Airway hyperresponsiveness: first eosinophils and then neuropeptides

Modulating asthma-COPD overlap responses with IL-17 inhibition

Background

IL-17 is a modulator of the inflammatory response and is implicated in lung remodeling in both asthma and chronic obstructive pulmonary disease (COPD). Well as and probably in patients with asthma-COPD overlap (ACO).

Methods

In this study, we evaluated the response of the airways and alveolar septa to anti-IL-17 treatment in an ACO model. Fifty-six male BALB/c mice were sensitized with ovalbumin (OVA group), received porcine pancreatic elastase (PPE group), or both (ACO group). Mice were then treated with either anti-IL-17 monoclonal antibody or saline. We evaluated hyperresponsiveness, bronchoalveolar lavage fluid (BALF) cell counts, and mean alveolar diameter. We quantified inflammatory, response, extracellular matrix remodeling, oxidative stress markers, and signaling pathway markers.

Results

Anti-IL-17 treatment in the ACO anti-IL-17 group reduced the maximum response of respiratory system Rrs, Ers, Raw, Gtis, this when compared to the ACO group (p<0.05). There was a reduction in the total number of inflammatory cells, neutrophils, and macrophages in the BALF in the ACO anti-IL-17 group compared to the ACO group (p<0.05). There was attenuated dendritic cells, CD4+, CD8+, FOXP3, IL-1β, IL-2, IL-6, IL-13, IL-17, IL-33 in ACO anti-IL-17 group in airway and alveolar septum compared to the ACO group (p<0.05). We observed a reduction of MMP-9, MMP-12, TIMP-1, TGF-β, collagen type I in ACO anti-IL-17 group in airway and alveolar septum compared to the ACO group (p < 0.05). We also observed a reduction of iNOS and 8-iso-PGF2α in the airways and in the alveolar septum was reduced in the ACO anti-IL-17group compared to the ACO group (p < 0.05). Regarding the signaling pathways, NF-kB, ROCK-1, and ROCK-2 in the airway and alveolar septum were attenuated in the ACO anti-IL-17 group when compared to the ACO group (p<0.05).

Conclusions

Our results suggest that inhibiting IL-17 modulates cell-associated cytokine production in lung tissue, extracellular matrix remodeling, and oxidative stress in ACO through the modulation of NF-kB and FOXP3.

Intestinal Barrier Function and Immune Homeostasis Are Missing Links in Obesity and Type 2 Diabetes Development

Noncommunicable diseases, such as type 2 diabetes (T2D), place a burden on healthcare systems worldwide. The rising prevalence of obesity, a major risk factor for T2D, is mainly attributed to the adoption of Westernized diets and lifestyle, which cause metabolic dysfunction and insulin resistance. Moreover, diet may also induce changes in the microbiota composition, thereby affecting intestinal immunity. The critical role of intestinal immunity and intestinal barrier function in the development of T2D is increasingly acknowledged, however, limited studies have investigated the link between intestinal function and metabolic disease. In this review, studies reporting specific roles of the intestinal immune system and intestinal epithelial cells (IECs) in metabolic disease are highlighted. Innate chemokine signaling, eosinophils, immunoglobulin A (IgA), T helper (Th) 17 cells and their cytokines were associated with obesity and/or dysregulated glucose homeostasis. Intestinal epithelial cells (IECs) emerged as critical modulators of obesity and glucose homeostasis through their effect on lipopolysaccharide (LPS) signaling and decontamination. Furthermore, IECs create a link between microbial metabolites and whole-body metabolic function. Future in depth studies of the intestinal immune system and IECs may provide new opportunities and targets to develop treatments and prevention strategies for obesity and T2D.

Nonclinical Safety Assessment of an Inhaled Formulation of Serelaxin: A Recombinant Human Protein in Rats and Cynomolgus Monkeys (Macaca fascicularis)

Serelaxin is a recombinant human relaxin-2 intended for cardiovascular indications. Inhalation was chosen as alternative route to intravenous to allow daily administration for chronic applications and home treatment. A total of 4 short-term studies were conducted in rats and cynomolgus monkeys with inhaled formulation of serelaxin at dose up to 10 mg/kg/d. All rats and cynomolgus macaques receiving serelaxin were exposed to the test item. One rat and approximately 50% of macaques developed immunogenicity, which did not appear to affect exposure. No adverse effect on respiratory function or systemic changes was noted. Both species developed similar microscopic lesions characterized by eosinophilic cell infiltration around bronchi; however, in the rat, this was more pronounced and extended to a perivascular location. In addition, in the rat, serelaxin showed eosinophilic crystalline material associated with macrophages in the alveoli and bronchioles. In macaques, serelaxin induced minimal macrophage infiltrates in alveoli and perivascular/peribronchiolar mononuclear cell infiltrations. The minimal airway eosinophilic/mononuclear inflammatory cell infiltrations were considered to be nonadverse in macaques due to the minimal severity and the lack of any other alterations in the lung parenchyma. In the rat, the presence of eosinophilic crystalline material and macrophage response, characterized as precipitated test article, was considered adverse.

dNP2-ctCTLA-4 inhibits German cockroach extract-induced allergic airway inflammation and hyper-responsiveness via inhibition of Th2 responses

German cockroaches are major household allergens that can trigger allergic airway inflammatory diseases with sensitive T-cell responses. Although the use of immune modulatory biologics, such as antibodies, to mediate allergic responses has recently been examined, only systemic administration is available because of the size limitations on intranasal administration. Here we utilized a cell-permeable peptide, dNP2, to deliver the cytoplasmic domain of cytotoxic T-lymphocyte antigen-4 (ctCTLA-4) through the airway epithelium to modulate Th2 responses in a German cockroach extract (GCE)-induced allergic airway inflammation model. The intranasal delivery efficiency of the dNP2-dTomato protein to the lungs was higher in GCE-induced asthmatic lung parenchymal cells compared to the sham cells. Intranasal administration of the dNP2-ctCTLA-4 protein inhibited airway hyper-responsiveness and reduced airway inflammation and remodeling, including goblet cell metaplasia and collagen deposition around the bronchi. The number of infiltrated cells, including eosinophils, and the levels of IL-4, IL-5, IL-13 and IFN-γ in the lungs were significantly reduced, presumably owing to inhibition of Th2 differentiation. However, intranasal administration of CTLA4-Ig did not inhibit airway inflammation. These results collectively suggest that dNP2-ctCTLA-4 is an efficient intranasally applicable candidate biologic for treating allergic asthma.

Th9 cells elicit eosinophil-independent bronchial hyperresponsiveness in mice

BACKGROUND

Airway accumulation of eosinophils and bronchial hyperresponsiveness (BHR) are prominent features of bronchial asthma, though the contribution of eosinophils to the development of BHR is controversial. Similar to Th2 cell-mediated pathology, Th9 cells, characterized by IL-9-producing activity, have been demonstrated to induce airway eosinophilia and BHR. In this study, we investigated the role of eosinophils in Th9-mediated BHR by employing Th9 cell-transferred murine airway inflammation model.

METHODS

Ovalbumin (OVA)-specific Th2 and Th9 cells were differentiated from CD4(+) T cells of DO11.10/RAG-2(-/-) mice in vitro and cytokine-producing activity of those cells was examined. BALB/c mice were adoptively transferred with Th2 or Th9 cells and challenged with OVA. Then, the number of inflammatory cells in bronchoalveolar lavage fluid and bronchial responsiveness to inhaled methacholine were determined.

RESULTS

Both in Th2 and Th9 cell-transferred mice, substantial accumulation of eosinophils in the lungs and BHR were induced by challenge with specific antigen. Nevertheless, an essential and dispensable role of eosinophils in Th2- and Th9-mediated BHR, respectively, was demonstrated by employing eosinophil-deficient mice. The neutralization of IL-9 as well as deficiency of IL-10 in the donor cells did not affect Th9-mediated BHR.

CONCLUSIONS

In contrast to Th2-mediated and eosinophil-dependent BHR, Th9 could induce BHR independently from eosinophils and its characteristic cytokines, IL-9 and IL-10.

Essential Contribution of CD4+ T Cells to Antigen-Induced Nasal Hyperresponsiveness in Experimental Allergic Rhinitis

Nasal hyperresponsiveness (NHR) is a characteristic feature of allergic rhinitis (AR); however, the pathogenesis of NHR is not fully understood. In this study, during the establishment of an experimental AR model using ovalbumin-immunized and -challenged mice, augmentation of the sneezing reaction in response to nonspecific proteins as well as a chemical stimulant was detected. Whether NHR is independent of mast cells and eosinophils was determined by using mast cell- and eosinophil-deficient mice. NHR was suppressed by treatment with anti-CD4 antibody, suggesting the pivotal contribution of CD4+ T cells. Furthermore, antigen challenge to mice to which in vitro-differentiated Th1, Th2, and Th17 cells but not naïve CD4+ T cells had been adoptively transferred led to the development of equivalent NHR. Since antigen-specific IgE and IgG were not produced in these mice and since antigen-specific IgE-transgenic mice did not develop NHR even upon antigen challenge, humoral immunity would be dispensable for NHR. CD4+ T cells play a crucial role in the pathogenesis of AR via induction of NHR, independent of IgE-, mast cell-, and eosinophil-mediated responses.

Antiasthmatic effects of schizandrae fructus extract in mice with asthma

Background:

Schizandrae fructus (SF), the fruit of Schisandra chinensis, has been used for the treatment of cough, wheezing, dry mouth, hepatitis, cardiovascular disease, and as a tonic and astringent in China, Japan, and Korea.

Objective:

Investigation of the antiasthmatic effects of SF.

Materials and Methods:

We investigated the effects of SF on airway hyperresponsiveness (AHR) to methacholine, production levels of antigen-specific antibodies, and histopathological changes in the lung tissue in a mouse model (Balb/c) of asthma induced by repeated intranasal instillation of an antigen.

Results:

SF lowered AHR to methacholine (P < 0.05), antigen-specific immunoglobulin E (IgE) level (P < 0.01), and immune cell infiltration in mice with asthma. Prednisolone (PD) effectively decreased AHR (P < 0.01), total antibody (P < 0.01) and IgE (P < 0.01) levels, and immune cell infiltration. SF and PD did not affect the levels of antigen-specific IgG1 and IgG2a antibodies.

Conclusion:

Our data suggest that SF has possible application as an antiasthmatic drug. We also suggest that SF could be used as a complementary or alternative medicine to glucocorticoids.

Chemokines mediate ethanol-induced exacerbations of murine cockroach allergen asthma

Asthma imposes considerable patient and economic burdens, with the most severe cases causing the greatest affliction. Identifying stimuli that worsen asthma severity is an essential step to controlling both disease morbidity and the lessening economic impact. This study provides the first mechanistic investigation into how acute ethanol exposure will increase asthma severity in a murine model of mild cockroach allergen (CRA)-induced asthma. Outbred mice were sensitized to induce mild allergic asthma, with intratracheal CRA exposures on days 0 and 14. On day 21 mice were gavaged with water or 32% ethanol, and the third allergen exposure was given 30 min post-gavage. Asthmatic responses were measured at several time-points up to 42 h after the third allergen challenge. Ethanol-gavaged mice showed increased asthma severity within 90 min post-allergen challenge, with exacerbations lasting for 24 h. Ethanol caused greater airways obstruction, including an eightfold increase in epithelial cell mucin and increased mucus plugs, resulting in a 50% reduction in bronchiole patency. Ethanol gavage also induced significant increases in airways hyperreactivity. While T helper type 1 (Th1) and Th2 cytokines were not altered by ethanol gavage, pulmonary neutrophil and eosinophil recruitment were augmented. This increase was associated with increased chemokine production. Administration 2 h prior to ethanol gavage of a neutralizing antibody cocktail to keratinocyte-derived chemokine, macrophage inflammatory protein-2, eotaxin-1 and eotaxin-2 prevented ethanol-induced eosinophil recruitment and airways hyperreactivity. These data provide evidence that acute alcohol exposure immediately prior to a mild allergen-triggered asthmatic episode will exacerbate asthma severity mediated by increased production of chemokines.

Glucocorticoids ameliorate antigen-induced bronchial smooth muscle hyperresponsiveness by inhibiting upregulation of RhoA in rats

To determine the mechanism(s) of the inhibitory effect of glucocorticoids on airway hyperresponsiveness in allergic bronchial asthma, the effects of systemic treatment with glucocorticoids on bronchial smooth muscle hyperresponsiveness and RhoA upregulation were investigated in rats with allergic bronchial asthma. Rats were sensitized and repeatedly challenged with 2,4-dinitrophenylated Ascaris suum antigen. Animals were also treated with prednisolone or beclomethasone (each 10 mg/kg, i.p.) once a day during the antigen inhalation period. Repeated antigen inhalation caused a marked bronchial smooth muscle hyperresponsiveness to acetylcholine with an upregulation of RhoA. Augmented acetylcholine-induced activation of RhoA and phosphorylation of myosin light chain were observed in bronchial smooth muscles of the antigen-exposed animals. Systemic treatment with either glucocorticoid used inhibited the bronchial smooth muscle hypercontraction until the level of the sensitized control rats that received saline inhalation instead of antigen challenge. Interestingly, both glucocorticoids also inhibited the upregulation of RhoA and augmented acetylcholine-induced activation of RhoA and phosphorylation of myosin light chain. In conclusion, glucocorticoids ameliorated the augmented bronchial smooth muscle contraction by inhibiting upregulation of RhoA. These effects of glucocorticoids may account for, in part, their beneficial effects in the treatment of asthma.

Ontogeny of the eotaxins in human lung

The ontogeny of the C-C chemokines eotaxin-1, eotaxin-2, and eotaxin-3 has not been fully elucidated in human lung. We explored a possible role for eotaxin in developing lung by determining the ontogeny of eotaxin-1 (CCL11), eotaxin-2 (CCL24), eotaxin-3 (CCL26), and the eotaxin receptor, CCR3. We tested discarded surgical samples of developing human lung tissue using quantitative RT-PCR (QRT-PCR) and immunostaining for expression of CCL11, CCL24, CCL26, and CCR3. We assessed possible functionality of the eotaxin-CCR3 system by treating lung explant cultures with exogenous CCL11 and analyzing the cultures for evidence of changes in proliferation and activation of ERK1/2, a signaling pathway associated with CCR3. QRT-PCR analyses of 22 developing lung tissue samples with gestational ages 10-23 wk demonstrated that eotaxin-1 mRNA is most abundant in developing lung, whereas mRNAs for eotaxin-2 and eotaxin-3 are minimally detectable. CCL11 mRNA levels correlated with gestational age (P < 0.05), and immunoreactivity was localized predominantly to airway epithelial cells. QRT-PCR analysis detected CCR3 expression in 16 of 19 developing lung samples. Supporting functional capacity in the immature lung, CCL11 treatment of lung explant cultures resulted in significantly increased (P < 0.05) cell proliferation and activation of the ERK signaling pathway, which is downstream from CCR3, suggesting that proliferation was due to activation of CCR3 receptors by CCL11. We conclude that developing lung expresses the eotaxins and functional CCR3 receptor. CCL11 may promote airway epithelial proliferation in the developing lung.

The role of Alkoxy group on the a ring of isoflavones in the inhibition of Interleukin-5

Novel isoflavones were found to be potent inhibitors of interleukin-5 (Il-5). 5-Benzyloxy-3-(4-hydroxyphenyl)-4H-chromen-4-one (2a, 87.8% inhibition at 50 microM, IC50 = 15.3 microM) was initially identified as a potent inhibitor of IL-5. Its activity was comparable to that of budesonide or sophoricoside (1a). The benzyloxy group appeared to be critical for the enhancement of the IL-5 inhibitory activity. To identify the role of this hydrophobic moiety, 5-cyclohexylmethoxy (2d), 7-cyclohexylmethoxy (2e), 5-cyclohexylethoxy (2f), 5-cyclohexylpropoxy (2g), 5-(2-methylpropoxy) (2h), 5-(3-methylbutoxy) (2i), 5-(4-methylpentoxy) (2j) and 5-(2-ethylbutoxy) (2k) analogs were prepared and tested for their effects on the bioactivity of IL-5. Compounds 2d (IC50 = 5.8 microM), 2e (IC50 = 4.0 microM) and 2j (IC50 = 7.2 microM) exhibited the most potent activities. Considering the cLog P values of compounds 2 and the different three dimensional structures of 2d and 2e, the alkoxy group on ring A contributed to their cell permeability for the enhancement of activity, rather than playing a role in the ligand motif binding to the receptor. The optimum alkoxy group should be one that provides cLog P values of compounds 2 in the range of 4.13 to 4.39.

The role of the hydrophobic group on ring A of chalcones in the inhibition of interleukin-5

Novel chalcones were found as potent inhibitors of interleukin-5 (11-5). 1-(6-Benzyloxy-2-hydroxyphenyl)-3-(4-hydroxyphenyl)propenone (2a, 78.8% inhibition at 50 microM, IC50 = 25.3 microM) was initially identified as a potent inhibitor of IL-5. This activity is comparable to that of budesonide or sophoricoside (1a). The benzyloxy group appears to be critical for the enhancement of the IL-5 inhibitory activity. To identify the role of this hydrophobic moiety, cyclohexyloxy (2d), cyclohexylmethoxy (2c), cyclohexylethoxy (2e), cyclohexylpropoxy (2f), 2-methylpropoxy (2g), 3-methylbutoxy (2h), 4-methylpentoxy (2i), and 2-ethylbutoxy (2j) analogs were prepared and tested for their effects on IL-5 bioactivity. Compounds 2c (IC50 = 12.6 microM), 2d (IC50 = 12.2 microM), and 2i (IC50 = 12.3 microM) exhibited the most potent activity. Considering the cLog P values of 2, the alkoxy group contributes to the cell permeability of 2 for the enhancement of activity, rather than playing a role in ligand motif binding to the receptor. The optimum alkoxy group in ring A of 2 should be one that provides the cLog P of 2 in the range of 4.22 to 4.67.

Histamine type 1 receptor deficiency reduces airway inflammation in a murine asthma model

BACKGROUND

Histamine plays an important role in immediate and late immune responses. The histamine type 1 (H1) receptor is expressed on several immune cell populations, but its role in a murine model of asthma remains unclear. The present study evaluated the role of histamine H1 receptors in airway allergic inflammation by comparing the development of bronchial asthma in histamine H1 receptor gene knockout (H1RKO) and wild-type mice.

METHODS

H1RKO and wild-type mice were sensitized by intraperitoneal injection of ovalbumin (OVA) or saline, and then challenged with aerosolized OVA or saline. Ventilatory timing in response to inhaled methacholine was measured, and samples of blood, bronchoalveolar lavage, and lung tissues were taken 24 h after the last OVA challenge.

RESULTS

OVA-treatedwild-type mice showed significantly increased airway eosinophilic infiltration, and airway response to methacholine compared to OVA-treated H1RKO mice. The serum level of immunoglobulin E and levels of interleukin (IL)-4, IL-5, IL-13, and TGF-beta1 in bronchoalveolar lavage fluid were lower in OVA-treated H1RKO mice than in OVA-treated wild-type mice, but there was no significant difference in interferon-gamma expression. Overall, deletion of histamine H1 receptors reduced allergic responses in a murine model of bronchial asthma.

CONCLUSION

Histamine plays an important role via H1 receptors in the development of T helper type 2 responses to enhance airway inflammation.

Treatment of cockroach allergen asthma model with imatinib attenuates airway responses

In the present study it was determined whether a pharmacologic approach to blocking receptor tyrosine kinase-mediated activation during allergic airway responses could be beneficial. To examine these responses, allergic mice were given a single oral dose of imatinib at clinically relevant concentrations, ranging from 0.05 to 50 mg/kg, by oral gavages just before allergen challenge. The reduction in the allergen-induced responses was significant and centered on reducing overall inflammation as well as pulmonary cytokine levels. In particular, the treatment of the mice with imatinib significantly attenuated airway hyperreactivity and peribronchial eosinophil accumulation, and significantly reduced Th2 cytokines, interleukin-4 and interleukin-13. In addition, chemokines previously associated with allergen-induced pulmonary disease, CCL2, CCL5, and CCL6, were significantly reduced in the lungs of the imatinib-treated animals. Together these data demonstrate that the pharmacologic inhibitor imatinib may provide a clinically attractive therapy for allergic, asthmatic responses.

Relationship of airway symptoms from chemicals to capsaicin cough sensitivity in atopic subjects

BACKGROUND

It is well known that some patients with allergy complain of airway symptoms from chemicals (ASCs) and strong odours. However, the importance of such information for the treatment of allergic disease is not known. Such symptoms in non-allergic patients have previously been shown to be related to increased sensory nerve reactivity, which is expressed as increased cough sensitivity to inhaled capsaicin.

OBJECTIVE

The aim of this study was to examine ASC in atopic patients and relate it to cough reaction to capsaicin inhalation.

MATERIALS AND METHODS

Fifty-seven consecutively chosen, skin prick-positive patients with symptoms of the upper and/or lower airways completed a questionnaire concerning ASC. The patients were then divided into two groups, those with and those without such symptoms. Both groups were provoked with inhaled capsaicin in three increments and compared with 73 healthy control subjects.

RESULTS

Out of 57 atopic patients, 34 reported ASC agents and 23 did not. The patients with ASC were older (P<0.01) and coughed significantly more on capsaicin provocation (P<0.001), but did not differ from them with respect to the allergic disease or its treatment or to smoking habits. Patients with atopy but without ASC did not differ from healthy controls with regard to sensitivity to capsaicin inhalation. The scored degree of ASC was directly related to the number of coughs during the capsaicin provocation.

CONCLUSION

ASC in atopic patients are related to increased airway sensory nerve reactivity. There is still no explanation for this in certain patients with atopy, but age may be a confounding factor.

The tachykinin NK1 receptor is crucial for the development of non-atopic airway inflammation and hyperresponsiveness

Mast cell activation, bronchoconstriction, inflammation and airway hyperreactivity are prominent features of non-atopic hypersensitivity reactions in mouse airways. We studied the role of tachykinin receptors in mice that were skin-sensitized with dinitrofluorobenzene (or vehicle) and challenged intranasally with dinitrobenzene sulfonic acid. Tachykinin NK1 receptor blockade, by treatment with the antagonist RP67580, or absence of the tachykinin NK1 receptor resulted in a strong reduction in the accumulation of neutrophils in the bronchoalveolar lavage fluid, and in the development of tracheal hyperreactivity in mice 48 h after challenge. In contrast, treatment with the tachykinin NK2 receptor antagonist SR48968 did not affect the dinitrofluorobenzene-induced hypersensitivity reaction. We have previously shown that mast cells play a crucial role in the development of non-atopic asthma. However, we did not observe an inhibitory effect of the tachykinin receptor antagonists or the genetic absence of tachykinin NK1 receptors on mast cell protease release. In conclusion, distal from mast cell activation, the tachykinin NK1 receptor is crucial for the infiltration of pulmonary neutrophils and the development of tracheal hyperreactivity in non-atopic asthma.

Structural requirement of isoflavonones for the inhibitory activity of interleukin-5

Sophoricoside isolated from Sophora japonica is a glycoside of isoflavonone as an inhibitor of interleukin (IL)-5. To identify structural requirements of this isoflavonone for its inhibitory activity against IL-5, isoflavonones, isoflavanones, and their glycosides were prepared and their inhibitory activity was tested against IL-5. Among them, 5-benzyloxy-3-(4-hydroxyphenyl)chromen-4-one (4b, 87.9% inhibition at 50 microM, IC(50)=15.3 microM) shows the most potent activity, comparable with that of sophoricoside. The important structural requirements of these isoflavonone analogs exhibiting the inhibitory activity against IL-5 were recognized as (1) planarity of chromen-4-one ring, (2) existence of phenolic hydroxyl at 4-position of B ring, and (3) introduction of benzyloxy at 5-position, which may act as a bulky group for occupying hydrophobic pocket in putative binding site. However the glucopyranosyl moiety of sophoricoside is not an essential motif for the activity.

Capsaicin cough sensitivity in allergic asthmatic patients increases during the birch pollen season

BACKGROUND

A change in neural responsiveness may occur as the result of allergic inflammation in the lower airways as well as in the upper airways. In the lower airways, capsaicin cough sensitivity is known to reflect sensory neural reactivity.

OBJECTIVE

The aim of this study was to establish whether allergic inflammation changes airway neural sensory reactivity during prolonged allergen exposure.

METHODS

Ten nonsmoking patients with birch pollen-allergic asthma performed a capsaicin inhalation challenge twice, once in the off-pollen season and once during the pollen season. The number of coughs and symptoms induced by capsaicin were recorded and compared with those of healthy control subjects.

RESULTS

The response to capsaicin, expressed as number of coughs, increased in a dose-dependent manner during both tests. Before the season, the response was similar to that of healthy control subjects, but during the pollen season, the reactivity was significantly increased. Variations in forced expiratory volume in 1 second were not significant before and after each challenge, and values did not change during the pollen season as compared with the winter season.

CONCLUSIONS

Sensory reactivity in allergic asthmatic patients may be increased during prolonged allergen exposure as during the pollen season. This finding suggests that allergic inflammation in the lower and/or upper airways may trigger neurogenic mechanisms of significant clinical importance.

Role of bovine chemokines produced by dendritic cells in respiratory syncytial virus-induced T cell proliferation

Respiratory syncytial virus (RSV) has been reported to induce the production of chemokines in the airway epithelia. Dendritic cells (DC) are the most potent antigen-presenting cells. They are located throughout the body and release chemokines in response to inflammation and infection. We have investigated the chemokine profile of bovine DC in response to exposure to bovine RSV (BRSV). Transcripts for several chemokines were detected by RT-PCR, subsequently cloned and expressed, and the products analysed by western blotting. To test the effect of the recombinant chemokines on RSV-induced T cell proliferation, DC were pulsed with BRSV, irradiated, and added to purified bovine CD4(+) T cells from RSV-immune cattle in combination with various concentrations of recombinant chemokines, and the proliferative response of the T cells assessed. Eotaxin was the only chemokine, of those investigated, that specifically enhanced the T cell response to BRSV-pulsed DC. Addition of MIP-1alpha to control wells or to wells containing BRSV-pulsed DC had similar effects, suggesting non-specific stimulation of T cells. RANTES and MIP-3alpha did not seem to influence the proliferative response of T cells co-cultured with BRSV-pulsed DC. Thus, although BRSV induced the production of several chemokines by DC, only eotaxin promoted a BRSV specific CD4(+) T cell proliferative response.

Effect of suplatast tosilate on airway hyperresponsiveness and inflammation in asthma patients

Because eosinophilic airway inflammation is a characteristic of bronchial asthma, the treatment of such inflammation is important in the management of this disease. Suplatast tosilate is a novel anti-asthma drug that suppresses eosinophil proliferation and infiltration through selective inhibition of Th2 cytokine synthesis. We investigated the effect of oral suplatast tosilate therapy in patients with mild and moderate asthma. Twenty-eight asthma patients were randomized into two groups with or without suplatast tosilate treatment (100 mg t.i.d. for 28 days). We examined the blood eosinophil counts, eosinophilic cationic protein level, sputum eosinophil count, exhaled nitric oxide level, and airway responsiveness before and after treatment. In patients treated with suplatast tosilate, the eosinophil count in the blood and sputum was significantly decreased after treatment, while there was no such change in the patients without suplatast treatment. The exhaled nitric oxide level and airway responsiveness (measured using an Astograph) were also decreased after treatment with suplatast tosilate, while there were no significant changes in patients without suplatast tosilate. These results strongly suggest that oral administration of suplatast tosilate suppresses airway hyperresponsiveness in asthma patients by reducing eosinophilic inflammation in the airways.

A3 receptors mediate rapid inflammatory cell influx into the lungs of sensitized guinea-pigs

BACKGROUND

Inhaled adenosine causes bronchoconstriction in asthmatics and may modulate inflammatory cell activity. Elevated adenosine levels occur in the lungs after antigen challenge of asthmatics.

OBJECTIVES

The aim of this study was to investigate whether the bronchoconstrictor effects of the adenosine derivative, 5'-AMP, were associated with altered migration of inflammatory cells into the airways using a sensitized atopic guinea-pig model previously shown to display a bronchoconstrictor response. Comparisons were made with the effects of inhaled antigen.

METHODS

Airway responses of conscious sensitized guinea-pigs to inhalation exposures of 5'-AMP were determined by whole body plethysmography as the change in specific airway conductance (sGaw). Influx of leucocytes into the airways was determined by bronchoalveolar lavage (BAL).

RESULTS

5'-AMP caused bronchoconstrictor airway responses in sensitized animals. Dose-dependent infiltration of inflammatory cells into the lungs occurred 1 h after 5'-AMP exposure. No bronchoconstriction or cell influx was seen in unsensitized guinea-pigs. Exposure to ovalbumin (OA) also caused influx of inflammatory cells. Twenty-four hours after an OA exposure, 5'-AMP produced no bronchoconstriction. The P1-receptor antagonists, 8-PT and 8-SPT, inhibited the 5'-AMP-induced bronchoconstriction, indicating that the bronchoconstriction seen in sensitized animals is mediated by A1 or A2 receptors. They had no effect on the cell influx, whereas the A3 antagonist, MRS-1220, significantly inhibited cellular infiltration, suggesting mediation through A3 receptors. At 24 h after an OA challenge and accompanying the cellular influx, there was airway hyper-responsiveness to the bronchoconstriction by histamine. In contrast, no hyper-responsiveness to histamine was seen 1 h after 3 mM or 24 h after 300 mM 5'-AMP.

CONCLUSIONS

5'-AMP caused a rapid migration of eosinophils and macrophages into the airways only in sensitized guinea-pigs, and this was blocked by the A3 antagonist MRS-1220. This was not associated with bronchial hyper-reactivity to histamine.

Complement-dependent immune complex-induced bronchial inflammation and hyperreactivity

Bronchoconstriction responses in the airway are caused by multiple insults and are the hallmark symptom in asthma. In an acute lung injury model in mice, IgG immune complex deposition elicited severe airway hyperreactivity that peaked by 1 h, was maintained at 4 h, and was resolved by 24 h. The depletion of complement with cobra venom factor (CVF) markedly reduced the hyperreactive airway responses, suggesting that complement played an important role in the response. Blockade of C5a with specific antisera also significantly reduced airway hyperreactivity in this acute lung model. Complement depletion by CVF treatment significantly reduced tumor necrosis factor and histamine levels in bronchoalveolar lavage fluids, correlating with reductions in airway hyperreactivity. To further examine the role of specific complement requirement, we initiated the immune complex response in C5-sufficient and C5-deficient congenic animals. The airway hyperreactivity response was partially reduced in the C5-deficient mice. Complement depletion with CVF attenuated airway hyperreactivity in the C5-sufficient mice but had a lesser effect on the airway hyperreactive response and histamine release in bronchoalveolar lavage fluids in C5-deficient mice. These data indicate that acute lung injury in mice after deposition of IgG immune complexes induced airway hyperreactivity that is C5 and C5a dependent.

Neurokinin mediation of edema and inflammation

The aim of this article is to furnish a brief review of the role played by neurokinins in the inflammatory process. Further attention is given to the mechanisms, as well as to the receptor subtypes involved in neurokinin-mediated inflammation, in an attempt to clarify the participation of neurokinins in different models of acute and chronic inflammation. The involvement of SP, NKA and NKB is also examined in relation to the major signs of inflammation, including edema formation, protein plasma extravasation and vasodilatation. Finally, we provide a general overview on the potential clinical applications of neurokinin antagonists, along with the involvement of neurokinins in human diseases.

Neuropeptide-induced chemotaxis of eosinophils in pulmonary diseases

Eosinophilic lung diseases include various disease entities, and the incidence of pulmonary infiltration with eosinophilia is on the rise. Because eosinophils, well known as inflammatory cells, respond to peripheral neuropeptides in vitro and in vivo, and these peptides are also present in human airway nerves, their interactions are thought to play a major role in the initiation and perpetuation of inflammatory lung diseases. This article reviews the current literature on eosinophil biology and interactions of these cells with the neuroendocrine system. Also, implications of tachykinins and other neuropeptides in eosinophilic pulmonary diseases is discussed based on recently investigated mechanisms. Eosinophils and sensory nerves most likely influence each other in a two-directional way in the pathogenesis of pulmonary diseases. Although release of sensory neuropeptides is involved in most conditions of airway hyperresponsiveness, increased bronchial resistance, and lung eosinophilia, the role of these nervous system-derived mediators in pulmonary diseases may be underestimated.

Neurokinin B- and specific tachykinin NK(3) receptor agonists-induced airway hyperresponsiveness in the guinea-pig

1. The aim of this study was to determine whether neurokinin B (NKB) or specific agonists of tachykinin NK(3) receptors, [MePhe(7)]NKB and senktide, were able to induce airway hyperresponsiveness in guinea-pigs. The effects of these compounds were compared to those of substance P (SP), neurokinin A (NKA) and the preferential tachykinin NK(1) ([Sar(9), Met(0(2))(11)]SP) or NK(2) ([betaAla(8)]NKA (4-10)) receptor agonists. 2. In guinea-pigs pretreated with phosphoramidon (10(-4) M aerosol for 10 min) and salbutamol (8.7x10(-3) M for 10 min), all tachykinins administrated by aerosol (3x10(-7) to 10(-4) M) induced airway hyperresponsiveness 24 h later, displayed by an exaggerated response to the bronchoconstrictor effect of acetylcholine (i.v.). The rank order of potency was: [betaAla(8)]NKA (4-10)>NKA=NKB=senktide=[MePhe(7)]NKB=[Sar(9),Met(0(2))(11)]SP>SP. 3. Airway hyperresponsiveness induced by [MePhe(7)]NKB was prevented by the tachykinin NK(3) (SR 142801) and NK(2) (SR 48968) receptor antagonists. 4. Bronchoconstriction induced by tachykinins administered by aerosol was also determined. SP, NKA, NKB and the tachykinin NK(1) and NK(2) receptor agonist induced bronchoconstriction. The rank order of potency was: NKA=[betaAla(8)]NKA (4-10)>NKB=SP=[Sar(9), Met(0(2))(11)]SP. Under similar conditions, and for concentrations which induce airway hyperresponsiveness, senktide and [MePhe(7)]NKB failed to induce bronchoconstriction. 5. It is concluded that tachykinin NK(3)-receptor stimulation can induce airway hyperresponsiveness and that this effect is not related to the ability of tachykinins to induce bronchoconstriction.

Asthma, oxidant stress, and diet

It has been suggested that the increased prevalence of atopy and asthma observed in many developed countries over the past 30 y is in part the result of a decrease in the incidence and severity of early childhood infections. The immunologic consequence of this phenomenon has been the expansion of T-lymphocyte populations away from the T-helper 1 (Th1) subset and in the direction of the Th2 subset. This leads to the creation of a cytokine-mediated propensity for the development of an intense inflammatory response in the airways, resulting in oxidative stress, airway tissue injury, and the development of atopy and asthmatic symptomatology. Over this same period, there has been a decreased intake of dietary substances that contribute to antioxidant defense, and this appears to have contributed to the rise of atopy and asthma. Studies evaluating the efficacy of these antioxidant substances in the prevention of asthma and as adjuvants in the treatment of asthma are reviewed, and suggestions are made for the direction of future studies.

Interleukin-1beta-induced hyperresponsiveness to [Sar9,Met(O2)11]substance P in isolated human bronchi

Interleukin-1beta has been reported to induce airway hyperresponsiveness in several animal models. In this study, we have investigated whether interleukin-1beta was able to potentiate the contractions of human isolated small bronchi (internal diameter < or = 1 mm) provoked by a specific tachykinin NK1 receptor agonist, [Sar9,Met(O2)11]substance P. Pre-incubation of human isolated small bronchi with interleukin-1beta (10 ng/ml, in Krebs-Henseleit solution, at 21 degrees C for 15 h) potentiated the contractile response to [Sar9,Met(O2)11]substance P. It also increased the [Sar9,Met(O2)11]substance P-induced release of thromboxane B2, the stable metabolite of thromboxane A2. Indomethacin (10(-6) M), a non-specific cyclooxygenase inhibitor, or GR 32191 ((1R-(1alpha(Z)),2beta,3beta,5alpha))-(+)-7-(5-(((1,1' -biphenyl)-4-yl)-methoxy)-3-hydroxy-2-(1-piperidinyl)cyclopentyl)-4-hept enoic acid, hydrochloride) (10(-6) M), a prostanoid TP-receptor antagonist, blocked the contractions induced by [Sar9,Met(O2)11]substance P both in control experiments and after interleukin-1beta pre-treatment, indicating that prostanoids and thromboxane receptors are directly implicated in the [Sar9,Met(O2)11]substance P-induced contractile response. The thromboxane mimetic U-46619 (10(-8)-10(-6) M) (9,11-dideoxy-11alpha,9alpha-epoxymethano-prostaglandin F2alpha)-induced contractions of human isolated small bronchi were not enhanced by interleukin-1beta pre-treatment, suggesting that no up-regulation of thromboxane receptors occurred. Furthermore, the cyclooxygenase-2 inhibitor CGP 28238 (6-(2,4-difluorophenoxy)-5-methyl-sulfonylamino-1-indanon e) (10(-6) M) had no direct effect on [Sar9,Met(O2)11]substance P-provoked contractions, but inhibited the interleukin-1beta-induced potentiation of [Sar9,Met(O2)11]substance P response. In conclusion, our results show that interleukin-1beta pre-treatment is able to potentiate the contractions of isolated human small bronchi provoked by [Sar9,Met(O2)11]substance P both by increasing prostanoid synthesis and by inducing a cyclooxygenase-2 pathway.