Eosinophil function in health and disease

Cocktail of Periodic Acid-Schiff and Papanicolaou: Novel staining technique for the identification of leukemic eosinophils - A pilot study

Background

Tissue eosinophilia may be caused due to reactive, neoplastic or idiopathic reasons. Reactive eosinophils in allergic and inflammatory conditions are transient and recruited from the circulation in response to various stimuli, whereas neoplastic eosinophils of leukemias and hematological malignancies are involved in the pathogenesis of the disease. The differentiation of reactive from neoplastic eosinophils has a serious implication on the treatment and prognosis of diseases. However, both these types of eosinophils display variation in morphology and staining characteristics in routine histopathology leading to a diagnostic dilemma.

Aim

The aim of this study is to evaluate the efficacy of special stains for the demonstration of eosinophils in normal/reactive lesions and leukemias.

Methodology

A retrospective study comprising twenty histologically diagnosed cases each of reactive oral lesions and leukemias were obtained from institutional archives. These tissue sections were subjected to staining with routine and special stains - Carbol chromotrope, Congo red, Leishman's stain, Periodic Acid-Schiff-papanicolaou (PAS-PAP) and PAS. Statistical analysis was performed using Pearson's Chi-square test to compare the various parameters in the evaluation of the staining efficacy.

Results

Carbol chromotrope and Congo red staining showed increased staining efficacy in normal/reactive eosinophils while PAS-PAP followed by PAS and Leishman's stain showed enhanced features such as homogenicity, specificity, increased staining intensity, enhanced nuclear and cytoplasmic details in leukemic eosinophils.

Conclusion

Combined PAS-PAP is a novel and cost-effective staining technique in differentiating reactive and leukemic eosinophils. It is significant in recognizing leukemic eosinophils of routine biopsies and alerts the clinician to rule out any underlying malignancies.

Immunobiology of Inherited Muscular Dystrophies

The immune response to acute muscle damage is important for normal repair. However, in chronic diseases such as many muscular dystrophies, the immune response can amplify pathology and play a major role in determining disease severity. Muscular dystrophies are inheritable diseases that vary tremendously in severity, but share the progressive loss of muscle mass and function that can be debilitating and lethal. Mutations in diverse genes cause muscular dystrophy, including genes that encode proteins that maintain membrane strength, participate in membrane repair, or are components of the extracellular matrix or the nuclear envelope. In this article, we explore the hypothesis that an important feature of many muscular dystrophies is an immune response adapted to acute, infrequent muscle damage that is misapplied in the context of chronic injury. We discuss the involvement of the immune system in the most common muscular dystrophy, Duchenne muscular dystrophy, and show that the immune system influences muscle death and fibrosis as disease progresses. We then present information on immune cell function in other muscular dystrophies and show that for many muscular dystrophies, release of cytosolic proteins into the extracellular space may provide an initial signal, leading to an immune response that is typically dominated by macrophages, neutrophils, helper T-lymphocytes, and cytotoxic T-lymphocytes. Although those features are similar in many muscular dystrophies, each muscular dystrophy shows distinguishing features in the magnitude and type of inflammatory response. These differences indicate that there are disease-specific immunomodulatory molecules that determine response to muscle cell damage caused by diverse genetic mutations. © 2018 American Physiological Society. Compr Physiol 8:1313-1356, 2018.

Functional characterization of ECP-heparin interaction: a novel molecular model

Human eosinophil cationic protein (ECP) and eosinophil derived neurotoxin (EDN) are two ribonuclease A (RNaseA) family members secreted by activated eosinophils. They share conserved catalytic triad and similar three dimensional structures. ECP and EDN are heparin binding proteins with diverse biological functions. We predicted a novel molecular model for ECP binding of heparin hexasaccharide (Hep6), [GlcNS(6S)-IdoA(2S)]3, and residues Gln(40), His(64) and Arg(105) were indicated as major contributions for the interaction. Interestingly, Gln(40) and His(64) on ECP formed a clamp-like structure to stabilize Hep6 in our model, which was not observed in the corresponding residues on EDN. To validate our prediction, mutant ECPs including ECP Q40A, H64A, R105A, and double mutant ECP Q40A/H64A were generated, and their binding affinity for heparins were measured by isothermal titration calorimetry (ITC). Weaker binding of ECP Q40A/H64A of all heparin variants suggested that Gln(40)-His(64) clamp contributed to ECP-heparin interaction significantly. Our in silico and in vitro data together demonstrate that ECP uses not only major heparin binding region but also use other surrounding residues to interact with heparin. Such correlation in sequence, structure, and function is a unique feature of only higher primate ECP, but not EDN.

Roles of periostin in symptom manifestation and airway remodeling in a murine model of allergic rhinitis

PURPOSE

Periostin was originally identified as a secreted factor during screening of a mouse osteoblastic library. In a recent study, periostin was found to directly regulate eosinophil accumulation in allergic mucosal inflammation. Chronic eosinophilic inflammation is related to the development of remodeling. The present study examined the expression of periostin and evaluated its role in the inflammatory process and remodeling associated with allergic rhinitis.

METHODS

A murine model of allergic rhinitis was established in periostin knockout mice. We analyzed the expression of periostin, manifestation of nasal symptoms, eosinophilic inflammation, and subepithelial fibrosis as well as the expression of MMP-2, TIMP-1, and type 1 collagen in nasal tissue.

RESULTS

Periostin was mainly distributed in the subepithelial tissue of the nasal mucosa. The subepithelial tissue was thinner in the knockout group than in the control group. No differences in the expression of MMP-2 or TIMP-1 were found in the knockout group. However, after a month of allergen challenge, type I collagen in the nasal tissue was lower in the knockout group than in the control group. The number of eosinophils and the symptom score were also lower in the knockout group.

CONCLUSIONS

Periostin is expressed in nasal tissues of murine models of allergic rhinitis. Periostin deficiency may affect the remodeling of nasal tissue with reduced subepithelial fibrosis, and lead to less eosinophilic inflammation.

Overview on the pathomechanisms of allergic rhinitis

Allergic rhinitis a chronic inflammatory disease of the upper airways that has a major impact on the quality of life of patients and is a socio-economic burden. Understanding the underlying immune mechanisms is central to developing better and more targeted therapies. The inflammatory response in the nasal mucosa includes an immediate IgE-mediated mast cell response as well as a latephase response characterized by recruitment of eosinophils, basophils, and T cells expressing Th2 cytokines including interleukin (IL)-4, a switch factor for IgE synthesis, and IL-5, an eosinophil growth factor and on-going allergic inflammation. Recent advances have suggested new pathways like local synthesis of IgE, the IgE-IgE receptor mast cell cascade in on-going allergic inflammation and the epithelial expression of cytokines that regulate Th2 cytokine responses (i.e., thymic stromal lymphopoietin, IL-25, and IL-33). In this review, we briefly review the conventional pathways in the pathophysiology of allergic rhinitis and then elaborate on the recent advances in the pathophysiology of allergic rhinitis. An improved understanding of the immune mechanisms of allergic rhinitis can provide a better insight on novel therapeutic targets.

Oxidative stress and therapeutic opportunities: focus on the Ewing's sarcoma family of tumors

Reactive oxygen species (ROS) are highly reactive by-products of energy production that can have detrimental as well as beneficial effects. Unchecked, high levels of ROS result in an imbalance of cellular redox state and oxidative stress. High levels of ROS have been detected in most cancers, where they promote tumor development and progression. Many anticancer agents work by further increasing cellular levels of ROS, to overcome the antioxidant detoxification capacity of the cancer cell and induce cell death. However, adaptation of the level of cellular antioxidants can lead to drug resistance. The challenge for the design of effective cancer therapeutics exploiting oxidative stress is to tip the cellular redox balance to induce ROS-dependent cell death but without increasing the antioxidant activity of the cancer cell or inducing toxicity in normal cells.

My approach to interstitial lung disease using clinical, radiological and histopathological patterns

The complex world of interstitial lung disease presents nearly insurmountable challenges to the general surgical pathologist faced with a lung biopsy in this setting. The pathology is often inflammatory and always requires clinical and radiological context for a relevant and clinically useful histopathological diagnosis. A pattern-based histopathological approach to interstitial lung disease provides a “map” for the general pathologist to navigate this area successfully, especially so when used with aid of the clinical and radiological patterns of presentation.

FUTURA STUDY-Evaluation of efficacy and safety of rupatadine fumarate in the treatment of persistent allergic rhinitis

Allergic rhinitis affects 10-30% of the population, negatively impacting one's quality of life and productivity. It has been associated with sinusitis, otitis media, sleep disorders, and asthma. Rupatadine is a second generation antihistamine with increased affinity to histamine receptor H1; it is also a potent PAF (platelet-activating factor) antagonist. It starts acting quite quickly, offers long lasting effect, and reduces the chronic effects of rhinitis.

Aim

this study aims to assess the efficacy and safety of rupatadine in the treatment of persistent allergic rhinitis.

Materials and method

this is a multi-centric open prospective study. This study included 241 patients from 13 centers in Brazil and was held between October of 2004 and August of 2005. Signs and symptoms of rhinitis and tolerance to medication were analyzed after one and two weeks of treatment.

Results

reduction on general scores from 8.65 to 3.21 on week 2 (p<0.001). All signs and symptoms improved significantly in the first day of treatment (p<0.001), except for nasal congestion and secretion, which improved from the second day of treatment (p<0.001). Adverse events occurred in 19.9% of the cases, 27.7% on week 1.

Conclusion

rupatadine effectively controls persistent allergic rhinitis; it is safe and presents low incidence of side effects.

Establishment of experimental eosinophilic vasculitis by IgE-mediated cutaneous reverse passive arthus reaction

Prominent eosinophil infiltration is a characteristic of some forms of vasculitis, such as Churg-Strauss syndrome, also known as allergic granulomatous vasculitis. In the current study, we established a mouse model of cutaneous eosinophilic vasculitis by the cutaneous reverse passive Arthus reaction using IgE injection instead of IgG. Wild-type C57BL/6 mice were injected with IgE anti-trinitrophenyl antibodies, followed immediately by intravenous administration of trinitrophenyl bovine serum albumin. IgE-mediated immune complex challenge induced substantial hemorrhage with marked infiltration of eosinophils in which neutrophils, mast cells, and macrophages were also mixed. This finding contrasted remarkably with the neutrophil-dominant infiltration pattern in IgG-mediated immune complex challenge. In the lesion, the expression level of monocyte chemotactic protein-3 was increased, and anti-monocyte chemotactic protein-3 treatment resulted in a significant but incomplete blockade of eosinophil recruitment. Furthermore, mice lacking E-selectin, P-selectin, L-selectin, or intercellular adhesion molecule-1, as well as wild-type mice that received anti-vascular cell adhesion molecule-1-blocking antibodies were assessed for the IgE-mediated Arthus reaction. After 24 hours, the loss of P-selectin resulted in a significant reduction in eosinophil accumulation compared with both wild-type mice and other mouse mutants. Collectively, the Fc class of immunoglobulins, which forms these immune complexes, critically determines the disease manifestation of vasculitis. The IgE-mediated cutaneous reverse passive Arthus reaction may serve as an experimental model for cutaneous eosinophilic infiltration in vasculitis as well as in other diseases.

Recent advances in eosinophil biology

Eosinophils are pleiotropic multi-functional leukocytes involved in initiation and propagation of diverse inflammatory responses. Recent studies examining eosinophil biology have focused on delineating the molecular basis of FIP1L1/PDGRFalpha-fusion gene induced HES, the molecular steps involved in eosinophil recruitment in tumor-associated eosinophilia and EGID, and the role of eosinophils in asthma. In this review, these studies are summarized, focusing on the implications of these findings in the understanding the role of eosinophils in diseases.

The role of allergic rhinitis in the development of otitis media with effusion: effect on eustachian tube function

PURPOSE

The pathogenesis of otitis media with effusion (OME) is considered multifactorial, with viral upper respiratory tract infection and eustachian tube dysfunction. Allergy may be related to the pathogenesis of OME or to another etiological factor. We investigated the role of allergic rhinitis (AR) in children with OME and evaluated eustachian tube function in patients with AR.

MATERIALS AND METHODS

We prospectively analyzed the prevalence of AR, serum eosinophil count, and serum total IgE concentrations in 123 children with OME and in 141 controls. IgE concentration in middle ear effusion was compared in children with OME with and without AR, and eustachian tube function after a nasal provocation test was compared between patients with AR and controls.

RESULTS

The prevalence of AR in children with OME (28.4%) and control subjects (24.1%) did not differ significantly. These 2 groups also showed no differences in total eosinophil count and serum and middle ear effusion IgE concentration. Abnormalities in eustachian tube function were the same in patients with AR and controls.

CONCLUSIONS

Allergic rhinitis may not be related to the development of OME in children.

Activation of human eosinophils via P2 receptors: novel findings and future perspectives

A growing body of information indicates that release of intracellular nucleotides represents an important way to modulate several cell pathways in physiological or pathological conditions. Nucleotides released as a consequence of cell damage, cell stress, bacterial infection, or other noxious stimuli signal at a class of plasma membrane receptors--P2 receptors--activating diverse intracellular pathways in many tissues and organs. For example, nucleotides secreted in the airway system control chloride/liquid secretion, goblet cell degranulation, and ciliary beat frequency. Several studies indicate that nucleotides play a role in airway diseases through their action on multiple cell types, including mast cells, dendritic cells, neurons, and eosinophils. Recent work by us and other groups led to the identification and characterization of P2 receptors expressed by human eosinophils. In this review, we will summarize recent developments in this field and put forward a hypothesis about the role of P2 receptors in pathophysiological conditions where eosinophils are major players.

IL-5 and granulocyte-macrophage colony-stimulating factor activate STAT3 and STAT5 and promote Pim-1 and cyclin D3 protein expression in human eosinophils

Allergic inflammation is characterized by elevated eosinophil numbers and by the increased production of the cytokines IL-5 and GM-CSF, which control several eosinophil functions, including the suppression of apoptosis. The JAK/STAT pathway is important for several functions in hemopoietic cells, including the suppression of apoptosis. We report in this study that STAT3, STAT5a, and STAT5b are expressed in human eosinophils and that their signaling pathways are active following IL-5 or GM-CSF treatment. However, in airway eosinophils, the phosphorylation of STAT5 by IL-5 is reduced, an event that may be related to the reduced expression of the IL-5Ralpha on airway eosinophils. Furthermore, IL-5 and GM-CSF induced the protein expression of cyclin D3 and the kinase Pim-1, both of which are regulated by STAT-dependent processes in some cell systems. Pim-1 is more abundantly expressed in airway eosinophils than in blood eosinophils. Because Pim-1 reportedly has a role in the modulation of apoptosis, these results suggest that Pim-1 action is linked to the suppression of eosinophil apoptosis by these cytokines. Although cyclin D3 is known to be critical for cell cycle progression, eosinophils are terminally differentiated cells that do not proceed through the cell cycle. Thus, this apparent cytokine regulation of cyclin D3 suggests that there is an alternative role(s) for cyclin D3 in eosinophil biology.

Review article: The eosinophil as a therapeutic target in gastrointestinal disease

Elevated levels of eosinophils in the gastrointestinal tract is a common feature of numerous gastrointestinal disorders including food allergy, parasitic infections, gastro-oesophageal reflux, eosinophilic oesophagitis, eosinophilic gastroenteritis, allergic colitis and inflammatory bowel diseases. Recently, clinical and experimental studies have provided evidence that eosinophils have a critical role in the pathophysiology of eosinophil-associated gastrointestinal disease. Collectively, these studies have provided relevant insight into identifying key targets for therapeutic intervention. The present review describes recent experimental investigations on the role of eosinophils in the clinical manifestations of eosinophil-associated gastrointestinal disease and discusses future therapeutic approaches for the treatment of disease.

Restricted entry of R5 HIV Type 1 strains into eosinophilic cells

A cell culture system previously developed by our laboratory demonstrated that T cell-tropic (CXCR4-using) but not macrophage-tropic (CCR5-using) HIV-1 strains productively infected eosinophilic cells. In the current study, an improved model was used to determine the level of this viral restriction by assessing viral entry and coreceptor usage. The model was improved by using AML14.3D10 cells that were engineered to express CCR3 in addition to the major HIV-1 coreceptors, CD4, CXCR4, and CCR5, thus making them more like primary eosinophils. A polymerase chain reaction (PCR) assay was used to detect viral entry. In the PCR assay, primers specific for early reverse transcription products were used to amplify minus strand viral DNA from HIV-1-infected AML14.3D10-CCR3 eosinophilic cells. Coreceptor blocking experiments, using the CXCR4 antagonist AMD3100, were performed to determine coreceptor usage by the CXCR4-using (X4) strain known to productively infect the cells. Virus production was measured by p24 immunoassay. As expected, viral DNA was detected in AML14.3D10-CCR3 cells infected with X4 HIV-1, and cell viability was decreased during maximal viral production. Conversely, viral DNA was not detected in eosinophilic cells exposed to a CCR5-using (R5) HIV-1 strain that is also capable of using CCR3, indicating that R5 HIV-1 is unable to enter eosinophilic cells despite the presence of the appropriate coreceptors. Infection of AML14.3D10-CCR3 cells by HTLV-III(B) was completely inhibited by AMD3100, indicating that X4 HIV-1 enters the AML14.3D10-CCR3 cell line by using the CXCR4 coreceptor exclusively. Since X4 strains predominate during the late stages of HIV-1 infection in many patients, when eosinophil numbers also tend to increase, the ability of these HIV-1 strains to infect eosinophilic cells has important implications for the involvement of eosinophils in the pathogenesis of AIDS.

Cytokine-regulated accumulation of eosinophils in inflammatory disease

The role of cytokines in the accumulation of eosinophil granulocytes in inflamed tissue has been studied extensively during recent years, and these molecules have been found to participate throughout the whole process of eosinophil recruitment. Haematopoietic cytokines such as IL-3, IL-5 and GM-CSF stimulate the proliferation and differentiation of eosinophils in the bone marrow, and the release of mature eosinophils from the bone marrow into the blood is probably promoted by IL-5. Priming of eosinophils in the blood following, for example, allergen challenge is performed mainly by IL-3, IL-5 and GM-CSF. An important step in the extravasation of eosinophils is their adhesion to the vascular endothelium. Adhesion molecules are upregulated by, e.g. IL-1, IL-4, TNF-alpha and IFN-gamma and the same cytokines may also increase the affinity of adhesion molecules both on eosinophils and endothelial cells. Finally, a number of cytokines have been shown to act as eosinophil chemotactic factors, attracting the cells to the inflammatory focus in the tissue. Some of the most important eosinophil chemoattractant cytokines are IL-5, IL-8, RANTES, eotaxin, eotaxin-2, eotaxin-3, MCP-3, MCP-4 and TNF-alpha. Th2 cells, mast cells and epithelial cells are important sources of proinflammatory cytokines, but in recent years, the eosinophils have also been recognized as cytokine-producing and thereby immunoregulatory cells. The aim of this paper is to review the role of cytokines in the process of eosinophil recruitment in asthma, allergy and ulcerative colitis.

Peripheral blood eosinophilia associated with gastrointestinal administration of iodinated contrast media

OBJECTIVE

This study was designed to assess whether gastrointestinal administration of iodinated contrast media results in peripheral blood eosinophilia.

MATERIALS AND METHODS

We studied 110 patients in a retrospective review. Diatrizoate meglumine and diatrizoate sodium for abdominal CT were administered to 98 of these patients; 22 of the 98 had also been given the same contrast medium administered by enema. The remaining 12 patients were given diatrizoate sodium for gastrointestinal fluoroscopy. A control group of 65 patients underwent single-contrast barium upper gastrointestinal or enema examinations. WBC and eosinophil counts were determined approximately 24 hr before the examination and every 24 hr thereafter, through the ninth day.

RESULTS

Eosinophilia was detected in 17 (15.5%) of 110 patients after gastrointestinal administration of iodinated contrast media. The prevalence of eosinophilia after administration of iodinated contrast media was statistically significantly different compared with that in the control group, in which none of the 65 patients had eosinophilia (p < 0.001). Eosinophilia was detected 48 hr after application of iodinated contrast agents and lasted through the sixth day, with a peak on the fifth day. The prevalence of eosinophilia was independent of route of application, dose, or type of iodinated contrast medium. Eosinophilia in all cases was clinically asymptomatic.

CONCLUSION

Eosinophilia that is caused by gastrointestinal administration of iodinated contrast media is a transient, clinically silent phenomenon. It may lead to unnecessary workup for known conditions associated with eosinophilia.

Tumour-associated tissue eosinophilia as a prognostic factor in oral squamous cell carcinomas

AIMS

Tumour-associated tissue eosinophilia has been described in many sites, including head and neck. The mechanism of eosinophil recruitment and its role in tumours has not yet been defined, and its presence has been related to a favourable as well as unfavourable prognosis. The aim of this study was to evaluate the influence of tumour-associated tissue eosinophilia on the prognosis of 125 oral squamous cell carcinoma patients.

METHODS AND RESULTS

The number of eosinophils was obtained by morphometric analysis and ranged from 0 to 392 per mm2. Tumour-associated tissue eosinophilia was classified according to intensity as mild, moderate, or intense and correlated statistically to the intensity of the mononuclear inflammatory infiltrate as well as to the location of the eosinophilic inflammatory infiltrate. The multivariate analysis demonstrated that intense tumour-associated tissue eosinophilia is an independent favourable prognostic factor for oral squamous cell carcinomas.

CONCLUSION

These findings suggest an anti-tumoral role of eosinophils not as yet well understood that should be better investigated.

Experimental analysis of eosinophil-associated gastrointestinal diseases

Eosinophil infiltration into the gastrointestinal tract occurs in a wide range of diseases. However, the underlying cellular and molecular mechanisms involved in eosinophil migration and the role of eosinophils in disease pathogenesis are largely unknown. Recent studies using experimental models of eosinophil-associated gastrointestinal allergy have revealed differential roles for IL-5 and eotaxin in the modulation of eosinophil accumulation into various regions of the gastrointestinal tract. Furthermore, such studies have revealed a possible role for eosinophils in the pathogenesis of gastrointestinal disorders. The present review describes the clinical manifestations of various eosinophil-associated gastrointestinal disorders and the current understanding of the role of IL-5 and eotaxin in the allergic inflammatory response, and the participation of the eosinophilic granulocyte in the expression of disease.

Truncated thioredoxin (Trx80) induces production of interleukin-12 and enhances CD14 expression in human monocytes

Human thioredoxin (Trx) is the major 12-kd cellular disulfide-reductase that on secretion acts as a cocytokine with several interleukins. Truncated Trx with the 80 N-terminal residues (Trx80), also present in plasma, was by itself a mitogenic cytokine for human peripheral blood mononuclear cells (PBMC). This study investigated which cells in PBMC are targets of recombinant Trx80. Purified human CD14(+) monocytes, but not B or T cells, in a synthetic medium were activated to differentiation by Trx80 as measured by flow cytometry of surface antigens because exposure to 100 nM Trx80 increased expression of CD14, CD40, CD54, and CD86. Proliferation of the monocytes was increased in a dose-dependent manner by Trx80 in concentrations ranging from 10 nM to 1 microM. Trx or interleukin (IL) 2 did not induce proliferation or expression of surface antigens on monocytes. Trx80 alone induced secretion of IL-12 from CD40(+) monocytes in the PBMC cultures and this effect was enhanced by IL-2. Trx80 and IL-2 together were strongly synergistic to induce secretion of interferon-gamma in PBMC cultures. The results showed that Trx80 is a potent cytokine for normal human monocytes and directs the immune system in favor of a Th1 response via IL-12 production.

Neutrophil and eosinophil granule proteins as markers of response to local prednisolone treatment in distal ulcerative colitis and proctitis

OBJECTIVE

The pathophysiological role of neutrophil and eosinophil granulocytes in relation to steroid enema treatment was studied in patients with distal ulcerative colitis and proctitis.

METHODS

The rectal release of the neutrophil (myeloperoxidase, MPO), and eosinophil (eosinophilic cationic protein, ECP and eosinophil peroxidase, EPO) granule constituents were measured in 11 patients using intraluminal segmental perfusion of the rectum. The released amounts of MPO, ECP, and EPO in the perfusion fluids were determined by radioimmunoassays before and during prednisolone enema treatment and related to clinical, endoscopical, and histopathological data in addition to treatment outcome.

RESULTS

Clinical activity and particularly endoscopic activity correlated well with intraluminal MPO concentrations both before and during treatment. At the end of the study, eight of 11 patients fulfilled predefined response criteria; all responding patients had significant decrease of MPO concentrations (p < 0.01). This decline of MPO concentration was seen after 7 days of treatment (p < 0.05) in the response group and often occurred before clinical improvement. There was a nonsignificant trend toward a decrease in the concentrations of ECP and EPO at the end of treatment in responders.

Truncated thioredoxin is a mitogenic cytokine for resting human peripheral blood mononuclear cells and is present in human plasma

Human thioredoxin (Trx) catalyzes intracellular disulfide reductions but has also co-cytokine activity with interleukins after leaderless secretion. A recombinant truncated form of thioredoxin with the 80 N-terminal residues (Trx80) was purified to homogeneity. We discovered that Trx80 by itself is a potent mitogenic cytokine stimulating growth of resting human peripheral blood mononuclear cells. No effect was seen by Trx, but Trx80 at 50-100 nm induced cell proliferation of human peripheral blood mononuclear cells in serum-free synthetic medium, measured as [(3)H]thymidine incorporation after 72 h, with a maximum effect being comparable with that of 5 units/ml of interleukin-2. Trx80 lacked redox activity, but CD spectra suggested a secondary structure similar to Trx. Reduced Trx80 had an M(r) of 25,000, indicating that it is a dimer in solution. We also developed two different sandwich enzyme-linked immunosorbent assays that distinguish between full-length Trx and Trx80 and determined plasma levels of Trx and Trx80 in blood donors. The levels of Trx80 varied from 2 to 175 ng/ml; in comparison levels of Trx varied from 16 to 55 ng/ml without correlation to Trx80. In conclusion, the naturally occurring Trx80 is a novel mitogenic cytokine for normal resting human blood mononuclear cells.

Eosinophils, ribonucleases and host defense: solving the puzzle

The eosinophil ribonucleases eosinophil-derived neurotoxin (EDN/RNase 2) and eosinophil cationic protein (ECP/RNase 3) are among the major secretory effector proteins of human eosinophilic leukocytes, cells whose role in host defense remains controversial and poorly understood. We have recently described the unusual manner in which this ribonuclease lineage has evolved, with extraordinary diversification observed in primate as well as in rodent EDNs and ECPs. The results of our evolutionary studies suggest that the EDN/ ECP ribonucleases are in the process of being tailored for a specific, ribonuclease-related goal. With this in mind, we have begun to look carefully at some of the intriguing associations that link eosinophils and their ribonucleases to disease caused by the single-stranded RNA viral pathogen, respiratory syncytial virus (RSV). Recent work in our laboratory has demonstrated that eosinophils can mediate a direct, ribonuclease-dependent reduction in infectivity of RSV in vitro, and that EDN can function alone as an independent antiviral agent. The results of this work have led us to consider the possibility that the EDN/ECP ribonucleases represent a heretofore unrecognized element of innate and specific antiviral host defense.

Eosinophilia of dystrophin-deficient muscle is promoted by perforin-mediated cytotoxicity by T cell effectors

Previous investigations have shown that cytotoxic T lymphocytes (CTLs) contribute to muscle pathology in the dystrophin-null mutant mouse (mdx) model of Duchenne muscular dystrophy through perforin-dependent and perforin-independent mechanisms. We have assessed whether the CTL-mediated pathology includes the promotion of eosinophilia in dystrophic muscle, and thereby provides a secondary mechanism through which CTLs contribute to muscular dystrophy. Quantitative immunohistochemistry confirmed that eosinophilia is a component of the mdx dystrophy. In addition, electron microscopic observations show that eosinophils traverse the basement membrane of mdx muscle fibers and display sites of close apposition of eosinophil and muscle membranes. The close membrane apposition is characterized by impingement of eosinophilic rods of major basic protein into the muscle cell membrane. Transfer of mdx splenocytes and mdx muscle extracts to irradiated C57 mice by intraperitoneal injection resulted in muscle eosinophilia in the recipient mice. Double-mutant mice lacking dystrophin and perforin showed less eosinophilia than was displayed by mdx mice that expressed perforin. Finally, administration of prednisolone, which has been shown previously to reduce the concentration of CTLs in dystrophic muscle, produced a significant reduction in eosinophilia. These findings indicate that eosinophilia is a component of the mdx pathology that is promoted by perforin-dependent cytotoxicity of effector T cells. However, some eosinophilia of mdx muscle is independent of perforin-mediated processes.

Expression and in vitro properties of guinea pig IL-5: comparison to human and murine orthologs

Interleukin-5 (IL-5) is a key mediator of eosinophilic inflammation. The biological role of this cytokine in an allergic airway inflammatory response has been widely demonstrated in guinea pigs, yet the interaction of guinea pig IL-5 (gpIL-5) with its receptor has not been studied. Experiments were performed to quantitate the interaction of gpIL-5 with gpIL-5r and to compare this affinity with that of hIL-5 and mIL-5 and their cognate receptors. The cross-species affinity and agonist efficacy were evaluated to see if gpIL-5r had a restricted species reactivity (as is the case with mIL-5r) or did not distinguish between IL-5 orthologs (similar to hIL-5r). gpIL-5 was cloned using mRNA isolated from cells obtained by bronchoalveolar lavage. Recombinant gpIL-5 was expressed in T. ni insect cells and purified from spent media. Binding assays were performed using insect cells expressing hIL-5ralphabeta or gpIL-5ralphabeta1 as previously described (Cytokine, 12:858-866, 2000) or using B13 cells which express mIL-5r. The agonist potency and efficacy properties of each IL-5 ortholog were evaluated by quantitating the proliferative response of human TF-1 cells and murine B13 cells. gpIL-5 bound with high affinity to recombinant gpIL-5r as demonstrated by displacing [125I]hIL-5 (Ki = 160 pM). gpIL-5 also bound to hIL-5r with high affinity (Ki = 750 pM). hIL-5 and mIL-5 showed similar, high-affinity binding profiles to both gpIL-5r and hIL-5r. In contrast, gpIL-5 and hIL-5 did not bind to the mIL-5r as demonstrated by an inability to displace [125I]mIL-5, even at 1000-fold molar excess. These differences in affinity for IL-5r orthologs correlated with bioassay results: human TF-1 cells showed roughly comparable proliferative responses to guinea pig, human and murine IL-5 whereas murine B13 cells showed a strong preference for murine over guinea pig and human IL-5 (EC50 = 1.9, 2200 and 720 pM, respectively). Recombinant gpIL-5 binds to the gpIL-5r with high affinity, similar to that seen with the human ligand-receptor pair. gpIL-5r and hIL-5r do not distinguish between the three IL-5 orthologs whereas mIL-5r has restricted specificity for its cognate ligand.

Do eosinophil counts correlate differently with asthma severity by symptoms versus peak flow rate?

BACKGROUND

Discrepancy in asthmatic assessment by symptoms and peak flow rate (PFR) is a frequent dilemma. Currently, total peripheral eosinophil count (TPEC) is under study for asthma evaluation.

OBJECTIVES

To explore the correlation between TPEC and asthma severity assessed by symptoms alone versus symptoms and PFR.

METHOD

Adults asthmatics were selected from the Asthma Clinic. Severity assessment was based on two methods: symptoms alone or symptoms and PFR. Expiratory PFR was recorded by a Wright peak flow meter. Severity levels included mild intermittent, mild persistent, moderate persistent, and severe persistent. Total peripheral eosinophil count was performed on a Celldyn-3500 counter. Data was analyzed for statistical significance.

RESULTS

Sixty asthmatics aged 15 to 70 years (mean = 34 years), of which 68.3% were female, were studied. Severity levels differed between the two assessment methods in 45% of the cases and showed a predominance of the moderate persistent type. Total peripheral eosinophil count ranged between 22 and 2470 cells/mm3 (mean = 520 +/- SD = 393) and eosinophilia was found in 50% of the cases. Total peripheral eosinophil count showed a high positive correlation with increased asthma severity level assessed by history alone (r = 0.460, P < .001); more than by history and PFR (r = 0.328, P < .05).

CONCLUSION

The discrepancy between symptoms and PFR is confirmed by these results. A reliable objective parameter in asthma assessment is a continuous challenge. This study advocates the possible supplementation of TPEC as another objective parameter that might help in selecting the appropriate severity level in asthmatics.

Is there a role for automated eosinophil count in asthma severity assessment?

Advances in asthma clinical assessment help in categorizing patients based on their clinical severity. Eosinophilia is a common laboratory finding in asthmatics. This paper explores the correlation between the clinical severity of asthmatic children and the degree of total peripheral eosinophil count (TPEC). Eighty asthmatic children referred to pediatric and allergy clinics were selected. Their clinical severity levels were assessed using the recent Global Strategy for Asthma Management and Prevention guidelines. Absolute TPEC was performed for all cases by the Cell-Dyne 3500 automated hematology counter. Correlation between clinical severity and TPEC was measured and their means in each severity group were compared for any significant association. Asthmatic children aged between 6 months and 15 years (mean = 5.9 years; 67.5% male) were studied. The clinical severity of their bronchial asthma was divided into four groups: intermittent (6, or 7.5%), mild-persistent (48, or 60%), moderate persistent (20, or 25%), and severe-persistent (6, or 7.5%). TPEC for the groups ranged between 10 and 2100 cells/mm3 (mean = 581.7 cells) and showed a very significant positive correlation with increased asthma severity (R = 0.61, p<0.001). A high linear trend of TPEC within each clinical group was found (F = 51.3, p<0.0001), and the means among each group also showed a significant increase as asthma severity level increased (F = 19.98, p<0.001). The study documents a significant positive correlation between the clinical severity of bronchial asthma and eosinophil counts. The authors advocate the use of this simple and sensitive laboratory test as a significant adjunct objective technique in the assessment of asthma severity and management.