Differential Production of Apoptosis-Modulating Proteins in Patients with Hypertrophic Burn Scar

• Published in: The Journal of surgical research 1998-02, Vol.75 (1), p.74-80
• Main Authors: Wassermann, R.J., Polo, M., Smith, P., Wang, X., Ko, F., Robson, M.C.
• Format: Article
• Language: English
• Subjects: Adult; Apoptosis; Biological and medical sciences; burns; Burns - complications; Caspase 1; Cicatrix, Hypertrophic - etiology; Cicatrix, Hypertrophic - metabolism; Cohort Studies; Cysteine Endopeptidases - biosynthesis; Fas Ligand Protein; Female; Fibroblasts - metabolism; Humans; hypertrophic healing; Immunoenzyme Techniques; Injuries of the skin. Diseases of the skin due to physical agents; Male; Medical sciences; Membrane Glycoproteins - biosynthesis; Protein Biosynthesis; Proto-Oncogene Proteins c-bcl-2 - biosynthesis; thermal injury; Traumas. Diseases due to physical agents
• ISSN: 0022-4804; 1095-8673
• DOI: 10.1006/jsre.1998.5267

Background. 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 thebcl-2protooncogene and theFascell 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 fibroblastsin vitro,to identify differential levels of Fas,bcl-2,and interleukin converting enzyme (ICE). Methods. 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 theFas/APO-1 enzyme-linked immunosorbent assay (ELISA) and thebcl-2ELISA. Results for each assay were compared between groups by unpairedttests. Further biopsy specimens of isolated proliferative scar were usedin vitroto analyze the role of these apoptosis-modulating proteins and ICE. This immunoperoxidase technique was analyzed qualitatively. Results. The expression of thebcl-2protein 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 theFasreceptor 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-2was not detectable in these specimens. Conclusions. Differential expression of thebcl-2protooncogene and theFascell 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 ofbcl-2could be responsible for delayed fibroblast apoptosis, resulting in the disruption of normal healing and subsequent hypertrophic scarring. This is confirmed by anin vitroexamination of wound fibroblasts versus those from surrounding uninjured skin. This immuno