Antigen dependent release of interleukin 5 in vitro from spleen cells of mice infected with Angiostrongylus cantonensis

Interleukin 33 mediates type 2 immunity and inflammation in the central nervous system of mice infected with Angiostrongylus cantonensis

Angiostrongylus cantonensis can induce central nervous system (CNS) injury and cause human eosinophilic meningitis. The CNS has been found to have high expression of interleukin 33 (IL-33), which promotes the pathogenesis of T-helper 2 (Th2)-related disease. Given the predominantly type 2 response induced by A. cantonensis-infected mice and human, it is likely that IL-33 may play a role in aiding this process. We report here that IL-33 protein and ST2L messenger RNA (mRNA) transcripts in the brains were upregulated during A. cantonensis infection and that both splenocytes and brain mononuclear cells became IL-33 responsive and produced interleukin 5 and interleukin 13. Furthermore, administration of IL-33 to A. cantonensis-infected mice enhanced ST2L expression and cytokine production. Interestingly, brain IL-33 protein and ST2L mRNA levels were elevated 14-21 days after infection in BALB/c mice, compared with C57BL/6 mice. Thus, our data indicate that IL-33 produced in the brain may function as an inflammatory mediator in eosinophilic meningitis induced by A. cantonensis.

Angiostrongylus cantonensis: effect of combination therapy with albendazole and dexamethasone on Th cytokine gene expression in PBMC from patients with eosinophilic meningitis

To determine how combination therapy with albendazole and dexamethasone changed cytokine responses in peripheral blood mononuclear cells (PBMC) in patients with eosinophilic meningitis caused by Angiostrongylus cantonensis (EOMA), we measured mRNA levels of Th2 (IL-5, IL-4 and IL-10) and Th1 (IL-2 and IFN-gamma) cytokines with reverse transcription polymerase chain reaction (RT-PCR). Forty-three patients were divided into three groups: group 1 (pre-treatment, 13 patients), group 2 (7 days post-treatment, 14 patients), and group 3 (30 days post-treatment, 16 patients). Peripheral eosinophil counts were also measured. EOMA patients showed higher levels of Th2 cytokines, including IL-5 and IL-10, and peripheral eosinophil counts, but no changes in IL-4 or Th1 cytokines. Combination therapy reduced IL-5 mRNA expression and peripheral eosinophil counts to control levels, but increased IL-10, IL-2, and IFN-gamma mRNA expression, and did not change IL-4 levels. These data suggest that systemic Th2 cytokine responses, especially IL-5, and peripheral eosinophil counts increased in EOMA patients. Combination therapy with albendazole and dexamethasone can shift the cytokine responses from Th2 to Th1 dominance, which may be a therapeutic mechanism.

Angiostrongylus cantonensis: apoptosis of inflammatory cells induced by treatment with mebendazole or/and interleukin 12 in mice

Angiostrongylus cantonensis is the major cause of human eosinophilic meningoencephalitis. ICR mice were infected orally with 35 infective larvae and sacrificed at 4-14 days, 25 days or 32 days post infection (dpi) for pathological and immunocytochemical examinations. In the non-treated group, no apoptosis signal was found in the meninges or parenchyma of the brains (4-14 dpi). Only a few apoptotic cells were noticed at 25 dpi (3%) and 32 dpi (10%). In the groups, the animals were given a single dose of mebendazole (20 mg/kg, per os at various times) or injections of interleukin 12 (IL-12) (10 ng/daily, intraperitoneally), all the animals were sacrificed at 14 dpi; the number of apoptotic cells was increased (17-21%). In the group that received a single dose of mebendazole (4 dpi) in combination with IL-12 injections (4-13 dpi), mild meningitis was observed, and most of the infiltrated inflammatory cells were in the apoptotic program (55%). Taken together, apoptosis of the inflammatory cells (most were eosinophils) could be induced when the infected mice were treated with mebendazole or/and IL-12.

The role of eosinophils in Angiostrongylus cantonensis infection

Angiostrongylus cantonensis is the causative agent of human eosinophilic meningoencephalitis in the Pacific Islands and Southeast Asia. Prominent eosinophilia in the cerebrospinal fluid (CSF) of the patients has been used as one of the diagnostic criteria for the disease but the role(s) of the CSF eosinophils has remained to be elucidated. In this article, Kentaro Yoshimura, Hiroko Sugaya and Kazuto Ishido discuss the involvement of CSF eosinophils in the killing of intracranial worms and the damage of the central nervous system of the hosts, and consider why eosinophils in A. cantonensis infection play a more important role in nonpermissive hosts (including humans) than in the permissive rat host.

Combined treatment with interleukin-12 and mebendazole lessens the severity of experimental eosinophilic meningitis caused by Angiostrongylus cantonensis in ICR mice

Angiostrongylus cantonensis is the major cause of eosinophilic meningoencephalitis cases in Taiwan. Mice were orally infected with 35 infective larvae. One group of mice were given a single dose of mebendazole (20 mg/kg of body weight) per os at various times and examined at 14 days postinfection (dpi) for worm recovery rate and pathological studies. A 94 to 97% reduction in worm recovery was observed when medication was given at 4 to 5 dpi. Sections of the brains revealed that untreated infected mice developed typical severe eosinophilic meningoencephalitis. Meninges of these mice were thickened by massive infiltration of eosinophils, whereas only moderate pathological change was observed in the brains of mice that were treated with mebendazole at 4 dpi. Infected mice that received daily injections of 10 ng of interleukin-12 (IL-12) only for various numbers of days also exhibited moderate pathological changes in the brain. Eosinophil infiltration in the brains of these mice was low, and severe mechanical injuries in the parenchyma were observed. Treatment with mebendazole in combination with IL-12, however, resulted in low levels of worm recovery and dramatic lessening of the eosinophilic meningitis. A reverse transcriptase PCR assay of mRNA expression in the brain also revealed that the use of IL-12 had shifted the immune response of the mouse from Th2 type to Th1 type. This study could be used in developing strategies for the treatment of human angiostrongylosis.

Eosinophils in the cerebrospinal fluid of mice infected with Angiostrongylus cantonensis are resistant to apoptosis

Interleukin-5 (IL-5) transgenic mice were used to assess the immunological features of CSF eosinophils from mice infected with Angiostrongylus cantonensis. CSF eosinophils were hypodense by day 14 post infection (p.i.). CSF eosinophils survived longer in vitro than peritoneal eosinophils collected from cadmium sulphate (CdSO(4)) -treated normal IL-5 transgenic mice. Apoptosis was measured by Annexin V binding and the presence of a distinct laddering pattern of DNA fragmentation on agarose electrophoresis. Regardless of the presence or absence of Actinomycin D, CSF eosinophils collected from IL-5 transgenic mice from days 15-36 p.i. exhibited less apoptosis than peritoneal eosinophils collected from uninfected IL-5 transgenic mice. CSF eosinophils collected from A. cantonensis infected C57BL/6 mice at days 15-34 p.i. showed elongation of survival time and less apoptosis during in vitro cultivation. Reduced apoptosis was noted only in CSF eosinophils, but not in peritoneal eosinophils recovered from the same infected IL-5 transgenic mice. CPP32/Caspase 3 activity of cultured peritoneal eosinophils from both infected and uninfected IL-5 transgenic mice was higher than that of cultured CSF eosinophils. Stimulation with A23187 readily induced apoptosis of peritoneal eosinophils, but not CSF eosinophils or peritoneal eosinophils cultured with mouse recombinant IL-5. The latter cells were morphologically identical to hypodense eosinophils. RT-PCR analysis indicated that bcl-2 and bcl-x(L) mRNA expression was higher in CSF eosinophils compared with peritoneal eosinophils and this expression in the latter cells was upregulated after culture with mouse recombinant IL-5. These results suggest that CSF eosinophils, shifting to hypodense status through an accumulation from peripheral blood, are resistant to apoptosis. These changes may explain the long-lasting, helminthotoxic and neurotoxic actions of CSF eosinophils in A. cantonensis infection.

Mediastinal lymph node cells of Angiostrongylus cantonensis-infected rats respond to antigens and release interleukin-5 in vitro

The kinetics of eosinophil growth and/or survival stimulating factor (Eo-stimulating factor) production in Angiostrongylus cantonensis-infected rats was assessed by in vitro marrow cultures. When lymphocytes, obtained from cervical, mediastinal or mesenteric lymph nodes of infected WKAH rats, were cultured with A. cantonensis antigens, Eo-stimulating factor activity was detected in the conditioned media obtained only from mediastinal lymph node cells at and after 35 days p.i. Eo-stimulating factor activity in the conditioned media was not detected before or at 20 days p.i. The kinetics of the factor was, therefore, almost identical to those of eosinophilia in bone marrow and peripheral blood. This Eo-stimulating factor activity was inhibited (maximum inhibition = 73%) by anti-mouse IL-5 monoclonal antibody in a dose-dependent fashion, indicating that the factor would be, at least in part, identical to IL-5. Similar Eo-stimulating factors were also detected in the conditioned media which were obtained by stimulating spleen cells from Wistar rats at 35-45 days p.i. with Con A. These data suggest that lymphocytes in the mediastinal lymph nodes, local lymph nodes near the adult worm habitat, could play an essential role in induction of eosinophilia in A. cantonensis-infected rats.