Interstitial Macrophage Phenotypes in Schistosoma-Induced Pulmonary Hypertension

Schistosomiasis, a prevalent cause of pulmonary hypertension (PH) globally, triggers type 2 inflammation, with interstitial macrophages (IMs) derived from monocytes playing a crucial role. These IMs produce thrombospondin-1 (TSP-1), activating TGF-β and driving PH pathology. Two distinct IM subpopulations were identified: resident FOLR2+ IMs expressing monocyte recruitment factors, and recruited CCR2+ IMs expressing TSP-1. Upon exposure to Schistosoma, the CCR2+ subpopulation expanded. Flow cytometry and single-cell RNA sequencing confirmed these findings, revealing crosstalk between IM subpopulations. The resident FOLR2+ IMs increased expression of monocyte recruitment ligands, while the recruited CCR2+ IMs expressed elevated TSP-1, activating TGF-β and contributing to PH. This study provides insights into the complex interplay of IM subpopulations in Schistosoma-induced PH, shedding light on potential therapeutic targets for this global health concern. Cx3cr1+/GFP reporter mice were intraperitoneally sensitized and then intravenously challenged with S. mansoni eggs. Lung interstitial macrophages (IMs) were sorted from unexposed and at day 1, 3 and 7 following Schistosoma IV challenge by flow cytometry. At each time point, IMs were sorted from of a pair of age- and sex-matched mice (1 male and 1 female) and were combined for subsequent analyses. Single cells were captured using a Chromium Box (10X Genomics, Pleasanton, CA). Libraries were sequenced using the Illumina NovaSEQ 6000 sequencer (Illumina, Inc., San Diego, CA). Subsequently, RNA sequence reads were aligned to the Mus musculus GRCm39 reference genome using Cell Ranger v6 (10x Genomics). Downstream analysis was performed using the Seurat package in R.