PPAR Subtypes Determine Distinct Modes of Action of Phthalate Esters (paes) and Per- and Polyfluoroalkyl Substances (PFAS) in Disrupting Human Macrophage Alternative Activation

Phthalate esters (PAEs) and per- and polyfluoroalkyl substances (PFAS) are ubiquitous pollutants tied to metabolic and immune disorders. The peroxisome proliferator-activated receptor (PPAR) pathway has been indicated to mediate their toxic effects, but the specific functions of PPAR subtypes and their mediating roles remain unclear. In this study, we generated PPARα-, δ-, and γ-specific knockout THP-1 cell lines by using CRISPR/Cas9 system and then differentiated them into interleukin-4 (IL-4) and interleukin-13 (IL-13)-polarized macrophages (alternative activation). During the induction process, the cells were exposed to 0, 6.25, 12.5, 25, 50, 100 μM of five PAE metabolites: Mono-(2-ethylhexyl) phthalate (MEHP), Monocyclohexyl phthalate (MCHP), Monoisonyl phthalate (MINP), Monoisobutyl phthalate (MIBP), and Monobenzyl phthalate (MBzP); and five PFAS: Perfluoroundecanoic acid (PFUnDA), Perfluorodecanoic acid (PFDA), Perfluorooctanoic acid (PFOA), Potassium perfluorooctanesulfonate (PFOS-K), and Potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (F53B) for 48 h. The results showed that PPARδ deletion abolished CD209 expression, confirming its essential role, whereas PPARα deletion reduced and PPARγ deletion enhanced CD209, indicating PPARα promotes and PPARγ restrains alternative activation. Compounds displayed subtype-selective actions: MEHP activated PPARα/γ; MBzP/MCHP inhibited PPARδ yet activated PPARγ; MINP activated PPARγ only. Among PFAS, PFOS-K activated PPARδ/γ; F53B inhibited PPARα; PFOA activated PPARγ; PFDA inhibited PPARα/δ. Transcriptomics revealed compound-specific enrichments-cholesterol (MEHP), fatty-acid (MCHP), glycolysis (PFOS-K), TCA cycle (PFOA)-despite common PPAR pathway engagement. In conclusion, PAEs and PFAS disrupt macrophage plasticity through distinct PPAR-subtype signatures, providing molecular landmarks for future hazard assessment of environmental pollutants.