thermally injured patient remain incompletely elucidated. A promising area of investigation is the phenomenon of programmed cell death and its modulation. The following study was designed to quantify differential levels of the bcl-2 protooncogene and the Fas cell surface receptor, two apoptosis-modulating proteins, in the peripheral blood mononuclear cell (PBMC) fractions of burn patients with hypertrophic scar versus those considered to have healed normally. The study also encompassed an immunohistochemical examination of fibroblasts in vitro, to identify differential levels of Fas, bcl-2, and interleukin converting enzyme (ICE).
PBMC fractions were isolated from two matched burn patient cohorts of 10 patients each, the experimental group carrying the clinical and histopathologic diagnosis of hypertrophic burn scar. The supernatant from each mitogenically stimulated specimen was halved and subjected to the Fas/APO-1 enzyme-linked immunosorbent assay (ELISA) and the bcl-2 ELISA. Results for each assay were compared between groups by unpaired t tests. Further biopsy specimens of isolated proliferative scar were used in vitro to analyze the role of these apoptosis-modulating proteins and ICE. This immunoperoxidase technique was analyzed qualitatively.
The expression of the bcl-2 protein in the PBMC fractions of the burn patients with hypertrophic scar is significantly elevated in comparison to the control cohort (307.72 +/- 72.29 u/ml vs 31.55 +/- 6.73 u/ml; P = 0.0042). The quantitative levels of the Fas receptor did not differ significantly between the groups, respectively (0.3988 +/- 0.179 u/ml vs 0.2899 +/- 0.066 u/ml; P = 0.5787). Immunoperoxidase staining of proliferative scar fibroblasts and those from surrounding skin revealed relatively decreased levels of membrane-bound Fas and ICE. bcl-2 was not detectable in these specimens.
Differential expression of the bcl-2 protooncogene and the Fas cell surface receptor in the PBMC fraction of patients with burn injuries may suggest a disequilibrium in a complex biochemical signaling mechanism mediating programmed cell death. The increased levels of bcl-2 could be responsible for delayed fibroblast apoptosis, resulting in the disruption of normal healing and subsequent hypertrophic scarring. This is confirmed by an in vitro examination of wound fibroblasts versus those from surrounding uninjured skin. This immunoperoxidase technique reveals a localized relative decrease in Fas and ICE, two apoptosis-inducing proteins, at the level of the fibroblast in the proliferative scar specimen.
热损伤患者中导致增生性瘢痕形成的生化和细胞途径仍未完全阐明。一个有前景的研究领域是程序性细胞死亡现象及其调节。以下研究旨在量化肥厚性瘢痕烧伤患者与正常愈合患者外周血单个核细胞（PBMC）组分中两种凋亡调节蛋白——bcl-2原癌基因和Fas细胞表面受体的差异水平。该研究还包括对体外成纤维细胞的免疫组织化学检查，以确定Fas、bcl-2和白细胞介素转化酶（ICE）的差异水平。
从两个各有10名患者的匹配烧伤患者队列中分离PBMC组分，实验组具有肥厚性烧伤瘢痕的临床和组织病理学诊断。每个经丝裂原刺激的标本的上清液分成两半，分别进行Fas/APO-1酶联免疫吸附测定（ELISA）和bcl-2 ELISA。通过不成对t检验比较两组间各测定结果。分离的增生性瘢痕的进一步活检标本用于体外分析这些凋亡调节蛋白和ICE的作用。对这种免疫过氧化物酶技术进行定性分析。
与对照组相比，肥厚性瘢痕烧伤患者PBMC组分中bcl-2蛋白的表达显著升高（307.72±72.29 u/ml对31.55±6.73 u/ml；P = 0.0042）。两组间Fas受体的定量水平无显著差异（0.3988±0.179 u/ml对0.2899±0.066 u/ml；P = 0.5787）。增生性瘢痕成纤维细胞和周围皮肤成纤维细胞的免疫过氧化物酶染色显示膜结合Fas和ICE水平相对降低。在这些标本中未检测到bcl-2。
烧伤患者PBMC组分中bcl-2原癌基因和Fas细胞表面受体的差异表达可能提示介导程序性细胞死亡的复杂生化信号机制失衡。bcl-2水平升高可能导致成纤维细胞凋亡延迟，从而破坏正常愈合并导致随后的肥厚性瘢痕形成。对伤口成纤维细胞与周围未受伤皮肤成纤维细胞的体外检查证实了这一点。这种免疫过氧化物酶技术显示增生性瘢痕标本中，在成纤维细胞水平上，两种凋亡诱导蛋白Fas和ICE出现局部相对减少。
