Calycosin attenuates Angiostrongylus cantonensis-induced parasitic meningitis through modulation of HO-1 and NF- κ B activation

Abstract

Angiostrongylus cantonensis causes a form of parasitic meningitis in humans. Albendazole (ABZ) kills nematode larvae in the brain. However, dead larvae can trigger a severe inflammatory response, resulting in brain damage. Accumulating evidence suggests that calycosin represents a potential anti-inflammatory therapeutic candidate. In this study, we investigated the combined effects of ABZ and calycosin in angiostrongyliasis caused by A. cantonensis in BALB/c mice. Inflammatory mediators (such as phospho-nuclear factor-κB, cyclooxygenase-2, matrix metalloproteinase-9, tumour necrosis factor-α and interleukin-1β) are associated with the development of meningitis and immune inflammatory reactions. We found that A. cantonensis significantly induces inflammatory mediator production and increases the blood–brain barrier (BBB) permeability. However, co-administration of both ABZ and calycosin markedly suppressed meningitis and inflammatory mediator production and decreased the BBB permeability compared to treatment with a single drug. Furthermore, calycosin and ABZ plus calycosin treatment facilitated production of the antioxidant haem oxygenase-1 (HO-1). Moreover, co-therapy with ABZ and calycosin failed to mitigate angiostrongyliasis in the presence of tin-protoporphyrin IX, an HO-1-specific inhibitor. This finding suggests that the beneficial effects of ABZ plus calycosin treatment on the regulation of inflammation are mediated by the modulation of HO-1 activation. The present results provide new insights into the treatment of human angiostrongyliasis using co-therapy with ABZ and calycosin.

Keywords: Angiostrongylus cantonensis; HO-1; anti-inflammation; calycosin; eosinophilic meningitis.

Graphical abstract

Fig. 1.

Protein levels of p-NF-κB, MMP-9, COX-2 and HO-1 in the brains of mice infected with Angiostrongylus cantonensis. (A) p-NF-κB, MMP-9, COX-2 and HO-1 bands were detected at all time points. (B) *P < 0.05 and **P < 0.01 vs day 0 group. Data are presented as mean ± s.d. of 3 independent experiments.

Fig. 2.

Protein levels of p-NF-κB, MMP-9, COX-2 and HO-1 in the brain of mice. (A) p-NF-κB, MMP-9, COX-2 and HO-1 bands were detected for all treatment groups. (B) *P < 0.05 and **P < 0.01 indicate the significant difference. Data are presented as mean ± s.d. of 3 independent experiments. Ctrl, control group; Infected, A. cantonensis infection group; ABZ, albendazole treatment group; Caly, calycosin treatment group; ABZ + Caly, albendazole combined with calycosin treatment group.

Fig. 3.

Levels of larval recovery, Evans blue, TNF-α and IL-1β. Larval recovery (A), Evans blue (B), TNF-α (C) and IL-1β (D) were detected in all treatment groups. *P < 0.05, **P < 0.01 and ***P < 0.001 indicate the significant difference. Data are presented as mean ± s.d. of 3 independent experiments. Ctrl, control group; Infected, A. cantonensis infection group; ABZ, albendazole treatment group; Caly, calycosin treatment group; ABZ + Caly, albendazole combined with calycosin treatment group.

Fig. 4.

Protein levels of p-NF-κB, MMP-9, COX-2 and HO-1 in the brain of mice. (A) p-NF-κB, MMP-9, COX-2 and HO-1 bands were detected for all treatment groups. (B) *P < 0.05 and **P < 0.01 indicate the significant difference. Data are presented as mean ± s.d. of 3 independent experiments. Ctrl, control group; Infected, A. cantonensis infection group; ABZ + Caly, albendazole combined with calycosin treatment group; SnPPIX + ABZ + Caly, SnPPIX and albendazole combined with calycosin treatment group.

Fig. 5.

Levels of larval recovery, Evans blue, TNF-α and IL-1β. Larval recovery (A), Evans blue (B), TNF-α (C) and IL-1β (D) were detected for all treatment groups. *P < 0.05 and **P < 0.01 indicate the significant difference. Data are presented as mean ± s.d. of 3 independent experiments. Ctrl, control group; Infected, A. cantonensis infection group; ABZ, albendazole treatment group; Caly, calycosin treatment group; ABZ + Caly, albendazole combined with calycosin treatment group.

Fig. 6.

Pathological morphology of the subarachnoid space in mice evaluated using haematoxylin and eosin staining. (A) Control group (Ctrl). (B) Angiostrongylus cantonensis infection group (Infected). (C) Albendazole treatment group (ABZ). (D) Calycosin treatment group (Caly). (E) Albendazole combined with calycosin treatment group (ABZ + Caly). (F) SnPPIX and albendazole combined with calycosin treatment group (SnPPIX + ABZ + Caly).