Intrathecal synthesis of IgE in children with eosinophilic meningoencephalitis caused by Angiostrongylus cantonensis

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.

Eosinophilic Meningitis Secondary to Intravenous Vancomycin

Eosinophilic meningitis may be due to infectious or noninfectious etiologies. Parasitic infections cause this entity most frequently and of the noninfectious causes, medications play an important role. We describe a 32-year-old male who developed eosinophilic meningitis while receiving intravenous vancomycin. No other apparent cause of the eosinophilic meningitis was appreciated. This case represents the first description of eosinophilic meningitis due to systemic vancomycin.

Intrathecal activation as a typical immune response within the central nervous system in angiostrongyliasis

Angiostrongylus cantonensis is a zoonotic pathogen that occasionally causes human angiostrongyliasis; its main clinical manifestation is eosinophilic meningitis. This report defines the concept of intrathecal activation of complement as evidence of intrathecal synthesis of major immunoglobulins during this disease. Details are presented of the activation of complement system components in cerebrospinal fluid, and their application to our understanding of this tropical disease, which is emerging in the Western hemisphere. Intrathecal synthesis of at least one of the major immunoglobulins and a wide spectrum of patterns may be observed. Although intrathecal synthesis of C3c is always present, C4 intrathecal synthesis does not occur in every patient. The diversity of intrathecal synthesis and activation of the different complement pathways enables their division into three variant groups (A, B, and C). Variant group A includes the classical and/or lectin pathway and involves two or more major immunoglobulins with C3 and C4 intrathecal synthesis. Variant group B involves C4 in cerebrospinal fluid that comes from blood in the intrathecal activation of the classical pathway. Variant group C includes the alternative pathway.

Alteration of T cell subtypes in spleen and antibodies of serum in mice infected with Angiostrongylus cantonensis

The immune responses of Angiostrongylus cantonensis infection are closely relevant to the host's self-protection and the nematode's pathogenesis. In the present study, BALB/c mice were randomly divided into uninfected control group, infection group 1, and infection group 2. The infection group 1 and infection group 2 were infected with 20 and 40 third-stage larvae of A. cantonensis per mouse, respectively. The splenocytes from the mice were collected and cultured on the 19th and 25th days post-infection; the subtypes of T cells in splenocytes were detected by flow cytometry with fluorescence staining method, and the cytokines in cultured supernatants of splenocytes were assayed by the method of ELISA. The specific IgG and IgE antibodies in sera of the mice were periodically detected by ELISA. The results showed that the percentages of CD4(+) and CD4(+) IL-4(+) T cells in splenocytes of infected mice were much higher (P < 0.05) than those in control mice; however, the percentages of CD4(+) IL-17(+) and CD4(+) IFN-γ(+) T cell were much lower(P < 0.01) after the infection. The levels of CD8(+) T cells in infected mice also rose, but differences between control mice and infected mice were not significant. In comparison with control mice, the concentration of IL-4 in the cultured supernatants of splenocytes in infected mice increased significantly (P < 0.05), but that of IL-17 decreased significantly (P < 0.01). In addition, the number of larvae infected and days after infection may influence levels of the T cell subtypes and the cytokines in spleen, too (P > 0.05). On humoral immunity, the levels of specific IgG antibodies in sera rose a bit at the fifth day post-infection, and reached a peak at the 20th day post-infection; the specific IgE antibodies gradually heightened during first 10 days post-infection; then, it showed a downward trend during the 15th to 25th days post-infection. It is evident that the percentages of CD4(+) T lymphocytes of spleen in the mice infected with A. cantonensis markedly increase and polarize to Th2 phenotypes, and the function of Th17 cells is inhibited. In addition, the elevation of specific IgG antibodies in sera of the infected mice is more significant than that of specific IgE antibodies.

Monoclonal antibody 12D5 inhibits eosinophil infiltration in the brain of Angiostrongylus cantonensis-infected BALB/c mice

Each of BALB/c mice was infected with 50 Angiostrongylus cantonensis larvae. One group of mice received an intraperitoneal injection of 50 μg 12D5 monoclonal antibody (mAb) against a 98 kDa antigen of adult worms at 10 days post-infection (dpi), with a booster injection of 25 μg at 12 dpi. Five mice from each group were sacrificed at 14 dpi for pathological examination and RNA extraction. The infiltration of eosinophils and severity of eosinophilic meningitis were reduced in 12D5 mAb-treated mice compared with the infected mice without 12D5 treatment. The levels of eotaxin mRNA expression in spleen significantly increased and the expression of the Th2-type cytokine IL-5 significantly decreased. However, the expression of IL-4 was not changed. 12D5 mAb can observably enhance the survival rate of infected mice and reduce symptoms of angiostrongyliasis. A. cantonensis infection is a major cause of eosinophilic meningoencephalitis. The results of this study could be helpful for the development of treatment of human angiostrongylosis.

Mannose-binding lectin deficiency with eosinophilic meningoencephalitis due to Angiostrongylus cantonensis in children: a case series

INTRODUCTION

Eosinophilic meningitis, a potentially fatal disease caused by Angiostrongylus cantonensis, is considered an emerging infectious disease.

CASE PRESENTATION

Three Caucasian boys (aged five-years-old, 10-years-old and six-years-old) with a diagnosis of eosinophilic meningoencephalitis caused by Angiostrongylus cantonensis were studied. Serum immunoglobulin A (IgA), IgM, IgG, and complements C3c and C4 levels were quantified by using an immunodiffusion technique. Immunoglobulin E in serum was quantified by nephelometry and mannose-binding lectin by time-resolved fluorometry. Mannose-binding lectin deficiency was observed in the three patients. The first patient showed a reduction in the levels of IgA and IgM and an increase in the values of IgE and C4. The second patient showed a reduction in mannose-binding lectin level with increased IgG, C4 and IgE levels, and the third patient showed a decrease in mannose-binding lectin level and increased levels of IgM and complement C3c as well as a low level of C4.

CONCLUSIONS

To the best of our knowledge, this is the first report of mannose-binding lectin deficiency associated with Angiostrongylus cantonensis meningoencephalitis in children, and it may contribute to the understanding of the participation of this component of the lectin pathway in the development of the disease.

Revisting Cerebrospinal Fluid (CSF) Examination

Routine cerebrospinal fluid (CSF) examination bears re-visiting as the body of knowledge has expanded and numerous new analytes touted as potential markers of CNS (central nervous system) diseases have emerged. Currently, visual assessment of CSF, microscopic examination for pathologic cells, and biochemical analysis for protein and glucose form the basis for routine CSF analysis. Further investigations that may be warranted include microbiology work-ups for CNS infections and immuno-detection for oligoclonal bands for multiple sclerosis. European guidelines for CSF analyses are available. CSF testing for other neurologic disorders (e.g. Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis) while promising are not ready for prime time.

Reibergram of intrathecal synthesis of C4 in patients with eosinophilic meningitis caused by Angiostrongylus cantonensis

Angiostrongylus cantonensis produces eosinophilic meningitis in humans and is endemic in Thailand, Taiwan, China, and the Caribbean region. During infection with this parasite, it is important to know if the complement system may be activated by the classical or lectin pathway. Cerebrospinal fluid and serum samples from 20 patients with meningitic angiostrongyliasis were used to quantify C4 levels and albumin. Results were plotted on a C4 CSF/serum quotient diagram or Reibergram. Twelve patients showed intrathecal synthesis of C4. Antibody-dependent complement cytotoxicity should be considered as a possible mechanism that destroys third-stage larvae of this helminth in cerebrospinal fluid of affected patients.