LGALS3BP promotes M1 polarization of macrophages and interacts with LGALS3, damaging endothelial function and exacerbating pulmonary arterial hypertension in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease that can affect multiple systems. Pulmonary arterial hypertension (PAH) is a rare but serious complication of SLE. However, the roles and underlying mechanisms of macrophages and endothelial cells in the pathogenesis of SLE-PAH remain largely unknown. In this work, five bulk RNA-sequencing datasets (GSE37356, GSE5099, GSE243193, GSE262084, GSE168905) and one single-cell RNA-sequencing dataset GSE179633 were analyzed, to screen the key differentially expressed genes (DEGs) in SLE-PAH. Subsequently, macrophages were treated with lipopolysaccharide and IFN-γ to induce M1 polarization of macrophages. The in vitro model of PAH was constructed by hypoxic treatment of human pulmonary artery endothelial cells (HPAECs), and a co-culture system of macrophages and pulmonary vascular endothelial cells was constructed. After Galectin 3 binding protein (LGALS3BP) was overexpressed or knocked down in macrophages, western blot was used to detect the expressions of M1 polarization markers in macrophages, as well as proteins related to endothelial-to-mesenchymal transition (EndMT) in endothelial cells. The proliferation of HPAECs was detected by the CCK-8 assay, and Apoptosis was detected by flow cytometry, and cell migration was detected by Transwell assay. LGALS3BP was identified to be a crucial modulator in SLE-PAH by bioinformatics, which could probably modulate the phenotypes of macrophages, and the interactions between macrophages and endothelial cells. Overexpression of LGALS3BP induced M1 polarization of macrophages, while knockdown of LGALS3BP had the opposite effect. Knockdown of LGALS3BP in macrophages reversed the effects of M1 polarization of macrophages on the proliferation, Apoptosis, migration and EndMT of HPAECs. The LGALS3BP secreted by M1 macrophages could bind to the ligand LGALS3 on HPAECs and promote its expression. Overexpression of LGALS3 in HPAECs could reverse the effects of LGALS3BP knockdown in macrophages on the phenotypes of HPAECs. In conclusion, up-regulation of LGALS3BP in macrophages contributes to M1 polarization, and promotes the proliferation, migration and EndMT of pulmonary vascular endothelial cells, and inhibit Apoptosis, which participates in the pathogenesis of SLE-PAH.