Apocynin and Nox2 regulate NF-κB by modifying thioredoxin-1 redox-state

Area of Science:

• Immunology
• Cellular Biology
• Biochemistry

Background:

• Nox2 enzyme is crucial for leukocyte antimicrobial functions.
• The role of Nox2 in cellular redox homeostasis and intracellular signaling is not fully understood.
• Leukocyte dysfunction in conditions like CGD and sepsis contributes to hyperinflammation.

Purpose of the Study:

• To elucidate the role of Nox2 in regulating cellular redox homeostasis and intracellular signaling pathways.
• To investigate the impact of Nox2 activity on thioredoxin-1 (TRX-1) localization and nuclear factor-kappa B (NF-κB) signaling.
• To evaluate the therapeutic potential of targeting the Nox2-TRX-1-NF-κB pathway in inflammatory diseases.

Main Methods:

• Investigated Nox2 activation effects on TRX-1/p40phox interaction and nuclear exclusion.
• Utilized genetic deficiency and pharmacological inhibition of Nox2 (apocynin) to study cellular redox state.
• Examined the impact of thioredoxin reductase-1 (TrxR-1) inhibition on TRX-1 oxidation and NF-κB activation in response to lipopolysaccharide (LPS).
• Analyzed inflammatory mediator production (TNF-α) in monocytes and neutrophils from CGD patients.
• Assessed the efficacy of TrxR-1 inhibitors (LaCl3, auranofin) in a mouse model of sepsis (CLP).

Main Results:

• Nox2 activation promotes TRX-1 exclusion from the nucleus.
• Genetic deficiency or inhibition of Nox2 leads to reductive stress and nuclear TRX-1 accumulation, enhancing inflammatory gene transcription via NF-κB.
• Inhibition of TrxR-1 oxidizes TRX-1, preventing NF-κB overactivation and reducing TNF-α production in CGD patient cells.
• TrxR-1 inhibitors improved survival rates in a mouse sepsis model.

Conclusions:

• A novel Nox2-mediated signaling pathway involving TRX-1 and NF-κB contributes to hyperinflammation in CGD and sepsis.
• TrxR-1 inhibitors represent a potential therapeutic strategy for managing sepsis, especially in CGD patients.
• Targeting TrxR-1 offers a promising approach to control inflammatory responses in specific disease contexts.