Hexose sugars differentially alter collagen gene expression and synthesis in fibroblasts derived from granulation tissue, hypertrophic scar and keloid.

Clinical observations have suggested that sugar and honey enhance granulation tissue formation and in vitro studies have shown that monosaccharide sugars stimulate mesenchymal and endothelial cells. In this study, the effects of glucose, fructose, galactose and mannose on type I and type III collagen gene expression and synthesis were studied in granulation tissue, hypertrophic scar and keloid fibroblast cultures. Glucose elevated both type I and type III collagen mRNAs in hypertrophic scar fibroblasts. Fructose increased type III collagen mRNA almost sevenfold in granulation tissue fibroblasts. Galactose caused an increase in type I and type III collagen mRNAs in granulation tissue fibroblasts and hypertrophic scar fibroblasts but, in contrast, mannose decreased type I and type III collagen levels in hypertrophic scar and keloid fibroblasts. Analysis of aminoterminal propeptides of type I and type III collagen (PINP and PIIINP) revealed that glucose decreased the amount of PINP in granulation tissue and keloid fibroblasts, whilst fructose decreased the amount in all the fibroblast cell lines studied. Galactose caused a decrease in the synthesis of type I collagen in all cell lines but a decrease was seen in type III collagen only in hypertrophic scar fibroblasts. Mannose decreased the amount of PINP in all cell lines but a decrease in the amount of PIIINP was seen only in granulation tissue fibroblasts. The effect of sugars on the ratio type I/type III collagen was negligible or decreasing with the exception of galactose, which increased the ratio in hypertrophic scar fibroblasts. The results suggest that glucose, fructose and galactose have no significant value in the stimulation of collagen synthesis in vitro. Mannose may have value in the prevention or treatment of abnormal scars.