CpG DNA for Treatment of Allergic Diseases

Choi, Sung Min

Abstract

Atopy is a highly prevalent and serious health problem. The prevalence and severity of asthma and allergic diseases have increased over recent decades, particularly in industrialized nations. Early life infections may protect against the development of atopy and allergic diseases like asthma. The inverse relationship between the incidence of atopy and childhood infections has led to the 'hygiene hypothesis', which suggests that diminished exposure to childhood infections in modern society has led to decreased Th1-type responses. Th1 and Th2 responses are counter-regulatory. Reduced Th1 may lead to enhanced Th2-type inflammation, which is important in promoting asthma and allergic disease via up-regulation of IL-4, IL-5, and IL-13. It is now widely accepted that altered regulation of Th2 responses(and possibly the balance between Th1 and Th2 responses) is an important factor in the development of atopy. CpG DNA represent a novel class of drugs with substantial immunomodulatory properties. CpG DNA contain unmethylated motifs centered on the CpG dinucleotides, like bacterial DNA. These CpG DNA promote Th1 and regulatory type immune responses and suppress Th2 responses. In murine studies, CpG DNA are effective in prevention and treatment of asthma and allergic diseases. CpG DNA are just beginning to be tested in human asthma. While its precise mechanisms continue to be fully studied, CpG DNA offers considerable promise as a novel treatment for atopic inflammation. It may prove to be an important disease modifying therapy, or even curative therapeutic agent for asthma and allergic diseases.