Th2 cells as targets for therapeutic intervention in allergic bronchial asthma

Pathogenesis and disease mechanisms of occupational asthma

Occupational asthma (OA) is one of the most common forms of work-related lung disease in all industrialized nations. The clinical management of patients with OA depends on an understanding of the multifactorial pathogenetic mechanisms that can contribute to this disease. This article discusses the various immunologic and nonimmunologic mechanisms and genetic susceptibility factors that drive the inflammatory processes of OA.

Allergen-specific CTL require perforin expression to suppress allergic airway inflammation

Allergen-specific CTL have a protective effect on allergic airway inflammation, a function thought to be mediated by cytokines, especially IFN-γ. However, the contribution of cytotoxic function to this protective effect has not been investigated. We examined the contribution of cytotoxic function to the therapeutic effect of allergen-specific CTL in allergic airway inflammation. We used a murine model of allergic airway inflammation in which mice were sensitized to OVA and then challenged with the same Ag via the intranasal route. CTL were elicited in these mice by immunization with dendritic cells (DC) or by adoptive transfer of in vitro-activated CD8(+) T cells. Hallmark features of allergic asthma, such as infiltration of eosinophils in the bronchoalveolar lavage fluid and mucus production, were assessed. Suppression of allergic airway inflammation by allergen-specific CTL was critically dependent on the expression of perforin, a key component of the cytotoxic machinery. Both perforin-sufficient and perforin-deficient allergen-specific CTL were recovered from the lungs of allergen-sensitized mice and upregulated CD69 expression and secreted the cytokines IFN-γ and TNF-α upon intranasal allergen challenge. However, only perforin-sufficient CTL inhibited eosinophil infiltration in the airway, mucus production, and cytokine accumulation in the bronchoalveolar lavage fluid. Treatment with allergen-specific CTL, but not their perforin-deficient counterparts, was also associated with a decrease in the number of DC in the mediastinal lymph node. Our data suggest that the cytotoxic function of allergen-specific CD8(+) T cells is critical to their ability to moderate allergic airway inflammation.

IFN-γ elevates airway hyper-responsiveness via up-regulation of neurokinin A/neurokinin-2 receptor signaling in a severe asthma model

The adoptive transfer of OVA-specific Th1 cells into WT mice followed by OVA inhalation induces a significant elevation of airway hyper-responsiveness (AHR) with neutrophilia but not mucus hypersecretion. Here, we demonstrate that the airway inflammation model, pathogenically characterized as severe asthma, was partly mimicked by i.n. administration of IFN-γ. The administration of IFN-γ instead of Th1 cells caused AHR elevation but not neutrophilia, and remarkably induced neurokinin-2 receptor (NK2R) expression along with neurokinin A (NKA) production in the lung. To evaluate whether NKA/NK2R was involved in airway inflammation, we first investigated the role of NKA/NK2R-signaling in airway smooth muscle cells (ASMCs) in vitro. NK2R mRNA expression was significantly augmented in tracheal tube-derived ASMCs of WT mice but not STAT-1(-/-) mice after stimulation with IFN-γ. In addition, methacholine-mediated Ca(2+) influx into the ASMCs was significantly reduced in the presence of NK2R antagonist. Moreover, the NK2R antagonist strongly inhibited IFN-γ-dependent AHR elevation in vivo. Thus, these results demonstrated that IFN-γ directly acts on ASMCs to elevate AHR via the NKA/NK2R-signaling cascade. Our present findings suggested that NK2R-mediated neuro-immuno crosstalk would be a promising target for developing novel drugs in Th1-cell-mediated airway inflammation, including severe asthma.

Inhibition of airway inflammation, hyperresponsiveness and remodeling by soy isoflavone in a murine model of allergic asthma

Epidemiologic studies have associated higher dietary consumption of soy isoflavones with decreased self-report of cough and allergic respiratory symptoms, but the pharmacodynamic effects of soy isoflavone on asthmatic model have not been well-described. Here, we hypothesized that soy isoflavone may have potential effects on airway hyperresponsiveness, inflammation and airway remodeling in a murine of asthma. Mice sensitized and challenged with ovalbumin developed airway inflammation. Bronchoalveolar lavage fluid was assessed for inflammatory cell counts, and for cytokine levels. Lung tissues were examined for cell infiltration, mucus hypersecretion and airway remodeling, and for the expression of inflammatory biomarkers. Airway hyperresponsiveness was monitored by direct airway resistance analysis. Oral administration of soy isoflavone significantly reduced ovalbumin-induced airway hyperresponsiveness to intravenous methacholine, and inhibited ovalbumin-induced increases in eosinophil counts. RT-PCR analysis of whole lung lysates revealed that soy isoflavone markedly suppressed ovalbumin-induced mRNA expression of eotaxin, interleukin(IL)-5, IL-4 and matrix metalloproteinase-9, and increased mRNA expression of interferon (IFN)-γ and tissue inhibitor of metalloproteinase-1 in a dose-dependent manner. Soy isoflavone also substantially recovered IFN-γ/IL-4 (Th1/Th2) levels in bronchoalveolar lavage fluid. In addition, histologic studies showed that soy isoflavone dramatically inhibited ovalbumin-induced lung tissue eosinophil infiltration, airway mucus production and collagen deposition in lung tissues. Our findings suggest that soy isoflavone as nutritional supplement may provide a novel means for the treatment of airway inflammatory disease.

Therapeutic targeting of respiratory syncytial virus G-protein

Respiratory syncytial virus (RSV) is a leading cause of pneumonia and bronchiolitis in infants and young children and an important pathogen of the elderly and immune suppressed. The only intervention currently available is a monoclonal antibody against the RSV fusion protein, which has shown utility as a prophylactic for high-risk premature infants, but which has not shown postinfection therapeutic efficacy in the specific RSV-infected populations studied. Thus, for the major susceptible populations, there remains a great need for effective treatment. Recent results support monoclonal antibody targeting of the RSV G-protein for therapeutic use. This objective encompasses a dual mechanism: reduction in the ability of RSV G-protein to distort the host innate immune response, and direct complement-mediated antiviral activity.

Inhibition of 2,4-dinitrofluorobenzene-induced atopic dermatitis by topical application of the butanol extract of Cordyceps bassiana in NC/Nga mice

ETHNOPHARMACOLOGICAL SIGNIFICANCE

The Cordyceps species are insect-borne mushrooms that have been ethnopharmacologically used for skin diseases such as eczema and dermatitis.

AIM OF THE STUDY

In this study, we investigated the curative effects of the butanol fraction (CBBF) of Cordyceps bassiana on atopic dermatitis.

MATERIALS AND METHODS

Dermatitis was induced by repeated application of 2,4-dinitrofluorobenzene (DNFB) in NC/Nga mice. After a topical application of CBBF on the skin lesions, the dermatitis score, epidermal thickness, mast cell number, and interleukin (IL)-4 and interferon (IFN)-γ, as well as the levels of histamine and immunoglobulin E (IgE) in the serum, were measured. Moreover, effect of CBBF on histamine release was examined using RBL-2H3 under stimulation with 2,4-dinitrophenylated bovine serum albumin (DNP-BSA).

RESULTS

CBBF inhibited atopic dermatitis symptoms and signs in the DNFB-treated NC/Nga mice. The suppressive activity of topically applied CBBF may be due to the dose-dependent blockade of a series of immunopathological events, including the release of histamine, the production of IgE, and the secretion of IL-4 and IFN-γ. However, this extract did not directly suppress the degranulation process, assessed by measuring β-hexosaminidase release.

CONCLUSIONS

Our results suggest that CBBF can be applied as an effective herbal remedy to treat atopic dermatitis.

Antioxidant and antiasthmatic effects of saucerneol D in a mouse model of airway inflammation

Chronic airway inflammation is a hallmark of asthma, which is an immune-based disease. We evaluated the ability of saucerneol D, a tetrahydrofuran-type sesquilignan isolated from Saururus chinensis, to regulate airway inflammation in an ovalbumin (OVA)-induced airway inflammation model. Furthermore, we determined whether heme oxygenase (HO)-1 was required for the protective activity of saucerneol D. The airways of OVA-sensitized mice exposed to an OVA challenge developed eosinophilia and mucus hypersecretion and exhibited increased cytokine levels. Mice were administered saucerneol D orally at doses of 20 and 40mg/kg once daily on days 26-30. Saucerneol D administered orally significantly inhibited the number of OVA-induced inflammatory cells and the production of immunoglobulin E as well as Th2-type cytokines. Histopathology studies revealed a marked decrease in lung inflammation and goblet cell hyperplasia after saucerneol D treatment. In addition, saucerneol D induced HO-1 and led to a marked decrease in OVA-induced reactive oxygen species and malondialdehyde and an increase in superoxide dismutase and glutathione in lung tissues. These antioxidant effects were correlated with HO-1 induction. In our experiments, saucerneol D treatment reduced airway inflammation and suppressed oxidative stress in an OVA-induced asthma model.

M(3) muscarinic receptor antagonist bencycloquidium bromide attenuates allergic airway inflammation, hyperresponsiveness and remodeling in mice

M(3) muscarinic receptors are localized on inflammatory cells, airway smooth muscle, and submucosal glands, known to mediate bronchoconstriction, mucus secretion, and airway remodeling. It is hypothesized bencycloquidium bromide (BCQB), a novel M(3) receptor antagonist, might have potential effects on airway hyperresponsiveness, inflammation and airway remodeling in a murine model of asthma. Mice sensitized and challenged with ovalbumin developed airway inflammation. Bronchoalveolar lavage fluid was examined to determine the total and differential cell counts, and cytokine levels. Lung tissues were evaluated for cell infiltration, mucus hypersecretion, airway remodeling, and the expression of inflammatory biomarkers. Airway hyperresponsiveness was monitored by direct airway resistance analysis. Inhalation administration of BCQB significantly not only reduced ovalbumin-induced airway hyperresponsiveness comparing to methacholine, and prevented the ovalbumin-induced increase in total cell counts and eosinophil counts. Reverse transcriptase polymerase chain reaction analysis of whole lung lysates revealed that BCQB markedly suppressed ovalbumin-induced mRNA expression of eotaxin, IL-5, IL-4 and MMP-9, and increased mRNA expression of IFN-γ and TIMP-1 in a dose-dependent manner. Substantial IFN-γ/IL-4 (Th1/Th2) levels were recovered in bronchoalveolar lavage fluid after BCQB treatment. In addition, histological studies showed that BCQB dramatically inhibited ovalbumin-induced lung tissue eosinophil infiltration, airway mucus production and collagen deposition in lung tissues. Results reported in current paper suggest that M(3) receptors antagonist may provide a novel therapeutic approach to treat airway inflammation, hyperresponsiveness and remodeling.

Chemoattractant-induced signaling via the Ras-ERK and PI3K-Akt networks, along with leukotriene C4 release, is dependent on the tyrosine kinase Lyn in IL-5- and IL-3-primed human blood eosinophils

Human blood eosinophils exhibit a hyperactive phenotype in response to chemotactic factors after cell "priming" with IL-5 family cytokines. Earlier work has identified ERK1/2 as molecular markers for IL-5 priming, and in this article, we show that IL-3, a member of the IL-5 family, also augments fMLP-stimulated ERK1/2 phosphorylation in primary eosinophils. Besides ERK1/2, we also observed an enhancement of chemotactic factor-induced Akt phosphorylation after IL-5 priming of human blood eosinophils. Administration of a peptide antagonist that targets the Src family member Lyn before cytokine (IL-5/IL-3) priming of blood eosinophils inhibited the synergistic increase of fMLP-induced activation of Ras, ERK1/2 and Akt, as well as the release of the proinflammatory factor leukotriene C(4). In this study, we also examined a human eosinophil-like cell line HL-60 clone-15 and observed that these cells exhibited significant surface expression of IL-3Rs and GM-CSFRs, as well as ERK1/2 phosphorylation in response to the addition of IL-5 family cytokines or the chemotactic factors fMLP, CCL5, and CCL11. Consistent with the surface profile of IL-5 family receptors, HL-60 clone-15 recapitulated the enhanced fMLP-induced ERK1/2 phosphorylation observed in primary blood eosinophils after priming with IL-3/GM-CSF, and small interfering RNA-mediated knockdown of Lyn expression completely abolished the synergistic effects of IL-3 priming on fMLP-induced ERK1/2 phosphorylation. Altogether, our data demonstrate a central role for Lyn in the mechanisms of IL-5 family priming and suggest that Lyn contributes to the upregulation of the Ras-ERK1/2 and PI3K-Akt cascades, as well as the increased leukotriene C(4) release observed in response to fMLP in "primed" eosinophils.

The other T helper cells in asthma pathogenesis

The complex phenotype of allergic bronchial asthma involves a variable degree of bronchoobstruction, increased mucus production, and airway remodeling. So far it is suggested that it arises from multiple interactions of infiltrating and structural cells in the context of chronic airway inflammation that is orchestrated by T helper 2 (TH2) cells. By secreting a plethora of typical mediators such as interleukin (IL) 4, IL-5, and IL-13, these cells hold a key position in asthma pathogenesis. However, therapeutic approaches targeting these TH2-type mediators failed to improve asthma symptoms and impressively showed that asthma pathogenesis cannot be reduced by TH2 cell functions. Recently, other T helper cells, that is, TH9 and TH17 cells, have been identified and these cells also contribute to asthma pathogenesis, the processes leading to formation or aggravation of asthma. Furthermore, TH25 cells, TH3 cells, and regulatory T cells have also been implicated in asthma pathogenesis. This paper aims at summarizing recent insights about these new T helper cells in asthma pathogenesis.

Serum cytokine analysis in a positive chemoprevention trial: selenium, interleukin-2, and an association with squamous preneoplastic disease

This study represents a multiplex cytokine analysis of serum from a 10-month randomized, controlled trial of 238 subjects that investigated the effects of selenomethionine and/or celecoxib in subjects with mild or moderate esophageal squamous dysplasia. The original chemoprevention study found that, among those with mild dysplasia, selenomethionine treatment favorably altered dysplasia grade. The current analysis found that selenomethionine downregulated interleukin (IL)-2 by 9% (P = 0.04), whereas celecoxib downregulated IL-7 by 11% (P = 0.006) and upregulated IL-13 by 17% (P = 0.008). In addition, an increase in IL-7 tertile from baseline to t10 was significantly associated with an increase in dysplasia grade, both overall [odds ratio (OR), 1.47; P = 0.03] and among those with mild dysplasia at t0 (OR, 2.53; P = 0.001). An increase in IL-2 tertile from baseline to t10 was also nonsignificantly associated with worsening dysplasia for all participants (OR, 1.32; P = 0.098) and significantly associated with worsening dysplasia among those with mild dysplasia at baseline (OR, 2.0; P = 0.01). The association of increased IL-2 with worsening dysplasia remained significant in those on selenomethionine treatment who began the trial with mild dysplasia (OR, 2.52; P = 0.03). The current study shows that selenomethionine supplementation decreased serum IL-2 levels, whereas celecoxib treatment decreased IL-7 levels and increased IL-13 levels during a 10-month randomized chemoprevention trial. An increase in IL-2 or IL-7 was associated with increased severity of dysplasia over the course of the trial, especially in those who began the trial with mild dysplasia. The favorable effect of selenomethionine on esophageal dysplasia in the original trial may have been mediated in part by its effect in reducing the levels of IL-2.

Histamine H1-receptor antagonists with immunomodulating activities: potential use for modulating T helper type 1 (Th1)/Th2 cytokine imbalance and inflammatory responses in allergic diseases

Being a first-line treatment for hypersensitivity allergic disease, histamine H1-receptor antagonists possess anti-inflammatory activity in addition to being H1-receptor antagonists. While it is not purely a histamine-related condition, hypersensitivity allergic disease is associated with an increase in the number of T helper type 2 (Th2) cells and Th2 cytokines, and a decrease in the number of Th1 cells and Th1 cytokines. Suppression of Th2-type cytokine production in addition to H1-receptor blockade may therefore represent a successful therapeutic strategy for the treatment of hypersensitivity allergic diseases. H1-receptor antagonists have been reported to modulate immune cascade at various points by acting on T cell-related inflammatory molecules, including adhesion molecules, chemokines and inflammatory cytokines. These effects of H1-receptor antagonists may be optimized for the treatment of allergic diseases. Besides their ability to regulate inflammatory molecules, some H1-receptor antagonists have been reported to down-regulate Th2 cytokine production. In particular, it has been shown that several H1-receptor antagonists specifically inhibit the production of Th2, but not Th1, cytokines. Accumulating evidence indicates a crucial role for Th1/Th2 cytokine imbalance on the development of allergic diseases. Accordingly, the use of H1-receptor antagonist with Th2 cytokine inhibitory activity to modulate Th1/Th2 cytokine imbalance might be a favourable strategy for the treatment of hypersensitivity allergic diseases. Furthermore, the identification of H1-receptor antagonists which possess immunoregulatory activities in addition to their anti-histamine activity will provide an important insight into the development of novel immunoregulatory drugs.