Protective effect of the ω-3 polyunsaturated fatty acids on the schistosomiasis liver fibrosis in mice

Abstract

This study aims to observe the effect of ω-3 polyunsaturated fatty acids on initiation and elimination of the schistosomiasis inflammatory response and liver fibrosis. The mice infected with the cercariae of Schistosoma japonicum (20 ± cercarie per mice) were separated randomly into several groups. After 60 days, liver tissue samples of all mice were sectioned. Hematoxylin-eosin (HE) staining, Masson staining, the enzyme-linked immunosorbent assay (ELISA), and flow cytometry (FCM) were performed. Through HE and Masson staining, the size of egg (ovum) granuloma and the collagen deposited in mice's livers in ω-3 PUFAs and praziquantel mixed groups were less than that of model group and praziquantel treated group. The serum level of IL-13 and TNF-α were lower than that of model group and praziquantel treated group. The indicators of liver fibrosis, such as HA and LN in the group treated with ω-3 PUFAs and praziquantel before the release of soluble eggs antigen (SEA) into blood, were lower than that of model group and praziquantel treated group, respectively. The combined treatment of ω-3 polyunsaturated fatty acids and praziquantel conducted before the release of soluble eggs antigens into the blood decreases liver ovum granulomatous inflammation and fibrosis degree in the schistosomiasis. The mechanism of the ω-3 polyunsaturated fatty acid may be related to the adjustment of the anti-inflammatory and immune responses.

Keywords: Schistosoma japonicum; liver fibrosis; protective effect; ω-3 polyunsaturated fatty acids.

Figure 1

Histological findings for the liver tissue with HE staining and Masson staining. HE staining in (A-F), nucleus is stained with blue or purplish blue, while cytolymph, muscle fiber, and collagenous fiber are in various shades of red, respectively. Masson staining in (G-L), nucleus and collagen is stained with blue, while the cytolymph and muscle fiber are in red. Representative HE and Masson staining images for model group A (A, original magnification × 40; G, original magnification × 100), praziquantel group B (B and H, original magnification × 100), ω-3 PUFAs and praziquantel mixed groups C₁, treated before SEA release (C and I, original magnification × 100), C₂, treated during SEA release (D and J, original magnification × 100), C₃, treated after SEA release (E and K, original magnification × 100), and control group D (F and L, original magnification × 100).

Figure 2

Positive staining for α-SMA. The liver tissues were fixed and stained with anti-α-SMA antibody. Collagen deposition and the α-SMA positive area were shown here and quantified in Table 2. Representative images (original magnification × 100) for model group A (A), praziquantel group B (B), ω-3 PUFAs and praziquantel mixed groups C₁ (C), C₂ (D), C₃ (E), and control group D (F).