Improvements of cognitive functions in mice heavily infected by Angiostrongylus cantonensis after treatment with albendazole, dexamethasone, or co-therapy

Upregulation of Nrf2 attenuates Angiostrongylus cantonensis-induced parasitic meningitis in mice

BACKGROUND

Angiostrongylus cantonensis is a food-borne parasite that can infect mammals, including humans, causing angiostrongyliasis. The nuclear factor E2-related factor 2 (Nrf2) is a transcription factor that plays a crucial role in the host's antioxidant defense and inflammation mechanisms. Herein, this study investigates the anti-inflammatory effects of Nrf2 in A. cantonensis-induced parasitic meningitis in mice.

METHODS

We used animal infection and treatment, larvae collection, western blotting, enzyme-linked immunosorbent assay (ELISA), hematoxylin and eosin (H&E) stain, blood-brain barrier (BBB) permeability assays, and an NAD(P)H quinone dehydrogenase 1 (NQO1) enzyme activity, reactive oxygen species (ROS), and superoxide dismutase (SOD) assay kit in this study.

RESULTS

Our findings revealed that larvae recovery, BBB permeability, and inflammatory mediators (interleukin (IL)-1β, IL-6, IL-17A, and tumor necrosis factor (TNF)-α) were increased in A. cantonensis-infected mice. However, p-Nrf2 levels were slightly increased in infected groups. To better understand the modulatory role of Nrf2 in the parasitic meningitis, we also treated A. cantonensis-infected mice with oltipraz (an Nrf2 activator) and trigonelline (an Nrf2 inhibitor). The larvae recovery, BBB permeability, and levels of inflammatory mediators were significantly decreased in the albendazole alone, oltipraz, and albendazole-oltipraz co-treatment groups, particularly in albendazole-oltipraz co-treatment groups. In contrast, trigonelline treatment resulted in increased levels of larvae recovery, BBB permeability, and inflammatory mediators. Moreover, since Nrf2 is involved in the regulation of antioxidant enzymes, we also examined the expression of ROS, NQO1, and SOD. ROS levels were significantly increased in infected groups but decreased in the albendazole alone, oltipraz alone, and albendazole-oltipraz co-treatment groups. NQO1 and SOD levels were significantly decreased in infected groups, but these levels were notably restored during treatment with albendazole alone, oltipraz alone, and albendazole-oltipraz co-treatment.

CONCLUSIONS

Our findings revealed the albendazole-Nrf2 activator co-treatment effectively suppressed excessive inflammation compared with the anthelmintics drug (albendazole) treatment alone, and Nrf2 activation might produce a synergistic effect in the inflammatory response of the brain in mice with angiostrongyliasis.

Doxycycline cotherapy with albendazole relieves neural function damage in C57BL/6 and BALB/c mice infected with Angiostrongylus cantonensis

BACKGROUND

We investigated the effects of combination therapy albendazole and doxycycline in Angiostrongylus cantonensis-infected mice during early and late treatment.

MATERIALS AND METHODS

C57BL/6 and BALB/c mice were divided into five groups: (i) uninfected, (ii) infected with A. cantonensis, (iii) infected + 10 mg/kg albendazole, (iv) infected + 25 mg/kg doxycycline, and (v) infected + 10 mg/kg albendazole + 25 mg/kg doxycycline. We administered drugs in both early treatments started at 7-day post infections (dpi) and late treatments (14 dpi) to A. cantonensis-infected C57BL/6 and BALB/c mice. To assess the impact of these treatments, we employed the Morris water maze test to evaluate spatial learning and memory abilities, and the rotarod test to measure motor coordination and balance in C57BL/6 mice. Additionally, we monitored the expression of the cytokine IL-33 and GFAP in the brain of these mice using Western blot analysis.

RESULTS

In this study, A. cantonensis infection was observed to cause extensive cerebral angiostrongyliasis in C57BL/6 mice. This condition significantly affected their spatial learning and memory abilities, as assessed by the Morris water maze test, as well as their motor coordination, which was evaluated using the rotarod test. Early treatment with albendazole led to favorable recovery outcomes. Both C57BL/6 and BALB/c mice express IL-33 and GFAP after co-therapy. The differences of levels and patterns of IL-33 and GFAP expression in mice may be influenced by the balance between pro-inflammatory and anti-inflammatory signals within the immune system.

CONCLUSIONS

Combination therapy with anthelmintics and antibiotics in the early stage of A. cantonensis infection, in C57BL/6 and BALB/c mice resulted in the death of parasites in the brain and reduced the subsequent neural function damage and slowed brain damage and neurobehavior impairment. This study suggests a more effective and novel treatment, and drug delivery method for brain lesions that can decrease the neurological damage of angiostrongyliasis patients.

In vivo screening of flavonoid compounds revealed quercetin as a potential drug to improve recovery of angiostrongyliasis after albendazole treatment

Human angiostrongyliasis, caused by consuming the larva stage of Angiostrongylus cantonensis, is an infectious disease involving the central nervous system (CNS) and ophthalmic system. Current treatment of angiostrongyliasis involves albendazole accompanied by analgesics and corticosteroids. However, long-term use of corticosteroids may lead to significant adverse effects. In the current study, we screened through different potentially effective flavonoid compounds and identified quercetin as an effective anti-inflammatory agent in an angiostrongyliasis mouse model. Our results identified that quercetin may reverse the neurological defects in mice with angiostrongyliasis. The brain pathology and inflammatory status were also improved by albendazole-quercetin co-therapy. Further analysis showed that albendazole-quercetin co-therapy had a better therapeutic effect than albendazole or quercetin monotherapy. This therapeutic effect was achieved by inhibiting the brain inflammasome activation and apoptosis. Albendazole-quercetin co-therapy also leads to the inhibition of brain IL-5, possibly leading to improved pathology. Our results here proved that quercetin may serve as a potential adjuvant drug in treating human angiostrongyliasis.

Ubenimex combined with Albendazole for the treatment of Echinococcus multilocularis-induced alveolar echinococcosis in mice

Introduction

Alveolar echinococcosis (AE) is a parasitic disease caused by E. multilocularis metacestodes and it is highly prevalent in the northern hemisphere. We have previously found that vaccination with E. multilocularis-Leucine aminopeptidase (EM-LAP) could inhibit the growth and invasion of E. multilocularis in host liver, and Ubenimex, a broad-spectrum inhibitor of LAP, could also inhibit E. multilocularis invasion but had a limited effect on the growth and development of E. multilocularis.

Methods

In this study, the therapeutic effect of Ubenimex combined with Albendazole on AE was evaluated. Mice were intraperitoneally injected with protoscoleces and imaging examination was performed at week 8 and week 16 to detect cyst change. During this period, mice were intraperitoneally injected with Ubenimex and intragastrically administered with Albendazole suspension. At last, the therapeutic effect was evaluated by morphological and pathological examination and liver function.

Results

The results revealed that the combined treatment could inhibit the growth and infiltration of cysts in BALB/c mice infected with E. multilocularis protoscoleces. The weight, number, invasion and fibrosis of cysts were reduced in mice treated with Ubenimex in combination with Albendazole. The same effect was achieved by the single Ubenimex treatment because of its inhibitory effect on LAP activity, but it was less effective in inhibiting the growth of cysts. The levels of ALT, AST, TBIL, DBIL, ALP, and γ-GT were reduced after the combined treatment, indicating that treatment with both Ubenimex and Albendazole could alleviate liver damage.

Discussion

This study suggests that the combined treatment with Ubenimex and Albendazole could be a potential therapeutic strategy for E. multilocularis infections.

Protective effect of benzaldehyde combined with albendazole against brain injury induced by Angiostrongylus cantonensis infection in mice

Angiostrongylus cantonensis, also known as rat lungworm, is an important food-borne zoonotic parasite that causes severe neuropathological damage and symptoms, including eosinophilic meningitis and eosinophilic meningoencephalitis, in humans. At present, the therapeutic strategy for cerebral angiostrongyliasis remains controversial. Benzaldehyde, an important bioactive constituent of Gastrodia elata (Tianma), reduces oxidative stress by inhibiting the production of reactive oxygen species. This study aimed to evaluate the therapeutic effect of benzaldehyde in combination with albendazole on angiostrongyliasis in animal models. First, the data from body weight monitoring and behavioural analyses demonstrated that benzaldehyde improved body weight and cognitive function changes after A. cantonensis infection. Next, blood‒brain barrier breakdown and pathological changes were reduced after benzaldehyde and albendazole treatment in BALB/c mice infected with A. cantonensis. Subsequently, four RNA-seq datasets were established from mouse brains that had undergone different treatments: normal, infection, infection + albendazole, and infection + albendazole + 3-hydroxybenzaldehyde groups. Ultimately, benzaldehyde was found to regulate cell apoptosis, oxidative stress and Sonic Hedgehog signalling in mouse brains infected with A. cantonensis. This study evaluated the therapeutic effect of benzaldehyde on angiostrongyliasis, and provided a potential therapeutic strategy for human angiostrongyliasis in the clinical setting. Moreover, the molecular mechanism of benzaldehyde in mouse brains infected with A. cantonensis was elucidated.

CEBPα/miR-101b-3p promotes meningoencephalitis in mice infected with Angiostrongylus cantonensis by promoting microglial pyroptosis

BACKGROUND

Angiostrongylus cantonensis (A. cantonensis) infection can induce acute inflammation, which causes meningoencephalitis and tissue mechanical injury to the brain. Parasite infection-induced microRNAs play important roles in anti-parasite immunity in non-permissive hosts. miR-101b-3p is highly expressed after A. cantonensis infection; however, the role of miR-101b-3p and the transcription regulation of miR-101b-3p in A. cantonensis infection remain poorly characterized.

RESULTS

In the present study, we found that miR-101b-3p inhibition alleviated inflammation infiltration and pyroptosis in A. cantonensis infection. In addition, we found that CCAAT/enhancer-binding protein alpha (CEBPα) directly bound to the - 6-k to - 3.5-k region upstream of miR-101b, and CEBPα activated miR-101b-3p expression in microglia. These data suggest the existence of a novel CEBPα/miR-101b-3p/pyroptosis pathway in A. cantonensis infection. Further investigation verified that CEBPα promotes pyroptosis by activating miR-101b-3p expression in microglia, and microglial pyroptosis further promoted inflammation.

CONCLUSIONS

Our results suggest that a CEBPα/miR-101b-3p/pyroptosis pathway may contribute to A. cantonensis infection-induced inflammation and highlight the pro-inflammatory effect of miR-101b-3p. Video Abstract.