Oral Multi-Enzymatic Manganese–Carbon Dots Alleviate Sepsis-Associated Lung Injury via the Gut–Lung Axis
Lei Peng, Honghao Song, Hu Shi, Lixue Wu, Yanwei Ma, Xiaoyi Fan, Min Wu, Liwei Duan, Zhenjie Li, Hongbin Yuan
Abstract
High Resolution Image Download MS PowerPoint Slide Sepsis-induced pulmonary injury represents a life-threatening global health challenge due to poorly defined pathological mechanisms. The gut-lung axis has been proven to be widely involved in sepsis-induced lung injury, yet effective interventions targeting gut microbiota homeostasis remain unknown. Single-cell sequencing revealed increased alveolar apoptosis and impaired macrophage efferocytosis during sepsis pathogenesis. Thus, we designed oral manganese-doped carbon dots (Mn-CDs) to alleviate septic lung injury by remodeling gut microbiota homeostasis and targeting the gut-lung axis. Biochemical characterization demonstrated Mn-CDs possess multienzyme mimetic activities (SOD-, CAT-, POD-, GPx-like) and potent ROS scavenging capacity. In murine sepsis models, Mn-CDs significantly improved systemic indices and were associated with macrophage anti-inflammatory states with enhanced efferocytosis, as evidenced by transcriptomic profiling. Integrated metagenomic/metabolomic analyses identified Mn-CDs-mediated enrichment of g_Clostridium and g_Bacteroides, concomitant with elevated indole-3-propionic acid (IPA) production. Subsequent in vitro studies demonstrate that IPA likely binds primarily to the aryl hydrocarbon receptor (AHR), promoting both efferocytosis and anti-inflammatory polarization in macrophages, thereby mitigating septic lung injury. Notably, the fecal microbiota transplantation (FMT) from Mn-CDs-treated mice not only alleviated systemic symptoms but also effectively promoted efferocytic polarization of pulmonary macrophages in septic mice. Depletion of the gut microbiota resulted in a significant loss of the protective efficacy of Mn-CDs in a murine model of septic lung injury. Collectively, the gut–lung axis mediated by microbiota-derived IPA and macrophage efferocytosis contributes to the remediation of septic lung injury, highlighting the potential of Mn-CDs in microbiome-directed critical care.