The eosinophil and airway remodelling in asthma

Eosinophil-Epithelial Cell Interactions in Asthma

BACKGROUND

Eosinophils have numerous roles in type 2 inflammation depending on their activation states in the blood and airway or after encounter with inflammatory mediators. Airway epithelial cells have a sentinel role in the lung and, by instructing eosinophils, likely have a foundational role in asthma pathogenesis.

SUMMARY

In this review, we discuss various topics related to eosinophil-epithelial cell interactions in asthma, including the influence of eosinophils and eosinophil products, e.g., granule proteins, on epithelial cell function, expression, secretion, and plasticity; the effects of epithelial released factors, including oxylipins, cytokines, and other mediators on eosinophils, e.g., on their activation, expression, and survival; possible mechanisms of eosinophil-epithelial cell adhesion; and the role of intra-epithelial eosinophils in asthma.

KEY MESSAGES

We suggest that eosinophils and their products can have both injurious and beneficial effects on airway epithelial cells in asthma and that there are bidirectional interactions and signaling between eosinophils and airway epithelial cells in asthma.

Unraveling the Role of Epithelial Cells in the Development of Chronic Rhinosinusitis

The pathophysiology of CRS is multifactorial and complex yet needs to be completed. Recent evidence emphasizes the crucial part played by epithelial cells in the development of CRS. The epithelial cells act as physical barriers and play crucial roles in host defense, including initiating and shaping innate and adaptive immune responses. This review aims to present a comprehensive understanding of the significance of nasal epithelial cells in CRS. New research suggests that epithelial dysfunction plays a role in developing CRS through multiple mechanisms. This refers to issues with a weakened barrier function, disrupted mucociliary clearance, and irregular immune responses. When the epithelial barrier is compromised, it can lead to the passage of pathogens and allergens, triggering inflammation in the body. Furthermore, impaired mucociliary clearance can accumulate pathogens and secretions of inflammatory mediators, promoting chronic inflammation. Epithelial cells can release cytokines and chemokines, which attract and activate immune cells. This can result in an imbalanced immune response that continues to cause inflammation. The interaction between nasal epithelial cells and various immune cells leads to the production of cytokines and chemokines, which can either increase or decrease inflammation. By comprehending the role of epithelial cells in CRS, we can enhance our understanding of the disease's pathogenesis and explore new therapeutics.

New insights into the regulation of TGF‐β/Smad and MPK signaling pathway gene expressions by nasal allergen and methacholine challenge test in asthma

Background

Asthma is a heterogeneous chronic inflammatory disease of the bronchi, the course of which is significantly influenced by extrinsic factors (specific and non‐specific).

Methods

The aim of this study was to evaluate the effect of these factors represented by nasal allergen challenge (specific factors) and methacholine challenge test (non‐specific) on changes in mRNA expression of genes encoding the TGF‐β (TGF‐β1 and TGF‐β3)‒Smad (mitogen‐activated protein kinase 1/3 [MPK1/3], Smad1/3/6/7) signaling pathway in asthmatic patients.

Results

Seventy‐five subjects were included in the study, of whom 27 were applied an intranasal allergen provocation and 48 a methacholine provocation. There were 9 men and 18 women in the intranasal provocation group, and 17 men and 31 women in the methacholine test group. We found that both examined the types of challenges contributed to changes in the relative expression of genes of the TGF‐β (TGF‐β1 and TGF‐β3)‒Smad (MPK1/3, Smad1/3/6/7) signaling pathway in asthmatic patients. A decrease was noted for MAPK1, MAPK3, Smad3, Smad6, and Smad7 genes and an increase of up to 2.5 times for TGF‐β1 gene.

Conclusions

Our experiment allows us to conclude that the change in the mRNA expression of the TGF‐β1–MPK1/3 and Smad3/6/7 genes occurs after an intranasal allergen and bronchial methacholine challenge.

Biocomposite-based nanostructured delivery systems for treatment and control of inflammatory lung diseases

Diseases related to the lungs are among the most prevalent medical problems threatening human life. The treatment options and therapeutics available for these diseases are hindered by inadequate drug concentrations at pathological sites, a dearth of cell-specific targeting and different biological barriers in the alveoli or conducting airways. Nanostructured delivery systems for lung drug delivery have been significant in addressing these issues. The strategies used include surface engineering by altering the material structure or incorporation of specific ligands to reach prespecified targets. The unique characteristics of nanoparticles, such as controlled size and distribution, surface functional groups and therapeutic release triggering capabilities, are tailored to specific requirements to overcome the major therapeutic barriers in pulmonary diseases. In the present review, the authors intend to deliver significant up-to-date research in nanostructured therapies in inflammatory lung diseases with an emphasis on biocomposite-based nanoparticles.

The Kynurenine Pathway-New Linkage between Innate and Adaptive Immunity in Autoimmune Endocrinopathies

The kynurenine pathway (KP) is highly regulated in the immune system, where it promotes immunosuppression in response to infection or inflammation. Indoleamine 2,3-dioxygenase 1 (IDO1), the main enzyme of KP, has a broad spectrum of activity on immune cells regulation, controlling the balance between stimulation and suppression of the immune system at sites of local inflammation, relevant to a wide range of autoimmune and inflammatory diseases. Various autoimmune diseases, among them endocrinopathies, have been identified to date, but despite significant progress in their diagnosis and treatment, they are still associated with significant complications, morbidity, and mortality. The precise cellular and molecular mechanisms leading to the onset and development of autoimmune disease remain poorly clarified so far. In breaking of tolerance, the cells of the innate immunity provide a decisive microenvironment that regulates immune cells’ differentiation, leading to activation of adaptive immunity. The current review provided a comprehensive presentation of the known role of IDO1 and KP activation in the regulation of the innate and adaptive arms of the immune system. Significant attention has been paid to the immunoregulatory role of IDO1 in the most prevalent, organ-specific autoimmune endocrinopathies—type 1 diabetes mellitus (T1DM) and autoimmune thyroiditis.

Understanding the key issues in the treatment of uncontrolled persistent asthma with type 2 inflammation

Asthma is a complex respiratory disease that varies in severity and response to treatment. Several asthma phenotypes with unique clinical and inflammatory characteristics have been identified. Endotypes, based on distinct molecular profiles, help to further elucidate the heterogeneity within asthma. Type 2 inflammation, involving both the innate (type 2 innate lymphoid cell) and adaptive (T-helper type 2 cells) immune systems, underpins the complex pathophysiology of chronic inflammation in asthma, as well as the presence of comorbid disease (e.g. chronic rhinosinusitis with nasal polyps, allergic rhinitis and atopic dermatitis). Type 2 inflammation is characterised by upregulation of the type 2 cytokines interleukin (IL)-4, IL-5 and IL-13, IgE-mediated release of immune mediators and dysfunction of epithelial or epidermal barriers. Targeting these key proximal type 2 cytokines has shown efficacy in recent studies adopting a personalised approach to treatment using targeted biologics. Elevated levels of biomarkers downstream of type 2 cytokines, including fractional exhaled nitric oxide, serum IgE and blood and sputum eosinophils, have been linked to mechanisms involved in type 2 inflammation. They have the potential to aid diagnosis, and to predict and monitor response to treatment. The objective of this review is to summarise the current understanding of the biology of type 2 inflammation in asthma, examine its influence on type 2 inflammatory comorbidities, and discuss how type 2 inflammatory biomarkers can be harnessed to further personalise treatments in the age of biologic medicines.

This review covers the pathophysiology of type 2 inflammation in asthma, its influence on type 2 comorbidities, and ways in which type 2 biomarkers can be harnessed to improve diagnosis and further personalise treatments in the age of biologic medicineshttps://bit.ly/2MSOI2O

Atopic respiratory diseases and IgE sensitization are associated with leukocyte subset concentrations in 14,440 blood donors

BACKGROUND AND AIMS

Allergic rhinitis (AR), allergic conjunctivitis (AC), and asthma are characterized by activation of the immune system. The aim of this study was to explore the long-term association between AR, AC, asthma, and specific immunoglobulin E (IgE) and blood platelet and leukocyte differential counts.

MATERIAL AND METHODS

In the Danish Blood Donor Study, 14,440 participants from Central Denmark Region had platelet and leukocyte differential counts available and completed a questionnaire regarding AR, AC, and asthma. Of these participants, 8485 were tested for IgE to inhalation allergens.

RESULTS

The prevalence of AR, AC, asthma, and IgE sensitization was 19%, 15%, 9%, and 29%, respectively. AR, AC, asthma, wheeze, and IgE sensitization was associated with increased blood eosinophil concentration even in IgE sensitized participants who did not report any allergy or asthma. The strongest associations were observed for participants with current disease. We found no differences in eosinophil concentration between months without symptoms and months with symptoms of AR and asthma.

CONCLUSION

AR, AC, asthma, wheezing, and IgE sensitization to inhalation allergens are associated with increased eosinophil concentration. This may reflect a persistent inflammation even in periods without symptomatic disease.

TGF-β1 increases permeability of ciliated airway epithelia via redistribution of claudin 3 from tight junction into cell nuclei

TGF-β1 is a major mediator of airway tissue remodelling during atopic asthma and affects tight junctions (TJs) of airway epithelia. However, its impact on TJs of ciliated epithelia is sparsely investigated. Herein we elaborated effects of TGF-β1 on TJs of primary human bronchial epithelial cells. We demonstrate that TGF-β1 activates TGF-β1 receptors TGFBR1 and TGFBR2 resulting in ALK5-mediated phosphorylation of SMAD2. We observed that TGFBR1 and -R2 localize specifically on motile cilia. TGF-β1 activated accumulation of phosphorylated SMAD2 (pSMAD2-C) at centrioles of motile cilia and at cell nuclei. This triggered an increase in paracellular permeability via cellular redistribution of claudin 3 (CLDN3) from TJs into cell nuclei followed by disruption of epithelial integrity and formation of epithelial lesions. Only ciliated cells express TGF-β1 receptors; however, nuclear accumulations of pSMAD2-C and CLDN3 redistribution were observed with similar time course in ciliated and non-ciliated cells. In summary, we demonstrate a role of motile cilia in TGF-β1 sensing and showed that TGF-β1 disturbs TJ permeability of conductive airway epithelia by redistributing CLDN3 from TJs into cell nuclei. We conclude that the observed effects contribute to loss of epithelial integrity during atopic asthma.

Genetic and shared environmental risk factors do not lead to eosinophil activation in healthy twins of IBD patients

OBJECTIVE

To examine the role of eosinophils in the pre-diagnostic phase of inflammatory bowel disease (IBD), we studied the influence of genetic and shared environmental risk factors in a twin cohort of IBD.

MATERIAL AND METHODS

We analysed eosinophil derived neurotoxin (EDN) and eosinophil cationic protein (ECP) in faecal samples from twin pairs with Crohn's disease (n = 37) or ulcerative colitis (n = 21) and from external healthy controls (n = 44). Eosinophils stained with eosinophil peroxidase (EPO) were quantified in rectal biopsies. Ratios with 95% confidence intervals were calculated.

RESULTS

Twins with Crohn' disease displayed higher levels of EDN (Ratio = 2.98, 1.65-5.37) and ECP (Ratio 1.83, 1.24-2.70) than their healthy siblings. Levels did not differ between healthy twin-siblings and external controls (EDN, Ratio = 1.52, 0.79-2.94 and ECP, Ratio = 0.93, 0.56-1.54). Higher levels of EDN (Ratio = 2.43, 1.13-5.24) and ECP (Ratio = 1.53, 0.92-2.53) were observed among twins with ulcerative colitis vs their healthy siblings. Levels did not differ between healthy twin-siblings and external controls (EDN, Ratio = 1.08, 0.51-2.25 and ECP, Ratio = 1.29, 0.74-2.26). Using intra-class correlation coefficient (ICC), we found no agreement in levels of EDN or ECP in discordant pairs, except for ECP in monozygotic Crohn's disease pairs (ICC = 0.63). In contrast, agreement was observed in monozygotic pairs concordant for Crohn's disease (EDN, ICC = 0.67 and ECP, ICC = 0.66). The number of eosinophils in rectum was increased in twins with ulcerative colitis vs their healthy sibling (Ratio = 2.22, 1.50-3.27).

CONCLUSIONS

Activation of eosinophils in IBD seems to be a consequence of inflammation rather than an effect of genetic and shared environmental risk factors alone.

Association of RANTES gene polymorphisms with susceptibility to childhood asthma: A meta-analysis

BACKGROUND

Previous investigations have illustrated that regulated upon activation, normal T-cell expressed and secreted (RANTES) polymorphisms are linked to susceptibility to childhood asthma; nevertheless, the findings continue to be controversial. Accordingly, we conducted the present meta-analysis to clarify the impact of RANTES genetic polymorphisms (-403G/A and -28C/G) on childhood asthma vulnerability.

METHODS

A search for published literature was performed using the PubMed, EMBASE, Chinese National Infrastructure, Cochrane Library, Scopus, Web of Science, and WanFang databases and selected in the form of PICOS (participants, interventions, comparisons, outcomes, and study design) to identify all eligible research works. The link between RANTES genetic polymorphisms and childhood asthma susceptibility was evaluated by a pooled odds ratio with a 95% confidence interval.

RESULTS

In total, 14 case-control studies were included in the analysis. No significant association existed between risk of childhood asthma and the -403G/A polymorphism subjected to any genetic framework in the overall population. In the stratified analysis, according to ethnicity, the -403G/A polymorphism was linked to augmented vulnerability to childhood asthma in Caucasians (allelic model: odds ratio [OR] = 1.63, 95% confidence interval [CI] = 1.04-2.57, P = .034; codominant model: OR = 2.20, 95% CI = 1.28-3.78, P = .004; dominant model: OR = 1.78, 95% CI = 1.01-3.13, P = .047; and recessive model: OR = 1.92, 95% CI = 1.11-3.30, P = .019). For the stratified analysis by atopic status, the -403G/A polymorphism was linked to augmented childhood asthma in the codominant (OR = 1.39, 95% CI = 1.02-1.91, P = .037) and dominant models (OR = 1.43, 95% CI = 1.02-2.01, P = .037) in atopic asthma. For the -28C/G polymorphism, there was a significant association between childhood asthma and the -28C/G variant (allelic model: OR = 1.33, 95% CI = 1.08-1.65, P = .009; codominant framework: OR = 2.14, 95% CI = 1.47-3.10, P < .001; dominant model: OR = 1.44, 95% CI = 1.07-1.93, P = .017; and recessive model: OR = 2.08, 95% CI = 1.44-3.02, P < .001). Stratified analysis based on ethnicity and the -28C/G polymorphism was linked to augmented vulnerability to childhood asthma in Asian and Caucasian populations. For the subgroup analysis by atopic status, no association was found in atopic and non-atopic asthma.

CONCLUSION

The present meta-analysis indicated that the RANTES -403G/A and -28C/G polymorphisms contributed to the development of childhood asthma.

Real-Life effects of benralizumab on exacerbation number and lung hyperinflation in atopic patients with severe eosinophilic asthma

BACKGROUND

The humanized monoclonal antibody benralizumab targets the α subunit of the interleukin-5 (IL-5) receptor and the FcγRIIIa receptor expressed by natural killer cells. Through this dual mechanism of action, benralizumab neutralizes the pro-eosinophil functions of IL-5 and promotes eosinophil apoptosis.

OBJECTIVES AND METHODS

The present real-life study aimed to evaluate, in 22 allergic patients with severe eosinophilic asthma, the effects of benralizumab on asthma exacerbations and lung hyperinflation.

RESULTS

In this regard here we show that, after 24 weeks of add-on treatment, benralizumab completely depleted peripheral blood eosinophils (from 810 to 0 cells/μL; p < 0.0001), and significantly decreased both asthma exacerbation number (from 4 to 0; p < 0.0001) and residual volume (from 2720 to 2300 mL; p < 0.01). Moreover, at the same time point (24 weeks) benralizumab also increased pre-bronchodilator FEV₁ (from 1295 to 1985 mL; p < 0.0001), FVC (from 2390 to 2974 mL; p < 0.0001), FEF_25-75 (from 0.6 to 1.42 L/sec; p < 0.0001), IC (from 1940 to 2460 mL; not significant), and ACT score (from 14.73 to 22.95; p < 0.0001), as well as reduced prednisone intake (from 25 to 0 mg; p < 0.0001).

CONCLUSION

In conclusion, our results suggest that via its anti-eosinophil actions benralizumab improved airflow limitation, lung hyperinflation, and respiratory symptoms, as well as lowered asthma exacerbation rate and abrogated OCS consumption in most patients.

Contribution of airway eosinophils in airway wall remodeling in asthma: Role of MMP-10 and MET

BACKGROUND

Eosinophils play an important role in the pathophysiology of asthma being implicated in airway epithelial damage and airway wall remodeling. We determined the genes associated with airway remodeling and eosinophilic inflammation in patients with asthma.

METHODS

We analyzed the transcriptomic data from bronchial biopsies of 81 patients with moderate-to-severe asthma of the U-BIOPRED cohort. Expression profiling was performed using Affymetrix arrays on total RNA. Transcription binding site analysis used the PRIMA algorithm. Localization of proteins was by immunohistochemistry.

RESULTS

Using stringent false discovery rate analysis, MMP-10 and MET were significantly overexpressed in biopsies with high mucosal eosinophils (HE) compared to low mucosal eosinophil (LE) numbers. Immunohistochemical analysis confirmed increased expression of MMP-10 and MET in bronchial epithelial cells and in subepithelial inflammatory and resident cells in asthmatic biopsies. Using less-stringent conditions (raw P-value < 0.05, log2 fold change > 0.5), we defined a 73-gene set characteristic of the HE compared to the LE group. Thirty-three of 73 genes drove the pathway annotation that included extracellular matrix (ECM) organization, mast cell activation, CC-chemokine receptor binding, circulating immunoglobulin complex, serine protease inhibitors, and microtubule bundle formation pathways. Genes including MET and MMP10 involved in ECM organization correlated positively with submucosal thickness. Transcription factor binding site analysis identified two transcription factors, ETS-1 and SOX family proteins, that showed positive correlation with MMP10 and MET expression.

CONCLUSION

Pathways of airway remodeling and cellular inflammation are associated with submucosal eosinophilia. MET and MMP-10 likely play an important role in these processes.

Control of cytokine-driven eosinophil migratory behavior by TGF-beta-induced protein (TGFBI) and periostin

Periostin, which is induced by interleukin (IL)-13, is an extracellular matrix (ECM) protein that supports αMβ2 integrin-mediated adhesion and migration of IL-5-stimulated eosinophils. Transforming growth factor (TGF)-β-induced protein (TGFBI) is a widely expressed periostin paralog known to support monocyte adhesion. Our objective was to compare eosinophil adhesion and migration on TGFBI and periostin in the presence of IL-5-family cytokines. Eosinophil adhesion after 1 h and random motility over 20 h in the presence of various concentrations of IL-5, IL-3, or granulocyte macrophage-colony stimulating factor (GM-CSF) were quantified in wells coated with various concentrations of TGFBI or periostin. Results were compared to video microscopy of eosinophils. Cytokine-stimulated eosinophils adhered equivalently well to TGFBI or periostin in a coating concentration-dependent manner. Adhesion was blocked by anti-αMβ2 and stimulated at the lowest concentration by GM-CSF. In the motility assay, periostin was more potent than TGFBI, the coating-concentration effect was bimodal, and IL-3 was the most potent cytokine. Video microscopy revealed that under the optimal coating condition of 5 μg/ml periostin, most eosinophils migrated persistently and were polarized and acorn-shaped with a ruffling forward edge and granules gathered together, in front of the nucleus. On 10 μg/ml periostin or TGFBI, more eosinophils adopted a flattened pancake morphology with dispersed granules and nuclear lobes, and slower migration. Conversion between acorn and pancake morphologies were observed. We conclude that TGFBI or periostin supports two modes of migration by IL-5 family cytokine-activated eosinophils. The rapid mode is favored by intermediate protein coatings and the slower by higher coating concentrations. We speculate that eosinophils move by haptotaxis up a gradient of adhesive ECM protein and then slow down to surveil the tissue.

Long-term exposure to low-dose Haemophilus influenzae during allergic airway disease drives a steroid-resistant neutrophilic inflammation and promotes airway remodeling

Growing evidences indicate that bacteria are associated with pathogenesis of neutrophilic asthma. However, the long-term effect of airway bacterial colonization remains unclear. We sought to establish a murine model to simulate the airway inflammation of long-term bacterial colonization, and to assess the effects of bacteria on allergic airway disease (AAD). BALB/c mice were sensitized twice and subsequently challenged with ovalbumin (OVA) and exposed to low-dose Haemophilus influenzae for approximately 2 months. Mice in treatment groups inhaled budesonide for consecutively 6 days in the last week. Airway inflammatory phenotype, immune response, phagocytic capacity, mucus production, airway remodeling and steroid sensitivity were assessed. Long-term exposure to low-dose H. influenzae during AAD did not cause serious infection but only a slightly increased airway inflammation, which resembled the colonization. Inflammatory phenotype was converted from a steroid-sensitive T helper (Th) 2-associated eosinophilic inflammation to a steroid-resistant Th17-associated neutrophilic inflammation. The increased neutrophilic inflammation was accompanied by defects in regulatory T cell (Treg)-associated immunosuppression and macrophage phagocytosis, and finally promoted mucus hypersecretion and airway remodeling. These features resembled those of refractory neutrophilic asthma in humans. These findings indicate that in asthmatic patients, airway bacterial colonization may be a potential therapeutic target. Minimizing the pathogen burden in airway, such as Haemophilus influenzae, may be beneficial.

Mouse Eosinophils: Identification, Isolation, and Functional Analysis

Eosinophils are bone marrow-derived cells that differentiate in the bone marrow and migrate into the peripheral blood primarily under the regulation of interleukin (IL)-5. Eosinophil levels in the blood are relatively low. However, under steady-state conditions and in settings of allergic inflammation, parasite infections, or even cancer, they migrate and mainly reside in mucosal tissues where they have key effector and immune-modulating functions. Functional studies using eosinophils are not simple, since these cells are terminally differentiated and rapidly die in vitro. Thus, establishing simple methods to characterize, obtain, and functionally assess eosinophil activities is important. In this unit, we describe methodology for identifying tissue eosinophils by flow cytometry. In addition, we provide detailed methods for isolating eosinophils and for differentiating them from bone marrow cells for further functional studies. © 2017 by John Wiley & Sons, Inc.

Notch Signaling: Linking Embryonic Lung Development and Asthmatic Airway Remodeling

Lung development is mediated by assorted signaling proteins and orchestrated by complex mesenchymal-epithelial interactions. Notch signaling is an evolutionarily conserved cell-cell communication mechanism that exhibits a pivotal role in lung development. Notably, both aberrant expression and loss of regulation of Notch signaling are critically linked to the pathogenesis of various lung diseases, in particular, pulmonary fibrosis, lung cancer, pulmonary arterial hypertension, and asthmatic airway remodeling; implying that precise regulation of intensity and duration of Notch signaling is imperative for appropriate lung development. Moreover, evidence suggests that Notch signaling links embryonic lung development and asthmatic airway remodeling. Herein, we summarized all-recent advances associated with the mechanistic role of Notch signaling in lung development, consequences of aberrant expression or deletion of Notch signaling in linking early-impaired lung development and asthmatic airway remodeling, and all recently investigated potential therapeutic strategies to treat asthmatic airway remodeling.

The Regulatory Function of Eosinophils

Eosinophils are a minority circulating granulocyte classically viewed as being involved in host defense against parasites and promoting allergic reactions. However, a series of new regulatory functions for these cells have been identified in the past decade. During homeostasis, eosinophils develop in the bone marrow and migrate from the blood into target tissues following an eotaxin gradient, with interleukin-5 being a key cytokine for eosinophil proliferation, survival, and priming. In multiple target tissues, eosinophils actively regulate a variety of immune functions through their vast arsenal of granule products and cytokines, as well as direct cellular interaction with cells in proximity. The immunologic regulation of eosinophils extends from innate immunity to adaptive immunity and also involves non-immune cells. Herein, we summarize recent findings regarding novel roles of murine and human eosinophils, focusing on interactions with other hematopoietic cells. We also review new experimental tools available and remaining questions to uncover a greater understanding of this enigmatic cell.

Transcriptome profiling of mouse colonic eosinophils reveals a key role for eosinophils in the induction of s100a8 and s100a9 in mucosal healing

Eosinophils are bone marrow-derived cells that have been largely implicated in Th2-associated diseases. Recent data highlights a key role for eosinophils in mucosal innate immune responses especially in the gastrointestinal (GI) tract, which is one of the largest eosinophil reservoirs in the body. Although eosinophils express and synthesize a plethora of proteins that can mediate their effector activities, the transcriptome signature of eosinophils in mucosal inflammation and subsequent repair has been considerably overlooked. We demonstrate that eosinophils are recruited to the colon in acute inflammatory stages where they promote intestinal inflammation and remain in substantial numbers throughout the mucosal healing process. Microarray analysis of primary colonic eosinophils that were sorted at distinct stages of mucosal inflammation and repair revealed dynamic regulation of colonic eosinophil mRNA expression. The clinically relevant genes s100a8 and s100a9 were strikingly increased in colonic eosinophils (up to 550-fold and 80-fold, respectively). Furthermore, local and systemic expression of s100a8 and s100a9 were nearly diminished in eosinophil-deficient ΔdblGATA mice, and were re-constituted upon adoptive transfer of eosinophils. Taken together, these data may provide new insight into the involvement of eosinophils in colonic inflammation and repair, which may have diagnostic and therapeutic implications.

Immune cells in liver regeneration

After partial hepatectomy, hepatocytes proliferate to restore mass and function of the liver. Macrophages, natural killer (NK) cells, natural killer T (NKT) cells, dendritic cells (DC), eosinophils, gamma delta T (γδT) cells, and conventional T cells, as well as other subsets of the immune cells residing in the liver control liver regeneration, either through direct interactions with hepatocytes or indirectly by releasing inflammatory cytokines. Here, we review recent progress regarding the immune cells in the liver and their functions during liver regeneration.

Autofluorescence multiphoton microscopy for visualization of tissue morphology and cellular dynamics in murine and human airways

The basic understanding of inflammatory airway diseases greatly benefits from imaging the cellular dynamics of immune cells. Current imaging approaches focus on labeling specific cells to follow their dynamics but fail to visualize the surrounding tissue. To overcome this problem, we evaluated autofluorescence multiphoton microscopy for following the motion and interaction of cells in the airways in the context of tissue morphology. Freshly isolated murine tracheae from healthy mice and mice with experimental allergic airway inflammation were examined by autofluorescence multiphoton microscopy. In addition, fluorescently labeled ovalbumin and fluorophore-labeled antibodies were applied to visualize antigen uptake and to identify specific cell populations, respectively. The trachea in living mice was imaged to verify that the ex vivo preparation reflects the in vivo situation. Autofluorescence multiphoton microscopy was also tested to examine human tissue from patients in short-term tissue culture. Using autofluorescence, the epithelium, underlying cells, and fibers of the connective tissue, as well as blood vessels, were identified in isolated tracheae. Similar structures were visualized in living mice and in the human airway tissue. In explanted murine airways, mobile cells were localized within the tissue and we could follow their migration, interactions between individual cells, and their phagocytic activity. During allergic airway inflammation, increased number of eosinophil and neutrophil granulocytes were detected that moved within the connective tissue and immediately below the epithelium without damaging the epithelial cells or connective tissues. Contacts between granulocytes were transient lasting 3 min on average. Unexpectedly, prolonged interactions between granulocytes and antigen-uptaking cells were observed lasting for an average of 13 min. Our results indicate that autofluorescence-based imaging can detect previously unknown immune cell interactions in the airways. The method also holds the potential to be used during diagnostic procedures in humans if integrated into a bronchoscope.

The emerging role of miR-223 as novel potential diagnostic and therapeutic target for inflammatory disorders

Since their discovery of more than a decade ago, microRNAs have been demonstrated to have profound effects on almost every aspect of biology. Specific microRNAs have emerged as key players in disease biology by playing crucial role in disease development and progression. This review draws attention to miR-223 that has been reported to be abnormally expressed in several diseases like diabetes-type2, sepsis, rheumatoid arthritis, viral infections likes' human immunodeficiency virus-1 (HIV-1) and inflammatory disorders. It regulates inflammation by targeting different targets, including cytoplasmic activation/proliferation-associated protein-1 (Caprin-1), Insulin-like growth factor-1 receptor (IGF-1R), heat shock protein 90 (Hsp90), STAT5, artemin, EPB41L3, Ect2, Pknox1, C/EBPα, C/EBPβ, E2F1, FOXO1, NFI-A and other transcription factors. In this review, we summarized the recent studies of miR-223, their mechanisms to develop inflammation diseases and its importance role to use as biomarkers for early diagnosis and therapeutic target against inflammation diseases.

Glycomacropeptide administration attenuates airway inflammation and remodeling associated to allergic asthma in rat

OBJECTIVE

Glycomacropeptide (GMP) is a bioactive peptide derived from milk that has been reported to exhibit a range of anti-inflammatory and immunomodulatory properties. The aim of this study was to analyze the prophylactic effect of GMP administration on airway inflammation and remodeling in an experimental model of asthmatic rat.

METHODS

Animals treated orally with or without GMP (500 mg/kg/day) were ovalbumin-sensitized and -nebulized and several indicators of Th2 response, airway structural changes and inflammatory cells recruitment were evaluated.

RESULTS

Treatment with GMP prior and during asthma development resulted in reduction of allergen-specific IgE titers in serum and blood eosinophilia. Also, GMP substantially suppressed the recruitment of inflammatory cells to bronchoalveolar compartment. Histological studies demonstrated that GMP markedly inhibits eosinophils infiltration, goblet cells hyperplasia and collagen deposit in lung tissue. The latter effect was related with an inhibition in transforming growth factor-β expression. In addition, expression of interleukin-5 and -13 were substantially inhibited in lung while that of interleukin-10 was increased.

CONCLUSION

Our results suggest that administration of GMP may prevent the development of an excessive Th2 response in asthma and effectively ameliorates the progression of the disease.

Differing roles for TGF-β/Smad signaling in osteitis in chronic rhinosinusitis with and without nasal polyps

BACKGROUND

Chronic rhinosinusitis (CRS) without nasal polyps (CRSsNP) and with nasal polyps (CRSwNP) is reported to involve different inflammatory processes in sinonasal mucosa and bone tissue, and these processes remain uncharacterized.

OBJECTIVE

We aimed to investigate the molecular mechanisms of osteitis in Chinese patients with CRS to better understand the pathogenesis of CRS.

METHODS

The study included 10 controls, 16 patients with CRSsNP, and 23 patients with CRSwNP. Ethmoid bone tissue samples were evaluated by histologic examination. Quantitative real-time reverse transcription polymerase chain reaction was used to assess expression of transforming growth factor (TGF) β1, TGF-β receptor I and II, Smad2, and Smad3. Immunohistochemical examination of osteoblast expression of TGF-β1, TGF-β receptor I and II, phosphorylated (p) Smad2, and p-Smad3 in ethmoid bone tissue was also performed.

RESULTS

The histopathologic evaluation of ethmoid sinus bone tissue showed that eosinophils had infiltrated the periosteum and induced TGF-β1 expression, periosteal thickening, increased osteoblast activity, and neo-osteogenesis. Messenger RNA levels of TGF-β1, TGF-β receptor I, and Smad3 in CRSwNP ethmoid bone tissues were significantly higher than those in ethmoid bone tissues of patients with CRSsNP and the controls. Immunohistochemical staining showed that TGF-β1, TGF-β receptor I, p-Smad2, and p-Smad3 protein expression was upregulated in patients with CRSwNP, consistent with the corresponding messenger RNA levels.

CONCLUSION

Different signaling pathways are involved in osteitis in CRS and are activated by the TGF-β/Smad signaling pathway in CRSwNP versus the TGF-β/Smad-independent signaling pathway in CRSsNP. Eosinophil infiltration of the periosteum, along with TGF-β1 expression, in CRSwNP indicates that eosinophils may play an important role in the bone remodeling process in CRSwNP.

Smooth muscle CaMKIIδ promotes allergen-induced airway hyperresponsiveness and inflammation

Airway smooth muscle (ASM) is a key target cell in allergen-induced asthma known to contribute to airway hyperresponsiveness (AHR) and chronic airway remodeling. Changes in ASM calcium homeostasis have been shown to contribute to AHR although the mechanisms and Ca(2+) signal effectors are incompletely understood. In the present study, we tested the function of ASM multifunctional protein kinase Ca(2+)/calmodulin-dependent kinase II (CaMKII) isoforms CaMKIIδ and CaMKIIγ in allergen-induced AHR and airway remodeling in vivo. Using a murine model of atopic asthma, we demonstrate that CaMKIIδ protein is upregulated in ASM derived from ovalbumin (OVA)-treated animals compared to controls. A genetic approach to conditionally knock out smooth muscle CaMKIIδ and CaMKIIγ in separate Cre-loxp systems was validated, and using this loss-of-function approach, the function of these CaMKII isoforms was tested in ovalbumin (OVA)-induced airway remodeling and AHR. OVA treatment in control mice had no effect on ASM remodeling in this model of AHR, and CaMKIIδ knockouts had no independent effects on ASM content. However, at 1 day post-final OVA challenge, OVA-induced AHR was eliminated in the CaMKIIδ knockouts. OVA-induced peribronchial inflammation and bronchoalveolar lavage fluid (BALF) levels of the Th2 cytokine IL-13 were significantly decreased in the CaMKIIδ knockouts. Unexpectedly, we found increased peribronchial eosinophils in the smooth muscle CaMKIIδ knockouts compared to control animals at 1 day post-final challenge, suggesting that lack of ASM CaMKIIδ delays the progression of AHR rather than inhibiting it. Indeed, when AHR was determined at 7 days post-final OVA challenge, CaMKIIδ knockouts showed robust AHR while AHR was fully resolved in OVA-challenged control mice. These in vivo studies demonstrate a role for smooth muscle CaMKIIδ in promoting airway inflammation and AHR and suggest a complex signaling role for CaMKIIδ in regulating ASM function. These studies confirm the diverse roles of ASM cells as immune effectors that control AHR and call for further studies into CaMKIIδ-mediated signaling in ASM cells during disease.

Hyaluronan fragments as mediators of inflammation in allergic pulmonary disease

Asthma is frequently caused and/or exacerbated by sensitization to allergens, which are ubiquitous in many indoor and outdoor environments. Severe asthma is characterized by airway hyperresponsiveness and bronchial constriction in response to an inhaled allergen, leading to a disease course that is often very difficult to treat with standard asthma therapies. As a result of interactions among inflammatory cells, structural cells, and the intercellular matrix of the allergic lung, patients with sensitization to allergens may experience a greater degree of tissue injury followed by airway wall remodeling and progressive, accumulated pulmonary dysfunction as part of the disease sequela. In addition, turnover of extracellular matrix (ECM) components is a hallmark of tissue injury and repair. This review focuses on the role of the glycosaminoglycan hyaluronan (HA), a component of the ECM, in pulmonary injury and repair with an emphasis on allergic asthma. Both the synthesis and degradation of the ECM are critical contributors to tissue repair and remodeling. Fragmented HA accumulates during tissue injury and functions in ways distinct from the larger native polymer. There is gathering evidence that HA degradation products are active participants in stimulating the expression of inflammatory genes in a variety of immune cells at the injury site. In this review, we will consider recent advances in the understanding of the mechanisms that are associated with HA accumulation and inflammatory cell recruitment in the asthmatic lung.

Distribution of airway smooth muscle remodelling in asthma: relation to airway inflammation

BACKGROUND AND OBJECTIVE

Pathological phenotypes of asthma have been based predominantly on inflammation, rather than airway wall remodelling. Differences in the distribution of airway smooth muscle (ASM) remodelling between large and small airways may affect clinical outcomes in asthma. The aim of this study was to examine the distribution of ASM remodelling and its relation to airway inflammation.

METHODS

Post-mortem cases of asthma (n = 68) were categorized by the distribution of increased thickness of the ASM layer (relative to nonasthmatic controls, n = 37), into 'large only' (LO, n = 15), 'small only' (SO, n = 4) 'large/small' (LS, n = 24) or no increase (NI, n = 25). Subject characteristics, ASM and airway wall dimensions and inflammatory cell numbers were compared between groups.

RESULTS

Apart from reduced clinical severity of asthma in NI cases (P = 0.002), subject characteristics did not distinguish asthma groups. Compared with control subjects, ASM cell number, reticular basement membrane thickness, airway wall thickness, percent muscle shortening and eosinophil number were increased (P < 0.05) in both large and small airways in LS cases and only the large airways in LO cases. Increased numbers of neutrophils were observed only in the small airways of LO cases.

CONCLUSIONS

Distinct distributions of ASM remodelling are seen in asthma. Pathology limited to the small airways was uncommon. Increased thickness of the ASM layer was associated with airway remodelling and eosinophilia, but not neutrophilia. These data support the presence of distinct pathological phenotypes based on the site of increased ASM.

Surfactant protein SP-D modulates activity of immune cells: proteomic profiling of its interaction with eosinophilic cells

Surfactant protein D (SP-D), a C-type lectin, is known to protect against lung infection, allergy and inflammation. Its recombinant truncated form comprising homotrimeric neck and CRD region (rhSP-D) has been shown to bring down specific IgE levels, eosinophilia and restore Th2-Th1 homeostasis in murine models of lung hypersensitivity. SP-D knockout mice show intrinsic hypereosinophilia and airway hyper-responsiveness that can be alleviated by rhSP-D. The rhSP-D can bind activated eosinophils, inhibit chemotaxis and degranulation, and selectively induce oxidative burst and apoptosis in sensitized eosinophils. A global proteomics study of rhSP-D-treated eosinophilic cell line AML14.3D10 identified large-scale molecular changes associated with oxidative burst, cell stress and survival-related proteins potentially responsible for apoptosis induction. The data also suggested an involvement of RNA binding- and RNA splicing-related proteins. Thus, the proteomics approach yielded a catalog of differentially expressed proteins that may be protein signatures defining mechanisms of SP-D-mediated maintenance of homeostasis during allergy.

Recent progress in the development of antagonists to the chemokine receptors CCR3 and CCR4

INTRODUCTION

The chemokine receptors CCR3 and CCR4 have been shown to be important therapeutic targets for the treatment of a variety of diseases. Although only two chemokine receptor inhibitors have been approved so far, there are numerous compounds that are in various stages of development.

AREAS COVERED

In this review article, the authors provide an update on the progress made in the identification of antagonists against the chemokine receptors CCR3 and CCR4 from 2009 to the present. The rationale of writing this review article is to cover the most important approaches to identifying antagonists to these two receptors, which could prove to be useful therapeutics in treating proinflammatory diseases.

EXPERT OPINION

Pharmaceutical companies have expended a considerable amount of money and effort to identify potent inhibitors of CCR3 and CCR4 for the treatment of asthma and atopic diseases. Although a variety of compounds have been described and several have progressed into the clinic, none have so far made it as approved drugs. There are, however, novel approaches such as mogamulizumab, a monoclonal antibody to CCR4 currently is in clinical trials for cancer and ASM8, an antisense nucleotide to CCR3, which is in Phase II clinical trials for asthma that might still prove to be successful new therapeutics.

Considerations for use of acupuncture as supplemental therapy for patients with allergic asthma

This study examines the clinical and immunomodulatory effects of acupuncture in the treatment of patients with allergic asthma. The acupuncture points GV14, BL12, and BL13 were selected based on the theory of traditional Chinese medicine in treating asthma. Manual acupuncture was performed once every other day (three times per week) for 5 weeks. The needles were twisted approximately 360° evenly at the rate of 60 times/min for 20 s, manipulated every 10 min and withdrawn after 30 min. Concentrations of sIgA and total IgA in secretions were determined by the combination of sucrose density gradient ultracentrifugation and RIA. Levels of cortisol in the plasma were measured by RIA. Total IgE in the sera was examined by ELISA. Flow cytometry was used to detect the numbers of CD3+, CD4+, CD8+, and IL-2R + T lymphocytes in the peripheral blood. The absolute and differential numbers of eosinophils in peripheral blood were counted with eosin staining. The total efficacy of the acupuncture treatment in patients with allergic asthma at the end of one course of treatment was 85 %. After treatment, the concentrations of sIgA and total IgA in the saliva (P<0.01, P<0.02) and nasal secretions (P<0.02, P<0.02) were significantly decreased in patients with allergic asthma. The levels of total IgE in sera (P<0.001), the counts of IL-2R + T lymphocytes (P<0.001), and the absolute and differential numbers of eosinophils (P<0.01, P<0.01) in the peripheral blood were also significantly decreased. The numbers of CD3+, CD4+, and CD8+ T lymphocytes in the peripheral blood were significantly increased in the allergic asthmatics treated by acupuncture (P<0.001, P<0.01, and P<0.001, respectively). The concentration of cortisol in the plasma of asthmatic patients did not change significantly after the acupuncture treatment (P>0.05). Acupuncture has regulatory effects on mucosal and cellular immunity in patients with allergic asthma and may be an adjunctive therapy for allergic asthma.

Pathology of asthma

Asthma is a serious health and socioeconomic issue all over the world, affecting more than 300 million individuals. The disease is considered as an inflammatory disease in the airway, leading to airway hyperresponsiveness, obstruction, mucus hyper-production and airway wall remodeling. The presence of airway inflammation in asthmatic patients has been found in the nineteenth century. As the information in patients with asthma increase, paradigm change in immunology and molecular biology have resulted in an extensive evaluation of inflammatory cells and mediators involved in the pathophysiology of asthma. Moreover, it is recognized that airway remodeling into detail, characterized by thickening of the airway wall, can be profound consequences on the mechanics of airway narrowing and contribute to the chronic progression of the disease. Epithelial to mesenchymal transition plays an important role in airway remodeling. These epithelial and mesenchymal cells cause persistence of the inflammatory infiltration and induce histological changes in the airway wall, increasing thickness of the basement membrane, collagen deposition and smooth muscle hypertrophy and hyperplasia. Resulting of airway inflammation, airway remodeling leads to the airway wall thickening and induces increased airway smooth muscle mass, which generate asthmatic symptoms. Asthma is classically recognized as the typical Th2 disease, with increased IgE levels and eosinophilic inflammation in the airway. Emerging Th2 cytokines modulates the airway inflammation, which induces airway remodeling. Biological agents, which have specific molecular targets for these Th2 cytokines, are available and clinical trials for asthma are ongoing. However, the relatively simple paradigm has been doubted because of the realization that strategies designed to suppress Th2 function are not effective enough for all patients in the clinical trials. In the future, it is required to understand more details for phenotypes of asthma.

CD14+CD33+ myeloid cell-CCL11-eosinophil signature in ulcerative colitis

This study tested the hypothesis that eotaxins (CCL11, CCL24, and CCL26) and IL-5 contribute to eosinophil recruitment to the intestine in UC and that intestinal macrophages are important producers of CCL11 in this disease. Peripheral blood and rectal biopsy samples were obtained from patients with active (n=18) and quiescent UC (n=9), and control patients (n=7). Eosinophil and macrophage levels and activation were analyzed by flow cytometry. Rectal mRNA levels of CCL11, CCL24, CCL26, and IL-5 were determined by qRT-PCR. The cellular source of CCL11 was visualized by immunofluorescence analyses. Eosinophil numbers were elevated in the blood and rectum of active and quiescent UC patients compared with controls. Levels of activated eosinophils (CD66b(high)) correlated with disease severity. Rectal CCL11, CCL24, and CCL26 mRNA levels were increased in active UC, whereas only CCL11 was elevated in quiescent UC. Levels of CCL11, but not CCL24 and CCL26, positively correlated with eosinophil numbers. Numbers of CD14(+)CD33(+) cells correlated with CCL11 and eosinophil levels. Immunofluorescence analyses revealed the presence of CD14(+)CCL11(+) mononuclear cells in colonic biopsies in UC. These results support the hypothesis that CCL11 contributes to eosinophil recruitment in UC and that intestinal myeloid cells are a source of CCL11. Interestingly, rectal levels of CCL24, CCL26, and IL-5 only increase during active UC, coinciding with further elevation of eosinophil numbers and with the activation of rectal eosinophils. In conclusion, there is a link among CD14(+)CD33(+) myeloid cells, CCL11, and eosinophils in adult UC.

Eosinophils promote epithelial to mesenchymal transition of bronchial epithelial cells

Eosinophilic inflammation and remodeling of the airways including subepithelial fibrosis and myofibroblast hyperplasia are characteristic pathological findings of bronchial asthma. Epithelial to mesenchymal transition (EMT) plays a critical role in airway remodelling. In this study, we hypothesized that infiltrating eosinophils promote airway remodelling in bronchial asthma. To demonstrate this hypothesis we evaluated the effect of eosinophils on EMT by in vitro and in vivo studies. EMT was assessed in mice that received intra-tracheal instillation of mouse bone marrow derived eosinophils and in human bronchial epithelial cells co-cultured with eosinophils freshly purified from healthy individuals or with eosinophilic leukemia cell lines. Intra-tracheal instillation of eosinophils was associated with enhanced bronchial inflammation and fibrosis and increased lung concentration of growth factors. Mice instilled with eosinophils pre-treated with transforming growth factor(TGF)-β1 siRNA had decreased bronchial wall fibrosis compared to controls. EMT was induced in bronchial epithelial cells co-cultured with human eosinophils and it was associated with increased expression of TGF-β1 and Smad3 phosphorylation in the bronchial epithelial cells. Treatment with anti-TGF-β1 antibody blocked EMT in bronchial epithelial cells. Eosinophils induced EMT in bronchial epithelial cells, suggesting their contribution to the pathogenesis of airway remodelling.

Eosinophils mediate the pathogenesis of halothane-induced liver injury in mice

Drug-induced liver injury (DILI) is a major health issue, as it remains difficult to predict which new drugs will cause injury and who will be susceptible to this disease. This is due in part to the lack of animal models and knowledge of susceptibility factors that predispose individuals to DILI. In this regard, liver eosinophilia has often been associated with DILI, although its role remains unclear. We decided to investigate this problem in a murine model of halothane-induced liver injury (HILI). When female Balb/cJ mice were administered halothane, eosinophils were detected by flow cytometry in the liver within 12 hours and increased thereafter proportionally to liver damage. Chemokines, eotaxin-1 (CCL11) and eotaxin-2 (CCL24), which are known to attract eosinophils, increased in response to halothane treatment. The severity of HILI was decreased significantly when the study was repeated in wildtype mice made deficient in eosinophils with a depleting antibody and in eosinophil lineage-ablated ΔdblGata(-/-) mice. Moreover, depletion of neutrophils by pretreating animals with Gr-1 antibody prior to halothane administration failed to reduce the severity of HILI at antibody concentrations that did not affect hepatic eosinophils. Immunohistochemical staining for the granule protein, major basic protein, revealed that eosinophils accumulated exclusively around areas of hepatocellular necrosis.

CONCLUSION

Our findings indicate that eosinophils have a pathologic role in HILI in mice and suggest that they may contribute similarly in many clinical cases of DILI.

Eosinophilic inflammation in allergic asthma

Eosinophils are circulating granulocytes involved in pathogenesis of asthma. A cascade of processes directed by Th2 cytokine producing T-cells influence the recruitment of eosinophils into the lungs. Furthermore, multiple elements including interleukin (IL)-5, IL-13, chemoattractants such as eotaxin, Clara cells, and CC chemokine receptor (CCR)3 are already directly involved in recruiting eosinophils to the lung during allergic inflammation. Once recruited, eosinophils participate in the modulation of immune response, induction of airway hyperresponsiveness and remodeling, characteristic features of asthma. Various types of promising treatments for reducing asthmatic response are related to reduction in eosinophil counts both in human and experimental models of pulmonary allergic inflammation, showing that the recruitment of these cells really plays an important role in the pathophysiology of allergic diseases such asthma.

Eosinophils in fungus-associated allergic pulmonary disease

Asthma is frequently caused and/or exacerbated by sensitization to fungal allergens, which are ubiquitous in many indoor and outdoor environments. Severe asthma with fungal sensitization is characterized by airway hyperresponsiveness and bronchial constriction in response to an inhaled allergen that is worsened by environmental exposure to airborne fungi and which leads to a disease course that is often very difficult to treat with standard asthma therapies. As a result of complex interactions among inflammatory cells, structural cells, and the intercellular matrix of the allergic lung, patients with sensitization to fungal allergens may experience a greater degree of airway wall remodeling and progressive, accumulated pulmonary dysfunction as part of the disease sequela. From their development in the bone marrow to their recruitment to the lung via chemokine and cytokine networks, eosinophils form an important component of the inflammatory milieu that is associated with this syndrome. Eosinophils are recognized as complex multi-factorial leukocytes with diverse functions in the context of allergic fungal asthma. In this review, we will consider recent advances in our understanding of the molecular mechanisms that are associated with eosinophil development and migration to the allergic lung in response to fungal inhalation, along with the eosinophil’s function in the immune response to and the immunopathology attributed to fungus-associated allergic pulmonary disease.

MiR-223 deficiency increases eosinophil progenitor proliferation

Recently, microRNAs have been shown to be involved in hematopoietic cell development, but their role in eosinophilopoiesis has not yet been described. In this article, we show that miR-223 is upregulated during eosinophil differentiation in an ex vivo bone marrow-derived eosinophil culture system. Targeted ablation of miR-223 leads to an increased proliferation of eosinophil progenitors. We found upregulation of a miR-223 target gene, IGF1R, in the eosinophil progenitor cultures derived from miR-223(-/-) mice compared with miR-223(+/+) littermate controls. The increased proliferation of miR-223(-/-) eosinophil progenitors was reversed by treatment with an IGF1R inhibitor (picropodophyllin). Whole-genome microarray analysis of differentially regulated genes between miR-223(+/+) and miR-223(-/-) eosinophil progenitor cultures identified a specific enrichment in genes that regulate hematologic cell development. Indeed, miR-223(-/-) eosinophil progenitors had a delay in differentiation. Our results demonstrate that microRNAs regulate the development of eosinophils by influencing eosinophil progenitor growth and differentiation and identify a contributory role for miR-223 in this process.

Eosinophils in infection and intestinal immunity

PURPOSE OF REVIEW

Inflammatory bowel diseases (IBDs, e.g., Crohn's disease and ulcerative colitis) are thought to be a consequence of an uncontrolled inflammatory response against luminal antigens, including commensal bacteria. The observed link between eosinophil levels and severity and remission rates in IBD has led to speculation that eosinophils may contribute to the antimicrobial inflammatory response in IBD.

RECENT FINDINGS

Eosinophils express the necessary cellular machinery (innate immune receptors, proinflammatory cytokines, antibacterial proteins, and DNA traps) to mount an efficient antibacterial response; however, the rapid decline in eosinophil numbers following acute systemic bacterial infection suggests a very limited role for eosinophils in bacterial responses.

SUMMARY

We describe the clinical evidence of eosinophil involvement in IBD, summarize the in-vitro and in-vivo evidence of eosinophil antibacterial activity and the biology of eosinophils focusing on eosinophil-mediated bactericidal mechanisms and the involvement of eosinophil-derived granule proteins in this response, and conceptualize the contribution of eosinophils to a response against commensal bacteria in IBD.

Correlation of hyaluronan deposition with infiltration of eosinophils and lymphocytes in a cockroach-induced murine model of asthma

Asthma is a chronic inflammatory disease that exhibits airway remodeling with changes in the extracellular matrix (ECM). The role of the ECM in mediating these changes is poorly understood. Hyaluronan (HA), a major component of the ECM, has been implicated in many biological processes in diseases. This study investigates the processes involved in HA synthesis, deposition and localization during the propagation of cockroach-induced asthma. Mice were sensitized and challenged with cockroach antigen, and sacrificed at various time points during an 8-week challenge protocol. Analysis of bronchoalveolar lavage (BAL) fluid revealed an increase in total nucleated cells as early as 6h, which peaked at 6 days. Histopathologic analysis of the lung tissue revealed an influx of inflammatory cells at the peribronchial and perivascular regions starting at 12 h, which peaked at 6 days and persisted to 8 weeks. Eosinophils predominated in the early time points while lymphocytes predominated during the late time points. Quantitative polymerase chain reaction (PCR) data showed that hyaluronan synthase 1 (HAS1) mRNA peaked within 6 h and then declined. HAS2 mRNA also peaked within 6 h but remained elevated throughout the 8-week exposure course. HA levels in lung tissue and BAL increased at 12 h and peaked by 6 and 8 days, respectively. Inflammatory cells and new collagen formation localized in areas of HA deposition. Taken together, these data support a role for HA in the pathogenesis in asthma.

Antimicrobial action and cell agglutination by the eosinophil cationic protein are modulated by the cell wall lipopolysaccharide structure

Antimicrobial proteins and peptides (AMPs) are essential effectors of innate immunity, acting as a first line of defense against bacterial infections. Many AMPs exhibit high affinity for cell wall structures such as lipopolysaccharide (LPS), a potent endotoxin able to induce sepsis. Hence, understanding how AMPs can interact with and neutralize LPS endotoxin is of special relevance for human health. Eosinophil cationic protein (ECP) is an eosinophil secreted protein with high activity against both Gram-negative and Gram-positive bacteria. ECP has a remarkable affinity for LPS and a distinctive agglutinating activity. By using a battery of LPS-truncated E. coli mutant strains, we demonstrate that the polysaccharide moiety of LPS is essential for ECP-mediated bacterial agglutination, thereby modulating its antimicrobial action. The mechanism of action of ECP at the bacterial surface is drastically affected by the LPS structure and in particular by its polysaccharide moiety. We have also analyzed an N-terminal fragment that retains the whole protein activity and displays similar cell agglutination behavior. Conversely, a fragment with further minimization of the antimicrobial domain, though retaining the antimicrobial capacity, significantly loses its agglutinating activity, exhibiting a different mechanism of action which is not dependent on the LPS composition. The results highlight the correlation between the protein's antimicrobial activity and its ability to interact with the LPS outer layer and promote bacterial agglutination.

Induction of eosinophil apoptosis by the cyclin-dependent kinase inhibitor AT7519 promotes the resolution of eosinophil-dominant allergic inflammation

Background

Eosinophils not only defend the body against parasitic infection but are also involved in pathological inflammatory allergic diseases such as asthma, allergic rhinitis and contact dermatitis. Clearance of apoptotic eosinophils by macrophages is a key process responsible for driving the resolution of eosinophilic inflammation and can be defective in allergic diseases. However, enhanced resolution of eosinophilic inflammation by deliberate induction of eosinophil apoptosis using pharmacological agents has not been previously demonstrated. Here we investigated the effect of a novel cyclin-dependent kinase inhibitor drug, AT7519, on human and mouse eosinophil apoptosis and examined whether it could enhance the resolution of a murine model of eosinophil-dominant inflammation in vivo.

Methodology/Principal Findings

Eosinophils from blood of healthy donors were treated with AT7519 and apoptosis assessed morphologically and by flow-cytometric detection of annexin-V/propidium iodide staining. AT7519 induced eosinophil apoptosis in a concentration dependent manner. Therapeutic administration of AT7519 in eosinophil-dominant allergic inflammation was investigated using an established ovalbumin-sensitised mouse model of allergic pleurisy. Following ovalbumin challenge AT7519 was administered systemically at the peak of pleural inflammation and inflammatory cell infiltrate, apoptosis and evidence of macrophage phagocytosis of apoptotic eosinophils assessed at appropriate time points. Administration of AT7519 dramatically enhanced the resolution of allergic pleurisy via direct induction of eosinophil apoptosis without detriment to macrophage clearance of these cells. This enhanced resolution of inflammation was shown to be caspase-dependent as the effects of AT7519 were reduced by treatment with a broad spectrum caspase inhibitor (z-vad-fmk).

Conclusions

Our data show that AT7519 induces human eosinophil apoptosis and enhances the resolution of a murine model of allergic pleurisy by inducing caspase-dependent eosinophil apoptosis and enhancing macrophage ingestion of apoptotic eosinophils. These findings demonstrate the utility of cyclin-dependent kinase inhibitors such as AT7519 as potential therapeutic agents for the treatment of eosinophil dominant allergic disorders.

Histopathologic diagnosis of eosinophilic conditions in the gastrointestinal tract

Eosinophils, a constitutive component of the columnar-lined gastrointestinal tract, play an essential role in allergic responses and parasitic infections. The tissue density of these cells also increases in a variety of conditions of uncertain etiology. With the exception of the esophageal squamous epithelium, in which no eosinophils are normally present, the population of normal eosinophils in the remainder of the luminal gut is poorly defined. Therefore, histopathologists must rely on their subjective judgment to determine when a diagnosis of eosinophilic gastritis, enteritis, or colitis should be rendered. Eosinophilic esophagitis is currently the best defined and most studied eosinophilic condition of the digestive tract; therefore, the confidence in accurate diagnosis is increasing. In contrast, the characteristic clinicopathologic features of eosinophilic conditions affecting other parts of the digestive tract remain somewhat elusive. This review was designed to present pathologists with simple and practical information for the biopsy-based histopathologic diagnosis of eosinophilic esophagitis, gastritis, enteritis, and colitis. It was prepared by critically reviewing more than 200 articles on the topic, along with incorporating evidence accumulated through our own collective experience. We anticipate that by increasing pathologists' confidence in reporting these abnormal but often nameless eosinophilic infiltrates, we can help better define and characterize their significance.

Eosinophils: offenders or general bystanders in allergic airway disease and pulmonary immunity?

Eosinophils have long been noted to be present in asthma and other forms of pulmonary inflammation, but whether they act as true offenders or merely as bystanders has been a point of uncertainty. However, in recent years, there has been increasing evidence suggesting that eosinophils are not passive cells in the respiratory system, acting only as markers of allergic inflammation. This review discusses key evidence from animal models and human clinical trials that support the importance of eosinophils as active and necessary, rather than passive and unnecessary, to the pathogenesis of allergic airway disease. Analyses that are supportive of important immunoregulatory roles of eosinophils in allergic pulmonary inflammation are also reviewed. Data indicating that eosinophils contribute to viral, bacterial, and mycobacterial defense and clearance are detailed. Continually increasing evidence has supported a new conception of eosinophils as being multifaceted immune cells with complex interactions with other immune cells and their local environment.

The persistence of allergen exposure favors pulmonary function decline in workers with allergic occupational asthma

BACKGROUND

In asthmatics, a rapid decline in pulmonary function is observed, likely as a consequence of airways remodeling. Persistence of allergen exposure in patients with occupational asthma (OA) maintains chronic bronchial inflammation, resulting in a more severe lung function decline. Few studies were performed on the effects of allergen exposure cessation.

OBJECTIVE

This study aims at evaluating the influence of allergen exposure cessation on respiratory decline in allergic asthmatic workers.

METHODS

Two groups of workers with allergic OA were selected. The first group (30 workers) changed job after the diagnosis and was no more exposed to sensitizing allergens, and the second group (28 subjects) did not and, as a consequence of preventive measures in the work place, was exposed to a lower level of allergens. All were treated with conventional therapy, according to GINA protocols. FEV1 changes during a 12-year period were evaluated.

RESULTS

Despite pharmacological therapy, the pulmonary function decay slope was steeper in workers continuously exposed to the sensitizing agent (even at reduced level) than in those with a complete cessation of exposure: final FEV1 loss was 512.5 ± 180 ml versus 332.5 ± 108 ml, respectively. The difference became significant after 4 years from the cessation of the exposure.

CONCLUSIONS

The study shows that the cessation of the exposure to allergen in the work place appears the most effective measure in limiting pulmonary function decline in asthmatic workers and underlines the importance of allergic risk assessment and control in the management of occupational asthma.