Eotaxin-1/CC chemokine ligand 11: a novel eosinophil survival factor secreted by human pulmonary artery endothelial cells

Persistent imbalance, anti-apoptotic, and anti-inflammatory signature of circulating C-C chemokines and cytokines in patients with paroxysmal nocturnal hemoglobinuria

OBJECTIVE

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal non-malignant disease in which hematopoietic cell apoptosis may play an important pathophysiological role. Previous studies of the content of phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) indicated the possibility of remote transmission of anti-apoptotic signals between pathological and normal hematopoietic progenitors.

METHODS

The study determined the plasma levels of beta chemokines and cytokines in N = 19 patients with PNH and 31 healthy controls. The research material was peripheral blood plasma (EDTA) stored at -80 °C until the test. Beta chemokine and cytokine concentrations were tested in duplicate with Bio-Plex Pro Human Cytokine Assay (Bio-Rad, Hercules, CA, USA) using a Luminex 200 flow cytometer and xPONENT software (Luminex Corporation, Austin, TX, USA). In peripheral blood CD34+ cells we tested the proportions of PI(3,4,5)P3+ and Annexin binding apoptotic phenotype using FC and phosflow.

RESULTS

Compared to the control group, the PNH group showed a significant increase in the plasma concentration of some beta chemokines and cytokines, including MIP-1alpha/CCL3, eotaxin/CCL11, MCP1/CCL2, IL4 and G-CSF. In the group of PNH patients, a significant decrease in the concentration of some cytokines was also observed: RANTES/CCL5, MIP-1beta/CCL4, PDGF-BB and IL9. At the same time, the plasma concentrations of the chemokine IP-10/CXCL10 and the cytokines IFN-gamma, TNF, IL6 and IL10 showed no significant deviations from the values for the control group. Anti-apoptotic phenotype and phosphatidylinositol (3,4,5)-trisphosphate content in PNH clone of CD34+ cells were associated with the level of CCL3 and negatively associated with CCL5, CCL4, PDGF-BB and IL9.

CONCLUSIONS

This data suggest the existence of apoptotic and PI(3,4,5)P3 imbalance in PNH CD34+ cells driven by anti-apoptotic cytokine biosignature in PNH. Plasma cytokines and intracellular enzymes that regulate the phosphoinositide pathways may become a therapeutic target in PNH.

The Intersection of IgE Autoantibodies and Eosinophilia in the Pathogenesis of Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by autoantibodies targeting cellular adhesion molecules. While IgE autoantibodies are occasionally reported in other autoimmune blistering diseases, BP is unique in that most BP patients develop an IgE autoantibody response. It is not known why BP patients develop self-reactive IgE and the precise role of IgE in BP pathogenesis is not fully understood. However, clinical evidence suggests an association between elevated IgE antibodies and eosinophilia in BP patients. Since eosinophils are multipotent effector cells, capable cytotoxicity and immune modulation, the putative interaction between IgE and eosinophils is a primary focus in current studies aimed at understanding the key components of disease pathogenesis. In this review, we provide an overview of BP pathogenesis, highlighting clinical and experimental evidence supporting central roles for IgE and eosinophils as independent mediators of disease and via their interaction. Additionally, therapeutics targeting IgE, the Th2 axis, or eosinophils are also discussed.

Modulation of blood inflammatory markers by benralizumab in patients with eosinophilic airway diseases

Background

Benralizumab, a humanized, afucosylated, monoclonal antibody that targets interleukin-5 receptor α, depletes eosinophils and basophils by enhanced antibody-dependent cell-mediated cytotoxicity. It demonstrated efficacy for patients with moderate to severe asthma and, in a Phase IIa trial, for chronic obstructive pulmonary disease (COPD) with eosinophilic inflammation. We investigated effects of benralizumab 100 mg every 8 weeks (first three doses every 4 weeks) subcutaneous on blood inflammatory markers through proteomic and gene-expression analyses collected during two Phase II studies of patients with eosinophilic asthma and eosinophilic COPD.

Methods

Serum samples for proteomic analysis and whole blood for gene expression analysis were collected at baseline and 52 weeks (asthma study) or 32 weeks (COPD study) post-treatment. Proteomic analyses were conducted on a custom set of 90 and 147 Rules-Based Medicine analytes for asthma and COPD, respectively. Gene expression was profiled by Affymetrix Human Genome U133 plus 2 arrays (~ 54 K probes). Gene set variation analysis (GSVA) was used to determine transcriptomic activity of immune signatures. Treatment-related differences between analytes, genes, and gene signatures were analyzed for the overall population and for patient subgroups stratified by baseline blood eosinophil count (eosinophil-high [≥300 cells/μL] and eosinophil-low [< 300 cells/μL]) via t-test and repeated measures analysis of variance.

Results

Eosinophil chemokines eotaxin-1 and eotaxin-2 were significantly upregulated (false discovery rate [FDR] < 0.05) by approximately 2.1- and 1.4-fold in the asthma study and by 2.3- and 1.7-fold in the COPD study following benralizumab treatment. Magnitude of upregulation of these two chemokines was greater for eosinophil-high patients than eosinophil-low patients in both studies. Benralizumab was associated with significant reductions (FDR < 0.05) in expression of genes associated with eosinophils and basophils, such as CLC, IL-5Rα, and PRSS33; immune-signaling complex genes (FCER1A); G-protein–coupled receptor genes (HRH4, ADORA3, P2RY14); and further immune-related genes (ALOX15 and OLIG2). The magnitude of downregulation of gene expression was greater for eosinophil-high than eosinophil-low patients. GSVA on immune signatures indicated significant treatment reductions (FDR < 0.05) in eosinophil-associated signatures.

Conclusions

Benralizumab is highly selective, modulating blood proteins or genes associated with eosinophils or basophils. Modulated protein and gene expression patterns are most prominently altered in eosinophil-high vs. eosinophil-low patients.

Trial registration

NCT01227278 and NCT01238861.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0968-8) contains supplementary material, which is available to authorized users.

Suppressed networks of inflammatory mediators characterize chronic venous insufficiency

OBJECTIVE

Chronic venous insufficiency (CVI) affects 25 million adults in the United States. Little emphasis has been placed on inflammatory changes associated with CVI. We hypothesize that in patients with early to mid-stage benign varicose vein disease, differences in circulating inflammatory mediators will be manifested in blood draining the involved area vs circulating blood in control subjects.

METHODS

Patients undergoing either endovenous ablation or sclerotherapy for Clinical, Etiology, Anatomy, and Pathophysiology clinical class 3 to 5 disease underwent phlebotomy from regional veins at the time of the procedure. The patient's age, gender, clinical class, duration of symptoms, presence of superficial truncal reflux by duplex ultrasound, and treatment modality were recorded. Plasma from patients and banked blood samples from healthy volunteers (HVs) were subjected to Luminex (EMD Millipore, Billerica, Mass) to evaluate the expression of an established panel of 20 inflammatory mediators. Mediator concentrations were compared between patients and HVs using Mann-Whitney U tests. Importantly, computational analysis allowed us to compare not only the panel of inflammatory mediators but also the inflammatory networks connecting these mediators to one another. Principal components were analyzed to assess network robustness in each group.

RESULTS

CVI venous blood revealed significantly lower levels of monokine induced by γ interferon, soluble interleukin (IL) 2 receptor α chain, IL-4, IL-6, IL-7, tumor necrosis factor α, eotaxin, and granulocyte-macrophage colony-stimulating factor than blood from controls. Inflammatory networks were significantly less complex and less robust in the CVI patients compared with HVs. Based on principal component analysis, responses among HVs were more varied than those of CVI patients.

CONCLUSIONS

We demonstrate that patients with CVI have significant differences not only in blood-borne inflammatory mediators but also in the interconnectedness of these mediators with one another and in their principal inflammatory characteristics. Results suggest hypoinflammation in chronic nonhealing changes in CVI. These novel findings, if validated in larger cohorts, may help predict the risk of disease progression or response to therapy in the future and may guide mechanistic studies on tissue responses to CVI.

Hypoxia causes IL-8 secretion, Charcot Leyden crystal formation, and suppression of corticosteroid-induced apoptosis in human eosinophils

BACKGROUND

Inflamed environments are typically hypercellular, rich in pro-inflammatory cytokines, and profoundly hypoxic. While the effects of hypoxia on neutrophil longevity and function have been widely studied, little is known about the consequences of this stimulus on eosinophils.

OBJECTIVE

We sought to investigate the effects of hypoxia on several key aspects of eosinophil biology, namely secretion, survival, and their sensitivity to glucocorticosteroids (GCS), agents that normally induce eosinophil apoptosis.

METHODS

Eosinophils derived from patients with asthma/atopy or healthy controls were incubated under normoxia and hypoxia, with or without glucocorticoids. Activation was measured by flow cytometry, ELISA of cultured supernatants, and F-actin staining; apoptosis and efferocytosis by morphology and flow cytometry; and GCS efficacy by apoptosis assays and qPCR.

RESULTS

Hypoxic incubation (3 kPa) caused (i) stabilization of HIF-2α and up-regulation of hypoxia-regulated genes including BNIP3 (BCL2/adenovirus E1B 19-kDa protein-interacting protein 3) and GLUT1 (glucose transporter 1); (ii) secretion of pre-formed IL-8, and Charcot Leyden crystal (CLC) formation, which was most evident in eosinophils derived from atopic and asthmatic donors; (iii) enhanced F-actin formation; (iv) marked prolongation of eosinophil lifespan (via a NF-κB and Class I PI3-kinase-dependent mechanism); and (v) complete abrogation of the normal pro-apoptotic effect of dexamethasone and fluticasone furoate. This latter effect was evident despite preservation of GCS-mediated gene transactivation under hypoxia.

CONCLUSION AND CLINICAL RELEVANCE

These data indicate that hypoxia promotes an eosinophil pro-inflammatory phenotype by enhancing eosinophil secretory function, delaying constitutive apoptosis, and importantly, antagonizing the normal pro-apoptotic effect of GCS. As eosinophils typically accumulate at sites that are relatively hypoxic, particularly during periods of inflammation, these findings may have important implications to understanding the behaviour of these cells in vivo.

TNFα drives pulmonary arterial hypertension by suppressing the BMP type-II receptor and altering NOTCH signalling

Heterozygous germ-line mutations in the bone morphogenetic protein type-II receptor (BMPR-II) gene underlie heritable pulmonary arterial hypertension (HPAH). Although inflammation promotes PAH, the mechanisms by which inflammation and BMPR-II dysfunction conspire to cause disease remain unknown. Here we identify that tumour necrosis factor-α (TNFα) selectively reduces BMPR-II transcription and mediates post-translational BMPR-II cleavage via the sheddases, ADAM10 and ADAM17 in pulmonary artery smooth muscle cells (PASMCs). TNFα-mediated suppression of BMPR-II subverts BMP signalling, leading to BMP6-mediated PASMC proliferation via preferential activation of an ALK2/ACTR-IIA signalling axis. Furthermore, TNFα, via SRC family kinases, increases pro-proliferative NOTCH2 signalling in HPAH PASMCs with reduced BMPR-II expression. We confirm this signalling switch in rodent models of PAH and demonstrate that anti-TNFα immunotherapy reverses disease progression, restoring normal BMP/NOTCH signalling. Collectively, these findings identify mechanisms by which BMP and TNFα signalling contribute to disease, and suggest a tractable approach for therapeutic intervention in PAH.

Reduced BMP receptor II signalling underlies pulmonary arterial hypertension (PAH). Here, Hurst et al. show that TNFα subverts BMP signalling by increasing BMP6 expression and signalling via an alternative BMP receptor, ALK2, in pulmonary artery smooth muscle cells to drive abnormal proliferation and PAH.

Severe asthma: anti-IgE or anti-IL-5?

Severe asthma is a discrete clinical entity characterised by recurrent exacerbations, reduced quality of life and poor asthma control as ordinary treatment regimens remain inadequate. Difficulty in managing severe asthma derives partly from the multiple existing phenotypes and our inability to recognise them. Though the exact pathogenetic pathway of severe allergic asthma remains unclear, it is known that numerous inflammatory cells and cytokines are involved, and eosinophils represent a key inflammatory cell mediator. Anti-IgE (omalizumab) and anti-IL-5 (mepolizumab) antibodies are biological agents that interfere in different steps of the Th2 inflammatory cascade and are licensed in severe asthma. Both exhibit a favourable clinical outcome as they reduce exacerbation rate and improve asthma control and quality of life, while mepolizumab also induces an oral steroid sparing effect. Nevertheless, it is still questionable which agent is more suitable in the management of severe allergic asthma since no comparable studies have been conducted. Omalizumab's established effectiveness in clinical practice over a long period is complemented by a beneficial effect on airway remodelling process mediated mainly through its impact on eosinophils and other parameters strongly related to eosinophilic inflammation. However, it is possible that mepolizumab through nearly depleting eosinophils could have a similar effect on airway remodelling. Moreover, to date, markers indicative of the patient population responding to each treatment are unavailable although baseline eosinophils and exacerbation rate in the previous year demonstrate a predictive value regarding anti-IL-5 therapy effectiveness. On the other hand, a better therapeutic response for omalizumab has been observed when low forced expiratory volume in 1 sec, high-dose inhaled corticosteroids and increased IgE concentrations are present. Consequently, conclusions are not yet safe to be drawn based on existing knowledge, and additional research is necessary to unravel the remaining issues for the severe asthmatic population.

Phytochemical profiles and inhibitory effects of Tiger Milk mushroom (Lignosus rhinocerus) extract on ovalbumin-induced airway inflammation in a rodent model of asthma

Background

Lignosus rhinocerus (L. rhinocerus), which is known locally as Tiger Milk mushroom, is traditionally used in the treatment of asthma by indigenous communities in Malaysia. However, to date, its efficacy on asthma has not been confirmed by scientific studies and there is also sparse information available on its active constituents. In this study, the volatile constituent of L. rhinocerus hot water extract was investigated using gas chromatography mass spectrometry (GC-MS). The potential effects of L. rhinocerus extract for anti-asthmatic activity was further investigated on ovalbumin (OVA)-sensitized asthmatic Sprague Dawley rats.

Methods

Sequential extraction using five solvents (petroleum ether, diethyl ether, hexane, ethyl acetate and methanol) was conducted prior to GC-MS analysis. Male Sprague Dawley rats were divided into the following four groups of five animals each: 1) normal rats, 2) sensitization plus OVA-challenged rats 3) sensitization plus OVA-challenged with L. rhinocerus treatment and 4) sensitization plus OVA-challenged with dexamethasone treatment. The levels of immunoglobulin E (IgE) in the serum and T-helper 2 cytokines, including interleukin (IL)-4, IL-5 and IL-13, in bronchoalveolar lavage fluid (BALF), as well as eosinophil infiltration in the lungs, were investigated.

Results

GC-MS analysis revealed the presence of five main groups (alkane, fatty acids, benzene, phenol and dicarboxylic acid) with a total of 18 constituents. Linoleic acid (21.35 %), octadecane (11.82 %) and 2,3-dihydroxypropyl elaidate (10.47 %) were present in high amounts. The extract significantly ameliorated the increase in total IgE in serum and IL-4, IL-5 and IL-13 levels in BALF and also effectively suppressed eosinophils numbers in BALF while attenuating eosinophil infiltrations in the lungs.

Conclusion

L. rhinocerus hot water extract has the potential to be used as an alternative for the treatment of acute asthma.

Resveratrol and its metabolites modulate cytokine-mediated induction of eotaxin-1 in human pulmonary artery endothelial cells

Coronary heart disease (CHD) is a leading cause of death in many developed countries. Evidence has long implicated endothelial injury and inflammation as apical events in the pathogenesis of atherosclerosis, the primary cause of CHD. Numerous risk factors contribute to a damaged, inflamed endothelium. Conversely, cardioprotective agents targeting the dysfunctional endothelium have also been identified, notably from dietary sources. We have used cultured human pulmonary artery endothelial cells (HPAECs) to test the diet-mediated cardioprotective hypothesis. In this review, we summarize our recent findings on control of transcription and expression of inflammation biomarker eotaxin-1 in HPAECs exposed to single or combined proinflammatory cytokines interleukin-13 (IL-13) and tumor necrosis factor-α (TNF-α), and attenuation of the observed eotaxin-1 responses by prior or simultaneous treatment with resveratrol and its metabolites. Control of eotaxin-1 gene regulation may be considered an in vitro model to evaluate agents linking cardioprotection with endothelial cell damage and inflammation.

Association of inflammatory gene polymorphisms with ischemic stroke in a Chinese Han population

BACKGROUND

Inflammatory mechanisms are important in stroke risk, and genetic variations in components of the inflammatory response have been implicated as risk factors for stroke. We tested the inflammatory gene polymorphisms and their association with ischemic stroke in a Chinese Han population.

METHODS

A total of 1,124 ischemic stroke cases and 1,163 controls were genotyped with inflammatory panel strips containing 51 selected inflammatory gene polymorphisms from 35 candidate genes. We tested the genotype-stroke association with logistic regression model.

RESULTS

We found two single nucleotide polymorphisms (SNPs) in CCL11 were associated with ischemic stroke. After adjusting for multiple testing using false discovery rate (FDR) with a 0.20 cut-off point, CCL11 rs4795895 remained statistically significant. We further stratified the study population by their hypertension status. In the hypertensive group, CCR2 rs1799864, CCR5 rs1799987 and CCL11 rs4795895 were nominally associated with increased risk of stroke. In the non-hypertensive group, CCL11 rs3744508, LTC4S rs730012, FCER1B rs569108, TGFB1 rs1800469, LTA rs909253 and CCL11 rs4795895 were associated with ischemic stroke. After correction for multiple testing, CCR2 rs1799864 and CCR5 rs1799987 remained significant in the hypertensive group, and CCL11 rs3744508, LTC4S rs730012, FCER1B rs569108, TGFB1 rs1800469, LTA rs909253 remained significant in the non-hypertensive group.

CONCLUSIONS

Our results indicate that inflammatory genetic variants are associated with increased risk of ischemic stroke in a Chinese Han population, particularly in non-hypertensive individuals.

CCL11-CCR3 interactions promote survival of anaplastic large cell lymphoma cells via ERK1/2 activation

CCR3 is a specific marker of anaplastic large cell lymphoma (ALCL) cells. ALCL cells also express CCL11, a ligand for CCR3, leading to the hypothesis that CCL11 may play an autocrine role in ALCL progression. In this study, we investigated a role of CCL11 in cell survival and growth of human Ki-JK cells, established from an ALCL patient, and murine EL-4 lymphoma cells. Both Ki-JK and EL-4 cells expressed cell surface CCR3. CCL11 increased cell survival rates of Ki-JK cells in a dose-dependent manner, whereas it promoted EL-4 cell proliferation. Furthermore, CCL11 induced phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 in both Ki-JK cells and EL-4 cells. Cell survival and tumor proliferation promoted by CCL11 was completely blocked by inhibition of ERK phosphorylation. CCL11 induced expression of antiapoptotic proteins, Bcl-xL and survivin, in Ki-JK cells. CCL11 also enhanced tumor growth of EL-4 and Ki-JK cells in vivo. Consistent with these results, tumor cells of cutaneous ALCL expressed CCR3 and increased levels of phosphorylated ERK1/2, Bcl-xL, and survivin in situ. Thus, our findings prompt a novel therapeutic approach to treat relapses of an aggressive form of lymphoma based on the discovery that a cell surface marker of disease functions as a critical autocrine growth receptor.

Targeting CCL11 in the treatment of ovarian cancer

IMPORTANCE OF THE FIELD

The chemokine network, comprised of mediators of inflammation, has been implicated in the development of a number of human cancers. The eosinophil chemoattractant CCL11 was recently shown to play a role in the development of ovarian cancer. Here we review findings regarding CCL11 and discuss its use as a target in the treatment of ovarian cancer.

AREAS COVERED IN THIS REVIEW

We review published findings related to the physiological actions of CCL11, its tumourigenic effects, the chemokine network and inflammatory response present in ovarian cancer, and the current state of therapeutics targeting CCL11 and its receptors. Findings published within the last 10 years receive particular attention.

WHAT THE READER WILL GAIN

An overview of the emerging role of the chemokine network in malignancy and a review of the role of CCL11 in ovarian tumourigenesis. The reader will be presented with a description of the unique aspects of CCL11 action and the inflammatory environment in the setting of ovarian malignancy that make this chemokine an attractive target for intervention.

TAKE HOME MESSAGE

Targeting CCL11 and its receptors through the use of monoclonal antibodies and small-molecule inhibitors may represent a beneficial new avenue of ovarian cancer treatment.

Anti-inflammatory and anti-asthmatic effects of Viola mandshurica W. Becker (VM) ethanolic (EtOH) extract on airway inflammation in a mouse model of allergic asthma

AIM OF THE STUDY

We investigated the efficacy of Viola mandshurica W. Becker (VM) ethanolic (EtOH) extract in the treatment of bronchial asthma in an ovalbumin (OVA)-induced asthmatic BALB/c mouse model.

MATERIALS AND METHODS

Female BALB/c mice were sensitized with intraperitoneal (i.p.) ovalbumin (OVA) on days 0 and 14, and were next given intranasal OVA on days 28-30. Randomized treatment groups of sensitized mice received VM EtOH extract, dexamethasone, or placebo, orally, from days 28 to 30.

RESULTS

VM EtOH extract significantly inhibited increases in total immunoglobulin E (IgE) and cytokines IL-4 and IL-13 levels in serum and bronchoalveolar lavage fluid (BALF), and also effectively suppressed airway hyperresponsiveness (AHR), eosinophilia, and mucus hypersecretion, in mice with OVA-induced asthma.

CONCLUSIONS

The results suggest that VM EtOH extract and allied extracts could be useful herbal medicines for asthma treatment, and that VM may also be a valuable lead material for anti-asthma drug development.

Eotaxin increases monolayer permeability of human coronary artery endothelial cells

OBJECTIVE

The objective of this study was to determine the effects and molecular mechanisms of eotaxin, a newly discovered chemokine (CCL11), on endothelial permeability in the human coronary artery endothelial cells (HCAECs).

METHODS AND RESULTS

Cells were treated with eotaxin, and the monolayer permeability was studied by using a costar transwell system with a Texas Red-labeled dextran tracer. Eotaxin significantly increased monolayer permeability in a concentration-dependent manner. In addition, eotaxin treatment significantly decreased the mRNA and protein levels of endothelial junction molecules including zonula occludens-1 (ZO-1), occludin, and claudin-1 in a concentration-dependent manner as determined by real-time RT-PCR and Western blot analysis, respectively. Increased oxidative stress was observed in eotaxin-treated HCAECs by analysis of cellular glutathione levels. Furthermore, eotaxin treatment substantially activated the phosphorylation of MAPK p38. HCAECs expressed CCR3. Consequently, antioxidants (ginkgolide B and MnTBAP), specific p38 inhibitor SB203580, and anti-CCR3 antibody effectively blocked the eotaxin-induced permeability increase in HCAECs. Eotaxin also increased the phosphorylation of Stat3 and nuclear translocation of NF-kappaB in HCAECs.

CONCLUSIONS

Eotaxin increases vascular permeability through CCR3, the downregulation of tight junction proteins, increase of oxidative stress, and activation of MAPK p38, Stat3, and NF-kB pathways in HCAECs.

Francisella tularensis directly interacts with the endothelium and recruits neutrophils with a blunted inflammatory phenotype

Francisella tularensis, the causative agent of tularemia, is a highly virulent organism, especially when exposure occurs by inhalation. Recent data suggest that Francisella interacts directly with alveolar epithelial cells. Although F. tularensis causes septicemia and can live extracellularly in a murine infection model, there is little information about the role of the vascular endothelium in the host response. We hypothesized that F. tularensis would interact with pulmonary endothelial cells as a prerequisite to the clinically observed recruitment of neutrophils to the lung. Using an in vitro Transwell model system, we studied interactions between F. tularensis live vaccine strain (Ft LVS) and a pulmonary microvascular endothelial cell (PMVEC) monolayer. Organisms invaded the endothelium and were visualized within individual endothelial cells by confocal microscopy. Although these bacteria-endothelial cell interactions did not elicit production of the proinflammatory chemokines, polymorphonuclear leukocytes (PMN) were stimulated to transmigrate across the endothelium in response to Ft LVS. Moreover, transendothelial migration altered the phenotype of recruited PMN; i.e., the capacity of these PMN to activate NADPH oxidase and release elastase in response to subsequent stimulation was reduced compared with PMN that traversed PMVEC in response to Streptococcus pneumoniae. The blunting of PMN responsiveness required PMN transendothelial migration but did not require PMN uptake of Ft LVS, was not dependent on the presence of serum-derived factors, and was not reproduced by Ft LVS-conditioned medium. We speculate that the capacity of Ft LVS-stimulated PMVEC to support transendothelial migration of PMN without triggering release of IL-8 and monocyte chemotactic protein-1 and to suppress the responsiveness of transmigrated PMN to subsequent stimulation could contribute to the dramatic virulence during inhalational challenge with Francisella.

Short hairpin RNAs against eotaxin or interleukin-5 decrease airway eosinophilia and hyper-responsiveness in a murine model of asthma

BACKGROUND

Eosinophilia plays the major role in the pathogenesis of asthma and correlates with the up-regulation of eotaxin, which, together with interleukin (IL)-5, is important for differentiation, chemo-attraction, degranulation, and survival of eosinophils in local tissue. In a previous study, we found that administration of lentivirus-delivered short hairpin RNA (shRNA) to suppress the expression of IL-5 inhibited airway inflammation. The present study aimed to investigate the role of eotaxin shRNA and the synergistic effect of eotaxin and IL-5 shRNAs on airway inflammation in an ovalbumin (OVA)-induced murine model of asthma.

METHODS

Lentivirus-delivered shRNAs were used to suppress the expression of eotaxin and/or IL-5 in local tissue in an OVA-induced murine asthma model.

RESULTS

Intra-tracheal administration of lentivirus containing eotaxin shRNA expressing cassette (eoSEC3.3) efficiently moderated the characteristics of asthma, including airway hyper-responsiveness, cellular infiltration of lung tissues, and eotaxin and IL-5 levels in bronchio-alveolar lavage fluid. Administration of lentiviruses expressing IL-5 or eotaxin shRNAs (IL5SEC4 + eoSEC3.3) also moderated the symptoms of asthma in a mouse model.

CONCLUSIONS

Local delivery of lentiviruses expressing IL-5 and eotaxin shRNAs provides a potential tool in moderating airway inflammation and also has the potential for developing clinical therapy based on the application of shRNAs of chemokines and cytokines involved in T helper 2 cell inflammation and eosinophilia.

Macrophage migration inhibitory factor is critical to interleukin-5-driven eosinophilopoiesis and tissue eosinophilia triggered by Schistosoma mansoni infection

Macrophage migration inhibitory factor (MIF) participates in the pathogenesis of inflammatory diseases, including asthma, in which it enhances airway hypersensitivity and tissue eosinophilia. Herein, we investigated the role of MIF in eosinophilopoiesis and tissue eosinophilia using Schistosoma mansoni infection. MIF-deficient (Mif(-/-)) mice had similar numbers of adult worms, eggs, and granulomas compared to wild-type mice, but the size of granulomas was strikingly reduced due to smaller numbers of eosinophils. MIF did not affect the acquired response to infection, as Mif(-/-) mice produced normal amounts of Th2 cytokines and IgE. Nevertheless, recombinant MIF (rMIF) behaved as a chemoattractant for eosinophils, what could partially explain the reduced eosinophilia in infected Mif(-/-) mice. Moreover, the percentage of eosinophils was reduced in bone marrows of Mif(-/-) mice chronically infected with S. mansoni compared to wild type. Mif(-/-) had impaired eosinophilopoiesis in response to interleukin (IL)-5 and addition of rMIF to bone marrow cultures from IL-5 transgenic mice enhanced the generation of eosinophils. In the absence of MIF, eosinophil precursors were unable to survive the IL-5-supplemented cell culture, and were ingested by macrophages. Treatment with pancaspase inhibitor z-VAD or rMIF promoted the survival of eosinophil progenitors. Together, these results indicate that MIF participates in IL-5-driven maturation of eosinophils and in tissue eosinophilia associated with S. mansoni infection.

Eosinophil progenitors in allergy and asthma - do they matter?

Allergic inflammation is associated with marked infiltration of eosinophils in affected tissues. The eosinophil is believed to be a key effector cells in allergen induced asthma pathogenesis. However, the role of eosinophils in the clinical manifestation of asthma has recently been questioned, since therapies directed against eosinophil infiltration (i.e. anti-interleukin-5) failed to improve clinical symptoms such as airways hyper-responsiveness (AHR) in patients with asthma. Although eosinophils in peripheral blood and the airways were largely depleted after anti-IL-5 treatment, residual eosinophilia in lung tissue persisted, which permits speculation that the remaining eosinophils may be sufficient to drive the asthma symptomatology. Furthermore, recent findings suggest that primitive eosinophil progenitor cells traffic from the bone marrow to sites of inflammation in response to allergen exposure. These progenitors may then differentiate in situ and thus provide an ongoing supply of mature pro-inflammatory cells and secretory mediators that augment the inflammatory response. In the present article, we will review the evidence for these findings, and discuss the rationale for targeting hematopoiesis and their migration pathways in the treatment of allergic diseases. Furthermore, this review will highlight the hypothesis that both IL-5- and CCR3-mediated signaling pathways may need to be targeted in order to control the inflammation and AHR associated with asthma.