Impact of gender on hepatic pathology and antibody - mediated immunity caused by Schistosoma japonicum infection in C57BL/6 mice / 中国血吸虫病防治杂志

ABSTRACT

Objective To investigate the effect of gender on hepatic pathology and antibody-mediated immunity in Schistosoma japonicum-infected C57BL/6 mice. Methods Female and male C57BL/6 mice were infected with S. japonicum, and the hepatic pathological changes were observed using HE and picrosirius red staining in mice 8 weeks post-infection. The serum specific IgG antibody levels against the soluble adult worm antigen (SWA) and soluble egg antigen (SEA) were measured in mice using enzyme-linked immunosorbent assay (ELISA), and the percentages of follicular helper T (Tfh) cells and regulatory T (Treg) cells were detected in mouse spleen and lymph nodes using flow cytometry. Results HE staining showed no significant difference in the mean area of a single hepatic egg granuloma between female and male mice 8 weeks post-infection with S. japonicum [(28.050 ± 3.576) × 104 μm2 vs. (26.740 ± 4.093) × 104 μm2; t = 0.241, P = 0.821], and picrosirius red staining revealed no statistical differences between female and male mice in terms of the mean proportion of picrosirius red stained hepatic tissues [(7.667 ± 1.856)% vs. (7.667 ± 1.764)%; t = 0, P = 1] or the mean optical density [(0.023 ± 0.003) vs. (0.027 ± 0.007); t = 0.447, P = 0.678]. ELISA detected no significant differences in the serum IgG antibody levels against SWA [(2.098 ± 0.037) vs. (1.970 ± 0.071); t = 1.595, P = 0.162] or SEA [(3.738 ± 0.039) vs. (3.708 ± 0.043); t = 0.512, P = 0.623] between female and male mice 8 weeks post-infection with S. japonicum. Flow cytometry detected significantly greater percentages of Tfh cells in the spleen [female mice, (8.645 ± 1.356)% vs. (1.730 ± 0.181)%, t = 5.055, P = 0.002; male mice, (8.470 ± 1.161)% vs. (1.583 ± 0.218)%, t = 5.829, P = 0.001] and lymph nodes [female mice, (3.218 ± 0.153)% vs. (1.095 ± 0.116)%, t = 11.040, P < 0.001; male mice, (3.673 ± 0.347)% vs. (0.935 ± 0.075)%, t = 8.994, P = 0.001) of both female and male mice 8 weeks post-infection with S. japonicum than in uninfected mice; however, no significant differences were seen between female and male mice 8 weeks post-infection with S. japonicum in terms of the percentages of Tfh cells in the spleen [(8.645 ± 1.356)% vs. (8.470 ± 1.161)%; t = 0.098, P = 0.925] or lymph nodes [(3.218 ± 0.153)% vs. (3.673 ± 0.347)%; t = 1.332, P = 0.241]. There was no significant difference in the proportion of Treg cells in the spleen of male mice between infected and uninfected mice [(10.060 ± 0.361)% vs. (10.130 ± 0.142)%; t = 0.174, P = 0.867], while a higher proportion of Treg cells was seen in the spleen of female mice 8 weeks post-infection with S. japonicum than in uninfected mice [(10.530 ± 0.242)% vs. (9.450 ± 0.263)%; t = 3.021, P = 0.023]. There was no significant difference in the proportion of Treg cells in the spleen between female and male mice infected with S. japonicum [(10.530 ± 0.242)% vs. (10.060 ± 0.361)%; t =1.077, P = 0.323]. In addition, the proportions of Treg cells were significantly greater in the lymph node of S. japonicum -infected female [(17.150 ± 0.805)% vs. (13.100 ± 0.265)%; t = 4.781, P = 0.003] and male mice [(18.550 ± 0.732)% vs. (12.630 ± 0.566)%; t = 6.402, P = 0.001] than in uninfected mice; however, no significant difference was seen between female and male mice 8 weeks post-infection [(17.150 ± 0.805)% vs. (18.550 ± 0.732)%; t = 1.287, P = 0.246]. Conclusion There are no gender-specific hepatic pathological changes or antibody-mediated immunity in C57BL/6 mice post-infection with S. japonicum.