Establishing a novel sepsis-associated brain dysfunction model in zebrafish larvae

Objective As a common complication of sepsis, sepsis-associated encephalopathy (SAE) was observed with high mortality, but there were less effective therapeutic strategies due to disease complexity. This study aimed to establish and characterize a larval zebrafish model of sepsis-associated brain dysfunction (SBD) suitable for phenotypic assessment and compound screening. Methods The SBD zebrafish larvae model was established by lipopolysaccharide (LPS) injection into the peritoneal cavity. Sepsis-induced inflammation of the intestine and brain was assessed using transgenic fluorescent larvae. The infection’s influence on intestine structure and brain function was monitored by HE staining, fluorescence staining, and behavioral assessment. Simultaneously, 16S rRNA sequencing and whole-larva transcriptomic profiling were conducted to characterize larva-associated microbial changes and systemic molecular responses. The expression of genes involved in inflammation, barrier function, ferroptosis as well as apoptosis was quantified via qPCR. Results After LPS treatment for 24 h, there were significant neutrophil infiltration, increasing peristalsis, structural damage, and upregulated inflammatory gene expression in the intestine. Traced by using 10 kDa dextran-tetramethylrhodamine, the zebrafish larvae were observed with obviously increased fluorescence in the brain. In combination with downregulated tight junction genes, it suggested the breakdown of blood–brain barrier permeability. Simultaneously, we found increasing apoptotic cells, infiltrated neutrophils as well as imbalanced neurotransmitters in the larvae brain, and they exhibited reduced locomotor activity and altered color-preference/exploratory behavior. The 16S rRNA sequencing and transcriptome results showed restructuring of the larva-associated microbial community, including an increased relative abundance of Aeromonas . Whole-larva transcriptomic profiling identified a prominent ferroptosis-related signature, which was supported by increased ROS levels, altered ferroptosis-related gene expression, and mitochondrial changes. Increased lipid peroxidation provided additional support for ferroptosis-related alterations. Conclusion We successfully developed a novel sepsis-associated brain dysfunction zebrafish larvae model. Based on its advantages of high throughput, rapidity, visualization, and facile gene edition, this model is expected to be beneficial for SAE drug discovery and disease mechanism exploration.