Lactobacillus acidophilus L-92 strain (L-92) was selected as the Lactic acid bacterium (LAB) which is highly effective against allergic diseases. Previous studies indicate that L-92 is useful in improving symptoms of allergic diseases, such as Japanese ceder pollen allergy, perennial allergic rhinitis and atopic dermatitis. Also, previous studies in mode of action indicate that L-92 may act through multiple ways, such as improving Th1/Th2 balance that generally known as anti-allergic effects mechanism of LAB, inducing apoptosis of activated T cells, inducing regulatory T cells and so on. This manuscript presents anti-allergic effects of L-92 for humans and anti-allergic mechanisms which have been revealed.

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We investigated the anti-allergic effect and the mechanism of the heat-killed Lactobacillus plantarum FG4-4 strain(FG4-4) isolated from the Japanese traditional fermented tea, the ‘Awaban tea' . NC/Nga mice, atopic dermatitis model mice, were divided into three groups that were fed a diet containing 0%(control), 0.05% or 0.5% of FG4-4, respectively. Fifteen days after the start of administration, these mice were sensitized by the topical application of picryl chloride (first sensitization). Four days after the first sensitization, these mice were boosted with picryl chloride by topical application once a week for 10 weeks. We measured the clinical score, ear thickness and serum IgE level with time. The clinical score, ear thickness and serum IgE level in the 0.05% and 0.5% FG4-4 groups were significantly lower than those in the control group. At 89 days, the ability of various cytokine and IgE productions of Peyer's patch (PP) cells and splenocytes were measured by ELISA. The ability of IgE production of PP cells and splenocytes in the 0.05% and 0.5% FG4-4 groups were significantly lower than those in the control group, and the ability of Th1 cytokine (IL-12 and IFN-γ) productions of PP cells and splenocytes in the 0.05% and 0.5% FG4-4groups were significantly higher than those in the control group. The ability of the Th2 cytokine (IL-4) production of PP cells in the 0.5% FG4-4 group was significantly lower than that in the control group. The abilities of IL-10 and IL-17 productions of PP cells and splenocytes in the 0.05% and 0.5% FG4-4 groups were significantly higher and lower than those in the control group, respectively. These results suggest that orally administrated FG4-4 has antiallergic effect through the improvement of the Th1/Th2 balance and inhibition of IgE production. Furthermore, we suggest that FG4-4 reduces the atopic dermatitis through enhancement of Treg cells and inhibition of Th17 cells.

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