Preliminary expression profile of cytokines in brain tissue of BALB/c mice with Angiostrongylus cantonensis infection

Identification and coregulation pattern analysis of long noncoding RNAs in the mouse brain after Angiostrongylus cantonensis infection

BACKGROUND

Angiostrongyliasis is a highly dangerous infectious disease. Angiostrongylus cantonensis larvae migrate to the mouse brain and cause symptoms, such as brain swelling and bleeding. Noncoding RNAs (ncRNAs) are novel targets for the control of parasitic infections. However, the role of these molecules in A. cantonensis infection has not been fully clarified.

METHODS

In total, 32 BALB/c mice were randomly divided into four groups, and the infection groups were inoculated with 40 A. cantonensis larvae by gavage. Hematoxylin and eosin (H&E) staining and RNA library construction were performed on brain tissues from infected mice. Differential expression of long noncoding RNAs (lncRNAs) and mRNAs in brain tissues was identified by high-throughput sequencing. The pathways and functions of the differentially expressed lncRNAs were determined by Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses. The functions of the differentially expressed lncRNAs were further characterized by lncRNA‒microRNA (miRNA) target interactions. The potential host lncRNAs involved in larval infection of the brain were validated by quantitative real-time polymerase chain reaction (qRT‒PCR).

RESULTS

The pathological results showed that the degree of brain tissue damage increased with the duration of infection. The transcriptome results showed that 859 lncRNAs and 1895 mRNAs were differentially expressed compared with those in the control group, and several lncRNAs were highly expressed in the middle-late stages of mouse infection. GO and KEGG pathway analyses revealed that the differentially expressed target genes were enriched mainly in immune system processes and inflammatory response, among others, and several potential regulatory networks were constructed.

CONCLUSIONS

This study revealed the expression profiles of lncRNAs in the brains of mice after infection with A. cantonensis. The lncRNAs H19, F630028O10Rik, Lockd, AI662270, AU020206, and Mexis were shown to play important roles in the infection of mice with A. cantonensis infection.

Angiostrongylus cantonensis induces energy imbalance and dyskinesia in mice by reducing the expression of melanin-concentrating hormone

BACKGROUND

Infection with Angiostrongylus cantonensis (AC) in humans or mice can lead to severe eosinophilic meningitis or encephalitis, resulting in various neurological impairments. Developing effective neuroprotective drugs to improve the quality of life in affected individuals is critical.

METHODS

We conducted a Gene Ontology enrichment analysis on microarray gene expression (GSE159486) in the brains of AC-infected mice. The expression levels of melanin-concentrating hormone (MCH) were confirmed through real-time quantitative PCR (RT-qPCR) and immunofluorescence. Metabolic parameters were assessed using indirect calorimetry, and mice's energy metabolism was evaluated via pathological hematoxylin and eosin (H&E) staining, serum biochemical assays, and immunohistochemistry. Behavioral tests assessed cognitive and motor functions. Western blotting was used to measure the expression of synapse-related proteins. Mice were supplemented with MCH via nasal administration.

RESULTS

Postinfection, a marked decrease in Pmch expression and the encoded MCH was observed. Infected mice exhibited significant weight loss, extensive consumption of sugar and white fat tissue, reduced movement distance, and decreased speed, compared with the control group. Notably, nasal administration of MCH countered the energy imbalance and dyskinesia caused by AC infection, enhancing survival rates. MCH treatment also increased the expression level of postsynaptic density protein 95 (PSD95) and microtubule-associated protein-2 (MAP2), as well as upregulated transcription level of B cell leukemia/lymphoma 2 (Bcl2) in the cortex.

CONCLUSIONS

Our findings suggest that MCH improves dyskinesia by reducing loss of synaptic proteins, indicating its potential as a therapeutic agent for AC infection.

Inhibition of activin A receptor signalling attenuates age-related pathological cardiac remodelling

In the heart, ageing is associated with DNA damage, oxidative stress, fibrosis and activation of the activin signalling pathway, leading to cardiac dysfunction. The cardiac effects of activin signalling blockade in progeria are unknown. This study investigated the cardiac effects of progeria induced by attenuated levels of Ercc1, which is required for DNA excision and repair, and the impact of activin signalling blockade using a soluble activin receptor type IIB (sActRIIB). DNA damage and oxidative stress were significantly increased in Ercc1^Δ/− hearts, but were reduced by sActRIIB treatment. sActRIIB treatment improved cardiac systolic function and induced cardiomyocyte hypertrophy in Ercc1^Δ/− hearts. RNA-sequencing analysis showed that in Ercc1^Δ/− hearts, there was an increase in pro-oxidant and a decrease in antioxidant gene expression, whereas sActRIIB treatment reversed this effect. Ercc1^Δ/− hearts also expressed higher levels of anti-hypertrophic genes and decreased levels of pro-hypertrophic ones, which were also reversed by sActRIIB treatment. These results show for the first time that inhibition of activin A receptor signalling attenuates cardiac dysfunction, pathological tissue remodelling and gene expression in Ercc1-deficient mice and presents a potentially novel therapeutic target for heart diseases.

Summary: Attenuated DNA repair is associated with pathological cardiac remodelling and gene expression. Much of this phenotype is attenuated by inhibition of the activin signalling pathway using soluble activin receptor treatment.

The meningeal lymphatic vasculature in neuroinflammation

The lymphatic vasculature is a unidirectional network of lymphatic endothelial cells, whose main role is to maintain fluid homeostasis along with the absorption of dietary fat in the gastrointestinal organs and management and coordination of immune cell trafficking into lymph nodes during homeostasis and under inflammatory conditions. In homeostatic conditions, immune cells, such as dendritic cells, macrophages, or T cells can enter into the lymphatic vasculature and move easily through the lymph reaching secondary lymph nodes where immune cell activation or peripheral tolerance can be modulated. However, under inflammatory conditions such as pathogen infection, increased permeabilization of lymphatic vessels allows faster immune cell migration into inflamed tissues following a chemokine gradient, facilitating pathogen clearance and the resolution of inflammation. Interestingly, since the re-discovery of lymphatic vasculature in the central nervous system, known as the meningeal lymphatic vasculature, the role of these lymphatics as a key player in several neurological disorders has been described, with emphasis on the neurodegenerative process. Alternatively, less has been discussed about meningeal lymphatics and its role in neuroinflammation. In this review, we discuss current knowledge about the anatomy and function of the meningeal lymphatic vasculature and specifically analyze its contribution to different neuroinflammatory processes, highlighting the potential therapeutic target of meningeal lymphatic vasculature in these pathological conditions.

IL-17A Mediates Demyelination by Activating A1 Astrocytes via SOCS3 During Angiostrongylus cantonensis Infection

Background

Demyelinating disease of the central nervous system is one of the most common neurological diseases and effective treatment is still under in-depth research. Our previous study showed that Angiostrongylus cantonensis infection can induce demyelination injury in mouse brains and IL-17A expression was shown to be significantly increased during this process. Moreover, we found that IL-17A inhibition attenuated the demyelination caused by A. cantonensis infection. However, the underlying mechanisms have not yet been fully elucidated.

Methods

IL-17A neutralizing antibodies were injected into A. cantonensis infected mice to decrease IL-17A levels. The activation of glial cells in the brain and the expression of cell markers were detected by a variety of methods, including real-time quantitative PCR, western blotting, and immunofluorescence staining. The relationship between IL-17A and astrocyte activation was further identified by in vitro experiments. The role of SOCS3 in the IL-17A stimulating process was determined using RNA-seq data collection of infected mice and the siRNA interference method.

Results

Demyelination of the corpus callosum was relieved after administration of IL-17A neutralizing antibody and this was accompanied by decreased activation of A1 type astrocytes around this region. The expression of SOCS3 was attenuated and activation of astrocytes by IL-17A was mediated by the IL-17RA/STAT3/SOCS3 pathway. IL-17A not only directly damaged oligodendrocytes but also indirectly damaged oligodendrocytes through A1 astrocyte mediation. Specific siRNA inhibition of IL-17A-inducible SOCS3 in astrocytes alleviated their damaging effects on oligodendrocytes.

Conclusion

IL-17A plays an important role in demyelination induced by A. cantonensis infection via the IL-17RA/STAT3/SOCS3 pathway in A1-type astrocytes, indicating that specific blockage of IL-17A and SOCS3 activity could be a therapeutic strategy for neuroinflammatory demyelinating diseases associated with astrocyte activation.

Interleukin 17A Derived from γδ T Cell Induces Demyelination of the Brain in Angiostrongylus cantonensis Infection

Angiostrongylus cantonensis infection is a typical cause of eosinophilic encephalitis (EM), which has been reported to induce serious damage in the central nervous system. Both parasite and host factors contribute to the onset of EM, but the related immune-inflammation pathogenesis remains poorly characterised. An A. cantonensis infection model was generated through the infection of mice by gavage. Transmission electron microscopy and immunohistochemistry were used to assess the pathologic changes in the brain. The mRNA expression of inflammatory factors was tested using qRT-PCR. A combination of flow cytometry and western blotting was used to evaluate the alteration of leukocytes and related cytokines. A critical role of IL-17 was found by injecting IL-17A monoclonal antibody into naïve and A. cantonensis-infected mice. A. cantonensis larvae altered the immune homeostasis in the brain, leading to the destruction of myelin sheaths and activation of microglia and macrophage. During this process, IL-17A accumulation was observed, and IL-17RA was expressed in oligodendrocytes and microglia during the infection. Notably, γδ T cell was the major origin of IL-17A production induced by the parasite. After an IL-17A-neutralising antibody was applied, alterations in myelination and the state of the microglia/macrophage were discovered; the neurobehavioural scores of the mice also improved. Our study reveals one unrecognised impact of the γδ T cells in parasitic encephalopathy and emphasises that blocking IL-17A signalling can attenuate microglia and macrophage activation, thus reducing CNS demyelination and ameliorating the neurobehavioural deficit in A. cantonensis-infected mice.

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

Administration of albendazole alone was not very suitable for the treatment of cerebral angiostrongyliasis. This study was designed to evaluate the effects of the co-therapy of this drug and dexamethasone in Th-1 and Th-2 dominant mice infected with Angiostrongylus cantonensis. Each of BALB/c and C57BL/6 mice infected with 50 A. cantonensis third-stage larvae were administered albendazole (10 mg/kg/day) alone, dexamethasone (0.5 mg/kg/day) alone, or co-therapy of the two drugs from day 7 or 14 post-infection for 7 or 14 days. After sacrifice, coronal slices were prepared from five brain regions and stained with hematoxylin and eosin. Eight pathological changes were employed to determine the therapeutic effectiveness using a scoring system. RNA-seq analysis was performed to confirm the histopathological findings. The infected BALB/c and C57BL/6 mice had similar patterns in the pathological changes. Meningitis, hemorrhage, size of worms, and encephalitis in the cerebral parenchyma were slighter in the mice treated with co-therapy than the remaining groups. Mice treated from day 14 had more severe changes than those from day 7. The histopathological findings were found to be consistent to immune responses determined by RNA-seq analysis. Co-therapy was determined to reduce pathological changes after administration to mice infected with A. cantonensis.

Trichostatin A, a Histone Deacetylase Inhibitor, Alleviates Eosinophilic Meningitis Induced by Angiostrongylus cantonensis Infection in Mice

Histone deacetylase inhibitor (HDACi) has been used in the treatment of neurodegenerative or autoimmune diseases. Angiostrongyliasis cantonensis caused by Angiostrongylus cantonensis infection is an emerging zoonosis of human eosinophilic meningitis or meningoencephalitis. Progressive neuronal apoptosis is the pathological basis of behavioral dysfunctions in angiostrongyliasis cantonensis. Neurological defects after anthelmintic treatment for angiostrongyliasis cantonensis are still common. In this study, we examined the effects of trichostatin A (TSA), a HDACi, on eosinophilic meningitis induced by A. cantonensis in mice. Intragastric administration of TSA significantly ameliorated brain injury and decreased cognitive impairments in mice at 15 days post-infection. TSA administration effectively reduced the inflammatory factor levels of iNOS, TNF-α, IL-5, IL-6, and IL-13 in infected mice. TSA treatment counteracted apoptosis with reduced expression levels of cleaved caspase-3, -4, -6, and RIP3 in A. cantonensis infected mice. In addition, TSA administration reduced total HDAC activity and increased the acetylation of histone H3 and H4 in the brain tissue of infected mice. The underlying mechanism of TSA on eosinophilic meningitis might be associated with decreased NF-κB p65 nuclear accumulation by inhibiting IκB phosphorylation. Furthermore, a co-expressive network of NF-κB p65 with 22 other genes was constructed according to our previous transcriptomic data in infected mice. We identified the correlations in the gene expression of NF-κB p65 with Lrp10, Il12rb1, Nfkbia, Ube2n, and Ube2d1 in infected mice after TSA administration. Thus, TSA has a protective effect on the progression of eosinophilic meningitis induced by A. cantonensis in mice.

Regulatory effect of host miR-101b-3p on parasitism of nematode Angiostrongylus cantonensis via superoxide dismutase 3

MicroRNA plays a vital role in the regulation of host-parasite interaction. In recent years, genomic and transcriptomic resources have become increasingly available for many helminths, but only a limited number of reports in this area are on the regulatory effects of host microRNAs on parasitic nematodes. In this work, we screened increased expression of host microRNAs after nematode infection from miRNA-seq data and predicted target genes by combined bioinformatics analysis and transcriptional profiling. We elucidated regulatory effects of one host miRNA on nematode infection using miRNA inhibitor and adeno-associated virus (AAV)-based TuD miRNA inhibitor. Using AAV-based TuD miRNA inhibitor, we showed that stable blockade of mmu-miR-101b-3p could alleviate the pathological damages of Angiostrongylus cantonensis, a parasitic nematode. Data from a luciferase report assay showed that mmu-miR-101b-3p targeted the extracellular superoxide dismutase 3 (Acsod3). Increased Acsod3 expression in larvae and alleviated oxidative damages were seen in the groups receiving mmu-miR-101b-3p inhibitor treatment in vitro and AAV-based TuD miRNA inhibitor injection in vivo. Results of this study demonstrate that murine miR-101b-3p inhibits the expression of antioxidant enzyme in A. cantonensis to strengthen host oxidative responses to nematodes. This work expands our knowledge of interspecies regulation of nematode gene expression by of host miRNAs.

The Interleukin-10 Family of Cytokines and Their Role in the CNS

Resident cells of the central nervous system (CNS) play an important role in detecting insults and initiating protective or sometimes detrimental host immunity. At peripheral sites, immune responses follow a biphasic course with the rapid, but transient, production of inflammatory mediators giving way to the delayed release of factors that promote resolution and repair. Within the CNS, it is well known that glial cells contribute to the onset and progression of neuroinflammation, but it is only now becoming apparent that microglia and astrocytes also play an important role in producing and responding to immunosuppressive factors that serve to limit the detrimental effects of such responses. Interleukin-10 (IL-10) is generally considered to be the quintessential immunosuppressive cytokine, and its ability to resolve inflammation and promote wound repair at peripheral sites is well documented. In the present review article, we discuss the evidence for the production of IL-10 by glia, and describe the ability of CNS cells, including microglia and astrocytes, to respond to this suppressive factor. Furthermore, we review the literature for the expression of other members of the IL-10 cytokine family, IL-19, IL-20, IL-22 and IL-24, within the brain, and discuss the evidence of a role for these poorly understood cytokines in the regulation of infectious and sterile neuroinflammation. In concert, the available data indicate that glia can produce IL-10 and the related cytokines IL-19 and IL-24 in a delayed manner, and these cytokines can limit glial inflammatory responses and/or provide protection against CNS insult. However, the roles of other IL-10 family members within the CNS remain unclear, with IL-20 appearing to act as a pro-inflammatory factor, while IL-22 may play a protective role in some instances and a detrimental role in others, perhaps reflecting the pleiotropic nature of this cytokine family. What is clear is that our current understanding of the role of IL-10 and related cytokines within the CNS is limited at best, and further research is required to define the actions of this understudied family in inflammatory brain disorders.

The opposite roles of PAS-5 and Galectin-1 in immune response during the early infection of Angiostrongylus cantonensis

BACKGROUND

Angiostrongylus cantonensis is a human zoonotic nematode parasite. Our previous studies found that PAS-5 and Galectin-1 (Gal-1) proteins of A. cantonensis could be strongly recognized by sera from mice infected with A. cantonensis. In this study, we further evaluated the potential roles of these two proteins in the induction of immune response in mice.

METHODS

Mice were immunized with recombinant PAS-5 or Gal-1 and then challenged with 30 infective A. cantonensis larvae following the last immunization. We then examined the infected mice for changes in serum antibodies and cytokines by ELISA, CD4+ T cells and CD4+CD25+FoxP3+ regulatory T cells (Tregs) by flow cytometry, and tissue damage severity by hematoxylin-eosin (H&E) staining.

RESULTS

Compared with control mice, the PAS-5-immunized mice exhibited increased levels of serum antibodies and cytokines (except for IL-10) at different time points post-infection. PAS-5 immunization promoted significant proliferation of CD4+ T cells, and caused more damage in the brain tissue. Vaccination with Gal-1 inhibited the production of antibodies (except for IgG1) and IFN-γ, but promoted the expression of IL-4 and IL-10. Gal-1 immunization results in significant increases in the levels of CD4+CD25+FoxP3+ Tregs, and mild inflammatory changes.

CONCLUSIONS

Taken together, our findings show that PAS-5 enhances, but Gal-1 inhibits the immune response in the early stage of A. cantonensis infections.

Chi3l3: a potential key orchestrator of eosinophil recruitment in meningitis induced by Angiostrongylus cantonensis

BACKGROUND

Angiostrongylus cantonensis, an important foodborne parasite, can induce serious eosinophilic meningitis in non-permissive hosts, such as mouse and human. However, the characteristics and mechanisms of the infection are still poorly understood. This study sought to determine the key molecules and its underlying mechanism in inducing brain eosinophilic infiltration caused by Angiostrongylus cantonensis.

METHODS

Mathematical models were established for prediction of significantly changing genes and the functional associated protein with RNA-seq data in Angiostrongylus cantonensis infection. The expression level of Chi3l3, the predicted key molecule, was verified using Western blotting and real-time quantitative PCR. Critical cell source of Chi3l3 and its relationship with eosinophils were identified with flow cytometry, immunohistochemistry, and further verified by macrophage depletion using liposomal clodronate. The role of soluble antigens of Angiostrongylus cantonensis in eosinophilic response was identified with mice airway allergy model by intranasal administration of Alternaria alternate. The relationship between Chi3l3 and IL-13 was identified with flow cytometry, Western blotting, and Seahorse Bioscience extracellular flux analyzer.

RESULTS

We analyzed the skewed cytokine pattern in brains of Angiostrongylus cantonensis-infected mice and found Chi3l3 to be an important molecule, which increased sharply during the infection. The percentage of inflammatory macrophages, the main source of Chi3l3, also increased, in line with eosinophils percentage in the brain. Network analysis and mathematical modeling predirect a functional association between Chi3l3 and IL-13. Further experiments verified that the soluble antigen of Angiostrongylus cantonensis induce brain eosinophilic meningitis via aggravating a positive feedback loop between IL-13 and Chi3l3.

CONCLUSIONS

We present evidences in favor of a key role for macrophave-derived Chi3l3 molecule in the infection of Angiostrongylus cantonensis, which aggravates eosinophilic meningitis induced by Angiostrongylus cantonensis via a IL-13-mediated positive feedback loop. These reported results constitute a starting point for future research of angiostrongyliasis pathogenesis and imply that targeting chitinases and chitinase-like-proteins may be clinically beneficial in Angiostrongylus cantonensis-induced eosinophilic meningitis.

Apoptosis and necroptosis of mouse hippocampal and parenchymal astrocytes, microglia and neurons caused by Angiostrongylus cantonensis infection

BACKGROUND

Angiostrongylus cantonensis has been the only parasite among Angiostrongylidae to cause human central nervous system infection characterized by eosinophilic meningitis or meningoencephalitis. The mechanism of the extensive neurological impairments of hosts caused by A. cantonensis larvae remains unclear. The aim of the present study was to investigate apoptosis, necroptosis and autophagy in the brains of mice infected with A. cantonensis, which will be valuable for better understanding the pathogenesis of angiostrongyliasis cantonensis.

METHODS

Functional and histological neurological impairments of brain tissues from mice infected with A. cantonensis were measured by the Morris water maze test and haematoxylin and eosin (H&E) staining, respectively. The transcriptional and translational levels of apoptosis-, necroptosis- and autophagy-related genes were quantified by quantitative real-time polymerase chain reaction (RT-PCR), and assessed by western blot and immunohistochemistry (IHC) analysis. Apoptotic and necroptotic cells and their distributions in infected brain tissues were analysed by flow cytometry and transmission electron microscopy (TEM).

RESULTS

Inflammatory response in the central nervous system deteriorated as A. cantonensis infection evolved, as characterized by abundant inflammatory cell infiltration underneath the meninges, which peaked at 21 days post-infection (dpi). The learning and memory capacities of the mice were significantly decreased at 14 dpi, indicating prominent impairment of their cognitive functions. Compared with those of the control group, the mRNA levels of caspase-3, -4, -6, and RIP3 and the protein levels of caspase-4, cleaved caspase-3, cleaved caspase-6, RIP3, and pRIP3 were obviously elevated. However, no changes in the mRNA or protein levels of FADD, Beclin-1 or LC3B were evident, indicating that apoptosis and necroptosis, but not autophagy, occurred in the brain tissues of mice infected with A. cantonensis. The quantitative RT-PCR, western blot, IHC, flow cytometry and TEM results further revealed the apoptotic and necroptotic microglia, astrocytes and neurons in the parenchymal and hippocampal regions of infected mice.

CONCLUSIONS

To our knowledge, we showed for the first time that A. cantonensis infection causes the apoptosis and necroptosis of microglia and astrocytes in the parenchymal and hippocampal regions of host brain tissues, further demonstrating the pathogenesis of A. cantonensis infection and providing potential therapeutic targets for the management of angiostrongyliasis.

The diverse cellular responses of the choroid plexus during infection of the central nervous system

The choroid plexus (CP) is responsible for the production of a large amount of the cerebrospinal fluid (CSF). As a highly vascularized structure, the CP also presents a significant frontier between the blood and the central nervous system (CNS). To seal this border, the epithelium of the CP forms the blood-CSF barrier, one of the most important barriers separating the CNS from the blood. During the course of infectious disease, cells of the CP can experience interactions with intruding pathogens, especially when the CP is used as gateway for entry into the CNS. In return, the CP answers to these encounters with diverse measures. Here, we will review the distinct responses of the CP during infection of the CNS, which include engaging of signal transduction pathways, the regulation of gene expression in the host cells, inflammatory cell response, alterations of the barrier, and, under certain circumstances, cell death. Many of these actions may contribute to stage an immunological response against the pathogen and subsequently help in the clearance of the infection.

Stimulation of IL-1β and IL-6 through NF-κB and sonic hedgehog-dependent pathways in mouse astrocytes by excretory/secretory products of fifth-stage larval Angiostrongylus cantonensis

BACKGROUND

Angiostrongylus cantonensis is an important causative agent of eosinophilic meningitis and eosinophilic meningoencephalitis in humans. Previous studies have shown that the Sonic hedgehog (Shh) signaling pathway may reduce cell apoptosis by inhibiting oxidative stress in A. cantonensis infection. In this study, we investigated the relationship between cytokine secretion and Shh pathway activation after treatment with excretory/secretory products (ESP) of fifth-stage larval A. cantonensis (L5).

RESULTS

The results showed that IL-1β and IL-6 levels in mouse astrocytes were increased. Moreover, ESP stimulated the protein expression of Shh pathway molecules, including Shh, Ptch, Smo and Gli-1, and induced IL-1β and IL-6 secretion. The transcription factor nuclear factor-κB (NF-κB) plays an important role in inflammation, and it regulates the expression of proinflammatory genes, including cytokines and chemokines, such as IL-1β and TNF-α. After ESP treatment, NF-κB induced IL-1β and IL-6 secretion in astrocytes by activating the Shh signaling pathway.

CONCLUSIONS

Overall, the data presented in this study showed that ESP of fifth-stage larval A. cantonensis stimulates astrocyte activation and cytokine generation through NF-κB and the Shh signaling pathway.

Establishment of a murine pancreatic cancer pain model and microarray analysis of pain‑associated genes in the spinal cord dorsal horn

There is emerging evidence on the mechanisms of pancreatic cancer pain. Following the establishment of an orthotropic transplantation model of pancreatic cancer, microarray analysis was performed to identify changes in the expression levels of pain-associated genes in the spinal cord. A mouse model of pancreatic cancer-induced pain was established by implanting SW 1990 cells into the pancreases of female BALB/c-nu mice. The survival rate and body weight were measured following orthotropic transplantation. Gross anatomical techniques and hematoxylin and eosin staining were used to analyze the pancreatic tumor tissue. Multiple behavioral tests were also performed to assess pain-associated responses. Additionally, using samples from mice with or without observable pain, microarray analysis was performed to determine the gene expression profiles in the spinal cord dorsal horn. The survival rate of mice with pancreatic cancer was high during the initial 3 weeks post-surgery, although the body weight decreased progressively. Gross anatomical techniques demonstrated that the tumor size increased significantly following the surgery, and this result was confirmed by solid tumor masses in the pancreatic tissues of the mouse model. Observable pain behavioral responses were also examined in the pancreatic cancer model by measuring the mechanical threshold of the abdominal skin, hunching behavior and visceromotor responses. The profiles of 10 pain specific-associated genes in the spinal cord dorsal horn that accurately reflect the molecular pathological progression of disease were also identified. In conclusion, the present study has developed a novel animal model of pancreatic cancer pain in BALB/c-nu mice that resembles human pancreatic cancer pain, and the expression of pain-associated genes in the spinal cord dorsal horn has been profiled. The results of the present study may further the understanding of the molecular mechanisms that mediate pancreatic cancer pain.

Neuronal Apoptosis: Pathological Basis of Behavioral Dysfunctions Induced by Angiostrongylus cantonensis in Rodents Model

Angiostrongylus cantonensis invades the central nervous system (CNS) of humans to induce eosinophilic meningitis and meningoencephalitis and leads to persistent headache, cognitive dysfunction, and ataxic gait. Infected mice (nonpermissive host), admittedly, suffer more serious pathological injuries than rats (permissive host). However, the pathological basis of these manifestations is incompletely elucidated. In this study, the behavioral test, histological and immunohistochemical techniques, and analysis of apoptotic gene expression, especially caspase-3, were conducted. The movement and motor coordination were investigated at week 2 post infection (PI) and week 3 PI in mice and rats, respectively. The cognitive impairs could be found in mice at week 2 PI but not in rats. The plaque-like lesion, perivascular cuffing of inflammatory cells, and dilated vessels within the cerebral cortex and hippocampus were more serious in mice than in rats at week 3 PI. Transcriptomic analysis showed activated extrinsic apoptotic pathway through increased expression of TNFR1 and caspase-8 in mice CNS. Immunohistochemical and double-labeling for NeuN and caspase-3 indicated the dramatically increased expression of caspase-3 in neuron of the cerebral cortex and hippocampus in mice but not in rats. Furthermore, western-blotting results showed high expression of cleaved caspase-3 proteins in mice but relatively low expression in rats. Thus, extrinsic apoptotic pathway participated in neuronal apoptosis might be the pathological basis of distinct behavioral dysfunctions in rodents with A. cantonensis infection. It provides the evidences of a primary molecular mechanism for the behavioral dysfunction and paves the ways to clinical diagnosis and therapy for A. cantonensis infection.

Spleen atrophy related immune system changes attributed to infection of Angiostrongylus cantonensis in mouse model

The spleen is one of the most important peripheral immune organs, which is frequently affected in infectious diseases. Infectious diseases can induce splenic alterations including splenic atrophy and functional alteration, while splenic atrophy may in turn interferes with recovery of infectious diseases. Angiostrongyliasis is an infectious disease by Angiostrongylus cantonensis (A. cantonensis), which invade non-permissive hosts, such as humans and mice, to cause severe damage to the central nervous system (CNS) and acute inflammatory response. A. cantonensis infection-induced CNS injury has been confirmed to be due to profound immunopathology derived from peripheral immune components. However, the mechanism of immunopathology remains largely unknown. Here, we found that A. cantonensis invaded non-permissive hosts such as mice in the brain, but not in the other peripheral organs. However, this infection induced severe spleen atrophy. We further recognized that this atrophy is associated with a decrease of total splenocyte number and disruption of splenic structure due to reduced proliferation and increased apoptotosis. These also resulted in deterioration of T cell profile in the periphery with a low CD4/CD8 ratio and B/T cell ratio, and increased ratio of CD4⁺CD25⁺Foxp3⁺ Treg, CD8⁺CD28^- T, and CD38⁺T lymphocyte of spleen. Albendazole treatment can alleviate spleen atrophy and set T cell immune reconstitution in some extend. Our data showed that A. cantonensis infection can cause splenic atrophy. These results are suggested to put more emphasis to improve the function of immune system. Meanwhile, infection and treatment model will be useful to evaluate new therapeutic approaches which can prevent or reverse immunosuppression and infectious complications.

Soluble antigen derived from IV larva of Angiostrongylus cantonensis promotes chitinase-like protein 3 (Chil3) expression induced by interleukin-13

Angiostrongyliasis caused by Angiostrongylus cantonensis (A. cantonensis) is an emerging food-borne parasitic disease, which refers basically to eosinophilic meningitis. Chitinase-like protein 3 (Chil3), a member of chitinase-like protein family which has chemotactic activity for eosinophils, is reported to be highly upregulated in brain of mouse infected with A. cantonensis. The mechanisms of high expression of Chil3 and the association between A. cantonensis and Chil3 are rarely reported. In order to understand the mechanism of high expression of Chil3 in A. cantonensis-infected mouse, we measured the level of Chil3 in RAW 264.7 and BV2 cell lines stimulated with soluble antigen of A. cantonensis by qPCR and ELISA. To explore the role of Chil3 in inflammation caused by A. cantonensis, we extracted and cultured brain mononuclear cells (BMNCs) and detected the eosinophil chemotactic activity of Chil3 using transwell assay and flow cytometer. Furthermore, we treated the infected mice by injection with rmChil3 and then counted the number of larvae in brains of infected mice and treated mice to examine the association between the worm and Chil3. Our results showed the soluble antigen from A. cantonensis could promote the Chil3 expression in macrophage and microglial cell lines induced by interleukin-13. In conclusion, we supposed that high expression of Chil3 enhanced by soluble antigens from A. cantonensis might be the reason of serious eosinophil infiltration in mouse brain after A. cantonensis infection.

Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen

Angiostrongylus cantonensis is a metastrongyloid nematode found widely in the Asia-Pacific region, and the aetiological agent of angiostrongyliasis; a disease characterized by eosinophilic meningitis. Rattus rats are definitive hosts of A. cantonensis, while intermediate hosts include terrestrial and aquatic molluscs. Humans are dead-end hosts that usually become infected upon ingestion of infected molluscs. A presumptive diagnosis is often made based on clinical features, a history of mollusc consumption, eosinophilic pleocytosis in cerebral spinal fluid, and advanced imaging such as computed tomography. Serological tests are available for angiostrongyliasis, though many tests are still under development. While there is no treatment consensus, therapy often includes a combination of anthelmintics and corticosteroids. Angiostrongyliasis is relatively rare, but is often associated with morbidity and sometimes mortality. Recent reports suggest the parasites' range is increasing, leading to fatalities in regions previously considered Angiostrongylus-free, and sometimes, delayed diagnosis in newly invaded regions. Increased awareness of angiostrongyliasis would facilitate rapid diagnosis and improved clinical outcomes. This paper summarizes knowledge on the parasites' life cycle, clinical aspects and epidemiology. The molecular biology of Angiostrongylus spp. is also discussed. Attention is paid to the significance of angiostrongyliasis in Australia, given the recent severe cases reported from the Sydney region.