SPP1 and idiopathic pulmonary fibrosis: Spatial transcriptomics has revealed IPF-tissue specific cellular niches including an ‘airway macrophage niche’ within the airway lumen consisting of SPP1+ macrophage subsets colocalised with epithelial cell populations including aberrant basaloid cells, preterminal bronchial secretory cells and distal SFTPB+-ciliated cells.100