B bifidum actively changes the gene expression profile induced by L acidophilus in murine dendritic cells

Dendritic cells (DC) play a pivotal regulatory role in activation of the innate as well as the adaptive part of the immune system by responding to environmental microorganisms. We have previously shown that some lactobacilli strains induce a strong production of the pro-inflammatory and Th1 polarizing cytokine IL-12 in DC. Contrary, bifidobacteria do not induce IL-12, but are able to inhibit the IL-12 production induced by lactobacilli. In the present study, genome wide microarrays were used to investigate the maturation and gene expression pattern murine bone marrow derived DC stimulated with Lactobacillus acidophilus NCFM and Bifidobacterium bifidum Z9. L. acidophilus NCFM strongly induced expression of interferon (IFN)-, multiple virus defence genes, and cytokine and chemokine genes related to both the adaptive and the innate immune response. Contrary, B. bifidum Z9 mostly up-regulated genes encoding cytokines and chemokines related to the innate immune response. Moreover, B. bifidum Z9 inhibited the expression of the genes initiating the adaptive immune response induced by L. acidophilus NCFM and had an additive effect on genes of the innate immune response and some Th2 skewing genes. The gene encoding Jun dimerization protein 2 (JDP2), a key regulator in cell signalling, was one of the few genes only induced by B. bifidum Z9. Blocking of the JNK1/2 pathway completely inhibited the gene expression of Ifn-. We suggest that B. bifidum Z9 employs an active mechanism to inhibit induction of genes in DC triggering the adaptive immune system and that JPD2 is involved in the regulatory mechanism.

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Weiss G, Rasmussen S, Nielsen Fink L, Jarmer H, Nøhr Nielsen B, Frøkiaer H