Anti-TNF-alpha and Th1 cytokine-directed therapies for the treatment of asthma

Different expression levels of interleukin-36 in asthma phenotypes

Interleukin (IL)-36 family is closely associated with inflammation and consists of IL-36α, IL-36β, IL-36γ, and IL-36Ra. The role of IL-36 in the context of asthma and asthmatic phenotypes is not well characterized. We examined the sputum IL-36 levels in patients with different asthma phenotypes in order to unravel the mechanism of IL-36 in different asthma phenotypes. Our objective was to investigate the induced sputum IL-36α, IL-36β, IL-36γ, and IL-36Ra concentrations in patients with mild asthma, and to analyze the relationship of these markers with lung function and other cytokines in patients with different asthma phenotypes. Induced sputum samples were collected from patients with mild controlled asthma (n = 62, 27 males, age 54.77 ± 15.49) and healthy non-asthmatic controls (n = 16, 10 males, age 54.25 ± 14.60). Inflammatory cell counts in sputum were determined. The concentrations of IL-36 and other cytokines in the sputum supernatant were measured by ELISA and Cytometric Bead Array. This is the first study to report the differential expression of different isoforms of IL-36 in different asthma phenotypes. IL-36α and IL-36β concentrations were significantly higher in the asthma group (P = 0.003 and 0.031), while IL-36Ra concentrations were significantly lower (P < 0.001) compared to healthy non-asthmatic controls. Sputum IL-36α and IL-36β concentrations in the neutrophilic asthma group were significantly higher than those in paucigranulocytic asthma (n = 24) and eosinophilic asthma groups (n = 23). IL-36α and IL-36β showed positive correlation with sputum neutrophils and total cell count (R = 0.689, P < 0.01; R = 0.304, P = 0.008; R = 0.689, P < 0.042; R = 0.253, P = 0.026). In conclusion, IL-36α and IL-36β may contribute to asthma airway inflammation by promoting neutrophil recruitment in airways. Our study provides insights into the inflammatory pathways of neutrophilic asthma and identifies potential therapeutic target.

Genomics of Treatable Traits in Asthma

The astounding number of genetic variants revealed in the 15 years of genome-wide association studies of asthma has not kept pace with the goals of translational genomics. Moving asthma diagnosis from a nonspecific umbrella term to specific phenotypes/endotypes and related traits may provide insights into features that may be prevented or alleviated by therapeutical intervention. This review provides an overview of the different asthma endotypes and phenotypes and the genomic findings from asthma studies using patient stratification strategies and asthma-related traits. Asthma genomic research for treatable traits has uncovered novel and previously reported asthma loci, primarily through studies in Europeans. Novel genomic findings for asthma phenotypes and related traits may arise from multi-trait and specific phenotyping strategies in diverse populations.

Monoclonal Antibodies and Airway Diseases

Monoclonal antibodies, biologics, are a relatively new treatment option for severe chronic airway diseases, asthma, allergic rhinitis, and chronic rhinosinusitis (CRS). In this review, we focus on the physiological and pathomechanisms of monoclonal antibodies, and we present recent study results regarding their use as a therapeutic option against severe airway diseases. Airway mucosa acts as a relative barrier, modulating antigenic stimulation and responding to environmental pathogen exposure with a specific, self-limited response. In severe asthma and/or CRS, genome-environmental interactions lead to dysbiosis, aggravated inflammation, and disease. In healthy conditions, single or combined type 1, 2, and 3 immunological response pathways are invoked, generating cytokine, chemokine, innate cellular and T helper (Th) responses to eliminate viruses, helminths, and extracellular bacteria/fungi, correspondingly. Although the pathomechanisms are not fully known, the majority of severe airway diseases are related to type 2 high inflammation. Type 2 cytokines interleukins (IL) 4, 5, and 13, are orchestrated by innate lymphoid cell (ILC) and Th subsets leading to eosinophilia, immunoglobulin E (IgE) responses, and permanently impaired airway damage. Monoclonal antibodies can bind or block key parts of these inflammatory pathways, resulting in less inflammation and improved disease control.

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.

Cytokines concentrations in serum samples from allergic children-Multiple analysis to define biomarkers for better diagnosis of allergic inflammatory process

BACKGROUND

Allergic diseases can expand at any age as a result of complicated interaction of environmental and genetic factors. Through the years, studies have found that allergic diseases are primarily described by elevated Th2 pathway activation, leading to increased serum IgE levels, allergen reactivity, blood eosinophil counts and secreted interleukins.

METHODS

A total of 20 patients with allergy and 20 matched controls participants were recruited for the study. A study was designed with the framework of an ongoing project at the Regional Children's Hospital in Olsztyn on the analysis of the immune profile of children with allergy and asthma. Diagnosis was conducted by medical specialists. Whole blood samples were collected and serum IL's and chemokin levels were made using ELISA kits.

RESULTS

Results demonstrated that in comparison to the controls, the individuals with allergy showed significantly higher concentration of IL-1β, IL-4, IL-6, IL-8, IL-10, IL-13 and TNF-α. We also demonstrated significant correlations between the levels of cytokines which implies the presence of an interactive network between them. The results of ROC analysis indicated the 3-factors (IL-1β, IL-4, IL-8) could be additional, helpful biomarkers in better diagnosis of allergy.

CONCLUSIONS

In this study, serum levels of cytokine differed among children with allergy. However, the findings of this support the possibility of using an appropriate selection of serum cytokine for the diagnosis allergy and emphasize the need to standardize quantitative methods for serum analysis.

Huai Qi Huang corrects the balance of Th1/Th2 and Treg/Th17 in an ovalbumin-induced asthma mouse model

The present study is designed to determine whether Huai Qi Huang has immunoregulatory effects on the (helper T (Th)) Th1/Th2 and regulatory T cell (Treg)/Th17 balance in ovalbumin (OVA)-induced asthma model mice. Asthma model mice were constructed by OVA treatment and Huai Qi Huang was administered. The amount of migrated inflammatory cells in the bronchoalveolar lavage fluid (BALF) from the OVA mice was counted. The total IgE in the sera was detected by the IgE ELISA kit. Cell suspensions from the lung were stained with antibodies specific for CD4 and the master transcription factors for Th1 (T-box expressed in T cells (T-bet)), Th2 (GATA-binding protein 3 (Gata-3)), Th17 (retinoic acid related orphan receptor γt (RORγt)), and Treg (forkhead box p3 (Foxp3)). The left lobe of the lung was used to prepare a single-cell suspension for flow cytometry to determine whether Huai Qi Huang influenced CD4⁺ T-cell subsets. Histological analyses were performed by using Hematoxylin and Eosin staining. The mRNA expression levels of the transcription factors were detected by using qRT-PCR. Huai Qi Huang inhibited infiltration of inflammatory cells into the lung, reduced influx of eosinophils (EOSs), lymphocytes (LYMs), neutrophils (NEUs), and macrophages (MACs) in the BALF, and decreased IgE in the serum in OVA-treated mice. Huai Qi Huang could regulate Th1/Th2 and Treg/Th17 via the re-balance of cytokine profiles and change the mRNA expression levels of the transcription factors, T-bet/Gata-3 and Foxp3/RORγt in OVA-treated mice. Our results showed that Huai Qi Huang could correct the imbalance of Th1/Th2 and Treg/Th17 in OVA-induced asthma model mice, indicating its effects on inhibiting the development and severity of asthma.

Cytokine production by PBMC and serum from allergic and non-allergic subjects following in vitro histamine stimulation to test fexofenadine and osthole anti-allergic properties

FXF is a third-generation antihistamine drug and osthole is assumed a natural antihistamine alternative. This paper compares peripheral blood mononuclear cell (PBMC) incubation with FXF and osthole, by studying FXF, osthole and histamine cytokine secretion in PBMC in vitro cultures. Mabtech kits determined the interleukins IL-1β, IL-4, IL-10, IL-13 and TNF-α. The influence of the above active substances on cytokine secretion in PBMC's and serum was assessed: cytokines were IL-1β, IL-4, IL-10, IL-13 and TNF-α; and cytokine levels secreted by untreated PBMCs in pure culture medium formed the absolute control (ctrl). We determined that osthole affects PBMC cytokine secretion to almost precisely the same extent as FXF (IL-1β, IL-4, IL-10 and TNF). In addition osthole had greater IL-13 blocking ability than FXF. Moreover, we observed significantly decreased IL-4 level in histamine/osthole theatment compared to histamine alone. Meanwhile, FXF not significantly decrease the level of IL-4 increased by histamine. This data indicates osthole's strong role in allergic inflamation. All results confirm our hypothesis that osthole is a natural histamine antagonist and therefore can be beneficially used in antihistamine treatment of conditions such as allergies.

Interleukin-1β mediates virus-induced m2 muscarinic receptor dysfunction and airway hyperreactivity

Respiratory viral infections are associated with the majority of asthma attacks. Inhibitory M2 receptors on parasympathetic nerves, which normally limit acetylcholine (ACh) release, are dysfunctional after respiratory viral infection. Because IL-1β is up-regulated during respiratory viral infections, we investigated whether IL-1β mediates M2 receptor dysfunction during parainfluenza virus infection. Virus-infected guinea pigs were pretreated with the IL-1β antagonist anakinra. In the absence of anakinra, viral infection increased bronchoconstriction in response to vagal stimulation but not to intravenous ACh, and neuronal M2 muscarinic receptors were dysfunctional. Pretreatment with anakinra prevented virus-induced increased bronchoconstriction and M2 receptor dysfunction. Anakinra did not change smooth muscle M3 muscarinic receptor response to ACh, lung viral loads, or blood and bronchoalveolar lavage leukocyte populations. Respiratory virus infection decreased M2 receptor mRNA expression in parasympathetic ganglia extracted from infected animals, and this was prevented by blocking IL-1β or TNF-α. Treatment of SK-N-SH neuroblastoma cells or primary cultures of guinea pig parasympathetic neurons with IL-1β directly decreased M2 receptor mRNA, and this was not synergistic with TNF-α treatment. Treating guinea pig trachea segment with TNF-α or IL-1β in vitro increased tracheal contractions in response to activation of airway nerves by electrical field stimulation. Blocking IL-1β during TNF-α treatment prevented this hyperresponsiveness. These data show that virus-induced hyperreactivity and M2 dysfunction involves IL-1β and TNF-α, likely in sequence with TNF-α causing production of IL-1β.

MicroRNA-708 regulates CD38 expression through signaling pathways JNK MAP kinase and PTEN/AKT in human airway smooth muscle cells

Background

The cell-surface protein CD38 mediates airway smooth muscle (ASM) contractility by generating cyclic ADP-ribose, a calcium-mobilizing molecule. In human ASM cells, TNF-α augments CD38 expression transcriptionally by NF-κB and AP-1 activation and involving MAPK and PI3K signaling. CD38^−/− mice develop attenuated airway hyperresponsiveness following allergen or cytokine challenge. The post-transcriptional regulation of CD38 expression in ASM is relatively less understood. In ASM, microRNAs (miRNAs) regulate inflammation, contractility, and hyperproliferation. The 3’ Untranslated Region (3’UTR) of CD38 has multiple miRNA binding sites, including a site for miR-708. MiR-708 is known to regulate PI3K/AKT signaling and hyperproliferation of other cell types. We investigated miR-708 expression, its regulation of CD38 expression and the underlying mechanisms involved in such regulation in human ASM cells.

Methods

Growth-arrested human ASM cells from asthmatic and non-asthmatic donors were used. MiRNA and mRNA expression were measured by quantitative real-time PCR. CD38 enzymatic activity was measured by a reverse cyclase assay. Total and phosphorylated MAPKs and PI3K/AKT as well as enzymes that regulate their activation were determined by Western blot analysis of cell lysates following miRNA transfection and TNF-α stimulation. Dual luciferase reporter assays were performed to determine whether miR-708 binds directly to CD38 3’UTR to alter gene expression.

Results

Using target prediction algorithms, we identified several miRNAs with potential CD38 3’UTR target sites and determined miR-708 as a potential candidate for regulation of CD38 expression based on its expression and regulation by TNF-α. TNF-α caused a decrease in miR-708 expression in cells from non-asthmatics while it increased its expression in cells from asthmatics. Dual luciferase reporter assays in NIH-3 T3 cells revealed regulation of expression by direct binding of miR-708 to CD38 3’UTR. In ASM cells, miR-708 decreased CD38 expression by decreasing phosphorylation of JNK MAPK and AKT. These effects were associated with increased expression of MKP-1, a MAP kinase phosphatase and PTEN, a phosphatase that terminates PI3 kinase signaling.

Conclusions

In human ASM cells, TNF-α-induced CD38 expression is regulated by miR-708 directly binding to 3’UTR and indirectly by regulating JNK MAPK and PI3K/AKT signaling and has the potential to control airway inflammation, ASM contractility and proliferation.

Cytokines in common variable immunodeficiency as signs of immune dysregulation and potential therapeutic targets - a review of the current knowledge

Common variable immunodeficiency (CVID) is characterized by low levels of circulating immunoglobulins and compromised specific antibody response leading to frequent infections. Cytokines play an important role in the orchestration of the antibody response. Several previous studies have attempted to identify distinct cytokines responsible for the inflammatory changes and different manifestations of CVID, but there are conflicting results regarding the cytokine profiles in CVID patients. In light of this, an extensive review regarding the level of various cytokines and their potential therapeutic role in CVID patients was performed. This review delineates the contribution of interleukin (IL)-1, IL-2, IL-4, IL-5, IL-6, IL-7, IL-10, IL-12, IL-21, interferons, tumor necrosis factor (TNF)-α, IL-17, APRIL (a proliferation inducing ligand) and BAFF (B cell activating factor) in CVID disease and outline their potential therapeutic implications in these patients.

Disabling inflammatory pathways with biologics and resulting clinical outcomes in severe asthma

INTRODUCTION

Patients with severe asthma have a significant unmet need with persistent symptoms and/or frequent exacerbations despite high intensity treatment. These severe unrelenting symptoms have a huge impact on heathcare resources due to frequent hospital admissions and requirement for intensive and expensive medications. There is a compelling need for more effective and safer therapies to help severe asthma sufferers to achieve adequate control of their disease.

AREAS COVERED

Expanding knowledge of innate and adaptive immune responses has led to development of new biologic approaches for severe asthma. Here, the authors will review the existing efficacy and safety data from clinical trials of some of the new biologic therapies that are in development for severe asthma. Their specific role in distinctively targeted subpopulations of severe asthmatics will be also discussed.

EXPERT OPINION

Defining and phenotyping severe asthma patients will become increasingly important as some patients who were previously classified as having severe asthma may become well-controlled with a targeted phenotype-specific treatment. However, pharmacoeconomic concerns should also be taken into account given the elevated acquisition costs of recombinant human monoclonals and of the diagnostic screening procedures for the identification of potential responders.

Blockage of nerve growth factor modulates T cell responses and inhibits allergic inflammation in a mouse model of asthma

OBJECTIVE

Blockage of nerve growth factor (NGF) by anti-NGF antibodies can inhibit allergic airway hyper-responsiveness in mice. This study was aimed at determining the mechanisms underlying the action of anti-NGF in vivo.

METHODS

BALB/c mice were sensitized with ovalbumin (OVA) and treated with anti-NGF. At 1 day after the last challenge, their airway responsiveness and inflammation were examined and the levels of cytokine and transcription factor mRNA transcripts in the lungs and cytokines in the bronchoalveolar lavage fluid were determined. The frequency of different functional T cells and the levels of serum OVA-specific antibodies were measured.

RESULTS

OVA challenge induced severe airway resistance, inflammation, higher levels of IL-4, TNFα, IL-17A, TGFβ, GATA-3 and RORγT expression and increased Th2 and Th17 cells and IgE responses, but decreased IFNγ and IL-10 responses, T-bet and Foxp3 expression and Th1 and Tregs. Treatment with anti-NGF significantly reduced allergic airway resistance and inflammation, up-regulated IFNγ, IL-10, TGFβ, T-bet, and Foxp3 expression, increased Th1 and Tregs, but down-regulated IL-4, TNFα, IL-17A, RORγT and GATA-3 expression and reduced Th2 and Th17 cells, accompanied by increased serum IgG2a.

CONCLUSIONS

Anti-NGF inhibits allergic airway inflammation by modulating the balance of pro- and anti-asthmatic T cell responses in the lungs of mice.

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.

Suppressive effect of low-level laser therapy on tracheal hyperresponsiveness and lung inflammation in rat subjected to intestinal ischemia and reperfusion

Intestinal ischemia and reperfusion (i-I/R) is an insult associated with acute respiratory distress syndrome (ARDS). It is not known if pro- and anti-inflammatory mediators in ARDS induced by i-I/R can be controlled by low-level laser therapy (LLLT). This study was designed to evaluate the effect of LLLT on tracheal cholinergic reactivity dysfunction and the release of inflammatory mediators from the lung after i-I/R. Anesthetized rats were subjected to superior mesenteric artery occlusion (45 min) and killed after clamp release and preestablished periods of intestinal reperfusion (30 min, 2 or 4 h). The LLLT (660 nm, 7.5 J/cm(2)) was carried out by irradiating the rats on the skin over the right upper bronchus for 15 and 30 min after initiating reperfusion and then euthanizing them 30 min, 2, or 4 h later. Lung edema was measured by the Evans blue extravasation technique, and pulmonary neutrophils were determined by myeloperoxidase (MPO) activity. Pulmonary tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), intercellular adhesion molecule-1 (ICAM-1), and isoform of NO synthase (iNOS) mRNA expression were analyzed by real-time PCR. TNF-α, IL-10, and iNOS proteins in the lung were measured by the enzyme-linked immunoassay technique. LLLT (660 nm, 7.5 J/cm(2)) restored the tracheal hyperresponsiveness and hyporesponsiveness in all the periods after intestinal reperfusion. Although LLLT reduced edema and MPO activity, it did not do so in all the postreperfusion periods. It was also observed with the ICAM-1 expression. In addition to reducing both TNF-α and iNOS, LLLT increased IL-10 in the lungs of animals subjected to i-I/R. The results indicate that LLLT can control the lung's inflammatory response and the airway reactivity dysfunction by simultaneously reducing both TNF-α and iNOS.

Role of TNF-α in virus-induced airway hyperresponsiveness and neuronal M₂ muscarinic receptor dysfunction

BACKGROUND AND PURPOSE

Infections with respiratory viruses induce exacerbations of asthma, increase acetylcholine release and potentiate vagally mediated bronchoconstriction by blocking inhibitory M₂ muscarinic receptors on parasympathetic neurons. Here we test whether virus-induced M₂ receptor dysfunction and airway hyperresponsiveness are tumour necrosis factor-alpha (TNF-α) dependent.

EXPERIMENTAL APPROACH

Guinea pigs were pretreated with etanercept or phosphate-buffered saline 24 h before intranasal infection with parainfluenza. Four days later, pulmonary inflation pressure, heart rate and blood pressure were measured. M₂ receptor function was assessed by the potentiation by gallamine (an M₂ receptor antagonist) of bronchoconstriction caused by electrical stimulation of the vagus nerves and measured as increased pulmonary inflation pressure. Human airway epithelial cells were infected with influenza and TNF-α concentration in supernatant was measured before supernatant was applied to human neuroblastoma cells. M₂ receptor expression in these neuroblastoma cells was measured by qRT-PCR.

KEY RESULTS

Influenza-infected animals were hyperresponsive to vagal stimulation but not to intravenous ACh. Gallamine did not potentiate vagally induced bronchoconstriction in virus-infected animals, indicating M₂ receptor dysfunction. Etanercept prevented virus-induced airway hyperresponsiveness and M₂ receptor dysfunction, without changing lung viral titres. Etanercept caused a non-significant decrease in total cells, macrophages and neutrophils in bronchoalveolar lavage. Influenza infection significantly increased TNF-α release from isolated epithelial cells, sufficient to decrease M₂ receptors in neuroblastoma cells. This ability of supernatants from infected epithelial cells to inhibit M₂ receptor expression was blocked by etanercept.

CONCLUSIONS AND IMPLICATIONS

TNF-α is a key mediator of virus-induced M₂ muscarinic receptor dysfunction and airway hyperresponsiveness.

Monoclonal antibodies for chronic refractory asthma and pipeline developments

Patients with severe asthma suffer persistent symptoms and/or frequent exacerbations despite high-intensity treatment. Their severe unrelenting symptoms have a huge impact on healthcare resources owing to frequent hospital admissions and requirement for intensive treatments. Consequently, there is an undeniable need for more-effective and safer medications. Expanding knowledge of innate and adaptive immune responses is leading to the development of novel therapies for severe asthma. Herein, we review efficacy and safety data from human clinical trials of monoclonal antibodies that are approved or under investigation for use in asthma. Future drug candidates directed at key targets and the specific role of monoclonal antibodies in distinctively targeted sub-populations of severe asthmatics will be also discussed.

Monoclonal antibodies for the treatment of severe asthma

Patients with severe asthma have a significant unmet need with persistent symptoms and/or frequent exacerbations despite treatment with high-dose steroid and other currently available therapies. These patients are also at risk of developing steroid-related side effects, and their severe, unrelenting symptoms have a huge impact on health care resources due to frequent hospital admissions and requirement for intensive medication use. Consequently, a compelling need exists for more effective and safer pharmacotherapies to help them achieve adequate disease control. Recent novel therapies for severe asthma are now emerging, some of the most promising of which are monoclonal antibodies. Monoclonal antibodies represent a form of immunotherapy used in a wide variety of therapeutic roles. The spectrum of disease states in which monoclonal antibodies have been approved for therapeutic use now includes respiratory and allergic diseases. At present, only one drug is licensed for allergic asthmatics with severe disease, omalizumab. We review some of the currently available biologics that are approved or under investigation for use in severe asthma. Some have shown to be useful in specifically targeted subpopulations of patients with severe asthma, whereas other have proven to be unsafe and/or unsuccessful. Despite these developments, more effort should be devoted to identifying new molecular targets, testing innovative approaches, and establishing the best use of what is available. Regarding this latter point, identifying individual characteristics that predict successful responses to these treatments is highly desirable.

Infliximab alleviates inflammation and ex vivo airway hyperreactivity in asthmatic E3 rats

Tumor necrosis factor-α (TNF-α) has been implicated in the pathogenesis of asthma, and neutralization of TNF-α is an effective therapy for inflammatory diseases. The present study tested the idea that a TNF-α antibody, infliximab, may be useful in the management of asthma. E3 rats were immunized with ovalbumin (OVA)/alum and received infliximab intra-peritoneally. Two weeks later, OVA-PBS was instilled intranasally daily for 7 days. Bronchoalveolar lavage fluids (BALFs), serum and lung homogenates were collected for analysis of cells and inflammatory mediators. Contractile responses of lobar-bronchus segments to agonists were functionally tested. Pulmonary tissues were investigated using histological examination. The results showed that the sensitized 'model E3 rats' exhibited an increase in the total amount of inflammatory cells, primarily eosinophils, in BALF and pulmonary tissue, as well as epithelial damage. Serum levels of IgE increased and so did the levels of nitric oxide, inducible nitric oxide synthase, TNF-α and IL-4, IL-5 and IL-13 in lung homogenate and serum. Furthermore, the contractile responses in bronchi induced by endothelin-1, sarafotoxin 6c and bradykinin increased and isoprenaline-induced relaxations decreased. All these changes induced by the sensitization procedure were reduced by the infliximab treatment. The results suggest that infliximab prevents the development of local airway inflammation and antagonizes changes of the bronchial smooth muscle receptor phenotype, thereby blocking the development of airway smooth muscle hyperreactivity of asthmatic rats.

Immunomodulatory impact of a synbiotic in T(h)1 and T(h)2 models of infection

BACKGROUND AND METHODS

The immunomodulatory activity of a synbiotic combination containing three bacterial strains (Lactobacillus helveticus R0052, Bifidobacterium longum subsp. infantis R0033 and Bifidobacterium bifidum R0071) and short-chain fructooligosaccharide was examined in two distinct infectious rat models. In the T(h)1 model, Wistar rats were administered the synbiotic combination for 2 weeks prior to challenge with a single oral dose of enterotoxigenic Escherichia coli or vehicle. In the T(h)2 model, pretreated rats were challenged with a single subcutaneous dose of hook worm, Nippostrongylus brasiliensis. Blood samples were collected 3 hours or 4 days postchallenge and serum levels of pro- and anti-inflammatory cytokines were measured.

RESULTS

Significant reductions in pro-inflammatory cytokines interleukin (IL)-1α, IL-1β, IL-6, and tumour necrosis factor (TNF)-α were observed in both models suggesting a single, unifying mode of action on an upstream regulator. The N. brasiliensis study also compared the effect of the individual strains to synbiotic. For most of cytokines the combination appeared to average the effect of the individual strains with the exception of IL-4 and IL-10 where there was apparent synergy for the combination. Furthermore, the cytokine response varied by strain.

CONCLUSIONS

It was concluded that this synbiotic combination of these three microbes could be beneficial in both T(h)1 and T(h)2 diseases.

Recommendation for optimal management of severe refractory asthma

Patients whose asthma is not adequately controlled despite treatment with a combination of high dose inhaled corticosteroids and long-acting bronchodilators pose a major clinical challenge and an important health care problem. Patients with severe refractory disease often require regular oral corticosteroid use with an increased risk of steroid-related adverse events. Alternatively, immunomodulatory and biologic therapies may be considered, but they show wide variation in efficacy across studies thus limiting their generalizability. Managing asthma that is refractory to standard treatment requires a systematic approach to evaluate adherence, ensure a correct diagnosis, and identify coexisting disorders and trigger factors. In future, phenotyping of patients with severe refractory asthma will also become an important element of this systematic approach, because it could be of help in guiding and tailoring treatments. Here, we propose a pragmatic management approach in diagnosing and treating this challenging subset of asthmatic patients.

Use of biologicals as immunotherapy in asthma and related diseases

Recent advances in our understanding of the immune-mediated inflammatory pathways in asthma and other allergic diseases have resulted in the development of novel biological compounds for the treatment of these conditions. These compounds offer an advantage over glucocorticosteroid therapy by specifically targeting components of the immunologic cascade, thereby allowing patients to reduce or discontinue their glucocorticosteroid treatment. Another potential advantage of biological compounds is that they may provide additional anti-inflammatory benefits, over and above those provided by glucocorticosteroid therapy, for patients who continue to have evidence of refractory asthma. The anti-IgE monoclonal antibody omalizumab is already being used for the treatment of allergic asthma and a number of other biological therapies are currently in various stages of clinical development. The purpose of this review is to summarize the data from these studies and to provide a rationale for the use of these compounds in asthma and related allergic airway diseases.

Pharmacotherapy of severe asthma

Severe asthma is a complex and heterogeneous phenotype where management can be challenging. While many patients with severe asthma respond to high-dose inhaled corticosteroids in combination with a long-acting beta-agonist, there remains a significant subset of patients that require oral corticosteroids to control symptoms. Alternative therapies are needed to help reduce the need for continuous oral corticosteroids; however, there are currently very few effective options. Several new alternatives to oral corticosteroids have been evaluated in severe asthma as add-on to conventional therapy. These include macrolide antibiotics, omalizumab, tumor necrosis factor-alpha inhibitors, cytokine receptor antagonists, and bronchial thermoplasty. The challenge with these entities is determining the appropriate phenotype of severe asthma where effectiveness is demonstrated, given the significant heterogeneity of the disease. Therefore, there is a crucial need to better understand the mechanisms and pathophysiology of severe asthma so more effective immunomodulators and biologic therapies can emerge.

Low level laser therapy (LLLT): attenuation of cholinergic hyperreactivity, beta(2)-adrenergic hyporesponsiveness and TNF-alpha mRNA expression in rat bronchi segments in E. coli lipopolysaccharide-induced airway inflammation by a NF-kappaB dependent mechanism

BACKGROUND AND OBJECTIVES

It is unknown if the decreased ability to relax airways smooth muscles in asthma and other inflammatory disorders, such as acute respiratory distress syndrome (ARDS), can be influenced by low level laser therapy (LLLT) irradiation. In this context, the present work was developed in order to investigate if LLLT could reduce dysfunction in inflamed bronchi smooth muscles (BSM) in rats.

STUDY DESIGN/MATERIALS AND METHODS

A controlled ex vivo study was developed where bronchi from Wistar rat were dissected and mounted in an organ bath apparatus with or without a TNF-alpha.

RESULTS

LLLT administered perpendicularly to a point in the middle of the dissected bronchi with a wavelength of 655 nm and a dose of 2.6 J/cm(2), partially decreased BSM hyperreactivity to cholinergic agonist, restored BSM relaxation to isoproterenol and reduced the TNF-alpha mRNA expression. An NF-kappaB antagonist (BMS205820) blocked the LLLT effect on dysfunction in inflamed BSM.

CONCLUSION

The results obtained in this work indicate that the LLLT effect on alterations in responsiveness of airway smooth muscles observed in TNF-alpha-induced experimental acute lung inflammation seems to be dependent of NF-kappaB activation.

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.

Managing patients with chronic severe asthma: rise to the challenge

Most asthmatic patients with moderate to severe disease can be satisfactorily managed with a combination of inhaled corticosteroids and beta(2)-agonists. However, there are perhaps 10% of the asthmatic population with persistent symptoms, impaired quality of life and excessive health-care utilization, despite this management regime. These patients often require frequent and even occasionally regular oral corticosteroid use. Chronic, severe asthma is a heterogeneous disease with distinct sub-phenotypes. A systematic diagnostic work-up may help to identify these distinct sub-phenotypes and this may help guide treatment and may even provide information about prognosis. Optimal treatment of chronic severe asthma should achieve the best possible asthma control and quality of life with the least dose of systemic corticosteroids. The choice and formulation of therapeutic agent is dictated by the severity of disease and includes conventional, immunosuppressive/immunomodulating and biologic therapies. Unfortunately, current asthma management guidelines offer little contribution to the care of the challenging patient with chronic severe asthma. This review article aims at summarizing the evidence regarding various therapeutic modalities for chronic severe asthma and also aims to provide a practical approach to diagnosis and management for the benefit of those who have a specific interest in this problematic condition.

Cytokine-producing effector B cells regulate type 2 immunity to H. polygyrus

Immunity to the intestinal parasite Heligomosomoides polygyrus is dependent on the successful generation of T helper 2 (Th2) memory cells. We showed that B cells contribute to immunity against H. polygyrus by producing antibody (Ab) and by promoting expansion and differentiation of primary and memory Th2 cells. We also demonstrated that cytokine-producing effector B cells were essential for effective immunity to H. polygyrus. Tumor necrosis factor alpha production by B cells was necessary for sustained Ab production, whereas interleukin 2 production by B cells was necessary for Th2 cell expansion and differentiation. These results show that B cells mediate protection from pathogens not only by presenting antigen and secreting antibody but also by producing cytokines that regulate the quality and magnitude of humoral and cellular immune responses.

Asthma: a syndrome composed of heterogeneous diseases

OBJECTIVE

To review the concept that asthma comprises distinct heterogeneous inflammatory disorders characterized by patients showing different phenotypes with distinct genetic components, environmental causes, and immunopathologic signa-

DATA SOURCES

Ovid MEDLINE and PubMed databases from 1950 to the present time were searched for relevant articles and references regarding the heterogeneity of asthma.

STUDY SELECTION

Articles that described the various phenotypes of asthma were used for this review.

RESULTS

Asthma is unlikely to be a single disease but rather a series of complex, overlapping individual diseases or phenotypes, each defined by its unique interaction between genetic and environmental factors. These conditions include syndromes characterized by allergen-exacerbated, nonallergic, and aspirin-exacerbated factors along with syndromes best distinguished by their pathologic findings (eosinophilic, neutrophilic, pauci-granulocytic), response to therapy (corticosteroid resistant), and natural history (remodeling prone). Additional phenotypes will almost certainly be identified as advances in genetics and other profiling methods are made and will be accompanied by the availability of clear biomarkers for distinguishing among them.

CONCLUSIONS

Responses to asthma medications vary considerably among patients, likely reflecting, at least in part, the differing sensitivities of the various asthma phenotypes. Selecting the best possible treatment course in individual patients will be aided by clearly identifying the different phenotypes. Physicians need to recognize this when making decisions to adjust treatment to improve asthma control.

Low level laser therapy (LLLT) decreases pulmonary microvascular leakage, neutrophil influx and IL-1beta levels in airway and lung from rat subjected to LPS-induced inflammation

BACKGROUND AND OBJECTIVE

Low level laser therapy (LLLT) is a known anti-inflammatory therapy. Herein we studied the effect of LLLT on lung permeability and the IL-1beta level in LPS-induced pulmonary inflammation. STUDY DESIGN/METHODOLOGY: Rats were divided into 12 groups (n = 7 for each group). Lung permeability was measured by quantifying extravasated albumin concentration in lung homogenate, inflammatory cells influx was determined by myeloperoxidase activity, IL-1beta in BAL was determined by ELISA and IL-1beta mRNA expression in trachea was evaluated by RT-PCR. The rats were irradiated on the skin over the upper bronchus at the site of tracheotomy after LPS.

RESULTS

LLLT attenuated lung permeability. In addition, there was reduced neutrophil influx, myeloperoxidase activity and both IL-1beta in BAL and IL-1beta mRNA expression in trachea obtained from animals subjected to LPS-induced inflammation.

CONCLUSION

LLLT reduced the lung permeability by a mechanism in which the IL-1beta seems to have an important role.

Targeting TNF-alpha: a novel therapeutic approach for asthma

Approximately 5% to 10% of patients with asthma have severe disease that is refractory or poorly responsive to inhaled corticosteroid therapy. These patients represent an important unmet clinical need because they experience considerable morbidity and mortality and consume a disproportionately large amount of health care resources. TNF-alpha is a proinflammatory cytokine that has been implicated in many aspects of the airway pathology in asthma. Evidence is emerging to suggest that it might play an important role in severe refractory disease. The development of novel TNF-alpha antagonists has allowed us to test the role of this cytokine in vivo. Preliminary studies have demonstrated an improvement in asthma quality of life, lung function, and airway hyperresponsiveness and a reduction in exacerbation frequency in patients treated with anti-TNF-alpha therapy. However, there is marked heterogeneity in response, suggesting that benefit is likely to be reserved to a small subgroup. Importantly, where efficacy is reported, this also needs to be considered in the context of concerns about the safety of anti-TNF-alpha therapies. Therefore the challenge for clinicians is to evaluate the risk/benefit ratio of these therapies in individual patients with asthma.

Enhanced osteopontin expression in a murine model of allergen-induced airway remodelling

BACKGROUND

Airway remodelling is a central pathophysiological feature of chronic asthma. A wide variety of cytokines and growth factors are likely to be involved in the development of airway remodelling. Osteopontin (OPN) is a cytokine with pro-fibrotic properties; however, its role in airway remodelling in asthma has not been explored.

OBJECTIVE

To determine the expression and cellular sources of OPN in a murine model of chronic allergen-induced airway remodelling.

METHODS

BALB/c mice were sensitized and exposed to ovalbumin (OVA) or saline inhalations for 5 weeks and killed 24 h after the last inhalation. The following parameters of inflammation and remodelling were assessed: differential cell counts in bronchoalveolar lavage (BAL) fluid lung collagen content (colorimetric biochemical assay) and peribronchial smooth muscle content (immunohistochemistry, followed by image analysis). OPN expression in BAL and lung tissue was determined by PCR and ELISA. The cellular source and distribution of OPN were evaluated by immunohistochemistry and immunofluorescence.

RESULTS

OPN expression is up-regulated in lung tissue and in BAL fluid of OVA-treated mice and correlates with collagen content and peribronchial smooth muscle area. In addition, OPN significantly increases collagen deposition in vitro in a murine lung cell line. Cells producing OPN include the airway epithelium and cells of the submucosal inflammatory infiltrate (T cells, eosinophils, and macrophages). Positive staining for OPN was also observed in bronchial tissue from human asthmatic subjects.

CONCLUSION

OPN expression in the lungs is increased in a murine model of allergen-induced chronic airway remodelling, suggesting a role for this cytokine in airway remodelling in asthma.

Allergen-induced CD11b+ CD11c(int) CCR3+ macrophages in the lung promote eosinophilic airway inflammation in a mouse asthma model

Although the recruitment of macrophages to the lung is a central feature of airway inflammation, its function in ongoing T(h)2 cell-mediated eosinophilic airway inflammation remains controversial. Here, we have demonstrated that the allergen-induced CD11b(+) CD11c(int) macrophage expressing CC chemokine receptor 3 (CCR3) in the lung performs a crucial function in the induction of eosinophilic asthma in a murine model. In the lungs of normal mice, residential cells evidencing high granularity phenotypically evidenced CD11b(int) CD11c(+) or CD11b(+) CD11c(int) cells, appearing at a 2:1 ratio. After allergen challenge, however, this reverses dramatically, up to a ratio of one to six. Approximately 91% of increased CD11b(+) CD11c(int) cells evidenced the expression of the CCR3 eotaxin receptor, but not other chemokine receptors, such as CCR5 and CXCR4. Interestingly, the CD11b(+) CD11c(int) cells purified from the lungs of OVA (ovalbumin)-sensitized and challenged mice evidenced higher antigen-presenting activity than was observed in CD11b(int) CD11c(+) cells. In order to investigate the in vivo function of CD11b(+) CD11c(int) cells, the cells were isolated from the lungs of OVA-sensitized and challenged mice and then adoptively transferred prior to the allergen challenge of normal mice. In the CD11b(+) CD11c(int)-transferred mice airway hyperresponsiveness, eosinophilic inflammation in the lung and T(h)2 cytokine secretion in the bronchoalveolar lavage fluids were significantly enhanced as the result of OVA challenge, as compared with the mice that received OVA-primed CD90(+) T cells or CD11b(int) CD11c(+) cells. These findings show that CD11b(+) CD11c(int) macrophages expressing CCR3 as key pro-inflammatory cells are both necessary and sufficient for allergen-specific T cell stimulation during ongoing eosinophilic airway inflammation.

Treating allergic rhinitis and asthma: different sides of the same fence

Allergic asthma and rhinitis are highly prevalent diseases. Although they are diagnosed and treated separately, many patients suffer from both. There is data suggesting that they can be considered as manifestations of the same disease or syndrome, but in different locations. This article discusses the evidence favouring a joint clinical approach, and the main therapeutic tactics to achieve disease control; tries to establish the importance of isolated and adjuvant treatment of rhinitis and asthma, highlighting a small number of clinical studies regarding the subject; and indicates points for future research.

TNFalpha blockade in human diseases: an overview of efficacy and safety

Tumor necrosis factor-alpha (TNFalpha) antagonists including antibodies and soluble receptors have shown remarkable efficacy in various immune-mediated inflammatory diseases (IMID). As experience with these agents has matured, there is an emerging need to integrate and critically assess the utility of these agents across disease states and clinical sub-specialties. Their remarkable efficacy in reducing chronic damage in Crohn's disease and rheumatoid arthritis has led many investigators to propose a new, 'top down' paradigm for treating patients initially with aggressive regimens to quickly control disease. Intriguingly, in diseases such as rheumatoid arthritis and asthma, anti-TNFalpha agents appear to more profoundly benefit patients with more chronic stages of disease but have a relatively weaker or little effect in early disease. While the spectrum of therapeutic efficacy of TNFalpha antagonists widens to include diseases such as recalcitrant uveitis and vasculitis, these agents have failed or even exacerbated diseases such as heart failure and multiple sclerosis. Increasing use of these agents has also led to recognition of new toxicities as well as to understanding of their excellent long-term tolerability. Disconcertingly, new cases of active tuberculosis still occur in patients treated with all TNFalpha antagonists due to lack of compliance with recommendations to prevent reactivation of latent tuberculosis infection. These safety issues as well as guidelines to prevent treatment-associated complications are reviewed in detail in this article. New data on mechanisms of action and development of newer TNFalpha antagonists are discussed in a subsequent article in the Journal. It is hoped that these two review articles will stimulate a fresh assessment of the priorities for research and clinical innovation to improve and extend therapeutic use and safety of TNFalpha antagonism.

Cysteinyl leukotrienes enhance tumour necrosis factor-alpha-induced matrix metalloproteinase-9 in human monocytes/macrophages

BACKGROUND

Matrix metalloproteinase-9 (MMP-9) is an important enzyme responsible for airway remodelling. Monocytes/macrophages have a cysteinyl leukotriene 1 (cysLT1) receptor, but its function is poorly understood.

OBJECTIVE

To elucidate the function of the cysLT1 receptor of human monocytes/macrophages in MMP-9 production.

METHODS

We examined the effect of cysLTs (LTC4, -D4 and -E4) on TNF-alpha-induced MMP-9 production in THP-1 cells, a human monocytic leukaemia cell line and peripheral blood CD14+ monocytes/macrophages. In addition, we examined the effect of pranlukast, a cysLT1 receptor antagonist, on the enhancement of TNF-alpha-induced MMP-9 production by cysLTs.

RESULTS

ELISA revealed that LTC4 and -D4, but not -E4, enhanced TNF-alpha-induced MMP-9 production in THP-1 cells and peripheral blood CD14+ monocytes/macrophages. Real-time polymerase chain reaction demonstrated that LTC4 and -D4, but not -E4, increased MMP-9 mRNA expression induced by TNF-alpha in THP-1 cells. Moreover, we demonstrated that pranlukast completely inhibited the enhancement of TNF-alpha-induced MMP-9 production by LTC4 and -D4 in THP-1 cells and peripheral blood CD14+ monocytes/macrophages.

CONCLUSION

LTC4 and -D4 enhanced the TNF-alpha-induced MMP-9 production via binding the cysLT1 receptor in human monocytes/macrophages. Pranlukast inhibited the enhancements by LTC4 and D4.

Simultaneous evaluation of circulating chemokine and cytokine profiles in elderly subjects by multiplex technology: relationship with zinc status

Cellular components of both adaptive and innate immune systems produce different chemokines and cytokines, involved in different signalling pathways among cells, and modulate effector function during immune response, playing a key role in the regulation of the type and extent of the immune response in the elderly. We evaluated the circulating concentration of selected chemokines: MCP-1, MIP-1alpha, IL-8, RANTES together with IL-6 and TNF-alpha in plasma obtained from a group of healthy old subjects, in order to highlight possible differences in the synthesis of these factors, assuming that both the cytokine and the chemokine networks are remodelled with ageing. The simultaneous evaluation was performed by a multiplex analysis system. In addition, since micronutrient deficiency may underlie an inflammatory response, the association between chemokine levels and a nutritional element such as zinc was also evaluated, since the immune system is the first system to be affected by changing zinc levels, due to its high cell turnover. A progressive age-related increase of plasma concentrations of all soluble factors was observed. The increment was particularly evident for IL-6, IL-8, MCP-1 and TNF-alpha in the over 85-year-old group in concomitance with increasing percentages of subjects with low circulating levels of zinc. In conclusion, the remodelling of chemokine profiles, skewed to Th2 response by both advanced ages and circulating levels of zinc, might reflect different states of activation and/or responsiveness of the human immune cell/mediator network, thus influencing the ability to develop rapid innate and long-lasting adaptive immune responses with advancing age.

Immunomodulatory effects of macrolide antibiotics in respiratory disease: therapeutic implications for asthma and cystic fibrosis

The macrolide antibiotics are a family of related 14- or 15-membered lactone ring antibiotics. There has been recent interest in the beneficial effects of these drugs as immune modulators in respiratory conditions in children. Cystic fibrosis (CF) and asthma, both of which occur in childhood, have an underlying inflammatory component and are associated with significant morbidity. The pathogenesis of both conditions is poorly understood but several molecular mechanisms have been suggested. In CF, these mechanisms broadly involve altered chloride transport and alteration of the airway surface liquid with disordered neutrophilic inflammation. There is much evidence for a proinflammatory propensity in CF immune effector and epithelial cells and many studies indicate that macrolides modulate these inflammatory processes. Recent studies have confirmed a clinical improvement in CF following treatment with macrolides, but the exact mechanisms by which they work are unknown. Asthma is likely to represent several different phenotypes but in all of these, airway obstruction, bronchial hyperresponsiveness, and inflammation are central processes. Results from trials using macrolides have suggested an improvement in clinical outcome. The putative mechanisms of macrolide immunomodulatory action include improvement of the primary defense mechanisms, inhibition of the bacteria-epithelial cell interaction, modulation of the signaling pathway and chemokine release, and direct neutrophil effects. Putative mechanisms of phenotypic modulation have also been proposed involving interactions with nitric oxide, endothelin-1, and bronchoconstriction, endothelial growth factors and airway remodeling, and bioactive phospholipids in both CF and asthma. Further characterization of these effects and development of targeted designer drugs will further expand our therapeutic repertoire and lead to improved quality and quantity of life for patients with CF and asthma.

A functional CD86 polymorphism associated with asthma and related allergic disorders

BACKGROUND

Several studies have documented a substantial genetic component in the aetiology of allergic diseases and a number of atopy susceptibility loci have been suggested. One of these loci is 3q21, at which linkage to multiple atopy phenotypes has been reported. This region harbours the CD86 gene encoding the costimulatory B7.2 protein. The costimulatory system, consisting of receptor proteins, cytokines and associated factors, activates T cells and regulates the immune response upon allergen challenge.

METHODS

We sequenced the CD86 gene in patients with atopy from 10 families that showed evidence of linkage to 3q21. Identified polymorphisms were analysed in a subsequent family-based association study of two independent Danish samples, respectively comprising 135 and 100 trios of children with atopy and their parents. Functional analysis of the costimulatory effect on cytokine production was performed in an autologous cell-based system based on cells expressing CD86 variants.

RESULTS

Two polymorphisms were identified, encoding the amino acid changes Ile179Val and Ala304Thr, respectively. Significant associations were observed between the Ile179Val polymorphism and allergy phenotypes in both samples (eg, asthma, p = 4 x 10(-3) in the two samples combined). The undertransmitted (protective) Val179 allele was found to induce higher production of both Th1 and Th2 cytokines than the overtransmitted (risk) Ile179 allele, suggesting a functional impact of the polymorphism.

CONCLUSION

The CD86 gene, and specifically the Ile179Val polymorphism, may be a novel aetiological factor in the development of asthma and related allergic disorders.

Asthma phenotypes

PURPOSE OF REVIEW

Asthma is a heterogeneous disorder presenting with many phenotypes. Precise phenotypic definition has eluded the medical research community for years, despite recognition of different disease subtypes. Improved phenotypic characterization and knowledge of underlying pathobiology is necessary for linkage of specific genotypes with clinical disease manifestations.

RECENT FINDINGS

Phenotyping has been difficult because asthma is likely to be comprised of overlapping syndromes with varying origins and heterogeneous pathobiology. Currently, the field is too reliant on classification by trigger or symptoms. Since genotypic and phenotypic heterogeneity are inherent in asthma, patients presenting with different asthma phenotypes may need tailored therapies. Studies have begun to link genetics with disease mechanism and therapeutic response. As disease etiology, onset, progression and severity vary greatly among patients, however, the relative contribution of genetic factors may be difficult to ascertain. Definition of the full array of complex biological consequences of molecular target modulation is a prerequisite for therapies based on this concept.

SUMMARY

The advent of targeted therapies for asthma and clinical trials based on phenotype and genotype have raised interest in more accurate description of asthma phenotypes. Therapies based on phenotypic and genotypic characteristics may be useful in asthma management. A variety of factors, however, must be addressed before such approaches become standard.

The mechanisms, diagnosis, and management of severe asthma in adults

There has been a recent increase in the prevalence of asthma worldwide; however, the 5-10% of patients with severe disease account for a substantial proportion of the health costs. Although most asthma cases can be satisfactorily managed with a combination of anti-inflammatory drugs and bronchodilators, patients who remain symptomatic despite maximum combination treatment represent a heterogeneous group consisting of those who are under-treated or non-adherent with their prescribed medication. After excluding under-treatment and poor compliance, corticosteroid refractory asthma can be identified as a subphenotype characterised by a heightened neutrophilic airway inflammatory response in the presence or absence of eosinophils, with evidence of increased tissue injury and remodelling. Although a wide range of environmental factors such as allergens, smoking, air pollution, infection, hormones, and specific drugs can contribute to this phenotype, other features associated with changes in the airway inflammatory response should be taken into account. Aberrant communication between an injured airway epithelium and underlying mesenchyme contributes to disease chronicity and refractoriness to corticosteroids. The importance of identifying underlying causative factors and the recent introduction of novel therapeutic approaches, including the targeting of immunoglobulin E and tumour necrosis factor alpha with biological agents, emphasise the need for careful phenotyping of patients with severe disease to target improved management of the individual patient's needs.