NRF2-Dependent Anti-Inflammatory Activity of Indole via Cell Surface Receptor Signaling in Murine Macrophages

Cheng, C.; Shivanagoudra, S.; Mukunth, A.; Biradar, S.; Serrano Matos, Y. A.; Klemashevich, C.; Kim, D. M.; Wright, G. A.; Ghosh, S.; Jala, V. R.; Safe, S. H.; Alaniz, R. C.; Jayaraman, A.

doi:10.64898/2025.12.21.695859

bioRxiv · 10.64898/2025.12.21.695859

NRF2-Dependent Anti-Inflammatory Activity of Indole via Cell Surface Receptor Signaling in Murine Macrophages

Cheng, C.·Shivanagoudra, S.·Mukunth, A.·Biradar, S.·Serrano Matos, Y. A.·Klemashevich, C.·Kim, D. M.·Wright, G. A.·Ghosh, S.·Jala, V. R.·Safe, S. H.·Alaniz, R. C.·Jayaraman, A.

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Abstract

In this study, we report indoles anti-inflammatory effects to be AhR-independent in RAW 264.7 macrophages. To explore the possibility of indoles surface-receptor mediated signaling, we developed an indole-bovine serum albumin conjugate (I3B), which primarily engage cell surface receptors and has limited intracellular engagement. Treatment with 10 M of I3B led to a comparable reduction of TNF- production in LPS-stimulated RAW 264.7 macrophages to that observed with 500 M of free indole. Transcriptome profiling of I3B-treated LPS-stimulated RAW 264.7 macrophages revealed, I3B blunts pro-inflammatory response and induces gene signatures consistent with NRF2 activation. LPS-stimulated NRF2-/- Bone Marrow-derived Macrophages (BMM) treated with I3B, showed higher levels of pro-inflammatory cytokine production relative to non-treated BMM. To define the upstream pathways responsible for this NRF2-depedent response, we examined GPCR-mediated signaling and found that I3B engages a Gq-coupled receptor to induce PKC{delta} phosphorylation, and subsequent NRF2 phosphorylation. Our results suggest I3B signals through a surface-receptor in a NRF2-dependent manner to reduce inflammation in murine macrophages. TeaserA cell-impermeant indole conjugate inhibits inflammatory signaling in macrophages through an NRF2-dependent mechanism.

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Cheng, C., Shivanagoudra, S., Mukunth, A., Biradar, S., Serrano Matos, Y. A., Klemashevich, C., Kim, D. M., Wright, G. A., Ghosh, S., Jala, V. R., Safe, S. H., Alaniz, R. C., Jayaraman, A.. 2025-12-23. NRF2-Dependent Anti-Inflammatory Activity of Indole via Cell Surface Receptor Signaling in Murine Macrophages. https://doi.org/10.64898/2025.12.21.695859

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