CpG oligodeoxynucleotides can reverse Th2-associated allergic airway responses and alter the B7.1/B7.2 expression in a murine model of asthma

CpG oligodeoxynucleotides (CpG-ODN) administered during Ag sensitization or before Ag challenge can inhibit allergic pulmonary inflammation and airway hyperreactivity in murine models of asthma, In this study, we investigated whether CpG-ODN ran reverse an ongoing allergic pulmonary reaction in a mo use model of asthma, AKR mice were sensitized with conalbumin followed by t wo intratracheal challenges at weekly intervals. CpG-ODN was administered 2 4 h after the first Ag challenge. CpG-ODN administration reduced Ag-specifi c IgE levels, bronchoalveolar lavage fluid eosinophils, mucus production, a nd airway hyperreactivity. We found that postchallenge CpG-ODN treatment si gnificantly increased IFN-gamma concentrations and decreased IL-13, IL-4, a nd IL-5 concentrations in bronchoalveolar lavage fluids and spleen cell cul ture supernatants. Postchallenge CpG-ODN treatment also increased B7.1 mRNA expression and decreased B7.2 mRNA expression in lung tissues. These resul ts suggest that CpG-ODN may have potential for treatment of allergic asthma by suppressing Th2 responses during IgE-dependent allergic airway reaction s, The down-regulation of Th2 responses by CPG-ODN may be associated with r egulation of the costimulatory factors B7.1 and B7.2.