Oral administration of whole dihomo-γ-linolenic acid-producing yeast suppresses allergic contact dermatitis in mice.

Dihomo-γ-linolenic acid (DGLA, C20: 3n-6) is known to have an anti-inflammatory activity, but its range of effects was not well studied because of its limited natural sources. We addressed these issues by constructing an yeast Saccharomyces cerevisiae strain having a complete metabolic pathway for DGLA synthesis by introducing two desaturase and one elongase genes to convert endogenous oleic acid to DGLA. Taking advantage of well-known safety of S. cerevisiae, we previously investigated the efficacy of heat-killed whole DGLA-producing yeast cells on irritant contact dermatitis, and showed that oral intake of this yeast significantly suppressed inflammatory reactions, whereas no such suppression was observed by the intake of 25 times the amount of purified DGLA. Since this method is considered to be a simple and efficient way to suppress inflammation, we examined its effectiveness against allergic contact dermatitis (ACD) in this study and showed that this method was also effective against ACD.