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bioRxiv · 10.1101/2023.12.22.572877

Diroximel fumarate acts through Nrf2 to attenuate methylglyoxal-induced nociception in mice and decreases ISR activation in DRG neurons

Yousuf, M. S.·Mancilla Moreno, M.·Li, J.·He, L.·Royer, D.·Zhang, J.·Woodall, B. J.·Grace, P. M.·Price, T. J.
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Abstract

Diabetic neuropathic pain is associated with elevated plasma levels of methylglyoxal (MGO). MGO is a metabolite of glycolysis that causes mechanical hypersensitivity in mice by inducing the integrated stress response (ISR), which is characterized by phosphorylation of eukaryotic initiation factor 2 (p-eIF2). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates the expression of antioxidant proteins that neutralize MGO. We hypothesized that activating Nrf2 using diroximel fumarate (DRF) would alleviate MGO-induced pain hypersensitivity. We pretreated male and female C57BL/6 mice daily with oral DRF prior to intraplantar injection of MGO (20 ng). DRF (100 mg/kg) treated animals were protected from developing MGO-induced mechanical and cold hypersensitivity. Using Nrf2 knockout mice we demonstrate that Nrf2 is necessary for the anti-nociceptive effects of DRF. In cultured mouse and human dorsal root ganglion (DRG) sensory neurons, we found that MGO induced elevated levels of p-eIF2. Co-treatment of MGO (1 {micro}M) with monomethyl fumarate (MMF, 10, 20, 50 {micro}M), the active metabolite of DRF, reduced p-eIF2 levels and prevented aberrant neurite outgrowth in human DRG neurons. Our data show that targeting the Nrf2 antioxidant system with DRF is a strategy to potentially alleviate pain associated with elevated MGO levels. PerspectiveThis study demonstrates that activating Nrf2 with DRF prevents the development of pain caused by MGO in mice and reduces ISR in mouse and human DRG in vitro models. We propose that Nrf2 activators like DRF should be tested to alleviate diabetic neuropathic pain associated with elevated MGO in patients. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/572877v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@5e0703org.highwire.dtl.DTLVardef@11e95bforg.highwire.dtl.DTLVardef@f92f2borg.highwire.dtl.DTLVardef@187f12d_HPS_FORMAT_FIGEXP M_FIG C_FIG Article HighlightsO_LIMGO induces mechanical and cold hypersensitivity in mice that is prevented with pre-treatment with DRF. C_LIO_LIDRF pre-treatment does not protect Nrf2-knockout mice from developing pain hypersensitivity suggesting that Nrf2 is necessary for DRFs antinociceptive effects. C_LIO_LIMMF, the active metabolite of DRF, prevents MGO-induced increase in p-eIF2a levels in mouse and human DRG neurons in vitro. C_LIO_LIMMF prevents MGO-induced aberrant neurite outgrowth in human DRG neurons. C_LIO_LINrf2 activators, like the FDA-approved DRF, is an option to alleviate neuropathic pain in patients with diabetes. C_LI

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Yousuf, M. S., Mancilla Moreno, M., Li, J., He, L., Royer, D., Zhang, J., Woodall, B. J., Grace, P. M., Price, T. J.. 2023-12-23. Diroximel fumarate acts through Nrf2 to attenuate methylglyoxal-induced nociception in mice and decreases ISR activation in DRG neurons. https://doi.org/10.1101/2023.12.22.572877

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