PPARα-Dependent and Independent Mechanisms Are Complexly Involved in the Ameliorative Effect of a Dietary Supplement Containing Lactic Acid Bacteria in a Dry Eye Mouse Model

PURPOSE: WB2000, has been shown to provide significant ameliorative effects in patients. However, the mechanism of the supplement has not been elucidated. In this study, we investigated the mechanism of the supplement on dry eye symptoms using an air stress-induced dry eye mice. METHODS: Stress-induced dry eye in mice was produced by exposing the mice to an air stream. OPTIADE® DE was administered for 5 days during the daily exposure to the air stress, and then the tear volume and the expression of specific mRNA were measured. Furthermore, the effects of WB2000 and the other nutritional ingredients were also investigated, respectively. The contribution of peroxisome proliferator-activated receptor α (PPARα) to the regulation of tear secretion was investigated by an inhibitor of PPARα. RESULTS: Exposure of the mice to air stress displayed a remarkable decrease in the tear volume with a concomitant reduction in the PPARα expression in the lacrimal gland. OPTIADE® DE significantly inhibited the decrease in the tear volume and the expression of the PPARα. WB2000 and the other nutritional ingredients additively inhibited the decrease in the tear volume. Inhibition of PPARα completely canceled the effects of the OPTIADE® DE and WB2000 without influencing the effect of the mixture of other nutritional ingredients on the tear volume. CONCLUSION: These results suggest that both the PPARα-dependent pathway and the independent pathway contributed to the ameliorative effect of OPTIADE® DE in the dry eye mice.