MARCO and idiopathic pulmonary fibrosis: All three ligand-receptor observations could be validated in the spatial data, with SCGB3A2 and SPP1 mostly expressed in the airway macrophage niche in IPF, while MARCO and the integrins ITGAV and ITGB6, as well as the WNT receptors FZD6 and LRP6, were up-regulated in IPF and expressed in the airway macrophage and airway niche, respectively (fig.