Figure 2 - The roles of IL-4 and IL-13 in asthma pathogenesis
Two main drivers of type 2 asthma are IL-4 and IL-13. These cytokines indirectly and directly lead to airway remodeling by inducing many cell types and factors, such as DC, epithelial cells, fibroblasts, airway smooth muscle. IL-4 has mainly central effects related to immunologic effects in the lymph nodes, while IL-13 mainly acts on tissue cells and mucus production. Environment factors can trigger the inflammation by damaging the epithelial barrier. Cycles of inflammation cause repetitive injury of and repair of the airway wall. IL-4 and IL-13 contribute to alterations in the epithelium (epithelial shedding, subepithelial fibrosis). Activated smooth muscle cells contribute airway hyperresponsiveness, basement membrane thickening and collagen deposition. Repetitive stimulation of airway epithelium by IL-13 causes goblet cell hyperplasia and mucus hypersecretion in airway epithelial cells. Airway remodeling supports the production of pro-inflammatory mediators.