Immunomodulators in asthma therapy

Inhibition of Spleen Tyrosine Kinase Restores Glucocorticoid Sensitivity to Improve Steroid-Resistant Asthma

Background: Regulation or restoration of therapeutic sensitivity to glucocorticoids is important in patients with steroid-resistant asthma. Spleen tyrosine kinase (Syk) is activated at high levels in asthma patients and mouse models, and small-molecule Syk inhibitors such as R406 show potent anti-inflammatory effects in the treatment of immune inflammatory diseases. Several downstream signaling molecules of Syk are involved in the glucocorticoid response, so we hypothesized that R406 could restore sensitivity to dexamethasone in severe steroid-resistant asthma.

Objective: To discover the role of the Syk inhibitor R406 in glucocorticoid resistance in severe asthma.

Methods: Steroid-resistant asthma models were induced by exposure of C57BL/6 mice to house dust mite (HDM) and β-glucan and by TNF-α administration to the bronchial epithelial cell line BEAS-2B. We evaluated the role of the Syk inhibitor R406 in dexamethasone (Dex)-insensitive airway inflammation. Pathological alterations and cytokines in the lung tissues and inflammatory cells in BALF were assessed. We examined the effects of Dex or R406 alone and in combination on the phosphorylation of MAPKs, glucocorticoid receptor (GR) and Syk, as well as the transactivation and transrepression induced by Dex in mouse lung tissues and BEAS-2B cells.

Results: Exposure to HDM and β-glucan induced steroid-resistant airway inflammation. The Syk inhibitor R406 plus Dex significantly reduced airway inflammation compared with Dex alone. Additionally, TNF-α-induced IL-8 production in BEAS-2B cells was not completely inhibited by Dex, while R406 markedly promoted the anti-inflammatory effect of Dex. Compared with Dex alone, R406 enhanced Dex-mediated inhibition of the phosphorylation of MAPKs and GR-Ser226 induced by allergens or TNF-α in vivo and in vitro. Moreover, R406 also restored the impaired expression and nuclear translocation of GRα induced by TNF-α. Then, the activation of NF-κB and decreased HDAC2 activity in the asthmatic model were further regulated by R406, as well as the expression of GILZ.

Conclusions: The Syk inhibitor R406 improves sensitivity to dexamethasone by modulating GR. This study provides a reference for the development of drugs to treat severe steroid-resistant asthma.

Serum levels of vitamin A and 25-hydroxyvitamin D3 (25OHD3) as reflectors of pulmonary function and quality of life (QOL) in children with stable asthma: A case-control study

BACKGROUND

This study aims to explore the relationship between serum vitamin A and 25-hydroxyvitamin D3 (25OHD3) levels with pulmonary function and quality of life (QOL) in children with stable asthma.

METHODS

A total of 117 cases of children with stable asthma were assigned into the case group and 129 healthy children underwent physical examination during the same period into the control group. Electrochemiluminescence was employed to determine serum vitamin A and 25OHD3 levels. The children with stable asthma were further divided into the mild, moderate, and severe groups according to their degree of asthma. A pulmonary function meter was used to assess the pulmonary function indexes: percentage of forced expiratory volume in 1 sec/predictive value (FEV1%pred), forced vital capacity (FVC), forced expiratory volume in 1 sec/forced vital capacity (FEV1/FVC), peak expiratory flow (PEF), and maximal voluntary ventilation (MVV). The children's quality (QOL) of life with asthma was evaluated by their activities of daily living (ADLs) and Medical Research Council (MRC) scores. Pearson correlation analysis was applied to analyze the correlations of serum vitamin A and 25OHD3 levels with FEV1%pred, FVC, FEV1/FVC, PEF, MVV, ADL, and MRC.

RESULTS

Serum vitamin A and 25OHD3 levels were lower in children with stable asthma than those who were in the control group (P < .05). The severe group showed the lowest FEV1%pred, FVC, FEV1/FVC, PEF, MVV, and ADL scores, and the highest MRC score compared to the mild and moderate groups (all P < .05). Serum vitamin A and 25OHD3 levels were positively correlated with pulmonary function and ADL score in children with stable asthma, while serum vitamin A and 25OHD3 levels were negatively correlated with MRC score (all P < .05). In the case group, serum vitamin A and 25OHD3 levels were positively correlated with serum calcium and phosphorus levels (all P < .05).

CONCLUSION

These findings indicate that increased serum vitamin A and 25OHD3 levels reflect good pulmonary function and good QOL in children with stable asthma.

Natural antibody repertoires: development and functional role in inhibiting allergic airway disease

In this review we discuss the effects of microbial exposure on the B cell repertoire. Neonatal exposure to conserved bacterial carbohydrates and phospholipids permanently reprograms the natural antibody repertoire directed toward these antigens by clonal expansion, alterations in clonal dominance, and increased serum antibody levels. These epitopes are present not only in bacterial cell walls, but also in common environmental allergens. Neonatal immunization with bacterial polysaccharide vaccines results in attenuated allergic airway responses to fungi-, house dust mite-, and cockroach-associated allergens in mouse models. The similarities between mouse and human natural antibody repertoires suggest that reduced microbial exposure in children may have the opposite effect, providing a potential mechanistic explanation for the hygiene hypothesis. We propose that understanding the effects of childhood infections on the natural antibody repertoire and the mechanisms of antibody-mediated immunoregulation observed in allergy models will lead to the development of prevention/interventional strategies for treatment of allergic asthma.

Differential expression of innate immunity genes in chronic rhinosinusitis

BACKGROUND

Prior research has identified several components of the innate immune system that may play a significant role in chronic rhinosinusitis (CRS), but the role of innate immunity in patients with CRS is poorly understood. The objective of this study was to determine differential expression of innate immunity genes in the mucosa of patients with CRS with nasal polyposis (CRSwNP) and CRS without nasal polyposis (CRSsNP) when compared with controls.

METHODS

Control patients (n = 9) and patients with CRS (n = 36) who failed medical management were prospectively enrolled. Ethmoid mucosa samples were harvested during surgery and quantitative real-time polymerase chain reaction was used to determine levels of mRNA expression of Toll-like receptor (TLR) 2 and TLR9 and interleukin-22 receptor (IL-22R). The average change in crossover threshold and fold change were calculated and differences between controls, CRSwNP, and CRSsNP were compared. Statistical analysis was performed using the Kruskall-Wallis and adjusted Mann-Whitney U tests.

RESULTS

Patients with CRSwNP (n = 16) and CRSsNP (n = 20) showed lower mean expression of TLR2 (p < 0.05) compared with controls. Patients with CRSsNP showed significantly higher mean expression of IL-22R (p < 0.05) than controls.

CONCLUSION

The sinonasal innate immune system may have a significant role in the development of CRS. We found differential expression of innate immune mediators between patients with and without nasal polyposis. These results provide further evidence of disruption of innate immunity at the mucosal level in CRS and highlight differences between polyp- and non-polyp-forming CRS phenotypes at the molecular level. In addition to our knowledge, this is the first report of altered IL-22R expression in CRSsNP patients. This study was a part of the clinical trial NCT01332136 registered in www.clinicaltrials.gov.

Emerging targets for novel therapy of asthma

Significant advances in understanding the cell and molecular biology of inflammation and airway smooth muscle (ASM) contractility have identified several potential novel targets for therapies of asthma. New agents targeting G-protein coupled receptors (GPCRs) including bitter taste receptors (TAS2R) agonists and prostaglandin EP4 receptor agonists elicit ASM relaxation. The cAMP/PKA pathway continues to be a promising drug target with the emergence of new PDE inhibitors and a novel PKA target protein, HSP20, which mediates smooth muscle relaxation via actin depolymerization. Smooth muscle relaxation can also be elicited by inhibitors of the RhoA/Rho kinase pathway via inhibition of myosin light chain phosphorylation and actin depolymerization. Targeting epigenetic processes that control chromatin remodeling and RNA-induced gene silencing in airway cells also holds great potential for novel asthma therapy. Further investigation may identify agents that inhibit smooth muscle contraction and/or restrain or reverse obstructive remodeling of the airways.

Bacterial expression and characterization of a novel human anti-IgE scFv fragment

Antibodies highly specific to human immunoglobulin (Ig) E are capable of selectively blocking the IgE interaction or eliminating IgE-producing cells, thus providing valuable agents for diagnostics and treatment of various allergic illness. An example is omalizumab, a humanized monoclonal anti-IgE antibody that is approved for the treatment of patients with moderate-to-severe allergic diseases in the United States, European Union and other countries. Here, we describe the generation and characterization of a novel human anti-IgE as a single-chain antibody fragment (scFv). The bacterially-synthesized scFv showed high affinity (86 nM) and specificity to the Fc region of human IgE. To our knowledge, this is the first report of the production of a human anti-IgE scFv in E. coli. Its further development as a potential candidate for medical applications is discussed.

Network analysis of single nucleotide polymorphisms in asthma

BACKGROUND

Asthma is a chronic inflammatory disease of the airways with a complex genetic background. In this study, we carried out a meta-analysis of single nucleotide polymorphisms (SNPs) thought to be associated with asthma.

METHODS

The literature (PubMed) was searched for SNPs within genes relevant in asthma. The SNP-modified genes were converted to corresponding proteins, and their protein-protein interactions were searched from six different databases. This interaction network was analyzed using annotated vocabularies (ontologies), such as the Gene Ontology and Nature pathway interaction databases.

RESULTS

In total, 127 genes with SNPs related to asthma were found in the literature. The corresponding proteins were then entered into a large protein-protein interaction network with the help of various databases. Ninety-six SNP-related proteins had more than one interacting protein each, and a network containing 309 proteins and 644 connections was generated. This network was significantly enriched with a gene ontology entitled "protein binding" and several of its daughter categories, including receptor binding and cytokine binding, when compared with the background human proteome. In the detailed analysis, the chemokine network, including eight proteins and 13 toll-like receptors, were shown to interact with each other. Of great interest are the nonsynonymous SNPs which code for an alternative amino acid sequence of proteins and, of the toll-like receptor network, TLR1, TLR4, TLR5, TLR6, TLR10, IL4R, and IL13 are among these.

CONCLUSIONS

Protein binding, toll-like receptors, and chemokines dominated in the asthma-related protein interaction network. Systems level analysis of allergy-related mutations can provide new insights into the pathogenetic mechanisms of disease.