Abstract:

Objective To investigate the therapeutic mechanism of interleukin-1β (IL-1β) receptor blocker on lung injury in the sensitization process of Echinococcus granulosus cyst extravasated fluid. Methods The cysts of E. granulosus were collected from fresh sheep livers infected with E. granulosus from Hualing Slaughterhouse of Urumqi, Xinjiang. The cyst fluid was collected, digested and sedimented to obtain protoscoleces, and the supernatant was treated with endotoxin to obtain allergenic cyst fluid. Twenty-four mice were randomly divided into control group, sensitized group, blocker treatment group and blocker prevention group, with 6 mice in each group. Mice in the sensitized group, the blocker treatment group and the blocker prevention group were intraperitoneally injected with about 2 000 protoscoleces, respectively, while mice in the control group were injected with about the same volume (1 ml) of normal saline. Three months later, mice in the sensitized group were intraperitoneally injected with allergenic cyst fluid (0.1 ml per g weight); mice in the blocker treatment group were injected with allergenic cyst fluid prior to intravenous injection with IL-1β blocker (4 μg per g weight) 15 minutes later; mice in the blocker prevention group were injected with IL-1β blocker prior to intraperitoneal injection with allergenic cyst fluid 15 minutes later; mice in the control group were injected with the same volume of normal saline. The paraffin sections of mice lung tissues were stained with hematoxylin-eosin (HE) to observe the inflammatory damage under microscope. Total RNA was extracted from lung tissue and the mRNA relative transcription levels of tumor necrosis factor α (TNF-α), IL-6, cysteinyl aspartate specific proteinase-8, phosphatidylinositol 3 kinase (PI3K), protein kinase B (Akt) and nuclear factor kappa-B (NF-κB) were detected by qRT-PCR. Western blotting was used to detect the protein relative expression levels of PI3K, Akt and NF-κB, with β-actin as an internal reference. Data was analyzed by GraphPad Prism software. One-way analysis of variance was used for comparison between groups. Results HE staining showed that the lung tissues of the sensitized group were congested, with inflammatory cells swimming out and lymphocytes aggregating around the congested area. There was no obvious inflammatory reaction in the lung tissues of the blocker treatment group, blocker prevention group and control group. qRT-PCR results showed that the mRNA relative transcription levels of IL-6, TNF-α, caspase-8, PI3K, Akt and NF-κB were 1.057 ± 0.363, 1.020 ± 0.217, 1.004 ± 0.097, 1.000 ± 0.031, 1.035 ± 0.312 and 1.029 ± 0.304 in the control group, 2.013 ± 0.514, 2.189 ± 0.194, 6.433 ± 0.340, 1.594 ± 0.117, 2.902 ± 0.181 and 1.342 ± 0.146 in sensitized group, 1.243 ± 0.279, 1.268 ± 0.225, 0.869 ± 0.172, 1.103 ± 0.180, 1.371 ± 0.199 and 1.008 ± 0.202 in the blocker treatment group and 1.223 ± 0.358, 0.970 ± 0.303, 0.932 ± 0.298, 0.825 ± 0.404, 1.421 ± 0.137 and 1.083 ± 0.222 in the blocker prevention group, respectively. The mRNA relative transcription levels in the sensitized group were higher than the control group (t = 3.481, 2.759, 37.640, 2.237, 12.670, 2.274, all P < 0.05). The mRNA relative transcription levels in the blocker treatment group and blocker prevention group were lower than those in the sensitized group (t = 3.221, 7.593, 35.240, 5.610, 13.920, 3.287; 3.088, 8.299, 28.610, 4.475, 15.930, 2.390, all P < 0.05). Western blotting results showed that the protein relative expression levels of PI3K, Akt and NF-κB were 0.516 ± 0.075, 0.638 ± 0.103 and 0.198 ± 0.086 in the control group, 0.831 ± 0.061, 0.917 ± 0.069 and 0.784 ± 0.120 in sensitized group, 0.535 ± 0.108, 0.612 ± 0.206 and 0.247 ± 0.145 in the blocker treatment group and 0.526 ± 0.117, 0.565 ± 0.087 and 0.154 ± 0.031 in the blocker prevention group, respectively. The protein relative expression levels in the sensitized group were higher than the control group (t = 5.650, 3.901, 6.871, all P < 0.05). The protein relative expression levels in the blocker treatment group and blocker prevention group were lower than those in the sensitized group (t = 4.142, 2.434, 4.945; 4.013, 5.477, 8.821, all P < 0.05). Conclusion IL-1β receptor blocker may reduce the pulmonary inflammatory response through inhibiting PI3K/Akt/NF-κB pathway in the allergic reaction induced by E. granulosus cyst fluid, implying its therapeutic effects on lung injury.

Key words: Echinococcus granulosus, Cyst fluid sensitization, IL-1β receptor blocker, Treatment of lung injury