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

Abstract

The reactive-oxygen-species-(ROS)-generating-enzyme Nox2 is essential for leukocyte anti-microbial activity. However its role in cellular redox homeostasis and, consequently, in modulating intracellular signaling pathways remains unclear. Herein, we show Nox2 activation favors thioredoxin-1 (TRX-1)/p40phox interaction, which leads to exclusion of TRX-1 from the nucleus. In contrast, the genetic deficiency of Nox2 or its pharmacological inhibition with apocynin (APO) results in reductive stress after lipopolysaccharide-(LPS)-cell stimulation, which causes nuclear accumulation of TRX-1 and enhanced transcription of inflammatory mediators through nuclear-factor-(NF)-κB. The NF-κB overactivation is prevented by TRX-1 oxidation using inhibitors of thioredoxin reductase-1 (TrxR-1). The Nox2/TRX-1/NF-κB intracellular signaling pathway is involved in the pathophysiology of chronic granulomatous disease (CGD) and sepsis. In fact, TrxR-1 inhibition prevents nuclear accumulation of TRX-1 and LPS-stimulated hyperproduction of tumor-necrosis-factor-(TNF)-α by monocytes and neutrophils purified from blood of CGD patients, who have deficient Nox2 activity. TrxR-1 inhibitors, either lanthanum chloride (LaCl3) or auranofin (AUR), also increase survival rates of mice undergoing cecal-ligation-and-puncture-(CLP). Therefore, our results identify a hitherto unrecognized Nox2-mediated intracellular signaling pathway that contributes to hyperinflammation in CGD and in septic patients. Additionally, we suggest that TrxR-1 inhibitors could be potential drugs to treat patients with sepsis, particularly in those with CGD.

Influence of apocynin on cardiac remodeling in rats with streptozotocin-induced diabetes mellitus

“…Apocynin has been widely evaluated in experimental research as an antioxidant agent [ 17 – 19 ]. In literature several apocynin dosages have been used, ranging from 4 mg/kg/day [ 49 ] to 100 mg/kg/day [ 50 ].…”

“…Apocynin, a drug isolated from the medicinal herb Picrorhiza kurroa [ 16 ], is considered an antioxidant agent which inhibits NADPH oxidase activity and improves ROS scavenging [ 17 – 19 ]. We have previously observed that apocynin reduces myocardial oxidative stress without changing NADPH oxidase activity in diabetic hypertensive rats [ 20 ].…”

Modulation of signaling mechanisms in the heart by thioredoxin 1

“…In macrophages, upon stimulation with lipopolysaccharides, p40 phox interacts with oxidized Trx1, preventing its reduction and its ability to bind with NF-κB. On the other hand, inhibition of Nox2 by apocyanin promoted reduction and nuclear translocation of Trx1, thus enhancing its ability to bind to NF-κB and promoting transcription of several inflammatory mediators during sepsis [21]. Cytoplasmic binding of Trx1 to IκB prevents degradation of IκB and inhibits nuclear translocation of NF-κB in HSC-1 cells, thus decreasing its transcriptional activity [22].…”

Papel das Neutrophil Extracellular Traps no controle da infecção por Chikungunya

“…Para poder relacionar essa produção de espécies reativas de oxigênio com a liberação de NETs, utilizamos Apocinina, um inibidor farmacológico da enzima NADPH oxidase. Pré-tratamos as células com Apocinina na concentração de 300uM, por trinta minutos, condição em que já é descrita por inibir a produção de espécies reativas de oxigênio (Trevelin et al, 2016) e avaliamos a produção de NETs. Observamos que a inibição farmacológico da produção de espécies reativas de oxigênio prejudicou a geração de NETs induzida por Chikungunya (Fig.…”