College of Veterinary Sciences and Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram, India; ICAR-IVRI, Izatnagar, Bareilly, Uttar Pradesh, India.
ICAR-IVRI, Izatnagar, Bareilly, Uttar Pradesh, India; ICAR-NIVEDI, Bengaluru, Karnataka, India.
Exp Parasitol. 2022 Nov;242:108369. doi: 10.1016/j.exppara.2022.108369. Epub 2022 Sep 1.
Fasciola gigantica faces a series of threats from various free radicals produced by the host immune system during its invasion through the abdominal cavity and establishment in the bile duct of ruminants, limiting the fluke viability. The role of the superoxide radical produced by Muzaffarnagari sheep immune effector cells against F. gigantica newly excysted juveniles (NEJs) is highlighted in this study, as is the critical role of superoxide dismutase enzyme (SOD) in dismutation of superoxide radicals derived from host immune effector cells in vitro. Three concentrations of the ovine immune effector cells viz. 2.5, 5, and 10 × 10 cells were tested for their ability to induced cytotoxic killing of the parasite. All the three cell concentrations caused significant (p < 0.01) cytotoxic killing of NEJs in comparison to the control groups. Also, reduction of the immune effector cell concentration directly correlates with the NEJs killing. Attachment of immune effector cells to the parasite tegument in the presence of anti-F. gigantica antibodies was found to be critical in inducing NEJs killing via antibody-dependent cell-mediated cytotoxicity (ADCC). However, the addition of SOD greatly inhibits cytotoxic killing of NEJs, demonstrating the importance of SOD enzyme in fluke survival and parasite evasion of the host immunity. Thus, F. gigantica SOD warrants a promising candidate for immunoprophylactic studies in ruminants against the tropical liver fluke.
巨型片形吸虫在通过腹腔入侵和在反刍动物胆管中定居时，会受到宿主免疫系统产生的各种自由基的一系列威胁，从而限制了片形吸虫的生存能力。本研究强调了 Muzaffarnagari 绵羊免疫效应细胞产生的超氧自由基在对抗新孵化的幼虫 (NEJ) 中的作用，以及超氧化物歧化酶 (SOD) 在体外将来自宿主免疫效应细胞的超氧自由基歧化中的关键作用。研究测试了三种浓度的绵羊免疫效应细胞，即 2.5、5 和 10×10 个细胞，以研究它们诱导寄生虫细胞毒性杀伤的能力。与对照组相比，所有三种细胞浓度都导致 NEJ 发生显著的细胞毒性杀伤 (p<0.01)。此外，免疫效应细胞浓度的降低与 NEJs 的杀伤直接相关。在存在抗巨型片形吸虫抗体的情况下，免疫效应细胞附着在寄生虫的表皮上，这对于通过抗体依赖的细胞介导的细胞毒性 (ADCC) 诱导 NEJs 杀伤至关重要。然而，添加 SOD 大大抑制了 NEJs 的细胞毒性杀伤，表明 SOD 酶在吸虫的存活和寄生虫逃避宿主免疫方面的重要性。因此，巨型片形吸虫 SOD 是针对反刍动物热带肝吸虫病进行免疫预防研究的有前途的候选者。
