Developmental immunotoxicity of PFAS

PROJECT SUMMARY The goal of this project is to determine how developmental exposure to a mixture of per- and polyfluoroalkyl substances (PFAS) disrupts humoral immune defenses against respiratory virus infection. There is evidence that PFAS affect the immune system, but uncertainty about underlying cellular mechanisms. This project builds on preliminary evidence that developmental exposure to a mixture of PFOA, PFOS, PFNA and PFHxS perturbs the response to influenza A virus (IAV) infection, including significantly fewer T follicular helper (Tfh) cells. Tfh cells are critical drivers of humoral immunity, controlling antibody production, isotype switching, affinity maturation, and immunological memory. Additional pilot data show that fewer Tfh cells in PFAS-exposed offspring correlate with reduced IAV-specific antibody levels. Our results are exciting because, although changes in antibody levels are often associated with PFAS, how developmental PFAS exposure alters key cellular events that underpin humoral immunity is not known. The proposed research will test the central hypothesis that developmental exposure disrupts Tfh cells, which contributes to alterations in B cell responses and antibody production. During IAV infection, we can track responses of Tfh cells, germinal center B cells, and plasma cells over time using multidimensional flow cytometry, and the kinetics of primary and anamnestic responses to IAV are well established. The first aim will define the contribution of alterations in T cells and B cells to the effects of developmental PFAS exposure on Tfh cells and anti-viral humoral immunity, including memory responses. The second aim will delineate key parameters of developmental immunotoxicity of PFAS, including the critical window during development that is most sensitive to PFAS exposure, and the dose-dependent and sex-dependent nature of immune function changes caused by developmental PFAS exposure. This will include using ultra-high- performance liquid chromatography coupled with high-resolution mass spectrometry to measure PFAS in the offspring, allowing internal dose and immune function to be directly related. The third aim will identify the mode of action through which PFAS affect immune function using conditional knockout mice and pharmacological agents. This aim will resolve whether developmental immunotoxicity is mediated via peroxisome proliferator activated receptors (PPAR). This research project will significantly advance knowledge of how developmental exposure to a representative real-world PFAS mixture modulates the immune system. Major impacts include that it will pinpoint cellular targets that contribute to clinical consequences, provide a framework to understand sex differences in PFAS developmental immunotoxicity, produce new information to guide research in human population studies, and refine our ability to identify at risk populations.