Eosinophil cationic protein stimulates migration of human lung fibroblasts in vitro

Chronic Lung Allograft Dysfunction: Clinical Manifestations and Immunologic Mechanisms

The term "chronic lung allograft dysfunction" has emerged to describe the clinical syndrome of progressive, largely irreversible dysfunction of pulmonary allografts. This umbrella term comprises 2 major clinical phenotypes: bronchiolitis obliterans syndrome and restrictive allograft syndrome. Here, we discuss the clinical manifestations, diagnostic challenges, and potential therapeutic avenues to address this major barrier to improved long-term outcomes. In addition, we review the immunologic mechanisms thought to propagate each phenotype of chronic lung allograft dysfunction, discuss the various models used to study this process, describe potential therapeutic targets, and identify key unknowns that must be evaluated by future research strategies.

Eosinophils and tissue remodeling: Relevance to airway disease

The ability of human tissue to reorganize and restore its existing structure underlies tissue homeostasis in the healthy airways, but in disease can persist without normal resolution, leading to an altered airway structure. Eosinophils play a cardinal role in airway remodeling both in health and disease, driving epithelial homeostasis and extracellular matrix turnover. Physiological consequences associated with eosinophil-driven remodeling include impaired lung function and reduced bronchodilator reversibility in asthma, and obstructed airflow in chronic rhinosinusitis with nasal polyps. Given the contribution of airway remodeling to the development and persistence of symptoms in airways disease, targeting remodeling is an important therapeutic consideration. Indeed, there is early evidence that eosinophil attenuation may reduce remodeling and disease progression in asthma. This review provides an overview of tissue remodeling in both health and airway disease with a particular focus on eosinophilic asthma and chronic rhinosinusitis with nasal polyps, as well as the role of eosinophils in these processes and the implications for therapeutic interventions. Areas for future research are also noted, to help improve our understanding of the homeostatic and pathological roles of eosinophils in tissue remodeling, which should aid the development of targeted and effective treatments for eosinophilic diseases of the airways.

Asthmatic Eosinophils Promote Contractility and Migration of Airway Smooth Muscle Cells and Pulmonary Fibroblasts In Vitro

Enhanced contractility and migration of airway smooth muscle cells (ASMC) and pulmonary fibroblasts (PF) are part of airway remodeling in asthma. Eosinophils are the central inflammatory cells that participate in airway inflammation. However, the role of asthmatic eosinophils in ASMC and PF contractility, migration, and differentiation to contractile phenotype has not yet been precisely described. A total of 38 individuals were included in this study: 13 steroid-free non-severe allergic asthma (AA) patients, 11 severe non-allergic eosinophilic asthma (SNEA) patients, and 14 healthy subjects (HS). For AA patients and HS groups, a bronchial allergen challenge with D. pteronyssinus was performed. Individual combined cell cultures were prepared from isolated peripheral blood eosinophils and immortalized ASMC or commercial PF cell lines separately. The migration of ASMC and PF was evaluated using wound healing assay and contractility using collagen gel assay. Gene expression of contractile apparatus proteins, COL1A1, COL5A1, and FN, in ASMC and PF was evaluated using qRT-PCR. We found that contractility and migration of ASMC and PF significantly increased after incubation with asthmatic eosinophils compared to HS eosinophils, p < 0.05, and SNEA eosinophils demonstrated the highest effect on contractility of ASMC and migration of both cell lines, p < 0.05. AA and SNEA eosinophils significantly increased gene expression of contractile apparatus proteins, COL1A1 and FN, in both cell lines, p < 0.05. Furthermore, the allergen-activated AA eosinophils significantly increased the contractility of ASMC, and migration and gene expression in ASMC and PF, p < 0.05. Thus, asthmatic eosinophils change ASMC and PF behavior by increasing their contractility and migration, contributing to airway remodeling.

Human RNase3 immune modulation by catalytic-dependent and independent modes in a macrophage-cell line infection model

The human RNase3 is a member of the RNaseA superfamily involved in host immunity. RNase3 is expressed by leukocytes and shows broad-spectrum antimicrobial activity. Together with a direct antimicrobial action, RNase3 exhibits immunomodulatory properties. Here, we have analysed the transcriptome of macrophages exposed to the wild-type protein and a catalytic-defective mutant (RNase3-H15A). The analysis of differently expressed genes (DEGs) in treated THP1-derived macrophages highlighted a common pro-inflammatory "core-response" independent of the protein ribonucleolytic activity. Network analysis identified the epidermal growth factor receptor (EGFR) as the main central regulatory protein. Expression of selected DEGs and MAPK phosphorylation were inhibited by an anti-EGFR antibody. Structural analysis suggested that RNase3 activates the EGFR pathway by direct interaction with the receptor. Besides, we identified a subset of DEGs related to the protein ribonucleolytic activity, characteristic of virus infection response. Transcriptome analysis revealed an early pro-inflammatory response, not associated to the protein catalytic activity, followed by a late activation in a ribonucleolytic-dependent manner. Next, we demonstrated that overexpression of macrophage endogenous RNase3 protects the cells against infection by Mycobacterium aurum and the human respiratory syncytial virus. Comparison of cell infection profiles in the presence of Erlotinib, an EGFR inhibitor, revealed that the receptor activation is required for the antibacterial but not for the antiviral protein action. Moreover, the DEGs related and unrelated to the protein catalytic activity are associated to the immune response to bacterial and viral infection, respectively. We conclude that RNase3 modulates the macrophage defence against infection in both catalytic-dependent and independent manners.

Targeting eosinophils in respiratory diseases: Biological axis, emerging therapeutics and treatment modalities

Eosinophils are bi-lobed, multi-functional innate immune cells with diverse cell surface receptors that regulate local immune and inflammatory responses. Several inflammatory and infectious diseases are triggered with their build up in the blood and tissues. The mobilization of eosinophils into the lungs is regulated by a cascade of processes guided by Th2 cytokine generating T-cells. Recruitment of eosinophils essentially leads to a characteristic immune response followed by airway hyperresponsiveness and remodeling, which are hallmarks of chronic respiratory diseases. By analysing the dynamic interactions of eosinophils with their extracellular environment, which also involve signaling molecules and tissues, various therapies have been invented and developed to target respiratory diseases. Having entered clinical testing, several eosinophil targeting therapeutic agents have shown much promise and have further bridged the gap between theory and practice. Moreover, researchers now have a clearer understanding of the roles and mechanisms of eosinophils. These factors have successfully assisted molecular biologists to block specific pathways in the growth, migration and activation of eosinophils. The primary purpose of this review is to provide an overview of the eosinophil biology with a special emphasis on potential pharmacotherapeutic targets. The review also summarizes promising eosinophil-targeting agents, along with their mechanisms and rationale for use, including those in developmental pipeline, in clinical trials, or approved for other respiratory disorders.

Serum eosinophil cationic protein: a prognostic factor for early postoperative recurrence of nasal polyps

BACKGROUND

The objective of this work was to assess the efficacy of serum eosinophil cationic protein (ECP) concentration in predicting early postoperative recurrence in patients with chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODS

We prospectively enrolled CRSwNP patients to receive bilateral functional endoscopic sinus surgery (FESS) and followed them for 1 year. Serum ECP level was measured within 1 week before surgery. Demographics and associated medical factors were analyzed with the surgical outcome, and nasal polyp histology was microscopically examined.

RESULTS

Overall, 58 patients met the inclusion criteria and underwent FESS. After at least a 1-year follow-up period, 9 patients had postoperative recurrence, with significantly higher serum ECP levels (p = 0.030). Receiver operating characteristic curve analysis showed the optimal cutoff level of serum ECP concentration for predicting the postoperative recurrence of nasal polyps was 21.8 µg/L (p = 0.030). Regardless of atopy status and histology type, logistic regression analysis showed that a higher ECP level was the sole significant factor related to early postoperative recurrence of nasal polyps (odds ratio, 54.8; p = 0.014). Cox proportional hazard regression analysis revealed that the hazard ratio of CRSwNP patients with an ECP level of >21.8 µg/L resulting in early postoperative recurrence was 7.6 (p = 0.011).

CONCLUSION

Serum ECP appears to be a feasible predictor for early postoperative recurrence of nasal polyps. CRSwNP patients with preoperative serum ECP levels of ≥21.8 µg/L had an approximately 55-fold increased risk of early recurrence. CRSwNP patients with higher preoperative serum ECP levels should be closely monitored within the first year after surgery.

Inducing type 2 immune response, induction of angiogenesis, and anti-bacterial and anti-inflammatory properties make Lacto-n-Neotetraose (LNnT) a therapeutic choice to accelerate the wound healing process

The healing process of non-healing and full-thickness wounds is currently facing some serious challenges. In such ulcers, losing a large part of skin causes a chronic infection due to the entrance of various pathogens in the wound bed. Moreover, poor vascularization, uncontrolled inflammation, and delayed re-epithelialization increase the healing time in patients suffering from such wounds. In this light, tissue engineering provides a wide range of strategies using a variety of biomaterials, biofactors and stem cells to decrease the healing time and restore the function of the damaged site. A suitable wound healing agent should possess some critical parameters such as inducing re-epithelialization, anti-inflammatory and anti-bacterial properties, and angiogenic capability. The Lacto-n-Neotetraose (LNnT) with chemical formula C26H45NO21 is an oligosaccharide present in human milk and soluble antigens extracted from Schistosoma mansoni eggs. It is reported that LNnT induces type 2 immune response (Th2 immunity). Th2 immunity promotes re-epithelialization, angiogenesis and wound contraction by recruiting the cells which produce Th2-related cytokines. Moreover, LNnT shows some special characteristics such as angiogenic capability, anti-inflammatory, and anti-bacterial effects which can address the mentioned challenges in the treatment of non-healing and full-thickness wounds. Here, we hypothesize that utilizing LNnT is an appropriate biofactor which would improve the healing process in full-thickness and non-healing wounds.

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.

The Biology of Eosinophils and Their Role in Asthma

This review will describe the structure and function of the eosinophil. The roles of several relevant cell surface molecules and receptors will be discussed. We will also explore the systemic and local processes triggering eosinophil differentiation, maturation, and migration to the lungs in asthma, as well as the cytokine-mediated pathways that result in eosinophil activation and degranulation, i.e., the release of multiple pro-inflammatory substances from eosinophil-specific granules, including cationic proteins, cytokines, chemokines growth factors, and enzymes. We will discuss the current understanding of the roles that eosinophils play in key asthma processes such as airway hyperresponsiveness, mucus hypersecretion, and airway remodeling, in addition to the evidence relating to eosinophil–pathogen interactions within the lungs.

Spectrum of Eosinophilic End-Organ Manifestations

Eosinophil-associated disorders can affect practically all tissues and organs in the body, either individually or in combination. This article provides an overview of end-organ manifestations of eosinophilia and discusses selected organ systems, including the upper and lower respiratory, cardiovascular, gastrointestinal, nervous, dermatologic, and renal systems. Mechanisms by which eosinophilia leads to end-organ damage are also considered.

Cytokine networking of innate immunity cells: a potential target of therapy

Innate immune cells, particularly macrophages and epithelial cells, play a key role in multiple layers of immune responses. Alarmins and pro-inflammatory cytokines from the IL (interleukin)-1 and TNF (tumour necrosis factor) families initiate the cascade of events by inducing chemokine release from bystander cells and by the up-regulation of adhesion molecules required for transendothelial trafficking of immune cells. Furthermore, innate cytokines produced by dendritic cells, macrophages, epithelial cells and innate lymphoid cells seem to play a critical role in polarization of helper T-cell cytokine profiles into specific subsets of Th1/Th2/Th17 effector cells or regulatory T-cells. Lastly, the innate immune system down-regulates effector mechanisms and restores homoeostasis in injured tissue via cytokines from the IL-10 and TGF (transforming growth factor) families mainly released from macrophages, preferentially the M2 subset, which have a capacity to induce regulatory T-cells, inhibit the production of pro-inflammatory cytokines and induce healing of the tissue by regulating extracellular matrix protein deposition and angiogenesis. Cytokines produced by innate immune cells represent an attractive target for therapeutic intervention, and multiple molecules are currently being tested clinically in patients with inflammatory bowel disease, rheumatoid arthritis, systemic diseases, autoinflammatory syndromes, fibrosing processes or malignancies. In addition to the already widely used blockers of TNFα and the tested inhibitors of IL-1 and IL-6, multiple therapeutic molecules are currently in clinical trials targeting TNF-related molecules [APRIL (a proliferation-inducing ligand) and BAFF (B-cell-activating factor belonging to the TNF family)], chemokine receptors, IL-17, TGFβ and other cytokines.

Use of discriminant analysis in assessing pulmonary function worsening in patients with sarcoidosis by a panel of inflammatory biomarkers

OBJECTIVES AND DESIGN

To date, no sufficiently sensitive and specific single marker has been found to predict the clinical course of sarcoidosis. We designed a cohort study to investigate whether a panel of biomarkers measured in bronchoalveolar lavage (BAL) and peripheral blood could help predict pulmonary function worsening during the clinical course of sarcoidosis.

METHODS

We analyzed 30 individuals with histologically proven sarcoidosis. At baseline, participants underwent pulmonary function tests (PFTs), fiberoptic bronchoscopy and radiological investigations. BAL and blood cellular profiles were obtained from all individuals and six pro-inflammatory molecules were quantified in BAL and serum. PFTs were performed at follow-up visits over a 2-year period. Using discriminant function analysis, a canonical variable was generated to optimize the accuracy of selected variables in predicting pulmonary function worsening and was validated on a subset of nine consecutive individuals with sarcoidosis.

RESULTS

A combination of 6 markers from BAL was able to predict pulmonary function worsening in 96 % of patients [95 % confidence interval (CI) 84.4-99.81]. We validated the generated formula on a group of nine patients with sarcoidosis, obtaining 77.8 % correct classification (95 % CI 45.3-93.7).

CONCLUSIONS

Our results show that a combinational approach could contribute to identifying individuals likely to experience pulmonary function worsening, thus helping to decide the correct therapeutic strategies.

Eosinophil associated genes in the inflammatory bowel disease 4 region: Correlation to inflammatory bowel disease revealed

AIM: To study the association between inflammatory bowel disease (IBD) and genetic variations in eosinophil protein X (EPX) and eosinophil cationic protein (ECP).

METHODS: DNA was extracted from ethylene diamine tetraacetic acid blood of 587 patients with Crohn’s disease (CD), 592 with ulcerative colitis (UC) and 300 healthy subjects. The EPX405 (G > C, rs2013109), ECP434 (G > C, rs2073342) and ECP562 (G > C, rs2233860) gene polymorphisms were analysed, by the 5’-nuclease allelic discrimination assay. For determination of intracellular content of EPX and ECP in granulocytes, 39 blood samples was collected and extracted with a buffer containing cetyltrimethylammonium bromide. The intracellular content of EPX was analysed using an enzyme-linked immunosorbent assay. The intracellular content of ECP was analysed with the UniCAP^® system as described by the manufacturer. Statistical tests for calculations of results were χ² test, Fisher’s exact test, ANOVA, Student-Newman-Keuls test, and Kaplan-Meier survival curve with Log-rank test for trend, the probability values of P < 0.05 were considered statistically significant.

RESULTS: The genotype frequency for males with UC and with an age of disease onset of ≥ 45 years (n = 57) was for ECP434 and ECP562, GG = 37%, GC = 60%, CC = 4% and GG = 51%, GC = 49%, CC = 0% respectively. This was significantly different from the healthy subject’s genotype frequencies of ECP434 (GG = 57%, GC = 38%, CC = 5%; P = 0.010) and ECP562 (GG = 68%, GC = 29%,CC = 3%; P = 0.009). The genotype frequencies for females, with an age of disease onset of ≥ 45 years with CD (n = 62), was for the ECP434 and ECP562 genotypes GG = 37%, GC = 52%, CC = 11% and GG = 48%, GC = 47% and CC = 5% respectively. This was also statistically different from healthy controls for both ECP434 (P = 0.010) and ECP562 (P = 0.013). The intracellular protein concentration of EPX and ECP was calculated in μg/10⁶ eosinophils and then correlated to the EPX 405 genotypes. The protein content of EPX was highest in the patients with the CC genotype of EPX405 (GG = 4.65, GC = 5.93, and CC = 6.57) and for ECP in the patients with the GG genotype of EPX405 (GG = 2.70, GC = 2.47 and CC = 1.90). ANOVA test demonstrated a difference in intracellular protein content for EPX (P = 0.009) and ECP (P = 0.022). The age of disease onset was linked to haplotypes of the EPX405, ECP434 and ECP562 genotypes. Kaplan Maier curve showed a difference between haplotype distributions for the females with CD (P = 0.003). The highest age of disease onset was seen in females with the EPX405CC, ECP434GC, ECP562CC haplotype (34 years) and the lowest in females with the EPX405GC, ECP434GC, ECP562GG haplotype (21 years). For males with UC there was also a difference between the highest and lowest age of the disease onset (EPX405CC, ECP434CC, ECP562CC, mean 24 years vs EPX405GC, ECP434GC, ECP562GG, mean 34 years, P = 0.0009). The relative risk for UC patients with ECP434 or ECP562-GC/CC genotypes to develop dysplasia/cancer was 2.5 (95%CI: 1.2-5.4, P = 0.01) and 2.5 (95%CI: 1.1-5.4, P = 0.02) respectively, compared to patients carrying the GG-genotypes.

CONCLUSION: Polymorphisms of EPX and ECP are associated to IBD in an age and gender dependent manner, suggesting an essential role of eosinophils in the pathophysiology of IBD.

Analysing the eosinophil cationic protein--a clue to the function of the eosinophil granulocyte

Eosinophil granulocytes reside in respiratory mucosa including lungs, in the gastro-intestinal tract, and in lymphocyte associated organs, the thymus, lymph nodes and the spleen. In parasitic infections, atopic diseases such as atopic dermatitis and asthma, the numbers of the circulating eosinophils are frequently elevated. In conditions such as Hypereosinophilic Syndrome (HES) circulating eosinophil levels are even further raised. Although, eosinophils were identified more than hundred years ago, their roles in homeostasis and in disease still remain unclear. The most prominent feature of the eosinophils are their large secondary granules, each containing four basic proteins, the best known being the eosinophil cationic protein (ECP). This protein has been developed as a marker for eosinophilic disease and quantified in biological fluids including serum, bronchoalveolar lavage and nasal secretions. Elevated ECP levels are found in T helper lymphocyte type 2 (atopic) diseases such as allergic asthma and allergic rhinitis but also occasionally in other diseases such as bacterial sinusitis. ECP is a ribonuclease which has been attributed with cytotoxic, neurotoxic, fibrosis promoting and immune-regulatory functions. ECP regulates mucosal and immune cells and may directly act against helminth, bacterial and viral infections. The levels of ECP measured in disease in combination with the catalogue of known functions of the protein and its polymorphisms presented here will build a foundation for further speculations of the role of ECP, and ultimately the role of the eosinophil.

The coding ECP 434(G>C) gene polymorphism determines the cytotoxicity of ECP but has minor effects on fibroblast-mediated gel contraction and no effect on RNase activity

Eosinophil cationic protein (ECP) is a secretory protein of the eosinophil granulocyte, a cell involved in innate immunity. Functional studies have implicated ECP in numerous processes, such as tissue remodeling in allergic inflammation and cytotoxicity toward a variety of pathogens. Recent genetic studies have suggested that the ECP 434(G>C) polymorphism resulting in an arg97thr substitution would alter the function of ECP in vivo. Functional (in vitro) studies of ECP up until now have either been conducted with native preparations containing an unknown mixture of the ECP(97arg) and ECP(97thr) variants, or with recombinant proteins. Therefore, we have now for the first time extracted the native ECP(97arg) and ECP(97thr) variants from healthy blood donors and tested them functionally in vitro. Our results show that the arg97thr shift dramatically alters the cytotoxic capacity of ECP in vitro; the tested ECP(97arg) variants were cytotoxic toward the small-cell lung cancer cell line NCI-H69, whereas ECP(97thr) was noncytotoxic. RNase activity was unaffected by the arg97thr substitution. Both ECP(97arg) and ECP(97thr) stimulated fibroblast-mediated collagen gel contraction, an experimental model, which depicts wound healing, in a dose-dependent manner. In conclusion, our results demonstrate that the ECP 434(G>C) gene polymorphism affects the functional properties of native ECP, but also that there is a dissociation between different biological activities; the arg97thr substitution impairs the cytotoxic potential of ECP but less the gel contraction and not at all the RNase activity.