Abstract Rationale Chronic thromboembolic pulmonary hypertension (CTEPH) progression is driven by pathological transitions from proximal thrombus organisation to distal vascular remodelling, yet the spatial distribution and regulatory mechanisms of macrophages across these anatomical compartments remain poorly defined. Methods Through integrated analysis of 10x Genomics spatial transcriptomics and single-cell RNA sequencing performed on proximal (elastic arteries), mid (transitional), and distal (muscular arterioles) lesions from pulmonary endarterectomy specimens, we mapped a spatial cellular ecosystem revealing a striking pathological gradient along the proximo-distal axis. Results While proximal and mid lesions featured an inflammatory microenvironment with abundant macrophage infiltration (46.04% and 46.67%, respectively), distal lesions were dominated by mural cells (35.10%) and fibroblasts (24.50%), indicative of advanced microvasculopathy and fibrosis. A novel signaling axis comprising Fibronectin 1 (FN1), CD44, and Glycoprotein Non-Metastatic Melanoma Protein B (GPNMB) was identified as central to disease progression. This axis consisted of two key components: 1) stromal FN1 promoted macrophage recruitment/retention via CD44, and 2) GPNMB (highly expressed in APOC1+ macrophages) interacted with CD44 to drive lipid metabolic reprogramming and accumulation. Consequently, the GPNMB-CD44 interaction linked proximal inflammation to a pro-fibrotic state, ultimately promoting distal vascular remodeling. Conclusions Our study unveils the spatial heterogeneity of macrophages in CTEPH and delineates a pivotal role for the FN1-CD44-GPNMB axis in driving disease progression, providing a new conceptual framework and potential therapeutic targets for intervention. This abstract is funded by: This study was supported by Natural Science Foundation of Fujian Province (2023J01092), National Natural Science Foundation of China (No.82470043), Major Scientific Research Program for Young and Middle-aged Health Professionals of Fujian Province (No.2023ZQNZD006).
Yan et al. (2026) studied this question.