Relationship between changes in interferon-gamma production by peripheral blood T cells and changes in peak expiratory flow rate in patients with chronic stable asthma

Temporal regulation of the human immune system

Under the model of spatial or tissue-specific immune compartmentalization, the site of immunogen exposure (oral, mucosal and dermal) shapes the consequent immune response. Thus, spatial compartmentalization provides a mechanism whereby different immune responses may evolve in different tissue compartments. Many immune cytokines are subject to circadian variation, for example, interleukin-1, -6, -10 and -12, macrophage migration inhibitory factor, tumor necrosis factor-alpha and interferon-gamma. These cytokine rhythms reflect the influence of regulatory hormones including cortisol and melatonin that exhibit circadian rhythmicity. This raises the question of what role, if any, circadian rhythms play in immune function. The hypothesis put forward is that circadian cytokine rhythms indicate the existence of temporal immune compartments. Temporal immune compartments include a daytime compartment characterized by high plasma cortisol and a regulatory cytokine environment, and a nocturnal compartment characterized by low cortisol, high melatonin and heightened inflammatory cytokine levels. Thus, time itself is a critical factor when measuring or interpreting immune response. This highlights the potential of immune chronotherapy where time-dependency principles guide the design of more effective and better tolerated immunotherapies and vaccines.

A functional polymorphism in IL-18 is associated with severity of bronchial asthma

RATIONALE

IL-18 is a unique cytokine that enhances innate immunity and both Th1- and Th2-driven immune responses. Recent murine and human genetic studies have shown its role in the pathogenesis of asthma.

OBJECTIVES

We conducted an association study in a Japanese population to discover variants of IL-18 that might have an effect on asthma susceptibility and/or progression and conducted functional analyses of the related variants.

METHODS

The IL-18 gene locus was resequenced in 48 human chromosomes. Asthma severity was determined according to the 2002 Global Initiative for Asthma Guidelines. Association and haplotype analyses were performed using 1,172 subjects.

MEASUREMENTS AND MAIN RESULTS

Although no polymorphisms differed significantly in frequency between the control and adult asthma groups, rs5744247 C>G was significantly associated with the severity of adult asthma (steps 1, 2 vs. steps 3, 4; P = 0.0034). We also found a positive association with a haplotype (P = 0.0026). By in vitro functional analyses, the rs5744247 variant was found to increase enhancer-reporter activity of the IL-18 gene in bronchial epithelial cells. Expression levels of IL-18 in response to LPS stimulation in monocytes were significantly greater in subjects homozygous for the susceptibility G allele at rs5744247 C>G. Furthermore, we found a significant correlation between the serum IL-18 level and the genotype of rs5744247 (P = 0.031).

CONCLUSIONS

Although the association results need to be replicated by other studies, IL-18 variants are significantly associated with asthma severity, and the rs5744247 variant reflects higher transcriptional activity and higher expression of IL-18 in LPS-stimulated monocytes and a higher serum IL-18 level.

Exhaled markers in the monitoring of airways inflammation and its response to steroid's treatment in mild persistent asthma

The measure of inflammatory cytokines in the exhaled breath condensate has been recently proposed for use in monitoring asthma and the therapeutic response to steroids. The aim of the present study was to investigate the usefulness of measuring exhaled IL-6, IL-4 and pH in mild persistent asthma. Furthermore the effects on these markers of inhaled steroids were assessed. The study enrolled 28 asthmatic (15 males, 38+/-12 years) and 15 healthy subjects (5 males, 35+/-6 years). IL-6, IL-4 and pH were measured in the exhaled breath condensate of the subjects studied. Significantly higher concentrations of IL-6 and IL-4 were observed in the breath condensate of asthmatic patients (7.1+/-1.1 and 64.4+/-8.3 pg/ml) compared to controls (2.7+/-0.6 and 31.7+/-3.5 pg/ml), p<0.001. Furthermore, exhaled IL-4 fell significantly after treatment with inhaled steroids for 6 months (47.9+/-3.2 pg/ml, p<0.001) while exhaled IL-6 did not (6.4+/-1.0 pg/ml, p=0.8). The exhaled pH turned out to be lower in asthmatic subjects than in controls (7.39+/-0.11 vs. 7.85+/-0.14; P<0.001) but trended towards control levels after steroid treatment (7.65+/-0.16, P<0.001). We conclude that the measurement of exhaled IL-4 and pH in mild asthmatic subjects could be a useful way of monitoring their airway inflammation as well as their response to the treatment.

Different IL-5 and IFN-gamma production from peripheral blood T-cell subsets in atopic and nonatopic asthmatic children

Defective Th1 and enhanced Th2-type cytokine responses have been implicated in the development of atopic disease. However, the immunopathology of nonatopic asthma, especially in children, remains unclear, and there have been few studies to compare the cytokine profile in peripheral blood T-cell subsets between atopic and nonatopic asthmatic children. To document whether atopic asthmatic children have a cytokine imbalance and to compare the cytokine profile between atopic and nonatopic asthmatic children, we investigated the interleukin (IL)-5-producing and interferon (IFN)-gamma-producing T-cell subsets from peripheral blood mononuclear cells (PBMC). The percentages of IFN-gamma-producing CD4+ and CD8+ T cells from atopic asthmatic children were decreased, but those in nonatopic asthmatic children were not decreased. In both groups of asthmatic children, the percentages of IFN-gamma-producing CD4+ T cells were inversely correlated with the peripheral blood eosinophils and had a significant correlation with airway responsiveness (PC20). Thus, we found that the mechanism underlying allergic inflammation of nonatopic asthma is not simple a Th1/Th2 cytokine imbalance. Considering the inverse relationship between IFN-gamma-producing CD4+ T cells and eosinophilia or airway hyperresponsiveness, IFN-gamma from CD4+ T cells may play an important role in allergic inflammation and airway hyperresponsiveness in asthmatic children.

Effects of cytokine milieu secreted by BCG-treated dendritic cells on allergen-specific Th immune response

Bacillus Calmette-Guerin (BCG) is reported to suppress Th2 response and asthmatic reaction. Dendritic cells (DCs), the major antigen-presenting cells, infections with BCG are known to result in inducing various cytokines. Thus, DCs are likely to play a role in the effects of BCG on asthma. This study aims at investigating that cytokine milieu secreted by BCG-treated DCs directly enhances allergen-specific Th1 response and/or suppresses Th2 response in allergic asthma. DCs and CD3+ T cells were generated from Dermatophagoides farinae-sensitive asthmatics. DCs were cultured with and without BCG and subjected to flow cytometric analysis. IL-12 and IL-10 were determined from the culture supernatants. Some DCs were cocultured with T cells in the presence of D. farinae extracts after adding the culture supernatants from BCG-treated DCs, and IL-5 and IFN-gamma were determined. BCG-treated DCs enhanced significantly the expressions of CD80, CD86, and CD40, and the productions of IL-12 and IL-10. Addition of culture supernatants from BCG-treated DCs up-regulated production of IFN-gamma by T cells stimulated by DCs and D. farinae extracts (p<0.05), but did not down-regulate production of IL-5 (p>0.05). The cytokine milieu secreted by BCG-treated DCs directly enhanced allergen-specific Th1 response, although did not suppress Th2 response.

Effects of anticytokine therapy in a mouse model of chronic asthma

The relative contribution of Th2 and Th1 cytokines to the pathogenesis of lesions of chronic asthma remains poorly understood. To date, therapeutic inhibition of Th2 cytokines has proved disappointing. We used a clinically relevant model of chronic allergic asthma in mice to compare the effects of administering neutralizing antibodies to interleukin (IL)-13, IL-5, and interferon-gamma (IFN-gamma) to animals with established disease. As has been observed in clinical studies, anti-IL-5 inhibited both inflammation and remodeling but had no effect on airway responsiveness to methacholine. Anti-IL-13 effectively suppressed eosinophil recruitment and accumulation of chronic inflammatory cells in the airways. This treatment also partially suppressed changes of airway wall remodeling, including goblet cell hyperplasia/metaplasia and subepithelial fibrosis, but had limited ability to inhibit airway hyperreactivity (AHR). In contrast, treatment with anti-IFN-gamma markedly suppressed AHR. This antibody inhibited accumulation of chronic inflammatory cells but did not affect eosinophil recruitment or changes of remodeling. We conclude that inhibition of IL-5 is beneficial and that inhibition of IL-13 has considerable potential as a therapeutic strategy in chronic asthma, that IFN-gamma may play an important role in the pathogenesis of AHR, and that co-operative interaction between Th2 and Th1 cytokines contributes to the pathogenesis of the lesions of chronic asthma.

Reassessing the Th2 cytokine basis of asthma

T helper (Th) 2 cytokines, particularly interleukin 4 (IL-4), IL-5 and IL-13, might be important in the development of allergic asthma. Humanized monoclonal antibodies (hMAbs) against IL-5, and a recombinant soluble human IL-4 receptor have been developed as possible treatments for this disorder. However, these approaches have not yet proven to be successful in the treatment of persistent asthma, suggesting that neither IL-4 nor IL-5 is important in asthma pathogenesis. Indeed, there is insufficient information about the efficacy of soluble IL-4 receptor and the anti-IL-5 hMAbs in the treatment of asthma to draw firm conclusions about the importance of these Th2 cytokines. Nevertheless, because IL-4 is required for IgE production and IL-5 is required for eosinophilopoesis, these Th2 cytokines must remain important candidates for a role in the pathogenesis of allergic asthma.