Cationic proteins from eosinophils bind bone morphogenetic protein receptors promoting vascular calcification and atherogenesis.

AIMS: Blood eosinophil count and eosinophil cationic protein (ECP) concentration are risk factors of cardiovascular diseases. This study tested whether and how eosinophils and ECP contribute to vascular calcification and atherogenesis. METHODS AND RESULTS: Immunostaining revealed eosinophil accumulation in human and mouse atherosclerotic lesions. Eosinophil deficiency in ΔdblGATA mice slowed atherogenesis with increased lesion smooth muscle cell (SMC) content and reduced calcification. This protection in ΔdblGATA mice was muted when mice received donor eosinophils from wild-type (WT), Il4-/-, and Il13-/- mice or mouse eosinophil-associated-ribonuclease-1 (mEar1), a murine homologue of ECP. Eosinophils or mEar1 but not interleukin (IL) 4 or IL13 increased the calcification of SMC from WT mice but not those from Runt-related transcription factor-2 (Runx2) knockout mice. Immunoblot analyses showed that eosinophils and mEar1 activated Smad-1/5/8 but did not affect Smad-2/3 activation or expression of bone morphogenetic protein receptors (BMPR-1A/1B/2) or transforming growth factor (TGF)-ß receptors (TGFBR1/2) in SMC from WT and Runx2 knockout mice. Immunoprecipitation showed that mEar1 formed immune complexes with BMPR-1A/1B but not TGFBR1/2. Immunofluorescence double-staining, ligand binding, and Scatchard plot analysis demonstrated that mEar1 bound to BMPR-1A and BMPR-1B with similar affinity. Likewise, human ECP and eosinophil-derived neurotoxin (EDN) also bound to BMPR-1A/1B on human vascular SMC and promoted SMC osteogenic differentiation. In a cohort of 5864 men from the Danish Cardiovascular Screening trial and its subpopulation of 394 participants, blood eosinophil counts and ECP levels correlated with the calcification scores of different arterial segments from coronary arteries to iliac arteries. CONCLUSION: Eosinophils release cationic proteins that can promote SMC calcification and atherogenesis using the BMPR-1A/1B-Smad-1/5/8-Runx2 signalling pathway.

Eosinophil Granule Proteins Involvement in Acute Appendicitis-An Allergic Disease?

Several pieces of evidence point to an allergic component as a trigger of acute appendicitis. As the Th2 immune response is characterized by eosinophil mobilization to the target organ and release of their cationic granule proteins, it is reasonable to investigate if the degranulation of eosinophils could be associated with the local injury. The primary aim of this study is to evaluate the participation of eosinophils granules proteins in acute appendicitis, both at local and systemic levels and the secondary aim is to evaluate the diagnostic accuracy of eosinophils granules proteins for the detection of acute appendicitis, as well as for distinguishing between complicated and uncomplicated acute appendicitis. Eosinophil-derived neurotoxin (EDN), eosinophil cationic protein (ECP) and eosinophil peroxidase (EP) are the most well-known eosinophil granule proteins. From August 2021 to April 2022, we present a prospective single-center study to evaluate the EDN, ECP, and EP concentrations simultaneously in appendicular lavage fluid (ALF) and the serum of 22 patients with acute phlegmonous appendicitis (APA), 24 with acute gangrenous appendicitis (AGA), and 14 normal controls. Concerning EDN, no differences were found between groups. ECP concentrations in ALF and serum were significantly higher in the histologically confirmed acute appendicitis compared to the control groups (p < 0.0001 and p < 0.0001, respectively). In ALF, no differences were found between ECP levels in APA: 38.85 ng/mL (IQR 26.50-51.77) and AGA 51.55 ng/mL (IQR 39.55-70.09) groups (p = 0.176). In the serum, no difference was found between ECP levels at APA: 39 ng/mL (IQR 21.30-56.90) and AGA: 51.30 ng/mL (IQR 20.25-62.59) (p = 0.100). For EP, the concentrations in ALF (p < 0.001) and serum (p < 0.001) were both higher in acute appendicitis compared to the control. In ALF, no difference was found between APA: 240.28 ng/mL (IQR 191.2-341.3) and AGA: 302.5 (IQR 227.7-535.85) (p = 0.236). In the serum, no differences were found between APA: 158.4 ng/mL (IQR 111.09-222.1) and AGA: 235.27 (IQR 192.33-262.51) (p = 0.179). Globally, the ALF concentrations were higher than serum concentrations, reflecting an intense inflammatory local reaction in AA. The optimal ECP cut-off for discriminating between acute appendicitis and the controls was >11.41 ng/mL, with a sensitivity of 93.5%, but with a specificity for identifying appendicitis of 21.4%, good discriminative power (AUC = 0.880). For EP, the optimal cut-off was >93.20 ng/mL, with a sensitivity of 87%, but with a specificity of 14.3% (AUC = 0.901), excellent discriminative power. For the diagnosis of perforated AA, the discriminative power of ECP and EP serum concentrations are weak (AUC = 0.562 and AUC = 0.664, respectively). Concerning the presence of peritonitis, the discriminative power of ECP and EP serum concentrations is acceptable, respectively: AUC = 0.724 and AUC = 0.735. Serum levels of EDN (p = 0.119), ECP (p = 0.586) and EP (p = 0.08) in complicated appendicitis were similar to uncomplicated appendicitis. Serum concentrations of ECP and EP can be added to decision-making AA diagnosis. A Th2-type immune response is present in AA. These data bring forward the role of an allergic reaction in the pathogenesis of acute appendicitis.

Eosinophilic cationic protein (ECP) in the clinical work-up of chronic cough.

BACKGROUND: Chronic cough is a common symptom, addressed in the clinical setting by empirical treatment together with some laboratory investigations. The aim of the present study was to investigate the value of testing eosinophilic cationic protein (ECP) serum levels combined with other diagnostic procedures and empirical treatment in the diagnostic workup of chronic cough. METHODS: In this study, we evaluated 194 patients with chronic cough. No subject had received any anti-inflammatory treatment before clinical evaluation, and none was an active smoker. ECP was measured with a commercially available fluoroenzyme immunoassay and results were expressed as µg/L. RESULTS: The analysis of variance showed that mean ECP level differs among the various diagnosis categories (P<0.001). Mean ECP level was significantly higher in asthmatic patients, particularly in the active disease. CONCLUSIONS: Serum ECP concentration could represent a useful biomarker in the clinical work-up of chronic cough, managing to differentiate asthma from other chronic disorders.

Identification of novel genes influencing eosinophil-specific protein levels in asthma families.

BACKGROUND: Eosinophils play a key role in the asthma allergic response by releasing cytotoxic molecules such as eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) that generate epithelium damages. OBJECTIVE: We sought to identify genetic variants influencing ECP and EDN levels in asthma-ascertained families. METHODS: We performed univariate and bivariate genome-wide association analyses of ECP and EDN levels in 1018 subjects from the EGEA study with follow-up in 153 subjects from the Saguenay-Lac-Saint-Jean study and combined the results of these 2 studies through meta-analysis. We then conducted Bayesian statistical fine mapping together with quantitative trait locus and functional annotation analyses to identify the most likely functional genetic variants and candidate genes. RESULTS: We identified 5 genome-wide significant loci (P &lt; 5 × 10^-8) including 7 distinct signals associated with ECP and/or EDN levels. The genes targeted by our fine mapping and functional search include RNASE2 and RNASE3 (14q11), which encode EDN and ECP, respectively, and 4 other genes that regulate ECP and EDN levels. These 4 genes were JAK1 (1p31), a transcription factor that plays a key role in the immune response and acts as a potential therapeutic target for eosinophilic asthma; ARHGAP25 (2p13), which is involved in leukocyte recruitment to inflammatory sites; NDUFA4 (7p21), which encodes a component of the mitochondrial respiratory chain and is involved in cellular response to stress; and CTSL (9q22), which is involved in immune response, extracellular remodeling, and allergic inflammation. CONCLUSION: Analysis of specific phenotypes produced by eosinophils allows the identification of genes that play a major role in allergic response and inflammation, and offers potential therapeutic targets for asthma.

Detection of Eosinophils in Tissue Sections by Immunohistochemistry.

Eosinophils are bone marrow-derived hematopoietic cells which represent a small subset in the peripheral blood, and under homeostatic conditions predominantly reside in certain organs, such as the gastrointestinal tract. However, eosinophil numbers increase both in the peripheral blood and tissues during allergic inflammation, parasitic infestation, drug reactions, vasculitides, as well as certain hematopoietic neoplasms. Their presence in tissues can be detected by hematoxylin and eosin staining; however, this may be challenging particularly at times of activation and/or degranulation, e.g., during allergic lung inflammation. Thus, detection of eosinophils and/or their released granule proteins is significantly enhanced by immunohistochemistry. This chapter describes methods for the detection of mouse or human eosinophils by using granule protein-specific antibodies in formalin-fixed paraffin-embedded tissue.

Essential Role of Enzymatic Activity in the Leishmanicidal Mechanism of the Eosinophil Cationic Protein (RNase 3).

The recruitment of eosinophils into Leishmania lesions is frequently associated with a favorable evolution. A feasible effector for this process is eosinophil cationic protein (ECP, RNase 3), one of the main human eosinophil granule proteins, endowed with a broad spectrum of antimicrobial activity, including parasites. ECP was active on Leishmania promastigotes and axenic amastigotes (LC50's = 3 and 16 µM, respectively) but, in contrast to the irreversible membrane damage caused on bacteria and reproduced by its N-terminal peptides, it only induced a mild and transient plasma membrane destabilization on Leishmania donovani promastigotes. To assess the contribution of RNase activity to the overall leishmanicidal activity of ECP, parasites were challenged in parallel with a single-mutant version, ECP-H15A, devoid of RNase activity, that fully preserves the conformation and liposome permeabilization ability. ECP-H15A showed a similar uptake to ECP on promastigotes, but with higher LC50's (>25 µM) for both parasite stages. ECP-treated promastigotes showed a degraded RNA pattern, absent in ECP-H15A-treated samples. Moreover ECP, but not ECP-H15A, reduced more than 2-fold the parasite burden of infected macrophages. Altogether, our results suggest that ECP enters the Leishmania cytoplasm by an endocytic pathway, ultimately leading to RNA degradation as a key contribution to the leishmanicidal mechanism. Thus, ECP combines both membrane destabilization and enzymatic activities to effect parasite killing. Taken together, our data highlight the microbicidal versatility of ECP as an innate immunity component and support the development of cell-penetrating RNases as putative leishmanicidal agents.

Eosinophils in Health and Disease: A State-of-the-Art Review.

Eosinophils play a homeostatic role in the body's immune responses. These cells are involved in combating some parasitic, bacterial, and viral infections and certain cancers and have pathologic roles in diseases including asthma, chronic rhinosinusitis with nasal polyps, eosinophilic gastrointestinal disorders, and hypereosinophilic syndromes. Treatment of eosinophilic diseases has traditionally been through nonspecific eosinophil attenuation by use of glucocorticoids. However, several novel biologic therapies targeting eosinophil maturation factors, such as interleukin (IL)-5 and the IL-5 receptor or IL-4/IL-13, have recently been approved for clinical use. Despite the success of biologic therapies, some patients with eosinophilic inflammatory disease may not achieve adequate symptom control, underlining the need to further investigate the contribution of patient characteristics, such as comorbidities and other processes, in driving ongoing disease activity. New research has shown that eosinophils are also involved in several homeostatic processes, including metabolism, tissue remodeling and development, neuronal regulation, epithelial and microbiome regulation, and immunoregulation, indicating that these cells may play a crucial role in metabolic regulation and organ function in healthy humans. Consequently, further investigation is needed into the homeostatic roles of eosinophils and eosinophil-mediated processes across different tissues and their varied microenvironments. Such work may provide important insights into the role of eosinophils not only under disease conditions but also in health. This narrative review synthesizes relevant publications retrieved from PubMed informed by author expertise to provide new insights into the diverse roles of eosinophils in health and disease, with particular emphasis on the implications for current and future development of eosinophil-targeted therapies.

Performance of Eosinophil Cationic Protein as a Biomarker in Asthmatic Children.

BACKGROUND: Although blood eosinophils are a frequently used marker of type 2 inflammation in children with asthma, their sensitivity is relatively poor. Additional markers of type 2 inflammation are needed. OBJECTIVE: We hypothesized that plasma concentrations of eosinophil cationic protein (ECP), a marker of eosinophil activation, would be useful for detection of type 2 inflammation and would predict poorer asthma outcomes over 1 year. METHODS: Children and adolescents 6 through 17 years (N = 256) with confirmed asthma completed a baseline visit and a follow-up visit at 12 months. A subset also underwent systemic corticosteroid responsiveness testing with intramuscular triamcinolone. Outcome measures at 12 months included uncontrolled asthma, lung function, and asthma exacerbations treated with systemic corticosteroids. RESULTS: Plasma ECP concentrations ranged from 0.03 to 413.61 ng/mL (median, 6.95 ng/mL) and were consistently associated with other markers of type 2 inflammation. At baseline, children in the highest ECP tertile had poorer asthma control, more airflow limitation, and more exacerbations, but also had greater symptom improvement with intramuscular triamcinolone. At 12 months, associations between the highest ECP tertile and exacerbations, but not lung function or asthma control, persisted after covariate adjustment. However, the sensitivity of ECP was modest and was not markedly different from that of blood eosinophil counts. CONCLUSION: Plasma ECP concentrations may be a useful marker of type 2 inflammation in children and may help identify those children at highest risk for recurrent exacerbations who could benefit from corticosteroid treatment. However, additional markers may be needed to improve sensitivity for outcome detection.

Eosinophils in the pathogenesis of pancreatic disorders.

Eosinophils comprise approximately 1-4% of total blood leukocytes that reside in the intestine, bone marrow, mammary gland, and adipose tissues to maintain innate immunity in healthy individuals. Eosinophils have four toxic granules known as major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil peroxidase (EPO), and eosinophil-derived neurotoxin (EDN), and upon degranulation, these granules promote pathogenesis of inflammatory diseases like allergy, asthma, dermatitis, and gastrointestinal disorders. Additionally, the role of eosinophils is underscored in exocrine disorders including pancreatitis. Chronic pancreatitis (CP) is an inflammatory disorder that occurs due to the alcohol consumption, blockage of the pancreatic duct, and trypsinogen mutation. Eosinophil levels are detected in higher numbers in both CP and pancreatic cancer patients compared with healthy individuals. The mechanistic understanding of chronic inflammation-induced pancreatic malignancy has not yet been reached and requires further exploration. This review provides a comprehensive summary of the epidemiology, pathophysiology, evaluation, and management of eosinophil-associated pancreatic disorders and further summarizes current evidence regarding risk factors, pathophysiology, clinical features, diagnostic evaluation, treatment, and prognosis of eosinophilic pancreatitis (EP) and pancreatic cancer.

Molecular Biology of Eosinophils: Introduction.

The eosinophil is an enigmatic cell with a continuing ability to fascinate. A considerable history of research endeavor on eosinophil biology stretches from the present time back to the nineteenth century. Perhaps one of the most fascinating aspects of the eosinophil is how accumulating knowledge has changed the perception of its function from passive bystander, modulator of inflammation, to potent effector cell loaded with histotoxic substances through to more recent recognition that it can act as both a positive and negative regulator of complex events in both innate and adaptive immunity. This book consists of chapters written by experts in the field of eosinophil biology that provide comprehensive clearly written protocols for techniques designed to underpin research into the function of the eosinophil in health and disease.

Observation and Quantification of Eosinophil Motility.

Eosinophils are important for tissue homeostasis and host responses to pathogens and allergens. The impact of eosinophils within tissues depends in part on whether cytotoxic proteins in crystalloid granules are released. Determinants of eosinophil motility and loss of granule contents are incompletely understood. The goal of this chapter is to present methods to study the effects of potential mediators on purified human blood eosinophils interacting with adhesive proteins found in extracellular matrix. We show that differential interference contrast video-enhanced microscopy and a bead-clearing assay provide complementary information about how different mediator-adhesive protein combinations direct eosinophil motility and granule fate. The former method is rich in information about cell shape, pattern of movement, and state of granules whereas the latter method lends itself to quantification and interrogation of multiple conditions in replicate.

Antimicrobial Activity of Human Eosinophil Granule Proteins.

Eosinophils secrete a number of proinflammatory mediators that include cytokines, chemokines, and granule proteins which are responsible for the initiation and maintenance of inflammatory responses. The eosinophil granule proteins, ECP, EDN, MBP, and EPO, possess antimicrobial activity against bacteria, helminths, protozoa, and viruses. In this chapter, we describe various assays used to detect and quantitate the antimicrobial activities of eosinophil granule proteins, particularly ECP and EDN. We have taken a model organism for each assay and described the method for antiviral, antihelminthic, antiprotozoan, and antibacterial activity of purified eosinophil granule proteins.

Experimental Modeling of Eosinophil-Associated Diseases.

Eosinophils are an important subtype of leukocytes derived from bone marrow multipotent hematopoietic stem cells and represent about 1% of leukocytes in circulating blood. In homeostatic conditions, eosinophils reside in the intestine to maintain the balance of immune responses by communicating with gut microbes without causing inflammation. However, under the stressed or diseased condition, eosinophils degranulate, releasing their granule-derived cytotoxic proteins that are involved in inflammatory responses. Various eosinophil-associated inflammatory diseases are eosinophilic esophagitis (EoE), eosinophilic gastroenteritis (EG), and eosinophilic colitis (EC), together called EGID, asthma, hypereosinophilic syndrome, and eosinophilic pneumonia (EP). Eosinophil degranulation results in the release of their four toxic proteins [major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil peroxidase (EPO), and eosinophil-derived neurotoxin (EDN)] which promote disease pathogenesis. Pancreatitis is the inflammatory disease of the pancreas that arises due to blockage of the pancreatic duct, trypsinogen mutation, alcohol consumption, and repeated occurrence of pancreatitis leading to chronic pancreatitis (CP); subsequently some CP patients may also develop pancreatic cancer. The presence of eosinophils is now shown in various case reports with acute, recurrent acute, and chronic pancreatitis and pancreatic cancer indicating the role of eosinophils in the pathogenesis of various pancreatic inflammatory disorders. However, the details of eosinophil accumulation during pancreatic diseases are not well explored and need further attention. Overall, the chapter provides the current understanding of reported eosinophils associated with inflammatory diseases like EGID diseases, asthma, and pancreatic disorders, i.e., acute, chronic pancreatitis, and pancreatic cancer. This knowledge will be helpful for future studies to develop novel treatment options for the eosinophils associated diseases. Therefore, more efforts are needed to perform preclinical and clinical studies in this field for the successful development of eosinophil-targeting treatments for a variety of eosinophil-associated diseases.

Mechanisms of toxicity mediated by neutrophil and eosinophil granule proteins.

Neutrophils and eosinophils are granulocytes which are characterized by the presence of granules in the cytoplasm. Granules provide a safe storage site for granule proteins that play important roles in the immune function of granulocytes. Upon granulocytes activation, diverse proteins are released from the granules into the extracellular space and contribute to the fight against infections. In this article, we describe granule proteins of both neutrophils and eosinophils able to kill pathogens and review their anticipated mechanism of antimicrobial toxicity. It should be noted that an excess of granules protein release can lead to tissue damage of the host resulting in chronic inflammation and organ dysfunction.

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.

Prognostic significance of faecal eosinophil granule proteins in inflammatory bowel disease.

Background: Non-invasive markers for predicting relapse would be a useful tool for the management of patients with inflammatory bowel disease. Eosinophil granulocytes and their granule proteins eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) have previously been shown to reflect disease activity in Crohn's disease and ulcerative colitis.Aim: To examine the capacity of faecal ECP and EDN to predict relapse in ulcerative colitis and Crohn's disease, and to compare these proteins with faecal calprotectin.Methods: Patients with Crohn's disease (n = 49) and ulcerative colitis (n = 55) were followed prospectively until relapse or end of the two-year study period. Faecal samples were obtained every third month. The predictive value of ECP and EDN was assessed in Cox regression models.Results: In ulcerative colitis, a doubled EDN or ECP concentration was associated with a 31% and 27% increased risk of relapse, respectively. EDN levels were increased both at relapse and three months prior. By contrast, in Crohn's disease, the concentration of EDN was higher among patients in remission than in those who relapsed. Correlations between faecal calprotectin, ECP and EDN were observed in both diseases.Conclusions: We demonstrate that the risk of relapse in ulcerative colitis can be predicted by consecutively measuring faecal EDN every third month, and suggest EDN as a complementary faecal marker to calprotectin to predict future relapse in ulcerative colitis. Our finding of higher EDN in Crohn's disease-patients staying in remission than in those who relapsed indicates different functions of the protein in ulcerative colitis and Crohn's disease.

The Effect of Helminths on Granulocyte Activation: A Cluster-Randomized Placebo-Controlled Trial in Indonesia.

BACKGROUND: Eosinophils are a prominent cell type in the host response to helminths, and some evidence suggests that neutrophils might also play a role. However, little is known about the activation status of these granulocytes during helminth infection. METHODS: We analyzed the expression of eosinophil and neutrophil activation markers in peripheral blood by flow cytometry and measured serum levels of eosinophil granule proteins in 300 subjects residing in an area endemic for soil-transmitted helminths (STH). The data generated are on samples before and after 1 year of 3-monthly albendazole treatment. RESULTS: Anthelmintic treatment significantly reduced the prevalence of STH. While eosinophil numbers were significantly higher in STH-infected compared to uninfected subjects and significantly decreased following albendazole treatment, there was no effect exerted by the helminths on either eosinophil nor neutrophil activation. Although at baseline eosinophil granule protein levels were not different between STH-infected and uninfected subjects, treatment significantly reduced the levels of eosinophil-derived neurotoxin (EDN) in those infected at baseline. CONCLUSIONS: These results show that besides decreasing eosinophil numbers, anthelmintic treatment does not significantly change the activation status of eosinophils, nor of neutrophils, and the only effect seen was a reduction in circulating levels of EDN. CLINICAL TRIALS REGISTRATION: http://www.isrctn.com/ISRCTN75636394.

C­C chemokine receptor type 3 gene knockout alleviates inflammatory responses in allergic rhinitis model mice by regulating the expression of eosinophil granule proteins and immune factors.

The present study aimed to investigate the effects of C­C chemokine receptor type 3 (CCR3) gene knockout on allergic rhinitis (AR) in mice, as well as the underlying molecular mechanisms. Ovalbumin was administrated to CCR3+/+ and CCR3­/­ BALB/c mice to establish an AR model. The mice were divided into four groups: i) Normal control (CG), ii) AR model (AR), iii) CCR3 knockout CG (CCR3­/­CG) and iv) AR model with CCR3 knockout (CCR3­/­AR). Histological sections of nasal mucosae were examined by hematoxylin and eosin staining, which revealed that CCR3 knockout suppressed the invasion of inflammatory cells and relieved the damage of nasal mucosae. Peripheral blood smear and nasal­washing smears were evaluated by Wright's staining. Eosinophil (EOS) numbers in nasal mucosae, peripheral blood, and nasal washings of the various groups were ranked in the order: AR>CCR3­/­AR>CG>CCR3­/­. mRNA expression levels of CCR3, EOS peroxidase (EPO), EOS cationic protein (ECP), and major basic protein (MBP) in the peripheral serum and nasal washings were detected by reverse transcription­polymerase chain reaction. Interferon­Î³ (IFN­Î³), interleukin (IL)­4, IL­10, and immunoglobulin E (IgE) protein levels in the peripheral serum and nasal washings were investigated by ELISA. CCR3 mRNA expression was not detected in the CCR3­/­ and CCR3­/­AR groups, whereas expression levels in the AR group were markedly higher compared with expression in the CG group. Compared with the CG­associated groups (i.e., the CG and CCR3­/­CG groups), the levels of EPO, ECP, MBP, IL­4, and IgE were significantly increased in the AR­associated groups (that is, R and CCR3­/­AR). In addition, the CCR3­/­AR group mice produced significantly lower levels of EPO, ECP, MBP, IL­4 and IgE compared with the AR group, whereas the expression levels of IFN­Î³ and IL­10 were increased. CCR3 gene knockout may alleviate EOS invasion and the inflammatory response in AR model mice by reducing the expression levels of EPO, ECP, MBP, IL­4, and IgE, and increasing the expression of IL­10 and IFN­Î³.

The role of neutrophil granule proteins in neuroinflammation and Alzheimer's disease.

Neutrophils are the innate immune system's first line of defense. Neutrophils play a critical role in protecting the host against infectious pathogens, resolving sterile injuries, and mediating inflammatory responses. The granules of neutrophils and their constituent proteins are central to these functions. Although neutrophils may exert a protective role upon acute inflammatory conditions or insults, continued activity of neutrophils in chronic inflammatory diseases can contribute to tissue damage. Neutrophil granule proteins are involved in a number of chronic inflammatory conditions and diseases. However, the functions of these proteins in neuroinflammation and chronic neuroinflammatory diseases, including Alzheimer's disease (AD), remain to be elucidated. In this review, we discuss recent findings from our lab and others that suggest possible functions for neutrophils and the neutrophil granule proteins, CAP37, neutrophil elastase, and cathepsin G, in neuroinflammation, with an emphasis on AD. These findings reveal that neutrophil granule proteins may exert both neuroprotective and neurotoxic effects. Further research should determine whether neutrophil granule proteins are valid targets for therapeutic interventions in chronic neuroinflammatory diseases.