Biology of IL-5 in health and disease

Dose-response effects of multiple Ascaris suum exposures and their impact on lung protection during larval ascariasis

BACKGROUND

Human ascariasis is the most prevalent geohelminthiasis worldwide, affecting approximately 446 million individuals. In regions with endemic prevalence, the majority of infected adults are frequently exposed to the parasite and tend to have a low parasite load. Further studies are necessary to provide more evidence on the dynamics of infection and to elucidate the possible mechanisms involved in regulating protection, especially during the acute phase, also known as larval ascariasis. The aim of this study is to compare the impact of lung function between single and multiple infections in a murine model.

METHODS

We infected BALB/c mice considering the frequency of exposures: single-exposure-SI; twice-exposures-RE 2x and thrice-exposures-RE 3x, and considering the doses of infection: 25 eggs-RE 25; 250 eggs-RE 250 and 2,500 eggs-RE 2500, followed by infection challenge with 2,500 eggs. From this, we evaluated: parasite burden in lungs, cellular and humoral response, histopathological and physiological alterations in lungs.

RESULTS

The main results showed a reduction of parasite burden in the reinfected groups compared to the single-infected group, with protection increasing with higher exposure and dose. Furthermore, the RE 250 group exhibited a decrease of parasite burden close to RE 2500, but with less tissue damage, displaying the most favorable prognosis among the reinfected groups.

CONCLUSION

Our research indicates a dose-dependent relationship between antibody production and the intensity of the immune response required to regulate the parasite burden.

Current and emerging biological therapies for Chronic rhinosinusitis with nasal polyps with type 2 inflammation

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP), especially CRSwNP with type 2 inflammation, remains the most difficult-to-treat subtype with high prevalence worldwide. The emergence of biologics has the potential to fulfill the unmet medical needs of patients with CRSwNP driven by type 2 inflammation.

AREAS COVERED

A current review of the literature was performed to overview current and emerging biological therapies in the treatment of CRSwNP.

EXPERT OPINION

In an era of precision medicine, biologics have been given expectations to provide customized therapies to patients with CRSwNP, particularly those with refractory CRSwNP. Large clinical trials and real-world experiences are both essential for the application of biologics. Moreover, to make biological therapy more tailored to patients, an in-depth understanding of the different mechanisms of biologics, further elucidating the relationship between biologics and conventional medical and surgical treatments, and identifying predictive biomarkers warrant thorough investigations.

A web server for predicting and scanning of IL-5 inducing peptides using alignment-free and alignment-based method

Interleukin-5 (IL-5) can act as an enticing therapeutic target due to its pivotal role in several eosinophil-mediated diseases. The aim of this study is to develop a model for predicting IL-5 inducing antigenic regions in a protein with high precision. All models in this study have been trained, tested and validated on experimentally validated 1907 IL-5 inducing and 7759 non-IL-5 inducing peptides obtained from IEDB. Our primary analysis indicates that IL-5 inducing peptides are dominated by certain residues like Ile, Asn, and Tyr. It was also observed that binders of a wide range of HLA alleles can induce IL-5. Initially, alignment-based methods have been developed using similarity and motif search. These alignment-based methods provide high precision but poor coverage. In order to overcome this limitation, we explore alignment-free methods which are mainly machine learning-based models. Firstly, models have been developed using binary profiles and eXtreme Gradient Boosting-based model achieved a maximum AUC of 0.59. Secondly, composition-based models have been developed and our dipeptide-based random forest model achieved a maximum AUC of 0.74. Thirdly, random forest model developed using selected 250 dipeptides and achieved AUC 0.75 and MCC 0.29 on validation dataset; best among alignment-free models. In order to improve the performance, we developed an ensemble or hybrid method that combined alignment-based and alignment-free methods. Our hybrid method achieved AUC 0.94 with MCC 0.60 on a validation/independent dataset. The best hybrid model developed in this study has been incorporated into the user-friendly web server and a standalone package named 'IL5pred' (https://webs.iiitd.edu.in/raghava/il5pred/).

Quantification of Cytokines in Lip Tissue from Infants Affected by Congenital Cleft Lip and Palate

Cleft lip and palate are amongst the most common congenital malformations worldwide presenting with variable manifestations. Previous research has been primarily focused on the genetical aspects of its complex and multifactorial etiology. In the present study, we investigated the role of cytokines as mediators of epithelial–mesenchymal crosstalk and local site inflammation in cleft affected infants. Lip material was obtained from 12 children aged before primary dentition who suffered from orofacial clefting. The quantification of 12 cytokines (Interleukin-2,4,5,6,10,12,13,17A, Tumor Necrosis Factor-α, Interferon-γ, Transforming Growth Factor beta-1 and Granulocyte-Colony Stimulating Factor) was done using ELISA. Nonparametric Spearman Rho was used to ascertain the correlation between the expression levels of different cytokines. A significantly strong positive correlation was found between IL-2 and IFN-γ coupled with an IL4/IFN-γ ratio favoring IFN-γ. These findings indicate a shift towards the preferential activation of the Th1 differentiation pathway. Further, a pathological reduction in TGFβ-1 levels was noted, which may contribute to mucosal damage. IL-6 was more highly correlated to IFN-γ and IL-12 indicating its potential proinflammatory role in cleft affected tissues. This preferential activation of Th1 cell differentiation and consistent expression of IL-2,6,13 and TNF-α in cleft patients may indicate certain underlying mechanisms for inflammation mediation at the site of clefting.

Host Immunity and Inflammation to Pulmonary Helminth Infections

Helminths, including nematodes, cestodes and trematodes, are complex parasitic organisms that infect at least one billion people globally living in extreme poverty. Helminthic infections are associated with severe morbidity particularly in young children who often harbor the highest burden of disease. While each helminth species completes a distinct life cycle within the host, several helminths incite significant lung disease. This impact on the lungs occurs either directly from larval migration and host immune activation or indirectly from a systemic inflammatory immune response. The impact of helminths on the pulmonary immune response involves a sophisticated orchestration and activation of the host innate and adaptive immune cells. The consequences of activating pulmonary host immune responses are variable with several helminthic infections leading to severe, pulmonary compromise while others providing immune tolerance and protection against the development of pulmonary diseases. Further delineation of the convoluted interface between helminth infection and the pulmonary host immune responses is critical to the development of novel therapeutics that are critically needed to prevent the significant global morbidity caused by these parasites.

The use of pharmacogenomics, epigenomics, and transcriptomics to improve childhood asthma management: Where do we stand?

Asthma is a complex multifactorial disease and it is the most common chronic disease in children. There is a high variability in response to asthma treatment, even in patients with good adherence to maintenance treatment, and a correct inhalation technique. Distinct underlying disease mechanisms in childhood asthma might be the reason of this heterogeneity. A deeper knowledge of the underlying molecular mechanisms of asthma has led to the recent development of advanced and mechanism-based treatments such as biologicals. However, biologicals are recommended only for patients with specific asthma phenotypes who remain uncontrolled despite high dosages of conventional asthma treatment. One of the main unmet needs in their application is lack of clinically available biomarkers to individualize pediatric asthma management and guide treatment. Pharmacogenomics, epigenomics, and transcriptomics are three omics fields that are rapidly advancing and can provide tools to identify novel asthma mechanisms and biomarkers to guide treatment. Pharmacogenomics focuses on variants in the DNA, epigenomics studies heritable changes that do not involve changes in the DNA sequence but lead to alteration of gene expression, and transcriptomics investigates gene expression by studying the complete set of mRNA transcripts in a cell or a population of cells. Advances in high-throughput technologies and statistical tools together with well-phenotyped patient inclusion and collaborations between different centers will expand our knowledge of underlying molecular mechanisms involved in disease onset and progress. Furthermore, it could help to select and stratify appropriate therapeutic strategies for subgroups of patients and hopefully bring precision medicine to daily practice.

Beware the "red herring"

A young patient with relapsed diffuse large B-cell lymphoma presented with new onset respiratory symptoms and hypereosinophilia in the early stage post high-dose therapy/autologous stem cell rescue. Here, we present a step-wise practical approach to this unexpected laboratory finding for a not uncommon infective complication in the immunosuppressed patient.

The Immunomodulatory Role of Adjuvants in Vaccines Formulated with the Recombinant Antigens Ov-103 and Ov-RAL-2 against Onchocerca volvulus in Mice

BACKGROUND

In some regions in Africa, elimination of onchocerciasis may be possible with mass drug administration, although there is concern based on several factors that onchocerciasis cannot be eliminated solely through this approach. A vaccine against Onchocerca volvulus would provide a critical tool for the ultimate elimination of this infection. Previous studies have demonstrated that immunization of mice with Ov-103 and Ov-RAL-2, when formulated with alum, induced protective immunity. It was hypothesized that the levels of protective immunity induced with the two recombinant antigens formulated with alum would be improved by formulation with other adjuvants known to enhance different types of antigen-specific immune responses.

METHODOLOGY/ PRINCIPAL FINDINGS

Immunizing mice with Ov-103 and Ov-RAL-2 in conjunction with alum, Advax 2 and MF59 induced significant levels of larval killing and host protection. The immune response was biased towards Th2 with all three of the adjuvants, with IgG1 the dominant antibody. Improved larval killing and host protection was observed in mice immunized with co-administered Ov-103 and Ov-RAL-2 in conjunction with each of the three adjuvants as compared to single immunizations. Antigen-specific antibody titers were significantly increased in mice immunized concurrently with the two antigens. Based on chemokine levels, it appears that neutrophils and eosinophils participate in the protective immune response induced by Ov-103, and macrophages and neutrophils participate in immunity induced by Ov-RAL-2.

CONCLUSIONS/SIGNIFICANCE

The mechanism of protective immunity induced by Ov-103 and Ov-RAL-2, with the adjuvants alum, Advax 2 and MF59, appears to be multifactorial with roles for cytokines, chemokines, antibody and specific effector cells. The vaccines developed in this study have the potential of reducing the morbidity associated with onchocerciasis in humans.

Genome-wide expression profiles identify potential targets for gene-environment interactions in asthma severity

BACKGROUND

Gene-environment interaction studies using genome-wide association study data are often underpowered after adjustment for multiple comparisons. Differential gene expression in response to the exposure of interest can capture the most biologically relevant genes at the genome-wide level.

OBJECTIVE

We used differential genome-wide expression profiles from the Epidemiology of Home Allergens and Asthma birth cohort in response to Der f 1 allergen (sensitized vs nonsensitized) to inform a gene-environment study of dust mite exposure and asthma severity.

METHODS

Polymorphisms in differentially expressed genes were identified in genome-wide association study data from the Childhood Asthma Management Program, a clinical trial in childhood asthmatic patients. Home dust mite allergen levels (<10 or ≥10 μg/g dust) were assessed at baseline, and (≥1) severe asthma exacerbation (emergency department visit or hospitalization for asthma in the first trial year) served as the disease severity outcome. The Genetics of Asthma in Costa Rica Study and a Puerto Rico/Connecticut asthma cohort were used for replication.

RESULTS

IL9, IL5, and proteoglycan 2 expression (PRG2) was upregulated in Der f 1-stimulated PBMCs from dust mite-sensitized patients (adjusted P < .04). IL9 polymorphisms (rs11741137, rs2069885, and rs1859430) showed evidence for interaction with dust mite in the Childhood Asthma Management Program (P = .02 to .03), with replication in the Genetics of Asthma in Costa Rica Study (P = .04). Subjects with the dominant genotype for these IL9 polymorphisms were more likely to report a severe asthma exacerbation if exposed to increased dust mite levels.

CONCLUSIONS

Genome-wide differential gene expression in response to dust mite allergen identified IL9, a biologically plausible gene target that might interact with environmental dust mite to increase severe asthma exacerbations in children.

Update on reslizumab for eosinophilic asthma

INTRODUCTION

Patients with severe eosinophilic asthma have an unmet need for novel and efficacious treatments. Reslizumab is one of the three monoclonal antibodies targeting the IL-5 pathway and has been found in Phase IIIb clinical trials to reduce asthma exacerbations, control asthma-related symptoms and improve pulmonary function in patients with eosinophilic asthma.

AREAS COVERED

In this article, we discuss the results of asthma clinical trials using reslizumab, beginning with a discussion of the relationship between eosinophils, IL-5 and asthma. We conducted PubMed searches using the terms 'reslizumab', 'anti-IL-5', 'eosinophilic asthma', 'IL-5 asthma'. We also searched ClinicalTrials.gov for 'reslizumab', 'reslizumab asthma', 'SCH 55700', 'SCH 55700 asthma', 'Cinquil' and 'Cinquil asthma'.

EXPERT OPINION

Reslizumab and other anti-IL-5 therapies have seen success in recent trials through more stringent study participant selection targeting eosinophilic inflammation. This selection can now be based on simple blood counts. These drugs have shown a very good safety profile, but long-term safety data are not yet available. Approval for these drugs is eagerly awaited by clinicians and patients alike.

Systemic delivery of alpha-asarone with Kolliphor HS 15 improves its safety and therapeutic effect on asthma

The commercially available alpha-asarone injections (CA-ARE) were frequently found to cause severe anaphylactic reactions by the solubilizer contained in the formulation such as polysorbate 80 and propylene glycol. This study aimed to develop a new ARE injection using Kolliphor HS 15 as solubilizing agent (HS 15-ARE) by the dissolution method to resolve its poor solubility problem and reduce the anaphylaxis of CA-AREs caused by Polysorbate 80. The HS 15-ARE micelle showed a homogeneous round shape with the mean particle size of around 13.73 ± 0.02 nm, polydisperse index (PDI) of 0.19 ± 0.01 and solubilizing efficiency of 95.7% ± 2.4%. In vitro and in vivo studies showed that HS 15-ARE is a stable injection presenting the same pharmacokinetic profile with CA-ARE. Moreover, improved therapeutic effect was observed for HS 15-ARE in treating asthma compared to CA-ARE (p < 0.05) with no anaphylactic reactions observed. These results demonstrate that the new formulation of ARE (HS 15-ARE) has a great potential for replacing CA-AREs injections.

Innate and adaptive immunity to the nematode Strongyloides stercoralis in a mouse model

Mice have been used to the study the mechanisms of protective innate and adaptive immunity to larval Strongyloides stercoralis. During primary infection, neutrophils and eosinophils are attracted by parasite components and kill the larvae by release of granule products. Eosinophils also function as antigen-presenting cells for the induction of a Th2 response. B cells produce both IgM and IgG that collaborate with neutrophils to kill worms in the adaptive immune response. Vaccine studies have identified a recombinant diagnostic antigen that induced high levels of immunity to infection with S. stercoralis in mice. These studies demonstrate that there are redundancies in the mechanisms used by the immune response to kill the parasite and that a vaccine with a single antigen may be suitable as a prophylactic vaccine to prevent human strongyloidiasis.

Update on strongyloidiasis in the immunocompromised host

Immunocompromised persons are the most vulnerable population at risk for developing life-threatening clinical syndromes associated with strongyloidiasis, such as hyperinfection syndrome (HS) or dissemination. This review focuses on describing Strongyloides infection in the immunocompromised host, including immune response against this infection, analyzing the cases with HS published during the past 4 years in the United States, and describing the most sensitive diagnostic tools and the most effective treatment for each clinical syndrome. Strongyloidiasis is becoming an important parasitic disease in the United States, especially in the immunocompromised immigrant population. Because the transplant population is particularly at risk for developing HS, both recipients and donors should be screened for Strongyloides. Clinicians should also be aware that the development of HS can follow unexpectedly a few days after appropriate anthelminthic therapy. Highly sensitive screening tests are still not available in the major tertiary medical centers. Parenteral ivermectin has been used in some severe cases. Further therapy developments and improving diagnostic tools are warranted.

Roles of integrin activation in eosinophil function and the eosinophilic inflammation of asthma

Eosinophilic inflammation is a characteristic feature of asthma. Integrins are highly versatile cellular receptors that regulate extravasation of eosinophils from the postcapillary segment of the bronchial circulation to the airway wall and airspace. Such movement into the asthmatic lung is described as a sequential, multistep paradigm, whereby integrins on circulating eosinophils become activated, eosinophils tether in flow and roll on bronchial endothelial cells, integrins on rolling eosinophils become further activated as a result of exposure to cytokines, eosinophils arrest firmly to adhesive ligands on activated endothelium, and eosinophils transmigrate to the airway in response to chemoattractants. Eosinophils express seven integrin heterodimeric adhesion molecules: alpha 4 beta 1 (CD49d/29), alpha 6 beta 1 (CD49f/29), alpha M beta 2 (CD11b/18), alpha L beta 2 (CD11a/18), alpha X beta 2 (CD11c/18), alpha D beta2 (CD11d/18), and alpha 4 beta 7 (CD49d/beta 7). The role of these integrins in eosinophil recruitment has been elucidated by major advances in the understanding of integrin structure, integrin function, and modulators of integrins. Such findings have been facilitated by cellular experiments of eosinophils in vitro, studies of allergic asthma in humans and animal models in vivo, and crystal structures of integrins. Here, we elaborate on how integrins cooperate to mediate eosinophil movement to the asthmatic airway. Antagonists that target integrins represent potentially promising therapies in the treatment of asthma.

Stem cell factor-mediated activation pathways promote murine eosinophil CCL6 production and survival

Eosinophil activation during allergic diseases has a detrimental role in the generation of pathophysiologic responses. Stem cell factor (SCF) has recently shown an inflammatory, gene-activating role on eosinophils and contributes to the generation of pathophysiologic changes in the airways during allergic responses. The data in the present study outline the signal transduction events that are induced by SCF in eosinophils and further demonstrate that MEK-mediated signaling pathways are crucial for SCF-induced CCL6 chemokine activation and eosinophil survival. SCF-mediated eosinophil activation was demonstrated to include PI-3K activation as well as MEK/MAPK phosphorylation pathways. Subsequent analysis of CCL6 gene activation and production induced by SCF in the presence or absence of rather specific inhibitors for certain pathways demonstrated that the MEK/MAPK pathway but not the PI-3K pathway was crucial for the SCF-induced CCL6 gene activation. These same signaling pathways were shown to initiate antiapoptotic events and promote eosinophil survival, including up-regulation of BCL2 and BCL3. Altogether, SCF appears to be a potent eosinophil activation and survival factor.

A T2 cytokine environment may not limit T1 responses in human immunodeficiency virus patients with a favourable response to antiretroviral therapy

Low-level production of interferon-gamma (IFN-gamma) marks human immunodeficiency virus (HIV)-induced immunodeficiency and has been ascribed to a bias towards T2 cytokines. This was investigated in two cross-sectional studies of HIV patients who were immunodeficient when they began antiretroviral therapy (ART) and had stable increases in CD4 T-cell counts. Blood leucocytes were assessed unstimulated or after stimulation with cytomegalovirus (CMV), anti-CD3 or mitogen. IFN-gamma and interleukin (IL)-5 responses were initially assessed by enzyme-linked immunosorbent spot-forming cell assay (ELISPOT) and enzyme-linked immunosorbent assay (ELISA). We then adopted a sensitive reverse transcription-polymerase chain reaction (RT-PCR) system to assess IFN-gamma, IL-5, IL-4 and IL-4delta2 (an inhibitory splice variant of IL-4) mRNA. The results were correlated with putative serological markers of a T1 [lymphocyte activation gene-3 (LAG-3), CD26] or a T2 [CD30, immunoglobulin E (IgE)] cytokine environment. IL-5 production and IgE levels were elevated in patients. IgE levels did not correlate with IFN-gamma, but showed an inverse correlation with IL-5 released in culture (P = 0.05). The levels of IL-4, IFN-gamma, IL-5 and IL-4delta2 mRNA were correlated after anti-CD3 stimulation, where IL-5 was the best predictor of IFN-gamma mRNA (P = 0.006). Weak positive correlations were evident between CD30 and cytokine mRNA levels, whilst IgE correlated inversely with IL-4, IL-4delta2, IL-5 and IFN-gamma mRNA levels. These analyses provide no evidence for an inverse relationship between T1 and T2 cytokine responses in HIV patients, but suggest that the elevation of IgE marks low cytokine responses.

Differential engagement of modules 1 and 4 of vascular cell adhesion molecule-1 (CD106) by integrins alpha4beta1 (CD49d/29) and alphaMbeta2 (CD11b/18) of eosinophils

We have studied adhesion of eosinophils to various forms of vascular cell adhesion molecule 1 (VCAM-1, CD106), an integrin counter-receptor implicated in eosinophil recruitment to the airway in asthma. Full-length 7d-VCAM-1, with seven immunoglobulin-like modules, contains integrin-binding sites in modules 1 and 4. The alternatively spliced six-module protein, 6d-VCAM-1, lacks module 4. In static assays, unactivated purified human blood eosinophils adhered similarly to recombinant soluble human 6d-VCAM-1 and 7d-VCAM-1 coated onto polystyrene microtiter wells. Further experiments, however, revealed differences in recognition of modules 1 and 4. Antibody blocking indicated that eosinophil adhesion to 6d-VCAM-1 or a VCAM-1 construct containing only modules 1-3, 1-3VCAM-1, is mediated by alpha4beta1 (CD49d/29), whereas adhesion to a construct containing modules 4-7, 4-7VCAM-1, is mediated by bothalpha4beta1 andalphaMbeta2 (CD11b/18). Inhibitors of phosphoinositide 3-kinase, which block adhesion of eosinophils mediated by alphaMbeta2, blocked adhesion to 4-7VCAM-1 but had no effect on adhesion to 6d-VCAM-1. Consistent with the antibody and pharmacological blocking experiments, eosinophilic leukemic cell lines lacking alphaMbeta2 did not adhere to 4-7VCAM-1 but did adhere to 6d-VCAM-1 or 1-3VCAM-1. Activation of eosinophils by interleukin (IL)-5 enhanced static adhesion to 6d-VCAM-1, 7d-VCAM-1, or 4-7VCAM-1; IL-5-enhanced adhesion to all 3 constructs was blocked by anti-alphaMbeta2. Adhesion of unstimulated eosinophils to 7d-VCAM-1 under flow conditions was inhibited by anti-alpha4 or anti-alphaM. IL-5 treatment decreased eosinophil adhesion to 7d-VCAM-1 under flow, and anti-alphaM had the paradoxical effect of increasing adhesion. These results demonstrate that alphaMbeta2 modulatesalpha4beta1-mediated eosinophil adhesion to VCAM-1 under both static and flow conditions.

Emerging anti-inflammatory agents for allergic rhinitis

Allergic rhinitis (AR) is a high-prevalence disease, affecting 10-15% of the general population. AR is sustained by an IgE-mediated reaction, and by a complex inflammatory network of cells, mediators and cytokines that becomes chronic when exposure to allergen persists. A T helper 2 (TH2)-biased immune response is the basis for the allergic inflammation. The current therapeutic strategy is mainly based on drugs (antihistamines, nasal corticosteroids, cromones, decongestants) and allergen immunotherapy. Drugs are overall effective in controlling symptoms, but do not modify the immune background that leads to allergic inflammation, and safety concerns may be present especially for prolonged treatments. Immunotherapy can modify the allergic response, but there is still space for improvement. Nowadays, several approaches are under investigation to optimise the management of AR. On one hand, new drugs and antimediators are being developed; on the other hand, attempts are made to selectively block relevant signal pathways of allergic reaction. Finally, one of the major goals is to modify the TH2-biased immune response by improving the characteristics and modes of action of allergen immunotherapy.

Serum interleukin-5 measurements for monitoring acute asthma in children

Cytokine-mediated interactions among the inflammatory cells may play a role in the pathogenesis of bronchial asthma. Interleukin-5 (IL-5) is a major cytokine in the recruitment of neutrophils to the area of inflammation. Serum IL-5 is a marker of disease activity and treatment efficacy in bronchial asthma. To understand the role of IL-5 in disease activity in acute asthma, changes in serum concentrations of IL-5 elaborated by activated eosinophil before and after prednisolone therapy with clinical improvement were determined in the present study. Circulating levels of IL-5 in 16 normal control subjects and in sera from 22 allergic asthmatic children with acute exacerbation and in stable condition were determined by using commercially available assay kits. The mean concentration of serum IL-5 was higher in patients with acute exacerbation (6.30 +/- 2.21 pg/mL) and in stable asthmatics (5.55 +/- 2.23 pg/mL) compared to control group subjects (4.81 +/- 0.54 pg/mL; p > 0.05). However, the difference was not statistically significant between the acute exacerbation and stable asthmatics groups (p > 0.05). Serum IL-5 is a poor indicator of disease activity in acute asthma; therefore, monitoring serum IL-5 concentration is of limited value. The clinical value of serum IL-5 as a marker of disease activity remains to be established.

Inhibitory effect of heparin-derived oligosaccharides on secretion of interleukin-4 and interleukin-5 from human peripheral blood T lymphocytes

AIM: To investigate the inhibitory effect of heparin-derived oligosaccharides (Oligs) on secretion of interleukin-4 (IL-4) and interleukin-5 (IL-5) from human peripheral blood T lymphocytes (PBTLs).

METHODS: Oligs were prepared by three different heparin depolymerization methods and separated by gel filtration chromatography. PBTLs from ten adult patients with allergic eosinophilic gastroenteritis were treated with phytahematoagglutinin (PHA) and Oligs. The supernatants from the cell culture of PBTLs were harvested and subjected to the determination of IL-4 and IL-5 contents by ELISA method.

RESULTS: At the concentration of 5 μg/mL, Oligs with different M_r had different effects on the secretion of IL-4 and IL-5. The tetrasaccharide with M_r of 1142, produced by depolymerizing heparin with hydrogen peroxide, had the strongest inhibitory effect on the secretion of IL-4. It decreased the IL-4 content from 375.6 ± 39.2 ng/L (PHA group) to 12.5 ± 5.7 ng/L (P < 0.01). The hexasaccharide with M_r of 1806, produced by depolymerizing heparin with β -elimination method, had the strongest inhibitory effect on the secretion of IL-5. It decreased the IL-5 content from 289.2 ± 33.4 ng/L (PHA group) to 22.0 ± 5.2 ng/L (P < 0.01).

CONCLUSION: The inhibitory activity of Oligs on the secretion of IL-4 and IL-5 from human PBTLs closely depends on their molecular structure, and there may be an essential structure to act as an inhibitor. The most effective inhibitors of IL-4 and IL-5 secretion are tetrasaccharides and hexasaccharides, respectively.

Mastocitoma cutâneo canino: estudo de 45 casos

Quarenta e cinco mastocitomas cutâneos caninos foram graduados histologicamente com o uso de hematoxilina-eosina. Foram empregados os métodos azul de toluidina e região organizadora nucleolar argirofílica (AgNOR) para, respectivamente, evidenciar os grânulos citoplasmáticos e avaliar o índice de proliferação celular. Diversas características histológicas foram observadas, como distribuição das células na pele, tamanho, forma, aspecto de citoplasma e núcleo, quantidade de estroma, presença de eosinófilos e alterações associadas. Com base nessas caracteríscas, 37,8% dos mastocitomas foram classificados como grau I, 51,1% como grau II e 11,1% como grau III. A média geral de AgNOR nos mastocitomas foi de 1,9 (1,2 a 4,3) e as médias para os graus I, II e III foram, respectivamente, de 1,5, 1,85 e 3,25. A técnica de AgNOR mostrou ser de fácil execução, custo acessível e confiável como meio auxiliar para estimar um prognóstico mais objetivo para os mastocitomas.

Crucial role of IL-4/STAT6 in T cell-mediated hepatitis: up-regulating eotaxins and IL-5 and recruiting leukocytes

T cell-mediated immune responses are implicated in the pathogenesis of a variety of liver disorders; however, the underlying mechanism remains obscure. Con A injection is a widely accepted mouse model to study T cell-mediated liver injury, in which STAT6 is rapidly activated. Disruption of the IL-4 and STAT6 gene by way of genetic knockout abolishes Con A-mediated liver injury without affecting IFN-gamma/STAT1, IL-6/STAT3, or TNF-alpha/NF-kappaB signaling or affecting NKT cell activation. Infiltration of neutrophils and eosinophils in Con A-induced hepatitis is markedly suppressed in IL-4 (-/-) and STAT6(-/-) mice compared with wild-type mice. IL-4 treatment induces expression of eotaxins in hepatocytes and sinusoidal endothelial cells isolated from wild-type mice but not from STAT6(-/-) mice. Con A injection induces expression of eotaxins in the liver and elevates serum levels of IL-5 and eotaxins; such induction is markedly attenuated in IL-4(-/-) and STAT6(-/-) mice. Finally, eotaxin blockade attenuates Con A-induced liver injury and leukocyte infiltration. Taken together, these findings suggest that IL-4/STAT6 plays a critical role in Con A-induced hepatitis, via enhancing expression of eotaxins in hepatocytes and sinusoidal endothelial cells, and induces IL-5 expression, thereby facilitating recruitment of eosinophils and neutrophils into the liver and resulting in hepatitis.

Effect of cocoa flavanols and their related oligomers on the secretion of interleukin-5 in peripheral blood mononuclear cells

We previously showed that flavanols and their related oligomers (FLO) isolated from cocoa can have immunomodulatory effects on production of the cytokines interleukin-1beta (IL-1beta), IL-2, and IL-4. In the present study, we examined whether selected FLO fractions isolated from cocoa (monomer through decamer) modulate IL-5 protein secretion from resting and phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC). Although FLO fractions were unstimulatory for IL-5 secretion in resting cells, PHA-induced IL-5 release from PBMC was markedly affected by certain FLO fractions. The monomeric and small oligomeric (dimer and trimer) fractions enhanced PHA stimulation by 50%, 54%, and 43%, respectively. In contrast, the larger oligomeric fractions (hexamer through decamer) inhibited IL-5 release in the range of 18% to 39%; the tetramer and pentamer showed intermediate effects. The increment in IL-5 suggests that FLO may preferentially stimulate immunoglobulin A. We suggest that in the oral cavity this could result in reduction in the risk for dental caries and periodontal disease. This work offers additional data for consideration of the health benefits of dietary FLO from a variety of foods, including those benefits associated specifically with consumption of some cocoas and chocolates.

Decreased expression of membrane IL-5 receptor alpha on human eosinophils: II. IL-5 down-modulates its receptor via a proteinase-mediated process

In the accompanying study, we demonstrated that following Ag challenge, membrane (m)IL-5Ralpha expression is attenuated on bronchoalveolar lavage eosinophils, soluble (s)IL-5Ralpha is detectable in BAL fluid in the absence of increased steady state levels of sIL-5Ralpha mRNA, and BAL eosinophils become refractory to IL-5 for ex vivo degranulation. We hypothesized that IL-5 regulates its receptor through proteolytic release of mIL-5Ralpha, which in turn contributes to the presence of sIL-5Ralpha. Purified human peripheral blood eosinophils were incubated with IL-5 under various conditions and in the presence of different pharmacological agents. A dose-dependent decrease in mIL-5Ralpha was accompanied by an increase in sIL-5Ralpha in the supernatant. IL-5 had no ligand-specific effect on mIL-5Ralpha or sIL-5Ralpha mRNA levels. The matrix metalloproteinase-specific inhibitors BB-94 and GM6001 and tissue inhibitor of metalloproteinase-3 partially inhibited IL-5-mediated loss of mIL-5Ralpha, suggesting that sIL-5Ralpha may be produced by proteolytic cleavage of mIL-5Ralpha. IL-5 transiently reduced surface expression of beta-chain, but had no effect on the expression of GM-CSFRalpha. Pretreatment of eosinophils with a dose of IL-5 that down-modulated mIL-5Ralpha rendered these cells unable to degranulate in response to further IL-5 stimulation, but they were fully responsive to GM-CSF. These findings suggest that IL-5-activated eosinophils may lose mIL-5Ralpha and release sIL-5Ralpha in vivo, which may limit IL-5-dependent inflammatory events in diseases such as asthma.

Acute eosinophilic pneumonia in AIDS

A 39-year-old man with AIDS presented with acute respiratory distress and diffuse bilateral infiltrates seen on a chest radiograph. Acute eosinophilic pneumonia (AEP) was diagnosed by thoracoscopic lung biopsy. There was no evidence of an infectious etiology, and the patient rapidly improved with corticosteroid therapy. Several of the idiopathic interstitial pneumonias have been reported in adult patients with AIDS. To our knowledge, this case represents the first tissue-confirmed case of AEP associated with adult AIDS.

Preclinical efficacy and safety of mepolizumab (SB-240563), a humanized monoclonal antibody to IL-5, in cynomolgus monkeys

BACKGROUND

Allergic respiratory diseases are characterized by large numbers of eosinophils and their reactive products in airways and blood; these are believed to be involved in progressive airway damage and remodeling. IL-5 is the principal cytokine for eosinophil maturation, differentiation, and survival. Mepolizumab (SB-240563), a humanized monoclonal antibody (mAb) specific for human IL-5, is currently in clinical trials for treatment of asthma.

OBJECTIVE

The purpose of this study was to characterize the pharmacologic activity and long-term safety profile of an anti--human IL-5 mAb to support clinical trials in asthmatic patients.

METHODS

Naive and Ascaris suum -sensitive cynomolgus monkeys received various dose levels of mepolizumab and were monitored for acute and chronic pharmacologic and toxic responses.

RESULTS

To support preclinical safety assessment, cynomolgus monkey IL-5 was cloned, expressed, and characterized. Although monkey IL-5 differs from human IL-5 by 2 amino acids (Ala27Gly and Asn40His), mepolizumab has comparable inhibitory activity against both monkey IL-5 and human IL-5. In A suum--sensitive monkeys, single doses of mepolizumab significantly reduced blood eosinophilia, eosinophil migration into lung airways, and levels of RANTES and IL-6 in lungs for 6 weeks. However, mepolizumab did not affect acute bronchoconstrictive responses to inhaled A suum. In an IL-2--induced eosinophilia model (up to 50% blood eosinophilia), 0.5 mg/kg mepolizumab blocked eosinophilia by >80%. Single-dose and chronic (6 monthly doses) intravenous and subcutaneous toxicity studies in naive monkeys found no target organ toxicity or immunotoxicity up to 300 mg/kg. Monkeys did not generate anti-human IgG antibodies. Monthly mepolizumab doses greater than 5 mg/kg caused an 80% to 100% decrease in blood and bronchoalveolar lavage eosinophils lasting 2 months after dosing, and there was no effect on eosinophil precursors in bone marrow after 6 months of treatment. Eosinophil decreases correlated with mepolizumab plasma concentrations (half-life = 13 days).

CONCLUSION

These studies demonstrate that chronic antagonism of IL-5 by mepolizumab in monkeys is safe and has the potential, through long-term reductions in circulating and tissue-resident eosinophils, to be beneficial therapy for chronic inflammatory respiratory diseases.

Therapeutic relevance of altered cytokine expression

Cytokines and their receptors have numerous physiological functions. Altered concentrations of these mediators are associated with various afflictions. For example, over-expression of cytokines has been associated with altered drug concentrations and activity. Greater concentrations of cardiovascular drugs have been observed in humans and laboratory animals with various types of inflammatory disorders compared to healthy controls. Interestingly, the observed higher concentrations of drugs such as propranolol and verapamil have not been associated with increased effects. Indeed, reduced response to these cardiovascular drugs is observed, suggestive of cytokine-mediated downregulation of receptors. Increased cytokine concentrations have also been associated with decreased response to drugs used in treatment of other disorders such as AIDS, asthma and psychiatric diseases. This reduced response to drug in the presence of altered cytokine concentrations is especially relevant to the elderly population which has a greater incidence of multiple diseases and elevated concentrations of various cytokines compared to younger individuals. Furthermore, inflammatory conditions and their accompanied increased over-expression of cytokines are suggested to be the main determinants of therapeutic failure in myocardial infarction and angina. Therefore, altered cytokine concentrations may influence therapeutic outcomes of pharmacotherapy and result in treatment failure.

Role of IL-5 in innate and adaptive immunity to larval Strongyloides stercoralis in mice

Protective immunity to Strongyloides stercoralis infective larvae in mice has been shown to be dependent on IL-5 based on mAb depletion studies. The goal of this study was to determine the functional role of IL-5 during the innate and adaptive immune response to larval S. stercoralis in mice. In these studies, three strains of mice were used: wild-type C57BL/6J (WT), IL-5 knockout (KO), and IL-5 transgenic (TG). Innate responses to the larvae indicated that there was enhanced survival in the KO animals and decreased survival in the TG animals compared with WT. Furthermore, killing of larvae in TG mice was associated with eosinophil infiltration and degranulation. In studying the adaptive immune response, it was observed that immunization of KO mice did not lead to the development of protective immunity. Experiments were then performed to determine whether KO mice reconstituted with Abs or cells could then develop protective immunity. KO mice displayed protective immunity via a granulocyte-dependent mechanism following injection of purified IgM from immune wild-type animals. Immunity in KO mice could also be reconstituted by the injection of eosinophils at the time of immunization. These eosinophils did not participate in actively killing the challenge infection, but rather were responsible for the induction of a protective Ab response. We conclude that IL-5 is required in the protective immune response for the production of eosinophils, and that eosinophils were involved in larval killing during innate immunity and in the induction of protective Abs in the adaptive immune response.

Asthma: where beyond steroids?

The prevalence of asthma is increasing dramatically despite major changes in monitoring and treatment of this disease. Currently available bronchodilators and anti-inflammatory drugs are effective in most patients, although these can have side effects and are mainly symptomatic. Many drugs are now in development for the treatment of asthma. Most of these new therapies are aimed at inhibition of the inflammatory components, with better safety profiles than steroids.

Advances in immunopharmacology of asthma

Asthma is a chronic inflammatory disease characterized by airway hyperresponsiveness and recurrent reversible airway obstruction. As there appears to be a preponderance of T-helper 2 (Th2) cells over Th1 cells in asthma, more attention has been focused on the role of Th2-derived cytokines such as interleukin (IL)-4 and IL-5 and their corresponding signaling pathways in the pathophysiology of the disease. These complex pathways may involve the activation of signal transducers and activators of transcription (STATs) and nuclear factor-kappaB (NF-kappaB). On the other hand, immunoglobulin (Ig) E-mediated mechanisms and the protein tyrosine kinase signaling cascade are important in triggering the release of mediators from inflammatory cells. In spite of all of these, host regulatory mechanisms exist to limit the inflammation. An increase in the 3', 5'-cyclic adenosine monophosphate (cAMP) level generally suppresses the activities of immune and inflammatory cells, and the level of cAMP is closely regulated by a family of phosphodiesterases (PDEs). Heparin, a glycosaminoglycan released exclusively from mast cells, also is believed to possess anti-inflammatory actions. Many new therapeutic agents have been developed either to attenuate the pro-inflammatory processes in asthma or to augment the host anti-inflammatory mechanisms. In this article, we discuss the immunopharmacology of several of these agents, which include heparin and inhibitors of PDEs, tyrosine kinases, and NF-kappaB, as well as antibodies and soluble receptors directed against IgE, IL-4, and IL-5.

ERK1 and ERK2 activation by chemotactic factors in human eosinophils is interleukin 5-dependent and contributes to leukotriene C(4) biosynthesis

Eosinophils, the major immune effector cells contributing to allergic inflammation and asthma, are profoundly affected by interleukin (IL) 5 with respect to their differentiation, viability, recruitment, and cytotoxic effector functions. IL-5 enhances eosinophil responsiveness to a variety of chemotactic factors via a process called priming, although the molecular mechanism is unknown. In this study, we report that, following IL-5 priming of eosinophils, chemotactic agents including fMet-Leu-Phe, IL-8, and RANTES, promote vigorous transient activation of ERK1 and ERK2. In contrast, these chemotactic factors stimulate weak or indiscernible ERK activation in unprimed eosinophils. Furthermore, this intracellular marker of priming is selective for IL-5-related cytokines, in that it is observed following exposure to IL-5 and granulocyte macrophage-colony stimulating factor but not to interferon-gamma, stem cell factor, tumor necrosis factor alpha, or IL-4. Interestingly, priming of chemoattractant-induced ERK activation is accompanied by an increase in association of tyrosine-phosphorylated proteins with the adapter protein Grb2. The biological relevance of ERK activation to IL-5 priming is supported by the observation that inhibition of ERK activity by treatment with the MEK inhibitors PD98059 or U0126 inhibited the release of leukotriene C(4) stimulated by fMet-Leu-Phe in IL-5-primed eosinophils. These data provide evidence for a previously undescribed fundamental mechanism by which stimulation of IL-5 family receptors induces a rapid phenotypic alteration in the signal transduction pathways of chemotactic receptors, enabling their activation of the ERK1 and ERK2 pathway and contributing to the capacity of these cells to synthesize LTC(4).