Laboratorio de Inmunidad en Mucosas, Unidad de Investigación en Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios 1, Los Reyes, Iztacala, Tlalnepantla, 54090, Estado de México, Mexico.
Laboratorio de Inmunidad en Mucosas, Unidad de Investigación en Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios 1, Los Reyes, Iztacala, Tlalnepantla, 54090, Estado de México, Mexico.
Dev Comp Immunol. 2021 Aug;121:104071. doi: 10.1016/j.dci.2021.104071. Epub 2021 Mar 22.
The insecticidal Bacillus thuringiensis protein Cry1Ac is produced as a protoxin and becomes activated to a toxin when ingested by larvae. Both proteins are immunogenic and able to activate macrophages. The proposed mechanism of immunostimulation by Cry1Ac protoxin has been related to its capacity to activate antigen-presenting cells (APC), but its ability to activate dendritic cells (DC) has not been explored. Here we evaluated, in the popliteal lymph nodes (PLN), spleen and peritoneum, the activation of DC CD11c MHC-II following injection with single doses (50 μg) of Cry1Ac toxin or protoxin via the intradermal (i.d.) and intraperitoneal (i.p.) routes in C57BL/6 mice. In vivo stimulation with both Cry1Ac proteins induced activation of DC via upregulation of CD86, primarily in PLN 24 h after i. d. injection. Moreover, this activation was detected in DC, displaying CD103+, a typical marker of migratory DC, while upregulation of CD80 was uniquely induced by toxin. Tracking experiments showed that Cy5-labeled Cry1Ac proteins could rapidly reach the PLN and localize near DC, but some label remained in the footpad. When the capacity of Cry1Ac-activated DC to induce antigen presentation was examined, significant proliferation of naïve T lymphocytes was induced exclusively by the protoxin. The protoxin elicited a Th17-biased cytokine profile. Moreover, only the Cry1Ac toxin induced a pronounced proliferation of B cells from both untreated and Cry1Ac-injected mice, suggesting that it acts as a polyclonal activator. In conclusion, Cry1Ac protoxin and toxin show a distinctive capacity to activate APCs.
苏云金芽孢杆菌杀虫蛋白 Cry1Ac 以原毒素的形式产生，当被幼虫摄入时会变成毒素。这两种蛋白都具有免疫原性，能够激活巨噬细胞。Cry1Ac 原毒素的免疫刺激作用机制已被证明与其激活抗原呈递细胞 (APC) 的能力有关，但它激活树突状细胞 (DC) 的能力尚未得到探索。在这里，我们评估了在 C57BL/6 小鼠的腘淋巴结 (PLN)、脾脏和腹膜中，经皮内 (i.d.) 和腹腔内 (i.p.) 途径注射 50μg 单一剂量的 Cry1Ac 毒素或原毒素后，DC CD11c MHC-II 的激活情况。两种 Cry1Ac 蛋白的体内刺激均通过上调 CD86 诱导了 DC 的激活，主要在 i.d. 注射后 24 小时的 PLN 中。此外，这种激活在显示 CD103+的 DC 中被检测到，CD103+是迁移性 DC 的典型标志物，而 CD80 的上调仅由毒素诱导。跟踪实验表明，Cy5 标记的 Cry1Ac 蛋白可以迅速到达 PLN 并定位在 DC 附近，但一些标记仍留在足垫中。当检查 Cry1Ac 激活的 DC 诱导抗原呈递的能力时，仅原毒素就可诱导幼稚 T 淋巴细胞的显著增殖。原毒素引发了 Th17 偏向的细胞因子谱。此外，只有 Cry1Ac 毒素诱导了来自未经处理和 Cry1Ac 注射小鼠的 B 细胞的明显增殖，这表明它是一种多克隆激活剂。总之，Cry1Ac 原毒素和毒素表现出激活 APC 的独特能力。
