Asthma is a chronic inflammatory airway disease characterized by episodes of reversible
airway narrowing, bronchial hyperresponsiveness and chronic pulmonary inflammation. The prevalence
of asthma has been increasing since the 1980s with more than 150 million people affected worldwide.
Developed and westernized countries have higher asthma prevalence. To date, asthma is the most
common chronic disease in children. More than 50% of asthma cases are the atopic/allergic form
triggered by environmental allergens. In the last decade, much attention has been focused on the role of
toll-like receptors (TLRs) in the pathogenesis of allergic asthma where it has been suggested that TLRs
form the link between the innate and the adaptive immune responses. Toll-like receptors exhibit an
important role in the activation of cells of the innate immune system, such as monocytes, macrophages,
dendritic cells, mast cells and neutrophils. This chapter will discuss the current knowledge on the
different TLRs and their possible roles in allergic asthma.
Keywords: Asthma, allergic lung, CpG-ODN therapy, probiotics.
