Joon Young Song

Regulation of interleukin-4 on collagen gene expression by systemic sclerosis fibroblasts in culture.

This study was performed to evaluate the transcriptional regulation of interleukin-4 (IL-4) on collagen gene expression in systemic sclerosis (SSc) fibroblasts. The pro alpha 2(I) collagen promotor activity has been examined by transfection experiments and chloramphenicol acetyl transferase (CAT) assay. Maximal elevation of collagen synthesis was presented at a concentration of 5 ng/ml of IL-4. In the CAT assay, the percentage of acetylation was 7.0% +/- 2.0% in untreated controls and 12.5% +/- 3.5% in SSc fibroblasts at 5.0 ng/ml of IL-4. In normal skin (NS), 3.5% +/- 1.0%, and 10.2% +/- 2.5% were acetylated, respectively. The promoter activity was increased 1.8 +/- 0.7-fold and 2.9 +/- 1.3-fold in IL-4-treated SSc and NS, respectively, as compared to untreated groups. In Northern and dot-blot analysis, the level of types I and III collagen mRNA increased 1.1 +/- 0.3-fold and 1.3 +/- 0.3-fold, respectively, in IL-4-treated SSc fibroblasts compared to 3.0 +/- 0.4-fold and 3.0 +/- 0.3-fold, respectively, in NS fibroblasts. These data may indicate that IL-4 could be important in promoting biogenesis of collagen proteins by increased stability and transcription of the collagen mRNA. Also, transcriptional activation of collagen gene expression appears to have a less sensitive effect on SSc than on NS.

Collagen mRNA expression detected by in situ hybridization in keloid tissue

The keloid fibroblasts exhibited increased extracellular matrix gene expression, and prominent elevated type I procollagen mRNA when compared to control fibroblasts cultured from the uninvolved skin of normal people. It also showed markedly elevated type I/III procollagen mRNA ratios, but no synthesis of type IV procollagen mRNA by keloid fibroblasts was observed. By in situ hybridization in keloid tissue, high levels of type I and type III procollagen mRNAs were detected in most of the fibroblasts, suggesting the presence of a subpopulation responsible for the increased collagen production. The levels of type I and type III procollagen mRNAs in these fibroblasts were clearly elevated compared to control skin specimens. And concentration of type I procollagen mRNA was found more predominantly than was type III. These results suggest that deposition of collagen in keloid could result from activation of certain fibroblasts responsible for type I procollagen production.

Effects of x-irradiation on survival and extracellular matrix gene expression of cultured keloid fibroblasts

Survival and extracellular matrix gene expression were studied by viable cell count assay and Northern transfer analysis to compare the sensitivity of normal skin and keloid fibroblasts towards x-irradiation. As the dosage of radiation increased, the numbers of viable cells in irradiated groups were remarkably decreased exponentially, with no significant difference between normal and keloid cell lines. By Northern blot analysis, there was no change in size of the mRNAs for pro alpha 1(I) collagen, fibronectin and beta-actin. By slot-blot hybridization, pro alpha 1(I) collagen mRNA levels in x-irradiated fibroblasts were markedly decreased compared with non-irradiated controls. The amounts of fibronectin and beta-actin mRNAs were also decreased. This study suggests that both normal skin and keloid fibroblasts are sensitive to x-irradiation, and that extracellular matrix gene expression is also affected by such exposure.