Lactobacillus acidophilus Strain L-92 Induces CD4+CD25+Foxp3+ Regulatory T Cells and Suppresses Allergic Contact Dermatitis

The anti-allergic mechanism of heat-killed Lactobacillus acidophilus strain L-92 has not been fully investigated. Recent studies have reported that CD4(+)CD25(+)Foxp3(+) (forkhead box P3) T regulatory (Treg) cells play important roles in controlling allergic diseases. Hence, we examined the effect of orally administered L-92 on CD4(+)CD25(+)Foxp3(+) cell populations. BALB/c mice were supplemented daily with L-92 by gavage for 5 weeks. 2,4-Dinitrofluorobenzene (DNFB) was used to induce allergic contact dermatitis (ACD) in mice. Fluorescent-activated cell sorter (FACS) analysis was used to determine CD4(+)CD25(+)Foxp3(+) T cell populations in spleen and cervical lymph nodes (CLN). Interleukin-10 (IL-10), transforming growth factor-beta (TGF-beta), and Foxp3 mRNA expressions in mouse ear skin were investigated by real-time reverse transcription-polymerase chain reaction (RT-PCR). The percentage of CD4(+)CD25(+)Foxp3(+) T cell populations were significantly increased in both spleen and CLN of L-92-fed group than vehicle and control. In addition, L-92 produced higher levels of Foxp3, IL-10 and TGF-beta compared to control mice. These results suggest that L-92 can up-regulate the number of Treg cells to suppress the progression of DNFB-induced contact dermatitis in mice.