TSLP expression is significantly increased in asthma patients compared to healthy individuals in the inner and outer epithelial layers of airway biopsies [51, 52, 53, 54, 55, 56, 57, 58] as well as in serum samples [59, 60], sputum [61], exhaled breath condensate [62], and bronchoalveolar lavage fluid [57, 63]. Here, TSLP is linked to asthma.