Co-culture of human AT2 cells with fibroblasts reveals a MUC5B phenotype: insights from an organoid model.

Impaired interaction of fibroblasts with pneumocytes contributes to the progression of chronic lung disease such as idiopathic pulmonary fibrosis (IPF). Mucin 5B (MUC5B) is associated with IPF. Here we analyzed the interaction of primary fibroblasts and alveolar type 2 (AT2) pneumocytes in the organoid model. Single-cell analysis, histology, and qRT-PCR revealed that fibroblasts expressing high levels of fibrosis markers regulate STAT3 signaling in AT2 cells, which is accompanied by cystic organoid growth and MUC5B expression. Cystic growth and MUC5B expression were also caused by the cytokine IL-6. The PI3K-Akt signaling pathway was activated in fibroblasts. The drug dasatinib prevented the formation of MUC5B-expressing cystic organoids. MUC5B associated with AT2 cells in samples obtained from IPF patients. Our model shows that fibrotic primary fibroblasts induce impaired differentiation of AT2 cells via STAT3 signaling pathways, as observed in IPF patients. It can be used for mechanistic studies and drug development.