Effect of β-defensin 2 gene silencing on the inflammatory response induced by Haemophilus influenzae type B combined vaccine immunization in rats

Abstract

Objective To investigate the effect of β-defensin 2 (rBD-2) silencing on the inflammatory response induced by Haemophilus influenzae type B vaccine immunization in rats. Methods A total of 144 SPF Sprague Dawley (SD) rats were divided into four groups. Group 1 were immunized with Haemophilus influenzae type B vaccine. Group 2 were immunized with Haemophilus influenzae type B vaccine and administered with lentivirus Lv-shRNA-rBD-2 by intratracheal instillation. Group 3 were administered with the lentivirus Lv-shRNA-rBD-2 by intratracheal instillation. Group 4 were blank controls. Each group was set with 12 rats. The serum was collected at 12, 24 and 72 hours after immunization, and tumor necrosis factor (TNF)-α, interleukine (IL)-1β and IL-10 were assessed by enzyme-linked immuno sorbent assay (ELISA). Expression levels of rBD-2 in lung tissues of rats were measured by western blotting. Results The recombinant virus was successfully produced by a lipofectmaine transfection method. At 12, 24, and 72 h of immunization, serum levels of TNF-α of rats in group 1 were (82.0±8.0), (155.0±18.2), and (272.0±32.5) pg/mL, respectively, which were all higher than those in group 4 ([55.0±6.2], [52.0±5.8], and [56.0±4.8] pg/mL, respectively; t=16.034, P=0.043; t=12.411, P=0.035; t=10.530, P=0.018, respectively). Serum levels of TNF-α at 12, 24, and 72 h of immunization in group 2 were (66.0±8.2), (90.0±12.6), and (108.0±13.6) pg/mL, respectively, which were all significantly lower than group 1 (t=12.115, P=0.039; t=12.830, P=0.033; t=15.522, P=0.012, respectively). At each time point, serum levels of IL-1β and IL-10 in group 1 were all significantly higher than those in group 4 (IL-1β: t=18.032, P=0.048; t=15.824, P=0.039; t=13.518, P=0.021, respectively; IL-10: t=15.410, P=0.045; t=14.294, P=0.032; t=13.375, P=0.013, respectively). Serum levels of IL-1β and IL-10 at each time points in group 2 were all significantly lower than those in group 1 (IL-1β: t=19.012, P=0.043; t=16.991, P=0.034; t=14.862, P=0.027, respectively; IL-10: t=15.134, P=0.048; t=15.264, P=0.036; t=11.408, P=0.024, respectively). Seventy-two hours after immunization of SD rats, the relative content of rBD-2 protein in lung tissue of rats significantly increased. Protein level in group 1 was significantly higher than that in group 4 (t=10.582, P=0.035), while protein level in group 2 was significantly lower than that in group 1 (t=13.250, P=0.027). Conclusions rBD-2 gene silencing can improve the inflammatory response induced by Haemophilus influenzae type B combined vaccine in rats Key words: Haemophilus influenzae type B vaccine; β-defensin 2; Inflammatory factor; Immunization; Gene silencing