Legumains belonging to C_13 peptidase family of proteins, and are ubiquitously disseminated among all vertebrate and invertebrate organisms, and have been implicated in innumerable biological and cellular functionality. Herein, we characterized and evaluated immunoregulatory characteristics of Legumain-1 from Fasciola gigantica (Fg-LGMN-1) during its interaction with host immune cells. The isopropyl-ß-d-thiogalactopyranoside (IPTG) stimulated RFg-LGMN-1 protein was positively detected by rat serum containing anti-RFg-LGMN-1 polyclonal antibodies. Furthermore, the uptake of RFg-LGMN-1 by goat monocytes was successfully confirmed using Immunofluorescence Assay (IFA). The immunohistochemical analysis revealed the native localization of LGMN-1 protein on the periphery and internal structures such as suckers, pharynx, and genital pore of the adult parasite, thereby validating its presence in excretory-secretory (ES) products of F. gigantica. The RFg-LGMN-1 co-incubated with concanavalin-A (Con-A) stimulated the increase of interleukin 2 (IL-2), IL-10, and IL-17 in monocytes derived from peripheral blood mononuclear cells (PBMCs) in the concentration-dependent manner. However, the IL-4 cytokine in response to the RFg-LGMN-1 protein declined. These results illuminated the role of LGMN-1 during the parasite-host interface. Our findings elaborated additional evidence that Legumain protein play a role in the manipulating host immune responses during parasite infections. However, further evaluation of RFg-LGMN-1 protein in context of its immunomodulatory roles should be conducted to enhance our understandings of the mechanisms employed by F. gigantica to evade host immune responses.

Legumains 属于 C_13 肽酶蛋白家族，在所有脊椎动物和无脊椎动物中普遍传播，并与无数的生物和细胞功能有关。在此，我们表征并评估了巨片形吸虫 Legumain-1 (Fg-LGMN-1) 在与宿主免疫细胞相互作用过程中的免疫调节特性。含有抗 RFg-LGMN-1 多克隆抗体的大鼠血清可阳性检测异丙基-β-d-硫代半乳糖苷 (IPTG) 刺激的 RFg-LGMN-1 蛋白。此外，使用免疫荧光测定 (IFA) 成功证实​​了山羊单核细胞对 RFg-LGMN-1 的摄取。免疫组织化学分析揭示了 LGMN-1 蛋白在成虫寄生虫的外周和内部结构（如吸盘、咽和生殖孔）的天然定位，从而验证了其在巨大巨镰孢的排泄分泌 (ES) 产物中的存在。 RFg-LGMN-1 与刀豆球蛋白-A (Con-A) 共孵育可刺激外周血单核细胞 (PBMC) 来源的单核细胞中白细胞介素 2 (IL-2)、IL-10 和 IL-17 的增加。浓度依赖性方式。然而，IL-4 细胞因子对 RFg-LGMN-1 蛋白的反应下降。这些结果阐明了 LGMN-1 在寄生虫-宿主界面中的作用。我们的研究结果阐述了额外的证据，证明 Legumain 蛋白在寄生虫感染期间操纵宿主免疫反应中发挥作用。然而，应进一步评估 RFg-LGMN-1 蛋白的免疫调节作用，以增强我们对 F. gigantica 逃避宿主免疫反应的机制的理解。