Properties of the Isolated Strain of Pseudobutyrivibrio sp. and Its Effect on the Alleviation of Allergic Dermatitis in a Mouse Model.

Microbial properties of the strain MDT-5, which was isolated from the rumen of a goat, were investigated. Comparative 16S rRNA gene sequence analysis revealed that MDT-5 belongs to the family Lachnospiraceae with the highest homology to Pseudobutyrivibrio ruminis DSM 9787T. However, on the basis of the phenotypic differences between MDT-5 and P. ruminis DSM 9787T, MDT-5 was identified as a Pseudobutyrivibrio sp. MDT-5 is able to generate conjugated linoleic acid (CLA) from linoleic acid (LA), and its ability was high enough to compete for LA with other bacteria in the host intestinal tract. When MDT-5 cells were administered to mice, the fecal contents of P. ruminis and closely related strains were increased but reduced close to the basal level 48 h after administration ceased. This result suggests that MDT-5 can transit through the mouse gut over a period of a few days. Administration of MDT-5 to allergic dermatitis mice induced by repeated topical applications of oxazolone alleviated the symptoms of allergic dermatitis and the associated increase in ear thickness. This effect was found to be related to a decrease in mRNA expression of the pro-inflammatory cytokine interleukin-1β. Fecal LA level tended to decrease by MDT-5 administration, and colonic CLA level was increased in the mice administered MDT-5. These results suggest MDT-5 is useful as biological agent for alleviation of allergic dermatitis to increase CLA absorption in the large intestine.