Expression levels of neuroimmune biomarkers in hypothalamus of allergic mice after phthalate exposure.

Previously, we demonstrated that maternal exposure to phthalates enhances atopic dermatitis in male mouse offspring. However, whether phthalate exposure affects neuroimmune biomarkers in allergic mice has not yet been studied. Di-(2-ethylhexyl) phthalate (DEHP) and di-isononyl phthalate (DINP) are environmental chemicals that are commonly used as plasticizers. This study was designed to investigate the expression levels of neuroimmune biomarkers in the hypothalamus of a murine model of allergic asthma after phthalate exposure throughout juvenility until adulthood. Six-week-old C3H/HeJ Jcl male mice were treated with DEHP or DINP (0, 0.02, 0.4 or 8 nmol per body per week) and ovalbumin (OVA; 1 µg per body per 2 weeks) for 7 weeks intratracheally. On the day after the completion of the phthalate and OVA treatment, the hypothalamus from each mouse was collected, and the mRNA expression levels of neuroimmune biomarkers were examined using a real-time RT-PCR analysis. The mRNA expression levels of the proinflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF)-α, the chemokine CCL3, the transcription factor nuclear factor (NF)-κB, the oxidative stress marker heme-oxygenase (HO)1, a nerve growth factor, and the microglia marker Iba1 were remarkably up-regulated in the hypothalami of mice treated with 8 nmol of DEHP in the presence of the allergen. However, no significant changes were observed, except for reductions in the TNF-α and CCL2 mRNA levels, in mice exposed to DINP combined with the allergen. This study is the first report to show that high-dose DEHP exposure throughout juvenility until adulthood may induce neuroinflammation by modulating neuroimmune biomarkers in the hypothalami of allergic mice.