Co-Therapy of Albendazole and Dexamethasone Reduces Pathological Changes in the Cerebral Parenchyma of Th-1 and Th-2 Dominant Mice Heavily Infected with Angiostrongylus cantonensis: Histopathological and RNA-seq Analyses

Benzaldehyde stimulates autophagy via the sonic hedgehog signaling pathway in mouse brain astrocytes after treatment with Angiostrongylus cantonensis excretory-secretory products

Autophagy is a vital cellular process responsible for digesting various cytoplasmic organelles. This process plays a crucial role in maintaining cell survival and homeostasis, especially under conditions that cause nutrient deficiency, cellular damage, and oxidative stress. Neuroangiostrongyliasis is an infection caused by the parasitic nematode Angiostrongylus cantonensis and is considered as an emerging disease in many parts of the world. However, effective therapeutic strategies for neuroangiostrongyliasis still need to be further developed. In this study, we investigated the effects of benzaldehyde treatment on autophagy and sonic hedgehog (Shh) signaling in A. cantonensis-infected mice and its mechanisms. First, we found autophagosome generation in the central nervous system after A. cantonensis infection. Next, benzaldehyde combined with albendazole treatment reduced eosinophilic meningitis and upregulated the expression of Shh signaling- and autophagy-related molecules in A. cantonensis-infected mouse brains. In vitro experiments demonstrated that benzaldehyde could induce autophagy via the Shh signaling pathway in A. cantonensis excretory-secretory products (ESPs)-treated mouse astrocytes. Finally, benzaldehyde treatment also decreased lipid droplet accumulation and increased cholesterol production by activating the Shh pathway after ESPs treatment. In conclusion, these findings suggested that benzaldehyde treatment could alleviate brain damage by stimulating autophagy generation through the Shh signaling pathway.

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.

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.

The therapeutic effect of tanshinone IIA in mouse astrocytes after treatment with Angiostrongylus cantonensis fifth-stage larval excretory-secretory products

BACKGROUND

Angiostrongylus cantonensis is an important food-borne zoonotic parasite that causes eosinophilic meningitis and meningoencephalitis in humans. Excretory-secretory products (ESPs) are valuable targets for studying host-parasite relationships. ESPs are composed of a variety of molecules that are used to penetrate defensive barriers and avoid immune attack of the host. Tanshinone IIA (TSIIA) is a vasoactive cardioprotective drug that is widely used in studies evaluating potential therapeutic mechanisms. In this study, we will evaluate the therapeutic effects of TSIIA in mouse astrocytes after A. cantonensis fifth-stage larvae (L5) ESPs treatment.

METHODS

Here, we examined the therapeutic effect of TSIIA by real-time qPCR, western blotting, activity assay, and cell viability assays.

RESULTS

First, the results showed that TSIIA can elevate cell viability in astrocytes after stimulation with ESPs. On the other hand, TSIIA downregulated the expression of apoptosis-related molecules. However, the expression of molecules related to antioxidant, autophagy, and endoplasmic reticulum stress was significantly increased. The results of antioxidant activation assays showed that the activities of superoxide dismutase (SOD), glutathione S-transferase (GST), and catalase were significantly increased. Finally, we found that cell apoptosis and oxidative stress were reduced in TSIIA-treated astrocytes by immunofluorescence staining.

CONCLUSION

The findings from this study suggest that TSIIA can reduce cellular damage caused by A. cantonensis L5 ESPs in astrocytes and clarify the related molecular mechanisms.

The Global Spread Pattern of Rat Lungworm Based on Mitochondrial Genetics

Eosinophilic meningitis due to rat lungworm, Angiostrongylus cantonensis, is a global public health concern. Human cases and outbreaks have occurred in the new endemic areas, including South America and Spain. The growing genetic data of A. cantonensis provides a unique opportunity to explore the global spread pattern of the parasite. Eight more mitochondrial (mt) genomes were sequenced by the present study. The phylogeny of A. cantonensis by Bayesian inference showed six clades (I-VI) determined by network analysis. A total of 554 mt genomes or fragments, which represented 1472 specimens of rat lungworms globally, were used in the present study. We characterized the gene types by mapping a variety of mt gene fragments to the known complete mt genomes. Six more clades (I2, II2, III2, V2, VII and VIII) were determined by network analysis in the phylogenies of cox1 and cytb genes. The global distribution of gene types was visualized. It was found that the haplotype diversity of A. cantonensis in Southeast and East Asia was significantly higher than that in other regions. The majority (78/81) of samples beyond Southeast and East Asia belongs to Clade II. The new world showed a higher diversity of Clade II in contrast with the Pacific. We speculate that rat lungworm was introduced from Southeast Asia rather than the Pacific. Therefore, systematic research should be conducted on rat lungworm at a global level in order to reveal the scenarios of spread.

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

Angiostrongylus cantonensis, the causative agent of human eosinophilic meningitis and eosinophilic meningoencepalitis, has been reported to cause cognitive impairments in the host. To determine whether drug treatment improves the cognitive functions, BALB/c mice infected with 50 third-stage larvae were treated with albendazole, dexamethasone, or co-therapy since day 7 or 14 post-infection for one or two weeks. Abilities of spatial memory and learning of these animals were assessed with the Morris water maze. Our results showed that body weight was significant higher then infected group in the albendazole and combined therapy groups. Significantly lower worm recovery rates were found in mice treated with the same groups. The mice treated with dexamethasone since day 7 for 14 day had significant longer time in the remaining groups were found in forced swimming test. The animals treated with albendazole and combined therapy since day 7 for 14 days was demonstrated to have significantly shorter latencies to the platform in learning memory on day 3 and 4. Mice in these two groups were demonstrated to have significantly higher sores in spatial memory tests. These results indicate that treatment with albendazole or combined therapy may be more efficient in preventing brain damages and depression as well as preserving their capabilities in learning and memory. Therefore, administration of albendazole alone or combined with dexamethasone should have higher efficacies than dexamethasone alone in treatment of BALB/c mice infected with a heavy dose of 50 third-stage larvae of A. cantonensis.

Synaptic loss and progression in mice infected with Angiostrongylus cantonensis in the early stage

Background

Angiostrongylus cantonensis is also known as rat lungworm. Infection with this parasite is a zoonosis that can cause eosinophilic meningitis and/or eosinophilic meningoencephalitis in humans and may lead to fatal outcomes in severe cases. In this study, we explored the mechanisms of the impairments in the cognitive functions of mice infected with A. cantonensis.

Methods

In infected mice with different infective intensities at different timepoint postinfection, loss and recovery of cognitive functions such as learning and memory abilities were determined. Neuronal death and damage to synaptic structures were analyzed by Western blotting and IHC in infected mice with different infection intensities at different timepoint postinfection.

Results

The results of behavioral tests, pathological examinations, and Golgi staining showed that nerve damage caused by infection in mice occurred earlier than pathological changes of the brain. BDNF was expressed on 14 day post-infection. Cleaved caspase-3 increased significantly in the late stage of infection. However, IHC on NeuN indicated that no significant changes in the number of neurons were found between the infected and uninfected groups.

Conclusions

The synaptic loss caused by the infection of A. cantonensis provides a possible explanation for the impairment of cognitive functions in mice. The loss of cognitive functions may occur before severe immunological and pathological changes in the infected host.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02436-8.

Benzaldehyde Attenuates the Fifth Stage Larval Excretory–Secretory Product of Angiostrongylus cantonensis-Induced Injury in Mouse Astrocytes via Regulation of Endoplasmic Reticulum Stress and Oxidative Stress

Excretory–secretory products (ESPs) are the main research targets for investigating the hosts and helminths interaction. Parasitic worms can migrate to parasitic sites and avoid the host immune response by secreting this product. Angiostrongylus cantonensis is an important food-borne zoonotic parasite that causes severe neuropathological damage and symptoms, including eosinophilic meningitis or meningoencephalitis in humans. Benzaldehydes are organic compounds composed of a benzene ring and formyl substituents. This compound has anti-inflammatory and antioxidation properties. Previous studies showed that 3-hydroxybenzaldehyde (3-HBA) and 4-hydroxybenzaldehyde (4-HBA) can reduce apoptosis in A. cantonensis ESP-treated astrocytes. These results on the protective effect underlying benzaldehyde have primarily focused on cell survival. The study was designed to investigate the molecular mechanisms of endoplasmic reticulum stress (ER stress) and oxidative stress in astrocytes in A. cantonensis ESP-treated astrocytes and to evaluate the therapeutic consequent of 3-HBA and 4-HBA. First, we initially established the RNA-seq dataset in each group, including normal, ESPs, ESPs + 3-HBA, and ESPs + 4-HBA. We also found that benzaldehyde (3-HBA and 4-HBA) can stimulate astrocytes to express ER stress-related molecules after ESP treatment. The level of oxidative stress could also be decreased in astrocytes by elevating antioxidant activity and reducing ROS generation. These results suggested that benzaldehyde may be a potential therapeutic compound for human angiostrongyliasis to support brain cell survival by inducing the expression levels of ER stress- and oxidative stress-related pathways.