Role of tumor necrosis factor alpha in asthma

Weighted Breaths: Exploring Biologic and Non-Biologic Therapies for Co-Existing Asthma and Obesity

PURPOSE OF REVIEW

To discuss the effectiveness of biologics, some of which comprise the newest class of asthma controller medications, and non-biologics in the treatment of asthma co-existing with obesity.

RECENT FINDINGS

Our review of recent preliminary and published data from clinical trials revealed that obese asthmatics respond favorably to dupilumab, mepolizumab, omalizumab, and tezepelumab, which are biologics currently indicated as add-on maintenance therapy for severe asthma. Furthermore, clinical trials are ongoing to assess the efficacy of non-biologics in the treatment of obese asthma, including a glucagon-like peptide-1 receptor agonist, a Janus kinase inhibitor, and probiotics. Although many biologics presently indicated as add-on maintenance therapy for severe asthma exhibit efficacy in obese asthmatics, other phenotypes of asthma co-existing with obesity may be refractory to these medications. Thus, to improve quality of life and asthma control, it is imperative to identify therapeutic options for all existing phenotypes of obese asthma.

Transcriptomics analysis of allergen-induced inflammatory gene expression in the Four-Core Genotype mouse model

Sex differences in allergic inflammation have been reported, but the mechanisms underlying these differences remain unknown. Contributions of both sex hormones and sex-related genes to these mechanisms have been previously suggested in clinical and animal studies. Here, Four-Core Genotypes (FCG) mouse model was used to study the inflammatory response to house dust mite (HDM) challenge and identify differentially expressed genes (DEGs) and regulatory pathways in lung tissue. Briefly, adult mice (8-10 wk old) of the FCG (XXM, XXF, XYM, XYF) were challenged intranasally with 25 μg of HDM or vehicle (PBS-control group) 5 days/wk for 5 wk (n = 3/10 group). At 72 h after the last exposure, we analyzed the eosinophils and neutrophils in the bronchoalveolar lavage (BAL) of FCG mice. We extracted lung tissue and determined DEGs using Templated Oligo-Sequencing (TempO-Seq). DEG analysis was performed using the DESeq2 package and gene enrichment analysis was done using Ingenuity Pathway Analysis. A total of 2,863 DEGs were identified in the FCG. Results revealed increased eosinophilia and neutrophilia in the HDM-treated group with the most significantly expressed genes in XYF phenotype and a predominant effect of female hormones vs. chromosomes. Regardless of the sex hormones, mice with female chromosomes had more downregulated genes in the HDM group but this was reversed in the control group. Interestingly, genes associated with inflammatory responses were overrepresented in the XXM and XYF genotypes treated with HDM. Sex hormones and chromosomes contribute to inflammatory responses to HDM challenge, with female hormones exerting a predominant effect mediated by inflammatory DEGs.NEW & NOTEWORTHY Gene expression profiling helps to provide deep insight into the global view of disease-related mechanisms and responses to therapy. Using the Four-Core Genotype mouse model, our findings revealed the influence of sex hormones and sex chromosomes in the gene expression of lungs exposed to an aeroallergen (House Dust Mite) and identified sex-specific pathways to better understand sex disparities associated with allergic airway inflammation.

Molecular mechanism of Ferula asafoetida for the treatment of asthma: Network pharmacology and molecular docking approach

Asthma is a significant health-care burden that has great impact on the quality of life of patients and their families. The limited amount of previously reported data and complicated pathophysiology of asthma make it a difficult to treat and significant economic burden on public healthcare systems. Ferula asafoetida is an herbaceous, monoecious, perennial plant of the Umbelliferae family. In Asia, F. asafoetida is used to treat a range of diseases and disorders, including asthma. Several in vitro studies demonstrated the therapeutic efficacy of F. asafoetida against asthma. Nevertheless, the precise molecular mechanism is yet to be discovered. In the framework of current study, network pharmacology approach was used to identify the bioactive compounds of F. asafoetida in order to better understand its molecular mechanism for the treatment of asthma. In present work, we explored a compound-target-pathway network and discovered that assafoetidin, cynaroside, farnesiferol-B, farnesiferol-C, galbanic-acid, and luteolin significantly influenced the development of asthma by targeting MAPK3, AKT1 and TNF genes. Later, docking analysis revealed that active constituents of F. asafoetida bind stably with three target proteins and function as asthma repressor by regulating the expression of MAPK3, AKT1 and TNF genes. Thus, integration of network pharmacology with molecular docking revealed that F. asafoetida prevent asthma by modulating asthma-related signaling pathways. This study lays the basis for establishing the efficacy of multi-component, multi-target compound formulae, as well as investigating new therapeutic targets for asthma.

Role of Ezrin in Asthma-Related Airway Inflammation and Remodeling

Ezrin is an actin binding protein connecting the cell membrane and the cytoskeleton, which is crucial to maintaining cell morphology, intercellular adhesion, and cytoskeleton remodeling. Asthma involves dysfunction of inflammatory cells, cytokines, and airway structural cells. Recent studies have shown that ezrin, whose function is affected by extensive phosphorylation and protein interactions, is closely associated with asthma, may be a therapeutic target for asthma treatment. In this review, we summarize studies on ezrin and discuss its role in asthma-related airway inflammation and remodeling.

Evaluation of IGF-1, TNF-α, and TGF-β Gene Expression after Oral Vitamin D Supplementation in School-Aged Children with Chronic Bronchial Asthma

BACKGROUND: Airway remodeling in children with bronchial asthma is due to the effect of inflammatory mediators and growth factors on the bronchial epithelium. Vitamin D (VitD) has immunomodulatory effect in many inflammatory diseases as bronchial asthma. The ant-inflammatory and anti-fibrotic role of VitD could prevent or improve air way remodeling in asthmatic patients. AIM: The study investigated the effect of VitD supplementation on the expression of transforming growth factor-beta (TGF-β), tumor necrosis factor-alpha (TNF-α), and insulin growth factor 1(IGF-1) and to correlate them with asthma severity and level of control. METHODS: The serum level of VitD and the mRNA expression of IGF-1, TGF-β, and TNF-α were estimated in 50 patients and 20 healthy controls control subjects using quantitative PCR in real-time. Asthmatic patients with VitD deficiency received VitD supplementation for 2 months followed by remeasurement of serum VitD and the genes expression TGF-β, TNF-α, and IGF-1. RESULT: Pre-intake of VitD and serum level of VitD were lower in all patients than control subjects (p = 0.005). VitD level was directly correlated with IGF-1 mRNA expression, which was indirectly correlated with TGF-β, r = 0.5 and −0.57; p = 0.0001 and 0.002, respectively. After VitD supplementation, the expression of the TGF-β mRNA gene was the only gene that decreased significantly (p = 0.04) together with improved asthma control and spirometric parameters. CONCLUSIONS: VitD supplementation down regulated the gene expression of TGF-β and improved asthma control level, but it did not significantly affect the gene expression of TNF-α and IGF-1.

Amelioration of Ovalbumin-Induced Allergic Asthma by Juglans regia via Downregulation of Inflammatory Cytokines and Upregulation of Aquaporin-1 and Aquaporin-5 in Mice

Juglans regia (J. regia) has been used traditionally to treat cough and asthma. The present study evaluates the immunomodulatory and anti-inflammatory potential of J. regia against ovalbumin (OVA)-induced allergic asthma. Intraperitoneal sensitization proceeded by intranasal challenge with OVA was used to induce allergic asthma. BALB/c mice were treated with methanol, n-hexane, and ethyl acetate extracts of J. regia and methylprednisolone one week after 2^nd sensitization with OVA and continued for 7 days. mRNA expression levels of IL-4, IL-5, IL-13, AQP-1, AQP-5 TNF-α, TGF-β, and NF-kB were determined using reverse transcription polymerase chain reaction. Hematoxylin and eosin, and periodic acidic-Schiff stains were used for histopathological studies of lung tissues. The data presented all three extracts of J. regia significantly ameliorated airway inflammation by reducing expression levels of IL-4, IL-5, and IL-13 and TNF-α in OVA-treated mice. The suppression of goblet cells hyperplasia and inflammatory cells infiltration by J. regia involved low TGF-β and NF-kB levels. Pretreatment with J. regia also increased the AQP-1 and AQP-5 expression levels in mice treated with OVA. This study supported the traditional use of J. regia and proposed that J. regia ameliorated allergic asthma by suppression of proinflammatory cytokines and elevation of AQP-1 and AQP-5 expression levels.

Association between particulate matter containing EPFRs and neutrophilic asthma through AhR and Th17

BACKGROUND

Epidemiological data associate high levels of combustion-derived particulate matter (PM) with deleterious respiratory outcomes, but the mechanism underlying those outcomes remains elusive. It has been acknowledged by the World Health Organization that PM exposure contributes to more than 4.2 million all-cause mortalities worldwide each year. Current literature demonstrates that PM exacerbates respiratory diseases, impairs lung function, results in chronic respiratory illnesses, and is associated with increased mortality. The proposed mechanisms revolve around oxidative stress and inflammation promoting pulmonary physiological remodeling. However, our previous data found that PM is capable of inducing T helper cell 17 (Th17) immune responses via aryl hydrocarbon receptor (Ahr) activation, which was associated with neutrophilic invasion characteristic of steroid insensitive asthma.

METHODS

In the present study, we utilized a combination of microarray and single cell RNA sequencing data to analyze the immunological landscape in mouse lungs following acute exposure to combustion derived particulate matter.

RESULTS

We present data that suggest epithelial cells produce specific cytokines in the aryl hydrocarbon receptor (Ahr) pathway that inform dendritic cells to initiate the production of pathogenic T helper (eTh17) cells. Using single-cell RNA sequencing analysis, we observed that upon exposure epithelial cells acquire a transcriptomic profile indicative of increased Il-17 signaling, Ahr activation, Egfr signaling, and T cell receptor and co-stimulatory signaling pathways. Epithelial cells further showed, Ahr activation is brought on by Ahr/ARNT nuclear translocation and activation of tyrosine kinase c-src, Egfr, and subsequently Erk1/2 pathways.

CONCLUSIONS

Collectively, our data corroborates that PM initiates an eTh17 specific inflammatory response causing neutrophilic asthma through pathways in epithelial, dendritic, and T cells that promote eTh17 differentiation during initial PM exposure.

Asthmatic condition induced the activity of exosome secretory pathway in rat pulmonary tissues

BACKGROUND

The recent studies highlighted the critical role of exosomes in the regulation of inflammation. Here, we investigated the dynamic biogenesis of the exosomes in the rat model of asthma.

RESULTS

Our finding showed an increase in the expression of IL-4 and the suppression of IL-10 in asthmatic lung tissues compared to the control samples (p < 0.05). Along with the promotion of IL-4, the protein level of TNF-α was induced, showing an active inflammatory status in OVA-sensitized rats. According to our data, the promotion of asthmatic responses increased exosome biogenesis indicated by increased CD63 levels and acetylcholine esterase activity compared to the normal condition (p < 0.05).

CONCLUSION

Data suggest that the stimulation of inflammatory response in asthmatic rats could simultaneously increase the paracrine activity of pulmonary cells via the exosome biogenesis. Exosome biogenesis may correlate with the inflammatory response.

Role of metalloproteinases and TNF-α in obesity-associated asthma in mice

Numerous population studies conducted worldwide indicate that the prevalence of asthma is higher in obese versus lean individuals. It has been reported that sensitized lean mice has a better recovery of lung inflammation in asthma. Extracellular matrix (ECM) plays an essential role in the structural support of the lungs regulating the airways diameter, thus preventing its collapse during expiration. ECM renewal by metalloproteinase (MMPs) enzymes is critical for pulmonary biology. There seems to be an imbalance of MMPs activity in asthma and obesity, which can impair the lung remodeling process. In this study, we characterized the pulmonary ECM of obese and lean mice, non-sensitized and sensitized with ovalbumin (OVA). Pharmacological intervention was performed by using anti-TNF-α, and MMP-8 and MMP-9 inhibitors in obese and lean sensitized mice. Activity of MMPs was assessed by gelatinase electrophorese, western blotting and zymogram in situ. Unbalance of MMP-2, MMP-8, MMP-9 and MMP-12 was detected in lung tissue of OVA-sensitized obese mice, which was accompanied by high degradation, corroborating an excessive deposition of types I and III collagen in pulmonary matrix of obese animals. Inhibitions of TNF-α and MMP-9 reduced this MMP imbalance, clearly suggesting a positive effect on pulmonary ECM. Obese and lean mice presented diverse phenotype of asthma regarding the ECM compounds and the inhibition of MMPs pathway could be a good alternative to regulate the activity in ECM lungs of asthmatic obese individuals.

Immunomodulatory and Anti-Inflammatory Potential of Curcumin for the Treatment of Allergic Asthma: Effects on Expression Levels of Pro-inflammatory Cytokines and Aquaporins

Curcumin is well known for possessing anti-inflammatory properties and for its beneficial effects in the treatment of asthma. Current study investigates the immunomodulatory and anti-inflammatory effects of curcumin using mouse model of ovalbumin-induced allergic asthma. BALB/c mice were immunized with ovalbumin on day 0 and 14 to induce allergic asthma. Animals were treated with two different doses of curcumin (20 mg/kg and 100 mg/kg) and methylprednisolone from day 21 to 28. Mice were also daily challenged intranasally with ovalbumin during treatment period, and all groups were sacrificed at day 28. Histopathological examination showed amelioration of allergic asthma in treated groups as evident by the attenuation of infiltration of inflammatory cells, goblet cell hyperplasia, alveolar thickening, and edema and vascular congestion. Curcumin significantly reduced total and differential leukocyte counts in both bronchoalveolar lavage fluid and blood. Reverse transcription polymerase chain reaction analysis showed significantly suppressed mRNA expression levels of IL-4 and IL-5 (pro-inflammatory cytokines), TNF-α, TGF-β (pro-fibrotic cytokines), eotaxin (chemokine), and heat shock protein 70 (marker of airway obstruction) in treated groups. Attenuation of these pro-inflammatory markers might have led to the suppression of airway inflammation. The expression levels of aquaporin-1 (AQP) and AQP-5 were found significantly elevated in experimental groups which might be responsible for reduction of pulmonary edema. In conclusion, curcumin significantly ameliorated allergic asthma. The anti-asthmatic effect might be attributed to the suppression of pro-inflammatory cytokines, and elevation of aquaporin expression levels, suggesting further studies and clinical trials to establish its candidature in the treatment of allergic asthma.

An inflammatory stimulus sensitizes TRPA1 channel to increase cytokine release in human lung fibroblasts

External stimuli such as cigarette smoke and house dust mite are often involved in the development and exacerbation of asthma. These risk factors could activate or sensitize transient receptor potential channel ankyrin 1 (TRPA1), which are primarily expressed in neuronal structures but also in non-neuronal cells such as fibroblasts. However, the role of non-neuronal TRPA1 in the pathophysiology of airway diseases including asthma remains unclear. We investigated TRPA1 expression on human fibroblast cells and whether inflammatory mediators could modulate its function. This study utilized human lung fibroblast cell lines, Medical Research Council cell strain 5 (MRC-5) and HF19 cells frequently used on experimental studies regarding allergic and respiratory disorders. The human lung fibroblasts were stimulated with house dust mite (Der p1) or tumor necrosis factor alpha (TNF-α) for 24 h, and we quantified TRPA1 mRNA and protein by qRT-PCR and western blot analysis, respectively. TRPA1 mRNA expressions were upregulated after TNF-α treatment. Calcium imaging analysis revealed that TNF-α treatment apparently sensitized TRPA1-mediated calcium influx by TRPA1 agonist allyl isothiocyanate (AITC) and the selective TRPA1 channel blocker HC-030031 effectively reduced the calcium response. Lastly, TRPA1 activation was not only involved in increased IL-8 cytokine release, but also in upregulating gene expression of matrix metalloprotease 9 (MMP9) in the human lung fibroblasts treated with TNF-α Together, these results indicate that presence of inflammatory mediators such as TNF-α could upregulate the non-neuronal expression of TRPA1 on fibroblasts which may aggravate further the release of inflammatory cytokines observed in human airway diseases.

Evaluation of the proinflammatory effects of contaminated bathing water

Contaminated marine bathing water has been reported to adversely affect human health. Our data demonstrated a correlation between total endotoxin (lipopolysaccharide; LPS) levels and degree of contamination of marine bathing waters. To assess the potential health implications of LPS present in marine bathing waters, the inflammation-inducing potency of water samples collected at different time points at multiple sampling sites were assessed using a cell culture-based assay. The numbers of fecal indicator bacteria (FIB) were also examined in the same samples. Water samples were used to stimulate two cell culture models: (1) a novel non-transformed continuously growing murine cell line Max Plank Institute (MPI) characteristic of alveolar macrophages and (2) human MonoMac 6 monocyte cell line. The inflammatory potential of the samples was assessed by measuring the release of inflammatory cytokines. The presence of high levels of LPS in contaminated bathing water led to induction of inflammatory response from our in vitro cell-based bioassays suggesting its potential health impact. This finding introduces an in vitro culture assay that reflects the level of LPS in water samples. These observations further promote previous finding that LPS is a reliable surrogate biomarker for fecal contamination of bathing water.

Respiratory Administration of Infliximab Dry Powder for Local Suppression of Inflammation

The airways are verified as a relevant route to improve antibody therapeutic index with superior lung concentration but limited passage into systemic blood stream. The current research aimed to process spray-dried (SD) powder of Infliximab to assess the feasibility of respiratory delivery of antibody for local suppression of lung-secreted tumor necrosis factor α (TNFα). Molecular and structural stability of powders were determined through size exclusion chromatography (SEC-HPLC) and Fourier transform infrared (FTIR) spectroscopy. Particle properties were characterized by laser light scattering, twin stage impinger (TSI), and scanning electron microscopy (SEM). In vitro biological activity was quantified applying L-929 cell line. Ovalbumin (OVA)-challenged balb/c mice were employed to evaluate the anti-TNFα activity of antibody formulation as in vivo experimental model. SD sample consisting of 36 mg trehalose, 12 mg cysteine, and 0.05% of Tween 20 was selected with minimum aggregation/fragmentation rate constants of 0.07 and 0.05 (1/month) based on 1 and 2 months of storage at 40°C and relative humidity of 75%. Fine particle fraction (FPF) value of this formulation was 67.75% with desired particle size and surface morphology for respiratory delivery. EC₅₀ was 8.176 and 6.733 ng/ml for SD Infliximab and Remicade®, respectively. SD antibody reduced TNFα (26.56 pg/ml) secretion in mouse lung tissue, more than 2 orders of magnitudes comparing positive control group (TNFα, 68.34 pg/ml). The success of antibody inhalation mainly depended on the spray drying condition, formulation components, and stability of antibody within aerosolization. Inhaled Infliximab could be a potential drug for local inhibition of lung inflammation.

MicroRNA-146a is induced by inflammatory stimuli in airway epithelial cells and augments the anti-inflammatory effects of glucocorticoids

Background

MicroRNAs (miRNAs) are emerging as central regulators of inflammation, but their role in asthma and airway epithelial cells is not well studied. Glucocorticoids are the cornerstone of therapy in asthma and other inflammatory disease, yet their mechanisms of action are not completely elucidated, and it is not clear whether miRNAs modulate their effects.

Objective

We aimed to identify miRNAs that regulate cytokine and chemokine expression in airway epithelial cells and whether these miRNAs are subject to the effects of glucocorticoids.

Methods and results

MicroRNAomic analyses of immortalized, normal human bronchial epithelial cells identified 7 miRNAs that were altered by inflammatory cytokine treatment and 22 that were regulated by glucocorticoids (n = 3 for each treatment condition). MiR-146a emerged as a central candidate, whose expression was induced by TNF-α and repressed by glucocorticoids. Its role as a candidate in asthmatic inflammation was supported by expression profiling in human asthmatics, which showed that plasma miR-146a expression was elevated in asthma and associated with measures related to worse asthma outcomes, including elevated blood eosinophil counts, higher asthma control questionnaire scores, and need for higher doses of inhaled glucocorticoids. However, transfection of miR-146a in A549 cells treated with TNF-α +/- glucocorticoids produced an anti-inflammatory effect and increased efficacy of glucocorticoids.

Conclusions

We propose a model whereby miR-146a is induced by inflammatory conditions as a feedback mechanism to limit inflammation. Exogenous administration of miR-146a augmented the effects of glucocorticoids and could be a novel therapeutic strategy to enhance efficacy of these medications.

Carica papaya ameliorates allergic asthma via down regulation of IL-4, IL-5, eotaxin, TNF-α, NF-ĸB, and iNOS levels

BACKGROUND

Natural products have a prime importance as an essential source for new drug discovery. Carica papaya leaves (CPL) have been used to treat inflammation in traditional system of medicine.

AIM/HYPOTHESIS

Current study evaluates the anti-inflammatory and immunomodulatory effects of CPL extract using mouse model of ovalbumin- (OVA) induced allergic asthma.

METHODS

All the mice were intraperitoneally sensitized and subsequently given intranasal challenge with OVA except the control group. Group-III and -IV were treated for seven consecutive days with CPL extract and methylprednisolone (MP), respectively. At the end of study, histopathological examination of the lungs was performed and inflammatory cell counts were done in blood as well as bronchoalveolar lavage fluid (BALF). The mRNA expression levels of IL-4, IL-5, eotaxin, TNF-α, NF-ĸB, and iNOS were measured using reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Results showed significant attenuation of lung infiltration of inflammatory cells, alveolar thickening, and goblet cell hyperplasia after treatment with CPL extract. We also found significant suppression of total and differential leukocyte counts in both blood and BALF samples of CPL extract treated group. CPL extract also alleviated the expression levels of IL-4, IL-5, eotaxin, TNF-α, NF-ĸB, and iNOS. Similarly, treatment with MP, used as a reference drug, also significantly ameliorated all the pro-inflammatory markers.

CONCLUSION

Current study shows that CPL extract possesses anti-inflammatory effect in mouse model of allergic airway inflammation by down-regulating IL-4, IL-5, eotaxin, TNF-α, NF-ĸB, and iNOS expression levels.

Pistacia integerrima ameliorates airway inflammation by attenuation of TNF-α, IL-4, and IL-5 expression levels, and pulmonary edema by elevation of AQP1 and AQP5 expression levels in mouse model of ovalbumin-induced allergic asthma

BACKGROUND

Natural products are considered as an essential source for the search of new drugs. Pistacia integerrima galls (PI) have been used for the treatment of asthma and cough in traditional system of medicine.

AIM/HYPOTHESIS

Current study investigates the immunomodulatory and anti-inflammatory activities of P. integerrima in mouse model of ovalbumin-induced allergic asthma.

METHODS

Mice were intraperitoneally sensitized and subsequently challenged intranasally with ovalbumin to induce allergic asthma. Experimental group mice were treated with methanol extract of P. integerrima extract (200mg/kg b. w.) and Methylprednisolone (MP) (15mg/kg b. w.) for 07 consecutive days, alongside intranasal challenge. Lung tissues were stained with Hematoxyline and Eosin (H & E), and Periodic Acid-Schiff (PAS) stains for histopathological evaluation. Lung wet/dry weight ratio was measured as an index of lung tissue edema. Albumin was injected in the right ear 24h before sacrificing the mice and difference of weight was taken as a degree of delayed type hypersensitivity (DTH). mRNA expression levels of TNF-α, IL-4, IL-5, Aquaporin-1 (AQP1), and AQP5 were evaluated using reverse transcription polymerase chain reaction (RT-PCR) followed by gel electrophoresis.

RESULTS

The data showed both PI extract and MP significantly alleviated DTH and nearly normalized total leukocyte count and differential leukocyte count in both blood and BALF. We found significantly suppressed goblet cell hyperplasia and inflammatory cell infiltration after treatment with both PI extract and MP. Expression levels of TNF-α, IL-4, and IL-5 were also found significantly reduced after treatment with both PI extract and MP, which might have resulted in the amelioration of airway inflammation. Current study displayed that both PI extract and MP significantly decreased lung wet/dry ratio, suggesting reduction in pulmonary edema. RT-PCR analysis showed significant increase in AQP1 and AQP5 expression levels after treatment with both PI extract and MP, which might have caused the alleviation of pulmonary edema.

CONCLUSION

Our study displays that P. integerrima possesses significant anti-asthmatic activity which may be attributed to reduction in TNF-α, IL-4, and IL-5 expression levels, and increase in AQP1 and AQP5 expression levels.

Real life study of three years omalizumab in patients with difficult-to-control asthma

BACKGROUND

Even though there are multiple options for the treatment of asthma, there still exists a fair group of patients with difficult-to-control asthma. We describe for the first time the real-world effects of three-year omalizumab treatment on patients with difficult-to-control asthma, seen in a social security hospital in a Latin American country.

METHODS

Difficult-to-control asthmatic patients from the out-patient clinic of a regional hospital were recruited to receive a three-year omalizumab course. Efficacy parameters were asthma control test (ACT) score; FEV1; daily beclomethasone maintenance dose; and unplanned visits for asthma exacerbations (emergency room (ER), hospitalisations, intensive care).

RESULTS

52 patients were recruited, 47 completed the three-year treatment (42 female, 15-67 years, mean age 43.5). Comparing efficacy parameters of the year before omalizumab with the 3rd year of omalizumab: mean ACT improved from 12.4 to 20.5, mean FEV1 from 66.3% (standard deviation (SD) 19.1%) to 88.4% (SD 16.2%) of predicted, while mean beclomethasone dose reduced from 1750 to 766 mcg/day and there was a significant reduction in patients experiencing ER visits (from 95% to 19%, p<0.0001), hospitalisation (38% to 2%, p<0.0001) and intensive care (4% to 0, NS). Five patients discontinued omalizumab, two because of an adverse event (anaphylaxis, severe headache, both resolved without sequelae).

CONCLUSION

Omalizumab improved most clinical parameters of Mexican patients with difficult-to-control asthma. Especially the rates of ER visits and hospitalisation were significantly reduced, thus reducing costs. Omalizumab was generally well tolerated.

Asthma is associated with cardiovascular disease in a representative population sample

SUMMARY

RATIONALE

People with asthma may have an increased risk of cardiovascular disease (CVD) and metabolic disorders due to the direct involvement of common inflammatory mediators in the pathogenesis of CVD and insulin resistance. The aim of this study was to determine whether asthma was associated with an increased prevalence of CVD/stroke, and diabetes in a cross-sectional population study and whether the relationship was modified by obesity.

METHODS

The North West Adelaide Health Study (NWAHS) (n = 4060, age ≥18 years) clinical assessment included spirometry, anthropometry, blood pressure, fasting lipids, glucose and HbA1c. Questionnaires assessed doctor diagnosed asthma, diabetes, CVD (myocardial infarction, angina)/stroke, smoking status, and demographics. Asthma was identified by self-report or significant bronchodilator reversibility of lung function.

RESULTS

After adjustment for known risk factors and confounders, asthma was not associated with diabetes (odds ratio (OR) = 1.06, 95% confidence interval (CI): 0.45-2.49, p = .91) yet remained positively associated with CVD/stroke (OR = 1.82, 95% CI: 1.20-2.73, p < 0.01) independent of the level of BMI (p for interaction between asthma and BMI = .22), smoking and lung function. Asthma was not positively associated with CVD risk factors or the metabolic syndrome.

CONCLUSIONS

In a representative population sample, asthma was associated with CVD/stroke after adjustment for traditional risk factors and lung function. Asthma may lead to CVD events via pathways unrelated to traditional risk factors and this requires further investigation. No significant effect modification by BMI was observed in relation to CVD, or diabetes.

Th-17 cell-related cytokines' potential role in the pathogenesis of severe asthma

Severe asthma represents a distinct, poorly-understood phenotype of asthma that has higher morbidity, mortality and a disproportionate need for health care support. Studies have indicated the presence of a specific inflammatory response in severe asthmatics, including the paucity of expression of classical Th-2 type cytokines. Following antigenic stimulation, naive CD4+ T cells proliferate and differentiate into various effector subsets such as Th-1 and Th-2 cells. A third subset of CD4+ T cells has recently been identified and designated as Th-17 cells, which produce IL-17A and F, IL-6, and TNF-alpha. In severe asthma, there may be a predominant Th-17 phenotype. These cells may promote the release of neutrophil chemotactic factors and induce the expression of GR-beta, which is responsible for corticosteroid hyporesponsiveness in immune and structural cells. If the role of Th-17 cytokines is confirmed, it might provide a new option in controlling this refractory subtype of asthma.

Role of long term antibiotics in chronic respiratory diseases

Antibiotics are commonly used in the management of respiratory disorders such as cystic fibrosis (CF), non-CF bronchiectasis, asthma and COPD. In those conditions long-term antibiotics can be delivered as nebulised aerosols or administered orally. In CF, nebulised colomycin or tobramycin improve lung function, reduce number of exacerbations and improve quality of life (QoL). Oral antibiotics, such as macrolides, have acquired wide use not only as anti-microbial agents but also due to their anti-inflammatory and pro-kinetic properties. In CF, macrolides such as azithromycin have been shown to improve the lung function and reduce frequency of infective exacerbations. Similarly macrolides have been shown to have some benefits in COPD including reduction in a number of exacerbations. In asthma, macrolides have been reported to improve some subjective parameters, bronchial hyperresponsiveness and airway inflammation; however have no benefits on lung function or overall asthma control. Macrolides have also been used with beneficial effects in less common disorders such as diffuse panbronchiolitis or post-transplant bronchiolitis obliterans syndrome. In this review we describe our current knowledge the use of long-term antibiotics in conditions such as CF, non-CF bronchiectasis, asthma and COPD together with up-to-date clinical and scientific evidence to support our understanding of the use of antibiotics in those conditions.

Asthma in children and adolescents: a comprehensive approach to diagnosis and management

Asthma is a chronic disease that has a significant impact on quality of life and is particularly important in children and adolescents, in part due to the higher incidence of allergies in children. The incidence of asthma has increased dramatically during this time period, with the highest increases in the urban areas of developed countries. It seems that the incidence in developing countries may follow this trend as well. While our knowledge of the pathophysiology of asthma and the available of newer, safer medication have both improved, the mortality of the disease has undergone an overall increase in the past 30 years. Asthma treatment goals in children include decreasing mortality and improving quality of life. Specific treatment goals include but are not limited to decreasing inflammation, improving lung function, decreasing clinical symptoms, reducing hospital stays and emergency department visits, reducing work or school absences, and reducing the need for rescue medications. Non-pharmacological management strategies include allergen avoidance, environmental evaluation for allergens and irritants, patient education, allergy testing, regular monitoring of lung function, and the use of asthma management plans, asthma control tests, peak flow meters, and asthma diaries. Achieving asthma treatment goals reduces direct and indirect costs of asthma and is economically cost-effective. Treatment in children presents unique challenges in diagnosis and management. Challenges in diagnosis include consideration of other diseases such as viral respiratory illnesses or vocal cord dysfunction. Challenges in management include evaluation of the child’s ability to use inhalers and peak flow meters and the management of exercise-induced asthma.

The possible role of trauma in skin tags through the release of mast cell mediators

Background:

Skin tags (ST) are common benign tumors of the skin but their etiopathogenesis is not well understood. STs arise in sites subjected to trauma. It was proved that mast cells are recruited to sites of skin trauma and increase their tumor necrosis factor-α (TNF-α) content.

Aim:

STs are linked to obesity and frictional sites, but this has not been studied at the molecular level. We hypothesized that mast cells, TNF-α and its family member, TNF-related apoptosis-inducing ligand (TRAIL) might play a role in the pathogenesis of STs as a response to trauma.

Materials and Methods:

A study was done on 15 patients with STs. Two STs and a snip of normal skin were obtained in each subject. We counted the mast cells after Toluidine blue staining. Enzyme-linked immunosorbant assay was used to measure TNF-α level while reverse transcriptase polymerase chain reaction was used to evaluate the level of TRAIL mRNA expression.

Results:

Mast cell count in all STs was significantly higher than that in control (P=0.0355). There was a highly significant increase in the level of TNF-α in all STs as compared to its level in controls (P<0.0001). Expression of TRAIL mRNA was significantly higher in STs as compared to its expression in controls (P<0.0001).

Conclusion:

Our study suggests that mast cells, TNF-α and TRAIL may play a role in the pathogenesis of STs.

Involvement of histamine receptors in SAPK/JNK phosphorylation

Histamine is a mediator of inflammation in allergic disease and asthma. Stress activated protein kinases/c-jun N-terminal kinases (SAPK/JNK) are involved in asthma. This study examined the role of histamine receptors on the phosphorylation of SAPK/JNK in splenocytes. C57BL/6 mice splenocytes were treated with histamine (10⁻⁴ M to 10⁻¹¹ M), and its selective receptor agonists, phorbol 12 myristate 13-acetate (PMA) was used as a positive control, and phosphorylation of SAPK/JNK was determined. Histamine (10⁻⁴ M-10⁻⁸ M) inhibited phosphorylation of SAPK/JNK. H1R agonist betahistine (10⁻⁵ M) decreased SAPK/JNK phosphorylation and H2R agonist amthamine (10⁻⁵ M) did not show any significant effect. However, H3R agonist methimepip (10⁻⁶ M) and H4R agonist 4-methyl histamine (10⁻⁶ M), increased SAPK/JNK phosphorylation. We used TNFα knockout mice to determine if histamine regulated SAPK/JNK phosphorylation via TNFα. While the effects of histamine and H1 agonists were similar to that of wild type mice in inhibiting the phosphorylation of SAPK/JNK, the effects of H3 and H4 agonists differed in TNFα knockout mice splenocytes. Activation of H3 receptors decreased SAPK/JNK phosphorylation in TNFα knockout mice, as opposed to an increase in wild type mice, whereas H4 agonist did not show any significant effect on the phosphorylation of SAPK/JNK. This data showed that histamine acting through H4 receptors caused the phosphorylation of SAPK/JNK via TNFα. The role of H4 receptors in pro-inflammatory response is intriguing.

Asthma in swimmers: a review of the current literature

Asthma is common in many types of athletes, but its prevalence appears to be particularly high in swimmers. Long-term and acute exposure to swimming pool disinfectants has been shown to increase asthma risk in swimmers through inducing oxidative stress, which results in inflammation of the pulmonary epithelium and subsequent airway remodeling. Individuals with specific genotypes are more likely to develop asthma when exposed to inhaled irritants. Therefore, it is important for physicians to be knowledgeable about the risks associated with asthma in swimmers, as well as the diagnostic techniques and practices to reduce asthma symptoms.

Anti-inflammatory effects of the neurotransmitter agonist Honokiol in a mouse model of allergic asthma

Chronic airway inflammation is a hallmark of asthma, an immune-based disease with great societal impact. Honokiol (HNK), a phenolic neurotransmitter receptor (γ-aminobutyric acid type A) agonist purified from magnolia, has anti-inflammatory properties, including stabilization of inflammation in experimentally induced arthritis. The present study tested the prediction that HNK could inhibit the chronic inflammatory component of allergic asthma. C57BL/6 mice sensitized to and challenged with OVA had increased airway hyperresponsiveness to methacholine challenge and eosinophilia compared with naive controls. HNK-treated mice showed a reduction in airway hyperresponsiveness as well as a significant decrease in lung eosinophilia. Histopathology studies revealed a marked drop in lung inflammation, goblet cell hyperplasia, and collagen deposition with HNK treatment. Ag recall responses from HNK-treated mice showed decreased proinflammatory cytokines in response to OVA, including TNF-α-, IL-6-, Th1-, and Th17-type cytokines, despite an increase in Th2-type cytokines. Regulatory cytokines IL-10 and TGF-β were also increased. Assessment of lung homogenates revealed a similar pattern of cytokines, with a noted increase in the number of FoxP3(+) cells in the lung. HNK was able to alter B and T lymphocyte cytokine secretion in a γ-aminobutyric acid type A-dependent manner. These results indicate that symptoms and pathology of asthma can be alleviated even in the presence of increased Th2 cytokines and that neurotransmitter agonists such as HNK have promise as a novel class of anti-inflammatory agents in the treatment of chronic asthma.

The role of TNF-alpha in eosinophilic inflammation associated with RSV bronchiolitis

The purpose of our study was to investigate whether tumor necrosis factor (TNF)-alpha correlates with eosinophilic inflammation that occurs during a lower respiratory tract infection with the respiratory syncytial virus (RSV) in children. Sixty children with RSV bronchiolitis (RSV group) and 20 healthy children with no respiratory symptoms (Control group) were enrolled. We measured the nasal lavage fluid (NLF) Th2 cytokine (IL-5), proinflammatory cytokine (TNF-alpha, IL-8), eosinophil-active cytokine [granulocyte-macrophage colony stimulating factor (GM-CSF), IFN-gamma], and eosinophil-active chemokine (eotaxin, regulated on activation normal T cell excreted and secreted) levels for both groups. We also measured serum eosinophil-degranulation product (eosinophil-derived neurotoxin; EDN, eosinophil cationic protein; ECP) levels from RSV group. TNF-alpha, IL-8, GM-CSF, IFN-gamma, and eotaxin levels were significantly higher in the RSV group compared with the Control group. TNF-alpha correlated with GM-CSF (r = 0.87, p < 0.0001), IFN-gamma (r = 0.92, p < 0.0001), eotaxin (r = 0.64, p < 0.0001), and IL-8 (r = 0.84, p < 0.0001). TNF-alpha may have an important role in eosinophilic inflammation of airways in children with RSV bronchiolitis.

Physiology and pathophysiology of canonical transient receptor potential channels

The existence of a mammalian family of TRPC ion channels, direct homologues of TRP, the visual transduction channel of flies, was discovered during 1995-1996 as a consequence of research into the mechanism by which the stimulation of the receptor-Gq-phospholipase Cbeta signaling pathway leads to sustained increases in intracellular calcium. Mammalian TRPs, TRPCs, turned out to be nonselective, calcium-permeable cation channels, which cause both a collapse of the cell's membrane potential and entry of calcium. The family comprises 7 members and is widely expressed. Many cells and tissues express between 3 and 4 of the 7 TRPCs. Despite their recent discovery, a wealth of information has accumulated, showing that TRPCs have widespread roles in almost all cells studied, including cells from excitable and nonexcitable tissues, such as the nervous and cardiovascular systems, the kidney and the liver, and cells from endothelia, epithelia, and the bone marrow compartment. Disruption of TRPC function is at the root of some familial diseases. More often, TRPCs are contributing risk factors in complex diseases. The present article reviews what has been uncovered about physiological roles of mammalian TRPC channels since the time of their discovery. This analysis reveals TRPCs as major and unsuspected gates of Ca(2+) entry that contribute, depending on context, to activation of transcription factors, apoptosis, vascular contractility, platelet activation, and cardiac hypertrophy, as well as to normal and abnormal cell proliferation. TRPCs emerge as targets for a thus far nonexistent field of pharmacological intervention that may ameliorate complex diseases.

Cardiovascular disease risk associated with asthma and respiratory morbidity might be mediated by short-acting beta2-agonists

BACKGROUND

Studies examining the asthma-related risks of cardiovascular disease (CVD) events have generally used selected samples or did not control for the effects of beta(2)-agonist use, itself associated with CVD events.

OBJECTIVES

We assessed the relationship between incident CVD/stroke and asthma and the effect of atopy while controlling for beta(2)-agonist use in a representative adult population cohort free of CVD at baseline.

METHODS

The North West Adelaide Health Study (stage 1, n = 3812; stage 2, n = 3113) assessed spirometry, anthropometry, atopy, blood pressure, and lipid levels. Questionnaires assessed doctor-diagnosed asthma and CVD (myocardial infarction and angina)/stroke, smoking status, and demographics. Asthma was defined by self-report or FEV(1) reversibility. Current short- and long-acting beta(2)-agonist use was identified at follow-up.

RESULTS

Results are expressed as odds ratios (ORs) and 95% CIs. By using multivariable logistic regression, after adjustment for risk factors, in female subjects incident CVD/stroke events were associated with asthma (OR, 3.24; 95% CI, 1.55-6.78), with no effect modification by atopy (P for interaction = .61), and with as-required short-acting beta(2)-agonist use (OR, 2.66; 95% CI, 1.06-6.61). In male subjects events were associated with daily cough/sputum (OR, 1.92; 95% CI, 1.05-3.50) and FEV(1) of less than 80% of predicted value but an FEV(1)/forced vital capacity ratio of greater than 0.70 (OR, 2.15; 95% CI, 0.91-5.09; P = .08). Although few CVD/stroke events occurred in male subjects with asthma, a significant interaction with atopic status was found (P = .05).

CONCLUSIONS

Studies are required to elucidate how asthma exposes older women to excess macrovascular risk and prospectively determine the short-acting beta(2)-agonist-related risk in persons without existing CVD. CVD risk in relation to atopic status of asthma also requires further investigation.

Dysregulation of the stress response in asthmatic children

The stress system co-ordinates the adaptive responses of the organism to stressors of any kind. Inappropriate responsiveness may account for increased susceptibility to a variety of disorders, including asthma. Accumulated evidence from animal models suggests that exogenously applied stress enhances airway reactivity and increases allergen-induced airway inflammation. This is in agreement with the clinical observation that stressful life events increase the risk of a new asthma attack. Activation of the hypothalamic-pituitary-adrenal (HPA) axis by specific cytokines increases the release of cortisol, which in turn feeds back and suppresses the immune reaction. Data from animal models suggest that inability to increase glucocorticoid production in response to stress is associated with increased airway inflammation with mechanical dysfunction of the lungs. Recently, a growing body of evidence shows that asthmatic subjects who are not treated with inhaled corticosteroids (ICS) are likely to have an attenuated activity and/or responsiveness of their HPA axis. In line with this concept, most asthmatic children demonstrate improved HPA axis responsiveness on conventional doses of ICS, as their airway inflammation subsides. Few patients may experience further deterioration of adrenal function, a phenomenon which may be genetically determined.

Th17 and allergy

The identification of novel helper T (Th) cell subsets, i.e., IL-17-producing Th cells (Th17 cells) and regulatory T cells (Treg cells), provided new insight into our understanding of the molecular mechanisms involved in the development of infectious and autoimmune diseases as well as immune responses, and thus led to revision of the classic Th1/Th2 paradigm. Several current lines of evidence from gene-deficient mice indicate that IL-17 and Th17 cells, but not IFN-gamma and Th1 cells, are responsible for the development of autoimmune diseases such as murine arthritis and encephalomyelitis, which have classically been considered to be Th1-mediated disorders. Th17 cells may also contribute to the pathogenesis of classically recognized Th2-mediated allergic disorders. In this review, we summarize the current knowledge regarding IL-17 and Th17 cells and discuss their potential roles in the pathogenesis of allergic disorders.

Prenatal exposure to endotoxin in rats attenuates the allergic airways eosinophil infiltration in the adult offspring: role of inducible nitric oxide synthase activation

A correlation between stressful events experienced by the mother during pregnancy and progression of respiratory disease in descendants has been reported. Prenatal exposure to lipopolyssacharide (LPS) reduces allergic airway inflammation in mice offspring. In this study we investigated whether reduction of airways inflammation by maternal LPS exposure involves activation of inducible nitric oxide synthase (iNOS) at prenatal life. Since LPS also induces the release of TNF-alpha, and that this cytokine has been implicated in pathogenesis of asthma, we also evaluated whether TNF-alpha plays a role in the allergic airways inflammation by maternal LPS exposure. Pregnant rats were pretreated with the iNOS inhibitor aminoguanidine (50mg/rat per day; given from day 13 of gestation up to delivery) before exposure to LPS (7mug/kg, given at day 17 of gestation). At adult ages, female and male offspring were sensitized with ovalbumin (OVA), and 14 days later they were challenged with this allergen. OVA challenge in sensitized offspring increased markedly the eosinophil number in bronchoalveolar lavage (BAL) fluid at 48h compared with the non-sensitized group. However, the eosinophil number was largely reduced in offspring from maternal LPS exposure, irrespective of offspring gender. Maternal pretreatment with aminoguanidine fully reversed the eosinophil suppression by LPS. The maternal LPS exposure also reduced the eosinophil number in bone marrow and peripheral blood of offspring, but this was not affected by aminoguanidine. No differences in TNF-alpha levels in BAL fluid were found. In conclusion, our study shows that maternal LPS exposure markedly reduces allergic airways eosinophil recruitment in adult offspring by mechanisms possibly involving iNOS activation.

Mast cells in the promotion and limitation of chronic inflammation

Observations of increased numbers of mast cells at sites of chronic inflammation have been reported for over a hundred years. Light and electron microscopic evidence of mast cell activation at such sites, taken together with the known functions of the diverse mediators, cytokines, and growth factors that can be secreted by appropriately activated mast cells, have suggested a wide range of possible functions for mast cells in promoting (or suppressing) many features of chronic inflammation. Similarly, these and other lines of evidence have implicated mast cells in a variety of adaptive or pathological responses that are associated with persistent inflammation at the affected sites. Definitively characterizing the importance of mast cells in chronic inflammation in humans is difficult. However, mice that genetically lack mast cells, especially those which can undergo engraftment with wildtype or genetically altered mast cells, provide a means to investigate the importance of mast cells and specific mast cell functions or products in diverse models of chronic inflammation. Such work has confirmed that mast cells can significantly influence multiple features of chronic inflammatory responses, through diverse effects that can either promote or, perhaps more surprisingly, suppress aspects of these responses.

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.

Mast cell-derived TNF contributes to airway hyperreactivity, inflammation, and TH2 cytokine production in an asthma model in mice

BACKGROUND

Mast cells, IgE, and TNF, which have been implicated in human atopic asthma, contribute significantly to the allergic airway inflammation induced by ovalbumin (OVA) challenge in mice sensitized with OVA without alum. However, it is not clear to what extent mast cells represent a significant source of TNF in this mouse model.

OBJECTIVE

We investigated the importance of mast cell-derived TNF in a mast cell-dependent model of OVA-induced airway hyperreactivity (AHR) and allergic airway inflammation.

METHODS

Features of this model of airway inflammation were analyzed in C57BL/6J-wild-type mice, mast cell-deficient C57BL/6J-Kit(W-sh)(/W-sh) mice, and C57BL/6J Kit(W-sh/W-sh) mice that had been systemically engrafted with bone marrow-derived cultured mast cells from C57BL/6J-wild-type or C57BL/6J-TNF(-/-) mice.

RESULTS

Ovalbumin-induced AHR and airway inflammation were significantly reduced in mast cell-deficient Kit(W-sh/W-sh) mice versus wild-type mice. By contrast, Kit(W-sh/W-sh) mice that had been engrafted with wild-type but not with TNF(-/-) bone marrow-derived cultured mast cells exhibited responses very similar to those observed in wild-type mice. Mast cells and mast cell-derived TNF were not required for induction of OVA-specific memory T cells in the sensitization phase, but significantly enhanced lymphocyte recruitment and T(H)2 cytokine production in the challenge phase.

CONCLUSION

Mast cell-derived TNF contributes significantly to the pathogenesis of mast cell-dependent and IgE-dependent, OVA-induced allergic inflammation and AHR in mice, perhaps in part by enhancing lymphocyte recruitment and T(H)2 cytokine production.

CLINICAL IMPLICATIONS

Our findings in mice support the hypothesis that mast cell-derived TNF can promote allergic inflammation and AHR in asthma.

TNF can contribute to multiple features of ovalbumin-induced allergic inflammation of the airways in mice

BACKGROUND

TNF is thought to contribute to airway hyperreactivity (AHR) and airway inflammation in asthma. However, studies with TNF-deficient or TNF receptor-deficient mice have not produced a clear picture of the role of TNF in the AHR associated with allergic inflammation in the mouse.

OBJECTIVE

We used a genetic approach to investigate the contributions of TNF to antigen-induced AHR and airway inflammation in mice on the C57BL/6 background.

METHODS

We analyzed features of airway allergic inflammation, including antigen-induced AHR, in C57BL/6 wild-type and TNF(-/-) mice, using 2 different methods for sensitizing the mice to ovalbumin (OVA).

RESULTS

In mice sensitized to OVA administered with the adjuvant aluminum hydroxide (alum), which develop IgE-independent and mast cell-independent allergic inflammation and AHR, we found no significant differences in OVA-induced AHR in C57BL/6-TNF(-/-) versus wild-type mice. By contrast, in mice sensitized to OVA without alum, which develop allergic inflammation that is significantly mast cell-dependent, C57BL/6-TNF(-/-) mice exhibited significant reductions versus wild-type mice in OVA-induced AHR to methacholine; numbers of lymphocytes, neutrophils, and eosinophils in bronchoalveolar lavage fluid; levels of myeloperoxidase, eosinophil peroxidase, and the cytokines IL-4, IL-5, and IL-17 in lung tissue; and histologic evidence of pulmonary inflammation.

CONCLUSION

In pulmonary allergic inflammation induced in mice immunized with OVA without alum, TNF significantly contributes to several features of the response, including antigen-induced inflammation and AHR.

CLINICAL IMPLICATIONS

Our findings in mice support the hypothesis that TNF can promote the allergic inflammation and AHR associated with asthma.

Parental smoking modifies the relation between genetic variation in tumor necrosis factor-alpha (TNF) and childhood asthma

BACKGROUND

Polymorphisms in the proinflammatory cytokine genes tumor necrosis factor-alpha (TNF) and lymphotoxin-alpha (LTA, also called TNF-beta) have been associated with asthma and atopy in some studies. Parental smoking is a consistent risk factor for childhood asthma. Secondhand smoke and ozone both stimulate TNF production.

OBJECTIVES

Our goal was to investigate whether genetic variation in TNF and LTA is associated with asthma and atopy and whether the association is modified by parental smoking in a Mexican population with high ozone exposure.

METHODS

We genotyped six tagging single nucleotide polymorphisms (SNPs) in TNF and LTA, including functional variants, in 596 nuclear families consisting of asthmatics 4-17 years of age and their parents in Mexico City. Atopy was determined by skin prick tests.

RESULTS

The A allele of the TNF-308 SNP was associated with increased risk of asthma [relative risk (RR) = 1.54; 95% confidence interval (CI), 1.04-2.28], especially among children of non-smoking parents (RR = 2.06; 95% CI, 1.19-3.55; p for interaction = 0.09). Similarly, the A allele of the TNF-238 SNP was associated with increased asthma risk among children of nonsmoking parents (RR = 2.21; 95% CI, 1.14-4.30; p for interaction = 0.01). LTA SNPs were not associated with asthma. Haplotype analyses reflected the single SNP findings in magnitude and direction. TNF and LTA SNPs were not associated with the degree of atopy.

CONCLUSIONS

Our results suggest that genetic variation in TNF may contribute to childhood asthma and that associations may be modified by parental smoking.

Thymoquinone attenuates proinflammatory responses in lipopolysaccharide-activated mast cells by modulating NF-kappaB nuclear transactivation

Activated mast cells play an important role in the development and maintenance of chronic inflammation by releasing proinflammatory cytokines such as Tumor necrosis factor alpha (TNFalpha). TNFalpha is a key mediator of immune and inflammatory responses as it controls the expression of inflammatory genes network and its overproduction contributes significantly to the pathological complications observed in many inflammatory diseases. We have previously shown that thymoquinone (TQ), which has broad anti-inflammatory activities, attenuates allergic inflammation in mice. In the present study, we investigated the effect of TQ on LPS-induced TNFalpha production in the rat basophil cell line, RBL-2H3. Stimulation of RBL-2H3 cells with LPS markedly increased TNFalpha production. TQ treatment significantly inhibited LPS-induced TNFalpha mRNA expression and protein production. To understand the mechanism by which TQ inhibited TNFalpha production, we examined its effects on activation of NF-kappaB transcription factor, which has been shown to be involved in regulating TNFalpha responses. LPS activated the NF-kappaB pathway, resulting in accumulation of NF-kappaB p65 and p50 subunits in the nucleus and activation of TNFalpha promoter. TQ administration to LPS-stimulated cells did not noticeably alter NF-kappaB cytosolic activation or nuclear expression as demonstrated by western blot analysis. Instead, TQ significantly increased the amount of the repressive NF-kappaB p50 homodimer, and simultaneously decreased the amount of transactivating NF-kappaB p65:p50 heterodimer, bound to the TNFalpha promoter as revealed by electrophoretic mobility shift and chromatin immunoprecipitation assays. Transient transfection of RBL-2H3 cells with TNFalpha promoter-driven luciferase gene constructs demonstrated that one of the three NF-kappaB binding sites in the TNFalpha promoter, the kappaB3 site, played a major role in the induction of TNFalpha promoter-driven luciferase gene expression by LPS, as well as in mediating the inhibitory effects of TQ on TNFalpha production, as TQ had minimal effect on the TNFalpha promoter-luciferase construct that lacks the kappaB3 site. Together, these results suggest that TQ attenuates the proinflammatory response in LPS-stimulated mast cells by modulating nuclear transactivation of NF-kappaB and TNFalpha production.

Raf-1 kinase mediates adenylyl cyclase sensitization by TNF-alpha in human airway smooth muscle cells

Tumor necrosis factor (TNF)-alpha is a potent inflammatory cytokine implicated in the exacerbation of asthma. Chronic exposure to TNF-alpha has been reported to induce G protein-coupled receptor desensitization, but adenylyl cyclase sensitization, in airway smooth muscle cells by an unknown mechanism. Cyclic AMP, which is synthesized by adenylyl cyclases in response to G protein-coupled receptor signals, is an important second messenger involved in the regulation of the airway muscle proliferation, migration, and tone. In other cell types, TNF-alpha receptors transactivate the EGF receptor, which activates raf-1 kinase. Further studies in transfected cells show that raf-1 kinase can phosphorylate and activate some isoforms of adenylyl cyclase. Cultured human airway smooth muscle cells were treated with TNF-alpha in the presence or absence of inhibitors of prostaglandin signaling, protein kinases, or G(i) proteins. TNF-alpha caused a significant dose- (1-10 ng/ml) and time-dependent (24 and 48 h) increase in forskolin-stimulated adenylyl cyclase activity, which was abrogated by pretreatment with GW5074 (a raf-1 kinase inhibitor), was partially inhibited by an EGF receptor inhibitor, but was unaffected by pertussis toxin. TNF-alpha also increased phosphorylation of Ser(338) on raf-1 kinase, indicative of activation. IL-1beta and EGF sensitization of adenylyl cyclase activity was also sensitive to raf-1 kinase inhibition by GW5074. Taken together, these studies link two signaling pathways not previously characterized in human airway smooth muscle cells: TNF-alpha transactivation of the EGF receptor, with subsequent raf-1 kinase-mediated activation of adenylyl cyclase.

Role of cytokines in allergic airway inflammation

Asthma is characterized by intense infiltration of eosinophils and CD4+ T cells into the submucosal tissue of airways. Accumulating evidence indicates that T helper type 2 cell-derived cytokines such as interleukin (IL)-4, IL-5 and IL-13 play critical roles in orchestrating and amplifying allergic inflammation in asthma. In addition, it has been suggested that newly identified cytokines including thymic stromal lymphopoietin, IL-25 and IL-33 are involved in the induction of allergic inflammation in asthma. In this review, we discuss the role of individual cytokines in the pathogenesis of asthma.

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.

Novel and emerging therapies for asthma

At present, there are a wide variety of novel and emerging therapeutic approaches for the treatment of asthma. Here, we will summarize these state-of-the-art approaches, including specific and nonspecific mediator inhibition-- a quest that has been on going for more than 25 years-- together with cytokine modulation in asthma (primarily attempting to modulate the Th2-Th1 balance in asthma), targeting cell recruitment, angiogenesis, signal transduction and gene transduction pathways. Finally, we will discuss the recently approved anti-IgE therapy for the treatment of allergic asthma and immune modulation using CpG oligodeoxynucleotides.

The effects of a monoclonal antibody directed against tumor necrosis factor-alpha in asthma

RATIONALE

Neutralization of tumor necrosis factor-alpha (TNF-alpha) is an effective antiinflammatory therapy for several chronic inflammatory diseases.

METHODS AND OBJECTIVES

We undertook a double-blind, placebo-controlled, parallel-group design study in 38 patients with moderate asthma treated with inhaled corticosteroids but symptomatic during a run-in phase. Infliximab (5 mg/kg) or placebo was administered by intravenous infusion at Weeks 0, 2, and 6. We assessed clinical response by monitoring lung function, symptoms, and inhaled beta(2)-agonist usage using hand-held electronic devices.

RESULTS

The primary endpoint, change in morning PEF at Days 50-56 compared with the last 7 d of the run-in, was not significantly different on treatment. However, infliximab was associated with a decrease in mean diurnal variation of PEF at Week 8 (p = 0.02; 95% confidence interval [CI], -8.1 to -0.72). Furthermore, there was a decrease in the number of patients with exacerbations of asthma (p = 0.01; 95% CI, 4.4 to 52.7) and an increased probability of freedom from exacerbation with time (p = 0.03) in patients on infliximab (n = 14) compared with placebo (n = 18). In addition, infliximab decreased levels of TNF-alpha (p = 0.01) and other cytokines in sputum supernatants. There were no serious adverse events related to the study agent.

CONCLUSIONS

Treatment with infliximab was well tolerated and caused a decrease in the number of patients with exacerbations in symptomatic moderate asthma. The promising preliminary findings underscore the need to evaluate therapy directed against TNF-alpha in larger trials enrolling patients with more severe asthma.

Mast cell-associated TNF promotes dendritic cell migration

Mast cells represent a potential source of TNF, a mediator which can enhance dendritic cell (DC) migration. Although the importance of mast cell-associated TNF in regulating DC migration in vivo is not clear, mast cells and mast cell-derived TNF can contribute to the expression of certain models of contact hypersensitivity (CHS). We found that CHS to FITC was significantly impaired in mast cell-deficient Kit(W-sh/W-sh) or TNF(-/)(-) mice. The reduced expression of CHS in Kit(W-sh/W-sh) mice was fully repaired by local transfer of wild-type bone marrow-derived cultured mast cells (BMCMCs), but was only partially repaired by transfer of TNF(-/)(-) BMCMCs. Thus, mast cells, and mast cell-derived TNF, were required for optimal expression of CHS to FITC. We found that the migration of FITC-bearing skin DCs into draining lymph nodes (LNs) 24 h after epicutaneous administration of FITC in naive mice was significantly reduced in mast cell-deficient or TNF(-/)(-) mice, but levels of DC migration in these mutant mice increased to greater than wild-type levels by 48 h after FITC sensitization. Mast cell-deficient or TNF(-/)(-) mice also exhibited significantly reduced migration of airway DCs to local LNs at 24 h after intranasal challenge with FITC-OVA. Migration of FITC-bearing DCs to LNs draining the skin or airways 24 h after sensitization was repaired in Kit(W-sh/W-sh) mice which had been engrafted with wild-type but not TNF(-/)(-) BMCMCs. Our findings indicate that mast cell-associated TNF can contribute significantly to the initial stages of FITC-induced migration of cutaneous or airway DCs.

Associations of tumor necrosis factor G-308A with childhood asthma and wheezing

RATIONALE

Tumor necrosis factor (TNF) mediates a spectrum of airway inflammatory responses, including those to air pollutants, and is an asthma candidate gene. One TNF promoter variant (G-308A) affects expression of TNF and has been associated with inflammatory diseases; however, studies of asthma have been inconsistent. Because ozone produces oxidative stress, increased airway TNF, and inflammation, the associations of the -308 TNF polymorphism with asthma may vary by ozone exposure and variants of oxidant defense genes glutathione-S-transferase (GST) M1 and GSTP1.

OBJECTIVES

To investigate the association of TNF G-308A with asthma and wheezing and to determine whether these associations vary with ozone exposure and GSTM1 and GSTP1 genotype.

METHODS

We studied associations of TNF-308 genotype with lifetime and current wheezing and asthma among 3,699 children in the Children's Health Study. We examined differences in associations with community ozone and by GSTM1 null and GSTP1 105 Ile/Val (A105G) genotype.

RESULTS

Children with TNF-308 GG had decreased risk of asthma (odds ratio, 0.8; 95% confidence interval, 0.7-0.9) and lifetime wheezing (odds ratio, 0.8; 95% confidence interval, 0.7-0.9). The protective effects of GG genotype on wheezing outcomes were of greater magnitude in lower compared with higher ozone communities. These findings were replicated in the two cohorts of fourth-grade children recruited in 1993 and 1996. The reduction of the protective effect from the -308 GG genotype with higher ozone exposure was most marked in the GSTM1 null and GSTP1 Ile/Ile groups.

CONCLUSIONS

The TNF-308 GG genotype may have a protective role in asthma pathogenesis, depending on airway oxidative stress levels.