Gross, microscopic, radiologic, echocardiographic and haematological findings in rats experimentally infected with Angiostrongylus cantonensis.

Although the gross and microscopic pathology in rats infected with Angiostrongylus cantonensis has been well described, corresponding changes detected using diagnostic imaging modalities have not been reported. This work describes the cardiopulmonary changes in mature Wistar rats chronically infected with moderate burdens of A. cantonensis using radiology, computed tomography (CT), CT angiography, echocardiography, necropsy and histological examinations. Haematology and coagulation studies were also performed. Thoracic radiography, CT and CT angiography showed moderately severe alveolar pulmonary patterns mainly affecting caudal portions of the caudal lung lobes and associated dilatation of the caudal lobar pulmonary arteries. Presumptive worm profiles could be detected using echocardiography, with worms seen in the right ventricular outflow tract or straddling either the pulmonary and/or the tricuspid valves. Extensive, multifocal, coalescing dark areas and multiple pale foci affecting the caudal lung lobes were observed at necropsy. Histologically, these were composed of numerous large, confluent granulomas and fibrotic nodules. Adult worms were found predominantly in the mid- to distal pulmonary arteries. An inflammatory leukogram, hyperproteinaemia and hyperfibrinogenaemia were found in most rats. These findings provide a comparative model for A. cantonensis in its accidental hosts, such as humans and dogs. In addition, the pathological and imaging changes are comparable to those seen in dogs infected with Angiostrongylus vasorum, suggesting rats infected with A. cantonensis could be a model for dogs with A. vasorum infection.

Serological survey and risk factors of Aelurostrongylus abstrusus infection among owned cats in Italy.

Feline lungworms affect the respiratory tract of domestic cats causing respiratory conditions of various degrees. In this study, we investigated the exposure of cats to feline lungworm infections by detecting antibodies in a large population of animals from several regions of Italy. Sera of 1087 domestic cats living in regions of the north (n = 700), the centre (n = 227) and the south (n = 160) of Italy were examined by a newly developed indirect ELISA conceived for detection of antibodies against the most frequently occurring feline lungworm Aelurostrongylus abstrusus. Individual cat data (i.e., age, sex, neutering status and provenience) were analysed as potential risk factors for exposure to lungworm infections. Samples were additionally screened for feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) proviral DNAs. Overall, 9% (98/1087; 95% confidence interval (CI) 7.4-10.9%) of the animals tested seropositive to lungworm antibodies. Positive cats were identified in the north (7.1%; CI 5.5-9.3%), in the centre (5.3%; CI 3.0-9.0%) and in the South (22.5%; CI 16.7-29.6%), with more seropositive animals in the latter area (p < 0.05). The risk of lungworm infection in cats was significantly associated with age less than 6 months (i.e. 24.4%, p < 0.05) and FIV infection (p < 0.05). This large-scale serological survey confirms the exposure of cats to lungworm infections in Italy and that serological tests can be used to assess the distribution of lungworm infections in large populations of animals.

Angiostrongylus costaricensis infection in Martinique, Lesser Antilles, from 2000 to 2017.

Human abdominal angiostrongyliasis (HAA) is a parasitic disease caused by the accidental ingestion of the nematode Angiostrongylus costaricensis in its larval form. Human infection can lead to severe ischemic and inflammatory intestinal lesions, sometimes complicated by life-threatening ileal perforations. Only one case had been reported in Martinique, an Island in the French Antilles, in 1988. We retrospectively reviewed the medical charts of patients diagnosed with abdominal angiostrongyliasis at the University Hospital of Martinique between 2000 and 2017. The objectives of this study were to evaluate the incidence and perform a descriptive analysis of the clinical, biological, radiological, and histopathological features of HAA in Martinique. Two confirmed cases and two probable cases were identified in patients aged from 1 to 21 years during the 18-year period, with an estimated incidence of 0.2 cases per year (0.003 case/year/100.000 inhabitants (IC95% = 0.00-0.05)). All patients presented with abdominal pain associated with high blood eosinophilia (median: 7.24 G/L [min 4.25; max 52.28 G/L]). Two developed ileal perforation and were managed by surgery, with diagnostic confirmation based on histopathological findings on surgical specimens. The other two cases were probable, with serum specimens reactive to Angiostrongylus sp. antigen in the absence of surgery. All cases improved without sequelae. The description of this case series highlights the need to increase awareness of this life-threatening disease in the medical community and to facilitate access to specific diagnostic tools in Martinique. Environmental and epidemiological studies are needed to broaden our knowledge of the burden of this disease.

TITLE: Infections par Angiostrongylus costaricensis à la Martinique, Antilles, de 2000 à 2017. ABSTRACT: L'angiostrongylose abdominale humaine (AAH) est une maladie parasitaire causée par l'ingestion accidentelle du nématode Angiostrongylus costaricensis sous sa forme larvaire. L'infection humaine peut conduire à des lésions intestinales ischémiques et inflammatoires sévères, parfois compliquées par des perforations iléales menaçant le pronostic vital. Un seul cas avait été signalé en Martinique, une île des Antilles françaises, en 1988. Nous avons revu rétrospectivement les dossiers médicaux des patients ayant reçu un diagnostic d'angiostrongylose abdominale au CHU de la Martinique entre 2000 et 2017. Les objectifs de cette étude étaient d'évaluer l'incidence et effectuer une analyse descriptive des caractéristiques cliniques, biologiques, radiologiques et histopathologiques de l'AAH en Martinique. Deux cas confirmés et deux cas probables ont été identifiés chez des patients âgés de 1 à 21 ans au cours de la période de 18 ans, avec une incidence estimée à 0,2 cas par an (0,003 cas / an / 100 000 habitants (IC95% = 0,00 − 0,05)). Tous les patients présentaient une douleur abdominale associée à une éosinophilie sanguine élevée (médiane: 7,24 G/L [min 4,25; max 52,28 G / L]). Deux ont développé une perforation iléale et ont été traités par chirurgie, avec une confirmation diagnostique basée sur les résultats histopathologiques sur des échantillons chirurgicaux. Les deux autres cas étaient probables, avec des échantillons sériques réagissant aux antigènes d'Angiostrongylus sp. en l'absence de chirurgie. Tous les cas se sont améliorés sans séquelles. La description de cette série de cas souligne la nécessité de sensibiliser davantage la communauté médicale à cette maladie potentiellement mortelle et de faciliter l'accès à des outils diagnostiques spécifiques en Martinique. Des études environnementales et épidémiologiques sont nécessaires pour élargir nos connaissances sur cette parasitose.

Anti-N-methyl-D-aspartate receptor encephalitis associated with intracranial Angiostrongylus cantonensis infection: a case report.

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a recently described paraneoplastic syndrome with prominent neuropsychiatric symptoms. Many of these cases are associated with neoplasma especially teratoma. In addition, a few of cases with anti-NMDAR antibodies triggered by viral infection have been reported, but never by parasitic infection. Here, we report a novel case of NMDA receptor encephalitis in a 51-year-old male related to the development of anti-NMDAR antibodies triggered by Angiostrongylus cantonensis infection.

Characterization of the inflammatory response to anthelmintic treatment of ponies with cyathostominosis.

Cyathostomins can cause a severe inflammation of equine large intestine characterized by substantial ventral edema and pronounced protein loss. Anthelmintic treatment of horses can result in a localized inflammatory response in the colonic mucosa of clinically normal horses. The aim of this study was to evaluate the systemic inflammatory response of ponies naturally infected with cyathostomins to single dose representatives of three anthelmintic drug classes, namely, oxibendazole, pyrantel pamoate, and moxidectin. Thirty ponies aged between 1 and 18 years of age were allocated to one of three anthelmintic treatments groups. Anthelmintic efficacy was evaluated using the fecal egg count reduction test performed weekly between 2 and 8 weeks post-treatment. Inflammatory responses were evaluated on days 0, 1, 3, 5, and 14 after treatment using hematology, measurement of the acute phase inflammatory markers serum amyloid A, fibrinogen, haptoglobin, and iron, and real-time PCR measurement of expression of the genes for interleukins 1-ß and -10, tumor necrosis factor-α, and interferon-γ. There were subtle inflammatory responses to treatment, but cytokine expression was significantly associated with the interaction term between treatment group and anthelmintic efficacy (P<0.05). Of the acute phase markers, only fibrinogen associated with treatment group. The findings suggest that systemic inflammatory responses subsequent to anthelmintic treatment of cyathostomin infection are minimal. It is possible that this response is 'buffered' by anti-inflammatory products of the parasites and/or the anti-inflammatory effects of the macrocyclic lactones.

Gain of function in the immune system caused by a ryanodine receptor 1 mutation.

Mutations in RYR1, the gene encoding ryanodine receptor 1, are linked to a variety of neuromuscular disorders including malignant hyperthermia (MH), a pharmacogenetic hypermetabolic disease caused by dysregulation of Ca(2+) in skeletal muscle. RYR1 encodes a Ca(2+) channel that is predominantly expressed in skeletal muscle sarcoplasmic reticulum, where it is involved in releasing the Ca(2+) necessary for muscle contraction. Other tissues, however, including cells of the immune system, have been shown to express ryanodine receptor 1; in dendritic cells its activation leads to increased surface expression of major histocompatibility complex II molecules and provides synergistic signals leading to cell maturation. In the present study, we investigated the impact of an MH mutation on the immune system by studying the RYR1Y522S knock-in mouse. Our results show that there are subtle but significant differences both in resting 'non-challenged' mice as well as in mice treated with antigenic stimuli, in particular the knock-in mice: (i) have dendritic cells that are more efficient at stimulating T cell proliferation, (ii) have higher levels of natural IgG1 and IgE antibodies, and (iii) are faster and more efficient at mounting a specific immune response in the early phases of immunization. We suggest that some gain-of-function MH-linked RYR1 mutations might offer selective immune advantages to their carriers. Furthermore, our results raise the intriguing possibility that pharmacological activation of RyR1 might be exploited for the development of new classes of vaccines and adjuvants.

Basophil effector function and homeostasis during helminth infection.

Basophils are effector cells of the innate immune system that are associated with allergic inflammation and infections with helminth parasites. However, their development and in vivo functions are largely unknown. Here, we characterize basophil development, turnover, tissue localization, and effector function during infection with the helminth Nippostrongylus brasiliensis. Our results demonstrate that under homeostatic conditions basophils have a lifespan of about 60 hours. N brasiliensis-induced basophilia is caused by increased de novo production of basophils in the bone marrow. Basophils were found near the marginal zone in the red pulp of the spleen, in the lamina propria of the small intestine, and in the lung parenchyma. Activated basophils promoted systemic eosinophilia, were associated with differentiation of alternatively activated macrophages in the lung, and contributed to efficient worm expulsion, demonstrating that basophils play a crucial role as effector cells in type 2 immune responses.

Decreased serum paraoxonase-1 activity during intestinal nematode (Nippostrongylus brasiliensis) infection in rats.

Reduced paraoxonase-1 (PON1) activity has been observed in a number of pathological conditions; however, little is known about the effects of intestinal nematode infections, such as Nippostrongylus brasiliensis, on paraoxonase activity. We observed a significant reduction in serum paraoxonase and arylesterase activity after N. brasiliensis infection in Wistar rats from Day 6 until Day 12 post-infection (p.i.) for serum paraoxonase and from Day 3 until Day 24 p.i. for arylesterase. In addition, N. brasiliensis infection increased serum concentrations of pro-inflammatory cytokines (interleukin-1, interleukin-6, and tumor necrosis factor-alpha), with maximum concentrations observed on Day 9 p.i. These cytokines are known to inhibit the synthesis of hepatic PON1 mRNA. Thus, the observed reduction in PON1 activity during N. brasiliensis infection is likely associated with inflammatory reactions mounted against the parasites.

Increased intestinal endotoxin absorption during enteric nematode but not protozoal infections through a mast cell-mediated mechanism.

It is known that hypersensitivity reactions in the gastrointestinal tract, which are primarily mediated by mast cells, are associated with a secretory response of the epithelium and often increased permeability to macromolecules. Studies to date have not examined the effects of hyperpermeability on the absorption of toxic substances normally present in the intestinal lumen such as bacterial LPS. In the present study, we observed that Strongyloides venezuelensis infection in mice decreases the mRNA expression of intestinal epithelial cell junctional molecules (occludin and zonula occludens 1) and increases portal endotoxin levels 4 h after intragastric administration of LPS (20 mg/kg body weight). Furthermore, an increase in the flux of immunoglobulin G into the intestinal lumen was observed 10 days postinfection (PI). An increased rate of LPS absorption was also seen in mice infected with Nippostrongylus brasiliensis on day 14 PI and rats concurrently infected with S. venezuelensis and N. brasiliensis on day 20 PI. On the other hand, infection with Eimeria vermiformis and Eimeria pragensis was not observed to enhance LPS absorption 4 h after intragastric administration of LPS (20 mg/kg body weight), although E. vermiformis infection did inhibit the epithelial cell mRNA expression of zonula occludens 1, but not occludin, on day 9 PI, resulting in a reduced immunoglobulin G flux than that produced by S. venezuelensis infection. Our results suggest that mastocytosis accompanying intestinal nematode infection increases the intestinal absorption of LPS into the portal circulation by suppressing the expression of tight junction molecules.

[Some biochemical parameters in sheep infected with endoparasites (Fasciola spp., Dicrocoelium dendriticum, hydatid cysts, Trichostrongylidae and Protostrongylidae)]. / Endoparazitli (Fasciola spp., Dicrocoelium dendriticum, kist hidatik, Trichostrongylidae ve Protostrongylidae) koyunlarda bazi biyokimyasal parametreler.

This study was performed in order to investigate the variations of some blood biochemical parameters as well as the levels of Vitamin. B(12) and some macro elements in sheep infected with endoparasites. The blood samples were taken from the sheep that were to be slaughtered in the Van Municipality Slaughterhouse while the stool samples were taken after the slaughtering of the same animals. The postmortem examinations were made to investigate for the presence of Fasciola spp., D. dendriticum and cyst hydatid infections. The stool samples were examined helminthologically using native, sedimentation, flotation and Baermann-Wetzel methods. The control group was composed of animals not showing any internal organ parasites or parasites in the stool examination. Following the macroscopic and the stool examination, the animals found to have the same type of parasites were considered to be the study group. According to the analyses performed on the animals, the levels of total protein (in Trichostrongylidae, hydatid cysts), globulin, amylase, chlorine, and Vit.B(12) were found to be increased significantly, while the levels of albumin, magnesium, and phosphorus were found to be decreased significantly. The other parameters analyzed were not significant statistically between the groups.

Biochemical and pathological evaluation of albendazole/thalidomide co-therapy against eosinophilic meningitis or meningoencephalitis induced by Angiostrongylus cantonensis.

OBJECTIVES: To evaluate the curative effect of albendazole/thalidomide co-therapy on eosinophilic meningitis in BALB/c mice caused by Angiostrongylus cantonensis. METHODS: Male mice were infected with 50 A. cantonensis larvae and treated with albendazole (5, 10 or 20 mg/kg per day) alone, thalidomide (25, 50 or 100 mg/kg per day) alone, or a combination of albendazole (10 mg/kg per day) and thalidomide (50 mg/kg per day) for 7 consecutive days on days 5, 10 and 15 post-inoculation (PI), respectively. RESULTS: Indicators used to measure this effect included: (i) worm recovery; (ii) histopathological score of meningitis; (iii) eosinophil counts; (iv) level of pro-inflammatory cytokines, such as tumour necrosis factor-alpha, interleukin-1beta and interleukin-5; (v) activity of enzymes, such as tissue-type plasminogen activator, urokinase-type plasminogen activator and matrix metalloproteinase-9; and (vi) CSF/serum albumin ratio. The results showed that albendazole/thalidomide co-therapy significantly decreased (P < 0.05) these factors when treatment was initiated on days 5 or 10 PI compared with treatment initiated on day 15 PI. CONCLUSIONS: The timing of medication use is important and is closely related to the anthelmintic efficacy of a drug. For a given dosage, earlier medication use is more effective. This novel approach to treating parasitic meningitis may suggest other new methods of treatment.

sICAM-1 in meningoencephalitis due to Angiostrongylus cantonensis / sICAM-1 en meningoencefalitis por Angiostrongylus cantonensis

INTRODUCTION: Angiostrongylus cantonensis meningoencephalitis is an emergent disease in the Americas. METHOD: Twelve children suffering from eosinophilic meningoencephalitis due to this parasite aged between 6-10 years were studied. Cerebrospinal fluid (CSF) and serum samples were taken simultaneously in the first diagnostic puncture at admission. RESULTS: All cases showed typical findings on the routine CSF and serum analysis: increased CSF total protein, increased Q (CSF/serum) albumin accompanied by eosinophilia in CSF. No intrathecal synthesis of immunoglobulins was found. Mean serum and CSF sICAM-1 values were 337.4 and 3.97 ng/mL. Qalbumin and QsICAM-1 mean values were 4.1 and 6.2 respectively. In 50 percent of the patients an increased brain-derived fraction of sICAM-1 was found. CONCLUSION: It may be suggested that a dynamic of the sICAM-1 brain derived fraction is perhaps associated to the immune response in the evolution of the disease.sICAM-1 may be an agent in negative feedback for eosinophils passage through the blood-CSF barrier into the inflammatory brain response.

INTRODUCCION: La meningoencefalitis por Angiostrongylus cantonensis es una enfermedad emergente en las Américas. MÉTODO: Doce niños con meningoencefalitis eosinofílica por Angiostrongylus cantonensis con edades entre 6 y 10 años fueron estudiados. Se tomaron muestras simultáneas de suero y líquido cefalorraquídeo (LCR) en la primera punción lumbar diagnóstica. RESULTADOS: Todos los casos evidenciaron hallazgos típicos en los análisis de rutina del LCR y suero: incremento de proteínas totales, aumento de la razón albúmina Q (LCR/suero) acompañado de eosinofilia en LCR. No se encontró síntesis intratecal de inmunoglobulinas. Los valores medios de sICAM-1 en suero y LCR fueron de 337,4 y 3,97 ng/mL respectivamente. Los valores medios de Q albúmina y Q sICAM-1 fueron de 4,1 y 6,2 respectivamente. En el 50 por ciento de los pacientes se encontró un incremento de la fracción de sICAM-1 derivado del cerebro. CONCLUSION: Se puede sugerir que la dinámica de la fracción sICAM-1 derivada del cerebro ocurre quizas asociada a la respuesta inmune frente a la enfermedad. sICAM-1 puede ser un agente de retroalimentación negativa para el paso de eosinófilos de la sangre a través de la barrera sangre-LCR en el cerebro inflamado.

Purification of a specific immunodiagnostic Parastrongylus cantonensis antigen by electroelution from SDS-polyacrylamide gels.

A 31-kDa glycoprotein antigen was purified by electrophoresing the crude extract of Parastrongylus cantonensis adult worms in a 12% SDS-polyacrylamide gel, identifying the 31-kDa component with prestained molecular weight standards, cutting the desired gel strip, and then isolating it by electroelution. Antigen fraction of 31 kDa was re-electrophoresed, transferred to a nitrocellulose membrane and found to be reactive with only the sera from patients with parastrongyliasis. No reactive band was observed with the sera from other related parasitic infections, eg, gnathostomiasis, toxocariasis, filariasis, paragonimiasis, cysticercosis and malaria, and the normal healthy control sera. This antigen fraction isolated showed 100% sensitivity and 100% specificity in the enzyme-linked immunosorbent assay (ELISA) for the detection of 31-kDa specific antibody in the sera from patients with parastrongyliasis. The P. cantonensis antigen of 31 kDa has been obtained by this means with a high degree of purity and applied successfully in conventional ELISA for the specific immunodiagnosis of human parastrongyliasis.

SCID mice show a similar susceptibility to Angiostrongylus cantonensis as do wild-type mice of the C.B-17 strain.

C.B-17-SCID/SCID (SCID) mice infected with Angiostrongylus cantonensis yielded a high percentage of worm recovery and did not show any body weight loss until day 24 postinfection. Unexpectedly, C.B-17-+/+(+/+) mice also produced a similar worm burden containing well-developed worms. This is probably attributable to the observation that +/+ mice failed to induce eosinophilia in cerebrospinal fluid (CSF) despite their production of antigen-specific IgA and IgGI; +/+ mice have defective bone-marrow eosinopoiesis, which in turn results in reduced blood and CSF eosinophilia. Interleukin 5 (IL-5) production in +/+ mice is similar to that in BALB/c and C57BL/6 mice. However, bone-marrow eosinopoiesis in response to IL-5 is markedly suppressed in +/+ mice. This is probably associated with impaired expression of common beta-chain mRNA in bone-marrow cells of +/+ mice, which leads to the failure of bone-marrow eosinopoiesis. Hence, +/+ mice may serve as a useful model for the elucidation of eosinophil production in the mouse and for determination of the relationship between parasite infection and the eosinophil.

Development of basophils in Mongolian gerbils: formation of basophilic cell clusters in the bone marrow after Nippostrongylus brasiliensis infection.

Development of basophilic leukocytes was studied in the Mongolian gerbil, Meriones unguiculatus, after infection with the nematode Nippostrongylus brasiliensis. After infection, peripheral blood basophilia developed and peaked at 2 weeks. In bone marrow sections, numbers of alcian blue+/safranine- basophilic cells were increased. These cells did not bind berberine sulfate and were clearly distinguishable from the bone marrow-resident mast cells, safranine+ and berberine sulfate+. Alcian blue+/safranine- cells were identified by electron microscopy as basophilic myelocytes in various stages of maturation. In the early period of infection, these cells had round-to-oval granules with a homogenous electron-dense matrix, a well-developed Golgi apparatus and rough endoplasmic reticulum, and a nonsegmented nucleus. By enzyme cytochemical analysis, intense peroxidase activity was demonstrated in all of the specific granules as well as in the rough endoplasmic reticulum and Golgi apparatus. Two weeks after infection, the number of bone marrow basophilic cells further increased, forming distinct clusters or islands composed of up to 100 cells each. On electron micrographs, the basophilic cells in these clusters appeared to be late-stage basophilic myelocytes, ie, having an increased number of granules, a less-conspicuous Golgi apparatus and rough endoplasmic reticulum, a horseshoe-shaped-to-lobulated nucleus, and reduced peroxidase activity. Eosinophils and mast cells were rarely found in the basophilic cell clusters. Four weeks after infection, the clusters had disappeared. These results show that gerbil basophilic myelocytes tend to form cell clusters in the bone marrow during their active proliferation. The comparative paucity of other cell lineages in basophilic cell clusters suggests that basophilia is generated from differentiation/proliferation of precommitted basophil progenitors independently from cells of other lineages.

Detection of circulating antigens of Parastrongylus cantonensis in human sera by dot-blot ELISA and sandwich ELISA using monoclonal antibody.

A dot-blot ELISA was compared with a previously performed sandwich ELISA for the detection of Parastrongylus cantonensis antigens in sera from patients. Using the same monoclonal antibody and the same sera, 6 of 10 sera (60%) from parastronglyiasis patients were positive in dot-blot ELISA, whereas with sandwich ELISA, 5 of the same patient sera (50%) were positive. The specificity in both assays was 100% using 50 sera from patients with other parasitic diseases; of these, 10 each were from patients with cysticercosis, filariasis, gnathostomiasis, malaria and toxocariasis. The control group consisted of 53 sera from normal health Thais and Malaysians. The sensitivity of the assays was, however, slightly better with dot-blot ELISA and because it is simple, quick and cost-effective, it may be a test of choice for specific diagnosis of human parastrongyliasis.

Irradiated larval vaccination and antibody responses evaluated in relation to the expression of immunity to Heligmosomoides polygyrus.

Infections induced in NIH mice by irradiated (300 Gy) larvae of Heligmosomoides polygyrus effectively stimulated immunity to challenge, whereas unirradiated larvae did not. Importantly, this difference was lost by the elimination of the adult worms arising from unirradiated sensitising infections by drug treatment prior to challenge. No difference in the level of parasite-specific serum and mucosal IgG, IgG1, IgG2a, or IgA was detected between immune mice sensitised either with drug-abbreviated unirradiated or irradiated larval infections and non-immune mice receiving two superimposed unirradiated infections. An enzyme-linked immunosorbent assay (ELISA) and immunoblotting data suggested that parasite-specific IgG1 was the predominant antibody class in both serum and intestinal perfusates. IgA exhibited differences in antigen specificity between the serum and the intestine. In serum, IgA responses were directed predominantly to L4 somatic antigens, whereas at the mucosal surface they were biased towards L4 excretory/secretory (ES) antigens. No correlation was found between the intensity of the serum or mucosal antibody responses and the mean worm burdens in groups of immune or non-immune mice. Moreover, no correlation was found between levels of parasite-specific serum or mucosal IgG, IgG1, IgG2a or IgA and the loss of worms in individual mice.

Infection with Nippostrongylus brasiliensis induces invasion of mast cell precursors from peripheral blood to small intestine.

Precursors of mast cells were defined as cells that formed mast-cell colonies in methylcellulose culture (CFU-mast). Mononuclear cells (MNC) were obtained from the bone marrow, peripheral blood, and small intestine of Ws/Ws rats with a small deletion at the tyrosine kinase domain of c-kit and of control normal (+/+) rats. In the culture containing concanavalin A-stimulated spleen cell conditioned medium (ConA-SCM) alone, the numbers of mast-cell colonies produced by Ws/Ws MNC were comparable with those of +/+ MNC. In the culture containing both ConA-SCM and stem cell factor (a ligand of c-kit), however, the numbers of mast-cell colonies produced by +/+ blood MNC were 107 times as great as that of Ws/Ws blood MNC. Using this culture condition, we investigated changes in concentration of CFU-mast in the marrow, blood, and intestine of +/+ rats after infection with Nippostrongylus brasiliensis (NB), which induced marked mast-cell accumulation in the small intestine. The concentration of CFU-mast in blood dropped to 21% of preinfection levels 1 week after the NB infection. In contrast, a sevenfold increase of CFU-mast occurred in the small intestine. The proportion of CFU-mast in S phase of the cell cycle remained at low levels in the marrow and blood after NB infection, but it increased significantly in the small intestine. The present result suggests that NB infection induces the invasion of CFU-mast into the intestine from blood and their subsequent proliferation in the tissue site.

Mucosal mast cell proliferation following normal and heterotopic infections of the nematode Nippostrongylus brasiliensis in rats.

Infections of intestinal nematodes induce the T cell-dependent proliferation of intestinal mucosal mast cells (MMC). To examine whether nematode-induced MMC proliferation is affected by the site of infestation, adult-stage nematode Nippostrongylus brasiliensis (NB) was transplanted into the normal infection site, the duodenum, or into heterotopic sites, the peritoneal cavity (i.p.) or subcutaneous tissue (s.c.), of rats. Two weeks after duodenal inoculation, MMC numbers in the small intestine had increased 6.5-fold. In contrast, i.p. and s.c. inoculation induced only slight increases of intestinal MMC. After i.p. inoculation, worm granulomas developed in the connective tissues adhering to stomach and duodenum, and large numbers of mast cells appeared around the granulomas. The majority of the latter mast cells showed histochemical features similar to MMC: they were formalin sensitive, berberine sulfate-, alcian blue+/safranine-, and rat mast cell protease (RMCP) II+. After s.c. inoculation, worm granulomas developed at the inoculation site, but the number of mast cells around the granulomas was not significantly increased. These results suggest that intense proliferation of MMC or MMC-like cells is induced only by the infections on mucosa or in mucosa-associated tissues.

Effects of estradiol on worm burden and peripheral leukocytes in Parastrongylus malaysiensis-infected rats.

Gonadectomized male laboratory rats were given 0.06 mg/kg estradiol benzoate daily for 14 days before being inoculated with 50 third-stage larvae of Parastrongylus malaysiensis. Hormone treatment was continued until the rats were killed. The numbers of larvae in the brain and of adult worms in the pulmonary area of the rats were determined every 7 days after the inoculation. It was found that the rats treated daily with estradiol benzoate had significantly and consistently higher numbers of larvae and adult worms as compared with the controls. The number of total leukocytes increased significantly after the rats were infected. The results show that estradiol-treated rats become susceptible to P. malaysiensis infection, which may indicate that the immunosuppressive effects of testosterone observed in earlier studies may partly be caused by estradiol that was peripherally aromatized from testosterone.