Response-associated changes in DHA and in vitro involvement of PPARγ-RXRα signaling in macrophage immunometabolic modulation following HIFU ablation

High-intensity focused ultrasound (HIFU) induces local tissue ablation and subsequent immune and metabolic changes, but the relationship between these changes and macrophage function remains unclear. We prospectively followed 57 patients with uterine fibroids undergoing HIFU and analyzed longitudinal plasma, urine, and hair metabolomes at four time points. Candidate metabolites were further examined in THP-1-derived macrophages using functional assays, cellular metabolomics, RNA sequencing, pathway inhibition, and patient-serum treatment. Single-cell transcriptomic data were also analyzed to assess macrophage-related cellular interactions in fibroid tissue. Among the metabolites detected, docosahexaenoic acid (DHA) showed response-associated changes across all three biospecimens. In in vitro assays, DHA treatment was associated with increased migration, phagocytosis, ACP activity, IL-10 secretion, and M2-associated gene expression, while reducing TNF-α, IL-6, iNOS, and intracellular lipid accumulation. DHA also altered fatty-acid and central-carbon metabolism and was associated with changes in PPAR signaling. Pharmacological inhibition of PPARγ or RXRα attenuated the DHA-induced functional and metabolic responses, implicating the involvement of the PPARγ-RXRα pathway. Serum from patients with sustained high HIFU response similarly enhanced macrophage phagocytosis, an effect that was reduced by pathway inhibition, though this cannot be attributed exclusively to DHA. Single-cell analysis further contextualized macrophage interactions with stromal and immune cell populations in fibroid tissue, though treatment- or DHA-induced dynamics cannot be directly inferred from this dataset. Overall, these findings suggest that response-associated changes in DHA may be linked to macrophage functional remodeling after HIFU through the involvement of PPARγ–RXRα signaling, providing a basis for further investigation of post-ablation immunometabolic responses.