Four-octyl itaconate activates Nrf2 cascade to protect osteoblasts from hydrogen peroxide-induced oxidative injury

Abstract

Four-octyl itaconate (4-OI) is the cell-permeable derivative of itaconate that can activate Nrf2 signaling by alkylating Keap1’s cysteine residues. Here, we tested the potential effect of 4-OI on hydrogen peroxide (H2O2)-induced oxidative injury in osteoblasts. In OB-6 cells and primary murine osteoblasts, 4-OI was able to activate Nrf2 signaling cascade and cause Keap1–Nrf2 disassociation, Nrf2 protein stabilization, cytosol accumulation, and nuclear translocation. 4-OI also augmented antioxidant-response element reporter activity and promoted expression of Nrf2-dependent genes (HO1, NQO1, and GCLC). Pretreatment with 4-OI inhibited H2O2-induced reactive oxygen species production, cell death, and apoptosis in osteoblasts. Furthermore, 4-OI inhibited H2O2-induced programmed necrosis by suppressing mitochondrial depolarization, mitochondrial cyclophilin D-ANT1 (adenine nucleotide translocase 1)-p53 association, and cytosol lactate dehydrogenase release in osteoblasts. Ectopic overexpression of immunoresponsive gene 1 (IRG1) increased endogenous itaconate production and activated Nrf2 signaling cascade, thereby inhibiting H2O2-induced oxidative injury and cell death. In OB-6 cells, Nrf2 silencing or CRISPR/Cas9-induced Nrf2 knockout blocked 4-OI-induced osteoblast cytoprotection against H2O2. Conversely, forced Nrf2 activation, by CRISPR/Cas9-induced Keap1 knockout, mimicked 4-OI-induced actions in OB-6 cells. Importantly, 4-OI was ineffective against H2O2 in Keap1-knockout cells. Collectively, 4-OI efficiently activates Nrf2 signaling to inhibit H2O2-induced oxidative injury and death of osteoblasts.

Integrative metabolomics and transcriptomics identifies itaconate as an adjunct therapy to treat ocular bacterial infection

“…The mechanisms for anti-inflammatory effects of itaconate have been reported to involve the inhibition of succinate dehydrogenase, 26 , 56 blockade of IκBζ translation, 57 and activation of NRF2. 39 Although our data support the idea of itaconate-induced Nrf2/Ho-1 antioxidant signaling in exerting protective effects, 39 , 58 , 59 recent studies report distinct mechanisms for endogenous itaconate versus its derivatives in regulating inflammation. 35 , 36 The itaconate derivative OI reduces inflammation by triggering electrophilic stress, which is compensated by activation of the antioxidant Nrf2/Ho-1 axis, whereas endogenous itaconate evokes NRF2-independent mechanisms.…”

The Emerging Application of Itaconate: Promising Molecular Targets and Therapeutic Opportunities

“…Furthermore, they also found that DI did not have the same effect on osteoclast function indicate that general electrophilic stress was probably not sufficient to induce the inhibition of osteoclastogenesis. In another research Zheng et al ( 2020 ) found 4-OI protected OB-6 cells and primary murine osteoblasts from oxidative injury, cell death, and apoptosis treated by H 2 O 2 through disassociation of Keap1 and Nrf2.…”

Nrf2 is a central regulator of the metabolic landscape in macrophages and finetunes their inflammatory response

“…Finally, 4-OI has emerged as an anti-inflammatory compound with utility in various disease models via activation of Nrf2 (Li et al, 2020;Liu et al, 2021;Olagnier et al, 2018;Olagnier et al, 2020;Zheng et al, 2020). Importantly, 4-OI represses interferon signaling both in response to viral stimuli and in cases of type I interferonopathies (Olagnier et al, 2018).…”