TLR7 and chronic asthma: TLR7 agonists have been shown to upregulate Th1 responses and downregulate Th2 responses to allergens in murine models of allergic or chronic asthma through a variety of complex mechanisms, such as activating nuclear factor NF-κB pathway transcription factors to increase production of cytokines, including IL-12, chemokines and Type I IFNs such as IFNα; some also appear to depend on the type II IFNγ [15–18].