Dehydroandrographolide Alleviates Oxidative Stress, Inflammatory Response, and Pyroptosis in DSS-Induced Colitis Mice by Modulating Nrf2 Signaling Pathway

TL;DR

Dehydroandrographolide reduces inflammation and oxidative stress in colitis mice by activating the Nrf2 signaling pathway.

Contribution

DA's protective effects in colitis are shown to depend on Nrf2 signaling, offering a new therapeutic approach for inflammatory bowel disease.

Findings

DA inhibits inflammation by modulating Erk, Jnk, P38, and NF-κB pathways.

DA activates Nrf2 signaling, reducing oxidative stress and pyroptosis in colitis.

DA's effects are lost in Nrf2-deficient mice, confirming Nrf2 dependency.

Abstract

Dehydroandrographolide (DA), a bioactive diterpenoid from Andrographis paniculata with diverse biological activity, was investigated for its antioxidant and anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and dextran sulfate sodium (DSS)-induced murine colitis. In vitro, DA inhibited the inflammatory response by modulating extracellular Signal-Regulated Kinase (Erk), c-Jun N-terminal Kinase (Jnk), p38 Mitogen-Activated Protein Kinase (P38), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 activation, and downregulated interleukin-6 (il-6) and interleukin-1β (il-1β) mRNA. It also had antioxidant effects by upregulating Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2), NAD(P)H quinone dehydrogenase 1 (Nqo-1) and heme oxygenase-1 (Ho-1), promoting protein kinase B (Akt) and 5′-adenosine monophosphate-activated protein kinase-α1 (Ampk-α1) phosphorylation. DA decreased cyclooxygenase-2 (Cox-2) and inducible nitric oxide synthase (iNos) levels and alleviated intracellular reactive oxygen species (ROS) accumulation. In vivo, DA alleviated DSS-induced colitis in wild type (WT) mice by improving weight loss, disease activity index, colonic inflammation, and oxidative stress. The beneficial effects were linked to inhibiting Erk, Jnk, and P38 activation and enhancing Nrf2 signaling pathway. DA inhibited NOD-like receptor family pyrin domain-containing 3 (Nlrp3) inflammasome-mediated pryoptosis. However, DA’s protective effects were abolished in DSS-induced nrf2−/− mice, suggesting its efficacy depends on Nrf2 signaling. Overall, DA alleviates oxidative stress, inflammatory responses, and pyroptosis in experimental colitis mice mainly by activating Nrf2 signaling pathway, highlighting its potential as a promising therapeutic option for inflammatory bowel disease.

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