Eosinophils, allergy and parasites

Conserved and tissue-specific immune responses to biologic scaffold implantation

Upon implantation into a patient, any biomaterial induces a cascade of immune responses that influences the outcome of that device. This cascade depends upon several factors, including the composition of the material itself and the location in which the material is implanted. There is still significant uncertainty around the role of different tissue microenvironments in the immune response to biomaterials and how that may alter downstream scaffold remodeling and integration. In this study, we present a study evaluating the immune response to decellularized extracellular matrix materials within the intraperitoneal cavity, the subcutaneous space, and in a traumatic skeletal muscle injury microenvironment. All different locations induced robust cellular recruitment, specifically of macrophages and eosinophils. The latter was most prominent in the subcutaneous space. Intraperitoneal implants uniquely recruited B cells that may alter downstream reactivity as adaptive immunity has been strongly implicated in the outcome of scaffold remodeling. These data suggest that the location of tissue implants should be taken together with the composition of the material itself when designing devices for downline therapeutics. STATEMENT OF SIGNIFICANCE: Different tissue locations have unique immune microenvironments, which can influence the immune response to biomaterial implants. By considering the specific immune profiles of the target tissue, researchers can develop implant materials that promote better integration, reduce complications, and improve the overall outcome of the implantation process.

Eosinophils and risk of ulcerative colitis in European population: Evidence from Mendelian randomization study

BACKGROUND

Observational studies have indicated that peripheral blood eosinophil count is elevated in individuals diagnosed with ulcerative colitis (UC) and correlates with the disease activity of UC. However, this conclusion contradicts with findings from other studies. Therefore, we employed Mendelian randomization (MR) method to assess the genetic link between eosinophil count and UC.

METHOD

This MR study utilized summary data from genome-wide association studies (GWAS) on eosinophil count and UC. The main approach used for conducting MR analysis was the inverse variance weighted (IVW) method. Meta-analysis of the IVW results was performed alongside multiple sensitivity analyses to confirm the robustness of the MR analysis results.

RESULTS

The IVW method unveiled a causal relationship between eosinophil count and UC (OR = 1.18, 95% CI: 1.04-1.33, p = .01) in the discovery cohort. This finding was further corroborated by the replication cohorts (OR = 1.16, 95% CI: 1.04-1.29, p = .01; OR = 1.12, 95% CI: 1.01-1.24, p = .03). The meta-analysis indicated that the overall odds ratio (OR) for all studies was 1.15 (common effect model, 95% CI: 1.08-1.23, p < .01). Sensitivity analysis suggested the absence of heterogeneity and horizontal pleiotropy in all MR analyses.

CONCLUSION

Based on bidirectional two-sample MR analysis, there is an indication that elevated eosinophil count may increase the risk of UC. However, potential confounding factors cannot be ruled out, and further research is necessary to explore how eosinophils contribute to the onset and progression of UC.

The chemistry of gut microbiome-derived lipopolysaccharides impacts on the occurrence of food allergy in the pediatric age

Introduction: Food allergy (FA) in children is a major health concern. A better definition of the pathogenesis of the disease could facilitate effective preventive and therapeutic measures. Gut microbiome alterations could modulate the occurrence of FA, although the mechanisms involved in this phenomenon are poorly characterized. Gut bacteria release signaling byproducts from their cell wall, such as lipopolysaccharides (LPSs), which can act locally and systemically, modulating the immune system function. Methods: In the current study gut microbiome-derived LPS isolated from fecal samples of FA and healthy children was chemically characterized providing insights into the carbohydrate and lipid composition as well as into the LPS macromolecular nature. In addition, by means of a chemical/MALDI-TOF MS and MS/MS approach we elucidated the gut microbiome-derived lipid A mass spectral profile directly on fecal samples. Finally, we evaluated the pro-allergic and pro-tolerogenic potential of these fecal LPS and lipid A by harnessing peripheral blood mononuclear cells from healthy donors. Results: By analyzing fecal samples, we have identified different gut microbiome-derived LPS chemical features comparing FA children and healthy controls. We also have provided evidence on a different immunoregulatory action elicited by LPS on peripheral blood mononuclear cells collected from healthy donors suggesting that LPS from healthy individuals could be able to protect against the occurrence of FA, while LPS from children affected by FA could promote the allergic response. Discussion: Altogether these data highlight the relevance of gut microbiome-derived LPSs as potential biomarkers for FA and as a target of intervention to limit the disease burden.

Conserved and tissue-specific immune responses to biologic scaffold implantation

Upon implantation into a patient, any biomaterial induces a cascade of immune responses that influences the outcome of that device. This cascade depends upon several factors, including the composition of the material itself and the location in which the material is implanted. There is still significant uncertainty around the role of different tissue microenvironments in the immune response to biomaterials and how that may alter downstream scaffold remodeling and integration. In this study, we present a study evaluating the immune response to decellularized extracellular matrix materials within the intraperitoneal cavity, the subcutaneous space, and in a traumatic skeletal muscle injury microenvironment. All different locations induced robust cellular recruitment, specifically of macrophages and eosinophils. The latter was most prominent in the subcutaneous space. Intraperitoneal implants uniquely recruited B cells that may alter downstream reactivity as adaptive immunity has been strongly implicated in the outcome of scaffold remodeling. These data suggest that the location of tissue implants should be taken together with the composition of the material itself when designing devices for downline therapeutics.

The prevalence of Leucocytozoon spp. in nestlings of three wild raptor species including implications on haematological and blood chemistry values

Leucocytozoonosis is a vector-borne infection of birds, caused by members of the haemosporidian genus Leucocytozoon. The clinical presentation may range from asymptomatic to severe disease. Consequences of Leucocytozoon infection on blood profiles remain to be described, especially for different host species in the wild. In the current study, the prevalence of Leucocytozoon infection was determined in wild nestlings of three European raptor species, the common buzzard (Buteo buteo, n = 464), red kite (Milvus milvus, n = 46) and northern goshawk (Accipiter gentilis, n = 18). Among 528 nestlings, 51.9% (n = 274) were infected with Leucocytozoon spp., whereby the highest prevalence was found in common buzzards (54.9%), followed by red kites (32.6%) and northern goshawks (22.2%). For a subset of 87 individuals (50 common buzzards, 29 red kites, 8 northern goshawks), a detailed analysis of differential leukocyte counts and several blood chemistry parameters in response to infection was conducted: AP (alkaline phosphatase), AST (aspartate aminotransferase), GLDH (glutamate dehydrogenase), LDH (lactate dehydrogenase), GGT (gamma glutamyl transferase), CK (creatine kinase), BuChE (butyrylcholinesterase), BA (bile acids), ALB (albumin) and TP (total protein). Even though in the physiological range, infected nestlings displayed significantly increased levels of heterophils, aspartate aminotransferase, lactate dehydrogenase, bile acids and butyrylcholinesterase, but decreased lymphocyte and monocyte values compared to uninfected ones. Furthermore, significant species differences with regard to blood parameters, but no sex differences were found. Overall, obtained results show a high prevalence, but a low pathogenicity of Leucocytozoon spp. in wild raptor chicks, presumably resulting from coevolutionary adaptation, but show signatures of infection in the haematological and blood chemistry profiles.

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Leucocytozoon prevalence in nestlings of three wild raptor species was 52%.

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Common buzzards (Buteo buteo) showed the highest prevalence (55%).

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Examined blood parameter values varied with species, age and infection status.

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Leucocytozoon infections were associated with increased AST and BuChE.

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Leucocytozoon infections in Accipitridae nestlings seem to be of minor pathogenicity.

Intestinal eosinophils, homeostasis and response to bacterial intrusion

Eosinophils are traditionally considered as end-stage effector cells involved in the pathogenesis of Th2 immune-mediated disorders as well as in the protection against parasite infection. However, this restricted view has recently been challenged by a series of studies revealing the highly plastic nature of these cells and implication in various homeostatic processes. Large numbers of eosinophils reside in the lamina propria of the gastrointestinal tract, at the front line of host defence, where they contribute to maintain the intestinal epithelial barrier function in the face of inflammation-associated epithelial cell damage. Eosinophils confer active protection against bacterial pathogens capable of penetrating the mucosal barrier through the release of cytotoxic compounds and the generation of extracellular DNA traps. Eosinophils also integrate tissue-specific cytokine signals such as IFN-γ, which synergise with bacterial recognition pathways to enforce different context-dependent functional responses, thereby ensuring a rapid adaptation to the ever-changing intestinal environment. The ability of eosinophils to regulate local immune responses and respond to microbial stimuli further supports the pivotal role of these cells in the maintenance of tissue homeostasis at the intestinal interface.

Isolation and Functional Aspects of Eosinophil-Derived Exosomes

Eosinophils are granulocytes involved in inflammatory processes related to type 2 immune responses as allergy and parasitic infestation. Eosinophils are scarce in homeostatic situations, comprising 3-6% of total granulocytes. In peripheral blood, they have a life span of 18-25 h. These cells are characterized by the presence of several types of granules that are very important because of their functions. Recently, we have described that these immune cells are able to release exosomes, which are nanovesicles involved in intercellular communication and implicated in development of several diseases such as cancer, cardiovascular diseases, and asthma. Here, we describe a technique for isolation of eosinophil-derived exosomes from human peripheral blood and for their utilization in cell functional assays.

High IL-5 levels possibly contributing to HIV viremia in virologic non-responders at one year after initiation of anti-retroviral therapy

Lack of viral monitoring in HIV infected patients on anti-retroviral therapy in low income countries may result in missing virologic non-responders (VNR) who show immunologic recovery in spite of unsuppressed viral replication. Biomarkers and drug resistance patterns in these discordant patients in comparison to the concordant treatment failure group need to be studied to understand possible risk factors associated with this condition. HIV infected patients on anti-retroviral therapy for one year were enrolled under three categories namely VNRs (n = 25), treatment failures (n = 18) and treatment responders (n = 40). They were assessed for HIV drug resistance by sequencing, plasma cytokines by luminex assay, T cell activation status by flow cytometry and total IgE levels by ELISA. VNR and failure patients had significantly lower median baseline CD4 counts than the responders. VNRs had significantly higher CD4 counts but lower viral load than treatment failures at one year of ART. VNRs had the highest eosinophil counts and the highest IL-5 levels among all the groups. IL-5 levels in them correlated with their viral load values. Frequency of Treg cells was also highest among the VNR group participants. More than 60% of the viremic patients irrespective of their groups harboured multiple HIV drug resistance mutations and mutation pattern did not differ between the groups. Low baseline CD4 counts and presence of multiple drug resistance mutations in the viremic groups highlighted the importance of early ART initiation and viral load monitoring irrespective of presence of immunologic failure. High IL-5 levels in VNR group indicated a need for investigating causal relationship between IL-5 and viral replication to devise therapeutic strategies to control viremia.

First Case of Idiopathic Eosinophilic Meningoencephalitis in a Sheep

A 1.5-year-old ewe was presented with neurological signs that had been observed from about 2 days prior to death. There had been no clinical response to anti-inflammatory and antibiotic treatment. Histopathological examination of the brain revealed a severe and widespread eosinophilic meningoencephalomyelitis of unknown aetiology. Defining histological features included diffuse angiocentric eosinophilic infiltrates in the neuroparenchyma and meninges, neuronal necrosis, astrocytosis, neuropil vacuolation and occasional glial scars. Differential diagnostics for eosinophilic meningoencephalitis were taken into account and investigated by means of special stains, immunohistochemistry, bacteriology and polymerase chain reaction. No pathological changes or ancillary tests were supportive or revealed a specific aetiology for the condition and therefore it was considered idiopathic. Idiopathic meningoencephalitis is a rare disease, mainly described in man and rarely in dogs, with no apparent aetiological cause or potential breed predisposition. To our knowledge this is the first case of idiopathic eosinophilic meningoencephalitis in a sheep and provides a histopathological guideline for prospective comparative pathology studies.

A case of fatal disseminated strongyloidiasis accompanied with intestinal obstruction

Strongyloides stercoralis is an endemic parasite in some regions including the tropical and subtropical areas with high humidity. Most infections are asymptomatic with nonspecific signs and symptoms, making the final diagnosis complicated. Here, we report a patient referred to our hospital with signs consistent with sepsis, intestine obstruction, which finally died with the diagnosis of strongyloidiasis. The patient was from northern parts of Iran which are considered as endemic areas for S. stercoralis. In conclusion, there is an important message in this history, i.e. physicians should be aware of specific and non-specific signs of strongyloidiasis especially in people living in endemic areas to make an accurate final diagnosis by proper clinical and paraclinical examinations.

Label-free optical hemogram of granulocytes enhanced by artificial neural networks

An outstanding challenge for immunology is the classification of immune cells in a label-free fashion with high speed. For this purpose, optical techniques such as Raman spectroscopy or digital holographic microscopy have been used successfully to identify immune cell subsets. To achieve high accuracy, these techniques require a post-processing step using linear methods of multivariate processing, such as principal component analysis. Here we demonstrate for the first time a comparison between artificial neural networks and principal component analysis (PCA) to classify the key granulocyte cell lineages of neutrophils and eosinophils using both digital holographic microscopy and Raman spectroscopy. Artificial neural networks can offer advantages in terms of classification accuracy and speed over a PCA approach. We conclude that digital holographic microscopy with convolutional neural networks based analysis provides a route to a robust, stand-alone and high-throughput hemogram with a classification accuracy of 91.3 % at a throughput rate of greater than 100 cells per second.

Different Lymphocyte Populations Direct Dichotomous Eosinophil or Neutrophil Responses to Pulmonary Cryptococcus Infection

Many pulmonary infections elicit lymphocyte responses that lead to an accumulation of granulocytes in the lungs. A variety of lymphocytes are capable of directing eosinophils or neutrophils to the lungs, but the contribution of each subset remains enigmatic. In this study, we used a murine model to examine lymphocyte subsets that ultimately drive the eosinophil or neutrophil response to infection with the fungal pathogen Cryptococcus neoformans. We show that granulocytes are produced in the bone marrow, released into the blood stream, and accumulate in the lungs under the instruction of lung parenchymal lymphocytes. The eosinophils that populated the lungs of wild-type animals were highly dependent on Th cells or IL-5. Surprisingly, infected mice with Th cell impairment experienced a compensatory neutrophil response that required IL-17A. This unexpected swing in the response prompted us to investigate the ability of different lymphocyte subsets to produce this dichotomous eosinophilia or neutrophilia. We used mice with lymphocyte deficiencies to determine which of the remaining IL-5- or IL-17A-producing lymphocyte subsets dominated the neutrophil or eosinophil response. Finally, skewing the response toward neutrophil-inducing lymphocytes correlated with accelerated disease. Our data collectively demonstrate that the predominance of a lymphocyte subset determines the functional consequences of an immune response to pulmonary fungal infection that can ultimately affect disease.

Network pharmacology-based identification of key pharmacological pathways of Yin-Huang-Qing-Fei capsule acting on chronic bronchitis

For decades in China, the Yin-Huang-Qing-Fei capsule (YHQFC) has been widely used in the treatment of chronic bronchitis, with good curative effects. Owing to the complexity of traditional Chinese herbal formulas, the pharmacological mechanism of YHQFC remains unclear. To address this problem, a network pharmacology-based strategy was proposed in this study. At first, the putative target profile of YHQFC was predicted using MedChem Studio, based on structural and functional similarities of all available YHQFC components to the known drugs obtained from the DrugBank database. Then, an interaction network was constructed using links between putative YHQFC targets and known therapeutic targets of chronic bronchitis. Following the calculation of four topological features (degree, betweenness, closeness, and coreness) of each node in the network, 475 major putative targets of YHQFC and their topological importance were identified. In addition, a pathway enrichment analysis based on the Kyoto Encyclopedia of Genes and Genomes pathway database indicated that the major putative targets of YHQFC are significantly associated with various pathways involved in anti-inflammation processes, immune responses, and pathological changes caused by asthma. More interestingly, eight major putative targets of YHQFC (interleukin [IL]-3, IL-4, IL-5, IL-10, IL-13, FCER1G, CCL11, and EPX) were demonstrated to be associated with the inflammatory process that occurs during the progression of asthma. Finally, a molecular docking simulation was performed and the results exhibited that 17 pairs of chemical components and candidate YHQFC targets involved in asthma pathway had strong binding efficiencies. In conclusion, this network pharmacology-based investigation revealed that YHQFC may attenuate the inflammatory reaction of chronic bronchitis by regulating its candidate targets, which may be implicated in the major pathological processes of the asthma pathway.

The Eosinophil in Infection

First described by Paul Ehrlich in 1879, who noted its characteristic staining by acidophilic dyes, for many years, the eosinophil was considered to be an end-effector cell associated with helminth infections and a cause of tissue damage. Over the past 30 years, research has helped to elucidate the complexity of the eosinophil's function and establish its role in host defense and immunity. Eosinophils express an array of ligand receptors which play a role in cell growth, adhesion, chemotaxis, degranulation, and cell-to-cell interactions. They play a role in activation of complement via both classical and alternative pathways. Eosinophils synthesize, store and secrete cytokines, chemokines, and growth factors. They can process antigen, stimulate T cells, and promote humoral responses by interacting with B cells. Eosinophils can function as antigen presenting cells and can regulate processes associated with both T1 and T2 immunity. Although long known to play a role in defense against helminth organisms, the interactions of eosinophils with these parasites are now recognized to be much more complex. In addition, their interaction with other pathogens continues to be investigated. In this paper, we review the eosinophil's unique biology and structure, including its characteristic granules and the effects of its proteins, our developing understanding of its role in innate and adaptive immunity and importance in immunomodulation, and the part it plays in defense against parasitic, viral, fungal and bacterial infections. Rather than our worst enemy, the eosinophil may, in fact, be one of the most essential components in host defense and immunity.

IgE epitope proximity determines immune complex shape and effector cell activation capacity

Background

IgE-allergen complexes induce mast cell and basophil activation and thus immediate allergic inflammation. They are also important for IgE-facilitated allergen presentation to T cells by antigen-presenting cells.

Objective

To investigate whether the proximity of IgE binding sites on an allergen affects immune complex shape and subsequent effector cell activation in vitro and in vivo.

Methods

We constructed artificial allergens by grafting IgE epitopes in different numbers and proximity onto a scaffold protein. The shape of immune complexes formed between artificial allergens and the corresponding IgE was studied by negative-stain electron microscopy. Allergenic activity was determined using basophil activation assays. Mice were primed with IgE, followed by injection of artificial allergens to evaluate their in vivo allergenic activity. Severity of systemic anaphylaxis was measured by changes in body temperature.

Results

We could demonstrate simultaneous binding of 4 IgE antibodies in close vicinity to each other. The proximity of IgE binding sites on allergens influenced the shape of the resulting immune complexes and the magnitude of effector cell activation and in vivo inflammation.

Conclusions

Our results demonstrate that the proximity of IgE epitopes on an allergen affects its allergenic activity. We thus identified a novel mechanism by which IgE-allergen complexes regulate allergic inflammation. This mechanism should be important for allergy and other immune complex–mediated diseases.

Changing roles of eosinophils in health and disease

OBJECTIVE

To review and highlight the unappreciated roles of eosinophils suggested by recent studies.

DATA SOURCES

The literature, unpublished observations, and insights by the authors.

STUDY SELECTIONS

Basic studies of mouse models and patient-based clinical studies of disease.

RESULTS

Eosinophils are often thought of as destructive end-stage effector cells primarily linked to parasite host defense and dysregulated immune responses associated with allergic diseases, such as asthma. However, recent studies (ie, research focused on mechanisms of action and translational studies examining disease/inflammatory pathways) are suggesting far more complex roles for eosinophils. The goal of this review is 3-fold. (1) The authors examine the dynamic history of eosinophils and how physicians over time used this information to formulate defining hypotheses. Particular emphasis is placed on recent studies challenging the parochial view of host defense in favor of roles maintaining homeostasis through immune modulation and tissue remodeling/repair. (2) They discuss diagnostic approaches to assess eosinophils in clinical settings as a means of disease identification and subsequently as a measurement of disease severity. (3) They examine how contemporary views of eosinophils and their perceived roles in diseases have led to specific therapeutic strategies. The emphasis is to review the successes and failures of these strategies as the basis of formulating future clinical studies targeting eosinophils as potential therapies of disease.

CONCLUSION

Despite the complexities of eosinophil-mediated activities and the less than overwhelming success of initial attempts targeting these cells, eosinophils remain a potentially important focal target of disease diagnosis and subsequent treatment strategies.

Specific IgE Anti-Ascaris in Brazilian Children and Adolescents

From an article published by our group by Medeiros et al, we discuss and review the literature on the role of serum specific anti-ascaris IgE in patients with respiratory allergies living in countries where helminthic infestations are common. Medeiros et al conducted a study using 101 patients aged 12 to 21 years with respiratory allergy. Median IgE level was 660 IU/mL. Serum specific anti-ascaris IgE was positive in 73% (74/101) of the individuals, but parasitological stool examination yielded positive results in only 33.7% (34/101). The correlation coefficient between serum total IgE level and serum specific anti-ascaris IgE was 0.52 (P < 0.001) and this effect occurred regardless of eosinophil count and of the presence of intestinal helminthic infection. In patients with respiratory allergy with very high serum total IgE levels, in whom the past or present history of parasitic infection is a possible explanation, the presence of serum specific anti-ascaris IgE was common and should be better evaluated in allergic patients from Ascaris lumbricoides endemic areas.

Study of the uterine local immune response in a murine model of embryonic death due to Tritrichomonas foetus

PROBLEM

Bovine tritrichomonosis is a sexually transmitted disease caused by Tritrichomonas foetus, characterized by conceptus loss. We developed a mouse model of tritrichomonosis to study the mechanisms involved in the embryonic death. We hypothesized that embryonic death may be due to an exacerbated maternal response to the pathogen that then affects embryo development.

METHOD OF STUDY

We infected BALB/c mice with Tritrichomonas foetus and paired them after confirming active infection. We studied the expression of pro- and anti-inflammatory cytokines, markers for T regulatory and T helper 17 cells as well as haem-oxygenase-1 expression in uterine tissue by real-time RT-PCR.

RESULTS

As expected, TNF-α was augmented in infected animals. IL-10 and IL-4 were also up-regulated. Treg-associated genes were higher expressed in uteri of infected group. In mice that have lost their conceptus after the infection, haem-oxygenase-1 (HO-1) mRNA levels were strongly decreased, while RORγt mRNA, a reliable marker for Th17, was augmented in uterus.

CONCLUSION

A T effector response of type 1 and 17 may be involved in tritrichomonosis-related embryonic death. This alters protective mechanisms as HO-1. Increased regulatory T cells may facilitate embryonic death by promoting the persistence of infection.

The influence of reproductive physiology and nutrient supply on the periparturient relaxation of immunity to the gastrointestinal nematode Trichostrongylus colubriformis in Merino ewes

A pen experiment was conducted to investigate the interaction of early-weaning and nutrient supply on the periparturient relaxation of immunity to the gastrointestinal nematode (GIN) Trichostrongylus colubriformis in Merino ewes. Mixed-age pregnant and non-pregnant (dry) ewes were infected with 8,000 T. colubriformis L(3)/week, and fed either a high or low quality diet. Following parturition, lambs were either removed from their mothers at 2 days of age or allowed to continue suckling. Systemic immunity began to wane during late pregnancy with circulating eosinophils and plasma total antibody (Ab) levels declining from day -37 (relative to the midpoint of lambing) and day -24, respectively. Pregnant ewes fed the low quality diet exhibited an increasing faecal worm egg count (WEC) from day -24 and had higher intestinal worm burdens on day 13, whereas ewes fed the high quality diet had a delayed transient rise in WEC of lower magnitude. Dry and early-weaned ewes remained highly resistant to T. colubriformis at all times. In the post-lambing/lactation period, ewes fed the high quality diet had higher levels of local total Ab and numbers of goblet cells (GC) in the small intestine on days 13 and 41. Lactating/suckled ewes had a lower anti-parasite local immune response as indicated by reduced titres of total Ab, IgG(1), IgM and IgA and lower numbers of mucosal mast cells (MMC), globule leukocytes (GL) and GC in small intestinal tissue compared to their dry and early-weaned counterparts. Early-weaning resulted in rapid recovery of blood eosinophils and total Ab. On day 13 post-lambing, titres of total Ab, IgG(1), IgM, IgA and IgE, and numbers of MMC and GL were greater than those measured in dry and suckled ewes. When fed the high quality diet, ewes had a higher dry matter (DM) intake, maternal weight, fat score, greater fat depth and eye muscle depth, birthed heavier lambs that had higher growth rates, and produced more milk. The physiological status of pregnancy resulted in a higher DM intake but lower measures of fat depth and eye muscle depth, and suckling led to an increase in DM intake but a reduction in body weight and fat score through mobilisation of fat and muscle reserves. Despite the marked effect of diet quality on production traits, some inconsistencies were observed between body composition and apparent parasite resistance, measured by WEC and worm counts, suggesting that the nutritional influence was not necessarily always mediated through changes in body composition. Although reproductive status affected blood leptin levels, diet had no effect within suckled ewes and therefore it was concluded that leptin has no causative role in maintaining the periparturient relaxation of immunity to T. colubriformis.

Basis of the intrinsic flexibility of the Cε3 domain of IgE

Allergic reactions are triggered by the interaction between IgE and its high-affinity receptor, FcεRI. Various studies have mapped the interaction surface between IgE and its cellular receptors to the third constant domain of IgE (Cε3). The isolated Cε3 domain has been shown to exist as a molten globule, and the domain retains significant flexibility within the context of the IgE protein. Here we have analyzed the structural basis of the intrinsic flexibility of this domain. We have compared the sequence of the Cε3 domain to the sequences of other members of the C1 subset of the immunoglobulin superfamily and observed that Cε3 has an unusually high electrostatic charge and an unusually low content of hydrophobic residues. Mutations restoring Cε3 to a more canonical sequence were introduced in an attempt to derive a more structured domain, and several mutants display decreased levels of disorder. Engineered domains of Cε3 with a range of structural rigidities could serve as important tools for the elucidation of the role of flexibility of the Cε3 domain in IgE's biological functions.

Advances in helminth immunology: optimism for future vaccine design?

Intestinal helminths infect approximately 2 billion people worldwide. Worm burdens correlate with disease morbidity and children generally harbor the largest numbers. The majority of intestinal helminths do not replicate within their host, and worm burdens increase through constant reinfection. Current strategies of worm control involve drug administration to school-aged children. Yet the rapid rate of reinfection and the appearance of drug resistant strains in livestock raise concerns over the sustainable nature of this strategy. A combined strategy of drug treatment for the expulsion of adult worms and vaccination designed to halt reinfection would offer the most effective means of control. Before successful vaccines can be developed our knowledge of the initiation and implementation of host immunity must be improved.

Murine lung eosinophil activation and chemokine production in allergic airway inflammation

Eosinophils play important roles in asthma and lung infections. Murine models are widely used for assessing the functional significance and mechanistic basis for eosinophil involvements in these diseases. However, little is known about tissue eosinophils in homeostasis. In addition, little data on eosinophil chemokine production during allergic airway inflammation are available. In this study, the properties and functions of homeostatic and activated eosinophils were compared. Eosinophils from normal tissues expressed costimulation and adhesion molecules B7-1, B7-2 and ICAM-1 for Ag presentation but little major histocompatibility complex (MHC) class II, and were found to be poor stimulators of T-cell proliferation. However, these eosinophils expressed high levels of chemokine mRNA including C10, macrophage inflammatory protein (MIP)-1alpha, MIP-1gamma, MIP-2, eotaxin and monocyte chemoattractant protein-5 (MCP-5), and produced chemokine proteins. Eosinophil intracellular chemokines decreased rapidly with concomitant surface marker downregulation upon in vitro culturing consistent with piecemeal degranulation. Lung eosinophils from mice with induced allergic airway inflammation exhibited increased chemokines mRNA expression and chemokines protein production and upregulated MHC class II and CD11c expression. They were also found to be the predominant producers of the CCR1 ligands CCL6/C10 and CCL9/MIP-1gamma in inflamed lungs. Eosinophil production of C10 and MIP-1gamma correlated with the marked influx of CD11b(high) lung dendritic cells during allergic airway inflammation and the high expression of CCR1 on these dendritic cells (DCs). The study provided baseline information on tissue eosinophils, documented the upregulation of activation markers and chemokine production in activated eosinophils, and indicated that eosinophils were a key chemokine-producing cell type in allergic lung inflammation.

Update on eosinophilic meningoencephalitis and its clinical relevance

Eosinophilic meningoencephalitis is caused by a variety of helminthic infections. These worm-specific infections are named after the causative worm genera, the most common being angiostrongyliasis, gnathostomiasis, toxocariasis, cysticercosis, schistosomiasis, baylisascariasis, and paragonimiasis. Worm parasites enter an organism through ingestion of contaminated water or an intermediate host and can eventually affect the central nervous system (CNS). These infections are potentially serious events leading to sequelae or death, and diagnosis depends on currently limited molecular methods. Identification of parasites in fluids and tissues is rarely possible, while images and clinical examinations do not lead to a definitive diagnosis. Treatment usually requires the concomitant administration of corticoids and anthelminthic drugs, yet new compounds and their extensive and detailed clinical evaluation are much needed. Eosinophilia in fluids may be detected in other infectious and noninfectious conditions, such as neoplastic disease, drug use, and prosthesis reactions. Thus, distinctive identification of eosinophils in fluids is a necessary component in the etiologic diagnosis of CNS infections.

Lipopolysaccharide-driven Th2 cytokine production in macrophages is regulated by both MyD88 and TRAM

Gram-negative bacterial lipopolysaccharide (LPS) activates macrophages by interacting with Toll-like receptor 4 (TLR4) and triggers the production of various pro-inflammatory Th1 type (type 1) cytokines such as IFNgamma, TNFalpha, and IL8. Though some recent studies cited macrophages as potential sources for Th2 type (type 2) cytokines, little however is known about the intracellular events that lead to LPS-induced type 2 cytokines in macrophages. To understand the mechanisms by which LPS induces type 2 cytokine gene expression, macrophages were stimulated with LPS, and the expression of IL-4 and IL-5 genes were examined. LPS, acting through TLR4, activates both type 1 and type 2 cytokine production both in vitro and in vivo by using macrophages from C3H/HeJ or C3H/HeOuJ mice. Although the baseline level of both TNFalpha and IL-4 protein was very low, TNFalpha was released rapidly after stimulation (within 4 h); however, IL-4 was released after 48 h LPS stimulation in secreted form. Silencing of myeloid differentiation protein (MyD88) and TRIF-related adaptor molecule (TRAM), using small interfering RNA abolished IL-4 induction induced by LPS whereas silencing of TRAM has no effect on TNFalpha induction, thereby indicating that LPS-induced TNFalpha is MyD88-dependent but IL-4 is required both MyD88 and TRAM. These findings suggest a novel function of LPS and the signaling pathways in the induction of IL-4 gene expression.

Histopathology for the diagnosis of infectious diseases

Histopathological examination of tissue biopsies for the identification of infectious organisms is a very important diagnostic tool. Conventional culture confirmation of tissue biopsies often fail to identify any pathogen as, first of all, invariably most of the tissue samples that are collected and sent for culture isolation are inappropriately collected in formalin, which prevents pathogen growth in culture media. Inadequate processing like grinding, etc. further hinders isolation. Presence of inhibitors like dead tissue debris, fibers, etc. also delays isolation. Microbiologists often lack expertise in identifying infectious pathogens directly from tissue biopsies by microscopic visualization. This review therefore acquaints microbiologists with the various methods available for detecting infectious agents by using histological stains. On histopathological examination of the tissue biopsy once, it is determined that a disease is likely to be due to an infection and has characterized the inflammatory response and hence associated microorganisms should be thoroughly looked for. Although some microorganisms or their cytopathic effects may be clearly visible on routine haematoxylin- and eosin-stained sections, additional histochemical stains are often needed for their complete characterization. Highly specific molecular techniques, such as immunohistochemistry, in situ hybridization and nucleic acid amplification, may be needed in certain instances to establish the diagnosis of infection. Through appropriate morphologic diagnoses and interlaboratory communication and collaboration, direct microscopic visualization of tissue samples can thus be very helpful in reaching a correct and rapid diagnosis.

The mucosal immune system at the gastrointestinal barrier

The immune system faces a considerable challenge in its efforts to maintain tissue homeostasis in the intestinal mucosa. It is constantly confronted with a large array of antigens, and has to prevent the dissemination and proliferation of potentially harmful agents while sparing the vital structures of the intestine from immune-mediated destruction. Complex interactions between the highly adapted effector cells and mechanisms of the innate and adaptive immune system generally prevent the luminal microflora from penetrating the intestinal mucosa and from spreading systemically. Non-haematopoietic cells critically contribute to the maintenance of local tissue homeostasis in an antigen-rich environment by producing protective factors (e.g. production of mucus by goblet cells, or secretion of microbicidal defensins by Paneth cells) and also through interactions with the adaptive and innate immune system (such as the production of chemotactic factors that lead to the selective recruitment of immune cell subsets). The complexity of the regulatory mechanisms that control the local immune response to luminal antigens is also reflected in the observation that mutations in immunologically relevant genes often lead to the development of uncontrolled inflammatory reactions in the microbially colonized intestine of experimental animals.

IgE in allergy and asthma today

The spreading epidemic of allergies and asthma has heightened interest in IgE, the central player in the allergic response. The activity of IgE is associated with a network of proteins; prominent among these are its two principal receptors, FcepsilonRI (high-affinity Fc receptor for IgE) and CD23, as well as galectin-3 and several co-receptors for CD23, notably CD21 and various integrins. Here, we review recent progress in uncovering the structures of these proteins and their complexes, and in our understanding of how IgE exerts its effects and how its expression is regulated. The information that has emerged suggests new therapeutic directions for combating allergic disease.

Cellular aspects of atopic dermatitis

Atopic dermatitis (AD) is a highly pruritic, chronic, and relapsing inflammatory skin disease. Recent interest in AD has been sparked by reports of its increasing prevalence and its contribution to increasing health care costs. A precise understanding of immunologic mechanisms is crucial for the development of effective treatment strategies for AD. Various studies reveal that AD has a multifactorial cause with the activation of complex immunologic and inflammatory pathways. This review will discuss cellular-mediated immunological pathomechanisms of AD. Emphasis will be given to the role played by T cells, antigen-presenting cells, eosinophils, and keratinocytes. We also examine the immunological effect of superantigens on various inflammatory cells including T regulatory cells.

Innate immune function of eosinophils: from antiparasite to antitumor cells

Eosinophils are multifunctional leukocytes classically described as being involved in helminth parasitic infections and allergic diseases. Previously restricted to an exclusive role in the release of cytotoxic mediators, they are now also considered to be immunoregulatory cells and potential effectors in innate immune responses. Eosinophils are mainly found in tissues, so specific procedures are needed for their isolation from venous blood and for functional assays. Murine models are very useful for the dissection of eosinophil physiology in vivo. But murine eosinophils significantly differ from human ones. A complete understanding of eosinophil biology therefore requires comparative study of eosinophils from different mammalian species. We summarize here the main experimental protocols used to study human, mouse, and rat eosinophil biology. We focus on technical improvements of existing methods that optimize purification and in vitro functional studies of eosinophils.

Regulation of the Il4 gene is independently controlled by proximal and distal 3' enhancers in mast cells and basophils

Mast cells and basophils are known to be a critical interleukin 4 (IL-4) source for establishing Th2 protective responses to parasitic infections. Chromatin structure and histone modification patterns in the Il13/Il4 locus of mast cells were similar to those of IL-4-producing type 2 helper T cells. However, using a transgenic approach, we found that Il4 gene expression was distinctly regulated by individual cis regulatory elements in cell types of different lineages. The distal 3' element contained conserved noncoding sequence 2 (CNS-2), which was a common enhancer for memory phenotype T cells, NKT cells, mast cells, and basophils. Targeted deletion of CNS-2 compromised production of IL-4 and several Th2 cytokines in connective-tissue-type and immature-type mast cells but not in basophils. Interestingly, the proximal 3' element containing DNase I-hypersensitive site 4 (HS4), which controls Il4 gene silencing in T-lineage cells, exhibited selective enhancer activity in basophils. These results indicate that CNS-2 is an essential enhancer for Il4 gene transcription in mast cell but not in basophils. The transcription of the Il4 gene in mast cells and basophils is independently regulated by CNS-2 and HS4 elements that may be critical for lineage-specific Il4 gene regulation in these cell types.

IL-5-induced hypereosinophilia suppresses the antigen-induced immune response via a TGF-beta-dependent mechanism

Although eosinophils play an essential role in allergic inflammation, their role has recently been under controversy. Epidemic studies suggest that hypereosinophilia induced by parasite infection could suppress subsequent Ag sensitization, although the mechanism has not been fully clarified. In this study, we investigated whether eosinophils could suppress the Ag-specific immune response in the airway. BALB/c mice were sensitized and airway challenged with OVA. Systemic hypereosinophilia was induced by delivery of an IL-5-producing plasmid. IL-5 gene delivery suppressed the Ag-specific proliferation and cytokine production of CD4+ T cells in the spleen. IL-5 gene delivery before OVA sensitization significantly suppressed airway eosinophilia and hyperresponsiveness provoked by subsequent OVA airway challenge, while delivery during the OVA challenge did not suppress them. This IL-5-induced immune suppression was abolished in eosinophil-ablated mice, suggesting an essential role of eosinophils. IL-5 treatment increased the production of TGF-beta1 in the spleen, and we demonstrated that the main cellular source of TGF-beta1 production was eosinophils, using eosinophil-ablated mice and depletion study. TGF-beta1, but not IL-5 itself, suppressed the Ag-specific immune response of CD4+ T cells in vitro. Furthermore, IL-5 treatment enhanced phosphorylation of Smad2 in CD4+ T cells. Finally, a TGF-beta type I receptor kinase inhibitor restored this IL-5-induced immune suppression both in vitro and in vivo. These results suggest that IL-5-induced hypereosinophilia could suppress sensitization to Ag via a TGF-beta-dependent mechanism, thus suppressed allergic airway inflammation. Therefore, hypereosinophilia could reveal an immunosuppressive effect in the early stage of Ag-induced immune response.

Relationship between eosinophilia and levels of chemokines (CCL5 and CCL11) and IL-5 in bronchoalveolar lavage fluid of patients with mustard gas-induced pulmonary fibrosis

OBJECTIVE

Therefore, this study was designed to analyze the bronchoalveolar lavage (BAL) fluid concentrations of IL-5, RANTES (CCL5) and eotaxin (CCL11) and also to examine the relationship between the percentage and absolute number of the BAL eosinophils and these measured chemokines in patients with sulfur mustard (SM) gas-induced pulmonary fibrosis (PF).

PATIENTS

Fifteen veterans with mustard gas-induced PF and 14 normal veterans as control group.

INTERVENTION

Pulmonary function tests, tests for D(LCO), computed tomography scans of the chest, analyses of BAL fluids for RANTES (CCL5), eotaxin (CCL11), and IL-5 were performed in all cases.

RESULTS

Eosinophilic alveolitis was the predominant feature (p < 0.0001). There were significant differences in CCL5, CCL11, and IL-5 levels of BAL fluid between patients with PF and controls (p < 0.0001, p < 0.0001, and p = 0.001, respectively). The concentrations of CCL5 and CCL11 showed positive correlations with percentage (r = 0.57 and p = 0.03; r = 0.52 and p = 0.04, respectively) and absolute counts (r = 0.54 and p = 0.04, r = 0.53 and p = 0.04, respectively) of BAL eosinophils. There were significant positive correlations between the concentrations of IL-5 and the proportion and total cell number of eosinophils in BAL (r = 0.67 and p = 0.01; r = 0.59 and p = 0.02, respectively) too.

CONCLUSION

A significant correlation between BAL CCL5, CCL11, and IL-5 levels and eosinophils in patients with pulmonary fibrosis due to SM gas inhalation has been demonstrated, suggesting that these C-C chemokines and IL-5 contribute to the recruitment of eosinophils cells in the lung in these victims.

Eosinophilia is induced in the colon of Th2-sensitized mice upon exposure to locally expressed antigen

Eosinophilic inflammation is a feature of a variety of gastrointestinal (GI) disorders including eosinophil-associated GI disorder, allergy, inflammatory bowel disease, and parasite infection. Elucidating the mechanisms of eosinophil infiltration into the GI tract is important to the understanding of multiple disease processes. We hypothesize that eosinophilia in the large intestine (colon) can be induced by an antigen in a host that is associated with Th2-skewed antigen-specific immune responses. To investigate the importance of antigenic triggering, we established polarized antigen-specific Th2 type responses in BALB/c mice, using ovalbumin in conjunction with aluminum hydroxide. Upon challenge at the colonic mucosa through transient (3-4 days) expression of the antigen gene encoded in an adenovirus vector, sensitized animals developed significant subepithelial colonic inflammation, characterized by marked eosinophilic infiltration, and the presence of enlarged and increased numbers of lymphoid follicles. The alterations peaked around day 5 and resolved over the next 5-10 days, and no epithelial cell damage was detected through the entire course. Administration of a control (empty) adenovirus vector did not lead to any pathological changes. These data suggest that colonic eosinophilia can be induced by exposure to an antigen associated with preexisting Th2-skewed responses. Thus the model established here may provide a useful tool to study GI and, in particular, colonic inflammation with respect to underlying mechanisms involved in the recruitment and the immediate function of eosinophils.

Stimulation of the In Vitro Migration of Ovine Eosinophils by Factors Derived from the Sheep Scab Mite, Psoroptes ovis

The ectoparasitic astigmatid mite Psoroptes ovis causes sheep scab, a highly contagious, severe allergic dermatitis associated with damage to the fleece and hide, loss of condition and occasional mortality. The scab lesion is characterized by a massive infiltration of eosinophils that begins very rapidly after infection. This paper reports the finding that mite-derived factors directly enhance the migration of ovine eosinophils in vitro. Significant (p < 0.01) and dose-dependent (r = 0.972 +/- 0.018 (SD)) activity was initially identified in whole mite extracts, by comparison with medium controls in an assay based on modified Boyden chambers and ovine bone marrow target cells. Similar pro-migratory activity (p < 0.005; r = 0.928 +/- 0.069 (SD)) was detected in washes containing mite excretory/secretory material. By direct comparison with migration ratios (n = 3) for defined chemotactic (rmeotaxin = 3.430 +/- 0.360 (SD)) and chemokinetic (rminterleukin-5 = 0.982 +/- 0.112 (SD)) stimuli it was determined that the activity in both mite extracts (0.992 +/- 0.038 (SD)) and mite washes (0.969 +/- 0.071 (SD)) was chemokinetic. Subsequent experiments (n = 3) in which live mites were incorporated directly into the in vitro assay system indicated that they produced factors that significantly (p < 0.001) enhanced eosinophil migration to a degree directly related to mite numbers (r = 0.993 +/- 0.005 (SD)). The identity of the factor(s) responsible is uncertain, but their presence suggests that mites may be capable of directly activating eosinophils in vivo, and raises the possibility that mites could directly influence, perhaps even initiate, the rapid early tissue eosinophilic response observed in experimental sheep scab infections.

High expression of co-stimulatory and adhesion molecules are observed on eosinophils during human Schistosoma mansoni infection

Herein we have focused attention on major phenotypic features of peripheral blood eosinophils from chronic Schistosoma mansoni-infected patients. For this purpose, detailed immunophenotypic profiles of a range of cell surface markers were performed, including activation markers (CD23/CD69/CD25/HLA-DR), co-stimulatory molecules (CD28/CD80/CD86), chemokine receptors (CXCR1/CXCR2/CCR3/CCR5) besides L-selectin-CD62L and adhesion molecules (CD18/CD54). Our major findings pointed out increased frequency of CD23+-cells, besides decreased percentages of CD69+-eosinophils, suggesting a chronic activation status with low frequency of early activated eosinophils in chronic S. mansoni-infected patients (INT) in comparison to non-infected individuals (NI). Moreover, a dichotomic expression of beta-chemokine receptors was observed during human schistosomiasis mansoni with higher CCR5 and lower levels of CCR3 observed between groups. Enhanced expression of co-stimulatory receptors (CD28/CD86) and adhesion molecules (CD54/CD18), besides striking lower frequency of L-selectin+ were reported for eosinophils from INT group as compared to NI. Interestingly, the frequency of CD62L+-eosinophils and a range of cell activation related molecules pointed out an opposite pattern of association in NI and INT, where only INT patients that display lower frequency of CD62L+-eosinophils (first CD62L tertile) kept the unusual relationship between the expression of L-selectin and the CD23 activation marker. These findings suggest that distinct dynamic of activation markers expressed by eosinophils may occur during chronic S. mansoni infection.

Schistosoma mansoni infection in eosinophil lineage-ablated mice

We explore the controversial issue of the role of eosinophils in host defense against helminthic parasites using the established Schistosoma mansoni infection model in 2 novel mouse models of eosinophil lineage ablation (DeltadblGATA and TgPHIL). No eosinophils were detected in bone marrow of infected DeltadblGATA or TgPHIL mice, despite the fact that serum IL-5 levels in these infected mice exceeded those in infected wild type by approximately 4-fold. Liver granulomata from infected DeltadblGATA and TgPHIL mice were likewise depleted of eosinophils compared with those from their respective wild types. No eosinophil-dependent differences in granuloma number, size, or fibrosis were detected at weeks 8 or 12 of infection, and differential accumulation of mast cells was observed among the DeltadblGATA mice only at week 12. Likewise, serum levels of liver transaminases, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) increased in all mice in response to S mansoni infection, with no eosinophil-dependent differences in hepatocellular damage observed. Finally, eosinophil ablation had no effect on worm burden or on egg deposition. Overall, our data indicate that eosinophil ablation has no impact on traditional measures of disease in the S mansoni infection model in mice. However, eosinophils may have unexplored immunomodulatory contributions to this disease process.

Eosinophils and urticaria

Previously believed to have an exclusive role in the release of cytotoxic mediators in the defense against helminthic infections, eosinophils are now considered key players in inflammatory reaction and regulation of immune response. Through activation of a large variety of membrane receptors and production of various pharmacologically active mediators, eosinophils may exert a detrimental role in tissues in which they have been recruited and may contribute to the perennization of inflammatory processes. The crucial role of eosinophils has been documented in several eosinophilic skin diseases, such as hypereosinophilic syndrome and bullous pemphigoid, and the literature provides strong evidence for their role in urticaria. The aim of this article is to discuss the mechanisms of specific tissue recruitment of eosinophils, the factors of eosinophil activation, and the contribution of these cells to inflammation and immunoregulation in urticaria. Recent advances in the knowledge of eosinophils will certainly help toward developing new strategies for the management of antihistamines resistant to urticaria.

Modulation of eosinophil generation and migration by Mangifera indica L. extract (Vimang)

The effects of Vimang, an aqueous extract of the stem bark of Mangifera indica L. (Anacardiaceae), on cell migration in an experimental model of asthma was investigated. In vivo treatment of Toxocara canis-infected BALB/c mice for 18 days with 50 mg/kg Vimang reduced eosinophil migration into the bronchoalveolar space and peritoneal cavity. Also, eosinophil generation in bone marrow and blood eosinophilia were inhibited in infected mice treated with Vimang. This reduction was associated with inhibition of IL-5 production in serum and eotaxin in lung homogenates. In all these cases the effects of Vimang were more selective than those observed with dexamethasone. Moreover, Vimang treatment is not toxic for the animals, as demonstrated by the normal body weight increase during infection. These data confirm the potent anti-inflammatory effect of Vimang and support its potential use as an alternative therapeutic drug to the treatment of eosinophilic disorders including those caused by nematodes and allergic diseases.

The alpha4bbeta7-integrin is dynamically expressed on murine eosinophils and involved in eosinophil trafficking to the intestine

BACKGROUND

Of the numerous adhesion molecules expressed by eosinophils, the alpha4-integrin has been identified as critically involved in eosinophil trafficking in the lung. Most studies have focused on the role of the alpha4beta1-adhesion complex, but eosinophils also express the alpha4beta7-integrin complex.

OBJECTIVE

To investigate the role of alpha4beta7, by assessing its membrane expression on eosinophils from different compartments using allergen-challenged mice and IL-4/IL-5 bi-transgenic mice. In addition, we aim to determine the impact of beta7-integrin deficiency on eosinophil recruitment to the lungs and intestine in specific experimental allergic models.

RESULTS

Evaluation of alpha4beta7 expression on bronchoalveolar lavage fluid (BALF) and lung tissue eosinophils revealed a down-regulation of this integrin as eosinophils migrate through the lungs. Indeed eosinophils isolated from the BALF and lung of allergic mice had low expression of the alpha4beta7-complex. While expression of the alpha4-chain remained unchanged, a significant decrease in beta7-surface expression was observed. Intestinal eosinophils, isolated from Peyer's patches, also displayed a down-regulation of the alpha4beta7-integrin, albeit only modest. In contrast, circulating eosinophils, isolated from the blood and spleen, expressed high levels of the alpha4beta7-integrin. However, eosinophil trafficking into the lungs of beta7-integrin-deficient mice was not significantly impaired in response to respiratory allergen challenges. In contrast, beta7-deficient mice had impaired eosinophil recruitment to the intestine.

CONCLUSION

Taken together, these results identify differential expression of the alpha4beta7-integrin on eosinophils and its critical role in regulating eosinophil responses in the intestine.

[Eosinophils: structure and functions]

Long considered to be secondary cells characterized mainly by their ability to be recruited to inflammation sites, these cells are now known to release a wide array of cytotoxic mediators. Moreover they participate in immune response regulation by producing Th1 and Th2 cytokines as well as regulatory cytokines and chemokines. This review describes recent findings about their expression of surface molecules, eosinophil mediators, and the role of both in these novel eosinophil functions.

Increased expression of chemokines in the skin of chronic proliferative dermatitis mutant mice

Chemokines direct the migration of leukocytes to sites of inflammation and are potential targets for anti-inflammatory therapy. Chronic proliferative dermatitis (cpdm/cpdm) mutant mice develop a persistent eosinophilic dermatitis associated with increased T(H)2 cytokines in the skin. Expression patterns of chemokines in the skin of cpdm/cpdm mice were evaluated to define the mechanisms driving cutaneous infiltration by leukocytes. RNA isolated from the skin of mutant and littermate control mice revealed a significant increase in Ccl1 (TCA-3), Ccl2 (MCP-1), Ccl11 (eotaxin), Ccl17 (TARC), Cxcl10 (IP-10), and the chemokine receptor Ccr3. The concentration of CCL11 protein was increased two- to threefold in the skin of cpdm/cpdm mice by enzyme-linked immunosorbent assay. In vitro culture of primary dermal fibroblasts from cpdm/cpdm and control mice with tumor necrosis factor, IL-4, and IL-13 stimulation did not reveal differences in their ability to secrete CCL11, suggesting that the increased chemokine expression observed in the skin of cpdm/cpdm mice is most likely caused by the increased T(H)2 cytokines in the dermis of this mouse model. Treatment of cpdm/cpdm mice with CCL11-neutralizing polyclonal antibodies did not affect the number of eosinophils in the skin or the severity of the dermatitis. Neutralizing multiple chemokines or chemokine receptors may be necessary to decrease eosinophil accumulation. The cpdm/cpdm mutant mouse is a potentially useful model to determine the role of various chemokines in eosinophil accumulation in chronic inflammation.

Exploiting the innate immune system to control allergic asthma

NKT cells are key actors at the interface between innate and acquired immunity. Indeed, upon activation by glycolipid antigens, they rapidly secrete both Th1 and Th2 cytokines, which affects the development of later immune responses. Previous studies have shown that NKT cells are essential for the development of allergic asthma, a prototypical Th2-mediated pathology. By contrast, three papers, two of which are published in this issue of the European Journal of Immunology, demonstrate, in mouse models, that treatment with alpha-galactosylceramide, a specific NKT ligand, inhibits most of the parameters associated with the disease, including airway hyperreactivity, eosinophilia and IgE production. Increased IFN-gamma synthesis, rather than regulatory IL-10, accounts for this paradoxical effect.

Gastrointestinal food allergy: new insights into pathophysiology and clinical perspectives

Adverse reactions to food that result in gastrointestinal symptoms are common in the general population; while only a minority of such individuals will have symptoms due to immunologic reactions to foods, gastrointestinal food allergies do exist in both children and adults. These immune reactions are mediated by immunoglobulin E-dependent and -independent mechanisms involving mast cells, eosinophils, and other immune cells, but the complexity of the underlying mechanisms of pathogenesis have yet to be fully defined. Knowledge of the spectrum of adverse reactions to foods that affect the digestive system, including gastrointestinal food allergy, is essential to correctly diagnose and manage the subset of patients with immunologically mediated adverse reactions to foods. Potentially fatal reactions to food necessitate careful instruction and monitoring on the part of health care workers involved in the care of individuals at risk of anaphylaxis. New methods of diagnosis and novel strategies for treatment, including immunologic modulation and the development of hypoallergenic foods, are exciting developments in the field of food allergy.

IFN-gamma determines distinct clinical outcomes in autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the CNS initiated by autoreactive CD4(+) T cells. EAE classically presents with a progressive ascending paralysis and is a model of multiple sclerosis that recapitulates some aspects of the disease. In this report we describe a mouse strain that spontaneously develops a severe, nonclassical form of EAE with 100% incidence. The distinct clinical phenotype is marked initially by a slight head tilt, progressing to a severe head tilt, spinning, or a rotatory motion. Classical EAE spontaneously occurs in myelin basic protein (MBP)-specific TCR transgenic RAG-1(-/-) mice (referred to as T/R(-)), whereas nonclassical EAE spontaneously occurs in T/R(-) IFN-gamma(-/-) mice (T/R(-)gamma(-)). Thus, the TCR recognizes the same Ag (MBP) and uses identical TCR in both cases. The cellular infiltrate in nonclassical EAE is predominantly found in the brainstem and cerebellum, with very little inflammation in the spinal cord, which is primarily affected in classical disease. Importantly, depending on the genetic makeup and priming conditions of the MBP-specific T cells, nonclassical disease can occur in the presence of an inflammatory infiltrate with eosinophilic, neutrophilic, or monocytic characteristics. Finally, we believe that nonclassical spontaneous EAE could be a useful model for the study of some characteristics of multiple sclerosis not observed in classical EAE, such as the inflammatory responses in the brainstem and cerebellum that can cause vertigo.