Nobiletin attenuates Nrf2-Gpx4-regulated ferroptosis in septic liver injury by modulating the gut microbiota

Abstract

AbstractBackground Nobiletin (NOB), a plant-based polymethoxyflavone, has been shown to be a promising protective agent against sepsis; yet the mechanisms were not fully elucidated. The gut microbiota is found to be strongly associated with sepsis-associated acute liver injury (SALI). Here, our study aimed to determine whether these protective effects of NOB against SALI were related to modulations in the gut microbiota. Methods Cecal ligation and puncture (CLP) was used to induce SALI in mice. NOB therapy by gavage (50 mg/kg/day) was administrated for 7 days before CLP treatment. The 16S rRNA gene sequencing and fecal microbiota transplantation (FMT) were performed to explore the function of gut microbiota in SALI mice. Markers of ferroptosis, inflammation, gut microbiota composition, and liver injury were determined. Results NOB administration significantly alleviated hepatic ferroptosis and inflammation in septic mice. Meanwhile, NOB upregulated nuclear factor E2-related factor 2 (Nrf2) and its downstream proteins heme oxygenase-1 (HO-1) expression levels in the liver. Nrf2 inhibitor ML385 significantly eradicated NOB administration decreased hepatic ferroptosis in SALI mice. Additionally, increased abundances ofLigilactobacillus,Akkermansia, andLactobacillus, and decreased abundances ofDubosiellaandBacteroidesin the gut were observed under NOB treatment, suggesting that NOB ameliorated SALI-induced microbial dysbiosis. Furthermore, gut microbiota ablation by antibiotic treatment partly eradicated NOB administration decreased hepatic ferroptosis and activated Nrf2 signaling in SALI mice, suggesting NOB inhibited ferroptosis and activated Nrf2 signaling in SALI mice by modulating gut microbiota. Moreover, transplantation of the NOB-microbiota to microbiota-depleted mice was sufficient to decreased hepatic ferroptosis, inflammation, and activated Nrf2 signaling in the liver. Conclusions We have shown that NOB attenuates Nrf2-Gpx4-regulated ferroptosis in septic liver injury by modulating the gut microbiota. Of note, NOB might be employed as a potential therapeutic agent for sepsis treatment. Our findings also provide novel insights into microbiome-based therapeutic approaches for sepsis.