Allergic reactivity and socio-economic level in a tropical environment

Intestinal Helminth Infection Impairs Oral and Parenteral Vaccine Efficacy

The impact of endemic parasitic infection on vaccine efficacy is an important consideration for vaccine development and deployment. We have examined whether intestinal infection with the natural murine helminth Heligmosomoides polygyrus bakeri alters Ag-specific Ab and cellular immune responses to oral and parenteral vaccination in mice. Oral vaccination of mice with a clinically relevant, live, attenuated, recombinant Salmonella vaccine expressing chicken egg OVA (Salmonella-OVA) induced the accumulation of activated, OVA-specific T effector cells rather than OVA-specific regulatory T cells in the GALT. Intestinal helminth infection significantly reduced Th1-skewed Ab responses to oral vaccination with Salmonella-OVA. Activated, adoptively transferred, OVA-specific CD4+ T cells accumulated in draining mesenteric lymph nodes of vaccinated mice, regardless of their helminth infection status. However, helminth infection increased the frequencies of adoptively transferred OVA-specific CD4+ T cells producing IL-4 and IL-10 in the mesenteric lymph node. Ab responses to the oral Salmonella-OVA vaccine were reduced in helminth-free mice adoptively transferred with OVA-specific CD4+ T cells harvested from mice with intestinal helminth infection. Intestinal helminth infection also significantly reduced Th2-skewed Ab responses to parenteral vaccination with OVA adsorbed to alum. These findings suggest that vaccine-specific CD4+ T cells induced in the context of helminth infection retain durable immunomodulatory properties and may promote blunted Ab responses to vaccination. They also underscore the potential need to treat parasitic infection before mass vaccination campaigns in helminth-endemic areas.

Helminth infections and allergic diseases: systematic review and meta-analysis of the global literature

INTRODUCTION

There is considerable research interest in the role of helminth infections in the development of allergic diseases. However, findings from previous studies are mixed. Existing systematic reviews of these studies are outdated. We performed a systematic review of the global literature on the association between helminth infections and development and clinical outcomes of allergic diseases.

METHODS

We searched Cochrane Library, MEDLINE, EMBASE, ISI Web of Science, PubMed, Global Index Medicus, Scielo, KoreaMed, Google Scholar, and Lilacs for studies published up to January 2020. We included observational epidemiological studies (cohort, case-control and cross-sectional studies) of children and adults reporting associations between helminth infections and asthma, allergic rhinitis, eczema and atopy. We performed random-effects meta-analysis to summarize the effect estimates.

RESULTS

We included 80 studies with 99,967 participants. In the meta-analyses, we did not observe an overall association between helminth infections and allergic diseases. There was, however, evidence that A. lumbricoides infections was associated with an increased risk of bronchial hyperreactivity in children (RR:1.41, 95%CI: 1.17-1.70; I²=50, p for I²=0.09), and was associated with an increased risk of atopy among helminth-infected adults (RR:1.37, 95%CI: 1.18-1.61; I²=52, p for I²=0.02). We found no study that addressed the association between helminth infection and clinical outcomes of allergic diseases. The overall strength of the underlying evidence was low to moderate.

CONCLUSION

Helminth infections may increase the risk of bronchial hyperreactivity in children and atopy in adults. Well-designed longitudinal cohorts may help clarify potential causal associations between chronic helminth infections and allergic diseases.

What Can Parasites Tell Us About the Pathogenesis and Treatment of Asthma and Allergic Diseases

The same mechanisms that enable host defense against helminths also drive allergic inflammation. This suggests that pathomechanisms of allergic diseases represent evolutionary old responses against helminth parasites and that studying antihelminth immunity may provide insights into pathomechanisms of asthma. However, helminths have developed an intricate array of immunoregulatory mechanisms to modulate type 2 immune mechanisms. This has led to the hypothesis that the lack of helminth infection may contribute to the rise in allergic sensitization in modern societies. Indeed, the anti-inflammatory potential of helminth (worm) parasites and their products in allergy and asthma has been recognized for decades. As helminth infections bring about multiple undesired effects including an increased susceptibility to other infections, intended helminth infection is not a feasible approach to broadly prevent or treat allergic asthma. Thus, the development of new helminth-based biopharmaceutics may represent a safer approach of harnessing type 2–suppressive effects of helminths. However, progress regarding the mechanisms and molecules that are employed by helminths to modulate allergic inflammation has been relatively recent. The scavenging of alarmins and the modulation of lipid mediator pathways and macrophage function by helminth proteins have been identified as important immunoregulatory mechanisms targeting innate immunity in asthma and allergy. In addition, by regulating the activation of dendritic cells and by promoting regulatory T-cell responses, helminth proteins can counterregulate the adaptive T helper 2 cell response that drives allergic inflammation. Despite these insights, important open questions remain to be addressed before helminth molecules can be used for the prevention and treatment of asthma and other allergic diseases.

Home environmental and lifestyle factors associated with asthma, rhinitis and wheeze in children in Beijing, China

BACKGROUND

The prevalence of asthma and allergic diseases has increased rapidly in urban China since 2000. There has been limited study of associations between home environmental and lifestyle factors with asthma and symptoms of allergic disease in China.

METHODS

In a cross-sectional analysis of 2214 children in Beijing, we applied a two-step hybrid Least Absolute Shrinkage and Selection Operator (LASSO) algorithm to identify environmental and lifestyle-related factors associated with asthma, rhinitis and wheeze from a wide range of candidates. We used group LASSO to select variables, using cross-validation as the criterion. Effect estimates were then calculated using adaptive LASSO. Model performance was assessed using Area Under the Curve (AUC) values.

RESULTS

We found a number of environmental and lifestyle-related factors significantly associated with asthma, rhinitis or wheeze, which changed the probability of asthma, rhinitis or wheeze from -5.76% (95%CI: -7.74%, -3.79%) to 27.4% (95%CI: 16.6%, 38.3%). The three factors associated with the largest change in probability of asthma were short birth length, carpeted floor and paternal allergy; for rhinitis they were maternal smoking during pregnancy, paternal allergy and living close to industrial area; and for wheeze they were carpeted floor, short birth length and maternal allergy. Other home environmental risk factors identified were living close to a highway, industrial area or river, sharing bedroom, cooking with gas, furry pets, cockroaches, incense, printer/photocopier, TV, damp, and window condensation in winter. Lifestyle-related risk factors were child caretakers other than parents, and age<3 for the day-care. Other risk factors included use of antibiotics, and mother's occupation. Major protective factors for wheeze were living in a rural/suburban region, air conditioner use, and mother's occupation in healthcare.

CONCLUSIONS

Our findings suggest that changes in lifestyle and indoor environments associated with the urbanization and industrialization of China are associated with asthma, rhinitis, and wheeze in children.

Exposure to sewage water and the development of allergic manifestations in Finnish children

BACKGROUND

The hygiene hypothesis suggests that a decreased microbial load contributes to an increased risk of allergies. In the Finnish municipality of Nokia, sewage water was accidentally mixed with drinking water for 2 days. We studied the association between exposure and the emergence of allergies in children.

METHODS

Children aged 2-5 years living in the accident area and an age-matched cohort from the control municipality were recruited. Based on the questionnaires, we identified 139 children exposed to the contaminated water and selected age- and sex-matched controls for them (mean age 16.59 months at the time of the accident). Allergic symptoms and diseases were recorded by ISAAC questionnaires and skin prick tests (SPTs) performed 2 and 5 years after the accident.

RESULTS

SPT positivity at 5 years of follow-up was decreased in the children exposed to the sewage water below 1 year of age (OR 0.311, 95% CI 0.118-0.820; P = 0.019), particularly in children who did not develop gastroenteritis at exposure. In contrast, the children over 1 year of age at the exposure tended more likely to be SPT-positive at 5 years of follow-up (OR 1.997, 95% CI 0.963-4.143; P = 0.070).

CONCLUSIONS

Sewage water exposure during the first year of life, but not later, decreased the risk of IgE sensitization emphasizing the importance of age as a modulator. The modulation of IgE sensitization by the presence of clinical gastroenteritis at the exposure suggests that the nature of microbial load may have importance or alternatively shared host defense mechanisms protect from infection and atopic sensitization.

Aluminum Adjuvant-Containing Vaccines in the Context of the Hygiene Hypothesis: A Risk Factor for Eosinophilia and Allergy in a Genetically Susceptible Subpopulation?

There are similarities between the immune response following immunization with aluminum adjuvants and the immune response elicited by some helminthic parasites, including stimulation of immunoglobulin E (IgE) and eosinophilia. Immunization with aluminum adjuvants, as with helminth infection, induces a Th2 type cell mediated immune response, including eosinophilia, but does not induce an environment conducive to the induction of regulatory mechanisms. Helminths play a role in what is known as the hygiene hypothesis, which proposes that decreased exposure to microbes during a critical time in early life has resulted in the increased prevalence and morbidity of asthma and atopic disorders over the past few decades, especially in Western countries. In addition, gut and lung microbiome composition and their interaction with the immune system plays an important role in a properly regulated immune system. Disturbances in microbiome composition are a risk factor for asthma and allergies. We propose that immunization with aluminum adjuvants in general is not favorable for induction of regulatory mechanisms and, in the context of the hygiene hypothesis and microbiome theory, can be viewed as an amplifying factor and significant contributing risk factor for allergic diseases, especially in a genetically susceptible subpopulation.

Schistosoma mansoni antigens alter activation markers and cytokine profile in lymphocytes of patients with asthma

Asthma is a chronic disease characterized by airway inflammation, obstruction and hyperresponsiveness. Severe asthma affects a small proportion of subjects but results in most of the morbidity, costs and mortality associated with the disease. Studies have suggested that Schistosoma mansoni infection reduces the severity of asthma and prevent atopy.

OBJECTIVE

We evaluated the ability of S. mansoni antigens, Sm29 and Sm29TSP-2 to modulate lymphocyte activation status in response to the allergen of the mite Dermatophagoides pteronyssinus (Der p1) in cell cultures of individuals with asthma.

METHODS

Thirty four patients were enrolled in this study: seventeen patients with severe asthma (SA group), seventeen patients with mild asthma (MA group) and six controls with no asthma. Peripheral blood mononuclear cells (PBMC) were obtained and stimulated with Sm29 and Sm29TSP-2 in the presence or absence of Der p1. The expression of surface markers and cytokines on lymphocytes was evaluated by flow cytometry and the levels of IL-10 in the culture supernatant were determined by ELISA.

RESULTS

The addition of Sm29 and Sm29TSP-2 antigens to PBMC cultures from both groups of subjects with asthma stimulated with Der p1 reduced the frequency of CD4⁺CD25^low cells whereas and increased frequency of CD4⁺CD25^high population was observed compared to unstimulated cultures. Moreover, cultures stimulated with Sm29TSP-2 showed a reduction in the frequency of T cells expressing CD69, IFN-γ, TNF and TGF-β in the MA group and an increase in the frequency of CD4⁺TSLPR⁺ T cells in the SA group. The addition of Sm29 to the cultures reduced the frequency of CD4⁺CD69⁺ and CD4⁺IL-5⁺ T cells in all asthmatic groups, and reduced the frequency of CD4⁺ T cells expressing IL-13 in the MA group. The cultures stimulated with Sm29 and Sm29TSP-2 showed an increase in the level of IL-10 in the supernatants.

CONCLUSION

These results suggest that the addition of Sm29 and Sm29TSP-2 to the cells cultures from subjects with asthma reduced cell activation markers and altered the cytokine production pattern in a way that can potentialy control the inflammatory response associated with asthma.

New Allergens of Relevance in Tropical Regions: The Impact of Ascaris lumbricoides Infections

One of the many aspects of the relationships between parasite infections and allergic diseases is the possibility that allergens from parasites enhance the T_H2 responses, especially IgE production, in allergic diseases such as asthma. In this review we discuss about the allergenic composition of the nematode Ascaris lumbricoides and their potential impact on allergy sensitization and asthma pathogenesis and prevalence in populations living in the tropics and naturally exposed to both, mite allergens and helminth infections.

The hookworm pharmacopoeia for inflammatory diseases

In the developed world, declining prevalence of parasitic infections correlates with increased incidence of allergic and autoimmune disorders. Current treatments for these chronic inflammatory conditions have little to no effect on their prevalence and are referred to as "controllers" rather than cures. There has been limited success in therapeutically targeting allergic and autoimmune pathways, leaving an unmet need for development of effective anti-inflammatories. We discuss the benefit of hookworm infections and the parasite's ability to condition the immune system to prevent allergic asthma and inflammatory bowel diseases. We then examine the immunomodulatory properties of selected hookworm-derived proteins in these two models of inflammation. While hookworm protein therapy has yet to be fully exploited, the identification of these proteins and the mechanisms by which they skew the immune system will provide new avenues for controlling and optimally reversing key pathological processes important in allergic and inflammatory bowel diseases.

Risk factors for asthma in a helminth endemic area in bahia, Brazil

Protective factors associated with atopy or asthma in rural areas include socioeconomic level, overcrowding, and helminth infection. However, little epidemiological information was originated from schistosomiasis areas. This study aimed to investigate factors associated with asthma in a schistosomiasis endemic area. A questionnaire was used to obtain information on demographics, socioeconomic, and environmental features. The ISAAC questionnaire was used to identify individuals with asthma. Parasitological exam was done in all participants and skin prick test to aeroallergens in all asthmatics. Prevalence of Schistosoma mansoni infection was 57.4% and Ascaris lumbricoides, 30.8%. Asthma was found in 13.1% of the population, and 35.1% of them had a positive SPT. Active and passive smoking was positively associated with asthma, whereas A. lumbricoides was negatively associated. In a schistosomiasis hyperendemic region, current infection with A. lumbricoides is protective against asthma. However, we cannot rule out the involvement of S. mansoni infection in this process.

Helminthic infection and the risk of neurologic disease progression in HTLV-1

BACKGROUND

Infection with the human T-cell lymphotropic virus, type 1 (HTLV-1) has been associated with an increased Th1 response. Interestingly, a higher prevalence of helminthic coinfection has been observed among infected individuals, and subsequent modulation of the immune response typically associated with helminths may influence clinical outcomes among HTLV-1 coinfected individuals.

OBJECTIVE

This study was conducted to elucidate the association between helminthic coinfection and the development of clinically characterized neurologic disease that occurs in HTLV-1 infection.

STUDY DESIGN

In a cohort analysis, incidence of HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP) was recorded. Incidence of clinical outcomes and disease-free survival of several neurologic outcomes associated with HTLV-1 were estimated using the Kaplan-Meier method with log-rank tests. The relationships between helminthic infection and risk of HTLV-1 neurologic outcomes were assessed by Cox proportional hazard modeling.

RESULTS

Seventy-four coinfected and 79 non-coinfected patients were followed, with 92 helminthic infections observed in the coinfected group. One patient per group developed HAM/TSP and the risk of progression to neurologic disease outcomes did not differ among those with and without helminthic coinfection (p>0.45). A significant difference was noted in the prevalence of neurologic disease outcomes among all patients at the conclusion of the study (p<0.01).

CONCLUSIONS

These data suggest that treated helminthic infection does not affect risk of development of neurologic disease in HTLV-1 infection, and reinforce that treatment of helminths does not adversely affect patients with HTLV-1. Importantly, among all patients, an overall progression of neurologic disease was observed.

IgE cross-reactivity between Ascaris lumbricoides and mite allergens: possible influences on allergic sensitization and asthma

Nematode infections such as Ascariasis are important health problems in underdeveloped countries, most of them located in the tropics where environmental conditions also promote the perennial co-exposure to high concentrations of domestic mite allergens. Allergic diseases are common, and most of patients with asthma exhibit a predominant and strong IgE sensitization to mites. It is unknown whether co-exposure to Ascaris lumbricoides and the domestic mites Blomia tropicalis and Dermatophagoides pteronyssinus potentiates Th2 responses and IgE sensitization, thereby modifying the natural history of allergy. Recently, we obtained experimental evidence of a high cross-reactivity between the allergenic extracts of these invertebrates, involving well-known allergens such as tropomyosin and glutathione transferases. There is indirect evidence suggesting that the clinical impact of these findings may be important. In this review, we discuss the potential role of this cross-reactivity on several aspects of allergy in the tropics that have been a focus of a number of investigations, some of them with controversial results.

A study on the immunological basis of the dissociation between type I-hypersensitivity skin reactions to Blomia tropicalis antigens and serum anti-B. tropicalis IgE antibodies

Background

Two conditions are used as markers of atopy: the presence of circulating anti-allergen IgE antibodies and the presence of positive skin prick test (SPT) reactions to allergenic extracts. The correlation between these conditions is not absolute. This study aimed at investigating immunological parameters that may mediate this lack of correlation. Individuals whose sera contained anti-B. tropicalis extract IgE antibodies (α-BtE IgE) were divided into two groups, according to the presence or absence of skin reactivity to B. tropicalis extract (BtE). The following parameters were investigated: total IgE levels; α-BtE IgE levels; an arbitrary α-BtE IgE/total IgE ratio; the proportion of carbohydrate-reactive α-BtE IgE; the proportion of α-BtE IgE that reacted with Ascaris lumbricoides extract (AlE); the production of IL-10 by BtE- and AlE-stimulated peripheral blood cells (PBMC).

Results

Total IgE levels were similar in the two groups, but α-BtE IgE was significantly higher in the SPT-positive group (SPT+). A large overlap of α-BtE IgE levels was found in individuals of both groups, indicating that these levels alone cannot account for the differences in SPT outcome. Individuals of the two groups did not differ, statistically, in the proportion of α-BtE IgE that reacted with carbohydrate and in the production of IL-10 by BtE- and AlE-stimulated PBMC. Both groups had part of α-BtE IgE activity absorbed out by AlE, indicating the existence of cross-reactive IgE antibodies. However, the α-BtE IgE from the SPT-negative individuals (SPT-) was more absorbed with AlE than the α-BtE IgE from the SPT+ individuals. This finding may be ascribed to avidity differences of the α-BtE IgE that is present in the two groups of individuals, and could occur if at least part of the α-BtE IgE from the SPT- individuals were elicited by A. lumbricoides infection.

Conclusion

The present results suggest that a low ratio of specific IgE to total IgE levels (in a minority of individuals), and differences in α-BtE IgE avidities (which would have high affinities for A. lumbricoides antigens in SPT- than in SPT+ individuals) may play a role in the down-modulation of type-I hypersensitivity reaction against aeroallergens described in helminth-infected individuals.

Impaired allergy diagnostics among parasite-infected patients caused by IgE antibodies to the carbohydrate epitope galactose-α 1,3-galactose

BACKGROUND

The carbohydrate epitope galactose-α 1,3-galactose (α-Gal) is abundantly expressed on nonprimate mammalian proteins. We have recently shown that α-Gal is responsible for the IgE binding to cat IgA, a newly identified cat allergen (Fel d 5).

OBJECTIVE

We sought to investigate the diagnostic relevance of IgE antibodies to Fel d 5 and α-Gal among parasite-infected patients from central Africa without cat allergy compared with patients with cat allergy from the same region.

METHODS

Sera from 47 parasite-infected patients and 31 patients with cat allergy were analyzed for total IgE and IgE antibodies against cat dander extract (CDE) by using the ImmunoCAP system. Inhibition assay was performed with α-Gal on solid phase-bound CDE. The presence of IgE specific for the major cat allergen Fel d 1, Fel d 5, and α-Gal was analyzed by means of ELISA.

RESULTS

Among the 47 parasite-infected patients, 85% had IgE antibodies against α-Gal (OD; median, 0.175; range, 0.102-1.466) and 66% against Fel d 5 (OD; median, 0.13; range, 0.103-1.285). Twenty-four of the parasite-infected patients were sensitized to CDE, and 21 of them had IgE antibodies to Fel d 5 and α-Gal. There was no correlation between IgE levels to CDE and rFel d 1 among the parasite-infected patients but a strong correlation between CDE and Fel d 5 and α-Gal (P < .001). Among the group with cat allergy, only 5 patients had IgE to α-Gal, and nearly 75% (n = 23) had IgE to rFel d 1 (median, 7.07 kU(A)/L; range, 0.51-148.5 kU(A)/L). In contrast, among the patients with cat allergy, there was a correlation between IgE levels to CDE and rFel d 1 (P < .05) but no correlation between CDE and Fel d 5 and α-Gal.

CONCLUSION

IgE to α-Gal causes impaired allergy diagnostics in parasite-infected patients. Screening for IgE to rFel d 1 and other allergens without carbohydrates might identify patients with true cat sensitization/allergy in parasite-infested areas.

Allergic disorders in Africa and africans: is it primarily a priority?

In Africa, the burden of some diseases has been a problem for centuries. The spectrum of African diseases includes allergies, infections, nutritional deficiencies, and natural disasters. Efforts made by scientists to search for possible means of disease control have been outstanding; however, in some infections, solutions are still out of reach. In disease control programs, it might be worthwhile to pay attention to the most striking diseases than merely follow a holistic approach. This short review tackles the problems of allergy and allergens in Africa as compared with other disease burdens that may suggest the need for a more balanced approach based on priority.

Reduced helminth burden increases allergen skin sensitization but not clinical allergy: a randomized, double-blind, placebo-controlled trial in Vietnam

BACKGROUND

Observational evidence suggests that infection with helminths protects against allergic disease and allergen skin sensitization. It is postulated that such effects are mediated by helminth-induced cytokine responses, in particular IL-10.

OBJECTIVE

We tested this hypothesis in a rural area of central Vietnam where hookworm infection is endemic.

METHODS

One thousand five hundred and sixty-six schoolchildren aged 6-17 were randomly allocated to receive either anti-helminthic therapy or a placebo at 0, 3, 6, and 9 months. We compared changes in the prevalence of exercise-induced bronchoconstriction, allergen skin sensitization, flexural eczema on skin examination, questionnaire-reported allergic disease (wheeze and rhinitis symptoms), and immunological parameters (hookworm-induced IFN-gamma, IL-5, IL-10) between 0 and 12 months.

RESULTS

One thousand four hundred and eighty-seven children (95% of these randomized) completed the study. The most common helminth infections were hookworm (65%) and Ascaris lumbricoides (7%). There was no effect of the therapy on the primary outcome, exercise-induced bronchoconstriction (within-participant mean percent fall in peak flow from baseline after anti-helminthic treatment 2.25 (SD 7.3) vs. placebo 2.19 (SD 7.8, P=0.9), or on the prevalence of questionnaire-reported wheeze [adjusted odds ratio (OR)=1.16, 95% confidence interval (CI) 0.35-3.82, P=0.8] and rhinitis (adjusted OR=1.39, 0.89-2.15, P=0.1), or flexural dermatitis on skin examination (adjusted OR=1.15, 0.39-3.45, P=0.8). However, anti-helminthic therapy was associated with a significantly higher allergen skin sensitization risk (adjusted OR=1.31, 1.02-1.67, P=0.03). This effect was particularly strong for children infected with A. lumbricoides at baseline (adjusted OR=4.90, 1.48-16.19, P=0.009). Allergen skin sensitization was inversely related to hookworm-specific IL-10 at baseline (adjusted OR=0.76, 0.59-0.99, P=0.04). No cytokine tested, including IL-10, changed significantly after the anti-helminthic therapy compared with the placebo.

CONCLUSION

A significant reduction in worm burden over a 12-month period in helminth-infected children increases the risk of allergen skin sensitization but not of clinical allergic disease. The effect on skin sensitization could not be fully explained by any of the immunological parameters tested.

PAS-1, a protein from Ascaris suum, modulates allergic inflammation via IL-10 and IFN-gamma, but not IL-12

Helminths and their products have a profound immunomodulatory effect upon the inductive and effector phases of inflammatory responses, including allergy. We have demonstrated that PAS-1, a protein isolated from Ascaris suum worms, has an inhibitory effect on lung allergic inflammation due to its ability to down-regulate eosinophilic inflammation, Th2 cytokine release and IgE antibody production. Here, we investigated the role of IL-12, IFN-gamma and IL-10 in the PAS-1-induced inhibitory mechanism using a murine model of asthma. Wild type C57BL/6, IL-12(-/-), IFN-gamma(-/-) and IL-10(-/-) mice were immunized with PAS-1 and/or OVA and challenged with the same antigens intranasally. The suppressive effect of PAS-1 was demonstrated on the cellular influx into airways, with reduction of eosinophil number and eosinophil peroxidase activity in OVA+PAS-1-immunized wild type mice. This effect well correlated with a significant reduction in the levels of IL-4, IL-5, IL-13 and eotaxin in BAL fluid. Levels of IgE and IgG1 antibodies were also impaired in serum from these mice. The inhibitory activity of PAS-1 was also observed in IL-12(-/-) mice, but not in IFN-gamma(-/-) and IL-10(-/-) animals. These data show that IFN-gamma and IL-10, but not IL-12, play an important role in the PAS-1 modulatory effect.

Toxocariasis associated with chronic cough in childhood: a longitudinal study in Hungary

Chronic cough lasting 8 weeks or more often seems to be an intractable problem in childhood. Toxocara infection is associated with an increased prevalence of airway symptoms and may be the possible aetiological agent of chronic cough. Of 425 children aged 2-17 years with chronic cough who were investigated for toxocariasis and the distribution of bronchial asthma (BA), cough variant asthma (CVA) and non-asthmatic eosinophilic bronchitis (NAEB), 136 (32%) were seropositive for Toxocara canis antigens. Ninety-three of the 136 were adequately assessed, diagnosed and followed up during 1 year. BA was diagnosed in 40%, CVA in 27% and NAEB in 33% of the children. The eosinophil cell count, serum T. canis IgG levels and symptoms are predictors of the improvement or the decline of the condition. Presuming the aetiopathogenetic role of T. canis in the inflammatory process of chronic cough, we treated the children not only with inhaled corticosteroid (ICS), but also with a 1-week course of anthelminthics. We could significantly decrease the dose of ICS in 23 (62%) of the 37 with BA. The administration of anthelminthics and the avoidance of sensitizers were sufficient for those with NAEB; none needed ICS. ICS therapy could be stopped 2-3 months later in 17 (68%) of the 25 with CVA. We found that 8 of the 25 with CVA (32%) presented asthmatic symptoms at the end of the 1-year period. In Hungary, T. canis may be a potential sensitizer for chronic cough in seropositive children. Deworming therapy will then alleviate the airway symptoms without exacerbation in patients with BA, and have a positive effect on those with NAEB and the majority of those with CVA.

Atopic disorders and parasitic infections

This chapter examines the relationship between atopic disorders and parasitic infections. Atopy is an exaggerated IgE-mediated Type-1 immune response in predisposed individuals. Conflicting information exists in regard to the relationship of parasitic infections and the classic allergic diseases, that is, atopic dermatitis, allergic rhinitis and asthma. Attention is paid to the explanations for these discrepancies in the literature found within both human and animal studies on atopy with particular emphasis on helminthic infections. The factors that cause only a proportion of atopic individuals to develop clinical disease have not been defined although helminths confer protection in many studies examined. Early childhood infections help induce a Th1-biased immunity and prevent the induction of the Th2 system that causes atopy. Acute parasitic infections may increase manifestations of allergy, whereas chronic infections with parasites decrease atopic predisposition. Nonetheless, a causal association between geohelminth infection and atopic disorders has not been established. Some helminthic substances, especially the cytokines, have respiratory and anti-allergic effects, and may therefore become useful as therapeutic modalities for many atopic and allergic disorders.

Probiotics in infancy induce protective immune profiles that are characteristic for chronic low-grade inflammation

BACKGROUND

Probiotics are widely studied both in the treatment and prevention of allergic diseases, but their mode of action is poorly known.

OBJECTIVE

Our aim was to examine the effect of probiotic bacteria on in vivo cytokine, antibody, and inflammatory responses in allergy-prone infants.

METHODS

In a randomized double-blind study, probiotic bacteria or placebo were given for 1 month before delivery to mothers and for 6 months to infants with a family history of allergy. Plasma samples were analysed for C-reactive protein (CRP), total IgA and IgE, food-specific IgA, IgG, and IgE, IL-2, IL-4, IL-6, IL-10, TNF-alpha, and IFN-gamma. We analysed the associations of immunological and inflammatory parameters at age 6 months with probiotic treatment and allergic phenotype at 2 years.

RESULTS

Infants receiving probiotic bacteria had higher plasma levels of CRP (P=0.008), total IgA (P=0.016), total IgE (P=0.047), and IL-10 (P=0.002) than infants in the placebo group. Increased plasma CRP level at age 6 months was associated with a decreased risk of eczema [odds ratio (OR) 0.41 [95% confidence interval (CI) 0.17-0.99], P=0.046], and with a decreased risk of allergic disease [OR 0.38 (95% CI 0.16-0.87), P=0.023] at age 2 years, when adjusted with probiotic use.

CONCLUSION

The association of CRP with a decreased risk of eczema at 2 years of age in allergy-prone children supports the view that chronic, low-grade inflammation protects from eczema. Probiotic-induced low-grade inflammation was characterized by elevation of IgE, IgA, and IL-10, the changes typically observed in helminth infection-associated induction of regulatory mechanisms. The findings emphasize the role of chronic microbial exposure as an immune modulator protecting from allergy.

Helminths, allergic disorders and IgE-mediated immune responses: where do we stand?

Th2 responses induced by allergens or helminths share many common features. However, allergen-specific IgE can almost always be detected in atopic patients, whereas helminth-specific IgE is often not detectable and anaphylaxis often occurs in atopy but not helminth infections. This may be due to T regulatory responses induced by the helminths or the lack of helminth-specific IgE. Alternatively non-specific IgE induced by the helminths may protect from mast cell or basophil degranulation by saturating IgE binding sites. Both of these mechanisms have been implicated to be involved in helminth-induced protection from allergic responses. An article in the current issue of the European Journal of Immunology describes the generation of an anti-Nippostrongylus brasiliensis-specific IgE antibody which was used to identify a novel N. brasiliensis antigen (Nb-Ag1). The authors demonstrated that Nb-Ag1 specific IgE could only be detected for a short period of time during infection, and that these levels were sufficient to prime mast cells thereby leading to active cutaneous anaphylaxis after the application of Nb-Ag1. This is the first report clearly showing that a low level of helminth-specific IgE, transiently produced, is able to induce mast cell degranulation in the presence of large amounts of polyclonal IgE.

Suppression of TH2-type allergic reactions by helminth infection

There is no immunological mechanism to adequately explain the sudden epidemic in allergies noted in the last 30 years in developed countries. The reduction in the development of allergic disorders observed in individuals infected with parasitic helminths, however, supports a possible role for worms in suppressing allergies. Helminths regulate the immunity of the host to ensure a mutually beneficial environment for the survival of both the parasite and the host. This interplay between helminths and allergic responses raises fundamental questions in immunobiology. Harnessing current mechanistic studies for translational research into helminth infections and atopy might have potential for the identification of novel biomarkers, and even therapeutics, in allergic diseases.

Worms and allergy

Worms and asthma are associated with a type 2 immune response, but evidence has accumulated that helminth infection is negatively associated with atopy, prevalence of allergic diseases and severity of asthma. One important difference between these polarized type 2 responses is that in allergy modulation of the immunological response is not appropriate, whereas in infection with helminths, several host mechanisms down-regulate the host immune response. As a result, patients infected with worms have a decrease in both type 1 and type 2 responses. The main mechanism involved in this down-modulation is increased production of IL-10, but expansion of regulatory T cells and NKT cells may also participate. Regarding the interaction between worms and allergy, a few variables need to be taken in account: phase (acute or chronic) of helminth infection, parasite load and species of helminth. In animals and humans, acute helminth infection may increase manifestations of allergy, whereas chronic infection with parasites decreases atopy. The modulation of the immune response by helminths is dependent on having an adequate parasite load. Moreover, although several helminth species have been shown to modulate immune responses, most in vitro and in vivo studies have focused on the importance of Schistosoma mansoni in down-modulating allergic reactions.

Factors responsible for differences between asymptomatic subjects and patients presenting an IgE sensitization to allergens. A GA2LEN project

The synthesis of allergen-specific IgE is required for the development of allergic diseases including allergic rhinitis and allergic asthma (patients), but many individuals with allergen-specific IgE do not develop symptoms (asymptomatic subjects). Differences may exist between asymptomatic subjects and patients. Whether the presence of allergen-specific IgE translates into clinical allergy most likely depends on a complex interplay of multiple factors. These include a family history of atopy, the levels of total serum IgE and, allergen-specific IgE or IgG, epitope-specificity of IgE and their degree of polyclonality (mono- vs polysensitized), as yet unidentified serum factors, the balance of T regulatory cells (Treg) and Th1/Th2 cells, the polymorphisms of the high affinity receptor for IgE (FcepsilonRI) and other factors regulating the activation of FcepsilonRI-bearing cells. Asymptomatic subjects may be more often monosensitized than patients who may be more often polysensitized. There are many unanswered important questions that need to be addressed in order to better understand how IgE sensitization translates into clinical allergy. The assessment of differences between the asymptomatic and symptomatic groups of subjects represent one of the scientific programs of Global Allergy and Asthma European Network funded by the European Union and the hypotheses underlying these differences are presented in this paper.

Helminths can protect themselves against rejection inhibiting hostile respiratory allergy symptoms

The ability of common environmental allergens to stimulate IgE responses and thus to produce allergic diseases has tended to overshadow the fact that helminthic parasites are possibly the most potent inducers of this immunoglobulin that exists in nature. Although it has been well established that during these infections there is a stimulation of IgE against their own antigens as well as a strong induction of nonspecific TH2/IL-4 polyclonal IgE, similarly to the allergic processes, many authors debate if the presence of these infections correlates inversely or not with the rate prevalence of atopy or respiratory allergy. Interpreting this relationship, we suggest that sometimes the intensive infections of hosts, especially with soil helminths which migrate in the respiratory ways or use there as entrance, can induce the production of some mediators ('helminth(k)ines'), to reduce the possibility of their reactive expulsion from the host. The ability to suppress hostile allergic symptoms despite the simultaneous induction of IgE response and local inflammation maybe is established due to the selective evolution, to assure for the parasites better chances for an effective life and reproduction within their mammalian hosts.

The expanding realm of heterologous immunity: friend or foe?

Antecedent or current infections can alter the immunopathologic outcome of a subsequent unrelated infection. Immunomodulation by co-infecting pathogens has been referred to as 'heterologous immunity' and has been postulated to play a role in host susceptibility to disease, tolerance to organ transplant, and autoimmune disease. The effect of various infections on heterologous immune responses has been well studied in the context of shared epitopes and cross-reactive T cells. It has been shown that prior infections can modulate protective immunity and immunopathology by forming a pool of memory T cells that can cross-react with antigens from heterologous organisms or through the generation of a network of regulatory cells and cytokines. While it is not feasible to alter a host's history of prior infection, understanding heterologous immune responses in the context of simultaneous unrelated infections could have important therapeutic implications. Here, we outline key evidence from animal and human studies demonstrating the effect of heterologous immunity on the outcome of disease. We briefly review the role of T cells, but expand our discussion to explore other immune mechanisms that may modulate the response to concurrent active infections. In particular, we underscore the role of the innate immune system, polarized responses and regulatory mechanisms on heterologous immune responses.

Asthma in Hispanics

Hispanic individuals trace their ancestry to countries that were previously under Spanish rule, including Mexico, large parts of Central and South America, and some Caribbean islands. Most--but not all--Hispanics have variable proportions of European, Amerindian, and African ancestry. Hispanics are diverse with regard to many factors, including racial ancestry, country of origin, area of residence, socioeconomic status, education, and access to health care. Recent findings suggest that there is marked variation in the prevalence, morbidity, and mortality of asthma in Hispanics in the United States and in Hispanic America. The reasons for differences in asthma and asthma morbidity among and within Hispanic subgroups are poorly understood but are likely due to the interaction between yet-unidentified genetic variants and other factors, including environmental tobacco smoke exposure, obesity, allergen exposure, and availability of health care. Barriers to optimal management of asthma in Hispanics in the United States and in Hispanic America include inadequate access to health care, suboptimal use of antiinflammatory medications, and lack of reference values for spirometric measures of lung function in many subgroups (e.g., Puerto Ricans). Future studies of asthma in Hispanics should include large samples of subgroups that are well characterized with regard to self-reported ethnicity, country of origin, place of birth, area of residence, and indicators of socioeconomic status. Because Hispanics are disproportionately represented among the poor in the United States, implementation of adequate access to health care and social reforms (e.g., improving housing conditions) would likely have a major impact on reducing asthma morbidity in this population.

Saturation of immunoglobulin E (IgE) binding sites by polyclonal IgE does not explain the protective effect of helminth infections against atopy

One hypothesis for the decreased rates of atopy observed among helminth-infected individuals is that parasite-induced polyclonal immunoglobulin E (IgE) out-competes allergen-specific IgE for FcepsilonRI binding on basophils and mast cells. In experiments with fresh blood drawn from filaria-infected patients, we found no association between ratios of polyclonal to Brugia malayi antigen (BmAg)-specific IgE (range, 14:1 to 388:1) and basophil responses to BmAg as measured by histamine release. Using serum samples from a filaria-infected patient who also had dust mite (Dermatophagoides pteronyssinus)-specific IgE antibodies from time points with various ratios of polyclonal to D. pteronyssinus-specific IgE (16:1 to 86:1), we demonstrated that increased ratios of polyclonal to D. pteronyssinus-specific IgE did not attenuate basophil sensitization as measured by D. pteronyssinus-specific histamine release. Suppression of histamine release was likely not observed in either of these sets of experiments because polyclonal to antigen-specific IgE ratios were not sufficiently high, as concurrent passive sensitization of basophil experiments required ratios of polyclonal to antigen-specific IgE of greater than 500:1 to suppress basophil histamine release. Further, the intensity of IgE staining in basophil populations from 20 patients with active filaria infections correlated strongly with total serum IgE levels (rho = 0.698; P = 0.0024) with no plateau in intensity of IgE staining, even though some patients had total IgE levels of greater than 10,000 ng/ml. Our data therefore suggest that in helminth infections (and in filarial infections in particular), the ratios of polyclonal to allergen-specific IgE rarely reach those levels necessary to inhibit allergen-specific IgE-FcepsilonRI binding and to suppress allergen-induced degranulation of mast cells and basophils.

The potential impact of early exposures to geohelminth infections on the development of atopy

Microbial exposures in early life may provide important signals for immune maturation and the development of an antiinflammatory network thereby preventing the development of dysregulated immune responses such as that associated with allergic disease. The human immune system has evolved in the presence of intense helminth infections and has developed regulatory mechanisms to limit the harmful inflammation that can be caused by the potent allergens secreted by these chronic pathogens. Geohelminth infections are highly prevalent childhood infections, and there is strong evidence that chronic geohelminth infections provide protection against atopy in the rural tropics. Because the early environmental exposures that may lead to the development of atopy are likely to occur in the first few years of life, geohelminth infections may exert their protective effects at this time. Early exposures to geohelminth antigens could occur transplacentally, through breast milk, or through early infant exposures, and could induce tolerance to parasite antigens resulting in suppressed allergic responses to the parasite. Tolerization to parasite antigens could suppress allergic responses to inhalant allergens through bystander effects or through tolerization of crossreactive epitopes that are shared between geohelminth parasites and inhalant allergens. Tolerization to crossreactive allergens could occur by thymic deletion or through peripheral mechanisms such as regulatory T cells. Immunologic studies of the mechanisms by which early exposures to geohelminth infections affect immune polarization to inhalant allergens are likely to provide important insights into the early regulation of the immune response and may lead to the design of novel interventions for the prevention of allergic disease.

Atopic sensitization and atopic dermatitis in Estonian and Swedish infants

BACKGROUND

Early life events seem to have a major impact on the development of tolerance or sensitization.

OBJECTIVE

The aim of the study was to compare the prevalence of sensitization and atopic dermatitis (AD) during the first 2 years of life in Estonia and in Sweden.

METHODS

Two groups comprising 110 Estonian and 123 Swedish infants were followed from birth up to 2 years of age. Data about symptoms of allergy, infections and use of antibiotics were obtained by questionnaires. Clinical examinations, skin prick tests (SPTs) with food and inhalant allergens, and blood sampling for IgE analyses were carried out at 3, 6, 12 and 24 months.

RESULTS

The cumulative incidence of AD and positive SPTs were lower in the Estonian than the Swedish infants (14% vs. 24%; P = 0.06 and 13% vs. 24%; P = 0.03), while circulating IgE antibodies were more common (39% vs. 27%; P = 0.06) and often present without any clinical significance in Estonian children. Estonian infants had respiratory illnesses more often and they had received antibiotics more frequently. Use of antibiotics increased the risk for positive SPT in the Estonian (odds ratio = 1.7, 95% confidence interval = 1.1-2.5), but not in the Swedish infants. This may be explained by the use of broad-spectrum antibiotics in Estonia, while in Sweden mostly penicillin was prescribed.

CONCLUSIONS

The prevalence of AD and positive SPTs was lower in the Estonian than the Swedish infants, while circulating IgE antibodies were more common and often present without any clinical significance. These differences cannot simply be explained by infections, or use of broad-spectrum antibiotics in the two countries, although more the natural lifestyle in Estonia may be contributing factor.

Parasite role reversal: worms on trial

Asthma has reached epidemic proportions globally. This has been attributed by many to improved hygiene. The frequent failure of conventional pharmaceuticals to manage the disease has led to the introduction of parasites as a potential alternative therapy for asthma and other immunological diseases. In this article, we briefly review the immunological rationale underpinning therapeutic parasitic infection, describe recently initiated trials, and highlight potential risks and benefits of introducing parasites into patient cohorts.

Helminth infections: protection from atopic disorders

Westernized countries are suffering from an epidemic rise in immunologic disorders, such as childhood allergy. A popular explanation is that the increased prevalence in allergy is due to a diminished or altered exposure to gut-dwelling microbes, resulting in a disordered immunoregulation. Various population studies have provided a strong case for the involvement of helminth infections in this respect. Detailed analysis of helminth-induced immune responses showed that helminths not only prime for polarized Th2 responses but also potently induce T-cell hyporesponsiveness. Recently, it has been demonstrated that helminths induce suppressed host immune responses by the priming for regulatory T cells. It is proposed that this regulatory T cell-inducing activity accounts for the protection observed in the development of allergic disorders. It would be interesting to define and characterize particular helminth molecules that have profound immunomodulatory capacities as a target for therapeutic application in the treatment or prophylaxis of allergic manifestations.

The increased prevalence of allergy and the hygiene hypothesis: missing immune deviation, reduced immune suppression, or both?

Allergic atopic disorders, such as rhinitis, asthma, and atopic dermatitis, are the result of a systemic inflammatory reaction triggered by type 2 T helper (Th2) cell-mediated immune responses against 'innocuous' antigens (allergens) of complex genetic and environmental origin. A number of epidemiological studies have suggested that the increase in the prevalence of allergic disorders that has occurred over the past few decades is attributable to a reduced microbial burden during childhood, as a consequence of Westernized lifestyle (the 'hygiene hypothesis'). However, the mechanisms by which the reduced exposure of children to pathogenic and nonpathogenic microbes results in enhanced responses of Th2 cells are still controversial. The initial interpretation proposed a missing immune deviation of allergen-specific responses from a Th2 to a type 1 Th (Th1) profile, as a result of the reduced production of interleukin-12 and interferons by natural immunity cells which are stimulated by bacterial products via their Toll-like receptors. More recently, the role of reduced activity of T regulatory cells has been emphasized. The epidemiological findings and the experimental evidence available so far suggest that both mechanisms may be involved. A better understanding of this question is important not only from a theoretical point of view, but also because of its therapeutic implications.

Allergies and parasitoses in sub-Saharan Africa

There has been nearly an epidemic rise in allergic disease throughout the world. However, this significant increase in the prevalence of allergic diseases has not been reported on the African continent. There are many factors which have been offered to explain these differences, including nutrition, environmental factors and genetic contributions. In addition, these differences in allergic disease incidents have often been discussed in terms of the hygiene hypothesis. In this manuscript, we have focused our attention on specific interactions between parasitoses and allergic diseases and illustrate their interactions with socioeconomic, cultural, and sanitary realities. The data is particularly applicable to Senegal but can be extrapolated to other regions throughout the world and the results have implications for the induction of allergic disease in both western and Third World countries.

Eosinophilic inflammation and airway hyper-responsiveness are profoundly inhibited by a helminth (Ascaris suum) extract in a murine model of asthma

BACKGROUND

The increase of atopic disorders in developed countries has been associated with the decline of infectious diseases, including helminthic infections. We have already demonstrated that adult worm extracts from Ascaris suum (ASC) suppress the IgE antibody production against unrelated antigens.

OBJECTIVE

Here we investigated the influence of ASC on the development of pulmonary eosinophilic inflammation in a murine model of asthma.

METHODS

Heat-coagulated egg white alone (EWI) or mixed with ASC (EWI + ASC) was implanted subcutaneously in B10.A or C57BL/6 mice, and 14 days later they were challenged intratracheally with OVA or exposed to aerosolized OVA for 4 days.

RESULTS

The suppressive effect of ASC was demonstrated on the accumulation of cells into airways, with reduction of eosinophil numbers and of eosinophil peroxidase activity in EWI + ASC-immunized mice. This effect correlated with a marked reduction of IL-5 and IL-4 levels in the BAL from C57BL/6 and B10. A mice, respectively, and of eotaxin in BAL and lung tissue from both strains. OVA-specific IgG1 and IgE levels were also impaired in serum and BAL from these mice. Airway hyper-reactivity to methacholine was obtained in B10. A mice sensitized with EWI, but the respiratory mechanical parameters returned to normal levels in EWI + ASC-immunized mice.

CONCLUSION

These results indicate that ASC has a profound inhibitory effect on lung inflammation and hyper-responsiveness and that suppression of IL-5 or IL-4 and of eotaxin contributes to this effect.

Ascaris lumbricoides infection is associated with increased risk of childhood asthma and atopy in rural China

There is growing international interest in the possible relationships between helminthic infection and allergic disease, although the nature of the relationships remains uncertain and controversial. The interrelationships of current and past infection with Ascaris lumbricoides and asthma and atopy were investigated in a cross-sectional sample of 2,164 children between the ages of 8 and 18 years from Anqing Province, China. The children were sampled from a larger family-based study of the genetics of asthma. The prevalence of either a history of or a positive stool examination for Ascaris was 24.5%. Asthma was defined for analytic purposes using previously validated, stringent criteria including airways responsiveness to methacholine. Independently of the other factors assessed, infection with A. lumbricoides was associated with increased risk of asthma (p < 0.001), an increased number of skin tests positive to aeroallergens (p < 0.001), and an increased dose-response slope to methacholine (p = 0.003). The association of sensitization to common aeroallergens with increased asthma risk was enhanced in those children infected with Ascaris, and such infection was associated with an increased risk of asthma independent of sensitization to aeroallergens in this selected population. These data suggest a complex relationship between ascariasis and susceptibility to childhood asthma among predisposed children that may involve an interaction with the immune response to inhaled aeroallergens.

Allergy, parasites, and the hygiene hypothesis

The increase of allergic diseases in the industrialized world has often been explained by a decline in infections during childhood. The immunological explanation has been put into the context of the functional T cell subsets known as T helper 1 (TH1) and T helper 2 (TH2) that display polarized cytokine profiles. It has been argued that bacterial and viral infections during early life direct the maturing immune system toward TH1, which counterbalance proallergic responses of TH2 cells. Thus, a reduction in the overall microbial burden will result in weak TH1 imprinting and unrestrained TH2 responses that allow an increase in allergy. This notion is contradicted by observations that the prevalence of TH1-autoimmune diseases is also increasing and that TH2-skewed parasitic worm (helminth) infections are not associated with allergy. More recently, elevations of anti-inflammatory cytokines, such as interleukin-10, that occur during long-term helminth infections have been shown to be inversely correlated with allergy. The induction of a robust anti-inflammatory regulatory network by persistent immune challenge offers a unifying explanation for the observed inverse association of many infections with allergic disorders.

Parasites and asthma/allergy: what is the relationship?

Asthma prevalence is increasing in Western industrialized countries. The infectious theory of asthma onset hypothesizes that lower levels of IL-12 result in reduced T(H)1 stimulation and failure of the neonate to deviate from its T(H)2 bias at birth. Helminthic infections may influence T(H)2 immune responses and hence immune development. Although ecologic data would support a protective effect of parasitic infection on asthma development, this may be due to other exposures. To date, there is no conclusive evidence that parasitic infection protects against asthma development.

Atopy is a risk factor for non-steroidal anti-inflammatory drug sensitivity

BACKGROUND

There is scarce information in the literature about a possible association between atopy and certain clinical manifestations of NSAID sensitivity.

OBJECTIVES

(1) To evaluate the prevalence of atopy in patients proved to be sensitive to cyclooxygenase inhibitors. (2) To assess cross-reactivity to two alternative NSAIDs, paracetamol (acetaminophen) and nimesulide.

METHODS

NSAID-sensitive patients attending an allergy clinic and unselected controls were prick tested with inhalant allergens. Oral challenges with NSAIDs were carried out by the single-blinded (SBOC) method. Clinical data about personal and family history of allergic and atopic diseases were obtained by a careful review of the medical records and by direct questioning by experienced allergists.

RESULTS

Fifty patients had positive SBOCs to the suspected NSAID and only these were studied. A personal history of atopic diseases was present in 41 patients (82%) and 7 controls (14.5%), and a family history in 24 patients (48%) and 6 controls (12.5%). Prick skin tests with aeroallergens were positive in 39 of 45 patients tested (86.6%) and in 14 of 48 controls (29.1%), (P = .0001). Skin test positivity rates were higher in patients with cutaneous challenge reactions who responded to only one NSAID (single reactors) in comparison to cross-reactors (P = .04). The most frequent clinical manifestations of NSAID sensitivity were (1) cutaneous (angioedema, urticaria) in 34 patients, (2) blended (cutaneous plus respiratory) in 12, (3) respiratory in 3, and (4) anaphylactoid in 1. Aspirin, pyrazolone, paracetamol, and ibuprofen were the drugs more frequently implicated in these reactions. Cross-sensitivity with paracetamol and nimesulide were 32% and 25%, respectively.

CONCLUSIONS

The prevalence of atopy is increased in challenge-proven NSAID-intolerant patients. The atopic condition may represent an important risk factor for developing reactions to these drugs. Paracetamol and nimesulide are relatively safe alternative choices in those patients, although their use still carries some risk of unwanted reactions.

The immunosuppressive activity of Ascaris suum is due to high molecular weight components

The role of isolated components obtained by gel filtration chromatography of Ascaris suum body extract (Asc) on the modulation of the immune response to ovalbumin (OvA) was evaluated and correlated with the immunogenic properties of such components. We showed that high (PI), but not low (PIII), molecular weight components have the ability to inhibit OvA-induced immediate and DTH reactions, lymph node (LN) cell proliferation, cytokine (IL-2, interferon-gamma (IFN-gamma), IL-4 and IL-10) and antibody (IgG1, IgG2a, IgM and IgE) production in mice concomitantly immunized with OvA and these high mol. wt components. The pattern of cytokines synthesized in response to PI or PIII was totally different: the former induced more IL-4 and IL-10 and the latter more IL-2 and IFN-gamma. The levels of Asc-specific IgG1 antibodies were higher in mice immunized with OvA plus PI and IgG2a anti-Asc antibodies predominated in those immunized with PIII. IgE antibody production, however, was low in the former group of mice. These results indicate that the high mol. wt components present in the body extract from the helminth A. suum are responsible for its suppressive effect upon Th1- and Th2-dependent immune responses to an unrelated antigen. The suppression of the Th1-dependent parameters could be related to high-level expression of IL-4 and IL-10 induced by such components.

Nutritional status and the IgE response against Ascaris lumbricoides in children from a tropical slum

Helminthic infection can stimulate the interleukin-4 (IL-4)-dependent polyclonal synthesis of immunoglobulin E (IgE) in children endemically exposed to these parasites. As such children are also frequently at nutritional risk, in this study we considered the possible influence of malnutrition on serum IL-4 levels and the IgE response in helminthic infection. We evaluated 85 Ascaris-infected children living in an urban slum area of Caracas, Venezuela, and found that the serum levels of IL-4 and total IgE were significantly higher in malnourished children than in their well nourished counterparts. In contrast, the specific anti-Ascaris IgE antibody response was significantly lower in the malnourished group. After anthelmintic treatment of the children, the total serum IgE and IL-4 levels decreased significantly in the well nourished group, while the specific anti-Ascaris IgE antibody response increased. No significant change was detected, however, in the malnourished group. Our results suggested that malnutrition potentiates the polyclonal stimulation of IgE synthesis induced by helminths. As specific IgE antibody has been implicated in the resistance to helminthic infection, and the polyclonal stimulus diminishes this response, these factors may increase the susceptibility of malnourished children to such parasites.

Ascaris reinfection of slum children: relation with the IgE response

Total and Ascaris-specific serum IgE levels were measured in a group of 98 Ascaris-infected children from a slum area of Caracas, Venezuela, in whom the infections were eliminated by regular treatment for 22 months with the anthelmint Oxantel/Pyrantel ('Quantrel'). The children were re-evaluated at the end of the treatment programme, and then 8 months later, at which time reinfection was assessed. Total IgE levels at the beginning of the study were significantly higher in the children who became reinfected after treatment, compared with those who did not. The anthelmint treatment caused a significant decrease in the total IgE levels in most of the children, and after a period of 8 months without treatment these continued to decrease in the non-reinfected group, but increased again in the reinfected children. The reverse pattern was found for Ascaris-specific IgE antibody levels, and in fact an inverse correlation was found between total and anti-Ascaris IgE levels. Striking associations were found between reinfection and high pretreatment values of total IgE, but low levels of specific IgE antibody. These data support the concept that specific IgE antibody may participate in the protection against helminthic infection, and suggest that the polyclonal stimulation of IgE synthesis caused by these parasites may reduce the effectiveness of such responses. The results also indicate that different individuals have varying propensities to respond polyclonally to the helminths, and this influences their resistance to infection.

Modulation of the allergic reactivity of slum children by helminthic infection

Infection by helminthic parasites can cause the polyclonal stimulation of IgE synthesis, possibly via an enhanced production of interleukin-4 (IL-4), and this has been suggested to influence the allergic reactivity of tropical populations where these parasites are endemic. We evaluated a group of urban slum children in Caracas, Venezuela, with a high prevalence of helminthic infection (70.8%), to establish the relationship between the elevated IgE levels (3696 IU/ml) induced by these parasites and various aspects of the allergic response. Although the absolute levels of IL-4 detected in the sera of these children were low (0.65 +/- 0.20 ng/ml), a strong positive correlation (r = 0.78) was found between these and serum IgE. The cutaneous immediate hypersensitivity reactivity to extracts of common environmental allergens was relatively low (17.5% to house dust), although that to Ascaris extract was moderately high (49.4%). Significant inverse correlations were found between total IgE levels and the different skin test reaction diameters, including Ascaris. The positivity of Prausnitz-Kustner passive transfer tests was low in this group (34%), with a strong inverse correlation (r = -0.75) being found between this and total IgE levels. Significant inverse correlations were also found between total IgE levels and specific IgE antibody to environmental allergens, and to Ascaris antigen. We suggest that the polyclonal production of IgE stimulated by helminthic infection can suppress the allergic response to environmental and parasite allergens via both mast cell saturation and inhibition of specific IgE production.

Relationship between the degree of poverty and the IgE response to Ascaris infection in slum children

We examined a group of urban slum children in Caracas, Venezuela, and demonstrated the relationship that exists between poverty, conditions of hygiene and the prevalence of helminth infection. Concordant with the high prevalence of helminth infection in these children, the total serum levels of immunoglobulin E (IgE) and blood eosinophilia were elevated and were directly related to the degree of poverty and lack of sanitary facilities. However, in contrast, the reverse pattern was observed for the specific allergic response to these parasites. Thus, the immediate hypersensitivity skin test reactivity to Ascaris antigens, and the serum levels of specific anti-Ascaris IgE antibody, were lowest in the poorest children, who had the highest prevalence of helminth infection and the highest total IgE levels. As allergic-type reactions may participate in protective mechanisms against helminths, these results suggest that poverty and poor sanitary conditions may, by influencing the IgE response, compromise the resistance of such children to parasitic infections.