Human eosinophils show chemotaxis to lymphoid chemokines and exhibit antigen-presenting-cell-like properties upon stimulation with IFN-gamma, IL-3 and GM-CSF

Significance of Indoleamine 2,3-Dioxygenase Expression in the Immunological Response of Kidney Graft Recipients

Kidney transplantation is unquestionably the most advantageous and preferred treatment when patients with end-stage renal disease are considered. It does have a substantially positive influence on both the quality and expectancy of their lives. Thus, it is quintessential to extend the survival rate of kidney grafts. On account of T-cell-focused treatment, this is being exponentially achieved. The kynurenine pathway, as an immunosuppressive apparatus, and indoleamine 2,3-dioxygenase (IDO1), as its main regulator, are yet to be exhaustively explored. This review presents the recognised role of IDO1 and its influence on the kynurenine pathway, with emphasis on immunosuppression in kidney transplant protection.

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.

Docosahexaenoic Acid Inhibits Proliferation of EoL-1 Leukemia Cells and Induces Cell Cycle Arrest and Cell Differentiation

Τhe effect of docosahexaenoic acid (DHA, an omega-3 polyunsaturated fatty acid) upon the proliferation of EoL-1 (Eosinophilic leukemia) cell line was assessed, while additional cellular events during the antiproliferative action were recorded. DHA inhibited EoL-1 cells growth dose-dependently by inducing growth arrest at G0/1 phase of the cell cycle. After DHA addition to the cells, the expression of MYC oncogene was decreased, PTAFR-mRNA overexpression was observed which was used as a marker of differentiation, and PLA2G4A-mRNA increase was recorded. The enzymatic activities of phospholipase A₂ (PLA₂), a group of hydrolytic enzymes, whose action precedes and leads to PAF biosynthesis through the remodeling pathway, as well as platelet activating factor acetylhydrolase (PAFAH) which hydrolyses and deactivates PAF, were also measured. DHA had an effect on the levels of both the intracellular and secreted activities of PLA₂ and PAFAH. The inflammatory cytokines IL-6 and TNF-α were also detected in high levels. In conclusion, DHA-induced EoL-1 cells differentiation was correlated with downregulation of MYC oncogene, overexpression of PTAFR and PLA2G4A-mRNAs, increase of the inflammatory cytokines production, and alteration of the enzymatic activities that regulate PAF levels. DHA is a natural substance and the understanding of its action on EoL-1 cells on molecular level could be useful in further investigation as a future therapeutic tool against F/P ⁺ hypereosinophilic syndrome.

Leukotriene D4 induces chemotaxis in human eosinophilc cell line, EoL-1 cells via CysLT1 receptor activation

Numerous reports have shown that cysteinyl leukotrienes (CysLTs) contribute to tissue accumulation of eosinophils in allergic airway inflammation. To date, only a few studies have reported that CysLTs promote chemotactic activity of human eosinophils in vitro. The purpose of this study was to investigate whether CysLTs promote chemotaxis in the human eosinophilic cell line, EoL-1. EoL-1 cells were induced to differentiate into mature eosinophil-like cells via incubation with butyric acid and cytokines (IL-3, IL-5 and GM-CSF). The chemotactic activity of the differentiated EoL-1 cells was assessed using the commercial cell migration assay kit. LTD₄ elicited dose-related chemotactic activity in the differntiated EoL-1 cells in the range of 1–100 nM. A typical bell-shaped dose-response curve was observed with optimal activity at 10 nM. The chemotactic activity elicited by LTD₄ (10 nM) was significantly inhibited by montelukast (control, 345 ± 19.2 × 10³ RFU; LTD₄ 10 nM alone, 511 ± 39.2 × 10³ RFU; LTD₄ 10 nM plus montelukast 100 nM, 387 ± 28.2 × 10³ RFU). LTD₄ induces migration in eosinophilic cells via activation of CysLT1 receptor. The present in vitro model may be useful for elucidation of the mechanism underlying CysLT-induced tissue eosinophilia.

Eosinophilic drug reactions detected by a prospective pharmacovigilance programme in a tertiary hospital

AIM

We conducted a prospective evaluation of all eosinophilic drug reactions (EDRs) through the Prospective Pharmacovigilance Program from Laboratory Signals at Hospital to find out the incidence and distribution of these entities in our hospital, their causative drugs, and predictors.

METHODS

All peripheral eosinophilia >700 × 10⁶  cells l^-1 detected at admission or during hospitalisation, were prospectively monitored over 42 months. The spectrum of the localised or systemic manifestation of EDR, the incidence, the distribution of causative drugs, and the predictors were analysed.

RESULTS

The incidence of EDR was 16.67 (95% Poisson confidence interval [CI]: 9.90-25.98) per 10 000 admissions. Of 274 cases of EDR, 154 (56.2%) cases in 148 patients were asymptomatic hypereosinophilia. In the remaining 120 (43.8%) cases, there was other involvement. Skin and soft tissue reactions were detected in 36 (13.1%) cases; visceral EDRs in 19(7.0%) cases; and drug-induced eosinophilic cutaneous and visceral manifestations were detected in the remaining 65 (23.7%) cases, 64 of which were potential drug reaction with eosinophilia and systemic symptoms (DRESS). After adjusting for age, sex, and hospitalisation wards, predictors of symptomatic eosinophilia were earlier onset of eosinophilia (hazard ratio [HR], 10.49; 95%CI: 3.13-35.16) higher eosinophil count (HR, 8.51; 95%CI: 3.28-22.08), and a delayed onset of corticosteroids (HR, 1.34; 95%CI: 1.01-1.73). A higher eosinophil count in patients with DRESS was significantly associated with greater impairment of liver function, prolonged hospitalisation, higher cumulative doses of corticosteroids, and if hypogammaglobinaemia was detected, a reactivation of human-herpesvirus 6 was subsequently detected.

CONCLUSIONS

Half (53.3%, 64/120 cases) of symptomatic EDRs were potential DRESS. The main predictor of severity of EDR was an early severe eosinophilia.

CCR9 Is a Key Regulator of Early Phases of Allergic Airway Inflammation

Airway inflammation is the most common hallmark of allergic asthma. Chemokine receptors involved in leukocyte recruitment are closely related to the pathology in asthma. CCR9 has been described as a homeostatic and inflammatory chemokine receptor, but its role and that of its ligand CCL25 during lung inflammation remain unknown. To investigate the role of CCR9 as a modulator of airway inflammation, we established an OVA-induced allergic inflammation model in CCR9-deficient mice. Here, we report the expression of CCR9 and CCL25 as early as 6 hours post-OVA challenge in eosinophils and T-lymphocytes. Moreover, in challenged CCR9-deficient mice, cell recruitment was impaired at peribronchial and perivenular levels. OVA-administration in CCR9-deficient mice leads to a less inflammatory cell recruitment, which modifies the expression of IL-10, CCL11, and CCL25 at 24 hours after OVA challenge. In contrast, the secretion of IL-4 and IL-5 was not affected in CCR9-deficient mice compared to WT mice. These results demonstrate for the first time that CCR9 and CCL25 expressions are induced in the early stages of airway inflammation and they have an important role modulating eosinophils and lymphocytes recruitment at the first stages of inflammatory process, suggesting that they might be a potential target to regulate inflammation in asthma.

Comparative Analysis of Dibutyric cAMP and Butyric Acid on the Differentiation of Human Eosinophilic Leukemia EoL-1 Cells

Purification of enough numbers of circulating eosinophils is difficult because eosinophils account for less than 5% peripheral blood leukocytes. Human eosinophilic leukemia EoL-1 cells have been considered an in vitro source of eosinophils as they can differentiate into mature eosinophil-like cells when incubated with dibutyryl cAMP (dbcAMP) or butyric acid. In this study, the viability and phenotypic maturation of EoL-1 cells stimulated by either dbcAMP or butyric acid were comparatively analyzed. After treatment with 100 µM dbcAMP or 0.5 µM butyric acid, EoL-1 cells showed morphological signs of differentiation, although the number of nonviable EoL-1 cells was significantly increased following butyric acid treatment. Stimulation of EoL-1 cells with 0.5 µM butyric acid more effectively induced the expression of mature eosinophil markers than stimulation with dbcAMP. These results suggest that treatment of EoL-1 cells with 0.5 µM butyric acid for limited duration could be an effective strategy for inducing their differentiation. Considering that expression of CCR3 was not sufficient in EoL-1 cells stimulated with 0.5 µM butyric acid, treatment of the chemically stimulated EoL-1 cells with cytokines, which primarily support eosinophil maturation, would help to obtain differentiated EoL-1 cells with greater functional maturity.

MHC class II expression in human basophils: induction and lack of functional significance

The antigen-presenting abilities of basophils and their role in initiating a Th2 phenotype is a topic of current controversy. We aimed to determine whether human basophils can be induced to express MHC Class II and act as antigen presenting cells for T cell stimulation. Isolated human basophils were exposed to a panel of cytokines and TLR-ligands and assessed for MHC Class II expression. MHC Class II was expressed in up to 17% of isolated basophils following incubation with a combination of IL-3, IFN-γ and GM-CSF for 72 hours. Costimulatory molecules (CD80 and CD86) were expressed at very low levels after stimulation. Gene expression analysis of MHC Class II-positive basophils confirmed up-regulation of HLA-DR, HLA-DM, CD74 and Cathepsin S. However, MHC Class II expressing basophils were incapable of inducing antigen-specific T cell activation or proliferation. This is the first report of significant cytokine-induced MHC Class II up-regulation, at both RNA and protein level, in isolated human basophils. By testing stimulation with relevant T cell epitope peptide as well as whole antigen, the failure of MHC Class II expressing basophils to induce T cell response was shown not to be solely due to inefficient antigen uptake and/or processing.

Human eosinophils express functional CCR7

Human eosinophils display directed chemotactic activity toward an array of soluble chemokines. Eosinophils have been observed to migrate to draining lymph nodes in experimental models of allergic inflammation, yet it is unknown whether eosinophils express CCR7, a key chemokine receptor in coordinating leukocyte trafficking to lymph nodes. The purpose of this study is to demonstrate expression of CCR7 by human eosinophils and functional responses to CCL19 and CCL21, the known ligands of CCR7. Human eosinophils were purified by negative selection from healthy donors. CCR7 expression of freshly purified, unstimulated eosinophils and of IL-5-primed eosinophils was determined by flow cytometry and Western blot. Chemotaxis to CCL19 and CCL21 was measured in transwell assays. Shape changes to CCL19 and CCL21 were analyzed by flow cytometry and microscopy. Calcium fluxes of fluo-4 AM-loaded eosinophils were recorded by flow cytometry after chemokine stimulation. ERK phosphorylation of CCL19- and CCL21-stimulated eosinophils was measured by Western blot and Luminex assay. Human eosinophils expressed CCR7 as demonstrated by flow cytometry and Western blots. Eosinophils exhibited detectable cell surface expression of CCR7. IL-5-primed eosinophils exhibited chemotaxis toward CCL19 and CCL21 in a dose-dependent fashion. Upon stimulation with CCL19 or CCL21, IL-5-primed eosinophils demonstrated dose-dependent shape changes with polarization of F-actin and exhibited calcium influxes. Finally, primed eosinophils stimulated with CCL19 or CCL21 exhibited increased phosphorylation of ERK in response to both CCR7 ligands. We demonstrate that human eosinophils express CCR7 and have multipotent responses to the known ligands of CCR7.

B cells secrete eotaxin-1 in human inflammatory bowel disease

BACKGROUND

Our previous studies have demonstrated that B cells in human inflammatory bowel disease (IBD) are highly activated and produce copious amounts of chemokines. Here, we showed that B cells produce eotaxin-1, a selective chemokine for acute eosinophilia. Increased levels of activated eosinophils have been found in the intestinal mucosa in patients with IBD, but their role(s) and the regulation of their migration patterns remain poorly defined.

METHODS

To determine how B-cell secretion of eotaxin-1 influences eosinophil activation and migration, we performed immunoepidemiological approaches coupled with in vitro studies. B cells and eosinophils from patients with Crohn's disease and ulcerative colitis were isolated, and responses to Toll-like receptor ligands (TLR) were measured and assessed for the relationship with clinical disease.

RESULTS

Eotaxin-1 from recirculating B cells, and TLR ligands, regulated eosinophil homing mechanisms in IBD. B cells stimulated with hypo-acylated lipopolysaccharide (LPS) produced copious amounts of eotaxin-1, which influenced eosinophil activation profiles in the bloodstream. We also found that hexa-acylated LPS, such Escherichia coli LPS, directly activated TLR2-expressing and TLR4-expressing eosinophils from patients with IBD to express a different repertoire of mucosal homing receptors, namely CCR9 and CCR10. Whereas B-cell production of eotaxin-1 was correlated with reduced disease activity, eosinophil activation by hexa-acylated LPS was associated with increased disease activity.

CONCLUSIONS

These results suggest that systemic TLR ligands influence eosinophil migration patterns, both directly and indirectly, through B cells. Our report uncovers unexpected mechanisms of cross talk between certain immune cells that shed new light on IBD immunology.

Markers of antigen presentation and activation on eosinophils and T cells in the esophageal tissue of patients with eosinophilic esophagitis

OBJECTIVES

Evidence suggests eosinophils may be acting as antigen-presenting cells (APCs) by presenting antigen to T cells. We investigated the surface proteins of eosinophils and T cells in the esophageal biopsies of patients with eosinophilic esophagitis (EoE), patients with gastroesophageal reflux disease (GERD), and healthy controls (HCs).

METHODS

: Subjects were categorized as EoE, GERD, or HC. In esophageal tissue, EG2+ eosinophils were stained for the APC markers, CD40 or CD80, via immunohistochemistry. CD3+ T cells were stained for costimulatory markers, CD40L or CD28, and for activation markers, CD69 or CD134, via immunofluorescence or immunohistochemistry.

RESULTS

Eosinophils stained with CD40 and CD80. The number of EG2+CD40+ cells was increased in EoE (mean 19.1±14.8 cells/high-power field [HPF], n=11), compared with GERD (mean 0.13±0.19 cells/HPF, n=5, P<0.01) and HC (mean 0.3±0.7 cells/HPF, n=5, P<0.01). There was an elevation in EG2+CD80+ cells in EoE (mean 18.1±16.2 cells/HPF, n=10), GERD (mean 1.7±2.8 cells/HPF, n=6, P<0.01), or HC (mean 0.8±1.3 cells/HPF, n=6, P<0.01). CD3+ T cells stained with CD40L (not quantified). CD3+ T cells stained with CD28 at elevated levels in EoE (mean 14±8.7 cells/HPF, n=9) versus GERD (mean 3.3±1.2 cells/HPF, n=6, P<0.05) or HC (mean 3.0±3.2 cells/HPF, n=7, P<0.01). The number of CD3+CD69+ cells was highest in EoE (mean 14.8±7.5 cells/HPF, n=6) versus GERD (mean 0.8±0.9 cells/HPF, n=6, P<0.001) or HC (mean 2.7±2.5 cells/HPF, n=6, P<0.001).

CONCLUSIONS

We show that esophageal eosinophils express CD40 and CD80, and T cells with CD40L, CD28, and CD69. The number of double-stained cells was higher in EoE in comparison to control groups. These data support the hypothesis that eosinophils in EoE may act as APCs, activating T cells.

Pathogenesis and classification of eosinophil disorders: a review of recent developments in the field

Eosinophils and their products play an essential role in the pathogenesis of various reactive and neoplastic disorders. Depending on the underlying disease, molecular defect and involved cytokines, hypereosinophilia may develop and may lead to organ damage. In other patients, persistent eosinophilia is accompanied by typical clinical findings, but the causative role and impact of eosinophilia remain uncertain. For patients with eosinophil-mediated organ pathology, early therapeutic intervention with agents reducing eosinophil counts can be effective in limiting or preventing irreversible organ damage. Therefore, it is important to approach eosinophil disorders and related syndromes early by using established criteria, to perform all appropriate staging investigations, and to search for molecular targets of therapy. In this article, we review current concepts in the pathogenesis and evolution of eosinophilia and eosinophil-related organ damage in neoplastic and non-neoplastic conditions. In addition, we discuss classifications of eosinophil disorders and related syndromes as well as diagnostic algorithms and standard treatment for various eosinophil-related disorders.

Eosinophils elicit proliferation of naive and fungal-specific cells in vivo so enhancing a T helper type 1 cytokine profile in favour of a protective immune response against Cryptococcus neoformans infection

Experimental Cryptococcus neoformans infection in rats has been shown to have similarities with human cryptococcosis, because as in healthy humans, rats can effectively contain cryptococcal infection. Moreover, it has been shown that eosinophils are components of the immune response to C. neoformans infections. In a previous in vitro study, we demonstrated that rat peritoneal eosinophils phagocytose opsonized live yeasts of C. neoformans, thereby triggering their activation, as indicated by the up-regulation of MHC and co-stimulatory molecules and the increase in interleukin-12, tumour necrosis factor-α and interferon-γ production. Furthermore, this work demonstrated that C. neoformans-specific CD4(+) and CD8(+) T lymphocytes cultured with these activated C. neoformans-pulsed eosinophils proliferated, and produced important amounts of T helper type 1 (Th1) cytokines in the absence of Th2 cytokine synthesis. In the present in vivo study, we have shown that C. neoformans-pulsed eosinophils are also able to migrate into lymphoid organs to present C. neoformans antigens, thereby priming naive and re-stimulating infected rats to induce T-cell and B-cell responses against infection with the fungus. Furthermore, the antigen-specific immune response induced by C. neoformans-pulsed eosinophils, which is characterized by the development of a Th1 microenvironment with increased levels of NO synthesis and C. neoformans-specific immunoglobulin production, was demonstrated to be able to protect rats against subsequent infection with fungus. In summary, the present work demonstrates that eosinophils act as antigen-presenting cells for the fungal antigen, hence initiating and modulating a C. neoformans-specific immune response. Finally, we suggest that C. neoformans-loaded eosinophils might participate in the protective immune response against these fungi.

Role of eosinophils in inflammatory bowel and gastrointestinal diseases

Inflammatory bowel diseases (IBD) are characterized by the invasion of leukocytes into the intestinal mucosa. However, a mixed inflammatory picture is observed that includes neutrophils, lymphocytes, monocytes, and eosinophils. To this day, the role of eosinophils in health and in disease remains unclear. Investigations into their function stem primarily from allergic diseases, asthma, and parasitic infections. This makes it even more difficult to discern a role for the fascinating eosinophil in IBDs because, unlike the lung or the skin, eosinophils reside in normal intestinal mucosa and increase in disease states; consequently, an intricate system must regulate their migration and numbers. These granulocytes are equipped with the machinery to participate in gastrointestinal (GI) inflammation and in the susceptible microenvironment, they may initiate or perpetuate an inflammatory response. A significant body of literature characterizes eosinophils present in the GI microenvironment where they have the potential to interact with other resident cells, thus promoting intestinal remodeling, mucus production, epithelial barrier, cytokine production, angiogenesis, and neuropeptide release. A number of lines of evidence support both potential beneficial and deleterious roles of eosinophils in the gut. Although studies from the gut and other mucosal organs suggest eosinophils affect mucosal GI inflammation, definitive roles for eosinophils in IBDs await discovery.

Antigen presentation and MHC class II expression by human esophageal epithelial cells: role in eosinophilic esophagitis

Professional antigen-presenting cells (APCs) play a crucial role in initiating immune responses. Under pathological conditions, epithelial cells at mucosal surfaces act as nonprofessional APCs, thereby regulating immune responses at the site of exposure. Epithelial cells in the esophagus may contribute to the pathogenesis of eosinophilic esophagitis (EoE) by presenting antigens on the major histocompatibility complex (MHC) class II. Our goal was to demonstrate the ability of esophageal epithelial cells to process and present antigens on the MHC class II system and to investigate the contribution of epithelial cell antigen presentation to EoE. Immunohistochemistry detected HLA-DR, CD80, and CD86 expression and enzyme-linked immunosorbent assay detected interferon-γ (IFNγ) in esophageal biopsies. Antigen presentation was studied using the human esophageal epithelial cell line HET-1A by reverse transcriptase-PCR, flow cytometry, and confocal microscopy. T helper cell lymphocyte proliferation was assessed by flow cytometry and IL-2 secretion. IFNγ and MHC class II were increased in mucosa of patients with EoE. IFNγ increased mRNA of HLA-DP, HLA-DQ, HLA-DR, and CIITA in HET-1A cells. HET-1A engulfed cell debris and processed ovalbumin. HET-1A cells expressed HLA-DR after IFNγ treatment. HET-1A stimulated T helper cell activation. In this study, we demonstrated the ability of esophageal epithelial cells to act as nonprofessional APCs in the presence of IFNγ. Esophageal epithelial cell antigen presentation may contribute to the pathophysiology of eosinophilic esophagitis.

Eosinophils in innate immunity: an evolving story

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

Eosinophils in the zebrafish: prospective isolation, characterization, and eosinophilia induction by helminth determinants

Eosinophils are granulocytic leukocytes implicated in numerous aspects of immunity and disease. The precise functions of eosinophils, however, remain enigmatic. Alternative models to study eosinophil biology may thus yield novel insights into their function. Eosinophilic cells have been observed in zebrafish but have not been thoroughly characterized. We used a gata2:eGFP transgenic animal to enable prospective isolation and characterization of zebrafish eosinophils, and demonstrate that all gata2(hi) cells in adult hematopoietic tissues are eosinophils. Although eosinophils are rare in most organs, they are readily isolated from whole kidney marrow and abundant within the peritoneal cavity. Molecular analyses demonstrate that zebrafish eosinophils express genes important for the activities of mammalian eosinophils. In addition, gata2(hi) cells degranulate in response to helminth extract. Chronic exposure to helminth- related allergens resulted in profound eosinophilia, demonstrating that eosinophil responses to allergens have been conserved over evolution. Importantly, infection of adult zebrafish with Pseudocapillaria tomentosa, a natural nematode pathogen of teleosts, caused marked increases in eosinophil number within the intestine. Together, these observations support a conserved role for eosinophils in the response to helminth antigens or infection and provide a new model to better understand how parasitic worms activate, co-opt, or evade the vertebrate immune response.

Eosinophils as antigen-presenting cells in allergic upper airway disease

PURPOSE OF REVIEW

The recognition of eosinophils as complex immunomodulatory cells has been increasing in recent years. One prominent novel immunomodulatory function of eosinophils is their role as antigen-presenting cells (APCs). This review will examine the evidence that has enhanced the understanding of eosinophils as APCs in the context of allergic inflammation, with a focus on data applicable to allergic upper airway disease.

RECENT FINDINGS

Recent studies expand on prior findings that eosinophils can express major histocompatibility complex class II and costimulatory molecules. Eosinophils have also been found to traffic to regional lymph nodes and act as professional APCs in various experimental settings.

SUMMARY

Accumulating evidence of the ability of eosinophils to act as APCs suggests that eosinophils may have more complex immunomodulatory roles in allergic upper airway disease than previously appreciated.

Angiotensin-converting enzyme inhibition down-regulates the pro-atherogenic chemokine receptor 9 (CCR9)-chemokine ligand 25 (CCL25) axis

Many experimental and clinical studies suggest a relationship between enhanced angiotensin II release by the angiotensin-converting enzyme (ACE) and the pathophysiology of atherosclerosis. The atherosclerosis-enhancing effects of angiotensin II are complex and incompletely understood. To identify anti-atherogenic target genes, we performed microarray gene expression profiling of the aorta during atherosclerosis prevention with the ACE inhibitor, captopril. Atherosclerosis-prone apolipoprotein E (apoE)-deficient mice were used as a model to decipher susceptible genes regulated during atherosclerosis prevention with captopril. Microarray gene expression profiling and immunohistology revealed that captopril treatment for 7 months strongly decreased the recruitment of pro-atherogenic immune cells into the aorta. Captopril-mediated inhibition of plaque-infiltrating immune cells involved down-regulation of the C-C chemokine receptor 9 (CCR9). Reduced cell migration correlated with decreased numbers of aorta-resident cells expressing the CCR9-specific chemoattractant factor, chemokine ligand 25 (CCL25). The CCL25-CCR9 axis was pro-atherogenic, because inhibition of CCR9 by RNA interference in hematopoietic progenitors of apoE-deficient mice significantly retarded the development of atherosclerosis. Analysis of coronary artery biopsy specimens of patients with coronary artery atherosclerosis undergoing bypass surgery also showed strong infiltrates of CCR9-positive cells in atherosclerotic lesions. Thus, the C-C chemokine receptor, CCR9, exerts a significant role in atherosclerosis.

Induction of nitric oxide by erythropoietin is mediated by the β common receptor and requires interaction with VEGF receptor 2

Vascular endothelial growth factor (VEGF) and erythropoietin (EPO) have profound effects on the endothelium and endothelial progenitor cells (EPCs), which originate from the bone marrow and differentiate into endothelial cells. Both EPO and VEGF have demonstrated an ability to increase the number and performance properties of EPCs. EPC behavior is highly dependent on nitric oxide (NO), and both VEGF and EPO can stimulate intracellular NO. EPO can bind to the homodimeric EPO receptor (EPO-R) and the heterodimeric receptor, EPO-R and the common β receptor (βC-R). Although VEGF has several receptors, VEGF-R2 appears most critical to EPC function. We demonstrate that EPO induction of NO is dependent on the βC-R and VEGF-R2, that VEGF induction of NO is dependent on the expression of the βC-R, and that the βC-R and VEGF-R2 interact. This is the first definitive functional and structural evidence of an interaction between the 2 receptors and has implications for the side effects of EPO.

Eosinophils and oral squamous cell carcinoma: a short review

The eosinophil cell has been related as a prognostic indicator for cancers. However, its exact function in tumour behaviour is still not clearly defined. In the oral cavity the presence of eosinophils can be a favourable prognostic indicator as well as it may be associated with a poor prognosis. In this short review, we briefly summarize the role of the eosinophils in the general context of immunoregulation and its relation to oral squamous cell carcinoma.

Immunoregulatory roles of eosinophils: a new look at a familiar cell

Eosinophils are usually considered as end-stage degranulating effector cells of innate immunity. However, accumulating evidence has revealed additional roles for eosinophils that are immunoregulatory in nature in both the adaptive and innate arms of immunity. Specifically, eosinophils have key immunoregulatory roles as professional antigen-presenting cells and as modulators of CD4(+) T cell, dendritic cell, B cell, mast cell, neutrophil, and basophil functions. This review addresses the emerging immunoregulatory roles of eosinophils with a focus on recent data that support this new paradigm. Recognizing both the effector and immunoregulatory functions of eosinophils will enable a fuller understanding of the roles of eosinophils in allergic airways inflammation and may be pertinent to therapies that target eosinophils both for their acute and ongoing immunomodulatory functions.