Browsing by Author "Taetzsch, Thomas"

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    Chlorpyrifos Oxon Primes Microglia: Enhanced LPS-Induced TNFα Production
    (Office of the Vice Chancellor for Research, 2016-04-08) Kouame, Elaine; Brookins, Savannah; Jayaraj, Richard L.; Taetzsch, Thomas; Mumaw, Christy; Block, Michelle L.
    Microglia, the resident innate immune cells of the brain, respond to various environmental stimuli, including factors from surrounding tissue and from systemic inputs. These stimuli impact microglial function in both health and disease. Increasing evidence implicates microglia and neuroinflammation in Gulf War illness (GWI) pathology. Gulf War illness is an untreatable chronic multi symptomatic disorder that affects about 30% of Gulf War veterans. It has been proposed that “multiple hits” from exposure to various environmental neurotoxicants such as Chlorpyrifos (CPF), an organophosphate pesticide, combined with low inflammation may initiate exaggerated and persistent central nervous system (CNS) pathology to drive GWI. CPF oxon, an active metabolite of CPF, is associated with deleterious CNS effects, but the role of microglia behind this phenomenon is not fully understood.To investigate the effects of CPF oxon on microglia, we assessed microglial ROS, pro-inflammatory cytokine factors, and NF-κB p50 DNA binding activity in the presence of CPF oxon. HAPI microglia cells were treated with CPF oxon (1μM-1nM), which resulted in a dose dependent increase in H2O2 production at 3 hours and elevated superoxide at 30 minutes. CPF oxon failed to initiate TNFα and nitric oxide from microglia cultures. However, CPF oxon significantly decreased NF-κB p50 binding to DNA in microglia, a key redox signaling mechanism linked to microglial priming. Consistent with this premise, pre-treatment with CPF oxon (0.5μM) amplified LPSinduced TNFα production in microglia and neuron-glia cultures. Moreover, when CPF oxon and LPS challenged cells were pre-treated with DPI, a NOX2 inhibitor, we found a significant reduction in TNFα response when compared to non-treated cells, supporting that NOX2 may regulate CPF oxon priming in microglia. These data suggest that CPF oxon may induce ROS production in microglia to reprogram these cells to become more sensitive to pro-inflammatory stimuli (priming).
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    Loss of NF-κB p50 function synergistically augments microglial priming in the middle-aged brain
    (BMC, 2019-03-12) Taetzsch, Thomas; Benusa, Savannah; Levesque, Shannon; Mumaw, Christen L.; Block, Michelle L.; Anatomy and Cell Biology, School of Medicine
    BACKGROUND: While NF-κB p50 function is impaired in central nervous system disease, aging in non-CNS tissues, and response to reactive oxygen species, the role of NF-κB p50 in aging-associated microglial pro-inflammatory priming is poorly understood. METHODS: Male NF-κB p50+/+ and NF-κB p50-/- mice at three different ages (1.5-3.0 month old, 8.0-11.0 month old, and 16.0-18.0 month old) were treated with LPS (5 mg/kg, IP) to trigger peripheral inflammation, where circulating cytokines, neuroinflammation, microglia morphology, and NF-κB p50/p65 function in brain tissue were determined 3 h later. RESULTS: Peripheral LPS injection in 9-month-old C57BL/6 mice resulted in lower NF-κB p50 DNA binding of nuclear extracts from the whole brain, when compared to 3-week-old C57BL/6 mice, revealing differences in LPS-induced NF-κB p50 activity in the brain across the mouse lifespan. To examine the consequences of loss NF-κB p50 function with aging, NF-κB p50+/+ and NF-κB p50-/- mice of three different age groups (1.5-3.0 month old, 8.0-11.0 month old, and 16.0-18.0 month old) were injected with LPS (5 mg/kg, IP). NF-κB p50-/- mice showed markedly elevated circulating, midbrain, and microglial TNFα when compared to NF-κB p50+/+ mice at all ages. Notably, the 16.0-18.0-month-old (middle aged) NF-κB p50-/- mice exhibited synergistically augmented LPS-induced serum and midbrain TNFα when compared to the younger (1.5-3.0 month old, young adult) NF-κB p50-/- mice. The 16.0-18.0-month-old LPS-treated NF-κB p50-/- mice also had the highest midbrain IL-1β expression, largest number of microglia with changes in morphology, and greatest elevation of pro-inflammatory factors in isolated adult microglia. Interestingly, aging NF-κB p50-/- mice exhibited decreased brain NF-κB p65 expression and activity. CONCLUSIONS: These findings support that loss of NF-κB p50 function and aging in middle-aged mice may interact to excessively augment peripheral/microglial pro-inflammatory responses and point to a novel neuroinflammation signaling mechanism independent the NF-κB p50/p65 transcription factor in this process.