Th2 cytokines and asthma. Interleukin-4: its role in the pathogenesis of asthma, and targeting it for asthma treatment with interleukin-4 receptor antagonists

Development of a human IgG4 bispecific antibody for dual targeting of interleukin-4 (IL-4) and interleukin-13 (IL-13) cytokines

Human bispecific antibodies have great potential for the treatment of human diseases. Although human IgG1 bispecific antibodies have been generated, few attempts have been reported in the scientific literature that extend bispecific antibodies to other human antibody isotypes. In this paper, we report our work expanding the knobs-into-holes bispecific antibody technology to the human IgG4 isotype. We apply this approach to generate a bispecific antibody that targets IL-4 and IL-13, two cytokines that play roles in type 2 inflammation. We show that IgG4 bispecific antibodies can be generated in large quantities with equivalent efficiency and quality and have comparable pharmacokinetic properties and lung partitioning, compared with the IgG1 isotype. This work broadens the range of published therapeutic bispecific antibodies with natural surface architecture and provides additional options for the generation of bispecific antibodies with differing effector functions through the use of different antibody isotypes.

Protective effects of Scrophularia striata in Ovalbumin-induced mice asthma model

BACKGROUND

Scrophularia striata Boiss. (Scrophulariaceae) is a plant growing in the northeastern part of Iran and being used as a traditional herb for various inflammatory disorders.This study was designed to investigate the protective effects of the Scrophularia striata extract in Ovalbumin (OVA) induced-asthma mice model.

METHODS

OVA-sensitized mice were intrapritonealy treated with two doses (100 and 200 mg/kg) of the extract on days 8 to 14 separately. Broncoalveolar lavage fluids (BALF) was collected 48 h after the final OVA challenge and then the number of eosinophils and other inflammatory cells were assessed by direct microscopic counting. In addition, total immunoglubolin (Ig) E and OVA-specific IgE levels in serum, IL-4 and IL-5 cytokines in BALF were determined by Enzyme-Linked Immunosorbent Assay. Moreover, phytochemical assay by thin layer chromatography (TLC) and the 2, 2 diphenyl-1-picrylhydrazyl (DPPH) were used to evaluate the main compounds and the antioxidant capacity of the plant extract, respectively.

RESULTS

The results showed that the main components; including flavonoids, phenolic compounds and phenyl propanoids were presented in the S. striata extract. In addition, the treatment with extract significantly reduced the number of inflammatory cells and suppressed T-helper 2 (Th2) cytokines including IL-4 and IL-5 in BALF. Also, total IgE and OVA-specific IgE levels in the serum decreased.

CONCLUSION

Collectively, it is concluded that the extract has the potential to modulate the Th2 cytokines and could be used as immunomodulatory agent in the treatment of allergic asthma.

Targeting interleukins to treat severe asthma

Severe asthma is thought to be a heterogeneous disease with different phenotypes predicated primarily on the nature of the inflammatory cell infiltrate and response to corticosteroid therapy. This group of patients often has refractory disease with an associated increase in morbidity and mortality, and there remains a need for better therapies for severe asthmatics. Inflammatory changes in asthma are driven by immune mechanisms, within which interleukins play an integral role. Interleukins are cell-signaling cytokines that are produced by a variety of cells, predominantly T cells. Knowledge about their actions has improved the understanding of the pathogenesis of asthma and provided potential targets for novel therapies. To date, this has not translated into clinical use. However, there are ongoing clinical trials that use monoclonal antibodies for various interleukins, some of which have shown to be promising in Phase II studies.

Effects of interleukin-31 on MUC5AC gene expression in nasal allergic inflammation

BACKGROUND

Interleukin-31 (IL-31) is a newly discovered T helper lymphocyte-derived cytokine that plays an important role in allergic inflammation. However, the effects of IL-31 on mucus production in nasal allergic inflammation are completely unknown.

OBJECTIVE

To investigate the effects of IL-31 on mucin gene expression (MUC5AC) in patients with allergic rhinitis and in human airway epithelial cells.

METHODS

Expression levels of IL-31 and IL-31 receptor A (IL-31RA) were evaluated in the inferior turbinate of patients with allergic rhinitis and non-allergic rhinitis with immunohistochemistry. IL-31-induced MUC5AC gene expression was measured with a MUC5AC luciferase reporter assay in human epithelial HM3-MUC5AC cells and quantified by quantitative real-time polymerase chain reaction in human airway epithelial A549 cells.

RESULTS

IL-31RA was primarily localized in submucosal glands and upregulated in allergic rhinitis. IL-31 was detected in submucosal tissue and increased in allergic inflammation. MUC5AC gene expression was induced by IL-31 stimulation both in HM3-MUC5AC and A549 cells. Additionally, IL-31 cooperated with Th2 cytokines on MUC5AC gene expression in HM3-MUC5AC cells.

CONCLUSION

IL-31 and IL-31RA are upregulated in patients with allergic rhinitis, and induce MUC5AC gene expression in human airway epithelial cells. These findings suggest that IL-31 plays an important role in mucus overproduction in nasal allergic inflammation.

Monoclonal antibodies for asthma and chronic obstructive pulmonary disease

INTRODUCTION

In asthma and chronic obstructive pulmonary disease (COPD), the inflammation in the airways cannot always be controlled with conventional therapies, such as inhaled corticosteroids. Addition of more specific anti-inflammatory therapies, such as monoclonal antibodies, against inflammation pathways might improve the disease outcome.

AREAS COVERED

This review individually discusses the major inflammation pathways and their potential blocking monoclonal antibodies in asthma and COPD.

EXPERT OPINION

The current use of omalizumab in asthma provides a good example on the potential therapeutic role of monoclonal antibodies in both asthma and COPD. There are many other monoclonal antibodies which are currently investigated as possible therapies in these diseases. The identification of the disease subsets in which such antibodies might exert the maximum benefit opens the door for personalized medicine and for targeted biological therapy in asthma and COPD.

The relationship of plasma aluminum to oxidant-antioxidant and inflammation status in asthma patients

Aluminum (Al) is a non-essential mineral which human beings are exposed to on day-to-day life. The purpose of this study was to assess the concentrations of plasma Al and the relationship of those levels with risk factors for asthma. In total, 27 allergic asthmatics and 30 healthy volunteers were enrolled. Plasma Al and selected blood parameters were measured, and a pulmonary function test was performed. Higher Al concentrations were found in the asthmatics than the healthy controls. Increased immunoglobulin E, high-sensitivity C-reactive protein, lipid peroxidation products, and pro-inflammatory cytokines (tumor necrosis factor-α and interleukin [IL]-4) were observed, but IL-10 and overall antioxidant and enzyme activities were lower. Associations between oxidative-antioxidant status and inflammatory markers with plasma Al levels in asthmatics were noted. Al status was also linked to cytokine concentrations and pulmonary function. In conclusion, abnormal Al distribution may further precipitate oxidative stress and inflammation, alter Th1/Th2 lymphocyte balance, and therefore contribute to the development of asthma.

Minocycline blocks asthma-associated inflammation in part by interfering with the T cell receptor-nuclear factor κB-GATA-3-IL-4 axis without a prominent effect on poly(ADP-ribose) polymerase

Minocycline protects against asthma independently of its antibiotic function and was recently reported as a potent poly(ADP-ribose) polymerase (PARP) inhibitor. In an animal model of asthma, a single administration of minocycline conferred excellent protection against ovalbumin-induced airway eosinophilia, mucus hypersecretion, and Th2 cytokine production (IL-4/IL-5/IL-12(p70)/IL-13/GM-CSF) and a partial protection against airway hyperresponsiveness. These effects correlated with pronounced reduction in lung and sera allergen-specific IgE. A reduction in poly(ADP-ribose) immunoreactivity in the lungs of minocycline-treated/ovalbumin-challenged mice correlated with decreased oxidative DNA damage. The effect of minocycline on PARP may be indirect, as the drug failed to efficiently block direct PARP activation in lungs of N-methyl-N'-nitro-N-nitroso-guanidine-treated mice or H(2)O(2)-treated cells. Minocycline blocked allergen-specific IgE production in B cells potentially by modulating T cell receptor (TCR)-linked IL-4 production at the mRNA level but not through a modulation of the IL-4-JAK-STAT-6 axis, IL-2 production, or NFAT1 activation. Restoration of IL-4, ex vivo, rescued IgE production by minocycline-treated/ovalbumin-stimulated B cells. IL-4 blockade correlated with a preferential inhibition of the NF-κB activation arm of TCR but not GSK3, Src, p38 MAPK, or ERK1/2. Interestingly, the drug promoted a slightly higher Src and ERK1/2 phosphorylation. Inhibition of NF-κB was linked to a complete blockade of TCR-stimulated GATA-3 expression, a pivotal transcription factor for IL-4 expression. Minocycline also reduced TNF-α-mediated NF-κB activation and expression of dependent genes. These results show a potentially broad effect of minocycline but that it may block IgE production in part by modulating TCR function, particularly by inhibiting the signaling pathway, leading to NF-κB activation, GATA-3 expression, and subsequent IL-4 production.

A novel cinnamate derivative attenuates asthma features and reduces bronchial epithelial injury in mouse model

Airway epithelial injury is the hallmark of various respiratory diseases and therapeutic targeting of epithelial injury could be an effective strategy for controlling these diseases. We recently reported that a novel cinnamate, ethyl 3',4',5'-trimethoxythionocinnamate (ETMTC) derived from Piper longum derivative, was most potent among various cinnamate derivatives in inhibiting inflammatory cell adhesion molecules (CAMs). In this study, we investigated the effects of ETMTC on the features of allergic asthma and epithelial injury in a murine model. ETMTC treatment to ovalbumin sensitized and challenged mice during ovalbumin challenge reduced airway hyperresponsiveness, and airway inflammation. This attenuation of asthma features was associated with the reduction in the expressions of various CAMs, NF-κB activation, Th2 cytokines, eotaxin and 8-isoprostane that were estimated in lung homogenates. Further, it increased activities of mitochondrial complexes I and IV in lung mitochondria and reduced cytochrome c and caspase 9 activities in lung cytosol. In addition, it reduced the levels of oxidative DNA damage marker in bronchoalveolar lavage fluid and DNA fragmentation of bronchial epithelia in lung sections. Further, ETMTC not only increased the levels of 15-(S)-hydroxyeicosatetraenoic acid, suppressor of airway remodeling, but also inhibited goblet cell metaplasia and sub-epithelial fibrosis. These results demonstrate that ETMTC reduces epithelial injury and mitochondrial dysfunction associated with allergic asthma and thus ETMTC could be useful to develop efficient therapeutic molecule against asthma.

Cytokine therapy of tuberculosis at the crossroads

Drug treatment is the key strategy in TB control. However, the treatment course lasts 6-9 months because the current anti-TB drugs are poorly effective against nondividing (i.e., persistent) bacilli. As a result, completion rates are unsatisfactory, leading to emergence and spread of multidrug-resistant infection. It would, therefore, be very desirable to design a form of complementary treatment that could speed up the recovery process for people afflicted with TB and reduce the relapse rates. With the advancement of our understanding of the immunopathogenesis of TB, it has become increasingly possible to develop novel adjunctive immunotherapies for both drug-susceptible and drug-resistant TB. Notably, cytokines probably offer the most promising prospect of such a therapy being introduced in routine clinical practice. However, in many ways, the cytokine therapy of TB has reached a crossroad, since, although the initial promise failed to live up to expectations, sufficient encouraging evidence exists to warrant further exploration. There are clear arguments in favor as well as against such treatments. This review aims to provide a rationale for cytokine treatment of TB, to describe the current status of several cytokines that have been considered for that purpose and, ultimately, to make a case for the need for further clinical trials.

Serum levels of interleukin-13 and interferon-gamma from adult patients with asthma in Mysore

Serum protein analysis for noninvasive quantification of airway inflammation in asthma is a promising research tool in the field of lung diseases. Cytokines are believed to have major role in inflammatory process of the airways of the lung. There is an imbalance between T-helper (Th)-2 cells, which secrete interleukin (IL)-4 and interleukin (IL)-13, and Th1 cells, which secrete interferon (IFN)-gamma in asthma. To test the hypothesis that serum IL-13 and IL-4 levels may be elevated whereas IFN-gamma would be decreased in this cohort of patients, a property that could make them possible candidate biomarkers in determining asthma occurrence and severity, we measured concentrations of IL-4, IL-13 and IFN-gamma in serum samples of 88 subjects (44 normal, 12 with mild asthma, 16 with moderate asthma, and 16 with severe asthma). Serum Levels of IL-4, IL-13, and IFN-gamma were determined by an enzyme-linked immune-sorbent assay (ELISA). Median serum level of IFN-gamma in asthmatic patients was 8.0 pg/ml, while it was 11.4 pg/ml in healthy controls. However, the difference was not significant. Among the different age groups in whom IFN-gamma was assessed, the highest median value in both cases and controls was observed in the age group of 31-40 years. The median serum level of IL-13 was 40.0 pg/ml in asthmatic patients and 58.25 pg/ml in healthy controls. The difference was not significant. On subgroup analysis, no significant difference of IFN-gamma and IL-13 between asthma of different severities was observed. The study also revealed nonsignificant difference of serum cytokines with the duration of asthma, number of allergens, and severity of sensitization. Normal serum levels of IFN-gamma and IL-13 in asthmatic patients suggest their neutral role in the inflammatory process; however, more studies are required to establish the effect of these cytokines in adulthood asthma in different ethnic populations.

Anti-inflammatory and antinociceptive effects of salbutamol on acute and chronic models of inflammation in rats: involvement of an antioxidant mechanism

The possible role of β-2 adrenergic receptors in modulation of inflammatory and nociceptive conditions suggests that the β-2 adrenergic receptor agonist, salbutamol, may have beneficial anti-inflammatory and analgesic effects. Therefore, in this study, we induced inflammatory and nociceptive responses with carrageenan-induced paw edema or cotton-pellet-induced granuloma models, both of which result in oxidative stress. We hypothesized that salbutamol would prevent inflammatory and nociceptive responses by stimulating β-2 adrenergic receptors and the prevention of generation of ROS during the acute inflammation process in rats. Both doses of salbutamol used in the study (1 and 2 mg/kg) effectively blocked the acute inflammation and inflammatory nociception induced by carrageenan. In the cotton-pellet-induced granuloma test, both doses of salbutamol also significantly decreased the weight of granuloma tissue on the cotton pellets when compared to the control. Anti-inflammatory and analgesic effects of salbutamol were found to be comparable with those of indomethacin. Salbutamol decreased myeloperoxidase (MPO) activity and lipid peroxidation (LPO) level and increased the activity of superoxide dismutase (SOD) and level of glutathione (GSH) during the acute phase of inflammation. In conclusion, salbutamol can decrease acute and chronic inflammation, possibly through the stimulation of β-2 adrenergic receptors. This anti-inflammatory effect may be of significance in asthma treatment, where inflammation also takes part in the etiopathology. This study reveals that salbutamol has significant antioxidative effects, which at least partially explain its anti-inflammatory capabilities. These findings presented here may also shed light on the roles of β-2 adrenergic receptors in inflammatory and hyperalgesic conditions.

Targeting interleukin-4 in asthma: lost in translation?

The first discovery that interleukin-4 (IL-4) is crucial in the development of allergic airway inflammation originates from the early 1990s. Whereas initial studies in experimental animal models provided the community with the optimistic view that targeting IL-4 would be the ultimate solution for treating asthma, the translation of these findings to the clinic has not been evident and has not yet fulfilled the expectations. Many technical challenges have been encountered in the attempts to modulate IL-4 expression or activity and in transferring knowledge of preclinical studies to clinical trials. Moreover, biological redundancies between IL-4 and IL-13 have compelled a simultaneous blockade of both cytokines. A number of phase I/II studies are now providing us with clinical evidence that targeting IL-4/IL-13 may provide some clinical benefit. However, the initial view that asthma is a purely Th2-mediated disease had to be revised. Currently, different asthma phenotypes have been described, implying that blocking specifically Th2 cytokines, such as IL-4, IL-5, and IL-13, should be targeted to only a specific subset of patients. Taking this into consideration, IL-4 (together with IL-13) deserves attention as subject of further investigations to treat asthma. In this review, we will address the role of IL-4 in asthma, describe IL-4 signaling, and give an overview of preclinical and clinical studies targeting the IL-4 Receptor pathway.

Lung natural helper cells are a critical source of Th2 cell-type cytokines in protease allergen-induced airway inflammation

Overproduction of cytokines by T helper 2 (Th2) cells in the lung is thought to be a cause of asthma. Here we report that innate lymphocytes termed lung natural helper (LNH) cells are a T cell-independent source of Th2 cell-type cytokines in protease allergen-treated lungs. LNH (Lin(-)Sca-1(+)c-kit(+/lo)CD25(+)CD127(+)) cells, when stimulated by IL-33 plus IL-2, IL-7, or thymic stroma lymphopoietin (TSLP), produced large amounts of IL-5 and IL-13. Intranasal administration of protease allergen papain induced eosinophil infiltration and mucus hyperproduction in the lung of wild-type and Rag1(-/-) mice, but not in Rag2(-/-)Il2rg(-/-) mice that lack LNH cells. LNH cell depletion inhibited papain-induced airway inflammation in Rag1(-/-) mice whereas adoptive transfer of LNH cells enabled Rag2(-/-)Il2rg(-/-) mice to respond to papain. Treatment of lung explants with papain induced IL-33 and TSLP production by stroma cells and IL-5 and IL-13 production by LNH cells. Thus, LNH cells are critical for protease allergen-induced airway inflammation.

CD4⁺T cells: differentiation and functions

CD4⁺T cells are crucial in achieving a regulated effective immune response to pathogens. Naive CD4⁺T cells are activated after interaction with antigen-MHC complex and differentiate into specific subtypes depending mainly on the cytokine milieu of the microenvironment. Besides the classical T-helper 1 and T-helper 2, other subsets have been identified, including T-helper 17, regulatory T cell, follicular helper T cell, and T-helper 9, each with a characteristic cytokine profile. For a particular phenotype to be differentiated, a set of cytokine signaling pathways coupled with activation of lineage-specific transcription factors and epigenetic modifications at appropriate genes are required. The effector functions of these cells are mediated by the cytokines secreted by the differentiated cells. This paper will focus on the cytokine-signaling and the network of transcription factors responsible for the differentiation of naive CD4⁺T cells.

Intracerebral microinjection of interleukin-4/interleukin-13 reduces β-amyloid accumulation in the ipsilateral side and improves cognitive deficits in young amyloid precursor protein 23 mice

We previously reported that the anti-inflammatory cytokine interleukin (IL)-4 induced selective clearance of oligomeric β-amyloid (Aβ(1-42)) in rat primary type 2 microglial cells. For the present study, we investigated whether IL-4 and IL-13 could activate microglial cells to induce Aβ clearance in vivo and improve cognitive deficits in APP23 mice, which are amyloid precursor protein transgenic mice. We administered an intracerebral microinjection of a mixture of IL-4 and IL-13 or of saline vehicle into one hemisphere of APP23 mice and their wild-type littermates, 4.5 and 9 months old, after which we evaluated the effects of these treatments on spatial learning and memory by Morris Water Maze test and on accumulated amounts of Aβ. The cytokine injection significantly improved memory deficits of 4.5-month-old APP23 mice, but did not do so in 9-month-old APP23 mice, even though similar Aβ reductions were observed in both age groups of APP23 mice in the ipsilateral neocortex. The cytokine injection improved memory impairment of 9-month-old wild-type (WT) mice in the probe trial. Immunohistochemical analysis of the 4.5-month-old APP23 mice revealed the presence of increased numbers of microglial cells at 2 days after the cytokine injection. In addition to induced CD36 expression in the activated microglia, increased expression of neprilysin, mainly in neurons, suggested that the cytokines improved the cognitive deficits via degradation and clearance of intra- and extraneuronal Aβ peptides, of buffer-extractable nonplaque form. Double immunostaining also revealed that most of the activated microglia had the M2-like phenotype. This unique mechanism of IL-4/IL-13-induced clearance of Aβ may provide an additional strategy to prevent and/or cure Alzheimer's disease at early stage.

Endogenous interleukin-4 regulates glutathione synthesis following acetaminophen-induced liver injury in mice

In a recent study, we reported that interleukin (IL)-4 had a protective role against acetaminophen (APAP)-induced liver injury (AILI), although the mechanism of protection was unclear. Here, we carried out more detailed investigations and have shown that one way IL-4 may control the severity of AILI is by regulating glutathione (GSH) synthesis. In the present studies, the protective role of IL-4 in AILI was established definitively by showing that C57BL/6J mice made deficient in IL-4 genetically (IL-4(-/-)) or by depletion with an antibody, were more susceptible to AILI than mice not depleted of IL-4. The increased susceptibility of IL-4(-/-) mice was not due to elevated levels of hepatic APAP-protein adducts but was associated with a prolonged reduction in hepatic GSH that was attributed to decreased gene expression of γ-glutamylcysteine ligase (γ-GCL). Moreover, administration of recombinant IL-4 to IL-4(-/-) mice postacetaminophen treatment diminished the severity of liver injury and increased γ-GCL and GSH levels. We also report that the prolonged reduction of GSH in APAP-treated IL-4(-/-) mice appeared to contribute toward increased liver injury by causing a sustained activation of c-Jun-N-terminal kinase (JNK) since levels of phosphorylated JNK remained significantly higher in the IL-4(-/-) mice up to 24 h after APAP treatment. Overall, these results show for the first time that IL-4 has a role in regulating the synthesis of GSH in the liver under conditions of cellular stress. This mechanism appears to be responsible at least in part for the protective role of IL-4 against AILI in mice and may have a similar role not only in AILI in humans but also in pathologies of the liver caused by other drugs and etiologies.

The association between IFN-γ and IL-4 genetic polymorphisms and childhood susceptibility to bronchial asthma

The present study aims to investigate the association between the genetic polymorphisms of interferon (IFN)-γ and interleukin (IL)-4 with childhood susceptibility to asthma and the levels of IFN-γ, IL-4, and immunoglobulin (Ig) E among asthmatic children. A total of 100 asthmatic children and 122 control children were enrolled in the present study. The genotypes of the IFN-γ gene at the -179G/T locus and the IL-4 gene at the -33C/T and -589C/T loci were detected using polymerase chain reaction with restriction fragment length polymorphism. The IFN-γ gene at the +874A/T locus and the IFN-γ CA repeats were tested using allele-specific and capillary electrophoresis, respectively, whereas the IFN-γ, IL-4, and total IgE levels were measured using enzyme-linked immunosorbent assays. The 100 asthmatic children and the 122 control children were all GG homozygous in the -179 locus of the IFN-γ gene, which shows that the IFN-γ gene is not mutated at the -179 locus. No significant differences were found in terms of genotypic and allelic frequency distribution in the IFN-γ gene or the CA repeat at the +874A/T locus between the asthmatic children and the control (P>0.05). An association was found between the polymorphism of the IFN-γ gene at +874A/T and IFN-γ levels. IFN-γ expression was lower among patients with the AA genotype than those with the AT genotype (P<0.05); the genotypic and allelic frequency distributions of the IL-4 gene at -33C/T and -589C/T were significantly different between the asthmatic children and the control (P<0.05). The levels of IL-4 and IgE among children with TT genotype at the -33 and -589 loci were higher than those with the CT genotype, but only the polymorphism at -33C/T was associated with IL-4 levels (P<0.05). The polymorphisms of the IFN-γ gene at +874A/T or the CA repeats are not correlated with susceptibility to asthma. Thus, the polymorphism at +874A/T is correlated with IFN-γ level. The TT genotypes of the IL-4 gene at the -33 and -589 loci are associated with asthma susceptibility in children, and polymorphism at the -33 locus may be associated with IL-4 level.

Cytokine levels and profiles in children related to sickle cell disease and asthma status

Atopic asthma in patients with sickle cell disease (SCD) is associated with an increased risk of acute chest syndrome (ACS). Cytokine-mediated inflammation might explain this association. Studies of cytokine profiles in patients with SCD have yielded conflicting data, but the possible influence of asthma status has not been examined. Our aim was to test the hypothesis that cytokine levels and profiles in SCD children reflected their asthma status. Samples from 155 Jamaican children (80 had SCD) and 64 British children (53 had SCD) who had their asthma status documented were analyzed for the presence and levels of interleukin 4 (IL-4) and interferon (IFN)-γ; they were also classified by their T helper cell (Th) cytokine profile. Jamaican children with SCD, when compared with Jamaican controls, were more likely to be diagnosed with asthma (P=0.001), more likely to be IL-4 positive (P<0.001), and more likely to be classified as having a Th-2 pattern (<0.001). In contrast, British children with SCD, when compared with the British controls, were less likely to have been diagnosed with asthma (P=0.04) and less likely to be classified as having a Th-2 pattern (P=0.006). Regression analysis demonstrated that amongst Jamaican children, SCD status, but not asthma status, ACS history, or gender, was predictive of IL-4 positivity and Th-2 status (P<0.001). In British children, none of those variables were significant predictors of IL-4 positivity or Th status. Cytokine profiles differed between Jamaican and British children. In the Jamaican children they reflected SCD, but not asthma or ACS status.

PARP-1 deficiency blocks IL-5 expression through calpain-dependent degradation of STAT-6 in a murine asthma model

BACKGROUND

We recently showed that poly(ADP-ribose)polymerase-1 (PARP-1) may play a role in allergen (ovalbumin)-induced airway eosinophilia, potentially through a specific effect on IL-5 production. We also reported that while IL-5 replenishment promotes reversal of eosinophilia in lungs of PARP-1(-/-) mice, IL-4 or Immunoglobulin E replenishment do not, suggesting a potentially significant regulatory relationship between PARP-1 and IL-5.

OBJECTIVE

To explore the mechanism by which PARP-1 regulates IL-5 production and to determine how PARP-1 inhibition blocks allergen-induced eosinophilia.

METHODS

This study was conducted using a murine model of allergic airway inflammation and primary splenocytes.

RESULTS

PARP-1 knockout-associated reduction in IL-5 upon allergen exposure occurs at the mRNA level. Such an effect appears to take place after IL-4 receptor activation as PARP-1 inhibition exerted no effect on JAK1/JAK3 activation. Signal transducer and activator of transcription-6 (STAT-6) protein was severely downregulated in spleens of PARP-1(-/-) mice without any effect on mRNA levels, suggesting an effect on protein integrity rather than gene transcription. Interestingly, the degradation of STAT-6 in PARP-1(-/-) mice required allergen stimulation. Additionally, PARP-1 enzymatic activity appears to be required for STAT-6 integrity. The downregulation of STAT-6 coincided with mRNA and protein reduction of GATA-binding protein-3 and occupancy of its binding site on the IL-5 gene promoter. IL-4 was sufficient to induce STAT-6 downregulation in both PARP-1(-/-) mice and isolated splenocytes. Such degradation may be mediated by calpain, but not by proteasomes.

CONCLUSION

These results demonstrate a novel function of PARP-1 in regulating IL-5 expression during allergen-induced inflammation and explain the underlying mechanism by which PARP-1 inhibition results in IL-5 reduction.

Inhibitory effects of costunolide isolated from Laurus nobilis on IgE-induced degranulation of mast cell-like RBL-2H3 cells and the growth of Y16 pro-B cells

This study investigated the inhibitory effects of costunolide isolated from the leaves of Laurus nobilis L. (Lauraceae) on basophil-mediated allergic reactions and interleukin (IL)-5-mediated B cell growth. The effects of costunolide on β-hexosaminidase (a key parameter of degranulation) release and IL-4 expression in rat basophilic leukemia (RBL-2H3) cells were determined by measuring β-hexosaminidase activity and by semi-quantitative RT-PCR, respectively. The effects of costunolide on Y16 pro-B cell viability and growth were determined by 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) assay. Costunolide was found significantly to inhibit β-hexosaminidase activity (p < 0.01) and IL-4 transcription in RBL-2H3 cells in a dose-dependent manner. Its 50% inhibitory concentration (IC50 ) was 34 µM, while that of the positive control, ketotifen, was 24 µM (IL-4 mRNA transcription). Moreover, costunolide dose-dependently suppressed pro-B cell growth in IL-5-stimulated Y16 cells. These results provide evidence that costunolide stabilizes mast cells by inhibiting IgE-mediated degranulation and inhibits IL-5-stimulated B cell growth.

Mitochondrial Dysfunction and Oxidative Stress in Asthma: Implications for Mitochondria-Targeted Antioxidant Therapeutics

Asthma is a complex, inflammatory disorder characterized by airflow obstruction of variable degrees, bronchial hyper-responsiveness, and airway inflammation. Asthma is caused by environmental factors and a combination of genetic and environmental stimuli. Genetic studies have revealed that multiple loci are involved in the etiology of asthma. Recent cellular, molecular, and animal-model studies have revealed several cellular events that are involved in the progression of asthma, including: increased Th2 cytokines leading to the recruitment of inflammatory cells to the airway, and an increase in the production of reactive oxygen species and mitochondrial dysfunction in the activated inflammatory cells, leading to tissue injury in the bronchial epithelium. Further, aging and animal model studies have revealed that mitochondrial dysfunction and oxidative stress are involved and play a large role in asthma. Recent studies using experimental allergic asthmatic mouse models and peripheral cells and tissues from asthmatic humans have revealed antioxidants as promising treatments for people with asthma. This article summarizes the latest research findings on the involvement of inflammatory changes, and mitochondrial dysfunction/oxidative stress in the development and progression of asthma. This article also addresses the relationship between aging and age-related immunity in triggering asthma, the antioxidant therapeutic strategies in treating people with asthma.

ASP3258, an orally active potent phosphodiesterase 4 inhibitor with low emetic activity

We investigated the pharmacology of a novel phosphodiesterase (PDE) 4 inhibitor, ASP3258 (3-[4-(3-chlorophenyl)-1-ethyl-7-methyl-2-oxo-1,2-dihydro-1,8-naphthyridin-3-yl] propanoic acid), comparing its potency with that of the most advanced PDE4 inhibitors, roflumilast and cilomilast. PDE4 inhibition by ASP3258 (IC(50)=0.28nM) was as potent as that achieved with roflumilast. ASP3258 inhibited lipopolysaccharide-induced tumor necrosis factor (TNF)-α production in rat whole blood cells (IC(50)=8.8 nM) and rat alveolar macrophages (IC(50)=2.6 nM). Orally administered ASP3258, roflumilast, and cilomilast dose-dependently inhibited production of interleukin-4, TNF-α, and cysteinyl leukotrienes, as well as leukocyte infiltration in bronchoalveolar lavage fluid from the airways of ovalbumin-sensitized Brown Norway rats, and these compounds showed almost complete inhibition at doses of 3, 3, and 30 mg/kg, respectively. PDE4 inhibitors induce emesis by mimicking the pharmacological action of α(2)-adrenoceptor antagonist. However, orally administered roflumilast (3mg/kg) and cilomilast (10mg/kg), but not ASP3258 (3mg/kg), inhibited α(2)-adrenoceptor agonist-induced anesthesia in rats and induced emesis in ferrets. Although ASP3258 (3mg/kg) inhibited airway inflammation completely, it had no emetic activity. As such, this compound may be useful in treating airway inflammatory diseases such as asthma and COPD.

The effects of antisense interleukin-4 gene transferred by recombinant adeno-associated virus vector on the airway remodeling in allergic rats

BACKGROUND

Th2-derived cytokines, including interleukin-4 (IL-4), are considered to play an important role in the development of airway remodeling of asthma.

OBJECTIVES

Our previous study has demonstrated that a recombinant adeno-associated virus containing antisense against IL-4 gene (rAAV-asIL4) vector could significantly suppress the expression of IL-4 protein and airway inflammation in the rat models of allergic asthma. In this study, we applied the rAAV-asIL4 vector to allergic rats to investigate the effects of anti-IL4 therapy on airway remodeling in allergic asthma.

METHODS

rAAV-asIL4 was used to infect the ovalbumin (OVA)-sensitized and challenged rats by tail-vein injection. IL-4 protein in bronchoalveolar lavage fluid (BALF) was detected by enzyme-linked immunosorbent assay. The number of eosinophils in BALF was counted. Transforming growth factor-beta1 (TGF-beta1) and TGF-beta2-positive cells in the peribronchial space were detected by immunohistochemical staining, and collagen deposition beneath the basement membrane was detected by Sirius red stain. The lung tissues were collected for histologic analysis of total bronchial wall area (W(At)) and airway smooth muscle area (W(Am)).

RESULTS

rAAV-asIL4 significantly decreased IL-4 protein in BALF of OVA-sensitized and challenged rats. The number of eosinophils in BALF, the TGF-beta1 and TGF-beta2-positive cells in the peribronchial space were also suppressed. Moreover, the rAAV-asIL4 treatment inhibited the area of Sirius red staining in airways and the increase in W(At) and W(Am).

CONCLUSION

These results suggest that rAAV-asIL4 may attenuate the airway remodeling process relevant to the inhibition of airway inflammation. This study provides elementary evidence for the potential utility of rAAV-asIL4 as an approach to gene therapy for asthmatic airway remodeling.

Role of the Mac-1 and VLA-4 integrins, and concomitant Th2-cytokine production, in nitric oxide modulated eosinophil migration from bone marrow to lungs in allergic mice

Although numerous studies demonstrate the participation of nitric oxide (NO) in various inflammatory diseases, the precise function of NO in allergic asthma remains unclear. We investigated whether iNOS inhibition could interfere with the kinetics of VLA-4 and Mac-1 expression and adhesion properties of bone marrow and peripheral blood eosinophils of sensitized mice after antigen exposure. Treatment of allergic mice with 1400 W (iNOS inhibitor) increased the adhesion of bone marrow eosinophils to ICAM-1, but not blood eosinophils, at 24h and 48 h after OVA-challenge. Conversely, adhesion of blood eosinophils from 1400 W-treated mice to VCAM-1 diminished at 24h and was almost completely blocked at 48 h. 1400 W did not induce any change in the adhesion of bone marrow eosinophils to VCAM-1, at 24h, but cells collected 48 h after challenge showed significantly lower adherence. Flow cytometry demonstrated that 1400 W resulted in a significantly increased Mac-1 expression on bone marrow eosinophils at 24h, as compared to control mice. However, at 24h, 1400 W significantly decreased Mac-1 and VLA-4 expressions on blood eosinophils. At 48 h, the expressions of both Mac-1 and VLA-4 returned to previous levels. Results show a temporal effect of iNOS upon Mac-1 expression and function, the chief adhesion molecule involved in the eosinophil efflux from the bone marrow at 24h. In contrast, Mac-1 and VLA-4 were involved in eosinophil mobilization from blood to lungs at 48 h after antigen challenge. Data suggest an important role of the Mac-1 and VLA-4 in the iNOS-modulated migration of eosinophils to the lungs of allergic mice.

Pitrakinra for asthma

IMPORTANCE OF THE FIELD

In asthma IL-4 and IL-13 have been demonstrated to play major pathogenic roles and therefore their blockade would potentially represent a plausible therapeutic approach.

AREAS COVERED IN THIS REVIEW

Pitrakinra is a dual IL-4/IL-13 inhibitor currently under development for asthma and the existing preclinical and clinical data are discussed.

WHAT THE READER WILL GAIN

Inhaled pitrakinra demonstrated a good anti-inflammatory potential and a good safety profile on a short-term basis but its place in asthma therapy is still to be found.

TAKE HOME MESSAGE

Specific anticytokine therapies might in the near future reshape asthma therapy.

Induction of RhoA gene expression by interleukin-4 in cultured human bronchial smooth muscle cells

RhoA, a small GTPase, is one of the key proteins of smooth muscle contraction. In allergic asthma, an upregulation of RhoA in bronchial smooth muscle has been suggested. However, the mechanism of its upregulation has not yet been clarified. In the present study, the effects of interleukin-4 (IL-4), one of the T-helper 2 cytokines, on RhoA mRNA expression and promoter activity of RhoA gene were examined in cultured human bronchial smooth muscle cells (hBSMCs). The quantitative real-time RT-PCR analyses revealed that incubation of hBSMCs with IL-4 (10, 30 and 100 ng/mL, for 24 hr) caused an increase in RhoA mRNA in a concentration-dependent manner. In luciferase reporter gene assay using hBSMCs that were transfected with luciferase constructs and were then stimulated with IL-4 (100 ng/mL), an importance of the most proximal STAT6 binding region (78-70 bp upstream of the transcription initiation site) was suggested. It is thus possible that IL-4 is capable of upregulating RhoA by promoting its transcription in hBSMCs. The proximal STAT6 binding region is required for the IL-4-induced increase in promoter activity of the human RhoA gene.

Aclidinium bromide abrogates allergen-induced hyperresponsiveness and reduces eosinophilia in murine model of airway inflammation

Airway hyperresponsiveness and inflammation characterize the airways of individuals with asthma and chronic obstructive pulmonary disease (COPD). Hence, therapeutic approaches that attenuate such manifestations may offer promise in the management of these diseases. In the present study, we investigated whether a novel long-acting cholinergic antagonist, aclidinium bromide, modulates airway function and leukocyte trafficking in an Aspergillus fumigatus (Af)-induced murine model of asthma. Nebulized aclidinium (1 mg/ml) administration completely abrogated increases in methacholine-induced lung resistance in Af-exposed mice. Parallel assessment of dynamic compliance showed that aclidinium also completely restores methacholine-mediated decreases in naïve and Af-exposed mice. As evidenced by differential cell counts within bronchoalveolar lavage fluid, aclidinium also diminished (51±4%) Af-induced airway eosinophil numbers with no significant change in other immune cell types. Further assessment of cytokine and total protein levels in bronchoalveolar lavage fluid showed that aclidinium had little effect on IL-4 or IL-6 levels in either Af-exposed or naïve mice but markedly decreased total protein levels in bronchoalveolar lavage fluid. These data suggest that aclidinium, a selective muscarinic antagonist, not only acts as a bronchodilator but could also act as an anti-inflammatory agent with potential clinical benefits in the treatment of COPD and asthma.

IL-4-mediated transcriptional regulation of human CYP2E1 by two independent signaling pathways

Cytochrome P450 2E1 (CYP2E1), the alcohol-inducible member of the cytochrome P450 super family, plays an important role in both physiological and pathophysiological processes. The present study focused on the induction of human CYP2E1 transcription by the anti-inflammatory cytokine interleukin-4 (IL-4) in human hepatoma B16A2 cells and revealed that this regulation is mediated by two independent pathways. RNA interference and overexpression of STAT6, indicated that the JAK-STAT signaling pathway is involved in IL-4-dependent induction and mutagenesis revealed the presence of a STAT6 binding site in CYP2E1 proximal promoter region (-583/-574-bp). However, inhibition of the JAK-STAT6 pathway using JAK1 siRNA constructs could only partially inhibit the induction of CYP2E1 promoter constructs indicating the presence of a second IL-4 responsive element. Indeed by using a series of truncated CYP2E1 promoter constructs a second more distal IL-4 responsive element (-1604/-1428-bp) was identified, which was further shown to involve the activation of IRS1/2. This induction was dependent on the transcription factor NFATc1 as IL-4-induced CYP2E1 expression was altered by silencing or overexpressing NFATc1. A NFATc1 binding site was identified in the second distal IL-4 responsive element (-1551/-1545-bp) by chromatin immunoprecipitation (ChIP) analysis. Finally simultaneous siRNA-mediated down-regulation of both STAT6 and NFATc1 or mutation of both STAT6 and NFATc1 binding sites abolished the IL-4-dependent transcriptional induction of CYP2E1, demonstrating that both pathways are required for maximal activation. In conclusion, the present study indicates that the induction of CYP2E1 transcription by IL-4 is mediated through two independent parallel pathways, involving JAK-STAT6 and IRS1/2 and NFATc1.

The influence of dexamethasone and the role of some antioxidant vitamins in the pathogenesis of experimental bronchial asthma

BACKGROUND

Bronchial asthma is a disease characterized by paroxysmal and reversible obstruction of the airways. The imbalance between the oxidant and antioxidant system that is called oxidative stress is critical in asthma pathogenesis. It is likely, therefore, that antioxidants may be effective in the treatment of asthma. Systemic treatment with glucocorticoids has been reported to inhibit smooth muscle hypercontraction which may account partially for their beneficial effects in the treatment of asthma.

OBJECTIVE

The present study was conducted in order to study the effect of dexamethasone and some antioxidant vitamins on interleukin-4 (IL-4), immunoglobulin E (IgE) and heat shock protein 70 (Hsp70) in bronchial asthma in rats, and to recognize their possible beneficial role.

METHOD

The study was conducted on 60 adult male albino rats randomly divided into 4 groups (15 for each group): including normal control group (group A); asthma model group where rats were sensitized by ovalbumin and challenged with antigen aerosol producing bronchial asthma (group B); asthma model group treated with antioxidant vitamins (vitamin E and vitamin C) (group C); asthma model group treated with dexamethasone (group D). Blood and lung samples were collected from all groups.

RESULTS AND CONCLUSION

Our results revealed a significant decrease of serum reduced glutathione (GSH) levels among groups B, C and D as compared to group A, while there was a significant increase in group C and D as compared to group B. Antioxidant and dexamethasone treatment resulted in a significant decrease of serum IL-4, malondialdehyde (MDA), and serum IgE levels in group C and D as compared to group B. Antioxidant treatment resulted in a significant decrease of serum Hsp70 level as compared to group B, while dexamethasone treatment resulted in a significant increase of serum Hsp70 level as compared to group B. This study suggests that it is likely that a combination of antioxidant vitamins may be effective in the treatment of asthma, considering their reported effects on lowering MDA, IL-4, and IgE levels, and the similar beneficial effects of dexamethasone in addition to increasing the expression of Hsp70 in the studied model of bronchial asthma.

Phosphorylation of signal transducer and activator of transcription 6 (STAT6) and STAT1, but not STAT3, induced by antigen inhalation in bronchial smooth muscles of sensitized mice

The signal transducer and activator of transcription (STAT) family of molecules play a critical role in the signaling of many cytokines. In addition to STAT6, implication of STAT1 and STAT3 in the development of airway hyperresponsiveness (AHR) has also been suggested in allergic bronchial asthma. However, there is little information whether or not antigen challenge really causes the in vivo activation of these STAT molecules in bronchial smooth muscles (BSMs). In the present study, the activations of these STATs were examined in BSMs of mice with allergic bronchial asthma. Male BALB/c mice were sensitized and repeatedly challenged with ovalbumin (OA) antigen. Total protein samples of the left main bronchi were prepared at 3 after the last OA challenge, and Western blot analyses for total and tyrosine-phosphorylated STATs molecules were conducted. In addition to the phosphorylation of STAT6, a significant increase in the level of phosphorylated STAT1 was also observed after the antigen exposure. In contrast, no significant increase in the level of phosphorylated STAT3 was observed in this mouse model of allergic bronchial asthma. The antigen exposure did not change the protein expressions of these STATs themselves. These findings suggest that STAT6 and STAT1, but not STAT3, might be crucial signal transducers in the development of BSM hyperresponsiveness, one of the causes of AHR in asthmatics.

Pro/Con debate: Is occupational asthma induced by isocyanates an immunoglobulin E-mediated disease?

Isocyanates, low-molecular weight chemicals essential to polyurethane production, are one of the most common causes of occupational asthma, yet the mechanisms by which exposure leads to disease remain unclear. While isocyanate asthma closely mirrors other Type I Immune Hypersensitivity (Allergic) disorders, one important characteristic of hypersensitivity ('allergen'-specific IgE) is reportedly absent in a large portion of affected individuals. This variation from common environmental asthma (which typically is induced by high-molecular weight allergens) is important for two reasons. (1) Allergen-specific IgE is an important mediator of many of the symptoms of bronchial hyper-reactivity in 'allergic asthma'. Lack of allergen-specific IgE in isocyanate hypersensitive individuals suggests differences in pathogenic mechanisms, with potentially unique targets for prevention and therapy. (2) Allergen-specific IgE forms the basis of the most commonly used diagnostic tests for hypersensitivity (skin prick and RAST). Without allergen-specific IgE, isocyanates may go unrecognized as the cause of asthma. In hypersensitive individuals, chronic exposure can lead to bronchial hyperreactivity that persists years after exposure ceases. Thus, the question of whether or not isocyanate asthma is an IgE-mediated disease, has important implications for disease screening/surveillance, diagnosis, treatment and prevention. The present Pro/Con Debate, addresses contemporary, controversial issues regarding IgE in isocyanate asthma.

Cytokine antagonists for the treatment of asthma: progress to date

Asthma is a disease of the airways in which several cytokines such as interleukin (IL)-4, IL-5, IL-13 and tumor necrosis factor-alpha (TNFalpha) play a major role in the development and progression of inflammation, airway hyperresponsiveness, mucus production, and airway remodeling. The conventional anti-inflammatory therapies, represented by inhaled corticosteroids and antileukotrienes, are not always able to provide optimal disease control and it is therefore hoped that cytokine antagonists could achieve this goal in such situations. Anticytokine therapies have been tested in preclinical studies and some have entered clinical trials. Anti-IL-4 therapies have been tested in animal models of allergy-related asthma, but because of unclear efficacy their development was discontinued. However, IL-4/IL-13 dual antagonists and IL-13-specific blocking agents are more promising, as they exhibit more sustained anti-inflammatory effects. IL-5 antagonists have been found to be of limited efficacy in clinical studies but might be useful in conditions characterized by severe hypereosinophilia, and in which asthma is one of the disease manifestations. Unlike other chronic inflammatory conditions, such as rheumatoid arthritis, the use of anti-TNFalpha therapies in asthma might be limited by the unfavorable risk/benefit ratio associated with long-term use. The identification of so-called asthma TNFalpha phenotypes and perhaps the use of a less aggressive treatment regimen might address this important aspect. Other cytokine antagonists (for example for IL-9 or IL-25) are currently being evaluated in the asthma setting, and could open new therapeutic perspectives based on their efficacy and safety.

Activation of signal transducer and activator of transcription factor 1 by interleukins-13 and -4 in cultured human bronchial smooth muscle cells

The family of signal transducer and activator of transcription (STAT) factors play a critical role in the signaling of many cytokines. In addition to the involvement of STAT6 in allergic bronchial asthma, both STAT1 and STAT3 have also been implicated. However, there is little information whether or not the T helper 2 cytokines, which cause several key features of allergic asthma, really induce the activation of STAT1 and/or STAT3 in bronchial smooth muscle (BSM) cells. In the present study, the effects of interleukin-13 (IL-13) and IL-4 on activation of these STAT molecules were examined in cultured human bronchial smooth muscle cells (hBSMCs). After a starvation period, the hBSMCs were treated with 100 ng/ml of IL-13 or IL-4. Total protein samples were prepared at intervals of 1, 3, 6, 12 and 24 hours after the cytokine treatment, and Western blot analyses for total and tyrosine-phosphorylated STATs molecules were conducted. As a result, ut was found that both IL-13 and IL-4 caused a significant increase in the levels of phosphorylated STAT1. Examination of the time-course revealed a peak of STAT1 phosphorylation at 1 hr after cytokine application. In contrast, neither IL-13 nor IL-4 induced phosphorylation of STAT3. Neither of these cytokines changed the protein expression of the STATs themselves. These findings suggest that STAT1, but not STAT3, might also be one of the crucial signal transducers in the development of BSM hyper-responsiveness, which is one of the causes of AHR in asthmatics.

Anti-inflammatory evaluation of Coronopus didymus in the pleurisy and paw oedema models in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Mastrunço (Coronopus didymus--CD) is currently considered as a medicinal specie often used in Brazil, especially in southeast region, for the treatment of several diseases in which pain and inflammation are common. Treatment with the plant can be done by infusion, decoction, or through food. The aim of this study was: to investigate the anti-inflammatory effect of hydroalcoholic extract obtained from the leaves of CD following the traditional procedure.

MATERIALS AND METHODS

The anti-inflammatory activity was determined using mouse of pleurisy and paw oedema models, both process being induced by different flogistic agents such as: carrageenan (Cg), bradykinin (BK), histamine (HIS), substance P (SP), dextran (DEX) or prostaglandin E(2) (PGE(2)). We evaluated the effect of CD (200-600 mg/kg) administered by oral route (p.o.) upon leukocytes migration, myeloperoxidase (MPO), and adenosine-deaminase (ADA) activities and nitric oxide (NO) levels.

RESULTS

CD (200-600 mg/kg) inhibited the leukocytes by 60.0+/-1.42%, neutrophils by 82.75+/-1.29%, MPO by 42.30+/-4.23%, and ADA activities by 57.89+/-1.94%, as well as NO levels by 64.28+/-2.15% in Cg induced pleurisy. CD also inhibited total and differential leukocytes in the pleurisy induced by BK (1.30+/-0.11/0.29+/-0.02), HIS (1.20+/-0.09/0.42+/-0.05) and SP (0.74+/-0.06/0.14+/-0.01). In addition, CD was effective in reducing paw oedema induced by Cg by 72.79+/-1.13%, SP by 68.26.+/-0.78%, BK by 66.66.+/-0.77%, PGE(2) by 53.346.+/-1.18 and DEX by 65.14+/-2.35%.

CONCLUSION

Several mechanisms, including the inhibition of enzymes (MPO and ADA) and mediators (BK, HIS, SP, NO and PGE(2)) release and/or action, appear to account for the anti-inflammatory effect of Coronopus didymus.

Antigen exposure causes activations of signal transducer and activator of transcription 6 (STAT6) and STAT1, but not STAT3, in lungs of sensitized mice

The signal transducer and activator of transcription (STAT) family of molecules play a critical role in the signaling of many cytokines. In addition to STAT6, implication of STAT1 and STAT3 in the pathogenesis of allergic airway diseases has also been suggested. However, there is little information whether or not antigen challenge to sensitized animals causes the in vivo activation of STAT1 and/or STAT3 in the airways. In the present study, the activations of these STAT molecules were monitored in lungs of mice with allergic bronchial asthma. Male BALB/c mice were sensitized and repeatedly challenged with ovalbumin (OA) antigen. Total protein samples of lungs were prepared at ∼1-24 h after the last OA challenge, and western blot analyses for total and tyrosine-phosphorylated STATs (pSTATs) molecules were conducted. In addition to the phosphorylation of STAT6, STAT1 was also phosphorylated in lungs after the inhalation of OA antigen. Both the phosphorylation of STAT6 and STAT1 occurred at the early stage after the antigen exposure. In contrast, no significant increase in the level of pSTAT3 was observed in this mouse model of allergic bronchial asthma. In conclusion, the current findings suggest that STAT6 and STAT1, but not STAT3, might be crucial signal transducers in the pathogenesis of allergic bronchial asthma.

Creation of a long-lifespan ciliated epithelial tissue structure using a 3D collagen scaffold

We describe a method of using a 3D collagen gel scaffold applied at the air-liquid interface to culture dissociated primary tracheal-bronchial ciliated cells into a ciliated epithelial tissue structure (CETS). This 3D collagen gel culture system enables the induction of ciliogenesis and continuously provides support, maintenance, development, differentiation and propagation for the growth of cilia into the CETS. The CETS developed by this system resembles the ciliary metachronal motility and morphological, histological and physiopharmacological characteristics of cells found in native and in vivo ciliated epithelia. The CETS can be sustained for months with a straightforward and simple maintenance protocol. The integrity of the functional ciliary activity of this CETS enables the evaluation of long-term effects of many pulmonary drug candidates without using animals.

Interleukin-4 up-regulates histamine H1 receptors by activation of H1 receptor gene transcription

Histamine plays an important role in allergy mainly through histamine H1 receptor (H1R). Recent studies showed that the H1R level is elevated in allergic conditions, suggesting that this will make the allergic symptoms worse by intensifying H1R-mediated processes. Some cytokines are also involved in allergy, and interleukin-4 (IL-4) has been implicated as an important mediator of allergic inflammation. It is noteworthy that the level of IL-4 is elevated under allergic states. We tested whether IL-4 has a role in up-regulating H1R level by using the cultured human HeLa cell as a model system that expresses both IL-4 receptor and H1R. IL-4 stimulation increased H1R protein levels and H1R mRNA levels. IL-4 also increased H1R promoter activity, but had no effect on H1R mRNA stability, indicating that up-regulation of H1R was due to an increase in H1R mRNA synthesis. IL-4 activated STAT6 (signal transducer and activator of transcription 6) in HeLa cells, and up-regulation of H1R mRNA and activation of STAT6 by IL-4 were inhibited by a specific JAK3 (Janus-activated kinase 3) inhibitor. Stimulation with histamine also up-regulated H1R mRNA, and co-stimulation with histamine and IL-4 elevated H1R mRNA level significantly higher than the stimulation with histamine or IL-4 alone did. These results indicated that IL-4 up-regulated H1R mRNA level through increased transcription of H1R gene via JAK3-STAT6 pathway. The effects of histamine and IL-4 were additive, suggesting that these allergic mediators will work together to up-regulate H1R level, and thus make the allergic symptom worse by intensifying H1R-mediated allergic processes.

Protective effects of allantoin against ovalbumin (OVA)-induced lung inflammation in a murine model of asthma

Asthma is characterized by difficulty in breathing because of the constriction of the smooth muscles of the bronchi, as a result of inflammation. In the present study, we focus on the protective effects of allantoin against ovalbumin (OVA)-induced lung inflammation in a murine allergic model, and assess cytokine release, eosinophilia, and mucus hypersecretion. Allantoin treatment led to significant reduction in the levels of Ig(immunoglobulin)E and T-helper-2-type cytokines, such as IL(interleukin)-4 and IL-5, in bronchoalveolar lavage (BAL) fluid. Airway inflammatory-cell infiltration was remarkably alleviated in allantoin-treated asthma groups, compared with the control group. Moreover, allantoin-treated asthma groups exhibited a marked decrease in cytokine mRNA expression in lung tissues, compared with the control group. The effectiveness of allantoin was similar to that of montelukast, used as a positive control. These results support the utility of allantoin as a protective agent against asthma.

The -590C/TIL4 single-nucleotide polymorphism as a genetic factor of atopic allergy

Elevated IgE levels in individuals with asthma, allergic rhinitis, and atopic dermatitis represents a situation in that increased IL4 production seems to occur because of the genetic component of the disease. In this study, one-hundred two matched-pairs of allergic and non-allergic individuals were phenotyped for total serum IgE level using enzyme-linked immunosorbent assay (ELISA). Atopic status was defined by serum IgE concentration ≥100 IU/mL The -590C/T IL4 (rs2243250) was screened by polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) analysis. An association between the IL4 -590 TT genotype and levels of IgE was confirmed in the study population (ANOVA p=0.017). Furthermore, the IL4 T allele was significantly increased in allergic (0.299) compared with non-allergic subjects (0.172) (OR=2.060, 95% 01 = 1.285-3.301, χ(2) uncorrected p=0.002) at total serum IgE cut-off of 100 IU/mL. A significant relationship between IL4 -590 TT genotype and very high IgE levels (>1000 IU/mL) (OR=3.968, 95% CI = 1.499-10.5, χ(2) uncorrected p=0.01624) was also established. The -590C/T IL4 polymorphism is a potential risk factor to and correlates with atopic allergy.

Interleukin-4 upregulates RhoA protein via an activation of STAT6 in cultured human bronchial smooth muscle cells

Interleukin-4 (IL-4) is believed to play a role in allergic bronchial asthma, and has been suggested to cause hyperresponsiveness of airway smooth muscle. In the present study, the effects of IL-4 on the expression of RhoA protein, a monomeric GTP-binding protein that contributes to the contraction of smooth muscle, were determined in cultured human bronchial smooth muscle cells (hBSMCs). Incubation of hBSMCs with IL-4 (100ng/mL) caused a distinct phosphorylation of signal transducer and activator of transcription 6 (STAT6), a major signal transducer activated by IL-4, indicating that IL-4 is capable of activating signal transduction in the hBSMCs directly. IL-4 also caused a significant increase in the expression level of RhoA protein: the peak of the upregulation of RhoA protein was observed at 12-24h after the IL-4 treatment. Both the phosphorylation of STAT6 and the upregulation of RhoA protein induced by IL-4 were inhibited by the co-incubation with AS1517499, a selective inhibitor of STAT6, in a concentration-dependent fashion. These findings suggest that IL-4 is capable of inducing an upregulation of RhoA via an activation of STAT6 in cultured hBSMCs. The RhoA upregulation induced by IL-4, one of the Th2 cytokines upregulated in the airways of allergic bronchial asthmatics, might result in an augmentation of bronchial smooth muscle contractility, that is one of the causes of airway hyperresponsiveness.

Reduced FcepsilonRI-mediated release of asthma-promoting cytokines and chemokines from human basophils during omalizumab therapy

BACKGROUND

Treating asthmatics with the humanized IgE-scavenging antibody, omalizumab (rhuMAb-E25, Xolair, reduces airways inflammation and asthma symptoms. Previously, omalizumab was shown to cause a dramatic and reversible loss of cell surface high-affinity IgE receptors, FcepsilonRI, from the peripheral blood basophils of asthmatics. The consequences of receptor loss for the FcepsilonRI-mediated synthesis and release of cytokines implicated in allergic asthma have not been examined.

METHODS

Fifteen asthmatic volunteers each received omalizumab for 12 weeks. Peripheral blood basophils were isolated before, during, 2 weeks after and 6 months after omalizumab. Basophils were assayed for the basal and anti-IgE-stimulated release of cytokines, chemokines and histamine. Pooled data were analyzed by repeated measures ANOVA and by paired t tests.

RESULTS

Anti-IgE-stimulated human basophils synthesize and release Th2 cytokines (IL-4, IL-13) and chemokines (IL-8, RANTES). The anti-IgE-stimulated release of IL-4, IL-13 and IL-8 was reduced during omalizumab treatment and returned to pretreatment levels after omalizumab withdrawal. Omalizumab did not alter basophil histamine levels or basal and anti-IgE-stimulated histamine release.

CONCLUSIONS

Omalizumab may reduce asthma symptoms in part by suppressing the FcepsilonRI-mediated production by basophils of Th2 cytokines and selected chemokines. Anti-IgE-stimulated basophil cytokine synthesis appears more sensitive than histamine release to the loss of FcepsilonRI caused by omalizumab treatment.

Esculetin restores mitochondrial dysfunction and reduces allergic asthma features in experimental murine model

We recently showed that IL-4-dependent oxidative stress and mitochondrial dysfunction are associated with allergic asthma. IL-4 also induces a prooxidant enzyme, 15-lipoxygenase, which predominantly expresses in asthmatic bronchial epithelium and degrades mitochondria. Esculetin (6,7-dihydroxy-2H-1-benzopyran-2-one), a plant-derived coumarin and immunomodulator, was found to have potent bronchodilating property in carbachol-induced bronchoconstriction and also reduces mitochondrial dysfunction in neurological diseases. In this study, we evaluated its potential in restoring mitochondrial dysfunction and structural changes and anti-asthma property in a mouse model of experimental asthma. In this study, we found that esculetin treatment reduced airway hyperresponsiveness, Th2 response, lung eotaxin, bronchoalveolar lavage fluid eosinophilia, airway inflammation, and OVA-specific IgE. It also reduced the expression and metabolites of 15-lipoxygenase and lipid peroxidation which is an essential prerequisite for mitochondrial dysfunction. Interestingly, esculetin treatment restored the activity of cytochrome c oxidase of electron transport chain in lung mitochondria and expression of the third subunit of cytochrome c oxidase of electron transport chain in bronchial epithelium. It reduced the cytochrome c level and caspase 9 activity in lung cytosol and restored mitochondrial structural changes and lung ATP levels. In addition, esculetin reduced subepithelial fibrosis and TGF-beta1 levels in the lung. These results suggest that esculetin not only restores mitochondrial dysfunction and structural changes but also alleviates asthmatic features.

Th2 cells as targets for therapeutic intervention in allergic bronchial asthma

Th2 cells play a central role in the pathogenesis of allergic bronchial asthma, since each of their characteristic cytokines such as IL-4, IL-5, IL-9 and IL-13 contributes to hallmarks of this disease, including airway eosinophilia, increased mucus production, production of allergen-specific IgE and development of airway hyper-responsiveness. Therefore, these cells are predisposed as target cells for therapeutic intervention. Experimental approaches targeted Th2-type effector cytokines, Th2-cell recruitment and Th2-cell development. Another strategy uses the immunomodulatory potential of tolerance-inducing cytokines such as IL-10 or of cytokines such as IL-12, IL-18 and IFN-gamma that are able to induce a counterbalancing Th1 immune response.