Recombinant Lactobacillus plantarum inhibits house dust mite-specific T-cell responses

Recent evidence suggests that chronic exposure to lactobacilli, which are p art of the normal intestinal flora, inhibits the development of allergic di sorders. Allergy is mediated by Th2 cells, which produce high levels of IL4 and IL5, and suppressive effects of lactic acid bacteria on the developmen t of allergy have been attributed to their Th1-inducing properties. On the other hand, lactic acid bacteria have also been shown to suppress autoimmun e disorders which are mediated by Th1 cells producing high levels of IFN ga mma. To study this apparent discrepancy, the immunomodulatory potential of lactobacilli was evaluated using recombinants that express an immunodominan t T-cell epitope of Der p 1 of house dust mites. Mucosal immunization of C5 7BL/6 J mice with such recombinants resulted in the induction of T cells wh ich produced low amounts of IFN gamma. Immunization with the house dust mit e peptide followed by treatment with recombinant Lactobacillus plantarum re sulted in the inhibition of both IFN gamma and IL5 production. The effect o n IFN gamma production was shown to be a non-specific effect of L. plantaru m. The effect on IL5 production, however, was only observed when the recomb inant expressing the Der p 1 peptide, but not the control recombinant, was used for treatment. Neither of the recombinants had an effect on the antibo dy response. Taken together, these data suggest that recombinant L. plantar um may be a suitable candidate for the treatment of allergic disorders.