Platinum-doped emodin carbon dots mitigate sepsis-induced lung injury by targeting the gut-lung axis

Sepsis-induced acute lung injury is a life-threatening complication with limited therapeutic options. Although the gut-lung axis is crucial in sepsis pathogenesis, effective interventions targeting this pathway remain scarce. Here, we developed multi-enzymatic platinum-doped emodin carbon dots (Pt-ECDs) via a hydrothermal method. Pt-ECDs exhibited superior catalase, superoxide dismutase, glutathione peroxidase and peroxidase-like activities, enabling potent reactive oxygen species (ROS) scavenging. In a murine sepsis model, oral Pt-ECDs significantly improved survival, reduced systemic inflammation, and ameliorated lung injury. Transcriptomic analysis revealed that Pt-ECDs suppressed oxidative stress and macrophage pyroptosis in lung tissues. Mechanistically, integrated metabolomic and microbiome analyses demonstrated that Pt-ECDs modulated the gut microbiota, specifically inhibiting g_Bacteroides-derived palmitic acid (PA) production. We further confirmed that PA exacerbates macrophage pyroptosis and pro-inflammatory polarization by directly binding to NOX2 and NLRP3. Crucially, fecal microbiota transplantation from Pt-ECDs-treated mice attenuated septic lung injury, whereas microbiota depletion abolished the therapeutic benefits. Collectively, our findings identify Pt-ECDs as a promising nanotherapeutic that alleviates septic lung injury by targeting the gut microbiota-palmitic acid-pyroptosis axis.