SAT425 Effects Of Endocrine-disrupting Polychlorinated Biphenyls On Adolescent Microglial Cytokine Expression And Responses To Secondary Inflammatory Challenge

Abstract

Abstract Disclosure: S.L. Kissinger: None. A.J. Fitzgibbon: None. R.A. Mejia: None. M.R. Bell: None. Polychlorinated biphenyls (PCBs) are a group of ubiquitous environmental endocrine-disrupting chemicals (EDCs), and exposure is associated with endocrine, neuronal, and immune dysfunction in various tissue types. Innate immune cells of the nervous system called microglia are critical in responding to infection and injury, and disruption of these functions is associated with neurodegenerative disease and mental health disorders. In addition, microglia are known to regulate developmental processes during neonatal and adolescent periods, in hormone-sensitive and age- and sex-differentiated ways. Work in our lab has shown that early life PCBs can affect microglia function in ways that depend on the age and sex of the individual rat in vivo. Ongoing work uses in vitro approaches to demonstrate direct effects on microglia. In primary culture, preliminary data suggest that acute PCB exposure causes neonatal microglia to become hyperresponsive to a secondary challenge; however, effects in adolescent microglia are unknown. To test the hypothesis that PCB exposure directly alters microglia activity in an age- and sex-specific manner, we determined the effects of PCBs on cytokine gene expression in acutely isolated microglia, with or without a secondary lipopolysaccharide (LPS) challenge. Adolescent Sprague-Dawley rats underwent transcardial saline perfusion, brains were removed and homogenized into a single cell suspension with collagenase and mechanical disruption, and debris was removed. Microglia, identified as CD11b+ cells, were collected by magnetic bead isolation and plated in enriched media for 24 hours prior to experimentation. Cells were exposed to one of three concentrations of PCB 153 (0.1 µM, 1 µM, 10 µM), DMSO vehicle, or DMEM/F12 media control for 18 hours, followed by a 4-hour LPS challenge (0.5 µg/mL) or PBS vehicle control. RNA was isolated and converted to cDNA for qPCR analysis of Tnf and Il1b gene expression, analyzed by two-way (exposure x challenge) ANOVAs within both male and female cells. Results indicate that 1.0 µM PCB 153 exposure caused an increase in expression of both cytokines, more so in females than males. Preliminary results (n = 3) indicate that the 10 µM dose may also blunt the later LPS response. These results confirm that microglia are directly sensitive to PCBs, however they illustrate that cells may show differential responses depending on the stage of development. Continued work will explore acute cell toxicity and confirm release of cytokines. Adolescent microglia dysfunction from PCB exposure may be a mechanism of adolescent-onset disorders, or increased risk of neurodegenerative conditions triggered by additional challenges later in life. Presentation: Saturday, June 17, 2023