TNF and asthma: Reduced responsiveness to β2-adrenergic agonists in airway smooth muscle also occur after persistent exposure to cytokines (IL-1β, tumor necrosis factor-α: TNF-α) [72], growth factors (Transforming Growth Factor-β1: TGF-β1, platelet-derived growth factor: PDGF) [73,74], phospholipids (S1P, lysophosphatidylcholine: Lyso-PC) [75,76], and mast cell tryptase [77], which are deeply involved in the pathogenesis of asthma and COPD (Figure 3).