Basophil mast cell and eosinophil growth and differentiation factors in human allergic disease

Identifying regulatory pathways of spleen tyrosine kinase expression in human basophils

BACKGROUND

Expression levels of spleen tyrosine kinase (SYK), a critical signaling tyrosine kinase in basophils, are uniquely low relative to all other circulating leukocytes, and levels are highly variable in the population.

OBJECTIVE

We sought to determine whether transcriptional regulation of SYK through unique silencing of the SYK gene determines its basophil-specific expression patterns.

METHODS

Culture-derived basophils (CD34B cells) were derived from cultures of CD34⁺ progenitor cells by using 2 methods (G1 or G3). Peripheral blood basophils (PBBs; relative SYK protein level = 1), B cells (SYK = 8), CD34B-G1 cells (SYK = 11), and CD34B-G3 cells (SYK = 5) were examined by using assay for transposase-accessible chromatin sequencing (ATAC-seq) methods. In addition, the transcriptomes of 6 cell types, PBBs, peripheral blood eosinophils (SYK = 11), plasmacytoid dendritic cells (SYK = 30), CD34⁺ progenitors (SYK = 11), CD34B-G1 cells, and CD34B-G3 cells, were analyzed for patterns that matched patterns of SYK expression in these cells, with a focus on transcription factors.

RESULTS

ATAC-seq showed that PBBs have multiple open regions in the SYK gene, suggesting a nonsilenced state with 1 region unique to PBBs (low SYK expression), 1 region unique to both PBBs (low SYK expression) and both G1 and G3 CD34B cells (high and moderate SYK expression, respectively), and 5 regions unique to B cells (high SYK expression). SYK expression across the 6 cell types explored showed a unique pattern that was matched to expression patterns of 3 transcription factors: Kruppel-like factor 5 (KLF5), zinc-finger protein 608 (ZNF608), and musculoaponeurotic fibrosarcoma protein (c-MAF).

CONCLUSIONS

Two new potential regulatory pathways for SYK expression were identified. One appears independent of transcriptional regulation, and one appears to be dependent on transcriptional control in the SYK gene.

Intraepithelial Cell Population in the Allergic Nasal Mucosa

Intraepithelial migrating cells are presumed to play an important role in nasal mucosal immunity because these are the first to come into contact with various foreign particles inhaled and deposited on the nasal surface.

To elucidate nasal mucosal immunity, we carried out a quantitative study of the overall population of migrating cells and the lymphocyte subsets in the epithelial compartment of nasal mucosa in patients with house-dust nasal allergy, in patients with nonallergic rhinitis (chronic infectious rhinitis) and “normal” persons (as controls), using both light and electron microscopy in combination with an immunoperoxidase technique. Scrapings from the inferior turbinates were collected for examination of the epithelium.

In order of predominance, the most numerous migrating cells were lymphocytes, followed by eosinophils, mast cells, neutrophils, and macrophages in the allergy group; in the nonallergy group neutrophils, lymphocytes, followed by macrophages and eosinophils; and in the normal group lymphocytes were the most predominant. Electron microscopic observation revealed globule leukocytes in addition to the other cells. In subjects with nasal allergy, the migrating cell population in nasal secretion differed from scrapings, in that neutrophils and eosinophils were predominant. In our study of the lymphocyte subsets, although CD8+ cells (suppressor/cytotoxic T cells) were the most numerous (followed by CD16+ [natural killer cells], CD4+ [helper/inducer T cells] and CD21+ [B cells] in that order of predominance in the epithelium), no difference was noted in number among CD4+, CD8+, and CD16+ cells in nasal secretions.

On the basis of their ultrafine structure, many CD8+ cells and some CD4+ cells had the morphological appearance of activated lymphocytes. Lymphocytes, mast cells, and globule leukocytes, all of which reside in the allergic nasal epithelium, are likely to be involved in the nasal mucosal immunity.

Atractylodin Inhibits Interleukin-6 by Blocking NPM-ALK Activation and MAPKs in HMC-1

Atractylodin is one of the major constituents of the rhizome of Atractylodes lancea, which is widely used in Korean traditional medicine as a remedy for the treatment of gastritis and gastric ulcers. Despite of a major constituent of widely used botanical to treat inflammatory responses little is known about anti-inflammatory effect of atractylodin in the human mast cell (HMC-1). Hence, we evaluated the effect of atractylodin on the release of IL-6, the involvement of nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) and mitogen-activated protein kinases (MAPKs) in phorbol-12-myristate-13-acetate and A23187-induced HMC-1. In addition, Janus kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), phospholipase C (PLC) gamma 1, and AKT phosphorylation relevant to NPM-ALK signal pathway were assessed. IL-6 levels in the HMC-1 stimulated by phorbol-12-myristate-13-acetate and A23187 were apparently decreased by the treatment of atractylodin. Concurrently, atractylodin not only inhibited the phosphorylation of NPM-ALK, but also suppressed the phosphorylation of JAK2, STAT3, PLC gamma 1, and AKT. Furthermore, the activated mitogen-activated protein kinases (MAPKs) by phorbol-12-myristate-13-acetate and A23187 were inhibited by atractylodin. These results suggested that atractylodin might have a potential regulatory effect on inflammatory mediator expression through blockade of both the phosphorylation of MAPKs and the NPM-ALK signaling pathway.

Stability of Syk protein and mRNA in human peripheral blood basophils

In human basophils, Syk expression is 10-fold lower than most other types of leukocytes. There are indirect studies that suggest that Syk protein is highly unstable (a calculated half-life less than 15 min) in human peripheral blood basophils. Therefore, in these studies, Syk stability was directly examined. Purified basophils were metabolically labeled and a pulse-chase experimental design showed Syk protein to be stable in the time frame of 12 h (95% likelihood that half-life is more than 12 h). However, its synthetic rate was very slow (∼10-fold slower) compared with CD34-derived basophils, which have been shown to express levels of Syk consistent with other mature circulating leukocytes. Syk mRNA expression was found to be 5-30-fold lower than other cell types (CD34-derived basophils, peripheral blood eosinophils, and plasmacytoid dendritic cells). Syk protein and mRNA levels, across cell types, were relatively concordant. Syk mRNA in basophils showed a half-life of 3.5 h, which was greater than that of interleukin-4 or Fc epsilon receptor I-α mRNA (∼2 h), but somewhat shorter than Fc epsilon receptor I-β mRNA (8 h). A comparison of miR expression between CD34-derived and peripheral blood basophils demonstrated only 1 significant increase, in miR-150 (77-fold). Transfection in human embryonic kidney cells of a stabilized form of miR-150 showed that it modified expression of c-Myb mRNA but not of Syk mRNA or protein. These results suggest that low Syk expression in basophils results, not from protein instability and perhaps not from mRNA stability. Instead, the results point to the transcriptional nature of an important point of regulation.

Expression profiling of human basophils: modulation by cytokines and secretagogues

Human basophils are an accessible participant of the human allergic reaction. There is natural variation in various functional endpoints and in signaling molecule expression but there has been only a limited effort to place this information in the context of mRNA expression profiles. This study examined the hypothesis that unique mRNA signatures could be identified during the response of human basophils to several known forms of stimulation. Highly purified human basophils were cultured in vitro and exposed to IL-3, IL-5, NGF, IL-33, IL-2, anti-IgE Ab, or FMLP and the mRNA profiles examined by microarrays. The response to IL-3 and anti-IgE Ab were examined on 2–3 time frames and the response to IL-3 examined at several concentrations. In addition, the mRNA signatures of 3 different potential phenotypes were examined. These included basophils with the so-called non-releaser phenotype, and basophils from atopic and non-atopic subjects. Given the role of IL-3 in basophil maturation and the known profound effects on mature basophil function, it was not surprising that IL-3 showed the greatest influence on the basophil transcriptome. However, it also became apparent that the act of isolating and culturing basophils was sufficient to induce a large number of changes in the transcriptome, despite high viability and recovery. These “culture-effect” changes dominated the changes in mRNA profiles induced by other stimuli. Unique signatures for anti-IgE antibody and IL-33 could be identified although the number of gene transcripts (6–30) that were unique to these two stimuli was very limited. There were no apparent unique profiles for IL-5, NGF, IL-2 or FMLP. Therefore, a potential tool for screening basophil phenotypes was limited to changes that could be induced by IL-3 (or no IL-3), IL-33 and anti-IgE Ab.

Current Thinking on the Relationship Between Rhinosinusitis and Asthma

An observation made initially on clinical grounds and epidemiologic evidence, i.e., that rhinosinusitis and asthma are closely linked diseases is now supported by a growing body of scientific evidence. Most recent evidence supports the characterization of rhinosinusitis and asthma as two compartmental expressions of a common mucosal susceptibility to exogenous stimuli. In addition, there is evidence that the compartmental processes can affect and amplify each other via a systemic intermediary. The bone marrow is involved in this process, and IL-5 may be a key cytokine for orchestrating the systemic interaction. These facts argue that rhinosinusitis and asthma are not simply localized disease processes but part of a systemic inflammatory disease affecting the respiratory tract. They also provide a compelling rationale for combined treatment strategies with consideration of the treatment of rhinosinusitis as a means of improving asthma control and monitoring for signs of bronchial involvement in those with rhinosinusitis.

Intranasal corticosteroids reduce ocular symptoms associated with allergic rhinitis

OBJECTIVE: Clinical data and recent guidelines support the positive effects of intranasal corticosteroids on allergic rhinitis-associated ocular symptoms. This article reviews the epidemiology and pathophysiology of ocular allergy symptoms and efficacy, tolerability, and potenti mechanisms of action of intranasal corticosteroids in the treatment of this condition.

DATA SOURCES: MEDLINE database.

REVIEW METHODS: A search of pertinent literature identified in vitro, preclinical, and clinical data that involve intranasal corticosteroids in ocular-related studies. Searches that used epidemiology, pathophysiology, drug class and specific agents, and other appropriate search terms were conducted.

RESULTS: Ocular symptoms, common in patients with allergic rhinitis, are associated with reduced quality of life and substantial economic costs. In the conjunctival epithelium, an early, type-1 hypersensitivity reaction occurs after direct allergen exposure. Progression to late-phase response, with recurrence of symptoms and infiltration of inflammatory cells, may occur 4 to 8 hours later and appears to be dose-related. Alteration of nasal ocular reflex pathways may also contribute to ocular symptoms in allergic rhinitis. Clinical data indicate that intranasal corticosteroids significantly reduce total and individual ocular symptoms in subjects with allergic rhinitis. Meta-analyses have found that oral/topical antihistamines are not superior to intranasal corticosteroids in reducing ocular allergy symptoms. Ocular adverse events from intranasal corticosteroids are rare.

CONCLUSION: Intranasal corticosteroids are effective and well-tolerated in the treatment of ocular symptoms associated with allergic rhinitis. Additional studies are needed to better understand the mechanisms underlying the effects of intranasal corticosteroids on ocular symptoms.

cDNA cloning and substrate specificity of equine tryptase, a possible mediator in equine heaves

BACKGROUND

Mast cell mediators are believed to play a central role in inflammatory lung disorders such as human allergic and occupational asthma. Equine heaves is characterized by reversible neutrophilic airway inflammation and airway obstruction, primarily due to bronchospasm and mucus hypersecretion, following exposure of susceptible horses to organic stable dusts. As such, heaves shares many similarities with human occupational dust-induced asthma and therefore it is proposed that mast cells may also be implicated in the pathogenesis of heaves. Tryptase, a mast cell-specific proteinase, can be used as an indicator of biological mast cell activity.

OBJECTIVE

The aim of this study was to determine the cDNA sequence of equine tryptase and to investigate its substrate specificity in order to rationalize its enzymatic activity.

METHODS

RT-PCR cloning was used to sequence equine tryptase. Substrate specificity of equine tryptase was investigated using arginine and lysine containing substrates.

RESULTS

The cDNA and deduced amino acid (Aa) sequences for equine tryptase shared strong identity with other tryptases. Unusually for a trypsin-like proteinase however, equine tryptase has alanine at residue 216, rather than glycine, which confers increased arginine substrate specificity in vitro and may restrict fibrinogenolysis in vivo.

CONCLUSION

Cloning and sequencing of the mast cell proteinase equine tryptase will allow molecular probing of its expression in the lung of control and heaves-affected horses. Further work is warranted to determine the biological relevance of the unique alanine 216 substitution in the molecular sequence of the equine tryptase substrate-binding pocket.

The effect of desloratadine on eosinophil/basophil progenitors and other inflammatory markers in seasonal allergic rhinitis: a placebo-controlled randomized study

BACKGROUND

Eosinophil/basophil (Eo/B) progenitors fluctuate in the peripheral circulation during seasonal allergen exposure in atopic subjects. Several drugs have been shown to modulate Eo/B progenitor levels in the peripheral blood but, to date, the possible effect of antihistamines on Eo/B progenitors has not been explored. Our objective was to evaluate whether the antihistamine desloratadine (DL) can modulate peripheral blood Eo/B progenitors or other markers of allergic inflammation.

METHODS

We performed a randomized double-blind placebo-controlled study on the effects of DL on peripheral blood Eo/B progenitors in subjects with symptomatic, seasonal allergic rhinitis during a ragweed pollen season. Forty-five subjects were randomized to treatment for 4 weeks with DL 20 mg daily or placebo.

RESULTS

The expected fall in the number of Eo/B progenitors from baseline to 2 weeks of treatment was seen in the placebo group [median drop of 1.0 colony-forming unit (CFU)/10(6) cells], and was greater than in the DL group (median drop of 0.0 CFU/10(6) cells) (p = 0.013). The change in histamine concentration per colony from baseline to 2 weeks of treatment was lower in the DL group (median decrease of 6.1 pg/colony) compared to placebo (median increase of 1.8 pg/colony) (p = 0.01). An increase in the nasal lavage eotaxin concentration from baseline to 4 weeks of treatment was statistically significant in the placebo group but not in the DL group. Eo/B CFU were not affected by varying in vitro concentrations of DL.

CONCLUSION

These results suggest that DL can modulate aspects of allergic inflammation in vivo through mechanisms other than simple blockade of H1 histamine receptors.

The potential role of allergen-specific sublingual immunotherapy in atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin disease associated with increasing prevalence, morbidity, and cost in developed Western countries. Frequently associated with respiratory allergy during adulthood, atopic dermatitis often represents the first phenotypic appearance of atopy in early childhood when the allergic 'march' starts and progressively moves toward food allergy, asthma, and rhinitis. At present, a consistent body of evidence supports the view that atopic dermatitis may represent the skin compartmentalization of a systemic allergic inflammation. Lymphocytes infiltrating early lesional skin express a T helper (Th) 2 pattern of cytokine secretion (increased levels of interleukin [IL]-4 and/or IL-13 and decreased levels of interferon-gamma) as well as the typical Th2-type chemokine receptor CCR4, specific to the thymus and activation-regulated chemokines. Keratinocytes from patients with atopic dermatitis produce thymic stromal lymphopoietin, a novel cytokine that supports the early lymphocyte development in mouse models, and activates dendritic cells involved in the pathogenesis of allergic diseases in humans. Increased levels of circulating hemopoietic precursor cells have been reported in atopic dermatitis, as in allergic asthma and rhinitis. Furthermore, the recognition of CD34+ hemopoietic precursor cells, and evidence for cellular differentiation/maturational events occurring within atopic dermatitis skin lesion infiltrates, are consistent with the recent reinterpretation of the Th2/Th1 paradigm, where Th2 cells appear to belong to the early stages and Th1 to the ultimate stages of a linear, rather than divergent, pattern of lymphoid differentiation. This more detailed understanding of the immunologic derangements contributing to the atopic dermatitis pathogenesis has led to growing interest in allergen-specific immunotherapy for the disease. Due to the complexity intrinsic to atopic dermatitis and the lack of consensus-based guidelines for standardized outcome measure, only eight studies are available in the literature for a qualitative evaluation of this treatment approach. Two of these studies were double blind and placebo controlled, and six were cohort studies. Immunotherapy was found to be effective in one controlled study and five observational reports. Uncertain results were provided by one low-powered, controlled study, and negative outcomes were raised by a unique study performed with oral immunotherapy, which is not an effective route of mucosal allergen administration. Thus, more efficacy studies are required before immunotherapy could be recommended for the routine treatment of atopic dermatitis. Allergen-specific sublingual immunotherapy, given its excellent safety profile and ability to interfere with the systemic aspects of allergic inflammation, appears a good potential candidate for the pathogenetic treatment of the disease.

The CCR3 receptor is involved in eosinophil differentiation and is up-regulated by Th2 cytokines in CD34+ progenitor cells

The involvement of chemokines in eosinophil recruitment during inflammation and allergic reactions is well established. However, a functional role for chemokines in eosinophil differentiation has not been investigated. Using in situ RT-PCR, immunostaining, and flow cytometric analysis, we report that human CD34+ cord blood progenitor cells contain CCR3 mRNA and protein. Activation of CD34+ progenitor cells under conditions that promote Th2 type differentiation up-regulated surface expression of the CCR3. In contrast, activation with IL-12 and IFN-gamma resulted in a significant decrease in the expression of CCR3. Eotaxin induced Ca2+ mobilization in CD34+ progenitor cells, which could explain the in vitro and in vivo chemotactic responsiveness to eotaxin. We also found that eotaxin induced the differentiation of eosinophils from cord blood CD34+ progenitor cells. The largest number of mature eosinophils was found in cultures containing eotaxin and IL-5. The addition of neutralizing anti-IL-3, anti-IL-5, and anti-GM-CSF Abs to culture medium demonstrated that the differentiation of eosinophils in the presence of eotaxin was IL-3-, IL-5-, and GM-CSF-independent. These results could explain how CD34+ progenitor cells accumulate and persist in the airways and peripheral blood of patients with asthma and highlight an alternative mechanism by which blood and tissue eosinophilia might occur in the absence of IL-5.

CD34+ cells in peripheral blood of healthy human beings and allergic subjects: clue to acute and minimal persistent inflammation

BACKGROUND

There is compelling evidence that hemopoietic precursor cells (HPC) play a crucial role in establishing cellular inflammation in allergic diseases. Increased levels of circulating CD34+ HPC committed to the myeloid lineage have been extensively reported in allergic rhinitis, asthma and eczema, whereas CD34+ cells have been identified within the cellular infiltrates of tissues, at peripheral sites of inflammation.

METHOD

We conducted a pilot study to evaluate CD34+ traffic in the peripheral blood of 22 consecutive patients (13 men and nine women; mean age 28.9 years), independently of treatment. The patients presented rhinitis, asthma, eczema, urticaria and adverse food reactions of suspected allergic origin. Allergic reactions were extrinsic in 18 patients and intrinsic in four. In 12 patients who underwent sublingual specific immunotherapy, CD34+ cells were quantified at enrollment (T0), one year later (T1) and two years later (T2). The severity of symptoms was graded on a five-point scale (0 = absence of symptoms and 4 = severe symptoms). Twenty healthy human subjects (10 men and 10 women; mean age 24.5 years) were evaluated as controls. To obtain information about the total amount of circulating HPC, independently of the lineage commitment (Lin+/-) and the degree of differentiation (CD34bright/dim), we used a modification of the Milan protocol of peripheral blood CD34+ cell estimation. The cells were analyzed using a BD FACScan or FACSCalibur and the results were expressed as the percentage of positive cells.

RESULTS

CD34+ cell traffic in the control group was very low since all values were < 0.10 (median value: 0.03 %). Values in the patient group were increased in both extrinsic and intrinsic forms with a median value of 0.25 % (interquartile range: 0.13- 0.33 %). The relationship between CD34+ traffic and the severity score was highly significant (Spearman's rho = 0.954; test of Ho: CD34; independent score: Pr > t = 0.000).

CONCLUSIONS

The data reported herein suggest that the method employed is effective in assessing acute allergic inflammation, as well as minimal persistent inflammation underlying an asymptomatic clinical condition. Evaluation of CD34bright/dim peripheral traffic, if confirmed by the outcomes of a multicenter study currently being planned together with traditional study of circulating IgE, could be a reliable non-invasive laboratory tool for monitoring allergic inflammation.

Systemic aspects of allergic disease: the role of the bone marrow

In recent years, there has been an increasing appreciation of the important contribution of bone-marrow-related, hemopoietic mechanisms to allergic diseases. Eosinophil/basophil-progenitor levels fluctuate in the peripheral blood during allergen exposure and the cells home to peripheral tissue, where they differentiate. It is becoming apparent that several cytokines, particularly IL-5, have multiple effects on progenitors and allergic inflammation. Within the past few years, studies of the therapeutic implications of this bone marrow contribution to atopy have been initiated; the effects of corticosteroids, leukotriene-receptor blockers, antagonism of IL-5 and modulation of differentiation by retinoic acid on progenitors will be reviewed.

Variations in serum levels of interleukin (IL)-1beta, IL-2, IL-6, and tumor necrosis factor-alpha during specific immunotherapy

BACKGROUND

Cytokine production by T helper cells is essential for the induction and maintenance of allergic inflammation in the bronchial mucosa. According to recent views, specific immunotherapy (SIT) favors the differentiation of T lymphocytes into cells of the Th1 rather than those of the Th2 subset.

OBJECTIVE

To determine whether or not SIT induces a decrease in the inflammatory reaction by studying eventual variations in the serum levels of IL-1beta, IL-2, IL-6, and TNF-alpha in allergic subjects during SIT.

METHODS

Serum levels of IL-1beta, IL-2, IL-6, and TNF-alpha were determined before and after 3, 6, and 9 months of SIT by an immunoradiometric assay (IRMA) in 11 adults with perennial allergic asthma and/or rhinitis caused by house dust mites and in 6 nonatopic healthy volunteers.

RESULTS

Median serum IL-1beta and TNF-alpha levels of the patients were significantly higher at baseline than those of the controls and decreased during SIT to values similar to or lower (P < .01) after 6 months of SIT for TNF-alpha than those of the controls. Median serum IL-2, significantly lower at baseline than in the controls, increased during SIT to a level similar to that of the controls. Although the median values of IL-1beta and TNF-alpha in the patients tended to decrease and those of IL-2 to increase during SIT, the differences were not significant; the correlation coefficients (r) of the serum levels of IL-1beta IL-6, and TNF-alpha versus duration of SIT were negative, while that of IL-2 was positive.

CONCLUSIONS

Decreases in median serum IL-1beta and TNF-alpha levels during SIT, together with the increases in serum IL-2 and IL-6, compared with those of the controls furnish evidence supporting a reduction in the inflammatory response in the course of SIT.

Systemic aspects of allergic disease: bone marrow responses

In patients with allergic diseases, allergen provocation can activate a systemic response that provokes inflammatory cell production by the bone marrow. After release and differentiation of progenitor cells, eosinophils, basophils, and mast cells are typically recruited to tissues in atopic individuals. An understanding at the molecular level of the signaling process that leads to these systemic responses between the target organ, especially the airways, and the bone marrow may open up new avenues of therapy for allergic inflammatory disease. Studies that support the critical involvement of the bone marrow in the development of eosinophilic inflammation of the airways point out the systemic nature of these conditions and their potential for biologic intervention. Hemopoietic events that originate in the bone marrow are potential targets of long-term therapy for rhinitis and asthma. For example, the "beneficial" systemic activity of cortico-steroids through modulation of hemopoietic mechanisms and inflammatory cell recruitment to the airways is essential for the optimal treatment of both upper and lower airway inflammation.

Evidence for local eosinophil differentiation within allergic nasal mucosa: inhibition with soluble IL-5 receptor

Eosinophil differentiation occurs within the bone marrow in response to eosinopoietic cytokines, particularly IL-5. Recently, however, eosinophil precursors (CD34/IL-5Ralpha+ cells) and IL-5 mRNA+ cells have been identified within the lungs of asthmatics, indicating that a population of eosinophils may differentiate in situ. In this report, we examined the presence of eosinophil precursors within allergic nasal mucosa and examined whether they undergo local differentiation following ex vivo stimulation. We cultured human nasal mucosa obtained from individuals with seasonal allergic rhinitis with either specific allergen, recombinant human IL-5 (rhIL-5), or allergen + soluble IL-5Ralpha (sIL-5Ralpha), shown to antagonize IL-5 function. Simultaneous immunocytochemistry and in situ hybridization demonstrated that there were fewer cells coexpressing CD34 immunoreactivity and IL-5Ralpha mRNA following culture with allergen or rhIL-5, compared with medium alone. Immunostaining revealed that the number of major basic protein (MBP) immunoreactive cells (eosinophils) was higher within tissue stimulated with allergen or rhIL-5, compared with unstimulated tissue. In situ hybridization detected an increase in IL-5 mRNA+ cells in sections from tissue cultured with allergen, compared with medium alone. These effects were not observed in tissue cultured with a combination of allergen and sIL-5Ralpha. Colocalization analysis indicated this expression to be mainly, but not exclusively, T cell (44%) and eosinophil (10%) derived. Our findings suggest that a subset of eosinophils may differentiate locally within allergic nasal mucosa, in what appears to be a highly IL-5-dependent fashion, and imply that this process might be regulated in vivo by endogenous production of sIL-5Ralpha.

Mechanisms and regulation of polymorphonuclear leukocyte and eosinophil adherence to human airway epithelial cells

Polymorphonuclear leukocytes (PMN) and eosinophils (Eos) are important cellular participants in a variety of acute and chronic inflammatory reactions in the airway. Histologic evidence has implicated direct interactions between these two subsets of leukocytes and airway epithelial cells during inflammation. A comprehensive characterization and comparison of physiologic stimuli and adhesion molecule involvement in granulocyte-epithelial-cell interactions done with nontransformed human airway epithelial cells has not been reported. We therefore examined the regulation and biochemical mechanisms governing granulocyte-epithelial-cell adhesion, using either purified PMN or Eos and primary cultures of human bronchial epithelial cells (HBECs). We investigated the involvement of a number of proinflammatory signals associated with allergic and nonallergic airway inflammation, as well as the contribution of several epithelial and leukocyte adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and members of the beta(1), beta(2), and beta(7) integrin families. ICAM-1 was expressed at low levels on cultured HBECs and was markedly upregulated after stimulation with interferon (IFN)-gamma or, to a lesser extent, with tumor necrosis factor (TNF)-alpha or interleukin (IL)-1. VCAM-1 was not present on resting HBECs, and was not upregulated after stimulation with IFN-gamma, IL-1, IL-4, or TNF-alpha. PMN adhesion to HBECs could be induced either through activation of PMN with IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), or C5a, but not with IL-5 or by preactivation of HBECs with TNF-alpha or IFN-gamma. Blocking antibody studies indicated that PMN-HBEC adherence depended on beta(2) integrins, primarily alpha(M)beta(2) (Mac-1). Adherence of Eos to HBECs could be induced through activation of Eos with IL-5, GM-CSF, or C5a, but not with IL-8 or by prior activation of HBECs with TNF-alpha of IFN-gamma. Maximal adhesion of Eos and PMN required pretreatment of HBECs with either TNF-alpha or IFN-gamma in addition to leukocyte activation. Adherence of Eos to unstimulated HBECs was mediated through both beta(1) and beta(2) integrins, whereas adhesion of Eos to activated HBECs was dominated by beta(2) integrins. Adhesion of both Eos and PMN was inhibited by treatment of HBECs with blocking antibodies to ICAM-1. Differential utilization of beta(1) and beta(2) integrins by Eos, depending on the activation state of the epithelium, is a novel finding and may affect activation and/or recruitment of Eos in airway tissue. Mechanisms of adhesion of HBECs to Eos and PMN, as evidenced by the different responsiveness of the two latter types of cells to IL-8 and IL-5, may account for a prevalence of Eos over PMN in certain airway diseases.

An inhaled corticosteroid, budesonide, reduces baseline but not allergen-induced increases in bone marrow inflammatory cell progenitors in asthmatic subjects

We have previously shown that allergen inhalation by asthmatics is associated with increases in bone marrow eosinophil/basophil colony-forming cells (Eo/B-CFU), and increases in CD34(+) hemopoietic progenitors expressing the alpha-subunit of the IL-5 receptor (IL-5Ralpha). This study investigated the effect of inhaled corticosteroid on baseline numbers and allergen-induced increases in these parameters. Nine subjects with mild, stable asthma inhaled budesonide (400 microgram/d) for 8 d in a placebo-controlled, double-blind, randomized crossover study. On Day 7, subjects inhaled allergen, with bone marrow sampling before and 24 h after challenge. Budesonide inhalation significantly attenuated the allergen-induced early and late asthmatic responses, degree of increase in sputum and blood eosinophils, as well as the baseline numbers of total bone marrow CD34(+) cells (p < 0.05), CD34(+)IL-3Ralpha+ cells (p < 0.01) and IL-5-responsive Eo/B-CFU (p < 0.05). Allergen inhalation significantly increased Eo/B-CFU grown in the presence of IL-3, GM-CSF, or IL-5 alone (p < 0.05) and in combination (p < 0.01), as well as the number of CD34(+)IL-5Ralpha+ cells (p < 0.01). However, these increases in Eo/B-CFU and CD34(+)IL-5Ralpha+ cells were not affected by budesonide treatment. These data demonstrate that short-term inhaled budesonide treatment has a systemic effect in inhibiting the turnover of a subpopulation of bone-marrow-derived progenitors, but that inhalation of allergen overcomes this inhibitory effect.

Allergen challenge increases cell traffic between bone marrow and lung

Increases in inflammatory-cell progenitors have been demonstrated in the bone marrow (BM) after inhalation of Ascaris suum in dogs at the time of allergen-induced airway hyperresponsiveness (AHR). The aim of this study was to evaluate the effect of allergen challenge on trafficking of inflammatory cells and their progenitors from the BM to the lung, using a marker of proliferating cells, bromodeoxyuridine (BrdU). BrdU is a thymidine analogue taken up by the DNA of dividing cells, and can be detected with immunohistochemistry (IHC). The development of AHR was assessed through acetylcholine (ACh) airway responsiveness before and after allergen inhalation. Two groups of dogs were matched for the degree of AHR after a screening allergen challenge. On the study day, one group inhaled allergen (n = 8) and one group inhaled diluent (n = 8). All dogs received equal bolus injections of BrdU before and at 5 h after challenge. Blood samples were taken before challenge and at 5 h and 24 h after challenge, and BM aspirate and bronchoalveolar lavage (BAL) samples were taken 24 h after challenge. BrdU-positive cells were detected in cytospin preparations of these samples, using IHC. Allergen inhalation caused AHR (P < 0.05) at 24 h after allergen challenge, and also an increase in BrdU-positive cells in blood, which was 5.7 +/- 0.6% (mean +/- SEM) after allergen challenge and 2.5 +/- 0.7% after diluent (P < 0.005); in BM the increase in BrdU-positive cells was 27.0 +/- 3.4% after allergen challenge and 18.9 +/- 3.2% after diluent (P = 0.1); and in BAL the increase was 3.2 +/- 0.4% after allergen challenge and 0.8 +/- 0.3% after diluent (P < 0.005). There was a significant correlation between the number of BAL neutrophils and the percentage of BrdU-positive BAL cells (r2 = 0.54, P < 0.05). These results demonstrate an allergen-induced increase in proliferating cells, probably in the BM, and indicate that such cells traffic through the circulation into the lungs in response to allergen inhalation.

Changes in bone marrow inflammatory cell progenitors after inhaled allergen in asthmatic subjects

Increases in inflammatory cell progenitors, particularly eosinophil/basophil colony-forming cells (Eo/B-CFU), occur in peripheral blood after allergen provocation. The role of bone marrow (BM) in these reactions is unclear. We examined the effect of allergen challenge on human bone marrow progenitor cell growth. Fifteen asthmatic subjects, eight dual responders (DR) and seven isolated early responders (IER), were challenged with inhaled allergen. BM aspirates were taken before and 24 h after challenge and progenitors were enumerated by a colony-forming assay. Eo/B-CFU numbers increased in both groups after allergen challenge (p < 0.0001). For DR, the increases were significant for BM incubated with optimal GMCSF and IL-5, but not with IL-3. For IER, the increases were significant for all three cytokines tested. At a suboptimal concentration of IL-5, there was a significant increase in the number of Eo/B-CFU after allergen in the DR, from 5.25 +/- 1.2 to 9.68 +/- 2.1 per 2.5 x 10(5) cells plated (p < 0.01), which was not demonstrated in the IER (p = 0.94). The responses at this concentration of IL-5 were different between groups (p < 0.05). These results demonstrate that inhaled allergen increases BM Eo/B-CFU, and that the bone marrow of dual responders is more responsive to IL-5 after allergen.

A new murine model of pulmonary eosinophilic hypersensitivity: contribution to experimental asthma

BACKGROUND

We have recently described a model of hypersensitivity reaction in the mouse paw, which induces a typical late-phase reaction with a marked eosinophilic infiltrate.

OBJECTIVE

In the search for a murine model of asthma, this model was adapted to the lungs and compared with other models of pulmonary hypersensitivity.

METHODS

A fragment of heat-coagulated hen's egg white was implanted subcutaneously, and 14 days later, the mice were challenged intratracheally with aggregated ovalbumin. Comparison was made with a group that received subcutaneous injection of soluble ovalbumin in alumen, challenged as described above and with four additional protocols of immunization and challenge.

RESULTS

Forty-eight hours after challenge, the percentage of eosinophils was higher in the egg white implant group (35%) than in the group immunized with ovalbumin in alumen (10.4%). The eosinophil peroxidase activity in lung homogenates of the first group was also significantly higher (529 ng/ml) than that of the second group (43 ng/ml). These results were reproduced in five different mouse strains. Compared with five different models of lung hypersensitivity, the egg white implant model was unique in terms of persistence of the pulmonary eosinophilia. Histopathologic analysis of the lungs of mice immunized with egg white implant showed peribronchial, perivascular, and intraepithelial eosinophil infiltration; morphologic characteristics of bronchoconstriction; and patchy epithelial shedding. At 21 days, in addition to persistence of eosinophil infiltrate, enlarged alveoli, reflecting air trapping, were observed.

CONCLUSION

On the basis of the characteristics of the model described here, we propose it as a suitable murine model of asthma.

The role of the bone marrow in allergy and asthma

The above studies have begun to address the fundamental question of the mechanisms of bone marrow involvement and response to allergen challenge in allergic asthmatics. Further studies in this area should complement our investigations in human asthma--which suggest that a particular bias toward differentiation of Eo-Baso progenitors characterizes the atopic state--as well as our findings in the dog model of allergen-induced airway hyperresponsiveness, which indicate that the bone marrow responds to inhalation of allergen or corticosteroids. Taken in the context of previous indications that IgE and bronchial responsiveness may both be transferrable through bone marrow transplantation (109), these findings indicate a physiologic role for the bone marrow in allergic inflammation. Likewise, these concepts provide a basis for making certain predictions regarding management and novel therapeutic interventions in atopy and asthma.

Lymphocyte infiltration and thickness of the nasal mucous membrane in perennial and seasonal allergic rhinitis

We have used immunocytochemical techniques to study infiltration by lymphocytes in biopsy specimens of the nasal mucosal membrane in 24 atopic patients and 10 normal volunteers. Twelve patients had perennial rhinitis and 12 had seasonal allergic rhinitis (SR) to grass pollen. Biopsy specimens were taken both in and out of the pollen season in patients with SR. Biopsy specimens were strained with the indirect immunoperoxidase technique and monoclonal antibodies to CD3, CD4, CD8, CD22, and CD25. T helper cells (CD4+) and CD24+ cells were significantly more numerous in patients exposed to allergen (those with perennial rhinitis and SR in season) compared with normal volunteers, whereas values for SR out of season were intermediate. The thickness of the nasal epithelium was significantly (p < 0.05) greater in biopsy specimens from patients with perennial rhinitis (mean, 51.43 microns) than in those from patients with SR in season (median, 32.44 microns). These results suggest that in allergic rhinitis, natural exposure to allergen is accompanied by increased infiltration of the nasal mucous membrane by T-helper and CD25+ cells.

Albuterol and nedocromil sodium affect airway and leukocyte responses to allergen

We investigated the effects of inhaled nedocromil sodium and albuterol administered prior to allergen challenge in the late asthmatic response (LAR) and circulating cells in a double-blind placebo-controlled study. An additional control day (no allergen) was included to determine diurnal variation. On the control day no change in airway caliber occurred, but a diurnal increase in the numbers of all circulating leukocytes except basophils was seen. Placebo premedication followed by allergen challenge caused both an early asthmatic response (EAR) and a late asthmatic response (LAR). Following allergen challenge after placebo the diurnal increase in eosinophils at 8 h was abolished, and elevated eosinophil and basophil counts were observed at 24 h. Nedocromil sodium attenuated both the EAR and the LAR, and it restored the eosinophil and basophil responses toward normal. Albuterol abolished the EAR and attenuated the LAR and the 24-h increase in circulating basophils. No changes in lymphocyte subpopulations were seen. We conclude that during the LAR there is entrainment of eosinophils within the lung, with a subsequent bone marrow response increasing peripheral populations of eosinophils and basophils. Nedocromil sodium may act by inhibiting the recruitment of inflammatory cells, particularly eosinophils, possibly by affecting the generation of cytokines and the expression of leukocyte-specific adhesion molecules. Albuterol may have similar actions as shown by an effect on basophils.

Airway mucosal inflammation even in patients with newly diagnosed asthma

We have studied bronchial biopsies from 14 patients with newly diagnosed asthma (four men and 10 women), who had had asthma symptoms, on average, 7.4 months (range, 2 to 12 months) and from four control subjects. The patients had not received corticosteroids, disodium cromoglycate, or theophylline before the study. The bronchial biopsies were taken, using a rigid-tube bronchoscope under local anaesthesia, from two different airway levels: (1) inside the right upper lobe bronchus, and (2) at the opening of the right middle lobe. The specimens were prepared for both light and electron microscopy. The use of Slot grids 1 x 2 mm enabled a large area of the thin sections to be photographed and analyzed by applying a graphic Autocad program. There was an increase in the numbers of mast cells (p < 0.001), eosinophils (p < 0.05), lymphocytes (p < 0.05), and macrophages (p < 0.05) in the epithelium of patients with newly diagnosed asthma as compared with those in control subjects. In the lamina propria, these asthmatic patients had more eosinophils (p < 0.001), lymphocytes (p < 0.001), macrophages (p < 0.001), and plasma cells (p < 0.001) than did the control subjects. We conclude that, in asthma, an airway inflammatory process is present even at a clinically early stage of the disease. In the asthmatic airways, there are signs of a general inflammatory response caused by more than one cell type.

Mediator and cytokine mechanisms in asthma

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Histopathologic and immunohistochemical findings associated with inflammatory dermatoses in human immunodeficiency virus type 1 disease and their correlation with Walter Reed stage. Military Medical Consortium for Applied Retroviral Research

BACKGROUND

Cutaneous lesions are common in patients with human immunodeficiency virus type 1 (HIV-1) infection. In many cases they are nonspecific inflammatory dermatoses.

OBJECTIVE

Our goal was to determine whether features of these inflammatory dermatoses were characteristic of HIV-1 infection and whether the changes correlated with the stage of disease.

METHODS

Biopsy specimens of inflammatory dermatoses from 176 HIV-1-infected patients in all Walter Reed stages were reviewed and the changes were compared with each WR stage.

RESULTS

The changes found were nonspecific but were suggestive of features described in graft-versus-host disease and became more prominent in late-stage disease.

CONCLUSION

A correlation was found between the changes and the stage of disease, and the findings add support to prior reports that at least some of the changes in HIV-1 infection may be autoimmune in origin.

Protective effects of cyclophosphamide, cyclosporin A and FK506 against antigen-induced lung eosinophilia in guinea-pigs

A close association has been recognized between activated T cells and eosinophils in asthma, albeit circumstantial. The present study attempted to investigate this relationship in an animal model of lung eosinophilia using the new generation of T cell-selective immunosuppressants, cyclosporin A and FK506, compared with the myelotoxic immunosuppressive agent cyclophosphamide. Antigen challenge of ovalbumin-sensitized guinea-pigs resulted in a lung eosinophilia which was assessed by bronchoalveolar lavage. All three agents caused a marked suppression of lung eosinophilia at 24 h post-challenge when the compounds were administered at the time of sensitization but not when administered for 3 days before lavage. However, the lung eosinophilia at 72 h post-challenge was reduced significantly by FK506 and by cyclophosphamide, but not by cyclosporin A, when the drugs were administered for 3 days, before lavage. These results strongly suggest the involvement of T cells in antigen-induced late phase (72 h) eosinophilia in guinea-pigs but not at 24 h. The effects of cyclophosphamide were always associated with a reduction in circulating white cell counts, whereas cyclosporin A and FK506 showed no myelotoxic properties. These results suggest the potential therapeutic use of selective, non-cytotoxic immunosuppressive agents in asthma.

Asthma: cells and cytokines

The pathology of bronchial asthma demonstrates a multicellular process. In an attempt to elucidate the cellular biology of airways inflammation, it becomes important to understand not only the biology of each individual cell type but also the interaction between different cells. This review focuses on a documentation of some of the biological effects of the constituent cells in the airway mucosa and a discussion of their potential interactions through the release and action of different cytokines. It seems likely that future research will address the in vivo release of different cytokine molecules in the asthmatic process using techniques of molecular biology. There likely will be increasing information available about the regulation and the actions of these molecules on target cells and tissues. Elucidation of some of the complex interactions between different cells and the role of different cytokine molecules may provide a novel approach to the therapy of bronchial asthma.

Allergen-induced asthmatic responses. Relationship between increases in airway responsiveness and increases in circulating eosinophils, basophils, and their progenitors

The inflammatory response during allergen-induced asthma was assessed using serial measures of peripheral blood eosinophils (Eo), basophils (B), and Eo/B progenitor cells (Eo/B-CFU). A group of 14 stable asthmatic individuals (beta 2-agonists only as needed) had inhalation provocation tests with allergen (18 tests in total) and with diluent. Serial blood samples were taken before and 1 and 24 h after the tests; methylcellulose cultures for Eo/B-CFU and granulocyte-macrophage (GM-CFU) were scored at 14 days. Circulating Eo, B, and Eo/B-CFU were increased at 24 h after allergen inhalation when this resulted in increased histamine airway responsiveness (n = 13). In the 5 subjects with isolated early asthmatic responses the Eo, B, and Eo/B-CFU counts did not change. There was no change in the GM-CFU after allergen. The ratio change in circulating Eo/B-CFU was negatively correlated with baseline histamine airway responsiveness (r = -0.8, p less than 0.05). Four subjects who had an isolated early response and no blood changes to one allergen developed an increase in histamine airway responsiveness and an increase in Eo, B, and Eo/B progenitors after inhalation of a second different allergen. The results indicate that in subjects with an allergen-induced increase in histamine airway responsiveness, an inflammatory response occurs that includes an increase in the number of Eo/B progenitors. This response, possibly mediated by Eo/B growth and differentiation factors, could lead to the accumulation of these cells in the airway and contribute to the airways inflammation present in asthma.

The inflammatory response in asthma exacerbation: changes in circulating eosinophils, basophils and their progenitors

Circulating eosinophils, basophils and eosinophil/basophil (Eo/B) progenitors were examined in 12 patients at the time of an exacerbation of asthma accompanied by sputum eosinophilia and after resolution of the exacerbation with inhaled corticosteroid treatment. Differential counts were performed and peripheral blood non-adherent mononuclear cells were cultured for 14 days in methyl-cellulose to determine the number of Eo/B and granulocyte-macrophage (GM) colonies without knowledge of the clinical conditions or findings. With resolution of the asthma exacerbation on beclomethasone therapy, there were significant falls in circulating eosinophils, basophils and Eo/B colonies whereas GM colonies were unchanged. To elucidate whether the observed changes could be due to systemic absorption or local action of inhaled corticosteroid, seven subjects with allergic rhinitis and no current evidence of lower airway inflammation (no symptoms of asthma and normal methacholine airway responsiveness) received 14 days' treatment with the same dose of inhaled beclomethasone or of placebo in a double-blind randomized cross-over study. No significant changes in airway function or in circulating cell counts were observed. The results suggest reduced production of eosinophils and basophils after the resolution of an exacerbation of asthma. This effect may be due to reduced levels of airway-derived eosinophil-basophil growth and differentiation factors.