PSAP and silicosis: We integrated data on silicosis fibrotic niches with macrophage differentiation data by intersecting the top 50 feature genes of fibrotic niches identified through ST-seq with the 60 feature genes indicative of fibrosis initiation in the trajectory of Spp1hiMacs, resulting in 11 key genes (Pla2g7, Spp1, Gpnmb, Cd68, Hmox1, Slpi, Ctsb, Ctsd, Tnfaip2, Psap, and Lgals3) (Fig. 3a).