Do aflatoxin B1 and trichothecene mycotoxins promote oxidative stress and increase phase II detoxification burden?

Exposure to aflatoxin B1 (AFB1) and trichothecene mycotoxins like nivalenol (NIV) and verrucarin initiates a cascade of cellular injury characterized by profound oxidative stress, inflammatory signaling, and metabolic strain.

Mechanisms of cellular injury and inflammation

• Oxidative and Ribotoxic Stress: These toxins generate significant intracellular and mitochondrial reactive oxygen species (ROS), causing lipid peroxidation, membrane damage, and ribotoxic stress.
• Pro-inflammatory Cascade: ROS accumulation activates key mitogen-activated protein kinases (including p38, ERK1/2, and JNK) and triggers the nuclear translocation of NF-kB. This cascade drives the expression of inflammatory mediators, including TNF-alpha, IL-6, IL-8, IFN-gamma, COX-2, and iNOS, leading to systemic immune dysregulation.

Phase II detoxification depletion

• Metabolic Bottlenecks: AFB1 bioactivation yields the highly reactive AFB1-8,9-epoxide (AFBO) intermediate, which requires intensive glutathione S-transferase (GST)-catalyzed conjugation, rapidly depleting cellular glutathione (GSH) reserves.
• Enzymatic Saturation: Trichothecenes like NIV and verrucarin further exhaust cellular defenses, relying on UDP-glucuronosyltransferases (UGTs) for glucuronidation and deepoxidation pathways.
• Nrf2 Pathway Suppression: Crucially, these mycotoxins actively suppress Nrf2, the master transcription factor regulating GSTs, UGTs, and glutamate-cysteine ligase. This prevents the cell from synthesizing the very enzymes and cofactors needed for toxin clearance.

Bottom line

• Aflatoxin B1 and trichothecenes synergistically promote severe oxidative stress and immune dysregulation while simultaneously disabling the cell’s detoxification machinery via Nrf2 suppression and glutathione depletion, creating a high-burden metabolic bottleneck.