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Abstract
Objective To explore the roles of protoscolex exosomes and their ultrafiltrated lysates in the activation and immune regulation of dendritic cell (DC), and to further provide a basis for the research on the immune mechanism of echinococcosis infection. Methods A retrospective study was conducted, 30 children with echinococcosis admitted to Children's Hospital of Xinjiang Uygur Autonomous Region from July 2023 to July 2024 were selected as the research subjects. Cyst fluid of children with echinococcosis were collected, and exosomes were isolated and identified, and their ultrafiltrated lysates were prepared. Mouse splenic DC were sorted, cultured and divided into four groups: negative control group, protoscolex exosomes group, protoscolex exosome ultrafiltrated lysate group, and positive control group. After 48 h of culture, flow cytometry was performed to detect DC surface activation markers [including CD11c, CD40, CD80, CD86, (major histocompatibility complex classⅡ, MHCⅡ), etc], reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was used to determine the transcription level of indoleamine 2,3-dioxygenase (IDO), mRNA high-performance liquid chromatography (HPLC) was applied to measure the tryptophan concentration in cell supernatants. Statistical analysis was performed using one-way analysis of variance and Bonferroni method. Results The isolated exosomes exhibited a typical exosomal morphology with a particle size of 121 nm and expressed CD9 and CD63; the purity of sorted mouse splenic DC was over 90%. Flow cytometry results showed that compared with the negative control group, the positive rates of CD11c, CD86, CD80, CD40 and MHCⅡ in the protoscolex exosome group, protoscolex exosome ultrafiltrated lysate group and positive control group were significantly increased, and all the three groups could remarkably upregulate the transcription level of IDO mRNA and reduce the tryptophan concentration in the cell supernatant (all P<0.05). Among them, the regulatory effect of the protoscolex exosome ultrafiltrated lysate group was significantly stronger than that of the protoscolex exosome group, with the relative expression level of IDO mRNA reaching 6.8±0.1, and the tryptophan concentration in the cell supernatant was 0.23 mg/L in the former group. Additionally, the changes in the above indicators in both the protoscolex exosome group and the protoscolex exosome ultrafiltrated lysate group were significantly weaker than those in the positive control group (all P<0.05). Conclusion Protoscolex exosomes and their ultrafiltrated lysates can promote DC activation and activate the IDO-tryptophan pathway, with a more significant effect observed for protoscolex exosomes ultrafiltrated lysates. This study provides experimental evidence for in-depth analysis of the immune interaction between echinococcus and the host, as well as for immune intervention of echinococcosis.
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2026, Vol. 14 
