Parasitic worms and allergies in childhood: insights from population studies 2008-2013

Resurgence of intestinal ascariasis among adults: radiological diagnosis and clinical implications

To report the radiological features of intestinal ascariasis and to review the clinical implications of this re-emerging disease for adult population of the USA. This retrospective observational study involved 12 adult patients, whose radiological examinations disclosed unsuspected presence of ascaris in their intestinal tract. They were evaluated by computed tomography of the abdomen with oral contrast, small bowel series with barium, and magnetic resonance enterography. This series included 7 men and 5 women, who ranged in age from 19 to 72 years (mean age 48 years). The typical configuration of ascaris within the bowel loops was demonstrated on CT of the abdomen in 5 patients, small bowel examination with barium in 3, and by MR enterography in another 4 cases. Our study highlights the radiological appearances of intestinal ascariasis and the clinical implications of this resurging disease. The practicing radiologists should be aware of these findings, particularly when examining patients who have immigrated from or traveled to the endemic regions.

Cellular immune response of asthmatic children in the presence of anti-Ascaris antibody

The presence of anti-Ascaris (anti-Asc) immunoglobin isotypes alters the risk of allergic asthma. In this study, we analyzed the relationships between serum levels of anti-Asc IgE, IgG1, and IgG4, without concurrent infection by the parasite, and the presence of asthma. We measured cytokine levels from Th1, Th2, and Th17 profiles. Children aged 2-14 years old, asthmatics (n = 64), and non-asthmatics (n = 40) were selected according to the International Study of Asthma and Allergies in Childhood criteria. Asthmatic patients who had positive skin allergy tests were considered to have allergic asthma. Stool exams were performed to exclude children who were parasitized by helminths/protozoans and blood samples were collected in non-parasitized individuals. We performed peripheral blood leukocyte counts and in vitro culture following mitogenic stimulation. Levels of cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, and IL-17) in the supernatants were measured using a cytometric bead array. Titration of serum total IgE and IgE specific to Ascaris were obtained using ImmunoCAP; IgG1 and IgG4 titers were measured using enzyme-linked immunosorbent assays. Anti-Asc IgE was associated with a higher risk of asthma and an increase in the number of eosinophils and neutrophils. By contrast, anti-Asc IgG1 could be considered a protective factor against asthma, associated with lower levels of circulating neutrophils. There were high levels of IL-6 and TNF-α in asthmatics. Levels of IL-6, but not TNF-α, depended on the presence of anti-Asc IgG1 in serum. Anti-Asc IgE appears to increase risk of asthma, and anti-Asc IgG1 appears to favor decreased neutrophil counts and increased IL-6 levels.

Helminth-Bacterial Interactions: Cause and Consequence

Intestinal helminths, along with mutualistic microbes, have cohabited the intestine of mammals throughout evolution. Interactions between helminths, bacteria, and their mammalian hosts may shape not only host-helminth and host-microbiome interactions, but also the relationship between helminths and the microbiome. This 'ménage à trois' situation may not be completely balanced in that it may favor either the host or the parasite, possibly at the cost of the other partner. Similarly, helminths may favor the establishment of a particular microbiome with either positive or negative consequences for the overall health and well-being of the host. Recent studies indicate that infection with intestinal helminths can and does impact the intestinal microbiome, with important consequences for each partner in this tripartite relationship.

Asthma and Seroconversion from Toxocara spp. Infection: Which Comes First?

The aim of this study was to estimate the incidence of seroconversion of Toxocara spp. infection and related variables. We conducted a cohort study of 77 children aged 2-12 years who had negative serology in a previous cross-sectional study. Univariate and bivariate analyses were performed to describe the cohort, using socioeconomic, behavioral, and health conditions as variables. Logistic regression analysis was performed using seroconversion as the dependent variable, and the remaining variables are treated as independent variables. Asthma was the only independent variable that showed an association with seroconversion, with an odds ratio = 3.57 (1.01-12.6). The incidence of seroconversion from Toxocara spp. infection in the children followed was 10.4 per 100 per year. Previous studies reporting an association of asthma with toxocariasis have only been carried out using cross-sectional studies. Therefore, this study is one of only a few describing the incidence of seroconversion from Toxocara spp. infection, which is relevant for understanding the burden of this parasite.

Perennial aeroallergens sensitisation and risk of asthma in African children and adolescents: a case-control study

OBJECTIVES

The distribution and impact of various aeroallergens on asthma occurrence vary across regions. We investigated the association between sensitisation to perennial aeroallergens and asthma risk in children and adolescents in Yaounde, Cameroon.

METHODS

This was a case-control study involving children and adolescents with asthma (cases) vs. non-allergic counterparts (controls). Children/adolescents with doctor-diagnosed asthma were included over a period of 30 months, and controls were selected from the community through random sampling. Logistic regression models were used to relate perennial aeroallergens sensitisation with asthma.

RESULTS

The asthma and control groups included, respectively, 151 and 372 participants, with no sex ratio difference. The mean age (standard deviation) was 11.9 (4.4) years in cases and 11.3 (3.7) years in controls. The prevalence of sensitisation to any aeroallergen (cases vs. controls) was 76.8% (116/151) and 32.3% (120/372), p < 0.001. Sensitisation to mites was found in 104 (68.9%) cases vs. 56 (15.1%) controls, p < 0.001. In multivariable analysis, sensitisation to Alternaria alternata, Blattella germanica and dander (cat and dog) was not associated with asthma. However, sensitisation to mites was significantly associated with asthma. Odds ratios (95% CI) for sensitisation to Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis in relation with asthma were 7.28 (3.75-14.15), 2.65 (1.27-5.45) and 3.23 (1.68-6.21), respectively.

CONCLUSIONS

Sensitisation to mites was the main perennial allergenic factor associated with asthma in children and adolescents in this setting. This has application for the selection of patients with asthma who could benefit from the control of exposure to mites and specific immunotherapy.

Secretory Products of Trichinella spiralis Muscle Larvae and Immunomodulation: Implication for Autoimmune Diseases, Allergies, and Malignancies

Trichinella spiralis has the unique ability to make itself "at home" by creating and hiding in a new type of cell in the host body that is the nurse cell. From this immunologically privileged place, the parasite orchestrates a long-lasting molecular cross talk with the host through muscle larvae excretory-secretory products (ES L1). Those products can successfully modulate parasite-specific immune responses as well as responses to unrelated antigens (either self or nonself in origin), providing an anti-inflammatory milieu and maintaining homeostasis. It is clear, based on the findings from animal model studies, that T. spiralis and its products induce an immunomodulatory network (which encompasses Th2- and Treg-type responses) that may allow the host to deal with various hyperimmune-associated disorders as well as tumor growth, although the latter still remains unclear. This review focuses on studies of the molecules released by T. spiralis, their interaction with pattern recognition receptors on antigen presenting cells, and subsequently provoked responses. This paper also addresses the immunomodulatory properties of ES L1 molecules and how the induced immunomodulation influences the course of different experimental inflammatory and malignant diseases.

Immune responses in children infected with the pinwormEnterobius vermicularisin central Greece

Previous studies have suggested an immunomodulatory and even protective role forEnterobius vermicularis, the least pathogenic human intestinal helminth. Here, in a study using haematological and serological parameters, we tested a total of 215 children from central Greece, with a mean age of 8.39, of whom 105 (48.84%) were infected withE. vermicularisand 110 (51.16%) were matched healthy controls. In particular, we analysed eosinophil counts (EO), serum eosinophil cationic protein (ECP), total and specific serum immunoglobulin E (IgE) and the ECP/EO ratio. The atopic status and the potential occurrence of clinically expressed allergic diseases were both taken into account. Eosinophils, ECP and IgE were found to be higher in infected than in uninfected children, indicating a type-2 immune response activation during infection. Atopic infected children exhibited higher IgE levels compared to non-atopic ones. EO and ECP were found to be lower in atopic children who had a history of allergic disease than in those with no such history. The type-2 oriented immune response elicited againstE. vermiculariscould contribute to a balanced activation of the immune system in the examined children. Interestingly, although the atopic children showed a stronger activation, they did not exhibit any symptoms and, moreover, there seemed to be some indication of immunosuppression in those children with a positive history of allergic disease.

Neonatal exposure to pneumococcal phosphorylcholine modulates the development of house dust mite allergy during adult life

Currently, ∼20% of the global population suffers from an allergic disorder. Allergies and asthma occur at higher rates in developed and industrialized countries. It is clear that many human atopic diseases are initiated neonatally and herald more severe IgE-mediated disorders, including allergic asthma, which is driven by the priming of Th2 effector T cells. The hygiene hypothesis attempts to link the increased excessively sanitary conditions early in life to a default Th2 response and increasing allergic phenomena. Despite the substantial involvement of IgE Abs in such conditions, little attention has been paid to the effects of early microbial exposure on the B cell repertoire prior to the initiation of these diseases. In this study, we use Ab-binding assays to demonstrate that Streptococcus pneumoniae and house dust mite (HDM) bear similar phosphorylcholine (PC) epitopes. Neonatal C57BL/6 mice immunized with a PC-bearing pneumococcal vaccine expressed increased frequencies of PC-specific B cells in the lungs following sensitizing exposure to HDM as adults. Anti-PC IgM Abs in the lung decreased the interaction of HDM with pulmonary APCs and were affiliated with lowered allergy-associated cell infiltration into the lung, IgE production, development of airway hyperresponsiveness, and Th2 T cell priming. Thus, exposure of neonatal mice to PC-bearing pneumococci significantly reduced the development of HDM-induced allergic disease during adult life. Our findings demonstrate that B cells generated against conserved epitopes expressed by bacteria, encountered early in life, are also protective against the development of allergic disease during adult life.

Regulatory T cells in early life: comparative study of CD4+CD25high T cells from foals and adult horses

The immune system of mammals is subject to continuous development during the postnatal phase of life. Studies following the longitudinal development of the immune system in healthy children are limited both by ethical considerations and sample volumes. Horses represent a particular valuable large animal model for T regulatory (Treg) cells and allergy research. We have recently characterised Treg cells from horses, demonstrated their regulatory capability and showed both their expansion and induction in vitro. Insect bite hypersensitivity (IBH) is a common allergy in horses resembling atopic dermatitis and studies have shown that first exposure to allergens in adult life results in an increased incidence of IBH. The aim of the present study was to characterize circulating CD4⁺CD25^highFoxP3⁺cells in foals, evaluate their suppressive capability and their in vitro induction compared to adult horses. 19 foals (age range, 1–5 months), their adult mothers and six one-year-old horses (yearlings) were included in the study. The proportion of FoxP3⁺ cells within the circulating CD4⁺CD25^high population was significantly higher in foals (47%) compared to their mothers (18%) and to yearlings (26%). Treg cells from foals also displayed a higher suppressive capability. Furthermore, CD4⁺CD25^high cells in foals could be induced in vitro from CD4⁺CD25⁻ cells in a significantly higher proportion compared to mares. These cells also displayed a significantly enhanced suppressive capability. In summary these findings support the notion that exposure of horses to allergens during maturation of the immune system assists the establishment of induced (i)Treg driven tolerance.

Helminth infections decrease host susceptibility to immune-mediated diseases

Helminthic infection has become rare in highly industrialized nations. Concurrent with the decline in helminthic infection has been an increase in the prevalence of inflammatory disease. Removal of helminths from our environment and their powerful effects on host immunity may have contributed to this increase. Several helminth species can abrogate disease in murine models of inflammatory bowel disease, type 1 diabetes, multiple sclerosis, and other conditions. Helminths evoke immune regulatory pathways often involving dendritic cells, regulatory T cells, and macrophages that help to control disease. Cytokines, such as IL-4, IL-10, and TGF-β, have a role. Notable is the helminthic modulatory effect on innate immunity, which impedes development of aberrant adaptive immunity. Investigators are identifying key helminth-derived immune modulatory molecules that may have therapeutic usefulness in the control of inflammatory disease.