Reduced interleukin-18 levels in BAL specimens from patients with asthma compared to patients with sarcoidosis and healthy control subjects

Caspase-1 and interleukin-18 in children with post infectious bronchiolitis obliterans: a case-control study

The exact immunological mechanisms of post infectious bronchiolitis obliterans (PIBO) in childhood are not fully known. It has been shown that the inflammasome and IL-18 pathway play important roles in the pathogenesis of lung fibrosis. We aimed to investigate the role of caspase-1, IL-18, and IL-18 components in PIBO. From January to May 2020, children with PIBO, children with history of influenza infection without PIBO, and healthy children were asked to participate in the study in three pediatric pulmonology centers. Serum caspase-1, IL-18, IL-18BP, IL-18R, and INF-γ levels were measured by ELISA and compared between the 3 groups. There were 21 children in the PIBO group, 16 children in the influenza group, and 39 children in the healthy control group. No differences in terms of age and gender between the 3 groups were found. IL-18 and IL-18BP levels were higher in the healthy control group (p = 0.018, p = 0.005, respectively). IL-18R was higher in the PIBO group (p = 0.001) and caspase-1 was higher in the PIBO and influenza group than the healthy control group (p = 0.002). IFN-γ levels did not differ between the 3 groups. IL-18BP/IL-18 was higher in the influenza group than the PIBO group and the healthy control group (p = 0.003).

CONCLUSIONS

Caspase-1 level was increased in patients with PIBO which suggests that inflammasome activation may have a role in fibrosis; however, IL-18 level was found to be low. Mediators other than IL-18 may be involved in the inflammatory pathway in PIBO. Further immunological studies investigating inflammasome pathway are needed for PIBO with chronic inflammation.

WHAT IS KNOWN

• Post infectious bronchiolitis obliterans (PIBO) is a rare, severe chronic lung disease during childhood which is associated with inflammation and fibrosis which lead to partial or complete luminal obstruction especially in small airways. • The exact immunological mechanisms of PIBO in childhood are not fully known.

WHAT IS NEW

• Inflammasome activation persists even years after acute infection and may play a role in fibrosis in PIBO. • Mediators other than IL-18 may be involved in these inflammatory pathway.

NLRP1 variant M1184V decreases inflammasome activation in the context of DPP9 inhibition and asthma severity

Background

NLRP1 is an innate immune sensor that can form cytoplasmic inflammasome complexes. Polymorphisms in NLRP1 are linked to asthma; however, there is currently no functional or mechanistic explanation for this.

Objective

We sought to clarify the role of NLRP1 in asthma pathogenesis.

Methods

Results from the GALA II cohort study were used to identify a link between NLRP1 and asthma in Mexican Americans. In vitro and in vivo models for NLRP1 activation were applied to investigate the role of this inflammasome in asthma at the molecular level.

Results

We document the association of an NLRP1 haplotype with asthma for which the single nucleotide polymorphism rs11651270 (M1184V) individually is the most significant. Surprisingly, M1184V increases NLRP1 activation in the context of N-terminal destabilization, but decreases NLRP1 activation on dipeptidyl peptidase 9 inhibition. In vitro studies demonstrate that M1184V increases binding to dipeptidyl peptidase 9, which can account for its inhibitory role in this context. In addition, in vivo data from a mouse model of airway inflammation reveal a protective role for NLRP1 inflammasome activation reducing eosinophilia in this setting.

Conclusions

Linking our in vitro and in vivo results, we found that the NLRP1 variant M1184V reduces inflammasome activation in the context of dipeptidyl peptidase 9 inhibition and could thereby increase asthma severity. Our studies may have implications for the treatment of asthma in patients carrying this variant of NLRP1.

Hyperoxia treatment of TREK-1/TREK-2/TRAAK-deficient mice is associated with a reduction in surfactant proteins

We previously proposed a role for the two-pore domain potassium (K2P) channel TREK-1 in hyperoxia (HO)-induced lung injury. To determine whether redundancy among the three TREK isoforms (TREK-1, TREK-2, and TRAAK) could protect from HO-induced injury, we now examined the effect of deletion of all three TREK isoforms in a clinically relevant scenario of prolonged HO exposure and mechanical ventilation (MV). We exposed WT and TREK-1/TREK-2/TRAAK-deficient [triple knockout (KO)] mice to either room air, 72-h HO, MV [high and low tidal volume (TV)], or a combination of HO + MV and measured quasistatic lung compliance, bronchoalveolar lavage (BAL) protein concentration, histologic lung injury scores (LIS), cellular apoptosis, and cytokine levels. We determined surfactant gene and protein expression and attempted to prevent HO-induced lung injury by prophylactically administering an exogenous surfactant (Curosurf). HO treatment increased lung injury in triple KO but not WT mice, including an elevated LIS, BAL protein concentration, and markers of apoptosis, decreased lung compliance, and a more proinflammatory cytokine phenotype. MV alone had no effect on lung injury markers. Exposure to HO + MV (low TV) further decreased lung compliance in triple KO but not WT mice, and HO + MV (high TV) was lethal for triple KO mice. In triple KO mice, the HO-induced lung injury was associated with decreased surfactant protein (SP) A and SPC but not SPB and SPD expression. However, these changes could not be explained by alterations in the transcription factors nuclear factor-1 (NF-1), NKX2.1/thyroid transcription factor-1 (TTF-1) or c-jun, or lamellar body levels. Prophylactic Curosurf administration did not improve lung injury scores or compliance in triple KO mice.

Addressing unmet needs in understanding asthma mechanisms: From the European Asthma Research and Innovation Partnership (EARIP) Work Package (WP)2 collaborators

Asthma is a heterogeneous, complex disease with clinical phenotypes that incorporate persistent symptoms and acute exacerbations. It affects many millions of Europeans throughout their education and working lives and puts a heavy cost on European productivity. There is a wide spectrum of disease severity and control. Therapeutic advances have been slow despite greater understanding of basic mechanisms and the lack of satisfactory preventative and disease modifying management for asthma constitutes a significant unmet clinical need. Preventing, treating and ultimately curing asthma requires co-ordinated research and innovation across Europe. The European Asthma Research and Innovation Partnership (EARIP) is an FP7-funded programme which has taken a co-ordinated and integrated approach to analysing the future of asthma research and development. This report aims to identify the mechanistic areas in which investment is required to bring about significant improvements in asthma outcomes.

Viruses exacerbating chronic pulmonary disease: the role of immune modulation

Chronic pulmonary diseases are a major cause of morbidity and mortality and their impact is expected to increase in the future. Respiratory viruses are the most common cause of acute respiratory infections and it is increasingly recognized that respiratory viruses are a major cause of acute exacerbations of chronic pulmonary diseases such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. There is now increasing evidence that the host response to virus infection is dysregulated in these diseases and a better understanding of the mechanisms of abnormal immune responses has the potential to lead to the development of new therapies for virus-induced exacerbations. The aim of this article is to review the current knowledge regarding the role of viruses and immune modulation in chronic pulmonary diseases and discuss avenues for future research and therapeutic implications.

Analysis of NLRP3 in the development of allergic airway disease in mice

The contribution of NLRP3, a member of the nucleotide-binding domain leucine-rich repeat-containing (NLR) family, to the development of allergic airway disease is currently controversial. In this study, we used multiple allergic asthma models to examine the physiologic role of NLRP3. We found no significant differences in airway eosinophilia, histopathologic condition, mucus production, and airway hyperresponsiveness between wild-type and Nlrp3(-/-) mice in either acute (alum-dependent) or chronic (alum-independent) OVA models. In addition to the OVA model, we did not detect a role for NLRP3 in the development of allergic airway disease induced by either acute or chronic house dust mite Ag exposure. Although we did not observe significant phenotypic differences in any of the models tested, we did note a significant reduction of IL-13 and IL-33 in Nlrp3(-/-) mice compared with wild-type controls in the chronic OVA model without added alum. In all of the allergic airway disease models, the NLRP3 inflammasome-associated cytokines IL-1β and IL-18 in the lung were below the level of detection. In sum, this report surveyed four different allergic asthma models and found a modest and selected role for NLRP3 in the alum-free OVA model. However, this difference did not greatly alter the clinical outcome of the disease. This finding suggests that the role of NLRP3 in allergic asthma must be re-evaluated.

The role of the NLRP3 inflammasome in the pathogenesis of airway disease

The incidences of respiratory diseases like asthma and Chronic Obstructive Pulmonary Disease (COPD) are increasing dramatically. Significantly, there are currently no treatments that can slow or prevent the relentless progression of COPD; and a sub-population of asthmatics are resistant to available therapies. What is more, currently prescribed medication has only minimal effect on the symptoms suffered in these patient groups. There is therefore an urgent need to develop effective drugs to treat these diseases. Whilst asthma and COPD are thought to be distinct diseases, it is currently believed that the pathogenesis of both is driven by the chronic inflammation present in the airways of these patients. It is thus hypothesised that if the inflammation could be attenuated, disease development would be slowed and symptoms reduced. It is therefore paramount to determine the pathways driving/propagating the inflammation. Recently there has been a growing body of evidence to suggest that the multimeric protein complex known as the Inflammasome may play key roles in the inflammation observed in respiratory diseases. The aim of this review is to discuss the role of the NLRP3 Inflammasome, and its associated inflammatory mediators (IL-1β and IL-18), in the pathogenesis of asthma and COPD.

Importance of cytokines in murine allergic airway disease and human asthma

Asthma is a common, disabling inflammatory respiratory disease that has increased in frequency and severity in developed nations. We review studies of murine allergic airway disease (MAAD) and human asthma that evaluate the importance of Th2 cytokines, Th2 response-promoting cytokines, IL-17, and proinflammatory and anti-inflammatory cytokines in MAAD and human asthma. We discuss murine studies that directly stimulate airways with specific cytokines or delete, inactivate, neutralize, or block specific cytokines or their receptors, as well as controversial issues including the roles of IL-5, IL-17, and IL-13Ralpha2 in MAAD and IL-4Ralpha expression by specific cell types. Studies of human asthmatic cytokine gene and protein expression, linkage of cytokine polymorphisms to asthma, cytokine responses to allergen stimulation, and clinical responses to cytokine antagonists are discussed as well. Results of these analyses establish the importance of specific cytokines in MAAD and human asthma and have therapeutic implications.

Serum interleukin-18 expression in children with bronchial asthma

BACKGROUND

: Interleukin 18 (IL-18) is reported to have regulatory functions on Th1 and Th2 cytokine production and proinflammatory effects through promoting recruitment of memory Th1 cells to inflammatory sites. We sought to investigate the expression of the serum IL-18 in childhood bronchial asthma in relation to disease activity and severity.

METHODS

: Serum IL-18 was measured by enzymatic immunoassay in 25 asthmatic children during exacerbation and after complete quiescence of symptoms and signs. The results were compared to those of 35 nonallergic age- and sex-matched children.

RESULTS

: Serum IL-18 levels during asthma exacerbation [median = 125 pg/mL; mean (SD) = 128.6 (43.3) pg/mL] were significantly lower than the follow-up levels during stability [median = 250 pg/mL; mean (SD) = 291.6 (66.7) pg/mL] and both levels correlated positively with each other. The corresponding values of the control group were higher than those of the asthmatic patients whether during exacerbation or stability [median = 380 pg/mL; mean (SD) = 476.1 (259.6) pg/mL]. The serum IL-18 concentrations did not vary significantly according to asthma severity, family history of atopy, or passive smoking. The influence of inhaled corticosteroids on IL-18 expression was not impressive and neither was the relation between serum IL-18 and the peripheral blood eosinophil count or serum total IgE expression.

CONCLUSIONS

: Serum IL-18 was found underexpressed in a group of asthmatic children especially during exacerbation. Further studies are needed to outline its exact role in the pathogenesis of asthma.

IL-18 levels in nasal lavage after inhalatory challenge test with flour in bakers diagnosed with occupational asthma

OBJECTIVES

The authors discuss the outcomes of a study on IL-18 concentration in nasal washings after the inhalatory challenge test with flour allergens (ICHT-F) in bakers with flour-induced occupational airway allergy (OAA).

METHODS

We measured IL-18 concentration using ELISA kit and assessed morphological changes in nasal lavage fluid (NLF) before, and 4 h and 24 h after ICHT-F in three groups of subjects: Group A - 9 patients with diagnosed OAA (occupational asthma and rhinitis), Group B - 10 patients with atopic asthma and rhinitis, and Group C - 9 healthy volunteers.

RESULTS

In Group A, significant differences in the basophil proportion in NLF were noted only 24 h after ICHT-F. Both the basophil proportion and total eosinophil count were higher in Group A than in Group C at this time-point. Group A also showed a statistically significant increase in IL-18 levels 4 h after the challenge. A significant relationship was noted between the proportion of basophils 4 h after ICHT-F and IL-18 level at 24 h after the test.

CONCLUSIONS

This is the first study demonstrating an increased expression of IL-18 in nasal washings of subjects diagnosed with OAA to flour allergens. The observed higher concentrations of IL-18 in nasal washings after ICHT as well as the increase in the proportion of basophils provide evidence for the important role of IL-18 in persistent allergic inflammation.

New drugs targeting Th2 lymphocytes in asthma

Asthma represents a profound worldwide public health problem. The most effective anti-asthmatic drugs currently available include inhaled beta2-agonists and glucocorticoids and control asthma in about 90-95% of patients. The current asthma therapies are not cures and symptoms return soon after treatment is stopped even after long term therapy. Although glucocorticoids are highly effective in controlling the inflammatory process in asthma, they appear to have little effect on the lower airway remodelling processes that appear to play a role in the pathophysiology of asthma at currently prescribed doses. The development of novel drugs may allow resolution of these changes. In addition, severe glucocorticoid-dependent and resistant asthma presents a great clinical burden and reducing the side-effects of glucocorticoids using novel steroid-sparing agents is needed. Furthermore, the mechanisms involved in the persistence of inflammation are poorly understood and the reasons why some patients have severe life threatening asthma and others have very mild disease are still unknown. Drug development for asthma has been directed at improving currently available drugs and findings new compounds that usually target the Th2-driven airway inflammatory response. Considering the apparently central role of T lymphocytes in the pathogenesis of asthma, drugs targeting disease-inducing Th2 cells are promising therapeutic strategies. However, although animal models of asthma suggest that this is feasible, the translation of these types of studies for the treatment of human asthma remains poor due to the limitations of the models currently used. The myriad of new compounds that are in development directed to modulate Th2 cells recruitment and/or activation will clarify in the near future the relative importance of these cells and their mediators in the complex interactions with the other pro-inflammatory/anti-inflammatory cells and mediators responsible of the different asthmatic phenotypes. Some of these new Th2-oriented strategies may in the future not only control symptoms and modify the natural course of asthma, but also potentially prevent or cure the disease.

Allergen-induced in vitro expression of IL-18, SLAM and GATA-3 mRNA in PBMC during sublingual immunotherapy

BACKGROUND

Signalling lymphocytic activation molecule (SLAM) and interleukin (IL)-18 induce interferon (IFN)-gamma production from Th1 cells. The allergen-induced SLAM and IL-18 mRNA expressions are increased during subcutaneous immunotherapy (SCIT), but nothing is known about their role during sublingual immunotherapy (SLIT). Transcription factor GATA-3 is associated with Th2 cells but its role in SCIT and SLIT is yet unexplored. This study was undertaken to analyse the allergen induced in vitro mRNA expression of IL-18, SLAM and GATA-3 in peripheral blood mononuclear cells (PBMC) of children with allergic rhinitis (AR) during SLIT.

METHODS

Ten patients with AR undergoing pollen SLIT with a weekly dose of 200,000 SQ-U, 10 with 24,000 SQ-U of mixture of Betula verrucosa, Corylus avellana and Alnus glutinosa and 10 with placebo were included. Peripheral blood mononuclear cell were stimulated with birch extract prior to, after 1 and 2 years of the treatment. The mRNA expression was assessed using kinetic real-time RT-PCR (TaqMan); Applied Biosystems, Foster City, CA, USA).

RESULTS

The expression of IL-18 mRNA was increased in the high-dose group in comparison to the placebo group after 1 year of therapy (P = 0.028) and had an inverse correlation with the late phase skin reaction after the second study year (r = -0.41, P = 0.041). SLAM mRNA expression increased in the high-dose group from baseline to 1 year (P = 0.028) and correlated with IL-10 (r = 0.96, P < 0.0001) and transforming growth factor-beta (r = 0.80, P = 0.0037) mRNA expression. No significant changes were seen in GATA-3 mRNA expression.

CONCLUSIONS

During SLIT, IL-18 and SLAM are upregulated, suggesting that the Th2 type inflammatory response is downregulated during SLIT by increased Th1 type response.

Effects of corticosteroids on expression of interleukin-18 in the airway mucosa of a mouse model of allergic rhinitis

OBJECTIVES

In this study, we aimed to investigate the release and response of interleukin (IL)-18 to steroid treatment in a mouse model of allergic rhinitis.

METHODS

BALB/c mice were sensitized systemically by intraperitoneal injection of ovalbumin and locally by ovalbumin inhalation. Dexamethasone sodium phosphate was given by intraperitoneal injection in the steroid treatment group. Symptom scores, eosinophil counts, and IL-18 concentrations in the nasal and lung lavage fluids were analyzed.

RESULTS

The symptom scores and eosinophil counts of the negative control and steroid treatment groups were significantly lower than those of the positive control group (p < .01). The mean IL-18 concentrations in the nasal lavage fluid were not significantly different among the three groups (56.68 +/- 9.57,63.39 +/- 8.93, and 64.47 +/- 6.83 pg/mL, respectively). The IL-18 concentrations in the lung lavage fluid were significantly different between the positive control group and the steroid treatment group (430.75 +/- 154.54 and 69.94 +/- 14.26 pg/mL, respectively, p = .028).

CONCLUSIONS

The IL-18 concentration was found to be increased in the lung lavage fluid, but not in the nasal lavage fluid, in a mouse model of allergic rhinitis. Increased IL-18 concentrations returned toward the previous concentrations after steroid treatment. These results suggest that the roles of IL-18 may be different in the pathogenesis of allergic rhinitis and the pathogenesis of asthma.

The clinical significance of interleukin 18 assessment in sarcoidosis patients

INTRODUCTION

Sarcoidosis is a multisystemic disease of unknown etiology characterized by the formation of immune granulomas in involved organs. The cytokine profile in inflamed lesions of sarcoidosis is mainly determined by T helper 1 (Th1) cells. Interleukin 18 (IL-18) is primarily a monocyte/macrophage-derived cytokine. IL-18 has been recently identified as an IFNgamma-inducing factor. The cytokine plays an important role in the induction of Th1 response and it may be responsible for sarcoidosis progression. The aim of the study was to assess the usefulness of IL-18 estimation in the sarcoidosis diagnosis and the disease course prognosis.

MATERIAL AND METHODS

The diagnosis of sarcoidosis was established in 88 patients (the mean age of 38.1+/-10.8 years). We measured IL-18 level in plasma and bronchoalveolar lavage fluid (BALF) cell culture supernatant (CCS) using the enzyme-linked immunoassay technique (ELISA). We also performed the flow cytometric analysis of BALF lymphocyte phenotype. Statistica 5.0 and non-parametric tests: the Mann-Whitney U-test and the Spearman correlation test, were used for statistical analysis.

RESULTS

The patient group consisted of 55 subjects without acute symptoms of sarcoidosis, 14 patients with acute Löfgren syndrome and 19 subjects with Löfgren syndrome in the past. Lung hilar lymphadenopathy was diagnosed in 49 patients and lung interstitial changes in 39 subjects. After 6-month-observation, 49 patients were in remission, 20 subjects manifested persistent disease and 19 patients had sarcoidosis progression. Plasma IL-18 level was significantly (P<0.0001) higher in sarcoidosis patients (383+/-250pg/ml) than in control subjects (146+/-72pg/ml). Plasma IL-18 level was similar both in subjects with Löfgren syndrome and in other patients. However, IL-18 level in BALF CCS was significantly (P<0.05) lower in Löfgren syndrome patients than in subjects without acute manifestation of the disease. The highest IL-18 level in plasma was found in patients with disease progression, in subjects with lung interstitial changes and in patients with extrapulmonary manifestation of the disease. We observed a positive correlation between plasma IL-18 level and the percentage of BALF lymphocytes (R=0.202, P=0.06) as well as the percentage of activated HLA DR+T cells (R=0.23, P<0.05). There was a negative correlation between the IL-18 level in BALF CCS and the percentage of BALF CD3-positive and CD4-positive lymphocytes (R=-0.27, -0.23, P<0.05).

CONCLUSION

IL-18 may play a significant role in the prolongation of sarcoidosis course. Its estimation may become a good prognostic factor, which should be analyzed together with other factors useful in sarcoidosis monitoring.

The common G-allele of interleukin-18 single-nucleotide polymorphism is a genetic risk factor for atopic asthma. The SAPALDIA Cohort Study

BACKGROUND

IL-18 is a pleiotrophic cytokine involved in both, T-helper type 1 (Th1) and Th2 differentiation. Recently genetic variants in the IL-18 gene have been associated with increased risk of atopy and asthma.

OBJECTIVE

To examine the relationship of a genetic, haplotype-tagging promotor variant -137G/C in the IL-18 gene with atopic asthma in a large, well-characterized and population-based study of adults.

METHODS

Prospective cohort study design was used to collect interview and biological measurement data at two examination time-points 11 years apart. Multivariate logistic regression analysis was used to assess the association of genotype with asthma and atopy.

RESULTS

The G-allele of the IL-18 promotor variant (-137G/C) was associated with a markedly increased risk for the prevalence of physician-diagnosed asthma with concomitant skin reactivity to common allergens. Stratification of the asthma cases by skin reactivity to common allergens revealed an exclusive association of IL-18 -137 G-allele with an increased prevalence of atopic asthma (adjusted odds ratio (OR): 3.63; 95% confidence interval: (1.64-8.02) for GC or GG carriers vs. CC carriers), and no according association with asthma and concomitant negative skin reactivity (adjusted OR: 1.13; 0.66-1.94). The interaction between IL-18 -137G/C genotype and positive skin prick test was statistically significant (P=0.029). None of 74 incident asthma cases with atopy at baseline exhibited the CC genotype.

CONCLUSION

Our results strongly suggest that this variant of the IL-18 gene is an important genetic determinant involved in the development of atopic asthma.

Upregulation of Th1 cytokine profile (IL-12, IL-18) in bronchoalveolar lavage fluid in patients with pulmonary sarcoidosis

Sarcoidosis, a systemic granulomatous disease of unknown etiology, is characterized by a predominantly Th1 cytokine milieu, which is involved in its immunopathogenesis. The role of novel immunologic markers reflecting T cell activity of the sarcoid immunologic response needs to be determined. The present study aims to evaluate the role of the Th1 cytokine pattern by estimating the local and systemic levels of interleukin-12 (IL-12) and IL-18 in bronchoalveolar lavage fluid (BALF), induced sputum, and serum of patients with pulmonary sarcoidosis. We studied prospectively 20 patients (12 women, 8 men) of median age 46 years (range 25-65) with sarcoidosis and 10 normal subjects (5 women, 5 men) of median age 39 years (range 26-60). IL-12 and IL-18 levels were measured using ELISA kits. The IL-12 BALF levels were significantly higher in sarcoidosis patients than in healthy subjects (5.64 +/- 0.21 pg/mL vs. 5.16 +/- 0.15 pg/mL, p < 0.001). In addition, IL-18 levels were significantly increased in BALF samples (47.69 +/- 6.29 pg/mL vs. 16.73 +/- 3.00 pg/mL, p < 0.001). A statistically significant decrease in IL-12 serum levels was detected in the sarcoid population compared with controls (5.77 +/- 0.50 pg/mL vs. 7.87 +/- 2.00 pg/mL, p < 0.001). No significant differences were detected in IL-12 and IL-18 levels between patients and controls in induced sputum samples. Our data suggest a potential role of IL-12 and IL-18 in the local immunologic response in pulmonary sarcoidosis. Further large-scale studies are needed to define the precise role of IL-12 and IL-18 in the immunopathogenesis of this disorder.

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

PURPOSE OF REVIEW

This article examines recent work about the role of TNF-alpha and of selected Th1-related cytokines in asthma with particular emphasis on the therapeutic potential of blocking the biological activity of these mediators.

RECENT FINDINGS

Current research endeavours suggest that asthma pathogenesis is driven by a mixed Th1/Th2 immune response. The contribution of individual Th1-associated and Th2-associated effector mechanisms to this mixed response profile is highly heterogeneous and variations in response patterns seem to be associated with heterogeneity in clinical phenotypes. In particular, it is now acknowledged that allergen-specific Th1 responses appear to be responsible for the pathogenetic effects seen in patients suffering from the more severe chronic forms of the disease. This is important because usual treatments for asthma appear to have limited effects on the more chronic severe forms of the disease and there is a pressing need for the development of new treatment strategies. The failure of topical corticosteroids to reduce TNF-alpha and Th1-derived cytokines to a significant level in asthmatic airways may explain to a certain extent why these drugs appear to have limited effects in the more severe forms of asthma.

SUMMARY

It is likely that therapies blocking TNF-alpha and interfering with Th1-derived cytokines may be a considerable advance in the management of those asthma patients who are particularly resistant to typical treatment modalities.

Antioxidant down-regulates interleukin-18 expression in asthma

An alteration in the balance between a T-helper type 2 cell (Th2) response and a Th1 response may predispose to the development of bronchial asthma. Interleukin-18 (IL-18) has an ability to promote both Th1 and Th2 responses, depending on the surrounding cytokine environment. Reactive oxygen species (ROS) play a crucial role in the pathogenesis of airway inflammation and hyperresponsiveness. Recent studies have demonstrated that antioxidants are able to reduce airway inflammation and hyperreactivity in animal models of asthma. In this study, we used a C57BL/6 mouse model of allergic asthma to examine the effects of antioxidants on the regulation of IL-18 expression. Our present study with ovalbumin-induced murine model of asthma revealed that ROS production in cells from bronchoalveolar lavage fluids was increased and that administration of L-2-oxothiazolidine-4-carboxylic acid or alpha-lipoic acid reduced the increased levels of ROS, the increased expression of IL-18 protein and mRNA, airway inflammation, and bronchial hyperresponsiveness. Our results also showed that antioxidants down-regulated a transcription factor, nuclear factor-kappaB (NF-kappaB), activity. These results indicate that antioxidants may reduce IL-18 expression in asthma by inhibiting the activity of NF-kappaB and suggest that ROS regulate the IL-18 expression.

The effect of 4 weeks treatment with desloratadine (5mg daily) on levels of interleukin (IL)-4, IL-10, IL-18 and TGF beta in patients suffering from seasonal allergic rhinitis

Anti-inflammatory effect of desloratadine (DL), including, but not limited to depression of production of IL-4, IL-6 and IL-8, has been shown in several in vitro experiments but only a few in vivo studies refer to this findings. The purpose of our study was to evaluate the influence of DL on levels of IL-4, IL-10, IL-18 and TGF-beta in sera of patients with seasonal allergic rhinitis (SAR). Sixty-nine subjects suffering from SAR with hypersensitivity to grass pollen were included into the evaluation of clinical efficacy of DL (5mg once daily). None of them was taking any H(1) receptor antagonist during the pollen season before inclusion into the study. Samples of peripheral blood were taken before and after 4 weeks of treatment. Levels of cytokines were determined using the ELISA method. The mean level of IL-4 was 0.212+/-0.07pg/ml before and 0.221+/-0.1pg/ml after the treatment (p=0.52); IL-10 5.13+/-3.14 and 4.71+/-0.88 (p=0.69); IL-18 54.45+/-26.09 and 44.80+/-22.42 (p=0.48); TGF beta 949.17+/-401.5 and 955.7+/-391.2 (p=0.97)pg/ml before and after the treatment, respectively. Unless in vitro DL demonstrates not only anti-allergic but also anti-inflammatory activities data from this in vivo study in a group of patients suffering from SAR do not support previous pre-clinical findings.

Targeting memory Th2 cells for the treatment of allergic asthma

Th2 memory cells play an important role in the pathogenesis of allergic asthma. Evidence from patients and experimental models indicates that memory Th2 cells reside in the lungs during disease remission and, upon allergen exposure, become activated effectors involved in disease exacerbation. The inhibition of memory Th2 cells or their effector functions in allergic asthma influence disease progression, suggesting their importance as therapeutic targets. They are allergen specific and can potentially be suppressed or eliminated using this specificity. They have distinct activation, differentiation, cell surface phenotype, migration capacity, and effector functions that can be targeted singularly or in combination. Furthermore, memory Th2 cells residing in the lungs can be treated locally. Capitalizing on these unique attributes is important for drug development for allergic asthma. The aim of this review is to present an overview of therapeutic strategies targeting Th2 memory cells in allergic asthma, emphasizing Th2 generation, differentiation, activation, migration, effector function, and survival.

Deficiency of a subset of T-cells with immunoregulatory properties in sarcoidosis

BACKGROUND

Sarcoidosis is a multisystem disorder that predominantly involves the lungs, characterised by a T-helper 1 (Th1) biased CD4-positive T-cell response and granuloma formation, for which the explanation is unknown. A newly identified subset of T-cells with immunoregulatory functions, CD1d-restricted natural-killer T (NKT) cells, has been shown to protect against disorders with increased CD4-positive Th1 responses in animals. We explored whether abnormalities in these cells are implicated in the pathogenesis of sarcoidosis.

METHODS

We generated fluorescence-labelled CD1d-tetrameric complexes and used them, with monoclonal antibodies to Valpha24 and Vbeta11 T-cell receptor, to assess the frequency of CD1d-restricted NKT cells in the peripheral blood of 60 patients with histologically proven sarcoidosis (16 with Lofgren's syndrome) and 60 healthy controls. Lung lymphocytes were also analysed in 16 of the patients with sarcoidosis.

FINDINGS

CD1d-restricted NKT cells were absent or greatly reduced in peripheral blood from all patients with sarcoidosis, except those with Lofgren's syndrome (median proportion of lymphocytes 0.01% [IQR 0-0.03] vs 0.06% [0.03-0.12] in controls; p=0.0004). The deficiency was found in both acute and resolved disease and was unrelated to systemic corticosteroid therapy. There was no difference in the proportion of CD1d-restricted NKT cells between peripheral blood and lungs in patients, suggesting that the peripheral-blood deficiency is not due to sequestration of these cells in the lungs. The NKT cells were not observed in mediastinal lymph nodes or granulomatous lesions. CD1d expression on antigen-presenting cells of patients was normal, thus the deficiency of CD1d-restricted NKT cells is not explained by abnormal CD1d expression.

INTERPRETATION

Loss of immunoregulation by CD1d-restricted NKT cells could explain the amplified and persistent T-cell activity that characterises sarcoidosis.

RELEVANCE TO PRACTICE

Our findings give new insight into the pathogenesis of sarcoidosis and draw attention to a potential target for therapeutic modulation in sarcoidosis.

Interleukin-18 levels in induced sputum are reduced in asthmatic and normal smokers

BACKGROUND

IL-18 is a cytokine which is known to have an important role in the development of a Th1 lymphocyte response. As such, it may have a regulatory role in asthma by modifying Th2 lymphocyte responses. Cigarette smoking may amplify the airway inflammation associated with asthma.

OBJECTIVE

This study investigated if IL-18 could be detected in induced sputum from asthmatics and normal subjects and if smoking altered IL-18 levels.

METHODS

Induced sputum was obtained from asthmatic (31 smokers, 35 non-smokers) and normal (20 smokers, 20 non-smokers) subjects. All smokers had a smoking history of > or =15 pack years. IL-18 levels in sputum supernatant were measured by ELISA. IL-18 mRNA expression and cellular localization were assessed by quantitative PCR and immunocytochemistry, respectively.

RESULTS

Smoking was associated with a significant reduction in IL-18 levels (median (interquartile range) - smokers 20 (0-102) pg/mL vs. non-smokers 358 (50-876) pg/mL, P<0.001). This was more pronounced in asthmatics (smokers, 47 (40-64) pg/mL vs. non-smokers, 530 (30-1484) pg/mL; P<0.001) than in normal subjects (smokers, 25 (0-78) pg/mL vs. non-smokers, 247 (50-656) pg/mL; P<0.01). Within each of the smoking and non-smoking groups there was no significant difference in IL-18 levels between asthmatic and normal subjects. There was no correlation between sputum IL-18 levels and any specific cell type in the sputum samples nor serum IgE levels. IL-18 mRNA expression was reduced in asthmatic smokers compared with non-smokers. IL-18 production was localized to sputum macrophages by immunocytochemistry.

CONCLUSIONS

IL-18 is detectable in induced sputum samples from both asthmatic and normal subjects. Cigarette smoking significantly reduces sputum IL-18 levels. This effect is more pronounced in asthmatics than in normal subjects.

IL-12p40 and IL-18 Modulate Inflammatory and Immune Responses to Respiratory Syncytial Virus Infection

Respiratory syncytial virus-induced bronchiolitis has been linked to the development of allergy and atopic asthma. IL-12 and possibly IL-18 are central mediators orchestrating Th1 and/or Th2 immune responses to infection. To determine a possible role for IL-12 in regulating the immune response to acute respiratory syncytial virus infection, IL-12p40 gene-targeted (IL-12p40-/-) and wild-type mice were intratracheally infected with respiratory syncytial virus, and lung inflammatory and immune responses were assessed. Lung inflammation and mucus production were increased in the airways of IL-12p40-/- mice as compared with those of wild-type mice, concurrent with increased levels of the Th2 effector cytokines IL-5 and IL-13. Respiratory syncytial virus clearance and levels of Th1 effector cytokine IFN-gamma were not altered. Interestingly, IL-18, another mediator of IFN-gamma production, was significantly increased in the lungs of IL-12p40-/- mice early during the course of infection. Abrogation of IL-18-mediated signaling in IL-12p40-/- mice further enhanced Th2 immune response and mucus production in the airways during respiratory syncytial virus infection but failed to modulate IFN-gamma production or viral clearance. These findings implicate a role for IL-12 and IL-18 in modulating respiratory syncytial virus-induced airway inflammation distinct from that of viral clearance.

Elevated interleukin-18 levels in bronchoalveolar lavage fluid of patients with eosinophilic pneumonia

BACKGROUND

Interleukin (IL)-18 can induce Th2 cytokine production particularly in collaboration with IL-2. Accumulation of Th2 cells and increased levels of Th2 cytokines are found in bronchoalveolar lavage fluid (BALF) from patients with eosinophilic pneumonia (EP). To evaluate the role of IL-18 in the pathogenesis of EP, we measured the concentration of IL-2, IL-12, IL-18, and Th2 cytokines in BALF from patients with EP.

METHODS

The concentrations of interferon (IFN)-gamma, IL-2, IL-5, IL-10, IL-12, IL-13, and IL-18 in BALF were measured in patients with idiopathic acute eosinophilic pneumonia (AEP), with idiopathic chronic eosinophilic pneumonia (CEP), with sarcoidosis and healthy volunteers (HV).

RESULTS

The BALF concentrations of Th2 cytokines, IL-5, IL-10, and IL-13, were higher in patients with EP than in sarcoidosis and control. The IL-2 level in BALF was higher in EP than in sarcoidosis and control. The IL-18 and IL-12 (p40 + p70) levels were higher in patients with EP than sarcoidosis, while the level of IL-12 (p70) was below the detection limit in patients with EP. There was a significant correlation between IL-2 level and both IL-5 and IL-13 in BALF of patients with EP.

CONCLUSIONS

Our findings suggest that IL-18 may contribute to Th2 cytokine-dominant responses in patients with EP in collaboration with IL-2.

Association study of polymorphisms within interleukin-18 in juvenile idiopathic arthritis and bronchial asthma

BACKGROUND

Interleukin-18 (IL-18) plays an important role in the regulation of TH1 as well as TH2 immunologic responses and thus in the development of chronic inflammatory diseases. Positive association studies of polymorphisms in IL-18 with different diseases have underlined the involvement of IL-18 in the pathogenetics processes. Our interest was to test polymorphisms of IL-18 for association with a typical TH1-mediated disease--juvenile idiopathic arthritis--and the TH2-mediated disease bronchial asthma in Caucasian children.

METHODS

We genotyped five polymorphisms that were in association with chronic inflammatory diseases (-607C, -137C, 113G, 127T, and -133G). This was performed by restriction fragment length polymorphism in populations of asthmatic children, control individuals, and children with antinuclear antibodies (ANA)-positive juvenile idiopathic arthritis. Statistical analysis was performed by the Armitage trend test; haplotypes were calculated by the Arlequine program.

RESULTS

No significant association was found between any single nucleotide polymorphism or any haplotype and bronchial asthma or ANA-positive juvenile idiopathic arthritis.

CONCLUSION

We conclude that the effect of IL-18 in the immunologic context of diseases like bronchial asthma or juvenile arthritis might be too complex to be reflected in a simple one-way association study. Furthermore, the polymorphisms under investigation might be nonfunctional.

Increased expression of allergen-induced in vitro interleukin-10 and interleukin-18 mRNA in peripheral blood mononuclear cells of allergic rhinitis patients after specific immunotherapy

BACKGROUND

During specific pollen immunotherapy (SIT) there is a local mucosal shift from Th2- to Th1- type cytokine predominance, with IL-12 having a major role in this shift. IL-10-induced tolerance is supposed to be a key phenomenon in venom immunotherapy (VIT). However, the role of Th1-promoting cytokines, on the one hand, and the role of regulatory cytokines, on the other hand, have not been studied in parallel during SIT.

OBJECTIVE

This study was undertaken to analyse the allergen-induced in vitro mRNA expression of Th1-type effector cytokine IL-18 and regulatory cytokines IL-10 and TGF-beta during SIT in peripheral blood mononuclear cells (PBMC) of allergic rhinitis (AR) patients.

METHODS

Thirty patients with AR undergoing pollen SIT and 10 patients with AR who were not treated with SIT were included in the study. The symptoms and medications were registered post-seasonally before the beginning of SIT and after 1 year of therapy. PBMC samples were collected and stimulated with pollen allergen extract prior to the treatment, at the maintenance phase in 12 patients and after 1 year of the treatment. The cytokine mRNA expression was assessed using kinetic real-time RT-PCR (TaqMan).

RESULTS

There was a clear increase in the treated AR patients, in comparison with untreated AR patients, in the expression of both IL-10 (mean change from baseline (SEM): 3.1 (0.8) vs. -0.3 (0.3), P<0.002, Mann-Whitney U-test) and IL-18 (2.7 (0.9) vs. -0.2 (0.6), P<0.03) mRNA after 1 year. The clearest increase in IL-10 mRNA expression was seen in patients who did not benefit at all (6.0 (2.3), P<0.001 vs. untreated) and the least increase in patients that had the greatest reduction of symptoms (0.8 (0.6), n.s. vs. untreated) at 1 year. The clearest increase in IL-18 mRNA expression was seen in patients with moderate outcome (3.4 (1.6), P<0.04 vs. untreated). In intermediate samples, taken when the maintenance dose was reached, the peak expression of allergen-induced IL-10 mRNA was associated with the most favourable outcome of SIT (P=0.01, Fisher exact test). A similar trend was seen in IL-18 mRNA expression.

CONCLUSIONS

The results suggest that an early and transient increase in allergen-specific IL-10 and IL-18 mRNA expression in PBMC is essential for the therapeutic outcome after 1 year of SIT.

Biomarkers in drug discovery and development: from target identification through drug marketing

Biomarkers of disease play an important role in medicine and have begun to assume a greater role in drug discovery and development. The challenge for biomarkers is to allow earlier, more robust drug safety and efficacy measurements. Their role in drug development will continue to grow for the foreseeable future. For biomarkers to assume their rightful role, greater understanding of the mechanism of disease progression and therapeutic intervention is needed. In addition, greater understanding of the requirements for biomarker selection and validation, biomarker assay method validation and application, and clinical endpoint validation and application is needed. Biomarkers need to be taken into account while the therapeutic target is still being identified and the concept is being formulated. Biomarkers need to be incorporated into a continuous cycle that takes what is learned from the discovery and development of one series of biomarkers and translates it into the next series of biomarkers. Optimum biomarker development and application will require a team approach because of the multifaceted nature of biomarker selection, validation, and application, using such techniques as pharmacoepidemiology, pharmacogenetics, pharmacogenomics, and functional proteomics; bioanalytical method development and validation; disease process and therapeutic intervention assessments; and pharmacokinetic/pharmacodynamic modeling and simulation to improve and refine drug development. The potential for biomarkers in medicine and drug development will be limited by the least effective component of the processes. The team approach will minimize the potential for the least effective component to be fatal to the rest of the process. As scientific/regulatory foundations for biomarkers in medicine and drug development begin to be established, successes and applications will need to be effectively communicated with all of the stakeholders, including not only internal and external drug developers and regulators but also the medical community, to ensure that biomarkers are totally integrated into drug discovery and development as well as the practice of medicine.

The role of T lymphocytes in the pathogenesis of asthma

There is considerable evidence to support a role for T cells in asthma, particularly the involvement of T(H)2 cells both in atopic allergic asthma and in nonatopic and occupational asthma. There might also be a minor contribution from T(C)2 CD8+ T cells. Several T(H)2 cytokines have the potential to modulate airway inflammation, particularly IL-13, which induces airway hyperresponsiveness independently of IgE and eosinophilia in animal models. The identification of transcription factors controlling T(H)1 and T(H)2 development further support the T(H)2 hypothesis because GATA3 is overexpressed and T-bet is underexpressed in the asthmatic airway. Specific T cell directed immunotherapy might allow induction, modulation, or both of T-cell responses, and elucidation of the mechanisms of regulatory T cells might allow further optimization of immunotherapy. Recent advances in our understanding of dendritic cell function in directing T-cell responses might uncover further therapeutic targets. The efficacy of cyclosporin A and anti-CD4 treatment in patients with chronic severe asthma argues for continued T-cell involvement, but whether remodeling contributes to pathology inaccessible to anti-inflammatory treatment or T-cell immunotherapy will be an important future question.

Interleukin-18

Interleukin-18 (IL-18), a recently described member of the IL-1 cytokine superfamily, is now recognized as an important regulator of innate and acquired immune responses. IL-18 is expressed at sites of chronic inflammation, in autoimmune diseases, in a variety of cancers, and in the context of numerous infectious diseases. This short review will describe the basic biology of IL-18 and thereafter address its potential effector and regulatory role in several human disease states including autoimmunity and infection. IL-18, previously known as interferon-gamma (IFN-gamma)-inducing factor, was identified as an endotoxin-induced serum factor that stimulated IFN-gamma production by murine splenocytes [(1) ]. IL-18 was cloned from a murine liver cell cDNA library generated from animals primed with heat-killed Propionibacterium acnes and subsequently challenged with lipopolysaccharide [(2) ]. Nucleotide sequencing of murine IL-18 predicted a precursor polypeptide of 192 amino acids lacking a conventional signal peptide and a mature protein of 157 amino acids. Subsequent cloning of human IL-18 cDNA revealed 65% homology with murine IL-18 [(3) ] and showed that both contain an unusual leader sequence consisting of 35 amino acids at their N terminus.