TSLP and pulmonary fibrosis: Interleukin (IL)‐25/IL‐33/thymic stromal lymphopoietin (TSLP) derived from alveolar epithelial cells (AECs) can initiate an abnormal, profibrotic crosstalk to mesenchymal cells (including fibroblasts, dendritic cell [DCs], M2‐macrophage, and type 2 innate lymphoid cells [ILC2s]) and thereby leads to lung fibrosis.