Immune reactions and allergy in experimental anisakiasis

Anisakis pegreffii Extract Induces Airway Inflammation with Airway Remodeling in a Murine Model System

Exposure of the respiratory system to the Anisakis pegreffii L3 crude extract (AE) induces airway inflammation; however, the mechanism underlying this inflammatory response remains unknown. AE contains allergens that promote allergic inflammation; exposure to AE may potentially lead to asthma. In this study, we aimed to establish a murine model to assess the effects of AE on characteristic features of chronic asthma, including airway hypersensitivity (AHR), airway inflammation, and airway remodeling. Mice were sensitized for five consecutive days each week for 4 weeks. AHR, lung inflammation, and airway remodeling were evaluated 24 h after the last exposure. Lung inflammation and airway remodeling were assessed from the bronchoalveolar lavage fluid (BALF). To confirm the immune response in the lungs, changes in gene expression in the lung tissue were assessed with reverse transcription-quantitative PCR. The levels of IgE, IgG1, and IgG2a in blood and cytokine levels in the BALF, splenocyte, and lung lymph node (LLN) culture supernatant were measured with ELISA. An increase in AHR was prominently observed in AE-exposed mice. Epithelial proliferation and infiltration of inflammatory cells were observed in the BALF and lung tissue sections. Collagen deposition was detected in lung tissues. AE exposure increased IL-4, IL-5, and IL-13 expression in the lung, as well as the levels of antibodies specific to AE. IL-4, IL-5, and IL-13 were upregulated only in LLN. These findings indicate that an increase in IL-4+ CD4+ T cells in the LLN and splenocyte resulted in increased Th2 response to AE exposure. Exposure of the respiratory system to AE resulted in an increased allergen-induced Th2 inflammatory response and AHR through accumulation of inflammatory and IL-4+ CD4+ T cells and collagen deposition. It was confirmed that A. pegreffii plays an essential role in causing asthma in mouse models and has the potential to cause similar effects in humans.

Identification of Helminth Parasites from Selar crumenophthalmus in Grenada, West Indies

HIGHLIGHTS

Helminths in Selar crumenophthalmus fish were identified by PCR. Two helminth taxa were identified: Anisakis typica and an unknown acanthocephalan. Neither taxon of helminth identified is zoonotic. To our knowledge, this is the first report of either type of helminth in fish in Grenada.

Short-term in vitro culture of purity and highly functional rat bone marrow-derived mast cells

Mast cells (MCs) are responsible for the innate immune response. Rat MCs are more suitable than mouse MCs as models of specific parasite infection processes and ovalbumin-induced asthma. Rat peritoneum-derived MCs and RBL-2H3 cells (an MC cell line) are widely used in disease studies. However, the application of rat bone marrow-derived MCs (BMMCs) are poorly documented in terms of the methodology of rat BMMC isolation. Here, we describe a relatively rapid, efficient, and simple method for the cultivation of rat BMMCs. As compared to previous protocols, rat BMMCs produced with the proposed protocol exhibited advantages in differentiation, proliferation, lifespan, and functionality, which should prove useful for studies of mucosal MC diseases in specific rat models.

The development of methods for primary mast cells in vitro and ex vivo: An historical review

Mast cells (MCs) are tissue-based stationary effector cells that form the immune system's first-line defense against various challenges. They are developed from the bone marrow-derived progenitors to complete their differentiation and maturation in the tissues where they eventually establish residence. MCs have been implicated in many diseases, such as allergy, parasitic infection, and neoplastic disorders. Immortalized MC lines, such as RBL-2H3, HMC-1, and LAD-2, are useful for investigating the biological functions of MC only to some extents due to the restriction of degranulation evaluation, in vivo injection and other factors. Over the past few decades, technologies for acquiring primarily MCs have been continually optimized, and novel protocols have been proposed. However, no relevant publications have analyzed and summarized these techniques. In this review, the classical approaches for extracting MCs are generalized, and new methods with potential values are introduced. We also evaluate the advantages and applicability of diverse MC models. Since MCs exhibit substantial plasticity and functional diversity due to different origins, it is both necessary and urgent to select a reliable and suitable source of MCs for a particular study.

Anisakis - immunology of a foodborne parasitosis

Anisakis species are marine nematodes which can cause zoonotic infection in humans if consumed in raw, pickled or undercooked fish and seafood. Infection with Anisakis is associated with abdominal pain, nausea and diarrhoea and can lead to massive infiltration of eosinophils and formation of granulomas in the gastrointestinal tract if the larvae are not removed. Re-infection leads to systemic allergic reactions such as urticarial or anaphylaxis in some individuals, making Anisakis an important source of hidden allergens in seafood. This review summarizes the immunopathology associated with Anisakis infection. Anisakiasis and gastroallergic reactions can be prevented by consuming only fish that has been frozen to -20°C to the core for at least 24 hours before preparation. Sensitization to Anisakis proteins can also occur, primarily due to occupational exposure to infested fish, and can lead to dermatitis, rhinoconjunctivitis or asthma. In this case, exposure to fish should be avoided.

Allergenic activity of Pseudoterranova decipiens (Nematoda: Anisakidae) in BALB/c mice

BACKGROUND

Anisakis simplex is the only fishery-product associated parasite causing clinical allergic responses in humans so far. However, other anisakids, due to the presence of shared or own allergens, could also lead to allergic reactions after sensitization. The aim of this study was to determine if Pseudoterranova decipiens belonging to the family Anisakidae has allergenic activity and is able to induce sensitization after oral administration in a murine (BALB/c mice) model.

RESULTS

The ingestion of A. pegreffii proteins by BALB/c mice, which had been previously sensitized by intraperitoneal inoculation with the corresponding live L3 larvae, triggers signs of allergy within 60 min, whereas P. decipiens did to a lesser extent. Beside symptoms, allergic reactions were furtherly supported by the presence of histamine in sera of sensitized mice. Specific IgG1 and IgE responses were detected in sera of all sensitized mice from week four. Specific IgG2a response was detected in sera from mice sensitized to P. decipiens. After polyclonal or specific activation with anti-CD3/anti-CD28 or antigens, respectively, splenocytes from mice infected i.p. with A. pegreffii or P. decipiens larvae showed significantly higher production of IL-10 than naïve mice. After stimulation with specific antigens, significantly higher IL-5 and IL-13 amounts were produced by specific antigen stimulated splenocytes than by the naïve cells; only P. decipiens proteins induced IFN-ɣ.

CONCLUSIONS

The overall results suggest that infection with P. decipiens can sensitize mice to react to subsequent oral challenge with anisakid proteins, as described for A. simplex (sensu stricto) and A. pegreffii infections. The results show that anisakid proteins induce a dominant Th2 response, although P. decipiens could also induce a mixed type 1/type 2 pattern.

Resposta imunológica a antígenos de Hysterothylacium deardorffoverstreetorum de peixes teleósteos

RESUMO Anisaquidose é uma doença provocada por parasitos da família Anisakidae e se caracteriza por manifestações gastrointestinais e alérgicas. O Anisakis simplex é o parasito mais patogênico ao homem e altamente alergênico. Porém, outros anisaquídeos também são danosos aos humanos, mas é desconhecida a imunogenicidade dessas larvas. O objetivo deste trabalho foi avaliar o potencial imunogênico do parasito Hysterothylacium deardorffoverestreetorum (HD) em modelo murino. Camundongos da linhagem BALB/c foram divididos em três grupos experimentais e receberam as preparações antigênicas obtidas de larvas de HD: extrato bruto de larvas (EBH), extrato secretado/ excretado de larvas (ESH) e extrato bruto de larvas após excreção/secreção (EEH). Amostras séricas foram obtidas em diferentes dias após imunização para determinação dos níveis de anticorpos específicos pelo ensaio imunoenzimático (ELISA). Os resultados demonstram aumento na produção de imunoglobulina (Ig) G após a segunda imunização, com aumento progressivo após a terceira imunização. Já em relação à IgE, a reatividade foi mais tardia, demonstrando aumento progressivo após a terceira imunização. Foi avaliada a imunidade celular por meio da intradermorreação, como resultado estatisticamente significativo em relação ao controle utilizado. Este experimento é a primeira descrição da potencialidade patogênica desse parasito em mamíferos e representa um avanço no diagnóstico da anisaquidose humana.

Changes over Time in IgE Sensitization to Allergens of the Fish Parasite Anisakis spp

BACKGROUND

Sensitization to Anisakis spp. can produce allergic reactions after eating raw or undercooked parasitized fish. Specific IgE is detected long after the onset of symptoms, but the changes in specific IgE levels over a long follow-up period are unknown; furthermore, the influence of Anisakis spp. allergen exposure through consumption of fishery products is also unknown.

OBJECTIVE

To analyse the changes in IgE sensitization to Anisakis spp. allergens over several years of follow-up and the influence of the consumption of fishery products in IgE sensitization.

METHODS

Total IgE, Anisakis spp.-specific IgE, anti-Ani s 1 and anti-Ani s 4 IgE were repeatedly measured over a median follow-up duration of 49 months in 17 sensitized patients.

RESULTS

Anisakis spp.-specific IgE was detected in 16/17 patients throughout the follow-up period. The comparison between baseline and last visit measurements showed significant decreases in both total IgE and specific IgE. The specific IgE values had an exponential or polynomial decay trend in 13/17 patients. In 4/17 patients, an increase in specific IgE level with the introduction of fish to the diet was observed. Three patients reported symptoms after eating aquaculture or previously frozen fish, and in two of those patients, symptom presentation was coincident with an increase in specific IgE level.

CONCLUSIONS

IgE sensitization to Anisakis spp. allergens lasts for many years since specific IgE was detectable in some patients after more than 8 years from the allergic episode. Specific IgE monitoring showed that specific IgE titres increase in some allergic patients and that allergen contamination of fishery products can account for the observed increase in Anisakis spp.-specific IgE level.

CLINICAL RELEVANCE

Following sensitization to Anisakis spp. allergens, the absence of additional exposure to those allergens does not result in the loss of IgE sensitization. Exposure to Anisakis spp. allergens in fishery products can increase the specific IgE level in some sensitized patients.

Experimental anisakid infections in mice

Anisakidosis is a human parasitic disease caused by infections with members of the Anisakidae family. Accidental infection after fish intake affects the gastrointestinal tract as a consequence of mechanical damage caused by migrating larvae. Infections can also trigger allergies, hives, severe asthma or anaphylaxis with angioedema. Although mouse models of intraperitoneal antigenic stimulation exist, enabling immunological studies, few models using gastric introduction of live larvae are available for the study of immunological and gastrointestinal damage in mice. This study was designed to characterize serum reactivity against Anisakis spp. and Contracaecum spp. in Balb/c mice following orogastric inoculation and to assess gastrointestinal damage. These anisakid species were classified at the Universidade Federal Fluminense (UFF) School of Veterinary Medicine and materials for live larval inoculation were developed at the UFF Immunobiology laboratory. Live larvae were inoculated following injection with a NaCl solution. Blood samples were collected and sera screened for immunoglobulin (Ig)E and IgG anti-larva responses to both nematodes, specific for somatic and excretory/secretory antigens, by enzyme-linked immunosorbent assay (ELISA). The means of the optical densities were analysed using analysis of variance (ANOVA) with Tukey's post-hoc test and the general linear model. This analysis identified the presence of anti-IgG seroreactivity to both somatic and excretory/secretory Anisakis antigens in inoculated animals compared with controls (P< 0.001), and no gastric or intestinal damage was observed. These experiments demonstrated that introduction of live Contracaecum spp. into the gastrointestinal tract did not elicit serum sensitization in animals.

Mitochondrial genomes of Anisakis simplex and Contracaecum osculatum (sensu stricto)--comparisons with selected nematodes

Anisakid nematodes parasitize mainly fish, marine mammals and/or fish-eating birds, and can be transmitted to a range of fish-eating mammals, including humans, where they can cause gastrointestinal disease linked to larval infection or allergic responses. In spite of the animal and human health significance of these parasites, there are still gaps in our understanding of the systematics, biology, epidemiology and ecology of anisakids. Mitochondrial (mt) DNA provides useful genetic markers for investigations in these areas, but complete mt genomic data have been lacking for most anisakids. In the present study, the mt genomes of Anisakis simplex sensu stricto and Contracaecum osculatum sensu stricto were amplified from genomic DNA by long-range polymerase chain reaction and sequenced using 454 technology. The circular mt genomes of these species were 13,926 and 13,823 bp, respectively, and each of them contained 12 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes consistent for members of the Ascaridida, Oxyurida, Spirurida, Rhabditida and Strongylida. These mt genomes provide a stepping-stone for future comparative analyses of a range of anisakids and a basis for reinvestigating their genetic relationships. In addition, these markers might be used in prospecting for cryptic species and exploring host affiliations.

A rat model of intragastric infection with Anisakis spp. live larvae: histopathological study

Anisakiasis is a fish-borne parasitic disease caused by consumption of raw or undercooked fish or cephalopods parasited by Anisakis spp. third stage larvae. The pathological effects of the infection are the combined result of the mechanical action of the larva during tissue invasion, the direct tissue effects of the excretory/secretory products released by the parasite, and the complex interaction between the host immune system and the Anisakis antigens. The aim of this study was to develop an experimental model of infection with Anisakis spp. live larvae in rats, useful to study the acute and chronic histopathological effects of the Anisakis infection. Sprague-Dawley rats were subjected to esophageal catheterization to place larvae directly into the stomach. Reinfections at different intervals after the first infection were preformed. Live larvae were found anchored to the mucosa and passing through the wall of the stomach and showed a strong resistance being able to stay alive at different sites and at the different pH. Migration of larvae from the stomach to other organs out of the gastrointestinal tract was also observed. The histopathological study showed the acute inflammatory reaction, with predominance of polymorphonuclear eosinophils and a mild fibrotic reaction. The model of infection described is valid to study the behavior of the larvae inside the host body, the histopathological changes at the invasion site, and the effects of the repeated infections by ingestion of live larvae.

Parasite excretory-secretory proteins elicit TRIF dependent CXCL1 and IL-6 mediated allergic inflammation

Currently, little information is available regarding innate immunity to helminthic parasite infection. In this study, we isolated the excretory-secretory (ES) proteins from Anisakis simplex (sea mammal intestinal parasite) third stage larva. We determined that the levels of IL-17 in the lung and lung draining lymph node of mice were increased sixfold as a result of intranasal treatment with ES proteins. The ES protein treatment elicited pro-inflammatory cytokine and chemokine secretion (especially IL-6 and CXCL1) from mouse lung epithelial cell line and primary lung epithelial cells. In addition, the expression of IL-6 and CXCL1 in mouse embryonic fibroblast (MEF) cells was significantly increased by the ES protein treatment, but we did not detect these effects in the TRIF(-/-) MEF cells. These elevations of IL-6 and CXCL1 expression were also not diminished by RNase treatment. In conclusion, the ES proteins of helminthic parasite larva may elicit TRIF dependent pro-inflammatory cytokines, and this is not double-stranded RNA.

Effects of IL-3 and SCF on Histamine Production Kinetics and Cell Phenotype in Rat Bone Marrow-derived Mast Cells

BACKGROUND

Rat mast cells were regarded as a good model for mast cell function in immune response.

METHODS

Rat bone marrow mast cells (BMMC) were prepared both by recombinant rat IL-3 (rrIL-3) and by recombinant mouse stem cell factor (rmSCF), and investigated for both proliferation and differentiation in time course. Rat BMMC was induced by culture of rat bone marrow cells (BMCs) in the presence of both rrIL-3 (5 ng/ml) and rmSCF (5 ng/ml). Culture media were changed 2 times per week with the cell number condition of 5x10(4)/ml in 6 well plate. Proliferation was analyzed by cell number and cell counting kit-8 (CCK-8) and differentiation was by rat mast cell protease (RMCP) II and histamine.

RESULTS

Cell proliferation rates reached a maximum at 8 or 11 days of culture and decreased thereafter. However, both RMCP II production and histamine synthesis peaked after 11 days of culture. By real time RT-PCR, the level of histidine decarboxylase mRNA was more than 500 times higher on culture day 11 than on culture day 5. By transmission electron microscopy, the cells were heterogeneous in size and contained cytoplasmic granules. Using gated flow cytometry, we showed that cultured BMCs expressed high levels of FcepsilonRI and the mast cell antigen, ganglioside, on culture day 11.

CONCLUSION

These results indicate that rat BMMCs were generated by culturing BMCs in the presence of rrIL-3 and rmSCF and that the BMMCs have the characteristics of mucosal mast cells.

The Anisakis simplex Ani s 7 major allergen as an indicator of true Anisakis infections

Ani s 7 is currently the most important excretory/secretory (ES) Anisakis simplex allergen, as it is the only one recognized by 100% of infected patients. The allergenicity of this molecule is due mainly to the presence of a novel CX(17-25)CX(9-22)CX(8)CX(6) tandem repeat motif not seen in any previously reported protein. In this study we used this allergen as a model to investigate how ES allergens are recognized during Anisakis infections, and the usefulness of a recombinant fragment of Ani s 7 allergen (t-Ani s 7) as a marker of true Anisakis infections. The possible antigenic relationship between native Ani s 7 (nAni s 7) from Anisakis and Pseudoterranova decipens antigens was also investigated. Our results demonstrate that nAni s 7 is secreted and recognized by the immune system of rats only when the larvae are alive (i.e. during the acute phase of infection), and that this molecule is not present in, or is antigenically different from, Pseudoterranova allergens. The t-Ani s 7 polypeptide is a useful target for differentiating immunoglobulin E antibodies induced by true Anisakis infections from those induced by other antigens that may cross-react with Anisakis allergens, including P. decipiens. The results also support the hypothesis that the Ani s 7 major allergen does not participate in maintaining the antigenic stimulus during chronic infections.