Environmentally relevant level of aflatoxin B₁ elicits toxic pro-inflammatory response in murine CNS-derived cells

Aflatoxin B₁ (AFB₁) is a well-known member of aflatoxins (AFs) that is considered among highly stable toxic contaminants of food, worldwide. The impact of AFB₁ on neural cells and systems has poorly been understood. To assess the cellular effects of AFB₁ on brain, we used murine pure primary astrocytes, sub ventricular zone-derived neural precursor cells (NPCs) and microglia cell line (BV2). Cells were exposed separately to environmentally relevant level (20ng/ml) of AFB₁ for 1, 2, 3, 6, 12, 24 and 48h in culture. At each time points, total free radicals production measured by luminol-enhanced cellular chemiluminescence (CL) assay; cytokines production of IL-1β, IL-6, TNF-α and IL-10 were analyzed using Bioplex ELISA and a set of genes involved in the immediate response to danger such as TLR2, TLR4 and iNOS etc. were evaluated by multiplex qPCR. Upon AFB₁ exposure production, of the total free radicals significantly increased only in microglial cells after 24h and slightly elevated in the other examined cells. AFB₁ also induced secretion of pro-inflammatory cytokines (i.e. TNF-α and IL-6) on both microglial cells (more TNF-α) and astrocytes (more IL-6). mRNA expression of TLR2, TLR4, MyD88 and NF-κB were up-regulated with different timing and levels among cells. Immunotoxicologically, microglial cells, and astrocytes, but not NPCs, are capable of sensing a low level of AFB₁. Thus, the pro-inflammatory effects of an environmentally relevant dose of AFB₁ on CNS-derived cells in vitro could potentially explain the immune dysregulation in neurodegenerative disorders.