Effects of Ether Perfluoro Carboxyl Acids (PFECAs) on Innate Immunity in Earthworms (Eisenia fetida)

Per- and polyfluoroalkyl substances (PFAS) persist in soils, yet their effects on invertebrate immunity remain poorly understood. We compared a legacy congener, perfluorooctanoic acid (PFOA), with three short-chain ether acids GenX (C6), MOBA (C5), and MOPrA (C4) using a 72 h OECD-207 filter-paper assay in the earthworm Eisenia fetida. Endpoints spanned cellular and humoral defenses: amoebocyte morphometry, oxidative burst (ROS production), phenol oxidase (PO) activity, and the transcription of the lectin CCF-1 and the pore-forming protein lysenin. MOBA and MOPrA caused enlargement of amoebocytes, whereas PFOA and GenX had no morphometric impact. Oxidative burst fell significantly for all congeners. PO inhibition followed the same potency order (MOPrA > GenX > MOBA ≫ PFOA), with near-complete loss at 229 µM MOPrA. Gene expression assays for CCF-1 and lysenin showed shifts in relative fold change for each PFAS congener. The combined biomarker panel—amoebocyte size, ROS, CAT, PO, CCF-1, and lysenin—offers a concise framework for assessing terrestrial PFAS risk and guiding remediation monitoring.