TSLP and asthma: After contact for example with HDM extracts, representing a major source of asthma associated allergens, TLR4 dependent activation of NFκB and protease induced injuries in airway epithelial cells lead to secretion of chemokines and cytokines like thymic stromal lymphopoietin (TSLP), GM-CSF, IL-25, and IL-33 (211–215).