Cytokines as targets for the inhibition of eosinophilic inflammation

Oxidative Stress Regulates IL-4 Gene Expression in Mast Cells through the Reduction of Histone Deacetylase

Objective

Many proinflammatory cytokines are regulated by the acetylation and deacetylation of the core histone. Since dysregulation of T helper 2 cytokine production is a key in the pathogenesis of allergic diseases, we examined the role of histone deacetylase (HDAC) on interleukin (IL)–4 gene expression in mast cells. We also examined whether oxidative stress has any impact on HDAC activity.

Study Design

In vitro study.

Setting

Academic research laboratory.

Methods

An IgE-sensitized mast cell line (RBL-2H3 cells) was treated with varying concentrations of the HDAC inhibitors trichostatin A (TSA) and H2O2 and stimulated with antigens. The amount of IL-4 gene expression was quantified by real-time polymerase chain reaction. Quantitative measurement of IL-4 in the cell supernatant was performed using enzyme-linked immunosorbent assay. Moreover, HDAC activity was measured with the use of a nonisotopic assay that utilized an HDAC Fluorescent Activity Assay Kit.

Results

IL-4 mRNA expression was induced by antigens in IgE-sensitized RBL-2H3 cells. Pretreatment with TSA and H2O2 enhanced IL-4 mRNA expression up to 5-fold in a dose-dependent manner. Furthermore, HDAC activity in RBL-2H3 cells was reduced after treatment with H2O2.

Conclusion

Our results suggest that oxidative stress may up-regulate IL-4 gene expression in mast cells via a decrease in HDAC activity.

The Potential Role of Innate Immunity in the Pathogenesis of Hodgkin's Lymphoma

The innate immune system is our first line of defense against danger signals but in Hodgkin's lymphoma the role seems opposite, favoring malignant development. In this article we describe interactions between Hodgkin's and Reed-Sternberg cells and the cells of the innate immune system: eosinophils, mast cells, neutrophils, and macrophages. These cells clearly contribute to the pathogenesis of this disease and to the prognosis. Cytokines and chemokines released from the activated immune cells probably promote tumor cell growth and survival along with angiogenesis. Mast cells and eosinophils seem also to contribute to the fibrosis that is so characteristic for nodular sclerosis.

Rosmarinic acid in perilla extract inhibits allergic inflammation induced by mite allergen, in a mouse model

BACKGROUND

Perilla and its constituent rosmarinic acid have been suggested to have anti-allergic activity. However, few studies have examined the effects on allergic asthma.

OBJECTIVE

The purpose of this study was to evaluate the effect of oral administration of perilla leaf extract, which contains high amount of rosmarinic acid, on a murine model of allergic asthma induced by house dust mite allergen.

METHODS

C3H/He mice were sensitized by intratracheal administration of Dermatophagoides farinae (Der f). Mice were orally treated with rosmarinic acid in perilla extract (PE) (1.5 mg/mouse/day).

RESULTS

Der f challenge of sensitized mice elicited pulmonary eosinophilic inflammation, accompanied by an increase in lung expression of IL-4 and IL-5, and eotaxin. Daily treatment with rosmarinic acid in PE significantly prevented the increases in the numbers of eosinophils in bronchoalveolar lavage fluids and also in those around murine airways. Rosmarinic acid in PE treatment also inhibited the enhanced protein expression of IL-4 and IL-5, and eotaxin in the lungs of sensitized mice. Der f challenge also enhanced allergen-specific IgG1, which were also inhibited by rosmarinic acid in PE.

CONCLUSION

These results suggest that oral administration of perilla-derived rosmarinic acid is an effective intervention for allergic asthma, possibly through the amelioration of increases in cytokines, chemokines, and allergen-specific antibody.

Ragweed-induced expression of GATA-3, IL-4, and IL-5 by eosinophils in the lungs of allergic C57BL/6J mice

Allergen-induced recruitment of T lymphocytes and eosinophils to the airways is associated with increased expression of the transcription factor GATA-3. In this study, the relationship between airway inflammation and GATA-3 expression in the lungs was investigated using ragweed-sensitized C57BL/6J mice. Intratracheal ragweed challenge increased both the number of GATA-3-expressing cells in the perivascular and peribronchial regions and the amount of expression per cell. Interleukin (IL)-4 and IL-5 levels in bronchoalveolar lavage fluid were upregulated in parallel with GATA-3 expression. GATA-3 mRNA and protein colocalized to eosinophils. Eosinophils isolated from the lungs and stimulated with phorbol 12-myristate 13-acetate and/or A-23187 released IL-5. The release was inhibited by actinomycin D, which indicates that de novo synthesis of the cytokine was involved. Western blot analysis of proteins from isolated eosinophils demonstrated expression of the p50 subunit of nuclear factor-kappaB, a transcription factor that is implicated in control of GATA-3 expression. These data provide evidence that allergen challenge increases GATA-3 and proinflammatory cytokine expression by pulmonary eosinophils, which could provide positive feedback for the inflammatory response.

Acute morphine treatment alters cellular immune function in the lungs of healthy rats

Previous work has shown that morphine suppresses the pulmonary immune response to infection and reduces pulmonary inflammation. No published studies have addressed the impact of morphine on lymphocyte function in the lungs without infection. This study addressed this question by assessing the impact of acute morphine treatment on proliferation, cytokine production, and natural killer (NK) cell activity in resident pulmonary lymphocytes from healthy rats. Male Lewis rats received either a single 15 mg/kg morphine sulfate or vehicle injection 1 h prior to sacrifice. Lungs were minced and passed through wire mesh following collagenase digestion. The resulting cell preparations were pooled (2 rats/pool) to yield sufficient cell numbers for the functional assays, and a portion of these suspensions were separated using a density gradient. Crude and purified cell suspensions were used in assays of NK cell activity and mitogen-induced proliferation and cytokine production. Morphine significantly suppressed lymphocyte proliferation and cytokine production in whole cell suspensions, but not in purified cultures. NK activity was enhanced by morphine treatment in purified treated cultures. Studies of nitrate/nitrite levels in crude and purified cultures suggest that macrophage-derived nitric oxide may be a mechanism of the suppression observed in whole cell suspensions following morphine treatment. These data are consistent with previous work showing that morphine suppresses mitogenic responsiveness and NK activity in the spleen and peripheral blood, and may do so through a macrophage-derived nitric oxide mechanism.

Interleukin 9 promotes influx and local maturation of eosinophils

The interleukin 9 (IL-9) pathway has recently been associated with the asthmatic phenotype including an eosinophilic tissue inflammation. The mechanism by which IL-9 affects eosinophils (eos) is not known. To investigate whether this cytokine has a direct activity on the development of eos and eosinophilic inflammation, a model of thioglycolate-induced peritoneal inflammation was used in IL-9 transgenic (TG5) and background strain (FVB) mice. In this model, a transient eosinophilic infiltration in the peritoneal cavity was observed in FVB mice 12 to 24 hours after thioglycolate injection that coincided with peak IL-5 and IL-9 release. In contrast, TG5 mice developed a massive eosinophilia that persisted at high levels (81% of total cells) even 72 hours after thioglycolate injection. Release of eosinophilic major basic protein (MBP), IL-4, and IL-5 to the peritoneal cavity of these mice was significantly increased when compared with the control FVB strain. To study the mechanism by which IL-9 exerts its effect on eos, bone marrow or peritoneal cells were cultured in the presence of IL-5, IL-9, or their combination in vitro. IL-5 alone was able to generate significant numbers of eos in TG5 but not FVB mice, whereas a combination of IL-5 and IL-9 induced marked eosinophilia in both strains indicating a synergism between these 2 cytokines. These data suggest that IL-9 may promote and sustain eosinophilic inflammation via IL-5-driven eos maturation of precursors.

Dichotomy between neurokinin receptor actions in modulating allergic airway responses in an animal model of helper T cell type 2 cytokine-associated inflammation

Neurokinins (NKs), which include substance P (SP) and neurokinin A (NKA), act through NK-1 and NK-2 receptors. There is considerable evidence of interaction between the neurogenic and the immune systems, and NKs are candidates for mediating such interactions. We hypothesized that selective inhibition of pulmonary NK-1 or NK-2 receptors may modulate immune responses so as to prevent the development of allergic airway responses in the atopic BN rat sensitized to ovalbumin (OA). To address this hypothesis, we have validated our animal model by showing that NK-1 and NK-2 receptors are expressed in the lungs, and that SP is released in the airways after allergen challenge. The selective NK-1 (CP-99,994) or NK-2 (SR-48968) antagonists before allergen challenge failed to reduce the allergic early airway responses. In contrast, both neurokinin antagonists decreased allergen-induced late airway responses in OA-challenged animals. However, only the NK-2 antagonist decreased the eosinophil numbers in the bronchoalveolar lavage (BAL). Likewise, the NK-2, but not NK-1, antagonist decreased both Th1 (INF-gamma) and Th2 (IL-4 and -5) cytokine expression in BAL cells by in situ hybridization. These results provide initial in vivo evidence linking neurokinins to the regulation of cytokine expression in cells without discrimination as to their phenotype. We conclude that there is a dichotomy between NK receptors in the modulation of the allergic airway inflammation, which has important implications for future therapeutic strategies for asthma using the NK antagonists.

Dissociation of inflammatory and epithelial responses in a murine model of chronic asthma

To study pathogenetic mechanisms in chronic asthma, we employed a novel experimental model that replicates characteristic features of the human disease. Chronic inflammation and epithelial changes, specifically localized to the airways, were induced by repeated exposure of systemically sensitized BALB/c mice to low mass concentrations of aerosolized ovalbumin for 6 weeks. The contribution of Th2 cytokine-driven inflammation to the development of airway lesions and hyperreactivity was assessed in cytokine-deficient mice. In interleukin-5-deficient animals, intraepithelial eosinophils and chronic inflammatory cells in the lamina propria of the airways were markedly decreased; however, these animals developed epithelial hypertrophy and subepithelial fibrosis comparable with that observed in sensitized wild type mice. Airway hyperreactivity to inhaled methacholine did not develop in interleukin-5-deficient mice. In contrast, interleukin-4-deficient mice exhibited no decrease in airway inflammation, but had significantly greater epithelial hypertrophy and subepithelial fibrosis, as well as exaggerated hyperreactivity to methacholine. We conclude that interleukin-5, but not interleukin-4, plays a central role in the development of chronic inflammation of the airways and the induction of airway hyperreactivity. Furthermore, chronic epithelial and fibrotic changes occur independently of interleukin-5 and are not required for the development of airway hyperreactivity. The dissociation between airway wall remodeling and airway hyperreactivity has important implications for therapeutic approaches to chronic asthma.

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

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

Streptomyces anulatus from indoor air of moldy houses induce NO and IL-6 production in a human alveolar epithelial cell-line

Moisture associated microbial growth in buildings may cause respiratory symptoms such as pulmonary inflammation. We studied the effects of spores of Streptomyces anulatus, commonly found in moldy buildings, on the production of nitric oxide (NO), interleukin-6 (IL-6), interleukin-5 (IL-5), interleukin-4 (IL-4), and tumour necrosis factor alpha (TNFα), as well as cell viability in human alveolar II type epithelial cell line (A549). Cells were exposed in vitro to S. anulatus spores with and without interferon-γ (IFNγ) in vitro. Lipopolysaccharide (LPS) was used as a reference substance. S. anulatus alone, and in combination with IFNγ induced NO and IL-6 production and decreased cell viability whereas IL-4, IL-5 or TNFα production were not affected. IFNγ alone had a weaker but otherwise similar effect as S. anulatus on NO and IL-6 production and it potentiated the effects of S. anulatus. LPS did not induce NO or cytokine production, or affect cell viability in A549 cells. These data indicate that spores of S. anulatus induce the excretion of inflammatory mediators in respiratory epithelial cells, which may partly explain the adverse respiratory health effects experienced by individuals exposed to the indoor air of moldy houses.

IL-9 induces chemokine expression in lung epithelial cells and baseline airway eosinophilia in transgenic mice

Recent data have identified IL-9 as a key cytokine in determining susceptibility to asthma. These data are supported by the finding that allergen-exposed IL-9-transgenic mice exhibit many features that are characteristic of human asthma (airway eosinophilia, elevated serum IgE and bronchial hyperresponsiveness) as compared to the background strain. A striking feature of these animals is a robust peribronchial and perivascular eosinophilia after allergen challenge, suggesting that IL-9 is a potent factor in regulating this process. In an attempt to gain insights into the molecular mechanism governing IL-9 modulation of lung eosinophilia, we investigated the ability of this cytokine to induce the expression of CC-type chemokines in the lung because of their effect on stimulating eosinophil chemotaxis. Here we show that IL-9-transgenic mice in contrast to their congenic controls exhibit baseline lung eosinophilia that is associated with the up-regulation of CC-chemokine expression in the airway. This effect appears to be through a direct action of IL-9 because the addition of recombinant IL-9 to primary epithelial cultures and cell lines induced the expression of these chemokines in vitro. These data support a mechanism for IL-9 in regulating the expression of eosinophil chemotactic factors in lung epithelial cells.

Flow cytometric detection of antigen-specific cytokine responses in lung T cells in a murine model of pulmonary inflammation

Multiparameter flow cytometry was used to examine the cytokine responses of antigen-specific T lymphocytes isolated from the lungs of antigen-sensitized mice which developed pulmonary inflammation after aerosol challenge with ovalbumin (OA) (OA/OA). Lung T cells were stimulated in vitro with OA and anti-CD28 monoclonal antibody (mAb) in the presence of the secretion inhibitor, brefeldin A. T cell subsets were examined for intracellular cytokine expression using fluorochrome-labeled cell-surface specific and anti-cytokine antibodies. Antigen-specific responses resulted in significant numbers of CD4+ lung cells expressing cytoplasmic interleukin (IL)-2 (6%), IL-4 (1.5%), IL-5 (4%), and tumor necrosis factor (TNF)-alpha (11%), but not interferon (IFN)-gamma. Dual cytokine analyses demonstrated antigen-specific responses resulted in CD4+ T cells being positive for IL-2 and IL-4 or IL-2 and IL-5. TNF-alpha was the only antigen-specific cytokine response detected in CD8+ lung T cells after in vitro activation with OA. Cytokines in the supernatants of cultures activated with OA and anti-CD28 were measured by ELISA and the results confirmed the antigen-specific responses measured by flow cytometry. Polyclonal activation of lung T cells from OA/OA mice with 12-myristate 13-acetate (PMA), ionomycin, anti-CD3 mAb, and anti-CD28 mAb resulted in higher percentages of IL-2+ (43%) and IL-5+ (7%) CD4 cells when compared to CD4+ T cells from non-OA sensitized, challenged mice. CD8+ cells from OA/OA mice demonstrated intracellular staining for IL-2 (26%), TNF-alpha (55%), and IFN-gamma (37%), but not IL-4 or IL-5, after polyclonal activation. There is less agreement between intracellular cytokine staining of CD4+ T cells and cytokines released into the culture medium after polyclonal activation. Dual cytokine analyses of polyclonal-activated CD4+ cells demonstrated co-expression of IFN-gamma with IL-2, IL-4, or IL-5. T cells co-expressing IL-2 with IL-4 or IL-5 were also detected. These results demonstrate the utility of multiparameter flow cytometry to directly measure antigen-specific cytokine responses in subsets of T lymphocytes isolated from inflammatory sites.

Hyperresponsiveness in the human nasal airway: new targets for the treatment of allergic airway disease

Allergic rhinitis is a condition which affects over 15% of the population in the United Kingdom. The pathological process involves two stages: nasal inflammation, and the development of nasal airway hyperresponsiveness (AHR) to allergen and a number of other stimuli. This results in the amplification of any subsequent allergic reaction, contributing to the chronic allergic state. A number of different hypotheses have been proposed to explain the underlying mechanism of AHR, including a role for eosinophil-derived proteins, free radicals and neuropeptides. While there may be a number of independent pathways which can result in AHR, evidence obtained from both animal models and in vivo experiments in humans indicate that some mediators may interact with one another, resulting in AHR. Further research into these interactions may open new avenues for the pharmacological treatment of chronic allergic rhinitis, and possibly other allergic airway diseases.

Cellular and molecular regulation of eosinophil trafficking to the lung

Airway inflammation is central to the pathogenesis of allergic asthma, and molecules that mediate this process obviously represent targets for therapy. In the present article, we discuss our experiments, which point to CD4+ T cells and IL-5-driven eosinophilia as potential targets for the relief of bronchial hyperreactivity in late-phase asthma.