Though mere overexpression of IL-13 in mice lead to increased fibrosis [24], and a clinical study using anti-IL-13 therapy is currently underway (NCT01872689), it is important to note that so far, therapies attenuating either Th1 [29] or Th2 inflammation [30,31] do not generally lead to better overall outcomes for IPF patients [32]. Here, IL13 is linked to idiopathic pulmonary fibrosis.