Chemokines and chemokine receptors: their role in allergic airway disease

Regulation of Chemokine-Receptor Interactions and Functions

Inflammation is the body's response to injury or infection. As early as 2000 years ago, the Roman encyclopaedist Aulus Cornelius Celsus recognised four cardinal signs of this response-redness, heat, swelling and pain; a fifth sign is loss of function.[...].

AcCystatin, an immunoregulatory molecule from Angiostrongylus cantonensis, ameliorates the asthmatic response in an aluminium hydroxide/ovalbumin-induced rat model of asthma

Epidemiological surveys have demonstrated that helminth infections are negatively related to atopic diseases, including asthma. Defining and characterising specific helminth molecules that have excellent immunomodulatory capacities as potential therapeutics for the treatment or prophylaxis of allergic manifestations are of great interest. AcCystatin, a cystatin protease inhibitor of Angiostrongylus cantonensis, is a homologue of other nematode cystatins with immunoregulatory properties. Here, we aim to determine the effects of AcCystatin on an ovalbumin/aluminium hydroxide (OVA/Al[OH]3)-induced rat model of asthma. Wistar rats were randomly divided into four groups, including a control group, an OVA/Al[OH]3-induced asthma group, a group receiving AcCystatin immunisation prior to OVA/Al[OH]3-induced asthma and a group receiving AcCystatin treatment after OVA/Al[OH]3-induced asthma. The numbers of eosinophils, basophils, neutrophils, lymphocytes and monocytes in the peripheral blood and of eosinophils in the bronchoalveolar lavage fluid (BALF) were counted for each animal. The expression levels of the cytokines interferon-γ, interleukin (IL) 4, IL-5, IL-6, IL-10, IL17A and tumour necrosis factor receptor-α in BALF, of OVA-specific immunoglobulin E in BALF and serum and of the chemokines eotaxin-1, eotaxin-2, eotaxin-3, MCP-1 and MCP-3 in lung tissue were measured. In addition, the degree of peribronchial and perivascular inflammation and the intensity of goblet cell metaplasia were qualitatively evaluated. The sensitised/challenged rats developed an extensive cell inflammatory response of the airways. AcCystatin administration significantly reduced the cellular infiltrate in the perivascular and peribronchial lung tissues and reduced both goblet mucous production and eosinophil infiltration. The rats that were treated with AcCystatin before or after sensitisation with OVA showed significant decreases in eotaxin-1, eotaxin-3 and MCP-1 expression in the lung tissue. The production of IL-4, IL-5, IL-6 and IL-17A and of OVA-specific IgE antibodies was also significantly reduced in AcCystatin-treated rats compared with untreated asthmatic rats. The AcCystatin treatment was associated with a significant increase in IL-10 levels. Our present findings provide the first demonstration that AcCystatin is an effective agent in the prevention and treatment of the airway inflammation associated with asthma.

Allergen-induced resistin-like molecule-α promotes esophageal epithelial cell hyperplasia in eosinophilic esophagitis

Resistin-like molecule (Relm)-α is a secreted, cysteine-rich protein belonging to a newly defined family of proteins, including resistin, Relm-β, and Relm-γ. Although resistin was initially defined based on its insulin-resistance activity, the family members are highly induced in various inflammatory states. Earlier studies implicated Relm-α in insulin resistance, asthmatic responses, and intestinal inflammation; however, its function still remains an enigma. We now report that Relm-α is strongly induced in the esophagus in an allergen-challenged murine model of eosinophilic esophagitis (EoE). Furthermore, to understand the in vivo role of Relm-α, we generated Relm-α gene-inducible bitransgenic mice by using lung-specific CC-10 promoter (CC10-rtTA-Relm-α). We found Relm-α protein is significantly induced in the esophagus of CC10-rtTA-Relm-α bitransgenic mice exposed to doxycycline food. The most prominent effect observed by the induction of Relm-α is epithelial cell hyperplasia, basal layer thickness, accumulation of activated CD4(+) and CD4(-) T cell subsets, and eosinophilic inflammation in the esophagus. The in vitro experiments further confirm that Relm-α promotes primary epithelial cell proliferation but has no chemotactic activity for eosinophils. Taken together, our studies report for the first time that Relm-α induction in the esophagus has a major role in promoting epithelial cell hyperplasia and basal layer thickness, and the accumulation of activated CD4(+) and CD4(-) T cell subsets may be responsible for partial esophageal eosinophilia in the mouse models of EoE. Notably, the epithelial cell hyperplasia and basal layer thickness are the characteristic features commonly observed in human EoE.

Acteoside inhibits type Ι allergy through the down-regulation of Ca/NFAT and JNK MAPK signaling pathways in basophilic cells

We have previously reported that acteoside inhibits the release of β-hexosaminidase from immunoglobulin E (IgE)-sensitized and bovine serum albumin-stimulated rat basophilic leukemia cells as well as the intracellular calcium level, release of histamine from, and production of tumor necrosis factor-alpha and interleukin-4 in human basophilic (KU812) cells. However, the molecular mechanism underlying the anti-allergic effects of acteoside has not yet been elucidated. Here, we used microarray analysis to determine the global gene expression profile of KU812 cells treated with acteoside and calcium ionophore A23187 plus phorbol-12-myristate 13-acetate (A23187+PMA), and the results were validated by real-time polymerase chain reaction (PCR) and Western blotting. Microarray analysis results showed that of the 201 genes in the microarray, 149 genes were up-regulated, while 52 genes were down-regulated. The significantly down-regulated genes have functions as chemokine and IgE receptors, as well as for immune response. Results of the validation of the microarray results using real-time PCR showed a significant decrease in the expressions of Fc fragment of IgE, high affinity I, receptor for; alpha polypeptide (FCER1A) and nuclear factor of activated T cell, cytoplasmic, calcineurin-dependent 1 (NFATC1) genes. Furthermore, Western blotting showed a decrease in the phosphorylation of mitogen-activated protein kinase (MAPK) Jun N terminal kinase (JNK), revealing the role of JNK MAPK in acteoside-mediated allergy inhibition. We determined that the anti-allergy effects of acteoside were due to the down-regulation of the expressions of the chemokine ligand 1 (CCL1), CCL2, CCL3, CCL4, FCER1A and NFATC1 genes and the inhibition of the MAPK pathway through decreased JNK phosphorylation.

Eosinophils in glioblastoma biology

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. The development of this malignant glial lesion involves a multi-faceted process that results in a loss of genetic or epigenetic gene control, un-regulated cell growth, and immune tolerance. Of interest, atopic diseases are characterized by a lack of immune tolerance and are inversely associated with glioma risk. One cell type that is an established effector cell in the pathobiology of atopic disease is the eosinophil. In response to various stimuli, the eosinophil is able to produce cytotoxic granules, neuromediators, and pro-inflammatory cytokines as well as pro-fibrotic and angiogenic factors involved in pathogen clearance and tissue remodeling and repair. These various biological properties reveal that the eosinophil is a key immunoregulatory cell capable of influencing the activity of both innate and adaptive immune responses. Of central importance to this report is the observation that eosinophil migration to the brain occurs in response to traumatic brain injury and following certain immunotherapeutic treatments for GBM. Although eosinophils have been identified in various central nervous system pathologies, and are known to operate in wound/repair and tumorstatic models, the potential roles of eosinophils in GBM development and the tumor immunological response are only beginning to be recognized and are therefore the subject of the present review.

Differences in the concentration and correlation of cervical immune markers among HPV positive and negative perimenopausal women

INTRODUCTION

Women≥45years of age with persistent HPV infections have distinct peripheral circulating immune profiles. Few studies have comprehensively evaluated the cervical immunologic microenvironment in HPV-positive and HPV-negative perimenopausal women.

METHODS

We collected cervical secretion specimens from 34 high risk HPV (HR-HPV) positive and 44 HR-HPV negative women enrolled in an ongoing prospective cohort assessing the natural history of HPV across the menopausal transition. We used these specimens to quantify concentrations of 27 different immune markers using multiplexed bead-based immunoassays.

RESULTS

HR-HPV positive women had significantly higher median concentrations of IL-5 (0.11 ng/mgtotal protein vs. 0.08 ng/mgtotal protein), IL-9 (2.7 ng/mgtotal protein vs. 2.1 ng/mgtotal protein), IL-13 (2.1 ng/mgtotal protein vs. 0.9 ng/mgtotal protein), IL-17 (2.9 ng/mgtotal protein vs. 1.1 ng/mgtotal protein), EOTAXIN (4.1 ng/mgtotal protein vs. 1.1 ng/mgtotal protein), GM-CSF (4.3 ng/mgtotal protein vs. 3.3 ng/mgtotal protein), and MIP-1α (3.5 ng/mgtotal protein vs. 1.9 ng/mgtotal protein) compared to HR-HPV negative women. A shift in the correlation of T-cell and pro-inflammatory cytokines (IFN-γ, IL-5, IL-9, IL-10, IL-12, IL-13, IL-15, and TNF-α) from IL-2 to EOTAXIN was observed between HR-HPV negative and positive women.

CONCLUSIONS

Higher local concentrations of anti-inflammatory and allergy associated markers, with a shift in T-cell associated cytokine correlation from IL-2 to EOTAXIN, are associated with HPV infection among older women.

Decreased proinflammatory cytokines production in children with complicated parapneumonic pleural effusion after intrapleural fibrinolytic treatment

Intrapleural fibrinolytic therapy (IFT) provides clinical benefit in the treatment of complicated pleural parapneumonic effusion (CPE). Whether IFT influences the proinflammatory cytokines production and fibrinlytic activity is currently unclear. Therefore, we collected pleural effusion samples from CPE patients with IFT (study group) and patients without IFT (control group). A membrane human inflammatory cytokines array kit was used to compare the difference of targeted cytokine production between these two groups. Enzyme-linked immunosorbent assay (ELISA) methods were used for quantitative analysis of targeted cytokines and fibrinolytic enzymes. The results showed there were no significant differences between the study (n = 16) and control (n = 14) groups in patients' demographic data. After fibrinolytic therapy, the patients in the study group had significant lower plasminogen activator inhibitor (PAI) level (732.36+/-254.09 ng/mL vs 1,509.36+/-1,340.11 ng/mL, p<0.05) and higher urokinase plasminogen activator (u-PA) level (75.56+/-41.70 ng/mL vs 6.87+/-5.07 ng/mL, p<0.05) than they did before treatment. Moreover, the tissue inhibitors of metalloproteinase-2 (TIMP-2) (1,560.03+/-403.49 pg/mL vs 3,686.45+/-1,263.83 pg/mL, p<0.05) and inflammatory chemokine, regulated on activation normal T-cell expressed and secreted/chemokine (C-C motif) ligand 5 (RANTES), (293.58+/-212.93 pg/mL vs 749.27+/-53.79 pg/mL, p<0.05), were also significantly lower in the study group after fibrinolytic therapy, but not in the control group. In conclusion, intrapleural fibrinolytic treatment with urokinase could enhance fibrinolytic activity and decrease TIMP-2 and RANTES production.

Genetic contribution of chemokine receptor 2 (CCR2) polymorphisms towards increased serum total IgE levels in Indian asthmatics

The chemokine (C-C motif) receptors (CCR) 2 and 5 are members of a large family of G protein-coupled receptors, playing important roles in asthma pathogenesis. Using standard sequencing techniques, a total of 15 single nucleotide and 8 insertion/deletion polymorphisms (DIPs) (5 novels) were identified in and around these two genes. None of the studied polymorphisms (N=7, selected on the basis on linkage disequilibrium) was associated with asthma in a case (N=315) - control (N=337) study and showed no evidence for non-random transmission to individuals with asthma/atopy in Indian pedigrees (n=235). However, multilocus haplotype analysis based on simulations yielded a P=0.00005 in the case-control study and a P=0.03 for the family-based association studies. Furthermore, rs3918356 and rs743660 polymorphisms in CCR2 were found to be associated with total serum IgE levels in both the study designs. Thus, our study supports a significant role for chemokine receptor polymorphisms in genetic susceptibility to asthma.

2007 E. Mead Johnson award: scientific pursuit of the allergy problem

My research has focused on elucidating the allergy problem over the past two decades. The primary approach has been to uncover critical mechanisms of allergic inflammation, with particular focus on eosinophils, a hallmark cellular constituent of allergic responses. Molecular processes that bridge T helper cell type 2 (TH2) immunity with eosinophilia and key checkpoints for regulating eosinophilia have been uncovered. Notably, interleukin (IL)-5 (derived from TH2 cells) has been identified as the chief hematopoietin responsible for eosinophil expansion in the circulation. Pathways for selective eosinophil mobilization from the blood stream to the tissue have been uncovered by defining the role of the eotaxin subfamily of chemokines in eosinophil chemoattraction and activation. Finally, TH2 cell derived IL-4 and IL-13 have been defined as chief inducers of the eotaxins, and upstream orchestrators of eosinophilic inflammation. These translational studies have formulated novel therapeutic strategies (currently being tested) for a variety of eosinophilic conditions, with particular attention on hypereosinophilic syndromes and eosinophil-associated gastrointestinal disorders such as eosinophilic esophagitis.

Expression and regulation of CCR1 by airway smooth muscle cells in asthma

C-C chemokines such as CCL11, CCL5, and CCL3 are central mediators in the pathogenesis of asthma. They are mainly associated with the recruitment and the activation of specific inflammatory cells, such as eosinophils, lymphocytes, and neutrophils. It has recently been shown that they can also activate structural cells, such as airway smooth muscle and epithelial cells. The aims of this study were to examine the expression of the CCL3 receptor, CCR1, on human airway smooth muscle cells (ASMC) and to document the regulation of this receptor by cytokines involved in asthma pathogenesis. We first demonstrated that CCR1 mRNA is increased in the airways of asthmatic vs control subjects and showed for the first time that ASMC express CCR1 mRNA and protein, both in vitro and in vivo. Calcium mobilization by CCR1 ligands confirmed its functionality on ASMC. Stimulation of ASMC with TNF-alpha and, to a lesser extent, IFN-gamma resulted in an up-regulation of CCR1 expression, which was totally suppressed by both dexamethasone or mithramycin. Taken together, our data suggest that CCR1 might be involved in the pathogenesis of asthma, through the activation of ASMC by its ligands.

Effects of in vitro exposure to hay dust on expression of interleukin-17, -23, -8, and -1beta and chemokine (C-X-C motif) ligand 2 by pulmonary mononuclear cells isolated from horses chronically affected with recurrent airway disease

OBJECTIVE

To examine effects of in vitro exposure to solutions of hay dust, lipopolysaccharide (LPS), or beta-glucan on cytokine expression in pulmonary mononuclear cells isolated from healthy horses and horses with recurrent airway obstruction (RAO).

ANIMALS

8 RAO-affected and 7 control horses (experiment 1) and 6 of the RAO-affected and 5 of the control horses (experiment 2).

PROCEDURES

Bronchoalveolar lavage cells were isolated from horses that had been stabled and fed dusty hay for 14 days. Pulmonary mononuclear cells were incubated for 24 (experiment 1) or 6 (experiment 2) hours with PBS solution or solutions of hay dust, beta-glucan, or LPS. Gene expression of interleukin (IL)-17, IL-23(p19 and p40 subunits), IL-8, IL-1beta, and chemokine (C-X-C motif) ligand 2 (CXCL2) was measured with a kinetic PCR assay.

RESULTS

Treatment with the highest concentration of hay dust solution for 6 or 24 hours increased expression of IL-23(p19 and p40), IL-8, and IL-1beta in cells from both groups of horses and increased early expression of IL-17 and CXCL2 in RAO-affected horses. Lipopolysaccharide upregulated early expression of IL-23(p40) and IL-8 in cells from both groups of horses but only late expression of these cytokines in cells from RAO-affected horses. Treatment with beta-glucan failed to increase cytokine expression at 6 or 24 hours.

CONCLUSIONS AND CLINICAL RELEVANCE

Cells from RAO-affected horses were not more responsive to the ligands tested than were cells from control horses, which suggests a minimal role of mononuclear cells in propagation of airway neutrophilia in horses with chronic RAO.

A novel antagonist of CRTH2 blocks eosinophil release from bone marrow, chemotaxis and respiratory burst

BACKGROUND

Chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) has been revealed to be a novel receptor for prostaglandin (PG) D(2), which is a major mast cell product released during the allergic response. The aim of this study was to analyze the effects of a newly developed small molecule antagonist of CRTH2, Cay10471, on eosinophil function with respect to recruitment, respiratory burst and degranulation.

METHODS

Chemotaxis of guinea pig bone marrow eosinophils and human peripheral blood eosinophils were determined using microBoyden chambers. Eosinophil release from bone marrow was investigated in the in situ perfused guinea pig hind limb preparation. Respiratory burst and degranulation were measured by flow cytometry.

RESULTS

Cay10471 bound with high affinity to recombinant human and guinea pig CRTH2, but not DP, receptors. The antagonist prevented the PGD(2)-induced release of eosinophils from guinea pig bone marrow, and inhibited the chemotaxis of guinea pig bone marrow eosinophils and human peripheral blood eosinophils. Pretreatment with PGD(2) primed eosinophils for chemotaxis towards eotaxin, and this effect was prevented by Cay10471. In contrast, PGD(2) inhibited the C5a-induced up-regulation of CD63, a cellular marker of degranulation, in a Cay10471-sensitive manner. Finally, Cay10471 abolished the respiratory burst of eosinophils upon stimulation by PGD(2).

CONCLUSION

These data further emphasize the importance of CRTH2 in eosinophil function and show that Cay10471 is a highly potent and selective antagonist of PGD(2)-induced eosinophil responses. Cay10471 might hence be a useful compound for the treatment of allergic diseases.

Microarray-based identification of novel biomarkers in asthma

Bronchial asthma is a complicated and diverse disorder affected by genetic and environmental factors. It is widely accepted that it is a Th2-type inflammation originating in lung and caused by inhalation of ubiquitous allergens. The complicated and diverse pathogenesis of this disease yet to be clarified. Functional genomics is the analysis of whole gene expression profiling under given condition, and microarray technology is now the most powerful tool for functional genomics. Several attempts to clarify the pathogenesis of bronchial asthma have been carried out using microarray technology, providing us some novel biomarkers for diagnosis, therapeutic targets or understanding pathogenic mechanisms of bronchial asthma. In this article, we review the outcomes of these analyses by the microarray approach as applied to this disease by focusing on the identification of novel biomarkers.

Induction of adhesion molecules upon the interaction between eosinophils and bronchial epithelial cells: involvement of p38 MAPK and NF-kappaB

Eosinophils are principal effector cells of inflammation in allergic asthma, characterized by their infiltration and accumulation at inflammatory sites mediated by chemokine eotaxin, and interaction with adhesion molecules expressed on bronchial epithelial cells. In this study, tumor necrosis factor (TNF)-alpha and/or the interaction of eosinophils and bronchial epithelial BEAS-2B cells were found to up-regulate the cell surface expression of adhesion molecules intercellular adhesion molecule (ICAM)-1 and vascular adhesion molecule (VCAM)-1 on BEAS-2B cells, and ICAM-1 and leukocyte function-associated antigen-1 (LFA-1) on eosinophils. Interaction of eosinophils and BEAS-2B cells could induce the release of granulocyte macrophage colony-stimulating factor (GM-CSF) and activate both p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappaB activities in BEAS-2B cells but only NF-kappaB activity in eosinophils. Both proteasome inhibitor MG-132 and selective p38 MAPK inhibitor SB 203580 could significantly decrease the expression of ICAM-1 on BEAS-2B cells and CD18 on eosinophils upon co-culture with or without TNF-alpha treatment. However, the expression of VCAM-1 on BEAS-2B cells was only up-regulated by TNF-alpha-induced NF-kappaB activity. The interaction of eosinophils and bronchial epithelial cells therefore plays an important role in the up-regulation of adhesion molecules on eosinophils and epithelial cells via differential intracellular signalling pathways during allergic inflammation.

Hierarchy of eosinophil chemoattractants: role of p38 mitogen-activated protein kinase

Several chemoattractants can regulate the recruitment of eosinophils to sites of inflammation, but the hierarchy among them is unknown. We observed here that eosinophil chemotaxis towards eotaxin or 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) was amplified up to sixfold in the presence of prostaglandin (PG) D2. This effect was only seen in eosinophils, and not in neutrophils or basophils. Pretreatment with the chemoattractant receptor-homologous molecule expressed on TH2 cells (CRTH2) antagonist ramatroban prevented the PGD2 enhancement of eosinophil migrations. In contrast, eotaxin or 5-oxo-ETE inhibited the migration of eosinophils towards PGD2. 5-oxo-ETE enhanced the chemotaxis to eotaxin, while eotaxin had no effect on 5-oxo-ETE-induced migration. 5-oxo-ETE induced the phosphorylation of p38 mitogen-activated protein kinase, and inhibition of p38 mitogen-activated protein kinase by SB-202190 converted the effect of 5-oxo-ETE on the chemotaxis to PGD2 from inhibition to enhancement. The presence of blood or plasma markedly decreased the sensitivity of eosinophils to eotaxin or 5-oxo-ETE, while responses to PGD2 were unaltered. In conclusion, PGD2 might be an initial chemoattractant, since it maintains its potency in the circulation and augments the responsiveness of eosinophils to other chemoattractants. In contrast, eotaxin seems to be an end-point chemoattractant, since it has reduced efficacy in blood and is capable of down-modulating eosinophil responsiveness to other chemoattractants.

Time-dependent alterations in gene expression of interleukin-8 in the bronchial epithelium of horses with recurrent airway obstruction

OBJECTIVE

To evaluate time-dependent alterations in gene expression of chemokines in bronchial epithelium of recurrent airway obstruction (RAO)-affected horses and whether alterations resulted from increases in gene expression of interleukin (IL)-17 in cells isolated from bronchoalveolar lavage fluid (BALF).

ANIMALS

8 RAO-susceptible horses and 9 control horses.

PROCEDURE

In 2 experiments, both groups of horses were evaluated after being maintained on pasture and after being stabled and fed dusty hay for 1, 14, 35, and 49 days (experiment 1) or 14 and 28 days (experiment 2). In experiment 1, gene expression of IL-8, chemokine (C-X-C motif) ligand 1 (CXCL1), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), and Toll-like receptor 4 (TLR4) in epithelium and IL-8, IL-17, and TLR4 in BALF cells was measured. In experiment 2, bronchial biopsy specimens were evaluated for IL-8 immunoreactivity.

RESULTS

In RAO-susceptible horses after 14 days of challenge exposure, there was a 3- and 10-fold increase in gene expression of IL-8 for epithelial and BALF cells and an increase in IL-8 immunoreactivity in epithelial cells. Challenge exposure failed to alter gene expression of CXCL1, GM-CSF, G-CSF, and TLR4 in epithelial cells of any horses at any time point. During challenge exposure, gene expression of BALF cell IL-17 was downregulated in control horses (day 1) and upregulated in RAO-affected horses (day 35).

CONCLUSIONS AND CLINICAL RELEVANCE

Epithelial-derived IL-8 may promote airway neutrophilia, but the inciting stimulus is unlikely to be IL-17 because upregulation of this gene is subsequent to that of IL-8 in epithelial cells.

Anti-asthmatic activity of an ethanol extract from Saururus chinensis

As an attempt to find bioactive medicinal herbs exerting anti-asthmatic activity, the effects of an ethanol extract from the parts of Saururus chinensis were evaluated in both in vitro and in vivo. The ethanol extract of S. chinensis (ESC) inhibited generation of the cyclooxygenase-2 (COX-2) dependent phases of prostaglandin D(2) in bone marrow-derived mast cells in a concentration-dependent manner with an IC(50) value of 14.3 microg/ml. ESC also inhibited leukotriene C(4) production with an IC(50) value of 0.3 microg/ml. This demonstrates that ESC has COX-2/5-lipoxygenase dual inhibitory activity. In addition, this compound inhibited degranulation reaction in a dose dependent manner, with an IC(50) value of 1.3 microg/ml. An ovalbumin induced mouse asthmatic animal model was used to determine its in vivo anti-asthmatic activity. The oral administration (50-200 mg/kg) of ESC reduced the number of infiltrated eosinophil in a bronchoalveolar lavage fluid. Furthermore, ESC (100 mg/kg) inhibited the eotaxin and IL-4 mRNA expression levels. These results suggest that the anti-asthmatic activity of S. chinensis might in part occur via the inhibition of eicosanoid generation, degranulation as well as the down regulation of IL-4 and eotaxin mRNA expression.

Anti-inflammatory Activity of Ailanthus altissima in Ovalbumin-Induced Lung Inflammation

As part of an ongoing investigation to find bioactive medicinal herbs exerting anti-inflammation activity, the effect of an ethanol extract from the parts of Ailanthus altissima (Simaroubaceae) was evaluated in both in vitro and in in vivo system. The ethanol extract of A. altissima (EAa) inhibited generation of the cyclooxygenase-2 (COX-2) dependent phases of prostaglandin D2 in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with an IC50 value of 214.6 microg/ml. However, this compound did not inhibit COX-2 protein expression up to a concentration of 400 microg/ml in the BMMC, indicating that EAa directly inhibits COX-2 activity. In addition, EAa inhibited leukotriene C4 production with an IC50 value of 25.7 microg/ml. Furthermore, this compound inhibited degranulation reaction in a dose dependent manner, with an IC50 value of 27.3 microg/ml. Ovalbumin (OVA)-sensitized mice were orally pretreated with EAa before aerosol challenges. EAa reduced the eosinophil infiltration into the airway and the eotaxin, IL-4, and IL-13 mRNA expression levels. These results suggest that the anti-inflammation activity of A. altissima in OVA-induced lung inflammation may occur in part via the down regulation of T(H)2 cytokines and eotaxin transcripts as well as the inhibition of inflammatory mediators.

Defensin and chemokine expression patterns in the palatine tonsil: a model of their local interaction

Defensins and chemokines are an essential part of the immune response mechanisms in the head and neck mucosa. This work investigates their correlation and their expression pattern in tonsillar disease. Forty-four tonsil tissue samples were obtained from patients who underwent tonsillectomy between 1998 and 1999 for chronic tonsillitis with (n =9) and without (n =25) inflammatory infiltrates and hyperplasia of the tonsil (n =10). Defensin (hBD-1, hBD-2, HNP-1 and HNP-4) and chemokine (RANTES, eotaxin, eotaxin-2, MCP-3, MCP-4 and IL-8) mRNA expressions were analyzed by SQRT-PCR. HNP-4 and eotaxin-2 expressions were positively correlated (P <0.05) in the acute tonsillitis group. HBD-2 and MCP-3 expressions were positively correlated in the hyperplastic tonsils group. Within all groups together, HNP-4 and RANTES expressions were highly positively correlated (P <0.01), and HNP-1 and hBD-2 were positively correlated with IL-8 expressions. Immunohistochemistry demonstrated eotaxin-1 as well as IL-8 production to be predominantly located within the lymphoid follicles and submucosa. RANTES production was shown in the epithelial lining and perivascular tissue. The expression of hBD-1 and hBD-2 was limited to the epithelial lining. Our data support an association between the innate and acquired immune systems on the defensin-chemokine level. The finding of positively correlated hBD-2 and IL-8 expression is biologically relevant because of the proximity of hBD-2 (epithelium) and IL-8 (submucosa) release, as well as the synergistic support of the Th1 system. In addition, our data suggest RANTES as a first-line mediator of perivascular leukocyte recruitment.

Eotaxin-3 and interleukin-5 pleural fluid levels are associated with pleural fluid eosinophilia in post-coronary artery bypass grafting pleural effusions

OBJECTIVES

The primary aim of this study was to examine the association between pleural fluid (PF) eosinophilia, and the PF and serum levels of interleukin (IL)-5, eotaxin-2, eotaxin-3, and vascular cell adhesion molecule (VCAM)-1 in patients with post-coronary artery bypass grafting (CABG) pleural effusions.

DESIGN

A prospective observational study.

SETTING

A tertiary teaching hospital.

PATIENTS AND METHODS

Thirty-eight patients with post-CABG pleural effusions were recruited into the study. An effusion that contained at least 10% eosinophils was called "eosinophilic." The PF and serum levels of the cytokines and VCAM-1 were measured using an enzyme-linked immunosorbent assay.

RESULTS

(1) The number of PF eosinophils significantly correlated with the number of blood eosinophils. (2) PF IL-5 levels were significantly higher than the corresponding serum levels, and there was a significant correlation between the PF and serum IL-5 levels. PF IL-5 levels significantly correlated with the PF eosinophil count, and serum IL-5 levels significantly correlated with the number of blood eosinophils. (3) PF eotaxin-3 levels were significantly higher than serum levels, and PF eotaxin-3 levels significantly correlated with the PF eosinophil count. (4) PF VCAM-1 levels were significantly lower than the corresponding serum levels, and PF VCAM-1 levels were significantly higher in eosinophilic pleural effusions (EPEs) than in non-EPEs.

CONCLUSION

In patients with post-CABG pleural effusions, IL-5 and eotaxin-3 are produced preferentially in the pleural cavity, and they are strongly associated with PF eosinophilia.

Mechanisms of eosinophil cytokine release

Human eosinophils have been demonstrated to contain a multitude of cytokines and chemokines that exist pre-formed within these cells. This content of pre-formed cytokines, with diverse potential biologic activities, provides eosinophils with capabilities distinct from most other leukocytes. The localization of pre-formed cytokines within eosinophils is both within specific granules and associated with substantial numbers of morphologically distinct cytoplasmic vesicles. Stimulation for release of specific cytokines, such as IL-4, leads to a regulated signal transduction cascade, which is dependent on the formation of leukotriene C4 within eosinophils where it acts as an intracrine mediator. IL-4 release occurs selectively and is by means of vesicular transport. The capabilities of eosinophils not only to rapidly release pre-formed cytokines but also to differentially regulate which cytokines are released endow eosinophils with distinct abilities in innate and acquired immunity.

Pathogenesis of the eosinophilic pleural effusions

PURPOSE OF REVIEW

Eosinophilic pleural effusions (EPE) are defined as those that contain at least 10% eosinophils. EPEs account for 5 to 16% of exudative pleural effusions. However, their pathogenesis is poorly understood. The purpose of this review is to discuss the mechanisms that lead to eosinophilic pleural inflammation.

RECENT FINDINGS

Eosinophilic pleural effusions are caused by the presence of air or blood or both in the pleural space, infectious or other inflammatory diseases, malignancy, pulmonary emboli, asbestos exposure, and drug reactions. Differences in the clinical features suggest that a variety of mechanisms operate to induce eosinophilic pleural inflammation and pleural fluid accumulation. Human and animal studies indicate that interleukin (IL)-5 is an important common contributor of different pathogenetic pathways. The possible role of other cytokines, chemokines, and adhesion molecules in the development of EPE is under investigation.

SUMMARY

Understanding the pathogenesis of EPE will permit the development of novel therapies for the persistent, symptomatic, posttraumatic and idiopathic EPE. Anti-IL-5 treatment is an interesting option that requires further research.

Critical role for galectin-3 in airway inflammation and bronchial hyperresponsiveness in a murine model of asthma

Galectin-3 is a member of a beta-galactoside-binding animal lectin family. Previous in vitro studies have demonstrated that galectin-3 is involved in a number of activities; however, the roles of this lectin in physiological and pathological processes in vivo remain to be elucidated. Herein, we show, in a murine model of ovalbumin (OVA)-induced asthma that 1) peribronchial inflammatory cells expressed large amounts of galectin-3; 2) bronchoalveolar lavage fluid from OVA-challenged mice contained significantly higher levels of galectin-3 compared to control mice; and 3) macrophages in bronchoalveolar lavage fluid were the major cell type that contained galectin-3. We investigated the role of galectin-3 in the allergic airway response by comparing galectin-3-deficient (gal3(-/-)) mice and wild-type (gal3(+/+)) mice. OVA-sensitized gal3(-/-) mice developed fewer eosinophils and lower goblet cell metaplasia, after airway OVA challenge compared to similarly treated gal3(+/+) mice. In addition, the OVA-sensitized gal3(-/-) mice developed significantly less airway hyperresponsiveness after airway OVA challenge compared to gal3(+/+) mice. Finally, gal3(-/-) mice developed a lower Th2 response, but a higher Th1 response, suggesting that galectin-3 regulates the Th1/Th2 response. We conclude that galectin-3 may play an important role in the pathogenesis of asthma and inhibitors of this lectin may prove useful for treatment of this disease.

Role of p38 MAPK and NF-kB for chemokine release in coculture of human eosinophils and bronchial epithelial cells

Eosinophils are principal effector cells of inflammation in allergic asthma, characterized by their accumulation and infiltration at inflammatory sites mediated by the chemokine eotaxin and their interaction with adhesion molecules expressed on bronchial epithelial cells. We investigated the modulation of nuclear factor-kappaB (NF-kappaB) and the mitogen-activated protein kinase (MAPK) pathway on the in vitro release of chemokines including regulated upon activation normal T cell expressed and secreted (RANTES), monokine induced by interferon-gamma (MIG), monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-8, and interferon-inducible protein-10 (IP-10) upon the interaction of human bronchial epithelial BEAS-2B cells and eosinophils. Gene expression of chemokines was evaluated by RT-PCR and the induction amount of chemokines quantified by cytometric bead array. NF-kappaB and p38 MAPK activities were assessed by electrophoretic mobility shift assay and Western blot, respectively. The interaction of eosinophils and BEAS-2B cells was found to up-regulate the gene expression of the chemokines IL-8, MCP-1, MIG, RANTES and IP-10 expression in BEAS-2B cells, and to significantly elevate the release of the aforementioned chemokines except RANTES in a coculture of BEAS-2B cells and eosinophils. IkappaB-alpha phosphorylation inhibitor, BAY 11-7082, and p38 MAPK inhibitor, SB 203580 could decrease the release of IL-8, IP-10 and MCP-1 in the coculture. Together, the above results show that the induction of the release of chemokines in a coculture of epithelial cells and eosinophils are regulated by p38 MAPK and NF-kappaB activities of BEAS-2B cells, at least partly, through intercellular contact. Our findings therefore shed light on the future development of more effective agents for allergic and inflammatory diseases.

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.

Vdelta1+ gammadelta T cells producing CC chemokines may bridge a gap between neutrophils and macrophages in innate immunity during Escherichia coli infection in mice

An influx of neutrophils followed a short time later by an influx of macrophages to the infected site plays a key role in innate immunity against Escherichia coli infection. We found in this study that Vdelta1-/- mice exhibited impaired accumulation of peritoneal macrophages but not neutrophils and delayed bacterial clearance after i.p. inoculation with E. coli. Peritoneal gammadelta T cells from E. coli-infected wild-type mice produced CCL3/MIP-1alpha and CCL5/RANTES in response to gammadelta TCR triggering in vitro, whereas such production was not evident in gammadelta T cells from E. coli-infected Vdelta1-/- mice. Neutralization of CCL3/MIP-1alpha by a specific mAb in vivo significantly inhibited the accumulation of macrophages in the peritoneal cavity after E. coli infection, resulting in exacerbated bacterial growth in the peritoneal cavity. These results suggest that Vdelta1+ gammadelta T cells bridge a gap between neutrophils and macrophages in innate immunity during E. coli infection mediated by production of CC chemokines, enhancing macrophage trafficking to the site of infection.

Impact of Engagement of FcϵRI and CC Chemokine Receptor 1 on Mast Cell Activation and Motility

CC chemokines participate in the recruitment and activation of immune cells through CC chemokine receptors (CCRs). Here, we report that cross-talk between CCR1-mediated signaling pathway and FcepsilonRI-mediated signaling pathway affects degranulation positively but affects chemotaxis of mast cells adversely. Costimulation via FcepsilonRI engagement with IgE/antigen and CCR1 engagement with recombinant human CCL3 synergistically enhanced degranulation in rat basophilic leukemia-2H3 cells expressing human CCR1 (RBL-CCR1). Interestingly, FcepsilonRI engagement inhibited CCL3-mediated chemotaxis and membrane ruffling of RBL-CCR1 cells. Small GTP-binding proteins of the Rho family, Rac, Cdc42, and Rho control chemotaxis by mediating the reorganization of the actin cytoskeleton. Both a Rho inhibitor C3 exoenzyme and a Rho kinase (ROCK) inhibitor Y-27632 inhibited chemotaxis of RBL-CCR1 cells toward CCL3, indicating that activation of the Rho/ROCK signaling pathway is required for the CCL3-mediated chemotaxis of the cells. Costimulation with IgE/antigen and CCL3 enhanced Rac and Cdc42 activation but decreased ROCK activation in RBL-CCR1 cells compared with that in the cells stimulated with CCL3 alone. These results suggest that costimulation via FcepsilonRI and CCR1 engagements induced 1) inhibition of membrane ruffling, 2) decreased ROCK activation, and 3) reciprocal imbalance between Small GTP-binding proteins of the Rho family, which result in the inhibition of chemotaxis of RBL-CCR1 cells. The cross-talk between FcepsilonRI-mediated signaling pathway and CCR-mediated signaling pathway would induce optimal activation and arrested chemotaxis of mast cells, thus contributing to allergic inflammation.

Monocyte chemoattractant protein-1 production by human detrusor smooth muscle cells

PURPOSE

Most recently attention has turned to the secretory properties of smooth muscle cells. Monocyte chemoattractant protein-1 (MCP-1) is a potent chemokine that causes mast cells recruitment and provokes mast cells activation in vitro. We investigated whether MCP-1 is produced by human detrusor smooth muscle cells (HDSMCs) cultured under inflammatory conditions.

MATERIALS AND METHODS

Using an explantation technique HDSMCs were isolated and short-term cultured. HDSMCs were incubated at 37C for 24 hours with the proinflammatory mediators interleukin-1 beta (IL-1 beta), tumor necrosis factor (TNF-alpha), lipopolysaccharide, histamine, leukotriene D4 and prostaglandin E2. The level of MCP-1 in cell supernatants were measured by enzyme linked immunoassay.

RESULTS

There was basal secretion of MCP-1 in unstimulated cultures. Following 24-hour incubation with IL-1 beta or TNF-alpha (1 pg/ml to 100 ng/ml) the level of MCP-1 increased in a dose dependent manner. IL-1 beta was more potent at inducing MCP-1 release in 8 of 10 experiments. Lipopolysaccharide (10 microg/ml), histamine (100 microM), leukotriene D4 (50 nM), prostaglandin E2 (1 microM) and KCl (30 to 100 mM) failed to induce MCP-1 production. When IL-1 beta (10 ng/ml) and TNF-alpha (10 ng/ml) were given in combination, a highly synergistic effect on MCP-1 production was observed.

CONCLUSIONS

To our knowledge this study shows for the first time that human detrusor smooth muscle cells cultivated under inflammatory conditions produce significant amounts of MCP-1. In addition to contractile function, HDSMCs have synthesis and secretory potential with the release of MCP-1. Thus, MCP-1 may contribute to the local inflammatory process by producing proinflammatory mediators. The release of cytokines and chemokines by human detrusor muscle even in small amounts may have important functional consequences.

Eotaxin-2 and IL-5 cooperate in the lung to regulate IL-13 production and airway eosinophilia and hyperreactivity

BACKGROUND

Eotaxin-2 is a member of the eotaxin subfamily of CC chemokines that display eosinophil-specific, chemotactic properties and has been associated with allergic disorders. However, the contribution of eotaxin-2 to the development of defined pathogenic features of allergic disease remains to be defined.

OBJECTIVE

We sought to determine whether eotaxin-2 was a cofactor with IL-5 for the regulation of pulmonary eosinophilia and to identify the combined role of these molecules in the induction of phenotypic characteristics of allergic lung disease.

METHODS

We instilled recombinant eotaxin-2 into the airways of wild-type mice that had been treated systemically with IL-5 or into IL-5-transgenic mice and characterized pulmonary eosinophil numbers, IL-13 production, and airway hyperreactivity (AHR) to methacholine. Mice deficient in the IL-4 receptor alpha-chain, IL-13, and signal transducers and activators of transcription 6 or mice treated with anti-CCR3 monoclonal antibody were also used.

RESULTS

Eotaxin-2 and IL-5 cooperatively promoted eosinophil accumulation, IL-13 production, and AHR to methacholine. Neither eotaxin-2 nor IL-5 alone induced these features of allergic disease. IL-13 production was critically dependent on eotaxin-2- and IL-5-regulated eosinophilia, which predisposed to the development of AHR. AHR was dependent on IL-13 and signaling through the IL-4R alpha-chain and signal transducers and activators of transcription 6 pathways and the presence of eosinophils in the lung.

CONCLUSION

These investigations demonstrate important cooperativity between eotaxin-2, IL-5, and IL-13 signaling systems and eosinophils for the development of hallmark features of allergic disease of the lung.

11-Dehydro-thromboxane B2, a stable thromboxane metabolite, is a full agonist of chemoattractant receptor-homologous molecule expressed on TH2 cells (CRTH2) in human eosinophils and basophils

Thromboxane (TX) A(2), a cyclooxygenase-derived mediator involved in allergic responses, is rapidly converted in vivo to a stable metabolite, 11-dehydro-TXB(2), which is considered to be biologically inactive. In this study, we found that 11-dehydro-TXB(2), but not the TXA(2) analogue U46,619 or TXB(2), activated eosinophils and basophils, as assayed by flow cytometric shape change. 11-Dehydro-TXB(2) was also chemotactic for eosinophils but did not induce, nor inhibit, platelet aggregation. Chemoattractant receptor-homologous molecule expressed on TH2 cells (CRTH2) is an important chemoattractant receptor expressed by eosinophils, basophils, and TH2 lymphocytes, and prostaglandin (PG)D(2) has been shown to be its principal ligand. 11-Dehydro-TXB(2) induced calcium flux mainly from intracellular stores in eosinophils, and this response was desensitized after stimulation with PGD(2) but not other eosinophil chemoattractants. Shape change responses of eosinophils and basophils to 11-dehydro-TXB(2) were inhibited by the thromboxane (TP)/CRTH2 receptor antagonist ramatroban, but not the selective TP antagonist SQ29,548, and were insensitive to pertussis toxin. The phospholipase C inhibitor U73,122 attenuated both 11-dehydro-TXB(2)- and PGD(2)-induced shape change. 11-Dehydro-TXB(2) also induced the chemotaxis of BaF/3 cells transfected with hCRTH2 but not naive BaF/3 cells. At a threshold concentration, 11-dehydro-TXB(2) had no antagonistic effect on CRTH2-mediated responses as induced by PGD2. These data show that 11-dehydro-TXB(2) is a full agonist of the CRTH2 receptor and hence might cause CRTH2 activation in cellular contexts where PGD-synthase is not present. Given its production in the allergic lung, antagonism of the 11-dehydro-TXB(2)/CRTH2axis may be of therapeutic relevance.

Preferential signaling and induction of allergy-promoting lymphokines upon weak stimulation of the high affinity IgE receptor on mast cells

Mast cell degranulation and de novo cytokine production is a consequence of antigen-aggregation of the immunoglobulin E (IgE)-occupied high affinity receptor for IgE (Fc epsilon RI). Herein, we report that lymphokines that promote allergic inflammation, like MCP-1, were potently induced at low antigen (Ag) concentrations or at low receptor occupancy with IgE whereas some that down-regulate this response, like interleukin (IL)-10, required high receptor occupancy. Weak stimulation of mast cells caused minimal degranulation whereas a half-maximal secretory response was observed for chemokines and, with the exception of TNF-alpha, a weaker cytokine secretory response was observed. The medium from weakly stimulated mast cells elicited a monocyte/macrophage chemotactic response similar to that observed at high receptor occupancy. Weak stimulation also favored the phosphorylation of Gab2 and p38MAPK, while LAT and ERK2 phosphorylation was induced by a stronger stimulus. Gab2-deficient mast cells were severely impaired in chemokine mRNA induction whereas LAT-deficient mast cells showed a more pronounced defect in cytokines. These findings demonstrate that perturbation of small numbers of IgE receptors on mast cells favors certain signals that contribute to a lymphokine response that can mediate allergic inflammation.

CC chemokines mediate leukocyte trafficking into the central nervous system during murine neurocysticercosis: role of gamma delta T cells in amplification of the host immune response

According to a previous report, the degree of the host immune response highly correlates with severity of the disease in the murine model for neurocysticercosis. In wild-type mice, Mesocestoides corti infection induced a rapid and extensive accumulation of gamma delta T cells and macrophages in the brain. NK cells, dendritic cells, alpha beta T cells, and B cells were also recruited to the brain but at lower levels. In contrast, gamma delta T-cell-deficient mice exhibited decreased cellular infiltration and reduced central nervous system (CNS) pathology. To understand the mechanisms of leukocyte recruitment into the CNS, chemokine expression was analyzed in infected brains in the present study. MCP-1 (CCL2), MIP-1 alpha (CCL3), and MIP-1 beta (CCL4) were up-regulated within 2 days after M. corti infection. Protein expression of RANTES (CCL5), eotaxin (CCL11), and MIP-2 was detected later, at 1 week postinfection. Correlating with the decreased cellular infiltration, delta chain T-cell receptor-deficient (TCR delta(-/-)) mice exhibited substantially reduced levels of most of the chemokines analyzed (with the exception of eotaxin). The results suggest that gamma delta T cells play an important role in the CNS immune response by producing chemokines such as MCP-1 and MIP-1 alpha, enhancing leukocyte trafficking into the brain during murine neurocysticercosis.

Delta 12-prostaglandin J2, a plasma metabolite of prostaglandin D2, causes eosinophil mobilization from the bone marrow and primes eosinophils for chemotaxis

PGD(2), a major mast cell mediator, is a potent eosinophil chemoattractant and is thought to be involved in eosinophil recruitment to sites of allergic inflammation. In plasma, PGD(2) is rapidly transformed into its major metabolite delta(12)-PGJ(2), the effect of which on eosinophil migration has not yet been characterized. In this study we found that delta(12)-PGJ(2) was a highly effective chemoattractant and inducer of respiratory burst in human eosinophils, with the same efficacy as PGD(2), PGJ(2), or 15-deoxy-delta(12,14)-PGJ(2). Moreover, pretreatment of eosinophils with delta(12)-PGJ(2) markedly enhanced the chemotactic response to eotaxin, and in this respect delta(12)-PGJ(2) was more effective than PGD(2). delta(12)-PGJ(2)-induced facilitation of eosinophil migration toward eotaxin was not altered by specific inhibitors of intracellular signaling pathways relevant to the chemotactic response, phosphatidylinositol 3-kinase (LY-294002), mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (U-0126), or p38 mitogen-activated protein kinase (SB-202190). Desensitization studies using calcium flux suggested that delta(12)-PGJ(2) signaled through the same receptor, CRTH2, as PGD(2). Finally, delta(12)-PGJ(2) was able to mobilize mature eosinophils from the bone marrow of the guinea pig isolated perfused hind limb. Given that delta(12)-PGJ(2) is present in the systemic circulation at relevant levels, a role for this PGD(2) metabolite in eosinophil release from the bone marrow and in driving eosinophil recruitment to sites of inflammation appears conceivable.

A causative relationship exists between eosinophils and the development of allergic pulmonary pathologies in the mouse

Asthma and mouse models of allergic respiratory inflammation are invariably associated with a pulmonary eosinophilia; however, this association has remained correlative. In this report, a causative relationship between eosinophils and allergen-provoked pathologies was established using eosinophil adoptive transfer. Eosinophils were transferred directly into the lungs of either naive or OVA-treated IL-5(-/-) mice. This strategy resulted in a pulmonary eosinophilia equivalent to that observed in OVA-treated wild-type animals. A concomitant consequence of this eosinophil transfer was an increase in Th2 bronchoalveolar lavage cytokine levels and the restoration of intracellular epithelial mucus in OVA-treated IL-5(-/-) mice equivalent to OVA-treated wild-type levels. Moreover, the transfer also resulted in the development of airway hyperresponsiveness. These pulmonary changes did not occur when eosinophils were transferred into naive IL-5(-/-) mice, eliminating nonspecific consequences of the eosinophil transfer as a possible explanation. Significantly, administration of OVA-treated IL-5(-/-) mice with GK1.5 (anti-CD4) Abs abolished the increases in mucus accumulation and airway hyperresponsiveness following adoptive transfer of eosinophils. Thus, CD4(+) T cell-mediated inflammatory signals as well as signals derived from eosinophils are each necessary, yet alone insufficient, for the development of allergic pulmonary pathology. These data support an expanded view of T cell and eosinophil activities and suggest that eosinophil effector functions impinge directly on lung function.

Altered intracellular expression of the chemokines MIP-1alpha, MIP-1beta and IL-8 by peripheral blood CD4+ and CD8+ T cells in mild allergic asthma

BACKGROUND

The ability of chemokines to regulate Th1 and Th2 responses suggests a role in the pathogenesis of atopic disorders such as allergic asthma where Th2 response dominance has been observed. Although the impact of allergic asthma on local chemokine production in the lung has been the subject of investigation, little is know about the influence of disease progression on peripheral chemokine production. We now report use of whole blood culture and flow cytometry to assess the influence of mild allergic asthma on peripheral T-cell chemokine expression.

METHODS

Study participants included patients with mild allergic asthma (n = 7) and nonasthmatic controls (n = 7). Following in vitro stimulation of peripheral venous blood with phorbol 12-myristate acetate (PMA) and ionomycin, flow cytometry was used to estimate the percentage of CD4+ and CD8+ T cells producing a number of chemokines, including macrophage inflammatory proteins MIP-1alpha and MIP-1beta, RANTES (regulated on activation, T-cell expressed and secreted), monocytic chemotactic protein-1 (MCP)-1, and interleukin (IL)-8, or the cytokines interferon (IFN)-gamma and IL-4. Serum levels of MIP-1alpha, MIP-1beta, RANTES, MCP-1, IL-8, IFN-gamma and IL-4 were also assessed by quantitative ELISA.

RESULTS

Intracellular expression of MIP-1beta by CD4+ and CD8+ T cells from allergic asthmatics was significantly reduced in comparison to that observed for nonasthmatics (median = 2.29% (1.75-3.50) vs 4.57% (3.38-6.64), P = 0.05; 14.20% (13.18-17.88) vs 44.10% (30.38-48.70), P = 0.01). Similarly, intracellular expression of MIP-1alpha by CD8+ T cells from allergic asthmatics was also significantly lower (3.67% (1.17-5.42) vs 17.10% (4.97-20.43), P = 0.05). Conversely, IL-8 expression by both CD4+ and CD8+ T cells from allergic asthmatics demonstrated significant enhancement (9.93% (7.77-11.28) vs 4.14% (3.61-7.11), P = 0.05; 8.40% (6.97-10.04) vs 4.98% (3.37-6.08), P = 0.05). Examination of intracellular IFN-gamma and IL-4 revealed no significant difference in the expression of either cytokine by CD4+ T-cells from allergic asthmatics and nonasthmatics. In contrast, expression of IFN-gamma was significantly reduced in CD8+ T-cells from allergic asthmatics (24.60% (21.08-32.50) vs 48.40% (41.50-55.28), P = 0.01).

CONCLUSIONS

The occurrence in mild allergic asthma of peripheral T-cell chemokine expression suggestive of a diminished Th1 response, coinciding with marginal change in cytokine profiles indicative of a Th2 response bias, confirms the importance of chemokine involvement in the etiology of allergic asthma. The ability to use whole blood culture to estimate chemokine expression in T cell subsets may ultimately provide a practical means to evaluate disease status and to monitor early intervention therapies which target chemokines.

A soluble chemokine-binding protein from vaccinia virus reduces virus virulence and the inflammatory response to infection

Many poxviruses express a secreted protein that binds CC chemokines with high affinity and has been called viral CC chemokine inhibitor (vCCI). This protein is unrelated to any known cellular protein, yet can compete with host cellular CC chemokine receptors to modulate host inflammatory and immune responses. Although several strains of vaccinia virus (VV) express a vCCI, the best characterized VV strains Western Reserve and Copenhagen do not. In this study, we have expressed the vCCI from VV strain Lister in a recombinant Western Reserve virus (v Delta B8R-35K) and characterized its binding properties in vitro and its effect on virulence in vivo relative to wild-type virus (v Delta B8R) or a revertant virus (v Delta B8R-R) where Lister 35-kDa had been removed. Cells infected with v Delta B8R-35K secreted a 35-kDa protein that bound the CC chemokine macrophage-inflammatory protein 1 alpha. Expression of vCCI attenuated the virus in a murine intranasal model, characterized by reduced mortality and weight loss, decreased virus replication and spread, and a reduced recruitment of inflammatory cells into the lungs of VV-infected mice. The CC chemokines macrophage-inflammatory protein 1 alpha, eotaxin, and macrophage chemotactic protein 1 were detected in bronchoalveolar lavage fluids from v Delta B8R-infected mice; however, bronchoalveolar lavage fluids from v Delta B8R-35K-infected mice had lower levels of chemokines and a reduced chemotactic activity for murine leukocytes in vitro. These observations suggest that vCCI plays an important role in regulating leukocyte trafficking to the lungs during VV infection by binding to CC chemokines and blocking their chemotactic activities.

Eosinophil recruitment in type-2 hypersensitivity pulmonary granulomas: source and contribution of monocyte chemotactic protein-3 (CCL7)

Monocyte chemotactic protein-3 (MCP-3/CCL7) has potent eosinophil chemoattractant properties. The present study determined its relative contribution to the formation of Th2 cytokine-mediated (type-2) eosinophil-rich interstitial lung granulomas induced by antigens of Schistosoma mansoni eggs. Both MCP-3 transcripts and protein levels were more strongly expressed in lungs with type-2 than with type-1 (mycobacterial antigen-elicited Th1-mediated) granulomas. In vivo treatment with neutralizing antibodies demonstrated that MCP-3 abrogated eosinophil accumulation in type-2 lesions by 40 to 50%. Immunohistochemical staining revealed that MCP-3 localized to vessels in or near granulomas suggesting that endothelial cells were an important in situ source of MCP-3. Maximal MCP-3 transcript expression was abrogated by anti-interleukin-4 treatment. Furthermore, cultured mouse lung endothelial cells displayed augmented MCP-3 production in response to interleukin-4. Together, these results suggest that MCP-3 contributes to a significant component of eosinophil recruitment in the type-2 interstitial granuloma formation and Th2 cytokines promote its production.

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.

Selective cyclooxygenase-1 and -2 inhibitors each increase allergic inflammation and airway hyperresponsiveness in mice

Nonselective cyclooxygenase (COX) inhibition during allergic sensitization with ovalbumin in a murine model leads to an increase in the Type 2 cytokines interleukin-5 (IL-5) and IL-13; however, the effect of selective COX-1 and COX-2 inhibitors on these cytokines is unknown. We found that COX-1 protein was constitutively expressed in lung tissue. Expression of COX-1 protein did not increase with ovalbumin sensitization, but expression of COX-2 protein did. Ovalbumin-sensitized mice treated with either selective COX-1 inhibitor SC58560 (OVA-COX-1 inhibitor) or selective COX-2 inhibitor SC58236 (OVA-COX-2 inhibitor) had significantly greater airway hyperresponsiveness (p < 0.05) and higher levels of IL-13 (p < 0.05) in lung supernatants than did untreated mice that were ovalbumin sensitized (OVA). Lung mRNA levels for the chemokine receptors CCR1 through CCR5 (expressed on eosinophils, basophils, lymphocytes, and dendritic cells) were increased in the OVA-COX-2 inhibitor and OVA-indomethacin groups. We conclude that in the BALB/c mouse, COX inhibition with either a COX-1 or COX-2 inhibitor during allergen sensitization augments production of IL-13 and increases airway hyperresponsiveness.

Eotaxin expression by epithelial cells and plasma cells in chronic asthma

Chemoattractants such as eotaxin are believed to play an important role in the recruitment of eosinophils into the airways in asthma. We investigated expression of eotaxin in the airway wall in a model of chronic human asthma, in which systemically sensitized mice were exposed to low mass concentrations of aerosolized antigen for 6 weeks. In these animals, the number of intraepithelial eosinophils in the airways was significantly increased 3 hours after exposure and declined by 24 hours. In parallel, immunoreactivity for eotaxin was strikingly up-regulated in airway epithelial cells and in inflammatory cells in the lamina propria. The latter were identified as plasma cells by double immunofluorescent labeling. Increased expression of eotaxin by epithelial cells and plasma cells was also demonstrated in a case of fatal human asthma. In contrast, sensitized mice that received a single exposure to a high mass concentration of aerosolized antigen exhibited delayed eosinophil recruitment, which did not correlate with eotaxin expression. Furthermore, in sensitized chronically exposed interleukin-13-deficient mice there was virtually no recruitment of eosinophils into the airways, although eotaxin expression was greater than or equal to that in wild-type mice. These results indicate that there are striking differences between acute and chronic exposure models in the time course of eotaxin expression and eosinophil recruitment. Although high eotaxin levels alone are not sufficient to cause recruitment of eosinophils into the airways, recurrent exposure may generate or up-regulate additional signals required for eosinophil chemotaxis.

Gq signaling is required for allergen-induced pulmonary eosinophilia

The complexity and magnitude of interactions leading to the selective infiltration of eosinophils in response to inhaled allergens are formidable obstacles to a larger understanding of the pulmonary pathology associated with allergic asthma. This study uses knockout mice to demonstrate a novel function for the heterotrimeric G protein, G(q), in the regulation of pulmonary eosinophil recruitment. In the absence of G(q) signaling, eosinophils failed to accumulate in the lungs following allergen challenge. These studies demonstrate that the inhibition of eosinophil accumulation in the airways is attributed to the failure of hemopoietically derived cells to elaborate GM-CSF in the airways. The data suggest that activation of a G(q)-coupled receptor(s) on resident leukocytes in the lung elicits expression of GM-CSF, which, in turn, is required for allergen-induced pulmonary eosinophilia, identifying a novel pathway of eosinophil-associated effector functions leading to pulmonary pathology in diseases such as asthma.

Heterotrimeric G protein signaling: role in asthma and allergic inflammation

Asthma and rhinitis are pathophysiologic conditions associated with a prototypical allergic response to inhaled allergens consisting of both neuromechanical and inflammatory components. Heptahelical receptors that bind guanosine triphosphate-binding proteins (G proteins), referred to as G protein-coupled receptors (GPCRs), have been intimately linked with asthma and allergic inflammation for many years. G protein signaling mediates responses throughout the immune, nervous, and muscular systems that might contribute to the pathogenesis of allergic processes and asthma. For example, GPCR agonists or antagonists are used as therapies for asthma either by promoting airway smooth muscle relaxation (beta2 adrenergic receptor agonists) or by inhibiting inflammation in the nasal mucosa and airways (cysteinyl leukotriene receptor antagonists). The focus of this review is to explore how downstream signaling cascades elicited by GPCR activation contribute to the allergic phenotype and the mechanism by which pharmaceuticals alter signaling to generate a therapeutic effect. We also discuss physiologic modulators of G protein signaling, such as regulator of G protein signaling proteins and G protein receptor kinases, inasmuch as they represent potential new therapeutic targets in the treatment of atopy and other inflammatory conditions.

IL-13-induced chemokine responses in the lung: role of CCR2 in the pathogenesis of IL-13-induced inflammation and remodeling

IL-13 stimulates inflammatory and remodeling responses and contributes to the pathogenesis of human airways disorders. To further understand the cellular and molecular events that mediate these responses, we characterized the effects of IL-13 on monocyte chemotactic proteins (MCPs) and compared the tissue effects of transgenic IL-13 in mice with wild-type (+/+) and null (-/-) CCR2 loci. Transgenic IL-13 was a potent stimulator of MCP-1, -2, -3, and -5. This stimulation was not specific for MCPs because macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta, MIP-2, MIP-3alpha, thymus- and activation-regulated chemokine, thymus-expressed chemokine, eotaxin, eotaxin 2, macrophage-derived chemokines, and C10 were also induced. The ability of IL-13 to increase lung size, alveolar size, and lung compliance, to stimulate pulmonary inflammation, hyaluronic acid accumulation, and tissue fibrosis, and to cause respiratory failure and death were markedly decreased, whereas mucus metaplasia was not altered in CCR2(-/-) mice. CCR2 deficiency did not decrease the basal or IL-13-stimulated expression of target matrix metalloproteinases or cathepsins but did increase the levels of mRNA encoding alpha1-antitrypsin, tissue inhibitor of metalloproteinase-1, -2, and -4, and secretory leukocyte proteinase inhibitor. In addition, the levels of bioactive and total TGF-beta(1) were decreased in lavage fluids from IL-13 transgenic mice with -/- CCR2 loci. These studies demonstrate that IL-13 is a potent stimulator of MCPs and other CC chemokines and document the importance of MCP-CCR2 signaling in the pathogenesis of the IL-13-induced pulmonary phenotype.

Ectopic expression of IL-5 identifies an additional CD4(+) T cell mechanism of airway eosinophil recruitment

CD4(+) T cells have a critical role in the development of allergic pulmonary inflammation, including the recruitment of eosinophils to the airway lumen and interstitium. The expression of interleukin (IL)-5 by CD4(+) cells has, in particular, often been lionized as the central link between allergic inflammation and the concomitant expansion or recruitment of eosinophils. The mechanism(s) by which CD4(+) T cells mediates eosinophil recruitment was assessed with gene knockout mice deficient for T cells or T cell subtypes and a unique IL-5 transgenic mouse (line NJ.1726) that constitutively overexpresses this cytokine in the lung epithelium. Pulmonary IL-5 expression is significantly attenuated in T cell- and CD4(+) but not CD8(+) cell-deficient animals, suggesting an obvious explanation for the lack of eosinophils in the lungs of T cell-deficient and CD4(-/-) mice. However, although the constitutive expression of IL-5 in the lung epithelium of NJ.1726 mice elicited an eosinophilia in the airway lumen of both naive and ovalbumin-treated mice, in the absence of CD4(+) cells, allergen-mediated eosinophil recruitment to the bronchoalveolar lavage fluid was abolished. Moreover, intranasal instillation of the potent eosinophil-specific chemokine eotaxin-2 was incapable of eliciting eosinophil recruitment in naive and ovalbumin-treated NJ.1726 CD4(-/-) mice, suggesting that eosinophil trafficking during allergic inflammatory responses is a consequence of a CD4(+) cell-mediated event(s) in addition to IL-5 expression and the establishment of a pulmonary chemokine gradient.