Toll-like receptor-induced expression of epithelial cytokine receptors on haemopoietic progenitors is altered in allergic asthma.

BACKGROUND: Haemopoietic progenitor cells (HPC) migrate to sites of allergic inflammation where, upon stimulation with epithelial cytokines, they produce Th2 cytokines and differentiate into mature eosinophils and basophils. They also express Toll-like receptors (TLR) involved in antimicrobial responses. OBJECTIVE: The objective of this study was to compare TLR expression on peripheral blood HPC and TLR-induced responses, in particular changes in epithelial cytokine receptors, in healthy and asthmatic subjects at baseline and following allergen challenge. METHODS: Ten healthy and 11 allergic asthmatic subjects were studied. HPC-enriched cell populations were stimulated with TLR-2, TLR-4 or TLR-9 ligands. TLR expression by circulating HPC and interleukin (IL)-25 (IL-17RB), IL-33 (ST2) and thymic stromal lymphopoietin receptor (TSLPR) expression after TLR ligation were examined by flow cytometry at baseline and, in asthmatics, following allergen challenge. The effects of dexamethasone (Dex) on TLR-induced responses were also assessed. RESULTS: Asthmatics had significantly lower circulating HPC expressing TLR-2 and TLR-9 with a similar trend for TLR-4. TLR-4 stimulation of HPC yielded higher numbers of TSLPR+ cells in asthmatics compared with healthy subjects. A similar trend was seen for TLR-9 ligation, an effect further augmented by allergen inhalation. Allergen challenge also enhanced TLR-induced ST2 expression on HPC. Treatment with Dex in vitro increased TLR-4-induced TSLPR expression but had no effect on other epithelial cytokine receptors. CONCLUSIONS AND CLINICAL RELEVANCE: These data demonstrate an interaction between allergen and TLR ligand exposure in asthmatics. Allergen inhalation augments the TLR-induced inflammatory response by HPC, possibly leading to increased "in situ haemopoiesis" through up-regulation of TSLPR. These findings show that HPC may be a part of the pro-inflammatory cascade in pathogen-induced asthma exacerbation through their increased responsiveness to TLR stimulation.

Prenatal and early-life predictors of atopy and allergic disease in Canadian children: results of the Family Atherosclerosis Monitoring In earLY life (FAMILY) Study.

Prenatal and early-life environmental exposures play a key role in the development of atopy and allergic disease. The Family Atherosclerosis Monitoring In earLY life Study is a general, population-based Canadian birth cohort that prospectively evaluated prenatal and early-life traits and their association with atopy and/or allergic disease. The study population included 901 babies, 857 mothers and 530 fathers. Prenatal and postnatal risk factors were evaluated through questionnaires collected during the antenatal period and at 1 year. The end points of atopy and allergic diseases in infants were evaluated through questionnaires and skin prick testing. Key outcomes included atopy (24.5%), food allergy (17.5%), cow's milk allergy (4.8%), wheezing (18.6%) and eczema (16%). The association between infant antibiotic exposure [odds ratio (OR): 2.04, 95% confidence interval (CI): 1.45-2.88] and increased atopy was noted in the multivariate analysis, whereas prenatal maternal exposure to dogs (OR: 0.60, 95% CI: 0.42-0.84) and acetaminophen (OR: 0.68, 95% CI: 0.51-0.92) was associated with decreased atopy. This population-based birth cohort in Canada demonstrated high rates of atopy, food allergy, wheezing and eczema. Several previously reported and some novel prenatal and postnatal exposures were associated with atopy and allergic diseases at 1 year of age.

T regulatory cell phenotypes in peripheral blood and bronchoalveolar lavage from non-asthmatic and asthmatic subjects.

BACKGROUND: An unresolved issue in T regulatory cells' cell biology is the lack of consensus on phenotypic markers that accurately define the natural Treg (nTreg) population. OBJECTIVES: To examine nTreg frequency and functional capacity in healthy controls and their frequency in asthmatic subjects using three different phenotypic strategies. We hypothesized that phenotypically different nTreg are quantitatively and functionally different. METHODS: Thirty-four healthy, non-asthmatic and 17 asthmatic subjects were studied. Three nTreg phenotypes were defined as follows: nTreg1 (CD4(+) CD25(+) Foxp3(+) ), nTreg2 (CD4(+) CD25(+) CD127(low) Foxp3(+) ), and nTreg3 (CD4(+) CD25(high) Foxp3(+) ). The flow cytometric determination of nTreg frequency in peripheral blood (PB) and bronchoalveolar lavage (BAL) was performed using fluorescently labelled antibodies. Peripheral blood nTreg functional capacity was assessed using a CFSE-based suppression assay. RESULTS: There was a significantly lower frequency of PB nTreg3 compared to nTreg2 and nTreg1 (P < 0.05). Both nTreg2 and nTreg3 had a significantly greater suppressive capacity than nTreg1 at T responder (Tresp) to nTreg ratios of 16 : 1 up to 1 : 1 (P < 0.01). Asthmatics exhibited a significantly lower PB nTreg3 and nTreg1 frequency than healthy controls (P < 0.05). There were no differences between healthy controls and asthmatic subjects when comparing BAL nTreg frequency. CONCLUSIONS AND CLINICAL RELEVANCE: Phenotypically different nTreg subsets are quantitatively and functionally different and are variably observed in asthma. The CD4(+) CD25(high) Foxp3(+) phenotype was the least frequent, but demonstrated the greatest suppression, and was significantly lower in PB of asthmatic subjects. Consequently, it is imperative that nTreg phenotypes be clearly defined and that the interpretation of their frequency and function be phenotype specific.

In situ hematopoiesis: a regulator of TH2 cytokine-mediated immunity and inflammation at mucosal surfaces.

Hematopoiesis refers to the development of blood cells in the body through the differentiation of pluripotent stem cells. Although hematopoiesis is a multifocal process during embryonic development, under homeostatic conditions it occurs exclusively within the bone marrow. There, a limited number of hematopoietic stem cells differentiate into a rapidly proliferating population of lineage-restricted progenitors that serve to replenish circulating blood cells. However, emerging reports now suggest that under inflammatory conditions, alterations in hematopoiesis that occur outside of the bone marrow appear to constitute a conserved mechanism of innate immunity. Moreover, recent reports have identified previously unappreciated pathways that regulate the egress of hematopoietic progenitor cells from the bone marrow, alter their activation status, and skew their developmental potential. These studies suggest that progenitor cells contribute to inflammatory response by undergoing in situ hematopoiesis (ISH). In this review, we highlight the differences between homeostatic hematopoiesis, which occurs in the bone marrow, and ISH, which occurs at mucosal surfaces. Further, we highlight factors produced at local sites of inflammation that regulate hematopoietic progenitor cell responses and the development of TH2 cytokine-mediated inflammation. Finally, we discuss the therapeutic potential of targeting ISH in preventing the development of inflammation at mucosal sites.

The Canadian healthy infant longitudinal development birth cohort study: biological samples and biobanking.

BACKGROUND: It is hypothesised that complex interactions between genetic and environmental factors give rise to allergy and asthma in childhood. The Canadian Healthy Infant Longitudinal Development (CHILD) study was designed to explore these factors. METHODS: CHILD is a longitudinal, general population birth cohort study following infants from mid-pregnancy to age 5 years. Over this time period, biological samples, questionnaires, clinical measures and environmental data are collected. RESULTS: A total of 3624 families have been recruited, and many thousands of samples and questionnaires have been collected, annotated, and archived. This report outlines the rationale and methodology for collecting and storing diverse biological samples from parents and children in this study, and the mechanisms for their release for analyses. CONCLUSIONS: The CHILD sample and data repository is a tremendous current and future resource and will provide a wealth of information not only informing studies of asthma and allergy, but also potentially in many other aspects of health relevant for Canadian infants and children.

Thymic stromal lymphopoietin (TSLP) secretion from human nasal epithelium is a function of TSLP genotype.

Recent candidate gene and genome-wide association studies have identified "protective" associations between the single-nucleotide polymorphism (SNP) rs1837253 in the TSLP gene and risk for allergy, asthma, and airway hyperresponsiveness. The absence of linkage disequilibrium of rs1837253 with other SNPs in the region suggests it is likely a causal polymorphism for these associations, having functional consequences. We hypothesized that rs1837253 genotype would influence TSLP secretion from mucosal surfaces. We therefore evaluated the secretion of TSLP protein from primary nasal epithelial cells (NECs) of atopic and nonatopic individuals and its association with rs1837253 genotype. We found that although atopic sensitization does not affect the secretion of TSLP from NECs, there was decreased TSLP secretion in NECs obtained from heterozygous (CT; 1.8-fold) and homozygous minor allele (TT; 2.5-fold) individuals, as compared with NECs from homozygous major allele individuals (CC; P<0.05), after double-stranded RNA (dsRNA) stimulation (50 µg ml(-1)). Our novel results show that rs1837253 polymorphism may be directly involved in the regulation of TSLP secretion. This may help explain the protective association of this genetic variant with asthma and related traits. Identifying functional consequences of SNPs in genes with previously reported clinical associations is critical in understanding and targeting allergic inflammation.

Anti-cyclic citrullinated peptide antibody as a marker of erosive arthritis in patients with systemic lupus erythematosus: a systematic review and meta-analysis.

OBJECTIVE: Anti-cyclic citrullinated peptide (CCP) antibody is an established marker in the diagnosis and prognostication of rheumatoid arthritis (RA). Infrequently, systemic lupus erythematosus (SLE) patients also develop a deforming erosive arthritis, similar to that of RA. Our objective was to determine whether anti-CCP antibody is a useful marker of erosive disease in SLE patients presenting with arthritis. METHODS: Electronic databases EMBASE, MEDLINE and non-indexed MEDLINE citations were searched through April 11, 2014, using the outlined key terms. Studies meeting predefined inclusion and exclusion criteria were reviewed. Two reviewers independently assessed the quality of included articles using previously described criteria. The DerSimonian-Laird random effects model was used to calculate pooled sensitivity and specificity of anti-CCP antibody for erosive arthritis in SLE. RESULTS: Seven articles met inclusion and exclusion criteria. A total of 609 SLE patients with arthritis were identified, 70 of whom had erosive disease. Pooled sensitivity and specificity of anti-CCP antibody for erosive arthritis was 47.8% (95% CI, 26.2%-70.2%) and 91.8% (95% CI, 78.4%-97.2%), respectively. CONCLUSION: Our findings suggest that anti-CCP antibody is a highly specific marker for erosive arthritis in SLE. Longitudinal prospective studies are needed to determine if anti-CCP antibody can be used as a predictor of erosive disease.

T cell-mediated induction of thymic stromal lymphopoietin in differentiated human primary bronchial epithelial cells.

BACKGROUND: Inhaled peptide challenge has been shown to induce T cell-mediated, isolated late asthmatic reaction (LAR), characterized by recruitment of CD4(+) T cells and increased levels of thymus and activation-regulated chemokine (TARC; CCL17). Epithelial-derived thymic stromal lymphopoietin (TSLP) has been shown to modulate dendritic cell function to promote TH 2 responses via CCL17 production. OBJECTIVES: To elucidate the mechanisms involved in allergen-specific T cell-induced LAR and recruitment of CD4(+) T cells by examining the effects of T cell-derived factors on the induction of TSLP in primary bronchial epithelial cells (PBEC). METHODS: PBEC grown at air-liquid interface from healthy individuals and patients with asthma were stimulated with double-stranded RNA (dsRNA) or supernatants from activated allergen-specific T cells. TSLP was measured in PBEC culture supernatants. Neutralizing antibodies and signalling inhibitors were used to examine the mechanisms responsible for the induction of epithelial-derived TSLP. The functional activity of PBEC-derived TSLP was measured using a bioassay involving the induction of CCL17 production from monocyte-derived dendritic cells (moDC). RESULTS: Both dsRNA and allergen-specific T cells induced enhanced TSLP secretion from asthmatic PBEC compared to healthy PBEC. Activated PBEC culture supernatant induced TSLP-dependent CCL17 production from moDC in a manner related to clinical asthmatic status. IL-1ß, IL-6, and CXCL8, rather than TH 2 cytokines (IL-4/5/13), appeared to be the principle mediators of allergen-specific T cell-dependent induction of epithelial-derived TSLP, which was regulated by the MEK, MAPK, and NFκB pathways. CONCLUSION AND CLINICAL RELEVANCE: Our data reveal a novel effect of allergen-specific T cells as a positive regulator of TSLP production by epithelial cells, suggesting T cell-airway epithelium interactions that may lead to maintenance and amplification of allergic inflammation. TSLP is currently a candidate for therapeutic intervention in asthma, but the factors that drive TSLP expression (T cell-derived factors) may be equally relevant in the treatment of allergic inflammation.

The LINA cohort: indoor chemical exposure, circulating eosinophil/basophil (Eo/B) progenitors and early life skin manifestations.

BACKGROUND: Hematopoietic progenitor cells, especially those committed to the Eo/B lineage, are known to contribute to allergic inflammation. OBJECTIVE: The aim of the present study was to investigate whether environmental factors are associated with changes in numbers of circulating Eo/B progenitors at 1 year of age. METHODS: Peripheral blood from 60 1-year-old children enrolled in the LINA (Lifestyle and environmental factors and their Influence on Newborns Allergy risk) birth cohort was assessed for Eo/B progenitor cells (Eo/B CFU) using standardized and validated methylcellulose assays. Frozen peripheral blood mononuclear cells (PBMC) were cultured in the presence of IL-3, IL-5 or GM-CSF, and Eo/B CFUs enumerated. Clinical outcomes and exposure to environmental tobacco smoke (ETS) were documented by standardized questionnaires, and indoor volatile organic compound (VOC) concentrations were assessed by passive sampling. RESULTS: Children with skin manifestations (atopic dermatitis or cradle cap) within the first year of life had higher numbers of circulating IL-3-, IL-5- or GM-CSF-stimulated Eo/B CFUs (P < 0.05) at 1 year. In children with cradle cap, a positive correlation was found between Eo/B CFUs and exposure to ETS-related VOCs during pregnancy or at 1 year of age (P < 0.05). CONCLUSIONS AND CLINICAL RELEVANCE: This is the first demonstration that environmental exposures are positively associated with levels of circulating Eo/B progenitors. The recruitment and differentiation of Eo/B progenitors in response to environmental triggers may play a role in the development of skin manifestations during the first year of life.

Haemopoietic processes in allergic disease: eosinophil/basophil development.

Haemopoietic myeloid progenitors contribute to the ongoing recruitment of pro-inflammatory cells, such as eosinophils and basophils (Eo/B), to target tissue sites in allergic diseases. It is apparent that the development of allergic inflammation is critically dependent on the ability of the bone marrow to support the proliferation, differentiation and mobilization of haemopoietic progenitors. The haemopoietic inductive microenvironment in the bone marrow is crucial for providing signals necessary for maintenance of progenitor populations at varying stages of lineage commitment and permitting these cells to circulate in the bloodstream. Progenitors demonstrate responsiveness to specific cytokines, which varies with stage of differentiation. Pro-inflammatory signals, Th2 cytokines in particular, generated following allergen challenge, can impact on haemopoietic progenitor differentiation and mobilization, leading to accelerated Eo/B production. Allergen inhalation by allergic asthmatics induces a time-dependent change in cytokine levels within the bone marrow compartment, influencing differentiation of Eo/B progenitors, as evidenced by the relationship between increased bone marrow IL-5 levels and Eo/B production. It is proposed that inhaled allergen induces trafficking of IL-5-producing T lymphocytes to the bone marrow, further promoting eosinophilopoiesis through IL-5R signalling. In this manner, Th2 lymphocyte trafficking from the airway may regulate events occurring in the bone marrow. Negative regulators of Eo/B differentiation, including Th1 cytokines, may prove to be important for restoring homeostasis. Eo/B progenitors are also altered in cord blood of infants at risk of atopy and asthma, offering a potential biomarker for, and raising the possibility that Eo/B progenitors are directly involved in the development of allergic disease. For example, changes in the expression of haemopoietic cytokine receptors on cord blood progenitor cells are associated with maternal allergic sensitization, atopic risk and its development, suggesting that haemopoietic processes underlying the allergic phenotype may begin to evolve in the perinatal period.

Allergic rhinitis management pocket reference 2008.

Allergic rhinitis is a major chronic respiratory disease because of its prevalence, impacts on quality of life and work/school performance, economic burden, and links with asthma. Family doctors (also known as 'primary care physicians' or 'general practitioners') play a major role in the management of allergic rhinitis as they make the diagnosis, start the treatment, give the relevant information, and monitor most of the patients. Disease management that follows evidence-based practice guidelines yields better patient results, but such guidelines are often complicated and may recommend the use of resources not available in the family practice setting. A joint expert panel of the World Organization of Family Doctors (Wonca), the International Primary Care Airways Group (IPAG) and the International Primary Care Respiratory Group (IPCRG), offers support to family doctors worldwide by distilling the globally accepted, evidence-based recommendations from the Allergic Rhinitis and its Impact on Asthma (ARIA) initiative into this brief reference guide. This guide provides tools intended to supplement a thorough history taking and the clinician's professional judgment in order to provide the best possible care for patients with allergic rhinitis. A diagnostic Questionnaire specifically focuses the physician's attention on key symptoms and markers of the disease. When questionnaire responses suggest a diagnosis of allergic rhinitis, a Diagnosis Guide and a simple flowchart then lead the clinician through a series of investigations commonly available in primary care to support the diagnosis. In addition, key aspects of differential diagnosis are illuminated. According to ARIA, allergic rhinitis may be classified as Intermittent or Persistent, and as Mild or Moderate/Severe. The classification of rhinitis determines the treatment necessary, as set out in an ARIA flowchart included in this guide. The guide also includes information about the strength of evidence for efficacy of certain rhinitis treatments, a brief discussion of pediatric aspects, and a glossary of allergic rhinitis medications to assist the clinician in making medication choices for each individual patient. Finally, many patients with allergic rhinitis also have concomitant asthma, and this must be checked. The World Organization of Family Doctors has been delegated by WHO as the group that will be taking primary responsibility for education about chronic respiratory diseases among primary care physicians globally. This document will be a major resource in this educational program.

An evaluation of peripheral blood eosinophil/basophil progenitors following nasal allergen challenge in patients with allergic rhinitis.

OBJECTIVE: To evaluate the effect of a single nasal allergen challenge on peripheral blood eosinophil/basophil (Eo/B) progenitor cells and induced sputum eosinophil counts in subjects with allergic rhinitis. METHODS: Sixteen adults entered a sequential nasal control and allergen challenge study, outside the pollen season. Blind assessment of peripheral blood Eo/B progenitor colony forming units (CFU), induced sputum and nasal lavage cell counts was made before and 24 h after both challenges. Subjects recorded their rhinitis symptoms and nasal peak inspiratory flow, hourly at home, following both challenges. RESULTS: When comparing the values 24 h after the control vs. the allergen challenge, there were no significant differences in Eo/B progenitor CFU (control (mean, SD): 3.6 (1.0)/10(6) cells; allergen: 4.4 (1.1)/10(6) cells) or sputum eosinophils (control (median, inter-quartile range): 1.0 (0.3-1.7)%; allergen: 0.7 (0.0-1.3)%) despite a significant increase in the percentage (median (inter-quartile range) of eosinophils in nasal lavage (control: 0.6 (0.1-0.9)%; allergen; 1.9 (0.9-8.1)% and significant worsening of nasal peak inspiratory flow and rhinitis symptoms. CONCLUSIONS: Despite a significant increase in nasal symptoms and lavage eosinophil counts, a single nasal allergen challenge was not sufficient to elicit a measurable haemopoietic response in circulation, or an increase in sputum eosinophil counts.

Hemopoietic progenitor cells and hemopoietic factors: potential targets for treatment of allergic inflammatory diseases.

Eosinophilic infiltration is a cardinal feature of allergic inflammation; based upon its biological actions, the eosinophil has assumed the role as the principal inflammatory cell in asthma. In assessing the mechanisms by which eosinophils are recruited to sites of inflammation, a sizeable body of evidence exists supporting the proposal that expansion of hemopoietic compartments in the bone marrow stimulates an increased turnover and traffic of mature eosinophils to the site of allergic inflammation. In addition, recent findings point to the possible egress and traffic of primitive progenitor cells to the site of inflammation where in-situ differentiation may provide a continued supply of pro-inflammatory cells. In the present article, we will review the evidence for these findings, and discuss the rationale for targeting hemopoiesis and migrational pathways of hemopoietic cells in the treatment of allergic disease. In this context, we will discuss the effect of corticosteroid treatment on hemopoietic mechanisms; the effects of therapies that inhibit the actions of cysteinyl leukotrienes (CysLTs); the effects of in vivo blockade of the eosinophil-active cytokine, interleukin (IL)-5; and, the effects of antihistamines on hemopoiesis. In addition, we will address the potential role that small molecular weight chemokine receptor antagonists may play in modulating progenitor cell trafficking to tissue sites of inflammation.

Cognitive dysfunction and antiphospholipid antibodies in systemic lupus erythematosus.

Nervous system involvement in systemic lupus erythematosus (SLE) is typically diagnosed on the basis of clinical psychiatric and/or neurologic syndromes (NPSLE). Neuropsychological tests can be used to assess nervous system integrity even in the absence of major NP syndromes. Their application has uncovered significant cognitive dysfunction, ranging from mild to severe, in a sizeable proportion of SLE patients irrespective of clinical NP status. Cognitive dysfunction has now been accepted as a bona fide manifestation of NPSLE. The heterogeneity of clinical NPSLE manifestations is paralleled by the diversity of cognitive deficits reported in different studies and within different patients. The success of attempts to explain these deficits on the basis of potential pathogenetic mechanisms, such as antibrain antibodies and proinflammatory cytokines, has been uneven. To date, the most robust findings have emerged in relation to antiphospholipid antibodies, which carry with them important therapeutic implications.

Distinct phenotypic adhesion molecule expression on human cord blood progenitors during early Eosinophilic commitment: upregulation of beta(7) integrins.

Increasing levels of proinflammatory cells, including eosinophils and basophils, are seen at the site of allergen challenge in allergic disease of the airways. Mechanisms for the recruitment of these cell types could involve either specific upregulation of adhesion molecule and chemoattraction, or the initiation of proliferation and differentiation of inflammatory cell progenitors derived from the bone marrow. In this study, we demonstrate, in two systems of eosinophilic-basophilic lineage-committed granulocytes of relative immaturity, that eosinophilic differentiation in vivo implies the induction of a distinct adhesion phenotype, characterized by the upregulation of beta(7) integrin and downregulation of beta(1) and alpha(5) integrins. Moreover, the eosinophilic differentiation induced an upregulation of complement receptor type 1 and type 3, and the expression was further enhanced upon a short-course in vitro activation with ionomycin. These data indicate a sequential alteration of disparate members of the integrin family during eosinophilic-basophilic differentiation, which may attribute to specific adhesion requirements at distinct stages of cell maturation.