Chemokines in asthma: cooperative interaction between chemokines and IL-13

n-Nonanoyl-CC chemokine ligand 14, a potent CC chemokine ligand 14 analogue that prevents the recruitment of eosinophils in allergic airway inflammation

CCR3 is responsible for tissue infiltration of eosinophils, basophils, mast cells, and Th2 cells, particularly in allergic diseases. In this context, CCR3 has emerged as a target for the treatment of allergic asthma. It is well known that the N-terminal domain of chemokines is crucial for receptor binding and, in particular, its activation. Based on this background, we investigated a number of N-terminally truncated or modified peptides derived from the chemokine CCL14/hemofiltrate CC chemokine-1 for their ability to modulate the activity of CCR3. Among 10 derivatives tested, n-nonanoyl (NNY)-CCL14[10-74] (NNY-CCL14) was the most potent at evoking the release of reactive oxygen species and inducing chemotaxis of human eosinophils. In contrast, NNY-CCL14 has inactivating properties on human eosinophils, because it is able to induce internalization of CCR3 and to desensitize CCR3-mediated intracellular calcium release and chemotaxis. In contrast to naturally occurring CCL11, NNY-CCL14 is resistant to degradation by CD26/dipeptidyl peptidase IV. Because inhibition of chemokine receptors through internalization is a reasonable therapeutic strategy being pursued for HIV infection, we tested a potential inhibitory effect of NNY-CCL14 in two murine models of allergic airway inflammation. In both OVA- and Aspergillus fumigatus-sensitized mice, i.v. treatment with NNY-CCL14 resulted in a significant reduction of eosinophils in the airways. Moreover, airway hyper-responsiveness was shown to be reduced by NNY-CCL14 in the OVA model. It therefore appears that an i.v. administered agonist internalizing and thereby inhibiting CCR3, such as NNY-CCL14, has the potential to alleviate CCR3-mediated diseases.

Immunopathogenesis of experimental ulcerative colitis is mediated by eosinophil peroxidase

The precise role that individual inflammatory cells and mediators play in the development of gastrointestinal (GI) dysfunction and extraintestinal clinical manifestations of ulcerative colitis (UC) is unknown. In this study, we have used a mouse model of UC to establish a central role for eotaxin and, in turn, eosinophils in the development of the immunopathogenesis of this disease. In this model the administration of dextran sodium sulfate (DSS) induces a prominent colonic eosinophilic inflammation and GI dysfunction (diarrhea with blood and shortening of the colon) that resembles UC in patients. GI dysfunction was associated with evidence of eosinophilic cytolytic degranulation and the release of eosinophil peroxidase (EPO) into the colon lumen. By using IL-5 or eotaxin-deficient mice, we show an important role for eotaxin in eosinophil recruitment into the colon during experimental UC. Furthermore, using EPO-deficient mice and an EPO inhibitor resorcinol we demonstrate that eosinophil-derived peroxidase is critical in the development of GI dysfunction in experimental UC. These findings provide direct evidence of a central role for eosinophils and EPO in GI dysfunction and potentially the immunopathogenesis of UC.

Increased macrophage-derived chemokine in exhaled breath condensate and plasma from children with asthma

BACKGROUND

Type 2 helper T lymphocyte-specific chemokines including macrophage-derived chemokine (MDC), thymus and activation-regulated chemokine (TARC) and eotaxin are important mediators for allergic airway inflammation.

OBJECTIVE

We investigated whether these chemokines can be detected in exhaled breath condensate (EBC) and their relation to childhood asthma.

METHODS

Asthmatics recruited from paediatric clinics of a university teaching hospital were classified into intermittent asthma (IA) and persistent asthma (PA) according to Global Initiative for Asthma guidelines. EBC was collected by a disposable collection kit, whereas fractional exhaled nitric oxide (FENO) was measured by a chemiluminescence analyser. Concentrations of MDC, TARC and eotaxin in both EBC and plasma were measured using sandwich enzyme immunoassay. The intra-subject reproducibility of exhaled chemokine measurements was determined by co-efficients of variation (CV).

RESULTS

Forty-eight patients with PA, 36 children with IA and 18 controls were recruited. MDC and eotaxin were present in EBC from nearly all subjects, whereas TARC could be measured in EBC from 33 (32%) subjects only. The median MDC concentration in EBC was higher in PA (117 pg/mL) as compared with IA (106 pg/mL) and controls (105 pg/mL; P=0.003 for both). The median plasma MDC concentration in PA (648 pg/mL) was also higher than that in IA (520 pg/mL; P=0.002) and controls (490 pg/mL; P=0.008). The median plasma TARC concentration was also increased in PA as compared with IA (72 pg/mL vs. 35 pg/mL; P=0.004). MDC concentrations in EBC were lower in patients with PA who received high-dose inhaled corticosteroid (P=0.005). FENO was significantly higher in asthmatics than controls (P<0.0001), but it was not associated with chemokines in EBC or plasma. The mean (range) CV for measuring MDC, TARC and eotaxin in EBC (n=6) were 5.5 (2.0-7.2%), 8.8 (3.6-14.4%) and 5.2 (2.8-7.9%), respectively.

CONCLUSIONS

Our results suggest that MDC in EBC and MDC and TARC in plasma are increased in children with PA as compared with IA or control. MDC concentrations in EBC are suppressed in patients on high-dose inhaled corticosteroid treatment.

Threonine for alanine substitution in the eotaxin (CCL11) gene and the risk of incident myocardial infarction

Recent studies suggest that the chemokine eotaxin may participate in atherosclerosis. Threonine (T) for alanine (A) substitution at amino acid 23 in the eotaxin gene (CCL11) has been associated with risk of developing allergic-inflammatory disorders. However, no genetic-epidemiological data are available on the risk of cardiovascular disease associated with this polymorphism. Using DNA samples collected at baseline in a prospective cohort of 14,916 initially healthy American men, we evaluated the A23T polymorphism among 523 individuals who subsequently developed myocardial infarction (MI) and among 2092 individuals who remained free of reported cardiovascular disease over a mean follow-up period of 13.2 years. The T23 allele was significantly associated with risk of myocardial infarction (odds ratio (OR) in an age and smoking adjusted recessive model of inheritance, 1.86; 95% confidence interval (CI), 1.15-3.01; P = 0.012). This risk effect remained statistically significant in analyses further controlling for body mass index, history of hypertension, the presence of diabetes, and randomized treatment assignment (OR, 1.95; 95% CI, 1.19-3.18; P = 0.008). In this cohort, a T for A substitution at amino acid 23 in the eotaxin gene is associated with increased risk for incident myocardial infarction. If confirmed in other cohorts, these data support the emerging hypothesis that eotaxin participates in atherosclerosis.

A model of chronic IgE-mediated food allergy in ovalbumin-sensitized mice

Food allergy is most frequently the result of IgE-mediated hypersensitivity reactions. Here, we describe a chronic model in which some of the intestinal and systemic consequences of continuous egg white solution ingestion by ovalbumin-sensitized eight-week-old BALB/c mice, 6 animals per group, of both sexes, were investigated. There was a 20% loss of body weight that began one week after antigen exposure and persisted throughout the experiment (3 weeks). The sensitization procedure induced the production of anti-ovalbumin IgG1 and IgE, which were enhanced by oral antigen exposure (129% for IgG1 and 164% for IgE, compared to sensitization values). Intestinal changes were determined by jejunum edema at 6 h (45% Evans blue extravasation) and by a significant eosinophil infiltration with a peak at 48 h. By day 21 of continuous antigen exposure, histological findings were mild, with mast cell hyperplasia (100%) and increased mucus production (483%). Altogether, our data clearly demonstrate that, although immune stimulation was persistently occurring in response to continuous oral antigen exposure, regulatory mechanisms were occurring in the intestinal mucosa, preventing overt pathology. The experimental model described here reproduces the clinical and pathological changes of mild chronic food allergy and may be useful for mechanistic studies of this common clinical condition.

Chemokines in eosinophil-associated gastrointestinal disorders

Eosinophil-associated gastrointestinal disorders (EGDs) are characterized by a pronounced cellular inflammation. Recent clinical and experimental investigations have implicated a family of molecules known as chemokines in the regulation of leukocyte recruitment in these diseases. The underlying cellular and molecular mechanisms involved in chemokine-mediated cellular infiltration are largely unknown. In this review, we describe the role of CD4+ T cells and eosinophils in the clinical manifestations of EGDs and discuss the current understanding of the role of chemokines in the recruitment of these cells in the expression of diseases.

Presence of IgE antibodies to bacterial superantigens and increased IL-13-producing T cells in myelitic patients with atopic diathesis

BACKGROUND

Superantigens are considered to exacerbate autoimmune inflammation through the expansion of autoreactive T cells; however, the immune response to bacterial superantigens has not been extensively studied in any type of myelitis. We recently reported the occurrence of a distinct type of myelitis in patients with atopic diathesis, which in a recent nationwide survey was reported to be widespread in Japan. The aim of this study was to investigate the presence of IgE antibodies to bacterial superantigens and the proportion of IL-13- or IL-5-producing CD4+ or CD8+ T cells in patients with myelitis and atopic diathesis.

METHODS

Twenty-four myelitic patients with and 12 myelitic patients without hyperIgEemia, 28 patients with multiple sclerosis (MS) and 34 healthy controls were enrolled in this study. IgE antibodies to staphylococcal enterotoxins A (SEA) and B (SEB) in sera were measured using a liquid-phase enzyme immunoassay, and the intracellular production of IL-5 and IL-13 in peripheral blood CD4+ and CD8+ T cells was measured by flow cytometry.

RESULTS

The myelitic patients with hyperIgEemia showed significantly higher positive rates of serum SEA/SEB-specific IgE antibodies (41.7 and 62.5%, respectively) than the healthy controls (5.9 and 8.8%), patients with MS (0 and 21.4%) and those with normoIgEemic myelitis (0 and 0%). Moreover, IL-13-producing CD4+ T cells and CD8+ T cells increased significantly in the myelitic patients with hyperIgEemia compared to the controls, while IL-5-producing CD4+ or CD8+ T cells did not.

CONCLUSIONS

The IgE response to staphylococcal superantigens is heightened in myelitic patients with atopic diathesis, which might contribute to increases in IL-13-producing T cells and thus the development of myelitis.

Negative regulation of eosinophil recruitment to the lung by the chemokine monokine induced by IFN-gamma (Mig, CXCL9)

Experimental analysis of allergic airway inflammation (AAI) in animals and humans is associated with coordinate gene induction. Using DNA microarray analysis, we have identified a large panel of AAI signature genes. Unexpectedly, the allergen-challenged lung (a T helper 2 microenvironment) was found to be associated with the expression of T helper 1-associated CXCR3 ligands, monokine induced by IFN-gamma (Mig), and IFN-gamma-inducible protein of 10 kDa (IP-10). Here we report that Mig functions as a negative regulator of murine eosinophils. Whereas Mig was not able to induce chemotaxis of eosinophils, pretreatment with Mig induced a dose-dependent inhibition of chemoattractant-induced eosinophil transmigration in vitro. Moreover, i.v. administration of low doses of Mig ( approximately 10-30 microg/kg) induced strong and specific dose-dependent inhibition of chemokine-, IL-13-, and allergen-induced eosinophil recruitment and, conversely, neutralization of Mig before allergen challenge increased airway eosinophilia. Importantly, Mig also inhibited a CCR3-mediated functional response in eosinophils. These results indicate that the ultimate distribution and function of inflammatory cells within the allergic lung is dictated by a balance between positively and negatively regulatory chemokines. The identification of a naturally occurring eosinophil inhibitory chemokine pathway in vivo provides a strategic basis for future therapeutic consideration.

Allergen-induced cytokine production, atopic disease, IgE, and wheeze in children

BACKGROUND

The early childhood allergen-induced immune responses associated with atopic disease and IgE production in early life are not well understood.

OBJECTIVE

We assessed the relationship of allergen-induced cytokine production by PBMCs to both atopic disease and to IgE increase in a cohort of children with a parental history of allergy or asthma (n = 112) at a median of 2 years of age. We examined cockroach (Bla g 1)-induced, house dust mite (Der f 1)-induced, and cat (Fel d 1)-induced cytokine secretion, including secretion of IFN-gamma, IL-13, IL-10, and TNF-alpha. We investigated whether distinct cytokine patterns associated with atopic disease can be detected in immune responses of children.

METHODS

PBMCs were isolated, and allergen-induced cytokine secretion was analyzed by means of ELISA. Atopic disease was defined as physician- or nurse-diagnosed eczema or hay fever. Increased IgE was defined as an IgE level of greater than 35 U/mL to dust mite, cockroach, cat, and egg white or a total IgE level of 60 U/mL or greater.

RESULTS

Compared with children without atopic disease, children with atopic disease had lower Der f 1 (P =.005) and Bla g 2 (P =.03) allergen-induced IFN-gamma levels. Compared with children without increased IgE (n = 95), those with increased IgE (n = 16) had higher Der f 1-induced (P =.006) and Fel d 1-induced (P =.005) IL-13 levels and lower Bla g 2-induced (P =.03) IFN-gamma levels. Compared with children with neither atopic disease nor repeated wheeze, children with both atopic disease and repeated wheeze had lower levels of allergen-induced IFN-gamma (P =.01 for Der f 1 and P =.02 for Bla g 2) cytokine secretion.

CONCLUSION

In young children at risk for asthma or allergy, decreased allergen-induced IFN-gamma secretion is associated with atopic disease and, in some cases, with increased IgE levels. Increased allergen-induced IL-13 secretion is most strongly associated with early life increase of IgE.

Regulation of eotaxin gene expression by TNF-alpha and IL-4 through mRNA stabilization: involvement of the RNA-binding protein HuR

During inflammatory responses, a major posttranscriptional regulation of early response and inflammatory gene expression occurs through modulation of mRNA turnover. We report that two potent inducers of the CC chemokine eotaxin, TNF-alpha and IL-4, regulate its production in airway epithelial cells by increasing eotaxin mRNA stability. In experiments using the transcriptional inhibitor actinomycin D, eotaxin mRNA half-life was significantly prolonged by cell stimulation with TNF-alpha or IL-4, with the combination of the two cytokines being the most effective in extending the mRNA half-life. Involvement of the eotaxin 3' untranslated region in the mRNA-stabilizing effect was tested by transient transfection of a construct expressing a chimeric transcript carrying a serum-inducible beta-globin reporter linked to the eotaxin 3' untranslated region. The half-life of the chimeric mRNA was markedly increased in cells stimulated with TNF-alpha and IL-4. Evidence that the mRNA-stabilizing protein HuR participated in the cytokine effect was obtained: first, HuR presence in the cytoplasm, believed to be required for HuR-mediated mRNA stabilization, increased in both transformed (BEAS-2B cell line) and primary bronchial epithelial cells following treatment with TNF-alpha and IL-4. Second, endogenous eotaxin mRNA was found to bind to HuR in vivo, as detected by immunoprecipitation of HuR-containing messenger ribonucleoprotein complexes followed by real-time RT-PCR analysis; such association increased after cell treatment with TNF-alpha and IL-4. Third, overexpression of HuR in BEAS-2B cells significantly increased the expression of eotaxin mRNA and protein. Our findings implicate mRNA stabilization in the cytokine-mediated increase in eotaxin expression and strongly suggest a role for HuR in this effect.

Intratracheal IL-13 induces eosinophilic esophagitis by an IL-5, eotaxin-1, and STAT6-dependent mechanism

BACKGROUND & AIMS

Eosinophil infiltration into the esophagus occurs in a wide range of diseases; however, the underlying pathophysiologic mechanisms involved are largely unknown. We have previously reported that simultaneous delivery of allergen to the lung and gastrointestinal tract induces experimental eosinophilic esophagitis (EE). We aimed to determine whether delivery of a Th2 cytokine (interleukin [IL]-13) to the lung was sufficient for induction of EE.

METHODS

IL-13 was delivered intratracheally to wild-type, signal transducer and activator of transcription (STAT) 6, eotaxin-1, or IL-5-deficient mice. Eosinophil levels and 5'-bromodeoxyuridine (BrdU) incorporation were examined by immunohistochemical staining.

RESULTS

Intratracheal delivery of IL-13 induced dose-dependent eosinophil accumulation in the esophagus (but not the stomach). In addition, intratracheal IL-13 induced esophageal epithelial hyperplasia. The ability of IL-13 to induce EE was abolished in STAT6-deficient mice. IL-13-induced EE was nearly completely ablated in IL-5-deficient mice (37.3 +/- 11.6 vs. 3.3 +/- 3.2 eosinophils/mm(2) in wild-type and IL-5-deficient mice, respectively). Additionally, IL-13-induced EE was significantly diminished in eotaxin-1-deficient mice (48.7 +/- 10.3 vs. 14.1 +/- 12.5 eosinophils/mm(2) in wild-type and eotaxin-1-deficient mice, respectively).

CONCLUSIONS

IL-13 delivery to the lung induces EE by an IL-5, eotaxin-1, and STAT6-dependent mechanism. These results further establish an intimate connection between respiratory and esophageal inflammation.

Role of regulator of G protein signaling 16 in inflammation-induced T lymphocyte migration and activation

Chemokine-induced T lymphocyte recruitment to the lung is critical for allergic inflammation, but chemokine signaling pathways are incompletely understood. Regulator of G protein signaling (RGS)16, a GTPase accelerator (GTPase-activating protein) for Galpha subunits, attenuates signaling by chemokine receptors in T lymphocytes, suggesting a role in the regulation of lymphocyte trafficking. To explore the role of RGS16 in T lymphocyte-dependent immune responses in a whole-organism model, we generated transgenic (Tg) mice expressing RGS16 in CD4(+) and CD8(+) cells. rgs16 Tg T lymphocytes migrated to CC chemokine ligand 21 or CC chemokine ligand 12 injection sites in the peritoneum, but not to CXC chemokine ligand 12. In a Th2-dependent model of allergic pulmonary inflammation, CD4(+) lymphocytes bearing CCR3, CCR5, and CXCR4 trafficked in reduced numbers to the lung after acute inhalation challenge with allergen (OVA). In contrast, spleens of sensitized and challenged Tg mice contained increased numbers of CD4(+)CCR3(+) cells producing more Th2-type cytokines (IL-4, IL-5, and IL-13), which were associated with increased airway hyperreactivity. Migration of Tg lymphocytes to the lung parenchyma after adoptive transfer was significantly reduced compared with wild-type lymphocytes. Naive lymphocytes displayed normal CCR3 and CXCR4 expression and cytokine responses, and compartmentation in secondary lymphoid organs was normal without allergen challenge. These results suggest that RGS16 may regulate T lymphocyte activation in response to inflammatory stimuli and migration induced by CXCR4, CCR3, and CCR5, but not CCR2 or CCR7.

Chemokines: roles in leukocyte development, trafficking, and effector function

Chemokines, representing a large superfamily of 8- to 15-kd proteins, were originally discovered through their ability to recruit various cell types into sites of inflammation. It is now clear that these molecules play a much wider role in immune homeostasis, playing key roles in driving the maturation, homing, and activation of leukocytes. In this review we analyze the roles chemokines play in the development, recruitment, and activation of leukocytes. Because signaling from the receptors drives these processes, signal transduction from chemokine receptors will also be reviewed. Taken together, we highlight the various points at which chemokines contribute to allergic inflammation and at which their targeting might contribute to new therapies for type I hypersensitivity reactions.