Satoko Takei

Interleukin-18 production and pulmonary function in COPD

Interleukin (IL)-18 production and pulmonary function were evaluated in patients with chronic obstructive pulmonary disease (COPD) in order to determine the role of IL-18 in COPD. Immunohistochemical techniques were used to examine IL-18 production in the lungs of patients with very severe COPD (Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage IV, n = 16), smokers (n = 27) and nonsmokers (n = 23). Serum cytokine levels and pulmonary function were analysed in patients with GOLD stage I–IV COPD (n = 62), smokers (n = 34) and nonsmokers (n = 47). Persistent and severe small airway inflammation was observed in the lungs of ex-smokers with very severe COPD. IL-18 proteins were strongly expressed in alveolar macrophages, CD8+ T-cells, and both the bronchiolar and alveolar epithelia in the lungs of COPD patients. Serum levels of IL-18 in COPD patients and smokers were significantly higher than those in nonsmokers. Moreover, serum levels of IL-18 in patients with GOLD stage III and IV COPD were significantly higher than in smokers and nonsmokers. There was a significant negative correlation between serum IL-18 level and the predicted forced expiratory volume in one second in patients with COPD. In contrast, serum levels of IL-4, IL-13 and interferon-γ were not significantly increased in any of the three groups. In conclusion, overproduction of interleukin-18 in the lungs may be involved in the pathogenesis of chronic obstructive pulmonary disease.

Redox-Regulated Mechanisms in Asthma

Homeostasis of the reduction-oxidation (redox) state is critical to protection from oxidative stress in the lungs. Therefore, the lungs have high levels of antioxidants, including glutathione, heme oxygenase, and superoxide dismutase. The numbers of inflammatory cells -- particularly eosinophils -- are increased in the airways of asthma patients, and these pulmonary inflammatory cells release large amounts of harmful reactive oxygen species and reactive nitrogen species. Human thioredoxin 1 (TRX1) is a redox-active protein of approximately 12 kDa that contains a (32)Cys-Gly-Pro-(35)Cys sequence necessary for its activity. The strong reducing activity of the sequence results from the cysteine residues acting as proton donors and cleaving disulfide (S-S) bonds in the target protein. Endogenous or exogenous TRX1 or both protect the lungs against ischemia-reperfusion injury, influenza infection, bleomycin-induced injury, or lethal pulmonary inflammation caused by interleukin-2 and interleukin-18. We showed that exogenous TRX1 inhibits airway hyperresponsiveness and pulmonary inflammation accompanied by eosinophilia in mouse models of asthma. Recently, we reported that exogenous TRX1 improves established airway remodeling in a prolonged antigen-exposure mouse asthma model. Exogenous and endogenous TRX1 also prevents the development of airway remodeling. Here, we discuss the role and clinical benefits of TRX1 in asthma.

Overexpression of Chitinase 3-Like 1/YKL-40 in Lung-Specific IL-18-Transgenic Mice, Smokers and COPD

We analyzed the lung mRNA expression profiles of a murine model of COPD developed using a lung-specific IL-18-transgenic mouse. In this transgenic mouse, the expression of 608 genes was found to vary more than 2-fold in comparison with control WT mice, and was clustered into 4 groups. The expression of 140 genes was constitutively increased at all ages, 215 genes increased gradually with aging, 171 genes decreased gradually with aging, and 82 genes decreased temporarily at 9 weeks of age. Interestingly, the levels of mRNA for the chitinase-related genes chitinase 3-like 1 (Chi3l1), Chi3l3, and acidic mammalian chitinase (AMCase) were significantly higher in the lungs of transgenic mice than in control mice. The level of Chi3l1 protein increased significantly with aging in the lungs and sera of IL-18 transgenic, but not WT mice. Previous studies have suggested Chi3l3 and AMCase are IL-13-driven chitinase-like proteins. However, IL-13 gene deletion did not reduce the level of Chi3l1 protein in the lungs of IL-18 transgenic mice. Based on our murine model gene expression data, we analyzed the protein level of YKL-40, the human homolog of Chi3l1, in sera of smokers and COPD patients. Sixteen COPD patients had undergone high resolution computed tomography (HRCT) examination. Emphysema was assessed by using a density mask with a cutoff of −950 Hounsfield units to calculate the low-attenuation area percentage (LAA%). We observed significantly higher serum levels in samples from 28 smokers and 45 COPD patients compared to 30 non-smokers. In COPD patients, there was a significant negative correlation between serum level of YKL-40 and %FEV1. Moreover, there was a significant positive correlation between the serum levels of YKL-40 and LAA% in COPD patients. Thus our results suggest that chitinase-related genes may play an important role in establishing pulmonary inflammation and emphysematous changes in smokers and COPD patients.

Soluble interleukin-18 receptor complex is a novel biomarker in rheumatoid arthritis

IntroductionThere has been no report in the literature of a soluble form of interleukin (IL)-18 receptor α (IL-18Rα). In this study, we evaluated the levels and characteristics of soluble IL-18Rα (sIL-18Rα) in the sera of patients with rheumatoid arthritis (RA) and compared these results to control populations.MethodsThe sIL-18Rα complex was isolated from pooled human blood serum using an anti-IL-18Rα monoclonal antibody affinity column. The purified sIL-18Rα was then examined using Western blot analysis and used in experiments to evaluate the effects on an IL-18-responsive natural killer (NK) human cell line, NK0. An enzyme-linked immunosorbent assay was developed, and sera from 145 patients with RA, 6 patients with adult-onset Stills disease, 31 patients with osteoarthritis (OA), 39 patients with systemic lupus erythematosus (SLE) and 67 controls were tested, along with levels of immunoglobulin M, rheumatoid factor, anticyclic citrullinated peptide antibody, IL-18, IL-13 and interferon (IFN)-γ. Area under the receiver operating characteristic curve (ROC-AUC) analysis was used to evaluate the diagnostic utility of the sIL-18Rα complex.ResultsThe isolated sIL-18Rα complex can be associated with IL-18 and the soluble form of the IL-18Rβ chain. The sIL-18Rα complex bound to the surface to the NK0 cell line, antagonized the stimulatory effects of IL-18 and IL-2 on the NK0 cell line and inhibited IFN-γ production by the cells. The serum levels of sIL-18Rα complex in RA (186.0 ± 33.5 ng/mL, n = 145) and adult-onset Stills disease (98.2 ± 8.9 ng/mL, n = 6) were significantly (P < 0.001) higher than those in the healthy controls (52.3 ± 8.5 ng/mL, n = 67), OA (38.6 ± 5.4 ng/mL, n = 31), SLE (44.6 ± 3.2 ng/mL, n = 39). The serum level of sIL-18Rα complex was not significantly different between RA and adult-onset Stills disease patients. The serum levels of IL-18, IL-13 and IFN-γ in the RA patients were significantly (P < 0.01) higher than in OA and SLE patients as well as healthy controls. ROC-AUC analysis of the serum concentration of sIL-18Rα indicated that it was significantly diagnostic of RA. Moreover, a tumor necrosis factor inhibitor, etanercept, significantly (P < 0.0001) decreased levels of sIL-18Rα in the sera of 29 RA patients 6 months after treatment.ConclusionsThe sIL-18Rα complex could be a potentially useful biomarker for the diagnosis of RA.

Endogenous and Exogenous Thioredoxin 1 Prevents Goblet Cell Hyperplasia in a Chronic Antigen Exposure Asthma Model

BACKGROUND Goblet cell hyperplasia with mucus hypersecretion contribute to increased morbidity and mortality in bronchial asthma. We have reported that thioredoxin 1 (TRX1), a redox (reduction/oxidation)-active protein acting as a strong antioxidant, inhibits pulmonary eosinophilic inflammation and production of chemokines and Th2 cytokines in the lungs, thus decreasing airway hyperresponsiveness (AHR) and airway remodeling in mouse asthma models. In the present study, we investigated whether endogenous or exogenous TRX1 inhibits goblet cell hyperplasia in a mouse asthma model involving chronic exposure to antigen. METHODS We used wild-type Balb/c mice and Balb/c background human TRX1-transgenic mice constitutively overproducing human TRX1 protein in the lungs. Mice were sensitized 7 times (days 0 to 12) and then challenged 9 times with ovalbumin (OVA) (days 19 to 45). Every second day from days 18 to 44 (14 times) or days 35 to 45 (6 times), Balb/c mice were treated with 40 microg recombinant human TRX1 (rhTRX1) protein. Goblet cells in the lungs were examined quantitatively on day 34 or 45. RESULTS Goblet cell hyperplasia was significantly prevented in TRX1-transgenic mice in comparison with TRX1 transgene-negative mice. rhTRX1 administration during OVA challenge (days 18 to 44) significantly inhibited goblet cell hyperplasia in OVA-sensitized and -challenged wild-type mice. Moreover, rhTRX1 administration after the establishment of goblet cell hyperplasia (days 35 to 45) also significantly ameliorated goblet cell hyperplasia in OVA-sensitized and -challenged wild-type mice. CONCLUSIONS Our results suggest that TRX1 prevents the development of goblet cell hyperplasia, and also ameliorates established goblet cell hyperplasia.