IFN-γ-mediated efficacy of allergen-free immunotherapy using mycobacterial antigens and CpG-ODN.

Epidemiological and experimental evidence supports the notion that microbial infections that are known to induce Th1-type immune responses can suppress Th2 immune responses, which are characteristics of allergic disorders. However, live microbial immunization might not be feasible for human immunotherapy. Here, we evaluated whether induction of Th1 immunity by the immunostimulatory sequences of CpG-oligodeoxynucleotides (CpG-ODN), with or without culture filtrate proteins (CFP), from Mycobacterium tuberculosis would suppress ongoing allergic lung disease. Presensitized and ovalbumin (OVA)-challenged mice were treated subcutaneously with CpG, or CpG in combination with CFP (CpG/CFP). After 15 days of treatment, airway inflammation and specific T- and B-cell responses were determined. Cell transfer experiments were also performed. CpG treatment attenuated airway allergic disease; however, the combination CpG/CFP treatment was significantly more effective in decreasing airway hyperresponsiveness, eosinophilia and Th2 response. When an additional intranasal dose of CFP was given, allergy was even more attenuated. The CpG/CFP therapy also reduced allergen-specific IgG1 and IgE antibodies and increased IgG2a. Transfer of spleen cells from mice immunized with CpG/CFP also reduced allergic lung inflammation. CpG/CFP treatment induced CFP-specific production of IFN-γ and IL-10 by spleen cells and increased production of IFN-γ in response to OVA. The essential role of IFN-γ for the therapeutic effect of CpG/CFP was evidenced in IFN-γ knockout mice. These results show that CpG/CFP treatment reverses established Th2 allergic responses by an IFN-γ-dependent mechanism that seems to act both locally in the lung and systemically to decrease allergen-specific Th2 responses.

Hybridization signatures of gamma-irradiated murine fetal thymus organ culture (FTOC) reveal modulation of genes associated with T-cell receptor V(D)J recombination and DNA repair.

In this study, we observed the occurrence of TRBV8.1-DB2.1 V(D)J recombination in murine fetal thymus organ culture (FTOC), in which the thymic microenvironment is mimicked. Since ionizing radiation affects T-cell development, we irradiated FTOCs with gamma rays to evaluate the modulation of genes implicated in TRBV8.1-BD2.1 rearrangements. The nylon cDNA microarray method was employed to monitor the expression of 9216 genes, which were organized in coexpression clusters. Clustering analysis showed similar expression profiling of genes implicated in the V(D)J recombination and DNA double strand break (DSB) repair processes such as XRCC4, RAG-2, Artemis and DNA-PK-cs, thus suggesting overlap between the two processes. The RUNX3 gene, whose coded protein binds to the enhancers of TR genes, was also modulated and the DNA cross-linking LR1 gene, which plays a role in the opening of hairpin DNA structures and whose expression pattern is similar to Artemis, may play a role in the control of V(D)J recombination. Furthermore, our data demonstrate that the FTOC model system and cDNA microarray method are useful tools to evidentiate genes that may play a role in both processes V(D)J recombination and DNA repair.