Author’s Accepted Manuscript IκB kinase β inhibitor, IMD-0354, prevents allergic asthma in a mouse model through inhibition of CD4+ effector T cell responses in the lung-draining mediastinal lymph nodes Tomasz Maślanka, Iwona Otrocka-Domagała, Monika Zuśka-Prot, Mateusz Mikiewicz, Jagoda Przybysz, Agnieszka Jasiecka, Jerzy J. Jaroszewski
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S0014-2999(16)30047-4 http://dx.doi.org/10.1016/j.ejphar.2016.02.023 EJP70457
To appear in: European Journal of Pharmacology Received date: 2 October 2015 Revised date: 28 January 2016 Accepted date: 8 February 2016 Cite this article as: Tomasz Maślanka, Iwona Otrocka-Domagała, Monika ZuśkaProt, Mateusz Mikiewicz, Jagoda Przybysz, Agnieszka Jasiecka and Jerzy J. Jaroszewski, IκB kinase β inhibitor, IMD-0354, prevents allergic asthma in a mouse model through inhibition of CD4+ effector T cell responses in the lungdraining mediastinal lymph nodes, European Journal of Pharmacology, http://dx.doi.org/10.1016/j.ejphar.2016.02.023 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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IκB kinase β inhibitor, IMD-0354, prevents allergic asthma in a mouse model through inhibition of CD4+ effector T cell responses in the lung-draining mediastinal lymph nodes Tomasz Maślankaa,*, Iwona Otrocka-Domagałab, Monika Zuśka-Prota, Mateusz Mikiewiczb, Jagoda Przybysza, Agnieszka Jasieckaa, Jerzy J. Jaroszewskia a
Department of Pharmacology and Toxicology, bDepartment of Pathological Anatomy,
Faculty of Veterinary Medicine, University of Warmia and Mazury, Oczapowskiego Street 13, 10-719 Olsztyn, Poland *Corresponding author; e-mail: [email protected] Abstract IκB kinase (IKK) is important for nuclear factor (NF)-κB activation under inflammatory conditions. It has been demonstrated that IMD-0354, i.e. a selective inhibitor of IKKβ, inhibited allergic inflammation in a mouse model of ovalbumin (OVA)-induced asthma. The present study attempts to shed light on the involvement of CD4+ effector (Teff) and regulatory (Treg) T cells in the anti-asthmatic action of IMD-0354. The animals were divided into three groups: vehicle treated, PBS-sensitized/challenged mice (PBS group); vehicle treated, OVAsensitized/challenged mice (OVA group); and IMD-0354-treated, OVA-sensitized/challenged mice. The analyzed parameters included the absolute counts of Treg cells (Foxp3+CD25+CD4+), activated Teff cells (Foxp3-CD25+CD4+) and resting T cells (CD25CD4+) in the mediastinal lymph nodes (MLNs), lungs and peripheral blood. Moreover, lung histopathology was performed to evaluate lung inflammation. It was found that the absolute number of cells in all studied subsets was considerably increased in the MLNs and lungs of mice from OVA group as compared to PBS group. All of these effects were fully prevented by treatment with IMD-0354. Histopathological examination showed that treatment with
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IMD-0354 protected the lungs from OVA-induced allergic airway inflammation. Our results indicate that IMD-0354 exerts anti-asthmatic action, at least partially, by blocking the activation and clonal expansion of CD4+ Teff cells in the MLNs, which, consequently, prevents infiltration of the lungs with activated CD4+ Teff cells. The beneficial effects of IMD-0354 in a mouse model of asthma are not mediated through increased recruitment of Treg cells into the MLNs and lungs and/or local generation of inducible Treg cells. Keywords: Asthma, NF-κB, CD4+ T cells, Treg cells, MLNs, lungs. 1. Introduction Asthma is a heterogeneous disorder defined as a variable and largely reversible airway obstruction usually accompanied by airway hyperreactivity. In general, inhaled glucocorticoids remain the first line treatment for most patients, however, these therapies are not always sufficiently effective and can be associated with undesired side effects and steroid resistance (Edwards et al., 2009). Currently, nuclear factor (NF)-κB is regarded as a promising target for the development of a novel therapeutic strategy in asthma treatment because asthmatic airway inflammation is mediated, at least in part, by NF-κB signaling pathways (Edwards et al., 2009). NF-κB is a transcription factor expressed in numerous cell types and plays a key role in the expression of many pro-inflammatory genes (Hoffmann and Baltimore, 2008). In unstimulated cells, NF-κB is bound to IκB and retained in the cytosol in its inactive form. Phosphorylation of IκB by the IκB kinase (IKK) complex leads to the degradation of this protein, thereby releasing the active form of NF-κB which translocates to the nucleus and up-regulates gene expression (Edwards et al., 2009). Studies by Sugita et al. (2009) showed that IMD-0354, i.e. a selective inhibitor of IKKβ, inhibited allergic inflammation in an acute mouse model of ovalbumin (OVA)-induced asthma. In subsequent studies (Ogawa et al., 2011), these investigators demonstrated, using a mouse model of chronic asthma, that IMD-0354 inhibited the pathological features of airway remodeling.
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The present study attempts to shed light on the involvement of CD4+ effector (Teff) and Foxp3+CD25+CD4+ regulatory (Treg) T cells in the anti-asthmatic action of IMD-0354. CD4+ Teff cells have a central role in the pathogenesis of asthma. Following antigen presentation by dendritic cells to recirculating naïve T cells (Tn) in the mediastinal lymph nodes (MLNs), specific CD4+ T cells are activated and differentiated into Th2 effector type cells, which migrate to the lungs and orchestrate pulmonary immune responses (Lambrecht and Hammad, 2003). Moreover, Foxp3-expressing Treg cells have been discovered as another pivotal subset of CD4+ T cells involved in the pathogenesis of asthma (Provoost et al., 2009; Barczyk et al., 2014). There are numerous indications suggesting that the anti-allergic and anti-inflammatory effects of IKK inhibition in mouse models of asthma may be mediated, in a large part, through controlling the levels of CD4+ Teff and Treg cells in the MLNs and lungs. For example, it has been demonstrated that NF-κB plays a critical role in Th2 differentiation in allergic airway inflammation (Das et al., 2001). A beneficial effect of NF-κB inhibition in a rat model of severe pulmonary arterial hypertension was accompanied by a markedly increased abundance of Treg cells in the lungs (Farkas et al., 2014ab). Therefore, we hypothesized that one of the mechanisms underlying the anti-asthmatic action of IKK inhibitors can be the following effects: (a) preventing an allergen-induced increase in the number of CD4+ Teff cells in the MLNs, (b) inhibition of the recruitment of CD4+ Teff cells into the lungs, and (c) an increase in the number of Treg cells in the lungs and/or MLNs. 2. Materials and methods 2. 1. Animals All of the procedures were approved by the Local Ethics Commission (Ethic permission No. 10/2015). The experiments were carried out on 6-week-old Balb/c mice. Mice were bred and maintained under standard lab conditions [12/12 h light/dark cycle, controlled temperature (21 +/- 2°C) and humidity (55+/- 5%), and ad libitum access to food and water]
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in the Animal Facility of the Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn. 2. 2. IMD-0354 The specificity of IMD-0354 (N-[3,5-bis-trifluoromethyl-phenyl]-5-chloro-2-hydroxybenzamide) and its inhibitory action against IKKβ have been demonstrated previously (Onai et al., 2004; Tanaka et al., 2007). IMD-0354 powder was dissolved in 0.5% carboxymethylcellulose (both from Sigma-Aldrich, Munich, Germany) and administered intraperitoneally (i.p.) at a dose of 20 mg/kg/day for 6 days. This dose was chosen according to our preliminary studies and published reports (Ogawa et al., 2011; Sugita et al., 2009) indicating the anti-asthmatic effect of IMD-0354 at this dosage. 2. 3. Sensitization, challenge, and treatment protocol Mice were divided into three groups, namely PBS group (PBS-sensitized and challenged mice treated with vehicle, i.e. negative control group), OVA group (OVAsensitized and -challenged mice treated with vehicle, i.e. mice with OVA-induced model of allergic asthma), and OVA + IMD-0354 group (OVA-sensitized and -challenged mice treated with IMD-0354). The mice were sensitized on days 0 and 14 via i.p. injection of 20 µg OVA (Grade V) emulsified in 2 mg aluminum hydroxide (both from Sigma-Aldrich) in total volume of 200 µl PBS. On days 21, 22, 23 and 24, mice were challenged intranasally (i.n.) with 100 μg of OVA in 50 µl of PBS. Mice in PBS group received only aluminum hydroxide in PBS (sensitization) or PBS alone (challenge). IMD-0354 or vehicle (0.5% carboxymethylcellulose) administration was started 48 h prior to i.n. challenge (i.e. on day 19 after the initial sensitization) and continued for 5 consecutive days; the test substance or placebo were given 3 h before challenge. Mice were euthanized (by asphyxiation with CO2) 24 h after the last administration. The experimental study design scheme is shown in Fig. 1.
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2. 4. Lung histology Lungs taken during necropsy were fixed in 10% neutral buffered formalin and embedded in paraffin wax. Lung histological sections (3-4 µm) were stained with haematoxylin and eosin (H&E) (Merck, Germany) for detection of inflammatory infiltrates and with periodic acid-Schiff (PAS) (Sigma-Aldrich) for goblet cells and mucus production visualization. Sections were analyzed using a light microscope (Olympus BX51, Japan) with digital camera (ColorView, Olympus, Japan) and Cell^B software (Olympus, Japan). Airway inflammation was quantified in the peribronchial region of 5 different medium-sized bronchi per slide on the basis of a scoring system (Table 1) previously described and used in similar studies (Wittke et al., 2004). The results were averaged and totaled for each mouse, and thereafter, the mean [± standard deviation (S.D.)] score per group was calculated. Epithelial thickness (as the area between the luminal cell membrane and the basement membrane) was measured at 4 sites for 5 different medium-sized bronchi per slide. All measurements were averaged, giving the mean (± S.D.) epithelial thickness per group. 2. 5. Cell recovery 2. 5. 1. MLNs MLNs were removed and subjected to dounce homogenization. The resulting cell suspensions were filtered through nitex fabric (Fairview Fabrics, Hercules, USA), washed with Facs (fluorescence-activated cell-sorting) buffer [FB; Dulbecco's PBS devoid of Ca2+ and Mg2+ with 2% (v/v) heat-inactivated FBS (both from Sigma-Aldrich)], and centrifuged (300 x g for 5 min. at 5˚C; the same parameters were used for all cell-washing procedures). Cells were re-suspended in FB, counted and stained for flow cytometric analysis. 2. 5. 2. Lung samples Lungs obtained from two mice were combined into one sample. Lungs were minced, subjected to dounce homogenization, and washed in incomplete medium (RPMI-1640 + 10
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mM HEPES buffer + 10 U/ml penicillin/streptomycin; all from Sigma-Aldrich)]. Subsequently, lung tissues were digested with 50 U/ml (25 ml per sample) collagenase type IV (Sigma-Aldrich) solution containing DNase I (50 U per ml, Sigma-Aldrich) in a glass 50ml flask containing a magnetic stir bar. Following rapid agitation during digestion at 37˚ C for 90 min., the resulting cell supernatant was removed and filtered through nitex fabric, and the cells were washed in complete medium [CM; RPMI-1640 + 10% heat-inactivated fetal bovine serum + 10 mM HEPES buffer + 10 mM non-essential amino acids + 10 mM sodium pyruvate + 10 U/ml penicillin/streptomycin; all from Sigma-Aldrich]. Isolated cells were resuspended in a 40% percoll solution (Sigma-Aldrich), and then were layered over a 60% percoll solution and subjected to a gradient centrifugation (400 x g for 20 min. at 20˚C). Mononuclear cells were removed from the interface layer, washed and then re-suspended in FB, counted, and stained for flow cytometric analysis. 2. 5. 3. Peripheral blood Blood was drawn from the inferior vena cava into heparinized (for flow cytometry analysis) or EDTA coated [for the complete blood count (CBC)] tubes. Erythrocytes were removed using Red Blood Cell Lysing Buffer (RBCLB) [Na2EDTA (0.37 g) + NH4CL (8 g) + NaHCO3 (0.84 g) + H20 (500 ml); all from Sigma-Aldrich]. The samples (i.e 100 µl of whole blood) were treated with 2 ml of RBCLB, incubated for 7-8 min at 4˚C, and washed twice with 2 ml of FB. The remaining cells were re-suspended in FB and stained for flow cytometric analysis. Routine CBC was performed using a hematology analyzer Advia 2120i (Siemens Healthcare Diagnostics, Erlangen, Germany). 2. 6. Staining for flow cytometry analysis Cells prepared as described above were stained for surface antigens with fluorochrome conjugated monoclonal antibodies (mAbs): FITC rat anti-mouse CD4 (clone H129.19, IgG2a, κ), APC-Cy7 rat anti-mouse CD8a (clone 53-6.7, IgG2a, κ), PE-Cy7 rat anti-mouse CD25
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(clone PC61, IgG1, λ; all from BD Biosciences, San Jose, USA]; cells were stained for CD8 expression to distinguish CD4+CD8- T cells from double positive (i.e. CD4+CD8+) T cells. Following surface staining, cells were washed, fixed with 2% paraformaldehyde, and permeabilized using mouse Foxp3 buffer set (BD Biosciences). For intracellular Foxp3 expression, cells were labeled with PE-conjugated rat anti-mouse Foxp3 mAb (clone: MF23, IgG2b, BD Bioscience). 2. 7. FACS acquisition and analysis Flow cytometry analysis was performed using a FACSCanto II cytometer (BD Biosciences). The data were acquired by FACSDiva version 6.1.3 software (BD Biosciences) and analyzed by FlowJo software (Tree Star Inc., Stanford, USA). The entire volume of each sample was always acquired. Absolute cell counts of lymphocyte subsets (i.e. number of cells from particular subpopulations per μl of blood or per tissue sample) were calculated using the dual platform method: · Blood samples: absolute cell count was determined by calculating the data obtained from CBC by the percentage of particular cell subsets. · MLNs and lung samples: absolute count was determined by calculating the total cell yield from individual samples (cells were counted by using cell counting chamber) by the percentage of particular cell subsets. Fig. 2 presents a gating strategy for flow cytometric data analysis and specifies how the absolute count was calculated for particular cell subsets. 2. 8. Statistical analysis Data were expressed as the mean (± S.D.) for 8 mice/sample per group. Statistical analysis was done using one-way analysis of variance (ANOVA) followed by Bonferroni's post hoc test. Differences were deemed significant when the P values were < 0.05. SigmaPlot
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Software Version 12.0 (Systat Software Inc., San Jose, USA) was used for statistical analysis and plotting graphs. 3. Results 3. 1. Histopathology Mice were primed and challenged with OVA to induce a model of allergic asthma. The scoring system was used for quantification of histopathological changes in the lungs. The mean scores for OVA group (7.90 ± 1.24) were significantly increased (P < 0.001) compared to PBS (0.53 ± 0.56) and OVA + IMD-0354 groups (1.50 ± 1.75) (Fig. 3A). There were no significant differences between the last two groups (Fig. 3A). All mice in OVA group developed features characteristic for asthmatic inflammation (Fig. 3C). The influx of inflammatory cells occurred around the bronchi and bronchioles; the invading cells were composed mainly of eosinophils (Fig. 3C, H&E). There was observed goblet cell hyperplasia and mucus hypersecretion (Fig. 3C, PAS). In contrast, there was no airway inflammation in PBS and OVA + IMD-0354 groups (Fig. 3C), with the exception of one mouse from the IMD-0354-treated group, which showed very little inflammation. Quantitative assessment of epithelial thickness demonstrated a significant increase (P < 0.001) in epithelial thickening in OVA group (24.17 ± 6.76) compared to PBS group (11.37 ± 2.59) and to OVA + IMD-0354 group (12.16 ± 4.24) (Fig. 3B). Epithelial thickness did not differ significantly between the PBS and OVA + IMD-0354 groups (Fig. 3B). 3. 2. The effect of IMD-0354 on the absolute counts of CD4+ T cell subsets in MLNs The conducted studies demonstrated that immunization with OVA induced a significant increase (P < 0.001) in the number of Foxp3+CD25+CD4+ (Fig. 4A), Foxp3-CD25+CD4+ (Fig. 4B) and CD25-CD4+ (Fig. 4C) T cells in the MLNs of vehicle treated mice (OVA group) compared to PBS and OVA + IMD-0354 groups. The number of these cell subsets was more than 4-, 3-, and 4-fold greater in OVA group, respectively, relative to PBS group. Significant
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differences were not found between PBS and OVA + IMD-0354 groups with respect to the absolute counts of Foxp3+CD25+CD4+ (Fig. 4A), Foxp3-CD25+CD4+ (Fig. 4B) and CD25CD4+ (Fig. 4C) T cells in the MLNs. 3. 3. The effect of IMD-0354 on the absolute counts of CD4+ T cell subsets in the lungs Similar to observations in the MLNs, the absolute number of Foxp3+CD25+CD4+ (Fig. 5A), Foxp3-CD25+CD4+ (Fig. 5B) and CD25-CD4+ (Fig. 5C) T cells was considerably increased (P < 0.001) in the lungs of mice from OVA group compared to PBS and OVA + IMD-0354 groups. The absolute count of these cell subsets in OVA group was significantly elevated by about 19-, 5-, and 7-fold, respectively, relative to PBS group. The absolute number of Foxp3+CD25+CD4+ (Fig. 5A), Foxp3-CD25+CD4+ (Fig. 5B) and CD25-CD4+ (Fig. 5C) T cells did not differ significantly between PBS and OVA + IMD-0354 groups. 3. 4. The effect of IMD-0354 on the absolute counts of CD4+ T cell subsets in peripheral blood The present studies did not reveal any effect of OVA or IMD-0354 exposures on the absolute counts of Foxp3+CD25+CD4+ (Fig. 6A) and CD25-CD4+ (Fig. 6C) T cells in peripheral blood. In OVA group, the absolute number of Foxp3-CD25+CD4+ T cells was considerably elevated (P < 0.001) compared to PBS group (Fig. 6B). The absolute count of cells from this subset in mice treated with IMD-0354 was not different from that in PBS group (Fig. 6B). 4. Discussion Glucocorticoid resistance presents a profound management problem in patients with asthma because conventional therapies are not effective (Adcock et al., 2008). Treatment of patients with steroid-resistant asthma will require novel therapies tailored to this specific subgroup of patients. NF-κB is an attractive and important therapeutic target for the treatment of asthma. This notion is supported by the fact that several lines of evidence indicate
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increased NF-κB pathway activation in the airway tissues of asthmatic subjects; increased activation of NF-κB has been demonstrated in the airway epithelium of human asthmatics (Hart et al., 1998; Zhao et al., 2001) and in the lungs of animal models of asthma (Bureau et al., 2000; Lin et al., 2000; Poynter et al., 2002). IKKβ, but not IKKα, plays a crucial role in NF-κB activation (Edwards et al., 2009; Hoffmann and Baltimore, 2006), and therefore its inhibition is considered an attractive target for the development of novel anti-asthmatic agents. Sugita et al. (2009) and Ogawa et al. (2011) demonstrated that inhibition of IKKβ with IMD-0354 led to a significant reduction in inflammatory cell infiltration and mucus production in lung tissues of OVA-sensitized/challenged mice. Moreover, other research found that treatment with IKKβ inhibitor (Compound A) efficiently reduced the number of eosinophils and neutrophils in bronchoalveolar lavage fluid of rats with OVA-induced allergic airway inflammation (Ziegelbauer et al., 2005). In the present studies, analysis of the lung tissue by the scoring system indicated that treatment with IMD-0354 prevented OVA-induced allergic airway inflammation. Thus, our results confirm the conclusions of the above-cited studies that IMD-0354 may be therapeutically beneficial for treating airway inflammation in asthma. However, the present research aimed to explore the involvement of CD4+ Teff and Treg cells in the anti-asthmatic action of IMD-0354. It should be clarified that CD25 is α chain of the IL-2 receptor that is expressed on Treg cells and activated T and B lymphocytes, whereas Foxp3 is a unique marker and a “master” regulator of the development and suppressive function of Treg cells (Fontenot et al., 2003). Foxp3 currently represents the most specific marker used to distinguish Treg cells (Foxp3+CD25+CD4+) from activated Teff cells (Foxp3-CD25+CD4+); the CD25-CD4+ phenotype represents resting cells, i.e. Tn, effector memory (Tem) and central memory (Tcm) T cells (Sondel et al., 2003). In the OVA-induced asthma model, apart from Th2 cells [the primary Teff cells in asthmatic patients (Lambrecht
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and Hammad, 2003)], other CD4+ Teff cell subsets, such as Th17 [very important in the pathogenesis of asthma (Park and Lee, 2010)] and Th1 (their role in asthma is still uncertain), occur in the MLNs and lungs (Lee et al., 2013). The present studies have demonstrated that the amount of activated CD4+ Teff and resting T cells in the MLNs and lungs of mice with OVA-induced allergic asthma was several fold higher compared to healthy control mice. All of these effects were fully prevented by the treatment with IMD-0354. It is intriguing that in the lungs of untreated mice with OVA-induced asthma, similar to normal lungs, CD25-CD4+ T cells, but not activated Teff cells, were the predominant subset, which is in agreement with results reported by Pastva et al. (2011). They found 24 h after the third challenge with OVA that the majority of lung CD4+ T lymphocytes were naïve and memory cells. Moreover, although numerous reviews and textbooks state that Tn cells do not normally enter nonlymphoid organs, several studies have demonstrated that as part of the normal migratory pathway, these cells enter non-lymphoid organs including the lungs (Cose et al., 2006; Luettig et al., 2001; Westermann et al., 2001). Therefore, OVA-induced increases in CD25-CD4+ T cells observed in the present studies can be interpreted as infiltration of the lungs with Tn and Tem cells. Taking all of the above into consideration, it can be stated that IMD-0354 exerts anti-asthmatic effects, at least partially, by preventing the activation and clonal expansion of CD4+ Teff cells in the MLNs. This conclusion is supported by reports indicating that IKK inhibitors, including IMD-0354, exert anti-proliferative action on T cells (Min et al., 2013; Tanaka et al., 2007; Ziegelbauer et al., 2005). Furthermore, it has been demonstrated that NFκB plays critical roles in Th2 differentiation in allergic airway inflammation (Das et al., 2001). Kimura et al. (2007) found an enhanced ability of CD4+ T cell with up-regulated NFκB activation to differentiate into Th2 cells. Our hypothesis presumed that one of the mechanisms responsible for anti-asthmatic action of IMD-0354 might be prevention of the recruitment of activated CD4+ Teff cells into
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the lungs. This hypothesis was supported by the fact that activation of NF-κB contributes to the production of Th2-attracting chemokines [i.e. thymus and activation-regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22)], which play a key role in controlling the trafficking of Th2 cells into the lung during allergic inflammation (Jeong et al., 2010; Kwon et al., 2012; Nakayama et al., 2004). It was found that the inhibition of NFκB activation was associated with the suppression of TARC/CCL17 and MDC/CCL22 production (Jeong et al., 2010; Kwon et al., 2012), which suggests that IKK inhibitors may impair/block recruitment of Th2 cells into the lungs. Our studies show that treatment with IMD-0354 prevented infiltration of the lungs with activated CD4+ Teff cells. However, this effect was probably not a result of the direct influence of IMD-0354 on lymphocyte trafficking and homing into the lungs but was secondary in character, i.e. it was a consequence of its effect on the MLNs. As the OVA-induced increase in the number of activated CD4+ Teff in the MLNs was abolished by IMD-0354 treatment, there were not Teff cells available for recruitment into the lungs. This conclusion is supported by the fact that IMD-0354 prevented the OVA-induced increase in the number of activated CD4+ Teff cells in peripheral blood, which apparently reflected the trafficking of these cells from the MLNs into the lungs. On the other hand, our results strongly suggest that IMD-0354 prevented infiltration of the lungs with Tn cells (the majority of CD4+CD25- T lymphocytes represent cells in the naïve stage), but the importance of this effect is not clear. Foxp3+CD25+CD4+ Treg cells have been strongly associated with suppression of immune responses in animal models of asthma including the OVA-induced asthma (Kearley et al., 2005, 2008; Leech et al., 2007). It was demonstrated that the beneficial effect of NF-κB inhibition in a rat model of severe pulmonary arterial hypertension was accompanied by a markedly increased abundance of Treg cells in the lungs (Farkas et al., 2014ab), and the antiarthritic action of IKK inhibitor was associated with an increase in the number of Treg cells in
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the draining inguinal lymph nodes and joints (Min et al., 2013). Therefore, taking all the above into consideration, the hypothesis was formulated that anti-asthmatic effect of pharmacological inhibition of NF-κB signaling may be also associated with the expansion and/or accumulation of Treg cells in the lungs and/or MLNs. However, we found that in mice treated with IMD-0354 the number of Treg cells in any of the examined compartments did not differ significantly from that in the healthy controls, while in the lungs and MLNs of mice with asthma, their count was increased by approximately 20- and 4-fold, respectively, compared to control values. The last finding was not surprising and is consistent with two other related studies. Olsen et al. (2015) revealed that OVA challenge resulted in a comparable increase in the absolute number of Treg cells in the lungs. Other investigators (Leech et al., 2007) demonstrated that the resolution of allergic airway inflammation was mediated by Treg cells; they found that upon airway challenge of Der p1-sensitized mice, Treg cells migrated into both lungs and MLNs and peaked in number at 4 days after challenge, i.e. just before the start of resolution of disease markers. Recapitulating, our results indicate that the anti-allergic and anti-inflammatory actions of IMD-0354 are not mediated through increased recruitment of Treg cells into the MLNs and lungs and/or local generation of inducible Treg cells. 5. Conclusions Our results indicate that IMD-0354 exerts anti-asthmatic action, at least partially, by blocking the activation and clonal expansion of CD4+ Teff cells in the MLNs which, in consequence, prevents infiltration of the lungs with activated CD4+ Teff cells. The beneficial effects of IMD-0354 in a mouse model of asthma are not mediated through increased recruitment of Treg cells into the MLNs and lungs and/or local generation of inducible Treg cells. Acknowledgments
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The study was supported by the grant No. 15.610.008-300 from the University of Warmia and Mazury in Olsztyn. References Adcock, I.M., Ford, P.A., Bhavsar, P., Ahmad, T., Chung, K.F., 2008. Steroid resistance in asthma: mechanisms and treatment options. Curr. Allergy Asthma Rep. 8, 171-178. Barczyk, A., Pierzchala, W., Caramori, G., Wiaderkiewicz, R., Kaminski, M., Barnes, P.J., Adcock, I.M., 2014. Decreased percentage of CD4+Foxp3+TGF-β+ and increased percentage of CD4+IL-17+ cells in bronchoalveolar lavage of asthmatics. J. Inflamm. 11:22. Bureau, F., Delhalle, S., Bonizzi, G., Fievez, L., Dogne, S., Kirschvink, N., Vanderplasschen, A., Merville, M.P., Bours, V., Lekeux, P., 2000. Mechanisms of persistent NF-kappa B activity in the bronchi of an animal model of asthma. J. Immunol. 165, 5822-5830. Cose, S., Brammer, C., Khanna, K.M., Masopust, D., Lefrancois, L., 2006. Evidence that a significant number of naive T cells enter non-lymphoid organs as part of a normal migratory pathway. Eur. J. Immunol. 36, 1423-1433. Das, J., Chen, C.H., Yang, L., Cohn, L., Ray, P., Ray, A., 2001. A critical role for NF-kappa B in GATA3 expression and TH2 differentiation in allergic airway inflammation. Nat. Immunol. 2, 45-50. Edwards, M.R., Bartlett, N.W., Clarke, D., Birrell, M., Belvisi, M., Johnston, S.L., 2009. Targeting the NF-kappaB pathway in asthma and chronic obstructive pulmonary disease. Pharmacol. Ther. 121, 1-13. Farkas, D., Alhussaini, A.A., Kraskauskas, D., Kraskauskiene, V., Cool, C.D., Nicolls, M.R., Natarajan, R., Farkas, L., 2014a. Nuclear factor κB inhibition reduces lung vascular lumen obliteration in severe pulmonary hypertension in rats. Am. J. Respir. Cell Mol. Biol. 51, 413-525.
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Farkas, D., Kraskauskas, D., Kraskauskiene, V., Voelkel, N.F., Fowler, A.A., Natarajan, R., Nicolls, M.R., Farkas, L., 2014b. Inhibition of NF-κB improves immune regulation in the SU5416 and chronic hypoxia model of severe obliterative PAH. Am. J. Respir. Cell Mol. Biol. 189 (Abstract Issue), A3347. Fontenot, J.D., Gavin, M.A., Rudensky, A.Y., 2003. Foxp3 programs the development and function of CD4+CD25+ regulatory T cells. Nat. Immunol., 4, 330-336. Hart, L.A., Krishnan, V.L., Adcock, I.M., Barnes, P.J., Chung K.F., 1998. Activation and localization of transcription factor, nuclear factor-kappaB, in asthma. Am. J. Respir. Crit. Care Med. 158, 1585-1592. Hoffmann, A., Baltimore, D., 2006. Circuitry of nuclear factor kappaB signaling. Immunol. Rev. 210, 171-186. Jeong, S.I., Choi, B.M., Jang, S.I., 2010. Sulforaphane suppresses TARC/CCL17 and MDC/CCL22 expression through heme oxygenase-1 and NF-κB in human keratinocytes. Arch. Pharm. Res. 33, 1867-1876. Kearley, J., Robinson, D.S., Lloyd, C.M., 2008. CD4+CD25+ regulatory T cells reverse established allergic airway inflammation and prevent airway remodeling. J. Allergy Clin. Immunol. 122, 617-624. Kearley, J., Barker, J.E., Robinson, D.S., Lloyd, C.M., 2005. Resolution of airway inflammation and hyperreactivity after in vivo transfer of CD4+CD25+ regulatory T cells is interleukin 10 dependent. J. Exp. Med. 202, 1539-1547. Kimura, M.Y., Iwamura, C., Suzuki, A., Miki, T., Hasegawa, A., Sugaya, K., Yamashita, M., Ishii, S., Nakayama, T., 2007. Schnurri-2 controls memory Th1 and Th2 cell numbers in vivo. J. Immunol. 178, 4926-4936. Kwon, D.J., Bae, Y.S., Ju, S.M., Goh, A.R., Youn, G.S., Choi, S.Y., Park, J., 2012. Casuarinin suppresses TARC/CCL17 and MDC/CCL22 production via blockade of NF-
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κB and STAT1 activation in HaCaT cells. Biochem. Biophys. Res. Commun. 417, 12541259. Lambrecht, B.N., Hammad, H., 2003. Taking our breath away: dendritic cells in the pathogenesis of asthma. Nat. Rev. Immunol. 3, 994-1003. Lee, C.C., Lai, Y.T., Chang, H.T., Liao, J.W., Shyu, W.C., Li, C.Y., Wang, C.N., 2013. Inhibition of high-mobility group box 1 in lung reduced airway inflammation and remodeling in a mouse model of chronic asthma. Biochem. Pharmacol. 86, 940-949. Leech, M.D., Benson, R.A., De Vries, A., Fitch, P.M., Howie, S.E., 2007. Resolution of Der p1-induced allergic airway inflammation is dependent on CD4+CD25+Foxp3+ regulatory cells. J. Immunol. 179, 7050-7058. Lin, C.C., Lin, C.Y, Ma, H.Y., (2000) Pulmonary function changes and increased Th-2 cytokine expression and nuclear factor kB activation in the lung after sensitization and allergen challenge in brown Norway rats. Immunol. Lett. 73, 57-64. Luettig, B., Kaiser, M., Bode, U., Bell, E.B., Sparshott, S.M., Bette, M., Westermann, J., 2001. Naive and memory T cells migrate in comparable numbers through the normal rat lung: only effector T cells accumulate and proliferate in the lamina propria of the bronchi. Am. J. Respir. Cell Mol. Biol. 25, 69-77. Min, S.Y., Yan, M., Du, Y., Wu, T., Khobahy, E., Kwon, S.R., Taneja, V., Bashmakov, A., Nukala, S., Ye, Y., Orme, J., Sajitharan, D., Kim, H.Y., Mohan, C., 2013. Intra-articular nuclear factor-κB blockade ameliorates collagen-induced arthritis in mice by eliciting regulatory T cells and macrophages. Clin. Exp. Immunol. 172, 217-227. Nakayama, T., Hieshima, K., Nagakubo, D., Sato, E., Nakayama, M., Kawa, K., Yoshie, O., 2004. Selective induction of Th2-attracting chemokines CCL17 and CCL22 in human B cells by latent membrane protein 1 of Epstein-Barr virus. J. Virol. 78, 1665-1674.
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Ogawa, H., Azuma, M., Muto, S., Nishioka, Y., Honjo, A., Tezuka, T., Uehara, H., Izumi, K., Itai, A., Sone, S., 2011. IκB kinase β inhibitor IMD-0354 suppresses airway remodelling in a Dermatophagoides pteronyssinus-sensitized mouse model of chronic asthma. Clin. Exp. Allergy 41, 104-115. Olsen, P.C., Kitoko, J.Z., Ferreira, T.P., de-Azevedo, C.T., Arantes, A.C,. Martins, ΜA., 2015. Glucocorticoids decrease Treg cell numbers in lungs of allergic mice. Eur. J. Pharmacol. 747, 52-58. Onai, Y., Suzuki, J., Kakuta, T., Maejima, Y., Haraguchi, G., Fukasawa, H., Muto, S., Itai, A., Isobe, M., 2004. Inhibition of IkappaB phosphorylation in cardiomyocytes attenuates myocardial ischemia/reperfusion injury. Cardiovasc. Res. 63, 51-59. Park, S.J., Lee, Y.C., 2010. Interleukin-17 regulation: an attractive therapeutic approach for asthma. Respir. Res. 11:78. Pastva, A.M., Mukherjee, S., Giamberardino, C., Hsia, B., Lo, B., Sempowski, G.D., Wright J.R., 2011. Lung effector memory and activated CD4+ T cells display enhanced proliferation in surfactant protein A-deficient mice during allergen-mediated inflammation. J. Immunol. 186, 2842-2849. Provoost, S., Maes, T., van Durme, Y.M., Gevaert, P., Bachert, C., Schmidt-Weber, C.B., Brusselle, G.G., Joos, G.F., Tournoy, K.G., 2009. Decreased FOXP3 protein expression in patients with asthma. Allergy 64, 1539-1546. Poynter, M.E., Irvin, C.G., Janssen-Heininger, Y.M., 2002. Rapid activation of nuclear factorkappaB in airway epithelium in a murine model of allergic airway inflammation. Am. J. Pathol. 160, 1325-1334. Sondel, P.M., Buhtoiarov, I.N., DeSantes, K., 2003. Pleasant memories: remembering immune protection while forgetting about graft-versus-host disease. J. Clin. Invest. 112, 25-27.
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Sugita, A., Ogawa, H., Azuma, M., Muto, S., Honjo, A., Yanagawa, H., Nishioka, Y., Tani, K., Itai, A., Sone, S., 2009. Antiallergic and anti-inflammatory effects of a novel I kappaB kinase beta inhibitor, IMD-0354, in a mouse model of allergic inflammation. Int. Arch. Allergy Immunol. 148, 186-198. Tanaka, A., Muto, S., Jung, K., Itai, A., Matsuda, H., 2007. Topical application with a new NF-kappaB inhibitor improves atopic dermatitis in NC/NgaTnd mice. J. Invest. Dermatol. 127, 855-863. Westermann, J., Ehlers, E.M., Exton, M.S., Kaiser, M., Bode, U., 2001. Migration of naive, effector and memory T cells: implications for the regulation of immune responses. Immunol. Rev. 184, 20-37. Wittke, A., Weaver, V., Mahon, B.D., August, A., Cantorna, M.T., 2004. Vitamin D receptordeficient mice fail to develop experimental allergic asthma. J. Immunol. 2004, 173, 34323436. Zhao, S., Qi, Y., Liu, X., Jiang, Q., Liu, S., Jiang, Y., Jiang, Z., 2001. Activation of NF-kappa B in bronchial epithelial cells from children with asthma. Chin. Med. J. (Engl.) 114, 909911. Ziegelbauer, K., Gantner, F., Lukacs, N.W., Berlin, A., Fuchikami, K., Niki, T., Sakai, K., Inbe, H., Takeshita, K., Ishimori, M., Komura, H., Murata, T., Lowinger, T., Bacon, K.B., 2005. A selective novel low-molecular-weight inhibitor of IkappaB kinase-beta (IKK-beta) prevents pulmonary inflammation and shows broad anti-inflammatory activity. Br. J. Pharmacol. 145, 178-192. Conflict of interest statement The authors declare that they have no conflict of interests. Figure captions
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Fig. 1. Experimental study design scheme. Mice were sensitized to ovalbumin (OVA) by two intraperitoneal (i.p.) injections on days 0 and 14 with OVA absorbed on aluminum hydroxide. Subsequently, mice were challenged intranasally with OVA (OVA and OVA + IMD-0354 groups) on days 21, 22, 23, and 24. Mice in the negative control group (PBS group) received only aluminum hydroxide in PBS (sensitization) or PBS alone (challenge). Different groups of mice were treated i.p. with vehicle (PBS and OVA groups) or IMD-0354 (OVA + IMD0354 group). Fig. 2. Gating strategy for flow cytometric data analysis and calculation of the absolute cell counts of lymphocyte subsets. Lymphocytes were identified based on forward and side scatter (FSC/SSC) properties and then gated for expression of CD4 and CD8 surface receptors. Relative to the presence of CD25 expression, the CD4+ T cell population was subdivided into CD25- and CD25+ cell subsets. CD25+CD4+ T cells were analyzed for Foxp3 expression. Absolute cell counts of lymphocyte subsets (i.e. number of cells from particular subpopulations per μl of blood or per tissue sample) were calculated using the dual platform method, as shown above. Fig. 3. Quantitative assessment of allergic airway inflammation and treatment efficacy. Mean histology scores of airway inflammation (A) and mean epithelial thickness (B). Results are expressed as the mean (± S.D.) of two independent experiments with 4 animals per group (n = 8 per group, *P < 0.001, one-way ANOVA with the Bonferroni post hoc test). Examples of photomicrographs of tissue sections stained with haematoxilin/eosin (H&E) and periodic acid-Schiff (PAS) (C). Densely infiltrated eosinophils and lymphocytes (enlargement of rectangle in upper photograph) with mucous hypersecretion are visible in lung sections of vehicle-treated, ovalbumin-immunized mouse (OVA group), while there are not histopathological abnormalities in sections of non-immunized mouse (PBS group) and IMD-
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0354-treated, OVA-immunized mouse (OVA + IMD-0354 group). Magnification: 20-fold; 100-fold for the insert. Fig. 4. The effect of IMD-0354 on the absolute counts of Foxp3+CD25+CD4+ (A) Foxp3CD25+CD4+ (B) and CD25-CD4+ (C) T cells in the mediastinal lymph nodes (MLNs) of nonimmunized mice (PBS group), vehicle-treated, ovalbumin-immunized mice (OVA group) and IMD-0354-treated, OVA-immunized mice (OVA + IMD-0354 group). The absolute count represents the number of cells of each subset per MLN sample. Results are expressed as the mean (± S.D.) of two independent experiments with 4 mice per group (n = 8 per group, *P < 0.001, one-way ANOVA with the Bonferroni post hoc test). Fig. 5. The effect of IMD-0354 on the absolute counts of Foxp3+CD25+CD4+ (A) Foxp3CD25+CD4+ (B) and CD25-CD4+ (C) T cells in the lungs of non-immunized mice (PBS group), vehicle-treated, ovalbumin-immunized mice (OVA group) and IMD-0354-treated, OVA-immunized mice (OVA + IMD-0354 group). The absolute count represents the number of cells of each subset per lung sample pooled from 2 animals. Results are expressed as the mean (± S.D.) of two independent experiments involving 4 lung samples per group (n = 8 per group, *P < 0.001, one-way ANOVA with the Bonferroni post hoc test). Fig. 6. The effect of IMD-0354 on the absolute counts of Foxp3+CD25+CD4+ (A), Foxp3CD25+CD4+ (B) and CD25-CD4+ (C) T cells in peripheral blood of non-immunized mice (PBS group), vehicle-treated, ovalbumin-immunized mice (OVA group) and IMD-0354treated, OVA-immunized mice (OVA + IMD-0354 group). The absolute count represents the number of cells of each subset per µl of blood. Results are expressed as the mean (± S.D.) of two independent experiments, each with 4 animals per group (n = 8 per group, *P < 0.001, one-way ANOVA with the Bonferroni post hoc test).
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 1
Table 1
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Table 1. The scoring system used for evaluation of airway inflammation (Wittke et al., 2004)
Category
Criterion of evaluation
Points assigned per criterion
Inflammation
no inflammation
0
minimal: inflammatory cells present
1
mild: a few (
PII: DOI: Reference:
www.elsevier.com/locate/ejphar
S0014-2999(16)30047-4 http://dx.doi.org/10.1016/j.ejphar.2016.02.023 EJP70457
To appear in: European Journal of Pharmacology Received date: 2 October 2015 Revised date: 28 January 2016 Accepted date: 8 February 2016 Cite this article as: Tomasz Maślanka, Iwona Otrocka-Domagała, Monika ZuśkaProt, Mateusz Mikiewicz, Jagoda Przybysz, Agnieszka Jasiecka and Jerzy J. Jaroszewski, IκB kinase β inhibitor, IMD-0354, prevents allergic asthma in a mouse model through inhibition of CD4+ effector T cell responses in the lungdraining mediastinal lymph nodes, European Journal of Pharmacology, http://dx.doi.org/10.1016/j.ejphar.2016.02.023 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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IκB kinase β inhibitor, IMD-0354, prevents allergic asthma in a mouse model through inhibition of CD4+ effector T cell responses in the lung-draining mediastinal lymph nodes Tomasz Maślankaa,*, Iwona Otrocka-Domagałab, Monika Zuśka-Prota, Mateusz Mikiewiczb, Jagoda Przybysza, Agnieszka Jasieckaa, Jerzy J. Jaroszewskia a
Department of Pharmacology and Toxicology, bDepartment of Pathological Anatomy,
Faculty of Veterinary Medicine, University of Warmia and Mazury, Oczapowskiego Street 13, 10-719 Olsztyn, Poland *Corresponding author; e-mail: [email protected] Abstract IκB kinase (IKK) is important for nuclear factor (NF)-κB activation under inflammatory conditions. It has been demonstrated that IMD-0354, i.e. a selective inhibitor of IKKβ, inhibited allergic inflammation in a mouse model of ovalbumin (OVA)-induced asthma. The present study attempts to shed light on the involvement of CD4+ effector (Teff) and regulatory (Treg) T cells in the anti-asthmatic action of IMD-0354. The animals were divided into three groups: vehicle treated, PBS-sensitized/challenged mice (PBS group); vehicle treated, OVAsensitized/challenged mice (OVA group); and IMD-0354-treated, OVA-sensitized/challenged mice. The analyzed parameters included the absolute counts of Treg cells (Foxp3+CD25+CD4+), activated Teff cells (Foxp3-CD25+CD4+) and resting T cells (CD25CD4+) in the mediastinal lymph nodes (MLNs), lungs and peripheral blood. Moreover, lung histopathology was performed to evaluate lung inflammation. It was found that the absolute number of cells in all studied subsets was considerably increased in the MLNs and lungs of mice from OVA group as compared to PBS group. All of these effects were fully prevented by treatment with IMD-0354. Histopathological examination showed that treatment with
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IMD-0354 protected the lungs from OVA-induced allergic airway inflammation. Our results indicate that IMD-0354 exerts anti-asthmatic action, at least partially, by blocking the activation and clonal expansion of CD4+ Teff cells in the MLNs, which, consequently, prevents infiltration of the lungs with activated CD4+ Teff cells. The beneficial effects of IMD-0354 in a mouse model of asthma are not mediated through increased recruitment of Treg cells into the MLNs and lungs and/or local generation of inducible Treg cells. Keywords: Asthma, NF-κB, CD4+ T cells, Treg cells, MLNs, lungs. 1. Introduction Asthma is a heterogeneous disorder defined as a variable and largely reversible airway obstruction usually accompanied by airway hyperreactivity. In general, inhaled glucocorticoids remain the first line treatment for most patients, however, these therapies are not always sufficiently effective and can be associated with undesired side effects and steroid resistance (Edwards et al., 2009). Currently, nuclear factor (NF)-κB is regarded as a promising target for the development of a novel therapeutic strategy in asthma treatment because asthmatic airway inflammation is mediated, at least in part, by NF-κB signaling pathways (Edwards et al., 2009). NF-κB is a transcription factor expressed in numerous cell types and plays a key role in the expression of many pro-inflammatory genes (Hoffmann and Baltimore, 2008). In unstimulated cells, NF-κB is bound to IκB and retained in the cytosol in its inactive form. Phosphorylation of IκB by the IκB kinase (IKK) complex leads to the degradation of this protein, thereby releasing the active form of NF-κB which translocates to the nucleus and up-regulates gene expression (Edwards et al., 2009). Studies by Sugita et al. (2009) showed that IMD-0354, i.e. a selective inhibitor of IKKβ, inhibited allergic inflammation in an acute mouse model of ovalbumin (OVA)-induced asthma. In subsequent studies (Ogawa et al., 2011), these investigators demonstrated, using a mouse model of chronic asthma, that IMD-0354 inhibited the pathological features of airway remodeling.
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The present study attempts to shed light on the involvement of CD4+ effector (Teff) and Foxp3+CD25+CD4+ regulatory (Treg) T cells in the anti-asthmatic action of IMD-0354. CD4+ Teff cells have a central role in the pathogenesis of asthma. Following antigen presentation by dendritic cells to recirculating naïve T cells (Tn) in the mediastinal lymph nodes (MLNs), specific CD4+ T cells are activated and differentiated into Th2 effector type cells, which migrate to the lungs and orchestrate pulmonary immune responses (Lambrecht and Hammad, 2003). Moreover, Foxp3-expressing Treg cells have been discovered as another pivotal subset of CD4+ T cells involved in the pathogenesis of asthma (Provoost et al., 2009; Barczyk et al., 2014). There are numerous indications suggesting that the anti-allergic and anti-inflammatory effects of IKK inhibition in mouse models of asthma may be mediated, in a large part, through controlling the levels of CD4+ Teff and Treg cells in the MLNs and lungs. For example, it has been demonstrated that NF-κB plays a critical role in Th2 differentiation in allergic airway inflammation (Das et al., 2001). A beneficial effect of NF-κB inhibition in a rat model of severe pulmonary arterial hypertension was accompanied by a markedly increased abundance of Treg cells in the lungs (Farkas et al., 2014ab). Therefore, we hypothesized that one of the mechanisms underlying the anti-asthmatic action of IKK inhibitors can be the following effects: (a) preventing an allergen-induced increase in the number of CD4+ Teff cells in the MLNs, (b) inhibition of the recruitment of CD4+ Teff cells into the lungs, and (c) an increase in the number of Treg cells in the lungs and/or MLNs. 2. Materials and methods 2. 1. Animals All of the procedures were approved by the Local Ethics Commission (Ethic permission No. 10/2015). The experiments were carried out on 6-week-old Balb/c mice. Mice were bred and maintained under standard lab conditions [12/12 h light/dark cycle, controlled temperature (21 +/- 2°C) and humidity (55+/- 5%), and ad libitum access to food and water]
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in the Animal Facility of the Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn. 2. 2. IMD-0354 The specificity of IMD-0354 (N-[3,5-bis-trifluoromethyl-phenyl]-5-chloro-2-hydroxybenzamide) and its inhibitory action against IKKβ have been demonstrated previously (Onai et al., 2004; Tanaka et al., 2007). IMD-0354 powder was dissolved in 0.5% carboxymethylcellulose (both from Sigma-Aldrich, Munich, Germany) and administered intraperitoneally (i.p.) at a dose of 20 mg/kg/day for 6 days. This dose was chosen according to our preliminary studies and published reports (Ogawa et al., 2011; Sugita et al., 2009) indicating the anti-asthmatic effect of IMD-0354 at this dosage. 2. 3. Sensitization, challenge, and treatment protocol Mice were divided into three groups, namely PBS group (PBS-sensitized and challenged mice treated with vehicle, i.e. negative control group), OVA group (OVAsensitized and -challenged mice treated with vehicle, i.e. mice with OVA-induced model of allergic asthma), and OVA + IMD-0354 group (OVA-sensitized and -challenged mice treated with IMD-0354). The mice were sensitized on days 0 and 14 via i.p. injection of 20 µg OVA (Grade V) emulsified in 2 mg aluminum hydroxide (both from Sigma-Aldrich) in total volume of 200 µl PBS. On days 21, 22, 23 and 24, mice were challenged intranasally (i.n.) with 100 μg of OVA in 50 µl of PBS. Mice in PBS group received only aluminum hydroxide in PBS (sensitization) or PBS alone (challenge). IMD-0354 or vehicle (0.5% carboxymethylcellulose) administration was started 48 h prior to i.n. challenge (i.e. on day 19 after the initial sensitization) and continued for 5 consecutive days; the test substance or placebo were given 3 h before challenge. Mice were euthanized (by asphyxiation with CO2) 24 h after the last administration. The experimental study design scheme is shown in Fig. 1.
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2. 4. Lung histology Lungs taken during necropsy were fixed in 10% neutral buffered formalin and embedded in paraffin wax. Lung histological sections (3-4 µm) were stained with haematoxylin and eosin (H&E) (Merck, Germany) for detection of inflammatory infiltrates and with periodic acid-Schiff (PAS) (Sigma-Aldrich) for goblet cells and mucus production visualization. Sections were analyzed using a light microscope (Olympus BX51, Japan) with digital camera (ColorView, Olympus, Japan) and Cell^B software (Olympus, Japan). Airway inflammation was quantified in the peribronchial region of 5 different medium-sized bronchi per slide on the basis of a scoring system (Table 1) previously described and used in similar studies (Wittke et al., 2004). The results were averaged and totaled for each mouse, and thereafter, the mean [± standard deviation (S.D.)] score per group was calculated. Epithelial thickness (as the area between the luminal cell membrane and the basement membrane) was measured at 4 sites for 5 different medium-sized bronchi per slide. All measurements were averaged, giving the mean (± S.D.) epithelial thickness per group. 2. 5. Cell recovery 2. 5. 1. MLNs MLNs were removed and subjected to dounce homogenization. The resulting cell suspensions were filtered through nitex fabric (Fairview Fabrics, Hercules, USA), washed with Facs (fluorescence-activated cell-sorting) buffer [FB; Dulbecco's PBS devoid of Ca2+ and Mg2+ with 2% (v/v) heat-inactivated FBS (both from Sigma-Aldrich)], and centrifuged (300 x g for 5 min. at 5˚C; the same parameters were used for all cell-washing procedures). Cells were re-suspended in FB, counted and stained for flow cytometric analysis. 2. 5. 2. Lung samples Lungs obtained from two mice were combined into one sample. Lungs were minced, subjected to dounce homogenization, and washed in incomplete medium (RPMI-1640 + 10
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mM HEPES buffer + 10 U/ml penicillin/streptomycin; all from Sigma-Aldrich)]. Subsequently, lung tissues were digested with 50 U/ml (25 ml per sample) collagenase type IV (Sigma-Aldrich) solution containing DNase I (50 U per ml, Sigma-Aldrich) in a glass 50ml flask containing a magnetic stir bar. Following rapid agitation during digestion at 37˚ C for 90 min., the resulting cell supernatant was removed and filtered through nitex fabric, and the cells were washed in complete medium [CM; RPMI-1640 + 10% heat-inactivated fetal bovine serum + 10 mM HEPES buffer + 10 mM non-essential amino acids + 10 mM sodium pyruvate + 10 U/ml penicillin/streptomycin; all from Sigma-Aldrich]. Isolated cells were resuspended in a 40% percoll solution (Sigma-Aldrich), and then were layered over a 60% percoll solution and subjected to a gradient centrifugation (400 x g for 20 min. at 20˚C). Mononuclear cells were removed from the interface layer, washed and then re-suspended in FB, counted, and stained for flow cytometric analysis. 2. 5. 3. Peripheral blood Blood was drawn from the inferior vena cava into heparinized (for flow cytometry analysis) or EDTA coated [for the complete blood count (CBC)] tubes. Erythrocytes were removed using Red Blood Cell Lysing Buffer (RBCLB) [Na2EDTA (0.37 g) + NH4CL (8 g) + NaHCO3 (0.84 g) + H20 (500 ml); all from Sigma-Aldrich]. The samples (i.e 100 µl of whole blood) were treated with 2 ml of RBCLB, incubated for 7-8 min at 4˚C, and washed twice with 2 ml of FB. The remaining cells were re-suspended in FB and stained for flow cytometric analysis. Routine CBC was performed using a hematology analyzer Advia 2120i (Siemens Healthcare Diagnostics, Erlangen, Germany). 2. 6. Staining for flow cytometry analysis Cells prepared as described above were stained for surface antigens with fluorochrome conjugated monoclonal antibodies (mAbs): FITC rat anti-mouse CD4 (clone H129.19, IgG2a, κ), APC-Cy7 rat anti-mouse CD8a (clone 53-6.7, IgG2a, κ), PE-Cy7 rat anti-mouse CD25
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(clone PC61, IgG1, λ; all from BD Biosciences, San Jose, USA]; cells were stained for CD8 expression to distinguish CD4+CD8- T cells from double positive (i.e. CD4+CD8+) T cells. Following surface staining, cells were washed, fixed with 2% paraformaldehyde, and permeabilized using mouse Foxp3 buffer set (BD Biosciences). For intracellular Foxp3 expression, cells were labeled with PE-conjugated rat anti-mouse Foxp3 mAb (clone: MF23, IgG2b, BD Bioscience). 2. 7. FACS acquisition and analysis Flow cytometry analysis was performed using a FACSCanto II cytometer (BD Biosciences). The data were acquired by FACSDiva version 6.1.3 software (BD Biosciences) and analyzed by FlowJo software (Tree Star Inc., Stanford, USA). The entire volume of each sample was always acquired. Absolute cell counts of lymphocyte subsets (i.e. number of cells from particular subpopulations per μl of blood or per tissue sample) were calculated using the dual platform method: · Blood samples: absolute cell count was determined by calculating the data obtained from CBC by the percentage of particular cell subsets. · MLNs and lung samples: absolute count was determined by calculating the total cell yield from individual samples (cells were counted by using cell counting chamber) by the percentage of particular cell subsets. Fig. 2 presents a gating strategy for flow cytometric data analysis and specifies how the absolute count was calculated for particular cell subsets. 2. 8. Statistical analysis Data were expressed as the mean (± S.D.) for 8 mice/sample per group. Statistical analysis was done using one-way analysis of variance (ANOVA) followed by Bonferroni's post hoc test. Differences were deemed significant when the P values were < 0.05. SigmaPlot
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Software Version 12.0 (Systat Software Inc., San Jose, USA) was used for statistical analysis and plotting graphs. 3. Results 3. 1. Histopathology Mice were primed and challenged with OVA to induce a model of allergic asthma. The scoring system was used for quantification of histopathological changes in the lungs. The mean scores for OVA group (7.90 ± 1.24) were significantly increased (P < 0.001) compared to PBS (0.53 ± 0.56) and OVA + IMD-0354 groups (1.50 ± 1.75) (Fig. 3A). There were no significant differences between the last two groups (Fig. 3A). All mice in OVA group developed features characteristic for asthmatic inflammation (Fig. 3C). The influx of inflammatory cells occurred around the bronchi and bronchioles; the invading cells were composed mainly of eosinophils (Fig. 3C, H&E). There was observed goblet cell hyperplasia and mucus hypersecretion (Fig. 3C, PAS). In contrast, there was no airway inflammation in PBS and OVA + IMD-0354 groups (Fig. 3C), with the exception of one mouse from the IMD-0354-treated group, which showed very little inflammation. Quantitative assessment of epithelial thickness demonstrated a significant increase (P < 0.001) in epithelial thickening in OVA group (24.17 ± 6.76) compared to PBS group (11.37 ± 2.59) and to OVA + IMD-0354 group (12.16 ± 4.24) (Fig. 3B). Epithelial thickness did not differ significantly between the PBS and OVA + IMD-0354 groups (Fig. 3B). 3. 2. The effect of IMD-0354 on the absolute counts of CD4+ T cell subsets in MLNs The conducted studies demonstrated that immunization with OVA induced a significant increase (P < 0.001) in the number of Foxp3+CD25+CD4+ (Fig. 4A), Foxp3-CD25+CD4+ (Fig. 4B) and CD25-CD4+ (Fig. 4C) T cells in the MLNs of vehicle treated mice (OVA group) compared to PBS and OVA + IMD-0354 groups. The number of these cell subsets was more than 4-, 3-, and 4-fold greater in OVA group, respectively, relative to PBS group. Significant
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differences were not found between PBS and OVA + IMD-0354 groups with respect to the absolute counts of Foxp3+CD25+CD4+ (Fig. 4A), Foxp3-CD25+CD4+ (Fig. 4B) and CD25CD4+ (Fig. 4C) T cells in the MLNs. 3. 3. The effect of IMD-0354 on the absolute counts of CD4+ T cell subsets in the lungs Similar to observations in the MLNs, the absolute number of Foxp3+CD25+CD4+ (Fig. 5A), Foxp3-CD25+CD4+ (Fig. 5B) and CD25-CD4+ (Fig. 5C) T cells was considerably increased (P < 0.001) in the lungs of mice from OVA group compared to PBS and OVA + IMD-0354 groups. The absolute count of these cell subsets in OVA group was significantly elevated by about 19-, 5-, and 7-fold, respectively, relative to PBS group. The absolute number of Foxp3+CD25+CD4+ (Fig. 5A), Foxp3-CD25+CD4+ (Fig. 5B) and CD25-CD4+ (Fig. 5C) T cells did not differ significantly between PBS and OVA + IMD-0354 groups. 3. 4. The effect of IMD-0354 on the absolute counts of CD4+ T cell subsets in peripheral blood The present studies did not reveal any effect of OVA or IMD-0354 exposures on the absolute counts of Foxp3+CD25+CD4+ (Fig. 6A) and CD25-CD4+ (Fig. 6C) T cells in peripheral blood. In OVA group, the absolute number of Foxp3-CD25+CD4+ T cells was considerably elevated (P < 0.001) compared to PBS group (Fig. 6B). The absolute count of cells from this subset in mice treated with IMD-0354 was not different from that in PBS group (Fig. 6B). 4. Discussion Glucocorticoid resistance presents a profound management problem in patients with asthma because conventional therapies are not effective (Adcock et al., 2008). Treatment of patients with steroid-resistant asthma will require novel therapies tailored to this specific subgroup of patients. NF-κB is an attractive and important therapeutic target for the treatment of asthma. This notion is supported by the fact that several lines of evidence indicate
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increased NF-κB pathway activation in the airway tissues of asthmatic subjects; increased activation of NF-κB has been demonstrated in the airway epithelium of human asthmatics (Hart et al., 1998; Zhao et al., 2001) and in the lungs of animal models of asthma (Bureau et al., 2000; Lin et al., 2000; Poynter et al., 2002). IKKβ, but not IKKα, plays a crucial role in NF-κB activation (Edwards et al., 2009; Hoffmann and Baltimore, 2006), and therefore its inhibition is considered an attractive target for the development of novel anti-asthmatic agents. Sugita et al. (2009) and Ogawa et al. (2011) demonstrated that inhibition of IKKβ with IMD-0354 led to a significant reduction in inflammatory cell infiltration and mucus production in lung tissues of OVA-sensitized/challenged mice. Moreover, other research found that treatment with IKKβ inhibitor (Compound A) efficiently reduced the number of eosinophils and neutrophils in bronchoalveolar lavage fluid of rats with OVA-induced allergic airway inflammation (Ziegelbauer et al., 2005). In the present studies, analysis of the lung tissue by the scoring system indicated that treatment with IMD-0354 prevented OVA-induced allergic airway inflammation. Thus, our results confirm the conclusions of the above-cited studies that IMD-0354 may be therapeutically beneficial for treating airway inflammation in asthma. However, the present research aimed to explore the involvement of CD4+ Teff and Treg cells in the anti-asthmatic action of IMD-0354. It should be clarified that CD25 is α chain of the IL-2 receptor that is expressed on Treg cells and activated T and B lymphocytes, whereas Foxp3 is a unique marker and a “master” regulator of the development and suppressive function of Treg cells (Fontenot et al., 2003). Foxp3 currently represents the most specific marker used to distinguish Treg cells (Foxp3+CD25+CD4+) from activated Teff cells (Foxp3-CD25+CD4+); the CD25-CD4+ phenotype represents resting cells, i.e. Tn, effector memory (Tem) and central memory (Tcm) T cells (Sondel et al., 2003). In the OVA-induced asthma model, apart from Th2 cells [the primary Teff cells in asthmatic patients (Lambrecht
11
and Hammad, 2003)], other CD4+ Teff cell subsets, such as Th17 [very important in the pathogenesis of asthma (Park and Lee, 2010)] and Th1 (their role in asthma is still uncertain), occur in the MLNs and lungs (Lee et al., 2013). The present studies have demonstrated that the amount of activated CD4+ Teff and resting T cells in the MLNs and lungs of mice with OVA-induced allergic asthma was several fold higher compared to healthy control mice. All of these effects were fully prevented by the treatment with IMD-0354. It is intriguing that in the lungs of untreated mice with OVA-induced asthma, similar to normal lungs, CD25-CD4+ T cells, but not activated Teff cells, were the predominant subset, which is in agreement with results reported by Pastva et al. (2011). They found 24 h after the third challenge with OVA that the majority of lung CD4+ T lymphocytes were naïve and memory cells. Moreover, although numerous reviews and textbooks state that Tn cells do not normally enter nonlymphoid organs, several studies have demonstrated that as part of the normal migratory pathway, these cells enter non-lymphoid organs including the lungs (Cose et al., 2006; Luettig et al., 2001; Westermann et al., 2001). Therefore, OVA-induced increases in CD25-CD4+ T cells observed in the present studies can be interpreted as infiltration of the lungs with Tn and Tem cells. Taking all of the above into consideration, it can be stated that IMD-0354 exerts anti-asthmatic effects, at least partially, by preventing the activation and clonal expansion of CD4+ Teff cells in the MLNs. This conclusion is supported by reports indicating that IKK inhibitors, including IMD-0354, exert anti-proliferative action on T cells (Min et al., 2013; Tanaka et al., 2007; Ziegelbauer et al., 2005). Furthermore, it has been demonstrated that NFκB plays critical roles in Th2 differentiation in allergic airway inflammation (Das et al., 2001). Kimura et al. (2007) found an enhanced ability of CD4+ T cell with up-regulated NFκB activation to differentiate into Th2 cells. Our hypothesis presumed that one of the mechanisms responsible for anti-asthmatic action of IMD-0354 might be prevention of the recruitment of activated CD4+ Teff cells into
12
the lungs. This hypothesis was supported by the fact that activation of NF-κB contributes to the production of Th2-attracting chemokines [i.e. thymus and activation-regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22)], which play a key role in controlling the trafficking of Th2 cells into the lung during allergic inflammation (Jeong et al., 2010; Kwon et al., 2012; Nakayama et al., 2004). It was found that the inhibition of NFκB activation was associated with the suppression of TARC/CCL17 and MDC/CCL22 production (Jeong et al., 2010; Kwon et al., 2012), which suggests that IKK inhibitors may impair/block recruitment of Th2 cells into the lungs. Our studies show that treatment with IMD-0354 prevented infiltration of the lungs with activated CD4+ Teff cells. However, this effect was probably not a result of the direct influence of IMD-0354 on lymphocyte trafficking and homing into the lungs but was secondary in character, i.e. it was a consequence of its effect on the MLNs. As the OVA-induced increase in the number of activated CD4+ Teff in the MLNs was abolished by IMD-0354 treatment, there were not Teff cells available for recruitment into the lungs. This conclusion is supported by the fact that IMD-0354 prevented the OVA-induced increase in the number of activated CD4+ Teff cells in peripheral blood, which apparently reflected the trafficking of these cells from the MLNs into the lungs. On the other hand, our results strongly suggest that IMD-0354 prevented infiltration of the lungs with Tn cells (the majority of CD4+CD25- T lymphocytes represent cells in the naïve stage), but the importance of this effect is not clear. Foxp3+CD25+CD4+ Treg cells have been strongly associated with suppression of immune responses in animal models of asthma including the OVA-induced asthma (Kearley et al., 2005, 2008; Leech et al., 2007). It was demonstrated that the beneficial effect of NF-κB inhibition in a rat model of severe pulmonary arterial hypertension was accompanied by a markedly increased abundance of Treg cells in the lungs (Farkas et al., 2014ab), and the antiarthritic action of IKK inhibitor was associated with an increase in the number of Treg cells in
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the draining inguinal lymph nodes and joints (Min et al., 2013). Therefore, taking all the above into consideration, the hypothesis was formulated that anti-asthmatic effect of pharmacological inhibition of NF-κB signaling may be also associated with the expansion and/or accumulation of Treg cells in the lungs and/or MLNs. However, we found that in mice treated with IMD-0354 the number of Treg cells in any of the examined compartments did not differ significantly from that in the healthy controls, while in the lungs and MLNs of mice with asthma, their count was increased by approximately 20- and 4-fold, respectively, compared to control values. The last finding was not surprising and is consistent with two other related studies. Olsen et al. (2015) revealed that OVA challenge resulted in a comparable increase in the absolute number of Treg cells in the lungs. Other investigators (Leech et al., 2007) demonstrated that the resolution of allergic airway inflammation was mediated by Treg cells; they found that upon airway challenge of Der p1-sensitized mice, Treg cells migrated into both lungs and MLNs and peaked in number at 4 days after challenge, i.e. just before the start of resolution of disease markers. Recapitulating, our results indicate that the anti-allergic and anti-inflammatory actions of IMD-0354 are not mediated through increased recruitment of Treg cells into the MLNs and lungs and/or local generation of inducible Treg cells. 5. Conclusions Our results indicate that IMD-0354 exerts anti-asthmatic action, at least partially, by blocking the activation and clonal expansion of CD4+ Teff cells in the MLNs which, in consequence, prevents infiltration of the lungs with activated CD4+ Teff cells. The beneficial effects of IMD-0354 in a mouse model of asthma are not mediated through increased recruitment of Treg cells into the MLNs and lungs and/or local generation of inducible Treg cells. Acknowledgments
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The study was supported by the grant No. 15.610.008-300 from the University of Warmia and Mazury in Olsztyn. References Adcock, I.M., Ford, P.A., Bhavsar, P., Ahmad, T., Chung, K.F., 2008. Steroid resistance in asthma: mechanisms and treatment options. Curr. Allergy Asthma Rep. 8, 171-178. Barczyk, A., Pierzchala, W., Caramori, G., Wiaderkiewicz, R., Kaminski, M., Barnes, P.J., Adcock, I.M., 2014. Decreased percentage of CD4+Foxp3+TGF-β+ and increased percentage of CD4+IL-17+ cells in bronchoalveolar lavage of asthmatics. J. Inflamm. 11:22. Bureau, F., Delhalle, S., Bonizzi, G., Fievez, L., Dogne, S., Kirschvink, N., Vanderplasschen, A., Merville, M.P., Bours, V., Lekeux, P., 2000. Mechanisms of persistent NF-kappa B activity in the bronchi of an animal model of asthma. J. Immunol. 165, 5822-5830. Cose, S., Brammer, C., Khanna, K.M., Masopust, D., Lefrancois, L., 2006. Evidence that a significant number of naive T cells enter non-lymphoid organs as part of a normal migratory pathway. Eur. J. Immunol. 36, 1423-1433. Das, J., Chen, C.H., Yang, L., Cohn, L., Ray, P., Ray, A., 2001. A critical role for NF-kappa B in GATA3 expression and TH2 differentiation in allergic airway inflammation. Nat. Immunol. 2, 45-50. Edwards, M.R., Bartlett, N.W., Clarke, D., Birrell, M., Belvisi, M., Johnston, S.L., 2009. Targeting the NF-kappaB pathway in asthma and chronic obstructive pulmonary disease. Pharmacol. Ther. 121, 1-13. Farkas, D., Alhussaini, A.A., Kraskauskas, D., Kraskauskiene, V., Cool, C.D., Nicolls, M.R., Natarajan, R., Farkas, L., 2014a. Nuclear factor κB inhibition reduces lung vascular lumen obliteration in severe pulmonary hypertension in rats. Am. J. Respir. Cell Mol. Biol. 51, 413-525.
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Ogawa, H., Azuma, M., Muto, S., Nishioka, Y., Honjo, A., Tezuka, T., Uehara, H., Izumi, K., Itai, A., Sone, S., 2011. IκB kinase β inhibitor IMD-0354 suppresses airway remodelling in a Dermatophagoides pteronyssinus-sensitized mouse model of chronic asthma. Clin. Exp. Allergy 41, 104-115. Olsen, P.C., Kitoko, J.Z., Ferreira, T.P., de-Azevedo, C.T., Arantes, A.C,. Martins, ΜA., 2015. Glucocorticoids decrease Treg cell numbers in lungs of allergic mice. Eur. J. Pharmacol. 747, 52-58. Onai, Y., Suzuki, J., Kakuta, T., Maejima, Y., Haraguchi, G., Fukasawa, H., Muto, S., Itai, A., Isobe, M., 2004. Inhibition of IkappaB phosphorylation in cardiomyocytes attenuates myocardial ischemia/reperfusion injury. Cardiovasc. Res. 63, 51-59. Park, S.J., Lee, Y.C., 2010. Interleukin-17 regulation: an attractive therapeutic approach for asthma. Respir. Res. 11:78. Pastva, A.M., Mukherjee, S., Giamberardino, C., Hsia, B., Lo, B., Sempowski, G.D., Wright J.R., 2011. Lung effector memory and activated CD4+ T cells display enhanced proliferation in surfactant protein A-deficient mice during allergen-mediated inflammation. J. Immunol. 186, 2842-2849. Provoost, S., Maes, T., van Durme, Y.M., Gevaert, P., Bachert, C., Schmidt-Weber, C.B., Brusselle, G.G., Joos, G.F., Tournoy, K.G., 2009. Decreased FOXP3 protein expression in patients with asthma. Allergy 64, 1539-1546. Poynter, M.E., Irvin, C.G., Janssen-Heininger, Y.M., 2002. Rapid activation of nuclear factorkappaB in airway epithelium in a murine model of allergic airway inflammation. Am. J. Pathol. 160, 1325-1334. Sondel, P.M., Buhtoiarov, I.N., DeSantes, K., 2003. Pleasant memories: remembering immune protection while forgetting about graft-versus-host disease. J. Clin. Invest. 112, 25-27.
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Sugita, A., Ogawa, H., Azuma, M., Muto, S., Honjo, A., Yanagawa, H., Nishioka, Y., Tani, K., Itai, A., Sone, S., 2009. Antiallergic and anti-inflammatory effects of a novel I kappaB kinase beta inhibitor, IMD-0354, in a mouse model of allergic inflammation. Int. Arch. Allergy Immunol. 148, 186-198. Tanaka, A., Muto, S., Jung, K., Itai, A., Matsuda, H., 2007. Topical application with a new NF-kappaB inhibitor improves atopic dermatitis in NC/NgaTnd mice. J. Invest. Dermatol. 127, 855-863. Westermann, J., Ehlers, E.M., Exton, M.S., Kaiser, M., Bode, U., 2001. Migration of naive, effector and memory T cells: implications for the regulation of immune responses. Immunol. Rev. 184, 20-37. Wittke, A., Weaver, V., Mahon, B.D., August, A., Cantorna, M.T., 2004. Vitamin D receptordeficient mice fail to develop experimental allergic asthma. J. Immunol. 2004, 173, 34323436. Zhao, S., Qi, Y., Liu, X., Jiang, Q., Liu, S., Jiang, Y., Jiang, Z., 2001. Activation of NF-kappa B in bronchial epithelial cells from children with asthma. Chin. Med. J. (Engl.) 114, 909911. Ziegelbauer, K., Gantner, F., Lukacs, N.W., Berlin, A., Fuchikami, K., Niki, T., Sakai, K., Inbe, H., Takeshita, K., Ishimori, M., Komura, H., Murata, T., Lowinger, T., Bacon, K.B., 2005. A selective novel low-molecular-weight inhibitor of IkappaB kinase-beta (IKK-beta) prevents pulmonary inflammation and shows broad anti-inflammatory activity. Br. J. Pharmacol. 145, 178-192. Conflict of interest statement The authors declare that they have no conflict of interests. Figure captions
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Fig. 1. Experimental study design scheme. Mice were sensitized to ovalbumin (OVA) by two intraperitoneal (i.p.) injections on days 0 and 14 with OVA absorbed on aluminum hydroxide. Subsequently, mice were challenged intranasally with OVA (OVA and OVA + IMD-0354 groups) on days 21, 22, 23, and 24. Mice in the negative control group (PBS group) received only aluminum hydroxide in PBS (sensitization) or PBS alone (challenge). Different groups of mice were treated i.p. with vehicle (PBS and OVA groups) or IMD-0354 (OVA + IMD0354 group). Fig. 2. Gating strategy for flow cytometric data analysis and calculation of the absolute cell counts of lymphocyte subsets. Lymphocytes were identified based on forward and side scatter (FSC/SSC) properties and then gated for expression of CD4 and CD8 surface receptors. Relative to the presence of CD25 expression, the CD4+ T cell population was subdivided into CD25- and CD25+ cell subsets. CD25+CD4+ T cells were analyzed for Foxp3 expression. Absolute cell counts of lymphocyte subsets (i.e. number of cells from particular subpopulations per μl of blood or per tissue sample) were calculated using the dual platform method, as shown above. Fig. 3. Quantitative assessment of allergic airway inflammation and treatment efficacy. Mean histology scores of airway inflammation (A) and mean epithelial thickness (B). Results are expressed as the mean (± S.D.) of two independent experiments with 4 animals per group (n = 8 per group, *P < 0.001, one-way ANOVA with the Bonferroni post hoc test). Examples of photomicrographs of tissue sections stained with haematoxilin/eosin (H&E) and periodic acid-Schiff (PAS) (C). Densely infiltrated eosinophils and lymphocytes (enlargement of rectangle in upper photograph) with mucous hypersecretion are visible in lung sections of vehicle-treated, ovalbumin-immunized mouse (OVA group), while there are not histopathological abnormalities in sections of non-immunized mouse (PBS group) and IMD-
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0354-treated, OVA-immunized mouse (OVA + IMD-0354 group). Magnification: 20-fold; 100-fold for the insert. Fig. 4. The effect of IMD-0354 on the absolute counts of Foxp3+CD25+CD4+ (A) Foxp3CD25+CD4+ (B) and CD25-CD4+ (C) T cells in the mediastinal lymph nodes (MLNs) of nonimmunized mice (PBS group), vehicle-treated, ovalbumin-immunized mice (OVA group) and IMD-0354-treated, OVA-immunized mice (OVA + IMD-0354 group). The absolute count represents the number of cells of each subset per MLN sample. Results are expressed as the mean (± S.D.) of two independent experiments with 4 mice per group (n = 8 per group, *P < 0.001, one-way ANOVA with the Bonferroni post hoc test). Fig. 5. The effect of IMD-0354 on the absolute counts of Foxp3+CD25+CD4+ (A) Foxp3CD25+CD4+ (B) and CD25-CD4+ (C) T cells in the lungs of non-immunized mice (PBS group), vehicle-treated, ovalbumin-immunized mice (OVA group) and IMD-0354-treated, OVA-immunized mice (OVA + IMD-0354 group). The absolute count represents the number of cells of each subset per lung sample pooled from 2 animals. Results are expressed as the mean (± S.D.) of two independent experiments involving 4 lung samples per group (n = 8 per group, *P < 0.001, one-way ANOVA with the Bonferroni post hoc test). Fig. 6. The effect of IMD-0354 on the absolute counts of Foxp3+CD25+CD4+ (A), Foxp3CD25+CD4+ (B) and CD25-CD4+ (C) T cells in peripheral blood of non-immunized mice (PBS group), vehicle-treated, ovalbumin-immunized mice (OVA group) and IMD-0354treated, OVA-immunized mice (OVA + IMD-0354 group). The absolute count represents the number of cells of each subset per µl of blood. Results are expressed as the mean (± S.D.) of two independent experiments, each with 4 animals per group (n = 8 per group, *P < 0.001, one-way ANOVA with the Bonferroni post hoc test).
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 1
Table 1
1
Table 1. The scoring system used for evaluation of airway inflammation (Wittke et al., 2004)
Category
Criterion of evaluation
Points assigned per criterion
Inflammation
no inflammation
0
minimal: inflammatory cells present
1
mild: a few (
