Sex-Specific Metabolic, Immunologic, and Behavioral Effects of Perfluorooctane Sulfonic Acid (PFOS) in BTBR-mtB6 Mice

Perfluorooctane sulfonate (PFOS), a member of the per- and polyfluoroalkyl substance (PFAS) family, has been associated with adverse health effects, including potential links to autism spectrum disorder (ASD). This study investigates the impact of PFOS on metabolic, immunologic and behavioral profiles in BTBR-mtB6 mice, a mouse strain that models ASD, to provide insights into the role of PFOS in ASD development and related health concerns. Three-month-old male and female BTBR-mtB6 mice were divided into two groups (n = 6) and received daily administration of either 1 mg/kg PFOS or vehicle over a three-month period by gavage. Metabolic assessments included measurements of body weight and weekly blood glucose levels, glucose and insulin tolerance tests, organ weights, and body compositions (free fluid, fat and lean tissue). Immune profiling was conducted via flow cytometric analysis of splenic leukocytes, while behavioral evaluations included grooming, sniffing, and three-chamber social interaction tests. PFOS exposure disrupted glucose homeostasis, with both sexes exhibiting elevated blood glucose levels. Male mice showed impaired glucose tolerance, delayed glucose level recovery, and increased insulin resistance, while females displayed decreased insulin resistance. Additionally, PFOS exposure led to liver enlargement in both sexes. Behavioral assessments revealed heightened grooming in PFOS-treated males, commonly interpreted as stress- or ASD-related repetitive behaviors, whereas females exhibited reduced grooming, reflecting altered behavioral responses to exposure. Immune alterations were also sex specific. PFOS-treated males exhibited decreased granulocytes, increased macrophages, and enhanced surface expressions of B220 and CD40L. PFOS-treated females showed increased macrophages, B-cells, cytotoxic T-cells and CD25+ T-cell subsets, with enhanced surface expression of B220 and CD8, and reduced surface expression of Mac-3. In addition, PFOS exposure reduced spleen weight in females. Taken together, PFOS exposure induced significant physiological and behavioral changes in BTBR-mtB6 mice, with sex-specific differences observed. These results raise concern that PFASs may contribute to the development or exacerbation of metabolic, immune and neurodevelopmental disorders, highlighting the need for sex-specific human risk assessment in environmental toxicology.