Human eosinophils have prolonged survival, enhanced functional properties, and become hypodense when exposed to human interleukin 3

IL-3: key orchestrator of inflammation

Interleukin (IL)-3 has long been known for its hematopoietic properties. However, recent evidence has expanded our understanding of IL-3 function by identifying IL-3 as a critical orchestrator of inflammation in a wide array of diseases. Depending on the type of disease, the course of inflammation, the cell or the tissue involved, IL-3 promotes either pathologic inflammation or its resolution. Here, we describe the cell-specific functions of IL-3 and summarize its role in diseases. We discuss the current treatments targeting IL-3 or its receptor, and highlight the potential and the limitations of targeting IL-3 in clinics.

Transcriptomic analysis of the anti-inflammatory effect of Cordyceps militaris extract on acute gouty arthritis

Background: Gouty arthritis (GA) is a common inflammatory disease that causes pain due to the deposition of monosodium urate (MSU) crystals into joints and surrounding tissues. Anti-inflammatory drugs have significant clinical anti-inflammatory and analgesic effects, but they have many side effects. Cordyceps militaris is an edible and medicinal fungus, and its extract (CME) has good anti-inflammatory and analgesic effects. This study aimed to investigate the anti-inflammatory effect of CME on GA and its underlying mechanism.

Methods: The effect of CME on the expression of related inflammatory factors and histopathological changes in the MSU-induced acute inflammatory gout model in rats was studied by ELISA and HE, and its anti-inflammatory mechanism was analyzed by transcriptome combined with RT-qPCR.

Results: CME significantly improved gait scores and joint swelling in GA rats, and reduced MSU-induced inflammatory cell infiltration. CME inhibited MSU-induced inflammatory responses by reducing the levels of pro-inflammatory factors TNF-α, IL-1β, IL-6, and Caspase-1 and increasing the anti-inflammatory factor IL-10. Transcriptome analysis showed that CME significantly altered inflammation-related cytokine pathways, and identified four major genes involved in regulation of inflammation, CCL7, CSF2RB, LIF, and IL-1β. In addition, RT-qPCR was performed to verify these differential genes.

Conclusion: CME significantly alleviated the inflammatory progression of GA and ameliorated the onset of GA. The underlying mechanism may be related to triggering the cytokine-cytokine receptor interaction signaling pathway to inhibit the activation of the inflammasome and regulate the immune system. And it regulates the inflammatory response induced by MSU crystals through the genes CCL7, CSF2RB, and IL-1β.

Regulation of Eosinophilia in Asthma-New Therapeutic Approaches for Asthma Treatment

Asthma is a complex and chronic inflammatory disease of the airways, characterized by variable and recurring symptoms, reversible airflow obstruction, bronchospasm, and airway eosinophilia. As the pathophysiology of asthma is becoming clearer, the identification of new valuable drug targets is emerging. IL-5 is one of these such targets because it is the major cytokine supporting eosinophilia and is responsible for terminal differentiation of human eosinophils, regulating eosinophil proliferation, differentiation, maturation, migration, and prevention of cellular apoptosis. Blockade of the IL-5 pathway has been shown to be efficacious for the treatment of eosinophilic asthma. However, several other inflammatory pathways have been shown to support eosinophilia, including IL-13, the alarmin cytokines TSLP and IL-33, and the IL-3/5/GM-CSF axis. These and other alternate pathways leading to airway eosinophilia will be described, and the efficacy of therapeutics that have been developed to block these pathways will be evaluated.

A Real-world Perspective of CD123 Expression in Acute Leukemia as Promising Biomarker to Predict Treatment Outcome in B-ALL and AML

INTRODUCTION

CD123 is overexpressed in many hematologic malignancies and found to be useful in characterizing leukemic blasts of both acute myeloid leukemia (AML) and B-acute lymphoblastic leukemia (B-ALL). CD123 has been recently found to be a marker of leukemic stem cells, and its utility to measure residual disease and potential role in disease relapse is under evaluation.

MATERIALS AND METHODS

Herein, we have evaluated the expression of CD123 in 757 samples of acute leukemia including 479 treatment-naive and 278 follow-up samples and compared with post-induction morphologic complete remission and measurable residual disease (MRD) status. Multiparametric flow cytometry was used for assessment of CD123 expression and immunophenotypic characterization of leukemic blasts at diagnostic and MRD assessment time points.

RESULTS

Using variable cutoffs of 5%, 10%, and 20% to define a case as CD123-positive, expression of CD123 was observed in 75.6%, 66.2%, and 50% of AML and 88.6%, 81.8%, and 75% of B-ALL, respectively. Of 11 patients, 7 (63.63%) had mixed phenotype acute leukemia, but none of the 12 patients with T-acute lymphoblastic leukemia showed positivity for CD123. CD123 expression at diagnosis was associated with post-induction MRD-positive status in both B-ALL (P < .001) and AML (P = .001). We also evaluated the utility of CD123 as a leukemia-associated aberrant immunophenotype and found it to be useful in both patients with AML (baseline, 50.6%; follow-up, 53%) and B-ALL (baseline, 75%; follow-up, 73.07%).

CONCLUSIONS

In conclusion, CD123 may be considered as a cardinal marker for residual disease assessment and response evaluation in AML and B-ALL.

Assessment of faithful interleukin-3 production by novel bicistronic interleukin-3 reporter mice

Interleukin-3 (IL-3) is an important hematopoietic growth factor and immunregulatory cytokine. Although activated T helper cells represent a main source of IL-3, other cell types have been reported to express this cytokine. However, precise identification and quantification of the cells that produce IL-3 in vivo have not been performed. Therefore, we used a CRISPR/Cas approach to engineer mice containing a bicistronic mRNA linking a readily identifiable reporter, enhanced green fluorescent protein (ZsGreen1), to IL-3 expression. To characterize these novel reporter mice, we first examined ZsGreen1 expression by CD4 T cells subsets primed and activated in vitro. We found that activated Th1 cells expressed ∼4-fold higher levels of ZsGreen1 as compared to Th0 and Th2 cells. Endogenous IL-3 expression remained intact although reporter Th1 cells secreted ∼33 % less IL-3 than similarly activated wild-type cells. To characterize the ability of reporter mice to accurately mark IL-3-producing cells in vivo, we infected mice with Nippostrongylus brasiliensis. Low but significant numbers of ZsGreen1+ CD4 T cells were detected in the mesenteric lymph nodes and lung following both primary and secondary infection. No difference in basophil and intestinal mast cell numbers were observed between infected reporter and wild-type mice indicating that reporter mice secreted IL-3 levels in vivo that results in IL-3-driven biological activities which are indistinguishable from those observed in corresponding wild-type mice. These IL-3 reporter mice will be a valuable resource to investigate IL-3-dependent immune responses in vivo.

Eosinophil diversity in asthma

Eosinophils are a type of granulated innate immune cells that have long been implicated in a specific type of asthma, referred to as eosinophilic asthma. Several immunotherapeutics that target and deplete eosinophils or limit their numbers are currently widely used and provide improved disease outcome in severe eosinophilic asthma. Current clinical results provide conclusive evidence of a generally detrimental role of eosinophils in asthma. Yet, a small but growing body of reports suggests that eosinophils may be more diverse than currently appreciated. In this review, we explore pre-clinical and clinical evidence that suggests the existence of eosinophil subsets with potentially distinct functional roles in asthma. We conclude by discussing state-of-the-art strategies for deciphering heterogeneity of this complex cell type, and argue this knowledge could translate into the improved personalized treatment of severe eosinophilic asthma.

Innate and secondary humoral responses are improved by increasing the time between MVA vaccine immunizations

Comprehending the mechanisms behind the impact of vaccine regimens on immunity is critical for improving vaccines. Indeed, the time-interval between immunizations may influence B and T cells, as well as innate responses. We compared two vaccine schedules using cynomolgus macaques immunized with an attenuated vaccinia virus. Two subcutaneous injections 2 weeks apart led to an impaired secondary antibody response and similar innate myeloid responses to both immunizations. In contrast, a delayed boost (2 months) improved the quality of the antibody response and involved more activated/mature innate cells, induced late after the prime and responding to the recall. The magnitude and quality of the secondary antibody response correlated with the abundance of these neutrophils, monocytes, and dendritic cells that were modified phenotypically and enriched prior to revaccination at 2 months, but not 2 weeks. These late phenotypic modifications were associated with an enhanced ex vivo cytokine production (including IL-12/23 and IL-1β) by PBMCs short after the second immunization, linking phenotype and functions. This integrated analysis reveals a deep impact of the timing between immunizations, and highlights the importance of early but also late innate responses involving phenotypical changes, in shaping humoral immunity.

Cysteinyl leukotriene metabolism of human eosinophils in allergic disease

Eosinophils are multifaceted immune cells with diverse functions that enhance allergic inflammation. Cysteinyl leukotrienes (cys-LTs), mainly synthesized in eosinophils, are a class of inflammatory lipid mediators produced via multiple enzymatic reactions from arachidonic acid. Multiple clinical studies have reported dysregulated fatty acid metabolism in severe asthma and aspirin-exacerbated respiratory diseases. Therefore, understanding the mechanism responsible for this metabolic abnormality has attracted a lot of attention. In eosinophils, various stimuli (including cytokines, chemokines, and pathogen-derived factors) prime and/or induce leukotriene generation and secretion. Cell-cell interactions with component cells (endothelial cells, epithelial cells, fibroblasts) also enhance this machinery to augment allergic responses. Nasal polyp-derived eosinophils from patients with eosinophilic rhinosinusitis present a characteristic fatty acid metabolism with selectively higher production of leukotriene D₄. Interestingly, type 2 cytokines and microbiome components might be responsible for this metabolic change with altered enzyme expression. Here, we review the regulation of fatty acid metabolism, especially cys-LT metabolism, in human eosinophils toward allergic inflammatory status.

Dysregulated fatty acid metabolism in nasal polyp-derived eosinophils from patients with chronic rhinosinusitis

BACKGROUND

Eosinophils are multifunctional granulocytes capable of releasing various cytokines, chemokines, and lipid mediators. We previously reported dysregulated fatty acid metabolism in peripheral blood-derived eosinophils from patients with severe asthma. However, functional characteristics of eosinophils present in allergic inflammatory tissues remain largely uncharacterized.

METHODS

We established a method for isolating CD69^hi CCR3^low CXCR4^- siglec-8^int eosinophils from nasal polyps of patients with eosinophilic rhinosinusitis (NP-EOS). Multi-omics analysis including lipidomics, proteomics, and transcriptomics was performed to analyze NP-EOS as compared to peripheral blood-derived eosinophils from healthy subjects (PB-EOS).

RESULTS

Lipidomic analysis revealed impaired synthesis of prostaglandins and 15-lipoxygenase (15-LOX)-derived mediators, and selective upregulation of leukotriene D₄ production. Furthermore, proteomics and transcriptomics revealed changes in the expression of specific enzymes (GGT5, DPEP2, and 15-LOX) responsible for dysregulated lipid metabolism. Ingenuity pathway analysis indicated the importance of type 2 cytokines and pattern recognition receptor pathways. Stimulation of PB-EOS with eosinophil activators IL-5, GM-CSF, and agonists of TLR2 and NOD2 mimicked the observed changes in lipid metabolism.

CONCLUSION

Inflammatory tissue-derived eosinophils possess a specific phenotype with dysregulated fatty acid metabolism that may be targeted therapeutically to control eosinophilic inflammatory diseases.

IL-4 enhances survival of in vitro-differentiated mouse basophils through transcription-independent signaling downstream of PI3K

Interleukin 4 (IL-4) is a critical cytokine implicated with T_H2 immune reactions, which are linked to pathologic conditions of allergic diseases. In that context, the initiation of T_H2 responses can critically depend on early basophil-derived IL-4 to activate T-cell responses, which then amplify IL-4 secretion. As a pleiotropic cytokine, IL-4 acts on a broad variety of hematopoietic and non-hematopoietic cells. However, the effect of IL-4 on basophils themselves, which are emerging as relevant players in allergic as well as autoimmune diseases, was only scarcely addressed so far. Here we used in vitro-differentiated mouse basophils to investigate the direct effects of IL-4 on cellular viability and surface expression of the high-affinity receptor for IgE, FcεRI. We observed that IL-4 elicits pronounced pro-survival signaling in basophils, delaying spontaneous apoptosis in vitro to a degree comparable to the known pro-survival effects of IL-3. Our data indicate that IL-4-mediated survival depends on PI3K/AKT signaling and—in contrast to IL-3—seems to be largely independent of transcriptional changes but effectuated by post-translational mechanisms affecting BCL-2 family members among others. Additionally, we found that IL-4 signaling has a stabilizing effect on the surface expression levels of the critical basophil activation receptor FcεRI. In summary, our findings indicate an important regulatory role of IL-4 on in vitro-differentiated mouse basophils enhancing their survival and stabilizing FcεRI receptor expression through PI3K-dependent signaling. A better understanding of the regulation of basophil survival will help to define promising targets and consequently treatment strategies in basophil-driven diseases.

Telfairia occidentalis Hook.f. - associated haematopoietic effect is mediated by cytokines but independent of testosterone: A preliminary report

ETHNOPHARMACOLOGICAL RELEVANCE

Telfairia occidentalis Hook.f. (TO) is popular in Nigeria for the ethnopharmacological use of its leaves to improve haematological parameters in normal and anaemic subjects. Cytokines are well-known to regulate haematopoiesis. However, their involvement in TO-associated haematopoietic effect is not known and necessitated this study.

MATERIALS AND METHODS

Twenty-five (25) male rats were randomly divided into 3 oral treatment groups as follows: Group 1 (control, n=5) received 0.2 ml/kg normal saline for 14 days. Groups 2 and 3 (n= 10 each) were subdivided into 2 (n=5) and received 100 mg/kg and 200 mg/kg of aqueous extract of TO respectively for 7 or 14 days.

RESULTS

TO had dose- and duration-dependent effects on the estimated parameters. Both doses of TO increased the RBC, WBC and erythropoietin concentrations at 14 but not 7 days. Moreover, its 100 mg/kg increased haemoglobin, neutrophil, and interleukin-3 concentrations at 7 days, while 200 mg/kg increased PCV and neutrophils at 14 days, lymphocytes at 7 days, and haemoglobin at both durations.

CONCLUSION

The haematopoietic effect of TO might be partly mediated by cytokines (interleukin-3 and erythropoietin) but independent of testosterone.

Modeling TH 2 responses and airway inflammation to understand fundamental mechanisms regulating the pathogenesis of asthma

In this review, we highlight experiments conducted in our laboratories that have elucidated functional roles for CD4⁺ T-helper type-2 lymphocytes (T_H 2 cells), their associated cytokines, and eosinophils in the regulation of hallmark features of allergic asthma. Notably, we consider the complexity of type-2 responses and studies that have explored integrated signaling among classical T_H 2 cytokines (IL-4, IL-5, and IL-13), which together with CCL11 (eotaxin-1) regulate critical aspects of eosinophil recruitment, allergic inflammation, and airway hyper-responsiveness (AHR). Among our most important findings, we have provided evidence that the initiation of T_H 2 responses is regulated by airway epithelial cell-derived factors, including TRAIL and MID1, which promote T_H 2 cell development via STAT6-dependent pathways. Further, we highlight studies demonstrating that microRNAs are key regulators of allergic inflammation and potential targets for anti-inflammatory therapy. On the background of T_H 2 inflammation, we have demonstrated that innate immune cells (notably, airway macrophages) play essential roles in the generation of steroid-resistant inflammation and AHR secondary to allergen- and pathogen-induced exacerbations. Our work clearly indicates that understanding the diversity and spatiotemporal role of the inflammatory response and its interactions with resident airway cells is critical to advancing knowledge on asthma pathogenesis and the development of new therapeutic approaches.

Eosinophil Development, Disease Involvement, and Therapeutic Suppression

Human eosinophils have characteristic morphologic features, including a bilobed nucleus and cytoplasmic granules filled with cytotoxic and immunoregulatory proteins that are packaged in a specific manner. Eosinophil production in the bone marrow is exquisitely regulated by timely expression of a repertoire of transcription factors that work together via collaborative and hierarchical interactions to direct eosinophil development. In addition, proper granule formation, which occurs in a spatially organized manner, is an intrinsic checkpoint that must be passed for proper eosinophil production to occur. In eosinophil-associated disorders, eosinophils and their progenitors can be recruited in large numbers into tissues where they can induce proinflammatory organ damage in response to local signals. Eosinophils are terminally differentiated and do not proliferate once they leave the bone marrow. The cytokine IL-5 specifically enhances eosinophil production and, along with other mediators, promotes eosinophil activation. Indeed, eosinophil depletion with anti-IL-5 or anti-IL-5Rα is now proven to be clinically beneficial for several eosinophilic disorders, most notably severe asthma, and several therapeutics targeting eosinophil viability and production are now in development. Significant progress has been made in our understanding of eosinophil development and the consequences of tissue eosinophilia. Future research efforts focused on basic eosinophil immunobiology and translational efforts to assist in the diagnosis, treatment selection, and resolution of eosinophil-associated disorders will likely be informative and clinically helpful.

IL-3R-alpha blockade inhibits tumor endothelial cell-derived extracellular vesicle (EV)-mediated vessel formation by targeting the β-catenin pathway

The proangiogenic cytokine Interleukin-3 (IL-3) is released by inflammatory cells in breast and ovarian cancer tissue microenvironments and also acts as an autocrine factor for human breast and kidney tumor-derived endothelial cells (TECs). We have previously shown that IL-3-treated endothelial cells (ECs) release extracellular vesicles (EVs), which serve as a paracrine mechanism for neighboring ECs, by transferring active molecules. The impact of an anti-IL-3R-alpha blocking antibody on the proangiogenic effect of EVs released from TECs (anti-IL-3R-EVs) has therefore been investigated in this study. We have found that anti-IL-3R-EV treatment prevented neovessel formation and, more importantly, also induced the regression of in vivo TEC-derived neovessels. Two miRs that target the canonical wingless (Wnt)/β-catenin pathway, at different levels, were found to be differentially regulated when comparing the miR-cargo of naive TEC-derived EVs (EVs) and anti-IL-3R-EVs. miR-214-3p, which directly targets β-catenin, was found to be upregulated, whereas miR-24-3p, which targets adenomatous polyposis coli (APC) and glycogen synthase kinase-3β (GSK3β), was found to be downregulated. In fact, upon their transfer into the cell, low β-catenin content and high levels of the two members of the “β-catenin destruction complex” were detected. Moreover, c-myc downregulation was found in TECs treated with anti-IL-3R-EVs, pre-miR-214-3p-EVs and antago-miR-24-3p-EVs, which is consistent with network analyses of miR-214-3p and miR-24-3p gene targeting. Finally, in vivo studies have demonstrated the impaired growth of vessels in pre-miR-214-3p-EV- and antago-miR-24-3p-EV-treated animals. These effects became much more evident when combo treatment was applied. The results of the present study identify the canonical Wnt/β-catenin pathway as a relevant mechanism of TEC-derived EV proangiogenic action. Furthermore, we herein provide evidence that IL-3R blockade may yield some significant advantages, than miR targeting, in inhibiting the proangiogenic effects of naive TEC-derived EVs by changing TEC-EV-miR cargo.

Activated Stat5 trafficking Via Endothelial Cell-derived Extracellular Vesicles Controls IL-3 Pro-angiogenic Paracrine Action

Soluble factors and cell-derived extracellular vesicles (EVs) control vascular cell fate during inflammation. The present study investigates the impact of Interleukin 3 (IL-3) on EV release by endothelial cells (ECs), the mechanisms involved in EV release and paracrine actions. We found that IL-3 increases EV release, which is prevented by IL-3Ralpha blockade. EVs released upon IL-3 stimulation were able to induce pro-angiogenic signals as shown by chromatin immunoprecipitation (ChIP) assay performed on the promoter region of cyclin D1 and tridimensional tube-like structure formation. We herein demonstrate that these effects rely on the transfer of miR-126-3p, pre-miR-126 and, more importantly, of activated signal transduction and activator of transcription 5 (pSTAT5) from IL-3-EV cargo into recipient ECs. We show, using the dominant negative form (ΔN)STAT5 and an activated STAT5 (1*6STAT5) constructs, that STAT5 drives IL-3-mediated EV release, miR-126-3p and pSTAT5 content. Finally, using EVs recovered from ΔNSTAT5 expressing ECs, we provide evidence that miR-126-3p and pSTAT5 trafficking is relevant for IL-3-mediated paracrine pro-angiogenic signals. These results indicate that IL-3 regulates EC-EV release, cargo and IL-3 angiogenic paracrine action via STAT5. Moreover, these results provide evidence that EC-derived IL-3-EVs can serve as pro-angiogenic clinical delivery wound healing devices.

Eosinophil cytokines, chemokines, and growth factors: emerging roles in immunity

Eosinophils derive from the bone marrow and circulate at low levels in the blood in healthy individuals. These granulated cells preferentially leave the circulation and marginate to tissues, where they are implicated in the regulation of innate and adaptive immunity. In diseases such as allergic inflammation, eosinophil numbers escalate markedly in the blood and tissues where inflammatory foci are located. Eosinophils possess a range of immunomodulatory factors that are released upon cell activation, including over 35 cytokines, growth factors, and chemokines. Unlike T and B cells, eosinophils can rapidly release cytokines within minutes in response to stimulation. While some cytokines are stored as pre-formed mediators in crystalloid granules and secretory vesicles, eosinophils are also capable of undergoing de novo synthesis and secretion of these immunological factors. Some of the molecular mechanisms that coordinate the final steps of cytokine secretion are hypothesized to involve binding of membrane fusion complexes comprised of soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs). These intracellular receptors regulate the release of granules and vesicles containing a range of secreted proteins, among which are cytokines and chemokines. Emerging evidence from both human and animal model-based research has suggested an active participation of eosinophils in several physiological/pathological processes such as immunomodulation and tissue remodeling. The observed eosinophil effector functions in health and disease implicate eosinophil cytokine secretion as a fundamental immunoregulatory process. The focus of this review is to describe the cytokines, growth factors, and chemokines that are elaborated by eosinophils, and to illustrate some of the intracellular events leading to the release of eosinophil-derived cytokines.

The innate immune response

The innate immune response is of prime importance in the immediate recognition and elimination of invading micro-organisms. However, deregulation of this system is clearly associated with the pathogenesis of a wide range of inflammatory diseases. Innate immunity consists of a humoral and a cellular branch, which are closely interacting. An additional level of control is found at the level of neuronal reflexes that can fine-tune these immunological mechanisms.

Grasping nettles: cellular heterogeneity and other confounders in epigenome-wide association studies

Platform technologies for measurement of CpG methylation at multiple loci across the genome have made ambitious epigenome-wide association studies affordable and practicable. In contrast to genetic studies, which estimate the effects of structural changes in DNA, and transcriptomic studies, which measure genomic outputs, epigenetic studies can access states of regulation of genome function in particular cells and in response to specific stimuli. Although many factors complicate the interpretation of epigenetic variation in human disease, cell-specific methylation patterns and the cellular heterogeneity present in peripheral blood and tissue biopsies are anticipated to cause the most problems. In this review, we suggest that the difficulties may be exaggerated and we explore how cellular heterogeneity may be embraced with appropriate study designs and analytical tools. We further suggest that systematic mapping of the loci influenced by age, sex and genetic polymorphisms will bring important biological insights as well as improved control of epigenome-wide association studies.

CD4+ T cells enhance the unloaded shortening velocity of airway smooth muscle by altering the contractile protein expression

Abundant data indicate that pathogenesis in allergic airways disease is orchestrated by an aberrant T-helper 2 (Th2) inflammatory response. CD4(+) T cells have been localized to airway smooth muscle (ASM) in both human asthmatics and in rodent models of allergic airways disease, where they have been implicated in proliferative responses of ASM. Whether CD4(+) T cells also alter ASM contractility has not been addressed. We established an in vitro system to assess the ability of antigen-stimulated CD4(+) T cells to modify contractile responses of the Brown Norway rat trachealis muscle. Our data demonstrated that the unloaded velocity of shortening (Vmax) of ASM was significantly increased upon 24 h co-incubation with antigen-stimulated CD4(+) T cells, while stress did not change. Enhanced Vmax was dependent upon contact between the CD4(+) T cells and the ASM and correlated with increased levels of the fast (+)insert smooth muscle myosin heavy chain isoform. The levels of myosin light chain kinase and myosin light chain phosphorylation were also increased within the muscle. The alterations in mechanics and in the levels of contractile proteins were transient, both declining to control levels after 48 h of co-incubation. More permanent alterations in muscle phenotype might be attainable when several inflammatory cells and mediators interact together or after repeated antigenic challenges. Further studies will await new tissue culture methodologies that preserve the muscle properties over longer periods of time. In conclusion, our data suggest that inflammatory cells promote ASM hypercontractility in airway hyper-responsiveness and asthma.

Airway epithelial regulation of pulmonary immune homeostasis and inflammation

Recent genetic, structural and functional studies have identified the airway and lung epithelium as a key orchestrator of the immune response. Further, there is now strong evidence that epithelium dysfunction is involved in the development of inflammatory disorders of the lung. Here we review the characteristic immune responses that are orchestrated by the epithelium in response to diverse triggers such as pollutants, cigarette smoke, bacterial peptides, and viruses. We focus in part on the role of epithelium-derived interleukin (IL)-25, IL-33 and thymic stromal lymphopoietin (TSLP), as well as CC family chemokines as critical regulators of the immune response. We cite examples of the function of the epithelium in host defense and the role of epithelium dysfunction in the development of inflammatory diseases.

Interleukin-3-deficient mice have increased resistance to blood-stage malaria

The contribution of interleukin-3 (IL-3), a hematopoietic growth factor and immunoregulatory cytokine, to resistance to blood-stage malaria was investigated by infecting IL-3-deficient (knockout [KO]) mice with Plasmodium berghei NK65. Male IL-3 KO mice, but not female mice, were more resistant to infection than wild-type (WT) mice, as evidenced by lower peak parasitemia and prolonged survival. Both male and female IL-3 KO mice had increased splenomegaly and were more anemic than corresponding WT mice. Anemia was compensated for by an increase in bone marrow and splenic erythropoiesis in IL-3 KO mice, as evidenced by higher levels of erythroid progenitors. Plasma levels of gamma interferon (IFN-γ) and CXCL9 (monokine induced by IFN-γ [MIG]) were found to be significantly reduced in IL-3 KO mice during early stages of infection. In contrast, granulocyte colony-stimulating factor (G-CSF) levels were significantly higher, and the percentage of peripheral blood neutrophils lower, in infected IL-3 KO mice than in WT counterparts. Overall, our results indicate that IL-3 plays a critical role in suppressing protective immunity to P. berghei NK65 infection and that it is involved in inhibiting the development of splenomegaly, anemia, and erythropoiesis. IL-3 also influences IFN-γ, CXCL9, and G-CSF production in response to infection. The abnormal responses seen in infected IL-3 KO mice may be due to the lack of IL-3 during development, to the lack of IL-3 in the infected mature mice, or to both.

CD 123 is a membrane biomarker and a therapeutic target in hematologic malignancies

Recent studies indicate that abnormalities of the alpha-chain of the interleukin-3 receptor (IL-3RA or CD123) are frequently observed in some leukemic disorders and may contribute to the proliferative advantage of leukemic cells. This review analyzes the studies indicating that CD123 is overexpressed in various hematologic malignancies, including a part of acute myeloid and B-lymphoid leukemias, blastic plasmocytoid dendritic neoplasms (BPDCN) and hairy cell leukemia.Given the low/absent CD123 expression on normal hematopoietic stem cells, attempts have been made at preclinical first, and then at clinical level to target this receptor. Since the IL-3R is a membrane receptor there are two relatively simple means to target this molecule, either using its natural ligand or neutralizing monoclonal antibodies. Recent reports using a fusion molecule composed by human IL-3 coupled to a truncated diphteria toxin have shown promising antitumor activity in BPDCN and AML patients.

Biological studies on the effect of estrogen on experimentally induced asthma in mice

This study evaluates the influence of estrogen hormone on the experimentally induced asthma in male mice. The animals were divided into four groups, with 20 mice in each group; group I (control mice) included mice that received no treatment, group II included mice that received intraperitoneal estrogen injection (0.25 mg/kg body weight (bw), twice on day 28 of the experiment), group III (asthmatic mice) included asthmatic mice that received intraperitoneal injection of two doses of ovalbumin (OVA; 2 µg of OVA mixed with 100 µg of aluminum potassium sulfate) on days 1 and 14 of the experiment and then challenged intranasally with a single dose of OVA (50 µg dissolved in 0.05 ml phosphate-buffered saline; PBS) on day 28 of the experiment, and group IV (asthmatic mice treated with estrogen) included asthma model male mice that received the estrogen (0.5 mg/kg bw in 40 ml PBS, twice on the day 28 of the experiment). The immunohistochemical studies observed a marked intensity of CD15 immunoreactivity in the lung tissues of asthma model mice. Physiological results recorded that the total and differential count of leukocytes in bronchoalveolar lavage fluid (BALF) of asthma model mice recorded a significant increase in the number of leukocytes especially in the number of eosinophil cells. The BALF of asthma model mice showed high levels of interleukins 4 and 5 (IL-4 and IL-5), and there was a significant decrease in both the levels of IL-4 and IL-5 in BALF of asthma model mice treated with estrogen. In conclusion, the obtained results indicated that the asthma is responsible for certain immunohistochemical and physiological alterations induced in lung tissues of mice. The administration of estrogen to asthmatic male mice could improve these changes. For this reason, the present findings support the possible role of estrogen in modulating the inflammatory effects caused by asthma in male mice and may be helpful to cure many asthmatic progressions.

Living and dying for inflammation: neutrophils, eosinophils, basophils

Neutrophils, eosinophils, and basophils play essential roles during microbe-induced and sterile inflammation. The severity of such inflammatory processes is controlled, at least in part, by factors that regulate cell death and survival of granulocytes. In recent years, major progress has been made in understanding the molecular mechanisms of granulocyte cell death and in identifying novel damage- and pathogen-associated molecular patterns as well as regulatory cytokines impacting granulocyte viability. Furthermore, an increased interest in innate immunity has boosted our overall understanding of granulocyte biology. In this review, we describe and compare factors and mechanisms regulating neutrophil, eosinophil, and basophil lifespan. Because dysregulation of death pathways in granulocytes can contribute to inflammation-associated immunopathology, targeting granulocyte lifespan could be therapeutically promising.

The GM-CSF/IL-3/IL-5 cytokine receptor family: from ligand recognition to initiation of signaling

Granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 are members of a discrete family of cytokines that regulates the growth, differentiation, migration and effector function activities of many hematopoietic cells and immunocytes. These cytokines are involved in normal responses to infectious agents, bridging innate and adaptive immunity. However, in certain cases, the overexpression of these cytokines or their receptors can lead to excessive or aberrant initiation of signaling resulting in pathological conditions, with chronic inflammatory diseases and myeloid leukemias the most notable examples. Recent crystal structures of the GM-CSF receptor ternary complex and the IL-5 binary complex have revealed new paradigms of cytokine receptor activation. Together with a wealth of associated structure-function studies, they have significantly enhanced our understanding of how these receptors recognize cytokines and initiate signals across cell membranes. Importantly, these structures provide opportunities for structure-based approaches for the discovery of novel and disease-specific therapeutics. In addition, recent biochemical evidence has suggested that the GM-CSF/IL-3/IL-5 receptor family is capable of interacting productively with other membrane proteins at the cell surface. Such interactions may afford additional or unique biological activities and might be harnessed for selective modulation of the function of these receptors in disease.

Apoptosis and inflammation

During the last few decades it has been recognized that cell death is not the consequence of accidental injury, but is the expression of a cell suicide programme. Kerr et al. (1972) introduced the term apoptosis. This form of cell death is under the influence of hormones, growth factors and cytokines, which depending upon the receptors present on the target cells, may activate a genetically controlled cell elimination process. During apoptosis the cell membrane remains intact and the cell breaks into apoptotic bodies, which are phagocytosed. Apoptosis, in contrast to necrosis, is not harmful to the host and does not induce any inflammatory reaction. The principal event that leads to inflammatory disease is cell damage, induced by chemical/physical injury, anoxia or starvation. Cell damage means leakage of cell contents into the adjacent tissues, resulting in the capillary transmigration of granulocytes to the injured tissue. The accumulation of neutrophils and release of enzymes and oxygen radicals enhances the inflammatory reaction. Until now there has been little research into the factors controlling the accumulation and the tissue load of granulocytes and their histotoxic products in inflammatory processes. Neutrophil apoptosis may represent an important event in the control of intlamtnation. It has been assumed that granulocytes disintegrate to apoptotic bodies before their fragments are removed by local macrophages. Removal of neutrophils from the inflammatory site without release of granule contents is of paramount importance for cessation of inflammation. In conclusion, apoptotic cell death plays an important role in inflammatory processes and in the resolution of inflammatory reactions. The facts known at present should stimulate further research into the role of neutrophil, eosinophil and macrophage apoptosis in inflammatory diseases.

IL-3 and TNFα increase Thymic Stromal Lymphopoietin Receptor (TSLPR) expression on eosinophils and enhance TSLP-stimulated degranulation

BACKGROUND

Thymic stromal lymphopoietin (TSLP) and eosinophils are prominent components of allergic inflammation. Therefore, we sought to determine whether TSLP could activate eosinophils, focusing on measuring the regulation of TSLPR expression on eosinophils and degranulation in response to TSLP, as well as other eosinophil activation responses.

METHODS

Eosinophil mRNA expression of TSLPR and IL-7Rα was examined by real-time quantitative PCR of human eosinophils treated with TNFα and IL-5 family cytokines, and TSLPR surface expression on eosinophils was analyzed by flow cytometry. Eosinophils were stimulated with TSLP (with and without pre-activation with TNFα and IL-3) and evaluated for release of eosinophil derived neurotoxin (EDN), phosphorylation of STAT5, and survival by trypan blue exclusion. A blocking antibody for TSLPR was used to confirm the specificity of TSLP mediated signaling on eosinophil degranulation.

RESULTS

Eosinophil expression of cell surface TSLPR and TSLPR mRNA was upregulated by stimulation with TNFα and IL-3. TSLP stimulation resulted in release of EDN, phosphorylation of STAT5 as well as promotion of viability and survival. TSLP-stimulated eosinophil degranulation was inhibited by a functional blocking antibody to TSLPR. Pre-activation of eosinophils with TNFα and IL-3 promoted eosinophil degranulation at lower concentrations of TSLP stimulation.

CONCLUSIONS

This study demonstrates that eosinophils are activated by TSLP and that eosinophil degranulation in response to TSLP may be enhanced on exposure to cytokines present in allergic inflammation, indicating that the eosinophil has the capacity to participate in TSLP-driven allergic responses.

Eosinophils and disease pathogenesis

Eosinophils are granulocytic innate immune cells whose presence is conspicuous in a variety of disease states, including eosinophilic hyperproliferative and infiltrative processes, as well as conditions associated with maladaptive Th2 inflammation. This review discusses the role of eosinophils in disease pathogenesis, including a consideration of relevant eosinophil biology. Eosinophilic disease patterns of tissue infiltration are also detailed, as are candidate mechanisms by which eosinophils cause fibrosis and hypercoagulability and the importance of eosinophils in allergic inflammation. Eosinophils are unique cells in their spectrum of associated disease, with the promise of future discoveries in delineating the manner in which they contribute to disease pathogenesis.

Biomarkers of eosinophil involvement in allergic and eosinophilic diseases: review of phenotypic and serum markers including a novel assay to quantify levels of soluble Siglec-8

There remains considerable controversy in the management of eosinophilic disorders, mainly due to a paucity of information regarding the clinical interpretation of total blood eosinophil counts versus surface activation markers versus eosinophil-derived or eosinophil-influencing mediator levels. Regrettably, few tests have been validated that define a unique clinical or prognostic phenotype that is more useful than simply monitoring total blood eosinophil counts. In this manuscript, phenotypic (cell surface) markers, along with serum and tissue-based markers that have been examined in the context of disease activity, are reviewed. We also report the development of a novel assay for detecting soluble Siglec-8 (sSiglec-8), a protein likely derived largely from eosinophils, as a potential serum biomarker. The assay consists of a competitive ELISA using a recombinant Siglec-8-Fc fusion protein. The goal of this preliminary study was to determine if sSiglec-8 is a useful biomarker that differentiates among patients with various eosinophil-associated diseases. In the final analysis, it is fair to say that further research is sorely needed to fully understand and validate the utility of various biomarkers, including sSiglec-8, before their use in clinical practice can be recommended with confidence.

The GM-CSF receptor family: mechanism of activation and implications for disease

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a pluripotent cytokine produced by many cells in the body, which regulates normal and malignant hemopoiesis as well as innate and adaptive immunity. GM-CSF assembles and activates its heterodimeric receptor complex on the surface of myeloid cells, initiating multiple signaling pathways that control key functions such as cell survival, cell proliferation, and functional activation. Understanding the molecular composition of these pathways, the interaction of the various components as well as the kinetics and dose-dependent mechanics of receptor activation provides valuable insights into the function of GM-CSF as well as the related cytokines, interleukin-3 and interleukin-5. This knowledge provides opportunities for the development of new therapies to block the action of these cytokines in hematological malignancy and chronic inflammation.

Cloning and sequencing of Indian water buffalo (Bubalus bubalis) interleukin-3 cDNA

Full-length cDNA (435 bp) of the interleukin-3(IL-3) gene of the Indian water buffalo was amplified by reverse transcriptase-polymerase chain reaction and sequenced. This sequence had 96% nucleotide identity and 92% amino acid identity with bovine IL-3. There are 10 amino acid substitutions in buffalo compared with that of bovine. The amino acid sequence of buffalo IL-3 also showed very high identity with that of other ruminants, indicating functional cross-reactivity. Structural homology modelling of buffalo IL-3 protein with human IL-3 showed the presence of five helical structures.

Eosinophils: multifaceted biological properties and roles in health and disease

Eosinophils are leukocytes resident in mucosal tissues. During T-helper 2 (Th2)-type inflammation, eosinophils are recruited from bone marrow and blood to the sites of immune response. While eosinophils have been considered end-stage cells involved in host protection against parasite infection and immunopathology in hypersensitivity disease, recent studies changed this perspective. Eosinophils are now considered multifunctional leukocytes involved in tissue homeostasis, modulation of adaptive immune responses, and innate immunity to certain microbes. Eosinophils are capable of producing immunoregulatory cytokines and are actively involved in regulation of Th2-type immune responses. However, such new information does not preclude earlier observations showing that eosinophils, in particular human eosinophils, are also effector cells with proinflammatory and destructive capabilities. Eosinophils with activation phenotypes are observed in biological specimens from patients with disease, and deposition of eosinophil products is readily seen in the affected tissues from these patients. Therefore, it would be reasonable to consider the eosinophil a multifaceted leukocyte that contributes to various physiological and pathological processes depending on their location and activation status. This review summarizes the emerging concept of the multifaceted immunobiology of eosinophils and discusses the roles of eosinophils in health and disease and the challenges and perspectives in the field.

Treatment of allergic asthma: modulation of Th2 cells and their responses

Atopic asthma is a chronic inflammatory pulmonary disease characterised by recurrent episodes of wheezy, laboured breathing with an underlying Th2 cell-mediated inflammatory response in the airways. It is currently treated and, more or less, controlled depending on severity, with bronchodilators e.g. long-acting beta agonists and long-acting muscarinic antagonists or anti-inflammatory drugs such as corticosteroids (inhaled or oral), leukotriene modifiers, theophyline and anti-IgE therapy. Unfortunately, none of these treatments are curative and some asthmatic patients do not respond to intense anti-inflammatory therapies. Additionally, the use of long-term oral steroids has many undesired side effects. For this reason, novel and more effective drugs are needed. In this review, we focus on the CD4+ Th2 cells and their products as targets for the development of new drugs to add to the current armamentarium as adjuncts or as potential stand-alone treatments for allergic asthma. We argue that in early disease, the reduction or elimination of allergen-specific Th2 cells will reduce the consequences of repeated allergic inflammatory responses such as lung remodelling without causing generalised immunosuppression.

Effects of respiratory syncytial virus infection and major basic protein derived from eosinophils in pulmonary alveolar epithelial cells (A549)

RSV (respiratory syncytial virus)-induced pneumonia and bronchiolitis may be associated with hyperresponsive conditions, including asthma. Eosinophilic proteins such as MBP (major basic protein) may also be associated with the pathophysiology of asthma. To elucidate the roles of RSV infection and MBP in the pathogenesis of pneumonia with hyperresponsiveness, we investigated the effects of RSV infection and MBP on A549 (alveolar epithelial) cells. CPE (cytopathic effects) in A549 cells were observed by microscopy. Apoptosis and cell death was evaluated by flow cytometric analysis and modified MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. We also measured 15 types of cytokines and chemokines in A549 cell supernatants. Although RSV alone did not affect the CPE of A549, high concentrations of MBP resulted in cell death within 24 h. Combinations of RSV and MBP synergistically induced cell death. In A549 cells infected with RSV alone, the release of GM-CSF (granulocyte-macrophage colony-stimulating factor) was significantly enhanced compared with control cells (no infection). In the cells treated with MBP alone, the production of IL (interleukin)-2, 4, 5, 7, 10, 12, 13, 17, IFN (interferon)-γ, GM-CSF, G-CSF (granulocyte colony-stimulating factor) and MIP (macrophage inflammatory protein)-1β was significantly increased compared with control cells. Notably, the levels of GM-CSF and IL-17 in RSV/MBP-treated cells were significantly higher than those treated with MBP alone. These results suggest that MBP synergistically enhanced the release of various cytokines/chemokines and the cell death of RSV-infected A549 cells, indicating that MBP may be closely associated with the pathophysiology of allergic reactions in bronchiolitis/pneumonia due to RSV.

Eosinophils in innate immunity: an evolving story

Eosinophils are innate immune leukocytes found in relatively low numbers within the blood. Terminal effector functions of eosinophils, deriving from their capacity to release their content of tissue-destructive cationic proteins, have historically been considered primary effector mechanisms against specific parasites, and are likewise implicated in tissue damage accompanying allergic responses such as asthma. However, the past decade has seen dramatic advancements in the field of eosinophil immunobiology, revealing eosinophils to also be key participants in many other facets of innate immunity, from bridging innate and adaptive immune responses to orchestrating tissue remodeling events. Here, we review the multifaceted functions of eosinophils in innate immunity that are currently known, and discuss new avenues in this evolving story.

MEDI-563, a humanized anti-IL-5 receptor alpha mAb with enhanced antibody-dependent cell-mediated cytotoxicity function

BACKGROUND

Peripheral blood eosinophilia and lung mucosal eosinophil infiltration are hallmarks of bronchial asthma. IL-5 is a critical cytokine for eosinophil maturation, survival, and mobilization. Attempts to target eosinophils for the treatment of asthma by means of IL-5 neutralization have only resulted in partial removal of airway eosinophils, and this warrants the development of more effective interventions to further explore the role of eosinophils in the clinical expression of asthma.

OBJECTIVE

We sought to develop a novel humanized anti-IL-5 receptor alpha (IL-5Ralpha) mAb with enhanced effector function (MEDI-563) that potently depletes circulating and tissue-resident eosinophils and basophils for the treatment of asthma.

METHODS

We used surface plasmon resonance to determine the binding affinity of MEDI-563 to FcgammaRIIIa. Primary human eosinophils and basophils were used to demonstrate antibody-dependent cell-mediated cytotoxicity. The binding epitope of MEDI-563 on IL-5Ralpha was determined by using site-directed mutagenesis. The consequences of MEDI-563 administration on peripheral blood and bone marrow eosinophil depletion was investigated in nonhuman primates.

RESULTS

MEDI-563 binds to an epitope on IL-5Ralpha that is in close proximity to the IL-5 binding site, and it inhibits IL-5-mediated cell proliferation. MEDI-563 potently induces antibody-dependent cell-mediated cytotoxicity of both eosinophils (half-maximal effective concentration = 0.9 pmol/L) and basophils (half-maximal effective concentration = 0.5 pmol/L) in vitro. In nonhuman primates MEDI-563 depletes blood eosinophils and eosinophil precursors in the bone marrow.

CONCLUSIONS

MEDI-563 might provide a novel approach for the treatment of asthma through active antibody-dependent cell-mediated depletion of eosinophils and basophils rather than through passive removal of IL-5.

Impact of varicella-zoster virus on dendritic cell subsets in human skin during natural infection

Varicella-zoster virus (VZV) causes varicella and herpes zoster, diseases characterized by distinct cutaneous rashes. Dendritic cells (DC) are essential for inducing antiviral immune responses; however, the contribution of DC subsets to immune control during natural cutaneous VZV infection has not been investigated. Immunostaining showed that compared to normal skin, the proportion of cells expressing DC-SIGN (a dermal DC marker) or DC-LAMP and CD83 (mature DC markers) were not significantly altered in infected skin. In contrast, the frequency of Langerhans cells was significantly decreased in VZV-infected skin, whereas there was an influx of plasmacytoid DC, a potent secretor of type I interferon (IFN). Langerhans cells and plasmacytoid DC in infected skin were closely associated with VZV antigen-positive cells, and some Langerhans cells and plasmacytoid DC were VZV antigen positive. To extend these in vivo observations, both plasmacytoid DC (PDC) isolated from human blood and Langerhans cells derived from MUTZ-3 cells were shown to be permissive to VZV infection. In VZV-infected PDC cultures, significant induction of alpha IFN (IFN-alpha) did not occur, indicating the VZV inhibits the capacity of PDC to induce expression of this host defense cytokine. This study defines changes in the response of DC which occur during cutaneous VZV infection and implicates infection of DC subtypes in VZV pathogenesis.

Immunologic messenger molecules: cytokines, interferons, and chemokines

Cytokines and chemokines are secreted proteins involved in numerous aspects of cell growth, differentiation, and activation. A prominent feature of these molecules is their effect on the immune system with regard to cell trafficking and development of immune tissue and organs. The nature of an immune response determines which cytokines are produced and ultimately whether the response is cytotoxic, humoral, cell mediated, or allergic. For this chapter, cytokines are grouped according to those that are predominantly antigen-presenting cell or T lymphocyte derived; that mediate cytotoxic, humoral, cell mediated, and allergic immunity; or that are immunosuppressive. A discussion of chemokine function and their role in cell trafficking and disease follows.

Non-allergic Eosinophilic Inflammation

Much is known about the eosinophilic processes associated with antigens, tumors, and infection, yet data on other causes of eosinophilic inflammation are scarce. This paper investigates the locations and causes of other nonrespiratory eosinophilic inflammation. Although eosinophilic inflammation can involve locomotor, urinary, cardiovascular, nervous, gastrointestinal, and other mucosal surfaces, such inflammation also can accompany tissue trauma, foreign-body reactions, and necrotic or granulomatous processes. Despite their cytolytic/histolytic effects, eosinophil leukocytes are a component of tissue remodeling, can be antigen-presenting cells, and have a role in the reproductive system and in blood coagulation. The study of various types of eosinophilic inflammation may increase our understanding of the biological responses of eosinophil leukocytes to different inflammatory stimuli.

Targeting eosinophils in asthma

Recruitment of eosinophils has long been recognized as a hallmark of the inflammatory response in asthma. However, the functions of this population of cells in host defense remain poorly understood. Eosinophils play an important part in the inflammatory response and have key regulatory roles in the afferent arm of the immune response. More recently, eosinophils have been demonstrated to participate in host defense against respiratory viruses. The specific contributions of eosinophils to the pathophysiology of asthma remain controversial. However, the balance of evidence indicates that they have a significant role in the disease, suggesting that they may be appropriate targets for therapy. Towards this end, a novel intervention of considerable potential interest is the use of an antibody directed against the beta common chain of the receptor for interleukin-3, interleukin-5 and granulocyte-macrophage colony-stimulating factor. However, eliminating eosinophils may not be a risk-free therapeutic strategy, as there is potentially an increased likelihood of respiratory viral infections. This may predispose to the development of acute exacerbations of asthma, an outcome that would have significant clinical implications.

IL-3 induces a Pim1-dependent antiapoptotic pathway in primary human basophils

The contribution of basophils in allergic disease and other Th2-type immune responses depends on their persistence at sites of inflammation, but the ligands and molecular pathways supporting basophil survival are largely unknown. The comparison of rates of apoptosis and of the expression of antiapoptotic proteins in different human granulocyte types revealed that basophils have a considerably longer spontaneous life span than neutrophils and eosinophils consistent with high levels of constitutive Bcl-2 expression. Interleukin-3 (IL-3) is the only ligand that efficiently protects basophils from apoptosis as evidenced by screening a large number of stimuli. IL-3 up-regulates the expression of the antiapoptotic proteins cIAP2, Mcl-1, and Bcl-X(L) and induces a rapid and sustained de novo expression of the serine/threonine kinase Pim1 that closely correlates with cytokine-enhanced survival. Inhibitor studies and protein transduction of primary basophils using wild-type and kinase-dead Pim1-Tat fusion-proteins demonstrate the functional importance of Pim1 induction in the IL-3-enhanced survival. Our data further indicate that the antiapoptotic Pim1-mediated pathway operates independently of PI3-kinase but involves the activation of p38 MAPK. The induction of Pim1 leading to PI3-kinase-independent survival as described here for basophils may also be a relevant antiapoptotic mechanism in other terminally differentiated leukocyte types.

2007 E. Mead Johnson award: scientific pursuit of the allergy problem

My research has focused on elucidating the allergy problem over the past two decades. The primary approach has been to uncover critical mechanisms of allergic inflammation, with particular focus on eosinophils, a hallmark cellular constituent of allergic responses. Molecular processes that bridge T helper cell type 2 (TH2) immunity with eosinophilia and key checkpoints for regulating eosinophilia have been uncovered. Notably, interleukin (IL)-5 (derived from TH2 cells) has been identified as the chief hematopoietin responsible for eosinophil expansion in the circulation. Pathways for selective eosinophil mobilization from the blood stream to the tissue have been uncovered by defining the role of the eotaxin subfamily of chemokines in eosinophil chemoattraction and activation. Finally, TH2 cell derived IL-4 and IL-13 have been defined as chief inducers of the eotaxins, and upstream orchestrators of eosinophilic inflammation. These translational studies have formulated novel therapeutic strategies (currently being tested) for a variety of eosinophilic conditions, with particular attention on hypereosinophilic syndromes and eosinophil-associated gastrointestinal disorders such as eosinophilic esophagitis.

The effect of tributyltin on human eosinophilic [correction of eosinophylic] leukemia EoL-1 cells

Organotin compounds are chemicals that are widely used in industry and agriculture as plastic stabilizers, catalysts and biocides. Many of them, including tributyltin (TBT), have been detected in human food and, as a consequence, detectable levels have been found in human blood. As organotin compounds were shown to possess immunotoxic activity, we focused our attention on the effect of TBT on the basic determinants of the function of eosinophils, i.e. cell adhesiveness and motility. We used human eosinophylic leukemia EoL-1 cells, a common in vitro cellular model of human eosinophils. Here, we demonstrate that TBT causes a dose-dependent decrease in the viability of EoL-1 cells. When administered at sub-lethal concentrations, TBT significantly decreases the adhesion of EoL-1 cells to human fibroblasts (HSFs) and inhibits their migration on fibroblast surfaces. Since the basic function of eosinophils is to invade inflamed tissues, our results indicate that TBT, and possibly other organotin compounds, may affect major cellular properties involved in the determination of in vivo eosinophil function.

Apoptotic eosinophils in sputum from asthmatic patients correlate negatively with levels of IL-5 and eotaxin

BACKGROUND

Eosinophilic inflammation of the airways is a key characteristic of asthma. A defect in eosinophil apoptosis might contribute to the chronic tissue eosinophilia associated with asthma.

OBJECTIVE

Our purpose was to examine whether the occurrence of apoptotic eosinophils in induced sputum from asthmatic patients correlate with interleukin (IL)-5 and eotaxin.

METHODS

Thirty stable and 30 exacerbated asthmatic patients were recruited. Twenty healthy subjects were enrolled as a control group. Induced sputum was obtained from asthmatic patients and from control subjects. The number of apoptotic eosinophils in sputum was assessed by flow cytometry. In sputum supernatant, eosinophil cationic protein (ECP) was measured by sensitive radioimmunoassay, and IL-5 and eotaxin by sandwich enzyme linked immunosorbant assay.

RESULTS

Levels of eosinophils, apoptotic eosinophils, IL-5, ECP and eotaxin from asthmatic patients were higher than those from healthy subjects. Thirty exacerbated asthmatics showed higher proportions of eosinophils (median 29.3%, range 13.4%-40.9%), more detectable levels of IL-5 (50.44, 32.99-67.01 pg/ml) and eotaxin (644.6, 197.4-937.7 pg/ml) in their sputum than the patients with stable asthma (P<0.05). There were significant inverse correlations between the levels of sputum IL-5 and the proportion of sputum eosinophil apoptosis in patients with exacerbated and stable asthma (r=-0.85 and -0.79, P<0.01 and P<0.05, respectively). Also inverse correlations were found between the levels of eotaxin and the proportion of sputum eosinophil apoptosis in exacerbated (r=-0.85, P<0.01), or stable asthma (r=-0.69, P<0.05). Additional positive correlations between the levels of sputum IL-5 and eotaxin in either exacerbatated (r=0.93, P<0.01) or stable asthma (r=0.82, P<0.05) were observed.

CONCLUSIONS

Apoptosis of eosinophils might be suppressed by proinflammatory cytokines and chemokines such as IL-5 and eotaxin leading to their accumulation in the lung. Stimulation of eosinophils in airway with IL-5 and eotaxin may play a crucial role in allergic inflammation.

Inflammation and disease progression

Inflammation is a physiological response to a foreign organism such as bacteria, dust particles, and viruses. Recent studies have enlightened the role of inflammation in the progression of a variety of diseases such as cancer, atherosclerosis, asthma, and psoriasis. This article is a brief overview of the inflammatory processes involved in the progression of these common diseases. Knowledge about these mechanisms can shed light into development of newer therapeutic agents that are aimed at the eradication of these diseases.

Effects of two types of inactivity on the number of white blood cells in rats

Prolonged inactivity is known to induce changes in responses of many physiological defense systems such as the hypothalamo-hypophyseal-adrenocortical axis, the sympathetic nervous system, and immuno-responsive systems. However, effects of various types of inactivity on immuno-responsive systems are still unknown. Therefore, the effects of two types of inactivity (immobilization: IMM and whole body suspension: WBS) on the number of white blood cells were studied in rats. Rats were divided into the control group and each inactivity group to compare the number of total white blood cells, lymphocytes, monocyte, neutrophil, eosinophil, and basophil during the experimental periods. Both IMM and WBS were maintained for 11 days. IMM markedly increased the number of total white blood cells, monocyte, neutrophil, and eosinophil in the 1st to 10th day. However, the number of total white blood cells, monocyte, neutrophil, and eosinophil during the experiment of WBS were characterized by the presence of a lag phase followed by the significant increased actions. IMM did not change the number of basophil during the experimental period. However, WBS increased the number of basophil in the 1st to 8th day to 2.8-4.8 times, compared with the values of the control. Both IMM and WBS did not change the number of lymphocytes. From these results, WBS increases the number of natural immunity cells without changing acquired immunity cells, and there are different responses in the number of total white blood cells, monocyte, neutrophil, eosinophil, and basophil between IMM and WBS.