Regulation of non-specific immunity induced by Trichinella spiralis to immune response in small intestinal tissue of Plasmodium berghei ANKA infected mice / 中华地方病学杂志

ABSTRACT

Objective:To investigate the regulatory effect of non-specific immunity induced by Trichinella spiralis (Ts) on the immune response of small intestinal tissue of mice infected with Plasmodium berghei (Pb)ANKA. Methods:Thirty-six specific pathogen free female Kunming mice (6-8 weeks old, weighting 18-22 g) were randomly divided into 4 groups according to body weight by the random number table method, including control group, Ts-mono-infected group (Ts group), PbANKA-mono-infected group (Pb group), and Ts + Pb-co-infected group (Ts + Pb group), 9 mice in each group. The mice were fed normal food, water and normal feed. The control group was not given any experimental treatment; the Ts group was infected with 20 Ts larvae orally on the first day of the experiment; the Pb group was infected with 1 × 10 6 PbANKA erythrocytes by intraperitoneal injection on the 9th day of the experiment; the Ts + Pb group was infected with 20 Ts larvae orally on the first day of the experiment, and 1 × 10 6 PbANKA erythrocytes were given by intraperitoneal injection on the 9th day. Mice were sacrificed on 22th day after Ts infection and/or 13th day after PbANKA infection, the morphological changes of peritoneal macrophages in each group were observed by transmission electron microscope; the mRNA expression levels of M1-type macrophage markers [inducible nitric oxide synthase (iNOS) and interleukin-6 (IL-6)], M2-type macrophage markers [mannose receptor C type 2 (Mrc-2) and chitinase-like 3 (Ym1)] in the small intestinal tissue of mice in each group were detected by quantitative real-time PCR (qRT-PCR), and the ratios of mRNA expression levels of M2/M1 macrophage markers were compared. Results:Transmission electron microscope showed that the morphology and structure of peritoneal macrophages in the control were normal; more pseudopodia were observed in the peritoneal macrophages in Ts group; and more pseudopodia and engulfed Plasmodium parasites were observed in the peritoneal macrophages in Pb group and Ts + Pb group. The iNOS (1.000 ± 0.290, 1.277 ± 0.251, 3.088 ± 1.110, 2.604 ± 0.773) and IL-6 mRNA expression levels (1.000 ± 0.393, 2.180 ± 0.629, 1.650 ± 0.612, 3.242 ± 1.780) of small intestinal tissue were compared among the 4 groups, the differences were statistically significant ( F=12.420, 5.270, P < 0.05). Compared with the control group, the iNOS mRNA expression levels in the Pb and Ts + Pb groups were significantly increased ( P < 0.05); compared with the Ts group, the iNOS mRNA expression level in the Ts + Pb group was significantly increased ( P < 0.05). Compared with the control group, the IL-6 mRNA expression level in the Ts + Pb group was significantly increased ( P < 0.05). The mRNA expression levels of Mrc-2 and Ym1 of small intestinal tissue in the 4 groups were significantly different ( F=9.890, 20.500, P < 0.05). The Mrc-2 mRNA expression level in the Ts + Pb group was significantly higher than those in the control, Ts, and Pb groups ( P < 0.05). The Ym1 mRNA expression level in the Pb group was significantly higher than that in the control group ( P < 0.05); the Ym1 mRNA expression level in the Ts + Pb group was significantly higher than those in the control, Ts, and Pb groups ( P < 0.05). The Mrc-2/iNOS, Ym1/iNOS of small intestinal tissue in the 4 groups were significantly different ( F=3.642, 22.360, P < 0.05). The Mrc-2/iNOS in the Ts + Pb group was significantly higher than those in the control and Pb groups ( P < 0.05). The Ym1/iNOS in the Ts + Pb group was higher than those in the control, Ts, and Pb groups ( P < 0.05). Conclusion:The non-specific immunity induced by Ts infection is involved in the regulation of intestinal immune response of mice infected with PbANKA, which may promote M2 polarization of macrophages in the small intestinal tissue.