Intestinal Epithelial Cell Exosome Launches IL-1β-Mediated Neuron Injury in Sepsis-Associated Encephalopathy

Abstract

BackgroundGut–microbiota–brain axis links the relationship between intestinal microbiota and sepsis-associated encephalopathy (SAE). However, the key mediators between them remain unclear.MethodsMemory test was determined by Water maze. Intestinal flora was measured by 16S RNA sequencing. Neurotransmitter was detected by high-performance liquid chromatography (HPLC). Histopathology was determined by H&E, immunofluorescence (IF), and terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL) staining. Flow cytometry was employed to determine the proportion of macrophages.ResultsFecal microbiota transplantation (FMT) relieved hippocampus impairment of SAE rats by inhibiting inflammation cytokine secretion, the expression of IBA-1 and neurotransmitter disturbance, and cell apoptosis and autophagy, accompanied by the reduced M1 polarization and M1 pro-inflammation factors produced by macrophages in mesenteric lymph nodes (MLNs). Actually, M1 polarization in SAE rats depended on intestinal epithelial cell (IEC)-derived exosome. GW4869-initiated inhibition of exosome secretion notably abolished M1 polarization and the secretion of IL-1β. However, GW4869-mediated improvement of hippocampus impairment was counteracted by the delivery of recombinant interleukin (IL)-1β to hippocampus. Mechanistically, IEC-derived exosome induced the excessive circulating IL-1β produced by CP-R048 macrophages, which subsequently induced damage and apoptosis of hippocampal neurons H19-7 in an autophagy-dependent manner. And reactivation of autophagy facilitates intestinal IL-1β-mediated hippocampal neuron injury.ConclusionCollectively, intestinal flora disturbance induced the exosome release of IECs, which subsequently caused M1 polarization in MLNs and the accumulation of circulating IL-1β. Circulating IL-1β promoted the damage and apoptosis of neurons in an autophagy-dependent manner. Possibly, targeting intestinal flora or IEC-derived exosome contributes to the treatment of SAE.

Targeting the gut microbiome in the management of sepsis-associated encephalopathy

“…The neurocognitive benefits correlated with a significant reduction in inflammatory cytokines IL-1β, IL-6, and TNF- α, apoptosis, and concentrations of the excitatory neurotransmitter glutamate. Inhibition of intestinal exosome section of IL-1β reversed neurologic deficits associated with SAE, a hypothesis further supported by the reemergence behavioral changes upon exogenous recombinant IL-1β administration ( 70 ).…”

Extracellular vesicles, from the pathogenesis to the therapy of neurodegenerative diseases

“…Interestingly, growing evidence has implicated the involvement of peripheral EVs in the pathogenesis of neurological diseases with the discovery of crosstalk between brain and other organ systems in a “bottom-up” manner including gut-brain, lung-brain, and bone-brain axes [ 161 , 162 ]. Intestinal epithelial cells have been reported to release EVs to induce IL-1β-mediated neuronal injury in sepsis-associated encephalopathy, which launches long-term cognitive deficits and neurodegeneration [ 163 ]. Moreover, ventilation-induced lung injury causes lung inflammation, leading to selective loading of caspase-1 into lung-derived EVs [ 164 ].…”

Sepsis-Induced Brain Dysfunction: Pathogenesis, Diagnosis, and Treatment

“…Recently, the interactions of organs are getting a lot of attention. The gut can damage neurons through the accumulation of cytokines [ 122 ]. In conclusion, in sepsis, various direct or indirect factors could lead to neuronal damage and aggravate the development of cognitive impairment.…”