Takumi Kiwamoto

Nrf2‐deficient mice are highly susceptible to cigarette smoke‐induced emphysema

Inflammation, protease/anti‐protease imbalance and oxidative stress play important roles in the pathogenesis of emphysema. Nrf2 counteracts oxidative tissue damage and inflammation through transcriptional activation via the anti‐oxidant responsive element (ARE). To clarify the protective role of Nrf2 in the development of emphysema, the susceptibility of Nrf2‐knockout mice to cigarette smoke (CS)‐induced emphysema was examined. In Nrf2‐knockout mice, emphysema was first observed at 8 weeks and exacerbated by 16 weeks following CS‐exposure, whereas no pathological abnormalities were observed in wild‐type mice. Neutrophilic lung inflammation and permeability lung damage were significantly enhanced in Nrf2‐knockout mice 8 weeks after CS‐exposure. Importantly, neutrophil elastase activity in bronchoalveolar lavage fluids was markedly higher in Nrf2‐knockout mice preceding the pronounced neutrophil accumulation. The expression of secretory leukoprotease inhibitor, a potent inhibitor of neutrophil elastase, was inducible in wild‐type, but not in Nrf2‐knockout mice. This protease/anti‐protease imbalance, together with the lack of inducible expression of ARE‐regulated anti‐oxidant/anti‐inflammatory genes, may explain the predisposition of Nrf2‐knockout mice to neutrophilic inflammation. Indeed, specific activators of Nrf2 induced the expression of the SLPI gene in macrophages. These results indicate that Nrf2 protects against the development of emphysema by regulating not only the oxidant/anti‐oxidant balance, but also inflammation and the protease/anti‐protease balance.

Transcription Factor Nrf2 Plays a Pivotal Role in Protection against Elastase-Induced Pulmonary Inflammation and Emphysema

Emphysema is one of the major pathological abnormalities associated with chronic obstructive pulmonary disease. The protease/antiprotease imbalance and inflammation resulting from oxidative stress have been attributed to the pathogenesis of emphysema. Nrf2 is believed to protect against oxidative tissue damage through the transcriptional activation of a battery of antioxidant enzymes. In this study, we investigated the protective role of Nrf2 in the development of emphysema using elastase-induced emphysema as our model system. We found that elastase-provoked emphysema was markedly exacerbated in Nrf2-knockout (KO) mice compared with wild-type mice. The severity of emphysema in Nrf2-KO mice correlated intimately with the degree of lung inflammation in the initial stage of elastase treatment. The highly inducible expression of antioxidant and antiprotease genes observed in wild-type alveolar macrophages was significantly attenuated in the lungs of Nrf2-KO mice. Interestingly, transplantation of wild-type bone marrow cells into Nrf2-KO mice retarded the development of initial lung inflammation and subsequent emphysema, and this improvement correlated well with the appearance of macrophages expressing Nrf2-regulated antiprotease and antioxidant genes. Thus, Nrf2 appears to exert its protective effects through the transcriptional activation of antiprotease and antioxidant genes in alveolar macrophages.

Suppression of eosinophilic airway inflammation by treatment with α-galactosylceramide

To clarify the essential role of NKT cells in allergy, we investigated the contribution of NKT cells to the pathogenesis of eosinophilic airway inflammation using α‐galactosylceramide (α‐GalCer), a selective ligand for NKT cells. Although continuous administration of α‐GalCer during ovalbumin (OVA) sensitization increased OVA‐specific IgE levels and worsened eosinophil inflammation, a single administration of α‐GalCer at the time of OVA challenge completely prevented eosinophilic infiltration in wild‐type mice. This inhibitory effect of α‐GalCer was associated with a decrease in airway hyperresponsiveness, an increase in IFN‐γ, and decreases in IL‐4, IL‐5 and IL‐13 levels in the bronchoalveolar lavage fluids. Analysis of lung lymphocytes revealed that production of IFN‐γ increased in NK cells, but not in T or NKT cells, following α‐GalCer administration. Induction of vascular cell adhesion molecule‐1 in the lungs of wild‐type mice was also significantly attenuated by treatment with α‐GalCer. These effects of α‐GalCer were abrogated in Jα281–/– mice, which lack NKT cells, and in wild‐type mice treated with anti‐IFN‐γ Ab. Hence, our data indicate that α‐GalCer suppresses allergen‐induced eosinophilic airway inflammation, possibly by inducing a Th1 bias that results in inhibition of eosinophil adhesion to the lung vessels.

Blockade of cysteinyl leukotriene-1 receptors suppresses airway remodelling in mice overexpressing GATA-3

Background We demonstrated previously that GATA‐3 overexpression markedly enhanced allergen‐induced airway inflammation and airway remodelling, including subepithelial fibrosis, and smooth muscle cell hyperplasia, in transgenic mice.

Promoter activity of human tissue inhibitor of metalloproteinase 2 gene with novel single nucleotide polymorphisms

Objective:  The single nucleotide polymorphism (SNP) −418G > C in the TIMP2 gene promoter region has been shown to be associated with in chronic obstructive pulmonary disease (COPD). The purpose of this study was to search for novel single nucleotide polymorphism (SNP) in the TIMP2 promoter region around the −418G > C locus, and to investigate whether any of these SNP, including −418G > C, had an influence on TIMP2 transcription activity.

Effect of Inhaled Steroids on Increased Collagen Synthesis in Asthma

Background: We previously reported that sputum levels of procollagen type I C-terminal peptide (PICP), a marker of ongoing collagen type I deposition, are increased in proportion to airway inflammation in asthma patients. Objectives: In this study, we examined the effect of inhaled corticosteroids on increased collagen synthesis in step 2–4 asthmatics. Methods: We compared the sputum PICP concentrations of 25 steroid-naive asthmatics, 25 normal volunteers, and 10 subjects with chronic obstructive pulmonary disease. Asthma subjects were also instructed to start fluticasone propionate treatment, and the percentage of forced expiratory volume in 1 s, sputum eosinophil counts, sputum PICP concentrations, and sputum transforming growth factor-β-positive cell counts before treatment were compared with those 1 month after treatment. Results: Sputum PICP concentrations were detected in the following order: asthma group ≧ chronic obstructive pulmonary disease group > control group. Asthma patients showing high sputum PICP belonged to step 4, although there was no correlation between sputum PICP and asthma severity. Treatment with fluticasone propionate not only significantly improved the mean percentage of forced expiratory volume in 1 s (from 66.7 to 87.2%), but also decreased the mean sputum eosinophil counts (from 13.4 to 5.8%), the mean sputum PICP concentrations (from 30.8 to 10.2 ng/ml), and the mean sputum tumor growth factor-β-positive cells (from 11.3 to 2.8%). Nevertheless, a significant difference in sputum PICP concentrations was still observed between the control group and the steroid-treated asthma group. Conclusions: The present results suggest that inhaled corticosteroid treatment might reduce sputum indexes of collagen metabolism and eosinophilic inflammation in asthma patients.

Landiolol hydrochloride ameliorates acute lung injury in a rat model of early sepsis through the suppression of elevated levels of pulmonary endothelin-1

Among the dysfunctions and pathologies associated with sepsis, the underlying molecular mechanisms of sepsis-induced acute lung injury (ALI) are poorly understood. Endothelin (ET)-1, a potent vasoconstrictor and pro-inflammatory peptide, is known to be involved in the pathogenesis of ALI in a rat model of sepsis. Here, we investigated whether landiolol hydrochloride, an ultra-short-acting β-blocker, plays a crucial role in ameliorating and attenuating LPS-induced ALI through modulation of the ET-1 system. Male Wistar rats at 8weeks of age were administered with either saline or lipopolysaccharide (LPS) for three hours (3h) and some of the LPS-administered rats were continuously treated with landiolol for 3h. ALI was induced by LPS, including levels of both circulatory and pulmonary TNF-α and IL-6 but [PaO2] was significantly decreased. LPS also induced a significant increase in levels of pulmonary ET-1 and ET-A receptor, but levels of ET-B receptor, which has vasodilating effects, were remarkably diminished. Further, LPS administration upregulated the pulmonary expression of HIF-1α. Finally, the treatment of LPS-administered rats with landiolol for 3h ameliorated and prevented ALI, normalized the altered levels of pulmonary ET-1 and ET-A receptors. Landiolol also induced significant down-regulation of ET-B receptor in lung tissues in the early hours (phase) of sepsis. However, Landiolol treatment had no effect on the up-regulated inflammatory mediators (TNF-α, IL-6) in both plasma and lung tissues during sepsis, and expression of pulmonary HIF-1α also remained unchanged after landiolol treatment. Collectively, these data led us to conclude that landiolol may ameliorate sepsis-induced ALI via the pulmonary ET system.

Sulforaphane ameliorates steroid insensitivity through an Nrf2-dependent pathway in cigarette smoke-exposed asthmatic mice

&NA; Oxidative stress induced by cigarette smoke and other environmental pollutants contributes to refractory asthma. To better understand the role of smoking in asthma, we investigated the effects of cigarette smoke on allergic airway responses in mice and examined expression of nuclear factor‐E2‐related factor‐2 (Nrf2) and its downstream factors, because Nrf2 is known to play a pivotal role in antioxidant responses. OVA‐sensitized and challenged BALB/c mice were exposed to cigarette smoke and then treated with dexamethasone, sulforaphane (an activator of Nrf2), or their combination. Upon exposure to cigarette smoke, Nrf2 and associated transcripts were upregulated in response to oxidative stress, and asthmatic responses were steroid resistant. In OVA‐sensitized and challenged mice exposed to cigarette smoke and treated with sulforaphane, Nrf2‐mediated antioxidant responses were upregulated to a greater extent, and steroid sensitivity of asthmatic responses was restored. Moreover, the expression and activity of histone deacetylase 2 (HDAC2), a key regulator of steroid responsiveness, was reduced in mice exposed to cigarette smoke, but restored by sulforaphane treatment. No effects of sulforaphane were observed in Nrf2‐deficient mice. These findings indicate that cigarette smoke induces steroid unresponsiveness in asthmatic airways, and that sulforaphane restores steroid sensitivity via upregulation of Nrf2 and enhancement of HDAC2 expression and activity. Thus, Nrf2 may serve as a potential molecular target for cigarette smoke‐related refractory asthma resistant to steroid therapy. Graphical abstract Figure. No caption available. HighlightsCigarette smoking induces steroid insensitivity and raises refractory asthma risk.Smoke exposure‐induced oxidant/antioxidant imbalance inhibits HDAC2 activity.Oxidant/antioxidant imbalance contributes to steroid resistance in asthmatic mice.HDAC2 activity is enhanced by sulforaphane via Nrf2 activation.Nrf2 may be a target for restoring steroid sensitivity in smoking‐related asthma.

Notch signaling regulates cell density-dependent apoptosis of NIH 3T3 through an IL-6/STAT3 dependent mechanism

Apoptosis is a physiological process that plays a critical maintenance role in cellular homeostasis. Previous reports have demonstrated that cells undergo apoptosis in a cell density-dependent manner, which is regulated, in part, by signal transducers and activators of transcription (STAT) 3. The molecular mechanisms regulating cell density-dependent apoptosis, however, has not been thoroughly investigated to date. Since Notch signaling is activated via direct cell-to-cell contact and plays a pivotal role in cell fate decisions, we examined the role of Notch signaling in cell density-dependent apoptosis of mouse embryonic fibroblasts NIH 3T3 cells. With the increase in cell density, IL-6 expression was induced, which was necessary for STAT3 activation as well as apoptosis regulation. Notch signaling was also activated in a cell-density dependent manner. Blocking Notch signaling either through siRNA-mediated targeting of Jagged1 expression or γ-secretase inhibitor treatment demonstrated that Notch signaling activation was necessary for IL-6 induction. Constitutive activation of Notch signaling via the overexpression of Notch1 intracellular domain was sufficient for the induction of IL-6, which was mediated via direct transcriptional activation. Taken together, our study indicates that Notch signaling regulates cell density-dependent apoptosis through IL-6/STAT3-dependent mechanism. Consequently, Notch signaling might represent a novel therapeutic target in diseases characterized by dysregulated apoptosis.

Paraneoplastic limbic encephalitis with late‑onset magnetic resonance imaging findings: A case report

Paraneoplastic limbic encephalitis (PLE), a paraneoplastic neurological syndrome (PNS), is a rare nervous system disorder that results from the indirect effects of tumors and is commonly associated with small-cell lung cancer (SCLC). Previous studies have reported that magnetic resonance imaging (MRI) may be useful for diagnosing LE. Temporal lobe abnormalities are observed using T2-weighted and fluid-attenuated inversion recovery sequences; however, such abnormalities are detected in only 60% of patients with PLE. The present study describes a case of PLE associated with SCLC, in which LE was observed using MRI 26 days after the first convulsive seizure. Although the serum and cerebrospinal fluid analyses for onconeural antibodies were negative, the findings of this case indicate that PLE should be considered in the differential diagnosis, and that repeated brain MRI may be more helpful for diagnosis, as the brain MRI findings may be normal during the early stages of PLE.