Design and characterization of Zweimab and Doppelmab, high affinity dual antagonistic anti-TSLP/IL13 bispecific antibodies.

Patients with severe Th2 type asthma often have a steroid resistant phenotype and are prone to acute exacerbations. Current novel therapies have only marginal therapeutic effects. One of the hypotheses for lack of major efficacy in most patients is targeting only one redundant pathway leaving others active. Hence, we have designed and developed novel highly potent bispecific anti-TSLP/IL13 antibodies called Zweimabs (monovalent bispecific) and Doppelmabs (bivalent bispecific) that concurrently inhibits the signaling by these two cytokines.

The Use of Mouse Asthma Models to Successfully Discover and Develop Novel Drugs.

The past 20 years have seen a proliferation of scientific data on the pathophysiology of asthma. Most of these data were generated in mice using tool reagents, gene-deficient or transgenic animals. In contrast, studies on disease pathogenesis in patients are scarce. Previously, a good novel antiasthma target for drug development was one that abrogated asthma in mice when it was knocked out, neutralized or induced asthma when it was overexpressed. This type of approach led to many drug candidates that worked in mice but unfortunately failed in patients, thereby demonstrating that the results of experiments in mice are not always predictive of clinical efficacy. Currently, there is active debate about the use of mouse models in drug discovery. In this review, we summarize the obstacles and challenges faced when using experimental mouse models of asthma in drug discovery. We propose that the initial selection of a novel drug target begins with defining the unmet medical need and specific patient population, followed by a thorough evaluation of available human data, and, only then, well-planned and executed mouse asthma experiments. Using this approach, we argue that mouse models lend support for the target when the models are tailored for the specific asthma patient population, and that targeted, reliable, and predictive mouse models can indeed improve and accelerate the drug discovery process.

Neutralization of both IL-1α/IL-1ß plays a major role in suppressing combined cigarette smoke/virus-induced pulmonary inflammation in mice.

Smoking is an important risk factor for the development of chronic obstructive pulmonary disease (COPD) and viral infections are believed to be major triggers of exacerbations, which periodically lead to a worsening of symptoms. The pro-inflammatory IL-1 family members IL-1α and IL-1ß are increased in COPD patients and might contribute to disease pathology. We investigated whether individual or combined inhibition of these cytokines reduced lung inflammation in cigarette smoke (CS)-exposed and H1N1-infected BALB/c mice. Animals were treated with individual or combined antibodies (Abs) directed against IL-1α, IL-1ß or IL-1R1. Cells in BAL fluid and cytokines/chemokines in lung homogenate were determined. The viral load was investigated. Blocking IL-1α had significant suppressive effects on total cells, neutrophils, and macrophages. Furthermore, it reduced KC levels significantly. Blocking of IL-1ß did not provide significant activity. In primary human bronchial epithelial air-liquid-interface cell cultures infected with H1N1, IL-1α Abs but not IL-1ß Abs reduced levels of TNF-α and IL-6. Concomitant usage of Abs against IL-1α/IL-1ß revealed strong effects in vivo and reduced total cells, neutrophils and macrophages. Additionally, levels of KC, IL-6, TNF-α, MCP-1, MIP-1α and MIP-1ß were significantly reduced and ICAM-1 and MUC5 A/C mRNA expression was attenuated. The viral load decreased significantly upon combined IL-1α/IL-1ß Ab treatment. Blocking the IL-1R1 provided significant effects on total cells, neutrophils and macrophages but was inferior compared to inhibiting both its soluble ligands IL-1α/IL-1ß. Our results suggest that combined inhibition of IL-1α/IL-1ß might be beneficial to reduce CS/H1N1-induced airway inflammation. Moreover, combined targeting of both IL-1α/IL-1ß might be more efficient compared to individual neutralization IL-1α or IL-1ß or inhibition of the IL-1R1.

Tiotropium Attenuates Virus-Induced Pulmonary Inflammation in Cigarette Smoke-Exposed Mice.

Viral infections trigger exacerbations in chronic obstructive pulmonary disease (COPD), and tiotropium, a M3 receptor antagonist, reduces exacerbations in patients by unknown mechanisms. In this report, we investigated whether tiotropium has anti-inflammatory effects in mice exposed to cigarette smoke (CS) and infected with influenza virus A/PR/8/34 (H1N1) or respiratory syncytial virus (RSV) and compared these effects with those of steroid fluticasone and PDE4-inhibitor roflumilast. Mice were exposed to CS; infected with H1N1 or RSV; and treated with tiotropium, fluticasone, or roflumilast. The amount of cells and cytokine levels in the airways, lung function, and viral load was determined. NCI-H292 cells were infected with H1N1 or RSV and treated with the drugs. In CS/H1N1-exposed mice, tiotropium reduced neutrophil and macrophage numbers and levels of interleukin-6 (IL-6) and interferon-γ (IFN-γ) in the airways and improved lung function. In contrast, fluticasone increased the loss of body weight; failed to reduce neutrophil or macrophage numbers; increased IL-6, KC, and tumor necrosis factor-α (TNF-α) in the lungs; and worsened lung function. Treatment with roflumilast reduced macrophage numbers, IL-6, and KC in the lungs but had no effect on neutrophil numbers or lung function. In CS/RSV-exposed mice, treatment with tiotropium, but not fluticasone or roflumilast, reduced neutrophil numbers and IL-6 and TNF-α levels in the lungs. Viral load of H1N1 and RSV was significantly elevated in CS/virus-exposed mice and NCI-H292 cells after fluticasone treatment, whereas tiotropium and roflumilast had no effect. In conclusion, tiotropium has anti-inflammatory effects on CS/virus-induced inflammation in mice that are superior to the effects of roflumilast and fluticasone. This finding might help to explain the observed reduction of exacerbation rates in COPD patients.

BI 1002494, a Novel Potent and Selective Oral Spleen Tyrosine Kinase Inhibitor, Displays Differential Potency in Human Basophils and B Cells.

BI 1002494 [(R)-4-{(R)-1-[7-(3,4,5-trimethoxy-phenyl)-[1,6]napthyridin-5-yloxy]-ethyl}pyrrolidin-2-one] is a novel, potent, and selective spleen tyrosine kinase (SYK) inhibitor with sustained plasma exposure after oral administration in rats, which qualifies this molecule as a good in vitro and in vivo tool compound. BI 1002494 exhibits higher potency in inhibiting high-affinity IgE receptor-mediated mast cell and basophil degranulation (IC50 = 115 nM) compared with B-cell receptor-mediated activation of B cells (IC50 = 810 nM). This may be explained by lower kinase potency when the physiologic ligand B-cell linker was used, suggesting that SYK inhibitors may exhibit differential potency depending on the cell type and the respective signal transduction ligand. A 3-fold decrease in potency was observed in rat basophils (IC50 = 323 nM) compared with human basophils, but a similar species potency shift was not observed in B cells. The lower potency in rat basophils was confirmed in both ex vivo inhibition of bronchoconstriction in precision-cut rat lung slices and in reversal of anaphylaxis-driven airway resistance in rats. The different cellular potencies translated into different in vivo efficacy; full efficacy in a rat ovalbumin model (that contains an element of mast cell dependence) was achieved with a trough plasma concentration of 340 nM, whereas full efficacy in a rat collagen-induced arthritis model (that contains an element of B-cell dependence) was achieved with a trough plasma concentration of 1400 nM. Taken together, these data provide a platform from which different estimates of human efficacious exposures can be made according to the relevant cell type for the indication intended to be treated.

Modeling Pulmonary Disease Pathways Using Recombinant Adeno-Associated Virus 6.2.

Viral vectors have been applied successfully to generate disease-related animal models and to functionally characterize target genes in vivo. However, broader application is still limited by complex vector production, biosafety requirements, and vector-mediated immunogenic responses, possibly interfering with disease-relevant pathways. Here, we describe adeno-associated virus (AAV) variant 6.2 as an ideal vector for lung delivery in mice, overcoming most of the aforementioned limitations. In a proof-of-concept study using AAV6.2 vectors expressing IL-13 and transforming growth factor-ß1 (TGF-ß1), we were able to induce hallmarks of severe asthma and pulmonary fibrosis, respectively. Phenotypic characterization and deep sequencing analysis of the AAV-IL-13 asthma model revealed a characteristic disease signature. Furthermore, suitability of the model for compound testing was also demonstrated by pharmacological intervention studies using an anti-IL-13 antibody and dexamethasone. Similarly, the AAV-TGF-ß1 fibrosis model showed several disease-like pathophenotypes monitored by micro-computed tomography imaging and lung function measurement. Most importantly, analyses using stuffer control vectors demonstrated that in contrast to a common adenovirus-5 vector, AAV6.2 vectors did not induce any measurable inflammation and therefore carry a lower risk of altering relevant readouts. In conclusion, we propose AAV6.2 as an ideal vector system for the functional characterization of target genes in the context of pulmonary diseases in mice.

Tiotropium bromide inhibits relapsing allergic asthma in BALB/c mice.

Recurrent relapses of allergic lung inflammation in asthmatics may lead to airway remodeling and lung damage. We tested the efficacy of tiotropium bromide, a selective long-acting, muscarinic receptor antagonist as an adjunct therapy in relapses of allergic asthma in mice. We compared the effectiveness of local intranasal administration of tiotropium and dexamethasone in acute and relapsing allergic asthma in BALB/c mice. Although tiotropium at low doses is a potent bronchodilator, we tested higher doses to determine effectiveness on inflammation and mucus hypersecretion. A 5-day course of twice daily intranasal tiotropium or dexamethasone (1 mg/kg (b.w.)) suppressed airway eosinophils by over 87% during disease initiation and 88% at relapse compared to vehicle alone. Both drugs were comparable in their capacity to suppress airway and parenchymal inflammation and mucus hypersecretion, though tiotropium was better than dexamethasone at reducing mucus secretion during disease relapse. Despite treatment with either drug, serum antigen-specific IgE or IgG1 antibody titres remained unchanged. Our study indicates that tiotropium at higher doses than required for bronchodilation, effectively suppresses inflammation and mucus hypersecretion in the lungs and airways of mice during the initiation and relapse of asthma. Tiotropium is currently not approved for use in asthma. Clinical studies have to demonstrate the efficacy of tiotropium in this respiratory disease.

Induced Syk deletion leads to suppressed allergic responses but has no effect on neutrophil or monocyte migration in vivo.

The spleen tyrosine kinase (Syk) is a key mediator of immunoreceptor signaling in immune cells. Thus, interfering with the function of Syk by genetic deletion or pharmacological inhibition might influence a variety of allergic and autoimmune processes. Since conventional Syk knockout mice are not viable, studies addressing the effect of Syk deletion in adult animals have been limited. To further explore functions of Syk in animal models of allergy and to shed light on the role of Syk in the in vivo migration of neutrophils and monocytes, we generated inducible Syk knockout mice. These mice harbor a floxed Syk gene and a tamoxifen-inducible Cre recombinase under the control of the ubiquitously active Rosa26-promoter. Thus, treatment of mice with tamoxifen leads to the deletion of Syk in all organs. Syk-deleted mice were analyzed in mast cell-dependent models and in models focusing on neutrophil and monocyte migration. We show that Syk deletion in adult mice reduces inflammatory responses in mast cell-driven animal models of allergy and asthma but has no effect on the migration of neutrophils and monocytes. Therefore, the inducible Syk knockout mice presented here provide a valuable tool to further explore the role of Syk in disease-related animal models.

Treatment of allergic asthma: modulation of Th2 cells and their responses.

Atopic asthma is a chronic inflammatory pulmonary disease characterised by recurrent episodes of wheezy, laboured breathing with an underlying Th2 cell-mediated inflammatory response in the airways. It is currently treated and, more or less, controlled depending on severity, with bronchodilators e.g. long-acting beta agonists and long-acting muscarinic antagonists or anti-inflammatory drugs such as corticosteroids (inhaled or oral), leukotriene modifiers, theophyline and anti-IgE therapy. Unfortunately, none of these treatments are curative and some asthmatic patients do not respond to intense anti-inflammatory therapies. Additionally, the use of long-term oral steroids has many undesired side effects. For this reason, novel and more effective drugs are needed. In this review, we focus on the CD4+ Th2 cells and their products as targets for the development of new drugs to add to the current armamentarium as adjuncts or as potential stand-alone treatments for allergic asthma. We argue that in early disease, the reduction or elimination of allergen-specific Th2 cells will reduce the consequences of repeated allergic inflammatory responses such as lung remodelling without causing generalised immunosuppression.

TLR agonist mediated suppression of allergic responses is associated with increased innate inflammation in the airways.

Toll-like receptor (TLR) mediated signaling induces pro-inflammatory responses and can both suppress and exacerbate allergic responses in the airways. The aim of our study was to directly compare the efficacy of different TLR agonists in inhibiting or exacerbating the development of Th2-mediated responses in the airways and investigate if the suppressive effects were associated with increased pro-inflammatory responses. Mice were immunized on day 0, 14 and 21 by intraperitoneal injection of ovalbumin/alum and exposed to ovalbumin aerosol on day 26 and 27. TLR2, TLR3, TLR4, TLR7 and TLR9 agonists (0.001, 0.01, 0.1, or 1 mg/kg) were administered intratracheally 1 h before each allergen exposure. Both the TLR7 and TLR9 agonists dose dependently reduced airway eosinophilia, while the TLR3 agonist only reduced airway eosinophilia at a dose of 1.0 mg/kg. The TLR2 and TLR4 agonists potentiated eosinophilia. All TLR agonists enhanced neutrophil numbers at doses as low as 0.01 mg/kg, in particular TLR2 and TLR4 agonists. TLR7 and TLR9 agonists also significantly reduced IL-4 and IL-5 levels and all TLR agonists, with the exception of TLR7, enhanced the amount IL-1ß, IL-6, and TNF-α detected in the whole lung lavage. Only application of TLR9 agonist induced detectable levels of IL-10 in the lung. Suppressive effects of the TLR agonists were not dependent upon IFN-γ and IL-10 or associated with increased numbers of Foxp3(+)CD4(+) Tr cells in the lavage fluid. Airway resistance was reduced significantly only when TLR7 agonist was administered. When applied therapeutically 2 days after allergen exposure, all TLR agonists, except TLR2, similarly reduced airway eosinophilia and IL-4 levels. Taken together our results show that TLR7 agonists had the strongest anti-asthmatic effects with the lowest pro-inflammatory potential, suggesting that activating TLR7 may have the greatest potential to treat allergic disorders in humans.

Probiotic Escherichia coli Nissle 1917 suppresses allergen-induced Th2 responses in the airways.

BACKGROUND: Recent clinical trials, epidemiological studies and animal experiments have suggested that probiotics may help suppress the development of allergic responses. OBJECTIVE: To investigate whether the application of the probiotic Escherichia coli strain Nissle 1917 (EcN) protects mice from developing ovalbumin (OVA)-specific T helper-2 responses in the airways. METHODS: OVA-specific Th2 responses were induced by 2 intraperitoneal (i.p.) injections with OVA/alum followed by 1 intranasal (i.n.) challenge with OVA. EcN was given orally during the entire sensitization and challenge period, together with OVA/alum during the i.p. sensitizations, or i.n. before or during the airway challenge with OVA. RESULTS: We found that when the bacteria were given together with OVA/alum airway eosinophilia, airway hyper-reactivity, goblet cell metaplasia and IL-5 levels in the bronchoalveolar lavage and mediastinal lymph node cell cultures were reduced. This effect was associated with increased numbers of IFN-gamma producing T helper-1 cells and IFN-gamma levels in the airways and strongly increased OVA-specific IgG(2a) titers in the serum. The suppressive effect on airway eosinophilia was dependent on IFN-gamma but not TLR-4. Applying EcN i.n. or orally did not reduce the development of allergen-specific Th2 responses. CONCLUSIONS: Our results suggest that EcN can inhibit the development of allergic responses when the bacteria are present at the site of Th2 cell priming and that this immunomodulatory effect is due to a shift from Th2 to Th1 response. The data support the hypothesis that probiotics may help reduce allergic responses and that EcN may also be used as adjuvant therapy to induce allergen-specific Th1 responses.

Novel vaccines protecting against the development of allergic disorders: a double-edged sword?

The severity and incidence of allergic disorders is steadily increasing despite the widespread use of steroids and other drugs. Recent results obtained in animals suggest that it may be possible to develop novel anti-allergy vaccines for human use, thereby stopping this alarming worldwide increase in allergic diseases. The most promising approaches are the induction of allergen-specific T helper 1 or allergen-specific T regulatory responses. However, both approaches potentially harbour negative side effects that need to be ruled out before vaccinating young children -- the best candidates for the primary prevention of allergic disorders.

Sublingual immunotherapy of allergic diseases.

The only disease-modifying treatment that is available for allergic patients is allergen-specific immunotherapy. Two competing application forms are used: subcutaneous immunotherapy, which has been used for > 90 years, and a relatively new immunotherapy where the allergen is applied sublingually. Numerous studies have shown efficacy for subcutaneous immunotherapy and have identified possible mechanisms that are responsible for the observed reduction in allergic responses. In contrast, the efficacy of sublingual immunotherapy has not been documented to the same degree and the responsible immunological mechanisms have not yet been clearly defined. This review focuses on the published clinical and experimental data on sublingual immunotherapy and points at possible mechanisms of how sublingual immunotherapy may differ from subcutaneous immunotherapy in its mode of action, and also discusses the potential advantages and pit falls of both therapies.

Infection with influenza a virus leads to flu antigen-induced cutaneous anaphylaxis in mice.

It is well established, that viral infections may trigger urticaria or allergic asthma; however, as viral infections induce T helper 1 polarized responses, which lead to the inhibition of T helper 2 cell development, the opposite would be plausible. We wanted to investigate how viral infections may mediate allergic symptoms in a mouse model; therefore, we infected BALB/C mice with influenza A virus intranasally. Histologic analyses of lung sections and bronchoalveolar lavages were performed. In addition, cells from the mediastinal lymph nodes were restimulated in vitro to analyze which types of cytokines were induced by the flu infection. Furthermore, flu-specific antibody titers were determined and local anaphylaxis was measured after rechallenge with flu antigen. We found that airways inflammation consisted predominately of macrophages and lymphocytes, whereas only a few eosinophils were observed. interferon-gamma but no interleukin-4 and little interleukin-5 could be detected in the culture supernatants from in vitro restimulated T cells from the draining lymph nodes. The antibody response was characterized by high levels of virus-specific IgG2a, IgG2b, and IgG1 and, surprisingly, low levels of virus-specific IgE antibodies. Interestingly, flu-infected mice developed active and passive cutaneous anaphylaxis after rechallenge with flu-antigen. As the passive cutaneous anaphylaxis reaction persisted over 48 h and was significantly lower after passive transfer of the serum, which was IgE depleted, local anaphylaxis seemed to be mediated predominately by specific IgE antibodies. Taken together, our results demonstrate that mice infected with flu virus develop virus-specific mast cell degranulation in the skin. Our results may also have implications for the pathogenesis of urticaria or other atopic disorders in humans.

The absence of IFN-gamma leads to increased Th2 responses after influenza A virus infection characterized by an increase in CD4+ but not CD8+ T cells producing IL-4 or IL-5 in the lung.

The cytokine IL-4 has been shown to be responsible for the switch of both CD4+ and CD8+ T cells to a Th2 or TC2 functional phenotype in vitro which both secrete IL-4 after stimulation. In contrast the presence of IFN-gamma interferes with the generation of Th2 and TC2 cells in vitro. Furthermore, it is well established that in the absence of IFN-gamma and the presence of IL-4 Th2 cells also develop in vivo. However, little is known about the conditions leading to the generation of TC2 cells in vivo. For this reason we investigated if Th2 and TC2 cells develop in the lung of IFN-gamma deficient mice which were infected with Influenza A virus. Surprisingly, we were only able to detect Th2 but not TC2 cells in the bronchoalveolar fluid and the mediastinal lymphnodes of IFN-gamma deficient mice infected with influenza A virus 1, 2 and 3 weeks by intracellular FACS staining for IL-4 or IL-5. In infected and uninfected wild type mice and uninfected IFN-gamma deficient mice we were not able to detect any Th2 or TC2 cells. These findings suggest that the prerequisites for Th2 and TC2 cell development are different in vivo than in vitro and may also explain why Th2 cells are more readily detected after immunisations or infections than TC2 cells in vivo.

[Heat-killed Mycobacterium bovis-Bacillus Calmette-Guerin prevents experimental respiratory tract eosinophilia in mice]. / Hóvel elölt mycobacterium bovis-Bacillus Calmette-Guerin kezelés gátolja a kísérletes légúti eosinophilia kialakulását egerekben.

INTRODUCTION: The increased prevalence of asthma has become a major public health issue worldwide. It has been proposed that this increase is due to the steady decline of infectious diseases such as tuberculosis. AIM OF THE STUDY: Supporting this view was, the suppressive effect of live Bacillus Calmette-Guerin (BCG) infection on allergen (ovalbumin) induced airway eosinophilia was published previously. METHODS: Next the authors compared the effects of live, heat killed BCG and purified protein derivative of Mycobacterium tuberculosis (PPD) on a murine model of ovalbumin induced airway eosinophilia. RESULTS: The results showed that both live and heat killed BCG, but not PPD strongly suppressed airway eosinophilia. This inhibition was correlated with the reduced number of Th2 cells in the lung. CONCLUSION: Their data support the hypothesis that the application of bacterial antigens may be a safe vaccination method against asthma in the future.

Development of a novel severe triple allergen asthma model in mice which is resistant to dexamethasone and partially resistant to TLR7 and TLR9 agonist treatment.

Severe asthma is characterised by persistent inflammation, hyperreactivity and remodeling of the airways. No efficient treatment is available, this is particularly the case for steroid resistant phenotypes. Our aim therefore was to develop a preclinical model showing characteristics of severe human asthma including steroid insensitivity. Mice were first sensitized with ovalbumin, extracts of cockroach or house dust mite followed by a challenge period of seven weeks. Further to this, an additional group of mice was sensitized with all three allergens and then challenged with allergen alternating weekly between allergens. All three allergens applied separately to the mice induced comparably strong Th2-type airway inflammation, airway hyperreactivity and airway remodeling, which was characterised by fibrosis and increased smooth muscle thickness. In contrast, application of all three allergens together resulted in a greater Th2 response and increased airway hyperreactivity and a stronger albeit not significant remodeling phenotype compared to using HDM or CRA. In this triple allergen model dexamethasone application, during the last 4 weeks of challenge, showed no suppressive effects on any of these parameters in this model. In contrast, both TLR7 agonist resiquimod and TLR9 agonist CpG-ODN reduced allergen-specific IgE, eosinophils, and collagen I in the lungs. The TLR9 agonist also reduced IL-4 and IL-5 whilst increasing IFN-γ and strongly IL-10 levels in the lungs, effects not seen with the TLR7 agonist. However, neither TLR agonist had any effect on airway hyperreactivity and airway smooth muscle mass. In conclusion we have developed a severe asthma model, which is steroid resistant and only partially sensitive to TLR7 and TLR9 agonist treatment. This model may be particular useful to test new potential therapeutics aiming at treating steroid resistant asthma in humans and investigating the underlying mechanisms responsible for steroid insensitivity.

Prerequisites for the pharmaceutical industry to develop and commercialise helminths and helminth-derived product therapy.

During the past 10 years, immunologists, epidemiologists and parasitologists have made many new exciting discoveries in the field of helminth-mediated immune regulation. In addition, many animal experiments have shown that certain helminths or products derived from helminths can protect mice from developing allergic or autoimmune disease. Some clinical trials utilising Trichuris suis or Necator americanus for the treatment of allergic disorders and inflammatory bowel disease have been conducted. The outcomes of these trials suggest that they may be used to treat these disorders. However, to date no helminth therapy is routinely being applied to patients and no helminth-derived product therapy has been developed. In order to bring new drugs to the market and shoulder the enormous costs involved in developing such therapies, pharmaceutical companies need to be involved. However, currently the resources from the pharmaceutical industry devoted to this concept are relatively small and there are good reasons why the industry may have been reluctant to invest in developing these types of therapies. In this review article, the hurdles that must be overcome before the pharmaceutical industry might invest in these novel therapies are outlined.

The absence of mrp4 has no effect on the recruitment of neutrophils and eosinophils into the lung after LPS, cigarette smoke or allergen challenge.

The multidrug resistance protein 4 (Mrp4) is an ATP-binding cassette transporter that is capable of exporting the second messenger cAMP from cells, a process that might regulate cAMP-mediated anti-inflammatory processes. However, using LPS- or cigarette smoke (CS)-inflammation models, we found that neutrophil numbers in the bronchoalveolar lavage fluid (BALF) were similar in Mrp4(-/-) and Mrp4(+/+) mice treated with LPS or CS. Similarly, neutrophil numbers were not reduced in the BALF of LPS-challenged wt mice after treatment with 10 or 30 mg/kg of the Mrp1/4 inhibitor MK571. The absence of Mrp4 also had no impact on the influx of eosinophils or IL-4 and IL-5 levels in the BALF after OVA airway challenge in mice sensitized with OVA/alum. LPS-induced cytokine release in whole blood ex vivo was also not affected by the absence of Mrp4. These data clearly suggest that Mrp4 deficiency alone is not sufficient to reduce inflammatory processes in vivo. We hypothesized that in combination with PDE4 inhibitors, used at suboptimal concentrations, the anti-inflammatory effect would be more pronounced. However, LPS-induced neutrophil recruitment into the lung was no different between Mrp4(-/-) and Mrp4(+/+) mice treated with 3 mg/kg Roflumilast. Finally, the single and combined administration of 10 and 30 mg/kg MK571 and the specific breast cancer resistance protein (BCRP) inhibitor KO143 showed no reduction of LPS-induced TNFα release into the BALF compared to vehicle treated control animals. Similarly, LPS-induced TNFα release in murine whole blood of Mrp4(+/+) or Mrp4(-/-) mice was not reduced by KO143 (1, 10 µM). Thus, BCRP seems not to be able to compensate for the absence or inhibition of Mrp4 in the used models. Taken together, our data suggest that Mrp4 is not essential for the recruitment of neutrophils into the lung after LPS or CS exposure or of eosinophils after allergen exposure.

Can helminths or helminth-derived products be used in humans to prevent or treat allergic diseases?

Recent epidemiological and experimental data indicate that infection with helminths can protect humans from the development of allergic disorders by immunosuppressive mechanisms that involve the induction of IL-10 and/or regulatory T cells. Furthermore, helminth-derived immune modulators suppress allergic responses in mice. Trichuris suis therapy has been shown to be safe and efficacious in treating inflammatory bowel disease in humans. Has the time come to treat patients who have allergic diseases or healthy humans who are at risk of developing these diseases with helminths or helminth-derived products? Here, I discuss the pros and cons of such an approach.