Co-Administration of CpG Oligonucleotides and Chenopodium album Extract Reverse IgG2a/IgG1 Ratios and Increase IFN-Gamma and IL-10 Productions in a Murine Model of Asthma

Abstract

Asthma is a disorder of increasing severity and prevalence. Recent knowledge about the pathogenesis of asthma emphasizes its inflammatory nature. CpG oligonucleotides are a class of compounds containing motifs based on the cytosine-guanine dinucleotides (CpG-ODNs). These motifs are suppressed in mammalian DNA. They induce inflammation in mammals characterized by the induction of T helper type 1 and regulatory responses.

In this paper, the effect of CpG DNA co-administration with a homemade Chenopodium album (Ch.a) extract in a murine model of asthma is reported for the first time. Balb/C mice were sensitized using Ch.a. pollen allergenic extract plus CpG-ODNs intraperitoneally and were challenged with aerosolized allergen. Results measured included IL-10 and IFN-gamma cytokines as well as IgG subclasses. For this, splenocytes from mice treated with CpG/Ag or Ag alone, were cultured in the presence of antigen.

The results showed that CpG ODN administered at the time of Ch.a sensitization, effectively increased cytokines and IgG2a/IgG1 ratios compared with those in mice treated with antigen  or with PBS alone(P≤ 0.001). Our experiments revealed that Ch.a. sensitization decreased IgG2a/IgG1 compared with non-sensitized mice (P≤ 0.001), while CpG ODN/Ch.a reversed this ratio, indicating CpG potentials towards IgG2a subclass switching.

We conclude that Co- administration of Ch.a. allergen and CpG ODN prevents the development of TH2-mediated response probably through the IL-10 regulatory effects. Thus, these components could be used with the other allergens in order to induce the prevention of inflammatory conditions. We suggest further studies are necessary to identify the potential effects of CpG-ODNs administration in conjunction with other antigens prepared from the regional allergens in Iran. Taken together, we suppose that the results obtained in this study in animal models may be useful in human trials conducted by other investigators