Lysophosphatidylcholine-induced macrophage polarization imbalance and functional dysregulation in immune thrombocytopenia

Abstract Introduction Immune thrombocytopenia (ITP) is an acquired bleeding disorder characterized by reduced platelet counts and increased risk of hemorrhage. Immune dysregulation of macrophages plays a critical role in ITP pathogenesis. Lysophosphatidylcholine (LPC), a class of bioactive lipid molecules, exerts complex yet pivotal effects in inflammation and immune regulation. In this study, we investigated whether LPC modulates macrophage polarization and function in ITP patients via metabolic reprogramming. Furthermore, we evaluated the therapeutic efficacy of combined dexamethasone (DXM) and atorvastatin (AT) treatment, both in vitro and in an active ITP murine model. Methods Bone marrow (BM) samples were collected from 61 ITP patients and 46 healthy controls (HCs) at the Department of Hematology, Qilu Hospital of Shandong University, China. Flow cytometry was employed to analyze M1 and M2 macrophage subsets in BM. Untargeted metabolomics and transcriptome sequencing were performed on sorted BM macrophages, and key metabolites were validated using ELISA. In vitro experiments were performed to evaluate the effects of LPC (16:0/0:0) on IL-10 expression, macrophage phagocytosis, and T-cell differentiation, along with the regulatory roles of DEX, AT , and their combination. An active ITP murine model was used for in vivo validation. Results The proportion of CD68⁺CCR2⁺ M1 macrophages among CD68⁺ macrophages in BM was significantly increased in ITP patients compared to HCs. Moreover, M1 macrophages predominated over M2 macrophages in ITP patients, whereas M2 macrophages were the dominant subset in HCs. The levels of anti-inflammatory cytokine IL-10 were significantly reduced in both BM supernatants and plasma form ITP patients compared to HCs. Untargeted metabolomic profiling was performed on BM macrophages isolated from ITP patients and HCs. KEGG pathway enrichment analysis showed that the differential metabolites were significantly enriched in the glycerophospholipid metabolism pathway, particularly LPC metabolism. Transcriptomic sequencing was also conducted, and the integrated analysis results of the two omics confirmed enrichment of the glycerophospholipid metabolic pathway, with LPC (16:0/0:0) identified as the most significantly altered metabolite. LPC (16:0/0:0) concentrations were elevated in both BM supernatants and plasma from ITP patients. Furthermore, it was found that LPC (16:0/0:0) levels were notably higher in patients with platelet counts <30×10⁹/L compared to those with counts ≥30×10⁹/L. Our results demonstrated that LPC (16:0/0:0)-treated macrophages exhibited significantly reduced IL-10 expression levels compared to untreated controls. Both DXM and AT restored IL-10 secretion, with the combination exerting a more pronounced effect. Platelet phagocytosis assays showed that LPC (16:0/0:0) enhanced the phagocytosis of platelets by M1 macrophages. Further study revealed that DXM or AT alone inhibited LPC-induced phagocytosis, although their combination did not confer additional benefit. We also found that LPC (16:0/0:0) modulated M2 macrophage-mediated T cell proliferation. T cell subsets were analyzed following co-culture with LPC-treated M2 macrophages. We found that LPC (16:0/0:0) treatment significantly reduced the proportion of Treg cells, alongside enhanced differentiation of T cells into Th1, Th2, and Th22 subsets. Further treatment analysis revealed that DXM predominantly suppressed Th1 and Th2 differentiation, whereas AT primarily restored Treg cell proliferation. An active ITP murine model was established, and mice were treated with LPC (16:0/0:0), DXM, AT, or their combination. LPC (16:0/0:0) treatment significantly reduced platelet counts, whereas co-treatment with DXM and/or AT promoted platelet recovery. Notably, combined treatment with DXM and AT produced more effective therapeutic effect. Additionally, LPC (16:0/0:0) induced the polarization of BM macrophages toward M1 phenotype, while DXM reversed this shift, promoting M2 polarization. Conclusions Our study identifies LPC (16:0/0:0)-mediated metabolism-immunity crosstalk of macrophages as a central pathogenic mechanism in ITP. We propose that the DXM–AT combination strategy may restore immune homeostasis by concurrently regulating metabolic and immune pathways.