目的 探究疟原虫感染红细胞源外泌体对实验性脑型疟（ECM）小鼠的免疫保护作用及机制。方法 从感染约氏疟原虫17XNL（P.y17XNL）的BALB/c小鼠外周血提取鉴定外泌体。将C57BL/6J小鼠随机分为ECM组、外泌体免疫组（Exos + ECM组）和阴性对照组（NC组）。Exos + ECM组分两次经尾静脉注射进行外泌体免疫；免疫后20 d，ECM组和Exos + ECM组小鼠经腹腔注射1 × 10⁶个伯氏疟原虫ANKA（P.bANKA）感染的红细胞，NC组腹腔注射同等体积生理盐水，动态观察红细胞感染率和小鼠生存率。取小鼠脑组织，伊文思蓝（EB）灌注后检测上清630 nm波长吸光度值（A₆₃₀值）评估小鼠血脑屏障完整性。苏木精-伊红（HE）染色观察小鼠脑组织病理变化，免疫组化染色观察脑微血管的细胞间黏附分子-1（ICAM-1）和血管细胞黏附分子-1（VCAM-1）表达。蛋白免疫印迹（Western blotting）和实时荧光定量逆转录PCR（qRT-PCR）检测小鼠脑组织炎症相关细胞因子的变化。结合蛋白质组学分析外泌体核心差异成分与脑组织炎症因子的调控关联。结果 ECM组和Exos + ECM组的红细胞感染率分别于感染后第11天和第15天达到峰值，分别为（25.0 ± 0.0）%和（17.2 ± 4.4）%，Exos + ECM组上升速度较慢；ECM组小鼠在感染后第13天全部死于脑型疟，Exos + ECM组小鼠感染后第15天生存率为83.3%。血脑屏障完整性检测结果显示，ECM组血脑屏障完整性被破坏、Exos + ECM组破坏不明显；NC组和Exos + ECM组上清液A₆₃₀值为分别为（0.28 ± 0.04）和（0.62 ± 0.01），均低于ECM组的（0.89 ± 0.02）（t = 24.24、10.53，均P < 0.01）。脑组织HE染色和免疫组化结果显示，与ECM组相比，Exos + ECM组脑微血管中感染红细胞减少、炎性浸润减轻，ICAM-1和VCAM-1表达水平下调。qRT-PCR结果显示，Exos + ECM组小鼠脑ICAM-1、VCAM-1、白细胞介素-6（IL-6）、IL-17A、转移生长因子β（TGF-β）、IL-10的mRNA相对转录水平分别为4.05 ± 0.42、1.24 ± 0.14、0.48 ± 0.3、0.27 ± 0.31、1.39 ± 0.53、4.23 ± 3.29，均低于ECM组的8.11 ± 0.86、2.80 ± 0.33、1.38 ± 0.76、2.28 ± 0.26、2.94 ± 0.49、16.02 ± 3.56（t = 8.76、8.52、2.91、6.81、4.51、5.41，P < 0.01、0.01、0.05、0.01、0.05、0.01）。Western blotting结果显示，Exos + ECM组小鼠脑Toll样受体4（TLR4）、IL-1β、肿瘤坏死因子-α（TNF-α）蛋白表达水平分别为0.84 ± 0.06、0.81 ± 0.04、2.07 ± 0.72，均低于ECM组的1.24 ± 0.04、0.85 ± 0.03、6.06 ± 2.45（t = 7.07、1.27、3.12，均P < 0.05）。蛋白质组学结果显示，P.y17XNL感染小鼠和正常小鼠外泌体的差异蛋白主要富集在细胞核蛋白、细胞质蛋白、质膜蛋白以及线粒体蛋白上，与蛋白质输出、转运和氨基酸代谢有关。结论 外泌体免疫对ECM具有免疫保护作用，能够降低红细胞感染率、提高小鼠存活率。主要作用机制可能与降低脑部炎症、保护血脑屏障完整性、改善小鼠脑组织病理损伤有关。

Objective To explore the immunoprotective effect and mechanism of exosomes derived from Plasmodium-infected red blood cells on experimental cerebral malaria (ECM) in mice. Methods Exosomes were extracted and identified from peripheral blood of BALB/c mice infected with Plasmodium yoelii 17XNL (P.y17XNL). C57BL/6J mice were randomly divided into ECM group, exosome immunization group (Exos + ECM group) and negative control group (NC group). Mice in the Exos + ECM group received two doses of exosome immunization via tail vein injection; 20 days after immunization, mice in the ECM group and Exos + ECM group were intraperitoneally injected with 1 × 10⁶ P. berghei ANKA (P.bANKA)-infected red blood cells, while mice in the NC group were intraperitoneally injected with an equal volume of normal saline. The erythrocyte infection rate and mice survival rate were dynamically observed. Mice brain tissues were collected, and the absorbance at 630 nm (A₆₃₀ value) of the supernatant was detected after Evans blue perfusion to evaluate the integrity of the blood-brain barrier in mice. Hematoxylin-eosin (HE) staining was used to observe the pathological changes of mice brain tissue, and immunohistochemical staining was performed to detect the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in brain microvessels. Western blotting and real-time fluorescent quantitative reverse transcription PCR (qRT-PCR) were used to detect the changes of inflammation-related cytokines in mice brain tissue. Proteomics analysis was combined to explore the regulatory association between core differential components of exosomes and brain tissue inflammatory factors. Results The erythrocyte infection rates of the ECM group and Exos + ECM group reached the peak on day 11 and day 15 post-infection, with values of (25.0 ± 0.0)% and (17.2 ± 4.4)%, respectively, and the erythrocyte infection rate in the Exos + ECM group increased more slowly. All mice in the ECM group died of cerebral malaria on day 13 post-infection, and the survival rate of mice in the Exos + ECM group was 83.3% on day 15 post-infection. The detection results of blood-brain barrier integrity showed that the blood-brain barrier in the ECM group was damaged, while the damage in the Exos + ECM group was not obvious. the A₆₃₀ values of the supernatant in the NC group and Exos + ECM group were (0.28 ± 0.04) and (0.62 ± 0.01) respectively, both lower than (0.89 ± 0.02) in the ECM group (t = 24.24, 10.53, both P < 0.01). The results of HE staining and immunohistochemistry of brain tissue showed that, compared with the ECM group, the number of infected red blood cells in brain microvessels, inflammatory infiltration, and the expression levels of ICAM-1 and VCAM-1 in the Exos + ECM group were reduced. The qRT-PCR results showed that the relative mRNA transcription levels of ICAM-1, VCAM-1, interleukin-6 (IL-6), IL-17A, transforming growth factor-β (TGF-β) and IL-10 in the brain of Exos + ECM group mice were 4.05 ± 0.42, 1.24 ± 0.14, 0.48 ± 0.3, 0.27 ± 0.31, 1.39 ± 0.53 and 4.23 ± 3.29, respectively, which were lower than 8.11 ± 0.86, 2.80 ± 0.33, 1.38 ± 0.76, 2.28 ± 0.26, 2.94 ± 0.49 and 16.02 ± 3.56 in the ECM group (t = 8.76, 8.52, 2.91, 6.81, 4.51, 5.41, P < 0.01, 0.01, 0.05, 0.01, 0.05, 0.01). Western blotting results showed that the protein expression levels of Toll-like receptor 4 (TLR4), IL-1β and tumor necrosis factor-α (TNF-α) in the brain of Exos + ECM group mice were 0.84 ± 0.06, 0.81 ± 0.04 and 2.07 ± 0.72, respectively, which were lower than 1.24 ± 0.04, 0.85 ± 0.03 and 6.06 ± 2.45 in the ECM group (t = 7.07, 1.27, 3.12, all P < 0.05). Proteomics results showed that the differential proteins of exosomes from P.y17XNL-infected mice and normal mice were mainly enriched in nuclear proteins, cytoplasmic proteins, plasma membrane proteins and mitochondrial proteins, which were related to protein export, transport and amino acid metabolism. Conclusion Exosome immunization had an immunoprotective effect on ECM, which can reduce the erythrocyte infection rate and improve the survival rate of mice. The main mechanism may be related to reducing brain inflammation, protecting the integrity of the blood-brain barrier and improving the pathological damage of mice brain tissue.