Anti-tumor necrosis factor-alpha antibody treatment reduces pulmonary inflammation and methacholine hyper-responsiveness in a murine asthma model induced by house dust

Therapeutic Potential of Combining IL-6 and TNF Blockade in a Mouse Model of Allergic Asthma

Combined anti-cytokine therapy is a promising therapeutic approach for uncontrolled steroid-resistant asthma. In this regard, simultaneous blockade of IL-4 and IL-13 signaling by Dupilumab (anti-IL-4Ra monoclonal antibody) was recently approved for severe eosinophilic asthma. However, no therapeutic options for neutrophilic asthma are currently available. Recent advances in our understanding of asthma pathogenesis suggest that both IL-6 and TNF may represent potential targets for treatment of severe neutrophilic asthma. Nevertheless, the efficacy of simultaneous pharmacological inhibition of TNF and IL-6 in asthma was not yet studied. To evaluate the potency of combined cytokine inhibition, we simultaneously administrated IL-6 and TNF inhibitors to BALB/c mice with HDM-induced asthma. Combined IL-6/TNF inhibition, but not individual blockade of these two cytokines, led to complex anti-inflammatory effects including reduced Th2-induced eosinophilia and less prominent Th17/Th1-mediated neutrophilic infiltrate in the airways. Taken together, our results provide evidence for therapeutic potential of combined IL-6/TNF inhibition in severe steroid-resistant asthma.

Muc5ac Production Inhibited by Decreased lncRNA H19 via PI3K/Akt/NF-kB in Asthma

Introduction

LncRNAs play important roles in multiple diseases including asthma, while there are a few reports on the role of lncRNA H19 about asthma. This study aimed to investigate the roles and mechanisms of lncRNA H19 in asthma.

Methods

We detected lncRNA H19 and Muc5ac mRNA by establishing a murine asthma model and an in vitro inflammation model. Regulatory roles of lncRNA H19 in asthma were explored by lncRNA H19 overexpression or knockdown in vitro. To study its mechanisms, we detect p-NF-κB and p-Akt expression, and treated 16-HBE cells with inhibitors of PI3K. To study regulatory effects of miR-675-3p on Muc5ac, miR-675-3p mimics and inhibitors were respectively transfected into 16-HBE cells.

Results

Firstly, we established a murine asthma model and an in vitro inflammation model. We found that lncRNA H19 expression was decreased, while Muc5ac mRNA was increased in lung tissues of murine asthma model and in the in vitro inflammation model. lncRNA H19 overexpression increased Muc5ac mRNA expression and lncRNA H19 knockdown decreased Muc5ac mRNA expression in 16-HBE cells. Moreover, lncRNA H19 overexpression further increased Muc5ac expression in TNFα-induced in vitro inflammation model. lncRNA H19 knockdown decreased p-Akt and p-NF-κB expression. Inhibitors of PI3K abolished Muc5ac induced by lncRNA H19 overexpression. Although miR-675-3p was increased by lncRNA H19 overexpression, it had no regulatory effects on Muc5ac expression.

Discussion

These results demonstrated that lncRNA H19 positively regulates Muc5ac expression through PI3K/Akt /NF-κB pathway in the in vitro inflammation model. Therefore, this study indicated that decreased lncRNA H19 in asthma might play a protective role relieving mucus overproduction, and lncRNA H19 might be a potential target for asthma treatment.

Pulmonary injury and oxidative stress in rats induced by inhaled sulfur mustard is ameliorated by anti-tumor necrosis factor-α antibody

Sulfur mustard (SM) is a bifunctional alkylating agent that causes severe injury to the respiratory tract. This is accompanied by an accumulation of macrophages in the lung and the release of the proinflammatory cytokine, tumor necrosis factor (TNF)α. In these studies, we analyzed the effects of blocking TNFα on lung injury, inflammation and oxidative stress induced by inhaled SM. Rats were treated with SM vapor (0.4 mg/kg) or air control by intratracheal inhalation. This was followed 15-30 min later by anti-TNFα antibody (15mg/kg, i.v.) or PBS control. Animals were euthanized 3 days later. Anti-TNFα antibody was found to blunt SM-induced peribronchial edema, perivascular inflammation and alveolar plasma protein and inflammatory cell accumulation in the lung; this was associated with reduced expression of PCNA in histologic sections and decreases in BAL levels of fibrinogen. SM-induced increases in inflammatory proteins including soluble receptor for glycation end products, its ligand, high mobility group box-1, and matrix metalloproteinase-9 were also reduced by anti-TNFα antibody administration, along with increases in numbers of lung macrophages expressing TNFα, cyclooxygenase-2 and inducible nitric oxide synthase. This was correlated with reduced oxidative stress as measured by expression of heme oxygenase-1 and Ym-1. Together, these data suggest that inhibiting TNFα may represent an efficacious approach to mitigating acute lung injury, inflammatory macrophage activation, and oxidative stress induced by inhaled sulfur mustard.

Novel Anti-Cytokine Strategies for Prevention and Treatment of Respiratory Allergic Diseases

Asthma is a heterogeneous inflammatory disease characterized by airflow obstruction, wheezing, eosinophilia and neutrophilia of the airways. Identification of distinct inflammatory patterns characterizing asthma endotypes led to the development of novel therapeutic approaches. Cytokine or cytokine receptor targeting by therapeutic antibodies, such as anti-IL-4 and anti-IL-5, is now approved for severe asthma treatment. However, the complexity of cytokine networks in asthma should not be underestimated. Inhibition of one pro-inflammatory cytokine may lead to perturbed expression of another pro-inflammatory cytokine. Without understanding of the underlying mechanisms and defining the molecular predictors it may be difficult to control cytokine release that accompanies certain disease manifestations. Accumulating evidence suggests that in some cases a combined pharmacological inhibition of pathogenic cytokines, such as simultaneous blockade of IL-4 and IL-13 signaling, or blockade of upstream cytokines, such as TSLP, are more effective than single cytokine targeting. IL-6 and TNF are the important inflammatory mediators in the pathogenesis of asthma. Preliminary data suggests that combined pharmacological inhibition of TNF and IL-6 during asthma may be more efficient as compared to individual neutralization of these cytokines. Here we summarize recent findings in the field of anti-cytokine therapy of asthma and discuss immunological mechanisms by which simultaneous targeting of multiple cytokines as opposed to targeting of a single cytokine may improve disease outcomes.

LncRNA-AK149641 associated with airway inflammation in an OVA-induced asthma mouse model

Asthma is defined as a heterogeneous disease, usually characterized by chronic airway inflammation. Long noncoding RNAs (lncRNAs) play important roles in various biological processes. To know more about the relationships between lncRNAs and asthma, gene microarray analysis was performed to screen differentially expressed lncRNAs between the lung tissue of ovalbumin (OVA) mice and control mice. Further studies showed that downregulating differentially expressed lncRNA-AK149641 by adeno-associated virus 6 (AAV6) in OVA mice inhibited airway inflammation, with improved airway compliance and resistance, diminished infiltration of inflammatory cells, as well as less secretions of mucus, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). Moreover, the activity of nuclear factor-kappa B (NF-κB) in the lung tissue was reduced after downregulating lncRNA-AK149641. In conclusion, we proposed that downregulation of lncRNA-AK149641 attenuated the airway inflammatory response in an OVA-induced asthma mouse model, probably in association with modulation of the NF-κB signaling pathway.

Panax notoginseng saponin R1 modulates TNF-α/NF-κB signaling and attenuates allergic airway inflammation in asthma

BACKGROUD

Panax notoginseng saponin R1 (PNS-R1) is one of the most important chemical monomers derived from the panax notoginseng, and our previous study found that PNS-R1 reduced glucocorticoid-induced apoptosis in asthmatic airway epithelial cells. Thus, in this study, we explored the effects of the PNS-R1 on inflammation of allergic asthma.

METHODS

The asthmatic mice were administered 15 mg/kg PNS-R1 by intraperitoneal injection three days before sensitized to OVA. The effects of PNS-R1 on asthmatic mice were detected by airway hyperresponsiveness, inflammation, mucus hypersecretion and inflammatory cytokines such as interleukin (IL)-13, IL-4, IL-5, IL-8 and tumor necrosis factor (TNF)-α were studied. We also treated human bronchial epithelial cells (16HBE) with house dust mites (HDM) and then detected the secretion of cellular inflammatory factors (IL-13 and TNF-α). Western blot and immunofluorescence were used to examine the effect of PNS-R1 on TNF-α/NF-κB pathway. TNF-α/NF-κB/IKK signal pathway activator was used in PNS-R1-treated asthmatic mice.

RESULTS

PNS-R1 significantly reduced the airway inflammatory, mucus secretion and hyperresponsiveness in asthma model. It also reduced the levels of IL-13, IL-4, IL-5 and IL-8 in bronchoalveolar lavage fluid (BALF) and IgE and OVA-specific IgE in serum for asthma mice. PNS-R1 reduced IL-13 and TNF-α secretion in HDM-treated 16HBE cells. In addition, PNS-R1 suppressed TNF-α/NF-κB pathway in both asthmatic mice and 16HBE. Activation of NF-kB pathway reversed the therapeutic effect of PNS-R1 on asthmatic mice.

CONCLUSION

The results indicated that PNS-R1 effectively suppresses allergic airway inflammation of asthma partly through TNF-α/NF-κB pathway. PNS-R1 may play a potential role in allergic asthma treatment in the future.

Antiallergic Effect of Hizikia fusiformis in an Ovalbumin-Induced Allergic Rhinitis Mouse Model

Objectives

The extract of Hizikia fusiformis is known to exhibit anticancer, antiatopic and antioxidant activities. We aimed to investigate the extract of H. fusiformis on allergic rhinitis inflammation in a mouse model.

Methods

The 4-week-old BALB/c mice were randomly assigned into four groups: group A, control group (n=9); group B, allergic rhinitis group (n=10); group C (n=10) received 300 mg/kg of H. fusiformis during nasal challenging period; group D (n=10) received 600 mg/kg of H. fusiformis during general sensitization period and 300 mg/kg of H. fusiformis during nasal challenging period. Allergic inflammation was made with ovalbumin (OVA) and alum then challenged intranasally with OVA. H. fusiformis was intraperitoneally administered 3 hours before the OVA administration. Allergic symptom score and the levels of immunoglobulin G₁ (IgG₁), IgG_2a, OVA-specific IgE antibodies, levels of cytokines in the nasal mucosa and in spleen cell culture supernatant, such as tumor necrosis factor alpha (TNF-α), interleukin 4 (IL-4), IL-5, IL-13, and IL-10 were assessed. The percentage of regulatory T cell was analyzed by flow cytometry. Eosinophilic infiltration and goblet cell hyperplasia were also evaluated.

Results

H. fusiformis administered groups C and D showed significant inhibitory effects on nasal symptoms, IL-13 mRNA expression and eosinophil infiltration/goblet cell hyperplasia in the nasal tissue; OVA-specific IgE production in serum (P<0.05). In group D, H. fusiformis treatment downregulated IL-4, IL-5, IL-13, TNF-α, and IL-10 cytokine expression in splenocyte culture as well as significantly decreased IgG_2a, IgG₁ levels in serum compared with group B (P<0.05). However, the expressions of IL-5, interferon-γ and forkhead box P3 mRNA did not change in groups C and D.

Conclusion

H. fusiformis could induce antiallergic inflammation by suppressing the T-helper type 2 cytokine production (IL-13) locally and systemically, OVA-specific IgE formation, goblet cell hyperplasia, and eosinophilic infiltration in a mouse model of allergic rhinitis. Thus, H. fusiformis could be considered as a potential therapeutic agent in treating allergic rhinitis.

Lung responses in murine models of experimental asthma: Value of house dust mite over ovalbumin sensitization

Ovalbumin (OVA) sensitization has limitations in modelling asthma. Thus, we examined the value of allergic sensitization using a purified natural allergen, house dust mite (HDM), over the sensitization performed with OVA. Mice were sham-treated, or sensitized with OVA- or HDM with identical chronology. Airway resistance, tissue damping and elastance were assessed under control conditions and after challenging the animals with methacholine (MCh) and the specific allergen. Inflammatory profile of the bronchoalveolar lavage fluid was characterized and lung histology was performed. While no difference in the lung responsiveness to the specific allergen was noted, hyperresponsiveness to MCh was observed only in the HDM-sensitized animals in the lung peripheral parameters. Lung inflammation differed between the models, but excessive bronchial smooth muscle remodelling occurred only with OVA. In conclusion, we demonstrate that a purified natural allergen offers a more relevant murine model of human allergic asthma by expressing the key features of this chronic inflammatory disease both in the lung function and structure.

Anti-TNFα therapy in inflammatory lung diseases

Increased levels of tumor necrosis factor (TNF) α have been linked to a number of pulmonary inflammatory diseases including asthma, chronic obstructive pulmonary disease (COPD), acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), sarcoidosis, and interstitial pulmonary fibrosis (IPF). TNFα plays multiple roles in disease pathology by inducing an accumulation of inflammatory cells, stimulating the generation of inflammatory mediators, and causing oxidative and nitrosative stress, airway hyperresponsiveness and tissue remodeling. TNFα-targeting biologics, therefore, present a potentially highly efficacious treatment option. This review summarizes current knowledge on the role of TNFα in pulmonary disease pathologies, with a focus on the therapeutic potential of TNFα-targeting agents in treating inflammatory lung diseases.

Mucosal expression of DEC-205 targeted allergen alleviates an asthmatic phenotype in mice

Considering the rising incidence of allergic asthma, the symptomatic treatments that are currently applied in most cases are less than ideal. Specific immunotherapy is currently the only treatment that is able to change the course of the disease, but suffers from a long treatment duration. A gene based immunization that elicits the targeting of allergens towards dendritic cells in a steady-state environment might have the potential to amend these difficulties. Here we used a replication deficient adenovirus to induce the mucosal expression of OVA coupled to a single-chain antibody against DEC-205. A single intranasal vaccination was sufficient to mitigate an OVA-dependent asthmatic phenotype in a murine model. Invasive airway measurements demonstrated improved lung function after Ad-Dec-OVA treatment, which was in line with a marked reduction of goblet cell hyperplasia and lung eosinophilia. Furthermore OVA-specific IgE titers and production of type 2 cytokines were significantly reduced. Together, the here presented data demonstrate the feasibility of mucosal expression of DEC-targeted allergens as a treatment of allergic asthma.

A human monoclonal anti-TNF alpha antibody (adalimumab) reduces airway inflammation and ameliorates lung histology in a murine model of acute asthma

BACKGROUND

A few experimental studies related to asthma have unveiled the beneficial effects of TNF alpha blocking agents on the airway histology, cytokine levels in bronchoalveolar lavage and bronchial hyper-responsiveness. In the current study, we aimed to assess the effect of adalimumab on the inflammation and histology of asthma in a murine model.

METHOD

Twelve-week-old BALB/c (H-2d/d) female rats (n=18) were allocated into three groups, including (group I) control (phosphate-buffered saline was implemented), (group II) asthma induced with OVA (n=6), and (group III) asthma induced with OVA+treated with adalimumab (n=6). Rats were executed on the 28th day of the study. The lung samples were fixed in 10% neutral buffered formalin. Lung parenchyma, alveolus, peribronchial and perivascular inflammation were assessed. Lung pathological scoring was performed.

RESULT

Severity of lung damage was found to be reduced significantly in the asthma induced with OVA+treated with adalimumab group. When compared with the untreated group, adalimumab significantly reduced the inflammatory cells around the bronchi and bronchioles, and reduced inflammation of the alveolar wall and alveolar wall thickness as well (median score=1, p=0.52). Peribronchial smooth muscle hypertrophy and oedema were significantly reduced after adalimumab administration.

CONCLUSION

Adalimumab (a human monoclonal anti-TNF alpha antibody) therapy significantly reduced the severity of lung damage by decreasing cellular infiltration and improvement on the lung histology in a murine model of acute asthma.

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.

Novel insights into mechanisms of food allergy and allergic airway inflammation using experimental mouse models

Over the last decades, considerable efforts have been undertaken in the development of animal models mimicking the pathogenesis of allergic diseases occurring in humans. The mouse has rapidly emerged as the animal model of choice, due to considerations of handling and costs and, importantly, due to the availability of a large and increasing arsenal of genetically modified mouse strains and molecular tools facilitating the analysis of complex disease models. Here, we review latest developments in allergy research that have arisen from in vivo experimentation in the mouse, with a focus on models of food allergy and allergic asthma, which constitute major health problems with increasing incidence in industrialized countries. We highlight recent novel findings and controversies in the field, most of which were obtained through the use of gene-deficient or germ-free mice, and discuss new potential therapeutic approaches that have emerged from animal studies and that aim at attenuating allergic reactions in human patients.

A2B adenosine receptor expression by myeloid cells is proinflammatory in murine allergic-airway inflammation

Asthma is a chronic condition with high morbidity and healthcare costs, and cockroach allergens are an established cause of urban pediatric asthma. A better understanding of cell types involved in promoting lung inflammation could provide new targets for the treatment of chronic pulmonary disease. Because of its role in regulating myeloid cell-dependent inflammatory processes, we examined A(2B) R expression by myeloid cells in a cockroach allergen model of murine asthma-like pulmonary inflammation. Both systemic and myeloid tissue-specific A(2B) R deletion significantly decreased pulmonary inflammatory cell recruitment, airway mucin production, and proinflammatory cytokine secretion after final allergen challenge in sensitized mice. A(2B) R deficiency resulted in a dramatic reduction on Th2-type airways responses with decreased pulmonary eosinophilia without augmenting neutrophilia, and decreased lung IL-4, IL-5, and IL-13 production. Chemokine analysis demonstrated that eotaxin 1 and 2 secretion in response to repeated allergen challenge is myeloid cell A(2B) R dependent. In contrast, there were no differences in the levels of the CXC chemokines keratinocyte-derived chemokine and MIP-2 in the myeloid cell A(2B) R-deficient mice, strengthening A(2B) R involvement in the development of Th2-type airways inflammation. Proinflammatory TNF-α, IFN-γ, and IL-17 secretion were also reduced in systemic and myeloid tissue-specific A(2B) R deletion mouse lines. Our results demonstrate Th2-type predominance for A(2B) R expression by myeloid cells as a mechanism of development of asthma-like pulmonary inflammation.

Biphasic late airway hyperresponsiveness in a murine model of asthma

BACKGROUND

Nonspecific airway hyperresponsiveness (AHR) is one of the cardinal features of bronchial asthma. Early AHR is caused by chemical mediators released from pulmonary mast cells activated in an IgE-dependent way. However, the mechanism of late AHR remains unclear.

METHODS

Features of airway allergic inflammation were analyzed, including antigen-induced AHR, using a murine model of asthma. The model was suitable for examining the sequential early molecular events occurring after the initial airway exposure to antigen.

RESULTS

AHR increased at 10-12 h after airway challenge, followed by the second-phase response, which was larger and broader in resistance at 18-30 h. Pretreatment of sensitized animals with anti-tumor necrosis factor (TNF) before airway challenge or induction of allergic asthma in TNF(-/-) mice resulted in abrogation of the first-phase late AHR. Intratracheal instillation of TNF induced a single peak of AHR at 10 h. IgE and IgG immune complexes induced the development of the first-phase late AHR by TNF production. Pretreatment with cytosolic phospholipase inhibitor and 5-lipoxygenase inhibitors abolished the first-phase late AHR as well as the leukotriene B(4) levels in the airway. CpG-oligodeoxynucleotide (ODN) pretreatment reduced airway levels of Th2 cytokines, eosinophil infiltration and second-phase late AHR. However, CpG-ODN did not reduce TNF levels or the magnitude of first-phase late AHR.

CONCLUSION

Biphasic late AHR occurs in a murine model of asthma. First- and second-phase late AHR is caused by TNF and Th2 response, respectively.

Role of TNFR1 in the innate airway hyperresponsiveness of obese mice

The purpose of this study was to examine the role of tumor necrosis factor receptor 1 (TNFR1) in the airway hyperresponsiveness characteristic of obese mice. Airway responsiveness to intravenous methacholine was measured using the forced oscillation technique in obese Cpe(fat) mice that were either sufficient or genetically deficient in TNFR1 (Cpe(fat) and Cpe(fat)/TNFR1(-/-) mice) and in lean mice that were either sufficient or genetically deficient in TNFR1 [wild-type (WT) and TNFR1(-/-) mice]. Compared with lean WT mice, Cpe(fat) mice exhibited airway hyperresponsiveness. Airway hyperresponsives was also greater in Cpe(fat)/TNFR1(-/-) than in Cpe(fat) mice. Compared with WT mice, Cpe(fat) mice had increases in bronchoalveolar lavage fluid concentrations of several inflammatory moieties including eotaxin, IL-9, IP-10, KC, MIG, and VEGF. These factors were also significantly elevated in Cpe(fat)/TNFR1(-/-) vs. TNFR1(-/-) mice. Additional moieties including IL-13 were also elevated in Cpe(fat)/TNFR1(-/-) vs. TNFR1(-/-) mice but not in Cpe(fat) vs. WT mice. IL-17A mRNA expression was greater in Cpe(fat)/TNFR1(-/-) vs. Cpe(fat) mice and in TNFR1(-/-) vs. WT mice. Analysis of serum indicated that obesity resulted in systemic as well as pulmonary inflammation, but TNFR1 deficiency had little effect on this systemic inflammation. Our results indicate that TNFR1 is protective against the airway hyperresponsiveness associated with obesity and suggest that effects on pulmonary inflammation may be contributing to this protection.

TNF-α-induces airway hyperresponsiveness to cholinergic stimulation in guinea pig airways

BACKGROUND AND PURPOSE

TNF-α is an inflammatory cytokine implicated in the pathogenesis of asthma and it causes airway inflammation, bronchoconstriction and airway hyperresponsiveness to a number of spasmogens following inhalation.

EXPERIMENTAL APPROACH

We compared contractions of guinea pig isolated trachea incubated with saline or TNF-α for 1, 2 or 4 days to electrical field stimulation (EFS), 5-HT or methacholine. In addition, we compared bronchoconstriction in anaesthetized guinea pigs 6 h after intratracheal instillation of saline or TNF-α to vagal nerve stimulation, i.v. 5-HT or methacholine. Differential counts were performed on the bronchoalvelolar lavage fluid (BALF).

KEY RESULTS

Maximum contractions to methacholine, 5-HT and EFS were not different between freshly prepared and saline-incubated tissues. Exposure to TNF-α concentration-dependently potentiated contractions to 5-HT and EFS, but not methacholine. All contractions were atropine-sensitive, but not hexamethonium-sensitive. 5-HT-evoked contractions were inhibited by ketanserin or epithelial denudation. Only EFS-evoked contractions were tetrodotoxin-sensitive. Vagal stimulation, i.v. 5-HT or MCh caused a significant atropine-sensitive, frequency- and dose-dependent bronchoconstriction and decreased blood pressure similarly in both saline and TNF-α pre-treated animals. TNF-α potentiated the bronchoconstriction to vagal stimulation and 5-HT, but not MCh. The BALF from saline-treated animals contained predominantly macrophages, whereas that from TNF-α-treated animals contained neutrophils.

CONCLUSIONS AND IMPLICATIONS

TNF-α caused airway hyperresponsiveness to nerve stimulation in vivo and increased contractility in vitro. However, responsiveness to MCh was unchanged, suggesting a pre-synaptic action of TNF-α on parasympathetic nerves. TNF-α-induced airway hyperresponsiveness to 5-HT suggested an increased 5-HT(2A) receptor-mediated acetylcholine release from epithelial cells.

Cockroach allergens induce biphasic asthma-like pulmonary inflammation in outbred mice

OBJECTIVES

The aim of this study is to define the kinetics of the pulmonary inflammatory response in cockroach allergen (CRA) sensitized and challenged outbred mice.

METHODS

Asthma-like pulmonary inflammation was induced with three pulmonary exposures to CRA, without the use of adjuvants. Mice were sacrificed at multiple time points and asthma-like pulmonary inflammation quantified.

RESULTS

Several pulmonary parameters showed a pronounced biphasic inflammatory response with an early stage (1.5 hours post challenge) and late stage (24 hours). The initial phase was characterized by the production of multiple inflammatory mediators, including CXC chemokines, and the recruitment of neutrophils to the lung. The number of pulmonary eosinophils decreased in the early phase but quickly rebounded. Both the early and late phases had increases in TNF production in addition to airways hyperreactivity. The model also demonstrated early production of mucin with clearance by 12 hours followed by new accumulation of mucin in the pulmonary epithelial cells. Eotaxins within the lung peaked at about 12 hours and the numbers of eosinophils in the lung remained constant throughout the 48 hours of the study.

CONCLUSIONS

The pulmonary inflammatory parameters in response to a clinically relevant allergen define a biphasic response. These data may be used to investigate the pathogenesis of the disease and develop targeted therapies for the distinct phases.

Mast cells and the development of allergic airway disease

Murine models have highlighted the importance of T-cells and T_H2 cytokines in development of allergen-induced airway disease. In contrast, the role of mast cells for the development of allergic airway disease has been controversial. Recent studies in murine models demonstrate a significant contribution of mast cells during the development of airway hyperresponsiveness and airway inflammation. Furthermore these models have allowed identifying certain mast cell-produced mediators (e.g. histamine and leukotriene B4) to be involved in the recruitment of effector T-cells into the lung. Additionally, mast cell-produced TNF can directly activate T_H2 cells and contribute to the development of allergic airway disease. These new findings demonstrate a complex role of mast cells and their mediators, not only as effector cells, but also during sensitization and development of allergic airway disease. Therefore mast cells and certain mast cell-produced mediators might be an interesting target for the prevention and treatment of allergic asthma.

Reducing LPS content in cockroach allergens increases pulmonary cytokine production without increasing inflammation: a randomized laboratory study

Background

Endotoxins are ubiquitously present in the environment and constitute a significant component of ambient air. These substances have been shown to modulate the allergic response, however a consensus has yet to be reached whether they attenuate or exacerbate asthmatic responses. The current investigation examined whether reducing the concentration of lipopolysaccharide (LPS) in a house dust extract (HDE) containing high concentrations of both cockroach allergens [1] and LPS would attenuate asthma-like pulmonary inflammation.

Methods

Mice were sensitized with CRA and challenged with the intact HDE, containing 182 ng of LPS, or an LPS-reduced HDE containing 3 ng LPS, but an equivalent amount of CRA. Multiple parameters of asthma-like pulmonary inflammation were measured.

Results

Compared to HDE challenged mice, the LPS-reduced HDE challenged mice had significantly reduced TNFα levels in the bronchoalveolar lavage fluid. Plasma levels of IgE and IgG1 were significantly reduced, however no change in CRA-specific IgE was detected. In HDE mice, plasma IgG2a levels were similar to naïve mice, while LPS-reduced HDE mice had significantly greater concentrations. Reduced levels of LPS in the HDE did not decrease eosinophil or neutrophil recruitment into the alveolar space. Equivalent inflammatory cell recruitment occurred despite having generally higher pulmonary concentrations of eotaxins and CXC chemokines in the LPS-reduced HDE group. LPS-reduced HDE challenge induced significantly higher concentrations of IFNγ, and IL-5 and IL-13 in the BAL fluid, but did not decrease airways hyperresponsiveness or airway resistance to methacholine challenge. Conclusion: These data show that reduction of LPS levels in the HDE does not significantly protect against the severity of asthma-like pulmonary inflammation.

Anti-tumor necrosis factor-alpha treatment reduces allergic responses in an allergic rhinitis mouse model

BACKGROUND

  Tumor necrosis factor (TNF)-α is a principal mediator of the acute inflammatory response, including allergic rhinitis. TNF-α inhibitors are widely used for the treatment of inflammatory conditions such as rheumatoid arthritis and inflammatory bowel diseases; however, the effects of TNF-α inhibitors on allergic rhinitis are not well established. We aimed to investigate the effects of infliximab, a TNF-α inhibitor, on allergic rhinitis in a mouse model.

METHODS

  BALB/c mice were sensitized with ovalbumin (OVA) and alum, and challenged intranasally with OVA. The TNF-α inhibitor, infliximab was administered intraperitoneally, and multiple parameters of allergic responses were evaluated to determine the effects of infliximab.

RESULTS

  Infliximab reduced allergic symptoms and eosinophilic infiltration into the nasal mucosa. It also suppressed total and OVA-specific IgE levels, and inhibited local Th2 cytokine transcription in the nasal mucosa and systemic Th2 cytokine production by splenocytes. Furthermore, the expression of E-selectin, neither intercellular adhesion molecule 1 (ICAM-1) nor vascular cell adhesion molecule 1 (VCAM-1), in the nasal mucosa was suppressed in the infliximab-treated group when compared to the nontreated group.

CONCLUSION

  This study shows that the TNF-α inhibitor infliximab induces anti-allergic effects by decreasing local and systemic Th2 cytokine (IL-4) production, total and OVA-specific IgE levels, adhesion molecule (E-selectin) expression, and eosinophil infiltration into the nasal mucosa in an allergic rhinitis model. Therefore, infliximab should be considered as a potential agent in treating allergic rhinitis.

A rat model of exercise-induced asthma: a nonspecific response to a specific immunogen

Exercise-induced bronchoconstriction (EIB) is common; however, key aspects of its pathogenesis are still unclear. We investigated the feasibility of adapting an established animal model of asthma to investigate the earliest stages of EIB. The hypothesis was that a single exposure to a normally innocuous, and brief, exercise challenge could trigger EIB symptoms in rats previously sensitized to ovalbumin (OVA) but otherwise unchallenged. Brown-Norway rats were sensitized by intraperitoneal injection of OVA at 0 and 2 wk. At week 3, animals were exposed to either aerosolized OVA (SS) or exercise (EXS). A trained, blinded, clinical observer graded EIB by respiratory sounds. Plasma and lung cytokine levels were analyzed. No control rats with or without exercise (EX, CON) showed evidence of EIB. Eighty percent of the SS group demonstrated abnormal breath sounds upon exposure to aerosolized OVA. Approximately 30% of EXS rats sensitized to OVA but exposed only to exercise had abnormal breath sounds. Lung tissue levels of TNF-α, IL-1α, growth-related oncogene/keratinocyte/chemoattractant, and IFN-γ were significantly higher (P < 0.001) in the SS group, relative to all other groups. Changes in most of these cytokines were not notable in the EXS rats, suggesting a different mechanism of EIB. Remarkably, IFN-γ, but not the other cytokines measured, was significantly elevated following brief exercise in both sensitized and unsensitized rats. Exercise led to detectable breathing sound abnormalities in sensitized rats, but less severe than those observed following classical OVA challenge. Precisely how this immune crossover occurs is not known, but this model may be useful in elucidating essential mechanisms of EIB.

Association between β+252 tumour necrosis factor polymorphism and asthma in western Saudi children

There is strong evidence that supports the role of tumour necrosis factors (TNF-alpha/beta) as common genetic factors, located on 6p21.1-6p21.3 loci, in the pathogenesis of asthma disease. In this study, we extended our research work on TNFA to include the genotyping of Saudi asthmatic children as regards to TNFB gene (namely as lymphotoxin-α, LTA). We examined 60 asthmatic Saudi children compared to 56 healthy non-asthmatics using the PCR-RFLP analyses to identify the polymorphism +252A>G in intron 1 in lymphotoxin-α gene. We identified 55% of the allele A of the LTA∗NcoI polymorphism in subjects with asthma disease, and 45% of the allele G. In this study, the frequency of the LTA∗NcoI-A/A genotype was 40% preferably to the LTA∗NcoI-G/A and LTA∗NcoI-G/G genotypes. In addition, the severe persistent asthmatic cases were associated with the LTA∗NcoI-AA genotype at a frequency of 80%, while the genotype LTA∗NcoI-GG are associated with the mildest form of the disease. Consequently, one could predict the severity of asthma and hence the polymorphism of the LTA∗NcoI. Herein, we stated that more than 93% of Saudi children under investigation lived in the randomized areas of western regions of Saudi Arabia. In conclusion, genotype frequencies for the LTA+252 polymorphisms were significantly different from the controls. These findings may have implications for future early intervention studies by helping to identify infants at increased risk for wheezing and childhood asthma.

Association between β+252 tumour necrosis factor polymorphism and asthma in western Saudi children

There is strong evidence that supports the role of tumour necrosis factors (TNF-alpha/beta) as common genetic factors, located on 6p21.1-6p21.3 loci, in the pathogenesis of asthma disease. In this study, we extended our research work on TNFA to include the genotyping of Saudi asthmatic children as regards to TNFB gene (namely as lymphotoxin-α, LTA). We examined 60 asthmatic Saudi children compared to 56 healthy non-asthmatics using the PCR-RFLP analyses to identify the polymorphism +252A>G in intron 1 in lymphotoxin-α gene. We identified 55% of the allele A of the LTA∗NcoI polymorphism in subjects with asthma disease, and 45% of the allele G. In this study, the frequency of the LTA∗NcoI-A/A genotype was 40% preferably to the LTA∗NcoI-G/A and LTA∗NcoI-G/G genotypes. In addition, the severe persistent asthmatic cases were associated with the LTA∗NcoI-AA genotype at a frequency of 80%, while the genotype LTA∗NcoI-GG are associated with the mildest form of the disease. Consequently, one could predict the severity of asthma and hence the polymorphism of the LTA∗NcoI. Herein, we stated that more than 93% of Saudi children under investigation lived in the randomized areas of western regions of Saudi Arabia. In conclusion, genotype frequencies for the LTA+252 polymorphisms were significantly different from the controls. These findings may have implications for future early intervention studies by helping to identify infants at increased risk for wheezing and childhood asthma.

Alveolar macrophages reduce airway hyperresponsiveness and modulate cytokine levels

The authors have recently demonstrated that alveolar macrophages (AMs) are important in protecting against early phase reactions and airway hyperresponsiveness following allergen challenge. To further understand the mechanisms involved, the authors investigated the capacity of AMs to modulate airway inflammation and cytokine levels in bronchoalveolar lavage (BAL). AMs from allergy-susceptible Brown Norway (BN) rats or allergy-resistant Sprague-Dawley (SD) rats were transferred into AM-depleted BN rats 24 hours prior to allergen challenge. Methacholine-induced airway hyperresponsiveness was examined 24 hours following ovalbumin challenge. Total cells, cell types, and cytokine levels (tumor necrosis factor [TNF], interleukin [IL]-4, IL-10, IL-12 and IL-13) in BAL were measured 24 hours after allergen challenge. The transfer of AMs from SD rats into AM-depleted BN rats 24 hours before allergen challenge eliminated methacholine-induced airway hyperresponsiveness, but did not modify the number and the type of inflammatory cells in BAL. Levels of IL-13 and TNF were significantly higher in BAL of BN rats compared with SD rats. Interestingly, IL-13 and TNF levels were significantly increased and inhibited, respectively, in BN rats that received AMs from SD rats compared with BN rats. Our data suggest that AM modulation of cytokine milieu is involved in the reduction of airway hyperresponsiveness.

Genetic factors in the treatment of bronchial asthma

Owing to the recent vast progress in analytical tools and procedures to elucidate the relationship between genes and diseases, many candidate genes leading to the development of bronchial asthma have been reported. However, the quantitative phenotypes of asthma, such as decrease in forced expiratory volume in the first second, serum hyper-IgE, bronchial hyperresponsiveness and blood hyper-eosinophilia, do not represent this disease completely. On the other hand, eosinophilic inflammation of the bronchial mucosa represents accurately the feature of bronchial asthma, although accurate quantification of its status is difficult. While the production of interleukin (IL)-5 in peripheral CD4(+) T cells probably correlates with eosinophilic inflammation of the airway, the effectiveness of anti-IL-5 antibody for the treatment of bronchial asthma is controversial. Since intervention with asthma-causing gene products may not be sufficient for the treatment of this disease, identification of therapy-responsive genes should become more important in the near future.

Beta-escin has potent anti-allergic efficacy and reduces allergic airway inflammation

Background

Type I hypersensitivity is characterized by the overreaction of the immune system against otherwise innocuous substances. It manifests as allergic rhinitis, allergic conjunctivitis, allergic asthma or atopic dermatitis if mast cells are activated in the respective organs. In case of systemic mast cell activation, life-threatening anaphylaxis may occur. Currently, type I hypersensitivities are treated either with glucocorticoids, anti-histamines, or mast cell stabilizers. Although these drugs exert a strong anti-allergic effect, their long-term use may be problematic due to their side-effects.

Results

In the course of a routine in vitro screening process, we identified beta-escin as a potentially anti-allergic compound. Here we tested beta-escin in two mouse models to confirm this anti-allergic effect in vivo. In a model of the early phase of allergic reactions, the murine passive cutaneous anaphylaxis model, beta-escin inhibited the effects of mast cell activation and degranulation in the skin and dose-dependently prevented the extravasation of fluids into the tissue. Beta-escin also significantly inhibited the late response after antigen challenge in a lung allergy model with ovalbumin-sensitized mice. Allergic airway inflammation was suppressed, which was exemplified by the reduction of leucocytes, eosinophils, IL-5 and IL-13 in the bronchoalveolar lavage fluid. Histopathological examinations further confirmed the reduced inflammation of the lung tissue. In both models, the inhibitory effect of beta-escin was comparable to the benchmark dexamethasone.

Conclusions

We demonstrated in two independent murine models of type I hypersensitivity that beta-escin has potent anti-allergic properties. These results and the excellent safety profile of beta-escin suggest a therapeutic potential of this compound for a novel treatment of allergic diseases.

Delayed addition of glucocorticoids selectively suppresses cytokine production in stimulated human whole blood

Glucocorticoids (GC) are potent drugs proven to effectively treat inflammatory diseases, although patients typically begin therapy after the onset of symptoms. Clinical studies with cytokine inhibitors prove that these mediators drive inflammatory responses in diseases such as rheumatoid arthritis and Crohn's disease. Despite the clear sequence of cytokine-induced inflammation followed by effective GC treatment, most basic science investigations have examined the ability of GC to prevent an inflammatory response rather than halt its progression. The current studies used the Toll-like receptor 2 (TLR2) agonist palmitoyl(3)-cysteine-serine-lysine(4) (PAM) or the TLR4 agonist lipopolysaccharide (LPS) to stimulate human whole blood and determine whether postponing the addition of the GC dexamethasone (DEX) limits its ability to decrease cytokine production. Twenty-four hours after stimulation, tumor necrosis factor (TNF), interleukin-1beta (IL-1beta), IL-6, and IL-8 levels were measured, in addition to the cytokine inhibitors IL-1 soluble receptor II (SRII), IL-1 receptor antagonist, and TNF SRII. LPS rapidly induced all of the proinflammatory mediators over 24 h while failing to induce any of the cytokine inhibitors. PAM stimulation also induced IL-1beta, IL-6, and IL-8. Concomitant addition of DEX plus LPS or PAM significantly suppressed all cytokine levels. Delaying the addition of DEX until 6 h after LPS stimulation failed to decrease TNF or IL-6. In contrast, delayed DEX addition significantly suppressed PAM-induced IL-1beta, IL-6, or IL-8 and also suppressed LPS-induced IL-1beta and IL-8. Our results show that cytokines which typically increase in concentration between 6 and 24 h after stimulation were significantly suppressed by the addition of DEX 6 h after stimulation.

Cytokine antagonists for the treatment of asthma: progress to date

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

Decrease in airway mucous gene expression caused by treatment with anti-tumor necrosis factor alpha in a murine model of allergic asthma

BACKGROUND

Mucous hypersecretion increases asthma morbidity and mortality. Tumor necrosis factor a (TNF-a) levels are elevated in bronchoalveolar fluid, sputum, and monocyte membranes in some patients with asthma. Anti-TNF-a decreased asthma exacerbations and improved forced expiratory volume in 1 second in these patients. Whether anti-TNF-a reduces mucous cell metaplasia or hyperplasia has not been evaluated.

OBJECTIVE

To investigate the role of anti-TNF-alpha in mucous hypersecretion.

METHODS

BALB/c mice sensitized intraperitoneally and challenged intratracheally with ovalbumin were treated with 250 microg of anti-TNF-alpha before ovalbumin sensitization and challenge or before only ovalbumin challenge. Control groups were sham treated. The tumor necrosis factor receptor (TNFR) mice (TNFR-/- and TNFR+/+) were identically sensitized and challenged. Seventy-two hours after the final challenge, the airway pressure time index (APTI), which measures airway hyperresponsiveness, was recorded. Mucous cell metaplasia was accessed by quantitative polymerase chain reaction for MUC-5AC (the epithelial cell mucous-inducing gene) and the percentage of periodic acid-Schiff (PAS) staining of bronchial epithelial cells. A human airway cell line (constitutively expressing MUC-5AC) was pretreated with a NF-kappaB inhibitor before TNF-alpha culture.

RESULTS

The mean (SE) fold change of MUC-5AC expression (compared with naive controls), the percentage of PAS-positive bronchiole epithelial cells, and the APTI decreased in BALB/c mice treated with anti-TNF-alpha before sensitization and challenge (4.9 [1.14], P = .007; 28.9% [6.8%], P < .001; and 545.8 [104.5] cm H2O/s, P < .001, respectively) and before challenge alone (9.3 [1.8], P = .03; 43.6% [10.7%], P = .009; and 896.8 [81.23] cm H2O/s, P = .06, respectively) compared with sham-treated mice (20.9 [3.9], 82.4% [1.8%], and 1,055 [30.6] cm H20/s, respectively). MUC-5AC expression decreased in ovalbumin sensitized or challenged TNFR-/- (2.41 [0.4]) compared with ovalbumin sensitized or challenged TNFR+/+ mice (18.4 [2.5], P < .001). TNF-alpha-induced MUC-5AC expression in human airway culture significantly decreased with pretreatment of a NF-kappaB inhibitor.

CONCLUSIONS

Anti-TNF-alpha treatment reduces airway mucous cell metaplasia in a mouse model of asthma, which may in part underlie its beneficial effect as asthma therapy.

Effects of TNF-alpha-converting enzyme inhibition on acute lung injury induced by endotoxin in the rat

We studied the effects of TNF-converting enzyme inhibition with Y-41654, which down-regulates the production of soluble TNF-alpha (sTNF-alpha), on acute lung injury induced by intratracheal administration of LPS. We first verified in vitro that pretreatment of isolated alveolar macrophages from Sprague-Dawley male rats with 20 microL of 0.1-mM Y-41654, decreased significantly (P < 0.05) the concentration of sTNF-alpha in cell supernatants induced by 10 microg/mL of LPS. We then studied four groups of rats (each n = 10) including 1) a control group, 2) an LPS group (300 microg /kg, instilled intratracheally), 3) a Y-41654 group, and 4) a treatment group treated with Y-41654 after LPS instillation. Y-41654, 10 mg/kg in 0.7 mL of phosphate-buffered saline, was administered (i.v.), 15 min before and 0.5, 1.5, 2.5, and 3.5 h after saline or LPS instillation. The animals were observed for 4 h. In the animals treated with Y-41654, the concentrations of sTNF-alpha and protein in bronchoalveolar lavage fluid, and the number of neutrophils in lung tissue and bronchoalveolar lavage fluid were significantly lower at 4 h than in the LPS group (P < 0.05). In conclusion, sTNF-alpha plays an important role in the development of acute lung injury induced by intratracheal administration of LPS, in part modulating neutrophil kinetics.

Obesity, airway hyperresponsiveness, and inflammation

Epidemiological data indicate that obesity is a risk factor for asthma, but the mechanistic basis for this relationship is not established. Here we review data from human subjects and animal models investigating the relationship between obesity and airway hyperresponsiveness, a characteristic feature of asthma. We discuss obesity as a state of chronic systemic inflammation resulting from interactions between adipocytes and adipose tissue macrophages that are recruited to obese adipose tissue. Finally, we focus on the possibility that aspects of this inflammation, particularly obesity-related changes in TNF-alpha, leptin, and adiponectin, may contribute to airway hyperresponsiveness in obesity. Determining how obesity promotes asthma may uncover novel therapeutic strategies that are effective in the obese asthmatic subject.

Obesity, airway hyperresponsiveness, and inflammation

Epidemiological data indicate that obesity is a risk factor for asthma, but the mechanistic basis for this relationship is not established. Here we review data from human subjects and animal models investigating the relationship between obesity and airway hyperresponsiveness, a characteristic feature of asthma. We discuss obesity as a state of chronic systemic inflammation resulting from interactions between adipocytes and adipose tissue macrophages that are recruited to obese adipose tissue. Finally, we focus on the possibility that aspects of this inflammation, particularly obesity-related changes in TNF-alpha, leptin, and adiponectin, may contribute to airway hyperresponsiveness in obesity. Determining how obesity promotes asthma may uncover novel therapeutic strategies that are effective in the obese asthmatic subject.

A non-cytosolic protein of Trypanosoma evansi induces CD45-dependent lymphocyte death

In a recent study dealing with a mouse model of Trypanosoma evansi-associated disease, a remarkable synchrony between the parasitaemia peak and the white-blood-cell count nadir was noticed. The present study was designed to establish whether there is a direct causal link between the parasite load during its exponential phase of growth and the disappearance of peripheral blood leukocytes. In vitro experiments performed with trypanosomes and purified peripheral blood mononucleated cells revealed the existence of a lymphotoxin embedded in the T. evansi membrane: a protein sensitive to serine proteases, with a molecular mass of less than 30 kDa. Lymphocytes death induced by this protein was found to depend on the intervention of a lymphocytic protein tyrosine phosphatase. When lymphocytes were exposed to increasing quantities of a monoclonal antibody raised against the extracellular portion of CD45, a transmembrane protein tyrosine phosphatase covering over 10% of the lymphocyte surface, T. evansi membrane extracts showed a dose-dependent decrease in cytotoxicity. As the regulatory functions of CD45 concern not only the fate of lymphocytes but also the activation threshold of the TCR-dependent signal and the amplitude and nature of cytokinic effects, this demonstration of its involvement in T. evansi-dependent lymphotoxicity suggests that T. evansi might manipulate, via CD45, the host's cytokinic and adaptive responses.

Etanercept prevents airway hyperresponsiveness by protecting neuronal M2 muscarinic receptors in antigen-challenged guinea pigs

BACKGROUND AND PURPOSE

Increased tumour necrosis factor-alpha (TNF-alpha) is associated with airway hyperreactivity in antigen-challenged animals. In human asthmatics, TNF-alpha is increased and blocking it prevents airway hyperreactivity in some asthmatic patients. However, the mechanisms by which TNF-alpha mediates hyperreactivity are unknown. Airway hyperreactivity can be caused by dysfunction of neuronal M(2) muscarinic receptors that normally limit acetylcholine release from parasympathetic nerves. Here we test whether blocking TNF-alpha receptors with etanercept prevents M(2) receptor dysfunction and airway hyperreactivity in antigen-challenged guinea pigs.

EXPERIMENTAL APPROACH

Ovalbumin-sensitized guinea pigs were challenged by inhalation of antigen. Some animals received etanercept (3 mg kg(-1) i.p.) 3 h before challenge. 24 h after challenge, airway hyperreactivity and M(2) receptor function were tested. Inflammatory cells in bronchoalveolar lavage, blood and lung were counted. TNF-alpha and its receptors were detected by real-time RT-PCR and immunocytochemistry in parasympathetic nerves from humans and guinea pigs and in human neuroblastoma cells.

KEY RESULTS

Antigen-challenged animals were hyperreactive to vagal stimulation and neuronal M(2) receptors were dysfunctional. Both M(2) receptor dysfunction and airway hyperreactivity were prevented by etanercept. Etanercept reduced eosinophils around airway nerves, and in blood, bronchoalveolar lavage and airway smooth muscle. Also, TNF-alpha decreased M(2) receptor mRNA in human and guinea pig parasympathetic neurons.

CONCLUSIONS AND IMPLICATIONS

Tumour necrosis factor-alpha may contribute to M(2) receptor dysfunction and airway hyperreactivity directly by decreasing receptor expression and indirectly by promoting recruitment of eosinophils, containing major basic protein, an M(2) antagonist. This suggests that etanercept may be beneficial in treatment of allergic asthma.

Acute pulmonary lipopolysaccharide tolerance decreases TNF-alpha without reducing neutrophil recruitment

Pulmonary LPS exposure plays a key role in exacerbation of lung diseases such as chronic obstructive pulmonary disease and asthma. However, little is known about the effects of repeated LPS exposure in the lung microenvironment. We have developed a novel murine model of pulmonary LPS tolerance induced by intratracheal (i.t.) administration of LPS. First, we show that pulmonary LPS exposure does not induce whole-body refractoriness to systemic LPS, because i.t. administration followed by i.p. administration did not decrease plasma TNF-alpha. However, a local refractory state can be induced with two i.t. LPS exposures. Pulmonary LPS tolerance was induced by i.t. administration of 100 ng LPS at time 0 and 48 h. Nontolerant mice received PBS at time 0 and LPS at 48 h. Bronchoalveolar lavage levels of TNF-alpha were significantly attenuated in tolerant mice vs nontolerant mice (1597 pg/ml vs 7261 pg/ml). TNF-alpha mRNA was significantly reduced in bronchoalveolar lavage cells (5-fold) and lung tissue (10-fold). No reduction was seen in neutrophil numbers in the bronchoalveolar lavage fluid, myeloperoxidase activity, or expression of neutrophil chemoattractants CXCL1 and CXCL2, reflecting the specificity of the response. The reduction in TNF-alpha was accompanied by a significant increase in soluble receptors, TNF-SRI (159 pg/ml vs 206 pg/ml) and TNF-SRII (1366 pg/m vs 2695 pg/ml). In conclusion, pulmonary LPS tolerance results in a specific reduction in TNF-alpha expression, while the neutrophilic response is unaffected. This response may be a mechanism to limit tissue damage by reducing TNF-alpha levels, while still maintaining the antimicrobial capacity of the lung.

Anti-TNF-alpha therapies in chronic obstructive pulmonary diseases

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and asthma are chronic diseases in which inflammation of the airways leads to progressive transient airway obstruction and TNF-alpha plays an important pro-inflammatory role.

OBJECTIVE

To assess the plausibility of anti-TNF-alpha therapies playing an anti-inflammatory role in asthma and COPD.

METHODS

Scientific rationale of TNF-alpha targeting in asthma and COPD was assessed individually and the available data on the use of anti-TNF-alpha in each disease were reviewed.

RESULTS AND CONCLUSION

Anti-TNF-alpha therapies demonstrate different efficacies in asthma and COPD and further supportive preclinical and clinical data are needed, especially about subsets of certain diseases which could benefit the most from these therapies.

Apoptosis, airway inflammation and anti-asthma therapy: from immunobiology to clinical application

T lymphocyte apoptosis is essential for maintaining immune system homeostasis. Experimental evidence suggests apoptosis control mechanisms may be impaired in inflammatory conditions, particularly airway Th2-type allergic diseases. This review briefly examines the mucosal immune system homeostasis and common apoptotic pathways and discusses impaired apoptosis, allergy, airway inflammation, remodelling and fibrosis. Finally, the paper presents an update on pharmacological targeting of apoptosis to control airway inflammation in patients with allergic asthma.

Evaluation of the anti-inflammatory effect of infliximab in a mouse model of acute asthma

BACKGROUND AND OBJECTIVE

To evaluate the potential role of anti-tumour necrosis factor (TNF)-alpha mAb (infliximab) on the inflammatory response in a mouse model of acute asthma.

METHODS

BALB/c mice received intraperitoneal (i.p.) ovalbumin (OVA) on days 0 and 14, 100 microg of OVA intranasally on day 14 and 50 microg of OVA intranasally on days 25, 26 and 27. The low-dose (2.5 mg/kg) and high-dose (6.25 mg/kg) infliximab groups received i.p. infliximab before each i.p. sensitization and on challenge days 1, 6, 13, 20 and 27. The control group received i.p. injections of normal saline with alum on days 0 and 14 and normal saline without alum on days 14, 25, 26 and 27.

RESULTS

There were statistically significant decreases in the numbers of BAL fluid (BALF) neutrophils, eosinophils, as well as lung eosinophils in both the low- and high-dose infliximab groups when compared with the control OVA sensitized/challenged group. The lower dose of infliximab did not alter lung neutrophil counts, but a marked decrease was seen with the high dose of infliximab. After treatment with low and high doses of infliximab, BALF levels of regulated on activation normal T cell expressed and secreted (RANTES), granulocyte macrophage-colony stimulating factor (GM-CSF), TNF-alpha, IL-6, macrophage inflammatory protein (MIP)-2, and levels of RANTES, IL-4, GM-CSF, TNF-alpha, IL-6 and MIP-2 in lung tissue were significantly decreased when compared with the control OVA sensitized/challenged group. There was a significant decrease in BALF IL-4 only in the high-dose infliximab group.

CONCLUSIONS

These results show that an anti-TNF-alpha mAb has a considerable anti-inflammatory effect on allergen-induced lung inflammation in an animal model of acute asthma.

Essential role of IFNbeta and CD38 in TNFalpha-induced airway smooth muscle hyper-responsiveness

We recently identified autocrine interferon (IFN)beta as a novel mechanism mediating tumor necrosis factor (TNF)alpha-induced expression of inflammatory genes in airway smooth muscle (ASM) cells, including CD38, known to regulate calcium signaling. Here, we investigated the putative involvement of IFNbeta in regulating TNFalpha-induced airway hyper-responsiveness (AHR), a defining feature of asthma. Using our pharmacodynamic model to assess ex vivo AHR isolated murine tracheal rings, we found that TNFalpha-induced enhanced contractile responses to carbachol and bradykinin was abrogated by neutralizing anti-IFNbeta antibody or in tracheal rings deficient in CD38. In cultured human ASM cells, where CD38 has been involved in TNFalpha-induced enhanced calcium signals to carbachol and bradykinin, we found that neutralizing anti-IFNbeta prevented TNFalpha enhancing action only on carbachol responses but not to that induced by bradykinin. In a well-characterized model of allergic asthma (mice sensitized and challenged with Aspergillus fumigatus (Af)), we found heightened expression of both IFNbeta and CD38 in the airways. Furthermore, allergen-associated AHR to methacholine, assessed by lung resistance and dynamic compliance, was completely suppressed in CD38-deficient mice, despite the preservation of airway inflammation. These data provide the first evidence that ASM-derived IFNbeta and CD38 may play a significant role in the development of TNFalpha-associated AHR.

Anti-IgE and other antibody targets in asthma

Asthma is a heterogeneous disorder of unknown etiology that manifests as recurrent episodes of coughing, wheezing, and breathlessness. These symptoms are often debilitating and exacerbations usually are unexpected, resulting in work or school absences, limitations in activity, reduced quality of life, and personal and economic hardships. Over the past several decades, a great deal has been learned about asthma pathophysiology, and currently available therapies have revolutionized asthma treatment. However, asthma remains a global public health problem, and the hope is that newer therapies targeting specific biological mediators of asthma, particularly antibody-mediated therapies, offer exciting new modes to the control of this disease. We will review some of these therapies, with the majority of attention devoted to anti-IgE therapy which has been approved for treatment of adult and childhood asthma by the US Food and Drug Administration (FDA) since 2003.

Tumor necrosis factor inhibitors for the treatment of asthma

Asthma is a unique form of chronic airway inflammation characterized by reversible airway obstruction, airway hyperresponsiveness and the production of specific inflammatory mediators. Local activation of both immune and nonimmune cells in the lung triggers the release of these immunomodulator molecules. Among them, tumor necrosis factor (TNF)-alpha, a multipotent pro-inflammatory mediator, plays a critical role in immunoregulation of asthma by contributing to bronchopulmonary inflammation and airway hyperresponsiveness. Blocking TNF-alpha activity has already shown outstanding efficacy in other chronic inflammatory diseases including rheumatoid arthritis, Crohn's disease, and psoriasis. The successful treatment of these other chronic inflammatory diseases provides hope that TNF inhibitors may have application for the treatment of asthma. Recent developments in animal models and clinical trials in patients with severe asthma provide strong support for the concept that blocking TNF-alpha activity represents a new approach in asthma therapy. In this review, we address the multipotential role of TNF-alpha in asthma and the efficacy and safety of TNF-alpha blocking agents in asthma.

Effects of TNFalpha on the human nasal mucosa in vivo

BACKGROUND

TNFalpha is a cytokine that may contribute to the pathophysiology of airway inflammation. Inhalation of TNFalpha produces granulocyte recruitment and airway hyperresponsiveness in man. Anti-TNFalpha treatment may inhibit allergen-induced plasma exudation in guinea-pig airways. Increased nasal mucosal output of TNFalpha has been demonstrated in allergic rhinitis, but the effect of TNFalpha on the human nasal mucosa has not been examined in vivo.

OBJECTIVE

To examine effects of topical TNFalpha on the human nasal mucosa in vivo.

METHODS

In a dose-finding study, healthy subjects received intranasal TNFalpha (0-7.5 microg). Nasal lavages were carried out before as well as 10 min and 24 h post challenge and alpha(2)-macroglobulin was measured as an index of plasma exudation. In a second study, involving patients with allergic rhinitis examined out of season, a sham-controlled nasal challenge with TNFalpha (10 microg) was performed and followed 24 h later by an allergen challenge. Lavages were performed before the TNFalpha challenge, 24 h thereafter, and 10 min post allergen challenge. alpha(2)-Macroglobulin, eosinophil cationic protein (ECP), myeloperoxidase (MPO), and IL-8 were analyzed as indices of plasma exudation, eosinophil activity, neutrophil activity, and pro-inflammatory cytokine production, respectively.

RESULTS

In the dose-finding study, TNFalpha produced significant increases in alpha(2)-macroglobulin 24h post challenge (p<0.01). In allergic rhinitis, 10 microg of TNFalpha also produced this effect (p<0.01) as well as increases in ECP and IL-8 (p<0.01). MPO was increased 24 h post challenge, but this change did not reach statistical significance. TNFalpha did not produce any acute effects and did not affect the responsiveness to allergen.

CONCLUSION

The present study demonstrates that topical TNFalpha produces a human nasal inflammatory response. These data suggest a role of TNFalpha in nasal conditions characterized by mucosal inflammation.

Mast cells play a key role in the development of late airway hyperresponsiveness through TNF-alpha in a murine model of asthma

We have investigated the role of TNF-alpha in mast cell-mediated late airway hyperresponsiveness (AHR) using mast cell-deficient WBB6F1-W/W(v) (W/W(v)) mice in a murine model of asthma, which exhibits a biphasic increase in AHR. TNF-alpha levels in the airway and magnitude of late AHR in response to airway allergen challenge were severely impaired in W/W(v) mice compared to their littermates. In addition to TNF-alpha, cytosolic phospholipase A(2) (cPLA(2)) phosphorylation and enzymatic activity in the lungs were also impaired in W/W(v) mice. Either anti-TNF-alpha antibody or an inhibitor of cPLA(2) abolished late AHR in congeneic +/+ mice. Intratracheal administration of TNF-alpha resulted in increases in late AHR, cPLA(2 )phosphorylation, cPLA(2 )activity, and phosphorylation of mitogen-activated protein kinases. Mast cell replacement restored airway TNF-alpha level, cPLA(2 )phosphorylation and enzymatic activity in the lungs as well as late AHR in W/W(v) mice. These data indicate that mast cells play a key role in the development of late AHR through liberation of TNF-alpha.

The impact of comorbid atopic disease on asthma: clinical expression and treatment

Clinically, asthma and allergic rhinitis involve separate regions of the respiratory tract while representing a common underlying inflammatory syndrome. Much evidence supports an epidemiologic association between the diseases, paranasal sinus involvement in both conditions, and parallel relationship in severity and treatment outcomes. Pathophysiologic mechanisms, including immunoglobulin E (IgE)- mediated inflammation, are also shared. Blocking IgE with the recombinant humanized monoclonal antibody omalizumab demonstrated clinical efficacy in patients with upper and lower airway diseases. IgE blockade, leukotriene modulation, and B-cell depletion therapy have all exhibited success in chronic inflammation, reinforcing and expanding the beneficial role of immunomodulation of global mediators.

Transforming growth factor beta enhances respiratory syncytial virus replication and tumor necrosis factor alpha induction in human epithelial cells

Asthma is characterized as a chronic inflammatory disease associated with significant tissue remodeling. Patients with asthma are more susceptible to virus-induced exacerbation, which subsequently can lead to increased rates of hospitalization and mortality. While the most common cause of asthma-related deaths is respiratory viral infections, the underlying factors in the lung environment which render asthmatic subjects more susceptible to viral exacerbation are not yet identified. Since transforming growth factor beta (TGF-beta) is a critical cytokine for lung tissue remodeling and asthma phenotype, we have focused on the effects of TGF-beta on viral replication and virus-induced inflammation. Treatment of human epithelial cells with TGF-beta increased respiratory syncytial virus (RSV) replication by approximately fourfold. Tumor necrosis factor alpha (TNF-alpha) mRNA and protein expression were also significantly increased above levels with RSV infection alone. The increase in RSV replication and TNF-alpha expression after TGF-beta treatment was concomitant with an increase in virus-induced p38 mitogen-activated protein kinase activation. Our data reveal a novel effect for TGF-beta on RSV replication and provide a potential mechanism for the exaggerated inflammatory response observed in asthmatic subjects during respiratory viral infections.