Objective To investigate the effect of Echinococcus multilocularis protoscoleces infection on lymphocytes and their subpopulations in livers and spleens of C57BL/6 mice. Methods Thirty-two C57BL/6 mice were randomly assigned into four groups of eight animals each: control group, low-dosage group (50 protoscoleces/mouse), mid-dosage group (500 protoscoleces/mouse) and high-dosage group (2 000 protoscoleces/mouse). The mice received portal vein injection of 200 μl protoscolex suspension or normal saline. Four weeks after infection, four mice in each group were euthanized to collect liver tissues for histopathological observation with routine Masson staining, while the other four mice were euthanized for orbital blood collection and liver and spleen cell suspension preparation. The numbers of CD3+ T cells, B cells, NK cells, NKT cells, CD4+ T cells, CD8+ T cells, CD4+CD69+ T cells, and CD8+CD69+ T cells, as well as the percentages of naive CD4+ T cells (CD4+ Tn), effector memory CD4+ T cells (CD4+ Tem), naive CD8+ T cells (CD8+ Tn), effector memory CD8+ T cells (CD8+ Tem) and central memory CD8+ T cells (CD8+ Tcm) were detected by flow cytometry (FCM). The FCM data were analyzed with Flow-Jo software. Statistical analysis was performed using Graphad Prism 7.0 software. Results Four weeks after infection, there were no significant changes in the livers of the control mice. Both the low- and mid-dosage groups showed weakening of acute inflammatory cell infiltration in liver tissues, and some lesions had gradually transformed to the fibrotic repair stage, with formation of small granulomatous nodules and appearance of penctate or focal necrosis. In the high-dosage group, small vesicles were seen in the liver. Germinal layers were observed, accompanied by intensive inflammatory cell infiltration. The numbers of CD3+ T cells in mouse liver in the high-, mid- and low-dosage groups and the control group were (4.10 ± 0.04) × 105, (3.81 ± 0.14) × 105, (3.02 ± 0.12) × 105, and (2.98 ± 0.03) × 105, respectively, with that in the high-dosage group being significantly higher than the other 3 groups (P < 0.05 or 0.01). The numbers of CD3+ T cells in mouse spleen in the high-, mid- and low-dosage groups and the control group were (16.01 ± 0.40) × 105, (11.03 ± 1.21) × 105, (10.10 ± 1.01) × 105, and (9.71 ± 0.90) × 105, respectively (P < 0.01), with that in the high-dosage group being significantly higher than the other 3 groups (P < 0.01). The high-dosage group also had significantly higher numbers of CD4+ T cells and CD8+ T cells in livers as well as B cells and CD8+ T cells in spleens, compared with other groups (P < 0.05 or P < 0.01). The numbers of CD4+CD69+ T cells in mouse liver in the high-, mid- and low-dosage groups and the control group were (3.23 ± 0.10) × 104, (1.98 ± 0.11) × 104, (1.51 ± 0.26) × 104, and (1.19 ± 0.21) × 104, respectively, with that in the high-dosage group being significantly higher than the other groups (P < 0.05). The respective numbers of CD4+CD69+ T cells in mouse spleen in the high-, mid- and low-dosage groups and the control group were (10.10 ± 0.41) × 104, (8.91 ± 0.80) × 104, (8.20 ± 0.41) × 104, and (6.81 ± 0.50) × 104, with that in the high-dosage group being significantly higher than the other groups (P < 0.01). The high-dosage group also had significantly higher numbers of CD8+CD69+ T cells in livers and spleens, compared with other groups (P < 0.05 or P < 0.01). The percentages of CD4+ Tn in mouse liver in the high-, mid- and low-dosage groups and the control group were (15.52 ± 1.51)%, (19.3 ± 2.09)%, (20.66 ± 1.28)%, and (23.62 ± 2.84)% respectively, with that in the control group being significantly higher than the other groups (P < 0.05 or P < 0.01). The control group also had significantly higher percentages of CD8+ Tn cells in livers and spleens, compared with other groups (P < 0.05 or P < 0.01). The high-dosage group had significantly higher percentages of CD8+ Tcm cells in livers and spleens, compared with other groups (P < 0.05). Conclusion In C57BL/6 mice infected with high-dose E. multilocular protoscoleces, the liver T cell recruitment occurred mainly of CD4+ and CD8+ T cells, while B cell and CD8+ T cell were mainly recruited in spleen.
ZHANG Ning
,
ZHANG Chuan-shan
,
LI Zhi-de
,
LI Liang
,
WANG Hui
,
TAN Ya-chao
,
SHANG Lin-lin
,
WEN Hao
. The effects of Echinococcus multilocularis protoscoleces infection on lymphocytes and their subpopulations in mouse liver and spleen[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2020
, 38(1)
: 30
-35
.
DOI: 10.12140/j.issn.1000-7423.2020.01.005
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