Human eosinophils have prolonged survival, enhanced functional properties, and become hypodense when exposed to human interleukin 3

Simultaneous Antagonism of Interleukin-5, Granulocyte-Macrophage Colony-Stimulating Factor, and Interleukin-3 Stimulation of Human Eosinophils by Targetting the Common Cytokine Binding Site of Their Receptors

Human interleukin-5 (IL-5), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-3 are eosinophilopoietic cytokines implicated in allergy in general and in the inflammation of the airways specifically as seen in asthma. All 3 cytokines function through cell surface receptors that comprise a ligand-specific  chain and a shared subunit (βc). Although binding of IL-5, GM-CSF, and IL-3 to their respective receptor  chains is the first step in receptor activation, it is the recruitment of βc that allows high-affinity binding and signal transduction to proceed. Thus, βc is a valid yet untested target for antiasthma drugs with the added advantage of potentially allowing antagonism of all 3 eosinophil-acting cytokines with a single compound. We show here the first development of such an agent in the form of a monoclonal antibody (MoAb), BION-1, raised against the isolated membrane proximal domain of βc. BION-1 blocked eosinophil production, survival, and activation stimulated by IL-5 as well as by GM-CSF and IL-3. Studies of the mechanism of this antagonism showed that BION-1 prevented the high-affinity binding of125I–IL-5, 125I–GM-CSF, and125I–IL-3 to purified human eosinophils and that it bound to the major cytokine binding site of βc. Interestingly, epitope analysis using several βc mutants showed that BION-1 interacted with residues different from those used by IL-5, GM-CSF, and IL-3. Furthermore, coimmunoprecipitation experiments showed that BION-1 prevented ligand-induced receptor dimerization and phosphorylation of βc, suggesting that ligand contact with βc is a prerequisite for recruitment of βc, receptor dimerization, and consequent activation. These results demonstrate the feasibility of simultaneously inhibiting IL-5, GM-CSF, and IL-3 function with a single agent and that BION-1 represents a new tool and lead compound with which to identify and generate further agents for the treatment of eosinophil-dependent diseases such as asthma.

Simultaneous Antagonism of Interleukin-5, Granulocyte-Macrophage Colony-Stimulating Factor, and Interleukin-3 Stimulation of Human Eosinophils by Targetting the Common Cytokine Binding Site of Their Receptors

Human interleukin-5 (IL-5), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-3 are eosinophilopoietic cytokines implicated in allergy in general and in the inflammation of the airways specifically as seen in asthma. All 3 cytokines function through cell surface receptors that comprise a ligand-specific  chain and a shared subunit (βc). Although binding of IL-5, GM-CSF, and IL-3 to their respective receptor  chains is the first step in receptor activation, it is the recruitment of βc that allows high-affinity binding and signal transduction to proceed. Thus, βc is a valid yet untested target for antiasthma drugs with the added advantage of potentially allowing antagonism of all 3 eosinophil-acting cytokines with a single compound. We show here the first development of such an agent in the form of a monoclonal antibody (MoAb), BION-1, raised against the isolated membrane proximal domain of βc. BION-1 blocked eosinophil production, survival, and activation stimulated by IL-5 as well as by GM-CSF and IL-3. Studies of the mechanism of this antagonism showed that BION-1 prevented the high-affinity binding of125I–IL-5, 125I–GM-CSF, and125I–IL-3 to purified human eosinophils and that it bound to the major cytokine binding site of βc. Interestingly, epitope analysis using several βc mutants showed that BION-1 interacted with residues different from those used by IL-5, GM-CSF, and IL-3. Furthermore, coimmunoprecipitation experiments showed that BION-1 prevented ligand-induced receptor dimerization and phosphorylation of βc, suggesting that ligand contact with βc is a prerequisite for recruitment of βc, receptor dimerization, and consequent activation. These results demonstrate the feasibility of simultaneously inhibiting IL-5, GM-CSF, and IL-3 function with a single agent and that BION-1 represents a new tool and lead compound with which to identify and generate further agents for the treatment of eosinophil-dependent diseases such as asthma.

Mechanisms and regulation of polymorphonuclear leukocyte and eosinophil adherence to human airway epithelial cells

Polymorphonuclear leukocytes (PMN) and eosinophils (Eos) are important cellular participants in a variety of acute and chronic inflammatory reactions in the airway. Histologic evidence has implicated direct interactions between these two subsets of leukocytes and airway epithelial cells during inflammation. A comprehensive characterization and comparison of physiologic stimuli and adhesion molecule involvement in granulocyte-epithelial-cell interactions done with nontransformed human airway epithelial cells has not been reported. We therefore examined the regulation and biochemical mechanisms governing granulocyte-epithelial-cell adhesion, using either purified PMN or Eos and primary cultures of human bronchial epithelial cells (HBECs). We investigated the involvement of a number of proinflammatory signals associated with allergic and nonallergic airway inflammation, as well as the contribution of several epithelial and leukocyte adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and members of the beta(1), beta(2), and beta(7) integrin families. ICAM-1 was expressed at low levels on cultured HBECs and was markedly upregulated after stimulation with interferon (IFN)-gamma or, to a lesser extent, with tumor necrosis factor (TNF)-alpha or interleukin (IL)-1. VCAM-1 was not present on resting HBECs, and was not upregulated after stimulation with IFN-gamma, IL-1, IL-4, or TNF-alpha. PMN adhesion to HBECs could be induced either through activation of PMN with IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF), or C5a, but not with IL-5 or by preactivation of HBECs with TNF-alpha or IFN-gamma. Blocking antibody studies indicated that PMN-HBEC adherence depended on beta(2) integrins, primarily alpha(M)beta(2) (Mac-1). Adherence of Eos to HBECs could be induced through activation of Eos with IL-5, GM-CSF, or C5a, but not with IL-8 or by prior activation of HBECs with TNF-alpha of IFN-gamma. Maximal adhesion of Eos and PMN required pretreatment of HBECs with either TNF-alpha or IFN-gamma in addition to leukocyte activation. Adherence of Eos to unstimulated HBECs was mediated through both beta(1) and beta(2) integrins, whereas adhesion of Eos to activated HBECs was dominated by beta(2) integrins. Adhesion of both Eos and PMN was inhibited by treatment of HBECs with blocking antibodies to ICAM-1. Differential utilization of beta(1) and beta(2) integrins by Eos, depending on the activation state of the epithelium, is a novel finding and may affect activation and/or recruitment of Eos in airway tissue. Mechanisms of adhesion of HBECs to Eos and PMN, as evidenced by the different responsiveness of the two latter types of cells to IL-8 and IL-5, may account for a prevalence of Eos over PMN in certain airway diseases.

LTC4 synthase. Enzymology, biochemistry, and molecular characterization

LTC4S conjugates reduce glutathione to LTA4 and is positioned as the pivotal and only committed enzyme involved in the formation of cysteinyl LTs. Despite its function as an enzyme that conjugates glutathione to LTA4, it is abundantly clear that LTC4S differs from the classic glutathione S-transferase (GST) families. This distinction is based on narrow substrate specificity, inability to conjugate GSH to xenobiotics, differential susceptibility to inhibitors, lack of homology, and failure to be immunorecognized by specific microsomal GST antibodies. The presence of LTC4S protein is restricted to a limited number of hematopoietic cells to include mast cells, eosinophils, basophils, monocytes/macrophages, and platelets, with the platelet being unique in its lack of the complete biosynthetic pathway for cysteinyl LTs. The purification of the protein and the cloning of the cDNA have demonstrated that the kinetic parameters of LTC4S are similar for the isolated natural or recombinant proteins. The protein is an 18-kDa integral perinuclear membrane enzyme, which is functional as a homodimer. The cDNA encodes a 150 amino-acid polypeptide monomer with three hydrophobic domains interspersed by two hydrophilic loops. Homology and secondary structural predictions have revealed that LTC4S is a member of a novel gene family that includes FLAP, mGST II, and mGST III. Each of these molecules is an integral membrane protein with the capacity to participate in LT biosynthesis: LTC4S as the terminal and only committed enzyme in cysteinyl LT formation, FLAP as an arachidonic acid presentation protein, and mGST II and mGST III as unique dual-function enzymes with primary detoxification functions. Site directed mutagenic studies of LTC4S have revealed that two residues, R51 and Y93, are involved in the acid and base catalysis, respectively, of LTA4 and GSH. Alignment of molecules with LTA4 conjugating ability demonstrates conservation of amino acid residues R51 and Y93, which appear necessary for this specific enzymatic function. The 2.5-Kb gene for human LTC4S contains five small exons and four introns, and the 5' UTR contains consensus sequences for AP-1 and AP-2 sites as well as an SP-1 site. The chromosomal localization of this gene is 5q35, distal to that of cytokine, growth factor, and receptor genes that have relevance to the development of allergic inflammation. Furthermore, there is genetic linkage of this region of human chromosome 5 to atopy and asthma, whereas no linkage exists for the chromosomal localization of the other family members, FLAP and mGST II, distinguishing LTC4S as a unique member of the novel gene family. LTC4S is profoundly overexpressed in the aspirin-induced asthmatic phenotype and correlates with overproduction of cysteinyl LTs and bronchial hyperreactivity to lysine aspirin. Ongoing studies are directed to the genomic regulation and additional polymorphisms within the gene of this pivotal enzyme, as well as to further identification of the amino acid residues central to its catalytic function.

Cysteinyl-leukotrienes partly mediate eotaxin-induced bronchial hyperresponsiveness and eosinophilia in IL-5 transgenic mice

Eotaxin, a selective chemoattractant for eosinophils, induces lung eosinophilia and bronchial hyperresponsiveness (BHR) when administered intratracheally to interleukin-5 (IL-5) transgenic mice. We determined whether these effects of eotaxin were mediated through the production of cysteinyl-leukotrienes. IL-5 transgenic mice were administered eotaxin (5 micrograms) intratracheally after pretreatment with either diluent or a selective 5-lipoxygenase inhibitor SB210661 or a cysteinyl-leukotriene receptor antagonist, pranlukast. Twenty-four hours later, bronchial responsiveness to acetylcholine was measured and the degree of eosinophil influx was determined in bronchoalveolar lavage fluid (BALF) or in lung tissue. Both pranlukast and SB210661 significantly attenuated BHR induced by eotaxin with logPC(50), which is the concentration of acetylcholine needed to increase baseline insufflation pressure by 50%, from -0.43 +/- 0.16 to 0.39 +/- 0.10 and from -0.22 +/- 0.10 to 0.53 +/- 0.10, respectively (p < 0.05). There was also a significant attenuation of the eosinophil counts in BALF and in airways. BALF levels of leukotriene C(4) (LTC(4)) showed a significant increase after eotaxin from 23.9 +/- 6.7 to 165.0 +/- 35.0 pg/ml (p < 0.05) but were partially suppressed by both SB210661 (71.2 +/- 21.0) and pranlukast (62.7 +/- 11.5). Concentrations of LTB(4) were not significantly changed. We conclude that eotaxin-induced effects in the airways of IL-5 transgenic mice are partly mediated by the activation of 5-lipoxygenase enzyme leading to the generation of cysteinyl-leukotrienes.

Asthma: an inflammatory mediator soup

Reversible or partially reversible airway obstruction, inflammation, and bronchial hyperresponsiveness to various stimuli are the defining characteristics of asthma. Airway obstruction in asthma is a complex event that is due to bronchospasm, inflammation, and mucus formation. Inflammation has assumed a more central role in the pathogenesis of the disease, as it contributes not only to airflow obstruction, but also to bronchial hyperresponsiveness. The inciting trigger, or inhaled allergen, in asthma induces the activation of mast cells and macrophages with the subsequent release of several proinflammatory mediators, including leukotrienes, chemotactic factors, and cytokines. Antigen processed by macrophages is presented to undifferentiated T helper cells, inducing differentiation to the Th2 phenotype, with the subsequent release of IL-4 and IL-5, causing IgE synthesis and eosinophil infiltration, respectively. Macrophage-derived cytokines, such as IL-1, TNF-alpha, and IFN-gamma, activate endothelial cells, upregulating the expression of adhesion molecules such as ICAM-1 and VCAM-1, which permit egression of leukocytes from the vasculature to the airway mucosa. Several inflammatory cells, such as eosinophils, mast cells, and macrophages, not only cause airway damage, but also synthesize cytokines that perpetuate the inflammatory process. This complex interplay of inflammatory cells and mediators causes the classic histopathophysiologic features in the airways of both symptomatic and asymptomatic individuals with asthma, emphasizing the importance of early recognition and antiinflammatory treatment.

IL-5 Increases Expression of 5-Lipoxygenase-Activating Protein and Translocates 5-Lipoxygenase to the Nucleus in Human Blood Eosinophils

Cysteinyl-leukotrienes are potent bronchoconstrictor mediators synthesized by the 5-lipoxygenase (5-LO) pathway. Eosinophilopoietic cytokines such as IL-5 enhance cysteinyl-leukotriene synthesis in eosinophils in vitro, mimicking changes in eosinophils from asthmatic patients, but the mechanism is unknown. We hypothesized that IL-5 induces the expression of 5-LO and/or its activating protein FLAP in eosinophils, and that this might be modulated by anti-inflammatory corticosteroids. Compared with control cultures, IL-5 increased the proportion of normal blood eosinophils immunostaining for FLAP (65 ± 4 vs 34 ± 4%; p &lt; 0.0001), enhanced immunoblot levels of FLAP by 51 ± 14% (p = 0.03), and quadrupled ionophore-stimulated leukotriene C4 synthesis from 5.7 to 20.8 ng/106 cells (p &lt; 0.02). IL-5 effects persisted for 24 h and were abolished by cycloheximide and actinomycin D. The proportion of FLAP+ eosinophils was also increased by dexamethasone (p &lt; 0.0001). Neither IL-5 nor dexamethasone altered 5-LO expression, but IL-5 significantly increased 5-LO immunofluorescence localizing to eosinophil nuclei. Compared with normal subjects, allergic asthmatic patients had a greater proportion of circulating FLAP+ eosinophils (46 ± 6 vs 27 ± 3%; p &lt; 0.03) and a smaller IL-5-induced increase in FLAP immunoreactivity (p &lt; 0.05). Thus, IL-5 increases FLAP expression and translocates 5-LO to the nucleus in normal blood eosinophils in vitro. This is associated with an enhanced capacity for cysteinyl-leukotriene synthesis and mimics in vivo increases in FLAP expression in eosinophils from allergic asthmatics.

Skin Homing (Cutaneous Lymphocyte-Associated Antigen-Positive) CD8+ T Cells Respond to Superantigen and Contribute to Eosinophilia and IgE Production in Atopic Dermatitis

In allergic inflammations of the skin, activation of CD4+ T cells was demonstrated to play an important role; however, a minor role for CD8+ T cells is implied. In the present study, we compared cutaneous lymphocyte-associated Ag (CLA)-expressing CD4+ and CD8+ subsets, which were isolated from peripheral blood and lesional skin biopsies in atopic dermatitis (AD) patients. We demonstrated that CD8+CLA+ T cells proliferate in response to superantigen and are as potent as CD4+CLA+ T cells in IgE induction and support of eosinophil survival. In atopic skin inflammation, the existence of high numbers of CD4+ and CD8+ T cells was demonstrated by immunohistochemistry and by culturing T cells from skin biopsies. In peripheral blood, both CD4+ and CD8+ subsets of CLA+CD45RO+ T cells were in an activated state in AD. The in vivo-activated CLA+ T cells of both subsets spontaneously released an IL-5- and IL-13-dominated Th2 type cytokine pattern. This was confirmed by intracytoplasmic cytokine staining immediately after isolation of the cells from peripheral blood. In consequence, both CD4+ and CD8+, CLA+ memory/effector T cells induced IgE production by B cells mainly by IL-13, and enhanced eosinophil survival in vitro by delaying eosinophil apoptosis, mainly by IL-5. These results indicate that in addition to the CD4+ subset, the CD8+CLA+ memory/effector T cells are capable of responding to superantigenic stimulation and play an important role in the pathogenesis of AD.

alpha4 integrin-dependent eotaxin induction of bronchial hyperresponsiveness and eosinophil migration in interleukin-5 transgenic mice

We investigated the roles of eosinophil infiltration and activation induced by the eosinophil-selective chemokine eotaxin, and of the expression of eosinophil alpha4 and beta2 integrins in causing bronchial hyperresponsiveness (BHR) in interleukin (IL)-5 CBA/Ca transgenic mice. These mice did not show BHR, despite the presence of some eosinophils in the lungs. Intratracheal mouse recombinant eotaxin (3 micrograms) did not induce BHR in wild-type mice. In IL-5 transgenic mice, eotaxin (3 and 5 micrograms) increased responsiveness at 24 h and increased eosinophils in bronchoalveolar lavage (BAL) fluid by 9.4- and 14-fold by 24 h, respectively, together with augmentation of eosinophil peroxidase activity and eosinophil infiltration in the airway submucosa. Using flow cytometry, the expression of alpha4, CD11b, and CD18 was upregulated in BAL, but not in blood, eosinophils. A rat anti-alpha4 antibody inhibited eotaxin-induced BHR and eosinophil migration and activation, but an anti-CD11b antibody had no significant effects on BHR. A combination of both antibodies was more effective. IL-5 and eotaxin synergize in the induction of BHR and airway eosinophilia, effects that are dependent on the induction of eosinophil alpha4 integrin. Expression of BHR depends on the recruitment and activation of eosinophils.

Ligation of FcγRII (CD32) Pivotally Regulates Survival of Human Eosinophils

The low-affinity IgG Fc receptor, FcγRII (CD32), mediates various effector functions of lymphoid and myeloid cells and is the major IgG Fc receptor expressed by human eosinophils. We investigated whether FcγRII regulates both cell survival and death of human eosinophils. When cultured in vitro without growth factors, most eosinophils undergo apoptosis within 96 h. Ligation of FcγRII by anti-CD32 mAb in solution inhibited eosinophil apoptosis and prolonged survival in the absence of growth factors. Cross-linking of human IgG bound to FcγRII by anti-human IgG Ab or of unoccupied FcγRII by aggregated human IgG also prolonged eosinophil survival. The enhanced survival with anti-CD32 mAb was inhibited by anti-granulocyte-macrophage-CSF (GM-CSF) mAb, suggesting that autocrine production of GM-CSF by eosinophils mediated survival. In fact, mRNA for GM-CSF was detected in eosinophils cultured with anti-CD32 mAb. In contrast to mAb or ligands in solution, anti-CD32 mAb or human IgG, when immobilized onto tissue culture plates, facilitated eosinophil cell death even in the presence of IL-5. Cell death induced by these immobilized ligands was accompanied by DNA fragmentation and was inhibited when eosinophil β2 integrin was blocked by anti-CD18 mAb, suggesting that β2 integrins play a key role in initiating eosinophil apoptosis. Thus, FcγRII may pivotally regulate both survival and death of eosinophils, depending on the manner of receptor ligation and β2 integrin involvement. Moreover, the FcγRII could provide a novel mechanism to control the number of eosinophils at inflammation sites in human diseases.

Circulating eosinophil/basophil progenitors and nasal mucosal cytokines in seasonal allergic rhinitis

Accumulation of eosinophils in the airways is characteristic of allergic rhinitis and asthma. The tissue eosinophilia may involve both recruitment of mature eosinophils and proliferation of their progenitors. This study examines mature eosinophils (nasal and circulating), their circulating progenitors, and a potential role of granulocyte-macrophage colony-stimulating factor (GM-CSF) in stimulating these progenitors. Twelve subjects with a history of seasonal allergic rhinitis and positive skin prick test for birch pollen were studied during four periods: shortly before, in the early and intense phase, at the end, and well after the Swedish birch-pollen season. Nasal mucosal and circulating eosinophils were examined in both nasal brushings and peripheral blood samples. Eosinophil/basophil progenitors were determined by counting colony-forming units in nonadherent mononuclear blood-cell cultures in methylcellulose at 14 days. The nasal mucosal cytokines GM-CSF, interleukin (IL)-1beta, IL-3, IL-5, IL-6, IL-8, and RANTES were analyzed (ELISA) in nasal lavage (NAL) fluids. All patients developed severe symptoms of rhinitis at the height of the season, with increased numbers of eosinophils in the nasal mucosa (P<0.05) and in the circulation (P<0.05). At this time point, the number of circulating progenitors (P<0.05) and the NAL fluid level of GM-CSF (P<0.05) were also increased. In contrast, there was no change in the NAL fluid levels of IL-1beta, IL-3, IL-6, or IL-8. Neither IL-5 nor RANTES could be detected in any of the NAL fluids. At the end of or after the season, there was no increase in nasal eosinophils or circulating eosinophils or progenitors (P>0.05). Ex vivo addition of GM-CSF (10-100 U) increased the number of blood progenitors grown before (P<0.01) and after (P<0.05) the season, compared with during the season. The in vitro GM-CSF responsiveness of progenitors may be related to whether or not these already have been stimulated endogenously by GM-CSF. Taken together, our data thus suggest that GM-CSF may play a role in vivo to increase production of eosinophilic progenitors in allergic airway disease.

Lymphocyte and eosinophil influx into alveolar tissue in nocturnal asthma

We have shown in nocturnal asthma that alveolar tissue eosinophils are increased at night as compared with the proximal airway, and that they correlate with the overnight decrement in lung function. As the CD4+ cell is thought to be the principal orchestrating cell in eosinophil recruitment, we evaluated its presence in the proximal and distal airways in nocturnal asthma. Eleven patients with nocturnal asthma (NA) and 10 patients with non-nocturnal asthma (NNA) underwent two bronchoscopies with proximal airway endobronchial and distal alveolar tissue transbronchial biopsy in a random order at 4:00 P.M. and at 4:00 A.M. separated by 1 wk. Immunohistochemical staining and morphometric analysis were used to determine the number of CD3+, CD4+, and CD8+ cells and EG2+ eosinophils per mm2 in the epithelium, lamina propria, and alveolar tissue. At 4:00 A.M., the NA group had a significantly greater number of CD4+ cells in the alveolar tissue than the NNA group (9.8 cells/ mm2 [5.6-30.8, interquartile (IQ)] versus 1.5 cells/mm2 [0-6. 3, IQ], p = 0.04). Within the NA group, there were significantly greater numbers of CD3+, CD4+, CD8+, and EG2+ cells in the proximal airway lamina propria than in the distal airway at both 4:00 P.M. and 4:00 A.M. There were no differences within the epithelium between the groups at either time point. Only alveolar tissue, not airway tissue, CD4+ cells correlated inversely with the percentage predicted FEV1 at 4:00 A.M. (r = -0.68, p = 0.0018) and positively with the number of alveolar tissue EG2+ cells (r = 0.66, p = 0.01). These findings suggest that the CD4+ lymphocyte is increased in the alveolar tissue at night in nocturnal asthma as compared with non-nocturnal asthma.

Effect of intranasal fluticasone on cellular infiltration, endothelial adhesion molecule expression, and proinflammatory cytokine mRNA in nasal polyp disease

BACKGROUND

Nasal polyp (NP) disease demonstrates a gradual response to treatment with intranasal steroids. We hypothesized that various inflammatory features that promote NP eosinophilia would show a differential sensitivity to treatment with intranasal fluticasone.

OBJECTIVES

We conducted a double-blind, placebo-controlled trial of 4 weeks of intranasal fluticasone propionate or matching placebo to assess their effectiveness in reducing NP inflammatory cells, expression of endothelial vascular cell adhesion molecule (VCAM)-1 and P-selectin, and expression of cytokines involved in induction of a group of adhesion molecules (ie, IL-4, IL-13, TNF-alpha, and IL-1beta).

METHODS

Twenty subjects (9 women and 11 men) with severe chronic sinusitis and NP were studied. Systemic and intranasal steroids were withheld for a minimum of 1 month and 2 weeks, respectively, before the study. Biopsy specimens of NPs were obtained 1 week before and 4 weeks after treatment with intranasal fluticasone 100 microg or placebo per nostril administered twice daily. Biopsy specimens were snap frozen for immunostaining or fixed in paraformaldehyde for in situ hybridization. Pretreatment to posttreatment results were analyzed with Wilcoxon's signed-rank test.

RESULTS

Fluticasone treatment significantly reduced NP eosinophilia (P =.02) and CD4(+) T lymphocytes (P =.02). Eosinophils expressing the marker EG2 were more significantly reduced (P =.007). Fluticasone also reduced the expression of P-selectin (P =.005) and the number of IL-4 and IL-13 mRNA+ cells (P =.02 and.05, respectively). In contrast, fluticasone did not significantly reduce expression of endothelial VCAM-1 or the number of TNF-alpha or IL-1beta mRNA+ cells in the polyps.

CONCLUSIONS

We conclude that intranasal fluticasone reduced NP inflammation but that expression of proinflammatory cytokines and endothelial VCAM-1 were relatively unaffected by fluticasone treatment. These latter inflammatory features may contribute to the persistence of NP disease despite intranasal steroid treatment.

Macrophage Colony-Stimulating Factor Stimulates Synthesis and Secretion of a Mouse Homolog of a Human IgE-Dependent Histamine-Releasing Factor by Macrophages In Vitro and In Vivo

Treatment of murine resident peritoneal macrophages with macrophage-CSF (M-CSF) up-regulated the synthesis of a discrete set of proteins, including a 26-kDa protein (p26). The sequence of 20 NH2-terminal amino acids of the purified p26 was identical with the mouse homolog of a human IgE-dependent histamine-releasing factor (HRF). Among macrophage activators tested (M-CSF, granulocyte-macrophage-CSF, IL-3, TNF-α, IFN-γ, and LPS), only M-CSF could up-regulate the p26 HRF synthesis by cultured macrophages. M-CSF not only increased the levels of p26 HRF mRNA and protein, but also stimulated the secretion of an N-glycosylated p26 HRF with a m.w. of 30 kDa. Repeated injections of M-CSF into mouse peritoneal cavity for 4 days elicited macrophages expressing abundant p26 HRF. A single i.p. injection of M-CSF failed to increase the p26 HRF level in peritoneal macrophages of thioglycollate-, LPS-, or adjuvant-treated mice, while M-CSF challenge to OVA-immunized mice caused macrophage infiltration and overproduction of p26 HRF, similarly as did OVA challenge. The Ag-specific priming for enhanced synthesis and secretion of p26 HRF by M-CSF was also demonstrated in cultured macrophages prepared from OVA-immunized mice. An i.p. injection of M-CSF or recombinant p26 HRF triggered eosinophil recruitment, even in the absence of the Ag, in the sensitized mice, but not in normal mice. Furthermore, recombinant p26 HRF could induce eosinophilia without marked macrophage and lymphocyte infiltrations. Our results suggest that p26 HRF secreted by M-CSF-stimulated macrophages may be an important mediator for the late phase allergic inflammation.

Familial eosinophilia maps to the cytokine gene cluster on human chromosomal region 5q31-q33

Familial eosinophilia (FE) is an autosomal dominant disorder characterized by peripheral hypereosinophilia of unidentifiable cause with or without other organ involvement. To localize the gene for FE, we performed a genomewide search in a large U.S. kindred, using 312 different polymorphic markers. Seventeen affected subjects, 28 unaffected bloodline relatives, and 8 spouses were genotyped. The initial linkage results from the genome scan provided evidence for linkage on chromosome 5q31-q33. Additional genotyping of genetic markers located in this specific region demonstrated significant evidence that the FE locus is situated between the chromosome 5q markers D5S642 and D5S816 (multipoint LOD score of 6.49). Notably, this region contains the cytokine gene cluster, which includes three genes-namely, those for interleukin (IL)-3, IL-5, and granulocyte/macrophage colony-stimulating factor (GM-CSF)-whose products play important roles in the development and proliferation of eosinophils. These three cytokine genes were screened for potential disease-specific mutations by resequencing of a subgroup of individuals from the present kindred. No functional sequence polymorphisms were found within the promoter, the exons, or the introns of any of these genes or within the IL-3/GM-CSF enhancer, suggesting that the primary defect in FE is not caused by a mutation in any one of these genes but, rather, is caused by another gene in the area.

GM-CSF, IL-5 and RANTES immunoreactivity and mRNA expression in chronic hyperplastic sinusitis with nasal polyposis (NP)

BACKGROUND

Eosinophils are a prominent feature of chronic hyperplastic sinusitis with nasal polyposis (CHS/NP). Our previous studies showed that their presence was associated with the expression of GM-CSF and RANTES mRNA. In allergic NP, increased expression of IL-5 was also found.

OBJECTIVE

We wished to examine cytokine immunoreactivity for IL-5, GM-CSF and RANTES mRNA in allergic and non-allergic NP and compare immunoreactivity with expression of cytokine mRNA by in situ hybridization. Methods NP were obtained from five allergic and eight non-allergic subjects with CHS/ NP. Middle turbinate tissue from eight normal subjects were used as controls. Cell-associated cytokine mRNA was detected by in situ hybridization (ISH). Cytokine immunoreactive cells were enumerated by immunostaining. Colocalization immunostaining was also performed to identify specific cell types producing IL-5.

RESULTS

Immunostaining for GM-CSF, IL-5 and RANTES protein was increased in both allergic and non-allergic NP compared with control middle turbinates. Allergic polyps contained greater numbers of IL-5 immunoreactive cells (P = 0.01), whereas non-allergic polyps contained greater numbers of GM-CSF immunoreactive cells (P = 0.04). Immunostaining was primarily associated with inflammatory cells, but immunostaining for RANTES and, to a lesser extent GM-CSF, was also seen in the epithelium. The density of immunoreactive cells was variably correlated with cytokine mRNA+ cells (GM-CSF: R=0.56, P=0.05; IL-5: R=0.76, P=0.003; and RANTES: R=0.89, P=0.0005). Colocalization immunostaining revealed that the majority of IL-5 immunoreactive cells in both allergic and non-allergic NP were T lymphocytes. However, allergic NP contained greater numbers of IL-5+/CD3+ T lymphocytes and IL-5+ mast cells, whereas non-allergic NP contained greater numbers of IL-5+ eosinophils.

CONCLUSION

We conclude that GM-CSF, IL-5 and RANTES are produced in increased amounts in both allergic and non-allergic NP. Distinguishing features of non-allergic NP include fewer numbers of CD3 T lymphocytes, fewer IL-5+/CD3+ T lymphocytes and greater numbers of IL-5+ eosinophils. These differences may suggest different mechanisms of eosinophil accumulation and activation in allergic vs non-allergic NP.

Soluble adhesion molecules and cytokines in perennial allergic rhinitis

BACKGROUND

Increasing evidence suggests adhesion molecules and cytokines in patients with inflammatory airway diseases are involved in steps of entrapment and migration of inflammatory cells. Recently, soluble forms of adhesion molecules and cytokines have been detected in the sera and other body fluids of patients with various diseases.

OBJECTIVE

Eosinophilia in nasal mucosa is characteristic of allergic rhinitis. Vascular adhesion molecules expressed on the endothelium are essential for eosinophils to move from the peripheral blood into the sites of inflammation. Herein, soluble forms of vascular adhesion molecules and eosinophil-activating cytokines are measured to investigate the significance of their appearance in the sera with eosinophil infiltration in the nasal mucosa of perennial allergic rhinitis.

METHODS

With the quantitative sandwich enzyme immunoassay technique, the sera of 36 patients of perennial allergic rhinitis and 20 nonatopic subjects were used to measure the levels of soluble intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), E-selectin (endothelial leukocyte adhesion molecule-1, sELAM-1), interleukin-3 (IL-3), and interleukin-5 (IL-5).

RESULTS

No significant differences in the levels of soluble vascular adhesion molecules were noted between the two groups. Eosinophil-activating cytokines, IL-3 and IL-5, were significantly increased in the group with perennial allergic rhinitis, and were correlated with eosinophil infiltration in nasal scrapings.

CONCLUSION

Although the vascular adhesion molecules expressed on the endothelium are necessary for eosinophils to appear in allergic tissues, eosinophil-activating cytokines as IL-3 and IL-5 are likely to be essential for eosinophils to function in tissues. The elevated concentrations of IL-3 and IL-5 in allergic rhinitis may reflect the inflammatory response occurring in the T cell activation and in relation to manifestation of eosinophils.

Effects of glucocorticoids on apoptosis of infiltrated eosinophils and neutrophils in rats

The effects of glucocorticoids on the survival of rat eosinophils and neutrophils infiltrated into the peritoneal cavity were examined. Glucocorticoids including dexamethasone, prednisolone and hydrocortisone inhibited the survival of rat peritoneal eosinophils at 10(-6) M, whereas they prolonged survival of rat peritoneal neutrophils at 10(-8) M. Sex steroids including estradiol and progesterone did not affect cell survival. Dexamethasone decreased the viability of eosinophils after 3 days of incubation and maintained the viability of neutrophils until 4 days after incubation concentration dependently. The EC50 of dexamethasone for inhibition of the survival of eosinophils was 1.5 x 10(-8) M, and that for the spontaneous death of neutrophils was 6.4 x 10(-10) M, suggesting that glucocorticoids at concentrations that inhibit eosinophil survival prolong neutrophil survival. Analysis of DNA fragmentation of cultured eosinophils and neutrophils revealed that glucocorticoids enhance eosinophil apoptosis but inhibit neutrophil apoptosis. The effects of dexamethasone on viability and DNA fragmentation were counteracted by the glucocorticoid receptor antagonist, mifepristone, concentration dependently. These findings indicate that glucocorticoids induce contradictory effects via the glucocorticoid receptor on rat eosinophils and neutrophils extravasated to an inflammatory locus such as the peritoneal cavity by modulating apoptosis.

Role for Tyrosine Phosphorylation and Lyn Tyrosine Kinase in Fas Receptor-Mediated Apoptosis in Eosinophils

Fas ligand/Fas receptor molecular interactions have been implicated as having an important function for the regulation of eosinophil apoptosis. The purpose of the present study was to investigate biochemical events triggered by the engagement of the Fas receptor in freshly isolated human and mouse eosinophils. Activation of the Fas receptor on eosinophils with the agonistic anti-Fas monoclonal antibody (MoAb) resulted in increased tyrosine phosphorylation of several intracellular proteins. The tyrosine kinase inhibitors lavendustin A and genistein inhibited Fas receptor-induced cell death in both human and mouse eosinophils in vitro and prevented, at least partially, Fas receptor-mediated resolution of eosinophilic inflammation in a mouse in vivo model of lung eosinophilia. In addition, in freshly purified human eosinophils, lavendustin A prevented anti-Fas MoAb-induced proteolytic cleavage of lamin B, suggesting that tyrosine kinases may amplify the proteolytic signaling cascade within interleukin-1β converting enzyme (ICE) family proteases. Moreover, the tyrosine kinase Lyn was identified as being involved in Fas receptor-mediated cell death. Collectively, these results demonstrate that tyrosine phosphorylation is an important step in the generation of the Fas receptor-linked transmembrane death signal in eosinophils and that Lyn participates in this pathway.

Role for Tyrosine Phosphorylation and Lyn Tyrosine Kinase in Fas Receptor-Mediated Apoptosis in Eosinophils

Fas ligand/Fas receptor molecular interactions have been implicated as having an important function for the regulation of eosinophil apoptosis. The purpose of the present study was to investigate biochemical events triggered by the engagement of the Fas receptor in freshly isolated human and mouse eosinophils. Activation of the Fas receptor on eosinophils with the agonistic anti-Fas monoclonal antibody (MoAb) resulted in increased tyrosine phosphorylation of several intracellular proteins. The tyrosine kinase inhibitors lavendustin A and genistein inhibited Fas receptor-induced cell death in both human and mouse eosinophils in vitro and prevented, at least partially, Fas receptor-mediated resolution of eosinophilic inflammation in a mouse in vivo model of lung eosinophilia. In addition, in freshly purified human eosinophils, lavendustin A prevented anti-Fas MoAb-induced proteolytic cleavage of lamin B, suggesting that tyrosine kinases may amplify the proteolytic signaling cascade within interleukin-1β converting enzyme (ICE) family proteases. Moreover, the tyrosine kinase Lyn was identified as being involved in Fas receptor-mediated cell death. Collectively, these results demonstrate that tyrosine phosphorylation is an important step in the generation of the Fas receptor-linked transmembrane death signal in eosinophils and that Lyn participates in this pathway.

Human ecalectin, a variant of human galectin-9, is a novel eosinophil chemoattractant produced by T lymphocytes

A 1.6-kilobase pair cDNA was isolated from a human T-cell-derived expression library that encodes a novel eosinophil chemoattractant (designated ecalectin) expressed during allergic and parasitic responses. Based on its deduced amino acid sequence, ecalectin is a 36-kDa protein consisting of 323 amino acids. Although ecalectin lacks a hydrophobic signal peptide, it is secreted from mammalian cells. Ecalectin is not related to any known cytokine or chemokine but rather is a variant of human galectin-9, a member of the large family of animal lectins that have affinity for beta-galactosides. Recombinant ecalectin, expressed in COS cells and insect cells, exhibited potent eosinophil chemoattractant activity and attracted eosinophils in vitro and in vivo in a dose-dependent manner but not neutrophils, lymphocytes, or monocytes. The finding that the ecalectin transcript is present in abundance in various lymphatic tissues and that its expression increases substantially in antigen-activated peripheral blood mononuclear cells suggests that ecalectin is an important T-cell-derived regulator of eosinophil recruitment in tissues during inflammatory reactions. We believe that this is the first report of the expression of an immunoregulatory galectin expressed by a T-cell line that is selective for eosinophils.

Human Eosinophils Produce Biologically Active IL-12: Implications for Control of T Cell Responses

The present study assessed the capacity of eosinophils (EOS) to synthesize the cytokine IL-12. Blood-derived, highly purified human EOS from six atopic patients and two nonatopic individuals were treated in culture with IL-4, IL-5, granulocyte-macrophage CSF, IFN-γ, TNF-α, IL-1α, RANTES, and complement 5a, respectively. The expression of both IL-12 protein and mRNAs for the p35 and p40 IL-12 subunits was strongly induced in all donors by the Th2-like cytokines IL-4 and granulocyte-macrophage CSF and was also moderately induced by TNF-α and IL-1α. IL-5 treatment resulted in IL-12 synthesis in four atopic donors and one nonatopic donor, whereas IFN-γ induced IL-12 synthesis in only two atopic donors. In contrast, RANTES exclusively induced mRNA for the p40 subunit without detectable protein release, and complement 5a had no effect on IL-12 mRNA or protein expression. EOS-derived IL-12 was biologically active, because supernatants derived from IL-4-treated EOS superinduced the Con A-induced expression of IFN-γ by a human Th1-like T cell line. This activity was neutralized by anti-IL-12 Abs. In conclusion, EOS secrete biologically active IL-12 after treatment with selected cytokines, which mainly represent the Th2-like type. Consequently, EOS may promote a switch from Th2-like to Th1-like immune responses in atopic and parasitic diseases.

Enhanced expression of GM-CSF in differentiating eosinophils of atopic and atopic asthmatic subjects

Higher numbers of eosinophil/basophil colony-forming units (Eo/B CFU) are observed in blood of atopic individuals, and can be enhanced in atopic asthmatics by allergen-inhalation challenge. It is known that mature basophils and eosinophils synthesize cytokines relevant to allergic inflammation. To investigate the potential role of growth factors in allergic disease we examined the expression of the hemopoietic cytokines, granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-5, in differentiating Eo/B colony cells from normal and atopic individuals, and from atopic asthmatics before and after allergen-inhalation challenge. Peripheral blood was collected from two normal and 12 atopic individuals, and also from 25 atopic asthmatics before and 24 h after allergen challenge. Nonadherent mononuclear cells were isolated and grown in semisolid growth medium. Eo/B colonies were selected and cytospins were prepared for immunocytochemical analysis of colony cells. Eo/B colonies, especially carbol chromotrope 2R+ cells, selected at Days 10, 14, and 18 from atopic donors contained messenger RNA for GM-CSF by combined in situ reverse transcription-polymerase chain reaction and cytochemistry, and demonstrated time-dependent expression of GM-CSF by immunocytochemistry (P = 0.007). Atopic individuals demonstrated a higher percentage of cells expressing GM-CSF than did normal subjects under all growth conditions when examined at Day 14 (P = 0. 04). Atopic asthmatics challenged with inhaled allergen who demonstrated a dual airway response, an increase in the number of blood eosinophils (P = 0.0001), and an increase in the number of Eo/B CFU (P = 0.02) also demonstrated a significant increase in the percentage of colony cells expressing immunostainable GM-CSF (P = 0. 0009), but only a variable effect on those expressing IL-5, 24 h after allergen. These results suggest that GM-CSF expression by differentiating Eo/Bs may provide an additional stimulus in vivo to enhance Eo/B progenitor differentiation in atopic and asthmatic individuals, especially after allergen challenge. The concept of microenvironmental differentiation, where blood progenitor cells may aid in their own differentiation, is supported by these ex vivo findings.

Granulocyte macrophage colony-stimulating factor augments ICAM-1 and VCAM-1 activation of eosinophil function

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are members of the immunoglobulin superfamily adhesion molecules on vascular endothelium and important in the development of eosinophil (EOS) accumulation in allergic inflammation. To define the role of these adhesion proteins in EOS inflammation, peripheral blood EOS from allergic donors were incubated in either buffer (control)-, recombinant human (rh)-VCAM-1-, or rh-ICAM-1-coated plates, and the effects of these adhesion proteins on EOS effector functions were determined. VCAM-1 induced spontaneous EOS adhesion whereas EOS adhesion to ICAM-1 required a second signal, such as granulocyte macrophage colony-stimulating factor (GM-CSF). Although only VCAM-1 stimulated EOS superoxide anion (O2-) generation, the addition of GM-CSF (100 pM) to the reactions resulted in a greater and equivalent production of O2- with VCAM-1 and ICAM-1. In the presence of GM-CSF, ICAM-1 and VCAM-1 caused significant release of EOS-derived neurotoxin (EDN). Moreover, only ICAM-1 (no GM-CSF) promoted calcium ionophore A23187 (0.2 microM)-induced EOS leukotriene C4 (LTC4). Enhanced O2- generation, EDN release, and LTC4 generation observed with ICAM-1 and VCAM-1 were significantly inhibited by anti-beta2-integrin antibody. These results suggest that ICAM-1 and VCAM-1 are important in determining the eventual function of airway EOS.

Sulfonylureas Inhibit Cytokine-Induced Eosinophil Survival and Activation

Eosinophils play a key role in the pathogenesis of asthma and other allergic inflammatory diseases. We have previously shown that treatment of eosinophils with lidocaine preferentially inhibits IL-5-induced survival. This inhibition cannot be overcome by increasing concentrations of IL-5 and is not due to the blocking of Na+ channels by lidocaine. Here we report that one class of K+ channel blockers, the sulfonylureas, inhibits eosinophil survival in a manner similar to lidocaine. The sulfonylurea glyburide inhibits eosinophil survival even at high concentrations of IL-5. In contrast, increasing concentrations of IL-3 or granulocyte-macrophage CSF overcome glyburide inhibition. Glyburide also blocks cytokine-induced eosinophil superoxide production. Similar results were seen with the sulfonylureas tolbutamide and glipizide. Interestingly, the effects of glyburide are not antagonized by the ATP-sensitive K+ channel openers cromakalim, pinacidil, or diazoxide. Although Scatchard analysis of [3H]glyburide binding to eosinophil membranes indicated that the high affinity sulfonylurea receptor (SUR1) is not present on eosinophils, human eosinophils do express mRNA homologous to the sulfonylurea receptor family, in keeping with the presence of a sulfonylurea receptor. Finally, coculture of eosinophils with combinations of glyburide, lidocaine, and dexamethasone resulted in synergistic inhibition of cytokine-mediated eosinophil survival and superoxide production. These results have intriguing clinical implications for the treatment of eosinophil-associated diseases.

Mast Cells Enhance Eosinophil Survival In Vitro: Role of TNF-α and Granulocyte-Macrophage Colony-Stimulating Factor

Mast cell-eosinophil interactions in allergy have not yet been completely defined. To determine whether mast cells influence eosinophil survival, human peripheral blood eosinophils were incubated with rat peritoneal mast cell sonicate. After 3 days, viable eosinophils in medium were 21.3% compared with 44% with mast cell sonicate. Like sonicate, supernatants of compound 48/80-activated mast cells enhanced eosinophil survival, demonstrating that the factor(s) involved is stored preformed and rapidly released. Increased eosinophil survival was due to an inhibition of apoptosis (morphologic analysis; annexin V/PI). Neutralizing Abs to granulocyte-macrophage CSF (GM-CSF), but not to IL-3 or IL-5, decreased by 61.7% the enhancing effect on eosinophil viability. Eosinophils are the source of GM-CSF since its release in the culture medium was inhibited by their incubation with the mast cell sonicate together with dexamethasone. In addition, eosinophils incubated with the sonicate expressed mRNA for GM-CSF. To partially characterize the mast cell-derived factor(s) increasing eosinophil survival, the sonicate was heated (56°C/30 min or 100°C/10 min) or preincubated with antihistamines or with anti-TNF-α-neutralizing Abs. Most of the activity was heat labile. TNF-α was found to be predominantly (70%) responsible, while histamine had no role. Mast cell sonicate also caused eosinophils to release eosinophil peroxidase and to display morphologic signs of activation. In conclusion, we have demonstrated that mast cells enhance eosinophil survival in part through their activation to produce and release the autocrine survival cytokine GM-CSF.

RANTES induces nasal mucosal inflammation rich in eosinophils, basophils, and lymphocytes in vivo

RANTES is a CC chemokine that causes chemotaxis of eosinophils, basophils, and lymphocytes in vitro. The objective of this study was to investigate the effect of RANTES on the influx of inflammatory cells into the nasal mucosa of 12 allergic patients. In the first phase, each patient was challenged with RANTES or diluent on two subsequent days. RANTES caused a significant (p < 0.05) influx of eosinophils as compared with the diluent. The number of eosinophils were 5,548 +/- 1,532/ml and 462 +/- 206/ml after RANTES and diluent challenge, respectively, at the peak of the response at 2 h. There was also a significant influx of metachromatic cells and lymphocytes, but not monocytes, neutrophils, or epithelial cells after RANTES challenge. In the second phase, the patients were first challenged with an allergen and 24 h later, challenged with RANTES or diluent. In the allergen-primed mucosa RANTES induced a significantly higher influx of eosinophils, basophils, and lymphocytes. Further, RANTES caused migration of monocytes and neutrophils, and shedding of epithelial cells. The influx of the inflammatory cells was associated with symptoms of rhinitis. We conclude that RANTES induces a clinically symptomatic inflammatory response in vivo by causing chemotaxis of eosinophils, basophils, and mononuclear cells.

Hematopoietic growth factors for the treatment of myelodysplastic syndromes

Administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF), rh granulocyte-macrophage colony-stimulating factor (rhGM-CSF) or rh interleukin-3 (rhIL-3) effectively stimulate and expand marrow myelopoiesis resulting in a dose-dependent increment of peripheral blood neutrophils in most patients with myelodysplasias (MDS). Clinical outcome with fewer infections have been reported in a few studies using rhG-CSF or rhGM-CSF, including a large randomized, controlled trial with rhGM-CSF. Clinical effective stimulation of megakaryopoiesis and erythropoiesis are however infrequent. Recently, rh erythropoietin (rhEpo) has been used to overcome the ineffective erythropoiesis in MDS to reduce transfusions needed. However, the efficiency has been low in most studies with marked differences in response rates. The most impressive clinical results were obtained in patients with milder forms of MDS combined with low prestudy endogenous S-Epo levels. The possible synergistic effect of combining rhEpo with rhG-CSF or rhGM-CSF has been studied with erythropoietic response rates of about 40%. The safety of the cytokine administration seems acceptable with no significant stimulation of leukemic myelopoiesis and subsequent progression into overt acute myeloid leukemia. In conclusion, combinations of hematopoietic growth factors may be of clinical benefit in some patients with MDS. However, due to the cost and unpredictable clinical outcome there is a need for extended laboratory research to understand the functional defects of MDS stem cells and progenitors.

Inflammatory mediators in naturally occurring rhinitis

BACKGROUND

The mediators released during the allergic inflammatory reaction induce the clinical symptoms of the allergic disease and although there have been numerous studies investigating mediator release in allergen challenge models of allergic rhinitis very few have extended this approach to the study of natural disease.

OBJECTIVE

The aim of this investigation was therefore to measure mast cell and eosinophil mediator levels and indices of vascular permeability in naturally occurring rhinitis.

METHODS

Three groups of subjects were studied, normal non-rhinitics, seasonal allergic rhinitics in and out of the grass pollen season and perennial allergic rhinitics. Mediators were recovered using the technique of nasal lavage and the levels of tryptase, histamine, eosinophil cationic protein and albumin were determined. In addition, eosinophils were enumerated in nasal smears as an indices of underlying inflammation.

RESULTS

The levels of tryptase, eosinophil cationic protein and albumin were significantly higher in the lavage recovered from the symptomatic seasonal allergic rhinitics than when asymptomatic (P = 0.05, P = 0.003, P = 0.009, respectively). These levels of eosinophil cationic protein and albumin were also significantly higher than those of the normal non-rhinitics (P = 0.0008, P = 0.0.003, respectively). In the perennial allergic rhinitics the levels of tryptase, eosinophil cationic protein and albumin were higher than the normal non-rhinitics (P < 0.0001, P = 0.0003, P = 0.0001, respectively). The levels of tryptase and histamine were higher in the perennial allergic rhinitics than the seasonal allergic rhinitics (P = 0.0003, P = 0.006, respectively). These changes in mediator levels were accompanied by a significant influx of eosinophils into the nasal mucosa of both the symptomatic seasonal rhinitics, compared with asymptomatic (P = 0.04) and normal controls (P = 0.0006) and the perennial rhinitics compared to normal controls (P = 0.03).

CONCLUSION

These results indicate that in both naturally occurring seasonal allergic rhinitis and perennial allergic rhinitis mast cell and eosinophil activation occurs and this is accompanied by an increase in vascular permeability. These measurements in lavage fluid provide a method of monitoring the mucosal cellular events in response to therapy.

Glucocorticoids: mechanisms of action and anti-inflammatory potential in asthma

GLUCOCORTICOIDS are potent inhibitors of inflammatory processes and are widely used in the treatment of asthma. The anti-inflammatory effects are mediated either by direct binding of the glucocorticoid/glucocorticoid receptor complex to glucocorticoid responsive elements in the promoter region of genes, or by an interaction of this complex with other transcription factors, in particular activating protein-1 or nuclear factor-kappaB. Glucocorticoids inhibit many inflammation-associated molecules such as cytokines, chemokines, arachidonic acid metabolites, and adhesion molecules. In contrast, anti-inflammatory mediators often are up-regulated by glucocorticoids. In vivo studies have shown that treatment of asthmatic patients with inhaled glucocorticoids inhibits the bronchial inflammation and simultaneously improves their lung function. In this review, our current knowledge of the mechanism of action of glucocorticoids and their anti-inflammatory potential in asthma is described. Since bronchial epithelial cells may be important targets for glucocorticoid therapy in asthma, the effects of glucocorticoids on epithelial expressed inflammatory genes will be emphasized.

Cytokines as targets for the inhibition of eosinophilic inflammation

Eosinophilic inflammation is thought to play a central role in the pathogenesis of asthma. The immunoregulatory effects of interleukin (IL)-4, IL-5 and immunoglobulin (Ig)E suggest that these molecules play key roles in the effector function of eosinophils and mast cells. IL-4 regulates the development of CD4+ TH2-type cells, which elicit essential signals through IL-4 and IL-5 for the regulation of IgE production and eosinophilia, respectively. IL-5-regulated pulmonary eosinophilia and airways dysfunction can also occur independently of IL-4 and allergen-specific Igs. Such IL-4-independent pathways may also play a substantive role in the aetiology of asthma. Thus, evidence is now emerging that allergic airways disease is regulated by humoral and cell-mediated components. The essential and specific role of IL-5 in regulating eosinophilia, and the subsequent involvement of this leukocyte in the induction of lung damage and airways dysfunction, identifies IL-5 as a primary therapeutic target for the relief of airways dysfunction in asthma.

Theophylline accelerates human granulocyte apoptosis not via phosphodiesterase inhibition

Theophylline, in addition to its bronchodilator effect, is reported to have an antiinflammatory action that may account for its clinical effectiveness in the reduction of inflammatory cells in the airway. In bronchial asthma, such inflammatory cytokines as GM-CSF and IL-5 are upregulated and have been proposed to cause granulocyte infiltration (neutrophils and eosinophils) in the airway by inhibition of granulocyte apoptosis. We examined the abilities of theophylline to counteract the prolongation of human granulocyte survival caused by cytokines. Theophylline was shown to shorten granulocyte survival in a dose-dependent manner. Upon incubation with a therapeutical concentration of theophylline (0.1 mM; 18 microg/ml), percentages of GM-CSF (10 ng/ml)-induced delayed apoptosis increased from 18+/-2% to 38+/-3% (p < 0.02) in neutrophils and from 21+/-2% to 35+/-2% (p < 0.02; 24-h incubation) in eosinophils. The percentage of IL-5 (5 ng/ml)-induced delayed eosinophil apoptosis also increased from 22+/-4% to 33+/-2% (P < 0. 05). In contrast, cyclic AMP (cAMP)-increasing agents (3-isobutylmethylxanthine, dibutyryl cAMP, and rolipram) inhibited granulocyte apoptosis in the control and anti-Fas antibody-treated cells. In eosinophils, the expression of bcl-2 protein decreased after incubation with theophylline. These findings suggest that theophylline accelerates granulocyte apoptosis, which may play an essential role in inflammation, and controls granulocyte longevity regardless of the elevation of intracellular cAMP levels.

Curcumin inhibition of Dermatophagoides farinea-induced interleukin-5 (IL-5) and granulocyte macrophage-colony stimulating factor (GM-CSF) production by lymphocytes from bronchial asthmatics

Curcumin, a dietary pigment responsible for the yellow color of curry, has been used for the treatment of inflammatory diseases and exhibits a variety of pharmacological effects such as anti-inflammatory, anti-tumor, anti-oxidant, and anti-viral activity. However, it has not been determined whether the effect of curcumin on the production of cytokine affects eosinophil functions and IgE synthesis. In the present study, we examined the effect of curcumin on the production of interleukin (IL)-2, IL-5, granulocyte macrophage-colony stimulating factor (GM-CSF), and IL-4 by lymphocytes from atopic asthmatics in response to house dust mites (Dermatophagoides farinea: Df) in order to clarify a potential application for allergic diseases. Curcumin inhibited Df-induced lymphocyte proliferation and production of IL-2. Exogenous IL-2 reconstituted the proliferative responsiveness of lymphocytes to Df in the presence of curcumin. Furthermore, curcumin inhibited IL-5, GM-CSF, and IL-4 production in a concentration-dependent manner. These results indicate that curcumin may have a potential effect on controlling allergic diseases through inhibiting the production of cytokines affecting eosinophil function and IgE synthesis.

FcγRII (CD32) Is Linked to Apoptotic Pathways in Murine Granulocyte Precursors and Mature Eosinophils

Murine granulocytes and precursors express low-affinity IgG Fc receptors (FcγR). We investigated the effects of FcγR ligation on the development of eosinophils in cultures of normal murine bone marrow. Eosinophilopoiesis was induced by culture of bone marrow cells in the presence of cytokines (granulocyte-macrophage colony-stimulating factor [GM-CSF], interleukin-3 [IL-3], and IL-5). Addition to the cultures of 2.4G2, a rat monoclonal antibody (mAb) that reacts with FcγRII (CD32) and FcγRIII (CD16), induced granulocyte apoptosis within 24 hours. Granulocytes in cultures that contained 2.4G2 showed chromatin condensation, binding of Annexin-V, and fas induction, and by electron microscopy, apoptosis was most commonly observed in cells of the eosinophil lineage. Since murine granulocytes can express both FcγRII (CD32) and FcγRIII (CD16), we investigated the effect of 2.4G2 on cultures of bone marrow obtained from FcγRIII (CD16) gene–disrupted mice and found that the apoptosis induced with 2.4G2 was CD16-independent. Studies with bone marrow cultures from B6MLR-lpr/lpr and C3H/HEJ-gld/gld mice established that the FcγRII (CD32)-triggered apoptosis was fas-fasL–dependent. When mature eosinophils isolated from hepatic granulomas of Schistosoma mansoni–infected mice were cultured in cytokines in the presence of 2.4G2, the eosinophils underwent apoptosis within 24 hours. These findings identify a previously unknown linkage between FcγR on eosinophils and fas-mediated apoptosis, a connection that could be relevant to mechanisms by which eosinophils mediate tissue injury and antibody-dependent cellular cytotoxicity reactions.

FcγRII (CD32) Is Linked to Apoptotic Pathways in Murine Granulocyte Precursors and Mature Eosinophils

Murine granulocytes and precursors express low-affinity IgG Fc receptors (FcγR). We investigated the effects of FcγR ligation on the development of eosinophils in cultures of normal murine bone marrow. Eosinophilopoiesis was induced by culture of bone marrow cells in the presence of cytokines (granulocyte-macrophage colony-stimulating factor [GM-CSF], interleukin-3 [IL-3], and IL-5). Addition to the cultures of 2.4G2, a rat monoclonal antibody (mAb) that reacts with FcγRII (CD32) and FcγRIII (CD16), induced granulocyte apoptosis within 24 hours. Granulocytes in cultures that contained 2.4G2 showed chromatin condensation, binding of Annexin-V, and fas induction, and by electron microscopy, apoptosis was most commonly observed in cells of the eosinophil lineage. Since murine granulocytes can express both FcγRII (CD32) and FcγRIII (CD16), we investigated the effect of 2.4G2 on cultures of bone marrow obtained from FcγRIII (CD16) gene–disrupted mice and found that the apoptosis induced with 2.4G2 was CD16-independent. Studies with bone marrow cultures from B6MLR-lpr/lpr and C3H/HEJ-gld/gld mice established that the FcγRII (CD32)-triggered apoptosis was fas-fasL–dependent. When mature eosinophils isolated from hepatic granulomas of Schistosoma mansoni–infected mice were cultured in cytokines in the presence of 2.4G2, the eosinophils underwent apoptosis within 24 hours. These findings identify a previously unknown linkage between FcγR on eosinophils and fas-mediated apoptosis, a connection that could be relevant to mechanisms by which eosinophils mediate tissue injury and antibody-dependent cellular cytotoxicity reactions.

Interleukin-3 interleukin-5, and granulocyte-macrophage colony-stimulating factor expression in nasal polyps

PURPOSE

Nasal polyps (NP) are grape-like clusters of chronically inflamed tissue. Little is known about the underlying cells and cytokines involved in nasal polyposis. For the present study, we hypothesize that elevated tissue levels of interleukin-3 (IL-3), interleukin-5 (IL-5), and granulocyte-macrophage colony-stimulation factor (GM-CSF) contribute to eosinophil recruitment and activation in NP.

MATERIALS AND METHODS

To begin to test this hypothesis, we evaluated IL-3, IL-5, and GM-CSF levels and distributions in nasal polyp specimens obtained intraoperatively from 13 patients and two normal controls. For these studies, nasal polyp levels were determined by enzyme-linked immunosorbent assay (ELISA), and IL-3, IL-5, and GM-CSF distribution was determined by immunohistochemistry.

RESULTS

Immunohistochemical staining of the NP indicated that in all 13 patient samples, IL-3, IL-5, and GM-CSF were associated with infiltrating cells, primarily eosinophils, in the NP. Quantitation of IL-3, IL-5, and GM-CSF in NP tissue homogenates indicated that IL-3, IL-5, and GM-CSF levels were evaluated in the NP tissues when compared with control tissues. Additionally, elevation of individual cytokines correlated with previous polypectomy (IL-3), steroid use (IL-3, IL-5, and GM-CSF), asthma (IL-5), and age (GM-CSF).

CONCLUSION

These data support our hypothesis that IL-3, IL-5, and GM-CSF are likely to play a key role in eosinophil recruitment/activation and NP formation and support recently advanced theories that cytokines play a key role in the pathogenesis of this disease.

Inhibitory effect of cetirizine on cytokine-enhanced in vitro eosinophil survival

BACKGROUND

Cetirizine is an antihistamine that inhibits in vivo eosinophil influx into the inflamed airways following allergen challenge, and in vitro eosinophil chemotaxis and adhesion. Since eosinophils are proposed to have an important role in the pathophysiology of asthma and allergic disease, the effects of cetirizine on eosinophil function may be a mechanism of this agent's therapeutic regulation of the allergic reaction.

OBJECTIVE

To determine the effect of cetirizine on in vitro eosinophil survival.

METHODS

Using human eosinophils isolated from patients with allergic rhinitis, the cells were cultured in vitro for 48 to 72 hours with medium, cetirizine, or dexamethasone in the presence of IL-5, IL-3, or GM-CSF. Eosinophil survival was assessed by trypan blue exclusion.

RESULTS

In the presence of IL-5, but not GM-CSF or IL-3 100 microM cetirizine significantly inhibited eosinophil survival at 48 and 72 hours; the magnitude of this inhibition was dependent on cytokine concentration. Although cetirizine significantly suppressed cytokine promotion of eosinophil survival, it was not as potent as dexamethasone.

CONCLUSIONS

Although the in vitro concentration of cetirizine was required to be quite high, cetirizine may affect in vivo airway inflammation through its inhibition of IL-5-dependent eosinophil survival.

The in vivo effects of interleukin-3 on histamine levels in non-Hodgkin's lymphoma patients

Recombinant human Interleukin-3 (RhIL-3) is a haemopoietic growth factor with effect both on early and differentiated cells, such as eosinophils and basophils, and it also acts as a histamine-releasing agent. The purpose of the present study was to examine whether in vivo rhIL-3 administration after chemotherapy affected basophil histamine levels and whether a concordance between rhIL-3 induced histamine release and side effects during the treatment could be demonstrated. Thirty patients with non-Hodgkin's lymphoma entered the study. All patients received 6 courses of chemotherapy, rhIL-3 was administered subcutaneously once daily after the second and the fourth course of chemotherapy from cycle day 2-15 at the dose levels 0.5, 1.0, 5.0, 7.5 and 10 micrograms/kg with 6 patients at each dose level. In cycle 6 recombinant human Granulocyte-Macrophage Colony-Stimulating Factor (rhGM-CSF) (3.0 micrograms/kg) was administered sequential/concurrent day 9-15 to rhIL-3 (day 2-15) at all dose levels except 7.5 micrograms/kg, where rhIL-3 was given day 2-8 and rhGM-CSF sequential day 9-15. Cycles 1, 3 and 5 served as control cycles with no cytokine therapy. During rhIL-3 treatment, and after CHOP chemotherapy, the basophil counts increased moderately especially during the recovery period day 15-22, and mainly at the two highest dose levels 7.5 and 10 micrograms/kg, but never exceeded the normal upper limit. Histamine levels in basophils were the same in patients before chemotherapy and healthy volunteers, and except from a trend to increased histamine level at 10 micrograms/kg on day 15, no difference was noted between rhIL-3 cycles and control cycles. Within 3-4 hr after rhIL-3 administration, a drop in histamine level in basophils was noted, which could be due to histamine-releasing properties of rhIL-3 as previously demonstrated by in vitro studies. No serious side effects were noted during the cytokine treatment, and despite that most patients had mild flushing of the face, neck and upper chest, no patients experienced sensitization throughout the study. Although a significant increase in rhIL-3-induced histamine release from basophils was noted in some of the patients, no correlation to the dose of rhL-3 was found, and no correlation was noted between side effects and histamine release or histamine levels in basophils.

Mast cells, eosinophils and fibrosis

We have presented results that increase our understanding of the roles MC and EOS play in modulating fibrotic processes. In vitro studies have provided clear-cut evidence for the direct involvement of these two inflammatory cells in enhancing proliferation, and either enhancing or decreasing collagen synthesis in human fibroblasts isolated from different anatomical locations. In addition, we have shown that MC and EOS interactions can also take part in modulating fibrosis. In vivo studies in murine and human cGVHD showed that MC activation is detrimental, and that MC stabilization therapy may be helpful in treating the fibrotic outcome of this disease. Much is still obscure. It is, for example, important to define the MC and EOS mediators involved in the modulation of fibroblast properties, and their pattern of influence, keeping in mind the ultimate goal of defining new therapeutic targets for the treatment of fibrotic diseases.

Steroid therapy in obstructive airway diseases

Asthma and chronic obstructive pulmonary disease (COPD) are two common illnesses that cause significant morbidity and mortality. Steroids are widely used in both conditions. They act through steroid or glucocorticoid receptors (GR) causing up or down regulation of protein synthesis resulting in an increase in lipocortin 1 and beta 2 adrenergic receptors, and decreased levels and activities of cytokines or cytokine receptors, which reduces the inflammatory process in the airways and decreases bronchial hyperreactivity. Consequently symptoms of airway obstruction are alleviated and lung function is improved. In asthma, steroids have been convincingly shown to be effective in the treatment of both acute exacerbations and chronic condition. In COPD, however, only a subset of patients seem to respond favourably to steroid therapy. Therapeutic trials are therefore recommended before committing to a long-term treatment in order to determine this subset of patients, as no markers of steroid responsiveness can be identified. The inhaled steroids currently available have a good safety profile with significant side effects occurring only occasionally. Such side effects are usually confined to the oropharynx, causing local irritation, candidiasis and dysphonia, which can be easily overcome. Biochemical abnormalities involving bone, adrenal, carbohydrate and lipid profiles have been noted with high doses of inhaled steroids; however, these have no significant clinical effects.

Relationship between interleukin-5 and eotaxin in regulating blood and tissue eosinophilia in mice

The mechanism of cooperation between IL-5 and eotaxin for the selective accumulation of eosinophils at sites of allergic inflammation is unknown. In this investigation we have used IL-5 deficient mice to define the relationship between this cytokine and eotaxin in the regulation of blood eosinophilia and eosinophil homing and tissue accumulation. Both IL-5 and eotaxin could independently induce a rapid and pronounced blood eosinophilia in wild type mice when administered systemically. In contrast, only eotaxin induced a pronounced blood eosinophilia in IL-5 deficient mice. The eosinophilic response induced by intravenous eotaxin in wild type mice did not correlate with a significant reduction in the level of bone marrow eosinophils, whereas intravenous IL-5 resulted in depletion of this store. These results suggest the existence of two mechanisms by which eosinophils can be rapidly mobilized in response to intravenous eosinophil chemoattractants; first, mobilization of an IL-5 dependent bone marrow pool, and second, an eotaxin-induced sequestration of eosinophils from tissues into the blood. Subcutaneous injection of eotaxin induced a local tissue eosinophilia in wild type mice but not in IL-5 deficient mice. Furthermore, tissue eosinophilia in wild type mice, but not in IL-5 deficient mice, was enhanced by adoptive transfer of eosinophils or the administration of intravenous IL-5. However, pretreatment of IL-5 deficient mice with intraperitoneal IL-5 for 72 h restored eosinophil homing and tissue accumulation in response to subcutaneous eotaxin. We propose that eotaxin secreted from inflamed tissue may play an important role in initiating both blood and tissue eosinophilia in the early phases of allergic inflammation. Furthermore, IL-5 is not only essential for mobilizing eosinophils from the bone marrow during allergic inflammation, but also plays a critical role in regulating eosinophil homing and migration into tissues in response to eotaxin and possibly other specific chemotactic stimuli.

Eosinophil apoptosis caused by theophylline, glucocorticoids, and macrolides after stimulation with IL-5

BACKGROUND

Glucocorticoids have long been used as the most potent drugs in the treatment of bronchial asthma. Data reported recently have led to the proposal that theophylline and macrolides have antiinflammatory effects.

OBJECTIVE

We examined the abilities of theophylline, glucocorticoids, and macrolides to counteract the prolongation of eosinophil survival caused by IL-5.

METHODS

Purified guinea pig eosinophils were cultured in the presence or absence of human IL-5 and with or without the aforementioned drugs at various concentrations. The percentage of cells alive after 3 days in culture was determined.

RESULTS

Aminophylline (AM), methylprednisolone (MP), erythromycin (EM), and clarithromycin (CAM) suppressed the IL-5 induced prolongation of eosinophil survival in a dose-dependent manner. The effects of these drugs on eosinophil survival were significantly greater at low concentrations of IL-5 than at high concentrations of IL-5. When eosinophils were cultured in the presence of IL-5 (1 ng/ml) with physiologic concentrations of MP (10(-6) mol/L), AM (10(-4) mol/L), and either EM or CAM (both 10 micrograms/ml), the effect of IL-5 was almost completely abolished, and the morphologic changes in eosinophils observed by electron microscopy were consistent with apoptosis. DNA extracted from eosinophils cultured with IL-5 and each of the drugs was definitely fragmented.

CONCLUSIONS

One mechanism of the effectiveness of these drugs is induction of eosinophil apoptosis. Some combination of these drugs may be useful in the treatment of bronchial asthma.

Inhibition by the immunosuppressive agent FK-506 of antigen-induced airways eosinophilia and bronchial hyperreactivity in mice

1. The effect of the immunosuppressive agent, FK-506, an allergen-induced airways eosinophilia and bronchial hyperreactivity (BHR) in hyper IgE mice (BP2 selection) was investigated. 2. Administration of FK-506 at 2 mg kg-1 s.c., 1 h before and 5 h after the first four ovalbumin challenges, reduced the recruitment of eosinophils into the bronchoalveolar lavage fluid (BALF) from 1.36 +/- 0.22 x 10(5) to 0.53 +/- 0.24 x 10(5) cells ml-1 (n = 5-6, P < 0.05; 60% inhibition), inhibited by 80% BHR in response to i.v. 5-HT and practically suppressed BHR in response to inhaled methacholine. 3. The antigen-induced interleukin (IL)-5 formation in the BALF and serum was inhibited by FK-506 by 75% in both instances. 4. FK-506 failed to modify the bronchoconstriction in BP2 mice, suggesting that different mechanisms are involved in acute bronchoconstriction and BHR. 5. The increased number of CD4+, CD8+, CD3+ T lymphocytes in the BALF to antigen-challenged mice was unaffected by FK-506. 6. These findings indicate that antigen-induced in vivo IL-5 release and eosinophil, but not T-cell, infiltration into the bronchial lumen of sensitized BP2 mice are targets for the anti-allergic activities of FK-506.

Differential regulation of eosinophil adhesion under conditions of flow in vivo

The proinflammatory role of eosinophils in patients with allergic inflammation is now well recognized. However, the molecular mechanisms mediating the sequential events of eosinophil recruitment from the blood stream to sites of allergic inflammation under conditions of shear force have not been clearly established. Using the xenogeneic rabbit model system to study human eosinophil adhesion under conditions of flow in vivo, we have demonstrated that eosinophils like neutrophils roll, adhere, and extravasate across cytokine-stimulated endothelial cells at physiological shear rates in vivo. Eosinophils rolling on venular endothelial cells is mediated by L-selectin and VLA-4. Mediators of cellular activation such as GM-CSF, PAF, or PMA had a differential effect on neutrophil and eosinophil receptor expression and their rolling function. It would thus appear that acting sequentially or in concert a variety of cytokines, including GM-CSF, RANTES, IL-5, and specific cell adhesion molecules (VLA-4/VCAM-1) might play a critical role in the selective sequestration of eosinophils and other proinflammatory leukocytes into the inflamed tissues during episodes of allergic inflammation. Further understanding of the function of these mediators as well as other traffic signals that regulate eosinophil adhesion will help in developing better therapeutic strategies to block the emigration of eosinophils from the blood stream, and also to inhibit the activation of eosinophils once they have reached sites of tissue inflammation.

TH2-type cytokines in asthma

TH2-type cytokines, particularly interleukin-5, together with granulocyte-macrophage colony-stimulating factor and interleukin-3, orchestrate the eosinophil response in asthma. Eosinophils are believed to be prime proinflammatory effector cells causing bronchial damage, which in turn, leads to chronic asthma symptoms. Although many cells may secrete cytokines (e.g., mast cells, epithelial cells, macrophages), all of which influence eosinophil differentiation, survival, and function, the TH2-type T cell is seen as having a central role since it is capable of direct antigen recognition. The putative "driving" antigen for asthmatic inflammation may be allergen, although other antigens (e.g., viral, epithelial) are also possible candidates. Although T cells also influence the synthesis of IgE, IgE-mediated mechanisms are seen as playing a secondary role only in atopic subjects, where they may be responsible for acute, short-lived symptoms superimposed on the chronic, on-going cell-mediated inflammatory disease.